Nuclear Tracks in Solids (Abstracts)

c'/vniH22V- -•'>'•'S INIS-mf—13731 ONAL IFERENCE ON NUCLEAR TRACKS IN SOLIDS (ABSTRACTS)

7-11 September, 1992 Organized by China Institute of Atomic Energy (CIAE)

Initiated by International Nuclear Track Society (INTS) Chinese Nuclear Society (CNS) Chinese Nuclear Physics Society (CNPS) China Institute of Atomic Energy (CIAE)

Sponsored by China National Nuclear Corporation (CNNC) Chinese Academy of Sciences (CAS) National Natural Science Foundation of China (NNSFC) China Institute of Atomic Energy (CIAE)

International Center for Theoretical Physics (ICTP) Third World Academy of Sciences (TWAS) 16TH INTERNATIONA CONFERENCE

NUCLEAR TRACKS IN SOLIDS

Beijing

September 7-11, 1992

ABSTRACTS Organizing Committee Chairmant Sun Zuxun (Beijing) Members: Cheng YuUn (Shanghai) Chen Zhonglin (Beijing) Cui Huanhua (Beijing) Feng Yushui (Beijing) Guo Shi-Lun (Beijing) Hu Ruiying (Guangzhou) U Xianhai (Xi' an) Liu Shunsheng (Changsha) Pang Deling (Shanghai) Shen Ronglin (Beijing) Sun Guangyu (Beijing) Wang Shicheng (Beijing) Wsu Huishan (Beijing) Wu Yonggen (Beijing) Zhao Chongde (Beijing) Zhao Yunlong (Beijing) Advisory Committee Members: Guo Shi-Lun (Beijing) He Zehui (Beijing) Huang Shengnian (Beijing) U Shounan (Beijing) Sun Hancheng (Beijing) Sun Zuxun (Beijing) Tang tin (Beijing) Wang Chuanying (Beijing) Yan Shuheng (Beijing) Yang Fujia (Shanghai) Yang Tianlu (Beijing) Zhang Jiahua (Shanghai) Zhou Yuanquan (Beijing) International Committee President: S.-L. Guo (China) Members, E. V. Benton (USA) R. Brandt (Germany) L, T. Chadderton (Australia) W.G. Gross (Canada) S. A. Durrani (UK) K.K.Dwiv«li (India) W. Enge (Germany) G. Espincsa (Mexico) R.L. Fleischer (USA) M. Fuji! (Japan) I.Hunyadi (Hungary) R. Hie (Yugoslavia) H. A. Khan (Pakistan) M.M.Monnin (France) D. F. C sullivan (Ireland) J.Palfalvi (Hungary) V.P.Perelygin (Russia) M.Sohrabi (Iran) L.Tommesino (Italy) H.S.Virk (India)

Scientific Secretary s Guo Shi-Lun (Beijing) 16th International Conference on Nuclear Tracks in Solids, Sept 7—11, 1992, Beijing, China Preliminary Programme

Thursday Sunday, Sept. 6 Monday, Sept. 7 Tuesday, Sept. 8 Wednesday, Sept. 9 Friday, Sept 11 Sept. 10

8 i 30—10 : 00 Registration Radon I Neutron I Track Development I 10 » 00—10 : 30 Coffee+Poster I Coffee+Poster I Coffee+Poster IV 10 : 00—11 « 30 10 * 00—12 : 00 G 1 :Life Science+ R Welcome Addresses / I : Space Research / I -Filters 10 « 30—12 •- 00 Registration Neutron I E Opening Lecture 1 I : Nuclear Physics I A I I -Track Development I Parallel Sessions < 11 s 30 Photograph T ll:Radon I I *Nuclear Physics I \ 1 :Radon V W I: Radon I A 12 « 00—14 '• 00 Lunch Lunch Lunch L Lunch L + Detector+ 14 « 00—15 i 30 Track Formation I Geoscjence I M I Track Observation N 15 i 30—16 • 30 14 « 00—18 : 00 Coffee+Poster I Scientific Coffee+Poster I G Coffee+Poster I Registration Visit T / 1 : Track Formation I 16 : 30—18 t 00 (plenary) O t I :Geoscience I M fcncluding Remarks Parallel Sessions Nuclear Physics I B 11: Radon IV S

18 : 30 19 : 00 Reception Peking Opera Banquet 19 : 30 INTS' Meeting CONTENTS

•••••• I Monday, Sept. 7 • • • ••••• 3 Tuesday, Sept. 8 •••• •••••••••••••• • 15 Wednesday, Sept. 9 •••••••••••••••••••••• •••• 37

rixKlcLjf y oCJjfl« JL JL %J\J Supplements •••• •••••• 139 Posters •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 203 Monday, Sept. 7 / Tuesday, Sept. 8, Poster I 205 Track Formation ••••••••••••••••••••••••••••• 209 Detectors ••••••*•••••••••••••••••••••••••••••••••••••* 219 Track Development 233 Track Observation 251 Wednesday, Sept. 9, Poster II 259 Nuclear Fnysics ••••• • zoo Space Research • 279 ^seutron ••••••••••••••••••••••••••••••••••••••••••••• 28 J Geoscience •••••••••••••••••••••••••••••••••••••••••• 301 life and Environmental Science 315 Friday, Sept. 11, Poster III •••• 331 Radon •••••••••••••••••••••••••••••••••••••••••••••••• 335 Filters and Material Science 371 ORAL PRESENTATIONS Monday, Sept. 7

Opening lecture (Chair: Guo, S. -L. )

Price, P. B. (Berkeley), ADVANCES IN SOLID STATE NUCLEAR TRACK DETEC- TORS (45)'

Track Formation I (Chair. Durrani, S. A. ):

Chadderton, L. T. (Canberra), THEORY OF LATENT RADIATION DAMAGE IN POLY- MERS. (30) 6 Schopper, E. (Frankftst): HOLLOW TRACKS OF HEAVY IONS IN AgCl (Cd)-DETEC- TORS. CONTRIBUTION TO THE RADIAL PROFILE OF THE ACTION OF CHARGED PARTICLE IN SOLIDS. (30) 7 GroeneveH, K. a (Frankfurt): PARTICLE PENETRATION THROUGH FROZEN GASES. (15) 8 Ruaell, F. M. (Oxon), TRACK FORMATION BY RELEASE OF LATTICE ENERGY IN MICA. (15) 9

Nuclear Physics I (Chair: Perelygin, V. P. )

Brandt, R. (Marbwg), WIDE ANGLE EMISSION OF HEAVY FRAGMENTS IN RELA- TTVISTTC HEAVY ION COLLISIONS AND SOME OPEN PROB- LEMS. (30) 10

Cat, X. (WuiMw): DIGFTALCONTROLLED MEASUREMENT AND THREE-DI- MENSIONAL RECONSTRUCTION OF PARTICLE TRACKS IN EMULSION CHAMBER OF CERN/ EMUOl EXPERIMENT. (15) 11 Dwiveft, K. K. (ShllkM«): STUDIES OF THE FISSION OF HEAVY IONS AND EVAPORA- TION OF ALPHA PARTICLES USING NUCLEAR TRACK DE- TECTORS. (15) 12 Zhang, Huan-QUo, (Bdjtnf ), ANOMALOUS ANISOTROPIES OF FISSION FRAGMENTS IN NEAR- AND SUB-BARRIER FUSION-FISSION REACTIONS. (15) 13 Hie, R. (Ljubljana): ETCHED TRACK DETECTORS IN SOLAR NEUTRINO EXPER- IMENTS. (15) 14

* The number in the parentheses after the title shows the time in minute for which this paper will be presented orally, including discussions. The same implication is for the number after other titles. RT—Round Table oral presentation. ADVANCES IN SOLID STATE NUCLEAR TRACK DETECTORS

P. B. Price Physics Department, University of California, Berkeley, CA 94720

New detectors made of phosphate glass, together with CR-39 and other poly mertic detectors, are being used in a rich variety of scientific applications, includ

ing: 1. Most of the world' s knowledge about cluster radioactivity comes from ex porimcnts with phosphate glass and polyester detectors. Depending on the parent nu deus, the preferred type of cluster may be MC, 22O, 23F, 24Ne, 28Mg, 32Si, or 34Si. 2. CR- 39 and phosphate glass have been used to study fragmentation of beams of 16O, 28Si, 32S, and 197Au at Brookhaven and CERN at energies of 12 to 200 GeV/nucleon. When the target has a high atomic number such as Pb, the cross section for fragmentation due to the electromagnetic interaction can be larger than that due to the nuclear interaction. The process of charge pickup — the in crease in atomic number of the beam ion during an interaction — is found to occur with a cross section that increases as the square of the atomic number of the projec tile and is nearly independent of energy for energies above about 1 GeV/nucleon. Secondary nuclei produced in projectile fragmentation are found to disintegrate with unusually high cross sections. A search for strangelets — hypothetical compos- ite particles with very large strangeness and A/Z — is in progress. 3. Large arrays of phosphate glass have been flown in Antarctic balloon flights and on the Soviet Mir Space Station. New data now exist on the isotopic composition of Fe and Ni nuclei in cosmic rays, and tracks of nuclei up to uranium are being collected for analysis after the glass is recovered from space. 4. Measurements of the response of CR-39 to ions from deuterons up to iron over a wide range of velocities show that at velocities below 0. 01c the track etch rate deviates from a simple dependence on REL. 5. Using an Atomic Force Microscope, one sees that etching of tracks of extremely low velocity ions in mica occurs by motion of steps one unit cell high. This powerful new observational tool may make it possible to distinguish recoil tracks of daughters of alpha decay from tracks due to recoil of atoms in the mica structure struck by neutral particles. An experiment is being set up to search in mica for recoils due to Weakly Interacting Massive Particles (WIMPs) which might explain THEORY OF LATENT RADIATION DAMAGE IN POLYMERS

LEWIS T. CHADDERTON1 and SALVADOR A. CRUZ2

Division of Applied Physics, CSIRO Institute of Industrial Technologies, and Laser Physics, Research School of Physical Sciences and Engineering, Institute for Advanced Studies, Australian National University, GPO Box 4, Canberra, ACT 2601, Australia.

2Dcpto. de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Apdo. Postal 55-534, 09340 Mexico DF.

An atomistic model is developed which accounts for the rate of accumulation and fixation of ion-induced radiation damage in polymers as, for example, in the case of latent nuclear tracks. The theory

specifically applies for incident ion energies E > Emax. where Em^ is that energy corresponding to the peak in the electronic stopping power Se for the particular ion/target combination. It is assumed that basic ionization processes create irreversible polymer damage by means of fundamental bond-breaking events along the particle trajectory, which totally dominate until the implanted ion comes to rest in a series of nuclear cascade events. Evolution of the accumulated damage pattern is calculated using an appropriate set of coupled rate equations for the moving species generated, which include consideration of isolated bond-breaking events, extended regions of damage, and their ultimate aggregation. HOLLOW TRACKS OF HEAVY IONS IN AgCl (Cd) -DETECTORS. Contribution to the radial profile of the action of charged particles in solids

E.Schopper. Univ.of Frankfurtam Main Germany

The microdensimetric lateral structure of tracks of charged particles in monocrystalline layers of AgCl-detectors, and in nuclear emulsion for comparison, has been measured by means of a videoelectronic computer-controlled image analysing system. The lateral optical density profiles in sequential steps of 0.2um are showing compact tracks with a density maximum around the track- axis as well as "coreless"tracks with a density minimum towards the axis in AgCl detectors. The fading effect of the core depends on the charge state q of the particle rather than on its (high) LET; it hints to an increased ion-displacement by Coulomb- repulsion into the lattice of the detector.especially of Ag+-atoms which are needed for the formation of the track. Examples of measurements and of the tracks are presented.The observations in AgCl are -we believe-not only of interest for nuclear track recording; the biologic action of heavy ions e.g. has raised related questions. The AgCl-detector should be regarded as an example of a special solid. PARTICLE PENETRATION THROUGH FROZEN GASES

M. SCHOSNIG, H. ROTHARD, K. KRONEBERGER, D, SCHI_6SSER, K.O. GROENEVELD Institut fur Keraphysik der Joh&nn Wolfgang Goethe Universit&l, August-Euler-Str.6, D-6000 Frankfurt a.Ii. 90, Germany

The energy deposition in sclids along the track of penetrating svitt particles can cause ndcrospspically a phd.-=e transition, e.g. frw. a solid to a liquid or gaseous state. Such mechanisms can play a role in track formation. The influence of near-surface properties at efficiently cooled solid targets, such as solidified xenon and carbon dioxyde, in ultra high vacuum on e.g. the emission of secondary electrons /I/ under ion bombardment ij- discussed. The observed yields of transmission erosion of frozen gases are surprisingly high /2/. The measured electron energy distributions show dram&tic yield dependences of both convoy electrons (CE) [not expected at

high electron energies (Eei500eV)] and secondary electrons (SE) [expected

at low energies (Eei25eV)] on the CO2 coverage thickness. These dependences can be interpreted in terras of enhanced transport lengths for CE in these large band gap insulators. For low energy SE a complementary behavior was found. Surprisingly, the adsorbate thickness dependence of the relative SE yield compared to the CE yield was not affected by the energy dependence of electron escape depths. Quadrupole mass spectrometry of the residual gas composition shows that the penetrating ion dissocia-

tes the carbon dioxyde in CO and O2. Similar effects on electron emission could be observed using xenon as adsorbate.

/I/ H. Rothard, K.O. Groeneveld, 3. Keranler, in: "Particle Induced Electron Emission II" (G. Hohler, Ed.) Springer-Verlag, Heidelberg, Springer Tracts in llodern Physics 123 (1991) and ref. quoted therein. /2/ H. Schcsnig, H. P.othard, K. Kroneberger, D. Schldsser, K.O. Groeneveld, Kucl. Instr. Keth. (Kay 1992) to appear Work has been supported by BEET, Bonn, under Nr. 06 OF 110 Ti 439 TRACK FORXATIOI BY RELEASE OF LATTICE EFERGY IF XICA.

F K Russell Rutherford Appleton Laboratory, Didcot, Oxon, UK

Tracks of energetic positrons from the decay of potassium atoms in nuscovite have been studied by optical microscopy, electron diffraction and X-ray dispersive analysis. This was helped by the great increase in range of the positrons due to channelling in the (001) plane. It was already known that the tracks are composed mostly of magnetite precipitated in proportion to the rate of loss of particle energy by ionization. However, some tracks showed evidence of a second recording process which was independent of energy loss by lonization and resulted in tracks being delineated by regions of altered material. It has been found that the altered material is epidote, a calcium-rich mineral closely related to muscovite. Hence, the tracks are the result of a solid-state phase change which releases energy from the lattice. Usually, tracks are formed in solid-state track-sensitive materials by particles depositing energy in the lattice. In this new recording mechanism a charged particle triggers the release of energy previously stored in the lattice to record a track, apparently without loss of energy by the particle. That is, the particle acts as a catalyst to initiate a phase change. This finding enables the highly variable track recording aad decorating processes in mica to be understood in considerable detail in terms of a spinodal decomposition model involving both iron and calcium impurities. WIDE ANGLE EMISSION OF HEAVY FRAGMENTS ]N RELATTVISTIC HEAVY ION COLLISIONS AND SOME OPEN PROBLEMS

R. Brandt (speaker)1), M. Heck1), S. Heise1), G. Haase1*8), P. Vater1), T. Schmidt1), B. Bisplinghoff1), B .A. Kulakov2). MX Krivopmtov2), VJ. Butsev2), AM. Sosnin2), E J. Langrock3), M. Rommel3), SX. Guo4), H.H. Cui5), RA. Khan6), I.E. Quresbi6), I. Shazad6), KK. Dwivedi7) 1 Kernchemie, Piiilipps-University, Marburg, Germany LHE, Joint Institute for Nuclear Research, Dubna, Kur.sia Fachbereich Naturwissenschaft, T.H., Leipzig, Germany Institute of Atomic Energy, Beijing, China Institute for High EnergyPbysics, Beijing, China PINSTECH, Islamabad/Pakistan . Chemistry, N.-E. Hill University, Shillong, India 8 present addr.: Bdsanst. f Milchforschung, Kiel Germany

Recent experiments from the SYNCHROPHASOTRON, Laboratory of High Energies, Joint Institute for Nuclear Research, Dubna, Russis, suggest two kinds of rather novel observations1: 1) In bubble chambers and counter-experiments one observes some effects of a reduced mean-free-path of secondary fragments. 2) With the copper target technique, analysed by radiocbemical methods, one observes too much production of decp-spallation products (2^Na) at large lab angles. Consequently, we studied the emission of heavy fragments into large angles, induced by 3.65 GeV/n heavy ion on copper targets. This set-up, a stack of CR-39, is called ARBUZOV-target. Finally, we present a recent experimental set-up, a rather massive heavy element target, to be irradiated again with the. "Dubna" 3.65 GeV/n ions; here we study the emission of low energy hadrons from this massive target with a variety of SSNTD and other detectors. 1) R. Brandt, et al., Phys.Rev. Q March 1992 (in print)

10 DIGITAL-CONTROLLED MEASUREMENT AND THREE-DIMENSIONAL RECONSTRUCTION OF PARTiqLE TRACKS IN EMULSION CHAMBER OF CERN/EMUOI EXPERIMENT

CAI Xu*

(InttHuU •/ Particle Phytie$, Huaikong Worm*/ t/mtcrotly, W«Ac* 430070, Ckint)

and

M I Adamovich, M M Aggarwal, Y A Alexandra*, N P Ancireeva, Z V Ansoa, R Arora, F A Avetyan, S K Badya], E Bwova, K B Bhalla, A Bhaiin, V S Bhatia, V G Bogtacov, V I Bobnov, T K Burnett, IY Chunikov, L P Cheraova, M M Chernyaviky, G 2 Eligbaeva, L E Ereznenko A S Gaitinov, E R Giniuu|c, S Carpman, S G Gerauimov, J Grots, K G Gularoov, S K Gupta, H H Heekman, B Jakobnon, B Judek, S Kachroo, F G Kadyrov, G S Kalyachldna, E K Kanyfina, M Karabova, G h Kaul. S P Khariunov, T KOM, S A Kraanov, V Kumar, P Lai, V G Larionovm, V N Lepetan, L S Liu, S Lokanatan, J Lord, N S Luldcheva, S B Luo, L K Mangotra, N A Marutyan, N V Matle&nikova, I S Mittra, S Mookeijee, H Nasrulaeva, S H Nasyrov, V S Navotny, G I Orlova, I Otterluad, H S Palsuia, N G Pcntadko, N V Pftrov, V A Plyui? chev, W Y Qian, R RaniwJ«, S RanJwaU, N K Rao, V M Rappoport, J Ravina, J T Rhee, N Saidkhanov, N A Salmaaova, L G Sarkuova, V R Sarkiiyan, G S Shabratova, T I Shakhova, D Skelding, K Sodentrom Z I Solovieva, E Stenlund, S C Straust, L N Svechaikova, K D Tolitov, M 1 lr«tyakovm, T P Trofimov*, U Tuleeva, S Vokal, H Q Wang, Z Q Weng. R J Wilkc*. G F Xu, D H Zhang, P Y 2hens, S I Zhokhova and D C Zhou

EMU01 COLLABORATION

*Pre»ented at the 16th Intern. Conference on Nuclear TVacki in Solidi, Beijing, China, Sept. 7-11, 1992

ABSTRACT

In this talk we will describe a new nuclear emulsion technique, a digital-controlled method, for making fast and accurate measurement and tnree-dimension reconstruction of charged particle tracks in a special nuclear emulsion chamber, which is used as detector with target foil of iilT«, gold or lead nuclei by the CERN/EMUOI experiment and has the best resolution in the investigation of Tery high multiplicity in vhra-rdativislie heary-ion collisions.

11 STUDIES ON THE FISSION OF HEAVY IONS AND EVAPORATION OF ALPHA PARTICLES USING NUCLEAR TRACK DETECTORS

K.K. Dwivedi" (speaker), J.Raju", P.Vater*> and R.Brandt2> ^Department of Chemistry, North-Eastern Hill University, Shillong-793 003, India. ^Kernchemie, FB 14, Philipps-Universitat, 3550 Marburg, Germany

A nuclear track technique has been developed for studying the fission of energetic ( E > 1.4 GeV ) heavy ions in polymeric dielectric solids. The technique offers a 4*r detection of fission fragments and the evaporated a-partides from the excited compound nuclei formed by the interaction of projectiles with the lighter nuclei constituting the matrix of the polymers. Several track detectors were exposed to well collimated beams of different accelerated heavy ions at UNILAC, GSI, Darmstadt. The irradiations were done with a moderate fluence of about 105 cm'2 at angles of 30° and 45°. The detectors were etched successively in suitable etchants till all the tracks are completely etched. The etched detectors were then scanned for fork-like events and the polar coordinates of all the branches of several hundred events were measured. A computer program NEWCOR has been developed and used to transform the measured polar coordinates into real parameters such as pre-fission energies, ranges of the fragments and the angles with respect to the beam direction. These data are then fed to an analysing program UFISS in order to evaluate fragment masses and kinetic energies, relative velocities, Q-values, asymmetry parameters, scattering angles and pre-fission mass of the compound nuclei. Nearly 5% of the events contain small tracks of evaporated residue at the point of bifurcation. In view of the analysed data, these events are attributed to the evaporation of a-particles from the excited compound nuclei. Some recent findings and future scope of this work will be discussed.

12 ANOMALOUS ANSIOTROPIES OF FISSION FRAGMENTS IN NEAR-AND SUB-BARRIER FUSION-FISSION REACTIONS

Zhang Huanqiao, Liu Zuhua, Xu Jincheng, Lu Jun, Ruan Ming and Xu Kan

China Institute of Atomic Energy, P. O. Box 275, 102413, Beijing, China

Fission cross sections and angular distributions have been measured for the reactions of 16O + 232Th and 238U, and 19F + 208Pb and 223Th at near- and sub-barrier energies with mica detector. The fission excitation functions are rather well re- produced on the basis of Wong moldel or coupled channels theory. However, the models which reproduce the sub-barrier fusion cross sections fail to account for the experimental anisotropies of fission fragments. It is found that the observed anisotropies are much larger than expected. For the first time it has been observed that the anisotropies as a function of the center-of-mass energy show a peak cen- tered near 4. 5 MeV below the fusion barrier for several reaction systems. The present approaches fail to explain these anomalies. For l9F -j- 208Pb system, our results confirm the prediction of an approximately constant value for the mean square spin of the compound nucleus produced in far sub-barrier fusion reaction.

13 ETCHED TRACK DETECTORS IN SOLAR NEUTRINO EXPERIMENTS

R. I1W, T. Sutej', J. Skvarf', M. Krimar", A. Ljubittd", S. KauCtt", M.

' J.Stefan Institute, University of Ljubljana, POB 100, 61111 Ljubljana, R Slovenia ** R. BoSkovic Institute, POB 41001 Zagreb, R Croatia *** Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, 229 Japan

Now there are four man made solar neutrino detectors in action and fifth is planned to start in 1995. The SAGE1 and GALLEX2 experiments are based on the utilization of TIGa(i>, e")7IGe reaction. In the HOMESTAKE3 experiment the neutrinos are measured via 37Cl(i/, e")37Ar reaction. The KAMIOKANDE4 and SNOS experiments use v + e~ —• v + e~ and v + d —• p + p + e~ reactions, respectively. Various mineral6 deposits in the earth were proposed for a time average (milion of years) neutrino flux measurements using !0STl(i>,e-)205Pb, 98Mo(i>,e-)98Tc and 126Te(i/,e-)126Xe reactions. The aim of the present study is twofold: (i) to analyze the potential application of etched track detectors for the assesment of background radiation and (ii) to present our first results obtained within the frame work of LOREX experiment where the mineral Lorandite (TlAsSj) of the old (5xl0c years) arsenic mine Allchar (Macedonia) is used to estimate solar neutrino flux from the amounts of 2a5Pb isotope (T1/2 = 1.5 x 107 years) induced by neutrino capture in 20oTl. In order to evaluate the amount of the 2O5 isotope induced by 2O4Pb(n, -7) the thermal neutron flux in the mine was measured by a high sensitive CR-39/BE neutron detector, and it founds to be (4.4 ± 0.6) x 10~3cm~2s-l. In addition to cosmic muon interactions and spontaneous fissions the neutrons can be produced through various (a, n) reactions due to the high aipha particle flux emitted in 220Rn and 222Rn chains. Radon concentration in the mine was measured by our diffusion chamber type radon dosemeter utilizing CR-3 detector and was found to be 1.5 x 104 Bq m~3. The possibilities to extend the present experiments will be discussed as the conclusion of the lecture.

1 Soviet American Gallium Experiment, Baksan Neutrino Observatory, USSR 2 European Collaboration, Gran Sasso, Italy 3 Homestake mine, USA 4 Kamiokande zine mine, Japan 6 Sudbury Neutrino Observatory, Canada 6 Thallium, molybdenium and tellurium minerals

14 Tuesday, Sept. 8

Radon I (Chair. Price, P. B. )

Durrani, S. A. (Brminfham): RADON AS A HEALTH HAZARD AT HOME; WHAT ARE THE FACTS. (30) 17

Khan, H. A. (Islamabad). USEFULNESS OF RADON MEASUREMENTS IN EARTH SCI- ENCES. (30) 18

Monnln, M. M. (MontpeUier): A COMPREHENSIVE APPROACH OF RADON MEASURE- MENTS FOR GEOPHYSICAL STUDIES. (30) 19

Space Research (Chair. Dolce, T. )

Ogura, K. (Chita): DETERMINATION OF HIGH LET COSMIC PARTICLES' TRA- JECTORIES FOR SPACE RADIOBIOLOGICAL STUDIES. (15) 20

Perron, C (Paris). COSMIC RAY-INDUCED SPALLATION RECOIL TRACKS IN METEORrnC PHOSPHATES: SIMULATION AT THE CERN SYNCHROCYCLOTRON, (15) 21

Oda, K. (Kobe). ANGULAR DEPENDENCE OF PROTON RESPONSE IN CR-39 TRACK DETECTOR. (10) 22

Rusov, V. D. (Odessa): PROSPECTS OF MAKING A MULTI- ELEMENT PHOTO- GRAPfflCSPEORC»ffiTER-DETECTOR. (10) 23

Adam, J. H. Jr. (Washington): PRELIMINARY RESULTS FROM THE HEAVY IONS IN SPACE (HnS) EXPERIMENTS. (15) 24

Crfge, I. (San Francisco): IDENTIFICATION OF RECOIL PARTICLES USING TRACK- COINCIDENCE AND MULTIPLE TRACK ETCHING METHOD. (10) 25

Zheng, Pu-YIng(BeiJing): TRACK DETECTION BY USING NUCLEAR EMULSION IN CHINESE SATELLITES. (10) 26

Nuclear Physics II (Chair. Virk, H. S. )

Treryakova, S. P. (Dubna): THE USE OF CR-39 PLASTIC DETECTORS FOR INVESTIGA- TION OF ELASTIC SCATERING OF EXOTIC NUCLEI. (15) 27

15 Cut, Huan-Hua (Beijing) t STUDY OF HIGH ENERGY HEAVY FRAGMENTS FROM THE INTERACTION OF 3. 65 A GEV »F OR UO IONS WITH CU. (15) 28

Dcbeauvatt, M. (Strabourg): APPLICATION OF SSNTDIN NUCLEAR PHYSICS, (15) 29

U, Xint-Zhong(Bdjinc): DETECTION OF ANOMALOUS NUCLEAR EFFECT IN DEU- TERIUM/SOLID SYSTMES USING CR-39. (15) 30

Zamanl, M. (Thewalonlkl) • SEMHONEMATICAL ANYLYSIS OF 3- AND 4- PRONGED EVENTS OF THE U+AG REACTION AT 15 MEV/N. (15) 31

Radon II (Chair.. Sohrabi, M. )

Pang, De-Ling (Shanghai), RECENT DEVELOPMENT IN TRACK ETCH RADON DETEC- TION TECHNIQUE. (30) 32

Virk, H. S. (amribar): RADON AND EARTHQUAKE PREDICTION: PRESENT STA- TUS AND FUTURE TRENDS. (30) 33

II, Xian-Jie (Hengyang): THE FIRST NATIONAL INTERCOMPARISON OF RADON IN- TEGRATNG DETECTORS IN RADON CHAMBER. (15) 34

Surbeck, H. (Frlbouif)- RADON MONITORING IN SOILS AND WATER. (15) 35

16 RADON AND HEALTH HAZARD AT HOME- WTAT ARE THE FACTS?

S. A. Durrani

School of Physics and Space Research, University of Birmingham, Birmingham B15 2TT, U.K.

17 Invited Talk

USEFULNESS OF RADON MEASUREMENTS IN EARTH SCIENCES

HAMEED AHMED KHAN Head SSNTD-Laboratory (NED), PINSTECH, P.O. Nilore, Islamabad, PAKISTAN

Abstract: Recent years have seen an ever increasing interest in studying the usefulness of radon measurements in Earth Sciences. These studies include (a) earthquake prediction, (b) mapping of geological faults, (c) carrying out volcanic studies, and (d) locating geothermal energy sources & materials such as uranium and oil. The SSNTD-Laboratory (PINSTECH) has been carrying out detailed experimental work concerning the relationship of (a) the emission and migration of radon and (b) production of shock waves in different geophysical phenomena. Theoretical work on the possible correlation of shock waves produced before the physical jolt of an earthquake is also under progress at our laboratory. The studies carried out at our institute and elsewhere has suggested that a more systematic approach in this regard is required before some quantitative applications can be made. This paper gives a brief review of the progress made in the field of radon measurements in earth sciences in different laboratories of the world.

18 A COMPREHENSIVE APPROACH OF RADON MEASUREMENTS FOR GEOPHYSICAL STUDIES

M. MONNIN, J-P. MORIN, J-L SEIDEL

Laboratoire d'Hydrogeologie - Centre National de la Recherche Scientifique University Montpellier II • 34095 Montpellier Cedex 5 . France

In spite of the fact that radon anomaly surveys have already provided useful information in the field of the geosciences much has yet to be done in order to qualitatively and quantitatively interpret the observed phenomena. In this paper a laboratory experimental and numerical apprehension of the involved phenomena is presented and discussed.

The experiments are carried out in a 10 m high tower which simulates the upper layer of the soil or of a water table, or both. The porosity can be changed depending on the filling material granulometry. Several inlets at the bottom of the tower allow to introduce differents carriers at controlled speed motion. Temperature, pressure, humidity and radon sensor are distributed within the tower thus allowing a detailed space mapping of the parameters variations.

With the use of this large experimental facility the following investigations have been undertaken: - influence of atmospheric temperature and barometric variations as a function of depth are reported. • transport of Radon in soil by convection of gas and liquid carriers at well monitored gas velocities and comparison with theoretical responses. - transport od radon by micro-bubbles in a water saturated medium and comparison with the Varnagy et al.'s model. The results of these investigations are presented and among them some unexpected findings are discussed. The overall work provides both an experimental and theorerical way to apprehend the basic geophysical phenomena as well as those involved in dwellings radon intake.

19 DETERMINATION OF HIGH LET COSMIC PARTICLES' TRAJECTORIES FOR SPACE RADIOBIOLOGICAL STUDIES K. Ogura, M. Matusima and H. Yamada College of Industrial Technology, Nihon University 1-2-1, Izumi-cho, Narashino, Chiba 275, Japan T. Takahashi, F. Yatagai, H. Ohnishi and T. Kasuya 2-1, Hirosawa, Wako, Saitama 351-01, Japan T. Doke and K. Kuwahara 17, Kikui-cho, Shinjuku, Tokyo 113, Japan S. Nagaoka 2-4-1, Hamamatsu-cho, Minato, Tokyo 105, Japan

During the IML-1 mission in January 1992, Radiation Monitoring Con- tainer accommodating biological samples and CR-39 track detectors were exposed to cosmic radiation for 7 days, lu the container three kinds of biologicdl samples fixed on CR-39 plates were sandwiched between the other CR-39 plates respectively. B. subtilis spores were fixed on the CR- 39 detector dyed brown. For better understanding of the mechanism of cell inactivation induced by cosmic HZE particles, we carried out experiments to characterize the microscopic structure of the radiation action near a single particle. This has been done by measuring the fraction of dead spores as a function of the distance between the center of the particle path and spores around it. After the mission, the stack was disassembled and CR-39 detectors both above and below the biological layer were etched and analysed by the video image analysis system. Only particles with high LET were tracked and determined the trajectories, and then estimated the points of intersection of the particle trajectories through the biological specimen layers. Around the coordinate of the intersection points, reference grid marks were printed with a UV laser beam of several tens of uJ per pulse on the dyed CR-39 detector on which spores have been fixing. A photograp was taken to check the outgrouth of the spores after an incubation at 37°C, and then CR-39 plates with laser markes were etched to reveal the track etch pits. As a result, the position of the spores in relation to the HZE particle track was determined to better than 0.5 urn. Experimental results on the fraction of dead spores as a function of the distance from the particle track will be presented.

20 COSMIC RAY-INDUCED SPALLATION RECOIL TRACKS BSf METEORITIC PHOSPHATES: SIMULATION AT THE CERN SYNCHROCYCLOTRON.

Claude Perron Institut d'Astrophysique Spatiale and Museum National d'Histoire Naturelle, 75005 Paris, France

Three main sources of nuclear tracks are usually considered for meteoritic minerals: i) Cosmic Ray Fe-group ion irradiation during the meteoroid journey from parent- asteroid to Earth; ii) spontaneous fission of 238U during the lifetime of the Solar 244 System; iii) spontaneous fission of Pu (Tj/2 = 82 Ma) during the first few hundred million years of the Solar System. In the calcium phosphate merrillite, Pu was very much enriched with respect to U, and, provided samples are taken from deep enough in the meteorite (i.e. they were shielded from Cosmic Ray Fe ions), Cosmic Ray track densities may be neglected. 244Pu fission is then commonly taken as the overwhelming source of tracks in this mineral, and it has been used to derive the relative chronology and thermal history of chondritic asteroids [1]. It has been known for a long time, however, that recoiling nuclei from spallation reactions induced by Cosmic Ray protons can make revealable tracks in merrillite, which mimic short fission tracks [2]. To check the importance of this phenomenon in chondritic merrillite, phosphate crystals from 7 chondrites were irradiated by the 600 MeV proton beam of the CERN synchro-cyclotron, after fossil tracks had been erased by thermal annealing. Spallation recoil tracks were observed and counted with a scanning electron microscope. The data analysis is not yet complete, but we have a preliminary value for the production yield of spallation tracks of about 10~7 cm'2 per incident proton. Assuming that this value does not significantly vary with proton energy, it can be converted into a production yield in space of about 3 to 7 cm"2 Ma'1, depending on the size of the meteoroid, and the depth of the sample considered. This is significantly larger than previous measurements [2] and it makes the contribution of spallation tracks to the track density of merrillite far from negligible, for most chondrites with exposure ages longer than 5-10 Ma.

[1] P. Pellas and D. Storzer, Proc. R. Soc. London, Ser. A 374, 253 (1981). [2] G. Crozaz and D.R. Tasker, Meteoritics 18, 284 (1983).

21 ANGULAR DEPENDENCE OF PROTON RESPONSE IN CR-39 TRACK DETECTOR '

K. Oda% I. Csige*, T. Yamauchi', H. Miyake" and E. V. Benton*

* Department of Nuclear Engineering, Kobe University of Mercantile Marine, Kobe 658, Japan f Physics Department, University of San Francisco, San Francisco, CA 94117, U.S.A.

The dependence of the etch rate ratio on the particle incident angle was investigated. In one case such dependence was found for CR-39 track detector exposed to accelerated protons in vacuum. In the expertiment the outgassing time before irradiation was about 1 hour. In another experiment, two layers of CR-39 were exposed to fast neutrons in normal air condition and the proton response of the detector was evaluated using a new internal calibration technique. In this case no significant incident angle dependence of the etch rate ratio was observed. The discrepancy between the results of the two experiments will be discussed in consideration with the vacuum effect (a possible decrease in sensitivity and /or increase in etch induction time).

H USF portion of the work partially supported by NASA Grant No. NACB-168 (Marshall Space Flight Center).

22 PROSPECTS OF MAK1HG A HULTI-ELEMEHT PHOTOGEAFHIC SPECTROHETEK - DETECTOR

V. D. Kusov

Odessa State University

Based on autowave processes tbeorr In distributed Kinetic systems, a srnergetic model Is proposed . one tbat taKes into account tbe most Important features of tbe development process (such as autocatairtic capability, selectivity. and tbe mechanism of photoenmlslon mlcrocrystals ' development) maKlng it possible to determine tbe formation conditions of various types of developed microcrystals. Creation of a single explanatary pattern for Kinetics, topography and morphology of developed pbotoemulslon mlcrocrystals is a promising step towards maKlng nuclear emulsions with regulated sensitivity depending upon tbe energy of detected particles. Presented are mlcrophotograpbs of nuclear emulsion mlcrocrystals of those intervals of successive development that indicate an evolutionary transition of silver grain structure from point - and - sphere to a hexagon , which is evidence of good prospects for synergetlc approach to be used In tbe maKing of a multi-element photographic spectrometer - detector. PRELIMINARY RESULTS FROM THE HEAVY IONS IN SPACE (HHS) EXPERIMENT

James H. Adams, Jr., Lorraine P. Beahm, and Allan J. Tylka

E. O. Hulbun Center for Space Research Code 4154, Naval Research Laboratory Washington, DC 20375-5000 USA

In January 1990, NASA's Long Duration Exposure Facility (LDEF) was retrieved after 5.8 years in space in a 28.4°-incIination orbit at an average altitude of 476 km. Mounted on the space-facing end of LDEF was the Heavy Ions in Space (HIIS) experiment. The HIIS experiment consisted of eight stacks of CR-39 and Lexan plastic track detectors, each with a total vertical thickness of -12 g/cm2. HIIS has a collecting power of 2.0 m2-sr, which ranks it as the second largest cosmic ray experiment ever flown in space. With this large collecting power and extended exposure, HIIS offers a survey of the near- ] Earth particle radiation environment of unprecedented sensitivity. \ ! j The HIIS experiment has two primary objectives: (1) to measure the elemental ! composition of ultraheavy Galactic cosmic rays, beginning in the tin-barium region of the > periodic table; and (2) to investigate heavy ions which arrive at LDEF below the geomagnetic cutoff, either because they are not fully stripped of electrons or because their source is within the magnetosphere.

We report on the performance of the detectors and show results on their calibration and charge resolution. We present preliminary results on the spectrum, composition, and arrival-direction distribution of below-cutoff stopping heavy ions of unknown origin. We also report on the status of HIIS measurements of ultraheavy cosmic rays.

24 IDENTIFICATION OF RECOIL PARTICLES USING TRACK-COINCIDENCE AND MULTIPLE TRACK ETCHING METHOD1

I. Csige, K. Oda. R. P. Henke and E. V. Benton Physics Department, University of San Francisco, 2130 Fulton St., San Francisco, CA 94117-1080, USA

Abstract-A new method has been developed to identify short range recoil partides - produced by energetic trapped protons (of the Earth's radiation belts) - in a two la}er solid state nuclear track detector stack exposed on the Long Duration Exposure Facility (LDEF). Tracks in coincidence at the adjacent surfaces - indicating that the particle crossed the inner surfaces - are selected for measurements. Using multiple etching the growth of the etched track parameters are measured as a function of the etching time. These growth curves are analyzed to obtain the range of the particle and also to measure the etch rate ratio at some characteristic points along the particle trajectory. Then the particles are identified by these experimental data and the response curve of the detector material. We have used this method to- identify particles in a CR-39 (double laj-er) with charges Z<8 and particle ranges greater than a few microns. The charge-, energy- and linear energy transfer spectra generation method of these particles is discussed. Analyzing the dip angle and the azimuth angle distribution of the measured recoil tracks, we found that some information about the anisotropy of the primary particle beam can also be obtained.

*Work partially supported by NASA grant No. NAGS-168 (NASA-Marshall Space Flight Cen- ter, Buntsville)

25 TRACK DETECTION BY USING NUCLEAR EMULSION

IN CHINESE SATELLITES

Zheng, Pu—Ying

lioijing, China

26 THE USE OF CR-39 PLASTIC DETECTORS FOR INVESTIGATION OF ELASTIC SCATTERING OF EXOTIC NUCLEI

j.P.Tretyakova , C.Borcea , A.Golovchenko , I.Chrovat , M.Lewitowicz2, [S:Lukyanov , Z.Dlouhy3, Yu.Penionzhkevich1, V.Ponomarenko1, N.Skobelev1, J.Svanda , G.Toustain2, T.Tretyakova1. LNR, OINR, 141980, Dubna, RUSSIA !2GANIL, BP5027, F-14O21 Caen, FRANCE 3Nucl. Phys. Inst., CS-25068 Rez, Czechoslovakia. Results of experiments on the investigation of elastic scattering cross-sections of the light neutron-rich nuclei (6'8He, 6»7»9>11Li) are given in order to obtain information about of the structure nuclei far from the stability line. Experiments have been carried out in the LNR, OINR and GANIL. For elastic scattering nuclei registration on C-, Si-, Ag- and Pb- targets, telescopes of plastic dielectric detectors of CR-39 type have been used. The method of cross-section measurement of elastic scattering of low fluxes of radioactive nuclei be means of CR-39 consists: a) of the determination of scattered ion track coordinates on both the sides of the detector the thickness of which is less than the ion range, and of the projection of the intersection point of the particle trajectory with the target plane with the aim of separating it from the background; b) of the measurement distance between of the entry and the exit oles of the track passing through the detector to determine the scattering angle; c) of the measurement of the track density of the ion beam passing through the detector after the target for the normalization of the event number of scattered ions at the cross-section calculations. As follows from the results of the measurements by using the CR-39 jetector layers one can achieve the accuracy of the scattering angle measurement 0.1'-0.5*. The values of production cross-sections of elastic scattering of the radioactive nuclei °He, 9Li and 11Li are in agreement dth data on the cross-sections of the elastic scattering obtained by the zlectron methods.

27 STUDY OF HIGH T3NERGY HEAVY FRAGMENTS FROM THE IHTEHACTIQH OP 3.65 A GeV 19P OR 16O WITH CU Huan-Hua Cui1'2,^ Barth2, R. Brandt2, V. S. Butsev5, G. Kaase2, M. Heck2, M. I. Krivopustov5, B. A. Kulakov5, E.-J. langrock4, F. Pille4'5, M. Rommel Institute of High Energy Physics, A cr.de mi a Sinica, Beijing, China Kernchemie, PMlipps-Universit'at, Marburg, Germany Joint Institute ior Nuclear Research, Dubna, Russia Fachbereich Waturwissenschaft, Technische Hochnchule, Leipzig, Germpny ^Institut fur Hochenergiephysik,Zeuthen, Germany A CR-39 track detector was used as a target snd a detector to study the products from the interaction of 3.65 A GeV 19F ions or 16O ions with light nuclei (1H, 12C and 0). Using the peaks of the measured diameter distrilsution, the charges of the products (relativistic °P, 0, 1 \i and C ions) end their reduced etch rate V./V have been measured, which can "be used as calibrations of relativistic heavy ions. Also, the heavy fragments from the interaction of 3.65 A ReV 1SP or 160 ions with thick Cu target at the angles of 25° v/ith respect to the beam direction have been studied by use of CR-39 trrrck detectors. The diameter distribution of the heavy fragments has not changed with the distance traversed in the CR-39 stack. It can be seen from the variation of track density v/ith the distance that the major port of the heavy fragments are low energy fragments. Only 4% of the heavy fragments was stopped at the 10 cm thick CR-39 stack, which may be light fragments (1H, *He etc.) or other heavy fragments with high energy.

28 APPLICATION OF SSNTD IN NUCLEAR PHYSICS

M. DEBEAUVAIS1. J. RALAROSY1. M ZAMANI2, S. JOK1C3 and F. FERNANDEZ-*

1. Centre de Recherches Kucleaires - Strasbourg/France 2. University of Thessaloniki-Thessaloniki/Greece 3 University Svetozar Kragujevac - Kragujevac/Yougoslavie 4..Universidad Autonoma de Barcelona - Barcelona/Spain

Many years ago mica and polycarbonate detectors were used for the study of very heavy ions on heavy targets. It was the first time that such multipronged events were found. Cross sections for reactions having binary, ternary and more correlated fragments were determined. Now with cellulose nitrate and CR39 detectors it is possible to register ions with a lower dE/dx and so to increase the number of observable 4-, 5- and 6- pronged events.

The calibration of these detectors, and in particular Pershore CR 39 as a function of etching conditions, furnishes range-energy curves. Geometrical measurement of length, dip and azimuthal angle were performed. With a kinematical program, we can calculate mass and energy and relative velocities among the fragments for ternary events.

For 4, 5 and 6 fragments in spatial correlation, it is necessary to know 1, 2 or 3 masses, respectively, for each event. The tip radius method, combined with a two-step etching procedure, gives this information. With another kinematical program, we can calculate with good accuracy all the characteristics of the multipronged events. Here we will present some of these results and an interpretation.

29 DETECTION OF ANOMALOUS NUCLEAR EFFECT IN DEUTERIUM / SOLID SYSTEMS USING CR-39

Xing-Zhong Li, Da-Wei Mo, Li Zhang Tsinghua University, Beijing 1000S4 CHINA Shi-Cheng Wang, Tie-Sun Kang Institute of High Energy Physics, Beijing 100039, CHINA

CR-39 ( Plastic Track Detector ) has been proved as a good detector in searching the anomalous nuclear effect in deuterium/solid systems, because it has low background, low noise, high sensitivity. It is particularly suitable to deicc! the burst signal with no dead-lime loss. It is convenient to use in a pressurized container C1 - cn ( Frascati type gas-loading experiment). It is relatively inexpensive also. In the new set of experiments, we measure the loading ratio ( D/Pd ) simultaneously in order to improve the rcproducibility. The electrical resistivity of the palladium wire is monitored in the whole process. IdenUfication of the energetic charged particle is done in two independent methods: ( I ) Calibration of the CR-39 in terms of ion beam from an accelerator; ( 2 ) Silicon Surface Barrier Detector with dE/dx function. Since it seems that the branch ratio of D-D reaction is abnormal also in the low energy region, we expect that the detection of energetic charged particle of fusion products may gain an advantage over the detection of neutrons. The primary results will be presented. CD Xing-Zhong Li, cl al., Proceedings of Anomalous Nuclear Effects in Deuterium / Solid Systems, Ed. by S.E. Jones ct al., (Provo, USA, Oct 1990) P.419. C2) Da-Wei Mo, ct al., Proceedings of the H Annual Conference on Cold Fusion, Ed. by T. Bressani et al., (Como, Italy, June, 1991) P.123. C3) Ke-Li Wang, el al., Ibid., P.163. (4) Shi-Cheng Wang, et al., Ibid., P.169.

30 SEMI-KINEMATICAL ANALYSIS OF 3- AND 4- PRONGED EVENTS OF THE U+Ag REACTION AT 15 MeV/n

M. ZAMANI1, M. DEBEAUVAIS2, J. RALAROSY2, F. FERNANDEZ3 AND S. JOKIC4

1. University of Thessaloniki - Thessaloniki/Greece 2. Centre de Recherches Nucleates - Strasbourg/France 3. Unjversjdad Autonoma de Barcelona - Barcelona/Spain 4. University Svetozar Marcovic - Kragujevac/Yugoslavia

For estimation of masses and velocity for multipronged events in CR-39 we have used a new method of calculation based on kinematical relations.

For three fragments in correlation, the three kinematical equations are sufficient, but for four fragments a complementary equation is needed if one does not assume mass conservation. We have overcome this problem by introducing the mass of one fragment which was estimated by using measurements of the tip radius.

Calculation is made by minimizing the difference of the sum of momemta projected on the z-axis and the incident momentum. Fragment momentum can be estimated according to a momentum-range calibration.

With the above procedure, the masses of 300 3-pronged events and 200 4-pronged events have been obtained. The total energy loss has also been found.

The results can be described by various scenarios, the most important of which is the deep inelastic reaction where a U projectile undergoes fission after mass transfer to or from the Ag target.

31 RECENT DEVELOPMENT IN TRACK ETCH RADON DETECTION TECHNIQUL

Pang deling

Institute of Radiation Medicine, Shanghai Medical University Shanghai], 200032, P R China

32 RADON AND EARTHQUAKE PREDICTION: PRESENT STATUS AND FUTURE TRENDS

H.S. Virk Physics Department* Guru Nanak Dev University* Amritsar-143005(INDIA).

Radon is present in trace amounts almost everywhere on the earth, being distributed in the soil* groudwater and in the lower atmosphere. Continuous and long term measurements of radon in sub-surface soil and groudwater are carried out using electronic alpha-counter* alphalogger* emanometer and plastic detector* LR-115 type II* Radon concentration level is being monitored daily at Amritsar* Punjab and other stations in Kangra valley* Himachal Pradesh. Radon anomalies are correlatable to some of the earthquakes which occurred in . the region. Radon diffusion from soil and groundwater and influence of meteorological variables on radon emanation have been studied to differentiate true from false anomalies. A network of ten radon recording stations is being set up in the highly seismic zone near the Main Boundary Fault in the Himalayas to forecast future earthquakes using radon as a precursor. Radon is posing a deep concern to human life from health-hazard point of view, it can prove as a saviour of human life if exploited for earthquake prediction.

33 THE FIRST NATIONAL INTERCOMPARISON OF RADON INTEGRATING DETECTORS IN RADON CHAMBER

Zhou jianliang, Li Xianjie and Qiu shoukang Uranium Mining Research Institute, CNNC P. O. BOX 48, postcode 421001 Henyang, Hunan, P.R. CHINA

ABSTRACT

A nation-wide intercomparison of radon integrating detectors (solid track etch, activated charcoal and thermoluminescence, etc. ) among 12 participants in China was conducted at Uranium Mining Research Institute (UMRI) in 1989. The paticipants intercompared their detectors in 6 exposure conditions ( low and high radon concentration , humidity and temperature) provided by UMRI radon chamber. Most of detectors showed a quite good reproducibil'ty. Exposure conditions seem to have influ- nce on some detectors, which application conditions could not be considered thor- oughly. Calibration of some detectors appeared to pose problems.

34 RADON MONITORING IN SOILS AND WATER

Heinz Surbeck Federal Office of Public Health Radioactivity Surveillance Section (SUeR) c/o Physics Institute, University Perolles CH-1700 Fribourg, Switzerland

Indoor radon measurement techniques are well developed. Reliable passive or active detectors are commercially available and there are generally accepted measurement protocols. Continous monitoring is widely used to study indoor radon transport.

Although the soil is known to be the most important radon source there are only few commercially available detectors for soil gas radon. Even fewer instruments allow for the simultanous measurement of the gas permeability of a soil, the most important factor determining underground radon transport. Dynamic processes like radon transport in the soil would best be studied with continous monitoring but work done on this subject is rare.

The situation is hardly better for radon-in-water measurements. Batch sampling and subsequent measurement in the laboratory is common practice but direct measurement in the field or continous monitoring is the exception.

This paper tries to explain why it is worth to improve measurement techniques for monitoring radon in soils and water and why there sould be an agreement on sampling techniques and measurement protocols. The problems with the methods currently in use are shown. New trends in this field and some applications are presented.

