DOCSLIB.ORG

Thermal and Resonance Neutrons Generated by Various Electron and X-Ray Therapeutic Beams from Medical Linacs Installed in Polish

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Thermal and Resonance Neutrons Generated by Various Electron and X-Ray Therapeutic Beams from Medical Linacs Installed in Polish reports of practical oncology and radiotherapy 1 7 ( 2 0 1 2 ) 339–346 View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Available online at www.sciencedirect.com jou rnal homepage: http://www.elsevier.com/locate/rpor Thermal and resonance neutrons generated by various electron and X-ray therapeutic beams from medical linacs installed in polish oncological centers a,∗ b a,d c b Adam Konefał , Andrzej Orlef , Marcin Łaciak , Aleksander Ciba , Marek Szewczuk a Department of Nuclear Physics and its Applications, Institute of Physics, Silesian University, Katowice, Poland b Department of Medical Physics, Center of Oncology, Gliwice Branch, Gliwice, Poland c Radiotherapy Department of the Stanisław Leszczynski´ Memorial Hospital, Katowice, Poland d Institute of Occupational Medicine and Environmental Health, Sosnowiec, Poland a r t i c l e i n f o a b s t r a c t Article history: Background: High-energy photon and electron therapeutic beams generated in medical lin- Received 5 October 2011 ear accelerators can cause the electronuclear and photonuclear reactions in which neutrons Received in revised form with a broad energy spectrum are produced. A low-energy component of this neutron radi- 24 April 2012 ation induces simple capture reactions from which various radioisotopes originate and in Accepted 14 June 2012 which the radioactivity of a linac head and various objects in the treatment room appear. Aim: The aim of this paper is to present the results of the thermal/resonance neutron flu- Keywords: ence measurements during therapeutic beam emission and exemplary spectra of gamma Thermal/resonance neutrons radiation emitted by medical linac components activated in neutron reactions for four X- Induce radioactivity ray beams and for four electron beams generated by various manufacturers’ accelerators Medical linacs installed in typical concrete bunkers in Polish oncological centers. Materials and methods: The measurements of neutron fluence were performed with the use of the induced activity method, whereas the spectra of gamma radiation from decays of the resulting radioisotopes were measured by means of a portable high-purity germanium detector set for field spectroscopy. Results: The fluence of thermal neutrons as well as resonance neutrons connected with ∼ 6 2 the emission of a 20 MV X-ray beam is 10 neutrons/cm per 1 Gy of a dose in water at a reference depth. It is about one order of magnitude greater than that for the 15 MV X-ray beams and about two orders of magnitude greater than for the 18–22 MeV electron beams regardless of the type of an accelerator. Conclusion: The thermal as well as resonance neutron fluence depends strongly on the type and the nominal potential of a therapeutic beam. It is greater for X-ray beams than for elec- trons. The accelerator accessories and other large objects should not be stored in a treatment room during high-energy therapeutic beam emission to avoid their activation caused by thermal and resonance neutrons. Half-lives of the radioisotopes originating from the simple capture reaction (n,) (from minutes to hours) are long enough to accumulate radioactivity of components of the accelerator head. The radiation emitted by induced radioisotopes causes the additional doses to staff operating the accelerators. © 2012 Greater Poland Cancer Centre. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved. ∗ Corresponding author. Tel.: +48 503830026. E-mail address: [email protected] (A. Konefał). 1507-1367/$ – see front matter © 2012 Greater Poland Cancer Centre. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved. http://dx.doi.org/10.1016/j.rpor.2012.06.004 340 reports of practical oncology and radiotherapy 1 7 ( 2 0 1 2 ) 339–346 1. Background High-energy photons and electrons used in radiotherapy can cause nuclear reactions (i.e. electronuclear and photonuclear 1–4 reactions ) in which neutron radiation is produced. This 5–19 problem was investigated by many authors. The resulting neutrons have a broad energy spectrum with mean energy 5–9 of several hundred keV. Significant contribution to the 10–12 spectrum is given by thermal and resonance neutrons. These low-energy neutrons come into being as a result of a slow-down processes (elastic scattering, mainly) of neutrons produced in the above mentioned reactions. The neutrons are slowed down mainly in walls, floor and ceiling of a treatment facility. The thermal and resonance neutrons can cause simple capture reactions from which various radioisotopes originate Fig. 1 – The view of the detection system with a high-purity and in which the radioactivity of