HOT FOR PUBLICATION EANDC 85 "U"

EUROPEAIV-AMERICATT XIJC1XA.R DATA COMMITTEE

TECHNICAL MINUI'ES OF THE TSD(CEENTH MEETING OF THE COMMITTEE

Bournemouth, Ecgland, 6th-10th October, 1969

Compiled by

M. NEVE de MEVERGNIES , (Mol) (Executive Secretary)

EANDC Secretarid

European Nuclear Energy Agency, OcE.C,C.

38, so~ievard. 5~che.t~ P,-.-is l&

PREFACE TO THE TECHNICAL MIATUTES

EANDC 83 "U"

This version of the minutes of the eleventh ~eeting of the European-American Nuclear Data Committee is produced for general distribution to those concerned with measurements programmes in the nuclear data field. The conclusions are, however, of an interim nature in many cases, and the document is therefore marked "Not for Publication" and should neither be quoted in publications nor listed by abstract journals.

Paae

HIGHLIGHTS OF THE 13th EBNI)C MEETING 5

LIST OP PARTICIPANTS 7

Consideration of the Minutes 12th meeting. (MD

2. REPORTS ON FACILITIES NT MEASIJREUENTS

a) Changes in Nuclear Data Facilities .b) Progress ~ e ~ o r t s t (c) Research Papers (d) Reports on New Results on the

alpha Value of Pu 239 (e) Reports on New Results on,Fast

Fission of Pu 239 and U 235 . . ., . ... . ~ . .

3. ' CONFERFNCES rg . . .

. . (a) Second Conference on the Physics an 19

Chemistry of Fission, Vienna, July (b) ~nterpational ~ o n f erence on Past ~eactor" 20

Physics, London, 24th-26th June 1969 (c) Conference on the Properties of Nuclear : , . 21

States, Mogtreal , 25th-30th August, 1969 . ,

(d) ~~rn~osium on Neutron capture % . G q n i a 'Ray 21 Spectroscopy, Studsvik; 11th-15th August 1969

(e) Conference on Computer Systems in '~xperimental 22 Nuclear Physics, Skytop, - Penn 3rd-6th March 1969.. ,,. .

(f) IkEk Meeting on Aipha of Pu 239, Winfrith, 2 3 U.K. , 30th J m e - 1st July 1969

( Othor sc5edui.sd c m f erences 24

4. REQUESTS ZOR NLTCIXAR DATA 25 (a) General remarks 25 (b) Lists of Requests from the various 26

EANDC regions (c) EACRP recommendations 27

5. IN'II'E33,NATIONAL CO-OPERATIOX IN THE M.EASmE1\TT 28 OF NUCLEAR DATA (a) Co-operative on '5 28 (b) Co-operative efforts on elastic and 29

inelastic scattering (c) Report of the Standards Sub-committee (d) Other areas of international co-operat

6. INPORMP,TIOB ON OICEIEX N I T C m DATA COMMITTEES . 30 (a) Meeting of the EACRF', London, 30

10th-14th February 1969 (b) Meeting of the LNDC, May 19 1

7. IPTFORMATION ABOUT DATA INDEXING, COMPILING . , , .: 32 AND EVALUATION

. . .

(a) IAEA activities 32 (b) E N E ~ activities " 34 (c) U.S. activities , . . . 36 (d) Other activities 37

8. NEXT EANDC MEETING (a) Procedure f

S Requests-Li (b) Place, ate

. . , ,

. .

App. 1 : List of EANDC documents issued since 41 the 12th EANDC meeting in Brussels January 1969)

App. 2 : Report of the EANDC Sub-comm Standards for Neutron Measur

45

HIGHLIGHTS OF THE ISTH W D C MEETING

Bournemouth, England, 6th-10th October 1969

1. PROGFLESS ON IMPORTANT NUCLEAR DATA

Dj.scussion of the latest results and current work related to some of the mos ctors yielded the following conclusions

Pu 239 : A general consen capture to fission ratio (i e 1 - 30 BeV neutron energy range. This is based both on recent integral measurements and on additional differential measurements : what remains to be done seems mainly %c consist of reaching an agreement on normalization. Regarding the absolute D value (i.e., average number 0:

secondary neutrons per fission) in the neutron resonance energy region, no progress w ~ s mentioned. However, new accurate measurements ofn in the energy range 40 keV - I .5 MeV have been made in France and in the U.K.

Fast Neutron Fission : In the neutron energy range from about 50 keV to 1.5 MeV, a number of reuent results are now in fair agreement as regards the relative values (namely, the ratio of the fission cross sections of U 233, U 235 and Pu 239, and also the ratio of U 238 capture to U 235 and Pu 239 fission), but the accuracy of the absolute values of each of these data is still unsatisfactory. Several independent measurements on these are under way or planned for the near future.

Fast Neutron Total Cross Sections : A large number of high resolution total cross section results on important elements (such as C, Fe, Na, Al, MO, V, Cr etc. ..) have been obtained at Xarlsruhe (in the 0.5 to 32 PleV neutron energy range) and at several laboratories in the U.S, (in the 0.15 to 1.5 1YeV range). There is good agreement on the very important data for Fe.

Fission Neutron Spectrum : Disagreement on the exact shape of the enerm s~ectrum of the ~ r o m ~ t fission neutrons (from U ,235 &d'~u 239 fission)-has recently arisen between various experimenters, and consequently, a critical review of this point will be prepared for the next UNDC meeting.

U 238 Ine l a s t i c Neutron Cross Section : A new measurement has been performed a t Argonne, and these r e su l t s have been used f o r a re-evaluation of the U 238 data.

S~andards : The work i n t h i s f i e l d i s slow because of the very large e f f o r t needed t o reach the desired accuracy of 1% or l e s s . Good progress was repor+;ed, among others, on the B 10 (n, a) cross section a t low and interme- d ia te neutron energy, on the absolute value of the Li 6 (n, U) cross sect ion a t thermal energy, and on the U 234 ha l f - l i f e ( t h i s l a s t data i s needed f o r etraluating .the absolute f i s s i on cross sect ion of U 235). An in terna t ional comparison of U 235 f i s s i on f o i l s i s under way with a view improving the assay of t h e i r uranium content .

2. DATA REQUESTS, INDEXING, COMi?ILING AND EVALUATION

e q u e s t ~ i & t f o r Nuclear Data wasnot discussed, een done extensively nine monthsear l ie r a t the C meeting, and :an extensively revised l i s t i s i n

preparation;, Ins.te.ad, the'way of reviewing the new list before and durilig the nextmeet ing was discussed, ;and what i s believe2 t o b e a n improved prdceclure was agreed and w i l l be applied.

The C o q i t t e e was informed by the IAEA observer t ha t a data request l i s t :from 'non-EAND.C coun t r i e s had p e n compiled by the I A U . and would be edited ear ly i n 1970. , ~

. . , . .