35 Wednesday, Sept 9

Neutron I (Chair: Schopper, E) Tommasino, L. (Rome): THE IMPORTANCE: OF TRACK DETECTORS IN RADIATION PROTECTION DOSIMETRY. (30) 41 Guo, ShI-Lun (Beijing), LATEST DEVELOPMENT OF NUCLEAR TRACK STUDY IN C3DNA INSTITUTE OF ATOMIC ENERGY. (30) 42 Tanner, R. J. (Own), NRPB PADC NEUTRON PERSONAL DOSIMETRY AFTER I- CRP60. (15) 43 Portal .G (Fontenajr-Aux-Roses): IMPLICATIONS OF NEW KRP AND KRU RECOMMENDA- TIONS ON THE USE OF S. S. D. T. DETECTORS FOR NEU- TRON DOSJMETRY. (10) 44

life Science/Neutron II (Chair: Cheng, Yulin)

Su, Chlng-Shen (Hsindiu): ALPHA PARTICLE RADIOGRAPHY OF SMALL INSECTS. (15) 45

Lin, Jun-Ylng (Shanghai), DISTRIBUTION OF URANIUM IN MICE USING THE FISSION TRACK TECHNIQUE. (10) 46

Zheng, Ii-Plng (Shanghai), TRACE URANIUM ESTIMATION IN BEVERAGES USING SS- NTD.O0) 47

Wang, Ma-Qi (Beijing), ATLD READER BASED ON SINGLE-CHIP MICROPROCES- SOR. (10) 48

Luszik-Bhadra, M. (Braunschweig), A WIDE RANGE NEUTRON DOSIMETER BASED ON CR-39 TRACK DETECTORS. (10) 49

Streubel, G. (Dresden) t NEUTRON DOSIMETRY BY MEANS OF CHEMICALLY ETCHED CR-39 MATERIAL PATRAS. (10) 50

Shi, Yong-Qian (Beijing), RESEARCH OF REACTOR POWER MEASUREMENTS BY SS- NTD. (10) 51

Moll«h, A. S. (Dhaka), USE OF CR- 39 TRACK DETECTOR IN PERSONNEL NEU- TRON DOSIMErRY. (10) 52

Majeed, A. (bfaumbad): NEUTRON SPECTRUM MEASUREMENTS USING ELECTRO- CHEMICALLY ETCHED CR-39-SPECTRUM UNFOLDING PRO- CEDURES. (10) 53

37 Nuclear Physics IU (Chair. Cui H. H. )

Gnba, B. (Beamd); TARGET FRAGMENTATION IN 3. 65 A GEV UC +mtb RE- ACTION. (10) 54

Mifthetjee, R. N. (Cukutta), STUDY OP COMPLEX PARTKXE EMISSION IN ALPHA IN- DUCED REACTIONS ON ALUMINIUM. (10) 55 Son, P. (Botocm): CALIBRATION OF THE CR-39 USED IN THE MACRO EXPER- IMENT. (10) 56 Zhai«, Du«-Hai (Talyun): THE MEAN FREE PATH OP ALPHA PROJECTILE FRAG- MENT FROM "O-Ern AT 60 A GEV. (10) 57

Hui, Wen-Stamg STUDY OF RANGE-ENERGY RELATION OF "Si HEAVY IONS IN TUFFAK POLYCARBONATE TRACK DETECTOR. (10) 59 QurcsM, I. E (Uamafaad), HEAVY ION REACTION SYSTEMATICS OBSERVED WITH SS- NTD. (10) 60

Radon HI (Chair: Espinosa. G. )

Han, Zhl-Heng (Gengyang): FAST AND MULTI-FUNCTIONAL METHOD OF RADON MEA- SUREMENT. (15) 61 Chlttrakam, T. (SongUa): LIGNITE AND TIN ORES EXLPLORATION IN SOUTHERN PART OP THAILAND BY USING NUCIEAR TRACK-ETCH DETECTORS. (15) 62 Segovia, N. (Mexico): RADON MONITORING RELATED TO A SUBDUCTTON ZONE IN MEXICO. (10) 63 Lu, Zu-Hul (Zhengdiou): PROSPECTING PETROLEUM OR NATURAL GAS RESER- VOIRS WITH CR-39. (15) 64 Helnfcke, J. (Fidberg): EXPERIENCES WITH RADON MEASUREMENTS FOR EARTHQUAKE PREDICTION AND LANDSLIDES. (10) 65 Klein, IX (BeUart): NUCLEAR TRACK DETECTOR FOR RADON MONITORING IN COAL MINES IN KOUZBASS SIBERIAN REGION (RUS- SIAN CONFEDERATION). (10) 66 Bullion, R. (Oaancai): CONTINUOUS MEASUREMENTS OF RADON CONTENT IN GROUNDWATER ON THE VOLCANIC SITE OF "FTTON DE LAFOURNAISE* (ISLAND OF REUNION, FRANCE). (10) 67 SeMd, J. L. (Montpdlkr): HYDROGEOLOGY STUDIES USING SSNTD AND ELECTRON- IC DETECTORS. (10) 68

38 Geosdence I (Chair: Brandt, R. )

i A. COMPARISON OF A NEW APPRO ACT FOR THE STUDY OF THERMAL HISTORY OF MINERALS WITH MORE STAN- DARD SIME-EMPIRICAL PROCEDURES. (30) 69 , V. P. (Dubm), THE STUDY OF NUCLEAR TRACKS IN CRYSTALS. (30) 70

Wan* SN-Ch««(BdJta«): RECENT PROGRESS ON APATITE FISSION TRACK ANALY- SE AND ITS APPUCATJON IN CHINA. (30) 71

Track Formation II (Chair: Chadderton, L. T. )

Schott, 3. U. TIME RESOLVING DETECTOR SYSTEMS, CHARGE COUPLED DEVICES IN STUDIES OF SINGLE PARTICLE EVENTS. (10) 72 Zhd, SCANNING TUNNELING MICROSCOPY STUDY OF HEAVY ION TRACKS. (15) 73

Fink, D. (BerUn); IRRADIATION OF PMMA WITH HIGH ENERGY LIGHT IONS, THE DEPTH DISTRIBUTIONS FOR VOLATILE REAC- TION-PRODUCT EMISSION. (10) 74

Dandrr, M. (Dubm), NEW RESULTS ON THE DESCRIPTION OF THE ETCHING PROCESS IN POLYMERS IRRADIATED WITH HEAVY IONS AND THE SYSTEMATICS OF PORE OPENING WITH THE HELP OF MODEL OF LOW ENERGY EXCITATION. (10) 75

Dunlop, A. (PlhtWMi). INFLUENCE OF THE IRRADIATION TEMPERATURE AND OF THE CRYSTALLOGRAPHIC STRUCTURE ON TRACK FORMATION IN METLLIC COMPOUNDS. (10) 76

Bermote.O. A. (Bucnw Aires)- DETECTION THRESHOLD. (10) 77

Bbfchoh, W. STUDY OF LATENT HEAVY ION TRACKS IN SSNTD BY SMALL-ANGLE NEUTRON SCATTERING. (10) 78

Geoscience II (Chair: Zhao, Y. L. )

ISgazd, G. (Pta). APPLICATION OF FT DATING TO ARCHAEOMETRYS PROVENANCE STUDIES OF PREHISTORIC OBSIDIAN ARTI- FACTS. (15) 79 Liu, Shwi-Shenc FISSION TRACK DATING OF HONGKONG GRANITES BY COMPARISON METHOD WITH STANDARD SAMPLE. (15) 80

KoriiMzu, S. (Ycfaaufca): COMPARISON OF THERMAL STABILITY BETWEEN INTER- NAL AND EXTERNAL SURFACES OF ZIRCON. (10) 82

39 Deng. Xin-Lu (Dalian) s COMPUTER SIMULATION OF THE ETCHING PROCESS OF THE FISSION TRACK. (10) 83

Grivct, M (Besunon): ELECTRON MICROSCOPY ANALYSIS OF KRYPTON ION

TRACKS INDUCED IN DURANGO APATITE. (10) 84 Long, Tian-Cal (Ttanjta). SOME PROBLEMS IN FISSION TRACK DATING. (10) 85 Hu, Rul-YIng (Guangzhou); FISSION TRACK DATING OF QUARTZ. (10) 86 Yan, Yurong (Beijing)» RADON MEASUREMENT IN SEEMOLOGICAL RESEARCH. (10) 87

Radon IV (Chair» Monnin, MM.)

Lu, Wd (Ttonjtn), USE OF SSNTD TO STUDY ENVIRONGEOLOGY OF CAR- CINOGEN RADON IN GEJIU AREA. (10) 88

Badr, I. (Birmingham). DETERMINATION OF THE SCALE OF VARIATION IN RADON SOIL GAS CONCENTRATIONS USING THE METHOD OF NESTED SAMPLING. (10) 89

Zhang, Zheng-Guo (Changsha): INVESTIGATION ON DISTRIBUTION OF INDOOR AND OUT- DOOR RADON CONCENTRATIONS. (10) §0

Abu-farad, F. (Dhahran), EFFECT OF CO* PULSED LASER ON THE REGISTRATION PROPERTIES OF NUCLEAR TRACKS OF CR-39. (10) 91

Feng, Yu-Shul (Belong), APPLICATION AND EVALUATION OF SOLID STATE NUCLE- AR TRACK DETECTORS FOR RADON MEASUREMENTS. (10) 92

Lu, Cun-Heng (Fuzhou). THE RELATION BETWEEN THE TRACK ETCHED DENSITY AND THE RADON CONCENTRATION. (10) 94

Han, De-Yuan (Beijing): INDOOR AND OUTDOOR RADON CONCENTRATION IN CHI- NA BY SSNTD. (10) 95

Zhang, Huai-Qin (Beijing), RADON-222 INDOOR CCWCENTRATION IN THE CIAE RE- GION OF BEIJING. (10) 96 J

Kcnawy, M. A. (Cairo), CR-39 AND LR-115 AS A SECONDARY STANDARD DOSIME- TER FOR RADON DOSE CALIBRATION. (10) 97

40 THE IMPORTANCE OT TRACK DETECTORS IN RADIATION PROTECTION DOSIMETRY

L. TOMMASINO

ENEA/DISP DIVISIOKE KETODOLOGIE E MISURE - VIA V.BRANCATI, 48 00144 ROMA

Damage track detectors exploit one of the most important properties of the nuclear track structure, mamely the high energy deposition along"the trajectory of high LET particles. The registration characteristics of these new detectors make it possible to solve some of the most complex problems of radiation protection dosimetry, such as the assessment of low concentrations of natural and man-made alpha emitting radionuclides and the measurement of neutron doses in the entire neutron energy range of interest. Unfortunately because of the recent ICRP recoramancations, the sensitivity of damage track detectors has become marginal. However, the unique- registration characteristics of damage track detectors may be used to good advantage to solve these shortcomings. LATEST DEVELOPMENT OF NUCLEAR TRACK STUDY IN CHINA INSTITUTE OF ATOMIC ENERGY

Shi-Lun Guo

China Institute of Atomic Energy P. O. Box 275(96), Beijing 102413, China

New progress has been made on nuclear track study in China Insti- tute of Atomic Energy in recent years, which includes: (1) Preparation of bubble damage detector for neutron detection; (2) Study of relativistic heavy ion interactions and neutron emission; (3) Study of reaction mechanism of 238U + ""'U at energy of 14. 2 MeV/N; (4) Heavy ion emission from nuclei; (5) Application of fission track techniques in large-area exploration of uranium; (6) Fission track dating of archaeological and geological sites; (7) Rn monitoring and its applications; (8) Development and production of nuclear track membranes at nuclear reactor and Tandem accelerator. Intensive and extensive studies and applications in different disci- plines have shown that nuclear tracks recorded in solids can provide plenty of new messages on the Nature.

42 NRPB PADC NEUTRON PERSONAL DOS1METRY AFTER ICRP 60

R.J. Tanner, D.T. Bartlett and J.D. Steelc

National Radiological Protection Board, Chilton, Didcot, Oxon, 0X11 ORQ, UK

The NRPB has been operating a routine neutron personal dosimetry service based upon the electrochemical etching of PADC (poly allyl diglycol carbonate) elements since 1985. This service covers approximately 1000 workers in the UK and abroad, requiring the issue of around 7500 dosemeters annually. It has performed relatively well in international intercomparisons with samples taken from routine stock. The publication of JCRP 60!1) has serious consequences for many operational neutron dosimetry services. The reduction in dose limits from 50 mSv to 20 mSv per year, the introduction of constraints and the requirements for dose estimation in some circumstances down to a few mSv per year, inevitably result in a need to estimate lower doses with greater precision. Additionally, the proposed change in the Q(L) relationship to be applied in respect of the 1CRU operational quantities will effectively decrease the (dose equivalent) sensitivity of detectors, the overall effect being a requirement for a fourfold increase in sensitivity over that currently necessary. Most PADC neutron services have struggled to meet existing limits because of high background variability and/or low sensitivity. This work covers the progress made at the NRPB in terms of meeting the challenge of ICRP 60: research has concentrated upon the pre-issue treatment of plastic in order to reduce background variability and the variation of cure cycles to enhance sensitivity and reduce background: particular success has been found by adopting the cure cycle developed by Ahmad and Stejny^. Additionally, research has been performed into improving the etch cycle in order to enhance the signal to noise ratio and also the energy dependence of response.

References 1. International Commission on Radiological Protection. ' 1990 Recommendations of the International Commission on Radiological Protection*. Publication 60 (1991).

2. Ahmad, A., and Stejny, J. 'Polymerisation Structure and Track Recording Properties ofCR39'. Nud. Tracks RadiaL Meas., 19 (1-4), ppll-16 (1991). IMPLICATIONS OF NEW ICRP AND ICRU RECOMMENDATIONS ON TOE USE OF S.S.D.T. DETECTORS FOR NEUTRON DOSIMETRY

Guy Portal Commissariat a l'Energic Alomique Insorut de Protection et de Surctc Nudcaire PO.BOX 6 92265 Fontcnay aux Roses France

ABSTRACT

The publication 60 of ICRP which includes new recommendations on the quality factor

concepi, annual dose equivalent limits and accuracy of measurements will introduce some changes in

the use of SSDT for neutron dosimetry. The energy response of the dosemeier will have ro be

adapted to the new "radiation weighting factors" defined in this document Tnc detection threshold

will have to be reduced by a factor approximately 10 to lake into account the reduction of the dose equivalent limit, the increase in the quality factor and the new accuracy requirements.

The introduction of the new "IsodirectionaT angular response concept for individual doscrocters, which is defined in the last recommendations to be published within the next few months, will change the requirements for this type of detectors

The author gives information on these new recommendations, analyses the implications of their introduction in the field of SSDT individual monitoring and draw conclusions for future research in this field.

44 ALPHA PARTICLE RADIOGRAPHY OF SMALL INSECTS

Ching-shen Su~

Institute of Nuclear Science, National Ting Hua University

HsinchUs, Taiwan, China f

Radiographies of small insects have been done with ;> radio-isotope 244Cm alpha source.

Energies of alpha particles were varied by attenuating the 5.81 MeV alpha particles

from the source with a stainless steel spacer to collimate the alpha particles passing

through the air spacing in its central hole. The cellulose nitrate film, commercial name

LR-115 from Kodak Pathe was used as the solid state nuclear track detector to register

radiographs. The image of the insect registered on the LR-115 was etched out in a 2.5

N NaOH solution at 52°C for certain minutes depending on the various parts of the

insects to be taken for the radiographs. Small insects such as ants, mosquitos, and small

bugs have been tried with alpha particles of energies from 3.5 to 5.5 MeV determined

by air spacings from 2.4 to 0.5 cm between the alpha source and the sample. For

larger insects, a scanning device for the alpha particle irradiation has been made which

includes a microscope stand to mount the alpha source and a scanning microscope stage to mount the sample. The distance from the alpha source to the sample can be adjusted to adjust the energy of alpha particles by the air attenuation, and the scanning period can be selected to give desired irradiation dosage. With this apparatus the radiograph of the whole body of a bigger insect was obtained. A CCDTV camera system connected to a microscope interfacing to a IBM/AT computer is used to register the microscopic image of the radiograph and to print out it with a vedio copy processor.

The experimental results show that the inner organ of the insects can be shown clearly by the radiographs. Examples of the sizes and the relative densities of the inner organs of an ant have been given.

45 DISTRIBUTION OF URANIUM IN MICE USING THE FISSION TRACK TECHNIQUE

Lin Junying, Cheng Yulin, Zhang Jiong, Liu Guaofu and Zheng lining Shanghai Institute of Nuclear Research, Academia Sinica, P.O.Box 800-204, Shanghai 201800, P.R.China

Cheng Xiaoyu Medical Physics,Department of Radiotherapy, Shanghai Sixth People's Hospital, Shanghai 200233. P.R.China and Hao Xiuhong Institute of Atomic Energy of China. P.O.Box 257(96), Beijing 102413, PJt.China

Abstract

Four groups of mice were dissected at various time intervals from 0, 5 to 144 hours after their intravenous injection of uranium.The uranium distribution and deposition in the tissues of kidney,lungfmarrow, liver, heart, muscle and blood have been studied using the fission track technique (FIT). Our experimental results show that trace uranium is deposited more likely in kidneys and Iung6 than in marrow and liver. The presence of uranium in the blood is so transient that blood-uranium level can not be used to estimate the degree of the storage of uranium in the body.However, the mice injected with high dose uranium die soon because the uranium poisons the hearts severely.

Keywords: fission track technique (FTT), uranium in tissues of mice.polycarbonate (PC) detector.

46 TRACE URANIUM ESTIMATION EC BEVERAGE USING SSNTD

Li-Ping Zheng, Jun-Ying lin and Yu-Iin Cheng Shanghai Institute of Nuclear Research, P.OJBox 800-204, Shanghai 201800, P.R.China

Xiu-Hong Hao Institute of Atomic Energy of China, P.CXBox 275, Beijing 102413 P.R.China

ABSTRACT

The U content of beverages and mineral water has been

estimated using the technique of fission track analysis

in polycarbonate plastic. The U content in beverages has

been found to vary from 0,26 ± 0.03 to 1.65 ± 0,07 ppb,

the average value is 0.93 ± 0.05 ppb. The mean U content

in mineral water is 9.20 + 0.16 ppb,which is 10 times

higher than the mean U content of beverages. The present

study shows the high U content in mineral water, indicating need for further investigation of U contsnt in mineral water for the studies of radiation health hazards.

Keywords

U-<:ontentf beverages, mineral water, polycarbonate detector(PCD)

47 A TLD READER BASED ON SINGLE-CHIP

WsnQ Jioqt, Wu Furong, Zhso Jienxinne, Li Yusn'sno,

Research Institute of Chemical Defence Bejing, China

The TLDB are used on more and more fields, including the militory application, in China now and it requeree a TLD reader with the high eignal-to-noiee ratio, stability, reliability, adaptability and automaticity. For this, the RGD3 TLD reader baaed on a single-chip microprocessor is designed. A set of semiconductor cooler h utilized in the reader for adjusting temperature of the TMP to keep it at lfi°C and avoid the dark current raited with the temperature and humidity of environment. And a special deeign eliminates the condensation in the dark room of the TMP while the current- frequency (I/F) converter overcosuee the leakage of electricity caused by the effects of environment temperature and moisture. The RGD3 reader can work at up to 4G°C and RH 95%.

Users can conveniently set up your heating programme with a keyboard on the front panel. With a stardard RS232-C interface, a IBM compatible computer may conmunicate with the reader and can all-timely acquire and procese the readouts and the grow curves. To fit verioue TLD detectors with different size, shape and spectrum, the heating tray and light filter can be easily replaced.

The RGD3 TLD reader is fittable to the National Stardard GB 10264 (equals to the IEC 1066).

48 A WIDE RANGE NEUTRON DOSEMETER BASED ON CR-39 TRACK DETECTORS

M. Lus2ik-Bhadra, W.G. Alberts, E. Dietz, S. Guldbakke, H. Kluge Physikalisch-Technische Bundesanstalt, W-3300 Braunschweig, Germany

A neutron dosemeter based on an electrochemically etched CR-39 detector covered by 3 mm air, 300 pro Makrofol, 3 mm polypropylene and 1 nun cadmium had shown a reasonably small energy dependence of the dose equivalent response from thermal up to 15 MeV. ' The energy dependence of the dosemeter response has been further improved and the energy range extended to higher energies. As an additional detector for high energy neutrons a 100 vim thick Melinex foil has been introduced, which is partly covered by a gold and a lead foil and indicates fast neutrons by recording recoil and reaction particles heavier than a-particles and fission products above the fission thresholds. To improve the angle dependence a dosemeter with a half cylindrical shaped CR-39 detector has been constructed, using as a thermal converte the air in the half cylindrically shaped hole towards the body of the wearer and an albedo capsule with collimated albedo windov/. Preliminary results obtained with quasi monoenergetic neutrons in the energy range between thermal and 66 MeV are presented.

'M. Luszik-Bhadra, W.G. Alberts, E. Dietz and S. Guldbakke. A Track-Etch Dosemeter with Flat Response and Spectrometric Properties. Nucl. Tracks Radiat. Meas. 19 (1991) 485-488.

49 NEUTRCN D03IMETRY BY MfcANS OF CHEMICALLY ETCHED CR-39 MATERIAL PATRAS

G.Strejbc;, B.Porschrl, T.Hahn, H.Hartmann, K.Kadner Dresden University of Technology* Institute of Radiation Protection Physics, Germany

Dosemeters based on chemically etched CR-39 material PATRAS (made in Germany) have been shown to be suitable for operational neutron dosimetry. The energy dependence CM ti-.cc rir.spmpter response could be reduced by optimizing :'<"'S etching and evaluation conditions. For instance, the track diameter distributions differ for several energies what can be utilized for selection of optimum evaluation conditions. Under these conditions the energy dependence of the dose equivalent-related response does not exceed + 25 "/. in the energy interval from 40 keV up to 2.5 MeV.

For ea=roie5 above 2.5 MeV the response decreases. At 14.7 MeV it is lower by a factor of about 3 than the value in the energy range from 40 keV to 2.5 MeV. The angular dependence of the directional dose equivalent-related response is influenced by the neutron energy. For low energies (E<2 MeV) a decrease of the response occurs up to 25 7. for an angle of 90° compared with the value of per— pendicular neutron incidence, whilst in the case of 14.7 MeV neutrons the response is approximately independent on the angle. A lower limit of the dynamic range of 0.1 mSv (for Cf neutrons) was obtained. The linear measuring range reaches up to 200 mSv. The accuracy of the dosemeter reading was estimated considering the influence of combined systematic and random errors.. The investigations of the combined energy and angular uncertainty shows that the required upper limit of the uncertainty of ±31 7. is not exceeded with exception of high energies (E>5 MeV).

50 RESEARCH OF REACTOR POWER MEASUREMENT BY SSNTD

SHIYONGQIAN

China Institute of Atomic Energy Beijing

In a reactor nuclear reaction produces nuclear fission and releases large energy .Rela- tion between reactor power P and fission rate F is

P"P0F (1)

There Po is the energy released in a nuclear fission . it bears a relation to fissible material . if available fission energy is 197 Mev. for a Thermal reactor loaded uranium , then

10 Po «= 0.321 x 10 " (wt • S)/afission Once fission rate is measured, the reactor power can be determined

We measure fission rate Fo of unit volume of fuel element in reactor a point by

SSNTD and use relation orF0/Ftsq>0/q> , After we measured is mean neutron flux in the moderator of the reactor core.

The SSNTD is fit tightly against cross section of the fuel to measure Fo .Tracks NT on the SSNTD are

r f 0 (2) There "L is macroscopic fission cross section S is SSNTD area.it is equal to across section of the fuel element t is linear length of the fuel element T is irradiation time £ is SSNTD efficiency tj is a bsorbself correction factor

Since Fo is fission rate of unit volume . We take product st is unit volume . Therefore

NT is tracks recorded on the SSNTD by fission of unit volume fuel element. The £17 is a definite value for definite detector and fission source . First we detect erj in the reference neutron field . When we irradiate the SSNTD with fuel clement. we also irradiate Au foil to measure neutron flux . NT) Ef,

.after we count the tracks on the SSNTD . The Fo is detected . we given F and F finally. We also given P.

51 USE OF CR-39 TRACK DETECTOR IN PERSONNEL NEUTRON DOSIMETR^

A. S. Mollah and M. M Kasim*

Institute of Nuclear Science and Technology, GPO Box 3767, Dhaka-1000, Bangladesh * Atomic Energy Centre, GPO Box 164, Dhaka-1000.

Personnel neutron dosimetry aims at providing a n-i' Lo Bvaluats lh« j'lES'tii Luds '_• f Ir.c Jt; Lr i rrcr. ta i effects on the personnel exposed to neutrons. Of all the recoil particle track detectors, CR-39 has shown considerable promise for personnel neutron monitoring due to its high sensitivity to protons. There are several laboratories in which operational trials using CR-39 track detector have been already started. At the Atomic Energy Research Estafcl -ishment ,'AERE). about 80 persons working with reactor, neutron generator and laboratory neutron sources (such as Am-Be, Cf-252 and Ra-Be) are being monitored using a CR-39 track detector. In order to use this detector as a personnel neutron monitoring, the dosimetric properties of CR-39 oetector have been investigated using Am-Be(4.20 MeV), Cf-252(2.1O MeV) and D-T (14 MeV) neutrons. The calibration data have been applied to personnel monitoring of fast neutrons at AERE. The experience achieved during an operational test of CR-39 track personnel neutron dosimeters is also described in this paper.

52 NEUTRON SPECTRUM MEASUREMENTS USING ELECTROCHEMICALLY ETCHED CR-39 —SPECTRUM UNFOLDING PROCEDURES

A. Majeed, S. M. Ahmed II S. A. Durrani

Institute of Industrial Automation P. O. Box 13M, hltmibid. Pakistan.

Department of Physics, University of Birmingbim, Birmingham BIS 2TT, U.K.

Electrocbemically etched CR-39 detectors can be used to measure neutrons either of a definite energy or from a broad energy spectrum. The measurement of energy spectra using this technique is, however, a relatively new area and has numerous problems yet to be solved, the most important being the spectrum unfolding. This paper describes the spectrum unfolding procedures developed for neutron spectrometry based on the measurement of ECS spot density in an electrochemically etched CR-39 detector used with a radiator and a degrader. The procedures have been applied to the measurements of neutron spectra of standard isotopic sources. The unfolded spectra have been found to be in reasonable agreement with the published data.

53 12 2Ofi TARGET FRAOMENTATION IN 3.65 A GEV C+ ""pb REACTION

B. GrabeX Ins1.it.ute of Physics, P.OJtox 57, 11001 Beograd, Yugoslavia

We investigated the emission of intermediate mass fragments from the *vPb target Induced by 3.65 A GEV G projectiles. For this purpose we used the. stacks of CR-39 plastic track detector. The events are classified according to the number of present heavy fragments. charge,angular and multiplicity distributions of fragment are presented. The correlations among fragments are also examined and analyzed. -With respect to the obtained result the possible mechanisms of the events production discussed.

54 STUDY OF COMPLEX PARTICLE EMISSION IN ALPHA INDUCED REACTIONS ON ALUMINIUM R.N. Mukherjee, T.K. De , and 8.B. Baliga Saha Institute of Nuclear Physics, l/AF, Bidhannagar Calcutta - 700 064, India 1. B.M. Mahavidyalaya, Midnapore - 721 655, West Bengal, India

The production of complex particles ranging from Li to 0 emitted in the reaction of 60 MeV alpha particles on an aluminium target has been experimentally studied using CR-39 (DOP) Solid State Nuclear Track Detectors, Energy spectra of the emitted fragments were measured in the angular range of 40° - 170° at an interval of 10°. The double differential cross-section data, which are Maxwe - llian shape, were fitted with a phenomenological moving source model [Ref. T. Kozik et al., Z. Phys. A 326 (1987) 421]. The results have been compared with those obtained by a gas AE - silicon E telescope. It is found that the results obtained by SSNTD's match remarkably well with those obtained by other detectors. Moreover the limitations of gas detectors in obtaining the energy spectra for low fragment energies are not present in the case of SSNTD's because of obvious reasons. As a result the data around the Coulomb bend could be obtained which has an important theoretical significance.

-1;

55 CALIBRATION OF THE CR39 USED IN THE MACRO EXPERIMENT

C.Capiluppi', H.Dckhissi*. G.Giacomelli^, EJCatsavounidis^, 2 1 J 2 LPalrizii , FJPredieri*2, P.Serta ^ t M.Spurio >

1) Dipariimemo di Fisica, vJmeiio 46, Bologna 2) INFN, sez. di Bologna, vimerio 46, Bologna 3) California Institute of Technology, Pasadena, CA 91125. USA

We present new calibration results of the CR39 nuclear track detector, made by the INTERCAST Co. of Parma, used in the MACRO experiment at Gran Sasso. High velocity and low velocity ions have been used. Results are also presented on the determination of the total and partial

charge changing cross-sections of 28sil4+ jons of 14 5 GeV/nucleon and of 32S16+ ions of 200 GeV/nucleon in CR39. Upper limits on the production of nuclei with fractional charge have also been obtained.

56 The Mean Free Path of Alpha Projectile Fragient Fro* *0-Ea at (0 A Gev

EMU01-collaboration

D.H. Zhang", M.I.Adaaovich", H.K.Aggarwal4, Y.A.Alexandrov", N.P.Andreeva1, Z.V.Anson', R.Arora4, F.A.Avetyan", S.K.Badyal1, E.Basova", K.B.Bhalla1, A.Bhasin', V.S.Bhatia', V.G.Bogdanov*, V.l.Bubnov1, T.H.Burnett", X.Cai", I.Y.Chasnikov', L.P.Chernova", M.M.Chernyavski", B.Dressel", G.Z.EUgbaeva1, L.E.Ereaenko1, E.M.Friedlander', A.S.Gaitinov', E.R.Gajissnuge", S.Garpaan", S.G.GerasiBOv", J.Grote", K.G.Gulamov", S.K.Gupta', H.H.Heckian',H.Huang", B.Jakobsson", B.Judek", S.Kachroo1, F.G.Kadyrov", G.S.Kalyachkina', E.K.Kanygina1, M.Karabova1, G.L.KaulM*.Kaur', S.P.KharlaBOv", T.Koss", S.A.Krasnov1, V.Kuaar1, P.Lai', V.G.Larionova", V.N.Lepetan1, P.J.Lindstro»', L.S.Liu", S.Lokanathan1, J.Lord0, N.S.Lukicheva", S.B.Luo", L.K.Mangotra', N.A.Marutyan", N.V.Maslennikova", I.S.Mittra', S.Hookerjee1, C.Mueller", H.Nasrulaeva", S. H.Nasyrov", V.S.Navotny", G. I.Orlova", I.Ollerlund", H.S.Palsania', N.G.Peresadko", N.V.Petrov", V.A.Pl'yushchev1, W.Y.Qian", R.Raniwala', S.Raniwala1, N.K.Rao1, V.H.Rappoport", J.T.Rhee", N.Saidkhanov", N.A.Salnanova", L.G.Sarkisova", V.R.Sarkisyan*, W.Schulz", G.S.Shabratova*,T. I.Shakhova1, B.Singh', D.Skelding", K.Soderstro«", Z. I.Solovjeva'.E.Stenlund", S.C.Strauss0, J.F.Sun8, L.N.Svechnikova", K.D.Tolstov*,M. l.Tretyakova", T.P.Trofimova", ll.Tuleeva"; S.Vokal1, H.Q.Wang",Z.Q.Wengs, R.J.KilkesB, G.F.Xu', P.Y.Zheng1, S. J.Zhochova", D. C. Zhou".

1). Alia-Ata, lnst. of High Energy Physics, U.S.S.R. 2). Beijing. Acadeaica Sinica, People's Republic of China. 3). Berkeley, Lawrence Berkeley Lab., U.S.A. 4). Chandigarh, Panjab University, India. 5). Changsa, Hunan Education Institute, People's Republic of China. 6). Oubna, JiNR, U.S.S.R. 7).Jaipur, University of Rajasthan, India. 8). Jauu, University of Juuu, India. 9). Leningrad, V.G.Khlopin Radius Institute, U.S.S.R. 10). Linfen, Shanxi Noraal University, People's Republic of China. 11). Lund, University of Lund, Sweden. 12). Marburg, Philipps University, B.R.D. 13). Mosscow, Lebedev Institute, U.S.S.R. 14). Otto*a, NRC, Canada. 15). Seattle, University of Washington, U.S.A.

57 16). Tashkent, Institute of Nuclear Physics, U.S.S.R. ]?>. Tashkent, Physical-Technical Institute, U.S.S.R. 18). Wuhan, Hua-Zhong Noraal University, People's Republic of China. 19). Yerevan, Physical Institute, U.S.S.R.

Abstract In EMU01 eaulsioa stack exposed to beaa of "0 nuclei with aoientua of to A Gev/c, 1135 heliua fragaents froa 1466 "0-Ea collisions have been recorded. These fragaents were followed until they interacted or left the stack. Aaong these fragaents there are 250 heliua fragaents interacted with eaulsion.Statistical analysis of the aean free path of these fragaents were perforaed. The evidence was found for the anoaalously short aean free path in first few centiaeters of the point of eaission for alpha fragaents.

58 STUDY OF RANGE-ENERGY RELATION OF 28Si HEAVY IONS IN TUFFAK POLYCARBONAET TRACK DETECTOR

Wen-Sheng Han Beijing UniverEi'ty of Aeronautics and Astronautics, Beijing , CHINA Shi-Lun Guo Chita Institute of Atocic Energy, P.O.Box 275(56), Beijing 1024IS, CHINA

The application of solid state cue Jeer track detectors iSSKTDs.) has cooe into core and core wide use in nuclear physics researches, especially in distingushing particles emitted from nuclear reactions, spontaneous decays and in cosmic rays. SSKTDs hare shoirn their disticctire advantages ic these researches. Most of these studies are based on the relationship between the range 2nd energy of the particles in the detectors. Therefore, it is very ioportsnt to study the range - energy relation of various heavy ions in the detectors.

We have ceasured the range of 28Si in Tuffak polycarbonate track detector by using the bead of aBSi scceUi&ted ic HI- 13 Tandem accelerator in China Institute of Atonic Energy. Theoretical calculation of range - energy relation has beeL carried out. It shovrs that the results of EeasureceDis sre consistent with that of theoretical calculation.

59 HEAVY ION REACTION SYSTEMATICS OBSERVED WITH SSNTDS

I.E. Quresbi1), S. Manzoor2), HA Khan2) }) NPD-PINSTECH, P.O.Nilore, Islamabad, Pakistan 2; NED-PINSTECH, P.O. Nilore, Islamabad, Pakistan

We have analysed the track parameters of the reaction products in the case of a number of interacting nuclear pairs at energies in the range of 10-20 MeV/u. This has been done by using Mica and CR-39 detectors. The partial and total cross-sections alongwith the kinematical quantities derived from the computerized analysis of track data has been used to understand possible modes of reaction mechanism.

The analysis of elastic scattering data using semi-quanta! models is performed in order to derive quarter-point angle which is an additional parameter related with total cross-sections. The comparison of experimental total cross- sections with theoretical values is also performed. The variation of derived physical quantities as a function of projectile energy is discussed with regard to apparent systematics.

60 FAST AND MULTI-FUNCTIONAL METHOD OF

RADON MEASUREMENT

Zhiheng Tian Detao Xiao Fuqi Zo Xiuliang Zhao (Hengyang Institute of Technology)

Abstract

In the Fast and Multi-functional Radon Measurement Method

the21* Po+ positive ions were collected by the static electric field

produced by electret. The response facter abtainned with this method

is as high as 4. 70 cm'^Bq^'m'h"1 av-A so the sensitivity of Radon

measurement is improved largely. The lower detection limits for

Radon concentration measurement (for lOh sampling)and Radon flux

rate measurement (for lh sampling) are 0.13 Bqm~3 and

0.14mBqm~2s~1, respectively. Ths. method has been widely applicat-

ed. In Qinshan Nuclear Power Plant, the environmental Radon back-

ground level before the start up of Nuclear Power Plant was mea-

sured « it is shown that Radon concentrtions were of wind—direction

dependence.In Hunan Province Environmental Monitoring Central Sta- tion, the distribution of Radon Concentration in the different locations inside a house, the distribution of indoor and outdoor Radon concentrations with height and the Radon flux rate from building material were measured. In Uranium Mines ,the Radon flux rates from mine piles .cliffs,stone pits*waste stone areas and pool water surfaces were measured. The methld is specially convinient for field use for its light weight ,high sensitivity, short sampling time and complete passive sampling.

61 LIGNITE AND TIN ORES EXPLORATION IN SOUTHERN PART OF THAILAND BY USING NUCLEAR TRACK-ETCH DETECTORS T. Chittrakarn, R. Boonnummar, T. Pongsuwan, P. Nuannin, S. Arrykul* and P. Poenthong** Physics Department, Faculty of Science, * Mining and Metallurgy Department, Faculty of Engineering, Prince of Songkla University, **Electrical Generating Authority of Thailand, Krabi Province.

Both lignite and tin mines in southern part of Thailand are associated with uranium ore. In Unite exploration, Bangpudum Lignite Hine at Krabi Province was chosen for this studied because we know the exact location and deposition of coal seam by using other geophysical technique and also confirm by borehole. The size 1x2 cm* of cellulose nitrate CN-85 films were used, each film was sticken at the inner bottom of a softdrink cup. Each cup was put up side down at the bottom of a borehole about 75 cms. depth from the earth surface and laid about 10 m. apart. All the cups were put in the hole along the line in order to cover about 280 metre in the cross sectional direction . long of the known coal seam. After one month, all the film detectors were collected and etched with NaOH 6.25 N at 60°C about 25 minutes long in order to enlarge the latent alpha registration tracks. These alpha particles decay from radon gas (Rn-222) in which generated from uranium that associated with lignite ore. The registration track density per area of each cup was studied by light microscope at 400x magnifications. We found that track density of each film have high correlation with the depth of the known coal seam while high and low track densities will correspond to the depth and shallow coal seam respectively. Also track denstiy was significantly higher than background. A similar manner of experiment was densigned for tin ore exploration at Ronpibul district, Nakorn Si Thammarat province. The result is in progress and will present at the conference.

62 RADON MONITORING RELATED TO A SUBDUCTION ZONE IN MEXICO

N. Segovia*, M. Mena**, E. Tames* *ININ, Ap. Post. 18-1027, 11801 Mexico, D.F., MEXICO **IGFUNAM, Ciudad Universitaria, 04510-Mexico, D.F., MEXICO

The southern part of the mexican Pacific coast - -- represents one of the most seismologically active in the world due to the subduction of the Cocos Plate under the North America Plate. Several years ago, a radon in soil monitoring network was initiated in this area, showing correlations between - the emanation fluctuations and the local seismicity. In -- particular, associated with the 1985, Michoacan, Mexico -- earthquake (Ms=8.1), a precursory radon in soil signal has been recognized. After this earthquake, 40 acelerographs were installed in the zone and, associated with them, a new dotation of radon in soil stations have been also -- operating. At present, the radon monitoring network consists of 54 stations located along the coast, and two transversa lines joining Mexico City to the coastal emplacements of Acapulco and Lazaro Cardenas. These two places are located at the so called Guerrero seismic gap. Radon determination has been sistematically performed with SSNTD exposed in the field for periods ranging from 15 days to one month. The alpha tracks are then etched and spark counted. In the present paper, results of radon in soil - -- fluctuations observed in the zone, in the last two years, are shown and discussed as a function of the local geology, environmental factors and local seismicity.

63 PROSPECTING PETROLEUM OR NATURAL GAS RESERVOIRS WITH CR-39

Lu Zuhui, Vang Yujin, Li Youning, Xu Aijun Fundanental 4 Applied Science Research Institute of Henan, Zhengzhou University, Henan, P.R. China 450052

222 Radon{ Rn),as a decay daughter of uraniu»,its concentration in soil gas is usually an expression of the locally uranium( **%) concentration and the escaping of radon from soil grains that contain uranium. Hydrocarbon seeping from a petroleum or natural gee reservoir dilutes the uranium concentration and affects the notion of radon gas in the soil. It is possible to prospect deep petroleuns or natural gas reservoirs by speculating the radon concentration anomalies in soil gas(l). In this work, radon concentrations in soil gas were measured with CR-39 detector and its anomaly was analyzed to study the petroleum or natural gas geoloical structures in both Scihant&la Hollow, Inner Mongglie and Shengli Oil Fields, Shandong. In Augster, 1991, 15 radon detectors were placed in a prfile of Sahantala Hollow for 22 days on ground at 70CB depth beneath earth surface with & distance of O.ft km between cups. The caculated number of tracks in ecch detector is > 1000 in its aera of 2x2 cm2- and obtained the rodon concentration at a standard relative deference < 1.20 Bq.e'* . The result shows that the low radon concentration anoealy presents the petroleuc or natural gas deposit determined by other geological prospecting methods in the aera. In Shenli Oil Fields, Shandong. radon detector CR-39 and thermolooinescenct dosiiueter LiF were placed in the same plastic cylinder ei2x£G cm to accquire the total gaeuna-ray radiation of .soil, and the gataiaa-ray spctra of soil were collected with a High-purity Gcrtcaniuc Crystal Detector to analyze its amounts of natural radiotcents. The results show the distrabutions of petroleum or natural gas reservoirs in these ficrcs effectively. hfferences: 1. Fleischer, P..L enci Turner, L.G Geophysics, Vcl.-!&, ic.6, eiO-SI7(lSS7} EXPERIENCES WITH RADON MEASUREMENTS FOR EARTHQUAKE PREDICTION AND LANDSLIDES

Heinicke, J.; Koch, U. Saxon Academy of Sciences at Leipzig, Germany

Abstract

The interpretation of radon measurements in springwater and soil air in the vicinity of epicentres of microearthquakes are discussed. Important informations about the dependence of the radon concentration are obtained by the registration of various additional parameters (temperature, air pressure, precipitation) . Changes of the radon content in soil air can found an explana- tion based on a mathematical model of meteorological parameters. Stress induced radon anomalies are clearly recognizable by measurements in the ground water. Furthermore the paper presents experiences of radon measurements with SSNTD on geodynamic problems (landslides).

65 —NUCLEAR TRACK DETECTORS FOR RADON MONITORING IN COAL MINES IN KOUZBASS SIBERIAN REGION (RUSSIAN CONFEDERATION)

DJCLEIN1, N. ROUDKO2, A.CHAMBAUDET3 and S.MALAKHOV2

• 1- Laboratoire de Metrologie des Interfaces Techniques, IUT de Belfort-Montbeliard, University de Franche Comte, BP 527, 90016 Belfort, France 2- Ecological and Medico-Biological International Center of west Siberian, 65000 Kemerovo, Russian Confederation 3- Laboratoire de Microanalyses Nucleaires, UFR des Sciences et Techniques, La Bouloie, Universite de Franche Comte, 25030 Besancon Cedex, France

The principal source of exposure to radiations to radiations for both workers and civilians of mining areas is known to be the inhalation of radon and its short living daughters. The actual data stimulated research on radiation-induced human health risks from these exposures.

For this reason, a radon survey has been carried out over the Kouzbass coal mining area near Kemerovo. Radon measurements were performed in mines, schools and different dwellings, using specific cells with LR3J5 plastic track detectors. For each studied building, radon concentration level is measured on four points : in soil (outside), in the cellar, on the ground floor and in storeys. In mines, radon is measured in all galleries and in open air.

Some preleminary results are to be used in drawing cartography of radon emanation in Kouzbass Region and indicating the areas where protection measures are to be taken because of an abnormally-high radon level.

66 CONTINUOUS MEASUREMENTS OF RADON CONTENT IN GROUNDWATER ON THE VOLCANIC SITE OF "PITON DE LA FOURNAISE" (ISLAND OF REUNION, FRANCE)

R. BARILLON', S.VIOLETTE2, RNICOUNP, D.KLEIN*, A.CHAMBAUDET and J.P.CARBONNEL2

1- Laboratoire dc Microanalyscs Nuclcaircs, UFR des Sciences et Techniques, Li Bouloic, University dc Franche Comte\ 25030 Besanc,on Cedcx, France 2- Laboratoire de Geologic Appliquee, Univcrsite P. et M. Curie, 4 Place Jussieu T26, 75252 Paris Cedex 05, France 3-Laboratoirc de Geologic Structural et Applique*e, UFR des Sciences Universiic* de Franche Comi6, Place LccJcrc, 25030 Bcsanc,on Cedcx, France 4- Laboratoire de M6trologie des Interfaces Techniques. IUT de Bel fort Montbeliard, Universite de Franche Comte, BP 527, 90016 Belfort, France

In the framework of "R.E.M.M.I" program (French program t< study relations between water and magma in intertropica environment), different physical and chemical parameters (radoi level, conductivity, pH, CO2 level, temperature) are attended in i drainage basin of the "Riviere de 1'Est" which is a subterranean water in order to correlate their variations with the stress in the volcanic chain of the "Piton de la Fournaise".

In a first experimentation, during the no rainy days of the year the radon concentrations in water have been measured by nuclea; track detectors only.

In a second field work, during the rainy days of the year, complementary technique is added: a continuous measurement will a portable proportional counter.

The radon measure and the other measurements encourage th. tracing, in continuous, through various time steps of the annual cycle likely to be indicators of volcanic activity. This second step shouk begin in 1992, September in the framework of a new European Program.

67 HYDROGEOLOGY STUDIES USING SSNTD AND ELECTRONIC DETECTORS

J-L. SEIDEL, J-P. MORIN, M. MONNIN

Laboratoire d'Hydrogeologie - Centre National de la Recherche Scientifique • University Montpellier II - 34095 Montpellier Cedex 5, France

For more than two years two different experimental sites have been put under survey by monitoring differents classical hydrogeological parameters and by concomitant radon measurements both in top-soil above the wate liable and in the aquifer itself. One of the sites is located in a karstic area, the other in a granite mountain range.

Radon measurements were performed with SSNTD detectors for measuring long term variations, and with electronic probes for measuring short term variations.

The influence of the degree of fracturation of the bedrock is exhibited by the fact that the radon content in the karstic water was found extremely high and not supported by local U concentrations.

Radon surveyed in the groundwaters indicates a correlation between Rn concentration and distances from main drain of the aquifer in the case of the karstic aquifer, and from the main fractures network in the case of the granitic site.

It has additionnaly been found that Radon measurements in groundwaters can also provide informations on the feeding system of the aquifer and on the size of the watershed.

The different findings show that a radon survey carried out in the soil and in the water can very well become an efficient part of an hydrogelogy study.

68 COMPARISON OF A NEW APPROACH FOR THE STUDY OF THERMAL HISTORY OF MINERALS WITH MORE STANDARD SEMI-EMPIRICAL PROCEDURES

A.Chambaudet*, J.C.Miellou**, H.Igli**, M.Rebefez* and M.Grivet* * Laboratoire de Microanalyses Nucldaires, ** Laboratoire de Calcul scientifique, University de Franche-Comte1, U.F.R. des Sciences et des Techniques, 16 route de Gray, F-25030 Besancon Cedex

Our aim is to compare with more standard empirical or semi empirical procedures, a new approach for the study of the thermal history of the rock. This new approach relates the track length reduction, directly controlled by the temperature history, to a convection phenomenon, and the corresponding model describes both creation and annealing of tracks leading to the histogram of length distribution. In OTdeT to get the temperature history, we aTe led to solve an inverse convection problem for which the final state - i.e. the track length distribution measured on a sample of apatite for example - is known. The main unknown of this inverse problem is the convection speed, the history of which allowing to get a corresponding history of temperatures.

69 THE STUDY OF NUCLEAR TRACKS IN CRYSTALS

V.P.Perelygin Joint Institute for Nuclear Research, 141980, Dubna, RUSSIA

The problem of fast heavy nuclei track registration stability in natural end artificial crystals is generally discussed in the frame of four - zone model of tracks first suggested in 1972. The results on calibrations on sensitivity of crystals the efficiency of particle registration, the sources of background, the thermal stability of lathent track, the uranium content in crystals are reviewed. The data on track age and .fossil galactic cosmic ray nuclei tracks in crystals provide a very important information about the nucleosynthesis processes in our Galaxy, about the history of the Earth and about the charge and energy spectra of Galactic cosmic ray nuclei with 2^26 averaged over time intervals up to 200 M.Y. The dependence of volume etchable track length (VETL) on threshold annealing procedure and track orientation in crystalline lattice suppose to be very important for fossil and fresh track studies.

70 RECENT PROGRESS ON APATITE FISSION TRACK ANALYSIS AND ITS APPLICATION IN CHINA

Wang Shicheng, Kang Tiesheng and Jing Guiru

( Institute of High Energy Physics,Academia Sinica P.O.Box 2732, Beijing, China ) Apatite fission track analysis ( AFTA ) has been developed and applied in China since 19S5. Since then great efforts have been made on methodology and applications. 3 n order to improve the accuracy of fission track dating Zeta calibration constants have been determined against NBS SRH 962 standard uranium glass and seven age standards. TINT method and silver coating were used to increase the density and contrast of confined spontaneous fission tracks on apatite. Based on the fanning model of fission track annealing for apatite presented by Laslett, a forward computer modelling of track shortening and age evolution was completed and an in- version method of modeling thermal histories from apatite fission trsck data is underway. Apatite fission track data ( ages and track lengths ), zircon ages end forward modelling method have been used to reveal thermal and tectonic histories of several sedimentary basins and collision zones in China. In this presentation , some of above-mentioned results are presented and discussed.

71 TIME RESOLVING DETECTOR SYSTEMS: CHARGE COUPLED DEVICES IN STUDIES OF SINGLE PARTICLE EVENTS

J.U. Schott DLR FF-ME, Under H6he, 5000 K61n 90, FRG

Abstract

The design and the atomic composition of Charge Coupled Devices (CCDs) makes them unique for investigations of single energetic particle events. As detector system for ionizing particles they detect single panicles with local resolution and near real time particle tracking. In combination with its properties as optical sensor, particle transversals of single panicles are to be correlated to any objects attached to the light sensitive surface of the sensor by simple imaging of their shadow and subsequent image analysis of both, optical image and panicle effects, observed in affected pixels. As semiconducting storage devices of high charge sensitivity with an atomic composition and structure being similar to charge sensitive memory devices, CCDs permit to investigate single panicle effects in microprocessor and memory devices, minor effects as well as those causing fatal errors and malfunctions by changing charge states {Single Event Upsets) in complex panicle radiation fields, such as in space. For calibration purpose of the CCD as particle detector, radiation effects of ionizing particles in the pixels have been quantified. Applications are presented in the field of radiobioiogy wilh metabolizing seedling of Arabidopiis ihaiiana and with the investigation of single particle events in high integrated electronic components in space radiation fields.

72 SCANNING TUNNELING MICROSCOPY STUDY OF HEAVY ION TRACKS

ZHAI PEINGJI and TANG X1A0WEI

Institute of High Energy Physics, Academia Sinica Beijing 100080, PRC

Detailed understanding of the radiation damage and reparation from interaction between the heavy charged particle and the solid material is an important topic in material science, but it is difficult to directly investigate such a small regions of damaged material. Braunshausen et al. , and Barbu et al. , have reported their ob- sevation of heavy ion latent tracks in zircon and metal compound using high-resolution transmission electron microscope (TEM). But it is known that the electron beam might cause the track fading in the sample. With the advent of STM and AFM it becomes possible to observe directly the radiation damage of heavy ion tracks on an atomic scale. At first the low energy heavy ion tracks were studied: Wilson et al. , (1988, 1989) have given results of low energy heavy ion-bombarded PbS and Si/SiC^ by STM. Porte et al. , (1991) have reported STM observation of local damages induced on HOPG surface by low energy heavy ion implantation. For high energy heavy ion tracks we (1991) reported our observation of high energitic heavy ions impacts on MoS2 surface by STM. Not only atomic structures of the original surface, but also the structures of craters and the re-arrangements at the bottom of the craters are clearly shown in the STM images. Neumann et al. , (1991) heave also presented their STM studies on HOPG surface modifications caused by ions of high kinetic energy.

73 IRRADIATION OF PKMA WITH HIGH ENERGY LIGHT IONS: THE DEPTH DISTRIBUTION FOR VOLATILE REACTION- PRODUCT EMISSION

D.Fink1, L.T.Chadderton2, A.Schmoldt1 " Hahn- Meitner- Institut GmbH, Glienickerstr. 100, D-1000 Berlin 39, Germany S) Division of Applied Physics, CSIRO, P.O.Box 218, Lindfield, NSW 2070 and Laser Physics Center, Research School of Physical Sciences, Australian National University, P.O.Box 4, Canberra, ACT 2601, Australia

Mass spectrometry has been used as an analytical tool in determining the species and quantities of volatile reaction products generated during destruction of polymers by ion implantation. Specifically, one very important objective was to try to relate the radiation chemistry with the radiation physics of the fundamental process.

Experiments are described in which the depth distribution of the emission of volatile products has been determined for irradiation of PMMA with 35 MeV 7Li2+ ions. The mass spectral measurements of the reaction products were carried out on a thin polymer foil with thickness smaller than the ion range, as a function of the ion implantation direction in respect to the sample's surface normal. Correlation of the differences in mass spectra with the ion track length in the polymer yielded the depth distribution of degassing. Comparison with theory shows the volatile gas degassing to be related to the polymer destruction via electronic rather than nuclear energy transfer processes, though there does not exist oportionality between the depth profiles of degassing and those of electronic energy transfer.

74 New results on the description of the etching process in polymers irradiated with heavy ions and the systematics of pore opening with the help of the model of low-energy excitations

Manfred Danziger Joint Institut for Nuclear Research, Dubna (Russia) Laboratory of Nuclear Reactions

The interaction of heavy ion with solid produces a narrow radial core of primary damage. The actual nature of the damage and the mechanism of its formation is not yet fully understud. In some of the recent publications, the author has introduced a new model which is based on the theory that the incident ion causes a disturbed structure directly around its trajectory and is characterized by vitreous properties. Tt is termed as the model of low-energy excitations. A response function describes the reaction of the solid of the external disturbance, caused by the penetrating ion, which is calculated by the model. First during the etching process the local regions around the track generated by the heavy ion are activated which is connected with the generation of low-energy excitations. Therefore, in the special case investigated in this work there is a mediating process between '.i-.v external disturbance and the generation of low- energy excitations, the etctiiii^ process. The response function is proportional to the radial etching rate in the case of only single pore in the bvestigated solid. In the case of itigh pore density the radial etching ra e is proportional to the imaginary part of the Fourier-transformation of the response function. This phenomenon has been supported by experimental results. A method to determine the systematics of pore formation has been shown. The thin films irradiated with heavy ions have been etched by electrochemical technique and the first result obtained about the opening process of smallest track (0.5 nro) has been presented. A distribution function describing the number of micropores with respect to the etching time can be generated with the help of the model of low-energy excitations and the measured data on trans\ ersal effective etching rate versus pore radius. The results obtained for the range of pore radius between 0.5 nm to ]0 nm have been presented and discussed in this paper.

75 INFLUENCE OF THE IRRADIATION TEMPERATURE AND OF THE CRYSTALLOGRAPHIC STRUCTURE ON TRACK FORMATION IN METALLIC COMPOUNDS

A. BARBU, A. DUNLOP, D. LESUEUR and G. JASKIEROWICZ Laboratoire des Solides Irradies CEA /EcoJe Polytechnique 91128 Palaiseau, France

Latent tracks have been shown very recently to be formed in some metallic compounds irradiated with very high energy (GeV) heavy ions m: their creation is unambiguously related to the strong level of energy deposition in electronic excitations. These tracks have been observed in some intermetallic alloys which are known to be more or less easily amorphizable by irradiation with MeV electrons and a fortiori easily amorphizable by irradiation with low energy ions. This talk will emphazise two aspects of track formation: (i) in a few compounds that exist in various crystallographic phases, it will be shown that latent tracks are formed in one of the phases and not in the other one: track formation is related in this case to the structure ot the target. (ii) in a given crystallographic phase, or in a single phased compound, the formation of latent tracks is strongly temperature dependent. Finally, some tentative explanations of the mechanisms of track formation in metallic targets as a result of strong excitation of the electronic system will be presented: they emphazise the predominant role of collective processes in damage creation.