air, linac head and vari- germanium detector by ORTEC (1 – the aluminum shield of ous objects in the treatment room appear. The main sources the germanium crystal, 2 – container with liquid nitrogen, 3 13 of neutrons are large components of linac head i.e. colli- – electronic modules – multichannel analyzer, amplifier, mators of the beam, a flattening filter, a target in the case etc., 4 – laptop). of X-ray beams and, additionally, scattered foils instead of a flattening filter in the case of electron beams. The resulting 8 neutrons can travel through a treatment room and a maze. of a circle with the radius of 0.75 cm. The foil superficial den- Thus, simple capture reactions can take place in the whole 2 115 sity was in the range from 98 to 110 mg/cm . Isotope In treatment facility. A comprehensive knowledge of the nuclear 22 is characterized by a relatively high cross section of 160 b reactions and radioisotopes induced during emission of ther- for a simple thermal neutron capture reaction. It also has a apeutic beams generated by medical linacs was presented in 23 14–21 high resonance of about 28,000 b at 1.45 eV and a number many papers. of lower resonances in the 3.5 eV to 1 keV range for the above- mentioned reaction, yielding the resonance activation integral 24 of 2700 b. 2. Aim The measurement of the thermal/resonance fluence consisted of two stages. In the first stage, the indium foil was The main aim of this paper is to present the results of mea- placed at a chosen location in the neutron field induced by a surements of the thermal and resonance neutron fluence in therapeutic beam inside a treatment room. The indium foil the vicinity of a medical linac during emission of various high- was activated by a capture of neutrons. The thermal and reso- energy therapeutic beams. Additionally, exemplary spectra of nance neutrons activate the indium according to the following gamma radiation emitted by medical linac components acti- reaction: vated in neutron reactions are shown. The purpose of this part of the study was to identify gamma emitters induced in 115 1 116m + n → , T = . In 0 In (unstable half-life 1/2 54 21 m) neutron reactions in linac accessory during emission of high- 49 49 energy photon/electron therapeutic beams. The presented 116m followed by radioactive decay. The unstable state In disin- investigations were carried out for four various therapeutic − 116 ˇ tegrates by decay into the exited state Sn*. Deexcitation electron beams and for four X-ray beams generated by three of this state gives gammas. In the second stage, the activated various manufacturers’ medical linacs installed in typical con- foil was removed to the operator room after the therapeutic crete bunkers in three Polish oncological centers: the Center beam emission and it was located on the surface of the germa- of Oncology in Gliwice, the Stanisław Leszczynski´ Memorial nium detector shield to measure the indium foil activity. In the Hospital in Katowice and the Greater Poland Cancer Centre in presented investigation, the detection system with the high- Poznan.´ purity germanium detector by ORTEC (Fig. 1) was applied to measure the activity of the foil on the basis of a measurement 3. Materials and methods of a spectrum of gammas emitted by the activated indium. In the presented investigation, the foil activity was determined 3.1. Measurements of the thermal and resonance by a net count area NCA of the peak at 1293.54 keV (Fig. 3), using neutron fluence the calibration factor K. The factor K was defined as a ratio of 60 the activity of the calibration source Co to net count area of The measurements of the thermal and resonance neutron the peak at 1332.50 keV in the gamma energy spectrum emit- 60 fluence were performed with the use of the induced activ- ted by the Co source used for the calibration. The energy ity method. This method uses the dependence between the of 1332.50 keV is close to 1293.54 keV from gammas emitted indium foil activity caused by thermal/resonance neutrons by the activated indium foil. The calibration source was in the and the thermal/resonance neutron fluence. The neutron acti- same shape and it had the same surface as the applied indium 115 vation detectors were indium foils ( In isotope) in the shape foils. reports of practical oncology and radiotherapy 1 7 ( 2 0 1 2 ) 339–346 341 The cadmium cover method was applied to separate the thermal neutron fluence and the resonance neutron fluence. Each measurement of the neutron fluence was performed twice: first by the use of the indium foil placed in a 1 mm thick cadmium shield, and then after the decay of the excited nuclei but without the shield. The cadmium shield absorbs almost all thermal neutrons but it lets through most of resonance ones. Thus, the total activity of the indium foil covered by cadmium is induced by resonance neutrons. However, a part of the resonance neutrons is absorbed in the cadmium layer.
