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ORGANISATION OF THE ILL In 1977 Page 4 L'INSTITUT LAUE-LANGEVIN 7 INTRODUCTION PAR LE DIRECTEUR 9
INSTRUMENTATION Introduction 15 Statistics and Instrument tables 20 Instruments which became operational in 1977 24
INSTRUMENT GROUPS Fundamental and nuclear physics 23 Three - axis 53 Time of flight 35 Diffuse scattering 38 Diffraction 41 Monochromators 40
COLLEGES Map showing the origin of experimenters 52 College 2 : Theory 33 College 3 : Fundamental and Nuclear Physics 56 College 4 : Excitations 02 Coilege 5 : Structures G7 College 6 : Liquids, gases and amorphous materials 72 College 7 : Imperfections 76 College 8 : Structural biology 81 Coilege 9 : Chemistry 84 European Molecular Biology Laboratory 88
DEPARTEMENT TECHNIQUE 89 DEPARTEMENT EXPLOITATION DU REACTEUR ET DES INSTRUMENTS 94 DEPARTEMENT INFORMATIQUE ET ELECTRONIQUE 104 ADMINISTRATION 109
INFORMATION 1977 Experiments performed 119 Theses 137 Conferences at ILL 138 Publications 139 external organisation of the institut laue-langevin 1977 associates of the institut 1=E\ f great britain france west germany
COMMISSARIAT A L'ENERGIE ATOMIQUE (CEA) SCIENCE RESEARCH COUNCIL (SRC) GESELLSCHAFT FUR KERNFORSCHUNG | CENTRE NATIONAL DE LA RECHERCHE KARLSRUHE (GfK)* SCIENTIFIQUE (CNRS) steering committee (at its last meeting)
L. Hobbb Winter - (CNRS) 1.. Gemel J. Enderby . Creyssel - (CNRS) Chairman W. Hofbauer J. Paton . Horowitz - (CEA) W.Schôtt M. Robins Vice-Chairman JUSM. Pascal • (CEA) W. Klose
audit commission
W. Becker W. Riess 1
«With effect from 1.1.78 Kernforschungszentrum Katisruhel KFK! scientific council (at its last meeting)
— CNRS Grenoble J. Enderby — Univ. Bristol H. Msicr-Leibnitz — Dt. Forschungsgemeinsch. Bonn — MPI Stuttgart E. Fischer — Univ. Mainz E. Mitchell — Univ. Reading — Portsmouth Polytechnic A. Guînier — Univ. Parts Sud P. Rigny — CEN Saclay — CEN Saclay W. Hoppe — MPI Martinsried H. Stiller — KFA JOIIch — Strasbourg P. Kienle — TU Munchen T. Waddington — Univ. Durham — Univ. Oxford A. Leadbetter — Univ. Exeter J. White — ILL - Chairman J. Yoccoz — IN2P3. Paris
SUBCOMMITTEES OF THE SCIENTIFIC COUNCIL
m m ii 3M2l2»2SiX«£aeK3 Crystal Physics Crystal Structure " Nuclear Physics Excitations and magnetism détermination Liquids Imperfections Biochemistry Phys. Cherr.islry Instruments
Armbruster Coles Bacon Bertaut Bronig Elliott Blow Ballard Famous Bouchiat Comes Sertaut Dachs Cowley Haaaen Bradbury Benoit Glâser Faissner Dransfield Dachs Fender Guinier Ouere Holmes Bienfait Mitche!! Gizon Glâser Goodenough Jagodzinski Hanson Schmatz Hoppe Ertl Rouit I'ienle Schofield Korokawa Korekawa Hertz Souietie Luzzati Fischer Schmatz Leroux Villain Pawley l-ivago Levelut Zittartz North Higyins Windsor Sandars Will Milledge Mitchell Parello Leadbetter Smith Pawley Powles Stunsanr: Monnerie Rees Ruppersberg Witz Ottewil von Schnering Renouprez Rivail Schellen Stiller Thomas Waddlngton Wegner Weiss
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I I o internal organisation of the institut iaue-langevin at 1.1277
DIRECTORATE J.White J. Joffrin SCIENCE BOARD T. Springer MANAGEMENT BOARD J. Brown B. Jacrot J. Joffrin B. Dornsr J. Joffrin M. Jacquemain T. von Egidy T. Springer A. Plattenteich J. White T. Springer J. White %=^« u.
/G» -•L - '• j COLLEGES (College Secretaries) INSTRUMENT GROUPS SERVICES % COLLEGE 2 THEORY J. Loveluck 3 AXiS SPECTROMETERS TECHNICAL, SAFETY AND HEALTH3 \ COLLEGE 3 FUNDAMENTAL AND (B. Dorner C.Escribe) PHYSICS DEPARTMENT NUCLEAR PHYSICS INSTRUMENTS FOR FUNDAMENTAL M. Jacquemain | G.Siegert AND NUCLEAR FHYSICS j COLLEGE 4 EXCITATIONS (T. v. Egidy-G.Siegert) W. Stirling DIFFRACTOMETERS REACTOR OPERATION AND | COLLEGE 5 STRUCTURES (J. Brown K.Ziebeck) INSTRUMENT SUPPORT DEPARTMENT F.Tasset DIFFUSE SCATTERING AND TIME Y. Droulers | COLLEGE G LIQUIDS, GASES OF FLIGHT SPECTROMETERS AND AMORPHOUS (B. Jacrot •A.Heidemann/ R.Scherm) COMPUTING AND ELECTRONICS MATERIALS MONOCHROMATORS DEPARTMENT J.Copley {A. Freund) COLLEGE 7 IMPERFECTIONS D. Rimmer A.Murani COLLEGE 8 STRUCTURAL BIOLOGY P.Timmins ADMINISTRATION COLLEGE 9 CHEMISTRY A. Plattenteich S. Howells W™—
^"scîÊTSCIENTIFIr C SECRETARIAT AND LIBRARY B.Mainr III I Willi— l'institut max von !aue-paui langevin
L'institut Max von Laue-Paul Langevin (ILL) de Grenoble a été créé officiellement en janvier 1967 par la signature d'un contrat entre les gouvernements de ia France et de la République Fédérale Allemande. Le but était de mettre à la disposition de l'ensemble des scientifiques des pays membres une source de neutrons unique en son genre et utilisable dans divers domaines tels que la physique de l'état conden sé, la chimie, la biologie, la physique nucléaire et la physique des matériaux. La construction de l'institut et de son réacteur à haut flux fut réalisée conjointement par la France et l'Allemagne, les capitaux investis s'élevant à 335 millions de francs français. Le réacteur divergea en août 1971 et atteignit pour la première fois sa pleine puissance de 57 MW en décembre 1971. L'année 1972 vit la mise en service des sources froide et chaud , des promlers dispositifs expérimentaux et marqua In commencement du prograrr ne expérimental. Le 1er janvier 1973, le Royaume-Uni devint le troisième partenaire associé a parts égales de l'Institut, apportant sa quote part à l'investissement total, line nouvelle convention fut alors signée en juillet 1974 par les ministres compétents de chacun des trois pays membres. Aux termes de la loi française, l'ILL est une société de droit civil. Les trois pays sont représentés par les organismes suivants : — <•• Kèrnforschungszentrum Karlsruhe GmbH » (KFK).RFA antérieurement •• Gesellschaft fur Kernforschung mbH » (GfK) — Centra National ic la Recherche Scientifique, France — Commissariat à l'Energie Atomique, France — « Science Research Council >•, Royaume-Uni. Ces associés sont représentés par un comité de direction qui fixe les règles géné rales de gestion de l'ILL. L'institut a à sa tête un directeur et deux directeurs adjoints, tous trois nommés pour une période de cinq ans'. Le directeur est nommé à tour de rôle par le partenaire allemand ou britannique, les deux directeurs adjoints par les associés n'ayant pas désigné le directeur. Un conseil scientifique, dont les membres sont nommés par les associés, conseille le directeur dans l'élaboration du programme scientifique et sur les problèmes pratiques liés à sa réalisation.
L'ensemble des scientifiques utilisateurs de l'ILL est représenté dans huit sous- comités du conseil scientifique. Ils se réunissent deux fois par an pour choisir parmi les projets de récherche qui leur sont soumis, ceux qui seront réalisés sur les appareils de l'ILL. Un autre sous-comité du conseil scientifique est chargé des questions d'instrumentation et sert de lieu de rencontre entre l'ILL et ses utilisa teurs extérieurs. Le but de l'ILL diffère ainsi fondamentalement de celui de la plupart des autres Instituts de recherche. Il constitue une facil/té centrale créée de telle sorte que les. spécialistes en chimie, physique, biologie et métallurgie appartenant aux labora toires des pays membres puissent utiliser cette puissance unique de techniques neutroniques pour attaquer leurs problèmes sur un plus large front. Concevoir et faire fonctionner les instruments, aider les utilisateurs extérieurs à mener à bien leurs expériences, telles sont les tâches principales des chercheurs ILL. L'utilisation expérimentale des instruments par le personnel ILL est soumise aux mêmes règles d'approbation que celles appliquées aux équipes extérieures. Le 14 mai, une journée d'accueil fut organisée à l'intention des familles et des amis du personnel de l'ILL. Sur la photographie ci-dessus, un groupe, accompagné par Mr White, Directeur, écoute les explications données sur la salle de contrôle. Le jeudi 7 juillet, Sir Fred Stewart, président du "Advisory Council for the Research Councils" (Conseil supérieur supervisant les divers organismes de recherche) du Royaume-Uni, visitait l'ILL. Sur la gravure ci-dessous, se trouvent (de gauche à droite) : Mr NT. Hardyinann et Mr W.O. Ulrich du "Department of Education and Science " (Ministère de l'Enseignement et des Sciences], Sir Fred Stewart, le professeur J.L. Jinks de l'Université de Birmingham et des membres du personnel de l'ILL.
1 1 c
instrumentation
introduction
An Integrated programme of Improvement to the existing instruments, and of new instrument construction, was carried out In 1977. Under the financial constraints, a high priority was given to finishing Instruments in the course of construction and both the ultra cold neutron source, PN5. and the spin echo spectrometer, IN11, came into operation, the first for a number of scheduled special beam expe riments and the second for a series of proving experiments being done In colla boration with external groups. This series of proving tests should take about nine months and should show the best methods of operating the spin echo spectrome ter. No new instrument construction WG' started, since, as mentioned in the Director's Report, priority was given to the development of underlying techniques and to finishing new instrument projects in hand. Even so, the completion of D18 (the interferometer] and IN12 (the cold neutron three-axis machine) will be delaynd until 1978. In the case of IN12, some advantage was taken of the delay to implement a new system of three-axis drive mechanics and of interfacing elec tronics which may servo as a standard for future throe-axis machines. The IM1R instrument will be the first three-axis machine to use the new range of Solar compu ters. A major technical investment was the establishment of a commission to determine and specify a modem system of mechanics, motors, electronics and computer Interface suitable for controlling all shaft movements. A uniform system for both three-axis instruments and diffractometers Is to be sought as a first objective, but uniformity between these different types of machines will not finally be a constraint. The commission will report early In 1978. The evolution in the number of scheduled instruments at the ILL Is shown In Figure 4.
11 NUMBER OF OPERATIONAL INSTRUMENTS 30 20 27 24
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i_aJAN. JAN. JAN. JAN. JAN JAN 1973 1974 1975 1975 1977 1978 Figure 4. - Development of the number of operational instruments. >wmm%$m mm®@m®ft @®é :m0mmmu m. ite- JKIFPW m? itjsx
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*"<# §#€^ t A detailed report on the work of each Instrument group Is given below. The Investments made for the groups have, In all cases, led to significant improve ment in instrument performance ; for example, on Lohengrin, reduction of back ground by a factor of 10, improvement by a factor of 10 In the timing sf the spectrometer, and a purer mass spectrum with, nevertheless, an improvement of 10 % in Intensity. On the GAMS, PN3, the new target changing device has allowed the manipulation of radio-active and actinide targets, and the graphic display system now allows any distortions in the sample to be Immediately detected. This has considerable value from the point of view of the safety of the installation.
In the Three-Axis Group, considerable improvements to goniometers on all ma chines have been made, as well as to the drive systems. The Rutherford Labora tory collimators have been Introduced widely and standardisation between spec trometers Is proceeding.
In the Diffraction Group, considerable relief was given to CAR1NE, and hence other instruments using this computer, by the Installation of OS on a dedicated PDP-11 computer. The problems of data transfer are now engaging full attention. General improvements to monachromators, cryostats, and to the stability of the diffracto- meters has led to increased performance and, for D3, the cryofllpper installed during the year* now has an efficiency which is independent of the neutron wave length and the sample magnetic field. The signal to noise ratio cf the film detection system of D12 has ben considerably improved by the addition of a system of oscillating slit collimators between the sample and the film. Oniy neutrons which come from the direction of the specimen or close to it (± 0.S cm) are recorded on the film. The background due to the cryostat walls is thus elimi nated, and long exposures are possible (see figures i and ii).
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a Fig. i. - The background signa! (upper Fig. if. • A 6 oscillation photograph of DyMn04 half of the figure) received from an on 012 at 20K (exposure time 30 minutes). aluminium cylinder around.-the sample position on D12. For the Diffuse Scattering and Time-of-Flight Group, Important Investments were made to Improve the operation of the small angle cameras D11 and D17 and, in particular, the transfer of IN5 to the ARC system of guaranteed supply has eli minated the effect of thunder-storms during the summer.
The area of special beam instruments at the ILL continues to be supported strongly, although the demands for servicing on the equipment brought to the Institut from other laboratories, and for general support, are sometimes beyond those which can be made available, Requests for greater standardisation of this equipment with that already at the ILL have been made. The policy with respect to special beam instruments is to give as much support as possible while maintaining a first priority for the scheduled programme. A review of the whole range of special beam Instruments at the ILL will be conducted at the Scientific Council in March 1978 In order to decide the priorities for future support. It will be a matter of policy to give strong eupport during an initial period to chosen experiments, which must have a well'dcflned life-time when proposed. After the initial period, support from outside the Institut will be a necessary condition for continuation. JUH**FM.ii«iBtr t\ MP»^fv>rT.-y <• i>—-» "TW>" »rw.-jti^mi«_» i!Pi^n^fiJw^MI'- •-*"™-""'"
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C- • - * 1 \. "8 A cutaway view of the reactor and some of thn associated beam tubes INSTRUMENT OPERATING STATISTICS (JANUARY THE REACTOR HAS OPERATED FOR 257 DAYS DURING THE YEAR. 14.3 DAYS (7.3 DAYS WERE RECUPERATED BY EXTENDI1. Instruments Total operating Loss of beam Coll. Coll. Coll. Coll. Coll. Coll. Coll. Internal tes: time (days) time (days) 3 A 5 6 7 8 9 < feasibility. and instfLire: • Jfnprovemei: experiment INI 22S.3 31.7 90.2 16.3 22.G 77.0 '9.8 IN2 226.7 3D.3 192.0 9.0 7.7 17.2 IN3 216.9 40.1 189.2 3.0 33.7 IN4 226.0 31.0 28.8 30.1 3S.2 94.4 33.5 INS 219.3 37.7 2.8 88.7 37.6 27.2 54.0 90 IN7 50.0 207.0 50.0 IN8 192.6 64.4 144.5 5.3 18.2 14.0 IN1C 239.4 17.6 10.5 34.8 50.9 10.0 109.2 1«-0 IN11 D1A 232.0 24.2 173.0 9.C G.O 9.1 35.7 ; DIB 250.3 6.7 136.4 33.6 10.7 7.5 62.1 D2 233.8 23£ 130.6 51.8 5.3 45.9 i D3 216.2 30.8 176.2 42.0 D4 234.1 22 9 1705 63.8 D5 231.7 25.3 171.7 31.5 14.6 13.9 ! D7 ' 1785 78.8 2.8 158.8 16.6 D8 220.7 36.3 166.1 41.0 13.6 D9 231.3 25.7 204.1 5.5 21.7 DIO 232.1 24.9 144.3 62.4 25.4 D11 231.5 25.5 7.9 5.9 51.8 68.4 40.7 SEa D12 218.0 39.0 22.0 93.0 7.0 96-° D13 114.0 114.0 015 207.2 49.8 205.7 1.5 63.0 DIE 226.4 30.6 51.3 112.1 D17 62.5 3.0 2.0 16.C 18.9 22.0 PN1 216.0 39.0 152.0 53.0 PN2 224.0 33.0 186.0 3G.0 23.7 PN3 (Gl) 210.5 46.5 136.8 PN3 (G2/3) 221.2 35.7 212.9 8.4 PN4 52.4 52.4 - PN5 PN6 27.0 27.0 ! I V CfL " (JANUARY TO DECEMBER 1977) -, i>R. , 14.3 DAYS WERE AFFECTED BY UNSCHEDULED SHUT-DOWNS iY I EXTENDING THE OPERATING CYCLE) II. I Internal test, j feasibility, and instrument Comments improvement . experiments I 1S.8 ! 17.2 I I 33.7 / i ^ 1 '!t "' 9.0 : Instrument modification completed June 1977, commissioning experiments in progress 1 14.6 Loss of beam time includes 20 days for electronic modification .- m.o • I Continuation of Instrument tests and scientific feasibility experiments .';""" 35.7 .5 62.1 - 45.9 42.0 53.0 Test period includes 35.0 days for multfdetcctor Installation and test 13.9 16.6 Loss of beam time includes changing instrument mode to polarised neutrons 13.6 v 21.7 25.4 J6.8 Test time Includes 43.0 days for D11B commissioning -.0 96.0 Test period Includes instrument modification and improvements 114.0 12 short term experiments recorded [XTAL alignment, mosaic control, topography. nembranes etc.) 1.5 63.0 Test period includes 15G days for instrument alignment and modifications Î.S 22.0 Commissioning experiments completed. Full scheduling commenced 22nd July 1977 53.0 36.0 23.7 Operational time includes decay measurements during shutdown period. SA Loss of beam time Includes sole use of PN4. [ Use restricted by experimental requirement and positioning of PN3 (G1] " Commissioning experiments continued Operational ILL instrument from November f, 1977 TABLE II • PROJECTS IN PROGRESS (1977) IN5 B A high Intensity tlme-of-flight spectrometer in the À-range 4.1 to' 5.5 A. It will have three double focusing monochromator crystals Si (III) 20 cm high; a Form i chopper ; 2 metre fliqht path; 4 m2 detector area. The guide bâam hole on H15 was sut during the October shut-down to provide space for the monochromator assembly. Tho instrument layout is in progress and a comparative study of detectors is unritrway. IN 12 High resolution triple axis speclometer on a cold neutron gulcfe tube. During 1977 the monochro- mator shielding and sample table were completed. The analyscr-dstecter unit is under construc tion. Tests hâve shown that the new drive modules are capable of speeds considerably in excess of those of the traditional "Tanzboden" units. 1N12 will be controlled by a SOLAR 1G/40 computer via ,i microcomputer for step-motcr control. The SOLAR will be delivered in January 1978. First tests nf the complete instrument should be possible by late summer of 1978. D18 B Polarised neutron version of the neutron interferometer. There has not been any progress made with this instrument duo to lack of funds. D19 In 1977 a few delays in the realization of D19 have occured due to the lack of means (technical and manpower). Nevertheless construction of the D19 multidetector will be finished !n 1S78, and it will then be tested with Its own computer, which has been ordered this year. A smaller prototype 2 dimensional detector, already under test, is expected to be of value to replace standard diffractometer counters. TABLE HI - PROJECTS UNDER DEFINITION The scientific and technical definition of this instrument, a backscattering spectrometer, is complete. It will operate with cold neutrons having a wavelength near 6  and an energy range up to 1 meV. Further progress is dependant upon the budget. This is a backscattering spectrometer on a thermal guide. It will operate at 2.2 À with O-values up to 6 A —' and an energy range from —300|tev to 4- 500|iev by means of a temperature-scan (0 to 500*0 together with a 28[t-Bcan (160 to 1781; of tho monochrumator. The project is new completed, and construction will start in 1S73 subject to manpower and budgetary constraints. According to an ideal time schedule, It would be operational during 1080. 22 TABLE (V - SPECIAL PROJECTS Optimised Shaft Control A working group has been sot up to study in depth the problems of automatic shaft control, that is. the moving time of shafts and the position of angles, as part of the long term plans for improving the performance of triple-axis spectrometers and diffractometers. The working group will report during 1978. Monochromators During 1977 the success rate of Ge and Si crystal production has been improved, the anisotropic mosaic sproad being controlled during production. Tests of the efficiency of Si crystals for cold neutrons aie In progress. Ge crystals have been produced to assemble vertical focusing monochromators: this technique has been succesRful on D10, giving a gain In intensity without subsequent hss in resolution. The Joint project by the MPI Stuttgart and ILL. to develop and produce good quality Beryllium crystals continues with good .results. Tests are being carried out at I.L.L for optimisation of the growth parameters. A feasibility study of pyrolytie graphite monochromators with variable lattice spacing has been undertaken. Evaporator A new type of neutron polariser, the super-mirror, was developed In 1976. The super-mirrors consist of a large number (50 or more] of thin iayers vacuum deposited on a glass subs trate. In 1977 they were tested In practice, serving as polariser and analyser on the IN 11 spectrometer. For their further development an ultra high vacuum evaporator is being instal led on a waste neutron beam, which will permit on-line monitoring of the neutron reflectivity of the super-mirror thai is hoing deposited. The evaporator will be put into full, automatic operation in 1978, and its size will bo sufficient for a small scale production of polariser systems. TABLE V SPECIAL INSTRUMENTS AND SPECIAL BEAM EXPERIMENTS CARRIED OUT OR IN PREPARATION IN 1977 EXPERIMENT No. TITLE 07-04-002A In beam NMR spectrometer 03-03073 (n, «} (n. p) end [n. f) reactions on 03-03-074 several heavy Isotopes 03-03-075 07-03-04S Neutron topography 05-16-94 0501-100 High precision lattice parameters in 5-15-81 KDP and TGS near Tc 5-10-93A 03-03-007 Neutron storage ring using ultra-cold neutrons 03-03-003 Neutron bottle using ultra-cold neutron: 03-03-OH Protein contents in seeds 03-04-001 Concentration profiles by (n, a) and (n. p] 03-03-0ISR ga/gv from free B -decay 03-03 030 Neutron half life 03-03-076 23'Pa. sMTh („, [) 0343-077 2KU (n, f! D3-03-OSÔ 1 and 2-photon decay in n 4 He3 0343-058 Gamma directional distribution from oriented nuclei 03-O3-O59 y—y directional correlation after neutron capture 03435-001 Neutrino cross section 03-05402 PNC effects in polarized neutron optics 5-16-51 5-17-104 laue illflractlon on iFe,03. COUÎ. NI0. CoO 5-17-105 03-05-003 Spin rotation 1 23 instruments which became operational in 1977 NEUTRON SPIN-ECHO SPECTROMETER IN11 The neutron spin-echo (NSE) principle is utilised to determine the time Fourier transform, S~(Q,t), of the scattering function S(Q,u) at a given momentum trans fer O. The NSE method compares the incident velocity of each Individual neutron with Its scattered velocity, so that resolution and beam monochromatization are basically Independent. The spectrometer, which Is designed specifically for high- resolution quasielastic spectrometry, is shown schematically In fig. S. For each neutron, the wavelenght changeA X during scattering is encoded as a phase shift A Within the quasielastic approximation one has AX« X, , so that u is jpropor- tional toAX , and the measured quantity isPx=JS (Q.io)cos(tot) du= S (O.t). The Fourier variable t depends on the number of precessions in the magnetic field H0 , the f^eld length d, and the incident wavelength X0. For d(cm), H„ (oersted) and X„ (A), t = 2|y|uN m£ H„ d X3/W, where h Is Planck's constant, m is the neutron mass, uN the nuclear magneton and Y = —1.913. Hence for fixed geometry, t = constant H„, and the experiment consists of measuring P, as a function of HD. Since this measurement gives the Fourier transform of the scattering function, the d^.inition of the instrumental resolution needs some clarification. In particular. the Fourier transformation makes deconvolutlon procedures unnecessary, the latter being replaced by a simple normalisation of the polarisation against a calibrated scattering sample. We therefore define the resolution in terms of a particular spectral shape. For example, if S(Q,w) is Lorontzian with width parameter Y. the NSE spectrum will be the exponential function P% = exp (—Y Itl). The resolution of the instrument can then be defined as the full-width at half maximum of the Lorentzian line for which P, has dropped, say, 5 % at the maximum attainable value of the Fourier parameter (i.e. exp (—2 y t „,.„ ) = 0.95). The percentage drop of 5 % is arbitrarily chosen as an easily measurable change in the polarisation. 24 Instrument details Boam tube : H14 (vertically S-bent cold guide) Incident wavelength range see fig. 6 Monochromotlzatlon : ± 20 % (± 10 %, variable is under construction) Polariser, Analyser : Neutron optical types, P„ > 97 %. Both supermirror and Soller guide systems are available. Peak Intensity at the sample : 1.5 c 10?n. cm-2.s-' (area 30 x 30 mm*) Scattered beam : accepted solid angle 15' x 15' to 1° x 1° Mompntum transfer range 1.0° S 20 «S 140° at at 3 , 6 x 10-9 »^S,^r(fsi»»,. *5""ff a^'f'^M^Sig ^•rSS^>JT. K li •it} ! !-?*!d ::.:.. U '.la»*' ;a: iT^i» ... iiMr-rrTT-** r.n-...-»ài-r ^.^l:*;'..^.: «w.J&lfl The iN11 spin-eciio spectrometer operating ut 80" scattering angle. The incident beam is raised by a vertically S-bent guide to allow clearance of the D11 collimation system. ultra cold and very cold neutron source P N 5 1. Description of the Source : The source of Ultra Cold Neutrons (UCM 3 < v. < 6 m/s) and of Very Cold Neutrons (VCN 6 < v„ < 100 m/s) which has been installed at the High Flux Reactor, is essentials a neutron guide. It fetches the neutrons Inside the reactor and guides them by total reflection to the experiments. It Includes : — an In-pile guide which Is an internally polished stainless steel tube of 6.7 cm internal diameter. Inside the reactor the entrance window Is a thin Zircalloy dome (< 0.6 cm) connected to the tube by a diffusion weld (Fig. 7). Outside the reactor Zircalloy diffusion weld pi : i\ r • > > > Si t i i I I t I > I • • . r • 30 m w w u ' •. 3=i Zircalloy dome 0,6 mm thick Fig. 7. - Sketch of the converter or the ulira~cold neutron source PNS. the exit window is a sheet of aluminium 100 pnl thick. The nuclear hat « S KW total ; 2.5 watt/g maximum) is removed by flowing HjO (300 g/s) which acts also as converter. The tube is installed inside the inclined beam tube IH3, thus with the exit 3 m above the entrance. — an out-of-pile guide which is a square (7x7 cm*) curved tube (R = 9.82 m), made of nickel-coated, berated glass plates. The glass elements are inside a stainless steel vacuum container, with on entrance window of 200 [im of alumi nium. The set is placed inside a removable beam catcher made of iron and paraffin. istnbubon boot — a "distribution box" which contains movable sections of guides which could divert the beam in three dif ferent direction 40° left, straight en, and 40° right. The curved guides (R = 0.5 m) are made of thin nickel- coated glass plates fixed In grooves inside nickel coated plastic plates with spacing of 2-3 cm. The layout of the instrument is shown in Fig. 8. Fig. S. - Lay-out of the uttra-cold neutron source PN5. ^.(7^,5,« „ spectrum over \ \ / ^j ihe whole seclioni \ ' / ^v. chopper a: 242 rpni \ ,\ recctor power \ i 2. Neutron Spectra ^\ 057MW,. -, \_» Preliminary measurements have been made by a time-of-flight method. ^ \ ' Fig. 9 gives VCN spectra, either the \i with « oddrbon- V\2»100 JJ AI \ mean spectrum over the whole sec u • IS -2 cm air tion at the exit of the main curved guide, or detailed spectra for various values of abscissa x from the top of the section (x = 0.5 — 1.5 — 2.5 — 3.5 — 5.5 cm). The total flux varies from 5.3 x 105 m/cm2/s at the top, to 0.84 x 105 at the bottom of the guide section with a mean value of 2 x 105. Fg. S. • The very cold neutron spectra of PNS. 27 V ;wilh UMmalor L=l,25Dl L. t =50nfcm2, s Flg. 10 gives UCN spectra taken with Tfor X>586 4 and without collimator, which are res V<6.7 m/» pectively lower and upper limits of the actual spectrum. The total number of detected UCN with velocities below 6.7 m/s (thus which can be stored in bottles made of nickel or beryllium) is about 50 m/crrv/s with collimator and 150 m/cm2/s without collimator and the actual value Is estimated to bo 90 (at full reactor power). ico IO3 A(I) Fig. 10. ' Th'.' ultr&cc/d .neutron spectre of PN5. 28 instrument group "fundamental and nuclear physics" PN1 Fission Product Spectrometer (LOHENGRIN) on beam tube H9 PN2 : Beta Spectrometer (BILL) on the vertical beam tube V3 PN3 Three Curved Crystal Gamma Spectrometers (GAMS 1, 2. 3) on the through going beam tube H6/H7 PN4 : Ge Anti-Compton and Pair Spectrometers on the through going beam tube H7 PN5 : Ultra-Cold Neutron Source on the inclined beam tube IH3 PN6 : On-Line Mass Separator for Thermally ionized Fission Products (OSTIS) on neutron guide H23L PN7 Cold Polarized Neutron Beam on neutron guide H14L H18 Cold neutron guide : Determination of the neutron half-life (S37) H22 : Thermal neutron guide : Neutron induced particle emission (S10), Y-Y angular correlation (S31). y-ray directional distribution from oriented nuclei (S34) and one and two photon decay after neutron absorption in 3He (S3S) H25 : Thermal neutron guide : Concentration profiles by neutron-induced particle emission (S30) IH1 : Very intense neutron beam tube : Neutron-induced fission (S16, S38) — Neutrino croc-sections and neutrino-oscillations (S40, no neutron Learn position requested). PNI - FISSION PRODUCT SPECTROMETER LOHENGRIN (H. Schrader) During 1977 the mass separator was operational for 215 days (SO % of the reactor time). The beam time has been used for 14 experiments in collaboration with external research groups for 148 days (55 %) and for several test runs during 67 days (25 %). Within the test runs the development of the fission product (f.p.) back-ground from sputtered uranium onto the beam tube and the technique of cove red targets have been studied in order to understand and to reduce the sputtering effect. From March to October 1977 the background decreased from 6 f.p./(s-cm parabola length) to 0.75 f.p./(s-cm) (0.4 %) because only very thin targets of 40 |»g/cm2 U02 or targets covered with a 400 u,g/cm2 Ni foil were used. The Ni foil produced an energy shift for heavy and light fission products of about 15 %. Ni covered targets are now available with a maximum intensity of 1.5 x 104 f.p/s at 72 cm beam exit length (210 f.p./'(s-cm)) with a mass resolution of A/A A = 800 tfwhm) and for the most abundant masses, kinetic energies and ionic charges. The experiments were mainly devoted to the investigation of fission yields. Diffe rent methods of y-intensity ratios in the mass chain were applied. The yield ef fission product isomers as a function of their kinetic energy has been studied by a group from the University of Mainz (A = 132-136) and by a CENG/KFA Julich collaboration (13'Sn, i32Te). A time of flight system for fission products with an absorber technique has been tested successfully by a group from CEN Saclay obtaining a nuclear charge resolution of Z/AZ = 40 (A = 91, E = 88 MeV) In an argon gas absorber. The energy straggling In He, Ar, N2 has been studied as well. In nuclear spectroscopy of neutron rich fission products the 0. -values of B5Se, 8S.9DBr, i«.K5Ba, 144-wu, U7Ce, i«Pr have been measured. PN2 • BETA SPECTROMETER BILL (K. Schreckenbach) In 1977 the beta spectrometer BILL was working continuously about 80 % of the time. 13 targets have been measured for nuclear and atomic physics. It could be shown that the sensitivity of a measurement can be Improved conside rably by repetitive scanning over a part of the spectrum. 