A.BARBU,A.DUNLOP,D. LESUEUR and R.S. AVERBACK Europhys. Lett. 15 (1) (1991)37

76 DETECTION THRESHOLD

O.A. Bernaola, G. Saint Hartin and J.C. Grasso National Atomic Energy Contission Av.Libertador 6250. Bs.As.<1429).Argentina

Considerable effort5 are devoted to the development of new materials searching for improved sensitivity, higher efficiency and lower detection threshold. Furthermore the attempts to predict the behaviour of the different materials when used as track detectors, employing a variety of registration criteria, are profuse. However, at present a definite and unequivocal interpretation of the track registration threshold is lacking. The replica technique for the observation of tracks by TEM, allowed the study of tracks in Makrofol E in regions of energy virtually "forbidden" by the traditional registration models. One or both critical extremes of energy were analyzed for particles such as protons, helium, deuterons and lithium, trying to find a correlation with any of the commonly proposed parameters to test detection threshold. The possibility of a different interpretation of the "threshold" origin in these opposite cases arises from the results obtained.

77 STUDY OF LATENT HEAVY ION TRACKS IN SSNTD BY SMALL-ANGLE NEUTRON SCATTERING

W. Birkholz1*, F. Haupler2), V.P. Perelygin2V S.G. Stetsenko2>« P. Vater3)

1) Technische Hochschule Leipzig, Germany 2) Joint Institut for Nuclear Research Dubna, Russia 3) Philipps-Universitat Marburg, Germany

Passing the SSNTD (solid state nuclear track detector) charged particles form latent tracks. The diameter and the length of these tracks vary with the atomic number and the energy of the particles. These latent tracks become visible in a light microscope by chemical etching. Only a part of the latent track is etchable.

In our studies we used the parameters of the etched tracks (diameter and length) for identification of the track inducing particles. The method of partial annealing of the latent tracks has been applied in investigations related to (fission) track dating and to the analysis of cosmic ray tracks in meteoritic minerals. The respective results de- I pend very critically on the fading of the latent tracks. Therefore the stability of latent tracks in SSNTD's stored for certain time at varying environmental conditions is of great importance and has to be studied.

The aim of our work is to investigate the formation of latent tracks by the use of small-angle neutron scattering at MURN-TEXT of JINR. This give information about the dependence of the latent track parameters on the energy loss along the particle path. Especially the study of the influence of partial annealing and of other environmental conditions on the storage of latent tracks over a long period requires the analysis of the latent tracks.

78 APPLICATION OF FT DATINS TO ARCHAEOMETRY : PROVENANCE STUDIES OF PREHISTORIC OBSIDIAN ARTIFACTS.

Bigazzi B.(l), Ercan T.(£)» Oddone M.(3), Bzdogan Ye§ i ng i1 Z. <(5^>

1-CNR, Pisa(Italy)?e-MTA. Ankara(Turkey); 3-Pavia University Favia i Italy); A-Istanbul University, Istanbul (Turkey) 5-Cukurova University, Adana (Turkey).

Obsidians have been widely exploited in prehistoric times for tool making. Several techniques, mainly based on chemical-physical charecterization, have been used for discrimination of the potential sources of raw meterial and for correlation of artifacts with them. FT dating is an alternative approach which proved to be very promising for the mentioned goals. Sevesal artifacts from Anatolian (Turkey) prehistoric sites have been analysed by the FT dating method and the results have been compared with the data referring to obsidian natural sources.

The conclusion of this resarch can be summarized es follows: 1) FT age and track densities well discriminate the occurences located in Anatolia £) Although the natural sources of this region are at present just partially known, FT dating allows us to indicate the provenance volcanic districts of many of the analysed artifacts 3) Other potential sources of the Hediterranian basin and of the Carpathian region ere not represented in the studied archaeological sample set. Comparison between the FT dating method and the trace element composition by Instrumental Neutron Activation Analysis shows that the combination of these two approaches is a powerful means for provenance studies of obsidian artifacts.

79 FISSION TRACK DATING OF HONGKONG GRANITES BY COMPARISON METHOD WITH STANDARD SAMPLE

Liu Shunsheng (Changsha Institute of Geotectonics, Academia Sinica, Changsha 410013,PRC)

In view of the difference of neutron fluene« measurement methods between the laboratories in the world, and the divergence of spontaneous fission decay constant ().[) of 23Su which are used in the formula for calculation of fission track age, it is more reasonable to use the comparison method of measured samples with a standard age sample. Besed on /• a 0) Pi

and , idiot - 1 =(-i-).«t (2). Pi ' If 2M where .* i; ie total decay constant of u, Xt spontaneous fission decay constant, t

fission track age, ps spontaneous fission track density, p, induced fission track density by thermal neutrons, I the natural ^u/23^ isotopic abundance ratio, a the cross section for inducing fission of asu with neutron at 2200 m / s, O integral thermal neutron fluence for sample irradiation in reactor, subsymbol std means standard sample, subsymbol unk measured sample, (1)/ (2) we obtain «

XD b pi s where a=«'"•" - 1, b = (^ ),*. For t^OO'yer and t,ld<10 ycr,

Pi p» Using the comparison method, we determined the fission track ages of several granites from Hongkong. The results are listed in following table.

80 Table Fission track ages of several granites from Hongkong by comparison method of standard sample Stand. Sample. No. of P. No. Mineral K. Pi Siand. Age Sample cm'* cm" No. P./Pi (Ma) (Ma) 1 HK-J Zircon J.5xJO* 485 3.26x10* 528 FC-3 0.299 ± 0.021 27.8±0.J 42.8 ±6.9 2 HK-2 Zircon 4.39 x JO' 1257 6.4x10* 918 FC-3 0.29910.021 27.8±0.1 63.6 ±8.6 3 | SK-4 Zircon 3.37x10* 1772 3.44X10* 879 FC-3 0.299 ±0.021 27.8 ±0.1 91±12

Because of restricts of conditions, the irradiated position of samples in reactor each time uncertainly is the same, and the physical parameters of reactor are not exactly known, the comparison method of fission track dating is a more convenient, in particular for geologists.

81 CO?:?AF:SON OF THERMAL STABILITY BETWEEN INTERNAL AND EXTERNAL SURFACES OF ZIRCON

Satoshi Koshimizu

Institute for Atocic Energy, Rikkyo University

Nagasaka 2-5-1, Yokosuka, 240-01 Japan

r-T igea ye re measured for both internal and external surfaces

of zircon crystals in quartz-diorite t-araples obtained from central

Japan (Koshinizu,1990). These data suggested that ages tightly cluster

around 3.8 Ma for internal surfaces and around 7.4 Ha for external

surfaces. This age discrepancy can be experimentally elucidated by

thermal stability difference in internal and external surfaces of zircon.

To establish a coinparison of thermal stability between internal and

external surirces of zircon, i hr annealing experiments for spontaneous

and induced fission tracks on both the surfaces of zircon were undertaken

in this study.

At temperatures between 200' C and 8C0* C, the density of spontaneous;

and induced fission tracks is reduced on both internal and external sur-

faces This reduction, however, takes, place at lower temperatures on in- '

ternal surfaces of zircon. This suggests that external surface is more

stable with respect to thermal influences and that tiscion track closure temperatuies vary between internal and external surfaces of 2ircon. COMPUTER SIMULATION OF THE ETCHING PROCESS OF THE FISSION TRACK DENG XINLU DEPARTMENT OF PHYSICS.DALIAN UNIVERSITY OF TECHNOLOGY 116023 DALIAN,CHINA

This paper introduced a method which can simulate the etching process of the fission track and compute the etching curve (i.e. the etched track density vs the etching time) for external detector using microcomputer. In addition, various distributions (for total length, Horizontal projection, vertical projection and incident angle) of the damage trail, the etchable track, the etched track and observable track were obtained. A important conclusion that the etched track (pit) density ( f€ ) is generally less than the etchable track density ( R_) was drawn and formulated as follows:

where

= J t/f R5 T

6t the critical angle, T the thickness of the source, Rs the range of the fission fragment in the source, Ra the ranqe of the fission fragment in ths detector, vt the etchinq velocity along the damaqe trail, tm the etching time, Nf the number of the fission action in unit volume of f the source material.

83 ELECTRON MICROSCOPY ANALYSIS OF KRYPTON ION TRACKS INDUCED IN DURANGO APATITE.

M. Grivet, ML Rebetez, A. Chambaudet and N. Ben Ghouma Laboratoire de Microanalyses Nucleaires.UFR Sciences et Techniques, Universite de Franche Comte", La Bouloie, 16 rte de Gray 25030 Besancon CEDEX, FRANCE

Nuclear tracks can be observed in minerals containing uranium like apatites, sphenes and zircons. In such a case, it is the isotope 238 of this element which spontaneously produces two fission fragments ejected in opposite directions. Consequently, a population of spontaneous latent tracks is recorded in the mineral throughout its history. These tracks can be observed with an optical microscope after an appropriate chemical etching. The determination of the etched track density enables the mineral to be dated. Secondly, latent fission tracks are sensitive mainly to time and temperature, that is, the etchable length of an individual track is shortened by an amount determined by the time/temperature it has experienced. The study of their characteristics can thus provide important information on the the mineral's thermal history. In order to study this annealing phenomenon, tracks were generated in Durango apatite, normally to the surface, by heavy ions accelerated at GANIL (Caen, France), after a total annealing of the spontaneous ones. 86Kr was chosen as it is similar to spontaneous fission fragments with an energy of 1-2 MeV per nucleon. Measurements of the etching speed of track diameters were taken for several annealing rates, by observation of Pt/C replica with electron microscope. This work is aimed at showing the link between the default distribution, obse/ved through the etching speed, and the degree of annealing, and at describing the kinetic of fission track annealing in apatite. SOHK jfrOLLiSiiS I1J i'lSSIOW ThACK lMlTIKG

Long Tiancai (Tianlin Institute of Geology and KLneral Hosourc

Abstract In recent years, the author dated the -t'englai basalt in Shandong Province and the Uatong volcanic rick in Snanxi -rirovince by using fission track method. Uder different etching conditions, the results is varied for zircon. To the former dating samples, i.e.the Penglai basalt * the etching condition of zircon are:

•iF:H1SQf=1: i,200 0, 1%. Its error of age is some 3O'/». Other a sampl:es,. i.e. the itetong volcanic rock, the etching conditions of zircon are: K0:i:Ka0H=1:1, 190 C, 19h. Tts error of age is about i5/». In addition, some geological factors also affect the dating results in some senfie, as well.

85 rISSlON TRACK DATING OF QUARTZ

Hu Ruiying, Cheng Jingping 1st. of Geochemistry, Chinese Academy of Sciences Guangzhou 510640, China Guo Shilun, Hfio Xiuhong China Institute of Atomic Energy, P.O. Box275(96), Beijing 102413, China

Fission track dating of quartz from a quartz ?eic containing gold has been carried out by using artificial heary quartz grain6 of 100-200 Mm in size. After separation from the rein, the quartz graitB were mounted in epoxy, and ground, polished and then etched in 65%NaOH at70'C for 210 mints. After etching, spontaneous fission tracks in the surface of quartz were counted under an optical microscope, at 1000 magnification (oil immersion). Fieeioc track age of fire quartz samples separated from the quartz rein containing gold in Hunan Province, Chins, are 115. 8+ 17. 3 Na, 107.4 ±19.4lia, 10S. 2± 16. 8 Ma, 160.7124. 8 Ma and 98.1 ± 20. 2 Ma respectively. These rake are lover than the age of theie mineralization which is estimated to be more than 200 Ma. Uranium content and distribution in quartz from a quartz vein containing gold in Xinjiang, China, have been studied by means of induced fimoc trsck6. The uranium contents are 6.1 ~ 12.4 ppb for quartz of mineralization and 2. 0 ~ 3. 9 ppb for quarts of un - mineralization, respectively. Uranium in mineralized samples distributes along uc- transparent metal minerals and clearage fractures, and looks like sadial and tight cumulus; while the distribution of uranium in un- mineralized samples is dispersive. According to the distribution of fission tracks, we ceo occlude that gold GOTCB together and beneficiatCE with uranium.

86 RADON MEASUREMENT IN SE1SMOLOG1CAL RESEARCH

Yang Yurong

(Center for Analysis and Prediction, SSB)

Abstract

The measurents of radon contents in groundwater and soil g&s are broadly used in seismlogical research in China. 1. In the study of earthquake precursors, variations of radon contents have been timely observed before earthquakes, but phenomena of some cases without radon changes or some changes without earthquakes also exsist. So anomaly changes of radon (or other gases) contents must be studied on concentration in space; on relations with anomaly phenomena of geoelectricity. groundwater. animal behavour, earth light and sound etc.; and on relation with seismicity. 2. In the study of fault activity, plane linear distrabution of radon content anomalies can be used for determination of fault (or buried structure) strike; the uneven distribution of radon contents along fault strike can be used for study of active segment; the fault- ing activity can be studied by radon content changes with time in a certain segment. 3. The measeurement results of radon content in epicentral area shou that attenuation of radon contents, from epicentre area, are quite similar with that of isoseismic line after occurrence of earthquakes, so it will help to evaluate intensity. Some further studies on relation between radon contents variation and earthquakes are also discussed.

87 USE OF 8SNTD TO STUDY ENVIROKGEOLOGY OF CARCINOGEN RADON IN GEJIU AREA Lu Vei Vang Zhengting Chen Ming Tienjin Institute of Geology and Mineral Resources Chinese Academy of Geological Science

Abstract Gejiu area of Yunnan Province is famous region for lung

cancer endemic disease. Over it2OO people have died from lung cancer for years in succession and radon has been proved a cause for lung cancer by medicine. This paper has measured seasonal variation in level of release radon from different rocks and ores in Gejiu by SSKTD and relative radon level in soil(red soil) at different seasons and variant elevation as well as indoor radon level* Auther have in 1990 to 1992 sealed CR39 SSlJ?Ds(made in China) into drill holes of variant rocks and ores,the time set are from seven days to a month.The level of radon release in summer from oxidised ores,glances, network veins and dolo- mites, marbles, granites are high up to 180 pCi/1 to 540 pCi/l and veathered granite is 600 pCi/1. V.'hole fall but in winter to 100 pCi/1 generally. Soil radon are 300 pCi/1 to 100 pCi/1 ficm summer to winter. In sum, subterranean radon level is higher in summer than winter. It is because of that radon go up with ascending air from soil in winter then the radon level in soil become lower than summer.This disccery is significan much more houses in Gejiu area have indoor radon level up to 8 to 12 pCi/1 even 20 or 24 pCi/l. According to study of envi rongeology author propose " Effect of plateau atmospheric pre ssure cooperate with fracture belt". Further study will find a way to prevent from radon calamity.

88 DETERMINATION OF THE SCALE OF VARIATION IN RADON SOIL CAS CONCENTRATIONS USING THE METHOD OF NESTED SAMPLING

l.Badr. S.A.Durrani, G.L.Hendry' and M.A.Oliver** School of Physics and Space Research University of Birmingham Birmingham B15 2TT, England Department of Earth Sciences/ Department of Geography University of Birmingham

Abstract

The scale and pattern of radon soil gas concentrations in the field have been determined using the statistical method of nested sampling. This technique allows these parameters to be economically determined over several orders of magnitude by incorporating a spatial scale in the nested analysis.

The study involved sampling radon concentrations in soil at 108 individual points across a 225 km square-grid in the Hereford and Worcester area of the English Midlands The survey was limited to a single geological formation, viz. the Old Red Sandstone, in order to simplify the interpretation of the results. Seven spatial scales (or 'stages') were used in the nested analysis. The entire survey was completed within a five week period in order to minimize the effect of seasonal fluctuations.

The soil gas concentrations were determined using the "can technique" - a simple passive detection system employing solid state nuclear track detectors. This technique allows radon gas to diffuse through a filter into a can, which contains a 2 cm x 2 cm piece of CR-39 plastic. The can unit is buried at a depth of 50 cm by placing it at the bottom of a 70 cm long PVC tube, of which the upper 20 cm projects out of the ground and is closed at the top in order to prevent the rain, etc., from getting in. Alpha tracks from the decay of radon gas were then etched electrochemically.

The results of our measurements show that 957. of the total variation in the activity concentrations occur over a scale of less than 10 m - the distance between the closest sampling points used. If the results, which were quite unexpected, are confirmed by further measurements at othsr locations, our nested sampling analysis would imply that the radon seems behaves erratf-ally over small distances. One would then have to conclude that there is little evidence of spatial correlation in the measurements, and that it is unsafe to estimate radon exhalation values at intermediate points by interpolation. If so, many of the surveys reported in the literature would be subject io question.

89 INVESTIGATION ON DISTRIBUTION OF INBOOR AND OUTDOOR RADON CONCENTRATIONS

Zhang Zheng'guo, Zhang Liang, Li Chunxiu Hunan Central Enviioiunental Monitoring Station China Xiao Detao Hengyang Industry College, China

ABSTRACT

Measurements of outdoor radon concentrations at different heights in the field and of indoor radon concentrations at different locations involving three houses were performed with electret track etching detector and CSR detector.

The results show that outdoor radon concentration is decreasing with height, the ratios between concentrations at different heights are 4.3 for 1.5 m to 10m, 1.4 for 0.8 m to 1.5 m and 2.4 for 0.3 mto 1.5m respectively. The indoor radoji (_ omeutrations at different locations in a house are also different; the values of radon concentrations at the end position of bed close to wall is the highest, being 1.6 and 2.9 times higher than those under the ceiling under both unventilation and ventilation conditions respectivelj'. EFFECT OF CO2 PULEED LASER ON TEE REGISTRATION PROPERTIES OF NUCLEAR TRACKS OF CR-39

F. ABU-JARAD, S.M.A. DURRANI AND M.A. ISLAM Energy Research Laboratory / Research Institute King Fahd University of Petroleum and Minerals Dhahran 31262, Saudi Arabia

ABSTRACT

Effect on alpha and fission fragments tracks for CR-39 nuclear track detectors irradiated with 10.6 /tm CO2 pulsed laser has been studied in the energy range of 60 mJ to 2 J per pulse for different exposure times. It has been found that sample surface structure including track sizes and shapes did not change for the energies below 180 mJ/P for the total energies up to 3500 J. While the surface has shown crystalline like structure and significant changes in track sizes and shapes for the energies greater than 180 mJ independent of the exposure time. Moreover, for a given sample, at different locations from the laser beam spot, track sizes has indicated Simultaneous hardening and softening of the material.

91 APPLICATION AND EVALUATION OF SOLID STATE NUCLEAR TRACK DETECTORS FOR RADON MEASUREMENT

Feng Yushui (Laboratory of Industrial Hygiene, Ministry of Public Health,Beijing 100080) Meng- ffenbin and Qin Changzhu (Liaoning Institute of Labour Hygiene, Shenyang 110005) The method , etohing conditions, and calibration of solid state nuclear track detector (SSNTD) of CR-39, and the results of fielduse and inten comparison measurements are desoribed in the paper. Optimum etching conditions have been found to be 6.25 N KOH solution temperature of 75*C. and duration of 6 hours. Calibrations wrer carried out using standard radon chamber at the Sixth Institute of Nuclear Industry. Calibration factors are derived from the track density divided by the radon exposure. The mean and the standard deviation of calibration factors is 3. 50±o. 42 tracks » cm^k Bq h • m3, With the integrated radon concentration detected at ±50S» relative standard deviation as the detectable lower limit, if background track density B is<10tracks • cm2, background standard deviation S&=0. 28, 500 microscopic fields area A=0. 245cm*, and exposure period is 1 month, then sensitivity is below lOBq-m'. The results of inter comparison measurements of samples showed that the relitive error was less than 2O5» as compared with the reference value. The results of field measurements showed that radon concentration in houses with walls surfaced with white ceramic tiles was higher than that in control houses. The maximum concentration in bathroom for radon spring hydrotherapy was found to be 793.7Bq«m* . The maximum radon concentration in bed room coupled with hot spring bathroom was found to be 336.9Bq»nf3 . Oractice has shown that SSNTD is suitable for radon measurements in various enviroments and places because of its high sensitivity, reliabi1ity,and easy operation.

Key words:SSNTD, calibration, etching condition, application evaluation. THE RELATION BETWEEN THE TRACK ETCH DENSITY AND THE RADON CONCENTRATION

Lu Cunheng

East China College of Geology

This paper gets some computation formulas on the relation between the track etch density and the radon concentration. For example, in the infinite radon medium, they exist as following.

In the formula j — the track etch density; N — the radon concentration; K — the radio of the range of a-particle in the air and that in the plate; t ~ shining time; d] and d2~ the length of the dark track for inable and enable etch part. INDOOR AND OUTDOOR RADON CONCENTRATION IN CHINA BY SSNTD

Tian Deyuan

Laboratory of Industrial Hygiene , Ministry of Public Health 2 Xinkang Street , Deshengmenvai Beijing 100088 > China

ABSTRACT

This paper detials that both Laboratory of Industrial Hygiene , Ministry of Public Health , China , and Department of Nuclear Engineering , Faculty of Enginerring , Nagoya University , lapan , cooperated to measure in- and outdoor radon concentrations in some places of China from Nov 1989 to Feb 1990 by means of electrostatic integrating radon monitor ( E1RM ) . The EIRH is a passive radon monitor which accommodates a cellulose nitrate film ( Kodak LR115 type 2 ) placed in the electrostatic field to collect charged Po-218 . Alpha particles of Po-218 ionize to form track in the film which is enlarged by etching for 3 hours at 60'C in 2.5 N MaOH solution . Each films exposured 2 months count by a microfiche ( Minolta RP405E ) having a magnification of 24 times . Radon concentration of exposured point is evaluated according to track density on the film . Lover detectable radon concentration of passive method is 1.2 Bq/M* for a 2-month-exposure . The annual mean out- and in-door radon concentrations employing passive method at Beijing , Nanjing and Xi'an et al cities of China are 8.0±2.5 and 22.6±3.4 , 6-4+1.3 and 13.7+5.3 , and 11.2+3.0 and 23-9±?.7 Bq-'M* et al respectively . On the other hand , a nationwide survey program of radon and its daughter concentrations in environment was conducted from 1986 to 1989 by instant method , such as scintillation cell or two-filter method et a] . It is well-known that the former's result is out of accord with the letter's . However , very good results were got if the latter's results make several corrections , for example annual and daily variation one et a] . The annual mean radon concentrtions by instant method at "dative to above places are 8.1 ± 4.1 and 22- 5± 18.1 , 13.0+9.6 and 17.0+14.0 , and 19.9+14.7 end 24.8 ±16.9 respectively . It is considered that both passive and instant method results coincide very well within error range . RADON-222 INDOOR CONCENTRATION IN THE CIAE REGION OF BEIJING

Zhang Huaiqin Chen Ling

(China Institute of Atomic Energy, P.O.Box 275, Beijing, 102413, China)

Abstract The passive radon monitor constructed by a solid state nuclear track detector has been used for the measurement of the radon concentration in residential houses in China Institute of Atomic Energy (CIAE) region. The sampling points have been selected for different floors and different kinds of building materials of a few typical style residential houses. Firstly, the variations of the radon concentration sampled in one room, but located at different distances to the window, have been measured. Then, a point near a central lamp has been choosed as a routine sampling point. The indoor radon concentration measured in a randomly selected samples oi 80 CIAE houses have been found to range from about 16 Bq/m3 to 209 Bq/m3 with a arithmetic mean value of 49 Bq/m3. The annual effective dose equivalent may be estimated about 1. 4 mSv. CR-39 AND LR-115 AS A SECONDARY STANDARD DOSIMETER FOR RADON DOSE CALIBRATION

M.A. Kenawy*, H.M. Eissa, M.A. Sharaf, M.A. El-Fiki and M.L. Abd El-Hady

* University College of Girls, Ain Shams Univ., Cairo, Egypt. National Institute of Standards, Cairo, Egypt.

Abstract: CR-39 and LR-115 were used for the calibration of radon dose in the secondary standard radon chamber designed and constructed at N I S Egypt. The response of both CR-39 and LR-115 SSNTD's for OS-particle registration have been estimated as 0.59 track/c<, 0.2 track/cC respectively. A reference standard 226Ra Source of activity 956Bq, has been used. Radon and daughter concentration as calculated has been compaired with these obtained by CR-39 and LR-115. It was found to be 50 pci/1, 49.73 pci/1 and 44.39 pci/1 respectively which proved that the CR-39 is more beneficial. Friday, Sept. 11

Track Developing I (Chair • Tommasino, L. )

Enge, W. (Kiel). ON THE FORMATIONS OF NUCLEAR TRACKS IN PLASTIC MATERIALS. (30) 103 Sohrabi, M. (Tehran). DISCOVERY OF SOME PHENOMENA IN POLYCARBONATE DETECTORS BY THE INTRODUCTION OF A NEW TRIPLET BCE TECHNIQUE. (30) 104 LI, Bo-Yang (Beijing). TRACK TREEING MECHANISM AND ITS APPLICATION. (30) 105

Filters (Chair: Zhang, Jiahua)

Vater, P. (Marburg).. NEW ACHIEVEMENTS IN INDUSTRIAL APPLICATIONS OF NUCLEAR TRACK MCROFITERS. (30) 106

Cheng, Yu-Lin (Shanghai). PRODUCTION AND APPLICATIONS OF SINGLE-PORE MEM- BRANES. (15) 107

Oiakarvarti, S. K. (Kurukshetra) - MICROFABRICATION OF METALSEMICONDUCTOR MI- CROSTRUCTURES: A NOVEL APPLICATION OF NUCLEAR TRACK FILTERS. (10) 108

Heise, S. (Marburg): ON THE DEVELOPMENT OF POLYPROPYLENE MICROFIL- TERS. (10) 109

Wu, Ri-Sheng (Beijing); APPLICATION OF NEW NUCLEAR TRACK MICROPOROUS MEMBRANE IN TRANSDERMAL THERAPEUTIC SYSTEM (TTS) STUDY. (10) HO

He, Gw-Kui (Beijing): STUDY OF THE SYSTEM FOR MEASURING RBC TRANSIT TIME THROUGH MICROPORES. (10) HI

Zhao, Chong-De (Beijing). STUDY ON PVDF NUCLEAR TRACK FILTER. (10) 112

Track Developing II (Chair: Liu, Shunsheng)

Espinosa, G. (Mexico); DEVELOPING ON THE INSTRUMENTATION FOR COUNT- ING AND ANALYSIS OF PARTICLE TRACKS IN SOLIDS. (15) 113

Maazei, R. (Buenos Aires) s SUBMICROSCOPIC NUCLEAR TRACK KINETIC THEORY. (15) Chong, C. S. (Penang); THE EFFECT OF X-RAY IRRADIATION ON TRACK FORMA- TION IN LR-115 TYPE II TRACK DETECTOR. (10)

Apel, P. Yu. (Dubna). EFFECTS OF ATOMIC HYDROGEN ON POLYMERIC TRACK DETECTORS. (10)

Ditlov, V. A. (Moscow): RESPONSE OF SENSITIVE SOLID STATE TRACK DETEC- TORS REGION AS A VISUALIZATION RESULT OF SOME PART OF ITS PHYSICAL STATES. (10)

Shweikani, R. (Birmingham): EFFECTS OF GAMMA IRRADIATION ON THE BULK AND TRACK ETCHING PROPERTIES OF CELLULOSE NITRATE (DAICEL 6000) AND CR-39 PLASTICS. (10)

Mahdl, S. (Tehran): A QUICK DYECET METHOD OF ECE TRACKS IN POLY- MERIEDECTECTORS. (10)

Raju, J. (ShiUong). VT (TRACK ETCH RATE). REFLECTION OF TOTAL ENER- GY-LOSS RATE (DE/DX) FOR 2S»U IN CR-39. (10)

Radon V (Chair: Khan, H. A. )

Jonsson, G. (Lund); STATISTICS AND ERROR CONSIDERATION AT THE APPLI- CATION OF SSNTD- TECHNIQUE IN RADON MEASURE- MENT. (RT) 12

Pollock, R. W. (Nbrtfabrook). PRESOAK STUDIES WITH CR-39 AND LEXAN. (RT)

Mahat, R. H. (Kuala Lumpur): LANDSLIDE PREDICTION BY SOIL RADON MONITORING. (RT)

Chen, Ling (Beijing)- THE MEASUREMENT OF EQUILIBRIUM FACTOR FOR RADON BY SSNTD. (RT)

Wang, Huan-Qiang (Wuhan). MEASUREMENT OF RADON ACCUMULATED CONCENTRA- TIONS IN AIR BY TURBIDIMETRIC TECHNIQUE. (RT)

Shang, Bing (Beijing) s CR-39 RN-222 DETECTORS. (RT)

Islam, G. S. (Rajshahl). INDOOR RADON MEASUREMENT IN THE NORTHERN RE- GION OF BANGLADESH. (RT)

Hassib, G. M. (Cairo); ASSESSMENT OF RADON CONCENTRATION IN EGYPTIAN DWELLINGS BY USING A PASSIVE TECHNIQUE (RT)

Andam, A. A. B. (Kumasi) • MEASUREMENT OF RADON FROM BUILDING MATERIALS IN GHANA. (RT) YegingU, Z. (Adana): USE OF CR-39 AS RADON AND RADON DAUGHTERS DE- TECTORS FOR INDOOR MEASUREMENTS IN A MILL IN ADANA. (RT)

222 Yaprak, G. (Izmil): MEASUREMENTS OF RN CONCENTRATIONS IN DWELLINGS IN A CITY WITH HIGH POPULATION. (RT)

Lu, Yang-Qiao (Beijing), SSNTD IS USED TO MEASURE THE RADON CONCENTRA- TION IN THE AIR IN THE AIR-CONDITIONED BUILDING. (RT)

MEASUREMENT OF INDOOR RADON CONCENTRATION BY Zhao, Yu-Hua (Beijing): CR-39. (RT)

Zhou, Uan-Jiang (Shijiazhuang)- a»TCENTRATION OF RADON IN THE SCENERY PLACE IN CHENGDE. (RT)

Detectors + Track Observation (Chair: He, Zehui)

Sun, Han-Cheng (Beijing); NUCLEAR EMULSION IN CHINA. (30)

Fujii, M. (Tohbafa). AGEING EFFECTS ON A NEW POLYMERIC TRACK DETEC- TOR SR-90 AND A MODEL OF THE NUCLEAR TRACK FOR- MATION. (30)

Ganssauge, E. (Marburg). A NEW APARATUS FOR TRACK ANALYSIS IN NUCLEAR TRACK EMULSION, BASED ON A OCD-CAMERA DEVICE. (30) in plastic materials ( Invited talk ) W. Enge Institut fur Reine und Angewandte Kernphysik, Christian- Albrechts- Universitat, D- W23OO Kiel, Germany

Since more han 25 years etched nucJear tracks in solids are known and there is still no unifying model to understand the formation of the etched tracks of heavy ions. A review about the present state of the art will be given together with a status report about our own work on this subject. Our measurements have been done in electrolytical chambers as well on single ion tracks as on many ion tracks. In our electrolytical chambers which are on line with computers, NaOH serves equally as etchant and as electrolyte. The break-through-time and the following temporal change of the electric current due to the enlargement of the etched tracks are measured and analysed. Theoretical and experimental problems and results will be discussed, espically for the detectors CR-39, Lexan and Makrofol.

103 DISCOVERY OF SOME PHENOMENA IN POLYCARBONATE DETECTORS BY THE INTRODUCTION OF A NEW TRIPLET ECE TECHNIQUE

M. Sohrabi and M. Sadeghi National Radiation Protection Department Atomic Energy Organization of Iran P. O. Box 14155-4494, Tehran Islamic Republic of Iran

ABSTRACT A new triplet electrochemical etching (TECE) technique has been developed at the National Radiation Protection Department (NRPD) in AEOI using a triplet ECE chamber (TECEC). It takes the advantage of the "internal heating effect" enhanced at higher frequencies and field strengths discovered recently (1,2). The TECE technique is a powerful tool and it provides new options for ECE of charged particle tracks especially at higher energies as well as the opportunity to generate and/or to observe fractally events in detectors like polycarbonate (PC). For example, the upper energy for registration of alpha particle tracks in PC detectors was increased from 2 MeV, by routine ECE procedures, to 5 MeV by the TECE with no pre-etching. By raising the temperature in the TECE technique through internally heating the etchant, interesting phenomena have been discovered in PC detectors such as real full-page fractal trees, crystal-type cracks, bubbling tracks, etc. In particular, the application of the newly dyed ECE track (DYECET) method (3), makes observation of such events in PC detectors colorful and distinguishable against the undyed surface. The generation of the real full-page trees on the PC surface, caused by a tree-type firing process, has been the most interesting. Generally speaking, the TECE technique has a high potential for broad applications especially for studying dielectric breakdown phenomena and physico-chemical characteristics of the ECE method. In this paper, the TECE technique is introduced and the results of our current research especially on the generation of the fractal events such as the firing trees are demonstrated and discussed.

~T~. H~. Sohrabi, Nucl. Instrum. Meth. in Phys. Research A 238 (1985) 517-523. 2. M. Sohrabi, Nucl. Instrum. Meth. in Phys. Research A 255 (1987) 225-230. 3. M. Sohrabi and S. Sadeghi Bojd, Nucl. Tracks Radiat. Meas. 17 (1990) 547-555.

104 Track Treeing Mechanism and Its Application

Chinese Hue1ear Society

Li Boyang

Abstract

Based on electrostriction and fracture mechanics, experiment, observation and data-processing, two models (inhibition among tree tracks and induction of tree traek onto stress concentrated points) and factors (inhibition and induction) are proposed; the existence of four types of plastic zone (spot-block pz,single crack isolate PZ, transtion fro* isolate to block PZ and crack-block pz) are pointed out; the development regularities of Gp (diameter of plastic zone), G(diameter of tree track), S(tree track density) and total areal of tree track (SG ) in two basic experiments (H=K+dH,H=Hc H-field strength) are described by using four basic formulae (dGr/dH= 2 CCdG/dT=CK'T* dS/dK'm=CS',d(SG )/dH

K-Stress strength factors) A Series of turning points (GrT.GT,HT,ST, Tj.T, and TJ are discovered. Hie physic meaning of the turning points,the essence of break -down during electrochemical etching and "water tree",the fatique and relation between stress and strain of metal material and the effect of loading mode on crack development are briefly discussed.

105 NEW ACHIEVEMENTS IN INDUSTRIAL APPLICATIONS OF NUCLEAR TRACK MICROFILTERS

P.Vater (speaker), CLaue, Uacobs, S.Heise, HJiang*, and R.Brandt Kemchemie, F.B.14, Pbilipps-University, D-3550 Marburg, Germany J.Roesch and J. Haag RWE-ENERGIE AG, Kraftwerk Biblis, D-6843 Biblis, Germany

Nuclear Track Micro Filters (NTMF) made of Kapton (polyimide, manufactured by Du Pont) are appb'ed to analyze the prime loop water of a nuclear power station for its content of Pu and Cm isotopes as well as solid particles. The filters were produced in the usual manner: irradiation with heavy ions (at UNILAC, GSI Darmstadt) and subsequent chemical etching. After filtrating a few litres of prime loop water the NTMF has to dry in open air. The radioactivity of the loaded filter was measured by means of a- and 7- spectrometers, resp. The collected solid particles were investigated for their chemical composition with the help of a scanning electron microscope with attached EDXA (energy dipersive x-ray analysis) equipment The plutonium content in the filtrate was studied, too, using conventional plutonium chemistry. First results indicate the capability of Kapton-NTMF to retain most of the plutonium activity. An a-spectrum of a loaded Kapton filter will be shown. Furthermore, it will be given a summary of the elemental composition of the solid contaminants.

China Institute of Atomic Energy, P.O. Box 275-26, Beijing, China

106 PRODUCTION AND APPLICATIONS OF SINGLE-PORE MEMBRANES

• Yulin Cheng, Junying Lin, Chunfa Ding, Bufa Zhang, Rong Lu, Liping Zheng and Xiuhong Hao* Institute of Nuclear Research, Academia Sinica P.O.Box 800-204, Shanghai 201800, P.R.China *China Institute of Atomic Energy, P.O.Box 275(96), P.R.China Abstract

Single-pore membranes (SPMs) are produced by etching 15 /jm think, 25 mm diameter foils of polycarbonate (PC) which have been irradiated with collimated one single-fission fragment from U(n,f) reaction. The fast neutrons (14MeV) are 4 produced in a neutron generator by the T(d,n) He reaction. The neutron fluences are controled in the range from 10 to 10 n/cm . The etching is performed at (70+5)°C in a solution of 5 mcl/L KaOH. Pore diameters are a function of the etching time. A suitable time is needed to give the desired pare size. Single-pore Membranes have several outstanding applications. SPKs can be used in biology and medicine, as counting apertures for measuring the number, size, mobility, and deformability of biological particles suspended in solution, and for characterizing, counting and identifying different cancer cells and viruses; in vaccum technology, as calibration leaks with a leak ratio defined by the pore size; in mass spectrometry, as gas-inlet leaks with standing pressure differences of several atmospheres; in laser technology, as pinholes; in cryogenics, as investigating the superfluidty in liquid helium. At present, SPKs have been used as microccllimators for single particle techniques. We are applying the SPK technique to searching and diagncseing senile dementia. This is one new development in using SPM technique.

107 MICROFABRICATION OF METAL-SEMICONDUCTOR MICROSTRUCTURES: A NOVEL APPLICATION OF NUCLEAR TRACK FILTERS

S.K.Chakarvarti and J.Vetter* Department of Applied Physics, Recional, Encineerinc College,Kurukshetra-132 119,India. * GSI.D-6100, Darmstadt, F.R.Germany.

Microstructures consisting of metallic or non- metallic elements like microsized

devices, needles, tubules ana fibrils provide a large variety of applications in the fields of diverse nature. Their fabrication techniques are mainly based upon optical, :•:— rays,electron and ion—beam 1ithography.Of late, electrochemical depos it ions of metals into the etched pores of nuclear track fi 1 ters(NTFs) have opened a new possibility of using them as potential tool in such fabrication processes producing ensembles of stochastically distributed homogeneous as well as heterogeneous nano/rd cro-structures.With the advancement, when ion-beams in write-mode are made available, it is expected that structures of desired configuration and size may also be produced.We report here the synthesis of Be-Cu heterostructures and Se microtubules using this technique with the pores of Makrofo-1 NTT as templates for growth.

108 ON THE DEVELOPMENT OF FOLYfKur XJUCIXJL MICROFILTERS S. Heise3> ICK. Dwivedi1^, P. Vailer!>, R, Brandt^ and C. Dankmeyer3* "Kernchemie, FB 14, Philipps-Universitat, 3550 Marburg, Germany 2>Department of Chemistry, North-Eastern Hill University, Shillong-793 003, India. 3>Deutsche KapiHar Plastik GmbH & Co.KG, 3563 Dautphetal 1, Germany

In an attempt to produce thick nuclear track microfilters, we have used strips of polypropylene tube manufactured by DEKA Plastik Co. Germany. As polypropylene is resistant towards solvents, strong acids and alkalies, therefore, its filters are expected to find new industrial applications. The main difficulty lies in performing a suitable chemical etching of such resistant material in order to develop the latent trails into well defined micro-holes.

Thin strips (50-200 /jm) were scraped off from polypropylene tubes (0 50 x 1.8 mm) and were exposed to ^Bi ions (13 MeV/u) at UNILAC, GSI, Darmstadt. The irradiations were done at angles of 90° and 45° and the ion fluence was kept between 2 x 104 to 106 cm"2. These polypropylene strips were then successively etched in an oxidizing etch solution kept at a temperature of 70°C. Starting with a strip of SO (im, in about 6 hours of etching the residual thickness was about 50 ^m and well defined microholes became visible having average inner and outer diameters of 8 txm and 16 urn respectively. The tapering angle (e) of the pores was found to be 8-10° and the etch-rate ratio under the present etching condition was measured to be about 6.

So far we have succeeded in developing about 150 //m thick filter of polypropylene film for nearly 200 »m range of Bi ion. A brief report of our experimental observations will be presented.

109 APPLICATION OF NEW NUCLEAR TRACK MICROPOROUS MEMBRANE IN TRANSDERMAL THERAPEUTIC SYSTEM (TTS) STUDY

Wu, Risheng Zhou, Jian Ke, Wei (Institute of High Energy Physics, Academia Sinica)

With the advantages of providing therapeutically effective- dose of drug at a constant rate over long period, while avoiding the side effects of drug and being more convenient than oral or other treatments, the research and application of TTS have been developed rapidly in the past decade. The key component in the TTS is the controlled release membrane which is used as the drug matrix• Now the condensed membranes, such as EVA, Silicon rubber membrane and porous membrane, are used for this purpose. These membranes all have good zero order release, but their release rate can only be regulated conveniently by the changes of the area of the TTS tape. For example, Anti- hypertension Agent Catapres TTS, has the following group of products, dose: 0.1 mg/24h, area: 3.5 cm2; dose: 0.2 mg/24h, area: 7 cm2; dose: O.3mg/24h, area: 10.5 cm2. New nuclear microporous membrane not only have good zero order release, its release dose can also be regulated conveniently by changing its number of pores or the porosity instead of increasing the area of TTS tape. The result of minimum expense of auxiliary materials and minimum skin irritation will be obtained. For example, nuclear track microporous membrane is used as controlled release membrane in clonidine TTS, zero order release rate is obtained • and the clonidine TTS retains smallest area', about 2 cm2 while the dose of clonidine changes: O.lmg/h, 0.2mg/24h and 0.3mg/24h. Therefore, the cost of clonidine TTS is decreased and its quality is improved.

110 STUDY OF THE SYSTEM FOR MEASURING RED BIX)OD CELL TRANSIT TIME THROUGH MICROPORES

Gao-Kui He, Xiao-Jian Huang, Bao-Liu Chen, Yu-Lan Wang, Tian-Cheng Zhu Institute of Atomic Energy, P.O.Box275(94), Beijing 102413, CHINA

In the human microcirculation of the red blood cell ( RBC) , the deformability of RBC is a important measure to diagnose a disease. We recently developed a new sj'stem, Measuring System of RBC Deformability (MSRD), the principle of the apparatus is based on electrical conductance change of a nuclear track filter when RBCs are passing through the pores of the filter, by which the passing time of individual erythrocyte and its distribution can be measured with the aim of determinating the deformability of RBC Sub-population and its influence on the distribution of RBC Theological properties.

Ill STUDY ON PVDF NUCLEAR TRACK FILTER

C.-D.Zhao. S.-L. Guo ( China institute of Atomic Energy. Seijing 102413 )

P.Vater. R.Brandt ( Kernchemie FB1 4 Philipps-Universitaet Marburg. 3550 Warburg)

It is well known that the nuclear track illters(NTFs) have been widely used in science and technology due to their unique advantages compaired with other conventional filters. Recently, a new kind of NTF, polyvinylidene fluoride(PVDF) NTF, has been developed by us. It is a very attractive one in the NTF family because of its special properties, in particular, electrical properties. The main properties of PVDF will be summarized. The recipes, etching and technical parameters will be reported. The possible applications will also be briefly discussed.

1.12 DEVELOPING ON THE INSTRUMENTATION FOR COUNTING AND ANALYSIS OF PARTICLE TRACKS IN SOLIDS

G. ESPINOSA IKSTITOTO DE FISICA, UNAM. Apdo. Postal 20-364 01000 Mexico, D.F.

A bottleneck in the method of detection of ionizing radiations by tracks in solids is the counting and analysis of tracks in the detector material, such as polymers, glasses and minerals. The purpose of this paper is to present an over-view of the methods that have been developed for the reading and characterization of the tracks formed in the detectors, in different laboratories since the late seventies. The physical principles and implementation of each method are emphatized. Following the chronological of their initial use the review includes, among others, the direct and simplest reading methods, such as optical microscopy, spark counting; more complex methods as electronic microscopy, densitometry, electrical field changes the partially computerized methods, such as automatic counting, and automated counting systems; and the fully computerized methods, such as image digitalisation and opto-electronic systems. In this cases, the physical characteristics of the tracks, the etching process (chemical or electrochemical) and the applications are considered.

113 SUBMICROSCOPIC NUCLEAR TRACE KINETIC THEORY R. Mazzei Departamento de Radiobiologia. Comision Nacional de Energia Atomica. Buenos Airee. Argentina A theoretical description for submicroscopic kinetics of track formation is described for very short etching times (new born tracks) and also for long etching times. On the other hand the variational principle was used to obtain the equations for the track profile. Track profile obtained by means of the variational principle and the submicroscopic track theory are in good agreement. Moreover, three theoretical methods are reported which yield, by a computer program, the theoretical submicroscopical track profiles for velocities of chemical attack which vary with the position on the incidence axis (x) of the ion and the perpendicular distance measured on the axis. It can simulate tracks for cases in which there are changes in the physical damage owing to statistical changes or states changes in the incident ion charges.

114 THE EFFECT OF X-RAY IRRADIATION ON TRACK FORMATION IN LR-115 TYPE II TRACK DETECTOR

C.S. CHONG, MARI15A A.C. CHAN and L.F. TAN School of Physics Universiti Sains Malaysia 11800 Penang, Malaysia

ABSTRACT

A study has been made of the etch track formation in LR-115 Type II polymer which has been exposed to high doses of X-rays prior to a-irradiation. The bulk etching rate after exposure to about 8 MR of X-rays is found to be three times that of an unexposed polymer. The ratio V_/V increases T £ only slightly with exposure. The diameter of the track opening increases exponentially with exposure.

115 P. Yu.Apel, V.I.Kuznetsov, V.G.Luppov, A.V.Levkovich,

V.A.Altynov and O.L.Orelovich

Joint Institute for Nuclear Research, 141980, Dubna, Russia

Effects of atomic hydrogen on polymeric track detectors were

investigated. Polyethylene terephthalate, polycarbonate and

polypropylene films with the thickness of 8-10 fim were beforehand

irradiated by xenon ions with the energy of 1 MeV/amu. The films were treated with a flux of thermal hydrogen atoms generated in a high frequency dissociator. The behaviour of the polymer samples was studied under chemical etching of heavy ion tracks. It was found that chemical reactions initiated by the atomic hydrogen can influence both the etching rate of the polymer jflatrix and the etching rate of charged particle tracks. The conclusion was made that the processes of generation, diffusion and interaction of mobile radicals (such as hydrogen atoms) should be taken into account when the formation and the structure of an etchable track in a polymer is considered. I

116 AS A VISUALIZATION RESULT OP SOMii .FAKT ur xxa rjusi

V.Ditlov

Institute of Chemico-photography Industry Moscow, Leningradskij pr.47

Sensitive region of solid state track detector is known to transit spontaneously into state "yes" or on the contrary, to return from state "yes" into state "no" in some time after exposure. This effect is explained to a great extent by visualization process and by inner physical state of sensitive region. On derivating expressions for sensitive region response probability it is necessary to consider total events quantity including not only events ?ion. caused ionizing particle but also spontaneous ones ?„,. The effectivity of events is to be BP considered in respect of a certain visualisation process realising access from some statistic states assembly described by function on some vector ~H* , therefore:

Vector components are time, temperature and other physical characteristics. So, in some cases transition of sensitive region from state, yielding to visualization process, into state not causing sensitive region response, is to be considered as a decay of the first one. The dependence of such processes on time is described be exponential law, therefore: - tA ?(t,r) =?.on e + ?8p(t,T) (2)

Thus, to develop approach (Ditlov V.A., 1980) in the present paper we generalise expressions for response probability accounting for (1). We compare calculations with the experiment studying for effect upon tracks density in photographic emulsion numerical treatment of the experiment according to tracks

117 regression in nuclear emulsion to find time parameter has been given.

References 1. Ditlov V.A. Theory of spatial calculation .... Solid State Nuclear Track Detectors. Pergamon Press 1980, pp. 131-141.

118 Vt UAMMA JKKAUIA1JUN Ul\ int cui-n. nnv ».w~.~ _ PROPERTIES OF CELLULOSE NITRATE (DAICEL 6000) AND CR-39 PLASTICS

R.SHV.'EIKANI , T.TSURUTA AND S.A.DURRANI

School of Physics and Space Research, University of Birmingham, Birmingham B15 2TT, UK • Atomic Energy Research Institute, Unh'ersity of Kinki, Kowakae, Higashiosaka, Osaka, 577, JAPAN

ABSTRACT

The effect of irradiation by Co gamma rays in the dose range 0 - !0 Gy has been examined on cellulose nitrate (Daicel 6000) and CR-39 SSTND detectors . The bulk etching rate after exposure to various gamma doses has been measured by determining the loss in the weight of the plastic as a function of etching time. The results indicate that, in the case of the CN plastic, the bulk etching rate begins at first to increase slowly when the gamma dose exceeds 103 Cy, and then rapidly beyond a dose of 104 Gy. Similarly, for CR-39, the bulk etching rate begins to increase slightly when the dose exceeds 10 Gy, but more rapidly beyond 10 Gy. It was also found that the etching time required for alpha tracks to be revealed decreases with increasing gamma dose, i.e. the etch induction time for the alpha tracks decreases at high doses. The effect.on the etch induction time, of irradiating these detectors with gamma rays before or after their exposure to alpha particles has also been investigated. It was found that the alpha tracks were revealed, in terms of clarity and appearance time, in the same way regardless of whether the gamma dose preceded or followed alpha irradiation. This work has wide-ranging implications for both the practical applications and for the basic mechanisms of tfack formation.

119 A QUICK DYECET METHOD OF ECE TRACKS IN POLYMERIC DETECTORS

M. Sohrabi and Sh. Mahdi National Radiation Protection Department Atomic Energy Organization of Iran P. 0. Box 14155-4494, Tehran Islamic Republic of Iran

ABSTRACT In a newly developed dyed electrochemically etched track (DYECET) method, tracks of alphas and fast- neutron-induced recoil particles in polycarbonate (PC) and CR-39 detectors have been effectively dyed (1-3). The principle rationale has been the provision of highly contrasted, large and dyed recoil and alpha particle tracks as highly photon absorbing sites on an unaffected polymer bulk surface for UV and IR spectrophotometry for track density measurements. In the procedures developed before (1-3), a DYECET method applying 20% acrylic acid at 75°C for 3.5 h for sensitization and 3% eosin at 95°C for 4 h in PC detectors for dyeing provided satisfactory results. This procedure regardless of its advantages is time consuming and relatively expensive.

Efforts were made to apply regular dyes without applying the acid sensitization step. Different dyes, solvents, dyeing procedures and UV spectrophotometry and optical densitometry methods have been applied. In the preliminary experiments, quick DYECET methods (with no sensitization) have been developed which make tracks, induced structural cracks and fractals, produced for this purpose, efficiently dyed within a short processing time. The method was applied to alpha and recoil tracks especially in PC detectors and DYECETs of different beautiful colors were developed. In this paper, the results of the current research and development on the above are presented and discussed.

Ti liT. Sohrabi and S~. Sadeghi Bojd, Radiation Protection Dosimetry 34, 5-8 (1990). 2. M. Sohrabi and S. Sadeghi Bojd, Radiation Protection Dosimetry 34, 47-50 (1990). 3. M. Sohrabi and S. Sadeghi Bojd, Nucl Tracks and Radiat. Meas. 17, 547-522 (1990).

120 (dE/dx) FOR 238U IN CR-39

J.Raju and K.K. Dwivedi Department of Chemistry, North-Eastern Hill University, Shillong-793 003, INDIA.

Latent damage trails created by energetic 238u ions cf three different energies (12.0, 10.0 and 4.5 MeV/u) in CR-39 have been developed by suitable chemical etching. Total energy-loss rate of the ions along the damage trails in the detector have been correlated to track etch rate in order to understand the track formation mechanism. Calibration curves have been obtained by correlating the track etch rate with residual range.

121 G. Jbnsson Department of Physics University of Lund Box 188, S-221 00 LUND, Sweden

Plastic films are used for the detection of alpha particles from disintegrating radon and radon daughter nuclei. After etching there are tracks (cones) or holes in the film as a result of the exposure. The step from a counted number of tracks/holes per surface unit of the film to a reliable value of the radon och radon daughter level is surrounded by statistical considerations of different nature. The reliability of the radon measurement depends on a number of elements. Some of them are the number of counted tracks, the length of the time of exposure, the point of time of the exposure, the etching technique and the method of counting the tracks or holes. The number of background tracks of an unexposed film is sometimes an overlooked parameter which increases the error of the measured radon level. In additional, there are different opinions about using arithmetic mean values at the presentation of results of radon measurements.

Some of the mentioned elements effecting the reliability of a radon measurement will be discussed in the report.

122 PRESOAK STUDIES WITH CR-39 AND LEXAN Robert W. Pollock Radon Environmental Monitoring Northbrook, IL 60062 USA

Ogura has shown an increase in sensitivity of about 30% for heavy ion and a roughening of the surface of CR-39 after a 3 hour presoak with water at 70 °C and chemical etching. This work looks at presoaking of CR-39 and Lexan with electrochemical etching after exposure to alphas. CR-39 from American Acrylics and Lexan were placed in REM AT-100 radon detectors and exposed in a radon chamber. The foils were loaded in Eankins ECE cells and warmed in the oven, either dry or filled with presoak solution. The CR-39 was processed with a two-stage ECE and the Lexan a short one-stage ECE. With water at 60 °C, the CR-39 showed a 27% increase after a 3-hr presoak and a 22% increase after an overnight presoak. A 3-hr presoak the previous day showed an 8% increase. There was no significant increase in background. The Lexan showed no effect, even overnight, of presoaking in water at 40 °C. A 50% (by volume) solution of ethanol also showed no significant increase. Acetonitrile was then tried because it can cause crystallization in Lexan. 2%, 5% and 10% presoak solutions showed no significant increase in track density. A 20% solution caused the foils to crack and buckle.