Load more

Recommended publications
  • The Radiochemistry of Tungsten
    National Academy of Sciences !National Research Council NUCLEAR SCIENCE SERIES The Radiochemistry of Tungsten — ...—- L. F. C URTISS,Chairman ROBLEY D. EVANS, Vice Chairman NationalBureau ofStandards MassachusettsInstituteofTechnology J.A. DeJUREN, Secretary WestinghouseElectricCorporation C. J.BORKOWSKI J.W. IRVINE,JR. Oak RidgeNationalLaboratory MassachusettsI&tituteofTechnology ROBERT G. COCHRAN E. D. KLEMA Texas Agriculturaland Mechanical NorthwesternUniversity College W. WAYNE MEINKE SAMUEL EPSTEIN UniversityofMichigan CaliforniaInstituteofTechnology J.J.NICKSON Memorial Hospital,New York U. FANO NationalBureau ofStandards ROBERT L. PLATZMAN Laboratoirede Chimie Physique HERBERT GOLDSTEIN NuclearDevelopmentCorporationof D. M. VAN PATTER America BartolResearch Foundation LIAISON MEMBERS PAUL C. AEBERSOLD CHARLES K. REED Atomic Energy Commission U. S.Air Force J.HOWARD McMILLEN WILLIAM E. WRIGHT NationalScienceFoundation OfficeofNavalResearch SUBCOMMITTEE ON RADIOCHEMISTRY W. WAYNE MEINKE, Chai~man HAROLD KIRBY UniversityofMichigan Mound Laboratory GREGORY R. CHOPPIN GEORGE LEDDICOTTE FloridaStateUniversity Oak RidgeNationalLaboratory GEORGE A. COWAN JULIAN NIELSEN Los Alamos ScientificLaboratory HanfordLaboratories ARTHUR W. FAIRHALL ELLIS P. STEINBERG UniversityofWashington Argonne NationalLaboratory JEROME HUDIS PETER C. STEVENSON BrookhavenNationalLaboratory UniversityofCalifornia(Livermore) EARL HYDE LEO YAFFE UniversityofC slifornia(Berkeley) McGillUniversity CONSULTANTS NATHAN BALLOU JAMES DeVOE NavalRadiologicalDefenseLaboratory
    [Show full text]
  • Creation and Nuclear Reaction Studies Sorption Behaviour of Short
    PL9601122 PL9601121 High-Spin Nuclear Target of 178m2Hf: Creation and Nuclear Reaction Studies Yu. Ts. Oganesian1, S.A. Karamian1, Yu. P. Gangrsky1, B. Gorski1, B.N. Markov1, Z. Szeglowski2, Ch. Briangon3, O. Constantinescu3, M. Hussonnois3, J. Pinard3, R. Kulessa4, H.J. Wollersheim4, G. Graw5, J. de Boer5, G. Huber6 and H.V. Muradian7 XFLNR, JINR Dubna, Russia; 2H. Niewodniczanski Institute Nuclear Physics, Krakow, Poland; 3CSNSM, IPN, Orsay, France; 4GSI, Darmstadt, Germany; 6Miinchen University, Germany; 6Mainz University, Germany; 7Kurchatov Institute, Moscow, Russia. Investigations of the hafnium-178 isomers are a new scientific direction promising the devel- opment of a fundamental knowledge both in the field of the nuclear structure and of nuclear reactions. The completed experiments give grounds for hope of obtaining data on the electro- magnetic moments, on the mean radius and the deformation of the 178Hf nucleus in the state 16+, on the wave function structure of this state, as well as to study the influence of the target high spin on the differential cross sections of nuclear reactions, to find and investigate neutron resonances with a high spin, to obtain direct information on the density of the levels in the earlier inaccessible region of the spin and of the excitation energy, to measure directly the parameters of a giant dipole resonance based on the high spin state and to clarify in detail the role of the structure hindrances in nuclear reactions. Sorption Behaviour of Short-Lived W and Hf Isotopes on Ion Exchangers from HC1/HF Solutions in Fast On-Line Experiments D. Schumann1, R. Dressier1, S. Fischer1, St.