20 scans over one line group (corresponding to a variation of 5 % of the magnetic field) during two days caused no deterioration of the resolution in the sum spectrum. The programs for the instrument control were modified and are written now in FORTRAN. Together v/ith a faster terminal (LA36) which was also instated this yaar, BILL can new be operated In a more convenient and flexible way. Also the reliability has been increased further. PN3 - CURVED CRYSTAL GAMMA SPECTROMETERS (GAMS 1 AND GAMS 2/3) (H.G. Borner, W.F. Davidson) During 1977 the curved crystal spectrometers GAMS 1 and GAMS 2/3 were runn ing for 85 % of the time. Test experiments and minor breakdowns summed up to the remaining 15 %. The Y-rays following neutron capture in 12 different tar gets were studied. A modification of the target changing facility including the installation of a glove box, and a shielding against fast neutrons allows for the Introduction of radio active and especially actinide targets. In addition the adjustment of the target position can be made by remote control. The actual state of a running experiment on GAMS 1 oan now be controlled via telephone which transmits the angle of diffraction and the counting rates. GAMS 2/3 has had a polarized laser installed to increase the precision of angle measurements. PN4 - GE PAIR AND ANTI-COMPTON SPECTROMFŒR3 (D. Warner) The Ge pair-spectrometer was fully operational throughout 1977. High energy spectra of y-rays following thermal, neutron capture in 7 different targets were Obtained. Modifications made to the shielding of the GAMS 1 detector with which the beam is shared lead to a 50 % increase in available measuring time. In addi tion, the time resolution and efficiency has been improved by the installation of constant fraction timing. The Ge detector for the anti-Compton spectrometer was delivered and measure ments performed on two targets. Unfortunately, the detector became unstable at its nominal operating voltage, and had to be returned under guarantee. The repair has now been completed and the detector is again operating satisfactorily. PN5 - ULTRA-COLD NEUTRON SOURCE (P. Ageron) The Ultra-Cold Neutron source became operational In April 1B77. Mux measure ments for ultra-cold neutrons (UCN) and very cold neutrons (VCN) have been made. The UCN flux (neutrons with velocities below 6,2 m/sec) is 250 n/cm2sec and the total flux is 2 x 105 n/cm^sec with a velocity distribution peaking at 60 m/sec. Two experiments are currently underway to store these neutrons either in a neu tron bottle or in a magnetic torus. The first experiment searches for an electric dipole moment of the neutron. In the second experiment neutrons (velocities between ID and 20 m/sec) have been stored for the first time in a toroidal ma gnetic sextapole field (0.5 m radius, 3T max field strength, îT/cm field gradient). Stored neutrons could still be detected after two periods of the neutron half-life. PN6 - ON-LINE MASS-SEPARATOR OSTIS FOR THERMALLY IONIZED FISSION PRODUCTS (K.D. WQnsch) After a modification made In November 1976 which increased the intensity by a factor of six, OSTIS now produces a point source of up to 5x106 mass separated rubidium or caesium fission products per second in front of the detectors. The high demand for this instrument continued in 1S77. OSTIS was operational 80 % of the time and 16 different experiments were carried out including two ion- source tests. A special experiment including 3He-detectors as well as a small ion source and a fast switching system for the acceleration voltage (20 kV) and for the quadru ples was set up to investigate the Rb-Cs coincidences. Measurements were performed to determine Q- -values, Pn -values, half-lives and fission yields. Delayed neutron, gamma and conversion-electron spectroscopy were continued. Plans exist to upgrade OSTIS further by increasing the high voltage to 40 kV and to change the ion source design. A first indirect heated ion-source is being developed at the University of Gic-ssen to work at higher temperature and'to ionize also the rare earth elements. PN7 - POLARIZED NEUTRON BEAM (W. Mampe and B. Vlgnon) ». . • ••* T/re on-line Isotope separator •\V; j OSTIS. The present experiments on this beam are intended to look for angular asymmetry in the electromagnetic dec.iy of nuclei which are oriented by the capture of pola rized cold neutrons. In this way violation of parity and time reversal invariance can be measured. According to the experimental requirements two very large liquid scintillators (500 I each) or two large Nal crystals or 6 Nal detectors can be mounted (ISN Grenob' . A high precision electronic system is available which has very small systematic drifts (3 parts in 106 due to temperature stabilisation and effective shielding against magnetic stray fields). Two long term experiments have been carried out in 1977. It is planned to install a new neutron polariser with increased performance in the beginning of 1978. The neutron beams H18. H22, H25 and IH1 were used continuously and success fully throughout 1977 for nuclear spectroscopy, fission research and fundamental physics experiments. A cooperation between ISN and ILL Grenoble. TU Munich and Caltec Pasadena started with the construction of the detector for the neu trino experiment. The scientific results obtained with the instruments are repor ted in the section of college 3 (fundamental and nuclear physics) in this volume. Co-ordinator : G. SIEGERT instrument group "three-axis spectrometers" !N1 on the hot source (beam tube H8) IN2 on the thermal beam tube K13 IN3 on guide tube H24 INB on the thermal beam tube H10 IN12 under constriction on cold guide H14. During the year 1977 the instruments IN2 and new IN'3 have operated in a reaso nably reliable manner. Unfortunately the performance of IN1 and IN8 has been marred by frequent breakdowns. No major modification of the existing instru ments was undertaken. The Carine system continues to give problems and leads to considerable loss of ilme ; its replacemnt should give significant improvement. IN1 - HOT SOURCE 3-AXIS (J.R.D. Copley and J. Tomkinson) The instrument has operated moderately well during the past twelve month.-, although there have been several serious breakdowns. Any breakdown which entails entry to the casemate (shared with D4) can mean considerable delay before the necessary repairs are made. Once again the motor which rotates the monochromsicr drum, and its associated electronics, have hod to be completely replaced. Improvements include the addition of a second monitor (betwen sam ple and analyser), partial motorisation of the overhead crane, and installation of shielding curtains between IN1 and D4. Further-more, improvements to the beryl lium filter analvsing system, in particular construction of a new multiwire detec tor, are under way. As soon as possible, a decision has to be taken regarding the replacement of INI with a completely redesigned hot source three-axis instrument. IN2 - THERMAL BEAM 3-AXIS WITH A DOUBLE MONOCHROMATOR (B. Dorner, W.J. Fitzgerald and C. Joffrin) IN2 has been in regular use for the last year and has been working satisfactorily apart frcm minor electronic and Carine problems. Most experiments have used pyroiitic graphite as monochromator and analyser crystals and a fixed incident energy of 3.14 THz. Many experiments have studied low-frequency excitations associated with structural and magnetic phase tran sitions. During the past six months two new " Rutherford collimators » using stretched mylar have been installed; one between the sample and analyser and the other between the analyser and detector. This has increased the measu red flux by a factor of — 1.5. Further use of these collimators Is envisaged for the future and the gain in flux is significant. IN3 - FOCUSING TRIPLE-AXIS SPECTROMETER ON THE GUIDE TUEE H24 (R. Scherm and V. Wagner) IN3 operated routinely throughout 1977 without any major breakdown problems. It has often been used with the Cu 111 monochromator, in the energy range 4 to 9 THz, thus filling the range between IN2 and IN8. The reproducible crystal mountings installed in 1976 have proved extremely useful, permitting the exchange of monochromators or analysers during the course of an experiment. A new, stronger sample table has been installed allowing the use of heavy cryostats. Except for the steady complaints about the slowness and frequent breakdowns of the Carir.e computer and electronics, the instrument is, in general, operating very satisfactorily. IN8 - THERMAL BEAM 3-AXIS (R. Ctrrrat, C. Escribe and R. Pynn) As in 1976, IN8 has been in great demand all year bocause of its high flux and low background. Variable vertically bent monochromators of pyrolytic graphite and germanium 111 are now available. The flux gain as measured on a small cample, is a factor of 2.5 for all the attainable incident wavelengths from 1.5 to 4À The improvement to the monochromalor drum drive unit and goniometer table permits a higher speed during positioning. The sample table now has independent rotations. The new beam stop permits one to work very near to the direction of the incident beam which can be very useful for magnetic excitations. The use of two Rutherford collimators is envisaged in the near future, the first between monochromator and sample and the second belween sample and analyser. IN12 - 3-AXIS SPECTROMETER (COLO NEUTRONS) (W. Stirling) Considerable progress has been made with the construction of this instrument. The monochromator protection of vertically displaced lead and polythene blocks has been completed and the automatic control system is almost ready. The sam ple table has been completed and tests have demonstrated that the new drive modules can move large masses much faster than with previous mechanical sys tems at ILL. Initial tests of ths neutron beam with a curved pyrolytic graphite monochromator have shown that, if the full vertical height of the H14 beam is used, fluxes in excess of 107 n cm—2 s—"• will be available at the sample position. A SOLAR 16/40 computer is to be delivered early in 1978 and will be connected to IN12 via a microcomputer which controls the stepmotors. First tests of the complete instrument should take place sometime in the summer of 1978. The new mechanical and electronic systems of IN12, if successful, may be implemented on future triple-axis spectrometers. Co-ordinator : C. Escribe instrument group "time of flight" IN4 : Rotating crystal spectrometer on thermal tube H12 J IN5 Multicliopper spectrometer on cold guide H16 > fully IN7 Double monochromator and Fermichopper on thermal / operational tube H15 IN11 : Spin echo spectrometer on cold guide H14 (full operation envisaged end of 1978) IN5B : New time of flight instrument (design study started in 1977) IN4 - TIME OF FLIGHT SPECTROMETER (J.B. Suck, P. Poncet, R. Richardson) 28 experiments were performed on IN4 In 1977. This year much effort was put into building a high temperature O 2000 K) furnace for IN4 which is difficult due to the horizontal sample geometry in the spectrometer. This furnace is the refore still not completed. To facilitate the control of the cryostat, an automatic He-backflcw regulation was added to the cryostat system. The results of the measurements of absolute intensities and the energy resolution for elastic scatte red neutrons for all three monochromator systems (graphite, Cu, Fermi chopper) are now available (internal scientific report 77SU17T). We are still looking for ?. good solution to reduce the background from windows and gas inside tlia spectro meter. Hopefully, this will be found next year. 6 new detector boxes were ins talled in autumn 1977, enlarging the intensity, and the momentum transfers mea surable at the same time by nearly 20 %. INS - MUUICHOPPER SPECTROMETER (AJ. Dianoux, F. Douchin) The instrument was operational throughout the year, performing 44 experiments. 7 of them were disturbed by chopper breakdown, with a mean loss of 3 days each time, mainly due to running In. In the present state of the machine this duty ratio can only be improved by grouping the experiments in long periods using the same chopper speed, i.e. 10 000 or 15 000 r.p.m. The temperature control sys tem of the chopper bearings has been equipped with a zero degree referene, improving safety and accuracy. The problem of power failures (thunderstorms) is now completely solved by the connection cf IMS to the ARC system. The link neutron guide between the choppers has been equipped with glass windows allowing optical control of the stability of the guide supports. The new series of 400 3He detectors is under delivery with very long delays due to electronic noise problems (microphonics). Only 100 new detectors are now available. Their background contribution is twice as high as that of th A new 400° C furnace is available, allowing the use of 3 samples simultaneously, with an automatic changer, good gradient, and thin windows in the beam. The former INS Helium cryostat has been eliminated and Is to be replaced in 1978. A special closed circuit refrigerating machine is under study. The replacement of the " NICOLE '" computer system and the completion of the detectors extension will take place in 1978. Mounting of a multidetector is being studied. It would fill a gap in the small O range of the instrument. IN7 • DOUBLE MONOCHROMATOR AND PERMICHOPPER (A. Murani) The rebuilding of the ttme-oF-flight spectrometer IN7 was completed in April 1977. it now consists of graphite double monochromators and the beam is pulsed by a Fermi chopper. A counter bank of 36 Ke3 counters at a flight path of 2m from the sample covers the small angle range of between —10° and + 25° about the beam centre thus providing an ideal arrangement for small angle and magnetic scattering work. The first tests carried out proved quite satisfactory : the spec trometer's performance, in terms of intensity at the sample and the overall energy resolution, being comparable to that of IN4 (despite the shorter flight path (or 1N7). A few scheduled experiments have been performed during the period June to August. However, due to the breakdown of the trigger unit, the spectro meter has been out of action during the 5th cycle and is not yet repaired. Ser vicing the electronics of the instrument is a major problem for ILL staff because of the non-standard electronic units and lack of complete and adequate circuit diagrams. It is clearly necessary to replace the instrument electronics by ILL standard units for more efficient use of the spectrometer and in order to avoid similar wasteful breakdowns in the future. IN11 - SPIN ECHO SPECTROMETER (J. Hayter and F. Mezei) Spectrometer construction was essentially completed by summer, and since then IN11 has been undergoing scientific evaluation tests. Both Soller guide and super- mirror polariser/analyser combinations have been used : the final installation will be a focusing supermirror system with longitudinal magnetization. Unlike the Soller guides, this has a vavelength-dependent polarization, but gives an intensity gain of a factor of 5 when optimised for the particular wavelength in use. Scientific evaluation have been successfully undertaken in four main areas : — coherent nuclear inelastic scattering (SrTi03) — Incoherent inelastic scattering including spin-flip processes (V2H20) • magnetic field compensation for the Interaction between the two arms of the spectiomoter • asymmetric Fourier scans to improve momentum as well as energy resolu tion (see figure 11). LI (counts) ,,!•«' A : r- l VU ~S\ : ': -,/\T /\ V V / V + 1 2 1 ; s i ; FIELD A5VMMcTF¥(fiHl lb) »<1) Fig. 11 - Fourier neutron spin-echo scan of the velocity selector spectrum aj Intensity vs. A H. the magnetic asymmetry between the two srms bj Fourier transform of measured data showing the beam spectrum Several external experiments were discussed for tentative scheduling at the Octo ber meeting of the Scientific Council. IN5B The concept of IN5B a new time-of-flight instrument in the X-iange 4.1 to 5.5 /•. (3 double curved Si monochromators in a 20 cm high guide, Fermichopper. 2 IT. flight path) has been started. The guide H15 was cut in October 1977 to accomo date the monochromctor. IN9 Work and development of the polarized proton filter has been stopped after having achieved the following performances : The 7 mm thick LMN crystal filter at 6.0 K can polarize a white beam of 3 x 3 cm. The filter transmits 28 % of an unpolarized X = 5 A beam yielding 83 % polarization with + 0.5 % stability over several runs of 10 days each. Co-ordlnator : R. SCKERM. instrument group "diffuse scattering' On the cold guide HIS : D7 Diffuse scattering spectrometer D11 Small angle and diffuse scattering spectrometer IN10 : Backscatterlng spectrometer On the cold guide H16 : D16 : Four circle Mk 6 diffractometer On the cold yuide H17 : D17 : Low-q, high resolution spectrometer On the thermal guide H24 : IN13 : New backscatterlng spectrometer for short wavelengths (design study started in 1977) D7 - DIFFUSE SCATTERING SPECTROMETER (TV. Just. K. Ibel. A. Murani) D7 was functioning with unpolarized neutrons from January 1977 to October 1977. The last reactor cycle of 1977 was reserved for experiments with polarized neu trons using a Heusler alloy-Cu2AIMn crystal as polarizer, a Mezei coll as neutron spin flip device and the dynamical flipping mode as an option for the measurement of the spin dependent part of a " time of flight " spectrum as In previous years. During the routine operation with unpolarized neutrons the main deficiencies of the Instrument appeared to be : — difficulties with alignment of the Incoming beam cfter wavelength changes (measures were taken during the Octobei shutdown to counter this problem). — for scans of the diffuse scattering pattern in the reciprocal space of a single crystal the present detector support necessitates several distinct angular dis placements in order to cover smoothly the angular range. — magnetic work suffers seriously from high background due to the tail cryostat of D7. Preparatory work for the change - ever from NICOLE to a PDP11 system was effected and first tests of real data and control link were performed. D11 - SMALL ANGLE AND DIFFUSE SCATTERING SPECTROMETER (G. Goeltz. J. Haas) Since April 1977. D11A and D11B have bean considered as one instrument named D11. In 1977 the incoming neutron guide was lengthened ; the diaphragms in the colli mator flight-path were aligned with a laser beam : the selector is now mounted on flat polished iron pieces allowing a more precise alignment. For transmission measurements the positions of monitor, counter and attenuator have been exchanged. On the IN12 side new protection walls have reduced the background for diffuse scattering and for the next positions of the multidetector (2m. 5m and 10m). During the long reactor stop in October the arrangement of the electronics in the control r-ibin was modified. Now the experiments can be controlled by the new PDP11/40 computer, beginning with the reactor cycle In November 1977. But the software still needs improving. New " time-of-fllght " electronics for the mul- tldctector are available (this also exists for diffuse scattering, but has not. yet been tested). A new chopper with a disk turning in vaccum will be installeo before the end of the year. D16 • FOUR CIRCLE MK6 DIFFRACTOMETER [G. Zaocai, S. Wilson) It Is the only diffractometer on a cold source guide at the Institute and it is conti nually being improved to cope with the increasing and varied demands which are made upon it. During the October shut-down, the rails on which it was mounted have bejn replaced by a Tanzboden element and air-pads. A change in wavelength Is nrvj much smoother and does not entail major realignment. Early in 1978, the monochromator shielding will be -eplaced. Different monochromators are under consideration, especially crystals with large spacing, which could reflect beams of wavelength greater than 6 A . Apart from experiments on biological samples and clays, 016 was used, in this past year, to study adsorption on surfaces, and chemical kinetics with a small one-dimensional multidetector mounted on the counter arm. Expansion of the computer system to use the extra memory is continuing satisfactorily. 017 - LOW-q, HIGH RESOLUTION SPECTROMETER (M. Roth, P. Timmins! D17 is a 2-axis spectrometer, with multidetector, for scattering experiments in the scattering vector range 5 x 10—3 A—t to 1.0 A —1, requiring high resolution. It is thus designed for studying high order diffraction peaks of large periodical structures. It can also be operated as a classical small an^le scattering spectro meter. The first measurements with this spectrometer wre made in September 1976. The main effort in 1977 has been to bring this apparatus into an easy and reliable state of use. This point seems now to have been reached. In addition a new velocity selector giving à FWHM wavelength distribution of 5 % with a high luminosity is now available (it supplements the first existing one with 10 % AtyA). This new selector can be used for neutrons with Y > 10 A . An effort has been put into the development of some new ancjllary equipment, mainly the adaption of an Eulerian cradle for crystal lographic experiments (at present only the movement is monitored by the computer), and the construction of a sam ple changer in vacuum for measurements on samples in controlled temperature conditions near room temperature. This also permits reduced background by remo val of the quartz window from the collimator exit and detector entrance. D17 is equipped with a PDP11-40 computer for controlling experiments and collect ing data. Some data reduction, treatment and display are possible Gn measured spectra. The computer is programmed in FORTRAN. A program is now available making easy the preparation of any series of experiments via a simple dialogue with the computer. The programs for data treatment allow the making of back ground corrections, transmission determinations, multidetector cell efficiency corrections, and data regrouping as a function of the scattering vector. A program for crystallographic experiments with the Euierian cradle (crystal orientation determination and positioning) is under development. IN10 - BACKSCATTERING SPECTROMETER (A. Heidmann, S. Howells) The backscattering spectrometer IN10 was working with hardly any Instrument breakdown (loss of beam time 1 %) in the period from January to October 1977. During the reactor shut-down In October 1977 a number of improvements have been made. A new support for the neutron guide between the graphite crystal and the sample was installed. The result was a IS % Increase in Intensity at the sample. The time needed for a change in wavelength was reduced from half a day to half an hour. Further improvements to the machine : a more precise system to guide the analysers, and a rigid connection between the branching-off guide hnd the analyser are necessary and planned for the next year. The "fast and transparent" Doppler drive has been under development for one and a half years. No great progress has been made until now due to a la'* of manpower and money. The standard DEC software RTII (Fortran language) was adapted to INIO within 3 months and has been running quite well since the beginning of the last reactor cycle. Some further improvements are necessary. INIO Doppler drive. IN13 - BACKSCATTERING SPECTROMETER FOR SHORT WAVELENGTHS (design study started 1977) (J.-L. Buevoz, A. Heidemann) The project of the high resolution backscattering inelastic spectrometer IN13 Is nearly completed. The mechanical solutions have been chosen with the aim of having a very versatile and automated instrument. A decision will be taken at the end of 1977 concerning the choice of the computer. The drawing of the different mechanical parts (special guide and its support, helium box, xy table for deflector movement) will begin soon in order to be able to cut the existing guide at the D6 position and install the monochromator part during the shut-down of October 1970, the analyser area being installed later. The work on electronics and programs will start as soon as the decision on the choice of the computer has been taken. Co-ordirtatar : A. HEIDEMANN instrument group "diffraction instruments" D1A High resolution powder diffractometer on thermal guide H22 D1B Multidetector on thermal guide H22 D2 High flux 2-axis diffractometer on thermal beam H11 D3 Two-axis polarized neutron dlffractometer with lifting counter on thermal beam H5 D4 Liquids diffractometer on hot beam H8 DS Three-axis polarization analysis spectrometer on hot beam H4 D6 High flux four circle diffractometer on thermal beam H11 D9 Four circle diffractometer on hot beam H3 D10A/E Four circle three-axis diffractometer on thermal guide H24 D12 Neutron cameras on thermal guide H23 D15 Four circle Mk6 diffractometer on inclined thermal beam IH4 D10 Neutron interferometer on neutron guide H25 D19 2D multidetector to be installed for tests on thermal guide H24 LW/5/7 X-ray laboratories G20 Neutron diffraction topography S21 High resolution double crystal spectrometer Amongst these Instruments all excepl D12, D18 and DIS have been fully sche duled throughout the year. Developments within the group have been directed towards improvement in the efficiency of use of the available neutrons and in Increasing the range of possible sample environments under which diffraction experiments can be done. Durnig the year experiments under stress, either uni axial or isotropic have been carried out on D1A, D15, D3 and D5. D12 has under gone considerable modification to enable Weissenberg photographs to be obtained at near helium temperatures. The use of low temperatures available from single stage cryorefrigerators Installed at D8 and D9 has continued to Increase in spite of some technical problems. Temperatures down to 8-10 K should shortly be available on D15 and using a two stage refrigerator and a new helium transfer cryostat on D10 should attain temperatures in the band helium range ; both of these retaining the flexibility of 4-circle geometry. To increase the efficiency in the use of the neutron beams improvements continue to bo made by increased use of focusing monochromators. Development of mul tidetector systems for which D19 is the prototype is being actively pursued and in such systems promise significant improvement in data collection rates in the future. High priority within the group is now given to replacement of CARINE by faster and more up to date diffractometer control systems. The prototype PDP11 system on D8 should undertake its first experiment before the end of the year and 1978 will see the development of a system on D1B aimed particularly at " reai time " experiments. D1A - HIGH RESOLUTION POWDER DIFFRACTOMETER (A.W. Hewat) The focusing monochromator (Freund, Howat & Hustache, Nucl. Instr. & Methods 1978). which was installed late in 1976, has made a big difference to the inten sity. For some problems, the flux is now even greater than available on D2, whilst the high resolution Is not reduced. A range of wavelengths from 1.1 A to 5.7 A can be rapidly selected by simple rotation of the focusing monochromator. Since this rotation is now encoded, the wavelength can be reset to a precision of AX/A = 10—4, so that calibration of each change Is no longer necessary. The new monochromator is particularly useful for work with very small samples, such os those used for high pressure experiments. For this type of work, a new single crystal sapphire pressure cell has been developed under a contract with the CNRS Grenoble Laboratory of Professor Bloch. With this cell, which at present will go to 10 kbar and a temperature of 5 K, most of the background features of polycrystalline cells ars suppressed. Development will continue in 1978 when Dr. C. Vettier becomes co-responsible. Other improvements were the commissioning of a much more reliable and flexible ILL cryostat, and a small crane for easier mounting of heavy equipment. The data roducticn package on the DEC-10 computer has been further improved, but the Carine control computer is increasingly showing signs of its considerable age. As well, without any technical assistance on D1A, more complex experiments and furiher improvements have become impossible. In fact, without more emphasis on the user program, it will be increasingly difficult to satisfy the high demand on D1A time (38 proposals in 1977). D1B - TWO AXIS DIFFRACTOMETER WITH MULTIDETECTOR (J.L. Buevoz (until 31-12-77), G. Bomchil (from 1-6-/7). P. Convert) D1B has operated efficiently all tile year, enabling experiments to be performod covering a wide field of structure analysis. A second menochromater (Ge 311) is F , ««*——~~ïT il >—ÏTr'-V i.fui'i! • . "v ./VW-**' i b^i—^*— /? R (!