The committee discussed with the IAEA observer the , gradual 'take-over by . IAFA o f the regponsibil i ty fo r publication

of ,GINDA . ( i . e . t he ' compilation o f a l l ,references pertaining t o nuclear data o f : i n t e r e s t f o r reac tors) , which had previously been shared b y t h e BrookQaven'and Saclay Nuciear Data Centres. The various s t e p s of th i s t ake-over , and some general guide- l i n e s f o r the fu ture of CINDA, were agreed upon.

S . , . , . , ,

The importance. 'df evaluation: was noted :several times diiring t h e meeting : r e p o r t s oh the evaluation o f some important data, were presented and discussed, the needo f a meeting of t h e J o i n t EANDC-EACRF:.Sub;-committee ohEvaZuation around m i d

'1970 was s t ressed , , andaCthe. .end of the meetingia half-day topica l discussionwas devoted t6evqluat ion .

-g INUTES OF THE THIRTEENTH NEETING OF

held a t

C a r l t o n H o t e l , E a s t C l i f f , B o u r n e m o u t h , &gland

6th - 10th O c t o b e r 1969

L i s t of part icipants :

W D C MEKBERS :

P, WEINZIERL, S e i A u s t r i a ( C h a i r m a n )

R. BATCHELOR, AWRE, A l d e r m a s t o n , U.K*

K.H. BECEURTS, K a r l any

H. CONDE, S t o c k h o l m , S w e d e n

G.C. HANNA, C h a l k R i v e r , C a n a d a

W.W. HAVENS, Jr., C o l u m b i a U n i v e r s i t y , U.S.A.

R. JOLY, CEA, Saclay, France

T. PIONOTA, J A E R I , Jap

M.S. MOORE, L o s A l a m o s , U.S.A.

M. NEVE de PEVERGNIES, Mol, ecutive Secreta~.~r

.R. RAE, AERZ, H a r w e l l , U.K.

ROSEN, EHEA, Paris , France

A. SMITH, A r g o n n e , U.S.A.

J. SPAEPEN, E u r a t o m , G e e l , B e l g i u m

J. STORY, AEE, Winfrith, U.K.

OBSERVERS :

Madame SOLANES, ENEA, Par is , France

W.T. POTTER, EKEA, Paris, France W. GOOD, IAFA, V i s n n a , A u s t r i a

J.J. SCHMIDT, K a r l s r u h e , G e r m a n y

The Chaiman opened the meeting at 10 o'clock in the Purbeck Suite of the Carlton Hotel.

He first welcomed the new members, namely Dr. M. Moore from Los Alamos, Mr. J. ROSm as well as Madame SOLA,$~ES EI.Q~ Mr. W. POTTER from the FLXER in Paris who were attending as observers. He then paid a tribute to Dr. R. PERRET, former member of the ~~~C who died in Paris on 14th May 1969. He stressed Dr. Perret's very valuable contz4.btifjion to , , tke pcesenhffici&nt operation of the Committee, esplcially as regards the administrative and political implications of the Committee's activities. He also pointed out his contribution to the general field of nuclear data, having had a large responsibility in the foundation and subsequent operation of the CCIIE, and in the editing of the EANDC-Requests List (RENDA-document). Both were now extremely useful tools for a large number of scientists. Last but not least, Dr. Perret's skill and sense of humour during the Committee's meetings had always been very much appreciated.

1. LNrRODUCTORY ITEMS

(a) Consideration of the minutes of the twelfth meeting

The minutes (EANDC-81 "8") were aocec%ed as published except for two changes : oz page 26, the reference pertaining to request numbers 10.41 and l.0.42 : the reference to EAM)C(CAN).-~~ should read EBM)C(CAN)-38. On page 16, line 11, change to, "It is intended to build an Isochronous Cyclotron at the Research Institute of Physics etc..."

2. REPORTS ON FACILITIES AND RECENT MEASUREKENTS

(a) Chan~es in Nuclear Data Facilities

The following recent changes or progress were mentioned.

Germanx The length of neutron flight tube at the Karlsruhe isoc~onous cyclotron has been increased up to 180 m ; the resolution is 6 ns/km and preliminary data collection is under way* The Franco-German High Flux Reactor at Grenoble is proceeding very well and should be completed by July 1, 1971, A Heavy Ion Accelerator will be built at Darmstadt, in a new research centre. It will be a linear accelerator of the UNILAC type developed by Schmelzer at Heidelberg. It should reach 8 MeV/nucleon and be capable of accelerating all elements up to Z = 92. Several versions under consideration.

U.S.

Argonne National Laboratory

Reactor IJhxsics Division ---------- ------------- The Fast Neutron Generator (Tandem ~ynamitron) is beiag

shipped to the A m site and the components are being installed as the3 arrive. S ecifications are for both tandem (8 MV) 2nd single ended (4 PiVy nodes of operation. Pulsed and DC capability is available in both modes. In DC mode factory tests, proton currents of -200 microamps have been observed. Various large experimental facilities aaaociated with the programme at the new facility are under construction and installation ; for example, time-of-flight collimators with flS&t paths to 7 meters at angles of + 160° to - 140D. Hopefully, Christmas 1969 will see full research operation.

Physics -- Division

The Argonne 4 MV Dynamitron is now in operation. To date, protons and deuterons have been accelerated and helium ions wlll be used in the immediate future. Until experience has been obtained in handling large currents of energetic ions, most experiments will be designed to use currents of less than a few hundred microamperes.

The energy resolution of the ionbeam is at least as good as that of the old 4 MV Van de Graaff. The beam quality and positional stability is exceptionally good. At beam currents of less than 100 PA a beam spot less than 3 mm is obtained both near to and at a considerable distance from the accelerator.

A new data room has been added to the facility. An on-line computer is now operating. Provisions have been made for up to thirteen beam lines. A pulsed ion source including Klystron bunching has been purchased and will be installed during the autumn.

Brookhaven National Laboratory Tandem Van de Graaff ProJect ---

The assembly of the accelerators started e This effort has gone quite well to date.

NF-7 has now met or exceeded all of the performance specificat:ions tbat any previous W accelerator has ever had to meet. There is still one remaining test to complete which has to do with a special requirement for the Brookhaven machines and involves the ion source characteristics rather than the accelerator. The completed tests represent 95% of the perfor- mance capabilities of the machine and show that the Van de Graaff accelerator performs quite well.

PP-6 i.s now completely assembled and the test programme has been started.

Duke Universi.?~ Injector Cyclotron ------------------

. . . ,

. A sec,>hd set of slits, has been installed i n the cyclotron v8cu:inI chsaber. -t.o decrease the R.P.,. phase acceptance for partizles- acceicratefi, to. f?.~ll radius. As a re'sult' the cyclctron m y be' tuned f ~ r 3 0 keV energy spreads routinely, and. energy spreads in. the extracted bearil of the order -of 20 keTJ

' may be obtained withminimum bean.: An additional advantage of the two sllt combination hhs been an improvement intuning reproducibility due to the additional constraint upon orbit

, . pattern. -

Neasurements of output pulse time characteristics have been made using commercially available equipment and have proven to be of great value in achieving optiaum tuning conditions. Installation of a separate cyclotron target area presently under way will facilitate future cyclotron development work.