    [Show full text]
  • Metastable Non-Nucleonic States of Nuclear Matter: Phenomenology
    Physical Science International Journal 15(2): 1-25, 2017; Article no.PSIJ.34889 ISSN: 2348-0130 Metastable Non-Nucleonic States of Nuclear Matter: Phenomenology Timashev Serge 1,2* 1Karpov Institute of Physical Chemistry, Moscow, Russia. 2National Research Nuclear University MEPhI, Moscow, Russia. Author’s contribution The sole author designed, analyzed and interpreted and prepared the manuscript. Article Information DOI: 10.9734/PSIJ/2017/34889 Editor(s): (1) Prof. Yang-Hui He, Professor of Mathematics, City University London, UK And Chang-Jiang Chair Professor in Physics and Qian-Ren Scholar, Nan Kai University, China & Tutor and Quondam-Socius in Mathematics, Merton College, University of Oxford, UK. (2) Roberto Oscar Aquilano, School of Exact Science, National University of Rosario (UNR),Rosario, Physics Institute (IFIR)(CONICET-UNR), Argentina. Reviewers: (1) Alejandro Gutiérrez-Rodríguez, Universidad Autónoma de Zacatecas, Mexico. (2) Arun Goyal, Delhi University, India. (3) Stanislav Fisenko, Moscow State Linguistic University, Russia. Complete Peer review History: http://www.sciencedomain.org/review-history/20031 Received 17 th June 2017 Accepted 8th July 2017 Original Research Article th Published 13 July 2017 ABSTRACT A hypothesis of the existence of metastable states for nuclear matter with a locally shaken-up nucleonic structure of the nucleus, was proposed earlier. Such states are initiated by inelastic scattering of electrons by nuclei along the path of weak nuclear interaction. The relaxation of such nuclei is also determined by weak interactions. The use of the hypothesis makes it possible to physically interpret a rather large group of experimental data on the initiation of low energy nuclear reactions (LENRs) and the acceleration of radioactive α- and β-decays in a low-temperature plasma.
    [Show full text]
  • Toxicological Profile for Tungsten
    TUNGSTEN 73 4. CHEMICAL AND PHYSICAL INFORMATION 4.1 CHEMICAL IDENTITY Tungsten is a naturally occurring element found in the earth=s surface rocks. Tungsten metal typically does not occur as the free element in nature. Of the more than 20 tungsten-bearing minerals, some of the commonly used commercial ones include feberite (iron tungstate), huebnerite (manganese tungstate), wolframite (iron-manganese tungstate), and scheelite (calcium tungstate). Tungsten appears in Group VIB of the periodic table. Natural tungsten is composed of five stable isotopes: 180W (0.12%), 182W (26.5%), 183W (14.3%), 184W (30.6%), and 186W (28.4%). Twenty-eight radioactive isotopes of tungsten are known; most of these isotopes have short half-lives. Tungsten forms a variety of different compounds, such as tungsten trioxide, tungsten carbide, and ammonium paratungstate (Penrice 1997a). Information regarding the chemical identity of elemental tungsten and tungsten compounds is located in Table 4-1. 4.2 PHYSICAL AND CHEMICAL PROPERTIES Tungsten has several common oxidation states (e.g., W[0], W[2+], W[3+], W[4+], W[5+], and W[6+]). However, tungsten alone has not been observed as a cation. Tungsten is stable, and therefore its most common valence state is +6. The naturally occurring isotopes of tungsten are 180 (0.135%), 182 (26.4%), 183 (14.4%), 184 (30.6%), and 186 (28.4%). Artificial radioactive isotopes of tungsten are 173–179, 181, 185, and 187–189 (O’Neil et al. 2001). Elemental tungsten metal is stable in dry air at room temperature. Above 400 °C, tungsten is susceptible to oxidation. Tungsten is resistant to many chemicals and is also a good electrical conductor (Penrice 1997a).