/• ".V*W! ••-«.. . '/,'/ h:, cj-'i l >. • 0* rf 4^/fc-v^Si X«- -•• XN. •$&••*$?• ' . i. ^-Â-^i.-.-aa^ai..^_ .^^i^ii - £*!&>&£ D1B in its new position. 42 now available with a wavelength of 1.3 À, but with a reduction In flux by a factor cf 4. During the October shut-down the geometrical setting of DIB has boen modified. The distance monochromotor-sample Is now 3 m instead of 4.3 m which provides a flux Increase of 50 %. In addition the take-off angle has been increa sed to 44° such that the graphite wavelength is now 2.5 A . This reduces the background by a factor of 4, for adsorption studies on graphite and eliminates the multiple scattering associated • with Bragg reflections for d = 1.23 A . A 15 cm high focusing Ge (311) monochromator for 2.5 A neutrons has been orde red for delivery in mid 1978. The new monochromator will increase the flux by a factor of 4 and alleviaia the X/3 contamination. The most important innovation concerning D1B is that a Solar 16.40 computer has been ordered. This will be a dedicated computer for data acquisition and instrument control permitting 800 data to be stored on disc and fast preliminary evaluation and comparison of data. The new computer will be operational in 1379 thus relieving the current limitations of the Carine system especially for kinetic studies. 02 • HIGH FLUX TWO AXIS DIFFRACTOM ETER (K.R.A. Ziebeck (up to 1-11-77) and C. Marti (from 1-11-77)) D2 continued to function satisfactorily throughout the year and maintained a heavy demand. The commissioning of D15 relieved most of the form factor single crystal experiments except those concerned with cri tical scattering. An increasing proportion of the experiments were concerned with surface studies or liquids. The choice of D2 for liquid studies has been its high fiux and improved resolution at small O. In order to further optimise these experiments o small linear detector is envisaged for 1978. For magnetic scattering experiments, a horizontal field. ST, superconducting magnet is expected to arrive eorly in 1978. D3 - TWO AXIS POLARISED NEUTRON DIFFRACTOMETER (F. Tasset and F.J. Brown) The high demand for D3 vvas maintained throughout 1977 and the diffractometer continued to operate effi ciently. Several programs have been written for the PDP11 which enable visitors to align their crystals more easily and without a detailed knowledge of the diffraction geometry. The programs on the DEC10 for analysing the D3 data, have been continuously up-dated as further improve ments were made to the measurement technique. It is now a simple matter for a visitor to process his data and obtain I a form factor before he leaves ' the Institute (see fig. 12). In ll T ^FHS** IS* IT , ,^?«t.-A. ïmbda FeCl2:Fe form factor form factor from b-axis data Fig. 12. - Form factor data obtained on D3. ."A'aw.1 *;_.'. • addition a completely new flipper has been developed and incorporated into 03. The new flipper makes use of the Meissner Effect in a superconducting Nb foil and the Majorama technique of flipping. The flipper which operates at 4.2 K provi des a stable highly efficient flipping ratio which is wavelength and field Inde pendent. D4 - TWO AXIS LIQUIDS DIFFRACTOMETER ON TJÎE HOT SOURCE (P. Chieux) Throughout 1977 D4 continued to operate efficiently. Improvements to the detec tor shielding and that of the environment of D4 have minimised the background. The introduction of a multidetector has significantly increased the effective neu tron flux and has enabled statistics of < 1 % to be obtained in a reasonable measuring time. Data collection is facilitated by two Texas Silent terminals, the cassettes being processed on tiie DEC10 computer. It is hoped in 1978 to have a direct link to the DEC10 via a concentrator. D5 - THREE AXIS POLARISATION ANALYSIS SPECTROMETER (J. ïïehweizer, D. Givord and K.R.A. Ziebeck from 1-11-77) œz&p; — """•™s8gg A wide variety of experiments were performed during 1977 which made full use of unique features of D5. The diver sity ranged from liquids and amorphous magnets to highly absorbent rare eartli compounds. The latter measurements on 8m and Gd compounds were possible because of the short wavelength pro vided by D5 and the reduction in the neutron absorption cross section with s^X wavelength. Several inelastic experiments i >y. *$ - have used polarised neutrons to distin guish between magnetic and lattice vibra k/i ( ^y I tions. The introduction of boron coated '•/ IV-i .;••. d", "f; Soller slits enabled measurements to be made on powder samples. The new electromagnet, with which the field may Wéï*j>m • -H be easily switched from the vertical to the horizontal direction, has greatly faci litated the polarisation analysis experi ments. To improve these measurements still further, a new shielding for the D5 seen from above In the analyser is currently being developed. "W" configuration. D8 - HIGH FLUX FOUR CIRCLE DIFFRACTOMETER (S. Mason and C. Riekcl) DB is now controlled by a PDP11./40 system including disc, Dectapes and Tektro nix display. The control system will-remain similar to those on D9 and D10 but 44 many new features will added. During 1978 we expect to test on D8 a linear detector (length one metre} which has a degroe of vertical resolution and is sui table for both single crystal and powder studies. The Displex 100 temperature refrigerator (T > 45 K) works well, especially since the addition of flexible transfer lines. Motor driven variable apertures for the a2 colllmation (between monochromator and sample will soon be Installed). D9 - FOUR CIRCLE DIFFRACTOMETER WITH SHORT WAVELENGTHS (M.S. Lehmann and G. Bentley) During the year D9 has been in routine operation and only minor modifications were carried out. The vacuum tube, connecting the menochromator housing to the exit at the reactor face, was replaced owing to radiation damage to the joints. A gas flow furnace constructed at the CNRS Grenoble has been tested and found to work successfully. Plans are in progress to construct a similar furnace, for temperatures up to 800°C, which will be available to ILL users. A new detector arm and shielding have been constructed and will be installed early In 1978. The new detector will move more rapidly thus reducing the setting time. During 1377 D9, which was constructed for single crystal diffractometry, was used briefly as a powder diffractometer. This type of experiment is not fore seen as a routine use of D9, since neither detector banks nor adequate Sollei collimator are readily available. CO A/B - HIGH RESOLUTION FOUR CIRCLE THREE AXIS SPECTROMETER (C. Zeyen and A. Filhol) Throughout 1S77 D13 continued to operate efficiently, with s high flux provided by the vertically focusing copper monochromator. A new detector shielding has become operational this year. The increased signal to background ratio has been especially useful for measurements of very weak scattering. For structural stu dies the influence of the high flux has been reduced by the Carine computer system, which is now far too slow for the diffractometer. More than one half the experiments in 1977 used the three axis mode of opera tion and it is envisaged that this tendency will increase. Many different types of sample environment are now possible on the D10 cradle, these include high and low temperatures, high pressures and uniaxial stress, as well as magnetic fields. D12 - NEUTRON CAMERA (A. Wright) During 1977 the low temperature Weisenberg arrangement was essentially rebuilt. The rotation table has been changed and a more substantial goniometer incor porated. The wall' thickness of the cryostat tails was reduced to minimise the background scattering. In addition to new layer line screens a major innovation was the development of a novel set of collimators. The collimators, which are essentially two concentric cylinders with radial apertures, oscillate about the film axis and permit only those neutrons diffracted by the specimen to impinge on the film. These improvements have enabled the magnetic super lattice of ma terials with complicated magnetic structures and small moments to be recorded. D1S - FOUR CIRCLE DIFFRACTOMETER ON AN INCLINED BEAM (M. Thomas) The lifting counter Is now controlled automatically within the Andromache crys tallography package of the PDP6. This enables crystals to be measured, In nor mal beam geometry, even if the zone axis Is Inclined by — 4° to the vertical. Therefore large ancillary equipment, for example superconducting magnets, can now be mounted on the diffractometer. The improvement has also optimised the measuring technique since it is now possible to automatically measure reflec tions in different layers. The working area around D1S has been Increased by extension of the platform thus enabling the spectrometer to be operated In comfort. In mid 1978 D15 will equipped with a two stage refrigerator mounted on the mark VI Eulerian cradle enabling measurements to be made in equi-incli- n.ition geometry, over the temperature range 10-300 K. D18 - NEUTRON INTERFEROMETER (W. Eauspiess, Schlndler and M. Schlenker (since October 1977)) In April 1977 the diffractometer bench for D18. manufactured at the Inst, of Phy sics Univ. Dortmund, arrived at the ILL and was installed in the D18 E position so that the mechanics could be tested. To demonstrate the high angular resolu tion of the interferometer axis, rocking curves of two Bragg reflections have been measured which show oscillatory structures In the range of 0.1 sec. of arc. In August an insulating room was constructed to contain the whole D18 area. This improved the thermal stability of the Instrument' by a factor of at least 4. The relative position of the monochromator and interferometer crystals do not now change measurably over a period of 12 hours even if the feed back control is switched off. LI4/5/7 (Y. Glaize and PJ. Brown) Owing to insufficient technical support there has been no further developments to these facilities over the past year. S20 - NEUTRON DIFFRACTION TOPOGRAPHY (M. Schlenker) A special Instrument, S20, is dedicated to neutron diffraction topography, an observation technique akin to X-ray topography which produces images of single crystals using Bragg diffracted neutrons. The original capabilities of neutron topography are related with the low absorption of neutrons by most materials and with the direct interaction of neutrons with the distribution of magnetic moments. This instrument, operated by a group fro m the Laboratoire Louls-Néel of the CNRS Grenoble, was used in investigations of growth defects in crystals contain ing heavy elements, hence too absorbing for X-ray topography to be feasible, and in studies of ferromagnetic and antiferromagnetic domain structures ; In the latter case, neutron topography Is particularly valuable because It is the only direct method of observation available, S21 - HIGH RESOLUTION DOUBLE CRYSTAL SPECTROMETER (C. Zeyon) S21 is situated on the thermal guide tube H24 and uses the waste beam of D10. Two nearly perfect crystals are arranged in the parallel focusing geometry. Extremely narrow reflection profiles fa few seconds of arc depending on the crystal quality) are obtained by either rotating the second crystal (u-scan) or by varying the temperature of the first crystal (temperature-scan). Both crystals are mounted Into cryostate guaranteeing very good temperature homogeneities. Temperature is controlled and measured with a precision better than 10—3 Kelvin. Thus very small lattice distortions acompagnying structural phaso transitions, lattice parameter changes induced by defects or impurities can be measured with a resolution of up to 10—6 depending on the crystal quality. Given the extreme temperature resolution this spectrometer is particularly suited for the measurement of critical exponents, scaling functions and the study of mul- ticritical points in order to check the predictions of renormalization-group-theory. The instrument can also be used for certain small-angle scattering experiments by placing the sample between the two parallel crystals. The spectrometer and the temperature regulation 2re computer controlled. Operated in collaboration with Dr. H. Meistor (Euratom, Ispra) the machine Is also mainly financed by this organizaticn. This year it has started to be sche duled for outside users. Co-ordinator : K. ZIEBECK instrument group "monochromators' D13A : Neutron double-crystal diffractometer en thermal guide H24 D13B : High precision neutron double-crystal dlffractometer on guide tube H24 D13C Neutron single crystal orientation unit on H23 LI 2A : X-ray double crystal diffractometer LI 2B : X-ray single crystal orientation unit Ll 3 : Gamma-ray diffractometer Laboratory for singis crystal orientation and preparation 1. - INSTRUMENT DEVELOPMENT D13A has carried cut its routine work as usual without major modifications, i.e. check of monochromator crystal efficiency and special experiments on samples before being studied on neutron spectrometers. The installation of D13B between D13A and 321 on H24 has been achieved and first expeiments of its performance with neutrons will be started soon. D13C has been installed, too, on the thermal guide H£3. Six nearly perfect Ge crystals with différant orientations mounted on a drum can be used alternatively ac moncchromators and provide a 6 cm high monochromatic neutron beam with out second order contamination. This beam height, which is not available on D13A. permits a much more rapid alignment of vertically and/cr horizontally focusing multi-crystal monochromators than on D14A. At present minor parts of the construction are being finalised and first experiments are foreseen for Janua ry 1978. On the y-dlfiractometer L13 the support of the deformation device at high tem peratures was modified. It has thus become possible to control the maximum mosaic spread used mostly in the horizontal direction of hot-pressed Ge and Si monochromator crystals during the anisotropic deformation process instead of the minimum mosaic spread. 2. - DEVELOPMENT OF MONOCHROMATOR MATERIALS The success rate at the production of Ge and Si menochromator crystals has been improved, especially at low deformations where the mosaic structure was still somewhat non-uniform, by varying the rate of applied stress during the hardening process. Si crystals in particular now present a very homogeneous dislocation distribution. These crystals deform in a more uniform way because of their homogeneous defect structure before deformation. Tests of their effi ciency for cold neutrons are in progress in order to replace pyrolytic graphite. Several beryllium single crystals have been grown in the Max-Planck-lnstitut filr Metallforschung, Stuttgart, Germany, and tested at the ILL for optimization of the growth parameters. With increasing amounts of impurities the mosaic spread became less uniform whereas small amounts of Cu seemed to homogenize the mosaic structure. The thick bars have also been studied by neutron topography for selecting large nearly perfect subgrains for subsequent iu-beam plastic defor mation. The a- p transformation Is being investigated with the aim of Improving the subgrain structure by a special cooling procedure. Finally, a feasibility study of pyrolytic graphite menochromators with variable lattice spacing has been undertaken. 3. - COMPOSITE SYSTEMS AND BENT CRYSTALS A series of tests for curving thin plates of Si and Ge perfect crystals by a chemical procedure aiming at higher curvatures than achieved up to now has been carried out. Based on positive results a set of 15 crystals is being treated for the construction of a composite focusing monochromator. Germanium crystals with anisotropic mosaic spread have been produced in order to asssnible a 16 x 9 cm2 vertically focusing monochromator for IN8 allowing the variation of the radius of curvature during the experiment. The vertical mosaic spread of the (W)-oriented plates is 5 minutes whereas the horizontal one is about 30 minutes. Uased on the first successful application of the vertical Focusing technique for neutron diffraction experiments at D10 another diffraction instrument (D1A) has been equipped with a composite system of 28 Ge crystals 14 x 5 cm2 in dimen sion. Here the anisotropic mosaic spread (4 minutes vertical, 18 minutes hori zontal) is of great advantage for focusing efficiently. The gain in intensity without subsequent loss in resolution was such that the intensity at D1A is now compa rable to the intensity at D2 which is installed on a beam tube close to the reactor. The development of large, vertically focusing monochromators with anisotropic mosaic spread has completely changed the philosophy of neutron guide tube exploitation, especially for thermal guide tubes. Gut vertical focusing will also lead to a large gain in intensity for slow neutrons. A 21 x 15 cntf horizontally and vertically focusing Si monochromator is under construction for IN5B. 4. - DIFFRACTION STUDIES OF IMPERFECT CRYSTALS The dislocation structure of Cu single crystal which have been deformed under different conditions is being studied In more detail combining electron micros copy, Y-rav and neutron diffraction and topography in order to understand better the diffraction properties of monochromator crystals with isotropic and anisotrcpio mosaic structure. This work is carried out in collaboration with Oxford University. As a first result, the total attenuation coefficient |i has been determined as a func tion of neutron wavelength and of mosaic spread. Whereas the dependence of u on the mosaic spread is negligibly small, Its wavelength dependence came out to be a strong one in the thermal region. The experimental data obtained with Cu and Si could be fitted rather well, by a formula describing the combined processes of inelastic scattering, capture and multiple scattering in a first approximation. Fig. 13 represents the results for several neutron monochromator materials at room temperature. More detailed and temperature dependent investigations are in progress. -—^ / \~~\ ftCul .X \ ^s^^_-^^' \ / vs. / / \\\ A-MlNt/ J .•/ A \L_^ e.oi y \ /^ <^S. \ / / \ \ / \ / X/iitel y / A „ \ / Fig. 13. • Linear coefficient): of nuclear absorption (\i^) and total attenuation (p) as a function of / / ^^X^' neutron wavelength fcr different / /\ rr.onochromator materiats. /|U INM / \ - A / / X-- / //iAISil / / /*A«*> / . ,/ , , , ,/, 02 03 05 07 1 Wavelength [A] Neutron diffraction patterns of nearly perfect Si and Ge crystals have been studied in the asymmetrical Laue case. The observation of a very high peak reflec tivity of 80 % compared to 50 % In the symmetrical case was theoretically explained using a relatively simple model and dynamical theory. Co-ordlnalor : A. FREUND 50 colleges introduction All the internal scientific activity of the Institut is grouped Into " colleges ' with particular scientific interests. The following is the current list of colleges : College 2 Theory College 3 : Fundamental and Nuclear Physics College 4 Excitations College 5 : Structures College 6 : Liquids, gases and amorphous materials College 7 : imperfections Co'oge 8 : Structural biclogy College 9 : Ciemistry Each Collene corresponds to a Subcommittee of the Scientific Council of the ILL, which advises the directors on the scientific programme. New research pioposals submitted to the ILL will first be examined by the Colleges with respect to their technical feasibility and then be presented to the Council. A further task of the College is to contribute to a smooth carrying-out of the experiments by appointing local contacts and by advising the instrument responsible as well as the Scientific Secretary on the time schedules for the various instruments. Experimenters have corne to I.LL. from these research centres or universities ICELAND Reykjavik AUSTRALIA Canberra AEC Lucas Heights Monash DENMARK New South Wales Atrhus Queensland RIs* Sydne' AACHEN BERLIN BIELEFELD BONN JAPAN UOCI1UM Hiroshima BH, Kyoto JiMl Totioku BRTMUND Tokyo HANKFURT FREIBURG <-.ANACA /GARCHING Chalk River GIESSEN Guelph GGTTINGEN Kingston HEIDtLBERG McGIII Ghent à JÛLICH Liège * USSR New Brunswick fÊAUX KARLSRUHE Louvaln Ottawa " BREST KÔLN Baku MOL . Toronto CEA-SACLAY KONSTANZ Dutaj CEA-FONTENAY MAINZ tflngrad USA CEA- GRENOBLE MARTINSRIED Moscow Argonne CEA-CADARACHE MÛNCHEN RigB Bell Labs DIJON MUNSTER Brookhoven GRENOBLE •fADERBORN HUNGARY Boston IEGENSBURG LE MANS ludapest Burnham LILLE SAARBRÛCKEN California LYON STUTTGART Evanston MARSEILLE TUBINGEN Florida METZ Idaho MONTPELLIER Illinois NANCY Indiana NANTES Iowa Sofbjrsdcrf NICE Harvard Vienna PARIS Houston PASTEUR • INST. ; Alamos POITIERS RENNES Massachu! ROUEN Michigan ST-ETIENNE Missouri STRASBOURG New York TOULOUSE Oak Ridge VILLEURBANNE Ohio Philadelphia Yale INDIA PORTUGAL IVORY CCA! Madras Coimbra Abidjan Trambay ISRAEL Beer Sheva 52 college 2 theory" MEMBERS OF THE COLLEGE : VISITINC3 SCIENTISTS : Brack M. Barber M. (New South Wales) Burkhardt T.W. Béal-Monad M.T. (Orsay) Derrida B. Caslalng (ENS, PARIS) Fogedby H. Eisenriegler E. (KFA, Jûlich) Haldane F.D.M. Fischer K. (Jûlich) Hinkelman H.J. Ford G.W. (Univ. of Michigan) Iche G. (CNRS! Gautier F. (Strasbourg) Johnston R. Jennings 13. (Stony Brook) Loveluck J.M. Lavis D.A. (London) Lovesey S.W. Leggeit A. (Sussex) Nozières P. Lindgard PA. (RisjO Schuck P. Mcnyhard N. (Budapest) Sherrington D. Schofield P. (Harwell) Southern B. rhouless D. (Birmingham) Theumann A. Toiilouse G. (ENS. PARIS) Young F. Wallace D. (Southampton) Zawadowski A (Budapest) (Tills list does not includes short visits of a few days) The Theory College has continued to concentrate its effort in the field of condensed matter physics, but there are now two members of the group working in nuclear theory. SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 The year has seen a continuing effort In several already established fields (e.g. phase transitions and critical phenomena, spin glasses, static and dynamic pro perties of one-dimensional magnets), together with ventures into some new areas, such as the study of mixed valence systems (Haldane, Sherrington) and both the magnetic ordering and lattice dynamics of quantum crystals (Béal-Monod, Cas- taing, Nozières). These new interests partly reflect changes in college member ship, and are partly the result of a development of existing interests. The effort in noclear physics has now been increased by the addition of a second nuclear theorist (Brack), and, supported by a number of visitors in this field, a success ful Interaction with both ILL experimentalists and nuclear theorists at the Institut des Sciences Nucléaires has developed. A striking feature of recent developments in theoretical physics is that many of the concepts and techniques are applied to s wide variety of appa'ently rather different problems. While this provides an underlying unification of different bran ches of theoretical physics, it also frustrates a description of the activities of the theory group in terms of traditional subject classifications. For example. within the group, real space renormalization group methods have been applied to a number of different problems : in the field of spin glasses, to compare the effects of dilution (percolation) and the competition between ferro- and antiferro- magnetism (" frustration ") by Southern and Young, to discuss the surface critical behaviour of the Ising model (Burkhardt, Eisenriegler) and to calculate the surface free energy of Islng-type models (Burkhardt, Southern). The renormalization group approach has also been applied to study non-critical effects, such as the theory of bifurcations (Derrlda), the description of long time - long wavelength correlations in Heisenbarg paramagnets (Fogedby and Young) and in a study of the tempera ture dependence of the spin wave stiffness for a model ferromagnet (Lovesey), while other aspects of the dynamical behaviour of liquids (Lovesey) Heisenberg paramagnets in the hydrodynamic regime (Fogedby and Young) and one-dimen sional magnets (Loveluck and Lovesey) are related by a description In terms of a generalized Lanoevin equation and the idea of mode-coupling. Other aspects cf scaling theop/ have found applications In the Kondc problem (Haldane, Nozières) and in a study of the asymmetric Anderson model (Haldane), which was shown to exhibit universal behaviour, with two interesting limiting cases - the " mixed valence " and " Kondo " limits. Furthermore, apparently unifying themes sometimes cover a diversity which is only resolved by consideration of the methodology rather than the system studied. For example, the heading of one-dimensional magnets covers work on the 1D XY model (Fogedby), using field-theoretic techniques previously applied to a model of a ID electron gas, and, a completely different aspect, development jf a sto chastic equation to study the spin dynamics of s 1D Hcisenberg magnet (Loveluck and Lovesey) which is based on mode-coupling theory. Similarly, some aspects of mixed vaience systems were elucidated by the scaling approach to the asymme tric Anderson model, mentioned above, but other aspects, such as the role of electron-lattice coupling, have been investigated by a completely different approach by Sherrington. The apparently unifying theme of 3He also embraces such diverse aspects as the study of two dimensional itinerant spin systems (Béal-Monod), as a model of helium films, the spin ordering of both 3D and 2D solid 3He (Béal- Monod), which has possible connections with spin glass ordering, and the lattice dynamics (vacancy dynamics, melting mechanism, etc.) of solid 2He (Castaing. Nozières). Besides the renormalisation group approach to spin glasses, mentioned above, further work on disordered systems has included consideration of some exactly soluble models of quenched disordered systems (Sherrington), a 1D spin glass model incorporating some essential features of previous studies in a more trans parent context (Theumann). and some preliminary work on excitations in disorder ed magnetic systems (Sherrington). A study of surface effects in the order- disorder transition of binary alloys was also completed by A. Theumann. In the field of nuclear physics, work continued on semiclassical theories of nuclear matter (Brack, Schuck), with the inclusion of the effect of correlations, while work on the time-dependent Hartree-Fock method for the description of nuclear fission and fusion (Schuck) Has also been extended to the theory of fis- slon-fragment mass distributions (Brack), which is d'reclly relevant to ILL expe riments. Much of this work was done In collaboration with B. Jennings and P. Ring both of whom visited the ILL for over a month. VISITORS, SEMINARS, WORKSHOPS AND CONFERENCES As In previous years, the group has greatly benefited from visiting scientists, listed above, partly through direct Interaction with the research programme of the group, but also by the influx of new ideas and themes which such visits pro vide. Many of these visitors have been extremely valuable in keeping the group in touch with recent developments In rapidly evolving fields, such as the renorma- llsation group approach to critical phenomena (visitors in this field Included Barbor, Toulouse, Wallace and Zawadowskl) and the study of spin glasses (Fischer, Thou- less). The group also profited from the sabbatical year of Prof. G.W. Ford, in particular from a number of seminars on topics with the general themes of non linear perturbations and stochastic différentiel equations, with applications for example to rotational Brownian motion. The Theory College has participated In the seminars on theoretical physics, organised by P. Nozlères, which provide a valuable contact with other theoreti cians in the Grenoble area. The seminar continues to be a very successful forurn, and this year almost forty talks were given, covering both topics in which the ILL Theory Group has active" research in'.erasts, as well as other topics which are currently attracting attention In theoretics; physics, for example, super- fluid 3He and both surface magnetic and chemisorptive properties cf transition metals. A 3-day workshop on " Recent Developments of Semlc'assicai Approaches in Nu clear Physics " was held in November, organised by M. Brack and P. Schuck. The programme Included invited speakers from Saclay (A. Votros, B. Grammeticos), Orsay (O. Bohigas, J. Treiner, H. Krivlne), Stony Brook, New York (B. Jennings), Berkeley, California (B. Myers) and ISN Grenoble (M. Bouyssy), as well as the ILL organisers. The active participation of nuclear physicists from the Grenoble area ensured a very lively and successful meeting and provided an excellent forum for the exchange of ideas. Secretary : J. M. LOVELUCK college 3 '"fundamental and nuclear physics" INTERNAL AND EXTERNAL MEMBERS OF THE COLLEGE Avenler M. Hawerkamp K. Almeida J. Hungerford P. Asghar M. v'euch P. Barreau G. Jung G. Bauspiess W. Kaiser W. Blachot J. (CENG) Koglln E. Blakeway S. Larysz J.R. Bocquet J.