123 LANDSLIDE PREDICTION BY SOIL RADON MONITORING

Rosli H. Mahat Physics Department, University of Malaya 59100 Kuala Lumpur, Malaysia.

A dosimeter for monitoring the level of radon gas in the soil has been developed for use in tropical region such as Malaysia. One application that is being tested is for the prediction of landslides. Soil radon monitoring has been used for volcanic and earthquakes prediction, where any anamolies in the radon level is a precursor. It is hoped that the same would be true for landslide prediction.

124 CHEN Ling China Institute of Atomic Energy* P.O.Box 275 <83).102413* Beijing

A simple passive SSNTD* v?hich is based on a doubIe-chacber method and used for seasuring equilibrium factor (F) for radon, has been developed. The factor F and the ratio D1/D2 possess a linearity relation approximately. Here* Di and Da are the surface track densities on the unshielded and shielded detector respectively. The calibration experiment has been finished in the Standard Radon Chamber at Henyang city. The relative error of calibration factor for radon is about 137.> and the affection of relative humidity and aerosol concentration is saaller.The calibration factor for radon daughter is more scattered* it is mainly affected by relative husidity and aerosol concentration.The reasons of them have been discussed breifly.

125 MEASUREMENT OF RADON ACCUMULATED CONCENTRATIONS IN AIR BY TURBIDIMENTRIC TECHNIQUE

Wang Huan Qiang Hubei Province Institute of Radiation Protection 430070 WuHan, China

Abstract—This paper described a turbidimetric technique to count the tracks registered on CR-39 foils exposed to radon „ instead of eye view through microread- r. Strong correlation between the radon accumulated concentrations in air and track turbidances measured by the differential spectrophotometer method was observed. Under the etching conditon of 7. 07 mol/1 KOH at 80' s for 16hr, linear regression showed that the ratio of truck turbidances and accumulated concentrations of radon exposed was 1. 99 x 10-3 (kBq. m-3. h)-l, and the determination limit was 36 KBq. m- 3. h. Comparing to the traditional eye view method, it costs much less time to accomplish whole counting with high accuracy. This paper presented the experimental details.

Key Words-radon, CR-39, turbidimetry, nucleuar tracks technique

126 CR-39 Rn-222 DETECTORS

Shang Bing Laboratory of Industrial Hygiene, Ministry of Public Health, Beijing 100088, China

This paper presents a easy method of 222Rn concentration accumu lating measurement in air. CR-39 chips manufacted by Pershore Mould ings LTD. of England and Karlsruhe diffusion chambers are used as pas sive accumulating 222Rn detectors. After exposure, the CR-39 chips are etched in 6. 25N NaOH at 80 "C for five hours. Typical and clear al pha tracks can be observed with a microscope. The relationship between alpha track density and 222Rn accumulating concentration is proportion ally (r > 0. 9990). The calibration efficiency of two batches of CR- 39 chipa are 5. 54 and 5. 79 tracks cm2 per KBq M~3h, respectively. With one month exposure in air, the detection limit is 7. 0 BqM3. The standard deviation of the method is less than 15%.

Keywords; CR-39, 222Rn detector, accumulating measruement.

127 INDOOR RADON MEASUREMENT IN THE NORTHERN REGION OF BANGLADESH

G. S. Islam, M. A. Islam, A. K. M. F. Haque and G. C. Mistry.

Department of Physics, Rajshahi University) Rajshahi, Bangladesh.

ABSTRACT

Solid state nuclear track detectors CR-39 have been used to determine the in door and subsiol radon activity at four locations in the northern region of Bangladesh. The indoor radon activity of Naogaon was found to be higher than that at Rajshahi, Nawabgong and Ruppur. Radon concentration in the mud-built houses at Naogaon was estimated to be 425 Bq/m3 which is about three times higher the recommended limit. In general, radon activity in the mud-built dwelling houses was found to be consistently higher than that of the brick-built houses.

128 ASSESSMENT OF RADON CONCENTRATION IN EGYPTIAN

DWELLINGS BY USING A PASSIVE TECHNIQUE.

G.M.Hassib, M.I.Hussein and H.A.Amer.

The National Centre For Nuclear Safety And Radiation Control, Atomic Energy Authority P.O.Box 7551-Nasr it,a, Egypt.

Abstract In this work, the KFK-passive radon dosimeter is used to evaluate the radon concentrations in Egyptian dwellings. The survey program includes indoor and outdoor measurements during summer and winter seasons. Measurements were made in different heavy populated towns as well as some dwellings nearby black sand deposits in the outlet of the River Nile. Results have shown that the indoor radon concentrations in 3 Egypt varries between 20 and 5 Bq/m with a mean value of 1G 3 Bq/m . The difference between indoor and outdoor was found to oe not significant due to the non-tight building style. Some analysis are given about the impact of black sand deposits on the nearby cities and the effect of smoking on the indoor radon cancentrat ions.

* This work is partially supported from KFA-IB Julich Germany and supervised by E.Piesch, KFK-KarIcrule, Germany.

129 A.A.B. /ndao and D.N. Anoo

Nuclear Research Laboratoryt Department of Physics, Ifaiversity of Science & Technology, Eumssi,

We present measurements of radon from building materials in Ghana* The building materials range from cement - based concrete blocks cade from imported and locally produced cement, to sun-dried cud bricks used in constructing the adobe houses prevalent in rural areas< Our survey is part of a national programme on the accumulation of a database for natural radiation in Ghane»

130 t-UK J.NUUUK HtHijUKt.nt.IM 1 ilM

S.unlii and Z.Yegingil Cukurova University, Art—Sciencf Faculty) PhyEicE Department, 01330 Adane, TURKEY

Radon and its daughters' concentrations were assessed by using passive bare detectors based on CR—39, pi seed in a mill in Adsna, indoors for about 1 year. The results obtained gave a minimus value of 10 Bq/m in July, 1991 and a maximum value of 315 Bq/m in November, 1991. Results were studied according to the soil characteristics and indoor factors such as floor level, room usage, ventilation.

131 MEASUREMENTS OF RN-222 CONCENTRATIONS IN DWELLINGS IN A CITY KITH HIGH POPULATION

Gunseli YAPRAK and Selman R. KINACI Ege University, Institute of Nuclear Sciences. Bornova 35100, TORKiYE

ABSTRACT The contribution of radon and its daughters to the natural radiation exposure of human beings which especially increases quite excessively in the atmosphere of living quarters during winter for energy saving purposes is alwalys significant levels. Accumulation of radon and radon daughters in the indoor atmosphere increases the risk of lung cancer in human beings.

Considering the importance of radon and its decay products for human health,our Institute has started a programme to measure the concentration of radon and its decay products in the atmosphere of dwellings in Izmir. For this purpose, track-etch films (Kodak LR-115 type II) were hung to 250 houses and offices during the winter. After exposing for a month, the films were collected and processed chemically (etching conditions: 10% (2.5 N) NaOH at 60 °C for 2 hours) in our laboratory. Thus the concentrations of radon and its daughters have been determined.

132 SSNTD IS USED TO MEASURER THE RADON CONCENTRATION IN THE AIR IN THE AIR-CONDITIONED BUILDING

Lu Yang Qiao Feng Yu Shui (Laboratory of Industrial Hygiene, Ministry of Public Health, Beijing 100088)

Th<> radon cn-icfin trat i on in the air-conditioned building is current quest inn of which the radiohygiene concerns.

The medicinal MRI-CT's experimental building is developing since the 1980s is one of the most advanced instrument. It is used to apply air-conditional system.

We have put SSNTD in the MRI-CT's building. The MRI-CT is made in Germany. The building is asmall indepeding storey.

SSNTD had been put fron Junel991 to September 1991. Measured radon concentrations (KBq.m** ) are 0.192*0.038, 0.125*0.015 and 0.130*0.007, respectively in the control room, equipmeht room and examination room.

Those values are 6.3, 4.5 and 4,3 times respectively as high as average value in the room in Beijing.

SSNTD is roade in China is CR-39. IT is calibrated by the standard radon chamber. The radon chamber usualy particlpats in the international comparison and has international comparable and accuracy.

133 CONCENTRATION BY CR-39

Zhao Yu-hua Zhao Chong-de HaoXiu-hong Zhou Pei-de 6uo Shi-lun ( China institute of Atomic Energy, Beijing 102413 )

An a— sensitive solid state nuclear track detector (SSNTD) CR-39 was employed to assess the concentration of indoor radon and its daughters. The detectors of CR-39 mounted in a cup-type sampler were deployed in some typical workshops, laboratories and offices in the area where some nuclear facilities are located for ages. They were mostly exposed for 7 months and then the tracks were etched in NaOH and counted with microscope. It is shown that the contribution of Rn to the background in the area is not significant.

134 CONCENTRATION OF RADON IN THE SENERY PLACE IN CHENGDE

Zhou lianjiang Sun kexin Zhou kaijian Yang yanwen Wang xin (Hebei Institute of Radiation Hygiene) Zhou jiuku Bai zhijun Li cuibing Du lihua Du deyun (Chengde Prefecture Sanitary-Epidemiological Station)

This paper has reported the level of Radon concentraion in the senery place in Chengde in the method of CR-39 plastic. 98 samples were measured, including 77 indoor and 2 outdoor. The average level of Radon concentration is 38. 23 Bq. m indoor and 18. 46 Bq. nr3 outdoor. The range of percapita annual effective dose to tourists and officals from Radon is estimated to be 0. 4 to 0. 95 msv.

135 NUCLEAR EMULSION IN CHINA

Sun Hancheng

China Institute of Atomic Energy P. 0. Box 275 (94), Beijing 102413, China

The history and the present status of the research vork of nuclear emulsion and its application in China are reviewed. In 1950, professor Be Zehui initiated the research work of preparation of nuclear emulsions at CIAE. The proton sensitive emulsions He-2, Be-3 and the electron sensitive emulsions Be-4, He-5, as well as some other special emulsions have been produced and supplied for applications in unclear reaction studies, fast neutron spectroscopy, cosmic ray studies, geophysics, biology, metallurgy, etc. Some new methods for fast neutron spectroscopy, i.e., the dihedral angle method and the H B (n, a )' Li (p )' Be(2fl ) reaction Method/ were invented. Several He-4 emulsions were carried on some recovery artificial satellites and the doses of the environment were measured. A laboratory cooperated with Japan has been established at an altitude of 5500 metres above sea level in Ganbula mountain and emulsion chambers have been exposed for ultra high energy cosmic ray stndies. For the relativistic nucleus-nodeus collision studies, there is a joint research group in China, of which the main members —the Institute of High Energy Physics ( Beijing ), the Hua Biong Normal University ( Wihan ), the Shanxi Normal University (Linfen) and the Hunan Education Institute (Changsha) are also tlie members of the international EHU-01 group.

J36 AGEING EFFECTS ON A NEW POLYMERIC TRACK DETECTOR SR-90 AND A MODEL OF THE NUCLEAR TRACK FORMATION

M. Fujii*, R. Yokota**, T. Kobayashi*** and H. Hasegawa****

* Aomori University, the Faculty of Engineering 2-3-1 Kohbata, Aomori, 030 T*pan ** Institute of Space and Astronautical Science 3-1-1 Yoshinodai, Sagamihara, 229 Japan *** Aoyama Gakuin University 6-16-lChitosedai, Setagaya, Tokyo, 157 Japan **** Fukuvi Chemical Industry Co., Ltd. akaicho, Sakai-Gun, Fukui, 919-05 Japan

The relationship between the detection sensitivity for charged particles and the molecular structure of polymers like CR-39 was studied while changing the average length of the molecular chain between two adjacent carbonate groups in these polymers. It has been found that the polymer shows the highest sensitivity when its chain length is about 1.6 times longer than that of CR- 39. Just after polymerization this polymeric track detector named SR-90 has about 4 times higher sensitivity than CR-39 but ageing effects on its sensitivity are very strone. In this connection a model of the latent track formation and the mechanism of the track fading will be discussed on the basis of the recombination of free radicals produced by charged particles.

237 A NEW APPARATUS FOR TRACK-ANALYSIS IN NUCLEAR TRACK EMULSION, BASED ON A CCD-CAMERA DEVICE

E. Ganssauge, L. Mangoxa, M. Ochs, M. Roper F. B. Physik, Philipps-Universitat Marburg, Germay

A CCD-camera based image analyzing system for automatic evaluation of nuclear track emulsion chambers is presented. The stage of a normal microscope is driven using three stepping motors to bring the emulsion-pellicles into the right position in spetps of > 0. 25 um by remote control. On top of the microscope a CCD- camera mounted to register the nuclear emulsion. The resolution of the camera is good enough to resolve single emulsion-grains (0. 6 um). The camera picture is transformed from analogue to digital signals. Then it is taken by a frame grabber for storage. Certain background-picture elements can be eliminated. The central computer controls the picture acceptance, correlates the single picture points, coordinates and grey-levels such that at the end one has a unique assignment of each picture point to an address on the hard disc. By means of a suitable software (for instance our vertex program" the coordinates of the points are combined to tracks, and a variety of distributions like pseudo- rapidity-distributions can be calculated and presented on the terminal.

Ganssauge et al. , Comp. Phys. Comm. 55 (1989), 233.

138 Supplements

Sharma, S. K. (Kurukshetra). STOPPING POWER AND RANGE DETERMINATION OF REL- ATIVISTIC AND NON-RELATIVISTIC HEAVY IONS IN DIF- FERENT MATERIALS INCLUDING SOLID NUCLEAR TRACK DETECTORS. (10)

Mcdeiros, J. A. (Rio de Janeiro) • EFFECT OF REACTOR IRRADIATION AND KINETICS OF FISSION TRACK FORMATION IN HIGH PURITY QUARTZ GLASS. (10)

Zylberberg, H. (Rio de Janeiro): REACTOR IRRADIATION EFFECTS AND KINETICS OF FIS- SIONTRACK FORMATION ON " CR-39" CROSS-LINKED POLYCARBONATE. (10)

Bradnova V. (Dubna): Agd (Cd) DETECTORS PREPARED BY PRESSING. (10)

Hadler N. , J. C (Campinas): AN AUTOMATED SYSTEM FOR TRACK MEASUREMENT FOR THE EMPLOYMENT OF CR-39 AS ALPHA-SPECTROME- TER IN RADON AND DAUGHTERS MONITORING. (10)

Rebetez, M. (Besancon)- VERSION 3. 0 "ATOM" SOFTWARE WITH BUILT- DM MO- TORIZED STAGE CONTROL FOR OPTICAL MICROSCOPY ANALYSIS OF NUCLEAR TRACKS. (10)

Vukovic, J. B. (Belgrade). CR-39 IMAGED BY ATOMIC FORCE MICROSCOPE. (10) Singh, L. (Amritsar): RECOVERY STAGES OF HEAVY IONS INDUCED DAMAGE IN CRYSTALLINE MINERALS. (10) 150

Zhdanov, G. B. (Moscow); SELFCONSISTENT METHOD OF ENERGY DETERMINATION FOR HIGH ENERGY Y-QUANTA BY DENSITOMETER MEA- SUREMENTS IN X-RAY EMULSION CHAMBER. (10) 151

Sartori, S. M. (Torino): ELECTROMAGNETIC DISSOCIATION STUDY IN CR-39 AND EMULSION. (10) 152

Rosa, G. (Rome): NUCLEAR EMULSION AND PLASTIC TRACK DETECTORS APPLIED TO HIGH ENERGY PHYSICS: HYBRID EXPERI- MENTS IN THE PAST AND PRESENT DECADE. (15) 153

Shahzad, M. I. (Islamabad).. INTERACTION OF "O AND "F IONS WITH THICK COPPER TARGET AT RELATIVISTIC ENERGIES. (10) 154

Manzoor, S. (Islamabad): INTERACTION OF 15. 9 MeV/U 1>7AU :ONS WITH NATAu AND 2MBi AS TARGETS ON CR-39 PLASTIC TRACK DETECTORS. (10) 155

Antanasijevic, R. (Beograd): MEASUREMENT OF FLUENCES AND ENERGY OF D+ EMIT- TED FROM PLASMA FOCUS IN CAPACITOR BANK ENER- GIES INTERVAL OF 1-30KJ. 156

139 Jovanovic, L. (Wien): FISSION TRACKS ANNEALING AND THE THERMAL HISTO- RY OF YUGOSLAVIAN CHONDRTTES. (10)

Bernard!, L. (Pfcioia). DETECTION OF INTERMEDIATE Z COSMIC RAYS BY MEANS OF POLYCARBONATE SSNTDs. CHOICE OF THE BEST DETECTOR. (10)

Sharma, A. P. (Aligarh): COSMIC RAY RECORDS OF HEAVY IONS IN GALACTIC CRYSTALS. (10)

Flitsiyan, E. S. (Tashkent); THE USE OF RADIOGRAPHIC TECHNIQUES FOR STUDY- ING ELEMENTAL DISTRIBUTIONS IN NATURAL AND TECH- NOLOGICAL OBJECTS. (10)

Otgonsuren, O. (Ulan-Bator) • ON DETERMINATION OF THE TRACK AGE OF SOME NATU- RAL CRYSTALS. (10)

Sandliu, A. S. (Toronto); ISOTHERMAL PLATEAU FISSION TRACK AGE DETERMINA- TIONS ON VOLCANIC GLASS SHARDS. (10)

Singh, S. (Amritsar); CORRECTION METHODS IN FISSION TRACK DATING. (10)

Mironov, A. G. (Ulan-Ude). THE APPLICATION OF THE ARG- AND SSNTD-METHODS IN THE GEOCHEMICAL INVESTIGATION OF GOLD AND U- RANIUM. (10)

Lucia, M. (Rio de Janeiro); FISSION TRACK DETERMINATION OF URANIUM AND THO- RIUM IN ZIRCONIUM, THORIUM AND URANIUM ORES. (10)

Ng, I. K. (Kajang). DETERMINATION OF ZETA CONSTANT FOR FISSION- TRACK DATING. A PRELIMINARY CALIBRATION BY POP- ULATION METHOD. (10) 167

Afaridch.H. (Tehran). URANIUM CONTENT AND AGE DETERMINATION OF VARI- OUS MINERALS OF IRAN. (10) 168

Murtasaev, Kh. (Khudjant); ON DETERMINATION OF THE TRACK AGE OF SOME NATU- RAL CRYSTALS. (10) 169

Nor, A. F. MD. (Kuala Lumpur). EFFECT OF RADIATION DAMAGE ON THERMOLUMI- NESCENCE AND INFRA-RED PROPERTIES OF NATURAL A- PAT1TES. (10) 170

Viasova, I. E. (Moscow): GROWTH RATES OF THE FERROMANGANFKE NODULES OBTAINED BY THE CELLULOSE NITRATE DETECTOR LR 115. (10) 171

STANDARD RADON CALIBRATION CHAMBER USING SS- El-Fiki, M. A. (Cairo) : NTDs. (10) 172

140 DeviUard, C (Besancon): DEVELOPMENT OF MEASURING TECHNIQUES USING SILI- CON DIODE PIN DETECTOR FOR CONTINUOUS RADON MONITORING. (10) 173

Qureshi, A. A. (Islamabad): USE OF ALPHA SENSITIVE PLASTIC FILM (ASPF) TECH- NIQUE TO LOCATE THE RE-MOBILIZED URANIUM ORE BODIES IN SANDSTONES. 174

Singh, a (Amritsar). RADON DIFFUSION STUDIES IN WATER, SOIL, AIR, CON- CRETE AND SAND. 175

Balcazar, M. (Mexico): RADON- A TOOL FOR GEOTHERMAL ENERGY PROSPECT- ING IN EL SALVADOR. 17 6

Tavera, L. (Mexico): RADON CONCENTRATION MEASUREMENTS IN A RADON CHAMBER FOR BIOLOGICAL TREATMENT USING TRACK DETECTORS. 177

Chavez, A. (Mexico); RADON DIFFUSION THROUGH THIN PLASTICS. 178

Djeffal.S. (Alger): PASSIVE RADON PERSONAL DOSEMETER. 179

Azimi-Garakani, D. (Villlgen). COMPARISON OF SHORT-TERM RADON MONITORING TO LONG-TERM AVERAGES. 180

Nikezic, D. (Kragujevac): THEORETICAL DETERMINATION OF CALIBRATION COEF- FICIENT FOR RADON MEASUREMENTS WITH CR-39. 181

Singh, M. (Amritsar): INVESTIGATIONS OF RADON IN SUBSURFACE SOIL AND WATER AS AN EARTHQUAKE PRECURSOR. 182

Farid, S. M. (Swaziland): MEASUREMENT OF CONCENTRATIONS OF RADON AND ITS DAUGHTERS IN INDOOR ATMOSPHERE USING CR-39 NUCLEAR TRACK DETECTOR. " 183

Ramola, R. C (Salzburg)- EXHALATION OF 2»Rn FROM PAPERS. 184

Singh, N. P. (Sangrur): CHARACTERISATION OF SOIL PARAMETERS FOR RADON ASSESSMENT IN HUMAN ENVIRONMENTS. 185

Karamdoust, N. A. (Tehran).- RADON MEASUREMENT IN DWELLINGS AROUND THE HOT SPRING IN THE NORTH WEST OF IRAN. 186

Tufail, M. (Islamabad); ESTIMATION OF INTERNAL AND EXTERNAL DOSE EQUIV- ALENT RATES FOR THE DWELLERS OF DEAR ISMAIL KHAN AREA-PAKISTAN. Jg7

Fernandez, F. (Barcelona): FAST NEUTRON ENERGY AND ANGLE RESPONSE OF ELEC- TROCHEMICALLY ETCHED CR- 39 PLASTIC DETECTORS. (10) . 188

141 Matiullah (Islamabad): CALIBRATION OF VARIOUS TYPES OF CR-39-BASED NEU- TRON DOSIMETERS IN A HEAVY WATER MODERATED AND MONOENERGETIC NEUTRON FIELDS-PART-II- EX- PERIMENTAL. (10)

Zhang, G. L. etal. (Beijing); STUDY ON EFFECT OF NEUTRON RADIATION ON CR- 39 AND SURFACE OF CR-39.

Akopova, A. B. (Yerevan); THE a-ACTIVITY AND THE HOT PARTICLE SIZES IN THE VICINITY OF THE CHERNOBYL NUCLEAR POWER PLANT. (10)

Sharina, M. (Aligarh); ON THE IMPACT OF NUCLEAR TRACK SIENCE FOR RECORDING THE EFFECTS OF RADIOACTIVE ENVIRON- MENTAL INTERACTIONS IN BIOLOGY. (10)

Zaichick, V. Ye. (Obninsk); QUANTITATIVE NEUTRON ACTIVATION AUTORADIOGRA- PHY OF EXOGENOUS 6U IN RAT TISSUES BY SSNTD. (10)

Gromov, A. V. (Saint-Petersburg): APPLICATION OF TRACK DETECTORS FOR SOIL, WATER AND OBJECTS' SURFACE ALPHA- ACTIVITY MEASURE- MENT IN 30-KM ZONE OF THE CHERNOBYL NPP. (10)

Das, K. C. (Assam); URANIUM ESTIMATION IN THE BLOOD OF POKILOTHER- MIC AND HOMOIOTHERMIC ANIMALS. (10)

Cucu, M. (Bucharest) • ON THE URANIUM DISTRIBUTION IN THE INTERNAL CON- TAMINATION. (10)

Dajko, G. (Debrecen)- PRODUCTION AND APPLICATION OF PARTICLE TRACK MAMBRANE IN HUNGARY. (10)

Danis, A. (Bucharest): ON THE RADIOCOLLOIDAL AND PSEUDORADIOCOL- LOIDAL STATE OF THE FISSIONABLE ELEMENT SOLU- TIONS. (10)

Hussain, G. (Islamabad): DIFFUSION OF RADON THROUGH NUCLEAR TRACK MI- CROFILTERS. (10)

Akbari, R. B. (Tehran); THE PHYSICAL CHARACTERISTICS OF THE TLD- LiF DOSEMETERS. (10)

142 STOPPING POWER AMD RANGE DETERMINATIOM OF RELETIVISTIC AND NON-RELATIVISTIC HEAVY IONS IN DIFFERENT MATERIALS INCLUDING SOLID NUCLEAR TRACK DETECTORS.

S.K.Sharma, Shyam Kumar and A.P.Sharma.

Department of Physics, Kurukshetra University, Kurufcshetra - 132 119 (India). •» Department of Physics, Aligarh Muslim University, Aligarh - 202 001 (India).

The knowledge of stopping power and range of heavy iont in different media is one of the most essential requirement in almost all heavy ions related studies. In the present work the calculations of stopping power and range of various heavy ions at both, the relativistic and non-relativistic energies have been done in various elemental as well as complex media. For this purpose various existing formulations (Benton E.V. arid. h'*nM& R. P. , i960; MakA*r-£#e S, and K'a.yak A. K,

lQTOi Ziegler J. F. artd Martoyon J.M.t 1Q8S; Hubert F. ©t. al. ; SQ9O) have been utilised . Finally a comparison has been made with the existing experimental results.

143 Effect of Reactor Irradiation and Kinetics of Fission Track Formation In High Purity Quartz Glass JoSo A.Medeiros (1,2) and Orlando M.G. de Moraes (1) (Dchemistry Dept, Catholic university - PUC/RJ (2)Institute of Nuclear Engineering, Atomic Energy Commission, Rio de Janeiro, Brasil High purity quartz glass (Suprasil, Heraeus) was studied and used as fission track detectors at high fast neutron fluxes, out of range of plastic detectors (to 1038 n/cma), to determine small amount of uranium and thorium and in the search for superheavy elements. Previous work on the influence of reactor Irradiation showed strong alterations in detector properties, systematic study of radiation effects was realized : a strong fi8Co source and fast neutrons of research reactor ( KFA Jttlich, Germany ), looking for the kinetics of track formation. Microscope slides 25x75mm were cut in 12.5x25 m» detectors. Detectors were exposed to aBaCf fission fragments at 2n geometry, and at 90° incidence, before and after irradiations. Seven gamma doses from 10° Gray (10 MRad) to 15 MGray (1.5 GRad) were investigated. Previously observed absorption bands in uv-Vis region during reactor irradiation are identical

to gamma effects, and are not correlated to vb, which is mantalned constant (4,66 Hm/h), nor to efficiency to register new tracks, nor to annealing of latent tracks, insignificant at those doses. Experiments were run for reactor irradiation, at Jtllich (FRJ-1 Reactor, **=7.5xl013 n*/cra2/s and •*/•* = 7.5, for 10 different integrated fluxes, from 10X' nt=/cm2 and 16 2 2B a i8 a 1.3xl0 r.e/cm to 10 n*/cm and 1.3xl0 n*/cm . V*. increases exponentially, and efficiency to register new tracks decreases to 0.66 for 1.3.101* n«/cma, being well represented as function of time by a parabolic equation, as well as exponentially. Latent tracks are strongly annealed by fast neutrons in a double exponential expression as function of irradiation time or integrated flux. Detectors irradiated in contact with high purity Al and Graphite show a curve like a parabola for track density, with a maximum at 2.5xl0a> n*/cm2. A model for the kinetics of track formation is proposed. The formation of etchable tracks during reactor irradiation may be expressed by equations Nt=No.

-t - aat*}. Reactor irradiation Effects and Kinetics of Fission Track Formation on "CR-39" Cross-linked Polycarbonate Heliane Zylberberg (1) and Jo3o A.Medeiros (2) (l)lnstitute of Nuclear Engineering, Atomic Energy Commission, (2)chemistry Dept., catholic University - PUC/RJ Rio de Janeiro, Brasil CR-39, a cross-linked addition alyphatic polymer, has been recommended since years as an multi-purpose detector for charged particles and recoil protons, like those formed by fast neutron irradiation. Looking for its use as fission track detector, irradiation effects were studied for "Co gamma and reactor irradiation, close to the core of swimming pool research reactor IEA-R1 in Brasil.' Monomer was polymerized between glass plates, with and without dioctylphtalate (DOP) as

plasticizer. Bulk etching rate Vb was determined by mass losses and by diameters of tracks of 90 degrees incident "acf fission fragments, and by chemical method : determination of reducing compounds in etching solutions via oxidation by dichrornate in acid solution. Mass, width and track diameters give erroneous results, mainly for irradiated detectors. The chemical method with volumetry or spectrophotometry proved to be satisfactory to every case. Several series of commercial CR-39 and DOP containing polymerized detectors (DCR) were exposed, at 4n geometry, to aoaCf fission fragments and irradiated separately with gamma radiation (1 to 100 MRads) and close reactor core at ia a neutron flux of about 10 n/cm /s, tith.rn.i / n«..t = 8-10, to integrated fluxes from 10" to 10" n/cma. Adsorption bands in visible region increase with gamma dose and integrated neutron flux (•). V«» increases with 0 (-20 times for 10" n/cma) and with dose (-30 times for 10 MRads). Annealing of latent tracks decreases exponentially the number of etchable tracks in two lt: distinct processes N=No.e~ . Efficiency decreases exponential- . ly : N=No.e-fc*. starting from a differential equation were deduced equations to express the formation of etchable tracks during reactor irradiation, which fit well experimental data of tracks in detectors irradiated in contact with Al-foils and immersed in uranium solutions : Nx= c/(l-k) - (e->c*i-e-llt=1) , la a Na=cV(l-k).(e-*"-e- «= ) , where c=n«»-cr-*-e , c'=c-0.8 , and lat:a Nt=Ni.e- + N2. Commercial CR-39 showed stronger irradiation effects than DCR, this being attributed to aromatic rings. AgCl(Cd) DETECTORS PREPARED BY PRESSING

V.Bradnova, S.I.Kulikova, N. M. N'evzorova. Joint Institute -for Nuclear Research, 1419S0, Dubna, Russia

The results of work on detectors o-f si 1 verchloride doped with 500 ppm cadmium made by a new pressing technology are presented in the paper. It describes the conditions o-f pressing o-f AgCL (Cd) plates, making o-f •foil with 0.15-0.20 mm thickness snd analyses of irradiated detectors. The characteristics of tt-particle tracks &rs compared with the source Po and with energy at 9 MeV/n in detectors made from melted AgCl and by pressing. AN AUTOMATED SYSTEM FOR TRACK MEASUREMENT FOR THE EMPLOYMENT OF CR-39 AS ALPHA-SPECTROMETER IN RADON AND DAUGHTERS MONITORING

J.C.Hadler N., P.J.Iunes and S.R.Paulo

Depto de Raios Cosmicos e Cronologia, IFGW, Universidade Estadual de CaipLnas, 13081, Campinas-SP, Brazil

In this work, it is studied the automated analysis or alpha-particle tracks in CR-39, by employing a MITAKA photo-microdensi tometer with a C1522 KAMAMATSU Image Analysis System. This system can be used to measure track diameters - with a nominal precision of 0.8 pm -, superficial track density and track darkness. These informations can be employed to determinate the alpha-particle energies and also their incidence angles (azimuthal and zenithal). The performance of such automated system was studied comparing its response with measurements performed manually by experienced microscopists, to analyze CR-39 samples which were exposed to alpha-particles of known energies. The experimental results indicate that the MITAKA/HAMAMATSU system is very reliable for alpha track analysis in CR-39, making possible its use to perform time consuming measurements in microscopy, as in the case of radon and daughters surveys.. VERSION 3.0 "ATOM" SOFTWARE WITH BUILT-IN MOTORIZED STAGE CONTROL FOR OPTICAL MICROSCOPY ANALYSIS OF NUCLEAR TRACKS

M. Rebetez, D. Petit, R Nicot, M. Grivet, N. Ben Ghouma and A. Chambaudet. Universite de Franche-Comti, U.F.R. des Sciences et des Techniques, Laboratoire de Microanalyses Nucteaires, 16 route de Gray, F-25030 Besancon Cedex

We first developed a semi-automatic measuring system for the analysis of fission tracks. The first version of "ATOM" software was presented at the 15th conference on Particle Tracks in Solids in Marburg and has previously been described *. Since 1990, many improvements have been made, resulting in version 3.0 which will be presented in this paper. This version now has a built-in motorized stage control for optical microscopy analysis of different kinds of nuclear tracks or other surface defects. Efforts were mainly aimed at improving the efficiency of apatite fission track analysis (AFTA). In this way, the external detector dating method can now be used with automatic positioning of the motorized stage. Problems related to grain-image recognition and counting surface adjustment have been solved and the age determination is better with this extension. Moreover, preparation and analysis time is reduced thanks to the greater number of mounted grains. Statistical menus have also been improved, especially in the graphical presentation of results. Finally another software program has been written to enable data to be analysed using the Excel software (Microsoft) either with an IBM compatible or a Macintosh computer (Apple).

* M. Rebetez, B. Zoppis, A. Rebrab, P. Grillon, E. Gentina and A. Chambaudet, ATOM: a semi-automatic measuring system for the analysis of fission track characteristics in anisotropic minerals, Nucl. Tracks Trad. Meas. 19, 255-60 (1991) CR-39 IMAGED BY ATOMIC FORCE MICROSCOPE

J.B. Vukovic, Institute of Biophysics, Faculty of Medicine R. AntanasijeviC, Institute of Physics University of Belgrade, Belgrade, YUGOSLAVIA

Most important success, in microscopy is recent invention of Scannin tunneling microscope (STM Binning and Roher, Nobel Prize 1986). Atomic fora microscope (AFM noncontact) was the first microscopes derived from STM Also, a family of new microscopes opens this realm which is capable o •^solving the surface detail down to atomic and molecular level (Scanning arobe m. SPM: STM, AFM, Magnetic f. m. MFM, S. ion conductance m. SICM 3. near field m. SNOM, PhDton s. t. m. PSTM and others. The fundamental problems and their interpetation in Nuclear tracks in solid: tracks formation mechanism: direct production of atomic displacement, manv, nrocken molecular chains in plastics, free radicals, tracks structures before luring and after eatching, silver halide microcristals and orhers), must b« uccssefuly imaging by SPM. For STM imaging the specimen of detetctor neet jnly coating by thin conducting layer. Imaging by AFM is much easier becaus •hysical rigidity of dielectric specimens is suitable characterictic. lie left photo present the very rough surface of the CR39 detector irradia ited by alpha particles and etched. Vertical scale Z is difference betwee iright-dark spots. At very high magnification (photo right) from the sam lace of detector it is possible to see faintly "chains" like molecula irganization. (All photos made by AFM NanoScope II, Digital Ins. Inc.

Side - U75 nra 100 nm

149 RECOVERY STAGES OF HEAVY IONS INDUCED DAMAGE IN CRYSTALLINE MINERALS

Lakhwant Singh, Jaspal Singh, Surinder Singh and H.S.Virk Department of Physics, Guru Nanak Dev University, Amritsar 143005, India.

The penetration, of heavy ions of sufficient charge and energy through the crystalline minerals create a linear damage producing different types of localized defects along its trajectories. These defects involves various atomic and nuclear processes. To investigate these defects and their diffusion properties, the microscopic etching and annealing experiments were preformed as a function of time and temperature and its found that there exists two recovery stages corresponding to lower and higher temperature ranges. The mathematical description of the annealing behaviour is given by two recently proposed empirical relations based on the reduction of track etch rate and track retention rate. The activation energy for each annealing stage at different annealing intervals are reported in the present paper. SELFCONSISTENT METHOD OP ENERGY DETERMINATION FOR HIGH ENERGY V -QUANTA BY DENSITOMETER MEASUREMENTS IN X-RAY EMULSION CHAMBER F.Normuratov (Institute of Physics and Engeneering, Dushanbe), G.B.Zhdanov (P.N. Lebedev Institute of Physics, Moscow).

Instead of the usually eccepted simplest form for darkening characteristics of X-ray films D=Dco(1-exp(-n«s)) as a function of the incident particle flux n, and AgBr £rain cross-section S (Dec -D(M*-*'Oo )) another more adequate functions D(fi ,S)«=Do«V/(n,, (F ) are proposed. There is Do«Do(s, £ , Co, Db) special, for the given type of the film and the particular development procedure, function of the cross-section S, thickness of the sensitive layer £ , number density of the developed g£ain Do and the background darkness Db, W is the probability of the formation of the latent image center from the particle flux n, and the cross-section 6"(E) of their interaction with AgBr grains. The independence of W on the development regime was checked and the dependence of Do on this regime was studied for the real Y-quanta of energies Ey = 10 c -10 ^ eV using the theoretical results for cascade showers at various diafragm radii of the photome- ter. The selfconsistency of the method means that the set of measurements of real Y -quanta itself is enough to take into account the peculiarities both of the type of emulsion and its development procedure. ELECTROMAGNETIC DISSOCIATION STUDY IN CR.39 AND EMULSION

Sartori Maria Silvia Istituto Nazionale di Fisica NucJeare - Torino - Italy Politecnico di Torino - Italy

The electromagnetic dissociation of high energy projectile nuclei in lh«* Coulomb field of the target nucleus is an imporiarii effect, whose cross section becomes higher than the nuclear one when :he energy is high and the interacting ions are heavy.(e.g. S-Pb at 200 GeV N). We present here the experiment EMUQ9 (at the CERN SPS). in which it is possible to study, on several targets and with Inch statistics, the different channels of the projectile dissociation of 325 ions of 200 GeV per nucleon and to measure the fragment angular distributions. In addition, a differential deflection in a magnetic field allows the isotopes of the outgoing light fragments to be separated and identified. Two different techniques are combined: CR39 plates upstream and downstream the target are used to select the events in which the beam ions present a change in charge, and emulsion plates are used to reject nuclear interactions and measure the fragments emission angle and deflection in the magnetic field. NUCLEAR EMULSION AND PLASTIC TRACK DETECTORS APPLIED TO HIGH ENERGY PHYSICS: HYBRID EXPERIMENTS IN THE PAST AND PRESENT DECADE

Giovanni ROSA Dipartimento di Fisica and Sez. I.N.F.N. Universita' La Sapienza - P.le A. Moro 2 1-00185 ROME - ITALY

ABSTRACT Solid state track detectors were succesfully combined with electronic counters in many advanced high-energy physics and cosmic-ray experiments. In such hybrid experiments, the superior spatial resolution of tracking in solids and the triggering power of the electronic devices allows to single out and study rare interesting events. Outstanding hybrid experiments performed in the last years will be reviewed, both in the search for charm and beauty particles, at CERN ai-J FERMILAB, and in the study of ultrarelativistic ion collisions. Emphasis will be put on technical im- prouvements and on the consequent physics results. The topics of the magnetic zaonopole and of the search for neutrino oscillations will also be touched. Perspectives in the application of solid state track detectors to high-energy physics, by the hybrid approach, will be outlined. INTERACTION OF l6O AND 19F IONS WITH THICK COPPER TARGET AT RELATIVISTIC ENERGIES

M.I. SHAHZAD1, S. MANZ00R2, I.E. QURESHI3, R. BRANDT4, and H.A. KHAN2

1. Computer Division, PINSTECH, P.O. Nilore, Islamabad, PAKISTAN 2. SSNTD-Laboratory, NED, PTNSTECH, P.O. Nilore.. Islamabad, PAKISTAN 3. Nuclear Physics Division, PINSTECH, P.O. Nilore, Islamabad, PAKISTAN 4. Kernchemie, FB-14, Philipps Universitat, D-3550-Marbuig. GERMANY

ABSTRACT: Interactions of 58 GeV 0 ions and 65 GeV *^F ions on a Cu target have been studied. Stacks composed of CF-39 detectors (]0x4x4 cm.), have been used for calibration and detection of the reaction products. Detectors from the 'Calibration Stack1 and the 'Reaction Products Stack1 have been taken and developed under identical etching conditions. The track densities and the diameters of the front and back sides of the detectors have been obtained. The track diameter variation at different etching times has also been studied. An automatic, image analyzer system has been used for fast and accurate measurements cf the track diameter and density of the reaction products. The diametric distribution has been correlated with the rate of energy loss (dE/dX) of the beam in the calibration stack. INTERACTION OF 15.9 MeV/u 197Au IONS WITH AND 209Bi AS TARGETS ON CR-39 PLASTIC TRACK DETECTORS

S. MANZOOR1, ANEELA KHALID2, 0. K. CHAODHARY1, M.I. SHAH2AD4 I.E. QURESH13 and H.A. KHAN1

1. SSNTP-Laboratory, NED, PINSTECH, P.O. Nilore, Islamabad. PAKISTAN 2. Department of Physics, University of the Punjab, Lahore, PAKISTAN 3. Nuclear Physics Division, PINSTECH, P.O. Nilore,Islamabad, PAKISTAN 4- Computer Division, PINSTECH, P.O. Nilore, Islamabad, PAKISTAN

ABSTRACT: A 2fl" geometry has been employed for studying the interaction of 15.9 MeV/u Au ions with natAu and "^Bi targets making use of CR-39 as the detector. The detector has been scanned for binary and multiprong reaction products produced as a result of the interaction in the CR-39 plastic track detector. Reaction products have been analysed for partial and total reaction cross-sections and compared vith the theoretical values. Elastic and inelastic events have been separated from the two prong data. Quarter point angle and other reaction parameters have also been determined. Attempts have been made to establish an interaction mechanism. MEASUREMENT OF FLUENCES AND ENERGY OF D+ EMITTED FROM PLASMA FOCUS IN CAPACITOR BANK ENERGIES INTERVAL OF 1-30 KJ

R.Antanasijevid, I.Laki£evi£, S.Popovid. A.Zarie D.Sevid, J.Vukovi<* and D.Konjevit*

Diagnostics of D* emitted from D-plasma focus were provided with CR-39 and CA-80-15 detectors. The fluences and energy of D were measured in the dependence of energy of capacitor bank in energy interval of 1-30 KJ. Angular distribution of D was measured using the "Pin hole" camera at different positions in plasma focus chamber. Energy of D was estimated by measuring of diameters of the D tracks. Incident angle was 90°. FISSION TRACKS ANNEALING AND THE THERMAL HISTORY OF YUGOSLAVIAN CHONDRJTES

Larissa Jovanovic', G. Kurat and Aleksarvdar Kostic

Naturhistorische Museum, Burgring 7, Vien, Austria Museum or Natural History, Belgrade, Yugoslavia

Heat i ng and reerystsl J.i xsti on during methamorphism and further cooling processes anneal the existing fission tracks. In adding fission track data, the possibility of establishing on absolute time scale arizes with the prospect of more precise estimates of cooling rates. We have used analyzes of Ol, Opx, Cpx and Sp from the Yugoslavian chondrites CSlavetic* H4, Dubrovnik L3-L6, Mi 1 ena L6, Zavid L6, Soko-Banja LL4 and Jslica LL63 to calculate the closing temperatures from different mineral exchange reactions. A set of mineralogical thermometers Csingle and two- pyro>:&ne, oli vine-spinel , oli vine-clinopyroxene3 has been applied for estimating closing temperatures. Comparative cooling rates of different chondrites were calculated using the mathematical transformations of diffusion equations. Ol ivi n—spinel pairs from equilibrated chondrites -Jeli — ca, Milena and Zavid have closing temperatures in the range 475-490 C by Ol-Sp thermometer. Closing temperatures of unequilibrated chondrites are much higher C600-800 O. Slower cooling rates Cabout. 6-8 times) for equilibrated chondrites allowed more time for ionic redistribution in the crystal structure and for fission tracks annealing. Fossil track density in oli vine crystals from Jeli ca LL6 chondrite is about 1O times lower than in Soko Banja LL4 chondrite. In Zavid L6 and Miiena L6 chondrites fossil tracks are not determinated. A comparative study of thermal metamorphism of different chondrites shows -very strong influence of thermal history on the stability of fission tracks in the chondritic minerals.

157 IETECTION OF INTERMEDIATE Z COSMIC RAYS BY MEANS OF POLYCARBONATE SSNTDs.

JHOICE OF THE BEST DETECTOR.

.. Bernard! 1>2) A. Cecchi2*, C. Gori2'3*, and P. Spillantini2'4*

Sezione di Fisica Ambientale, U.S.h. 8, Pistoia, Italy

Istituto Nazionale di Fisica Nucleare, L.go E. Fermi 2, 50125 Firenze, Ital,

3) Servizio di Fisica Sanitaria, U.S.L. 10/D, Firenze, Italy

Dipartimento di Fisica dell'Universita, L.go E. Fermi 2, 50125 Firenze, Ital

In the framework of an ESA (European Space Agency) research programme an the abundance of intermediate Z (30

["he aim of this work has been the selection of the best detector for

>ur specific purpose among various possible candidates such as Lexan,

Ja^rofol or RodirneP.

Miree different classes of parameters ^:ave been invesigated:

- energy threshold

- bulk and trach etch velocity

- reproducibility

'he preliminary results available up to now as well as the sample

.rradiation and etching procedures will be presented and discussed.

158 COSMIC KAY RECORDS OF HEAVY IONS IK GALACTIC CRYSTALS A.P.Sharma Department of Physics, Aligarh Muslim. University, Aligarh-202001 (INDIA) ABSTRACT The extremly heavy ions produced in the Cosmos in. nucleosynthesis processes and eabecidied in metecrritic crystals and moon crystals have been measured in the laboratories on the surface of the earth.For calibration of irradiated and echiod tracks produced as Cosmic Roy records due tc the galactic heavy ions the use of Accelerators has been rc?de.Various heavy ions upto Z*92 (Uranium) produced by the Accelerators create track lengths in meteoritic material / moon, crystals and are used for estimating the unknown charges of the heavy ions irradiating the meteorites while in. space for several thousand years. About 22 stony-iron meteotitic pallacites have been analysed and partilly annealed at high temperatures for several hours in.order to create, fading in latent tracks and develope a new charge threshold of almost Z > 50 for the study of heavy galactic nuclei and super- heavies (ZN/-114) in the Cosmos.. Scanning of these ai.eteoritic crystals gives about 580 U-group tracks and 6-7 Superheavy elements. This : study also infers that the Uranium Ion encentration ir. Galactic spaces of the Cosmos is more than, that of a solai? system.-

159 ELEMENTAL DISTRIBUTIONS IN -NATURAL AND TECHNOLOGICAL OBJECTS

E.S. Flitsiyan

Institute of Nuclear Physics, Uzbek Academy of Sciences, Vlugbek, Tashkent 702232, Republic of Uzbekistan, CIS

Development of nuclear physics has made it possible to use i widely radioactive' isotopes and different analytical nuclear' reactions, as well as to improve the technology of producing special photoemulsions and dielectric track detectors and radiography, as a consequence, holds an unigue place between nuclear-physical methods for investigating the local chemical and structural inhomogeneities of materials' surfaces. The padiography method, sensitivity of which is within a -2 -7 -2 range of 10 •*- 10 g-rnm and resolution ability extends from 0.01 to 100 |jm, is being applied to solve various problems in material science, space physics, microdosimetry, radioecology, scientific photography, nuclear tomography, etc. The essence of the method consists in determining the distributions of ionizing irradiation sources on a surface under study by using the two-dimensional field of their irradiation registrated by means of a photoemulsion or dielectric track detector. The radiography exhibits the following pecularities: reaching a high resolution ability and high sensitivity in dependence on the choice of the measurement geometry, irradiation energy, exposure time and aims of study; possibility to determine simultaneously the character of the distribution of ionizing 160 irradiation sources on a radiogram and, as a result, the area corresponding to them on a replica; providing a long-term storing of registered information in the form of a latent image due to the photoemulsions and dielectric track detectors being noninertial instruments. Statistical analysis amd computer processing of radiographic images have allowed one to solve the two main tasks of the method, namely, the determination of true distributions of ionizing irradiation sources on the surface of an object under study and the quantitative estimation within given accuracy of the content of an element under study in a sample.

To solve a series of the problems in geology and geochemistry, as well as for analysis of technological samples, a complex of radiographic techniques based on the registration of secondary irradiation of the activated nuclei, instantaneous products of the nuclear reactions, and fussion fragments of the transuranium elements has been developed.

Upon designing and constructing special comparison standards modelling a sample in composition and structure, the quantitative data on distributions of more than thirty elements in rock sections and of the main microcomponents, including oxygen, in superconducting ceramics samples have been obtained.

161 ON DETERMINATION OF THE TRACK AGE OF SOME NATURAL CRYSTALS.

I.G.Abdullaev*x', G.G.Bankova*(2 )', L.Enchjin.(3* '), Ch.MurtasaevK ', a\ ii\ (21 O.Otgonsuren1 ', V.P.Perelygin1 , R.I.Petrova* ' ^•Chudjant State University, 735600, Chudjant, Tadjikistan. 2Joint Institute for Nuclear Research, 141980, Dubna, Russia Federation. 3Mongolian State University, Ulan-Bator, Mongolia.

Abstract The fission fragments due to spontaneous fission of "°238u. nucle produce latent tracks in the natural crystals. These latent tracks car be chemically revealed after many hundred million years their formation. It provides the possibility of determination of so-called track age of the crystals and more over in some case - the information about the fermal history of geological object being investigated. In that connection the detailed investigations of annealing behavior of fission fragment tracks in muscovite mica, apatite and whitlocite crystals have been performed. For muscovite mica the annealing procedure has been applied to single fission fragment tracks, for apatite and whitlocite crystals - for binary events. As it has been observed, the controlled annealing produced the shortening down of fission fragment track length. Such procedure provides more direct comparison of the track length spectra due to spontaneous fission of 238U and due, to thermal neutron induced fission of 235U in the same crystal. Such a procedure allows one to obtain more correct value of the track age. The track ages of five crystals at muscovite and phlogopite mica, three garnet crystals, two apatite crystals from Europa and Asia ore deposits and whitlocite crystals from Marjalahti meteorite were measured: The problem of earch for spontaneous fission events due to unknown natural ong-lived nucleus - the products of nucleosyhthesis in the Solar ystem about 4.7 B.Y. ago is discussed.

162 ISOTHERMAL PLATEAU FISSION TRACK AGE DETERMINATIONS ON VOLCANIC GLASS SHARDS

Amanjit S. Sandhu and John A. Westgate Department of Geology, Earth Sciences Centre, University of Toronto, Toronto, Ontario, M5S 3B1 Canada.

Abstract- Glass shards from Quaternary tephra beds are often used for fission-track dating since they are common constituents of such rocks. However, the dating of volcanic hydrated glass shards presents considerable difficulties such as fading of spontaneous tracks and fine grain size. But within recent years fission-track dating method based on isothermal plateau technique(ITPFT) have been successfully applied to such glasses. We have shown that this grain-discrete method is ideally suited to the dating of the distal tephra beds, which are typically thin, discontinuous, fine-grained, and contaminated by detrital material. A full correction for partial track fading is achieved by a single heat treatment of 150° C for 30 days at which time the ratio of mean spontaneous track diameter(Ds) to mean induced track diameter(Di) is equal to unity. Age estimates obtained by this means compare very well with those based on co-existing mineral phases using the K-Ar, 40Ar/39Ar and thermoluminescence techniques. The use of computer-based image analysis techniques have reduced the time required to determine (1) track size distributions and (2) track density of the muscovite detectors that cover the glass dosimeter (SRM 612), data used to determine the thermal neutron fluence.This paper presents details of the basic principles of the ITPFT technique, the practical difficulties involved in its use, and some of the results achieved.

163 CORRECTION METHODS IN FISSION TRACK DATING

Surinder Singh, Lakhwant Singh, A.S. Sandhu & H.S Virk Department of Physics Guru Nanak Dev University/ Amritsar-143005, India.

Fission track techniques is in use for dating minerals and rocks for more than two decades. Most of the ages reported in the literature are the observed ages and need corrections due to 1 anisotropy in crystalline minerals and 2 annealing effects due to geothermal events in the geological past. The effect of anisotropy and annealing on fission track age determination is discussed in this paper. A new annealing correction method based on the etch rate studies is given. The suitability of the fission track method for revealing geothermal history of geological eras is discussed.