    [Show full text]
  • Mass Fractionation Laws, Mass-Independent Effects, and Isotopic Anomalies Nicolas Dauphas and Edwin A
    EA44CH26-Dauphas ARI 10 June 2016 9:41 ANNUAL REVIEWS Further Click here to view this article's online features: • Download figures as PPT slides • Navigate linked references • Download citations Mass Fractionation Laws, • Explore related articles • Search keywords Mass-Independent Effects, and Isotopic Anomalies Nicolas Dauphas1,∗ and Edwin A. Schauble2 1Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637; email: [email protected] 2Department of Earth and Space Sciences, University of California, Los Angeles, California 90095 Annu. Rev. Earth Planet. Sci. 2016. 44:709–83 Keywords First published online as a Review in Advance on isotopes, fractionation, laws, NFS, nuclear, anomalies, nucleosynthesis, May 18, 2016 meteorites, planets The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract This article’s doi: Isotopic variations usually follow mass-dependent fractionation, meaning 10.1146/annurev-earth-060115-012157 that the relative variations in isotopic ratios scale with the difference in Copyright c 2016 by Annual Reviews. mass of the isotopes involved (e.g., δ17O ≈ 0.5 × δ18O). In detail, how- All rights reserved ever, the mass dependence of isotopic variations is not always the same, ∗ Corresponding author and different natural processes can define distinct slopes in three-isotope diagrams. These variations are subtle, but improvements in analytical capa- Access provided by University of Chicago Libraries on 07/19/16. For personal use only. Annu. Rev. Earth Planet. Sci. 2016.44:709-783. Downloaded from www.annualreviews.org bilities now allow precise measurement of these effects and make it possi- ble to draw inferences about the natural processes that caused them (e.g., reaction kinetics versus equilibrium isotope exchange).
    [Show full text]
  • EFFECTIVE RESONANCE INTEGRALS of SEPARATED TUNGSTEN ISOTOPES by Donald F. Shook and Donald Bogart Lewis Research Center
    -’ ‘ NASATND-3957 6 . 1 - EFFECTIVE RESONANCE INTEGRALS OF SEPARATED TUNGSTEN ISOTOPES By Donald F. Shook and Donald Bogart ’ I <II, Lewis Research Center Cleveland, Ohio 2- NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ~~ ~ For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - CFSTl price $3.00 EFFECTIVE RESONANCE INTEGRALS OF SEPARATED TUNGSTEN ISOTOPES by Donald F. Shook and Donald Bogart Lewis Research Center SUMMARY Measurements of effective resonance integrals for separated tungsten isotopes en- riched in tungsten 182, 183, 184, and 186 and for natural tungsten were made relative to gold. The effective integrals were determined by using a small homogeneous reactor to measure epicadmium reactivities for samples of various sizes located at the center of the core. For comparison with the reactivity data, relative y-ray activities of cadmium- covered thin samples of gold were also determined. The experimental results were compared with effective resonance integral calcula- tions by using the Nordheim integral method and recently measured isotopic resonance parameters. Agreement between the calculations and experimental results for tungsten 182, 183, and 184 were generally good. However, for the tungsten 186 samples and for thick samples of natural tungsten, the calculations overestimated experimental effective integrals by 10 to 20 percent. For tungsten 186, the use of a radiation width of 44*4 millivolts for the highly scattering 18.8-electron-volt resonance brought calculations and experiment into better agreement. For natural tungsten, the experimental results indicated the presence of overlap effects for resonances of constituent isotopes. INTRO D UCTlO N A reactor design limitation associated with the use of tungsten in high-temperature thermal spectrum reactors is introduced by the relatively large capture cross sections (ref.
    [Show full text]
  • On-Line Separation of Short-Lived Tungsten Isotopes from Tantalum; Hafnium and Lutetium by Adsorption on Ion Exchangers from Aqueous Ammonia Solution
    Jointly I,ublished by Elsevier Scie.ce S. A~. Lausanne and J.Radioanal.Nucl.Chem.,Letters Akad?miai Kiod6, Bltdapest 214 (I) I-7 (I 996) ON-LINE SEPARATION OF SHORT-LIVED TUNGSTEN ISOTOPES FROM TANTALUM; HAFNIUM AND LUTETIUM BY ADSORPTION ON ION EXCHANGERS FROM AQUEOUS AMMONIA SOLUTION 1 1 1 1 D. Schumann , R. Dressler , St. Taut , H. Nitsche , Z. Szeglowski2, B. Kubica2~ L.I. Guseva 3, 4 G.S. Tikhomirova3, A. Yakushev~, O. Constantinescu , V.P. Domanov 4, M. Constantinescu 4, Dinh Thi Lien 4, Yu. Ts. Oganessian 4, V.B. Brudanin 4, I. Zvara 4, H. Bruchertseifer 5 I Institute of Analytical Chemistry, University of Technology Dresden, 01062 Dresden, Germany 2H. Niewodniczanski Institut of Nuclear Physics, Krakow, Poland ~Institute of Geochemistry and Analytical Chemistry, Moscow, Russia 4joint Institute of Nuclear Research, Dubna, Russia 5paul-Scherrer-Institute, Villigen, Switzerland Received 17 June 1996 Accepted I July 1996 The title goal was achieved using a DOWEX 50Wx8 cation exchange column saturated with La(OH) 3 and ammonia solution as eluent.>Hf, Ta and Lu were adsorbed on this column, where- as W remained in the solution. This chemical system may be used for fast on-line separa- tions of element 106. INTRODUCT ION Subgroup VI elements form oxo-anions in alkaline solu- tion I , whereas subgroup IV and V elements and lanthanides hydroiyze under these conditions. This might be of inter- 0236 -5 731/76/.[/S ~ J 2,0 Cops I"ight ~'9~6 Ak~ch~nlirli KicaM, Blldapr All t il.,ht$ rest'tied SCHUMANN et al.: ON-LINE SEPARATION OF TUNGSTEN ISOTOPES est for fast on-line separation of element 106 from heavy actinides and element 104 produced simultaneously in heavy ion reactions.