-P. !CENG) Mampe W. Borner H. (Jûïich) Monnand E. (CENG) Brack M. Nifenecker H. (CENG) Braumartill F. Pcrrin P.E.J. (CENG) Byrne J. (Sussex) Rehfield D. (Giessen) Cavaignac J.-F. (ISN) Risto'i C. (CENG) Chan/et J.-L. (ISN) Schrader H. Crançon J. (CENG) Schreckenbach K Davidson W.F. Schussler F. (CENG) Decker R. (Giessen) Schuck P. Do Huu Phuoc (Lyon) Siegert G. Von Egidy T. Smith K. (Sussex) Emsallem A. (Lyon) Trlnks U. (Bonn) Greene G. (Harvard) Vlgnon B. (ISN) Gust C. Warner D. Hamilton D.W. (Sussex) White D. (Oregon) Wûnsch K.D. (Giessen) VISITING SCIENTISTS Armbruster P. (GSI Darmstadt) Leroux B. (Bordeaux) Bauchiat C. (Paris) Miller P. (Oak Ridge] Boehm F. (Pasadena) Môssbauer R. (Munich) Chery R. (Lyon) Moreh R. (Beer Sheva) Crawford G.I. (Glasgow) Miinnich F. (Braunschweig) Dakowski M. (Saclay) Muller K. (Munich) Denschlag H.O. (Mainz) Paul W. (Bonn) D'Hondt P. (Gent) Pendlebury J. (Sussex) Engler G. (Soveq) Ramsay N. (Harvard) Finch E. (Dublin) Rauch H. (Vienna) Forte M. (Ispra) Reines F.W. (California) Golub R. (Sussex) Robson J. (McGill) Greif J. (Giessen) Signarbieux C. (Saclay) Hagberg E. (CERN Geneva) Suffert M. (Strasbourg) Hoff R.W. (Llvermore) Van Assohe P. (Mol) Jonson B. (CERN Geneva) Wilson R. (Harvard) Kienle P. (Munich) Wagemans C. (Mol) Kobisk E. (Oak Ridge) Weirauch W. (Braunschweig) Kratz K.L. (Mainz) Wollnik H. (Giessen) GENERAL SUMMARY Experiments have been performed in the following fields of nuclear and funda mental physics. 1) The fission process was studied with the mass spectrometer for fission products LOHENGRIN (PN1). with the on-line mass separator OSTIS (PN6) and at the Intense neutron beam IH1. 2) Detailed and high precision Investigations of the nuclear structure are perfor med at the beta spectrometer âILL (PN2), at the crystal spectrometers for gamma rays GAMS1 and 2/3 (PN3), at the pair and anti-Compton spectrometers (PN4) and at the thermal neutron beam H22. Nuclear spectroscopy measurements on fission products were carried out at LOHENGRIN and OSTIS. Neutron induced par ticle emission ((n.c.) and (n, p)) is investigated at the thermal neutron guide H22. 3) The fundamental physics programme comprises measurements of the neutrino cross-sections and the searcn for neutrino oscillations, the half-life of the neutron, the magnetic moment of the neutron and the search fur the electric dipole moment of the neutron. Ultra-cold neutrons and cold neutrons were applied. A search for parity violation in hadronic interaction and tests of time reversal invariance are carried out at the polarized cold neutron beam (PN7). 4j Nuclear methods are applied to atomic physics at BILL and GAMS and to solid state physics at the thermal neutron guide H25. Altogether 103 experiments have been performed. They are given in detail In 79 accepted proposals which were selected from 113 proposals submitted in 1977. SCIENTIFIC TRENDS A programme was started in 1976 to use the anti-neutrino flux of the reactor to determine cross-sections for neutrino induced reactions (inverse p -decay) and to search for neutrino oscillations. New experiments have been devoted to the box (above the two people), to which 2 experiments are connected. The upper guide leads to the magnetic storage ring for ultra^old neutrons locsted In the cylindrical container on the right of the picture. half-life and to the electric dipole moment of the neutron. It was possible fur ;r. first time to store neutrons in a magnetic field for more than 20 miri. The search for parity violation in hadronic processes will continue with special emphasis re establish not only lower limits but definite values in simple nuclear systems. The main research activity with the beta spectrometer SILL and the gamma spec trometer GAMS is devoted to nuclear spectroscopy in the actinide region in order to establish new nuclear structures. In addition, this high precision nuclear spec troscopy is aiming at the detailed study of levels at higher excitation energies. In nuclear fission experiments were started to investigate yields of mass and nuclear charge in the fission valley and in the heavy fission product group and to look for isomer formation. EXPERIMENTS CARRIED OUT IN 1977 1) Nuclear fission experiments performed with the rrass separators for fission products LOHENGRIN and OSTIS and with special experimental arrangements. a) LOHENGRIN : The yield of spin isomers in fission was studied as a function of kinetic energy of the fission products. This permits a correlation to be established between the spin and the excitation energy of the fission fragments. Isomers in the (isec region are measured on-line, isomers with half-lives above 0.1 sec are transported with a tape to the measuring position. This tape transport facility was used also to mea sure the nuclear charge distribution of fission products with the radiochemical method in the light wing of the heavy group. By comparing Y-ray spectra taker, at lohengrin and at Ostis the nuclear charge distribution could be deduced in the heavy wing of the heavy group. To cover the heavy group completely, the develop ment of nuclear charge and mass sensitive detectors was continued. Promising results have been obtained from a gaseous absorber and from a silicon A -E-detec- tor each followed by a tlms-of-flight system. The application of the collision- Induced X-ray emission was followed further or, and the emitted p -particles (indicating a change of nuclear charge) were counted in a surface barrier detector to test this method. The programme to investigate the response function of surface barrier detectors was continued with measurements of the plasma delay time. b) OSTIS : The yield of Rb and Cs isotopes from fission was measured with a standard Ostis source containing about 2 g of 235U. The necessary corrections for the delay time in this ion source have been applied. In addition a very small ion source containing only 2 mg of 235U was developed. It could be shown thai the delay times are in the range of 5 to 15 msec which is much less than the shortest half lives. Therefore no corrections are necessary and the yields can be measured directly. c) SPECIAL EXPERIMENTS : Detector arrangements have been used to measure special modes of neutron induced fission of 23SU like a-particle accompanied fission, fission and simulta neous emission of two alpha particles and fission at very low excitation energy i.e. without neutron emission. 2) Nuclear Spectroscopy High precision nuclear spectroscopy.on nuclei excited by neutron capture was performed by the beta-spectrometer BILL, the gamma spectrometers GAMS, the anti-Compton and pair spectrometers and by special experiments at neutron beams. Nuclear spectroscopy on fission products was done at LOHENGRIN and OSTIS. a) Beta spectrometer BILL : Energies and spins of levels have been determined with the (n, e) reaction for N)9Pd, iS2,i54Eu, issGd, i<*£r, i«Yb, i99Pt and 235LI. The neutron binding energies of H4Cd, '65Dy, <68Er and 2i"Hg were measured with an error of about 10-5 (3100 eV). A direct measurement of M1 admixtures in the stop-over transitions in a Y-vibra- tlonal band (i68Er) was performed for the first time. The admixtures were measured from three such transitions via the L subshell ratios of the conversion electron lines. A M1 admixture is in contradiction to the model of a superfluid nuclear matter. In 235U many p -, v- and octapole vibrational bands have been Identified for the first time via the multlpolarities of the transitions. Strong E0 components were found in the transitions from the p -vibrations. The continuous p -spectrum from fission products produced by 225U (n, f) was measured. The result will be used to calculate the anti-neutrino spectrum from fission products and from the reactor. b) Gtmma spectrometers GAMS and pair and snti-Compton spectrometers : Level schemes in the isotopes loapd, 1303a, i«Sm, i53.tS3Gd, i°BEr, '^Os. 20»Hg, "27Ra, 23'Th. 23su and 25°Bk were deduced with the help of precise gamina spectra of these nuclei. In <45Sm a correlation between primary gamma intensities from (n, Yi and (d. p) strengths was established, indicating direct capture mechanism. In the case of iS5Gd and <68Er extensive y-data have been taken to explore the region of highly excited intrinsic states. 1940s was measured for the first time by exploiting to the full the combination of the high neutron flux plus the sen sitivity of the y-spectrometers. The prolate-oblate shape transition of the Os isoto pes was followed up to 19HOS which becomes a truly oblate rotor. From a mea surement made in 1976 together with Ge (Li) data from Brookhaven, a succession of nuclear levels could be established in ospt, which was predicted recently by the interacting boson approximation with the symmetry subgroup 0(6). The level structure of 'SSPt is believed to be the first example of this symmetry. The (n, Y)- spectrum of 22?Ra has been measured for the first time. This is one of the few nuclei accessible by (n, Y) techniques in the transitional region between 209Bi and 230Th and unusual vibrational states are expected. c) LOHENGRIN : The program to determine 0» values in the range of low yield fission products was continued successfully. The decay of spin isomers of fission products was examined. di OSTIS : On Rb and Cs fission products available at Ostis a wide variety of nuclear spec troscopic measurements have been carried out. Half-life determinations were made and the new isotope '^Cs was identified. Gamma- and conversion electron spec troscopy was performed to deduce energies and spins of nuclear levels of very neutron rich nuclei. High precision measurements of O» -values have been niede with an intrinsic Ge-detector with errors between 5 and 50 keV. Energy spectra of delayed neutrons have been taken by measuring the time of flight of the neutrons and by using 3He spectrometers. These energy spectra show pronounced structure. e] Special experiments : A facility was developed to measure Y-Y angular corre lations after neutron capture. First measurements were performed on i6i.i63Dy targets. A dilution refrigerator was operated at a temperature of 30 mK. It can be used now to measure on-line directional distributions of Y-rays from oriented nuclei. An experiment especially designed to measure the cross-section for one and two photon decay after neutron absorption in 3He was carried out. 3) Beam Experiments Using Nuclear Reactions a) Charged particle emission after neutron capture : The (n, a ), (n, Yo), (n, p) and [n, yp)-reactions were performed with S (natural sulphur), 4°K, Zn, i52,i55,is7Gd, 2093j, and 235U targets. In addition, the radioactive target nuclei 37Ar. ?6Br, '°=Cd (produced by the ISOLDE facility at CERN, Geneva) and 93Mo (produced aï the Lyon cyclotron] were used. After preliminary data evaluation the crois-section in the 235U (n, a) 232Th reaction seems to be much smaller than reported in the literature. The total (n, a) + (n, p) cross-section for 37Ar is 2040 ± 200 b. This is the highest cross-section -after '"B (n, ti) and 3Ke (n, p). b) Scattering length : With the neutron interferometer D18 the scattering lengths of H, 2H, 3He. N, O, Ne, Ar, Kr and Xe have been measured. The data set is currently analyzed. 4) Nuclear methods applier! to atomic physics and to solid stele physics. a) Atomic physics : the energy shift between the i — Range distribution and diffusion of 10B implanted in Si02- it was found that the mean projected range is 10 to 20 % higher whereas the straggling is 10 % lower than predicted by theory. The diffusion coefficient is much lower than expected. The diffusion of H>B in Si was measured separately for comparison with the known diffusion of "B in Si to get the mass dependence of the diffusion coefficient. — The concentration profiles at Si/Si02 boundaries (which are used in microelec tronic devices) were measured as a function of oxidizing conditions, inert annea ling, temperature and crystal orientation to deduce the segregation coefficient (the concentration of 1»B in Si02 compared to that in Si). Firs; results indicate that the segregation depends on the time of oxidation and whether dry or wet oxida tion was used. 5) Fundamental Physics a) Neutrino physics : To measure cross-sections for anti-neutrino induced reactions, and later to look for neutrino oscillations, detector prototypss were constructed (ISN, Grenoble) and background measurements were made. The detector will be Installed in the base ment of the reactor where the background from the reactor is very low and the cosmic rays are shielded by the concrete and water of the reactor. b) Properties of the neutron : The experiment to measure the magnetic moment of the neutron was completed. The precision has been improved by a factor of 100. The ratio of the magnetic moment of the neutron to that of the proton is now (In/up = — 0.68497945 (17). An experiment was set up and is progressing well, which stores the protons from the neutron decay by a combination of electric and magnetic fields in order to determine the half-life of the neutron. c) Parity violation : The programme to search for parity violation in hauronic processes has been continued. Nuclei are oriented by capture of polarized neutrons. A large asymme try effect of (4.4 + 0,6) 10—4 i.e. parity violation was found in the reaction i"Sn (n, Y) "BSn. A similar investigation for the reaction 35CI (n, y) 36CI is currently under way. Mors information on those experiments can be found in the Annexe to this Annual Report {separate volume). SEMINARS, WORKSHOPS AND CONFERENCES In 197V the fundamental and nuclear physics college organised 31 seminars, dea ling with nuclear structure, fission, heavy ion collisions, atomic and fundamental physics and the application of nuclear methods to solid state physics. Visiting scientists (S. Balestrini, R. Casten, H.G. Clerc, M. Dazowski, G. Engler, A. Gizon, W.D. Hamilton, R.W. Hoff, J. Lieder, B. Leroux, R. Moreh, P. Quentin, F. Reines, t. Hoeckl, D. White, H. Wollnik) contributed with 16 seminars. 15 talks were given by physicists from Grenoble (H.G. Borner, M. Brack, F. Braumandl, W.F. Davidson, R. Decker, J.P. Desclaux, A. Gizon, C. Guet, K. Hawerkamp, P. Jeuch, W. Mampe, E. Monnand, K. Schreckenbach, F. Schussler, K.D. WQnsch). Four workshops have been organized by the ILL in this college in 1977. The first was held 19 Jan. on "Future Fission Research at the ILL". The need for a fission product separator for coincidences betwen fission products and a -particles, neu trons and Y-rays at an external neutrons beam was pointed out in this workshop. On 17 June a workshop on Neutron Optics and Ultra-Cold Neutrons was organi zed. Ten participants came from outside, and about 25 ILL physicists participated. In cooperation with CEN-Grenoble a meeting devoted to " Nuclear Fission " was held on 29th and 30th Sept. About 50 physicists attendad, roughly one half of them being from the ILL. A workshop on "Fundamental Physics Experiments with Reactor Neutrons and Neutrinos " was organized by the ILL on 10 and 11 Oct. The workshop was atten ded by 37 participants from outside Grenoble and by about 40 physicists from the ILL, ISN and CENG. Theory and experiments of properties of the neutron, of parity violation and time reversal invariance and of neutrino physics were discus sed. Special emphasis was put on future experiments to be performed at the ILL. Secretary : G. SIEGERT college 4 ""excitations MEMBERS OF THE COLLEGE I - EXPERIMENTALISTS, ILL Suck J.B. Copley J.R.D. Wagner V. Currat R. Ziebeck K.RA. Dorner B. Escribe C. Fitzgerald W. II - THEORETICIANS AND EXTERNAL Ghosh R. Castets A. (CNRS) Jenkin G. Coey M. (CNRS) Joffrin C. (L.lii. Saclay) Fogedby U.C. Lechner R.E. Loveluck J. Lefebvre J. Lovesey S. Pynn R. Rossat-Mignod M . (CENG) Scherm R. Southern B. Stirling W.G. Villain J. (CENG) GENERAL SUMMARY As its name suggests, the work of College 4 is concerned with studies of the elementary excitations of solids and with their interactions. The principal sub ject subdivisions, as used by the ILL for administrative purposes, are : 04-01 : Lattice dynamics (essentially phonon dispersion curves and phcnon- phonon interactions) 04-02 : Dynamics of structural phase transitions and electron - phonon effects 04-03 : Magnetic excitations and magnon-phonon effects 04-04 : Dynamics 'A magnetic critical scattering. The College has approximately 25 members of whom 14 are engaged actively in experimental work at ILL, the others being external members or theoreticians. As in the past, most of the experimental work has been performed using triple-axis crystal spectrometers (INI, IN2, IN3, IN8) but some experiments use diffracto- meters (D5, D10, D12) and time-of-flight and high-resolution instruments (IN4, IN5, IN10). In the last year the triple-axis instruments have operated adequately, in general, but all continue to suffer from unacceptable time losses due to a combi nation of the Carine computer, a d.o. motor positioning system and somewhat outdated electronics. It is hoped that improvements to be implemented on the cold-neutron spectrometer IN12 will provide the basis for a new control system. IN12 has a step-motor " central-drive " system and is to be connected to a dedi cated SOLAR 16/40 computer. In Table 1 are given the totals of experimental periods, listed by instrument, for the period October 1976 to October 1977. The distribution of experiments is very similar to that for 1975-1976. At the meetings of March and October of 1977, the members of Subcommittee 4 considered a total of 96 proposals of which 62 were allocated beam time (not Including short test experiments). Table 2 lists these proposals by category ; for comparison the figures for 1976 are also given. Overall there is little obvious change from 1976 to 1977 except that the total number of "phonon " proposals de creased somewhat with a corresponding Increase In the "phase transition" category. At the March meeting the problem of the performance of ILL triple-axis spectro meters was raised. Although general satisfaction was expressed, it was sta ted that there was obviously room for improvement, particularly in shaft-posi tioning and computer control. Since that time an expert committee within the Institut has been studying the former of these problems, it is to be hoped that considerable improvements will result from this study. It was noted at the October meeting thrt there continues to be a lively interest in phonon dispersion curve measurements, particularly for molecular crystals. SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 In the field of molecular crystal dyna mics, it is interesting to note the success of an experiment on IN3 to measure in detail the dispersion curves of deutera- ted naphthalene [1]. Figure 14 pre sents the dispersion curves for two reciprocal space directions, principally at 98K but with some 5K data. These results are considerably more complete than previous measurements. The data is to be compared in detail with sophisti cated model calculations and future work on naphthalene will be concerned with the temperature and pressure de pendence of the phonon frequencies and widths. For this programme, workers from Russia, Poland, West Germany. Bri 05 CM 03 0.2 0] 00 0.1 02 03 Oi 05 tain and the ILL are collaborating. M * 1- Another unusual dispersion curve mea Fig. 14. '{Expérimental dispersion curves surements is that on p -Gallium [2]. of dcuterated naphthalene IIN3). (the lines are guides for the eye} Since the jî-phase is metastable. the crys- tal was grown in situ on a motorlsed 4-circle goniometer inside the cryostat ; parti cular care was necessary to maintain accurately the sample temperature and to protect the crystal against mechanical shocks. Rather complete dispersion curve data were obtained on IN2 for frequencies below 2.5 THz. There continues to be current interest in the lattice dynamics and phase transitions of perovskites represented by experiments on NaNb03 [2], KTN [4] and KTa03 [5]. The latest IN10 measurement of the "central peak " width in SrTiO [6] shows that no line broadening is observed within an experimental upper limit of 0.05 (ieV over a temperature range of more than 10° above and below Tc. Lead phosphate, Pb3(P04)s, has a rhombohedral high temperature phase and exhi bits a ferroelastic phase transition at 1B0°C to a moncclinic structure. Soft modes have been observed [7] at both fundamental Bragg peaks and at superlattice posi tions. A precise study of the linewidth of the latter soft mode is soon to be per formed. Another ferroelastlc material under study is 3b507l[8], which exhibits strongly temperature-dependent quasielastic scattering at the superlattice positions. Turning to materials where electron band effects play an important role, we should mention the elegant experiments on lead tin selenide, Pb,_, SnxSe [9]. Using a horizontally curved analyser on IN3, the low frequency [001] modes were studied as a function of temperature and concentration. A clear dip was found at 40K, for a tin concentration of 20 % in both the frequency and the linewlrith of the zone-centre transverse optic mode of lowest frequency. This effect has been related to the band inversion which occurs at that temperature. As in previous years, magnetic Inelastic IUSb BKI i PHONONS scattering continues to provide new and t R KiSNcTC exciting information. For the first time, a spin-wave excitation has been obser ved In a metallic actinide compound, USb [)0]. The dispersion curves, both phonon and spin-wave, are shown in Figure 15. H As well as the spin-wave excitation, b which decreases in frequency with de 4 - creasing temperature an exciton or .__j2_—-^-'-:/_-_. crystal-field transition has been observed t at about 6 THz. Further work is neces ~ ~ sary to determine the polarization of / those magnetic excitations. / v-*-/ ' \u - ?• ;* >' fa, - In recent years there has been a consi /LA derable interest in the behaviour of A' J- »• \ magnetic excitations In systems of low -? S »\ \ dimensionality. Although the one-di AV mensional Helsenberg antiferromagnet TMMC ((CD )„ NMnCI ) has been stu , . N S 3 C2 OA 05 , a,s at died In depth by neutron methods, it is only recently that the effect of impurities [ooO QKO] on the ordering has been considered. Fig. 15. - Experimental dispersion curves In TMMC containing paramagnetic cop of uranium artimonlde (1N81. (The lines are guides for the eye) per [11], it is found that the spin- waves develop a large width at wavevectors smaller than that corresponding to the Cu-Cu distance. There is also some evidence which suggests that in this case the spin-wave dispersion curve does not go smoothly to zero frequency, but rather develops an energy gap at zero wavevector. The first measurements on a dilute two-dimensional ferromagnet, K2Cu,.xZn,F4, have recently been performed [12]. Both the frequency and linewidth of the ma gnetic excitations are affected by the presence of the non-magnetic impurity. Excellent agreement was obtained between the experimental results and the pre dictions of a continued fraction calculation for low concentrations, while at higher impurity concentrations the calculation slightly underestimates the excitation fre quencies. Many neutron measurements have been made on the itinerant antlferromagnet chromium, usually alloyed with a transition metal. A recent IN8 experiment has studied the Magnetic excitations as a function of temperature in pure chromium [13]. In a series of constant energy scans through the satellite positions, the magnetic inelastic intensity was found to increase with temperature up to a maximum at ~> 331 K, some 20 K above the Néei temperature. Moreover a discon tinuous change in the intensity was observed at 301 K, consistent with a first order introduction of a band gap. The latest in a series of experiments on ordered ferromaonetic ?d3Fe concerns the behaviour of the [111] direction spin-waves as the temperature is raised through the Curie point (Tc~ 500 K) [14]. The spin-waves exhibit a large soften ing and damping, but, in contrast to the situation in iron and nickel, no well-defined opin-waves were observed above Tc in the paramagnetic phase. Of necessity, the above account constitutes a subjective, but reasonably repre sentative selection from the large number of College 4 experiments performed at ILL during the last year. It is to be hoped that it indicates the type of " exci tation " research at present being undertaken at the Institut. WORKSHOPS. CONFERENCES AND SEMINARS As usual, many of the Tuesday and Thursday seminars treated the physics of condensed matter. In addition, during 1977 the 3-axis group met regularly each Wednesday for informal seminars and discussions. Secretary : W. STIRLING 6 EXPERIMENTS CITED ABOVE [1] Naphthalene : Bokhenkov, Corner, Kalus, Mackenzie, CioD8 Natkanlsc, Pawley, Schmelzer [2] P-Ga Boslo, Cortes, Copley, Teuchert [3] NaNb03 Denoyer, Lambert, Currat, C. Joffrin [1] KTaNb03 Cowdille, J. Joffrin, ZIolkiewicz, Currat KTN [S] KTa03 Parry, Buhay, Currat [6] SrTI03 Heidemann, Hayter, Axe, Mezei p [7] Pt>3( 04)2 C, Joffrin, Currat [83 Sb507l Frettl, Wagner [9] PbSnSe Vodopyanov, Scherm [10] USb Under, Stirling [11] TMMC Renard, Boucher, Fitzgerald [12] K2CuZnF„ Wagner, Krey [13] Cr Booth, Ziebeck, Escribe [141 Pd3Fe Cowley. Hilton, Stirling TABLE VI Instruments used for experiments in 'he College "excitations" (October 1976 - October 1977) Instrument : INI IN2 IN3 . Il Number of experimental periods : 8 20 18 1 15 3 1 1 TABLE VII Number of proposals submitted to the meeting of the Subcommittee "Excitations" in 1977. J March 1977 October 1977 1976 Category Submitted Accepted Submitted Accepted Submitted Accepted 04-01 14 11 23 12 48 32 04 - 02 13 9 15 10 19 15 04- 03 13 9 14 9 31 20 04 - 04 2 1 2 1 Totals 42 30 54 32 98 57 college 5 "structures' MEMBERS OF THE COLLEGE Mason S.A. Overs T. Aldebert P. Riekel C. Bartunlk H.D. Savarlault J.M. Toulouse Bauspless W. Dortmund Schlenker J. Bentley G.A. Schwelzer J. CENG DRF/DN Bomchil G. Soubeyroux J.L. Bordeaux Brown P.J. Tasset F. Buevoz J.L. Thomas M. Burger N. Tlmmlns P. Choel V. Oxford Trost W. Convert P. Vettler C. Croset B. Wilson 8.A. Feld R. Wolfera P. CNRS Grenoble Filho! A. CNRS Bordeaux Wright A. Fitzgerald W. Zeyen C. Freund A. Zlcbeck K. Gardner P. Givord D. Graaff VV-. Dortmufid Gregory A. VISITING SCIENTISTS Hermann-Ronzaud D Hewat A.W. Costa M. Coimbra, Portugal Jenkin G. Elriksson V.R. Iceland Lehmann M.S. Lander G. Argonne, USA Leslie M. Oxford Olovsson G. Uppsala.Sweden Marti C. Olovsson I. Uppsala,Sweden GENERAL SUMMASÏ During 1977 the range of instruments used by members of the college has remai ned unchanged, though most of them have undergone some improvements as outlined in the section of the report devoted to diffraction group instruments. The college has made a major effort during the year to improve both the ease of use and the documentation of programs associated with crystallographic com puting. There now exist new documents describing the college 5 data reduction system, the Cambridge crystallography subroutine library, and a set of routine programs for 4-circle diffractometers. Programs from other centres which have been adapted to run on either the DECtO or the CDC system are : the constrained refinement program ORION of Andre. Foure and Reaud and the multipole refine ment program MAUDY from Buffalo. A start has been made on a new program •o determine conditions for multiple Bragg scattering from single crystals taking the diffractometer resolution into account. SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 Interest within the college in the determination of electron densltiea by compa rative X-ray and neutron diffraction studies remains high. Investigations have been carried out on pyridine n-oxlde trichloracetic acid, pyridine n-oxlde cobalt 2-perchlorate and para-nitro pyridine n-oxide. These are aimed at following the charge density around N02 groups as a function of chemical environment. A rather simpler system currently being studied by the same methods Is hydrogen peroxide (H202). Within this general area of interest some members of the college are taking part in the International Union of Crystallography project to assess reproducibility in the determination of charge densities. The compound being studied by the participants is oxalic acid. At ILL a set of integrated Inten sities has been collected on OS at 0.84  and on D15 at 1.16 A , both at 100 K. ' Comparison of the two ripta sets pin-points problems due to multiple scattering in the aligned zone-axis normal beam geometry used on D15. In the attempt to increase the spatial resolution of diffraction studies, data col lected with high momentum transfer at short wavelengths is becoming more and more important. In such measurements a proper subtraction of thermal diffuse REFLECTION 220 3i PERFECT CRYSTAL ooo K 7 MM THICKNESS 2000 1 000 (- 8.00 Fig. 16. - Rocking curve for the reflection 220 from a plate of perfect Si crystal in Laue Geo metry f A = 0.60 X ). The intensity of the elastic scattering from a perfect crystal is inde pendent of crystal thickness (if the crystal is sufficiently thick), whereas the thermal diffuse scattering is proportional to the amount of material in the beam, so in principle the thermal diffuse scattering can be obtained from rocking curves of two crystals with diffe rent thickness by subtraction. The reflection 220 is near the focusing position and the thermal diffuse scattering is clearly visible as tails on the elastic