164 THE APPLICATION OF THE ARG- AND SSNTD-METHODS IN THE GEOCHEMICAL INVESTIGATION OF GOLD AND URANIUM A.G.Mironov, S.M.Zhmodik, Y.N.Nimaev, Y.C.Ochirov Buryat Geological Institute, Ulan-Ude The autoradiography investigations of uranium and gold distribution in the minerals, ores and rocks have been carried out with the help of the solid state nuclear track detectors (SSNTD) (fluorine-phlogopite, laws on, CR-39t CN-85, LR-115) and nuclear emulsion (R, MR). The use of the macroautoradiography on SSNTD allowed to study the distribution of a sum of the aipha-radiators (U, Th, Ra) in the accessory minerals and carbonbearing black shale of large concentration ( 50 ppm). The neutron induced autoradiography has been realized for revealing the distribution of the low uranium concentration (0,1-10 ppm). The samples of the rocks and minerals have been placed in close contact with fluorine- phlogopite then irradiated by thermal neutrons flux 1-7*10 n/cm2. Detectors have been eched in HP at 25°C for 10-20 minutes. The fluorine-phlogopite detector is distinguished by the higt purity, low background in com- parision with other SSNTD. The ARG-methods have been used for the gold distribution study in the natural and synthetic minerals and ores. The distribution of invisible gold in the different ore types of the gold ore deposit has been revealed with 1Q8 the help of the activation autoradiography ( 7 Au). The peculiarities of gold localization in the sulphides and quartz, the gold redistribution in the different endoge- <|Qg nic processes have determined on the 7 Au-autoradiographic data. The autoradiography of "**Au previously introduced into a system by radioactive tracer method has been used for the study of the gold distribution in the synthetic minerals and rocks. Fission Track Determination of Uranium and Thorium in zirconium, Thorium and uranium ores Maria Lucia C.P.Carvalho (1) Joao A.Medeiros (2,3) (l)Analytical chemistry Dept., Federal university - UFRJ (2jlnstltute of Nuclear Engineering. Atomic Energy commission, (3)chemlstry Dept., Catholic University - PUC/RJ Rio de Janeiro, Brasil Analysis o£ uranium and thorium ores present serious problems using usual methods, mainly spectrophotometry, when Th content is very low, or when refractory minerals of Ti, Zr, or rare earth are present. Fission track determination of U an Th was studied for Phosphorite, Monazite, zirconite and Caldasite. Powdered samples and standards were diluted with high purity oxides or salts, to mantaln the same average atomic and mass number, and with cellulose (10%) and pressed to get pellets of 15 mm diameter and ~3 mm width, zroa and SiOa were used to dilute Zirconite and caldasite, and BaSO* to dilute monazite, in order to get samples with varying U and Th content, but about the same chemical composition or average Z and A. Pellets were sandwiched in Makrofol (0.3 mm) disks and irradiated in Brazil- lian research reactors. Samples of lower u and Th content were irradiated in a swimming pool reactor (IEA-RI). 3 3 a x Fast neutron flux of about 1.5-10 - n-cm~ -s" r near the core of the reactor, was used for Th, with closed cadmium shielding in aluminum capsules. Thermal flux of 10iin-cm~a-s~ was used for U, without shielding, in polystyrene capsules. Integrated thermal fluxes were determined with Al foils (domestic type, several Marks, with U content from 2 to 15 ug/g, which had been calibrated previously) in contact with Makrofol detectors. Integrated fast neutron fluxes were determined with Makrofol detectors on which Th solutions had been evaporated. Samples of higher U and Th content were Irradiated in a Grafite research reactor (Argonauta), at 10°n-cm~a-s-x, very close to the core, in the same way, with and without Cd shielding. Detectors were etched in 6M NaOH at 60°, for varying time, according to modified etching rate, and tracks were counted at an optical microscope (Leitz Orthoplan, 50ft x magnification). Low track densities were counted in motion, with the aid of an adapted device in the microscope. Linearity of track densities with dilution shows that effective width was hold constant. DETERMINATION OF ZETA CONSTANT FOR FISSION-TRACK DATING: A PRELIMINARY CALIBRATION BY POPULATION METHOD Inn Khuan Ng and Ah Auu Gui Nuclear Energy Unit, Ministry of Science, Technology and Environment, PUSPATI Complex, Bangi, 43000 Kajang, Selangor D.E., Malaysia.

Preliminary calibration of Zeta constant using Fish Canyon Tuff apatite age standard against dosimeter glass NBS SRM 962a had been carried out.Grains of the apatite standard were mounted in a 5x5 matrix arrangement on polyester resin. The samples were then divided into 2 aliquots; namely C and D aliquots. Grains from C aliquots were ground, polished and etched in 5 M HNOa for 12 seconds at room temperature to reveal spontaneous tracks (Ns) whereas grains from D aliquots were irradiated together with 2 dosimeter glasses (NBS SRM 962a) with inuscovite external detectors in close contact, in the rotary rack of the PUSPATI TRIGA Reactor at lOOkW for 1 hour, then ground, polished and etched to reveal a mixture of spontaneous and induced tracks (Ns+Ni). All the samples were irradiated again under the same reactor condition for 4 hours with muscovite external detectors in close contact. All the muscovite detectors were etched in 48% HF for 25 minutes at room temperature to reveal the tracks registered. These tracks are; the induced tracks, on external detectors for grains in C aliquots (NEDC) and D aliquots (NEDD), and induced track density on external detectors for dosimeter glass (fb). The expected value of Ns/Ni were obtained from the regression equation between Ns and NEDC as well as between Ns+Ni and KKDD for each set of samples (a set^fsamples consists of one each from C and D aliquots). The Zeta value obtained from this work was found to be 224.52 + 38.73, showing significant difference from that obtained by workers elsewhere using eoaipatible dosimeter glasses NBS SRM 962 and 612. The discrepancy in Zeta values could be due to a number of factors and it is premature to confirm the reliability of the Zeta value obtained from this work at this early stage. It is hoped that eventually the technique can be refined to the level required for fairly routine analysis. URANIUM CONTENT AND AGE DETERMINATION OF VARIOUS MINERALS OF IRAN H. Afarideh, M. Faghih Habibi* and F. Hashemi Atomic Energy Organization of Iran, P.O. Box 11365-8486, Tehran, Iran * Physics Department, Amir Kabir University of Technology, Tehran, Iran

Abstract

In this study we have used Fission Track Method (FTM) to obtain age and uranium content of minerals. The minerals used were: Apatite; Obsidian; Calcite; Fluorite and Sphene, collected from different parts of the country. For the preparation of samples, they were cut into small pieces and embedded in an epoxy resin and after grinding and polishing were put in close contact with Makrofol E as an external detector. Whole assemblies were irradiated in a thermal neutron flux of 6.8 x 1012 n/cm2 of the swimming pool reactor at the Nuclear Research Center of Atomic Energy Organization of Iran, the assemblies of standard glass (NBS) with Makrofol-E also used for irradiation, in order to determine uranium content of minerals. After irradiation, the external detectors and those minerals under investigation were etched in suitable etchant. The etched tracks were counted and then the standard formulas for calculating the uranium content and age were used. A typical result for uranium content of Apatite was in the range of 1.06 to 4.88 ppm. ON DETERMINATION OF THE TRACK AGE OF SOME NATURAL CRYSTALS.

I.G.Abdullaev*1J, G.G.Bankova*2*, L.Enchjin*3*, gh. O.0tgonsuren'3), V.P.Perelygin*2*, R.I.Petrova*2*

1j$iudjant State University, 735600, jtfiudjant, Tadjikistan. Joint Institute for Nuclear Research, 141980, Dubna, Russian Federation. 3Mongolian State University, Ulan-Bator, Mongolia.

Abstract 238. The fission fragments due to spontaneous fission of "°U nuclei produce latent tracks in the natural crystals. These latent tracks can be chemically, revealed after many hundred million years their formation. It provides the possibility of determination of so-called track age of the crystals and more over in some case - the information about the fermal history of geological object being investigated. In that connection the detailed investigations of annealing behavior of fission fragment tracks in muscovite mica, apatite and whitlocite crystals have been performed. For rauscovite mica the annealing procedure has been applied to single fission fragment tracks, for apatite and whitlocite crystals - for binary events. As it has been observed, the controlled annealing produced the shortening down of fission fragment track length. Such procedure provides more direct comparison of the track length spectra due to 2 3 8 spontaneous fission of U and due, to thermal neutron induced 235 fission of U in the same crystal. Such a procedure al?_ one to obtain more correct value of the track age. The track ac,o.; of five crystals at muscovite and phlogopite mica, three garnet crystals, two apatite crystals from Europa and Asia ore deposits and whitlocite crystals from Marjalahti meteorite were measured: The problem of search for spontaneous fission events due to unknown natural long-lived nucleus - the products of nucleosyhthesis in the Solar System about 4.7 B.Y. ago is discussed.

169 EFFECT OF RADIATION DAMAGE ON THERMOLUMINESCEIICE AND INFRA-RED PROPERTIES OF NATURAL APATITES. A.F MD. NOR > Y.M. AMEN , E. MAKAT • Thermoluminescence & Nuclear Tracks Laboratory Department of Physics, University of Malaya 59100 Kuala Lumpur, Malaysia. B. KAMALUDDIN Solid State Laboratory Department of Physics, University of Malaya 59100, Kuala Lunpur, Malaysia.

Thermoluminescenee (TL) and Infra-red (IE) spectra from various natural crystals of Apatite have been examined. All naturally damaged samples (the amount of damaged being monitored.by their fossil fission track density) vere found to exhibit a reduced contribution in the tL.'rmolumineseence glow intensity relative to that undamaged one. Annealing for 1 hour at different temperatures resulted in an increase in the thermoluminescence sensitivity starting at an annealing temperature of ^50° C : a maximum vas observed at annealing temperature of TOO°C - 800°C, after which the thermoluminescence sensitivity decreased steadily with increasirg temperature. Infra-red spectra of apatite did not show any noticeable change in shape and position of the absorption bands. X-ray diffraction studies on apatit-s shows it still retain ' its crystallinity even though the track density has reach to about 1012 tracks/cm2 .

170 GROWTH RATES OF THE FERROMANGANESE NODULES OBTAINED BY THE CELLULOSE NITRATE DETECTOR LR-115 I.E.Vlasova (P.P.Shirshov Institute of Oceanology, Russian Academy of Sciences. 23 Krasikova st., 117218 Moscow, Russia)

Nine pelagic ferromanganese nodules from the South-Eastern Pacific dredged from the R/V "Dm.Mendeleev"(the 14-th leg) have been analyzed by the alpha-radiography technique using the nitrate cellulose detector LR-115 (type II). The small detector slices were sticked to the nodule polish sections in the radial direction from the nodule surface to its nucleus for 10 months. Then the detectors were etched in 6S NaOH at 50° for 1 hour to reveal the alpha-particle tracks. Recorded distribution of the total alpha-radioactivity was measured along the radial zone 1.0-1.5mm wide through every 0.125mm. Some nodules were examined in two different directions (samples 994-2 and 1007-2). The obtained results (Table ) characterize the growth processes in the subsurface layers of the nodules.

Sample Position Depth, Nodule Growth rate number m radi us,mm mm/m. y.

983-1 39°56^S 5470 21 5.5

984-1 51°30^,S 4830 9 13.0 135°30'w 994-2/1 48°19'\S 4530 9 4.0 96°28 K 994-2/2 11 0 985-1 48°45^S 4050 5 11.5 130°00\W 992-2/a 49°11 S 4280 7 13.5 98°34'w 992-2/b 6 7.0 993-3 48°35^,S 4430 5 9.5 97°38^W 1005-2 39°04^,S 4635 6 1.0 124o60'w 1007-2/1 SB^o's 4340 5 9.5 121°30 V 1007-2/2 6 1.0 STANDARD RADON CALIBRATION CHAMBER USING SSNTDS

M.A. EL-FIKI, H.A. KENAWY*, H.M. EISSA, M.A. SHARAF AND M.L. ABDEL-HADY.

* University College, for Girls, Ain Shams University, Cairo. National Institute of Standards, Cairo, Egypt.

A Radon standard chamber for calibration the equipments used in research on Radon and its decay products has been designed and constructed. The chamber equipped with different facilities to control and monitor the conditions inside, such as ventilation, temperature, humidity... etc are described. Passive Radon measuring techniques, among them SSTD'S has been used. The calibration, factors for these detectors were determined.

172 PIN DETECTOR FOR CONTINUOUS RADON MONITORING

CDEVILLARD', D.KLEIN2, A-CHAMBAUDET* and R.BARJLLON'

1- Laboratoire de Microanalyses Nucleaires, UFR des Sciences et Techniques, La Bouloie. Universite de Franche Comte, 25030 Besangon Cedex, France 2- Laboraioire de Metrologie des Interfaces Techniques, IUT de Belfort-Montbeliard, Universite de Franche Comte, BP 527, 90016 Belfort, France

In order to increase the different kinds of alpha ionizing radiation measurements, silicon PIN diodes have been developed to measure continuously the radon concentration in both fields of Earth-Sciences and Radioprotection.

The progresses in detection microelectronic enable today to use silicon PIN detectors in addition to nuclear track polymeric detectors. In this way, a prototype device was performed.

Different tests and measurement intercomparisons with the other techniques were realized in Laboratory using a standard radon source and were also performed in fieldwork.

The first results show that this new technique can be used instead of nuclear track polymeric detectors with a higher sensitivity but so far the measurements are not accurate enough in a gas flow.

173 USE OF ALPHA SENSITIVE PLASTIC FILM (ASPF) TECHNIQUE TO LOCATE THE RE-MOBILIZED URANIUM ORE BODIES IN SANDSTONES

A.A. QURESHI1, M.A.S.BEG2 and H.A. KHAN1

1. SSNTD-Laboratory (NED), PINSTECH, P.O. Nilore, Islamabad, PAKISTAN 2. Atomic Energy Minerals Center (AEMC), Ferozpur Road, Lahore, PAKISTAN

ABSTRACT:: Uranium mineraliration occurs in Pakistan as lenses and remobilized ore bodies in the Siv-alik System of rocks. The Sivvliks consist of detrital sandstones and are exposed over a vast area from Pakistan-India border to Mekran Coast. They are the only source of uranium in the countr}'. One of the problems related to uranium exploration in these rocks is the young age of re-mobilized ore bodies due to which gamma counters and logging units do not respond properly. Hence ruthless drilling is required for the exploration cf these deposits requiring tremendous amount of expenditure. Use of Alpha Sensitive Plastic Films (ASPF) Technique based on the measurement of radon gas, coming from the deeply burried uranium ore bodies provides a reliable time integrated method for the location of such ore bodies. The technique is. versatile, simple, inexpensive and does not require complicated instrumentation. This technique has been applied in Pakistan for exploring the re-mobilized uranium ore bodies in sandstone terrain. In this paper, we present our experience of exploration in Bannu-Basin where uranium mineralization occurs as re-mobilized ore bodies in sandstones. The uranium mineralization seems to have been mobilized several times due to water table fluctuation and equilibrium between uranium and daughters has yet not been attained. The ASPF-technique has been found to be quite useful for the exploration of such deposits and geological terrain.

174 RADON DIFFUSION STUDIES IN WATER, SOIL, AIR, CONCRETE AND SAND

Baljinder Singh and H.S. Virk Physics Department, Guru Nanak Dev University, Amritsar - 143 005 (India).

Radon diffusion studies are carried out in water, soil, air, concrete and sand using plastic track detectors (LR-115 type II and CR-39) and electronic measurement techniques using alphameter 400. In this paper results of diffusion rate, diffusion constant, diffusion length are reported. Theoratical and experimental results are compared. RADON: A TOOL FOR GEOTHERMAL ENERGY PROSPECTING IN EL SALVADOR

M. Balca"zar, E. Gonzalez*, M. Ortega' and J. H. Flores.

Inst. Nal. de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico, D. F. * Inst. Inv. Etectricas. Apdo. Postal 475, 62000. Cuernavaca, Mor., Mexico. * GEOCEL, El Salvador, Centroam6rica.

Under an agreement, Mexico is taking part in the potentiality evaluation of geothermal energy in El Salvador, Centroame'rica. The first studies have been carried out in the Ahuachapan region which is located in a recent volcanic belt on the central east part of the country. Geochronologicaland geological studies located a probable production zone to the north of the volcanic belt in a region named Ahuachapan-Chipilapa. Hidrothermal activity and geochemical analysis indicate the existence of active geothermal faults aligned to the directions South-North and Northwest-Southeast. Radon mapping in that region covered a total of 8.7 km* where plastic detectors were placed 200 m apart. The results confirmed the existence of active faults. A discussion on the implication for locating the main heat source is given in the light of radon concentration obtained in the field. RADON CONCENTRATION MEASUREMENTS IN A RADON CHAMBER FOR BIOLOGICAL TREATMENT USING TRACK DETECTORS.

L. Tavera, M. E. Camacho and M. Balcfizar. Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico, D. F.

An experimental set-up was designed and calibrated for controlled exposition of biological systems to radon atmospheres, to investigate the effect of no-fetal radon doses. The set-up consists in two interconnected pexiglass-made chambers. The source chamber contains 0.987 g of pechblenda mineral, whereas Biological Treatment chamber is used to put in it different biological systems as: Tradescantia. Prosophila and Escherechia coli. In the treatment chamber the biological systems can be exposed to different radon concentrations. LR115 track detectors are used to measure the mean radon concentration as well as local differences in alpha particle distribution. Measurements were performed for both, to fix up the conditions before the biological systems were exposed and to determine the local radon concentration during the exposition, from which correction factors are obtained. Radon distribution in the treatment chamber are explained in terms of temperature variations and environmental impact produced by the biologica material in the chamber. RADON DIFFUSION THROUGH THIN PLASTICS

A. ChaVez, B. Cervantes* and M. BalcSzar Inst. Nal. de Inv. Nucleares. Apdo. Postal 18-1027. 11801, Mexico. D.F. • Department of Physics, University of Sonora, Mexico.

Radon diffusion properties of thin plastics such as polyethylene, cellulose nitrate and policarbonate, were determined using surface barried detectors coupled to a radon generator system. The generator system consists of a small sealed box containing 800 g of Pechblende from which radon passes through a valve to a versatile experimental chamber. Several accesses to the chamber permit to place inside ensembles of PVC tubes, protected on one end by a thin plastic and connected to a surface barried detector on the other end. Tubes are 5 cm in diameter and of several lenght up to a maximum of 30 cm. A multichannel analyzer in the multiscaling mode registered the radon concentration as function of time. The analysis of the above curves give radon diffusion properties of thin plastics. So far polyethylene and LR115 plastics have shown better diffusion characteristics. In another set of experiments, two PVC tubes, 150 cm in lenght were connected, one horizontally and the other one, vertically to the chamber, both protected by thin plastics. Several LR115 detectors were put inside the tubes to obtain distribution of radon along the tubes. PASSIVE RADON PERSONAL DOSEMETER

S. Djeffal . and M. AJJab 1- L'aboratoire de Dosimetrie, Centre de Radioprotect ion et de Surete, 2, Bd. Frantz Fanon, B.P. 1017, Alger, Algeria 2- Institut de Physique, Universite des Sciences et de la Technologie, El-Alia B.P. 32,-Bab Ezzouar, Alger, Algeria

Abstract The Dosimetry Laboratory of the Radiation Protection and Safety Centre in Algiers has developed a passive radon personal dosemeter. Based on the diffusion principle, it consists of an enclosed chamber into which radon gas diffuses and which contains a nuclear track detector for registation of alpha particle tracks. The radon diffusion chamber is either of cubical or cylindrical geometry with a track detector at one end and a polyethylene membrane at the other. It is designed to be used in atmospheres, where high humidity is present such as in mines, it also excludes radon progeny and detritus. It presents the advantage of being simple, cheap and robust. In order to optimize the dosemeter response, several tests were performed at laboratory scale, on different cham ber geometries. For the determination of the sensitivity factor, the calibration measurements were carried out at th NRPB radon exposure facility. In this paper, the design and the characteristics of the dosemeter as well as some result of the optimization studies are reported and discussed. I COMPARISON OF SHORT-TERM RADON MONITORING TO LONG-TERM AVERAGES

D. AZIMI-GARAKANI Radiation Hygiene Division, Paul Scherrer Institute CH-5232 Villigen PSI, Switzerland

The reliability of short-term radon measurements as low as one week for predicting annual radon concentration is described. The study is based on the continuous weekly radon level measurements in three different indoor environments over a period of entire year. Week-to-week variations during individual months and over various seasons are presented and statistically discussed. The measurements were made using envelope-type radon sampler with cellulose nitrate damage track detector. THEORETICAL DETERMINATION OF CALIBRATION COEFFICIENT FOR RADON MEASUREMENTS WITH CR 39

D. Nikezirf, D. Krstid, P. Markovid. B. Jovanovid Faculty of Natural Sciences, Physic Department, 34O00 Kragujevae, Yugoslavia

A solid state nuclear track detector CR 39 has been widely used for measuring radon concentration in the air This paper describes the calculating model for calibration coefficient determination for radon measurements. The model. is based on Bethe-Block*s expression for stopping power for heavy charged particles, as well as on the Monte Carlo Method. Calibration coefficient for CR 39 detector for radon measurements depends on equilibrium factor F and etching conditions. It has been calculated for various values of F, and different etching conditions. Obtained theoretical results are compared with e>d sting experimental data.

.*>:• INVESTIGATIONS OF RADON IN SUBSURFACE SOIL AND WATER AS AN EARTHQUAKE PRECURSOR

Manwinder Singh, Surinder Singh & H.S.Virk Physics Department, Guru Nanak Dev University Aroritsar 143005, India

In order to achieve earthquake prediction, observations of various kinds of geophysical and geochemical phenomena, including radon measurement, have been carried out on a word-wide basis. Natural water always contains radon in detectable quantities. Recent observations have shown that changes in soil gas and groundwater radon concentration can be used as a method for earthquake prediction. He have monitored radon in soil-gas and groundwater at Palampur, (Kangra Valley, Bimachal Pradesh) in the North-Western seismic zone of India, located on the Main Boundary Thrust (MBT) since 1989. The effects of meteorological variables and other geophysical parameters on soil gas radon are also studied for identification of radon signals above the noise. A significant increases in radon concentration of soil-gas and groundwater are observed which are correlated to the seismic events occurred in Northern India. MEASUREMENT OF CONCENTRATIONS OF RADON AND ITS DAUGHTERS IN INDOOR ATMOSPHERE USING CR -39 NUCLEAR TRACK DRTECTOR.

S.M.FARID

Department of Physicr University of Swaziland, Swaziland, Africa.

ABSTRACT

Public exposure to radon and its radioactive daughters present in the environment results in the largest contribution to the average effective dose received by human beings.This paper presents the results of the measurements of indoor aa2Rn and daughter levels in houses of different types located in different parts of Bangladesh.The passive time-integrate method of using a solid state nuclear track detector was employed for measuring both the ^^Rn gas concentration as well as the potential alpha energy exposure (PAEE) level from the short lived daughters of xxiRn.We have used CR-39 as the detector.lt was exposed to indoor environment of a house for a known period of time in two modes,(a) bare and (b) in a cup with a membrane. After retrieving the detector.it was etched chemically in 6M NaOH solution at 70* C and the tracks formed were counted microscopically.The •^tlRn concentration from cup exposure and the PAEE from the bare exposure were obtained directly from the track density using calibration curves.A total of 310 exposures were made in the bare mode in 13 locations and 70 exposures in the cup mode in 7 locations.The geometric mean PAEE level obtained is 9,6 mU'L with a geometric standard deviation of 1.8. The corresponding value forazxRn concentration are 61.3 BqirT* and 2.A. The total data was collected over a period of one and a half years. The monthly variation of the geometric mean of both PAEE andatl"Rn are also shown.The annual effective dose equivalent has been estimated for each location by using the conversion factor of 9 mSv per VLM as obtained from ICRP-50. The average PAEE level obtained from the total data is below the intervention level as suggested by US EPA. However, the individual averages for each location show that in 6 out of 13 locations intervention may be considered and in others no intervention is called for. The *2lRn concentrations at the seven locations are equal or less than the equilibrium equivalent Rn concentration value as suggested by EPA. Attempts have also been made to see the variation in the PAEE levels according to different type of construction material used for tfro houses. EXHALATION OF 222Rn FROM PAPERS R.C.Ramola Division of Biophysics, University of Salzburg Hellbrunrier Strasse 34, A-5020 Salzburg, Austria

ABSTRACT

A number of publications in last few years demonstrate the increasing interest in indoor radon concentration. The primary sources of radon and radon daughters in building are the soil adjacent to the building, potable water supplies and building materials. The indoor radon concentration is dependent on many factors, such as ventilation conditions, infiltration rate and meteorological conditions. Radon in -mbient air or home heating fuels may also contribute to indoor radon levels. Another possible source of indoor radon may be books present in a room. Efforts are currently being made to investigate the sources of indoor radon. In this paper some preliminary results of unidirectional and all round exhalation of radon from several sheets of paper are reported. The measurements were carried out by surface barrier detector and ionization chamber. For Unidirectional measurement the recorded values of 222Rn exhalation rate range from 3.23 to 7.72 Bq m"2h~1. The radon concentration in a cubic chamber is found to be 661 Bq m~3, quite high than the background radon concentration inside the rocm. The exhalation of radon from paper is due to its manufacturing processes and its relation with plants and trees. The preliminary results reported in this paper show that the contribution of radon from books in indoor atmosphere can not be ignored particularly in the libraries where a large number nf books are oresent. CHiRACIEBISAIION OF SOIL PAPAMFTFRg FOE RADGN ASSESSMENT IN HDMfiN ENYHtOKMEKIS.

N.P.SINGH LONGOWAL INSTITUTE OF ENGINEERING & TBCHNOLOGY(L.I.E.T) LONGOWAL:DISTT:SANGRUR: PUNJAB(INDIA)

Radon in dwellings is contributed by five sources i.e. natural gas, tap water, fresh air, building materials and the subjacent ground. The contribution of the first four to indoor concentration is generally low. High values, when they occur, are attributed to the high influx of radon from the ground on which dwellings stand. Although, the behaviour of radon and its short iived decay products in indoor air arises as a result of complex interplay between a number of processes but the radon influx from ground depends upon its generation and movement into dwellings. Thus for radon assessment it is of prime importance to know radon movement from ground into dwellings.

Accordingly, the soil parameters (i.e.permiability, humidity and temperature) influencing the radon movement are characterised to calculate the radon influx from ground into human environment. To test relationship between radon influx and soil parameters, the correlation coefficients and factor structures are evaluated. The maximum values of correlation coefficient and factor loading are found between radon influx and permiability of the soil. The influence of the above factors on radon influx independently of source of generation is discussed.

The contribution of radon influx, in radon in dwellings is also tried to calculate. Diuranal and seasonal changes of radon influx and hence their effect on environmental radon is reported.

185 RADON MEASUREMENT IN DWELLINGS AROUND THE HOT SPRING IN THE NORTH WEST OF IRAN

N.A. karamdoust and K. Afarideh* Faculty of Education, University of Tehran Tehran, Iran Atomic Energy Organization of Iran, P.O.BOX 11365-8486 Tehran, Iran

Abstract The exothermal ' fluidee carry natural radionudides and especially Rn-222, which is discharged into the atmosphere. Therefore, it is expected that the radon concentration to be high in dwellings around the hot springs. This measurement is interesting at least from three points of view: 1) There are many hot springs in the region, 2> The region has cold climate so much so that its temperature is about or below zero c for about 6 months of the year C autumn and winter >. So, during this period of the year the air exchange rate for dwellings reduces to its minimum vaJue C i.e about zero >, and 3> The region was also affected by a major earthquake which occured in the north of the country about two years ago. In order to carry ovjit this measurement several guest-houses and homes were chosen in different locations around the hot springs. In the first floor of each building one room was selected. Passive radon dosimeter using CR-30 plastic was placed in each room and the room was closed for a period of about 2.5 months. After this period of time samples were collected, etched and radon concentrations were determined. Our results show that ».h«? •_-.v.ier;iiIa-i.*u r»do» concentrations, in general, are high and in some cases it is well ijf.ove the limitation value recommended by 1CRP for future homes C i.e. 200 BqXm J. It is important to mention here that durjr.g the course of this measurement there was an earthquake in the region v hich may hive some effect on the results.

186 ESTIMATION OF INTERNAL AND EXTERNAL DOSE EOUIVALENT RATES FOR THE DWELLERS OF DERA ISMAIL KHAN AREA - PAKISTAN

M. Tufaii! Matiullah1, N. Ahmad5 and E-U. Khan2 1) Centre for Nuclear Studies, P.O. Nilore, Islamabad, Pakistan 2) Physics Department, Gomal University, Dera Ismail khan, Pakistan

Data on radon concentration in the dwellings of Dera Ismail Khan area and the gamma ray activities in the brick samples used in that area has already been reported in a paper presented at the Marburg Conference. Based upon that data we have estimated the internal dose to respiratory tract due to radon daughters and the external dose to whole body from the gamma ray activities in the rooms made of clay bricks. For internal dose calculations, the radon concentration has been • converted to equilibrium equivalent concentration (EEC) by multiplying it with equilibrium factor of 0.5 as recommended in UNSCEAR report of 1982. The EEC has been converted to dose equivalent rate using the conversion factor of ICRP-50. The external dose from the gamma-ray activities has been determined by using a mesh adoptive method developed at our centre (CNS) for model rooms constructed from various materials.

187 FAST NEUTRON ENERGY AND ANGLE RESPONSE OF ELECTROCHEMICALLY ETCHED CR-39 PLASTIC DETECTORS F. Fernandez, C. Domingo, B. Tayeb, E. Luguera and C. Baixeras Fisica de les Radiations. Depart amen t de Fisica. Universitat Autonoma de Barcelona. E-08193 Bellaterra (Barcelona). Spain.

The dose equivalent response (cm^'mSv"1) of a fast neutron dosemeter, composed of a polypropylene converter and CR-39 plastic track detector, has been calculated for several neutron incidence energies and angles using a Monte Carlo method. Limitations in proton energy and incidence angle in order to obtain visible tracks are imposed by means of a detection efficiency function. The calculation shows how the variations of the converter thickness and of the electrochemical etching conditions affect to the dose equivalent response. The theoretical calculation is compared with experimental results obtained from neutron irradiations using detectors with protonic equilibrium thickness converters. The agreement between measured and calculated values is good within experimental errors for neutrons with energies from — 140 keV to — 5 MeV.

188 CALIBRATION OF VARIOUS TYPES OF CR-39-BASED NEUTRON DOSIMETERS IN A HEAVY WATER MODERATED AND MONOENERGETI C NEUTRON FIELDS - PART-II: EXPERIMENTAL

MATIULLAH1*, K. KUD02) AND X. YANG3)

1) Centre for Nuclear Studies, Nilore/ Islamabad, Pakistan 2) Electrotechnical Laboratory/ 1-1-4 Umezono, Tsukuba-shi, Ibaraki 305/ Japan 3) Radiometro I ogy Center/ Institute of Atomic Energy, P.O. Box 275(20), Beijing, P.R. of China

In Part-I of this paper/ computer calculations concerning the determination of calibration factors of various types of CR-39-based neutron dosimeters were described. Here i.n Part- 11/ related experimental work is presented. Different types of CR-39 based neutron dosimeters were irradiated in free air and on a water phantom with monoeneroetic neutrons and in a heavy water moderated 2^2Cf neutron field. The detectors were then processed and tracks cm"2/ECE spots cm"2 were determined using a microscope or automatic counting system. Finally, the tracks cm"2 / ECE spots cm"2 were related to the neutron dose equivalent.

189 Study on Effect of Neutron Radiation on Cfi-39 atd surface of CR-38

Zhang Goangli (Departaent of Chemistry. Beijing University) and Feng Vushui (Laboratory of Industrial Hygiene. Ministry of Public Health* Beijing)

It has been found that CR-38 plastic as solid track detector has the properties of high sensitivity, good hoaogeneity. and clear contour of tracks. Up to soi> however* the known reason of these facts is that the plastic consists of a tridiaensional structure* and part of the cross linkea polyaer undaaaged by cheaical etching foras a clear background: little is known about the aechanisa in aore detail.

la this study the changes of residual double bonds in CR- 39 before and after neutron radiation were ceterained, i.e. C=C7.=0.837< and 0.667.. respectively. The aoleoular weights of its hydrolysate* allyl alcohol polyaer chain* before and after irradiation were deferained. Mn being 1.83X10" and 1.70X10*, respectively, and Si. being 7.39X10" and 12. 2 X10". respectively. It follows that part of residual double bonds were initiated and dioappeared in the course of irrdlation. and the changes in aoiecnlar weights account for that the effect of rediation cross linking of allyl chain is higher than that of radiation degradation. However, these are no aarked changes in the chemical structure of CR- 39 as seen froa solid "C-NHR spectra. In order further to ascertain the reason of high seusitivity and clear track contour of CR- 39 in track detection* the surface ot the polymer was observed under scanning electron aicroscope* • and daaaging effect of neutron radiation on the surface was found; surface infrared spectrosocpy reavealed that the higher the radiation dose. the greater the surface carboxy group absorption (1734ca~*) while the absorption of the non- irradiated saaples was quite slight: and ESCA study of the surface exhibited that after careful scraping of the surface of sasple* the ratio of nuaber of

190 atons between carbon and oxygen was 1.S8 for the denuded surface, i. e. within the range of experimental error as compared with the theoretical calculated value of 1.71 while the C/0 ratio for the infact surface was 3.

It is concluded from the above data that the determinant of this plastic being a good material for track detection is the particular structure abundant in C-C bonds in its surface. Under the condetion of etching by strong base* the C-C bonds in the surface are stabler and only ester bonds are hydolyzed. Neutron radiation damages part of C- C bonds in the surface and exposes the looal ester bonds while the surface with undamaged C-C bonds still isolates and protects the ester bonds underneath from contact with alkaline solution in the chenical etching. The background observed under microscope is precisely the surface with undamaged C-C bonds; and the etching pits as measures of radiation doses are formed by hydrolysis of ester bonds under the local surface with damaged C-C bonds.

191 THE a-^CTIVlTY AND THE HOT PAHTICI.E SIZES IN THE VICINITY OF THE CHERNOBYL NUCLEAR POWER PLANT

A.B.AKOPOVA, N.V.MAGRADZE, A. A.MOISEENKO, K .M.OVIiAKIAN Yerevan Physics Institute, Yerevan

V.V.DEMCHUK, N.V.VIKTOROVA, E.B.GANZHA UkrNIGMI, Kiev

A.M.MARENNY NICREKO, Moscow

It is known, that the contamination as a result of the Chernobyl accident substantially differs from that resulting front nuclear tests by the fact, that beside different volatile hot substances, the nuclear fuel was also blown up into the atmosphere. The present work is devoted to an experimental investigation of the behaviour of the fuel part of the precipitation in the flood-lands near the Pripyat river, 7 to 8km North from the Chernobyl nuclear power plant. A modification of the autoradiographic method is developed that allows us to make good-precision estimations of the total activity in the contaminated areas, avoiding labour-consuming microscopic measurements. The method is simple and economical, so it may be recommended for global investigations of the a-active contamination of the areas in the vicinity of and distant from the Chernobyl plant. Nuclear emulsions and plastic CR-39 were used as detectors. The results show a substantial contamination of the area flooded by the Pripyat river, where the density of contamination by a-active hot particles is by an order higher than that in the non-flooded side in the upper (0-10mm) layer of the soil (note that more than 85% of all hot particles of sizes 30-220^m are concentrated in this layer). We also present the data for the surface, volume and specific densities of contamination by a-active hot particles in the flood lands by the Pripyat river.

192 OH THE IMPACT OF NUCLEAR TRACK SIEKCE FOR RECORDING THE EFFECTS OF RADIOACTIVE ENVIRONMENTAL INTERACTIONS IN BIOLOGY

Madhuri Sharma and A.N-Kaurya

D.S.Postgraduate college(Agra gniversity)>Aligarh. (INDIA)

•ABSTRACT

The Various uses of Nuclear Track Science in different biological aspects h&y'tDeen discussed.. The role of heavy ions (Uranium ions) s.e trace elements in plants and animals has been shown and the biological effectiveness of radioactive radiations has been estictated The impact of radioactive fall out and environmental interaction on certain plants around Narora Atomic Pov/er Station (in Northern India) has been discussed*.

193 QUANTITATIVE NEUTRON ACTIVATION AUTORADIOGKAPHT OP EXOGENOUS Ii IN RAT TISSUES 31 SSNTD V.Ye.Zaichick Institate of Medical Badiology, Obninsk, Bussia

The path length for the capture reaction products of 6Li. , -* U neutrons is compared to the cell sizes. It provides for irradiation mainly of a tumor during the neutron-capture therapy preserving not only the adjacent tissues but the tumor stroma itself. It was suggested that exogenous Li might be effectively used for the neutron-capture therapy of myogenie sarcoma metastases in lungs. In this connection the metabolism of this nuclide in rats was studied including lungs affected by metastases of Walker-256 carcinosarcoma. Thus the technique of quantitative neutron activation autoradiography with SSNTD was developed since it offered no possibility of using a common technique with photoemulsion because of a very high attendant background from protons. The technique consists in preparing a"sandvich* of a thin frozen microscopic section of the examined organ tissue or total animal carcass put over a nitrocellulose(KC) film.Such a "sandwich" in a frozen state is irradiated within the reactor thermal channel. Then the NC film is taken off and etched with alkali while the microscopic section is fixed and coloured. A part of * -particles foamed in the section pene- trates into the NC film creating microdestructions which become visible after etching with fQVali, looking like tracks by means of a common microscope. The 6Li content in tissues and organs of interest can be analysed according to the density of tracks, the NC film being matched the coloured section. As a result of the present study it was in particular shown that the largest value of the concentration ratio for Li in metastases and adjacent areas of lungs was achieved 3.5 times on the average in 3 hours after intraperitoneal injection of Jfc6 LiCl solution.

194 APPLICATION OF TRACK DETECTORS FOR SOIL, WATER AND OBJECTS' SURFACES ALPHA-ACTIVITY MEASUREMENT IN 30-tan ZONE OF THE CHERNOBYL NPP.

GromovA.V., V.E.Kopchenov, A.S.Krivokhstskiy, V.A.Nikolaev RPA "V.G.Khlopin Radium Institute", Saint-Petersburg S.V.Stolyarov, V.V.Tokarevsk iy Ukranian AS Institute for Nuclear Research, Kiev

The track method based on nitrato-cellulose detectors and spark count of tracks was applied for measurements of objects" alpha-activity in the 30-km zone of the Chernobyl NPP in 1986 and 1990. In September-October of 1986 track detectors were applied in the cases when the use of alpha-radiometers was hampered or impossible because of: - high background of beta-gamma radiation which influenced the readings; - large dimensions of radiometers which did not allow to carry out measurements in places of equipments and buildings difficult to access and also in the case of measurement of spatial distribution of alpha-activity in many points simultaneously. In 19S0 the application of track detectors was conditioned mainly by their high sensitivity and possibility of large-scali measurements by bench-mark points network.

195 URANIUM ESTIMATION IN THE BLOOD OF POIKILOTHERMIC AND HOMOIOTHERMIC ANIMALS.

K. C. Das, Department of Zoology, Pandu College, Guwahati-781 012, Assam : India. T. D. Goswami, Department of Physics, Gauhati University, Guwahatj-781 014, Assam, India. ABSTRACT

The present study is an investigation of the trace element, uranium in the blood of two categories of animals (Poikilothermic or Cold blooded animals and homoiothermic or Warm blooded animals) by using nuclear etch Technique. The various groups of animals like lata fish, toad and garden lizard have been selected from the poikilothermic category whereas pigeon and guineapig have been selected from the hormoiothermic category. Blood samples have been prepared by collecting known volume (0.01 ml.) of blood from individual animal (of both sexes), with a population of 50 for each group.

The urammum content in the blood of poikilothermic animals has been found to vary from (0.27 + 0.018) to (0.62 ± 0.02S) micrograms/Jitre and in case of homoiothermic animals it varies from (0.55 ± 0.027) to (0.95 t 0.037) micrograms/htre. The analysis shows that U-content of homoiothermic animals (0.72 + 0.J16 rrucrograms/litre) is slightly higher than that of poikilothermic ones (0.46 ± 0.0&5 micrograms/litre). This higher value of uranium is significant as it may be one of the contributing factors for raising the body temparaiure in case of homoioihermic animals.

196 Oil THE U3AITIUI.1 DISTRIBUTION IN THE Ii:TI33SAL COiTTAIJIITATIOIT Llaria CUCU, Ana DAKTS, Lisrisna CIU30TAEIU, S.IAi^GU, Gabriels SDIilTRISCU Institute of Physics and j;uclear I^igineeriiig, Bucharest

In the previous researches, the authors proved the unexpected possibilities offered by track detection for internal radioactive contamination investigations. It is the authors'intention that using the fissionable elements and the fission track method, each of the internal radioactive contamination ways: ingeretion, inhalation, ebsorbtion by skin and by wounds ,to be investigated. In this paper only the preliminary results on the fissionable elements absorbtion by wounds are described. The uranium has been used as fissionable element. Two breed ,;istar—London rats 7/ere contaminated with uranium solution by the moistening their wounds placed on the back in the 2ieck region. The same uranium solution diveded in 10 identical amounts has been administered in different v/ays to both rats: to one the doses have been given for 14 days and to the other one for 35 days. Three days after the last uranium administra- tion the rats were sacrixied. Their soft tissues as well as the evacuation components sampling during the contamination to each 24 hours, were analysed by the fissinr track method, before and respectively after the calcination.The uranium track micronappin^s obtained for the rats led us to conclude: a) the uranium is transpor- ted by the blood in whole body; b) it is possible to establish the following radiosensitivity of certain ret organs in respect with uranium: the kidney,followed by the spleen,liver and rig.l- Sftril o :ht U distri- lung; c) the uranium eva- bution in F rr-t kidney cuation in the first tv/o days after e&oh dose of uranium is different in comparison with that one for following days; d) the uranium track micromappings obtained for the soft tissues samples represent a possibility to visualize the uranium distribution in the investigated organs (see fig.l); this fact can have a great implications in physiological studies.

197 PRODUCTION AND APPLICATION OF PARTICLE TRACK MEMBRANES IN HUNGARY

Gabor Dajko Institute of Nuclear Research of the Hungarian Academy of Sciences H-4001 Debrecen, P.O. Box 51. Hungary

Starting four years ago we have developed an equipment on purpose to prod uct track membranes. For lack of a heavy ion accelerator the irradiation of polyester foils is solved with proton induced fission fragments of a Th target. Plate and spiral modules, working on the cross flow system, have been devel oped from the track membranes. A measuring system was designed in order to de termine the characteristics of the modules. Some different small model equipment have been constructed. Some characteristics of these models are shown too.

198 02? THE RADIOCOLLOIDAL AHD PSEUDORADIOCOLLOIDAL STATE OP THE FISSIONABLE ELEMENT SOLUTIONS

Ane DAITIS and Meriane CIUBOTARIU Institute of Physics and ITuclear Engineering, P.O.Box 5206 Bucharest, Romania

Sisteaatic studies on the radiocolloidal end pseudoradiocolloidal states process have been performed taking two aims: to obtain the solutions with homo£« leity for g long time and to use this process in the secondary recupe- retion of the fissionable elements. The beheviour in time of the URANIUM solutions have been investigated by the fission treck method talcing into account the influence of sone chenical and physical fsctors such as: the chemical compound of uranium, the uranium concentration, the pK of solutions, the purity of solvent, as well as external irradiation factors. Up to the present our experimental results led us to conclude: -^ - it is possible to obtain for e long time the homogeneity of uranium solutions in the certain preparation and conservation conditions. In seven ureniura solutions of 0.01831 gll/l concentration with pK in the range 1.5 - 8.5, kept in dark at a constant temperrture, 18° - 20°C, after 10.16 years we found the initial homogeneity of s uranium; - 18 urenium solutions prepared in bidistilled weter having the uranium concentration range froia 20 ngU/1 up to 2 gU/1 and the pH in the re^ge 1.37 - 5.7^1, after 49 days from their preparation, they did not present the radiocolloidal states; - concerning the secondary recuperation of fissionable element using the evolution of the radiocolloidal or/and pseudoradiocolloidal states sone encouraging experimental results there are in the present, but much more experiments ere necessary.

199 DIFFUSION OF RADON THROUGH NUCLEAR TRACK MICROFILTERS

11 2 G. Hussain , H.A. Khan and M.S. Zafar 1. SSNTD-Laboratory, NED, PINSTECH, P.O. Nilore Islamabad, PAKISTAN 2. Physics Department, Punjab University New Campus, Lahore, PAKISTAN

Abstract: Nuclear track microfilters prepared by irradiating CN-85 cellulose nitrate track detectors with ^*"Cf in 2y geometry were given post-irradiation thermal annealing and ultraviolet treatments followed by etching. These filters were employed to investigate the diffusion of radon. Alpha particles produced due to the decay of radon and its daughters were registered and etched electrochemically in lexan polymeric detectors. Experimental findings have led to determine diffusion coefficient and activation energy for diffusion through various filters/membranes. Diffusion coefficient of radon through the filter treated with UV from the laser is (1.8 + 0.05) 10~4cm2 Sec-"1, being a maximum value as compared to other filters and membranes. Corresponding activation energy for diffusion bears a minimum value of 0.018 + 0.001 eV for this filter. It can be speculated that the post-irradiation laser exposure modifies the profiles of the pores which reduce the resistance to the flow of radon.

200 THE PHYSICAL CHARACTERISTICS OF THE TLD - LiF DOSEMETERS

R. B. AKBARI TEHRAN UNIVERSITY , SCIENCE FACULTY .PHYSICS DEPARTMENT. KARGAR AVENUE . TEHRAN - IRAN .

Abstract : I have investigated the physical characteristics of the TLD ~ LiF Chips .Powder,Discs and Rods with 30% , 100% , 30% and 8% Lithium Fluride by weight, respectively.TLD - LiF chips were used for glow curve , studies , where powder , discs and rods were used for dose levels 0.5 mGy up to 10 mGy. The accuracies were found to be +15% , +10% and +3% for the dose levels of; 0.5 mGy ,5 mGy and 10 mGy respectively. Reusability after annealing , washing and the sterilization did not significantly affect these dosemeters response and very little effect on the ideal energy dependence were observed. Glow curves stability was also investigated by using 90 Sr source exposure and healing at 300 C for reading. The hight of the glow curves were increased linearly by the increment of the time of exposure (radiation exposure). The desireable physical specifications of TEFLON used with excellent characteristics of the TLD - LiF makes it a small,simples reusable and mechanically flexable dosemeter which has a density close to the body tissues. keywords : Build - up , Backscatter , Radiation Response , Energy Dependence, Fading , Tribothermoluminescence , High Exposure.

201 POSTERS

203 Monday, Sept. 7/Tuesday, Sept. 8

POSTER SESSION I

Track Formation

Mazzei,R. SUBMICROSCOPIC NUCLEAR TRACK KINETIC (Buenos Aires) • THEORY AND THE CHARGE CHANGING PROCESS 211

Russell,F. M. USE OF PARTICLE TRACKS TO STUDY (Beijing) • METASTABLE MATERIALS 212

Ruhmann,A. et at- PERMEATION OF TEST GASES THROUGH NUCLEAR (Kiel). TRACKS IN PLASTICS 213

Dwivedi,K. K. et al. REGISTRATION THRESHOLD FOR TRACKS OF 40Ar (Shillong) • IONS IN MUSCOVITE MICA 214

Dwivedi,K. K. et at. MEAN RANGES OF M»Bi IONS IN ZnP- GLASS (Shillong) s DETECTOR 215

Kocsis,Zs. et al. TRACK LENGTHS OF 11. 4 MeV/u 20Ne IONS IN CR — (Veszprem): 39 216

Sharma,S. K. et al. RESPONSE OF SODA GLASS DETECTOR TO (Kurukshetra) • INTERMEDIATE ENERGY HEAVY IONS 217

Zizic,B- et al. THE NUCLEATION AND GROWING OF AgBr (Belgrade) • MICROCRYSTALS AS A FUNCTION FOR MAKING THE SENSITIVITY CENTRES AND THE LATENT IMAGES CENTERS PRODUCED BY IONIZING PARTICLES 218

Detectors

Csige,I. et al. HEAVY ION RESPONSE OF SR-90 AND CR-39 (San Francisco) j TRACK DETECTORS 221

Virk,H.S. etal. HEAVY ION RANGES IN GLASS DETECTORS 222 (Amritsar):

Abu—Jarad,F. COMPARISON BETWEEN SR - 90 AND CR - 39 223 (Dhahran):

205 Al-Jarallah,M. I. et al. PROTON RESPONSE OF CR-39 (PM-355) 224 (Dhahran):

Lucia, M. et al. BULK ETCHING RATE OF IRRADIATED LEXAN (Rio de Janeiro): POLYCARBONATE MEASURING FISSION TRACK DIAMETERS 225

Lucia,M. et al. REACTOR IRRADIATION EFFECTS AND KINETICS (Rio de Janeiro): OF FISSION TRACK FORMATION ON »BIS- PHENOL-A' POLYCARBONATE 226

Kocsis,Zs. et al. SENSITIVITY STUDY OF HUNGARIAN MADE CR- (Veszprem). 39 FOR HEAVY ION TRACKS 227

Jonsson,G. et al. LOW ENERGY HEAVY IONS REGISTERED IN (Lund)• PLASTIC FILMS 228

Virk.H.S. HEAVY ION RANGES IN PLASTIC. TRACK (Amritsar). DETECTORS 229

Pang,D. -L. OPTIMIZATION OF DOPANTS IN CR-39 230 (Shanghai):

Li,L. -D. et al. APPLICATION OF CR-39 (DAP) DETECTORS FOR (Shanghai): ALPHA AUTORADIOGRAPHY OF TISSUES 231

Track Development

Kruger,J. et al. PRESOAKING-INDUCED MODIFICATIONS OF THE (Kiel), ETCHING PROCESS IN CR-39 235 Petersen,F. et al. ELECTROLYTICAL MEASUREMENTS ON LATENT (Kiel). HEAVY ION TRACKS IN PLASTIC 236 ,t Espinosa,G. NUCLEAR TRACKS IN NATURAL AND SYNTHETIC (Mexico) s GEMSTONES 237 ^

Espinosa,G. et al. SHRIMP SHELLS AS NUCLEAR TRACK (Mexico): DETECTORS 238 m Hassib,G. M. et al. OPTIMIZATION OF ELECTROCHEMICAL TRACK ^

(Cairo): ETCHING FOR ALPHA PARTICLE SPECTROMETRY 239 Hassib,G. M. et al. THE SPARKABLE REGION PHENOMENA IN (Cairo) • ELECTROCHEMICAL ETCHING 240 .;

206 Sohrabi,M. et al. A NEW PARAMETER IN THE ECE OF POLYMER (Tehran): TRACK DETECTORS 241

Ghouma,N. B. et al. INFLUENCE OF THE APATITE F/Cl RATIO ON (Besancon); THE URANIUM FISSION TRACKS 242

Djeffal.S. et al. AGEING, FADING AND BACKGROUND STUDY OF (Alger) s VARIOUS NUCLEAR TRACK DETECTORS 243

Domingo,C. et ai. TIME EVOLUTION STUDIES OF POLYCARBONATE (Barcelona); RESPONSE TO FAST ULTRA HEAVY IONS 241

Dajko,G. et al. ELECTROCHEMICAL ETCHING OF CR- 39 TRACK (Debrecen): DETECTORS AT ROOM TEMPERATURE 245 Apel.P. Yu. et al. REGISTRATION TEMPERATURE EFFECT IN (Dubna): POLYPROPYLENE DETECTORS 246 Singh,N. P. A STUDY OF CHARACTERISTICS OF (Sangrur) • MICROSTRUCTURE OF 2"U IN CR-39 247 Liu,Y.-L. et al. STUDIES ON LATENT IMAGE FADING OF (Beijing) • NUCLEAR EMULSIONS 248 Wang,S.-C. et al. THE ETCHING CHARACTERESTICS OF (Beijing). PHOSPHATE GLASS TRACK DETECTORS 249

Track Observation

Meoli,P. et al. SUBMICROSCOPIC OBSERVATION OF FISSION (Buenos Aires) • PRODUCT TRACKS IN MICA 253

Chambaudet,A. et al. CHARACTERISATION OF NUCLEAR TRACK

(Besancon ): DETECTOR RESPONSE BY MICROTOPOGRAPHY OBSERVATIONS AND IMAGE ANALYSIS 254

Birkholz,W. et al. TRACK COUNTING BY AN IMAGE ANALYSING (Leipzig): SYSTEM 255

Sampsonidis,D. et al. IMAGE PROCESSING TECHNIQUES FOR SSNTDS (Thessaloniki). MEASUREMENTS 256

Deng,X. -L. A COMPUTERIZED SPARK COUNTER 257 (Dalian).

207 Granzer,F. et al. TRACKS OF SWIFT HEAVY IONS IN SILVER (Frankfurt): HALIDES,REVEALED BY DIFFERENT METHODS 258

208 TRACK FORMATION

209 SUBMICROSCOPIC NUCLEAR TRACK KINETIC THEORY AND THE CHARGE CHANGING PROCESS R.Mazzei Departamento de Radiobiologia.Comision Hacional de Energia Atomica.Buenos Aires.Argentina Three theoretical descriptions which yield, by a computer program, theoretical submicroBcopical track profile corresponditig to normal incidence ions are proposed. The chemical attack velocities was assumed to vary with the position on the incidence axis (x) of the ion and the perpendicular distance measured on the y axis. It can simulate for cases in which there are changes in the phisical damage owing to statistical changes or state changes in the incident ion charges. Moreover the effects of the fluctuations in the bulk material on the track profiles as well as the experimental track profiles are shown.

211 USE OF FARTICLE TRACKS TO STUDY XETASTABLE MATERIALS

F K Kussell Department of Physics, Peking University, Beijing, China.*

In a metastable material the probability for an exotbernic phase change to occur increases as.either the pressure or temperature decreases. Recently it has been found that such a pbase change can occur in positron tracks in muscovite under conditions of constant pressure and .temperature, to give tracks delineated by epidote. The tract results from a Iocali2ed perturbation of the lattice which releases energy previously stored in the lattice to produce a phase change. This recording mechanism can be understood in terns of a potential energy model in which the phase change is inhibited by a potential energy barrier. The occurrence of epidote in tracks shows that a moving positive charge can locally lower the potential energy barrier sufficiently to initiate a phase change. This aode] is used to examine the possibility that the phase change sight be initiated by other localized perturbations of the lattice. Gne such possibility is energetic lattice solitons which would create large amplitude relative novements of the lattice atone, equivalent to large adiabatic changes in pressure and temperature. This model is used to study previously unexplained lines in mica which exhibit properties characteristic of energetic lattice soliton tracks.

•Postal address: Rutherford Appleton Lab., Didcot, 0X11 OQX, UK.

212 PERMEATION OF TEST GASES THROUGH NUCLEAR TRACKS !N PLASTICS

A. Rlihmann and W. Enge Institut fur Reine und Angewandte Kernphysik Christian-Albrechts-Universitat Kiel D-W23OO Kiel, Germany

Permeation of different gases (N2. Ar and CO2) through the irradiated and unirradiated polymeric nuclear track detector (Makrofol KG) has been measured in ultra high vacuum using a mass spectrometer. The 60 urn thick Makrofol KG foils were irradiated at the GSI (Darm- stadt, Germany) with Au (13.42 MeV/nucIeon, 5*10" ions/cm2). The time behaviour of the permeation through the plastic material was analysed. The experimental data will be compared with theoretical diffusion calculations.