. ,

.'Major projects for ture include. continuing improvement .of the ;reliability of indiyidualcyclotron cdmpon@nts, development ,of an external feedback system to' improve the transverse -stability o,f the extracted beam, and investigation of improved dee voltage control with various feedhack possibilities. Work is presently under way in all of these azeas, An improvement in resolution by the C~rona control system should be observed after sending the cyclotron beam through the tandem. This effect has been found in a preliminary mezsurement, but the effecv is small.

Lawrence Radiation Laborator2

The Livermore Electron Accelerator Fac i l i t x .......................................... The new electron accelerator being ins ta l l ed a t the

Lawrence Radiation Laboratory., Livermore, consists i n i t i a l l y of f i ve S-band sections with room and provision t o expand t o seven sections. The f irst f i v e sections are powered by R.F. modulators constructed by the Applied Radiati.cn Company, and the l a s t two w i l l be modified forms of the SLAC design. The accelerator i n s t a l l a t i on has been completed and the accelerator sections are being t e s ted under R.F. power. The f i r s t beam was expected on October 1, 1969.

The accelerator w i l l be oper i n a choice of three modes. These are a s follows :

(a) The Steady Sta te Mode : Pulse lengths ranging from 5 nsec '

3 ysec are available, with a duty cycle of 10-3. The energy f o r f i v e sections i s t o be continuously variable from 10 t o 80 MeV a t a f u l l peak load current of 700 d.

(b) The Transient Mode : For t h i s mode the accelerator w i l l be loaded with currents from 10 t o 15 A. The pulse width w i l l be approximately 5 nsec or l e s s , with a pulse repe t i t ion r a t e a s high as 1800 pps. Maximum power with 5 sections i s 55 W.

(c) Positron Accelerator : The positrons are t o be created a t the end of the t h i r d sect ion (a t approximately 60 PIeV) and accelerated i n the fourth, f i f t h , and subsequent sections. I n i t i a l l y positrons of energy ranging from 10 t o 80 MeV, w i l l be available. With future expansion the energy w i l l reach 170 MeV. By placing a converter a t the end of the f i r s t sect ion the positron energy w i l l be extended t o 250 MeV, with considerable l o s s of in tens i ty . The peak current w i l l be approximately 1 mA with an average current of 1 yA.

Further charac te r i s t i c s of t he five-section accelerator a re given i n Table AI below.

TABLE A I

Ener Peak Current Max. Pulse Max.Puls me$' (Amp ) Width (ySec.) Rep. Rate

(p.p.s.1

I 10-80 0.700 0.10 660 Steady Sta te 11 11 11 1 .O 420 I 1 I 1

I 1 I 1 11 3.0 300 l 1 I 1

11 10-140 10.0-15.0 0.005 1800 Transient

111 10-100 0.100 0.10 1800 Peak B.F. Tower

I t 11 11 1 .OO 840 reduced t o II II 11 5-00 600 half

T ,j2-80 0.001 3 0 0 300 Positrcn mode Zull R.F. average power

Beam Trsns --m---*.---

, , ~ .

This : w i l l : consist i n i t i a l l y of s i x beam. l i n e s expandable t o a maximui o f ' i i i ne . The s i x b e a m l i n e s w i l l be rea l ized through the use ci$ 14 bending :.magnets, , eight quadrupole p a i r s and about f i v e s ing le t l e n s e s . . .A power s l i t w i i l be located a f t e r the f i r s t 22.50 bend, which wi l lmake 'avai lable momentm 'spread f o r photonuciear experiments a s small ;as 0.05%. , T W O large experimental caves ,have:,been constructed t o the north and south of a magnet room. High electron beam currents - w i l l n o t be permitted i n these caves, i n order t o avoid act ivat ion of

. . : the walls and beam transport 6 t. . . .

. ' ,

-Two of the beam l i ne s q u i r e d t o pass a..momentun!. spread. of 2 15%. These l i n e s gd-toneGtronproducing t a rge t s

Target Cboling. . --- ---------S

mirhnum' length :of 4 m.:,.:.There.:will' be two. t a r g e t posi t ions below ground fo r the prqduction ofneut rons . . The neutron y ie ld w i l l be approximately 1014 neutrons/sec . Above ground the f l i g h t tubes w i l l have lengths of 15 m , 66.01 and 240 m. About half ,of t h e accelerator time , . wil1,be ,, dev time-of -f l i g h t experiments.

University of Maryland . . .

'Cgclotron . - -------.. , .

,. ..

Work on the Cyclotron Project during the f i r s t half of 1969 has been primarily associated with t h e completion of the extraction system, t h e i n s t a l l a t i o n of the beani handling system, and bean development and extraction studies. The f i r s t extracted beam of 60 EeV alpha pa r t i c l e s was achieved on August 14, 1969- Considerable improvenents have a lso been made i n the s t a b i l i t y o f : t h e RF system an6 various msgnet power supplies.

. .

Plassachusetts Institute of Technology

Linac ----- Power supplies for the steering coils and solenoids

are being designed and fabricated at MIT. Construction is presently under way. All of the Varian water loads, rf windows and terminal loads have been delivered. The rectangular wave guides have been completed.

The major hardware components have been designed. Among those thus far procured are the bending magnets, quadrupole magnets,.power supplies, vacuum pumps, cooling system components, xnstrumentation and special vacuum chambers,

Preliminary tests on the injector gun and filamcnt have been completed satisfactorily. Design and fabrication of the renainder of the components is proceeding slightly behind schedule. The injector test facility at NIT is conplete and some of the support components have been installed.

Oak Ridge National Laboratory

ORELA (Oak Rid~e Electron Linear Accelerator)

On Auwst 25, 1969, the electron linear accelerator was accepted by OFSTT and experiments were officially started. The accelerator has met or exceeded all its performance specifications (except that the peak current at 2.5 nsec was 13.2 A) which were :

14.0 fleV average energy 15 amperes peak current 2.3 to 24 nseconds 2 . 3 to 1000 nanosecond pulse 50 joules/pulse 1000 pps 50 kilowatts <l0 pamp dark current during rf burst

The reliability runs were modified in order not to further delay the use of the accelerator for neutron cross section measurements. The accelerator was operated for the first week at a reduced repetition rate since the first experiments could not tolerate a high repetition rate. During the first week the accelerator operated 44.3 hours out of a scheduled 45 hours and produces 17.5 A pulses at 28 ns at 100 pps and 75 joules/pulse at 30 pps. 4 new electron gun was installed in the accelerator on August 22 since the emission of the old gun (which had been used for 8 nonths) had dropped by a factor of two.

The data acquisition system (two SEL-computers) and peripheral equipment are operating reliably and data can be accumulated into the nemory of the computer. The software to store dnta into the 800,000 and 400,000 word disks were completed

by the end of September 1969. Four bids for the immediate analysis computer were received in August and are being evaluated.