peak. (Graf, Schneider, Lehmann and freur.d) scattering (T.D.S.) is essential if the thermal parameters obtained are to have any physical meaning. Efforts are now being directed to ways of improving the TDS correction. A recent study of a perfect silicon crystal on D9 at 0.6 A enables the evolution of the TDS as a function of sin 8 A to be seen very clearly {Figure 16). In the field of protein crystallography measurements on a single crystal of trlcli- nic lysozyme begun in 1976, were completed to d-spacings below 1.5 A during 1977. Least-squares programs, for the refinement of individual atomic parameters for all atoms, are being implemented. These programs make exteri"- sive use of a fast Fourier algorithm. Studies of polycrystalline materials also continue to develop strongly. The availa bility of a new high temperature furnace has enabled the ceramics La203 and Nd2C3 to be investigated up to 2200°C on DIB. Three different phase regions have been identified and the structures of the three phases elucidated. Several hydrogen bonded systems have been studied using high resolution powder dif fraction on D1A. For example, new measurements on DADP have more clearly revealed the mechanism of the anti-ferroelectric transition from the behaviour of the anisotropic thermal ellipsoids in both phases. High pressure measurements on KDP and DKDP have shown how the hydrogen bonded P04 groups rotate with pressure in these ferroelectric materials. Both phases of douterated rcsor- clno! and acetanilide have been refined with up to 13D structural parameters, and with sufficient detaii to reveal molecular libratiens. The refinement of five phases of ND4N03 represents the most complete structural study yet mads of the series of transitions in this rather difficult material. Other problems still under attack include the phases of solid methanol and the transition in n-methyl aceta- mlde. Recent successful studies of phase transitions in inorganic materials are illustrated by Pb304, CsPbCI3, Na^^Og and KjSnCI6. A significant part of the scientific effort of the college is in the field of magne tic materials. D1B continues to be widely used for magnetic structure determi nation in cases where only polycrystalline material is available. The very high sensitivity obtainable with the D1B multidetector is illustrated by the determi nation of the magnetic structure of CeAL^. In this compound it was possible to measure the very small magnetic peaks associated with the magnetism of cerium in a complex spiral structure. The study of the complex antiferromagnetic structu re of VI2 using the low temperature Weissenberg camera D12b demonstrates the unique possibility offered by the photographic technique for the rapid and unambiguous determination of magnetic propagation vectors. This magnetic struc ture determination forms part of a larger programme aimed at a fuller under standing of magnetic interactions in layered transition metal haiides. Work done up to the present has included studies of the magnetisation densities in CoCI2, FeCI2 and CrCI3 in their field induced ferromagnetic phases. It Is hoped that such systematic studies of chemically similar and isomorphous materials will lead to a better appreciation of the forces involved in inter and intralayer interactions in these compounds. The programme of work on rare earth transition metal alloys has been continued in 1977. A polarised neutron study of TbCo2 has been carried out which enables the temperature dependence of the susceptibility of cobalt to be determined above and below the ordering temperature ; this dependence resembles more closely a Curie-Weiss susceptibility than that expected for the previously accep ted model of internal field motamagnetism. The study of the Laves phase alloy HoFe2 has allowed the holmlum ground state. In the presence of both crystal field effects and holmium-iron interactions, to be determined. In this alloy strong reflections with large polarisation ratios are observed which suggests that it may be possible to develop new and better polarising monochromators using them. In the Pauli paramagnet YNi5 the polarisation of the 3-d band induced by a 48 Kce applied field has been observed. It Is found that the induced moment is very different on the two distinct crystallographic sites. In TbNi5 the rare earth inter actions polarize the 3-d band and it Is hoped to compare the spatial distribution of the polarisation in this case with that of YNi5. The diminution of the absorp tion cross-sections of Sm and Gd at short wavelengths has enabled magnetic scattering in SmCo5 and GdMg to be studied using neutrons of wavelength <0.5 A available at D5 by virtue of the hot source. In SmCc5 the samarium wave func tion has been determined and shows an important admixture of terms coming from the first excited [ J = 1/2> multiplet. In GdCo5 the observation of a canted magnetic moment on S-state ions in a cubic field implies the existence of higher order exchange interactions as well as the Helsenberg coupling. New cryoflipper and Js: j\ # superconducting ms- _J gnet on D3. 70 Polarisation analysis has been used as a supplementary technique In magnetic structure determination and gives evidence for a canted structure In Mn4N. In NiS2 the superstructure lines have been shown, by this technique, to have both nuclear and magnetic contributions. A study of the polarisation of the conduction electrons in the metallic phase of V02 under 48 Kce applied field has been made, taking advantage of the high sensitivity of the polarised neutron technique. The corresponding magnetisation density Is significantly non-spherical in character. If this density is interpreted as corresponding to the charge density of conduction electrons then it shows that there are electrons at the Fermi-surface in all three sub-bands of the vanadium T2g manifold in disagreement with recent band models. SEMINARS. WORKSHOPS and CONFERENCES There was a workshop called : "Workshop on Magnetic Structures and Spin Densities " on Oct. 10th and 11th. 1977 The workshop had the following main topics (a) Methods of magnetic structure determination (b) New techniques in magnetic structure determination (c) Magnetisation densities (d) Magnetisation and the chemical bend Under each topic two or three invited speakers wore asked to give a review of the state of the art in their particular areas of interest. Tin res' •-' *he sessions were left open for informal presentations and discussion. Under topn. 'a) parti cular attention was given to the ambiguities that can be inherent in magnetic structure determinations. In topic (b) information on a wide variety of new tech niques was presented : these included the photographic Laue technique for study of magnetic domains, magnetic topography, polarisation analysis and classical photographic techniques applied to magnetic structures. Session (c) was devoted to the study of magnetisation densities in rare earth and actinide compounds ; considerable interest was shown In new techniques for obtaining the groundstate wave functions of rare earth metals from polarised neutron measurements. The final session was devoted to the kinds of investigations aimed at measuring délocalisation of magnetisation density brought about by chemical bonding ; topics discussed varied from very simple systems such as transition metal halides: through garnets to much more complicated chemical problems such as manga nese pthalocyanine and Cobalt II porphyrin. Taken as a whole the workshop pro vided a welcome forum in which ideas on the current status and future prospects for studies of elastic magnetic scattering were exchanged. J. BROWN college 6 "iiquids,gases and amorphous materials' MEMBERS OF THE COLLEGE : Jal J.F. Klein M. Lechner R.E. Besnard M. Lovesey S.W. Blêtry J. (Univ. of Grenoble) Poncet P.FJ. Chieux P. Pynn R. Copley J.R.D. Ranninger J. (CNRS) Cyrot F. (CNRS) Richardson R. Dcsre P. (Univ. of Grenoble) Seherm R. Dianoux A.J. Stirling W.G. Dupuy J. (Univ. of Lycn) Suck J.B. Heidemann A. Tliorel P. (CNHS) Hilton P. (Univ. of Edinburgh) Volino F. (CNRS) Howells W.S. Wright A.F. GENERAL SUMMARY The emphasis within this college is on neutron diffraction and neutron inelastic scattering experiments on various types of liquid and liquid crystal. Relatively little work has been performed on gases and amorphous materials. Of the key words listed in the keyword list for College 6 (oee end of the annual report), all but 6 - 06 (molten salts) were represented in proposais submitted this year. F'roposals in categories 6 - 03, 6 - 04 and 6 - 07 have up to new been structure studies, whereas the liquid crystal experiments (6 - 09) have been investigations of dynamical processes. Proposals in the remaining categories include both- struc ture and dynamics experiments. Of the diffraction instruments, D4 is exclusively used by College 6, and a large fraction of D2 time goes to the college. The machines D1B, D5. D7. D11 and D17 are also used. On the inelastic side the triple-axis machines IN1, IN2, IN3 and INS are employed occasionally, IN4 is used to a limited extent, but the main demand falls upon the high resolution spectrometers IN5 and IN10. In the 12 months ending December 1977, 63 experiments from College 6 were carried out. In March 1977. 32 proposals were submitted, of which 28 were accepted ; 22 of them were given reduced time. The corresponding figures for October were 30, 25 and 9. This change reflects the fact that in October several instruments were either undersubscribed, or only slightly oversubscribed. SCIENTIFIC TREND!". AND HIGHLIGHTS IN 1977 We shall briefly review some of the work that has been carried out during the past year. Quantum Liquids There is a continuing programme of research into the properties of liquid helium, and in particular 3He and 3He-4He mixtures. This year, a technically demanding 72 experiment has been performed to study the pressure dependence (from 0 to 20 bars) of the scattering from 3He at 0.7 K. The low frequency spin density scatter ing at wavevectors of order 1 A —1, becomes stronger with increasing pressure, whereas the higher frequency mass density fluctuations decrease in intensity. At about 2 A —1 the frequency at the peak decreases dramatically with increasing pressure. Attempts to explain this behaviour in terms of a pressure-dependent effective mass indicate that the mass changes more with pressure than is expec ted on the basis of macroscopic measurements. Monatomic Liquids, Binary Liquids and Molecular Liquids The neutron diffraction studies of liquid rubidium at low densities have recently been extended to temperatures as high as 1970 K and densities down to 0.6 g/cin^, i.e. 40 % of the density of normal liquid rubidium at 312 K. A preliminary analysis of these measurements indicates that in the density range 1.2 to 0.6 g/cm3 the nearest neighbour distance only Increases by a few per cent, but the number of nearest neighbours decreases by roughly a factor of two. This work is to be continued next year. Inclaslic scattering measurements on rubidium and aluminium were performed this year, using both triple-axis instruments and the time-of-flight spectrometer IN4. The IN4 results for liquid aluminium at two temperatures are 'fairly extensive, and a preliminary aanlysis shows that there may be collective excitations at OB 1.5 A —I. An experiment to examine the pressure dependence of both the self and distinct parts of SCQ,u>), for liquid argen, is being undertaken on IN4 at the time of writing. In the field of binary alloys, there has been an active programme of research, making extensive use of both isotopic substitution and concentration variation techniques. Work on Cu-Sb alloys has been completed, and the Li-Na system has been investigated close to the critical composition of 65 atomic per cent Na. Alloys with a tendency to ionic behaviour, such as Cs-Sb, have been examined, as well as systems which tend to segregate [e.g. Ag-Ge). A general aim is to try to deepen our understanding of these relatively simple binary mixtures, and to learn why it is that some segregate and others form compounds. A soft sphere model of alloys, proposed by a member of the College, may well help in this respect. A number of rather complicated liquids, such as CD3COOD, CDCI3 and CD-OD. continue to be studied using the Isotopic substitution technique, as well as pola rization analysis, and comparison with X-ray resuits. For the first time, the three leading terms in a spherical harmonics expansion of the orientational correlation function have been obtained for a molecular system, namely acetonitrile. It may be possible to obtain a larger number of terms in the expansion of the case of chloroform. Comparisons with model calculations should then be very fruitful. Progress has also been made in our understanding of the inelasticity corrections to the coherent part of the scattering from simple molecular liquids such as nitrogen, in part as a result of detailed comparisons between D4 data and data from the Harwell linac machine. The emphasis is now on more difficult mole cules such as D20 and DBr. Aqueous Solutions In previous work It was unambiguously shown that for concentrated solutions of NiCI2 In D20, the hydration number of the Ni?-*- Ion is six water molecules. The experiments have now been extended to two quite different solutions : NaCI in D20 of molality 5.32, and CaCI2 In D20 of molality 4.47. In spite of the different characteristics of the cation, the nature of the hydration around the anion is essentially the same in both cases (5.5 + 0.2 water molecules). This shows that a once and for all calculation of the coordination characteristics of the Ion- water system will be a good approximation, appropriate to a wide range of solutions. Glasses The kinetics of devitrification of Ti02 nucleated alurnino-silicate glass have been observed in situ at 1100 K by neutron smail angle scattering. The controlled sepalation of particles (believed to be ALaTi05! reaching a maximum radius of 120 A , regularly disposed in the glass with an interparticle radius of — 600 A, occurs only after a preliminary nucleating heat treatment at *•• 1050 K has been given. The mechanism followed is that of nucleation and growth rather than spi- noda! decomposition. Heat treatment at i 100 K, without the nucleation procedure, leads to uncontrolled crystallization with separated particle sizes exceeding 500 A . In each case an induction period of 30-40 minutes precedes the mcin growth curve, which appears to saturate after 3 hours. Liquid crystals During 1977 considerable effort has been devoted to an unambiguous test of the Meyer-tViacMliian theory for the tilted smectic phases. This microscopic tneory predicts an orientational ordering of the moieci.'les around their long axes, linked to the existence of a strong dipole-dipole interaction which is itself res ponsible for the tilted character of these phases. Earlier measurements in the H phase of TBBA, by incoherent quasi-elastic scat tering, failed to reveal any orientational ordering. Furthermore the elastic incohe rent structure factor (EISF), i.e. the ratio of the elastic incoherent intensity to the total intensity, showed that the motion in the normal H phase had to be more " isotropic " than uniaxial rotation, implying an additional motion which has been attributed to (anisotropic) fluctuations of the long axes. A more detailed study of the supercooied H phase (smectic Bc), and of the Vi phase (smectic Ec) of TBBA has now been undertaken. The EISF and the quasi- elastic lineshapes were analysed in terms of two models which permit orienta tional order about the long axis. Values for the orientational order parameters < cos0 > and < cos2cr >, for the polar and bipolar models respectively, were then extracted (Figure 17). !n the normal and the supercooled H phase, < cos 0 > = cos < 20 > = 0, as expected. For the VI phase the neutron data cannot discriminate between the two models. The model with two sites, where the molecules are allowed to flip by n . is however more consistent with X-ray diffraction results. Incoherent quasi-elastic neutron scattering experiments on aligned samples of smectic B and smectic E phases of iBPBAC have suggested that long range Fig. 17. - Values of the order parameters < cos o > and < cos 2o > as a function of tempera ture for TBBA in the supercooled H and VI phases : N = 1 t.nd A,' = 2 correspond respec tively to the polar and bipolar models described In the text. The corresponding mean angular fluctuation amplitudes A o are indicated for each case. The Sat VB j 5m VI j Unes through the points are drawn as guides to the eye. BO 911 100 r [iC] transiational diffusion constants In these phases are less than 10—?cm2s—1. Analyses of the scattering from faster components (correlation time i 10—10s) of the molecular motion have shown that current models for these phases are not wholly adequate. The conventional view that there is uniaxial rotational dif fusion about the long molecular axes which Is Isotropic in the smectie B phase, but restricted in the smeciic E, has been confirmed. However it has also been shown that there is an important diffusive motion In a direction perpendicular to the layers. The amplitude of this motion increases with temperature until the smectic layers are lost in the nematic or isotropic liquids. Critical Scattering There has been a detailed investigation (| T-Tc|/Tc as small as 10—*) of the criti cal exponents Y and v , both above and below the critical temperature for liquid- liquid immiscibility, in the K-KBr system. When Droperly corrected for density effects (density being extracted from neutron transmission measurements), these exponents are in accord with results based on the lattice gas-model. On the other hand the critical exponents measured for the alkali metal - ammonia system, which also displays a non-metal to metal transition as a function of metal concen tration, are more of the mean-field type. One is led to speculate that there may be different classes of non-metal to metal transition. SUMMER SCHOOL A highly successful NATO Advanced Study Institute, on the Microscopic Struc ture 3nd Dynamics of Liquids, was held In Aleria, Corsica, during the summer. The school was strongly supported by the ILL, financially, scientifically, and admi nistratively. About 10 ILL scientists participated. The Proceedings are to be published. It is a pleasure to thank P. Chleux for his fine work as College Secretary over the past two years. Secretary : J.R.D. COPLEY college 7 "imperfections' MEMBERS OF THE COLLEGE : Korblein A. (Univ. of Heidelberg) Kostorz G. Lechner R.E. Anders R. Mezei F. Bletry J. (CNRS. Grenoble) Murani A.P. Dorner B. Rotii M. Escribe C. Scheuer H. Preund A. Schweizer J. (CENG) Givord D. Schorm R. Goeitz G. Suck J.S. Hayter J. Wagner V. (Univ. or Wiirzburg) Heidemann A. Wright A. Holtjans P. (Univ. of Heidelberg) Young A.P. Hewat A. Zeyen C. Just W. Ziebeck K.R.A. The College has 27 listed members of whom about 10 ars more actively involved in the scientific programme of the college i.e. act most frequently as Iccal contacts for experiments falling within the domain of the college. The other members have their primary activities linked with other colleges. GENERAL SUMMARY The scientific activities of the college have been divided into the following groups, which partially overlap In some cases : 1 Mixed magnetic systems, i.e. magnetic impurities, alloys 2 Crystalline electric field including valence states 3 Non-magnetic defects and disorders 4 ln-beam NMR experiments 5 Inelastic scattering associated with defect states 6 Diffusion in bulk materials 7 Superlonlc conductors The experiments falling within the above groups have been carried out on the instruments listed in the table below, which gives the number of instrument days for each instrument used by the college during 1977 and the corresponding number of experiments. IN1 IN2 IN3 IN4 IN5 IN7 INS IN10 D1 D5 D7 D9 D10 D11 D17 Inst, days 18 - - 24 22 24 - 17 6 15 60 6 32 20 2 No. of expts. 2 — — 4 5 3 — 3 1 1 8 1 2 10 1 The following table gives the statistics of proposals submitted and accepted for College 7 during 1977 March 1977 No. of proposals No. of proposals Subgroup submitted accepted 01 1G 13 02 8 4 03 16 14 04 1 1 OS 1 1 OS B 2 P7 2 2 Totals : S3 3V Cctober 1977 No. of proposals No. of proposals Subgroup submitted accepted o-i K 1< 02 T C 03 5 ù 04 — OS 3 3 06 14 10 07 S C Totals : 48 43 SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 The scientific trends during the year appear to be towards an increasing interest In the study of spin glasses, both metallic alloys and amorphous systems, and also in the study of rare earth systems whose physical properties suggest the interconfiguration fluctuation behaviour or the intermediate valence state. The general scientific activities of the college may be best illustrated by the follow ing brief review of a few of the experiments carried out during the year. 1. Mixed magnetic systems, i.e. magnetic impurities, alloys Diffuse scattering study of Fe-Ni alloys containing 30-35 % Ni with unpolarizcd neutrons show evidence of chemical short range order and inhomogeneous ma gnetisation, but the exact relationship between the two is still unclear. It was found, however, that after Irradiation with fast electrons pseudopehodic magne tization inhomogeneities are produced, which are through* to be connected with a kind of chemical spinodal decomposition (Chambrold, Billard, Roth). Small angle neutron scattering measurements on Co-rich Co-Ga alloys have been per formed by Cywinski, Booth and Ralnford. These show that the critical composi tion for ferromagnetlsm is around 55 at.% Co, and the alloys with lower Co concentrations (50 Spin glasses continue to provide subjects of Interesting research. Low tempera ture inelastic scattering from a Cu-5at.%Mn alloy show dispersionless inelastic peaks which -the authors, Scheuer, Loewenhaupt and Suck, have attributed to spin- wavo-like excitations. Fur'her measurements to verify these findings are in pro gress. The separation of elastic and inelastic scattering from a Cu-8at.%Mn alloy using high resolution energy analysis («•I u,V'on IN10) show that the Edwards- Anderson order parameter for a spin glass is strongly dependent on the time constant of measurement; the results obtained here (with T-10—9s) being mar kedly different from those obtained earlier on 1N5 where the elastic energy resolution was ~ 200 uV and the corresponding T-10—1's) (Murani and Heide- rrann). It has long been known that very high concentration Cu-Mn alloys develop atomic and magnetic short range order around the [1, 1/2, 0] type positions. A systematic investigation of the short range order in a Cu-45at.% Mn alloy has been started by Coles, Ralnford, Burke and Givord using the polarization analysis technique on DS. The results obtained so far indicate that the magnetic short range order persist!; well above the freezing temperature and that field cooling the sample leads to a dramatic decrease of the spin-flip scattering cross-section. Another investigation of a concentrated spin glass with short range order is the study of spin dynamics of a disordered Pd3Mn alloy by Lilley, Rainford, Stirling, and Ziebeck, who plan to continue this investigation with higher energy resolution on the IN10 spectrometer. The temperature and field dependence of magnetic short range order in amorphous spin glasses such as Alj,Mn3Sis012and AI2Co3SI3012 have been studied by Prandl, Knorr, Nagele, Convert and Buevoz. In the former sample where the Mn ions have negligible local anisotropy and which the authors call the Helsenberg spin glass, magnetic short range order Is observed at rela tively high temperatures whereas in the latter sample where the Co2+ Ions have strong local anisotropy. and therefore the system termed an Ising type, the magnetic short range order was observed only at the very lowest temperature of 3K. 2. Crystalline electric field including valence states A knowledge of the crystalline electric field parameters of rare earth systems is essential to the understanding of their magnetic properties. With this aim in view, an investigation of the CsCI structured compounds of Co, Pr, Nd with Mg and Ag was undertaken by Morln, Pierre and Schmidt on IN7. They have also studied the influence of cooperative Jahn Teller effect of the crystal field level scheme in the compound TmZn. The influence of magnetic rare earth Impurities on the transition temperature of superconductors is determined principally by the low-lying crystal field states. The latter have been investigated for dilute concentrations ofTb and Pr solute atoms in LaAg, LaAI? and LaSn3 superconductors by Hoening and Loewenhaupt on the D7 spectrometer. A systematic study of the dynamical 'susceptibility of several interconfiguration fluctuation (ICF) compounds such as TmSe, CePd3, CeSn3, YbCu2Si2 and others has been carried out by Holland-Moritz. Loewenhaupt, Steglich, Wohlleben. Just and Suck, who find a broûd temperature Independent quasi-elastic scattering line- width for all the ICF systems whereas the normal magnetic rare earth system? have a linewidth which is two orders of magnitude smaller and linearly depen dent on the temperature. Other measurements on related systems include those on YbCuAl by de Boer, M&itens, Lander and Murani who find a quasi-elastic peak at high temperatures but which develops into two inelastic peaks at low tempe ratures. These measurements bear strong resemblance to earlier measurements on CeAig by Murani, Knorr and Buschow. There again the low temperature scat tering showed inelastic structure, thought to be due tc two crystal field transi tions, but which collapsed into a bread quasi-elastic peak at higher temperatures. 3. Non-magnetic defects and disorders Several experiments on non-magnetic defects, clustering, decomposition of alloys, and radiation damage have been carried out during the year, mostly involving smali angle scattering. The kinetics of decomposition in Al-Zn alloys was studied in-situ by Allen, Ste wart, iviessoloras, Guyot, Laslaz and Kostorz especially above and below the spi- nodsl temperature suggested by other workers. They found only a gradual nhange In the aging kinetics and in the form of small angle scattering when crossing this temperature. Another spinodal system Au-Pt was tsxarr.inod by Singhal, Her man and Kostorz using liquid- and solid-quenched samples. The solid-quenched alloy (Pt - 4u°.'oAu} showed rapid aging at 550fi C whereas the liquid-quenched alloys displayed slower aging in the bulk but also discontinuous precipitation at grain boundaries. Investigation of Al-Mg single crystals by Dauger, Boudili and Roth has shown non-isotropic and non-random configuration of Guinisr-Prcston zones in the alloys after aging at room temperature. A study of the formation of voids in quenched p'-NiAl has been completed providing detailed information on the size and shape of voids after various heat treatments (Epperson. Berner, Ortiz, Gestenberg and Kostorz). Among the investigations of defect scattering the continuing work (Roth) on some aspects of scattering by superficial tarnishing layers is also very interesting. This follows earlier observations of strong surface contribution to small anglo scattering from Al-Si alloys (Kostorz) and solids in general such as glass, alumi nium and vanadium (Roth). 4. In-beam NMR experiments The in-beam spectrometer S6 (Heidelberg group) has been used for studies of atomic diffusion by p-radiation detection of the spin-lattice relaxation of SLi in JJAg alloys. Recently simitar studies have been started in jj-silicate glasses (Muller-Warmuth) and in LiNbOa. The transfer of polarization from probe nuclei to the nuclei of the host (cross-relaxation 1 has been observed for Bj.i in L! metal, Lif, LiNb03 and for SOF in MgF2. The quadrupoiar and dipoisr couplings of pola rized 28AI nuclei in Al203 end .*\1P have also been measured down to 1.6K. S. Inelastic scattering associated with defect states Magnetic dlpole transitions have been observed by neutron scattering from Co2+ Ions In MgO using the !N4 TOF spectrometer by Wagner and Koldl. The measu rements show that the fine structure of the crystal field ground sate of the C02+ in MgO is due to electron phonon interaction which may be described in terms of a dynamic Jahn-Teller effect, giving rise to the two observed vlbrionlc levels. G. Diffusion in bulk materials Measurements of self diffusion of vacancies in Na single crystals have been continued on the IN10 spectrometer by Sc-eger, Mehrer, Goeltz and Heldemann. The diffusion constants for the different vacancies agree well with results of tracer measurements. A detailed data analysis, however, showed that the neutron results are not in full agreement with theoretical predictions of Wolff based en the migration of mono and dl-vacancies. Further measurements to supplement and verify these findings are planned. The physics of hydrogen in metals such as Pd continues to remain an interesting area of research. Measurements of the Debye-Walier factor of aPdH carried out by Rcos, Anderson and Carlilc show a systematic difference between the two crystal directions {200} and (220) even at low q's, suggesting either that the proton is not resident in a central position on the octahedral s'te or that higher order tiern-s of the Debye-Waller factor are large. The same authors have inves tigated diffuse scattering In p Pd-D in order to understand the specific heat ano maly at 50 K in the system. They observe that a peak in the diffuse scattering around 1.8 A —1 develops close to this temperature, which they interpret 33 due to th2 re-ordering of deuterons among the octahedral sites in Pd and a possible cause for the specific heat anomaly. 