213 REGISTRATION THRESHOLD FOR TRACKS OF 40Ar IONS IN MUSCOVITE MICA

K.K. Dwivedi, Swarnali Ghosh and Jolly Raju Department of Chemistry, North-Eastern Hill University, ShiIIong-793 003, India.

It has been observed by Fleischer et al. that ^Ar forms etchable tracks in mica when its energy lies between 0.5 to 3.0 MeV/u. In their experiment, they have used a number of degraded ion energies by aluminium foils. Here, we present our results on the determination of (dE/dx)c for muscovite mica using a single energy of ^Ar and a special inter-layer (INLAY) etching technique.

Muscovite mica detectors were exposed to 15.5 MeV/u ^Ar ions at UNTLAC, GSI, Darmstadt. A well collimated and low flux beam was used to irradiate the samples at 30°. Mica detectors were etched in 20% HF acid at 30°C. Microscopic observations failed to detect any track on the mica surface. In order to develop the etchable part of the damage trails, we have created micro-cavities or gaps between the layers by mechanical bending and then etched the mica samples in such a way so that the etchant can enter through interlayer spacings. After such INLAY etching, a large number of parallel tracks were observed about 80 /im below the surface and near the edges. The lengths and depths of a large number of tracks were measured to determine the most probable values of the maximum etchable track length and the location of the etched tracks along the ion trajectories. The mean value of critical energy-loss rate (dE/dx)c for ^Ar in mica has been found to be 15.5 ±0.5 MeV.mg^.cm2 from the plot of energy- *; oss rate versus depth of penetration.

The present work describes a simple method by which it is possible to measure the track registration threshold for charged particles in mica. One of the advantage of this technique lies in the fact that it enables us to determine the lower and higher energy registration threshold in a tingle exposure.

214 MEAN RANGES OF 2<»Bi IONS IN ZnP-GLASS DETECTOR

K.K. Dwivedi1), Zs.Kocsis2>, P.Vater3) and R. Brandt3>

"Department of Chemistry, North-Eastern Hill, University, Shillong-793 003, India. 2JDepartment of Physics, University of Veszprem, H-8201 Veszprem, Hungary. 3>Kernchemie, FB 14, Philipps-Universitat, 3550 Marburg, Germany

Measurements of heavy ion ranges in elemental and complex materials is of great importance due to several practical applications. In last few years, the nuclear track detectors have been considered to be very useful devices to accomplish such measurements. For heavy ions, the response of ZnP-glass is quite good and nearly entire damage trails can be chemically etched. Hence, the value of maximum etchable track lenghts of heavy ions in ZnP-glass are equal to ion ranges within the measuring accuracy.

Four aluminium degrader foils (15, 30, 45 and 60 /im) were mounted on a ZnP-glass plate in a stair-case configuration and leaving some area uncovered. This target-detector assembly was then irradiated with 13.0 MeV/u ^Bi at UNILAC, GSI Darmstadt. The etching was done in 6N NaOH at 50°C for 15-40 minutes (in steps) to develop the tracks till the end. Nearly 100 tracks for each ion energy were measured to derive most probable true track lenghts. The statistical errors in measurement vary from 1.5 to 2.8

Here, we present our measured data on mean ranges of 209Bi ions at five energies in ZnP-glass detector. The experimental data are also compared with the corresponding theoretical ranges from three commonly used computer codes. This experiment not only provides us with mean range data for ^Bi in ZnP-glass detector to verify the applicability of theoretical values but also to help in constructing a valuable range-energy calibration curve.

215 TRACK LENGTHS OF 11.4MeV/u so^e IONS IN CR-39

Zs. Kocsis1), K.K. Dwivedi2>, P. and R. Brandt3>

^Department of Physics, University of Veszprem, H-8201 Veszprem, Hungary. ^Department of Chemistry, North-Eastern Hill, University, ShiHong-793 003, India. 3>Kernchemie, FB14, Philipps-Universitat, 3550 Marburg, Germany

The maximum etchable track lengths of energetic heavy ions in CR-39 has a sharpe dependence on the charge, mass and energy of the ions. The track length data for lighter ions are rather few in literature as compared to those for heavy ions. The aim of our investigations is, therefore, to measure the maximum etchable track lengths of ^Ne ions in CR-39.

Samples having a size of 2 cm x 2 cm x 680 vm were irradiated at the X0 channel of UNILAC, GSI, Darmstadt at an angle of 45°. Aluminium foils of different thicknesses were used to decrease the ion energy. Hie ion energies were determined in both experimental and theoretical manner.

The samples were etched successively in 5M NaOH solution at suitable temperature to develop relatively long tracks up to their end. The etched track lengths as a function of etching time are measured for samples irradiated at different ion energies.

The experimental values of maximum etchable track lengths are given for five ion energies with experimental errors. The theoretical track I lengths of ^Ne ions as a function of ion energy was calculated using three different computer programs. A comparison of the measured and calculated track length data is presented and discussed.

216 RESPONSE OF SODA GLASS DETECTOR TO INTERMEDIATE ENERGY HEAVY IONS

S.K. Sharma,Shyam Kumar, J.S. Yadav and A.P. Sharma. Department of Physics, Kurukshetra Un i v e r s i 1 y, Kurukshetra - 132 119 (India). * Tata Institute of Fundamental Research Bombay - 400 005 (India). ** Department of Physics, Aligarh Muslim University, Aligarh - 202 001 (India).

In the present work, a stack of soda glass slides has been exposed to 144 ± 6 MeV/n . __U and 199 ± 4 MeV/n «A^e ions from heavy ion accelerator EtEVELAC at Berkeley. After processing the stack, the various track parameters have been measured as a function of the path traversed by the incident ion. The experimental values of range have been compared with the corresponding theoretically computed values of range using the various formulations. The experimental values of range have been found to be in good agreement with the corresponding values obtained from Benton & Henke and Hubert etal approches.

217 THE NUCLEATION AMD GROWING OF AgBr MICRDCRYSTALS AS A FUNCTIOtV FOR MAKING THE SENSITIVITY CENTERS AND THE LATENT IMAGES CENTERS PRODUCED BY IONIZING PARTICLES

B. 2i2ic, J.B. Vukovic* and M. Mijic Faculty of Physics, Belgrade, Studentski trg 12/JV Faculty of Medicine, Inst. of Biophysics*. Belgrade, Vi§egradska 26/2 University of Belgrade, YUGOSLAVIA

The nature, the mechanism of making sensitivity centers (specks) am. distribution of the latent image centers are basic problems of the ionizinc processes theory in solid state detector with AgHal crystals.

It is know that the latent image centers are forming on structural defect: of the crystal latice of the AgHai. They rise preferential during presipitat- ion (nucleation), ripening (increase of the size of the AgBr grains) an digestion (increase of the sensitivity). During of all these separate stage there are possibility to influence by careful selection of different physic chemical conditions.

We have studied by electron microscopy (TEM) the size distribution of AgBi microcristals and their sensitivity (distribution and spread of the latent image origine from different ionizing particles) according conditions of of precipitation (time and temerature. in magnetic field and others) ant also during post growing of the microcristals (after sensitization).

For more information sensitivity (axactly determination of the particl range and angles in stars of the tracks) we have sintetized nuclear emulsio; with ultafine microcrystals AgBr (grains diametar under 0,1 urn) and the are cappable to register ionizing particles of all energies. This goal wen achived by different physical conditions during making sensitivity am latent image centers and their new distribution on the surface of the AgB: microcrystalas.

218 DETECTORS

219 HEAVY ION RESPONSE OF SR-90 AND CR-39 TRACK DETECTORS1

I. Csige. E. R. Benton and E. V. Benton Physics Department, University of San Francisco, 2130 Fulton St., San Francisco, CA 94117-1080, U.S.A. M. Fujii The Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Saganxihara Kanagawa 229, Japan

Abstract-The heavy ion response of the new kind of SR-90 plastic nuclear track detector was studied in comparison with different kinds of commercially available CR-39s at the Bevalac accelerator. The reduced etch rate ratio (S-lj of SR-90 (a similar material to CR-39, but longer chain length between adjacent carbonate groups) was found to be about 1.2-1.5 times higher than the sensitivity of the CR- 39s for particles (Ne, Ar and Fe) and energies (100-600 MeV/nuc) investigated in our study. After the relatively long etching time (13 hours in 6.25N NaOH at 70 °C - the optimal etching time is 3 hours), however, the surface of SR-90 became foggy ! an^ i* was not possible to compare its sensitivity for very low LET particles because we could not distinguish the tracks against detector defects. The possible applications of this material are also discussed.

'Work partial]}- supported by NASA grant No. NAG9-235 (NASA-Johnson Space Center, Houston)

221 HEAVY ION RANGES IN GLASS DETECTORS

H.S. Virk, R. Kaur and G. Singh Physics Department, Guru Nanak Dev University, Amritsar-143005 (INDIA).

Glass detectors, viz. sodalime, phosphate and quartz, were irradiated at heavy ion cyclotron facility at JINR, 238 131 Dubna, USSR using U(5.9 and 15.0 MeV/u), Xe(5.9, 197 11.56 and 14.5 MeV/u), Au(11.4, 11.67 and 15.96 56 48 MeV/u), Fe(4.0 MeV/u) and Ti(4.0 MeV/u) beams. Heavy ion ranges are measured in glass detectors using appropriate etching conditions and compared with theoretical ranges. Bulk and track etch rates are determined from which sensitivity and efficiency parameters are calculated. Phosphate glass has maximum sensitivity and is most efficient for heavy ion track recording. It has potential applications in cosmic ray and space research programmes because of high charge and isotopic resolution.

222 COMPARISON BETWEEN SR-90 AND CR-39

F. ABU-JARAD Energy Research Laboratory / Research Institute King Fahd University of Petroleum and Minerals Ohahran 31261, Saudi Arabia

ABSTRACT

A new nuclear track detector, called SR-90, (Polymerized on Nov. 24, 1991 and received from Fujii/Japan on Feb. 1992) has been compared with two CR-39 nuclear track detector (i) (super grade PM-355 Pershore Kouldings/U.K. and MA-ND/a/ Hungary). All were irradiated with alpha and fission fragments and will be irradiated with protons and neutrons soon. They were etched under the same etching conditions. The bulk etching rate of SR-90 was double that of the CR-39 for all etching times. The track etching rate start with 8.5 yum/h at 2 h etching time and increased to 13 /m/h at 6.5 h, while the CR-39 remain nearly constant (2 /im/h) through etching time. Thus, the sensitivity of SR-90 was found to be improved with etching time. The surface of SR-90 is found to be rougher than the CR-39 detectors and the shape of perpendicular alpha and fission fragments tracks was not a uniformly rounded edge as in the CR-39. More detailed results will be presented at the time of the conference.

223 PROTON RESPONSE OF CR-39 (PK-355)

M.I. AL-JARALLAH**, F. ABU-JARAD*, A.B- HALLAK*, A. COBAN* AND M.A. ISLAM* * Energy Research Laboratory / Research Institute ** Department of Physics King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia

ABSTRACT

CR-39 type super grade PM-355 samples have been irradiated at normal incidence with monoenergetic protons at selected energies in the range range 0.2 MeV to 5 MeV. The sensitivity function and its variation with energy have been experimentally determined. A clear shift was observed in the - maximum sensitivity towards higher proton energy with increase etching time. The critical angle for proton registration decreases rapidly between 0.2 MeV and 0.5 to 0.8 MeV depending on the etching time. For higher energies the critical angle increases gradually. The CR-39 detection efficiency to protons was found to be 100% within the experimental accuracy for all energies in comparison with that of Surface Barrier detector.

224 Bulk Etching Rate of Irradiated Lexan Polycarbonate Measuring Fission Track Diameters Maria Lucia C.P.Carvalho (1) and JoSo A.Medeiros (2,3) (l)Analytical Chemistry Dept., Federal University - UFRJ (2)Instltute of Nuclear Engineering. Atomic Energy Commission, (3)Chemlstry Dept., Catholic University - PUC/RJ Rio de Janeiro, Brasil Polycarbonates of bis-phenol"A" , like Lexan (GE) and Makrofol or Makrolon (Bayer) are being used to determine uranium and thorium in rocks, water and biological samples. It is important to have a fine control of etching kinetics. Lexan plates ( 1,6 mm ) were irradiated separately with gamma radiation of a strong *"Co source up to 1 MGray (100 MRad) and in a swimming pool research reactor (IEA-R1) close to the core, at neutron fluxes of about 10xa thermal n-cnr^s"* and about 1 - 1.5. 10" fast n-cm-2-s-S at integrated neutron fluxes from 10in to 10a-7 n/cm* and exposed afterwards to 2S2cf fission fragments, collimated at 90 degrees. Detectors with latent tracks were etched in 6M NaOH at 60°c during varying time periods, to get large circular holes (3.5 to 18 hours). Track diameters were measured with a micrometric ocular at a Leltz orthoplan Microscope, at 500 x magnification. More than 100 tracks were measured for each detector . The precision of the measurements was determined to be about 3% . cone angles were measured with the aid of a drawing chamber at the microscope, for each gamma dose or integrated flux, using slightly etched tracks of aosCf fission fragments collmated at 25 degrees.

Corrected equation for bulk etching rate vb= D/(2t(l-sene) ) and average diameters were used to calculate vb = 0.65 Um/h. Gamna irradiated detectors showed a decrease of Vt, above 10 MRad (0.68 um/h) and did not show slstematlc changes between 30 and 100 MRad (0,60 * 0.02 um/h). Reactor irradiated detectors were strongly damaged, and V_, increased substantially. An 8th degree polynomial expression Vt. as function of log of Irradiation time 3 7 fits very well vto variation from integrated flux 0 to 10 -" n/cxa". Irradiation of detectors increase sensitivity against fission fragment energy. Bar charts show separation of two areas,this being more evident for detectors submitted to higher gamma doses. Similar effect is observed for neutron irradiated detectors, but recoil tracks decrease the precision of the measurements.

225 Reactor Irradiation Effects and Kinetics of Fission Track Formation on HBis-Phenol-A" Polycarbonate Maria Lucia c.P.carvalho (1) and Joao A.Medeiros (2,3) na

desired layer, to let Vb.t or track sizes constant. Direct measurements led to variations in efficiency less than 2-

efficiency (e> determination and ve/vb ratio. Latent tracks are annealed in such a way that the number of etchable tracks decreases exponentially during gamma or fast neutron irradiation. Detectors were irradiated with reactor neutrons in contact with Al-foils containing uranium. Track density follow a curve and not a straight line of equation N*= N«--t-e. Annealing effect on latent tracks follows an exponential law. Kinetics of formation of etchable tracks can be expressed by a differential equation analog to activation equation, leading to the integrated equation (e constant): N* = n»-o"-«-E/l - (l-e-"). 1 is the "decay" constant due to annealing of latent tracks. iP> a After 10 n/cm (nth-K»«1/n«..t= 8-10) there is almost no gain in sensitivity and detectors become very dark and brittle.

226 SENSITIVITY STUDY DF HUNGARIAN MADE CR-39 FOR HEAVY ION TRACKS Zs. Kocsisx, P. Vater, R. Brandt Kernchemie FB 14, Philipps-Universitat, D-355O Marburg, Germany x Department of Physics, University of Veszprem, H-8201 Veszprem, Hungary

The tracks of heavy ions 197Au with an energy of 5,9 MeV/u and 909 Bi with an energy of 13 MeV/u were studied in Hungarian made CR-39. The detectors were irradiated at the XO channel of UNILAC, GSI Darmstadt, at an incident angle of 90° and 45°. Aluminium foils of different thicknesses were used to decrease the ion energy. The irradiated samples were etched in 5M NaOH solution at different temperatures to develop the tracks. Deter- mination of the bulk etch rate was performed by weighing the mass loss of the detector and the track etch rate by measuring the track length. The diameter distribution of the track diameters as a function of ion energy as well as total energy loss rate was also measured. The Hungarian made CR-39 have been characterised by the sensitivity of the detectors (v-j/v,,) and by correlating the track etch rate (v,) with total energy loss rate (dE/dx). These data were compared to data obtained with foreign made CR-39 detektors.

227 LOW ENERGY HEAVY IONS REGISTERED IN PLASTIC FILMS;

G. Jonsson and R. Hellborg Department of Physics' University of Lund Box 118, S-221 00 LUND, Sweden

Plastic films of the types Kodak LR115-II and Pershore CR39 were used as the detectors of accelerated 0, Cl and Ag ions. The energy of the ions were below 15 MeV. The ions were obtained from the 3UDH Pelletron tandem accelerator in Lund. Some results of the response of the detectors are discussed.

228 HEAVY ION RANGES IN PLASTIC TRACK DETECTORS

H.S. VIRK Physics Department! Guru Nanak Dev University, Amritsar-143005 (INDIA).

Plastic track detectors,viz. CR-39 and Lexan polycarbonate 208 were irradiated at UNILAC, GSI, Darmstadt using Pb(13.6 238 132 MeV/u), U(15 MeV/u), Xe{5.6 and 14.5 MeV/u) and 139 La(14.6 MeV/u) beams. Heavy ion ranges are measured and corrected for bulk and over-etching. The experimental ranges are in good agreement with the theoretical ranges computed by using the computer programme based on equations of Mukherji and Nayak. Critical angle, etching efficiency and REL values for plastic detectors are determined from their bulk and track

etch rates. Track etch rate, VT , is a function of ion energy, however, track etch efficiency is independent of the concentration and temperature of the etchant. -1 -2 for lexan polycarbonate is found to be 4.25 MeV mg cm . The efficacy of 'Single Sheet Identification1 technique for identification of low energy cosmic ray particles is established.

229 OPTIMIZATION OF DOPANTS IN CR-39

Pang Deling Li Landi Zhu bing Institute of Radiation Medicine,Shanghai Medical University

Shanghai 200032, P R China

CR-39 plastic nuclear track detectors have been cast with noadditive and with methyl metha- crylate, diallyl phthalate, dibulyl phthalate and di-(2-ethylhexyl) phthalate. After irradiated with 5.15MeV alpha particles, the responses of the detectors were found to be significantly different for each kind of additive. The performance was reported of a new CR-39(DAP) solid state nuclear track detector, the CSR. The sheets with 1% addition of Diallyl phthalate of CR-39 monomer were more sensitive than those of pure CR-39.

230 APPLICATION OF CR-39(DAP) DETECTORS FOR ALPHA AUTORADIOGRAPHY OF TISSUES

Li Landi Pang Deling Zhu bing Institute of Radiation Medicine, Shanghai Medical University

Shanghai, 200032, P R China

High resolution autoradiography of mouse tissues containing 238U were prepared by CR-39(DAP) detectors which are specially sensitive to alpha particales. The radiation damaged sites in the polymer were developed by etching with NaOH. The methed does not require darkroom facilities. The detector are very stable and will not fog during long exposuresat room temperature.

231 TRACK DEVELOPMENT

233 PRESOAKING-INDUCED MODIFICATIONS OF THE ETCHING PROCESS IN CR-39

Kriiger.J. and Enge,W. Institut fiir Reine und Angewandte Kernphysik Otto-Hahn-Platz 1 W-2300 Kiel 1 Germany

By using conductivity measurement equipment for controlling pore-radius in heavy-ion-irradiated CR-39-foils while etching, we investigated the influence of presoaking on breakthrough-time. The CR-39-foils of 100 pm thickness were irradiated with Ar- respectively Au-ions of 11.4 MeV/u with an ion density of 104-106/cm2 at UKILAC of GSI Darmstadt. In the presoaking process different liquid chemicals of room temperature were used. The etching agent was NaOH at a temperature of 45-l°C. We tried to find out, which substances solve the track core with preference and generate an ideal cylindrical pore shape. First results will be presented.

vlj I

235 Electrolytical Measurements on Latent Heavy Ion Tracks in Plastic

F. Petersen and W. Enge Institut fiir Reine und Angewandte Kernphysik, Christian-Albrechts-Universitat Kiel W-2300 Kiel, FRG

In a special etching chamber, consisting of two gold-plated electrodes, running with 3V DC, electrolytical measurements on latent heavy ion tracks in different plastic materials were made. The electrolytical resistances of single ion tracks during the etching process under different conditions, i.e. etching temperature and solution, have been measured. From the pore growth the radius development and transversal track etching rate were calculated . These experimental data will be compared with theoretical models ( e.g. model of low-energy excitations [ M. Danziger, G. Andrassy; 1991 ] ) about the radial distribution of damage around the ion path through the plastic and the reaction and pore formation of the solid caused by the etching process.

Reference: M. Danziger, G. Andrassy, " Experimental and theoretical study of heavy ion irradiation processes in polymer materials *', Phys. stat. sol. ( b ) 161, 223 , 1990

236 NUCLEAR TRACKS IN NATURAL AND SYNTHETIC GEMSTONES Espinosa, G., Rodriguez-L., V. Golzarri, J.I. and Castano, V.M.

INSTITUTE DE FI5ICA, UHAM. APDO. POSTAL 20-364 01000 MEXICO, D.F. MEXICO

ABSTRACT The response of natural and synthetic gemstones to fission fragments and alpha particles are analyzed with the objective of finding new materials for SSNTD, and trying to understand their interaction with radiation and the formation of tracks.

In this work we present the results of the characterization of those materials as SSNTD, the micro structural changes observed by optical and electron microscopy. The preparation, etching solution concentration, etching time and effects of temperature are discussed.

keywords: Nuclear Tracks; Gemstones; New materials.

237 i SHRIMP SHELLS AS ; NUCLEAR TRACK DETECTORS j { Espinosa, G., Martinez, A. and Golzarri, J.I.

INSTITUTO DE FISICA, UN AH. APDO. POSTAL 20-364 01000 MEXICO, D.F. MEXICO

ABSTRACT

In the search for new and better materials such as Solid State Nuclear Track Detectors, some options are: 1) Synthesis of polymers with selective response to the type of particle, the energy of the ionizing radiation, high sensitivity, very low background, good mechanical strength, simple to etch, huge tracks, etc.; and 2) Investigation of naturally available materials determining their characteristics in order to use them in the appropriate applications. Shrimp shell, which is with a high content of chitin, a natural polymer, belong to the last option.

In this work, we report the response of shrimp shells as a SSNTD. Each type of shrimp shell is characterized according to its species and origin. For each type we indicate the method of preparation, pre-treatment, etching conditions and measurements. Those measurements are compared with the corresponding measurements using a conventional detector material. keywords: New materials; Nuclear Tracks.

238 OPTIMIZATION Of ELECTROCHEMICAL TRACK ETCHING FCR ALPHA PARTICLE SPECTRCMETRY.•

G.M.Hassib and H.A.Amer

The National Centre for Nuclear Safety and Radiation Control, Atomic Energy Authority, P.O.Box 7551, Nasr City, Cairo. Egypt.

Abstract.

In this work, the technique of chemical and electrochemical etching is applied for the energy discrimination of alpha particles. For each alpha energy, a given layer of the irradiated detector surface has to be removed chemicaMy before revealing the alpha tracks electrochemically. The optimum layer removal was determined for different alpha energies in the range between 0.7 - 5.0 Mev. The energy resolution of this technique was also studied and it was found that the resolution is getting better at the higher energy bands. Also, the registration efficiency was found to be dependent on the incident alpha energy and the maximum efficiency was found in the energy range between 2-2.5 Mev. The last observation can be taken into consideration when designing a passive radon dosimeter.

* This work is partially supported from KFA - IB, Julich. Germany and supervised by E.Piesch, KFK, Karlsruhe, Germany.

239 THE SPARKABLE REGION PHENOMENA IN ELECTROCHEMICAL ETCHING G.M.Hassib and H.A.Amer The National Center for Nuclear Safety and Radiation Control, Atomic Energy Authority, P.O.Box 7551, Nasr City, Cairo. Egypt.

Abstract.

It was observed by Hassib, et al that, for electrochemical etching of a given alpha energy, a layer has to be removed from the detector surface to reach a defined region . At this region, the track geometry is quite suitable to be sparked when appling the electric field. No tracks can be revealed electrochemically before reaching or after exceeding this region.In this work, a study is given about the sparkable region phenomena in view of the energy loss mechanism of alpha particles in polycarbonate. Some empirical formulae are given to correlate the depth and the width of the sparkable region with the energy of normal incident alpha particles.

* This work is partially supported from KFA-IB, Julich, Germany and supervised by E.Piesch. KFK-KarIsruhe, Germany.

240 A NEW PARAMETER IN THE ECE OF POLYMER TRACK DETECTORS

M. Sohrabi and M. Katouzi National Radiation Protection Department Atomic Energy Organization of Iran P. 0. Box 14155-4494, Tehran Islamic Republic of Iran

ABSTRACT

The effective registration of charged particle tracks in polymeric detectors by electrochemical etching (ECE) depends on many ECE parameters such as applied field conditions, physical and chemical characteristics of the detector, ECE chamber size and etchant parameters- Since the track density and diameter are usually two main measurable parameters considered in fundamental studies as well as in dosimetry applications, their control is necessary for precise measurements. Recently, a new parameter has been discovered in our laboratory which is the effect of pressure on the rubber rings or washers holding the detector tight and leak proof between the two semichambers. The pressure itself depends on the type of rubber holder and the degree of the tighteness of the two semichambers. The study of this parameter is therefore of great importance in better understanding of the ECE fundamentals and to standardize the chamber design for unification of the results.

In the prelimary studies, four types of foil holders were applied; (a) glueing the PC foil directly to the end of two cut syringes with no rings used, (b) round rubber "0" rings, (c) flat rubber "0" rings and (d) flat rubber sheets, applying different pressures. The temperature due to internal heating, track diameter and track density were determined at different field strengths and frequencies (e.g. 2 kHz, 20 kHz and 50 kHz). The studies show the strong dependence of the measured parameters on the type and degree of tightness of the foils. In this paper, the preliminary results on the above are presented and discussed.

241 INFLUENCE OF THE APATITE F/Cl RATIO ON THE URANIUM FISSION TRACKS.

N.Ben Ghouma, M.Rebetez, M.Grivet, A.Cbambaudet Laboratoirc de Microanalyses Nucleaires, Faculte des sciences 25030 Besancon cedex, FRANCE

The F/Cl ratio was measured by neutron activation and electron microprobe for ten natural single cristal apatites, it was found to vary between 4,5 and 115 in those samples. After total annealing of fossil tracks the samples were irradiated at the Strasbourg university reactor to induce U235 fresh fission tracks. A study was then done in order to show the influence of the apatite stucture on Uranium fission tracks formation and fading. Laboratory experiments were set up and the shortening of the tracks was monitored by confined track length measurements (within the body of the cristal) at each step of the experiment. The track length were firstable measured on the fresh induced tracks prior to any annealing, the influence of the structure of the apatite on the track formation was quantified. Furthermore an empirical fading equation was established for each apatite composition to define the influence of the fluorine-chlorine ratio on fission track annealing .

242 AGEING, FADING AND BACKGROUND STUDY OF VARIOUS NUCLEAR TRACK DETECTORS

S. Djeffal1 , Z. Lounis1 and M. Allab2 1- Laboratoire de Dosimetrie, Centre de Radioprotection et de Surete. 2, Bd. Frantz Fanon, B.P. 1017, AJger, Algeria 2- Institut de Physique, Universite des Sciences et de Ja Technologic EI-AIja B.P. 32, Bab Ezzouar, Alger, Algeria

Abstract An intercomparIson study of five different PADC materials was performed investigationg the background, ageing and fading in normal air at ambient temperature. Moreover, some properties of the Cellulose Nitrate known as LR-115 were investigated in this study. Results of the performance in terms of ageing, fading and background of the tested PADC materials have been compared with those obtained with the LR -115 detectors.

The storage experiment in ambient laboratory conditions over a period of 20 months resulted in a decrease on the response of pre-irradiated PADC detectors and an increase in the background. Fading ranging from about 10 to 25% has been found in all the tested PADC material s. Data of the increase of intrinsic background signal with time obtained over a 20 months storage period are also presented. For the LR-115 material, used during the first 12 months after manufacturing, the results obtained indicate that the changes in ageing and fading do not vary so much.

243 TIME EVOLUTION STUDIES OF POLYCARBONATE RESPONSE TO FAST ULTRA HEAVY IONS C. Domingo, C. Baixeras and F. Fernandez. Ffsica. de les Radiations. Department de F/s/ca. l/n/versjrat Autonoma de Barcelona, E-08193 Bellaterra (Barcelona). Spain.

It is known that the signal produced by ultra heavy ions in plastic nuclear track detectors depends not only on the recorded ion characteristics but also on some environmental parameters. Detector storage temperature and time elapsed between irradiation and etching are among the main variables to be taken into account when studying latent track evolution. Latent tracks produced at different moments by identical incident ions may give rise, at the moment of etching, to different response values and therefore the associated charge uncertainty increases. A stack composed of 400 (~ 250 ftm thick) polycarbonate plates was exposed to ~ 1 GeV/N U ions at the Berkeley Bevalac in March 1987. The stack was stored at 2°C and re-exposed in November 1989 to U and Au ions at - 1 GeV/N. Analysis of data from this stack allows to compare the signal strength from tracks whose latent track damage has been produced at different times, eliminating any variability which could be caused by the etching process, as older and younger tracks have been etched together.

244 ELECTROCHEMICAL ETCHING OF CR-39 TRACK DETECTORS AT ROOM TEMPERATURE

Gabor DAJKO, Karel TUREK+

Institute of Nuclear Research of the Hung. Acad. of Sciences H-4001 Debrecen Pf. 51. Hungary +Institute of Radiation Dosimetry, Czechoslovak Academy of Sciences, Na Truhlarce 39/64, CS-180 86 Prague 8, Czechoslovakia1*

The parameters of the elchtrochemical etching at room temperature were investigated in different solutions. The aim of this work is to find the optimal etching solution and etching parameters for the quick electrochemical evaluation of the detectors at room temperature.

245 REGISTRATION TEMPERATURE EFFECT IN POLYPROPYLENE DETECTORS

P.Yu.Apel". A.Yu.Didyk*. L.I.Kravets*, V.I.Kuznetsov*

and B.I.Fursov

• Joint Institute for Nuclear Research, 141980, Dubna, Russia

•• Institute of Physics and Power Engineering, 249020, Obninsk,

Russia.

The registration temperature effect (RTE) has been

investigated using two types of polypropylene detectors.

Polypropylene films with different amounts of the antioxidant were irradiated with fission fragments in vacuum at different temperatures ranging from 77 to 293 K. The detectors were etched and the breakthrough time was estimated by a conductometric method.

It was found that in both types of the films the track etching rate has the maximum at ca. 140 K. A markedly lower RTE was observed in the case of the sample with a lower content of the antioxidant which played the role of a radical scavenger. The phenomena observed are explained in terms of competing reactions between macroradicals. A correlation between the temperature dependence of the track etching rate and the relaxation transitions in the polymer is discussed.

246 A STUDY OF CHARACTERISTICS OF MICROSTRUCTURES OF U-238 IN CR-39

K.P.SINGH LONGOVIAL INSTITUTE OF ENGINEERING & TECHNOLOGY (L.I.E.T) LOlNXWIIALtDISTTrSAI-lGRUR.'PUIvJABdrlDIA) Studies of the structures of charged particle produced etched channels are important for further development of the applications of technique of ion tracks in microstructure technology. In the present investigations, the characteristics such as aspect ratio and lateral resolution of raicrostructures produced by ions of U-238 in CP.-39 are

studied. The track etch parameters VT and V£ are also measured to correlate them with above parameters using different concentrations of ITaOI and methanol. Results reveal that aspect ratio and lateral resolution can be enhanced with the addition of methanol in the developing solution(KaOH). A better microstructure in less time can thus be created by introducing alcohal in ths developer(JfeOK). A direct correlation is observed between above characteristics and the track etch parameters, V_ and \C.

247 STUDIES ON LATENT IMAGE FADING OF NUCLEAR EMULSIONS

Liu Yonglian, Han Jinqin and Liu Huichang China Institute of Atonic Energy

The paper describes the variation of some characteristics of the nuclear emulsion such as sensitivity, fog density and latent image stability etc. influenced by adding ascorbic acid into the finished emulsion N-4. A comparative study of latent image stability has been made between'Fuj iET-7B nuclear ennalsion and our's under different temperature and relative humidity. As the result shown withinhere, it indicates that the addition of ascorbic acid obviously improves latent image stability of the emulsion N-4. The Fuji ET-7B emulsion and the emulsion N-4 containing ascorbic acid have similar latent image fading quality at lower temperature while the Japanese sample does better at room temperature.

248 THE ETCHING CHARACTERESTICS OF PHOSPHATE GLASS TRACK DETECTORS

1 2 Shicheng Wang and P.B.Price 1.Institute of High Energy Physics,Beijing,China 2.Physics Department,University of California, Berkeley, USA

ABSTRACT

The etching characterestics of phosphate glass VG-13 and PSK-5O have been studied in various etching conditions using relativistic heavy ions U, Au and La. The addition of KF to HBF4 solution obviously increases the sesitivity of VG-13. The effects of concentration of KF on S and Vg were studied. For La ions (z/B = 63), S was measured to be about 1.15.

249 TRACK OBSERVATION

251 SUBMICR0SC0P2C OBSERVATION OF FISSION PRODUCT TRACKS IN HICA

P. Meoli, R. Maz2ei and O.A. Bernaela National Atomic Energy Comission. Av.Libertador 8250. Bs.As.(1429) Argentina

The track replica method has been shown to be a useful tool to analyze nuclear tracks at submicroscopic level. To date, this methodology was applied only to organic SSNTD. In the present work its applications are extended to inorganic materials. Mica was irradiated with fission products of a Cf source and chemically etched with a solution of 40% fluorhidric acid at room temperature. C-Pt replica of the tracks are obtained and the evaluation of track profiles is performed by TEM up to 10 A resolution. The tracks show a central damaged region of amorphous characteristics and an external bulk zone where the crystaline behaviour of the mica was maintained.

253 CHARACTERISATION OF NUCLEAR TRACK DETECTOR RESPONSE BY MICROTOPOGRAPHY OBSERVATIONS AND IMAGE ANALYSIS

A.CHAMBAUDET1, D.KLEIN2, V.MATHAE2, F.BERGER1 and CDUBOIS*

1- Laboratoire dc Microanalyses Nuclcaires, UFR dcs Sciences et Techniques, LJ Bouloic, Univcrshe de Franche Comte", 25030 Besanc.on Cedex, France

2- Laboratoire de Metrologie des Interfaces Techniques, 1UT de Bel fort Montbeliard, Univcrsit6.de Franche Comte, BP 527, 90016 Belfort. France

In order to increase the knowledge of nuclear radiation damage in mineral or plastic detectors, surface observations are carried bu through two complementary techniques: - microtopography observations - image analysis.

The chemical etching tracks of charged particles are studied ii area of different detectors. The microtopography observations are obtained through a three dimensional profilometer, the sensor bein§ the tip of a diamond pyramid, which enables numerical analysis o depth distribution. Image analysis, using a video camera connected U an optical microscope and a specific hardware system (CUE2, SCOP Olympus), leads to track densities and numerous analysis through the study of track shapes.

Special computer programs (in C langage), gather the both resul files and enable to correlate the both analyses with the registratioi haracteristics of nuclear damage in the nuclear track detectors.

254 TRACK COUNTING BY AN IMAGE ANALYSING SYSTEM

W. Birkholz, H. Baumbach, G- Matz

Technische Hochschule Leipzig, Germany

A new system for image analyzing (BVS) consisting of a light microscope, a televsion camara and a micro-computer was built. This system is used for track counting in solid state nuclear track detectors for measurements of radon concentrations in air.

The results of automatical track counting show a good agreement with manual countings. The system allows to increase the area counted per detector because of its short evaluation time and therefore to decrease the statistical error.

255 IMAGE PROCESSING TECHNIQUES FOR SSNTDS MEASUREMENTS

Sampsonidis D. and Zamani M. Nuclear Physics Dept., University of Thessaloniki Thessaloniki 540 06 GREECE.

In recent time a fully automated system has bsen developed in order to facilitate nuclear track technique in many fields of applications. The automated system is based on a PC-AT with a frame grabber (512x512 resolution and 256 grey level per pixel) and the Software has been entirely developed. The algorithms used by the automated system for Image scanning and track recognition are presented. The automatic measurement procedure consists of four consecutive steps: 1) Micro- scope stage movement. 2) Autofocus. 3) Image Analysis and track recognition. 4) Storage of measurements in peripheral memory. There are many problems associated with the reliability of the measurements in a fuDy automated system. When the field is not uniformly illuminated the obtained measurements for each track , such as track area, track axis etc, depend on the position of the track into the field. Many methods have been proposed in the literature in order to account this problem, which, unfortunatelly are time and memory consuming. In the system developed in Nuclear Physics Lab. of the University of Thessaloniki, we have applied a method which uses an adaptive threshold technique during image scanning, which proves to be faster and more effective. Due to this adaptive threshold technique we are able to overcome problems such as maladjustment of the microscope optics or ununiformity in the sensitivity of the camera. Furthermore, we are able to differentiate "tracks" due to surface structures by altering one parameter in the algorithm. Therefore, these "tracks" can be rejected directly during the counting procedure. Secondary data processing for the rejection of these tracks can therefore be avoided. Results obtained from heavy ion beams are presented, in order to access the effectiveness of the method in comparison with standard threshold techniques.

256 A COMPUTERIZED SPARK COUNTER DENG XINLU. ZHANG GOUB1NG. ZHANG LIANSHENG DEPARTMENT OF PHYSICS, DALIAN UNIVERSITY OF TECHNOLOGY 116023 DALIAN, CHINA

This paDer described a computerized spark counter used for the determination of uranium in water. The chief problem in discharqe countinq of the fission track of water sample is that an evaporatinq water drop does not deposit its solutes uniformly o\/er the area it covers. The fission tracks from the uranium in the solutes therefore tend to be clustered, and some are missed in the discharqe countinq because of their proximity to other tracks. The extent of this effect varies from drop to drop and. hence, nonreproducible relations between the content of uranium and the number of the track of the water drop are found. We have solved this problem by olacinq a drop of some solution (named as D2000) on the detector before droppinq the water sample. D2000 not only make uranium distribute uniformly over the area the drop covers but also make the area much bigger, so the detection limit of 5x10~12 can be reached by increasing the volume of the water sample without track clustering.

A special circuit (named as "auto — lock" circuit) was used for preventing small spark following the normal one, so that some loss of counting because of the period between cascade sparks being less than the time resolution of the counter can be avoided.

A oroqram was used for acauirinq the counting data and aettinq the results. Analysis speed of 1 sample per two or three minutes was reached. A comparison between spark countering and microscope reading was made.

257 TRACKS OF SWIFT HEAVY IONS IN SILVER HALIDES, REVEALED BY DIFFERENT METHODS

a) b) F. Granz^r C. Kahn ', G. Hegenbart and H. Kronenberger a)Institut fiir Angewandte Physik, Robert-Mayer-Str. 2-4, D/W-6000 Frankfurt 11, Germany b) Du Pont de Nemours (Deutschland), D/W-6078 Neu-Isenburg, Germany

Silver halides are the most versatile materials for the visualization of the tracks of ionizing heavy particles. Depending on the specific silver halide system in question, the particle tracks are revealed by different methods. In nuclear emulsions the latent track is reinforced by conventional wet development. In the solid state AgCl- detectors CO, the latent image of the particle track becomes visible under the light microscope after illumi- nating the AgCl-crystals with UV-light (decoxation). Ex- posing thin evaporated AgCl-films to a beam of ionizing particles at glancing incidence (- 4°), it is possible to resolve the original fine structure of the particle tracks - i. e. their latent image - without any further amplifi- cation in a high resolution transmission electron microscope (TEM) C2l.

Using an Atomic Force Microscope (AFM), experiments were started recently with the aim, to resolve on an atomistic scale the lattice damage, released by the impinging high energetic heavy ions on the surface of silver halide sheet crystals and evaporated silver halide films. Preliminary results of the AFM-experiments and of the accompanying TEM-investigations will be reported.

HID G. Kaase, E. Schopper and F. Granzer: Radiation Effects 3±, 25 (1977) C2D F. Granzer, B. Pischel and J. During: Nucl. Tracks Radiat. Meas. 15, 101 (1988)

258 Wednesday t Sept. 9

POSTER SESSION I

Nuclear physics

Castillo,F. et al. ENERGY STUDY OF ACCELERATED IONS FROM A (Mexico) s DENSE PLASMA FOCUS BY MEANS OF CR- 39 TRACK DETECTORS 267 Sharma,A. P. RECOMBINATION OF QUARKS AND ANTIQUARKS (Aligarh) • FOR MULTIPARTICLE PRODUCTION IN HIGH ENERGY INTERACTIONS 268

Rusov,V. D. et al. ELECTRON MICROSCOPE AUTORADIOGRAPHY (Odessa): USED FOR STUDING TRITIUM FORMATION AND DISTRIBUTION IN ELECTROLYTIC DEUTERIUM TREATMENT OF PALLADIUM 269 Grabez,B. MULTIFRAGMENT DISINTEGRATION OF 209Bi+Pb (Belgrade). (Ag) SYSTEM AT E/A = 11.6 MEV 270 Shahzad,M. I. et al. STUDY OF MULTIPRONG EVENTS IN THE (Islamabad): INTERACTION OF 16. 7 Mev/U mU- IONS WITH n"Au TARGET USING CR- 39 AND MICA TRACK DETECTORS 271 Tretyakova.S. P. et al. DISSOCIATION OF uLi WITH 34 Mev/N 272 (Dubna)s Raju,J. et al. FUSION-FISSION OF 2S*U AND *°'Bi IN DIFFERENT (Shillong). SSNTDs 273 Ahmed,M. et al. OBSERVATION OF MULTiPRONG EVENTS IN THE (Islamabad): INTERACTION OF 8. 5 Mev/U 2O'Pb WITH Pb (NATURAL) 274 Khan,H. A. OVERVIEW OF THE MASS- DEPENDENCE OF (Islamabad): PION-INDUCED FISSION. 275 Ren,G.-X. BEHAVIORS OF 200AGEV «S AND FRAGMENTS IN (Beijing) s COLLISIONS WITH Cu TARGET. 276 Cui,H.-H. etal. STUDY OF THE INTERACTION OF 960 A MeV "'U (Beijing). IONS WITH LIGHT NUCLEI. 277

259 Zhou,P. -D. et al. STUDY OF HEAVY ION REACTION 2MU -f n"U AT (Beijing). BEAM ENERGY OF 14. 2 MeV/N USING MICA TRACK DETECTOR 278

Space Research

Perron,C. et al. 244Pu FISSION TRACKS IN MICRO- INCLUSIONS IN (Paris); METAL OF CHONDRITIC METEORITES. 281

Jonathal,D. et al. HEAVY ION MEASUREMENT ON LDEF. 282 (Kiel), Huang,R. -Q. MEASUREMENT OF COSMIC RAY HEAVY NUCLEI

(Beijing) s FLUX IN SATELLITE CABIN. 283

Neutron

Hwang,S. D. et al. CHARACTERIZATION OF POLYCARBONATE AS (Hsinchu)j THE SOLID STATE TRACK RECORDER. 287

Boidy,J. M. et al. SOME RECENT DEVELOPMENT OF (Fontenay-aux-Roses): SPECTROPHOTOMETRIC MEASUREMENT OF HIGH NEUTRON DOSES. 288 '• Matiullah, CALIBRATION OF VARIOUS TYPES OF CR- 39-

(Islamabad). BASED NEUTRON DOSIMETERS IN A HEAVY ; i WATER MODERATED AND MONOENERGETIC NEUTRON FIELDS-PART-1 THEORETICAL. 289 Matiullah, EXPERIENCE WITH y AND BD- 100R NEUTRON (Islamabad): BUBBLE DETECTORS. 290 .*

Luszik-Bhadra ,M. et al. REACTOR BEAM PROFILE MEASUREMENTS WITH (Braunschweig) • ELECTROCHEMICALLY ETCHED TRACK DETECTORS. 291 j Wijaya,D.S. et al. EFFECT OF PRESENCE OF GAMMA RAYS WITH I (Islamabad): NEUTRON FIELDS ON THE PERFORMANCE OF A I CR-39-BASED CUBICAL NEUTRON DOSIMETER 292 1-

Wijaya,D. S. et al. REASSESSMENT OF THE CR-39-BASED CUBICAL (Islamabad) : NEUTRON DOSIMETER 293

260 Balcazar,M. et al. NEUTRON SPECTRA PROFILE IN BEAM PORTS OF (Mexico) • A TRIGA MARK I EXPERIMENTAL REACTOR 294

Majeed,A. et al. A SIMPLE TECHNIQUE TO DISCRIMINATE (Islamabad) • VARIOUS CHARGED PARTICLES, USING SSNTDs 295

Azimi-Garakani ,D. ENERGY RESPONSE OF ELECTROCHEMICALLY et al.. (Villigen) . ETCHED PADC AT DIFFERENT ANGLES 296 Zaichich.V.Ye. THERMAL NEUTRON DOSIMETRY WITH SSNTD 297 (Obninsk).

Tommasino,L. et al. A LONG-TERM STUDY OF CR-39 DETECTORS FOR (Rome); NEUTRON DOSIMETRY 298

Cheng,Y.-L. et al. MEASUREMENT OF 14 MeV NEUTRON FLUENCES (Shanghai) s USING SSNTDs 299 Chen,S. N. MEASUREMENT OF ENERGY SPECTRUM

(Beijing) : PARAMETER IN IRRADIATION TUBE OF PROTOTYPE MINIATURE NEUTRON SOURCE REACTOR (MNSR) WITH SSNTD. 300

Geoscience

Tretyakova,S. P. et al. ANOMALOUS OXYGEN IN THE NEAR- EARTH (Dubna): SPACE IN 1985-1989 303 Perelygin,V. P. et al. ON DETERMINATION OF BISMUTH

(Dubna)s CONCENTRATION IN SPECIMENS BY ALPHA- ACTIVATION TECHNIQUE 304 Mateen,A. STUDYING URANIUM DISTRIBUTION IN

(Islamabad): MINERALS OF CARBONATITES FROM NORTHWEST PAKISTAN USING FISSION TRACK ANALYSIS. 305 Zhang,F. et al. A STUDY ON THE METALLOGENTIC EPOCH OF (Guiyang). FINE DISSEMINATED GOLD DEPOSIT IN SOUTHWEST GUIZHOU USING THE FISSION TRACK. 306 Zhao,Y. -L. URANIUM FISSION TRACK M1CROMAPPING AND (Beijing) • ITS APPLICATION. 307

261 Lu,Z. -H. et al. ENDING TIME OF INTENSIVE GEOLOGIC (Zhengzhou) • ALTERNATING ACTION (IGAA) IN TAOWAN GROUP OF QINLING MOUNTAINS. 308

Zhai,P.-J. etal. CALIBRATION OF ZETA CONSTANT IN FISSION (Beijing) s TRACK DATING. 309 Wang,S.-C. etal. A STUDY ON STANDARDIZATION OF FISSION

(Beijing): TRACK DATING. 310

Wang,S-C. etal. THERMAL AND TECTONIC HISTORY OF TWO (Beijing) s BASINS IN NORTH CHINA. 311

Kang,T.-S. etal. THE THERMAL EVOLUTION HISTORIES OF THE (Beijing) : COLLISION ZONE IN ZHEJIANG- FUJIAN PROVENCES OF CHINA FROM FISSION TRACK ANALYSIS. 312 Jing,G.-R. etal. THERMAL HISTORY SIGNIFICANCE OF APATITE (Beijing) : FISSION TRACK LENGTH DISTRIBUTIONS AND AGES. 313

Life and Environmental Sciences

Eissa,H. M. et al. AUTORADIOGRAPHIC INVESTIGATION OF LOW

(Cairo) : ENERGY ACTIVITY USING SSNTD. 317

Shama,M. et al. STUDY OF HEAVY ION TRACKS IN CERTAIN

(Aligarh) s PLANTS OF NORTHERN INDIA. 318 Rusov,V. D. et al. PROBABILISTIC STATISTICS MODELS OF

(Odessa) s INTERACTION OF IONIZING AND NEUTRON RADIATION WITH BIOSUBSTANCE 319 Bersina,I. G. DETERMINATION OF THE ENVIRONMENTAL (Moscow) • RADIOACTIVE CONTAMINATION BY USING PLANT RADIOGRAPHY 320 Majeed, A. et al. AN INVESTIGATION ON IN- AIR DISTRIBUTION (Islamabad): OF METAL DUST DURING MACHINING, USING SSNTDs 321 Bajwa, B. S. et al. ESTIMATION OF URANIUM AND THORIUM USING (Amritsar) s NUCLEAR TRACK TECHNIQUES. 322

Victorova,N. V. etal. NONDESTRUCTIVE CONTROL OF CHERNOBYL (Kiev). HOT PARTICLES BEHAVIOR AND MIGRATION OF RADIONUCLIDES IN SOIL-PLANT SYSTEM 323

262 Borcea.C. et al. ESTIMATE OF THE ABSORBED DOSE DUE TO THE (Bucharest): "Ne BEAM WITH THE ENERGY OF 77. lMev/N AND ITS FRAGMENTS FORMED IN INTERACTIONS WITH WATER AND PLEXIGLAS 324

Perelygin.V. P. et al. ON THE DETERMINATION OF LOW Pu CONTENT (Dubna), IN ENVIRONMENT 325

Dan is, A. et al. THE TRACK DETECTION USE IN INTERNAL

(Bucharest): CONTAMINATION INVESTIGATIONS. 326

Liu,Y.-L. etal. APPLICABILITY OF AUTORADIOGRAPHY TO (Beijing), SORPTION STUDIES. 327

Badr.I. etal. ANALYSIS OP HUMAN HAIR AND LUNG SAMPLES (Birmingham): FROM CONTAMINATED AND NON- CONTAMINATED REGIONS OF BYELORUSSIA USING THE SSNTD TECHNIQUE. 328 Chen,H.L. etal. THE URANIUM CONTENT OF VEGETABLES (Lanzhou). DETERMINED BY METHOD OF FISSION TRACK. 32i/

263 NUCLEAR PHYSICS

265 ENERGY STUDY OF ACCELERATED IONS FROM A DENSE PLASMA FOCUS BY MEANS OF CR-39 TRACK DETECTOR

P. Castillo*, J.J.E. Herrera* and G. Espinosa** * Instituto de Ciencias Nucleares, U.N.A.M. A. Postal 70-543, 04510 Mexico, D.F., MEXICO ** Instituto de Flsica, U.N.A.H., A. Postal 20-364 01000 Mexico, D.F., MEXICO

Abstract A most interesting feature of Dense Plasma Focii is the acceleration of charged particles at energies in the ranqe of MeV per nucleon. This work describes the studies of this phenomenon in a low enerqy device (~6kJ) with a 3.0cm. diam eter copper inner electrode, 10cm. long. The outer electrode is 10.0cm. in diameter. The device is operated with two 1.85yf caDacitors in parallel at 54kV. Accelerated particles are analyzed with filtered CR-39 nlastic detectors for different filling pressures. A detailed study is made of track diameters when the plastic is chemically etched with NaOH. As a preliminary result, accelerated protons in the range of 11 to 16 MeV are observed.

267 RECOMBINATION OF QUARKS AND ANTIQUARKS FOR MULTIPARTICLE PRODUCTION IN HIGH ENERGY NUCLEAR INTERACTIONS

A. P. Sharma Department of Physics, Aligarh Muslim University) Aligarh-202001 (INDIA)

ABSTRACT Muitiparticle production due to 50 Gev/C n"-interaction in Nuclear Emulsion Detec- x>rs under strong magnetic field (~200 Kos) has been investigated for large trans-

erse momentum (i. e. large-PT) as well as low transeverse momentum (i. e. low "T) regions. The quark recombination model with pion, proton and neutron frag- mentations has been used to explain the existence of sharp peak in the low transverse momentum distribution of charged secondary pions (JI+ and JT) seperated out from about 1050 total number of events (stars/interactions). The process of recombination of Quarks-Antiquarks explains satisfactorily the iresence of the sharp peak in the region of Pfc^O. 12 (Gev/C)2. The results clear- y indicated that in the three classes of interactions (Nucleon, CNO and AgBr tar- ;ets), the pions have the much steeper as well as less steeper transverse momentum distribution.

268 ELBCTKOH MICROSCOPE AUTORADIOGSAPHY USED FOR STUDYIHG TRITIUM FORMATIOH AHD DISTBIBUTIOH IB ELECTROLYTIC DEUTERIUM TREATMEHT OF PALLADIUM

Busov V. D. i Semsnov B. Yn. . Zelentsova I. H.

Odessa State University

Presented are positive results of two of the five experiments in detecting tritium in the process of electrolytical treatment of a palladium alloy ( 72* of Fd • £5* AS * 3* Au J by deuterium. The current density being 10 mA/sq. cm .the voltage being £00 vt, the volume being DgO 150 ml. the electrolysis period feeing 6 hours. To detect tritium in samples of deuterium water we used the method of tores liquid sclntillators ( the Brer scintillator. HarK III device]• while to study the spatial distribution upon the palladium electrode surface we made use of the electron microscope autoradiography. The results obtained by the liquid scintillators method are in the table given below. ! Bate of Counting , pulse per mln. ; Substance before electrolysis after electrolysis !

! Fd 96 4-10 £255 t-47 ;

| DgO 529 • - 23 45172 • - 213 j

^Inspection - [Brey scintiTlator 623 • - 9 • Presented are electron microscope autoradiograms of Fd electrode surface, noteworthy is the fact of specific spatial distribution of tritium in the areas that are alfa - beta phase boundaries according to the date obtained by X-ray spectrum analysis. The average quantitative estimates of tritium formation speed obtained by the two methods are practically identical, being 0. 5 109 atom per second.