Experiments which are in progress, being de-bugged, or being installed on the linac include :

(a) q of U 233 from thermal to 10 eV (b) capture cross section of U 238 up to several keV using

an 800-gallon liquid scintillator (c) high-resolution transmission measurements up to 100 keV;

total cross section measurements on transplutonium isotopes up to a few keV in cooperation with Savannah River,

(d) gamma-ray spectra measurements from neutron capture in individual resonances using a Ge (~i) detector

(e) capture cross section measurements from 5 to 500 keV (f) fission measurements with aligned nuclei and transmission

and fission measurements with polarized neutrons and polarized nuclei.

Joly asked if a neutron-facility was still foreseen with the LAYG. The answer was positive.

Canada The PM Tandem at PIcMaster University has been accepted and is working well at present. The l~TRIUNT"E" Meson Factory Project at Vancouver is progressing.

Japan Since the last EANDC meeting, two Van de Graaff accelerators have begun operation. One installed at the Nagoya University is a 2 KiV machine and will mainly be used for reactor physics work. The other installed at the Tokyo Institute of Technology is a 4 MT machine and will be used for nuclear physics experiments including neutron data work.

The JMBI Linac has become so old that it is going to be replaced by a new machine of 32 NeV and 500 mA within half a year.

Sweden Wit d to the Isochronous Cyclotron mentioned at the last EANDC meeting as "under construction" at Stockholm, this should be changed as mentioned above (item 1 (a)), since final approval of the project is still pending.

United Kingdom The Harwell Synchro-cyclotron has been modified successfully. The present specificati ns are : 150 YleV protons, 4 ns pulse length, about 3.'lo1$n/s in the burst (i.e. increase of intensity by 5 with respect to previous situation) 800 bursts/s. The maximum flight path length is 100 m.

OR Countries A report on the Swiss sent t o a l l members.

l l l (b)' Progress' Reports ' , .

The 'current measur~ments an

9

. , ,

. . . . . . . . spaepen gave ' the ' f $llowing information ab

measurements a t Geel, . notmentioned , . , i n . (S)-115 - Pu 241 : measurements of Gt&i. (I'eV - . 3 j k e ~

' m a v e beenmade.:and tlie .analysis is:under.'wa - U 2 3 : the measurements of o f f r o m 0 . 0 2 ' e ~

bee: f inished . , . and w i l l b e publ~shedsoon. - 241 : a 0 -nea,~ukbment has been made (E, >

a t a detection o f near-barri&r:.fission ' ( a s indicated by' t he Petrel-resul ts of L.A.), ; n o evidence f o r , it was f o ~ d .

- Np 237 : a f i s s i on measurement has been s t a r t ed i n order t o f ind any evidence of (n, y f ) processes - no conclusions ye t . - . . . -

- - H : the t b t a l crdss sect ion has beenmeasured with high " accuracy i n the FieV region : no evidence of o sc i l l a t i ons ' . .

(reported by a Hungarian laboratory) .was.found. - , . ,

- Standards : t o be reported under agenda item 5 (c).

(c) Research Papers

k number of recent EANDC-research paperswere reviewed and discussed (some of them werediscussed l a t e appropriate a@.enda item). . , ' . ,

- (CAN)-41 : t h i s studywas used i n t 2000 m/sfundamental data , performed by'a.IAEAworking group and was.to be repor-ted i n the topica1discuss ion following the EANDC meeting.' . , ,

. . . ,

: Schmidt sa id t h a t these recommendations were and meant t o st imulate fu r the r more

systematic thought on t h i s matter (see sect ion 7 (a)). "

- (E)-119 "L" : Joly sa id t h a t t h i s was the document just i fying the French requests f o r f a s t reac tors (main requests : f i s s i on and capture of Pu 239, capture of U 238). Story found the assessment by Barre of the accuracy of arious' cross sections somewhat a rb i t rary .

- (E)-120 "L" : Schmidf sa id t h a t such t ions were very useful f o r ge t t ing a h in t on the energy regions o r nuclei

f o r which be t t e r data were needed, but the conclusions should not be overstressed.

: Eeckurts pointed out that only those data the CCDN files were olotted. The reasons for

the discrepancies with results frLm other laboratories were resolution effects, some systematic effects (like dead-time correction) and errors in the exact neutron energy values. The best agreement was found for Fe (cfr. Fig. 2, 3, 4 : En from 0.50 to 0.90 MeV). Smith said that such checks of total cross sections were very important; there were still some very disturbing discrepancies. However, one had to be cautious with some SCISRS-files : some data have to be screened by looking into the original publication. Moore added that an additional source of discrepancy was sample thickness, which might explain the differences in peak heights between Cierjacks' and Carlson's data for Fe around 0.85 MeV (Fig. 4) and 0.55 MeV (Fig. 5). Answering Nirve, Havens said that the list of neutron reference energies (see above, action 3) would only go up to 0.5 MeV.

- _(E)-123 "AL" : NBve commented on Table I1 and 111, which compared the conclusions about some low enera U 235 resonance spins drawn from various types of measurements and cast serious doubts on the validity of the y-multiplicity method for this nucleus. Moore and Havens said that the analgsis of scattering measurements had to be done very carefully; NBve agreed and said that, for this reason, a shape analysis was presently being lied to the Cm?-BCMEJ scattering measurement S.

- (OR)-92 "L" : Con oned that the experiment section error was 5% except for Pm where it amounted to 7%. UIC -111 "AL" : The error of the experimental value obtained -b for the cap use cross section of gold-198 for Maxwellian neutrons (25,102 ?: 3716) is smaller by a factor 3 compared with previous results.

- (W)-112 :lAL" - : Rae pointed out that using the B 10 scattering results reported here, and the B 10 total cross section results of Diment (AERE-R-5224), the shape of the resulting (n, a) cross section agreed with the Bergman-Shapiro expression which involves a constant term in addition to the l/v term (see also Fig. 3 of (UK)-113 "&").