7. Superionic conductors Investigations of the superionic conductor a-Agl have been performed on the INS TOF spectrometer by Funke, Echold and Lechner who conclude that for "mas shorter than -* 10-iîs the cations (I-) essentially perform local liquid-like diffu sion of cations through the system of voids and channels provided by the anion lattice becomes important. The authors have carried out a systematic investiga tion of thp temperature dependence of these effects betwen 160° and 300° C. Secretary : A.P. MURANI 80 college 8 "structural biology" MEMBERS OF THE COLLEGE At ILL : White J. Zaccaï G. Bartunik H. Bentley G. Chauvin C. (CENG) At EMBL : Dlanoux A. Haas J. Berthet C. Ibel K. Cusack S. Jacrct B. Gabriel A. Lehmann M. Hulmes D. Lewit A. Llndley H. Mason S. Miller A. Sud; J. Ngo Tri H. Tlmrnins P. Teccliettl D. Torbet J. (Euratom) White S. GENERAL SUMMARY College 8 is concerned primarily with the elucidation of molecular structures of biological systems. This may be to atomic resolution as In the case of protein crystallography or to a somewhat lower resolution, using the various low angle scat tering techniques. Systems investigated are often protein-nucleic acid complexes as in ribosomes, chromatin or viruses, fibrous molecules as in connective tissue, or membranes. These systems are studied as solutions or oriented (1, 2 or 3 dimensional specimens). A small amount of inelastic scattering for the investigation of the dynamics of biological macromolecules or their associated water is also carried out. Most of the work of College 8 is centred on the low angle scattering machines D11 and D17 but with a significant amount on D8 and D1G and small amounts on the Inelastic machines IN5 and IN10. There were 71 proposals submitted in 1977 of which 46 were accepted. In addition test time was allocated on D11 and D17 for the carrying out of short feasibility studies. These figures are very similar to those for 1976 and are indicative of a growing maturity in the field with increas ing emphasis on experiments which are more difficult or require more sophisti cated biochemical back-up. At the March Scientific Council the demand for a Staff Scientist In the field of protein crystallography was reiterated and in May S. Mason was appointed to this position. Two new 5-year physicists in the field of Biology were appointed : G. Bentley (for work in protein crystallography) and A. Lewit, bringing up to 7 the number of ILL scientists whose primary interest is biology. SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 Experiments performed by outside users with help from ILL scientists continue to play a major role in the biological field. In this domain work on the 50S subunlt of the ribosome (Stuhrmann et al.} has culminated In publication of a model which is in excellent agreement with others, particularly from electron microscopy. Stu dies on chromatin and nucleosomes are continuing by several groups each of which have produced important models, in particular that of Pardon et al. which has been strikingly confirmed by the recent E.M. and X-ray work of Finch et al. Studies on tRNA-tRNA-synthetase binding by two groups (Paris, Strasbourg) with strong ILL support Eaccaï, Jacrot) are beginning to throw light on the Interaction between the aminoacyl tRNA-synthetases and their cognate RNA. In the field of lipid bilayer studies an important phase In the study of deuterium labelled lipids has boen concluded and a publication accepted [Buldt and ZaccaT). Several essentially internal projects have been making good progress. In the field of protein crystallography the task of calculating a neutron scattering density map from the 17000 reflections to 1.5 A resolution now measured, is well under way. Some of the necessary programs have been implemented and preliminary calcula tions carried out, The contrast variation study of tomato bushy stunt single crystals (Lcwit and Timmins) is progressing well. Fig. 18 shows a 2° "oscillation photo- FIg, 18. - Tomato bushy__ stunt virus single crystal (123, a = 386 A } 2° " oscillation photograph " on D1? nv.tltidetector, x = 11,5%. ,A*/\ = 10 %, sample-detector — 1.41 m. The heavy scattering close to the centre comes primarily from the quartz ».<*. capillary h which the crystal Is enclosed. The crystal was soaked in 43 % D^O so that the scattering pattern is dominated by the RNA. graph " from a crystal soaked in 43 % D20. The first mass per unit length measu rements using neutrons have been carried out (Torbet) on the pf and fd filamentous bacteriophages and the results allow a clear distinction to be made between conflicting models. Two notable publications have been produced in virus solution scattering : a molecular weight determination and structural information on Satel lite Tobacco Necrosis Virus and a comparative study of the extent of RNA pene tration and stability in five spherical viruses [Chauvin, Jacrot and Witz). Impro vements made to D16 have enabled data of exceptional quality to be collected on samples of the purple membrane of halo-bacterium halobium. Using phases derived from electron microscopy a map of the exchangeable hydrogens in the plane of the membrane has been obtained (Fig. 19). f m. a L*aa^fcs-A • J^^^JJ^SÙAÀ Fig. 19 (a) and (b). - Neutron .scattering density of the purple membrane of halo-bacterium hatobium. (a) Membrane In H20 ; (b) Difference density between membrane in D20 and in H20, thus shewing the' location of exchangeable atoms. Heavy contours are positive and light coniours negative density In the difference mop. In the HgO mop high density indicates protein, thus a comparison of the maps shews more exchangeable hydrogens in the lipid region. Collaborative experiments with EMBL have continued in the field of connective tissue. Diffraction studies on the intervertebral disc showed the fixed angular separation of collagen fibres and contrast variation studies implied the probable attachment of some non-coilagenous moiety at regular intervals along the fibrils. In the field of inelastic scattering the most promising experiments are those on the flexibility of DNA in solution and the dynamics of water in proteins, in parti cular collagen. This latter investigation (carried out in collaboration with EMBL) has shown conclusively the existence of two states of water with different dyna mical properties in collagen. The biochemistry laboratory continues to provide important preparative and control facilities supplying a range of equipment complementary to that available at the EMBL WORKSHOPS, CONFERENCES AND SEMINARS A workshop on Small Angle X-ray and Neutron Scattering in Biology organised jointly with EMBO was held at Villard-de-Lans in March. This proved to be a great success and was attended by approximately 100 participants from Europe and the U.S.A. Many useful discussions were held and a successful cross - fertilisation between the X-ray and neutron fields was achieved. Secretary : P. TIMMINS college 9 "chemistry* MEMBERS OF THE COLLEGE : AlrieliC-t P. Jenkin G. Bartunlk H. Lehmann M. Bcsnard M. Leslie M. Bomchll G. Mason SA Carllle C. {Rutherford Lab.) Mejei F. Chieux P. Richardson R. (Univ. Exeter) Dianoux AJ. Rieke! C. Ghosh R. Rustichelli F. (Euratom) Haas J. (Univ. Mainz) Tabony J. Hayter J. Timmins P Hoitjans P. (Univ. Heidelberg) Tomkinson J. Howells S. Volino F. (CNRS) IbRl K. Wright A. Jscrot E. GENERAL RUMMAHY The Chemistry Coliege is active in the following fields : small angle neutron scat tering is carried out on polymers, including co-polymers and polymer mixtures, In the bulk and in solution. The inelastic scattering experiments on polymers invol ve both low energy diffuse motion and vibrational modes. The main effort in beam time however is in Inelastic scattering. In the field of molecular spectroscopy, quasi-elastic scattering is used to study diffusion, reorlentational motions and tunnelling, whilst inelastic scattering studies H-bonding and vibrational and tor sional modes. For multicomponent systems we now have Inelastic studies of dif fusion in lamellar phases and some colloid chemistry problems such as micellar phases and water in clays. A lot of effort is also going into surface studies (physi- sorption and chemlsorption) using both diffraction techniques and inelastic scat tering. Of the diffraction Instruments the Chemistry Coliege uses mainly D11 and D17 and most of the time goes to the polymer users. The only triple axis machine used is INI, but in its beryllium filter mode for work on molecular spectroscopy. The rest of the lime is used on the three inelastic instruments IN4, IN5 and IN10. The year saw D17 becoming scheduled and the polymer groups have taken advan tage of this. The number of experiments accepted seems to have settled down to about 100. There is also an increase in the amount of inelastic work, especially on IN4. The use of the main instruments is as follows : 84 D11 26 experiments 40 days 017 12 25 IN1 9 71 IN4 15 69 INS 14 53 IN10 18 97 The year saw a move towards accepting fewer proposals and allocating them enough lime to complete the experiment. This was particularly true for the inelastic work where users were encouraged to finish off continuation experiments. SCIENTIFIC TRENDS AND HIGHLIGHTS IN 1977 1) Polymers During the year the work on polymer materials was essentially a continuation of studies already started. In the field of stretched chains the CRM-Saciay group has now been joined in this type of study by the Imperial College group. Ths interesting results ore anisotropic in form so the experiments are time consuming uiid are likely to last several years. The stjdy of the crystalline solid state is the preoccupation of tlree groups : Bristol for polyethylene. Mainz for polyethylene oxide and Strasbourg for isostatlc polystyrene. All the groups involved in neutron scattering also perform charac terization of polymer conformation in solid amorphous state and in solutions, on a set of various polymers. One new study In this field is by the CRM Saclay Group with partially labelled chains which aliow them to study the interactior. between chains. In the field of solutions, experiments have been carried out to test the predictions of two theories ; the mean field [heory approach and the scaling lav; approi which agree for dilute solutions but differ for the semi-diiute and concentrated regimes. The activities of the polymer users were presented during their annual meeting In London on July 3, 1977 and the influence of the ILL can be judged by the number of publications (about 100) that have appeared since 1970. 2) Molecular spectroscopy - quasielastic Tunneling experiments continue to give interesting results. For example measure ments of Clough (Nottingham) on MDBP are entirely consistent with expecta tions based on very extensive studies using other techniques. They also provide new evidence in favour of two recent proposals concerning ths character of ther mally activated CH3 motion, namely the existence of "flip flop" motion and that at low temperature these motions occur mainly within the ground torsional state. 3) Molecular spectroscopy • infelastir. Molecular spectroscopy is now a well established field of study at the ILL using the instruments IN1B and IN4. The experiments on IN4 are still dealing with tor sional barriers whilst the work on moderately high energy transfer vibrations is conducted on IN1B. It is interesting to note that a spectroscopy experiment conducted to doten .ie methyl torsional bands from the Raman spectrum of n-methyl acetamide leads on to a serious re-examination of the accepted crystal structura. Furthermore, after having solved the crystal structures of some hydrogen bonded compounds, crys- tallographers are now returning to study the vibrational spectra. The field of molecular spectroscopy is also heavily involved in the research conducted on surfaces. Many organo metallic " model " compounds are being stu died in an attempt to understand the changes in vibrational spectra induced by absorption on solid surfaces. 4) Multicomponent systems Diffraction and inelastic studies have been carried out by the Oxford group to study the rate of intercalation of hydrogen and deuterium into CflK. The results arc consistent with the formation of clusters of potassium and hydrogci atoms or Ions, randomly distributed, forming an amorphous phase. Later these migrate and nucleate to form crystallites of CgKHj^ . The diffusion coefficient is determined by the diffusion of these clusters. IN10 - Smell angle analyser. 88 In the field of quasielastic scattering from clays, a lot of data has been accumu lated on IN5 which can be analysed using models of diffusion processes to yield constructive information for different ions and clays. For example, the Oxford Group have measured the diffusion of 1. 2 and 3 layers of H20 in Li montmorillc- nite. However in order to produce a detailed model for analyzing IN5 data, IN10 measurements are essential. The Birmingham Group have measured Ca and Mg montmorillonite on both instruments and the results are somewhat contradictory and further experiments are planned to resolve this. 5) Physisorption Important results were gained this year in physisorption. 35 Adsorption of Ar was compared on two iodine planes (belonging to MnJ2 and Pbt where distances are slightly different. On Mnl2 the registered structure of solid argon monolayer was confirmed feven the position of Ar relative to Mn was .established). These results agres with the entropies inferred from adsorption isotherms. In the same experiments good bidimensione! liquid [or glass] rings were observed for the first time. The question of liquid or class was solved for CD4 on graphite through quasi- elastic measurements : the disordered structure is very mobiîe (the two-dimen- sionai liquid is quite special because it can have bO % of vacancies}. A more complex situation arises with N-02 on graphite : at'/K two non registered solid structures a (W202 lying fiat ?J and fHN20, upright ?) which melt above 90 K, at 10 K the p solid, but 2lso an unexpected new structure which could nGt have been suspected by classical thennodynamical methods. This case emphasized the potentialities for complex molecules, but the studies of simple cases (rare gases) were even more rewarding : the stabilization of regis try, probably by pinning on defects, was confirmed with Kr on graphite at tempera tures and coverages where the solid monolayer is non registered on very clean substrates. Last but not least, the existence of static distortion waves was demonstrated with Ar on graphite ; i.e. the non registered two dimensional argon monolayer is modulated by the substrate. In the future a " registry degree " has to be intro duced ; it is the second order parameter needed to explain complex adsorption phase diagrams with singularities which can be called tncriticat points. Secretary : S. HOWELLS european molecular biology laboratory, g renoble EUROPEAN MOLECULAR The EMBL Grenoble Outstation was opened for use by ILL users in October 1976. Since that time some 14 user groups, all external to both EMBL and ILL, have used the equipment of EMBL. The equipment is also used by the ILL staff, espe cially the group directed by Dr. B. Jacrot. Initial difficulties with access to EMBL from ILL have been solved, thanks to excellent cooperation from the Security Deportments of both ILL and CENG. Now all holders of an ILL magnetic card (also issued to neutron users) have free access to the EMBL. Only the 300 m between the EMBL and Neutron Guide Hal! remains an obstacle ! it is still requested that prospective users cf EMBL give about two weeks notice of their intention so that staff can assure that the required equipment is prepared. The research programme on connective tissue and muscie. is underway and i:i the last year some new results were obtained. A complete correlation is now possible between the one dimensional structure of a native animal tissue (ten don) and the X-ray diffraction pattern to virtually amino-acid resolution. This ha': been used as a base from which to investigate how collagen interacts with other molecular species to produce composite tissues such as bone or cartilage. In the case of bone, a mineralising tendon system was chosen as a model, and a combined X-ray and neutron study allows an understanding of the relative loca tions of collagen and the inorganic crystallites of hydroxyepatite. The intervertebral disc contains tibro-cartillagenous material in the annulus fibrosus which forms its outer ring. This has been studied by X-rays and neutrons and is now being subjected to microanatomical dissection for comparative biochemical assay of its fine structure. The aim is to investigate the in vivo interaction between colla gen and the other main constituent proteoglycans. These studies have also been supported by the Arthritis and Rheumatism Research Council (U.K.). In collaboration with Dr. J.W. White (ILL) and colleagues, success has been achie ved in observing phonons in both collagen (of tendons) and muscle by Brillouin light scattering. This promises to be a useful bridge between the molecular structure and the function of biological fibres. It is worth emphasising that research collaboration has developed between the ILL and EMBL. Six ILL scientists have been co-authors on the in-house EMBL research group publications. Now that the EMBL is functioning in Grenoble, it is planned to gradually widen the research programme. The first steps in this direction, linked with a service facility, is the establishment of a deuteration laboratory. This will come into operation in 1978 and staff are now being recruited. The aim is to provide a sour ce of organisms (initially bacteria and perhaps a cell culture) which are almost fully deuterated. These organisms will be available to ILL neutron users. During 1977 we have enjoyed the benefit of several senior visitors, postdoctoral fellows and stagiaires. The EMBL/ILL series of Biology Seminars has continued. A. MILLER département technique service de construction et de maintenance mécanique La construction et l'installation de nouveaux dispositifs ou d'instruments spéciaux, la maintenance des dispositifs en fonctionnement, leurs modifications, la recher che d'améliorations technologiques, teis sont les grands domaines d'activité du Service. 1. Nouveaux instruments : — on cours d'étude, rie construction, d'installation : D18A. IN13, IN5b:s. IN12 — termines : PN5, D13C 2. Compléments d'équipements sur : !N5, IN7, D5, D'.', D17 3. Gros travaux de transformations ou de maintenance sur : D1A, D1B, D7, D10, D16, IN1, IN3, INS, IN10, PN6 -!. Support ou préparation des instruments spéciaux : SI, S25, S28. S32, S39. S4C, S42, SU 5. Gros travaux sur conduits de neutrons : H15 (création par coupure de rempla cement pour IN5bis), CH22 6. Aménagements : Plate-formes IN5, D15, potences IN1. IN11, D1A 7. Améliorations des conditions de fonctionnement des dispositifs expérimentaux : 7.1. - Contrôle en service : fabrication de coffrets standard de surveillance des machines tournantes 7.2. - Technologies nouvelles : palettes sur aéroglisseurs pour manutention des machines ou des protections - Développement des labyrinthes d'étanchéité, applications aux choppers à disque, aux sélecteurs - Application des étanchéités ferrofluides aux choppers, pour vide stati que et dynamique - Mise au point et applications des nouveaux modules motorisés codables pour les spectromètres tanzboden 8. Essais de sécurité : — Test de comportement d'un carter de chopper en cas do rupture d'arbre. Par ailleurs, l'assistance technique a continué à se développer pai la fourniture 3 de matériels standard (plateaux tournants, goniomètres, composants pneumati ques, etc.), par le prêt d'instruments de mesure et de contrôle, et par la prestation de services aux divers départements de TILL et notamment à l'Exploitation (Réac teur et Dispositifs expérimentaux). bureau des projets Le Bureau des Projets a assuré la préparation du budget, le suivi et le contrôle des dépenses dans le domaine des investissements pour les activités expérimen tales permettant en dépit d'une réduction sensible des moyens : — l'amélioration de 8 instruments (réglages mécaniques, protection, extension des possibilités de mesures, des moyens de manutention, otc) — ia coordination technique et financière de la construction du trois axes sur neutrons froids IN12, de l'interféromètre D18 (malgré un important ralentis sement dû au manque de moyens financiers], de la nouvelle source de neutrons ultra froids. Sur le plan technique, le Bureau des Projets — n collaboré étroitement avec les physiciens responsables, aux études de défi nition et à la construction des dossiers d'avant-projet des instruments IN13 et fN5bis don*- ia construction est planifiée et partiellement financée — a coordonné l'étu'le de l'amélioration des conditions du travail expérimental dans le hall des conduits — a assuré le suivi de l'installation d'un certain nombre d'instruments spéciaux : - installation d'un évaporateur en vue de la réalisation de miroirs polarisants - mesure du taux de protéine dans les grains de maïs - préparation du guide H21 en vue de son utilisation pour la mesure du rapport h/mn pour le neutron — a contribué à la préparation d'un plan pluriannuel d'amélioration et de renou vellement de l'appareillage scientifique. services fabrications mécaniques aménagement et entretien FABRICATIONS MECANIQUES 1. Les ateliers principaux de mécanique st chaudronnerie ont assuré, avec les mêmes moyens que l'année précédente (8 agenis), environ 11000 heures de travail réparties sur 280 demandes de travaux d'une durée supérieure à la journée, soit environ 75 % pour les besoins des expériences, 15 % pour le Réacteur et 10 % pour les besoins généraux. Les réalisations les plus marquantes concernent une importante contribution à la création de nouveaux instruments ou à la modification do ceux existants, sur études du « Service de Construction et Maintenance Mécanique -. 20 % environ du potentiel temps est réservé aux petits travaux, urgents ou sans dossier technique. 2. L'Atelier « libre service » a vu son activité croître sensiblement avec la fré- quentatio quotidienne de 12 à 14 techniciens qui, sous contrôle d'un ouvrier professionnel, ont assumé eux-mêmes leurs travaux de fabrications mécaniques. Bien que d'importance limitée du fait des moyens disponibles, la qualité des réalisations s'est maintenue à un niveau élevé cette année et a apporté une contribution importante aux travaux nécessités par les expériences. 3. L'Atelier « produits spéciaux » a continué à assurer, avec un agent, la fabrica tion et la mise en œuvre des matériaux de radioprotection habituels (polyuré- thann au carbure de bore, plaques de fluorure de lithium fritte, gadolinium, etc.). L'intérêt croissant du fluorure de lithium enrichi pour les dispositifs expérimentaux est à signaler, parallèlement à une certaine difficulté d'appro visionnement et aux problèmes technologiques liés au frittage par nos moyens disponibles. A. Le Magasin gênerai « matières premières » est resté exploité par un seul agent pour tous les besoins de l'Institut. AMENAGEMENT ET ENTRETIEN Los activités ce cette section se sont exercées cans les domaines suivants : 1. Etude des projets, passation des commandes, surveillance des travaux confies aux entreprises extérieures pour travaux neuf?, importants travaux d'entretien, ou modifications aux installations existantes. Les réalisations essentielles sont : — amélioration des conditions de travail dans le hall » conduits de neutrons « (chauffage, ventilation, sas camions, propreté) — réfection des réseaux souterrains d'alimentation en fluides du Bâtiment 1LL9 (ex-baraque de chantier) — amélioration des conditions climatiques des bureaux de physiciens ILL17 (pare-soleil en commande) — étude et appel d'offres pour création d'une zone réception marchandises et amélioration du magasin général — contribution à l'étude, avec le CENG, du nouveau réseau égout commun « eaux spéciales» en cours de réalisation. 2. Réalisation de tout ou partie des travaux d'aménagement complémentaires cor respondants. 3. Réalisation pour les expériences — et sur demande des physiciens — des branchements aux réseaux de fluides et petits aménagements complémentaires annexes. 4. Manutentions et transports à l'intérieur de l'ILL et partiellement vers l'extérieur. 5. Maintenance et réparation des Installations techniques générales en partie par agents ILL et en partie par entreprises extérieures. Ce secteur d'activité a représenté en 1977 une charge considérable de travail du fait du vieillissement général très sensible de certaines Installations (ascenseurs, monte-charges, ponts roulants, conduites de fluides ou d'eftluents). G. Mise en conformité des installations avec les règlements en vigueur et travaux visant à améliorer les conditions de sécurité en général. 7. Nettoyage et entretien général des bâtiments, espaces verts et voirie par contrats extérieurs. 8. Gestion et entretien du mobilier général de tout l'institut. Le montant des travaux réalisés par moyens extérieurs à l'ILL est voisin de 2 000 KF et concerne environ 70 firmes. service sécurité et radioprotection SECUH1TE GENERALE CLASSIQUE 1. Commission Interne de Sécurité (CIS) Etudes de sécurité, organisation et animation des séances de travail : par ex. : Définition des méthodes et des moyens a mettre en œuvre à l'ILL pour la manipulation et la détection ties émetteurs ci, examen du dispositif OS1IS, etc. 2. Amélioration des conditions de travail — Mesure des nuisances sur les lieux de travail : bruit (hall des neutrons, local TCMS) — Contrôle de la qualité de l'air dans les halls expérimentaux (poussières, hydrocarbures, métaux lourds...) 3. Animation du Comité d'Hygiène et de Sécurité (CHS) — Visites des lieux de travail, organisation des réunions, enquêtes sur les accidents du travail, compte-rendus à l'Inspection du Travail. 4. Action de prévention des accidents du travail — Essais périodiques du réseau de détection incendie. Suivi des travaux d'amélioration et d'extension de ce réseau. — Etalonnage des détections de fuite deuterium dans les installations Détri- tiation et source froide. 5. Formation et information du personnel — Organisation d'une semaine de sécurité avec conférences suivies de films (risques électriques, explosions, comportement physique au travail...) — Formation des agents aux travaux de levage et de manutention — Entrainement du personnel à l'emploi des appareils de premier secours (extincteurs) — Sensibilisation du personne! de quart aux problèmes de sécurité. 6. Maintenance et vérifications du matériel d'Intervention. 7. Assistance technique — des expérimentateurs : pour ie contrôle et le stockage des échantillons dan gereux (mise en place d'une nouvelle procédure par fiches) .— du médecin du travail : pour la visite et l'étude des postes de travail. SECURITE RADIOLOGIQUE 1. Radioprotection dans toutes les installations du réacteur et autour des dispo sitifs expérimentaux — Contrôles quotidiens des protections et des échantillons irradiés. Assis tance et information des physiciens et des techniciens d'expériences. — Contrôle et étalonage périodiques du matériel de détection fixe et mobiliî. 2. Travaux de laboratoire — Spectrométrie Y d'échantillons liquides et gazeux Analyses sur 250 échantillons liquides (D20, H20, huile des pompes) Analyses sur 700 échantillons solides (frottU:. déchets) Analyses sur 200 échantillons gazeux — Analyses du Tritium par scintillation liquide : 10 000 échantillons (barboteurs, frottis, urines). 3. Dosimetric Attribution et gestion des dosimètres : exploitation des résultats Films attribués en 1977: films individuels : 0 560 Films attribués en 1977: films do zoi:e : 1 020 800 films ont été délivrés en 1977 aux agents extérieurs à l'ILL (chercheurs invités et agents d'entreprises). 4. Préparation et contrôle de toutes les Interventions effectuées en miiieu radio actif notamment pendant les arrêts du réacteur. 5. Tous travaux de décontamination G. Contrôle des rejets d'effluents radioactifs liquides et gazeux 7. Conditionnement et gestion des déchets radioactifs solides et liquides avant transfert et traitement au CENG. 8. Assistance radioprotection pour les problèmes d'exploitation des installations et des dispositifs expérimentaux : laboratoire a, détection a sur les expérien ces, contrôles rejets cheminée, détection y autour du noyau central du Réacteur (niveau C). 