269 5r.no MULTIFRAGMENT DESINTEGRATION OP Bi+PbCAg> SYSTEM AT E/-AM1.6 MEV

B.GrabeZ Institute of Physics,P.O.Box 57,11001 Beograd,Yugoslavia

The collision of 11.6 MeV/u Bi and Pb nuclei was examined by using CtZ-39 plastic track detector. The comparison is made between results obtained with heavier and lighter CAg> target. It was found that most of the events have two or three heavy fragments 30> in the exit channel. But in some number of events one or two complex fragments <2 are also present. The possible origin of these fragments was discussed on the basis of the correlation analysis.

270 STUDY OF MULTIPRONG EVENTS IN THE INTERACTION OF 16.7 MeV/u238U-IONS WITH nat*Au TARGETS USING CR-39 AND MICA TRACK DETECTORS

M.I. SHAHZAD1, S. MANZOOR2, I.E. QURESHI3 and H.A. KHAN2 I. Computer Division, PINSTECH, P.O. Nilore, Islamabad, PAKISTAN 2. SSNTD-Laboratory, NED, PINSTECH, P.O. Nilore, Islamabad, PAKISTAN 3. Nuclear Physics Division, PINSTECH, Nilore, Islamabad, PAKISTAN

ABSTRACT: In experimental nuclear reaction studies the most general requirement is to measure the yield and angular distribution of the reaction products. CR-39 and mica track detectors have been used for coincidence measurements of the reaction products formed in the interaction of 16.7 MeV/u 238U-ions with nat*Au, employing a 27T geometry technique. The results so obtained have been used to find out the partial, and the total reaction cross-sections- Total reaction cross-section has also been calculated and the theoretical values have been compared with those obtained experimentally. Quarter-point angle has been obtained from the 2-prong elastic data and has been used to compute other reaction parameters. Inelastic total reaction cross-section has been obtained by counting the three, four and five prong events produced in the exit channel.

271 DISSOCIATION OF ULi WITH 34 MeV/n

i.P.Tretyakova , C.Borcea2, A.Golovchenko1, M.Lewitowicz2, C.Toustain2, TVTretyakova .

1LNR, 3INR, 1A1980, Dubna, RUSSIA !GANIL, 14021 Caen Cedex, FRANCE.

Dissociation of radioactive nuclei provides important information on the nuclei with the giant neutron halo. A stack of CR-39 layers with the total thickness exceeding the ion range was used for the investigation this problem by the track method. After the ion irradiation and chemical etching measurements of track diameters on all the CR-39 layers were carried out. ^ At the dissociation of ULi there were formed \i ions. Their (ULi and Li) original energies are equal. However the energy losses (dE/dx) snd the ranges (R) of these ions will be different when these ions will be stopped on passing through the detector stack. The difference in dE/dx would affect the track diameters and their spectral distribution on the layers along the stack thickness would affect the track diameters and their spectral distribution on the layers along the stack thickness would change. Mathematical development of the track diameters spectral distribution allowed to separate the ULi tracks from the \i ones. The calibration curve D(dE/dx), the calculated dependences dE/dx CE) and R(E) allowed to obtain the 9Li distribution along the ULi range >nd to calculate the dependence of the ULi dissociation possibility an their energy.

272 FUSION-FISSION OF 238U AND 209Bi IN DIFFERENT SSNTDs

J.Raju and K.K. Dwivedi Department of Chemistry, North-Eastern Hill University, Shillong-793 003, INDIA.

Fusion-fission of energetic 238U and 209Bi in different SSNTDs has been studied using 2n-geometry technique. Results indicate that the projectile ions react with the atoms of the detector matrix leading to the formation of the excited compound nuclei and subsequently scission of the compound nuclei take place in the forward hemisphere. Important results obtained from the experiments have been discussed.

273 OBSERVATION OF MULTIPR0N6 EVENTS IN THE INTERACTION OF 8.5 Mev/u Pb208 WITH Pb (NATURAL)

1 9 M. Ahmed", • H.A. Khan 1. National Physical and Standards Laboratory (NPSL), PCS1R, 16-H/9, Islamabad, Pakistan. 2. SSNTD-Laboratory, NED, PINSTECH, P.O. Nilor, Islamabad, Pakistan. Using rr.ica as nuclear track detector, we have studied the interaction of 8.5 Mev/u Pb ions with natural level target. We have carefully looked at the characteristics of tracks formed in mica by frequency distributions of track lengths and angles, in the case of two and three body channels. The partial cross- sections for different multibody channels are calculated and the total reaction cross-sections are estima* ted . These values have been compared with the theoretical predictions based on the systematics of nuclear radii. In the case of binary events, we have isolated the elastic subset by using the criterion of angular correlation valid for elastic scattering. Then the elastic scattering data was used to determine the quarter-point angle.

274 OVERVIEW OF THE MASS-DEPENDENCE OF PION-INDUCED FISSION H.A. Khan, Pakistan Institute of Nuclear Science & Technology P.O. Nilore, Islamabad, Pakistan N;A. Khan, COMSTECH, Islamabad, Pakistan R.J. Peterson, Nuclear Physics Laboratory, University of Colorado, Boulder, Colorado 80309-0446, U.S.A.

A study of n+-induced fission of targets from iron through uranium has been completed at 80 and 100 MeV, using track-detector techniques. Measured fission cross sections have been converted to fission probabilities Pf by comparison to computed reaction cross sections. At these two v+ energies, nearly equal values of Pf are found, and these are muc greater than the probabilities for fission induced by stopped n" for " lighter nuclei. A theory based on the 'high energy approximation' of Moretto et al., v^ing only known parameters, is found to agree with these data for both pion charge states. We use the total pion energy, kinetic plus rest mass, in this calculation, since our data show that fission probabilities are dependent upon the fissility parameter (Z*l)2/A, including the sign of the incident pi meson. Other evidence for the achievement of nuclear excitation energies near 200 MeV with little angular momentum will be presented to confirm our model.

275 BEHAVIORS OF 200AGEV ^S AND FRAGMENTS IN COLLISIONS WITH CU TARGET

Ren Guoxiao Jing Guiru Institute of High Energy Physics, Academia Sinica, Beijng 100039

Using CR-39 nuclear track detectors and an automated scanning system , the behaviors of 200AGeV 32S and projectile fragments with charges

276 STUDY ON THE INTERACTION OP §50 A MeV 258U IOHS WITH LIGHT NUCEEI Huan-Hua Cui1 , Wei Ke1 , Jian Zhou1 , V/ei-Chun lu2 and R. Brandt5 1 Institute of High Energy Physics, Acadeinia Sinica, P.O.Boy 2732, Beijing, China 2 Tsinghua University, Beijing, China 3 Kernchemie, FJ314, Philipps Universitat, D-3r5O Marburg, Germany A CR-39 track detector was used both as a target and a detector to study the interaction of 960 A KeV 2;)5U ions with light target nuclei (1H, 12C, 160), the constituents of CR-39. The range, mean free path.and cross section of 960 A MeV J U ions in CR-39 have "been measured. The experimental value of range is in good agree vrith the value calculated theoretically. The experimental values of mean free path and cross section have been compared with the values calculated theoretically. The average multiplicity due to fragmentation of 238U projectiles with light target nuclei in CR-39 has been found to be 2.03. It shows that the roost common mode of the interaction is binary fission.

277 STUDY OF HEAVY ION REACTION + r*tu AT BEAM ENERGY OF 14.2Mev/N USING MICA TRACK DETECTOR

Pef-De ZhoufShhLun Guo,R.Br8ndn,P.v3ter

Chin? ^Tstftote of Atomic Energy, P.O.Box 275(86), Beijing 102413, China

-. Kernchemie FB14,Universit6t Marburg, D-3550 Marburg, Germany

Heavy ion reaction 14. 2Mev/N 2aeU + »•* U is studied using 2^-geometry technique with muscovite mica. The irradiation was performed at the UNILAC accelerator in GSI, Germany. The track analysis was carried out at China Instiutte of Atonic Energy. The spherical coordinates of the tracks were measured using a normal optical microscope system. Using the quantitative analysing methodology developed by P. A. GottschaIk ct al. and the standard velocity--range data, we performed the detailed kinema - tical analysis on the reaction. Numerical analysis of the track data (range-1, polar angle- 6, azimuthal angle- qp ) yielded masses and energies of the reaction products formed in the mu 11ifragment 6 events. Based on masses and energies of the reection products, sorae quantities such as total kinetical energy loss ( TKEL ) , relative velocity of each two correlated fragments and so on can be obtained. As showed in the others previous studies on the same kinds reaction at the different beam energies (7.5, 9.0, 16.7 Mev/N) , the main reaction channel of 14. 21/iev/N zaeU +"°*U is the sequential fission process after quasi-elastic or deep inelastic collision.

278 SPACE RESEARCH

279 FISSION TRACKS IN MICRO-INCLUSIONS IN METAL OF CHONDRmC METEORITES.

Claude Perron and Michele Bourot-Denise Institut d'Astrophysique Spatiale and Museum National d'Histoire Naturelle, 75005 Paris, France

We have been studying for some time mineral inclusions in the metal phase of chondritic meteorites. They consist in oxidised forms of Si, P and Cr, which, most probably, formed by exsolution from solid solutions of these elements in Fe-Ni metal, at some early stage of metal evolution. In the most primitive chondrites (i.e. chondrites which suffered very little transformation on their parent body), these inclusions are very small (

D. Jonathal, R.Beaujean and W. Enge Institut fur Reine und Angewandte Kernphysik Christian-Albrechts-Uniyersitat, W-2300 Kiel, FRG

The NASA Long Duration Exposure Facility (LDEF) was put into a 28° inclination orbit at 250 nm altitude on April 7,1984 and was retrieved at 180 nm altitude on January 12, 1990. The LDEF maintained a constant orientation during the mission.

The Kiel LDEF experiment M0002 was designed to measure the heavy ion environment by means of CR-39 plastic solid state track detectors. The detector stack with a size of 40*34*4.5 cm^ was exposed in vacuum covered by thermal protection foils with a total thickness of approximately 14 mg/cm2. Two additional stacks, each with a size of 40 mm depth and 95 mm diameter, were integrated in subunits of the Biostack Experiment A0015. They consists of CR-39 and Kodak cellulose nitrate foils under 10 mg/cm2 Kapton shielding.

The number of heavy ion tracks detcted in Kodak-CN is much higher then in CR-39, which is equivalent to a higher sensitivity. The detected arrival directions of low energy particles are close to a plane perpendicular to the magneticfieid line at the edge of the SAA. This is an evidence for the detection of heavy ions from a radiaton belt population. Results of the charge composition and the energy spectra of these particles will be given. MEASUREMENT OF COSMIC RAY HEAVY NUCLEI FLUX IN SATELLITE CABIN

Huang Rongqing Institute Of .High Energy Physics* Academia Sinica Beij ing

ABSTRACT Some experimental work is described which has been designed to investigate the distribution and to measure the flux of cosmic ray heavy nuclei in satellite cabin. In August 1988 and October 1990. we twice placed six plastic nuclear track detector stacks on the difference place in satellite cabin. The detector stacks consisted of CR-Sy^Makrofol-E and Laxan plastic sheets. The thickness is 1. 1.5> 2.1 and 3.3 cm. respectively. Each stack effective area is about 100 cm2 . After the flight, the plastic track detectors were etched. The particle tracks were scanned and measured by an opticl microscope. The heavy charged particle fluxes and the distribution were obtained in the cabin. Some information vere provided for experimental investigations in the field of radiation damage of organism and electronic devices in our space experiments. NEUTRON Characterization of Polycarbonate as the Solid State Track Recorde

S.D.Hwang C.S.Tauzo Institute of Nuclear Engineering National Tsing Hua University Hsinchu.Taiwsn.R.O.C. Abstract Polycarbonate .one of the organic aaterials. was used to the solid state track recorder ( S.S.T.R.) in neutron physic.Fission fragments were always thought as the bullets to shoot the track recorder and to produce daaages. Counting the nuiber of danages and the absolute fission rate would be known. This paper would discuss about the performance of a polycarbonate and the relation between etching tiie and the track density. Using an lathenatic lodel to descripe the relation between the diameter and etching tite. Poisson distribution was used to coapare with the frequency histograi to estimate the randos error froi counting the S.S.T.R. . The agreement was good for this result . And using the S.S.T.R. in a low fast neutron field leasured the fast neutron flux. The S.S.T.R. can easily leasure fast neutron as low as 1 0 # / c v?

i .this is difficult for K.A.A. method to leasure.

I SOME RECENT DEVELOPMENT OF SPECTROPHOTOMETRIC MEASUREMENT OF HIGK NEUTRON DOSES

J.M. BORDY, R. MEDIONI, H. BOUESCAYROL and G. PORTAL CEA, DPHD/S-DOS, Centre d'Etudes, B.P. n*6, 92265 Fontenay-aux-Roses, Cedex, FRANCE

An attempt has been made to develop a track density determination method suitable for high neutron uose irradiation (ie : criticality accident dosimetry). In a previous paper, we have found that the measurement of the optical transmission of a monochromatic light through CR39 detector, chemically etched, is a possible method to perform measurements from 0.3 Gy to 100 Gy. We have used this method to perform measurements from 3 10"* Gy to 0.4 Gy to determine its dose threshold. Different kinds of CR39 (produced by Intercast Europe SPA [Italy], and American Acrylics) were studied. They were irradiated near AmBe and JMCf neutron sources. The results obtained show that : - depending on the quality of the CR39, the threshold is different. The best result (8 10"4 Gy) is obtained with Italian CR39. - a linear relation between the optical density and neutron kerma can be obtained by suitably adjusting chemical etching conditions. The experimental results are presented. CALIBRATION OF VARIOUS TYPES OF CR-39-BASED NEUTRON DOSIMETERS IN A HEAVY WATER MODERATED AND MONOENERGETIC NEUTRON FIELDS - PART-I: THEORETICAL

MATIULLAHn, X. YANG2> AND K. KUDO3)

1) Centre for Nuclear Studies. Nilore, Islamabad/ Pakistan 2) RadiometroIogy Center/ Institute of Atomic Energy/ P.O. Box 275(20)/ Beijing, P.R. of China 3) EIectrotechnicaI Laboratory/ 1-1-4 Umezono/ Tsukuba-shi/ Ibaraki 305/ Japan

Computer calculations have been performed to determine calibration factors of various types of CR-39-based neutron dosimeters in a heavy water moderated 252rjf an(j monoenergetic neutron fields in free air and on a water phantom. In the case of a heavy water moderated 252rjf source/ the neutron spectra from the source was determined with MORSE-CG code. The back-scattered neutron spectra on the surface of the water phantom was determined with MCNP code and then the contribution of these back-scattered neutron to the dose equivalent was estimated. EXPERIENCE WITH 7 AND BD-100R NEUTRON BUBBLE DETECTORS

MATIULLAH(1> AND K. KUD0(2>

1) Centre for Nuclear Studies/ Nilore/ Islamabad/ Pakistan 2) EIectrotechnicaI Laboratory 1-1-4 Umezono/ Tsukuba-shi, Ibaraki 305/ Japan

After achieving a reasonable success in BD-100R neutron bubble detectors/ the Bubble Technology Industries has recently developed a new type of 7 -bubble detector and is commercially available. A series of experiments were carried out in order to determine the sensitivity and the effect of temperature on both of the above-mentioned detectors. The response of both of the detectors is strongly dependent upon the temperature during irradiation. The 7 bubble detector needs a lot of improvements before it can be applied in actual measurements. Although BD-100R detector has a lot of promising properties/ it can not replace CR-39 based personnel neutron dosemeter but they complement each other. REACTOR BEAM PROFILE MEASUREMENTS WITH ELECTROCHEMICALLY ETCHED TRACK DETECTORS

M. Luszik-Bhadra, E. Dietz Physikalisch-Technische Bundesanstalt, W-3300 Braunschweig, Germany

The beam profile of the bismuth-filtered thermal neutron beam of the • PTB research reactor has been measured using track detectors etched electrochemically on a relative big area of 5,5 cm x 5,5 cm. The tracks were counted automatically with an image analyser. With the use of track-shape analysis also tracks appearing in close distance are counted separately and linearity is observed up to several thousand 2 tracks per cm . With the use of two CR-39 track detectors, one of them in contact with a thermal neutron converter, and a Makrofol foil it is possible to determine the local distribution of the thermal neutrons as well as the local distribution of fast neutrons present in the beam with energies above 70 keV and above 1.5 KeV. The method may be useful in beam positions, where it is not possible to use electronic devices or a scanning apparatus. The results are compared with those obtained with other techniques. EFFECT OF PRESENCE OF GAMMA HAYS WITH NEUTRON FIELDS ON THE PERFORMANCE OF A CR-39-BASED CUBICAL NEUTRON DOSIMETER

D. SOFIA WIJAYAn AND MATIULLAH2

1) PPTN BATAN, Tl. Tamansari/ Bandung, Indonesia 2). Centre for Nuclear Studies/ Nilore, Islamabad/ Pakistan

The observed response of CR-39-based personnel neutron dosimeters may be significantly influenced by the environment in which the dosimeters are exposed. One of the factor which may effect the performance of the dosimeters is the presence of gamma rays with neutron fields. To quantify this, samples of CR-39 were exposed to neutrons, gamma rays, alpha particles and fission fragments under various conditions and the effect of presence of gamma rays with neutrons on the response of CR-39-based neutron dosimeter was investigated. Moreover, the effect of gamma rays on etching characteristics of CR-39 was also studied. Our results indicated that high gamma rays doses significantly affect the response and etching characteristics of the dosimeter. REASSESSMENT OF THE CR-39 BASED CUBICAL NEUTRON DOSIMETER

D. SOFIA W1JAYA1} AND MATIULLAH2

1) PPTN BATAN/ Tl. Tamansari/ Bandung/ Indonesia 2). Centre for Nuclear Studies/ Nilore, Islamabad/ Pakistan

CR-39 based cubical neutron dosimeter/ reported by Ma t i uI I a h and Durrani several years ago. has been reassessed. Significant improvements have been made in the detector assembly and the response of the detector is tested experimentally on a phantom. Our studies indicated that such a detector assembly would be very promising in routine neutron dosimetry. NEUTRON SPECTRA PROFILE IN BEAM PORTS OF A TRIGA MARK III EXPERIMENTAL REACTOR.

M. Balc£zar, A. Defffn, M. E. Camacho, R. Maz6n and L. Tavera. Instituto Naoional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico, D. F.

The Triga Mark III research reactor located at the Nuclear Center of Mexico had an array of nuclear fuels mainly formed by 20 % Uranium enrichment, the fuel configuration is modified each eighteen months or so according to a fuel management program, in order to keep the neutron flux as close as the reactor original specifications. Recently the fuel life improvement program (FLIP) was introduced in the nuclear core activities to extend the reactor life. The 26 FLIPE fuels of 70 % Uranium enrichment changed substantially the neutron flux characteristics, both in the core and the beam ports. Dose profile measurements were performed in the three beam ports at three power levels 100 kW, 300 kW and 1 MW. Continuous dose measurements on a circular cross section in the beam port was achived by means of a set

of two CR39 detectors, one covered by foils of B10O3Li2 to increase thermal neutron detection efficiency. On each CR39 detector ten gold activation foils were placed to obtain discrete neutron fluence measurements. Five of the activation foils were covered with cadmium sheets to suppress neutron energies below 0.4 eV. Seven dose profile data inside each beam port were obtained with the experimental set-up described above. Routine analysis techniques for activation foils and CR39 detectors are used to obtain neutron fluence measurements from which dose values are derived. A SIMPLE TECHNIQUE TO DISCRIMINATE VARIOUS CHARGED PARTICLES, USING SSNTDs

A Mijeed, S M Ahmtd tnd S A Durrini

A complete evaluation of the effectiveness of a neutron therapy beam requires information about the distribution of various charged particles produced in tissue by neutron interactions. The major problem in the study of these distributions has always been the discrimination among various types of charged particles. There hardly exists any detector which can successfully discriminate and give a separate estimate of various charged particles in a mixed field. Because of the importance of these charged particle distributions, their study is, however, very vital in neutron therapy applications.

SSNTDs being tissue equivalant in composition, are now widely used in various neutron therapy related measurements. An interesting property of these detectors, the selectivity of response, makes these detectors very useful for cahrged particle distribution studics.too. Using this property of SSNTDs a simple technique has been developed which helps in discriminating among the tracks produced by different types of charged particles. This paper describes the details of this technique which is based on the use of three different types of polymeric track detectors (CR-39, CN-85 & Lexan), each having different registration characteristics and etch them under specially chosen conditions. The technique has successfully been tested to discrimnate among the tracks produced by protons, alpha particles and C, O & N recoils, in neutron irradiated plastics. ENERGY RESPONSE OF ELECTROCHEMICALLY ETCHED PADC AT DIFFERENT ANGLES

D. AZIMI-GARAKANI AND C. WERNU Radiation Hygiene Division, Paul Scherrer Institute CH-5232 Villigen PSI, Switzerland

The energy response of various electrochemically etched poly allyl diglycol carbonate (PADC) track detectors at different angles were studied. The detectors were irradiated at the angles of 0°, 30° and 60° for the neutron energies of 144 keV, 565 keV, 5.3 MeV, 14.8 MeV and ^Cf bare spectrum. The variations of the angle dependence response at 30° were found to be higher than those at 60° for various types of PADCs. Below 5.3 MeV, the response at the wedge angles, is reduced by some 70%, but at 14.8 MeV, the reduction is less pronounced. The angle dependence response falls off more rapidly than the calculated value. THERMAL KEUTBDH D0SIK3MH WITH SSHTD V.Ye.Zaichick Institute of Medical Radiology,Obninsk,Russia

The activation detectors (foil made of gold, indium, copper etc.) are generally used to measure thermal neutron flux. However these detectors often turn to be unfit because of specific conditions of neutron application for medicine (for example, fractionary irradiation, rather small neutron flux etc.). A solid state nuclear track detector on the basis of nitrocellulose (KG) is used for theunal neutron monitoring while a special optico-electronic system - for the measurement of *—track numerical density on the detector surface. The d. -particles form micro destructions in the NC along their trajectory. Then by etching -with alkali the mi erode struct ions can be enlarged up to sizes visible by means of a light microscope. A detector represents a cylindrical ampule made of polyethylene, filled with lid solution (96£ concentration) and contained the 1\TC film of 100 ftm thick. Following the Li (n,ik) nuclear reaction (its section is 950 barn) thermal neutrons cause the

L. TOMMASINO, G. TORRI, M. CAVAIOLI, K. P.ICCAP.DI AND TRINK VAN GIAP Divisione Ketodologie e Kisure, ENEA-D1SP

Via V. Brancati 46, 00144 ROME 1TALV

In che past decade, the neutron response of CR-39 dosemeteres has been investigated several times using different etching processes and materials from different manufacturers. In spite of the fact that the data have been gathered using different batches, stored and aged under different conditions, the neutron-response has resulted highly consistent. By contrast, the detector background has shown lack of reprcducibility not only from batch to batch but also from sheet to sheet vithin the same batch. In spite of the many efforts made in the past, little success has been achieved in the prodution of CR-39 materials with consistently low background.

At this stage the possibility to use the etching process and/or counting procedure capable of differentiating background from neutron-induced recoil tracks appears to be an interesting alternative. MEASUREMENT OF 14 KeV NEUTRON FLUENCES USIKG SSNTDs

Yulin Cheng, Junying Lin/ Eufa Zhang, Rcng Lu, Liping Zheng Shanghai Institute of Nuclear Research, Acade.nia Sinica, P.O.Box 800-204, Shanghai 201800, P.R.China

ABSTRACT

The CSR (China Shanghai Resin) and (polycarbonate) PC tr*ck detectors have been used for measuring fast neutron fluences ranging frc.a 10. tc 10 n/c.r. . A comparative study of two different modes cf fast neutrcn measurements based on SSNTDs is presented. In the internal radiator mode, the neutrons are detected due to the alpha particles and recoil nuclei created in the SSNTDs itself, e.g. C, O and K presenting in the detectors by neutron interactions. In the external radiator mode, the SSKTD is covered by a front radiator consisting of 0.5 mm thick polyethylene (PE) , or with fissile material , and the tracks are produced by recoil protons cf the (n,p) reaction or fission fragments of U(n,f) reaction; recoil particles and (n,a) reactions created in the detector itself by neutrcn interactions. Results show that the CSR detector can be used successfully for detecting 14 KeV neutron fluences in the range from 5 x 10 to 6 x 1010 n/c.ti . The detection -5 efficiency cf the CSR is on the average 2.88 x 10 tracks per neutron and the CSR with PE radiator is 3.32x10 tracks/n. The detection efficiency cf the PC detector with a thin layer cf uranium is 1.75 x 10 tracks/n for detecting fast neutron fluences in the range from 2.5 x 10 tc 5 x 1010 n/cm2.

KEYWORDS: CSR and FC fietectcrs. PE and uranium rsniahors. MEASUREMENT OF ENERGY SPECTRUM PARAMETER IN IRRADIATION TOBE OF PROTOTYPE MINIATURE NEUTRON SOURCE REACTOR (MNSR) WITH SSNTD

Chen Shaoneng, Xi Dejiang China Institute of Atomic Energy, P. 0. Box 275(75)* Beijing 102413, China

In this paper, the parameters of the energy spectrum in irradiation tube in the prototype Kiniature Neutron Source Reactor (KNSR) has been measured by relative comparative method with the ^Pu-^TJ fission sources and the muscovite mica solid state nuclear track detector The measurement principle, device, date treatment and error analysis are introduced in detail. The results are in agreement with other methea• GEOSCIENCE ANOMALOUS OXYGEN IN THE NEAR-EARTH SPACE IN 1985-19B9 S.P.Tretyakova , N.L.Grigorov2, D.A.Zhuravlyov2, M.A.Kondratyeva2, A.V.Podgurskaya and Ch.A.Tretyakova

Joint Institute for Nuclear Research, 141980 Dubna, Russia o Research Institute of Nuclear Physics of the Moscow State University, Moscow, Russia Some exposures of DTD stacks were made on "Cosmos" earth-or-biting satellites in the period 1964-89. The orbits were close to circular ones inclination angle was 70* at 350-420 km altitude in most experiments, exposure duration was typically 14 days (an oriented flight, as a rule). This duration provides sufficient statistics and the possibility of discrimination between exposures made in solar quiet period and those which took place during solar proton events. Small stacks (4-8 layers) of nitrate cellulose "Kodak" 90-100 urn thick and 10-50 cm2 in area were used to detect CN0 ions. Such stacks make it possible to determine the energy of the CNO nuclei that had there, in the energy range between 4 and 20 MeV/nucleon, and distinguish reliably these nuclei according to their charges. The procedure of charge determination was a standard one, by the L-R technique. An analysis of the energy spectra, charge ratios, angular distributions and time variations of the ion fluxes leads to the conclusion that the particles detected in the experiments in the solar minimum pariod are the ions of the anomalous cosmic-ray component which penetra- te on to altitudes of observation directly from interplanetary space and from the Earth's magnetosphere. The set of the experimental data obtained supports the assumption that the anomalous oxygen ions are partly ionized. >.. •

ON DETERMINATION OF BISMUTH CONCENTRATION IN SPECIMENS BY ALPHA-ACTIVATION TECHNIQUE

V.P.Perelygin, S.G.Stetsenko Joint Institute for Nuclear Research, 141980, Dubna, Russia

The ©(-activation technique for high-sensitive Bismuth exploration in common rock minerals and alloys is developed. The technique based on bombardment of smooth surfaces specimens is being investigated with high fluxes of accelerated deuterium ions, E^ 6 MsV/n total fluence 0=10 - 10 . The pv-active polonium isotopes then are produced in nuclear reactions 209Bi. After deuterium beam exposure the induced activity of Po c* -emitters is measured with ^-sensitive plastic track detectors - cellulose nitrate, cellulose acetate poly(allil)diglycolcarbonate (CR-39) placed in close contact with the specimen surface for few hours or cays. The control experiment with deuterium exposed Pb foils provides no A'-particle track at all. The sensitivity obtained under these conditions corresponds to Bi concentrations at the level 10" g/g the space resolution of Bi inclusions is ^10-15 urn. Our technique allows one to determine minor Bi concentrations and local inclusions in specimens which contains much higher content of Pb and other elements. STUDYING URANIUM DISTRIBUTION IN MINERALS OP CARBONATITES FROM NORTHWEST PAKISTAN USING FISSION TRACK ANALYSIS

A. MATEEN1, A. AHMED1, A.A. QURESHI2, HAMID A.KHAN2, A.RAUF3

1) Centre for Nuclear Studies P.O. N1LORE, ISLAMABAD, PAKISTAN

2) SSNT-Laboratory, N.E.D. PINSTECH, ISLAMABAD, PAKISTAN

3) Department of Earth Sciences, Quaid-i-Azam University ISLAMABAD, PAKISTAN

Series of experiments were carried out in order to determine uranium distribution in minerals of carbonatites rock assemblages using fission track analysis. For this purpose samples were collected from kno.;n localities of carbonatites occurrences in the Peshawar Plain alkaline igneous province, northwest Pakistan. Our results show interesting patterns of uranium distribution in mineral grains in terms of textural relationships. Geochemical dispersion of uranium in carbonatites is interpreted in relation to track-length distribution in uranium bearing minerals. A STUDY ON THE METALLOGENTIC EPOCH OF FINE DISSEMINATED GOLD DEPOSIT IN SOUTHWEST GUIZHOU USING THE FISSION TRACK

Zhang Feng Yang Keyou Institute of Geochemistry, Academia Sinica, . Guiyang, Guizhou 550002

ABSTRACT Southwest Guizhou, which is located at the Yunnan, Guangxi and Guizhou delta area, is not only a very important ore glebe, but it is also one of the places of Chinese ultramicro disseminated gold ore. In this paper, metallogenetic epoches of beidl deposit, in Ceheng county and Lannigou deposit, in Zhengfeng county, have been studied by using the fission track method. Quartz in pyrite-qurtz veinule, which has direct relationship with metallogenesis, is chosen as object of study. Ac- cording to the results of many experiments, the optimum etching condition of quartz was discoveried. Through counting the spontaneous fission and induced fission tracks of quartz in large quantities and widely, and correcting them as a whole, we overcome the difficulties of low uranium content and fire particles. The metallogenetic epoches of beidl and Lannigou deposits are (87. 6±6. 1) Ma, and (82. 9±6. 3) Ma respectively. These results are very important for metallogenetic condition of fine disseminated gold ore and deposit forecast. URANIUM FISSION TFACK KICROMAPPING AND ITS APPLICATION

ZHAO YUNLONG Bei.iing Research Institute of Uranium Geology P.O.Box 764 Beijing, 100029 P.R. CHINA

Solid state track detectors have unique capabilities for rr.essuring the concentration and srcatial distribution of ursnium in rock, minerals et pi. In this t>nr)er we present the br>sic techniques of urrnium mp-niaing in geology samples ( rock, minerals et al ) snd the application of uranium fission track method to the study of uranium redistribution in the process of granite alteration. Also, it is made an aT)t>roch to resource of uranium'and cause of formation of uranium ore deposit. EKDING TIME OF INTENSIVE GEOLOGIC ALTERNATING ACTION (IGAA) IN TAOWAN GROUP OF QINLING MOUNTAINS

Lu Zuhui, Xu Aijun, Chen Dongrong, Vang Yujin Fundamental fc Applied Science Research Institute of Kenan Zhengzhou University, Zhengzhou, P. R. China 450052 Gou Shilun, Kao Xiouhong Atonic Energy Institute, China Academy, Beijing Guan Baode.Tao ZiJiang Geogolic Institute of Henan, Zhengzhou

Teowan Group of Qinling Mountains, as the juncture of the two great geologic structure units of north and sourth China, has a great complex geologic conditions and had ever experienced many tines of late intensive geologic alternating actions (IGAA), such as invading, extruding and mixing of magmas which had intensively changed its original pedologic conditions. It is very important to determine the tine of the lastest IGAA in Taowan Group for studying the geologic structure and exploring the mineral resources of Qinling Mountains. For the lacking of fossil evidences and only having few isotopic age data, it has become one of the most controversial issues of geology to determine its forcing time and its changing process. Taowan Group was deduced being formed in 569-682 Ma. and experienced the lastest IGAA in 324*30-362+40 Ma. from isotopic age data(l).

In our work, a total caculated aera 46.82x10"*" cm1 were observed in 22 rock grains which were seperated from 20 Kg cf phosphate rocks collected at the seise site as reference(l), and 77S induced fission traks and 13G self- fission tracks were caculated in the out ttica detectors at a radiated neutron flux of 5.96xI0'fc n/cii' . At the confident level of 95%, it was deternined by the experisive age recorded with the nuclear fission tracks in sosphate rocks that the lastest IGAA ended in £3

Reference: 1. Zhang L-Q, Liu D-Y, Fu G-M, Isotopic Age Study in Qinling Monutains, Kuanping, Taowan. (to be pubilished; CALIBRATION OF ZETA CONSTANT IN FISSION TRACK DATING

2HAI PENGJI Institute of High Energy Physics, Academia Sinica Beijing 100080, PRC

ZHAO YUNLONG Beijing Institute of Uranium Geology, Beijing 100029, PRC

In order to system calibration in fission track dating zeta constant method was recommended so that it is possible to compare fission track data from different laboratories with ages from other radioisotopic techniques. In our laboratory FiEh Canyon Tuff, Buluk Member Tuff and Tardtee Rhyolite zircon, Fish Canyon Tuff and Durango apatite and dosimeter glass NBS-SRM 612 or 962 have been used for the calibration. All zircon and apatite smaples. were determined using the external detector. The etching of zircon-mounts and apatite- mounts were carried out in molten NaOH+KOH at 210 *C and HNO3 +HF at 190 *C subsequently and in 5% HNO3 respectively. Throughout the study spontaneous and induced tracks were counted using an Olympus microscope with.lOOx oil or 40x dry objective and 15x eyepiece and the area of tracks counted was estimated by an eyepiece graticule. The zeta constants determined are give as 330.918.3 for zircon, 331.3117.3 for apatite, showing no significant difference between the two minerals. The weighted mean zeta value is 331.0+7.5. A STUDY ON STANDARDIZATION OP FISSION TRACK DATING Wang shicheng and Kang tiesheng (Institute of High Energy Physics, Acadimia Sinica) (P.O. Box 2732, Beijing, China)

Two methods were used to improve procedures of fission, trftck dating (1) to monitor neutron fluence during reactor irradiation using 962 standard uranium glass calibrated against Co activation foils; (2) to determine Zeta calibration constants. NBS SRM 962 standard glass has been calibrated against Co monitors in nine irradiations in an irradiation hole at anoutergraphite reflector in HWRR reactor (Beijing) over two years. Mean value of the calibration factor B is found to be (5. 86± 0. 28) »io' neutron/track for conventional neutron fluence. Then three zircon, three apatite and one sphene age standards were employed to check the accuracy of neutron fluences calculated using B. (V/_f<-for each age standard was measured by external detector method. The reference age of age standards, fs /f^andRvalue of 7. 03*10q a~J were sub6tituded into age equation to calculate neutron fluences. The results show that neutron fluence measured by 962 glass are approximate to the values measured by age standards. However it was found that the former are systema- tically 1-10% higher than the later. Thus Zeta constant calibration was used to reduce the systematic error. "Zeta constants have been determined for above mentiond age standards. The Zeta values determined against the 962 glass are 325.0+11.6 for zircon, 336.8+4.6 for apatite and 332.1 + 9.6 for Ephene. THERMAL AND TECTONIC HISTORY OF TWO BASINS IN NORTH CHINA

Wang shicheng and Kang tiesheng (Institute of High Energy Physics. Acadimia Sinica) (P.O.Box 2732, Beijing, China) Feng Shi and Zhou Licheng (Beijing Graduate School, Petroleum University)

Apatite fission track analysis has been used to study the thermal and tectonic history of two wells. Fission track ages and confined track lengths in 37 apatite samples have been measured. Fission track age data from Xishe-1 well 6how a pattern of ages which decrease with depths. The mean confined track lengths decrease from 11. 45 MO with a standard deviation of 1.49 M in at near surface level to 6. 61 Mm at 4.0km with a standard deviation of 2. 62 M m and a positively skewed distribution. Both fission track age data and track length data in Xishe-1 well consistently show an increasing degree of annealing in samples from increasing depths. Samples from Qiu-3 well show a little similar pattern of age and different track length distributions. The track length distributions of two samples at the depths of 2.2km and 2.7km are much wider than the ones expected from their present temperature and contain a large number of tracks shorter than 10 Mm, which could result from annealing at high tenperature at some time in the past. There was a early cretaceous period unconformity and the upper cretaceous system has missed in this well from stratigra- phic data. All these facts suggest that the cooling was due to uplift and erosion. A quantitative modelling of fission track annealing in apatite has been developed to estimate maximum paleotemperature. The differences between estimated an A toBnontnro THE THERMAL EVOLUTION HISTORIES OF THE COLLISION ZONEIN ZHEJIANG - FUJIAN PROVENCES OF CHINA FROM FISSION TRACK ANALYSIS

Kang tiesheng, Wang shicheng (Institute of High Energy Physics, Academia Sinica) (P.O.Box. 2732, Beij ing China) Wang yihua (Deparpment of Geoscience, Nanjing University, Nanj ing, China)

Abstract

The collision zone in Zhejiang - Fujian provinces of China has involved continental collision - mappe structure evolution process. Fission tracks in mineral can provide rich thermal history informations. In this paper, the zircon - apatite pair ages were measured by zeta -calibration method and apatite fission track length distributions were measured. Based on the ages and closing temperatures of zircon and apatite, single gain age and apatite track length distributions, time of the collision movement and thermal evolution histories of the collision zone were determined. THERMAL HISTORY SIGNIFICANCE OF APATITE FISSION TRACK LENGTH DISTRIBUTIONS AND AGES Jing guiru, Wang shicheng and Kang Tiesbeng (Institute of High Energy Physics, Academia Sinica) (P.O.Box 918, Beijing, China)

Apatite fission track length distributions and ages provide an integrated record of the low-temperature thermal history of the host rock over geologic time scales. Baeed on the fanning model of fission track annealing for appatite presented by G. M. Las let t, a forward computer modelling of track shortening and age evolution was given in this paper. The thermal significance of apatite track length distribution and ages was studied for the following four types of thermal histories: 1) isothermal heeting; 2) linear cooling; 3) linear heating; 4) step heating. The fission track length distribution and age evolution are given for above-metioned thermal histories. The forward model has been used for thermal history analysis of sedimentary basins in China. LIFE AND ENVIRONMENTAL SCIENCES AUT0RADI0GRAPH3C INVESTIGATION OF LOW ENERGY ACTIVITY VS1KG SSNTD

H.M. EISSA. K.Pi. SHARAF, G.M HASSAN. M:A EL FIKI

ABSTRACT: Atechnique is described by which the distribution of redionulei in histolagical sections kidney and liver of rats are visua3ised by nuclear track recording plastics. The particles emitted from radio- nuclei contained within the section, register as tracks in CR39 . AN image of tissue stucture is induced superimposed upon particle track distribution by autoradiography . The uranyl acetate was injected introperitoneal into rats with activity 55 Bq/mL The effeciency of CR39 for «particle is 0.52. The distribution of ^activity in ashed samples was found highest in kidneys STUDY OF HEAVY ION TRACKS III CURTAIN PL A NTS OF KOHTH^HN INDIA

Madhuri Sharma and A.N.Maurya D.S.Postgraduate Collece(Agra University), Aligarh-202001

ABSTRACT Study of investigation of heavy ion tracks(aiostly Uranium ion tracks) in soae edible plants and soil samples from Northern India using Plastic Track Detector technique has been. .;ade • The heavy ion dose in various plant parts end its impact in aetabolism is being estimated » Undoubtedly the tiote is found maximum in the soil layers, while it shows a aini value in the stems part of the plants as compared to their leaves. The concentrate on of Uranium heavy ion^cereais is found comparable with that of plant roots* PROBABILISTIC STATISTICS JiODELS OF 1HTEFACTI08 OF IOHIZIKG AKD HEUTKOH KADIATION WITH BIOSUBSTAKCE V. D. Rusov, T. S. Zelentscva, ¥. F. BabiKova Odessa State University

Ionizing and neutron radiation effect upon cells is Known to be a spectrum of various types of aberrations (injuries ) depending upon quality of radiation, cell types, and other reasons. UP to now much effort has been spent to maKe biophysical models tod determine the yield of chromosome aberration as dependant upon ionizing radiation or neulrfctts. Those attempts were based on studying the function of aberration distribution In the process of Ionizing or neutron radiation of cells. But It was so far of no use. The paper describes some probabilistic statistics models of detecting the ionizing radition by the biosubstance that are based on chromosome aberration statistics and that provide parameters required t« identify and to quantitatively analyse the radiation, Presented are results of experimental data of chromosome aberrations in eucariot cells esposed to X-ray and neutron radiation, it is shown that the detection statistics of eucariot cells chromosome aberration in the said experiments was under the Neumann distribution , trpe A . Noteworthy is the fact that the said models need thorough and purposeful checKins upon a much wider range of experimental material. Therewith It is possible to maKe similar stochastic multiple models to count for the blodetector properties and radiation patterns, The suggested novel probabilistic statistics approach in solving direct and inverse problems of chromosome aberration statistics in cells has a potential for identification and quantitative analysis of nuclear radiation ( biospectrometry ) as well as for studying the stochastics of energy transfer in cells (microdosimetry J. The most important result of the said approach is a prospect of nontrivial biophysical experiments both in the field of fundamental studies of radioblological effects upon various levels of organisation and In practical application, e.g. as an express - method of dosimetric diagnostics and inspection of radloecoloeic situation in areas of potential radioactive contamination . such as alpha - monitoring. DETERMINATION OF THE ENVIRONMENTAL RADIOACTIVE CONTAMINATION BY USING PLANT RADIOGRAPHY

I.G. Bersina

Institute of Railways Transport, Moscow, U.S.S.R.

The radiography technique enables one to manifest the radioactive contamination accumulated by plant's parts, such as leaves, trunk and roots, to determine the degree of the radioartive pollution of the environment, to identify the element composition of that and to find out the radioactive dust even if its quantity is small. The data concerning interpretation of the radioactive pollution distribution pictures obtained for different parts of plants have been given. The methods allowing one to identify availability of the dust radiopollution and soil radiopollution penetrated into a plant through the roots have been also discussed. The report presents the experimental data on the manifestation of the radioactive contamination sources above-enumerated and a comparison of the radiogram data with the data on the 7-irradiation dose power measurements. It is shown that contemporary methods designed to manifest the radioactivity do not supply complete information about availabUity of local radioactive sources in the environment. The latter makes it possible to conclude that the standard safety radiation levels need to be revised qualitatively and quantitatively to eliminate a risk of getting radioactive elements into a man's organism by a direct way from the air and/or the agricultural plants. The questions concerning manifestation of uranium, plutonium and their radioartive decay products have been considered.

1 '3 AN INVESTIGATION ON IN-AIR DISTRIBUTION OF METAL DUST DURING MACHINING, USING SOLID STATE NUCLEAR TRACK DETECTORS

A. Majeed, Z. Hoswin, F. Humanyon, S. M. Ahmed

Institute of Industrial Autojoation P.O. Box No. 1384, Islamabad, Pakistan.

Fine metal dust is produced during machining of hard metals. Although most of it is washed away with the cooling fluid, the part escaping the coolant sheath is spread in the air and constitutes internal hazard to operator. Experiments, using SSNTDs, have been performed to determine the spatial distribution of dust from hard metals, spread in the vicinity of cutting tool. The dust particles have been found to follow parabolic paths with varying ranges, the most abundant being approximately 14-16 cm. The information about the distribution of such machine produced metal dust may be extremely helpful in designing a Safety System for the machine operator. ESTIMATION OF URANIUM AND THORIUM USING NUCLEAR TRACK TECHNIQUES. B.S.BAJiVA and H.S.VIRK Department of Physics Gjru Nanak Dev University Amritsar - 143005

The relation connecting the concentration of Urenium and Thorium atoms in geological samples with a- track production rates in plastic track detector LR-115 type-2 and fission track rates in Lexan has been used for the analysis of radioactive fossil bones. The a- track measurements from the samples under secular equilibrium define the total Uranium and Thorium concentrations whereas fission track measurements yield Uranium concentrations alone* So by combining the results of both measurements Uranium and Thorium is determined. Fission track show that Uranium is dispersed throughout the fossil bones. However, a white layer of a bone may contain only half as much as the darker organic-stained layer and the surface of bone can be depleted in Uranium. Autoradiographic patterns reveals the highest track densities in the rsdioactively darkened zones of samples. NONDESTRUCTIVE CONTROL OF CHERNOBYL HOT PARTICLES BEHAVIOR AND MIGRATION OF RADIDNUCLIDES IN SOIL-PLANT SYSTEM

N.V.Victorova1, V.V.Demchuk1, E.V.Ganga1, N.A.Chuiko1, S.P.Tretyakova2

Hydrometeorological Institute, Kiev, Ukraina 2 Laboratory of Nuclear Reactions, JINR, Oubna, Russia

The Chernobyl hot particles dimensions and their composition were measured by the nondestructive beta- , alpha- , and fission fragment radiography by the dielectric track detectors and special X - plates. The behavior and the migration of the radionuclides in soil- plant system were investigated under the laboratory conditions. The radionuclides (5r, Cl, Cs, Co, Pu, U) were inserted into soil where the different plants have to grow. After definite time a part of the plants were cut off and the cytological samples were prepared for investigation. These nuclides entering into the plants from the soil and their distribution dynamic during their growth were observed by the track and X - radiography. ESTIMATE OF THE ABSORBED DOSE DUE TO THE 20Ne BEAM KITH THE ENERGY OF 77.1 MeV/nucleon AND ITS FRAGMENTS FORKED IN INTERACTIONS WITH WATER AND PLEXIGLAS

C.Borcea1, A.N.Golovchenko2, S.P.Tretyakova2, R.Anne3, G.Tousset3, C.Tostain3, R.Bimbot4, F.Clapier4, B.Kubica4. IFA, R-76900 Msgurele-Bucharest, P.O.Box MG-6, ROMANIA 2 JINR, LNR, 1419B0, Dubna, RUSSIA 3 GANIL, B.P.5027, 14021, Caen Cedex, FRANCE 4 IPN, 91406 Orsay Sedex, FRANCE.

The present study is a part of the research aimed the application of heavy ion beams for radiotherapy of malignant tuirors. The solid state track detectors CR-39 and CN-85 were used to estimate the absorbed dose due to the 20Ne beam with the energy of 77.1 MeV/n and to its fragments from the reactions with tissue equivalent materials (CR-39, plexiglas and water). When the calibrating dependence Dj=f(dE/dx) (where D, is the track diameter) and the diameter spectrum on each detector layer are available one can cbtain the elementary dose value. In this case it is not necessary to know beforehand the partial yield of fragments after the interaction of the primaty beam nuclei with the given matter. The detectors were calibrated with the ions of 4He and12 C on the U-200 accelerator (LNR, JINR). The calibration curves, the track diame-

ter DT of the particle entering the detector normally, were obtained with respect to the energy^.loss, dE/dx. Preliminary results on the depth dose distribution and on the yield of fragments (of about 10% relative to the primary beam flux) with 3^Z^9 beyond the Bragg peak of 20Ne are obtained. ON THE DETERMI.'iATION OF LOW Pu CONTENT IN ENVIRONMENT

v.P.Perelygin, Yu.T.Chuburkov Joint Institute for Nuclear Research, 141960, Dubna, RUSSIA

The method of Z39Pu minor content determination in the soil water, air, living species is developed. It is based on chemical extraction of plutonium from the specimens. The 236 Pu cv'-active tracer which was choosen to control the chemical yield of Pu from samples being investigated was obtained with accelerated helium ions in the reaction U( He,3n)" Pu. After chemical separation the foils with Pu were putin contact with polytere- phtalrte foils and irradiated on pulsed nuclear reactor IBR-II 3INR with thermal neutron fluences 1015-1016 cm2 together with culibrated etnslon. After proper etching and scanning the Pu content in soil specimens from some Ukraina regions were determined to be 310 "-1.210 x g/g. To check the possible Th-U minor admixures of U and Th in Pu fractions the control experiments with heavy flux 23 MeV 2 - ravs were carried out. It provides on upper limit of admixture of these nuclei at the level of ^ 108 por sample. The method proposed provides much higher — 1 Tt sensitivity of Pu determinations-at the level of 10 1 Tt-1 0 "^ h g/'g than any.other techniques of Pu exploration. Ana DAl-:iS, Maria CUCU, Liarians CIUSOTAKIU Institute of Physics said iruclear Engineering, Bucharest

The ain: of these Gaudies consists of establishing the experimental conditions in which the track detection can be used in fissiojasble element internal con inves- igg aation and to chose the adequatq e method or certain investigations. As fissionable element the uranium hs.s beer, used. A rat '.Vistex-London breed v;&s internptl contseined by ingest ion. 'i'he rat or{~sns £.s v/ell &s itsevacuation conpo- nersts were analysed 'oy track detection. A lot off expe iner.- ts were performed in order to establish: - the more adequate track dexection method - alpha tr^ck method or fission track method - as well &s the sampling ways and the processing of the samples for track analyses. Pour sodes' on the sampling and processing of the samples were investigated: a) soft tissues sampling just after the rat '.7as sacrified; b) thermal drying of the soft tissues; c) drying by alcohol dehydration; d) calcination. The re.t evacuation components collected for each 24 hours, the urine separated from e:-:crer:.ents, v/ere analysed only as crlcined SEr;plesp . The experimeitln al led us to following conclusions : - the track detection is an efficient method in the qualitative and quantitative investigations of the interna c on t aL"}i r.at ion; - the biodistribution of fissionable element in soft tissue sc:r.ples car. beobtained only by the fission track ethohdd using a mineral trsck detector. The plastic alphr track detector is destroyed by the liquids the soft tissue consists in;; the fission track method it is possiblp e to accurately the uranium amount fixed in different organs as well as that one evacuated by urine end excre- ments for a certain period after the contamination; - the track detection is the only method which can visualise by track aicrosappings the biodistribution of fissionable elements ir; each body organ, but after the animal sacrification. APPLICABILITY OF AUTORADIOGRAPHY TO SORPTION STUDIES

Liu Yonglian, Zheng Venji and Hu Xiuhau

China Institute of Atomic Energy

Autoradiography has been used to determine the distribution of radionuclides sorbed on the rock samples. The observed radionuclide. distributions reveal the sorptive capacity of variable mineral components of the rock samples. All autoradiograms were made with nuclear emulsion plates to study the sorptive distribution of some radionuclides such as Pu-239, Am-241, Tc-99 and I-I25 on the different kinds of the rock samples, and some valuable results have been obtained.

Jb ANALYSIS OF HUMAN HAIR AND LUNG SAMPLES FROM CONTAMINATED AND NON-CONTAMINATED REGIONS OF BYELORUSSIA USING THE SSNTD TECHNIQUE

l.Badr and S.A.Durrani School of Physics and Space Research University of Birmingham Birmingham BIS 2TT, EngJand

Abstract

Five human hair and five lung samples were received by us towards the end of 1990 from putatively contaminated as well as non-contaminated regions around the site of the Chernobyl nuclear accident of April 19S6. These were analysed using the SSNTD technique. The samples, which included control specimens from the former USSR as well as a British control hair sample, were prepared for analysis by first ashing them at 300 C and then compacting them into pellets of diameter 21 mm and depth 2 mm. The lung samples had already been charred before dispatch to us by the staff of the Nuclear Power Engineering Institute of the BSSR Academy of Sciences in Minsk. The hair samples were found to have levels of alpha activity ranging from 21 to 62 Bqkg~ ; the solid lung tissue samples displayed an activity of 3 - 66 Bqkg"1. These levels are broadly comparable to those expected in a normal healthy subject. Statistical analysis indicates that the 62 Bqkg" level for one of the hair samples is the only statistically significant result (p <0.01). showing high c-activity. These findings can therefore be said to corroborate the recent report of the IAEA International Chernobyl Project, published in the Proceedings of the International Conference, held at Vienna in May 1991. This report suggests that the ill effects found in the area are primarily due to factors other than abnormally high levels of radiation. The Uranium Content of Vegetables Determined by Meethod of Fistion Track®

Chen Huailu Jing Lanhuax Chen Fahu (Lanzhou University, Lanzhou, P. R China) liu Xuezhen (Institute of Endemic Disease of gansu Province, Lanzhou, P. R China)

Abstract

The basic principle and method of fishion track are detailed explained in this paper. The method is also used to determine uranium content of vegetables both in polluted lanzhou City and unpolluted counties around Lanzhou City. The measurement results are analysised by comparison. It is shown that uranium contents of vegetables in polluted area are much higher than those in unpolluted area. In polluted area the uranium content of cucumber leaf, up to 26. 49 10""g/g, is highest.

1. Preparation and Measurement Oi Samples

Samples, including Chinese leek, eggplant leaf, hot pepper leaf, garlic leaf, tomato and its plant leaf, and cucumber and its plant leaf, are taken form Erjia Vallage of Lintao County, Binjiawan Village of Yuzhong County and Juenjiatan Village of yaotan Township of Lanzhou city. Sample is put on center of washed auter Sounder film and dried by heat after weighing, and then covered by a layer of film. Finally, the Sample is irradiated with hot niutrons after wrapped by aluminium platinum paper. The accumulation rate of hot neutrons is 7. 34 X10" neutrons/cm2. The Sample after the irradiation are cooled and washed. Then, it etched in the NaOH solution wich concentration of 6. 25N at 50 Centigrade for 80 minutes. The numbed of fishion tracks is counted under optics microscole.