: Pioxon1s results agree in shape with those (Menlove and Poenitz), but the value is 13%

lower around 30 keV. Rae asked if this disa~reement would t be due to-improper knowledge of the neutron spectrum Kzrlsruhe. Smith and Beckurts answered that this had

een checked and was found to be a small part of the error quoted. Eeckurts added that if the U 238 capture was indeed lower by 13% than the Menlove and Poenitzts value, then it would have 8 serious impact on fast reactor physics. Rae considered that some good evaluation work should be done now. Lynn had made some theoretical calculations and found a value intermediate between ANL and Harwell data.

s t o r y sa id ' that t h e 'accurai$:. ~f .%heore%i.c&!- calculat ions. was probably not be t t e r than 1576 (other -parameters:, l i k e the nuclear radius, were involved). Havens mentioned t ha t i n resonance ana ly s i s ; one could ge t : a -self-consistent se$ of r e su l t s , but t h i s did not y ie ld t h e - t r u e experimental' accuracy ; an example. was the, difference.. between average

va lues quoted by d i f f e r en t au tho r s , . ' Other'cpimittee e r s mentioned tha t . fur ther work o n U 238 was. under way CPm . ( ? to from 65" t o 600' e8].' and Earwell' U t o t , low

energy regionj o r pl,-ed :at. M O ~ . low. ,.energy region). . , , . . .

star$. m&ti:onkd,that',this, ei&uat.ion work . . wa-s..n.eede .. f o r neutr.,on "age!' calculations. .%'her&. was, a 6%

spread among the available data on thebound coherent t t e r i n g amplitude of D20, and i n addit ion age'measurements

oalculations, indi.c+e.d t ha t : .the .fie sca t te r ing cross section of .l)&, shpuld be. i n e r than , . ,

. . . . . . decreased. . , . , . . . ,

: T h i s evaluation work indicates (cfr . Table 11, masis-.exc'ess.. :dat.a .'are i n ,;exce , and. n o t wi th , the sol id-s tat

<on,&luded that . . further. accu nt4 k ine t i c . :energies a r e nee:d

- (UK)-116 "U" : This evaluation points out ed' f o r r e l i ab le measurements of hermal neutron secttbns for $11' . ,.. . , . . :

. . . . - iUk),-? '7 -,.t$: .: at ion indicates d S e g i ~ u s ' l a @ . of knowledge o . t sorption.' cross sectloa: (a 100 t o 200 mb) and excess resonance in tegea l (0 .01 t o %.?=b. ) O f natural X i . . xt i s mast probable t h a t a . number of neutron .resonames are still t o be discovered. Neasurementshaye , . . . . , . , . . been ca r r i ed out a t Harwell., . . L , . ,. . g . , , , , . . .

. ,

: ~anna';$ema$ked t h a t ' the ha l f - l i f e of : . , X.-105'obtained a t ANL - f o r U, 234 would .bring -, - - - - . , - ~- : ';he BCPm 'value fo r ' U L(U-235) up t o . 589 b. , -but t h e valuk 'recommended :by the I A working groupwould-only, be increased by about 1 b. (from 580.2 2 1.8 b.).

- (US)-125 "Ar! . .. : The value . ... . , . f o r the .Be 7 branching r a t i o reported i n t h i s documEnt ~i.~t; ' '0.1051: ?'0.0018)- agrees w i th the older ~ ~ .---- p ~.

Canadian value of 0.1032 6.0016 (0btaing.d-by Taylor and . . . Merritt.) . Xpaepen mentioned. t h a t apreliroinary value obtained

a t the BCiQT agreed with t h i s ANL.lka1u.e. * . .

-~ (.US)-l26 "Au : .Thevalue of (934.2 6) b:. . r epo r t ed fo r the thermal absorpt ion cross section' .of ' L i 6, agrees with"the

, . . . .Harwell r e s u l t s of 940.3 .+ 3.2 ,b.' ( see . W D C - 8 1 "U"' page 30). . . Spaepen mentioned ' t h a t 1 ; ~ ~ w$s pl ' ake a. d i rec t

. meaeurement a t 2200 m/s. . . , . . . . , .

- (US)-q29 "An and (US)-130 "An : Measureme shielding problems.

I n addition t o these reports , Smith commented on two preprints from Argonne : ,:.. . . . . . ~.

- A measurkmentof ;d. ' t& (Carbon from 100 ke V up, to 1:.5 MeV, b y Meadows and Whden: a 'good f i t had been obtained with parameters. s,ome.what , , , di f fe ren t 'from , . those obtained i n Japan.

' - A measurement: by ' . , c~o~ -(.relat,&d ':to ' the ' Sifiguardsi program) of the delayed neutron y ie lds fromu' '235 and

2MeV t o 2.5 MeV']: the yield kia i n disagree'ment with t.he r e s u l t . ~. . , . . .. :. . . . . . . ,

. , ,. . . .. , . . ,, . ,

. . , . . . . . . .

. . , .

PIomota, dis t r ibuted .and coken te of tlie' Japanese evaluatiollon C, ,by

and on report (J)-15 "AL". . .

' . .. . , . . , . . . . . . .. . ~ , , ,

.:: (cl) ~ e b o r t . ~ ; . on .new . r&su l t6 on - the alpha value. of 'h 239 . , ' , ' '

. , .

. . . ,

' J q l y Said. tha t a measurehen$ of ' . total-.and f i s s ion s sedtibn'on a Pu-239 saris16 a t 1 i q u i d : N ~ temperature had erf ormed a t Saclay. Data w$re now avai lable f o r Tn bEgns up, t o 660,:eV and r i up t o 500eV. , I n a d d i t i ~ n , an,

irradiati0n:experiment of Pu. 240 ;,.h, 239 andU 238 sa.mples i n f lux spectrumpeaked a t 25 keVhad been performed and the

nalysis , presen t ly under way, should . . yield a n a-value., . . . a t 25 keV. ., . . , , . .

. .

. .. .. , . ..

o r t s

- (US)-128''uAfl waspresented bp ~mi'th. In the energy range studied ( I 30 , t o 1400 keV) . the r a t i o s U 238 (n, y )/'U 235 ' (n , f ) and 'Pu 239- ' (n, . f ) /U 235.. (n, f)..agrei?d with previous measurements, and' the 'da ta were over determined s o : a s t o check the in ternal consistency.' A t p resen t , abso lu te U 235 ( n f ).-measurements:were. under way a t a few selected energies between 30 keV and I MeV with ( Y , n) sources. ' ~ ,

- .. :~):232?:: !!&!'.was ...P eeken$,ed...by, Backurtsi :, I\he:,ratios Pu 239 {n, f ) / U 235 (n, f ) and K:2)J.:(n, f)/ii..23:5 ( n ' , had been measured from 5 keV up t o 1 MeV. The

' '(U~)-128. 'and D&+ey'' S.: evaluatipp Was- g6 t ha t f iss ion: cro t i . 0 ~ measuPement

, plannkd': at ,. , . .. . . L . . I . ,..~ . . . . I ! , ' .' ,)

. . .,:.. . a . . . . ~, . . . . . , . . . . . , . . .

, . , .I-Joly. ,mentioned. t h a t abso1,ute a ; f i n the region 5 keV - 2 M ~ V had bk'k$perf Prel'fminaky: &su15s: b6twb,gj '.F&guson ( i n f a c t , somewhat closer t o Ferguson's h f lux measuring te~hniques~~ere,checked,by.reproducing . . . .3, . .~, . them . a t BCMN .

Rae said.. ' that the~arwel~-measurements. on U 238 with the l i nac would be extended t o higher energie h . c b t i l l a t i ~ n '&kector .!: , . ~ f :it,:i.,ere , . .~ ,.