9. Formations et éducation du personnel 10. Permanences de Sécurité pendant les nuits et les week-ends Assistance du personnel de quart. Contrôle des lieux de travail. Interventions sur demande ou en cas d'incident. département exploitation réacteur fonctionnement du réacteur en 1977 Le système de fonctionnement adopté depuis le début de 1975 n'ayant pas été remis en cause, la même périodicité a été conservée en 1S77. Six cycles de fonctionnement ont donc été programmés ; chaque cycle dure B semaines et se compose de 44 jours de marc::e continue suivie d'une période d'arrêt de 12 Jours, sauf su mois d'octobre où une période d'arrêt de l'ordre de 5 semaines permet des Interventions ou tics modifications plus importantes. ANALYSE DU FONCTIONNEMENT CVCLE PAU CYCLF. Cycie 1-77 : Démarrage du réacteur le mardi 4 janvier Arrêt le jeudi 17 février. Ce cycle a été Interrompu une première fois par une chute de barres suivi d'un redémarrage immédiat, mais surtout par un empoisonnement Xénon consécutif à des perturbations sur le réseau EOF. Le temps perdu n'a p?.s été récupéré pour permettre la mise en pile programmée de la boucle neutrons ultra-frcids sur le canal IH3. Cycle 2-77 : Démarrage du réacteur le mardi 1er mars. Arrêt le jeudi 14 avril à 0 h 45. Ce cycle s'est déroulé sans Incident, mais a dû être raccourci de quelques heures du fait de l'usure complète et prématurée de ('élément combustible. Cycle 3-77 : Démarrage du réacteur le mardi 26 avril. Arrêt repoussé au dimanche 12 Juin à 23 heures. Ce cycle a connu un certain nombre de perturbations ayant entraîné trois empoisonnements Xénon. Un seul de ces arrêts est lié è une défaillance tech- que interne, les deux autres sont dus, l'un à un grève, l'autre à une coupure de 20 minutes du réseau EOF. Cycle 4-77 : Démarrage du réacteur le mardi 21 juin. Arrêt repoussé au vendredi 5 août à 23 h 30. Ce cycle a été. lui aussi, marqué par quelques brèves interruptions suivies de redémarrage immédiat et par un empoisonnement Xénon survenu en fin de cycle. On a noté, aussi, un incident de contamination par du 56Mn en poudre sur l'expérience D5 dans le hall des expérimentateurs. La contamination corpo relle et vestimentaire observée sur l'expérimentateur a pu être éliminée. La zone concernée a pu être décontaminée immédiatement. Cycle 5-77 : Démarrage mercredi 17 août. Arrè' repoussé au dimanche 2 octobre à 8 heures. Ce cycle a été perturbé par une défaillance de la garniture mécanique de l'une des deux pompes principales eau lourde (qu'il était prévu de remplacer pen dant l'arrêt annuel). La puissance a été réduite à 45 MW pendant 5 jours, puis le réacteur arrêté pendant 2 jours pour permettre le remplacement de la pompe. Arrêt annuel : Octobre. L'essentiel des travaux programmés a pu être exécuté dans les délais prévus et dans des conditions satisfaisantes. Cependant, certains inconvénients liés aux entretiens et Interventions obligatoires ont été notés (par exemple lors de coupures de courant générales sur certains réseaux ; lors de l'arrêt de la ventilation et dos effluents gazeux...}. Certains aménagements pourront être cpportés a l'avenir, mais on no peut espérer éviter complètement toute gêne lors de ces opérations. Cyclo 6-77 : Démarrage mardi 8 novembre. Arrêt le jeudi 22 décembre. Marqué par 2 arrêts suivis de redémarrages immédiats. La fin de cycle a été perturbée par un troisième arrêt prolongé par l'empoisonnement Xénon, à la suite d'un déclenchement général des « Alimentations Secourues ». BILAiM CHIFFRE - 1977 Nombre de jours programmés initialement 2G4 Nombre de jours de marche effective 257 Nombre ds Jours Equivalents Pleine Puissance !JEFP) 253,56 Rapport marche effective/marche prévue 97.3 temps de marche % de marche effective = 70 % 36S jours Nombre d'éléments combustibles utilisés 6 Nombre d'éléments combustibles envoyés en retraitement 6 (effectivement expédiés) Nombre de chutes de barres ou arrêts imprévus 38 Nombre d'arrêts avec empoisonnement Xénon 7 Si l'on considère globalement le rapport du nombre de jours équivalents pleine puissance au nombre de jours de marche prévus, soit 96 %. on peut estimer que le fonctionnement du réacteur à été satisfaisant. Cependant, il faut remarquer que pour 3 cycles sur 5, la date de fin de cycle a dû être repoussée pour récu pérer des jours perdus par des srcëts en cours de cycle. ANALYSE DES ARRETS NON PROGRAMMES On a retenu, dans le total du nombre d'arrêts imprévus, tout incident ayant entraîné l'ouverture non programmée du circuit de sécurité, en dehors des périodes d'essai 95 ,3"— *_ . _..*_VH'.Tf«i.r..- - - iWIi'.-lïT.-.Tffl.'^VJvlWïUCT'fcj.-» * proprement dites. Ce nombre est bien supérieur à celui des Incidents réellement perçus par les expérimentateurs car il correspond, pour l'essentiel, à des pertur bations pendant les phases de démarrage ou de redémarrage après une chute de barres. Le nombre d'arrêts prolongés par un empoisonnement Xénon (7) est intermédiaire entre celui de 1976 (2) et celui de 1975 (8). Il est lié à celui des arrêts imprévus (3B cette année) car tout arrêt qui survient après le trentième jour d'un cycle provoque obligatoirement un empoisonnement Xénon par manque de réactivité. Le nombre d'arrêts imprévus (dont la définition a encore été légèrement élargio par rapport è celle de 1976) est comparable d'une année à l'autre, malgré les efforts faits pour le diminuer. Ceci est lié, d'une part à la diversité des causes possibles d'arrêt, et, d'autre part, à la difficulté ou à l'impossibilité d'éliminer complètement les causes connues (exemple : perturbations du réseau EDF). Néan moins, Il semble nécessaire de poursuivre les efforts entrepris pour diminuer ies causes d'Incidents reconnus», avant que les causes liées au vieillissement inéluc table de certains installations ne viennent s'y surajouter. FONCTIONNEMENT DES SOUS-EUSEMBLES LIES AU REACTEUR Les sources froide et chaude ont continué, comme par le passé, à fonctionner sans aucun problème. L'installation de détritiation a fonctionné suivant les besoins. — Quantité D20 traitées en 77 : R.H.F. 51 507 I Extérieur 3 017 I — Quantité de tritium expédiée à Marooule 69 945 Ci Les problèmes de montée de . adioactivlté dans les circuits d'eau lourde signalés en 76 se sont plutôt aggravés. Des recherches sont faites pour identifier !a couse de cette évolution encore inexpliquée, il est certain que la dose totale reçue on 77 par le personnel d'exploitation a été augmentée par ce phénomène. Le distillateur d'eau lourde, mis en route en début d'année, pose des problèmes de decontamination ; celle-ci est nécessaire pour pouvoir réparer une fuite qui a été détectée sur cet appareil. Le système d'alimentation régulée des calculateurs a été mis en service et fonc tionne correctement. Toutefois, l'absence de batteries d'accumulation ne lui permet pas d'éviter les coupures de courant en cas de défaillance du réseau de durée supérieure à 0,5 seconde. La mise en place d'accumulateurs est envisagée et étudiée. PRINCIPAUX TRAVAUX" ET AMENAGEMENTS1 CONTROLE De nouvelles chambres de pilotage chargées du contrôle du réacteur ont été mises en place dans la piscine. Ce système sera étendu aux chambres de sécurité. Il devrait permettre de doubler le temps de vie de ce matériel tout en éliminant les problèmes d'étanchéité rencontrés jusqu'à présont. 96 BARRES DE SECURITE Une barre de sécurité complète a été remplacée par un élément neuf. Ceci doit permettre d'évaluer la durée de vie des éléments absorhnts de ces barres, ELEMENTS COMBUSTIBLES Les retards successifs apportés à la signature du contrat de retraitement ont conduit à une situation difficile pendant l'été 77. Deux voles ont été poursuivies en parallèle pour pallier ce problème. L'une, valable à moyen terme, consistait à négocier avec le C.E.A. pour l'utilisation d'une piscine en cours d'aménagement a CADARACHE. L'autre consistait à accroître notre propre capacité tie stockage des éléments usés. La procédure de demande d'autorisation a été menée à bien ; 6 places de stockage supplémentaires ont pu, ainsi, être dégagées, ce qui corres pond è une année de fonctionnement du réacteur. D'autre part, les 4 premiers transports d'éléments combustibles vers l'usine de retraitement de SAVANNAH RIVER ont été effectués. 2 autres transports program més sont bloqués par une grève des dockers américains. Néanmoins, on peur estimer que la question du stockage et du retraitement des éléments combusti bles usés ne représente plus un problème majeur, tout au moins pour 1»78. BARRACE SUR LE DRAC L'ollmeritation en eau de refroidissement du réacteur est assurée ;iaï une prise d'eau sur la rivière Drac constituée par un barrage en enrochement. Or, l'abaisse ment du lit de la rivière en av?l de ce barrage, abaissement dû au prélèvement I •m&ï <*^l3*>*&Gt-ï- •"." • î\y- ../—-''" • "' ^U^ \£gu&£c- V-.-T^J ^C X -- ^*„v *%* te barrage en enrochements sur le Drac, à partir duquel l'eau de refroidissement du Réacteur est captée. En arrière-pian, le bôtardoau provisoire qui protège les travaux de réparation. 97 Depart po>jr le retraitement mix Etats-Unis des premiers châteaux de transport contenant des Cléments combustibles. de matériaux de construction, est d'ores et déjà supérieur h l'hypothèse la plus pessimiste retenue lors de sa construction en 1SG9, ei conduit à menacer se stabilité. Uno brèche ouverte en cours d'année dans ce barrage a dû être répa rée et consolidée. Des négociations sont entamées avec la Direction de l'Equipe ment pour envisager la construction d'un deuxième barrage en aval du premier, afin de stabiliser l'évolution ultérieure du lit de la rivière. BOUCLE POUR LA SOURCE NEUTRONS ULTRA-FROIDS Cette boucle destinée à produire des neutrons de très grande longueur d'onde a été introduite dans Is canal incliné IH3. Elle est raccordée aux circuits d'eau déminéralisée du réacteur pour assurer soq refroidissement, et aux circuits de sécurité pour arrêter automatiquement le réacteur en cas de fuite ou de défaut de refroidissement. AMENAGEMENTS LIES AUX EXPERIENCES SUR LES EMETTEURS ALPHA Des aménagements liés à l'utilisation è I 'ILL d'échantillons émetteurs alpha, ont été effectués afin de permettre de manipuler ces échantillons dans des conditions normales de sécurité. Ces aménagements comportent la création d'un réseau de contrôle de radioactivité alpha auprès des expériences, dans le nouveau laboratoire alpha et sur l'air extrait vers la cheminée. Les travaux sont en cours et In mise en service se déroule progressivement. Des modifications ont aussi dû être apportées aux expériences intégrées (H6 et canal P ) destinées à recevoir ces échantillons). Enfin, le service réacteur a effectué l'étude et !a réalisation du système de ven tilation et d'aspiration dans le laboratoire alpha. service environnement des échantillons 1. SECTION VIDE — Maintenance du parc comprenant : 209 pompes primaires 45 pompes secondaires 39 groupes spéciaux 25 pompes à air 5 Helitests. — 640 interventions, dont 177 réparations Importantes. — 760 tests de fuites pour usagers divers. — Mise ou point et construction de 20 filtres absolus pour protéger les pom pes primaires des contaminations alpha. Le nombre de groupes secondaires est insuffisant pour satisfaire à la demande et doit être augmenté de 10. 2. FLUIDES CRYOGENIQUES 2.1. /--ote liquide Consommation : 337 177 litres (+ 4 %) à 0,47 F/1. Hélium liquide — Consommation : 46 011 I (+ 12 %). — Coût moyen du litre, pertes comprises :11F. — Gaz fourni en libre service : 4 735 ma. — Pertes de gaz : '.' 216 irtf (21 %). i[ Depuis cette année, les corrections d'Imperfection du gaz ont été prises f en compte dans le calcul du gaz retourné sous haute pression au C.E.N.G. t. Cette correction diminue de 10 % l'évaluation de la quantité do gaz rendu. En conséquence, les pertes des années précédentes ont été sousestlmées. La stabilisation apparente des portes au niveau de 21 % correspond en fait à une diminution des pertes de 10 %. Des consommations très élevées (100 à 200 l/jour) ont été observées pour deux Instruments spéciaux. Bien que ces consommations aient été limitées à de courtes périodes de quelques Jours, elles ont dangereuse ment déséquilibré le système habituel de distribution d'Hélium liquide. Une | augmentation notable de la capacité de stockage devra être envisagée pour faire face à ces nouveaux besoins. 3. CRYOSTATS 3.1. Exploitation courante L'ILL dispose maintenant de 48 cryostats dont 28 affectés à un instrument. 27 cryostats permettent d'obtenir des températures inférieures à 4,2 K et 15 couvrent toute la gamme 1.5 — 300 K. 99 33 Instruments différents ont utilisé un cryostat à Hélium liquide au moins une fols dans l'année. Le rapport : nombre de cryostats/nombre d'instruments, égal à 1,45, est environ la moitié de celui des instituts équivalents (Brookhaven, Harwell, etc.), ce qui signifie un taux de charge particulièrement élevé. Plus de 70 % dos expériences ont nécessité un cryostat. Les 202 demandes de prêt ont été satisfaites. De nouveaux problèmes sont apparus avec la mise sur le marché des cryostats développés à TILL en raison de la qualité des résultats obtenus. Ces cryostats représentent un tel progrès par rapport aux modèles précédents que les expérimentateurs souhaiteraient les utiliser exclusi vement. Leur petit nombre (5) ne permet pas de répondre à toutes les demandes. L'utilisation des deux réfrigérateurs en circuit fermé n'a pas été inten sive, malgré leurs avantages indéniables, en raison de leur limitation aux plus basses températures vers 9 à 10 K. Peut-être aussi la nouveauté de ces appareils rebute-t-ello un certain r.smbre d'utilisateurs potentiels. 5.2. Développement Des améliorations ont été apportées sur un modèle expérimental de cryostat typo ILL et ont montré que la température minimale d'utilisation de routine pouvait être descendue à 1.1 K et peut-être même à 1 !C. •Température minimale précédente : 1,5 K). 3.3. Très basses températures (T < 1 Ki Grâce à une mutation interne en Juin 1977. un technicien qualifié a été affecté a plein temps à ces problèmes. Son premier travail a été une refonte importante du cryostat à dilution pour l'adapter aux mesures sur l'Hélium liquide, et au redémarrage de ce cryostat en novembre 1977. Ces opérations se sont déroulées parfaitement, exactement dans les délais prévus. Un second technicien sera affecté début 1978 aux mêmes problèmes, et on peut espérer obtenir enfin à TILL des très basses températures dans des conditions de relative facilité d'utilisation. Comme dans tous les autres domaines de l'environnement des échantil lons, l'objectif ne sera pas d'obtenir des performances limites, mais de mettre au point des appareils robustes et d'utilisation aussi aisée que possible. 4. FOURS Environ 10 % des expériences ont nééessité un four. Les températures de 20° C à 1 600° C sont maintenant obtenues de façon cou rante, avec une stabilité de + 0.5°C. Un four spécial à axe horizontal et 2 000° C a été étudié, et sa construction est en voie d'achèvement. 100 Les développements ont été consacrés essentiellement à la normalisation des fours et des électroniques de contrôle, ainsi qu'aux améliorations de détails dont l'expérience a montré l'utilité (ou la nécessité). De nouveaux développements seront nécessaires dans trois directions: — Températures plus élevées — Stabilité de température améliorée (0,1° C T < 800" C) — Automatisation. 5. CONCLUSION Plus de 80 % des expériences ont été' faites hors température ambiante. En dehors de la charge qui on résulte pour tout le groupe, cela démontre la nécessité absolue d'une mise au point permanente du matériel en fonction de l'évolution des besoins. Une étude précise a montré qu'un temps considérable était consacre par les expérimentateurs aux chamgements ds température. Il apparaît de plus en plus nécessaire de pouvoir commander la température par l'ordinateur qui pilote l'instrument, pour que finalement la température soit un paramètre comme les autres, pour lequel on puisse « positionner •> l'échantillon de ia manie manière. Une pré-étude technique a permis d'évaluer les possibilités techniques ei 'es moyens nécessaires. Il est probable que dés 1978 des réalisations pilotes seront faites pour des contrôles de fours, ies contrôles cryogéniques étant reportées à l'étape suivante. groupe centra! Ainsi que les années précédentes, le groupe a fourni un soutien quotidien aux instruments lors de ia distribution, du maniement, du contrôle et de la récupé ration des fluides cryogéniques et des gaz et en étant disponible lors du mon tage et du démontage d'appareils expérimentaux. Ce travail a augmenté cette année dans des proportions considérables; ceci est dû à l'utilisation croissante d'hélium Kquide et d'azote liquide, en particulier pour les Instruments Spéciaux, et au nombre important d'expériences qui ont été transformées. Au cours de l'année, presque toutes les protections biologiques des instruments ont été, au moins une fois, partiellement ou complètement démontées afin d'y effectuer des modifications ou des réparations et quatre positions expérimentales entièrement nouvelles ont été créées. L'installation et la normalisation des circuit's de l'eau, de l'hélium comprimé, de l'air et des effluents ont, continué en collaboration avec le groupe Circuits du réacteur. Les interventions électriques d'ordre général ont comporté l'installation et la maintenance des circuits électriques normaux et des circuits de secours, organes de commande et Indicateurs d'obturateurs de faisceaux, et des systèmes de verrouillage de sécurité. En plus du travail habituel consistant à fournir un soutien et à effectuer de peti tes modifications aux instruments, le groupe a aussi réalisé un travail de déve loppement général et ? participé à des projets spéciaux en collaboration avec d'autres groupes. Certains de ces projets sont mentionnés ci-après. — Construction et équipement de deux nouveaux laboratoires dans le hall expéri mental du réacteur ; l'un pour la manipulation d'échantillons de faible activité et l'autre pour l'examen avant et après Irradiation, les manipulations et le stockage des échantillons dangereux (en particulier les émetteurs K). — Equipement d'un nouvel atelier à l'usage des techniciens d'instruments. — Etude des modification!- à apporter à l'actuel laboratoire d'évaporations sous vide. — Définition d'une nouvelle canalisation d'effluents gazeux pour le hall des conduits de neutrons, dont l'installation doit être réalisée en 197B. — Il a résulté de IVxamen des conditions de travail dans le hall des conduit1; que chaque entrée réservée aux véhicules a été équipée d'un sas afin d'éviter les changements brusques de température. Des propositions détaillées visant à remplacer les cabines individuelles par deux grandes zones d'air conditionné qui regrouperont les ordinateurs et l'élec tronique servant au contrôle d'un certain nombre d instruments sont mainte nant en cours d'étude. — La protection nécessaire aux instruments suivants : IN12. OSTIS. S30B. IN5bis, D10, S21, S42, D13A, B et C a été déterminée en collaboration avec le Bureau des Projets et le groupe de radîoprotection. — Modifications apportées à l'intérieur de la casemate D2/D8 en vue de diminuer le bruit de fond des neutrons rapides ainsi qu'aux protections do IN8, DS, D3/IN7, D1A/D1B et IH1 afin de diminuer le bruit de fond des rayons Y- — En collaboration avec des experts de l'ILL et, dans certains cas, avec ceux du C.E.A., des recommandations ont été faites, au point de vue sécurité, pour un certain nombre de matériaux parmi lesquels le 3H, T20 et les isotopes du Pu, Am, Th, Np, 6k et Ra. C'est au Groupe Central qu'il incombe de s'assurer que la méthode de travail recommandée par les experts et que les procédés de manipulation qu'ils ont prescrits sent suivis et que les procédures d'urgence sont prévues. — Le travail portant sur le développement .d'un système d'ultra-vide comprenant une cryopompe à hélium liquide, qui sera éventuellement utilisée en relation avec une microbalance sur D1B pour faire des études d'absorption, a été pour suivi. Au cours de l'année, un-appareil permettant d'étudier l'absorption iso therme de l'ammoniaque sur le graphite et de l'H20 et du D20 sur le iodure d'argent a été construit. — En collaboration avec le Groupe détecteurs, des essais ont été effectués sur un détecteur localisant à anode résistante et sur deux modèles d'un nouveau type de moniteur localisant construit à l'ILL. Un détecteur fission à 16 cellules est en cours de réalisation pour D11. — Un programme a été écrit pour le PDP10 pour tracer les courbes de résolution de chaque fil des multldétecteurs en cours d'essai. — La mise en service du spectromètre spnl-echo IN11 a nécessité l'avant-projet et la construction d'une alimentation électrique de 600 A 100 V, de 15 mètres de tubes à vide, des babines de changement d'orientation du spin, des bobi nes d'orientation Ç , une correction de champ et des bobines de réglage ainsi que la fabrication d'un super-miroir polarisant et analyseur. — La spécification d'un avant-projet d'évaporateur pour la production en ligne de super-miroirs. Cfit évaporateur a maintenant été fourni et I! sera prêt à fonc tionner en 197e. — Système de contrôle électrique des appareils destinés a la croissance dea cristaux organiques. — Afin de faciliter l'alignement dos monocristaux, les dispositifs suivants or;t été étudiés et construits : - Un coillmateur réglable par un micromètre trisé sur une articulation de pré cision, ce qui permet au faisceau de neutrons de balayer exactement et ce, de façon reproductible, dans une zone de 12 mm dans les directions X et Y. A ce jo'jr, sept collimateurs ont été construits et instsilés. - Une tête miniature de translation à utiliser avec le cryostat D10 et avec des cryoréfrigérateurs displex à un étage permettant un réglage de position de + 3 mm en X, Y et 2. - Un support ajustable à utiliser avec un cryoréfrigérateur h deux étages sur D15 ou D16 et comprenant des orifices de pompage, des passages de courant ainsi qu'un flexible pour le vide et capots cryogéniques permettant d'accé der au cristal. - Des demi-volets réglables pour le faisceau monochromatique sur D8. 103 département informatique et électronique 1977 a vu le démarrage des opérations pratiques du remplacement du système de commande NICOLE. Ceci devrait se traduire par une plus grande souplesse, davantage de puissance directement accessible et, espérons-le, une meilleure fiabilité. Pour le reste, les efforts ont continué à porter sur le maintien des installations existantes en bon état de fonctionnement. Ces opérations nécessitent de plus en plus de tempo, et le Département attend la mise en place du programme de modernisation qui devrait alléger la situation. 1 service contrôle des instruments et acquisition des données Ce service assume la responsabilité des mises au point, des améliorations 3t de l'entretien dos équipements électronique?., des dispositifs éiecironlquec de com mande des Instruments, des systèmes informatiques ries instruments et des détec teurs do l'iLL. L'affectation des instruments aux différents systèmes de commande était à la fin de l'cnnée ;977 la suivante : En fonctionnement de routine Systèmes CARINE (équipés de calculatrices TELEMECANIOUE T 2000) CARINE 1 - D1A, D1B, D2, D5. D9 CABINE 2 - D10. INI, 1N2. IN3, INB CARINE 3 - Réserve, essais et mise au point. Systèmes NICOLE (équipés de calculatrices TELEFUNKEN TR 86) NICOLE 1 - D7, IN4, IN5, PN1 NICOLE 2 - Réserve, essais PDP 11s autonomes (différents types) : IN10, IN11. D3, D17, PN2, PN3 (GAMS1). PN3 (GAMS 2/3). Calculatrices autonomes (autres que les PDP 11) : IN7, D15/16 En service, mais encore en test PDP 11/40 autonomes : D8 (provenant de CARINE 1); D11A/E (D11A provenant de NICOLE 1). En cours de mise au point Différents PDP 11/34 se partageant ias services d'un PDP 11/55 faisant office de concentrateur : D7, IN4 IN5. PN1 (à prendre sur NICOLE) SOLAR 16/40 autonomes : !l«1-2. D1B (à prendre sur CARINE 1) PDP 11/34 autonomes : D19 Microprocesseur : D18. 104 1.1. ENTRETIEN A l'heure actuelle, étant donné lo pou de de ressources dont on dispose pour le remplacement des systèmes vieillissants, k bon entretien de l'équipement existant est devenu un aspect vital des activités du Service. L'augmentation de la fréquence des erreurs dans les mémoires de l'ordinateur CARINE a nécessité, pour rétablir leurs caractéristiques, une étude diagnostique d'ensemble. Il se pourrait fort bien que ceci se traduise par la nécessité de rem placer certains modules. Les pertes 'Je temps de mesure au niveau des instru ments, par suite de défectuosités dans les circuits éiectreniques de commande de CARINE, ont été sérieuses au cours do l'année 1977 et sont quoique peu pré occupantes. Le système NICOLE a dû même être mis hors service pour entretien préventif hebdomadaire. La fréquence des pannes a récemment baissé, mais il est prati quement certain que ceci est dû au fait c,uo tout nouveau développement sur le système a été arrêté. L'entretien des dispositifs électroniques généraux constitue une charge dont l'Im portance ne cesse de croître. Etant donné l'augmentation constante de ces équi pements, il est possible que l'on se trouve amené à revoir l'organisation de ce travail. 1.2. AMELIORATIONS (INSTRUMENTS EXISTANTS) Les programmes pour le remplacement du système NICOLE sont maintenant en cours de léalisalion. Quatre instruments, à savoir D7, IN4. Ilv5, PN1 sont en cours d'équipement avec un PDP 11/34 pour l'exécution de functions d'acquisition de données et de contrôle où le facteur temps joue un rôle primordial, ceu;;-ci étant raccordés à un PDP 11/55 plus puissant, équipé d'un ensemble complet de périphériques, fournissant des possibilités de préparation de programmes et per mettant un contrôle des données. Pour la manipulation des quantités importantes de données et du très grand nombre de canaux de données (128 K sur IN4 et IN5). l'acquisition de données s'effectuera par l'intermédiaire d'une mémoire extérieure CAMAC (semblable à celles équipant déjà le D11 et le D17). L'essai de ce systè me devrait débuter au début de 1978. L'autre instrument précédemment connecté à NICOLE, à savoir le D11A a été branché sur le PDP 11/40 du D11B. Ce système double a été mis en service à fa fin de l'année. De ce fait, très peu de modifications ont été apportées à NICOLE. Une exception cependant : PN1 qui a été équipé de 4' K de mémoire supplémentaires. Le remplacement des systèmes CARINE n'est pas possible dans un Futur immédiat. Quelques instruments, qui sont ceux imposant au système la charge de travail la plus farte, sont en train d'être équipés de leur propre calculatrice. D8 travaille maintenant sur un PDP 11/40, et un SOLAR 16/40 est en commande pour le D1B. Ce dernier calculateur, fabriqué par l'entreprise française SEMS. est considéré comme constituant une alternative au'PDP 11 satisfaisante pour les instruments sur lesquels la densité de données n'est pas trop élevée. Les autres instruments ont dû se satisfaire d'améliorations de caractère généra! en matière de logiciels, telles qu'une meilleure méthode d'alignement pour les machin :. à trois axes, des programmes supports améliorés pour les diffractornètres et une procédure d'échange plus efficace. Un certain nombre de possibilités à plus long terme sont évoquées plus loin (paragraphe t.4). Différentes améliorations ont été apportas aux systèmes fondés sur l'emploi de PDP 11 et PDP 8. Le PDP 11/20 qui est devenu disponible lorsque le D6 a été mis hors service est destiné à constituer l'élément de base d'un analyseur à paramè tres multiples pour la réalisation d'expériences de physique nucléaire. Des améliorations et des perfectionnements ont été apportés aux détecteurs de plusieurs instruments. Différents détecteurs supplémentaires ont été montés sur IN4, INS et IN7. De petits multi-détecteurs ont été essayés sur D4 et D16. Comme toujours, on a détecté certains besoins en systèmes électroniques amé liorés, non seulement sur les Instruments mais encore au niveau des dispositifs mobiles tels que les enregistreurs et les cryostats. 1.3. NOUVEAUX INSTRUMENTS le PDP 11/40 du D17 est maintenant considéré comme intégralement opération nel, bien que le système n'ait pas encore été exploité au maximum de ses possi bilités pour le contrôle de données. Dans une certaine mesure, il en va de même pour le système équivalent du D11 A/B, mais celui-ci a bénéficié de program mes antérieurement existants pour l'analyse des données du D11 A sur le PDP 10, dont la majeure partie a été transférée sur le FDP 11/40. Le nouveau spectromètre à 3 axes IN12, qui avait été initialement prévu pour fonctionner sur CARINE, a été équipé de son propre SOLAR 16/40 pour pallier aux problèmes de temps de réponse caractérisant CARINL. En conséquence, les systèmes électroniques initialement acquis adaptés au fonctionnement sur CARINE, ont été modifiés, le CAMAC étant maintenant contrôlé par un microprocesseur INTEL. BO-80. Le multidétecteur mobile pour utilisation sur des diffractomètres, D19, a été construit au cours de cette année. Les éléments détecteurs &e situent sur une surface courbe englobant 64° horizontalement et 4e verticalement avec des réso lutions de l'ordre de 0.125° et 0,25" respectivemânt, avec remplissage de He3 sous 12 bars. Pour l'acquisition des données on a choisi un PDP 11/34, pour réaliser la compatibilité avec le D8. En dépit du fait que le projet ait été gale pour une partie de l'année en raison d'un manque de fonds, des progrès considérables ont été réalisés au niveau de la partie électronique de l'interféromètre à neutrons D18. L'argent faisant défaut pour l'acquisition d'une mini-calculatrice, la commande sera initialement réali sée par l'intermédiaire d'un microprocesseur Motorola M6800. 