    [Show full text]
  • Toxicological Profile for Tungsten
    TOXICOLOGICAL PROFILE FOR TUNGSTEN U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Agency for Toxic Substances and Disease Registry August 2005 TUNGSTEN ii DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. TUNGSTEN iii UPDATE STATEMENT A Toxicological Profile for Tungsten, Draft for Public Comment was released in September 2003. This edition supersedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary. For information regarding the update status of previously released profiles, contact ATSDR at: Agency for Toxic Substances and Disease Registry Division of Toxicology/Toxicology Information Branch 1600 Clifton Road NE Mailstop F-32 Atlanta, Georgia 30333 TUNGSTEN vii QUICK REFERENCE FOR HEALTH CARE PROVIDERS Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Primary Chapters/Sections of Interest Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance’s relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 2: Relevance to Public Health: The Relevance to Public Health Section evaluates, interprets, and assesses the significance of toxicity data to human health.
    [Show full text]
  • Compton Detector of Neutrons for the Energy Yieldcontrol in the Active Zone of Wwer
    UDC 621.387.426 COMPTON DETECTOR OF NEUTRONS FOR THE ENERGY YIELDCONTROL IN THE ACTIVE ZONE OF WWER B.A. Shilyaev, A.L. Ulybkin, A.V. Rybka, K.V. Kovtun, V.E. Kutny, A.O. Pudov, K.V. Kutny National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine E-mail: [email protected] The article examines the processes of radiative neutron capture by nuclei of atoms of metallic rhodium and hafnium. Rhodium is used as the emitter in the direct charge detectors of neutrons, which are used to control the energy yield in the core of nuclear power reactors. A new Compton direct charge detector (DCD) (so-called SPND – Self Powered Neutron Detector) with the emitter of the metallic Hf is proposed. The specifics of the signal formation of the β-emission and Compton neutron detectors are considered. The signal lag time of the rhodium detector was calculated and the respective published data was studied, and the conclusion was made that the use of β-emission detectors for the detection of rapid changes of the neutron flux density is inappropriate. The main advantages of the hafnium emitter is a long “burnout” time of the emitter material and the instantaneous response to changes in the neutron flux in the reactor core. Therefore, the use of detectors with such emitters will simultaneously enhance the reliability and safety of operation of the reactors that are in use currently and those that are being developed. INTRODUCTION and of the emitter of gamma rays from the metallic The technology of the electrical energy production hafnium.