. . ~ . '"black"- .det&tor, would:.be. to, dalibr&g::a S . . .aet&ctors in. a,, separate., expe*iment ; , . ..,~, : , .: : , :,

. , . . . . " . . . , . . . , . . . ~ , , ' ; : :::.

It was concluded from,. the discussion t h tie: me;isur&',,en*$.look&& .'faif:ly..;go,bd,, .the; :&bsolute U 235

. , . ~ . . , . n :cross: $e,cti?n., ,$.$S ' s t i l l a -ve+ .opbn'.probl:em'.c. A s ' ,

,asurem&t&- ,on . - th is .,qu-mtity- under way:&%: A~Zgonne, ' . , :[ r k b d b . :anai'c&a&rach& ., B e & ~ r t + .&W: JOT':: e r e 'a'sked . ,. . - . , . ,

to: .try . . ! t o 'produce , . . status , report-$ for ' the n ' ... . . . . . , . I ' . ,.. . . , . ." , ., . ' ... ' , > , ' ..; ;' , . - . , ' ' ,. .'..,. .

(a) Second Conference on the Physics and Chemistry of Fission, Vienna, July 1969

. . , .. :, . . , ~ . , , , : ! '

. . GOo'd ..&id, t ha t .t&g .'!Proceedings ;of :: the . Conf eJX?ncen .~hbu&d:.~omeC i n ! J&u&p~ '1970:: .abd .wi-: ~ o n t a i n t h e fu31: t e x t o f :.the invited:' papers',: a : d&densed :.tr~rsi.0n.:,gf t h e contrzbutions present& $r,a$.xy ,,,. &id.& .the;:abstracts. of '1 a l l :~

. . . , . , . 8 , , . , , , . . : S

, ' submittgd:a - ;., , . : .i ,, . . . , , . 1 , ,

. . .., ., . . . . , . C . , , , . , , > ! . . , "

. . . . . .. . . , ~ . ' . , . : , .. , . . . . . . . " ' i : . . ,

, , . , .

remaSkabl&: fact :had, .beeb.: the: $&act of St ru t insk i 1s model; bout. &g' thir&. :d f..:gll; ,&htributions .w&re mare, o r l e s s emted td ; th& ' !'poub&+-h~p&" .fission:pot.enti&li barr ier . : .. bac@rdi~g . .data,,? b~.f6rf' mdr&:!:dirgct !interest ; t o "th'e =DC ' he, pointed

9 . u t : the: &i&&k&p&t >esults f yom.!mIi and Dubn$ on: IJ: in: the : 239

resonances, the smooth behaviour of. delayed,neutron. y ie l~d i n the 14-15 MeV region found i n the US and i n Gerniany, ?..a disagreement with the Obninsk r e s u l t s , and the theore t ica l calculat ion cf de?,.ayed neutron sp:?ctm perfcrmed a t Saclay,

. , , ,. - . .

, , . : - .. of ;oalcula$ion:s;, ,with; integral: data. :., .: ., . . . . . . . . . ,. , , . , . , . . . . . . . . . . . . . , : : ,,,, , . I . . . . , , ~ : :., ..:. . , ,. . . .,-, :., ; ; . , . . , ..,. . ., . ,

. , ; . , . . . . J?here . s , ~ ~ & d . :td: be., a, 'fair,.gea&rk' c i f 'a$re.ement 'about they-ma& adjustments: needed,' :butj t h i s ' m& be.., n o ' m o r e ' y . t ~ : . a ref lec t ion of the fac t ' tha t . . . ,.,. .everyone ,. $:<ends .,. . t o use . . . . . imore:q l e s s the same s e t of in tegra l experiments.

. . . . . . . . . . . . . . . . . . . . " > . . . . . . . . . . . . . . . . . . . . . . , , , . .,. .

.:of the-.ihtRg@al &aiu+kS@rit5:; repo.?hd: related t o ym_fuelled',':fast' reactors. , ':The::@rit.ical assemblies

con.si@ered. were ... MASURCA: i n '.Franc:&:,', :SNEKfC:$n"Germ&,,:>: t h e . JAERX f a s t c ~ i t i c , a l , .... , . . _ assembly l i n Japan, FRO, i n ~ijeden,:~'~EBRA ...... :a$d VEU i n t h e U,.K ,.,, &b. ZPR. 3,. 6 and 9. i n the.. U.S.A. .In addxt'ion measurements were made i n fas t ' spectrum test"zones" 'dr i~ed by thermal reactors.

Comparisons of theory with experime o critical;~::sLze;.: reaction, r a t e , , r a$ ios at, core centre; oore centre perturbai5ion'data ,'.'and central-'.void 'c9efficients .: I

, . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . .

here had been.a;:well-attended panel :meeting on data one, evening. Least :sq~~res:adjustment ,p.roc.educes

ev8loped,' with :some diyersi.ty:i.n t h e treatment of ..

a r r e b methods: Mere .describe.d:..in de t a i l i g ,,. :.- . , . I :

120. John Rowlands would describe h i s w~rkr-op t h e EANDC topical discussion on 10th October 1969. (Story added further tha t i the- timec:.sca1e~. of; f as$:. re.aq$or .d.eyelopment had forcedl,:the .adoption of ,~adju~trnent~~pro~edures: f o r ~ n t e ~ r p o l a t i o n

Neutron spectrum measurements had been reported from France, Germany, Sweden and the U.K., using a variety of methods. Storgfs understanding was that measurements above I MeV were still not good enough.

Much attention had been paid to Pu 239 alpha, especially for the region below 15 keV. There seemed to be an increasing measure of agreement with the differential data (see section 3 (f)).

Heterogeneity corrections seemed still to be a possible source of error, though attemps had been made to measure average cross sections (non-local values, rather than highly localised values).

There seemed to be differences in absolute reactivity calibrations based for example on central perturbations with fissile samples and calibrations based on absolute delayed neutron yields. This uncertainty of about 30% affected all kinds of absolute reactivity measurements including Doppler and sodium coefficients, and control rod worths.

Of the various Doppler experiments the activation method introduced by the Swedes seemed especially worthy of note, it reduced the heterogeneity problem.

S conference was summarized by G.C. Hanna. There ticipants from 29 countries; about 370 papers were

submitted, and about 30 review or invited papers were presented. The summary was given by E.P. Wigner who stressed the need for greater concentration on fundamental concepts. New experimental developments were discussed, and heavy ion accelerators and the prospect of studying superheavy elements were emphasized. The Proceedings were planned to appear 10 weeks after the conference.

) Smosium on Neutron Capture Gamma Ray Spectroscop;~, Studsvik, 11-75 August 1969

This conference was summarized by H. Condi.. The symposium had about 110 participants from 20 countries. About 70 papers had been presented of which 52 dealt with thermal neutron capture and 18 with fast capture. The symposium had 9 different sessions covering both experimental tec

en given of the reports and the final proceedings would appear as an IA;EB publication (Spring 1970?).

An introductory talk had been given by Prof. Ar Bohr (Copenhagen) about the theory of nuclear dipole modes.