1.4. ETUDES, PROTOTYPES ET REALISATIONS A LONG TERME On a étudié les possibilités d'incorporation de microprocesseurs dans le système CARINE pour accélérer les temps de réponse, mais cette solution a été rejetée comme pratiquement irréalisable. Cependant, le remplacement des moteurs à courant continu par des moteurs pas à pas semble présenter quelques avantages pour la précision, et un prototype doit être essayé sur l'IN8. La seule solution réelle aux problèmes de CARiNE reste cependant le rempla cement intégral de la calculatrice, des ensembles électroniques et des moteurs, et on espère que ceci interviendra dans le cadre du programm«5 de modernisa tion. A cet effet, un groupe d'étude constitué de physiciens et d'ingénieurs est 106 on train d'étudier la technologie concernant la mise en place du faisceau et le codage angulaire. L'acquisition de deux calculatrices SOLAR 16/40, avac la possibilité d'en avoir encore d'autres par la suite, a conduit à l'idée d'un concentrateur SOLAR destiné à jouer un rôle équivalent à celui du PDP 11/55. Les problèmes techniques en rapport avec l'installation d'un tel réseau de calculatrices SOLAR sont actuel lement en cours d'étude. Le travail de mise au point générale dons le domaine des multi-détecteurs se poursuit. La tendance générale est à la poursuite de l'utilisation de détecteurs à remplissage gazeux, étant donné qu'ils fonctionnent dans des conditions extrê mement satisfaisantes aux grandes longueurs d'onde. On s'efforce parallèlement de réduire les temps morts et le coût des équipements électroniques associés. On estime également qu'il est judicieux de continuer à étendre l'utilisation de mémoires extérieures pour une acquisition rapide des données. Les micro-pla- quetles à haute densité nouvellement fabriquées contiennent 16 K bits chacune, ce qui permet de loger 128 K mots de 16 bits dans un module CAMAC. Plusieurs autres Instituts de recherches se sont déclarés intéressés par l'acquisition de tels modules, et l'achat de microplaquettes en grandes quantités s'accompagne rait de réductions de prix considérables. service calcul scientifique 2.1. - ACTIVITES L'ordinateur central DEC système 10 continue à fournil au personnel de l'ILL des possibilités de calcul en général et des facilités de manipulations de données réduites pour les visiteurs, mais ses ressources sont de plus en plus fortement sollicitées. Le débit de travail d'ensemble est fonction, tout d'abord, de la période do couver ture par opérateurs, qui reste a environ 75 heures par semaine. Le débit de traite- mert d'ensemble de la machine s'est donc maintenant stabilisé à environ 3 200 heures- par an. Même les utilisateurs qui utilisent la machine en libre service la nuit doivent maintenant accepter d'autres utilisateurs jusqu'à minuit. Un supplément de 64 K mots de mémoire reconditionnée a été installé (portant le total disponible à 224 K), constituant en l'occurrence la seule possibilité prati que restante d'amélioration de l'efficacité du système. C'est la seule adjonction à la configuration qui ait été possible cette année. 2.2. MANIPULATION DES DONNEES La quantité de données reçues des instruments a légèrement augmenté au cours de l'année, principalement du fait que le D17 est passé en utilisation de routine, et travaille maintenant à environ 220 Mmots/an. L'incorporation de données en provenance de certains instruments commandés par PDP-11 (dans -in premier temps D11 et D17, D8 étant prévu ensuite) dans la base des données expérimentales générales, antérieurement limitées aux seuls instruments CARINE et NICOLE, a constitué une amélioration particulièrement marquante. 2.3. GRAPHIQUES L'imprimante électrostatique « Versatek • mise en placo a la fin de 1976, a été à l'origine de certaines perturbations cor, bien qu'elle donne des diagrammes d'excellente qualité, elle nécessite l'utilisation d'une part importante du temps de l'ordinateur pour produire l'image finale. De gros ; rions ont été entrepris pour résoudre ce problème, et ont porté entre autres sur l'amélioration du logiciel du constructeur et l'utilisation du PDP Î1/55 pour constituer la bande d'entrée. Il est cependant prévu qu'en dernier lieu la seule solution satisfaisante pourrait être celle consistant a faire fonctionner le traceur de courbes sur le 11/55. Pour le reste, les efforts ont porté sur i'unification des logiciels qui supportent les nombreux types différents de dispositifs d'affichage. Malheureusement, bien que des logiciels unifiés soient, du point de vue de l'utilisateur, une chose pra tique, il peut s'ensuivre des manques d'efficacités si l'on néglige de prendre en considération les caractéristiques du dispositif utilisé. 2.4. SUPPORT DE PROGRAMMATION GENERAL L'effort de programmation actif reste toujours nécessairement limité à un petit Viombre de secteurs clés. La version RUTHERFORD LABORATORY (Atlas Div.) du système dit X-RAY a été installée, donnant à l'ILL pour la première fois une version complète à jour de ce programme particulièrement renommé. Le personnel du RUTHERFORD LAB. mérite d'être remercié pour toute l'aide qu'il a apportée à cet égard. Les disponibilités restreintes en matière d'efforts ont également limité les possi bilités de développement de la bibliothèque de sous-programme mathématique, mais l'acquisition de bibliothèques et de différents sou*-programmes dans d'autres Instituts de Recherches a été possible. La série de programmes de gestion qui s'occupe des dépenses de déplacement et des statistiques correspondantes a nécessité certaines modifications au cours de l'année, et eu égard à sa complexité, il ne s'est pas encore avéré possible de confier son exploitation, dans son intégralité, au Département Administratif. 2.5. COURS DE FORMATION Plusieurs séries de conférences et de cours de formation ont été effectuées sur des sujets du plus grand intérêt pour les utilisateurs. Des cours d'initiation aux manipulations sont également dispensés en fonction des besoins, pour permettre aux utilisateurs de faire fonctionner le PDP 10 eux-mêmes. 2.6. REMPLACEMENT DU SYSTEME 10 On s'est rendu compte depuis un certain temps qu'il serait nécessaire de ret.v placer le système 10 vers 1980. Etant donné que cette date se situe dans le programme chronologique du projet de modernisation générale de l'Institut, ce remplacement est prévu dans le cadre de ces propositions. Pour pouvoir effec tuer des prévisions budgétaires avancées, il a été procédé à une estimation des besoins de l'Institut en matière de-traitement de l'information au cours des années 1980. Pour tenir ce programme, il sera nécessaire de démarrer dès le commen cement de l'année 1978 une étude sérieuse des machines possibles. administration Le département « administratif et financier « comprend le Service du Personnel, le Service des Relations Sociales et le Service Financier. Le 25 juillet 1977 a été signée par la Direction et les organisations syndicales CGT, CFDT, FO la Convention d'Entreprise de l'ILL. Cet accord tient compte de la situation spécifique de l'iLL. Il remplace le Statut du Personnel en vigueur jusqu'à cette date. personnel Dans les différents domaines relevant du Personnel il paraît intéressant de faire ressortir en 1977 ks questions relatives aux effectifs de l'Institut et aux repré sentants du Personnel qui jouent un rôle essentiel dans le cadre des relations contractuelles avec la Direction. 1. EFFECTIFS 1. SITUATION DE L'EFFECTIF Mouvements en 197? Fluctuations Embauches Départs Situation et et col. 4 Fluctuations fluctuations Différence Situation par rapport Cateoories internes internes -r ou — au 31-12-77 (1) (2) (3) (4) (5) (6) (7) 1. Scientifiques 73 19 16 + 3 76 22 2. Cadres techniques et administratifs. 58 3 1 + 2 60 2 3. Collaborateurs temporaires de thèse 25 10 5 + 5 30 2D 4. Techniciens 142 5 3 + 2 144 2 5. Autres catégories 99 9 3 + 6 105 3 Total 397 46 2» + 13 415 7 * Pourcentage du personnel ILL qui a quitté l'Institut en 1977, par comparaison avec l'effectif au 31-12-76. Comme pour les années précédentes, les mouvements importants de personne! sont essentiellement dus au personnel scientifique ayant des contrats à durée limitée. A noter toutefois que si le nombre d'arrivées reste identique à 1976 (46). le nombre de départs a sérieusement diminué (28 au lieu de 44). Remorques : 1) A titre indicatif, le personnel féminin représente au 31-12-77, 55 agents soit 13 % de l'effectif total de l'Institut. 2) A noter : un départ à la retraite, le premier d'ailleurs depuis la création de l'ILL. 2. REPARTITION PAR NATIONALITE : 1973, 1974, 1975. 1976. 1377 Français A.lem.Hda Britannlquos Divers Total Calagsriea 73 74 T5 70 7? 73 74 75 75 77 »l» 75 :G 77 73 74 76 77 73 74 75 le 77 Scientifiques 15 1C, 17 17 IS 2S 23 ?? 21 18 M 2? SE :? '•2 1" « 63 « 73 7, 76 Cidr*9 it ^ Ingénieurs I engineers 35 35 35 40 «1 IS o 11 11 11 S 7 a M 49 54 M 60 CollaborMoa-s temporaires 16 15 15 9 lu ie 7 5 D il 1 2 7 7 3 2 2 2 - „ 31 :s 20 30 de thè.ifi - Non-Cadres 182 ISS 15? îM 192 19 16 13 19 2! S 14 21 25 29 ij_ 3 a A 7 >14 235 B3S 2S9 Totaux 257 2G3 266 259 261 G3 GO SS GO m 22 3t SS 6< 7? iî 16 U 17 s: 3Ï1 373 W5 357 -115 Variât tons +6 7 -f-2 -9 + 4 -i 1 12 +21 ••fi + 11 —7 i-2 ,i + 7 i-2 . 13 +» ~ -* -, « Effectif nettement en progression en 1977 {•*- 18Ï et plus particulièrement l'effectif britanr.iquo (+ 11). 2. REPRESENTATION DU PERSONNEL Le personnel de l'ILL est représenté par ; 1) Trois syndicats (CGT, CFDT, FOi. A noter dans ce domaine la création d'une nouvelle section syndicale au sein de l'ILL depuis le début de l'année 1977 (FO). 2) Les représentants au Comité d'Entreprise. Les élections de ces représentants se sont déroulées en Février 1977. 3) Les représentants au Comité d'Hygiène et Sécurité. 4) Les Délégués du Personnel. Les élections ont eu lieu en Mars 1977. 5) Les représentants à la Commission Paritaire des Carrières. COMITE D'ENTREPRISE Le Comité d'Entreprise, dans le cadre de ses attributions, a joué un rôle important dans la vie de l'iLL, aussi bien dans le domaine économique à titre consultatif que dans le domaine professionnel où il a coopéré avec la Direction pour l'améliora tion des conditions d'emploi et de travail à l'Institut. Par ailleurs, dans l'ordre des attributions sociales, le Comité d'Entreprise a assuré, contrôlé ou participé à la gestion de toutes les œuvres sociales établies à l'ILL au benefice de ses agents. 3. PERSONNEL PAR CATEGORIE ET NATIONALITE AU 31-12-1977 Effectif total : 415 F : Français Français 261 A : Allemands Allemands 61 B : Britanniques Britanniques 72 D : Divers Divers SCIENTIFIQUES INGENIEURS ET COLLABORATEUR TECHNICIENS AUTRES CADWES admin. lèmp.de THESE CATEGORIES Total : ?6 Total : 60 Total : 30 Total-.1 A4 Total:l05 F A B D I- A B e A B F A B 0 F A 3 D 1 20 I 00 80 60 68% 4C 34 24 20 18* 18 14 337,30% 5% 0 m 111 service relations sociales (Tous les chiffres indiqués sunt arrêtés au 15-11-1977) Rappelons tout d'abord que le service est essentiellement chargé : — de l'accueil du personnel et des chercheurs invités — des questions sociales et médicales — de ia liquidation des frais de mission du personnel de DLL, des chercheurs Invités et des statistiques correspondantes — de la formation du personnel. Un changement important est intervenu, au cours de cette année, dans le domaine médical. Soucieuse de résoudre au mieux les problèmes de médecine du travail, l'ILL a mis en place un service médical autonome auquel un jeune médecin du travail est attaché à mi-temps. Ce médecin se consacre de façon efficace et dyna mique à la surveillance du personnel et des chercheurs invités de longue durée. Il travaille en liaison étroite avec les Chefs de Service pour acquérir une bonne connaissance des postes de travail et des risques éventuels correspondants. I! est en relation permanente avec certains services médicaux du Commissariat à i'Energie Atomique, en particulier le Centre de Marcoule, ot avec les servircs hospitaliers grenoblois compétents. Dans ie cadre de ce Service médical, ont été suivie : Directement Affectés : 202 agents ILL 32 chercheurs invités Non-Directement Affectés : 123 agents ILL 6 chercheurs invités Non Affectés t 103 agents ILI. 1 chercheur invité. Les scientifiques invités en tant qu'utilisateurs du Réacteur passent obligatoire ment des examens et subissent une visite médicale lorsqu'ils no sont pas en mesure de fournir une attestation d'aptitude à travailler sous rayonnements ionisants. — Accidents de travail : 19 accidents, dont 7 ayant entamé au total 114 jours d'arrêt de travail (20 ùr. 1976 pour 49 jours d'arrêts) — Arrêts de travail (maladies) : Dont arrêt do Total nombro do Cadres NcivCndres Total + 30 jDurs jours d"abs';nr:e II I 20 115 135 9 1558 13 85 98 6 1666 31 107 13B 12 1692 — Maternités : 8 maternités ont entraîné 856 (ours d'absence en 1977. — Cures : 2 cures ont entraîné 38 jours d'absence cette année. Le total des jours d'absence au titre accident de travail, maladie, maternité, cure, représente 2,28 % du nombre théorique total de jours travaillés. SECURITE SOCIALE Le nombre du dossiers de maladie, maternités, etc.. contrôlés et transmis pour règlement à la Sécurité Sociale a augmenté au cours des 4 années passées, ainsi que, parallèlement, le nombre des remboursements complémentaires liqui dés par la Société Mutualiste du Personnel ILL et celui des dossiers transmis à l'IRRAPRI (Caisse de Retraite Cadres) (dossiers chirurgicaux, maternité en par ticulier). Mutuelle IRRAPRI Sécurité Nombre Montants Nombre Montants Soci&le dossiers remboursés dossiers remboursés 1S75 5580 4800 172,289 F 194 20,745 F 1376 6170 4715 210,843 F 213 39,055 F 1977 6380 4675 205,623 F 271 45,047 F GESTION DES CHERCHEURS INVITES Sous le terme Chercheur Invité sont regroupés les scientifiques, venant à l'ILL: — en qualité d'utilisateurs du Réacteur pour effectuer les expériences décidées par le Conseil Scientifique — pour donner des séminaires — pour séjourner en année sabbatique. Le tableau ci-dessous indique le nombre de passages (missions) de chercheurs invités par laboratoires français, allemands, britanniques, divers, indépendamment de la nationalité des personnes envoyées par ces laboratoires. Français Allemand Britannique Divers Avec frais 3 mois 144 214 240 il) 74 3 mois - 1 an 3 6 — 2 Plus de 1 an 3 10 1 — 150 230 241 76 = 697 Français Allemand Britannique Divers Sans frais 3 mois 157 94 112 139 3 mois - 1 an 3 2 7 11 Plus de 1 an 2 2 4 7 157 = 540 (1) Estimation En liaison avec le Secrétariat Scientifique, un certain nombre de documents sta tistiques concernant les chercheurs invités ont pu être mis au point grâce à l'aide du Service de Calcul Scientifique. AIDE AU LOGEMENT Elle se manifeste sous plusieurs aspects : 1) Recherche d'appartements ou villas pour les nouveaux arrivés, le personnel en place ou les chercheurs invités de longue durée. A ce titre, nous avons aidé une quarantaine de familles ; les recherches s'effec tuent par prospection téléphonique auprès d'agences, par annonces dans les Journaux, etc. L'ILL étant connu maintenant, beaucoup d'offres nous arrivent spontanément. 2) Investissement des « fonds de 1% •• Les employeurs sont tenus de consacrer 1 % des salaires bruts à des actions en faveur du logement du personnel, dans un cadre légal très strict. L'ILL s'est orienté essentiellement vers le versement de prêts complémentaires à un prêt principal (Crédit Foncier, par exemple) sans intérêt, remboursables en 10 ans, aux personnes accédant à la propriété de logements en cours de construc tion répondant aux normes définies par la législation. Les plafonds des prêts sont également fixés par la loi (ex. : 21 000 F pour 3F, 27 000 F pour 4F, 34 000 F au maximum). Le service intervient pour conseiller les agents lorsqu'ils s'engagent dans de telles actions, les orienter éventuellement, les aider s constituer leurs dossiers de demandes de prêt auprès des organismes choisie. Le tableau ci-dessous précise l'évolution des demandes et montants des prêts obtenus ou en cours, pour les quatre dernières années, au titre du 1 %, par l'intermédiaire du Comité Grenoblois d'Aide au Logement. Nombre de bénéficiaires Montant totai des rîréts Année Cadres et ass. Non-Cadres Total 1974 3 6 9 95 000 1975 4 11 15 173 000 1976 3 18 21 253 000 1977 4 16 20 438 000 en cours au 15-11-77 1 4 5 97 000 Total 15 55 70 1 056 000 QUESTIONS SCOLAIRES La moyenne d'enfants non-français accueillis à l'Ecole primaire de la Houille Blanche est de 50 pour l'année scolaire 1976-77. Elle sera du même ordre pour l'année scolaire en cours. Le principe de la composition des classes expérimenta les est le suivant : — 25 enfants au maximum par classe dont 15 français (appartenant au secteur scolaire) et 10 non-français, enfants du personnel de l'ILL, du Max Planck Institut, etc. — 2 enseignants allemands et 2 britanniques sont attachés à cette école ainsi qu'un enseignant français, chargé de l'apprentissage du français aux jeunes étrangers lorsqu'ils arrivent à Grenoble. Les classes de sixième et cinquième aux Eaux-Claires constituent la suite nor male dn l'Ecole primaire. Il semble que la nouvelle direction du Collège d'ensei gnement secondaire soit mieux sensibilisée aux problèmes de l'enseignement aux Jeunes étrangers. Des démarches sont en cours pour obtenir, de la part du Rectorat, l'autorisation de poursuivre les classes expérimentales jusqu'au niveau cie la troisième incluse. FORMATION DU PERSONNEL Comme chaque année, un plan formation a été élaboré offrant au personnel la possibilité de suivre des actions de plus ou moins longue durée, dans les domai nes linguistique, technique ou d'information générale. On ne peut qu'être frappé par le sérieux des demandes de formation : elles sont l'écs essentiellement au poste de travail ; elles visent à l'accroissemer, des connaissance? et compétences techniques, ainsi qu'à l'amélioration des relations dans l'entreprise, par exemple par le souci de connaître les langues utilisées le plus couramment dans le travail (français, anglais). Les organismes de formation auxquels nous faisons le plus souvent appel sont le CUEFA (Centre Universitaire d'Education et Formation pour Adultes). l'APPS [Association pour l'Enseignement Professionnel et la Promotion Sociale), le Centre •de Formation Professionnelle pour Adultes de Pont-de-C!aix. finance 1. BUDGET ET COMPTABILITE Le budget autorisé pour l'année 1977 prévoyait des dépenses totales d'un montant de 99,3 Mio F, dont 2,0 Mio F devaient être couverts par les recettes propres à l'entreprise, et 97,3 Mio F par les contributions des associés. D'ap;tiS l'arrêté des comptes provisoire 1977 la situation des dépenses, par rapport à 1976, se présentait comme suit (hors taxes) : 1977 %du 1976 % du (1000 F) total (1 000 F} total a) Dépenses de fonctionnement Matières consommables 6 200 6,4 6 323 7,1 Eléments combustibles 14170 14,5 9 913 11.1 Frais de personnel 48 000 49,2 41833 46,7 Taxes et Impôts 121 0,1 97 0,1 Travaux, Fournitures et Services à long terme 8 600 8,8 7 555 8,4 Autres Travaux, Fournitures et Services Extérieurs 5 900 6,0 5 492 6,'i Frais de transport. déménagement et missions 890 0,9 978 1,1 Frais divers de gestion 3 125 3,2 2815 3.1 Total dépenses de fonctionnement 87 006 89,1 75 006 83.7 b) Investissements Bâtiments 325 0.3 218 0,2 Equipements (sans dispositifs expérimentaux) 1307 1,3 1078 1,2 Dispositifs expérimentaux 7 200 7,4 8 568 9,6 Autres investissements 1800 1,9 4 711 5,3 Total investissements 10 632 10,9 14 575 16,3 Total dépenses 97 638 100,0 89 581 100.0 1077 %du 1976 % du (1 000 F) total (1 000 F) total c) Recettes Recettes propres à l'entreprise 1980 2.0 2115 2,4 Contributions des associés 95 658 98.0 87 466 97,6 Total recettes 97 638 100.0 89 581 100.0 1.1. Par rapport à l'année précédente, los frais de fonctionnement sont passés do 75,0 Mio F à 87,0 Mio F (+ 16 %). Cette augmentation est due essentiel lement au démarrage des travaux de retraitement aux USA des éléments combustibles usés en 1976 et 1977, aux augmentations de prix lors des approvisionnements, et aux augmentations des prix de fabrication des élé ments combustibles, ainsi que des frais de personnel. 1.2. Les dépenses d'investissements ont diminué par rapport à l'année précédente, soit de 14,6 Mio F à 10,6 Mie F au cours de l'année de référence. En 1976, les investissements comportaient les dépenses pour l'achat d'un calculateur scientifique d'un montant de 3,1 Mio F. En raison de retards de livraisons imprévus, principalement pour 'es dispo sitifs expérimentaux, quelques commandes de 1977 et des années précéden tes n'ont pas pu être exécutées conformément au pinning. Les paiements, d'environ 1,5 Mio F, ne sont donc pus intervenus en 1977 comme prévu, mais seulement début 1978. C'est pourquoi les dépenses d'inveîîtissements pour 1977 sont inférieures de ce même montant par rapport à ce qui avait été évalué. 2. EVOLUTION DES DEPENSES 1973 - 1978 t FF X 1,000,000 50 40 Frais de personnel 30 Frais de fonctionnement 20 Investissements en dispositifs «expérimentaux 10 1973 1974 1975 1976 1977 de 1973 à 1977 il s'agit des dépenses effectives, 117 3. ACHATS Au cours de l'année de référence, 5 187 commandes (contre 5 541 l'année précé dente) ont été traitées. Toutes les commandes sont exécutées en étroite collaboration avec les services techniques et scientifiques. La répartition des commandes dans les trois pays partenaires se présente comme suit : 1977 % du 1976 % du (1000 F) total (1000 F) total Volume total de commandes 33 22G 100 29 487 100 Répartition : — France Î!i800 50,6 16 493 55,9 — RFA 11 900 35,8 CE55 29.0 — lioyaume Uni 900 2,7 3 143 10,7 — Autres 3 620 10,9 1 296 4,4 Malgré tous les efforts dans co sens, on n'est pas parvenu à améliorer la répar tition des commandes dans les trois pays partenaires. La régression des commandes en Grande-Bretagne est due avant tout aux délais de livraison et à la concurrence des prix. Les efforts pour parvenir à une répartition plus équilibrco des contrats à l'avenir seront accrus. c v^. ,_,? Before completing the attached farm,TOO ar e requested to careful/ read the following the Scientific Couvert, I ne College iiset! oxamine» all new proposals nip) n-^-t points which are essential for the forwarding of your proposal to the Scientific to the practical ard technical aspects, with the sub-eemmitteex asc^jir-g Ile CounciJ of the ILL. scientific merit und assigning priorities. There are at present 7 suhconmontées - aNucloar am Fundamental Physics» - aPureCrysuisk (Excintions) CONTENTS OF THE APPUCATION - hCrysidHoRTaphrc and Magnetic Structures» Insufficient information on vour research project mav load to e postponement - (Liquids and Amorphous Substances» of your proposal, it is essential that among51 other information, the procosal - a Imperfections» should contain : - « Biology» - An outlina of tho scientific bockgrnind and rate want fciturei of tha • «Chemistry». envisaged experiment. The Scientific Council of the ILL receives end reviews the recommendations tr-rr - Tha reasons for carrying out tha experiment at tho HFR. the various subcommittees and acts as en advisory committee to the Direcioi v.-' s >• - • A realistic data Tor the availability of all experimental equipment including, the final authority. This Council serves mainly to coordinate the various p. JIL".;.S «amples (not provided by tha ILLI. to establish general guide-linos for :ne scientific policy and to define pn.ti,!^-. - The detoa whan it is ahsnlutelv Impossible fcr yav to sarry our your within tho «xncimen'. prc-nritr.-ime cf tha Institut. experiment (see attached reactor ichoduJe) In tha kchr-dullng period under consldorriian. SCIKNTfrtC COUNCIL DECISIONS : - Tnfc key-word number (au? ruverae si do) end up-to-date I in nf référenças. Please respect also the following points when completing the proposal form : Immediately aW each meeiir.g of the Scientific Council tne user wnl be info-n--j by tJw Scientific Secretary whether or nui his re^eaech proposal has been acc^Xij Ho win sto be jntormed at tf-e same Sniu sf the name of his local contact. MAIUNfi OF YOUR PROPOSAL: Fach exoerimantal r-roposot should be BUrt'essed to the Office of the Scientific EXPERIMENT TIME SCHEDULES : Secretary (Dr Orna MAIËfl, Institut •.aua-Un.ievii, 156X, Cemia 0? Tri. 38042 Grenoble-Où ex, France! Iiom where it will te forwarded automatically Six monthly limi schedules incorporating the Scientific Council decisions aie to the pertinent re » iow- boa ids. normally compiled in the tt>w w.teVs following a Council meeting. It is (hereforu essential thai leouasif far specific dates and moailicanant :r suggested dates are comniu.-ncatecl to the Scientific Secretory as soon us possible OEAO-LINES FOR SU a MISSION : [by telephone or preferably in writing). The various subcommittees of the ILL- wh;ch, in general, raviaiv each proposal, meet twice a year. Fcr 'he tub minion of c proposai, a UedC-lx.e of one month error to TIME VALfDiTY Of ACCt-PTEO PROPOSALS : the subcommittee meetings h ai been established in order ^«U»*t^^^-»l--«-j-^»J(i>lt'<-t^i-iAt'.UJi-^t^('A COLLEGE 3 (Fundamental and Nuclear 5-2. Powder Diffraction 7-03 Defects and dtso:der in solids Physics* 5-21 General structure problems - point defects 3-01 ILotengrin Experiments, nuclear spectro - mineral stnictures - strongly deformed crystals scopy on fission Droducis - inorganic and organic structures - strains in crystals 1 3-1 iLohengrin Experiments), Fission - disordered structures - clusters 3-02 I Gams - and Bill - Experiments) !n,Y I and • site occupancy problems - tiffceipitates - alloys (n, ej • spectroscopy 5-22 Struciurnl changes and phaso trimarans - ordering effects 3-03 Beam experiments using nuclear tactions induced by temperature, pressure, fislds, - glasses 3-04 Beam experiments using nuclear methods etc. - solid state phase Transformations in solid state physics, biology, médecin:*, 5-23 Megnetic ordering 5-24 Structures of adsorba:es 7-W In beam experiment etc. - NMH - speciru'ccpy for defect stuoies 3-05 Fundamental physics and intercalated compounds 5-25 Special applications ot power diffraction 7-05 Impurity and dcfoci states - scattering length dmerminarion • inelastic impurity scattering COLLEGE 4 llnolastic Scattering in • kinetic measurements by diffraction • hyperfine intera'.--tior.s Simple Solids) methods - spin waves in alloys 4-01 Lattice Dynamics - methodic questions • stiffness constant • phonon dispersion relations - lattice dimension and thermal expansion • spin relaxation effects 7-05 Diffusion ir; bulk maie'id' - pressura effects measurements - self * didusion in bulk rns'srial - surface phenomena 5-3. Polarised Neutron Diffraction - diffusion in bulk materbi -. Kohn anomalies 5-31 Magnetic form factors - dynamics of hydrogen in bulk mutais - Jahn-Teller effects k 5-32 Spin density • tine shape measurements : asymmetries • structure of hydrogen in bulk metals and photon life-time mwsurements • derealization of moment nnnex : vortex linu spectroscopy - :cvBlency effects 4-02 Dynamics of Structura) Phase Transitions 7-07 - Ionic and suparionic condurtors . - soft mc/dss 5-33 Polarization ar.afysis 1 • nsn-collinear magnetisation - central peaks COLLEGE C (BlolcgyJ - etectron-phonon interaction effects (su • spin-orbit coupling perconducting materials) 5-3* Paramagnetic scattering B- Biology (All subjects) 5-35 Polarized nuclei 4-03 Magnetic Excitations - magnon dispersion in metals Ealloys) and COLLEGE 9 IChemlilryl ionic compounds (mixed systems) COLLEGE 6 (Fluids and Amorphous - collective modes in low dimensional Substances) 9-01 Polymers and polyetactrolytes. collcida; systems (mixed systems I systems - Small ongle scattenng from - magnon-phoiicn hybridisation 6-00 General properties and phys:.;al constants 9-02 Polymers, pohelectrorytos and oiiocmers - 4-04 Dynamics of Magnetic Critical Scattering measurements Quasi-elastic and Inelastic Scans, imj frrun - measurement el critical indices S-Ol Quantum liquids - studies of low energy (diffuse) motions :~. - fine-shape determinations 6-02 Monoatomic liquids and gases polymers, in bvBt or in solution 6-03 Binary liquids alloys - vibrational modes in bulk or dissolved a) Normal or ideal typs COLLEGE 5 (Crvttallographic and polymers b) Compound type • phonons in polymer: Mignotic Structuras) c) Segregation type 903 Molecules in Solution {liquid or solid! - 5-1. Single Crystal Diffraction 6-04 Magnetic properties of fiuics and amor Quasi-elastic Scattering from 5-17 Inorganic structures phous substances - diffusion • mineral structures 6-05 Molecular liquids of low molecular weight - chemical reactions - chemical structures less than 20 atomes per molecule) and ionic - reo rien rational motions - zeolites liquids of low melting point (less than - tunnelling 100°CI • disordered structures 3-04 Molecules in Solution or Solid State - In 6-06 Molten salts 5-*2 Organic structures elastic Scattering from 6-07 Ionic solutions (excluding chemical reac - H-bcnding - genera! organic compounds tions) - vibrational, torsional modes • organomeiallic compounds 6-06 Glasses (pure glasses only) and amorphous 9-05 Multicomponent Liquid Crystalline ana - organic inclusion complexes materials Colloidal Systems - Dynamics of - disordered structures 6-09 M us op ha se s (liquid crystals, plastic 5-13 Hydrogen positions crystals) pure systems only - mult «component liquid crystalline or lamel 5-14 High precision neutron diffraction measure 6-11 Critical scattering of fluids lar phases - diffusion within and bet wee" ments for electron density work layers 5-15 Structural changes and phase transitions (Each item includes the dynamic and the - colloid chemistry problems (e. g. Micel'a' induced by tempereture, pressure, fields, structural aspect) or hexagonal phases, water in cays. s"-; etc. COLLEGE 7 (lmperfections) 3-00 Dynamics of physfeoibed end chcrmsoreee 5-16 Special applications of single crystal measu systems rements 7-01 Mixed magnetic systems • catalysis • magnetic impurities t - space group problems • molecules ehemisorbed on surfaces - giant moments - superstructures (e.g. H2 on Naney -Nickel. C2H5 in - d'rffuscness of reflections - spin glasses zeolites, etc.! - methodic questions ianomalcus scat - magnetic alloys • Oynami:s of molecules in layered tering, extinction, etc.) - critkol magnetic phenomena intercalates 1 - topography • magnetic anisotrepy 5-17 Magnetic ordering • magnetic phase transition* 7-02 Crystalline «lectr*c field - cryttol field parameters - crystal field transition - H-bonding in bulk metel hydrides • valance states I i J& A