2. Experiment Result and Discussion Table 1 Average urarium content (by 10""g/g) of different Vegetables.

Smples lot- tomato cucumber Chinese ;ggplanf garlic tomato cucumber content jepper plant plant leek eaf leaf location eaf leaf leaf

Lanzhou 9.42 15.80 13.16 9.70 2.25 10.47 6.84 26.49

Yuzhong 1.96 5.79 5.00 1.38 1.22 1.40 1.30 7.33

Lintao 2.00 6.66 7.09 1.58 1.04 1.38 1.42 7.64

ft can be seen from the table that the uranium content of egetables in Lintao and Yuzhong Is almost same, while that in Lanzhou is much higher than that in the tow counties. The uranium content in leaf are higher than that other part of vegetable. Therefore, it is suggested that the best way is to plant vegetables in the area far away torn polluted area, but if vegetables have to be their friuts are the best choice. Friday, Sept. 11

POSTER SESSION I

Radon

Segovia, N. RADON CONCENTRATION LEVELS IN

(Mexico): DWELLINGS AND MINE ATMOSPHERES IN MEXICO 337

Matiullah RADON MEASUREMENTS IN SOME HOUSES OF (Islamabad) • TSUKUBA SCIENCE CITY JAPAN. 338

Matiullah RECENT STUDIES ON RADON- A MEASURE OF (Islamabad)- LIVING STANDARD. 339

Eissa,H. M. et al. CR-39 AND LR-115 AS A SECONDARY STANDARD (Cairo). DOSIMETER FOR RADON MEASUREMENTS. 340

Eissa,H. M. et al. INTERCOMPARISON MEASUREMENTS OF RADON (Cairo) • CONCENTRATION USING SECONDARY STANDARD RADON CHAMBER. 341 Adriamanantena,R. et al. RADON MEASUREMENTS WITH LR-115 AND CR- (Kiel). 39. 342

Espinosa,G. et al. COMPARATIVE STUDIES OF POLYMER (Mexico) s MATERIALS AS Rn PROTECTION COATIOGS. 343

Borau,J. et al. RADON LEVEL MEASUREMENTS INSIDE (Mexico) • MEXICAN CAVES. 344

Singh,M. et al. RADON DIFFUSION STUDIES THROUGH

(Amritsar); HYDROCARBONS. 345

Singh,B. et al. EARTHQUAKE PREDICTION STUDIES IN KANGRA (Amritsar): VALLEY USING PLASTIC TRACK RECORDERS. 346

Hadler,J. C. et al. PERFORMANCE OF THE ALPHA-SPECTROMETER (Campinas) • CR-39 VERSUS ETCHING TIME AND ITS POSSIBLE APPLICATION IN RADON/ THORON DISCRIMINATION. 347 BariJlon,R. et al. COMPARISON OF EFFECTIVENESS OF 3 RADON (Besancon ); DETECTORS (LR115, CR39 AND SILICON DIODE PIN) PLACED IN A CYLINDRICAL DEVICE. THEORY AND EXPERIMENTAL TECHNIQUES.

Chambaudet,A. et al. FEATURES OF A NEW RUSSIAN TRACK (Besancon): DETECTOR FOR RADON MEASUREMENT.

Abu-Jarad,F. et al. PASSIVE RADON SURVEY IN THREE FLOOR (Dhahran): LABORATORY.

Segovia,N. et al. RECOMMENDATIONS FOR THE SETTING-UP OF A (Mexico) • RADON IN SOIL NETWORK BASED UPON A DECENNIAL STUDY.

Morin,J. P. et al. AN AUTOMATIC ELECTRONIC COUNTER FOR (Montpelher). SHORT TERM RADON MEASUREMENTS IN SOIL AND/OR WATER.

Morin,J. P. et al. A TRI- DIMENTIONAL MODEL FOR RADON (Morntpellier) • TRANSPORT IN A POROUS MEDIUM.

Azimi-Garakani, D. PREDICTION OF SEASONAL RADON (VMigen). CONCENTRATIONS FROM WEEKLY SCREENING MEASUREMENTS. Azimi-Garakani, D. RESPONSE OF DIFFERENT PASSIVE DETECTORS (Villigen)s IN A RADON CHAMBER.

Birkholz,W. et al. Rn MEASUREMENTS IN DWELLINGS. (Leipzig) •

Mahat,R. H. SOIL RADON DOSIMETER FOR HOT HUMID (Kuala Lumpur): TROPICAL REGION.

TufaiI,M. et al. RADON DOSIMETERs OPTIMIZATION OF

(Islamabad): GEOMETRICAL PARAMETERS FOR UNDERGROUND MEASUREMENTS. Baixeras,C. et al. STUDY OF THE TWO- STEP ELECTROCHEMICAL (Barcelona). ETCHING CONDITIONS APPLIED TO POLYCARBONATE DETECTORS USED IN RADON DIFFUSION CHAMBERS. Shi,J. -H. et al. MEASUREMENTS OF RADON LEVELS USING CSR (Wuhan): DETECTOR IN HARBIN AND YAN' AN. Sun,Z.-T. RADON DISTRIBUTION MEASUREMENT OF LUGO (Zhengzhou); COAL MINE BY CSR TECHNIQUE

Zhai,P. -J. et al. THE EFFECT OF USING WATER IN A TOILET ON (Beijing): INDOOR RADON LEVEL.

Fan,X. COMPARISON OF RADON MEASURING (Xian): INSTRUMENTS OF CHINESE MADE WITH OF JAPANESE MADE.

Pang,D.-L. A SMALL PASSIVE MONITOR FOR RADON WITH

(Shanghai): CR-39 (DAP).

Pang,D. -L. A NON- CONSTANT CONCENTRATION RADON (Shanghai) • CALIBRATION CHAMBER.

Shen,B. M. THE APPLICATION OF CR-39 SSNTDs TO RADON (Huhehaote) • SURVEY IN THE MAIN CITIES OF INNER MONGOLIA.

Luo,D. -L INDOOR RADON MEASURED WITH NUCLEAR (Guangzhou): TRACK DETECTORS AND CHARCOAL CANISTERS IN HONG KONG.

Filters and Material Sciences

Ogura,K. et al. APPLICATION OF THE PRESOAKING EFFECTS TO (Chiba): THE PRODUCTION OF CR-39 MICROFILTERS.

Dey,M. et al. DEVELOPMENT AND CHARACTERIZATION OF (Shillong): POLYCARBONATE MICROFILTERS.

Hussain,G. et al. THERMAL STABILITY OF PORES IN NUCLEAR (Islamabad): TRACK MICROFILTERS.

Gemende,B> et al. APPLICATION OF PARTICLE TRACK MEMBRANES (Rossendorf ): IN SOLVENT RECOVERY.

Shriwastwa,B. B. et al. ASSESSMENT OF SSNTD TECHNIQUE FOR

(Bombay) • QUANTITATIVE ESTIMATION OF UO2 CONTENT IN NATURAL UO2- ThO2 MIXED OXIDE PELLETS INCOMPARISON TO X- RAY FLUORESCENCE, Luguera,E. et al. SIMULATION OF A THERMOLUMINESCENT (Barcelona): CaSO4! DY DOSIMETER FOR BETA RADIATION DETECTION. 379 Fernandez,F. et al. PREPARATION AND CHARACTERISTICS OF A (Barcelona): CaSO4 s DY THERMOLUMINESCENT DOSIMETER. 380

Wu,R.-S. A NEW NUCLEAR TRACK MICROPOROUS

(Beijing) s MEMBRANE. 381

Wang,Y. L. et al. THEORETICAL CALCULATIONS AND MONTE (Beijing), CARLO SIMULATIONS OF MULTIPLE HOLE PROBABILITIES FOR ETCHED NUCLEAR TRACKS. 382

Luo,Y. S. et al. AUTOMATED IMAGING SYSTEM FOR ETCHED TRACK COUNTING. 383 (Beijing)

,1 RADON RADON CONCENTRATION LEVELS IN DWELLINGS AND MINE ATMOSPHERES IN MEXICO

N. Segovia*, P. Pena*, F. Mireles**, I. Davila** L. Quirino** *ININ, Ap. -Post. 18-1027, llSOl-Mexico, D.F., MEXICO *CEN, UAZ, Cipres 10, 9S000, Zacatecas, Zac . , MEXICO

Atmospheric radon surveys have been performed in dwellings and mines from the city of Zacatecas, and -- unifamiliar homes in Mexico City. The monitoring \\Tas performed using track detectors, LR 115 type II, and exposure times were between one and four months during one year. Twenty unifamiliar houses and seven mines have been monitored in the city of Zaca- tecas and 50 home were under survey, both indoors and - outdoors, in Mexico City. Preliminary, results show moderate'radon values below 100 Bq/m in most of the studied atmospheres. Some values higher -- than 150 Bq/m3 are discussed as a function of local - -- meteorological and geological parameters as well as related to the particular building characteristics. RADON MEASUREMENTS IN SOME HOUSES OF TSUKUBA SCIENCE CITY -JAPAN

MATIULLAHn, K. KUDO2) AND X. YAN63)

1) Centre for Nuclear Studies- Nilore« Islamabad/ Pakistan 2) E I ectrotechnica I Laboratory/ 1-1-4 Umezono/ Tsukuba-sh i , Ibaraki 305/ Japan 3) RadiometroIogy Center/ Institute of Atomic Energy. P.O. Box 275(20)/ Beijing, P.R. of China

Measurements concerning radon and its daughter products concentration levels have been performed in some selective houses of Tsukuba science city using CR-39 detectors. To do so/ CR-39 detectors were installed in the bed rooms of the selected houses for 3 months during the winter season. The radon exposed samples were then processed/ analyzed and related to the WL. Our studies indicate that the radon levels are very low in the houses surveyed. RECENT STUDIES ON RADON - A MEASURE OF LIVING STANDARD

MATIULLAH

Centre for Nuclear Studies, Nilore/ Islamabad/ Pakistan

Following the work reported elsewhere/ we studied the effect of temperature on the radon concentration levels. For this purpose/ a small volume of "6pa solution was taken in a tube and then placed carefully in a bottle. Radon concentration level was studied as a function of temperature using CR-39 and LR-115 detectors. To obtain the desired temperatures/ refrigerator and water controlled bath were used. This study indicated that temperature significantly affects the radon concentration levels and together with the ventilation data/ one may be able to guess about the living standards of the residents from the measured values of radon and its daughter product concentration levels. CR-39 AND LR-115 AS A SECONDARY STANDARD DOSIMETER FOR RADON MEASUREMENTS

X H.M. E1SSA, M.A. SHARAF. fl. LOTFV M.A. KENAWY and M:A. EL-FIKI

NATIONAL INSTITUTE ^STANDARDS, CAIRO, EGYPT. (tUNIVERSITY COLLEGE OF GIRLS, AIN SHAMS UNIV. EGYPT.

I ABSTRACT: CR-39 and LR-I15 were used as secondary I standard dosimeter for radon measurement • The secondary standard radon chamber was designed and constructed at NIS. The response of both CR-39 and LR-115 SSNTD'S for K-particle registration was estimated as 0.59 track/K. 0.2 track/*; respectively, a refrence standard Ka source of activity 956 Bq was used. Radon and radon daughters concentrations were calculated compared with these obtained by CR-39 and LR-115. Data obtained vcas 50 PCi/L, 49.73 PCi/L and 44.39 PCi/L respectively; which shows that CR-39 is mere efficient. [NTERCOMPARISON MEASUREMENTS OF RADON CONCENTRATION USING SECONDARY STANDARD RADON CHAM3ER

M. EISSA , M. LOTFY NIS, CAIRO, EGYPT

ABSTRACT: Atecnique for intercomparison measurements of radon concentration using secondary standard radon chamber was developed at the NIS EGYPT, using a refrence instruments for radon measurements. A set of detectors CR-39, LR-115, Charcoal, TLD detectors and radon monitor were used for this purpose. The coversion factor for these detectors was* determined . A standard refrence radon source of activity 956 Bq was used for the intercomparison studies. RADON MEASUREMENTS WITH LRJJ5 AND CR-39

R.Adrtamanantena, T.KJeis, R.Gbose and W.Enge Jnstitut fur Reine und Angewandte Kernphysik Christian-Albrechts-Universitat Kiel, D-W23OO Kiel, FRG

Calculations of Rn-sensitivities for LRH5 and CR-39 IT.KIeis, W.Enge and H.Woith: 1991] have been continued. The calculations have been carried out for different shapes of Rn-detector-containers under consideration of various environmental parameters, e.g. airpressure and aerosol concentration. Theoretical models based on the calculations will help to compare Rn-measurements carried out with different types of Rn- detector-containers. The results of the calculations will be compared with the results of an experimental calibration.

Reference: T.Kleis, W.Enge and H.Woith, "PJastic Detectors for Radon Monitoring in Earthquake Prediction", Nucl.Tracks Radiat Meas., Vol.19, Nos.1-4, 1991 COMPARATIVE STUDIES OF POLYMER MATERIALS AS RADON PROTECTION COATINGS Espinosa, 6. and Golzarri, J.I.

1NSTITUTO DE FISICA, UNAH. APDO. POSTAL 20-364 01000 MEXICO, D.F. MEXICO

and Gammage, R.1 OAK RIOCE NATIONAL LABORATORY HEALTH AND SAFETY DIVISION OAK RIDGE, TN. 37831-6383

ABSTRACT

The control of indoor radon levels has become a public health issue. New regulations and architectural designs are being developed for residential areas, homes and public buildings. Radon concentrations are directly related to the ratio between energy conservation and open-window ventilation. A large percentage of the accumulated radon comes via its infiltration through walls and floors. Some possible solutions to the problem involve: 1) the use of thermally insulating boards which still allow the passage of radon to the outside; and 2) the use of coatings to reduce the infiltration through the walls and floors. In this work we present the results of a comparative study of different coatings for walls, floors and/or ceilings. These coatings are specifically made with polymeric materials with different permeability to radon, and besides, are easy to apply to walls, floors and ceilings without affecting the architecture and decoration. keywords: Nuclear Tracks; Radon; Coating materials.

~ RESEARCH SPONSORED BY: U.S. DEPARTMENT OF ENERGY UNDER THE CONTRACT DE-AC05-840R21400 RADON LEVEL MEASUREMENTS INSIDE MEXICAN CAVES Borau, J. and Gonzalez, A. FACULTAD DE CIENCIAS, UNAH. CIRCUITO EXTERIOR, C.U. MEXICO, D.F. and Espinosa, G. and Golzarri, J.I. IHSTITUTO DE FISICA, UHAH. APDO. POSTAL 20-364 01000 MEXICO, D.F. MEXICO

ABSTRACT

Living animal species on Earth have been exposed to environmental radon from the very beginning of time. The effects of radiation, combined with other natural parameters such as temperature, humidity, salts content, etc.,, have most likely influenced the evolution of different species. Thus, it is important to know and to evaluate the radon levels, among other radioactive elements present in enclosed environments such as caves, especially since those caves were also the dwellings and refuge of the predecessor of man.

In this work we present radon level measurements inside some caves with vestiges of ancient inhabitants and some recently discovered natural caves, using Nuclear Track Detectors.

keywords: Environmental radon; Caves; Nuclear Tracks. RADON DIFFUSION STUDIES THROUGH HYDROCARBONS

Manwinder Singh* Surinder Singh and H.S.Virk Department of Physics* Guru Nanak Dev University Amritsar-143 005, India.

The inherent mobility of radon has stimulated interest in its use for detecting small* near surface tectonic features and buried radioactive deposits. Radon and -ray measurements may also be useful in connection with prospecting for petroleum deposits. In tie present study* the experiments related to radon diffusion/migration through different medias viz.* water and hydro-carbons (Petrol* diesel and Mobile oil) has been carried out using solid state track detectors (LR-115 Type 2). It has been observed that the radon activity through water is three to four times higher as compared to the hydrocarbons. In hydrocarbon the activity of radon is of the order of petrol>diesel> Mobile oil. The diffusion coefficients and diffusion lengths have also been calculated in these continuous medium . EARTHQUAKE PREDICTION STUDIES IN KANGRA VALLEY USICNG PLASTIC TRACK RECORDERS

Baljinder Singh and H.S. Virk Physics Department, Guru Nanak Dev University, Amritsar - 143 005 (India).

Earthquake prediction is based on the precursory phenomena and radon has emerged as a useful precursor in recent years. Radon emanation in soil-gas was continuously monitored at sensitive observation sites since August 1989 in Kangra valley of Kimachal Pradesh using LR-115 type II plastic track recorder. The recording stations viz. Palampur, Andretta, Chamunda Devi, Dharamshala and Mcleod ganj are located on the main boundary thrust of Himalayas. Many earthquake related anomalies are recorded. To observe the effect of meteorological parameters viz. soil, and air temperature, pressure, humidity and rainfall were also monitored. A correlation matrix is computed for radon data and meteorological parameters to eliminate the effect of spurious signals. PERFORMANCE OF THE ALPHA-SPECTROMETER CR-39 VERSUS ETCHING TIME AND ITS POSSIBLE APPLICATION IN RAPON/THORON DISCRIMINATION

J.C.Hadler N., P.J.Iunes, A.P.Policastro and S.R.?aulo

Depto. de Ralos Cosmicos e Cronologia, IFGW, Universicade Estadual de Caipinas, 13081, Campinas-SP, Brazil

In this work, it is investigated the possibility of determining the relative concentrations of two racon isotopes (R.n-222 and Rn-220) in the air, using a solid state nuclear track detector (CR-39) as an alpha-spectrometer. Samples of such detector were exposed to Rn-222 and daughters and Rn-220 and daughters atmospheres. Analyzing only roundish tracks, it was observed that the performance of CR-39 as an alpha-spectrometer varies with etching time, improving markedly for long etching times. Possible applications of this technique to indoor radon monitoring and to the employment of CR-39 as an alpha-spectrometer in Nuclear Physics are discussed. COMPARISON OF EFFECTIVENESS OF 3 RADON DETECTORS (LRl 15, CR39 and SILICON DIODE PIN) PLACED IN A CYLINDRICAL DEVICE. THEORY AND EXPERIMENTAL TECHNIQUES

R.BARELLON', D.KLEIN^, A.CHAMBAUDET1 and CDEVILLARD*

- Laboratoire de Microanalyses Nucleaires, UFR des Sciences et echniques, La Bouloie, Universite de Franche Comte, 25030 Besancon 'edex, France - Laboratoire de Metrologie des Interfaces Techniques, 1UT de elfort-Montbeliard, Universite de Franche Comte, BP 527, 90016 elfort, France

Researchers at the Laboratory of Nuclear Micfoanalysis in esangon (FRANCE) are developing and improving radon measurements in order to detect and analyse, more precisely radon manation anomalies in both fields of Earth Sciences and adioprotection.

In order to characterize radon emanation, two complementary jchniques are developed: continuous measurement through a oriable proportional counter and passive measurements by nuclear ack deiectors for both fieldwork and laboratory analysis.

A mathematical model is being devised to interpret the nuclear ack detector response. This model is performed according to the ;vice characteristics: type of detectors, shape and size of cells and hether a membrane is used or not.

Added to the theoritical study, experimental radon >ncentration measurements will be reported. FEATURES OF A NEW RUSSIAN TRACK DETECTOR FOR RADON MEASUREMENT

A.CHAMBAUDETl, V. PAUTOV2, D.KLEIN3 and CBARENBOIM*

1- Laboratoire de Microanalyses Nucleaires, UFR des Sciences e Techniques, La Bouloie, Universite de Franche Comte, 25030 Besanc,on C&dtx, France 2- State Research Institute of Photochemical Industry Pereslavl- Zalessky Branch, Pereslavl-Zalessky, Russian Confederation 3- Laboratoire de Metrologie des Interfaces Techniques, IUT de Belfort-Montbeliard, Universite de Franche Comte, BP527, 900]6 Belfort, France 4- Ecological Station of Environmental Control (ESCOS), Kardovski St.20, Pereslavl-Zalessky, Russian Confederation

In order to develop Russian-French collaborations in the field of radon 222 measurements, a new russian polymeric track detector of high sensitivity (cellulose nitrate) is being studied.

This detector is used as an integrating alpha particle registration device for radon dosimetry. Firstly, the geometry of pecific cells, etching parameters and technical analysis methods were optimised. Comparison with radon measurements obtained by other nuclear track detectors (LR115 and CR39) and by different echniques (proportional counter and silicon diode) is performed in Besancon (France) and in Pereslavl Zalessky (Russian confederation). The results aTe compared and analysed in order to .define the ields of applications and the standard responses of this new detector. PASSIVE RADON SURVEY IN THREE FLOOR LABORATORY

F. ABU-JARAD AND M.A. ISLAM Energy Research Laboratory / Research Institute King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia

ABSTRACT

Small Radon survey was performed in the Energy Research Laboratory (ERL) building as part of a general background radiation survey for gamma, neutron and tritium. The purpose of the survey is to establish the base line and background level of all various sources in the newly built laboratory which accommodate two particle accelerators (14 MeV neutron generator D-T reaction and Tandetron). The radon activity in the three different floors of the laboratory building is being surveyed by distributing passive radon dosimeters in different places of the building. The dosimeters has been calibrated four times through CEC inter-comparison in NRPB/ UK. For comparison purpose, few dosimeters were also distributed in many houses in the university campus. The paper will address the results of the survey and compare it with similar work previously done in the kingdom.

350 RECOMMENDATIONS FOR THE SETTING UP OF A RADON IN SOIL NETWORK BASED UPON A DECENNIAL STUDY

N. SEGOVIA , E. TAME2 . J-P. MORIN , M. MONNIN , J-L SEIDEL * : Instituto Nacionalde Investigaciones Nucleares, App. Post. 18-1027, 11801 Mexico, DF, Mexico. **: Laboratoire d'Hydrog^ologie - Centre National de fa Recherche Scientifique - Universite Montpellier II - 34095 Montpellier Cedex 5 , France

Soil radon concentration measurements are mostly performed in view to find precursors of volcanic eruptions and/or earthquakes. However it has been established for quite a time that several external and environmental parameters do affect the concentration of radon in the soil, regardless of any possible incumbent event. Thus, in order to ascertain the genuineness of a potential radon concentration anomaly, it is of the uttermost importance to previously gather as deep a knowledge as possible of the normal radon response of the area under survey. Furthermore, this will allow later on the making of appropriate corrections depending on the variation of the pertinent parameters. On the other hand, for obvious financial reasons it is unthinkable to cover a wide area with a dense network of detectors and to regularly retrieve and replace them. However a minimum number of baseline detectors can be determined by experimental means only.

In order to find out how to meet the above requirements at minimum cost, an extended survey was undertaken over an area located in central Mexico. It lasted for more than ten years. The variations of Radon concentration has been regularly recorded by means of SSNTD, together with those of the environmental parameters. In this paper the results are presented and analyzed. Seasonnal and yearly variations are sought as well as their correlation with the variations of the environmental parameters. Recommendations for the setting up of geophysical Radon networks are derived and proposed. AN AUTOMATIC ELECTRONIC COUNTER FOR SHORT TERM RADON MEASUREMENTS IN SOIL AND/OR WATER

J-P. MORIN, J-L SEIDEL, M. MONNIN Laboraloire d'Hydrogeologie - Centre National de la Recherche Scienttfique Universite Montpellier II - 34095 Montpellier Cedex 5 , France

SSNiD are widely used for performing radon concentration measurement surveys both in soi' and water. They offer well known numerous advantages. They also have their drawbacks. Particularly they do not allow to achieve short term measurements unless they are retrieved and replaced frequently. In this case, the measurement performed is not relevant because of the perturbation of the medium.

We have presented earlier a model according to which strong geophysical events such as earthquake or volcanic eruptions could be preceded by a short term but very strong radon anomaly. In order to gather evidence for the existence of such anomalies we have devised an electronic probe.

The present paper describes the probe in its various parts. Namely, the probe head containing a silicon diode detector, the associated electronics and the adquiring data processing unit and the storage unit. The storing device is a mobile credit card-like memory whose storage capacity at the moment is in the range up to 1300 different measurements. Data can be either transferred on the field directly on a laptop computer or later on at the laboratory tranferred in a computer by reading out the memory card.

The equipment has been set up on several different sites. We present the first radon burst we registered on a volcano and which happens to happen prioi to an eruption. A TRI-DIMENTIONAL MODEL FOR RADON TRANSPORT IN A POROUS MEDIUM

J-R MORIN. J-L SEIDEL, M. MONNIN Laboratoire d'Hydrogeologie - Centre National de la Recherche Scientifique - University Montpellier II - 34095 Montpellier Cedex 5, France

Radon motion in the Nature is a multiple parameter and complicated phenomenon. Its understanding can be attempted through experiments and via "in situ" surveys. However this approach is unlikely to bring up all the necessary knowledge because the intimate structure of the geological structure is largely unknown and the radon responds to simultaneous variations of several parameters which may be contradictory in their effect. One complementary, promising and versatile approach is the conception and use of numerical model.

A tri-dimentiona! simulating model for the radon transport process in a porous medium has been conceived, considering more complicated spatial phenomena as sideways diffusion, convection, moisture content, geological structure and fracturation.

The first step is solving the general steady state equation describing the concentration pattern in a 3 D homogeneous system. Secondly starting from the result of the previous step and using the finite differences method, one solves the same equation in the case of a non-homogeneous medium. Then in order to take into consideration the transport via a carrier, one solves the non stationna equation in a non homogenous medium.

Using this model one obtain the isoconcentration curves in a 31 structure. Several documented cases are presented, which illustrate relevai situations. PREDICTION OF SEASONAL RADON CONCENTRATIONS FROM WEEKLY SCREENING MEASUREMENTS

D. A22MI-GARAKAN1 Radiation Hygiene Division, Paul Scherrer Institute CH-5232 Villigen PSI, Switzerland

Short-term radon measurements were used to determine a correlation between weekly screening tests and seasonal concentration. The screening measurements v/ere made in an indoor environment over a period of one quarter and the results axe compared with the averaged radon level during that period. The results show that it is possible to derive a relationship between weekly radon concentration and that of a longer duration to predict the seasonal average radon level for an individual environment In these experiments two types of radon sampling devices were used and the statistical analysis of the results are presented. The samplers were envelope-type and plastic bag monitors for screening and long term radon concentration measurements, respectively. RESPONSE OF DIFFERENT PASSIVE DETECTORS IN A RADON CHAMBER

D. AZIMI-GARAKANI AND C. WERNU

Radiation Hygiene Division, Paul Schener Institute CH-5232 Villigen PSI, Switzerland

Two types of radon monitors, namely plastic bag and envelope-type, were exposed in the Paul Schcrrer Institute (PSI) radon calibration chamber as pan of an intercalibration of various radon detectors. The irradiations were performed at 20 °C and relative humidity of ~ 50% for three different radon exposure levels of approximately 900,450 and 40 kBqhnv3, respectively. The results are compared with those of the radon chamber Lucas oell monitoring system.. __Some experiment were carried out at 20 °C and relative humidity of 90% with the radon exposure level of about 135 kBqhnv3. When the relative humidity was increased from 50% to 90%, the response of the envelope-type radon monitor showed a decrease by a factor of 3.3 compared with that of the Lucas cell which was by a factor of 3.7. RADON MEASUREMENTS IN DWELLINGS

W. Birkholz1*, Th. Klink1*, H. Baumbach1*, D. Stiller2)

1) Technische Hochschule Leipzig, Germany 2) Bohrlochmessung GmbH Leipzig, Germany

Radon and its daughter products gain in importance in health protection and radiation safety. Especially in the thouthern region of Saxonia radon concentrations in dwellings may be high by former silver and uranium mines. We found radon contents of about 20.000 Bq/m in dwellings. To redevelope such houses it is necessary to know the intrude path of radon.

The aim of our work was to analyse the mean radon concentration in selected buildings over a long period and the search of the radon sources and radon intrude pathes. Good results for long time measurement give solid state nuclaer track detectors. We used calibrated ALTRACK detectors (CR- 39) in different configurations as screening detectors, diffusion chambers, and personal dosimeters. The results of this measurements were compared with those of other methods. SOIL RADON DOSIMETER FOR HOT HUMID TROPICAL REGION

Rosli H. Mahat Physics Department, University of Malaya 59100 Kuala Lumpur, Malaysia

A dosimeter for monitoring the level of radon gas in the soil has been developed for use under hot humid condition such as in Malaysia. It is a diffusion detector with solid-state nuclear track detector which record the alpha decay from the radon. Some of the problems during field measurement are high temperature, high humidity, heavy rainfall, flooding and interference from human and wild animals. Other consideration are low production and operational cost. RADON DOSIMETER: OPTIMIZATION OF GEOMETRICAL PARAMETERS FOR UNDERGROUND MEASUREMENTS

M. TufailJ Sikander M. MirzaJ I.E. Qureshi? H.A. Khan3 and A. A. Qureshi3

Centre for Nuclear Studies, P.O. N'iJore, Islamabad, Pakistan 2NPD, PINSTECH, P.O. Nilore, Islamabad, Pakistan 3SSNTD-Laboratory, NED, PINSTECH, P.O. Nilore, Islamabad, Pakistan

The passive measurements of the underground radon are performed with SSNTDs installed in a cylindrical tube which is buried in the subsoil. The dimensions of the tube play an important role to establish the sensitivity of the detection method. Therefore calculations have been made to find the optimum dimensions of the cylindrical container for the maximum sensitivity of radon and its daughter products. For an SSNTD installed inside the closed end of a cylindrical tube, the alpha track density varies with the diameter of the tube. Diameter of the tube has been optimized based upon the analytical calculations by using the numerical technique of Monte Carlo and verified by the experimental results. STUDY OF THE TWO-STEP ELECTROCHEMICAL ETCHING CONDITIONS APPLIED TO POLYCARBONATE DETECTORS USED IN RADON DIFFUSION CHAMBERS C. BaixerasW, E. Piesch<2>, B. Burgkhardt<2\ LI. Font, F. Fernandez*1* and C. Domingo*1) de les Radiations. Departament de Fisica. Universitat Autbnoma de Barcelona. E-08193 Bellaterra (Barcelona). Spain. WKemfoTscbungszentruTn Karlsruhe GmbH. Postfach 3640. D-T500 Karlsruhe. Germanv.

Alpha particles reaching the Makrofol DE plates in the KfK diffusion chamber , have energies greater than 3 MeV because of its small size. The two step ECE i i conditions have been optimized, in order to increase the alpha registration energy j range up to 5.4 MeV, for bare Makrofol DE plates as well as for plates covered with . a 2 fim thick Mylar foil. The study has been carried out for several values of the electric field strength, of the KGH concentration and of the etching duration. In order to obtain monoenergetic alpha particles in the energy range from 2.5 MeV to 5.4 MeV, Makrofol DE plates have been irradiated using an 241Am source, varying the air pressure between the source and the plates with a vacuum device. The optimum etching conditions have been selected considering the registration of high energy alpha particles and the background levels. MEASUREMENTS OF RADON LEVELS USING CSR DETECTOR IN HAREIN AND YAN'AN

Shi Jinhua Chen Changhua Environmental Protection Institute of Environmental Bureau, ..Wuhan Protection, Wuhan

Abstract -— Measurements were made of indoor and outdoor radon levels in two cities, Karbin and Yan't.n, in China using CSR detector, and potential alpha energy and equilibrium factor, F, was determined with balloon method at some main measuring points. The analysis and comparison of the results of these measurements were made. The measurements with CSR detectors indicate that the indoor radon concentration ranges from 16 to 144 Bg/a3 with an average of-73 Bg/m3 in Harbin, and from 13 to 78 Eq/ns3 with an average of 35 Bo/m3 in Van'an respectively, the comparison of these results gained with the tvo methods shows that the results are consistent within a deviation of 40%, DETERMINATION OF INDOOR AND OUTDOOR CONCENTRATIONS OF RADON AND ITS DAUGHTERS USING CSR DETECTOR

Zhang zhengguo Zhang Liang Li Chunxiu Bunan Central Environmental Monitoring Station, China

Abstract — The annual mean values of indoor and outdoor concentrations of radon and its decay products were j determined, with a total sample number of 224, using CSR measurements for typical cinder-brick buildings in Hunan province in China and for residential quarters surrounding the coal mines and uranium mines in radium bearing zones.

The annual mean concentrations of indoor radon were found to be 15.6 Bq ra"J for ordinary buildings and 2S.5, 31.6 and 71.1 Bq m"3 for the houses made of 3 kinds of cinder bricks respectively. The values of indoor radon concentrations in residential quarters around a coal nine including its power plant and near two uranium mines were estimated to be 36.1, 43.8 and 85.6 Bq m"3 respectively.

The outdoor radon concentration, decreasing with height, is found to be 1.6 times higher at h-1.5 m than at h = 3 in. Indoor radon concentrations at different locations even inside the same house are also founded to be different: the value of radon concentration at the end position of bed near wall is the highest, being 1.6 and 2.9 times higher than those under the ceiling under both non-ventilation and ventilation conditions respectively. Equilibrium factor of radon daughters determined using accumulative measurements are 0.55 indoors and 0.70 outdoors respectively. The total sum of annual effective dose incurred by the local habitants is 1.6 mSv, of which 1.1 i&Sv is from the inhalation of radon daughters, being 2.2 times that of gamma external exposure. Additional annual effective dose equivalent received by the residents living in the cinder-brick buildings is estimated at 2,6 mSv, being 2 times that of gamma external exposure, 0.5 mSv. Additional collective effective dose equivalents from 14 cinder brickfields and 24 stone-coal-cinder brickyards are 52 and 411 man.Sv respectively every year since their foundation. RANDON DISTRIBUTION MEASUREMENT OF LUGO COALMINE BY CSR TECHNIQUE

sun ZHONGTIAN, pan XIANJIA and hu GUOJU Physics Department, Zhengzhou University. P. R. China 450052

ABSTRACT

We discuss the relationship between the Alpha radioactivity derived from Uranium anci thorium natural radioactive systems, especially from Randon and the safe production in coalmine region. The Alpha radioactive distributions of different sites were detected and measured by using CSR technique in LUGO Coalmine which is typical medial coalmine with 1 /A Kilometer main lane deepness and 11 X 10s Tons Production per year, So, the Randon distribution can be deduced. A discussion of the Randon concentrations of different sites, different productive conditions, different deeps and safe production conditions is given in coalmine region. Measurement shows that the Randon concentration under the g;ound is less than that on the ground under today's productive condition in a large area in Henan LUGO coalmine. (See Table 1 and Fig. 1) Table 1. (part)

Sampling date Sample number Number of track Structure type March 23, 286 19 Room on the ground 1S92. 300 38 Office on the ground 287 898±6 End of mine lane 288 M2 Electromotor Room 290 833±5 West transformer "12" Room 298 112 East transformer "12" Room

-•*--*[

f. Fig. 1 Patterns of track for No. 287. 288. THE EFFECT OF USING WATER IN A TOILET ON INDOOR RADON LEVEL

ZHAI PENGJI Institute of High Energy Physics, Academia Sinica, Beijing 100080, PRC . • ZHAO YUNLONG Beijing Institute of Uranium Geology, Beijing 1G0029, PRC

In this work plastic and small columnar glass(^ 35x30) cup *2*Rn monitoring dosemeters and CR-39 detectors were used. During normal using water of a water tank in a toilet without window, a building located in Zhongguancun district in Beijing, the effect of separated out Rn on indoor radon level was surveyed. Those Rn monitoring dosemeters were kept in the water tank, below lid of the water tank, on the lid, bedroom and balcony for two-month, four to five-month. The ratio of *a*Rn level in various monitoring section is in water tank : below lid : on lid : bedroom : balcony=300 : 5 : 1 : 0.4-0.8 : 0.2-0.3. The concentrations are 98.3Bq.m~3 in air of the tank, 19.9Eq.m~* in air above the tank, 8.8(summer) and 15.0Bq.nT* (autumn) in air of the bedroom, 4.7(summer) and 6.4Bcj-m-* (autumn) in air of the balcony respectively. This level is consistent with that determined simultaneously in indoor and outdoor of a official building located in the same district of distance long more than lkm. COMPARISON OF RADON MEASURING INSTRUMENTS OF CHINESE MAKE WITH OP JAPANESE MAKE IN XI' AN

Fan Xin (Shaanxi Provincial Antiepidemic Station,Xi' an, 710054)

Abstract: Eadoa concentration of Xir an in 1986 to 1987 measured by FDT-S4+FD-301S radon measuring instrument have been compared with radon concentration of Xif an from Nov. 1988 to Feb.1990 measured by 20 Bets ERMl5-1/1 type Rn-222 electrostatic integral detectors of solid- state nuclear track of Nagoya University, and result devi- ated in about 0.8-4.0% higher of radon concentration outdoor and about 6.3% lower of radon concentration indoor by the instrummenmt of Chinese make, average devitation is about± 4. 7%, which shows the well coincidence. In addition, from the integral measurement made by the instrument of Japanese make, have obtained the variational law of radon concentration in height of Xir an outdoor , the ratio of indoor with outdoor in Xi' an is about 2 times which follows the foreign reports.

Key Words:radon concentration, falloon-method, solid- state nuclear trsek detector, comparison. A SMALL PASSIVE MONITOR FOR RADON WITH CR-39(DAP)

Pang Deling Li Landi Zhu bing Institute of Radiation Medicine, Shanghai Medical University

Shanghai, 200032, P R Chna

The design is optimized for sensitivity asd easy to use. The response of radon diffusion chambers of several ten cubic centimetre volume have been determined by experiment. The best choice for the size of the cylinderical chamber ie that the ratio of diameter and height is 1. A CSR-II type of environment radon monitor, which makes use of CR-39(DAP) inside a 20cma diffusion chamber has been developed. With chemical etching and counting in a single field up to 3cm3 size, mean radon concentrations of at least 2Bq/m3 can be measured after accumulation periods of 3 months. Experience in field use showed that moisture collection on the surface of the SSNTD was practically avoided, even under unfavorable weaather conditions during exposure. A NON-CONSTANT CONCENTRATION RADON CALIBRATION CHAMBER

Pang Deling Li Landi Zhu bing Institute of Radiation Medicine, Shanghai Medical University

Shanghai, 200032, P R China

The paper introduces a non-constant concentration radon calibration chamber. According to the basic principle, radioactive decay law, a calibration chamber was designed. Experiments of calibration were carried out, It has been domonstr- ated that the response is stable to within +-10% for exposure periods of three days. The radon calibration chamber is low cast, passive, unatteneded operation, and is easity constructed from inexpensive and commercially available materials. m APPLICATION OF CR-JJ SOLID STATE RLEII TRACK DETETORS 10 RADON SURVEY IN JBE MAIN CITIES OF INKER KONOOLIA

Slsen Bao-aing, Chen Rui-hna, Wsng Qisg-zfci (Inner Nonjjolia Institute of Radiological Health and Protectioii,Kuhhot)

In the prriod of I, mi to (,|))l,Vt used the SSNTD (SY-1, CR-39) produced by Peking Institute of Am icheaical to survey the accuaulative density cf Radon indoor,outdoor and in the baseeerl in the sain cities of the Inner Mongolia .They are Huhhot,Baotou , Chifeng ,Kanchuria, Vnhai ,Linhe,Bayanhot .We surveyed 45 rooas,4 fields ,1] baseaents within 3 to 5 aonlhs.Aaoog the rest,the houses surveyed in Manchuria are ell Kussion or Japanese designs ttnniUr! houses or stone.There is a basearat in the rooi for that Teason. The density of Radon indoor is relatively high.Therefore,Manchuria is a special region .It isn' t closen to jo'in the average.The averages of the density of Ration indoors and outdoors are 33.0±10.H3a)Bqa~*cThe figure in the brakets is the figure of the sasple) and I.1±1.«(4)Bqa'*.The averages of Radon density the building, erne-storey and in the basraenl are 24. 0± 12. ii 17)Bq« *, 40.3±24.5Bqa'and 42. »± ». 3( lDBqa" rtsnectively .The average of indcor Radon density in t onr-storey houses of Manchuiia is H1.7+ l.3Bqa"*.So the btseasnt is an iaportance structual reason that aake underground soil 51s indoors produce leakage effect .Indoor-Radon density is acre higher with baseaenl than without baseaerit INDOOR RADON MEASURED VITH NUCLEAR TRACK DETECTORS AND CHARCOAL CANISTERS IN HONG KONG

Luo Dating and Zhang Chunxiang (Zhongshan University. Guangzhou, P R China)

ECU Young and K H Yu (City Polytechnic of Hong Kong, Kovloon, Hong Kong)

The screening ieasureients of indoor radon concentration were carried out during the period froi July to October 1990 by means of the passive activated charcoal device at a total of 160 sets in various buildings in different areqs of Hong Kong. The standardised charcoal canisters and the EERF standard operating procedure recouended by the EPA of United States were used. After the end of the 2 to 3 days exposure, the detectors were returned to laboratory for analysis. The aiount of radon absorbed on the carbon device was detenined by counting the gaua rays of radon progeny in equilibrium with radon. It is obtained that the arithnetic lean of the Measured indoor radon concentrations is equal to 40.0 Bq/i3. Based on above experiments, CR-39 nuclear track detectors were used to measure the average radon concentrations over a period of three •onths ( Feb. to April 1991 ) in a total 71 survey sites selected froi dwellings and working places in different areas in Hong Kong. The CR-39 detector we used has a mean sensitivity of 1.83 track.ci^kBq"1.*^"1. Chemical etching ( 6.25N KOH for 8h at 70 t) and optical microscopy are used for track visualization and counting. The normal distributions have been obtained froi measured results. The arithmetic means of the indoor average radon concentrations in dwellings and working places were found to be 72.2 Bq/i3 and 155.4Bq/i3 respectively. Meanwhile, the arithmetic means of gaua radiation doserates in dwellings and working places were determined to be 216.0 nGy/h and 200.4 nGy/h respectively by LiF-TLDs placed on each sites with CR-39 detectors together. FILTERS AND MATERIAL SCIENCES APPLICATION OF THE PRE-SOAKING EFFECTS TO THE PRODUCTION OF CR-39 MICROFILTERS

K. Ogura, T. Naito*. K. Nakano** and T. Takahashi** College of Industrial Technology, Nihon University 1-2-1 Izumi-cho, Narashino, Chiba 275, Japan ^Industrial Research Institute of Niigata Prefecture 1-11-1 Abuipinishi, Niigata-shi, niigata 950, Japan **The Institute of Physical and Chemical Research 2-1 Hirosawa, Wako, Saitama 351-01, Japan Pre-soaking is a process during which an exposed track detector is soaked in a liquid chemicals for a few hours just before etching. The pre-soaking in HCB(hexachloro butadiene) significantly improves the track sensitivity(Vj/Vg) and the etched-surface quality as well as the sharpness of the etched track edge of CR-39 *). These pre-soaking effects have been applied to the production of CR-39 microfliters. CR-39 stacks were irradiated with 88 NeV/n Ar ions. From the irradiated stacks, the sheets of about 200 um thick were used in which the Ar ions have a remaining energy of approximately 30 MeV/n or 20 MeV/n. Samples were pre-soaked in HCB at 70cC for 3 hours and subsequently etched in 10 N KOH solution at 90cC for 20 minutes. The results show that the pre-soaking in HCB is very useful procedure to produce the nuclear pores when Vj/Vg of the irradiated ions is not high enough for the purpose of microfilter production. The pore geometries of CR-39 nuclear track nicrofilters inspected by scanning electron microscope and optical microscope as well as pre-soaking and etching condition will be presented.

1) K. Ogura (1991) Nucl. Tracks Radiat. Meas., Vol. 19, Nos 1-4, pp. 197-202. DEVELOPMENT AND CHARACTERIZATION OF POLYCARBONATE MICROFILTERS

Maushumi Dey, Jolly Raju, Swarnali Ghosh and K.K. Dwivedi Department of Chemistry Nortk-Eastern Hill University, Shillong-793 003, India.

Nuclear track microfilters have a wide applicability in Biological, Environmental and Chemical Sciences. The nuclear track technique provides a unique tool for the production of such micropore filters with statistically distributed uniform tracks of desired diameter, length and area! density. In this report, we present our work on the development of 100 pm thick microfilters from Makrofol-N films with pore size between 2 nm to 6 Mm and their characterization by using them in aerosol collection and in purifying natural water. Makrofol-N films (102 pm) were exposed to 16.3 MeV/u ^U ions at UNflLAC, GSI, Darmstadt. The irradiated foils were etched in 3N NaOH at 55CC for different durations in order to develop micro-holes of desired diameters. The etched pores were observed under an optical microscope and also with scanning electron microscope. The diameters of about 50 pores were measured in each microfilter and the most probable outer (surface) pore diameters (D) were found to be 2.6 pm, 4.0 i

In order to characterize these filters for their applications in aerosol collection and in purifying natural water, we have used these filters to collect air participates from work room atmosphere and filtered 3 samples of natural water from streams. The performance of these filters was evaluated in terms of filtration rate and throughput. THERMAL STABILITY OF PORES IN NUCLEAR TRACK MICROFILTERS

G. HDSSAIS1, H.A. KHAN1.and M.S. ZAFAR2

1. SSNTD-Laboratory, NED, PINSTECH, P.O. Nilore Islamabad, PAKISTAN 2. Physics Department, Punjab University New Campus, Lahore, PAKISTAN

Abstract: CN-85 cellulose nitrate track detectors irradiated with 252 Cf in 21T geometry, had undergone post-irradiaticn thermal annealing and ultraviolet treatments, separately. Diametric measurements of the etched "through holes" have been made. Profiles of the pores affected by the post irradiation treatments have been studied. Thermal annealing of the detectors at 98°C produces "through holes" of uniform size and relatively of smaller dimensions as compared to the unannealed and U.V. treated filters. Activation energy of annealing has been found to be 0.12 + 0.01 eV. For poster presentation:

APPLICATION OF PARTICLE TRACK MEMBRANES IN SOLVENT RECOVERY

B. Gemende1, E. Heinrich1 and U. Wehlmenn3 . ; * Centre o-f Reseer-crri Rossendor-f, Germany = Research InEtiti_rr= -for Leather Industry, Freiberg, Germany

The ever growing c-wand -for technologies which produces no or only a limited epount of waste requires a new approach in developing new anc reconstructing old production lines. This is especially true -for the chemical, dye and textile industries. One problem there is e.g. the handling o-f used solvents, which are c-?ten hazardous -for health and environment.

In this presentatlc-r» results are given -for separating used sol vent—dye-mix tures -from the leather industry by Particle Track Membranes ?) both in dead—end and cross -flow nsicro- •f ij tration. These results demonstrate the promising possibility o-f recycling <= great amount o-f solvent.

•he used RoTracTr ? »M from polyether had a good rejection characteristic tcc=nher with high chemical resistivity. Only solvent -fluxes we^e• rather low and decreased steadily with time,. However a-fr.e-' an easy cleaning procedure the -fluxes reached almost ths- same values as -for new membranes. A cc«m- parison with othe-~ competitive membranes showed no -flux eci- vantage for eithe--. 5ut these couldnxt be as easy cleaned as ABSTCACT

Assessment of SSM'i) technique for Quantitative estimation of UO

natural UO o-ThOn mixed oxide pellets incomparison to X-rav flouorescence.alpha and gamma ———— s s. — r - r - —

sectromeirv.

+ + B.B.Shriwastwa*)J.K.Ghosh*,D.R.Bende ,M.C.Abani and B.Raghunath +

* Radio Metallurgy Division.Bhabha Atomic Research Ccntre,Trombay,Bombay-400085,India

-I- Radiation Safety Systems Division.Bhabha Atomic Research Centre.Trombay,Bombay-400085,

India

Quantitative estimationof thorium and uranium in sintered pellets is difficult by normal chemical dissolution or redox titration method.Though there are other methods available for estimation of thoria,tbey are not commonly used due to their complexity .An attempt has been made to compare the performance of solid track nuclear track detectors in the quantitative estimation with respect to other nondestructive techniques like XRF analysis, alpha and gamma spectrometry.Eight groups of sintered UO 2/ThO 2 pellets of different compositions were fabricated for the comparitive studies.Pretrcated,alpha sensitive CR-39 plastic detector film is used for alpharadiography,surface barrier detectors for alpha spectrometry and Nal crystal for gamma spectrometry.Preliminary results indicate alpbaradiography can be a quick technique for predicting the composition within 2% accuracy by proper optimisation of th* Parameters like detector.time of irradiation .etching condition and accuracy of the microdensitometer scanner.Results are in close comparison with XRF, where as alpha spectrometry gave erroneous results due to degradation of alpha energy within the pellets.Gamma spectrometry requires long counting intervals and complex calculations. OK THE ADHERENCE OP THE UHAHIUM TO THE WALLS OP THE SOLUTION VESSELS Ana DAMS Institute of Physics end Nuclear Engineering, Bucharest

It is well known there is an interaction between the elements of a chemical compound and the wall of the vessel in which. ?.ts solution is kept. In the authors'opinion an important interaction is the adherence of the elements to the wall because this adherence can be responsible for some changes in the behaviour in time of the solution. The authors tried to find a correlation between the uranium adherence and the appearance and evolution of its radiocolloidal and pseudoradiocolloidel state. Such investigations require high quality analysis. For this reason, the authors used the uranium track micromspping technique. Three materials currently used to make the vessels were investigated: plastic polyethylene, brown glass and light transparent glass. Por each material a lot of pieces were introduced into the same uranium solution. Time by time, for 834 days, parts of these pieces were analysed by the track technique. In order to put into evidence the way of the adherence, ebsorbtion and/or adsorption, the following treatments have been applied to samples from each material before their analysis:cotton-wool wipe, distilled water wesh or concentrated HNO3 wash. The experimental data le d us to conclude: 1. The edherence of uranium on the wall of the vessel consists of both ebsorbtion and adsorption; 2. Any impurities into material, as well as the surface scrapes can be responsible for the appearance and evolution of the uranium pseudoradiocolloidal state; 3. The brown gless is the best meterisl for keeping the uranium solutions, never the plastic vessel will be used to keep the calibrated uranium solution. SIMULATION OF A THERMOLUMINISCENT CaSO4:Dy DOSEMETER FOR BETA RADIATION DETECTION E. Luguera«1*, F. Fernandez«», I. Al-Khatib«1), C. Baixeras«», C. Domingo«1) and H. Serviere«2) WFisica de les Radiacions. Dep&rtament de Fxsica. Universität Autönoma de Barcelona. E-08193 Bellaterra (Barcelona). Spain. M Centre d'Electronique de Montpellier (UA 391). Université des Sciences et Techniques du Languedoc. Place E. Bataillon. F-34095 Montpellier Cedex 5. France.

This paper describes an application of the EGS4 Monte Carlo code in order to simulate an optimum CaSO4:Dy dosemeter for beta radiation detection. The performance of the code is illustrated with results obtained for different dosemeter configurations (thickness, size, support layer) and irradiation conditions. The resuus suggest that the method would be very usefull in order to define the best possible configuration and conditions for carrying out personnel beta dosimetry. PREPARATION AND CHARACTERISTICS OF A CaSO4:Dy THERMOLUMINISCENT DOSEMETER F. Fernandez*1', E. LugueraW, H. PrevostW, C. Baixeras»'1) and C. Domingo*1) WFisica de les Radiacions. Departament de Fisica. Universität Autônoma de Barcelona. E-08193 Beilaierra (Barcelona). Spain. (2) Centre d'Electronique de Montpellier (VA 391). Université des Sciences et Techniques du Languedoc. Place E. Bataillon. F-34095 Montpellier Cedex 5. France.

We have used a method similar to the one suggested by Yamashita for the preparation of thermolumiscent material. The dosimetric properties of CaSO<:Dy powder have been tested varying the dopant concentration and the thermal treatment. Results of the linearity, fading and sensitivity characteristics of a phos^ui piepared with Mei Jv CaS04-2H20, dopped with 0.1 mo!% of dysprosium, are presented.. A NEW NUCLEAR TRACK MICROPOROUS MEMBRANE

Wu, Risheng

(Institute of.High Energy Physics, Academia Sinica)

The traditional Nuclear Track Microporous Membrane is made of polycarbonate irradiated in nuclear reactors or accelerators, and then pores are formed from chemical etching. The cost of irradiation in reactors and accelerators is so high that the price of Nuclear Track microporous membrane is difficult to decrease. Although it has homogeneous aperture, its porosity can be regulated conveniently and it is superior to other membranes in not a little application, its applications are confined due to its higher price than other membranes after all. In addition, there remains trace radioactivity in nuclear microporous membrane, so it is hard to say there is no environmental pollution at all. In order to eliminate the above-mentioned problems, a new nuclear track microporous membrane is designed. Poly- carbonate film is exposed to 0?-particles from y( source, and then after fine chemical process the pores are formed. In this way, the cost of the new membrane is greatly reduced to that of the stretched polypropylene membrane. What is more, there is no radioactive contamination at all and some of its property is superior to the traditional nuclear track microporous membranes. New nuclear track microporous membranes of the apertures 0.2 - 4^im have been made, and some of their applications have been studied in Controlled Release, e.g. transdermal therapeutic system of clonidine, classifier, filter etc. THEORETICAL CALCULATIONS AM) MOXTE CARLO SIMULATIONS OF MULTIPLE HOLE PROBABILITIES FOR ETCHED NUCLEAB TRACKS

Yu-Lan Wang. Turn-Cheng Zhu Institute of Atomic Energy, P.O.Box 275(94), Beijing 102413, CHINA

Statistical properties of inner and outer holes distribution in nuclear track membrane are investigated by analytical calculations and Monte Carlo computer simulations. Analytical expressions for the effective porosity and the probability of forming single, double and multiple holes are given as a function of the nominal porosity , and a computer simulations is presented in the paper. AUTOMATED IMAGING SYSTEM FOR ETCHED TRACK COUNTING

Luo Yisheng * Tao Deyuan * * He Xiaohai * * ZhaoYing" Chen EH* 'Beijing Institute of Radiation Medicine, Beijing, China * *Si Chuan University, Chengdu, China