Several new techniques and improvements had been reported i n the technical sessions, e.g. neutron guide tubes, in te rna l p a i r spectrometer, and improvelnents of bent c rys ta l spectro- meters a t ANL and Ris$ .

An impressive amount of da ta had been presented a t the thermal capture sessions from measurements on about 50 d i f fe ren t isotopes ranging from Mg 24 t o U 235.

The sca t te r ing of y-rays from (n, y)-reactions had been successfully used t o study both h i m y excited l eve l s near the neutron binding energy and low energy l eve l schemes.

-

Before the f i n a l sessions devoted t o fast neutron and resonance capture D r . A. Lane (Harwell) had given a review t a l k about the theory of neutron capture where he e.apecially discussed the channel capture theory. -

The "5.5 MeV anomaly" observed i n f a s t neutron capture spectra of heavy elements near closed she l l s had been discussed. A qual i ta t ive agreement with experiments had been reported from c a l the semi-direct capture mechanism.

discussion about the future of the "Slow ~ e " the .conclusion D r . E.D. Earle,

(e) Conference on Computer Systems i n Experimentai Nuclear Physics, Skytop, Pennsylvania, Narch 3-6, 1'369

Report (US)-123 "LT1 en t i t l ed "RBsumB of Impressions of the Skytop Conference", a s observed by W. Havens (Columbia University), J.R. Pasta (Universit of I l l i n o i s ) , R.B. Lazarus (Los Alamos) and A. Smith (Argonne , was presented by Smith and Havens and discussed.

7 The conclusions of the Report are the following : -

1. Computers have made a great impact on experimental physics but they have not basical ly a l te red experimentd. philosophy nor has t h e i r potent ia l been exploited fu l ly . Pa r t i cu la r a t t en t ion should be given t o establishing the essent ia l charac ter i s t ics of systems operating i n problem areas with the i n t of providing guidance future usage.

2. The emergence of a new special ty i n experimental nuclear physics, computer applications, i s i n evidence. Continued a t tent ion must be given t o coordinating this special ty with the basic f i e l d of nuclear physics and with computer sciences.

, ,

3 . At present there is an immense variety of approaches to essentially similarproblems. Some of these ,amount to establishing central computing facilities fraught with familiar problems. Th evi unique answer

4. The economics of computer usage in the experimental context are not quantitatively known. There is need for a realistic accounting of costs if reasonable fiscal planning is to be achieved.

5. The use of computers in experimental nuclear physics is stabilizing and the same judgements applicable to the acquisition and operation of any major piece of experimental equipment apply. This is inclusive of the decommissioning of obsolete or ineffective computer systems.

6. Standardization of interface hardware and software should receive prompt, continuing, and detailed attention by competent groups. In particular the standardization of interfacing should be referred for immediate attention to the established AEC-NIM Committee.

(f) IAEA Meeting on Alpha of Pu 239, Winfrith, U-K., 30 June - 1 July 1969 This meeting was reported by J. Schmidt.

IAEA had called together specialists from France, F.R. of Germany, Japan, USSR, UK and USA, besides ENEA and IAEA re~resentatives. The main conclusions and recommendations had been the following

The agreement between the different series of differential measurement ved during the past year and the accuracy was in <of> .

<oa> (This is equivalent f ?: ?O% in alpha, when alpha is equal to unit ossibly some of the main remaining discrepancies were due fferences in primary normalisation. It was agreed that in order to aid in the solution of the normalisation problem the resonance alpha values used for normalisation should be based on eta and/or alpha measurements extending into the thermal energy range. After having obtained the sets o ~ - ~ f f e - ~ e ~ ~ ~ E ~ - Z I ~ ~ values used for normalisation in the various experiments, it was recommended that the experimentalists involved attempt to get out a common standard set of resonance alpha values and renormalise their measurements to these. The renormalised average alpha values should be made available to the specialists attending the meeting and other interested people. The experts finally recommended to the UEA to continue, through its Nuclear Data Unit and in

co-operation with the other centres, to help in providing the necessary information and data for the CO various Pu 239 alpha measurements.

(2) Alpha values deduced from data adjustments Some cross section adjustment studies had been made

at Cadarache and Winfrith, but the conclusions were somewhat uncertain, as the adjustments may depend on the uncertainties for data other than a(Pu 239), and on inaccuracies in the calculation methods themselves.

(3) Integral exueriments Several integral experiments had been performed and

analysed in the US (Argonne and Brookhaven), UEC (Dounreay), Germany (KFK) and France (Cadarache). In the energy range 1 - 10 keV, they were well fitted by the latest Harwell (Schomberg, Sowerby and Evans, (a)-100 "AL") and Gwin (not yet published) results. In the 10 keV - I MeV range, the evidence from integral experiments for an increase in alpha- value was still inconclusive, and further work was needed.

As a general conclusion, it could be said that, although some further work was needed (and was in fact underway at several laboratories) agreement seemed in view.

(g) Other scheduled conferences

Regarding the IAEA conferences, Good gave some infor- mation about the next Conference on Nuclear Data for Reactors, to be held at Helsinki on 15-19 June 1970. The preliminary announcement came out in July 1969. The program committee would try to have the conference more biased towards reactor application than had been the previous similar Paris Conference. The sessions headings would be : general aspects of the needs and use of nuclear data, high-accuracy measurements, data in thermal and resonance energy region for A > 220; the same for A C 220, data above resonance region for A > 220, the same for A < 220, relations between microscopic and integral data, evaluation, and instruments and methods. A few special subjects would be treated by invited speakers (nuclear data for astrophysics by Fowler, nuclear data for controlled thermonuclear energy by Golovin, and theory of nuclear reactions . A total of 14 inv peakers was foreseen.

Following a questio eckurts, Good said that there were no IAEA plans for holding a neutron physics conference similar to the 1965 Antwerp Conference. -

Havens mentioned that there was a proposal for holding IUPAP conference on the statistics of neutron resonances, at

the State University of New York, Albany, in 1971. Good asked if a session on this subject should not be included on the program of the Helsinki Conference, or alternatively whethsr

a meeting o n t h i s subject with l imited attendance could possibly take p l a c e i n Leningrad j u s t vefore jHelsinki;' The opinion of Havens on this was negative. The 'sub j,ect was : too specialized f o r .the.Hel;sinki Confereqce, i t was . t o o l a t e t o . g e t something done, and the U S at tendance would b e . v e r y . . . limited., , ,

. . . , , .. . . , , ~ . .

: , ' ~ d l s t a d had been informed' b " p a n e l o n instrumentation f o r low ener

sca t te r ing wo.uld. be .held% i n -,-November . . , ( , . . ,

~ o o d added t ha t ' thk p

accelerators.