    [Show full text]
  • Electric Quadrupole Moments of the First Excited States of 194 Pt, 196 Pt
    THE AUSTRALIAN NATIONAL* UNIVERSITY RESEARCH SCHOOL OF PHYSICAL SCIENCES ANU-P/948 April 1986 ELECTRIC QUADRUPOLE MOMENTS OF THE FIRST EXCITED STATES OF 19i+Pt, 296 Pt AND X 98Pt G.J. GYAPONG, R.H. SPEAR, M.T. ESAT and M.P. FEWELL Department of Nuclear Physics, Australian National University, Canberra, ACT 2600, Australia and A.M. BAXTER and S.M. BURNETT Department of Physics and Theoretical Physics, Faculty of Science Australian National University. INSTITUTE OF ADVANCED STUDIES ANU-P/948 April 1986 ELECTRIC QUADRUPOLE MOMENTS OF THE FIRST EXCITED STATES OF 194Pt, 196Pt AND 198Pt G. J. GYAPONG, R M. SPEAR, M.T. ESAT and M.P. FEWELL Department of Nuclear Physics, Australian National University, Canberra, ACT 2600, Australia. and A.M. BAXTER and S.M. BURNETT Department of Physics and Theoretical Physics, Faculty of Science, Australian National University, Canberra, ACT 2600, Australia. 12 16 Abstract: Coulomb excitation of iHi96,i98Pt by «He, C and 0 projectiles has + been used to determine the static electric quadrupole moments Q(2t ) of the first excited states of 194« 196« 198Pt, together with values of BfpliOf^f). It is clearly established that Q(2t+) is positive for each nucleus, having values of 0.48(14)eb and 0.66(12)eb for 194Pt and 196Pt, respectively, and 0.42(12)eb or 198 + 0.54(12)eb for Pt, depending on whether the interference term P4(22 ) is positive or negative. Results obtained for B(E2;0J+->2J+) are 1.661(1 l)e2b2, 2 2 2 2 1.382(6)e b and 1.090(7)e b for iHi96,i98Pt> respectively.
    [Show full text]
  • Simulation of Neutron Irradiation Damage in Tungsten Using Higher Energy Protons
    Nuclear Materials and Energy 9 (2016) 29–35 Contents lists available at ScienceDirect Nuclear Materials and Energy journal homepage: www.elsevier.com/locate/nme Simulation of neutron irradiation damage in tungsten using higher energy protons ∗ R. Rayaprolu a, , S. Möller a, Ch. Linsmeier a, S. Spellerberg b a Forschungszentrum Jülich, Institut für Energie- und Klimaforschung - Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany b Forschungszentrum Jülich GmbH, Institut für Neurowissenschaften und Medizin - Nuklearchemie, 52425 Jülich GmbH, Germany a r t i c l e i n f o a b s t r a c t Keywords: This study combines both transmutational changes and accelerated damage by simulation of irradiat- Irradiation damage ing tungsten with 16, 30 and 45 MeV protons. Comparative results indicate 30 MeV to be most optimal Neutron damage amongst the three, for uniformity of combined damage. Finally, the results were compared against fis- Fusion sion reactor calculations and DEMO relevant compositional changes. Using 30 MeV protons, for damages Tungsten Proton irradiation of 1 dpa equivalent, the rhenium content is calculated as 401 appm. This compares well against appm Plasma-facing materials induced within a DEMO reactor and is better than estimated 50,000 appm for a fission reactor. Using higher energy protons, the recoils are expected to behave similar to neutron displacement damage cre- ation. Additionally, the study suggests near constant and comparable damage for sample thickness’s upto 500 μm. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ).
    [Show full text]
  • Experimental Searches for Rare Alpha and Beta Decays
    Experimental searches for rare alpha and beta decays P. Belli1;2;a, R. Bernabei1;2, F.A. Danevich3, A. Incicchitti4;5, and V.I. Tretyak3 1 Dip. Fisica, Universit`adi Roma \Tor Vergata", I-00133 Rome, Italy 2 INFN sezione Roma \Tor Vergata", I-00133 Rome, Italy 3 Institute for Nuclear Research, 03028 Kyiv, Ukraine 4 Dip. Fisica, Universit`adi Roma \La Sapienza", I-00185 Rome, Italy 5 INFN sezione Roma, I-00185 Rome, Italy Abstract. The current status of the experimental searches for rare alpha and beta decays is reviewed. Several interesting observations of alpha and beta decays, previously unseen due to their large half-lives (1015 − 1020 yr), have been achieved during the last years thanks to the improvements in the experimental techniques and to the underground locations of experiments that allows to suppress backgrounds. In particular, the list includes first observations of alpha decays of 151Eu, 180W (both to the ground state of the daughter nuclei), 190Pt (to excited state of the daughter nucleus), 209Bi (to the ground and excited 209 19 states of the daughter nucleus). The isotope Bi has the longest known half-life of T1=2 ≈ 10 yr relatively 115 115 to alpha decay. The beta decay of In to the first excited state of Sn (Eexc = 497:334 keV), recently observed for the first time, has the Qβ value of only (147 ± 10) eV, which is the lowest Qβ value known to-date. Searches and investigations of other rare alpha and beta decays (48Ca, 50V, 96Zr, 113Cd, 123Te, 178m2Hf, 180mTa and others) are also discussed.
    [Show full text]