The problem of a "world-wideTt request l is t wa~":d%scussed Eolstad remarked t ha t a s long a s a r e q u e s t . l i s t f,rom non-OECD countries, s i q i l a r t o the , EANDC-RFENDA- l i s t , . h a d not been d is t r ibuted and: ,discuss.e@, no decision fo r - a . ,W co'uld be' taken, The 'Committee- .agreed .. . w i t h t h i - ,

Good reported progress i n this matter. asked the non-OECD countries.. for.. l i s t s : of: requests;f o r reactor and other. applked .needs arid RENDA has:.been ,d is t r ibuted t o them a s a model. Following this enquiry,' t h e IBEAhad. received since June 1969, 135 requests from the USSR, Fin land, East- Germany, Hungary, India , South-Af rica,,,: Pakis tan etc. . . Most of them (110 ,out of . . 135) were:'.neu. reqqests;. . i,. I+. not appearing asbsuch i n t he :latest RmDA., Hoi$ever, -:Some. coun'trie S had sa id t h a t they would be ready: t o .-j'oih &me of the -REND.& requests, Accordingly,' t h e 1~~kA was' fioxi &skikg t h h no'n-OECD ,countries exp l i c i t l y what RENDA requests they would support joint ly . NO supporting document had been asked:'for.:(the.:~t.i.ming :imposed d i d .:not allowrf on : i t ) , but only corpments. It.. could be infer red from these i f t he . request was . ne.eded .fo+'..reactor technolo y o r f o r S urposes (e.g. ac t iva t ion &alysi.s$. , . . , , ~. , . , ., . ,

It was suggested t o Good t h a t a supporting document .might bea sked for. from t h

. ZNDC % meeting, ,and: t h a t t he requests f o rnon- might be . ;grouped:; ina. . . . . . , . s e p a r a t e ' l i s t .

. . . ~ G;'od"said' that. was

l is t s e n t t a the F3A f a .. view . , . : t o p r i n t i n g :it b y . ~ .~

------- ------ Spaepen said that t h i s l i s t had been discussed by the

Euratom Data Committee. Each class of ,requests hadbeen screened by various- special is tsand t h i s atep was nownearly finished. The revised l'st would be

, soon.

it

sooner than 15 January 19

. . lusions . . ' ' ;

. , A ~ S members ;:are ',ask$&. - . r ev i sed l i s t s t o Maaame Solanes as soon, as ..poss&ble ,,, ;ind i n . any case 'not . l a te r than January 15, 'l970. Whereno revised~li 'st .3 have been received b y t h i s dead-line, the older , . . . requests . . . w i l l be retained.

Madame Solanes asked a l l members t o give detailed information for each requestor ( in i t i a l s , address etc...).

.., Th,e most, 'appropriate way t o . ' r e v i ~ a t the 14th. W D C Meeting was discussedl 18 Wd actions a r e reported i n se'ction 1 1 (a

, . , . . . . ,.,. .. .., ! , . . , , . ,

(c) U C R P recommendation$,

A . list!. of specif. t o EANDC had 56jeeci ' ' uo t6d ' - EANDC-81 , mA:lI. . ~ 3 % , m e , t h e , present . . . meeting. . . : . ' .:

(I). Prompt f i s s i o n n ---- ---A--

NBve sa id t h a t , according t o information from Benzi, a measurement had been ota lognti, . using . & elaborate proton r e c o i l count.er ., . .,. .: , .

Moore sa id t h a t some work had been s tar ted a t NBS, using a-converter p la te i n .%-yeactor thermal, ,column and both a c t i v a t ~ o n .ap@ ,direct';measurements., 'Some work --was 'also uhaer way a t Argonne w i t h TOF techrliques (cfr . Wash 1727)-

, , An act ion was put on t h e ,US and Euratom delegates, t o repor t - .on. -the- -US work a id -the .:.Italian work ,. respectively, a t the next meeting (see a lso sect ion 5 (a)) . . . . ...., . .

(2) I ne l a s t i c __I________U scatterf~.bL~..:23.8'..in:the.0;8, __ - __------.---------- t o 2.0 MeV ran= . . --- , . . ,.

Smith sa id t h a t a measurement of t h i s quantity had : been performed a t Argonne , in.: addit ion t o theore t ica l work.

. . It had ,. been -.f ound : t h a t . the .hypothesis of a - s ta t i . s t i ca1 d i s t r ibu t ion . of. , levels was good _above l ; 5 MeV. In ,addit ion,

: ve ry good agreement, between theory and exper~mept '':had 'been found f o r -the-. exci ta t ion, ,curyes of .:some individual levels. The a reement; between evaluated :aqd measuredto ta l . ( n , n ' ) and

. . (n, ;ny .cross sect ion bad a lso been godd ( the .%ful l angular d i s t r ibu t ion was measured, while previous measurements, e.g. those o f Harwell, were l imited t o one angle). It had been concluded, . tha t a t presen

,,. . .

he committee a s k o, the Laboratory Repo

, . . . . ,

NBve said that. scatt atMol and Geel, ,,at ,,the: BR2 a these measurements ,would ,be ve integral -, was proportional to t jn for low-lying resonances fo

Ca&ure'byU22 -- ----- -- i n the keV to ------ 100 keV range, fiis had been discussed ui%de$! igenaa item : 2 (c). ' .

added that measurement's at a few se1ected:neutron energies were. being carried out by Axton at NPL (between ' '

30 keV and 1 MeV) , :using.. a Li , (p', n) :source and a Yln bath. ~.

of ..m -- -------- This had been

3 (f). , , I . . . . ,

. . . . . , . . . . . ,

,. 6)',stibcommittee on Evaluatio ----I ----.----------- --

,. This was ' discusked. later ' , , ,

. . .

. . , .

5. . I~JTERNAT,IONAL CO-OPERATION ' m- $HE SUREME MEN^ 'OF NUCLEAR DATA : : . . . , , . . , . .

This field . . . ~ ,.

compilation by Hanna et al. a at ,2200 ,m/s .. - cfr. Atomic En.

, . Chemistry. of Fission (only the-. abstract is available) which gave for 'the 'ratio' of total c (Pu 239)/0 .(Cf 252) = 0.7

evaluation). . , . . . . .

egarding the 'abs rted at the Gee measurements h ep. and ANS Meeting, San Francisco, Novi 1969).

These twq measurements, r agreement. , , . ,

An offer had b ribute goia f oils with Cf 252 for intercalibration of primarily the fission rates (se'e J. Nu 7, '1969). ' Foils'had been sent to. BCMN, ANL and o results were. yeat available.

, , . . . , . . . . , . , . . . . .

~ e ~ a r d -energy dependance of C, widely d5screpant. result S in the :Pu 23q:resonances had been presented at the last Fission Conference by RP1 and Dubna; In, the EeV region, measurements were in progress at AWRE and in France. For the latter (by Soleilhac), the range was from 200 keV un

t o 1.5 MeV; TOP techniques were being used. For U 23.5, the r e su l t s yielded a s t ruc ture (of up t o 1.5% amplitude) superimposed on the overnl l l i nea r behavious vs E f o r Pu 239, % there was some indicat ion f o r a s t ruc ture , but muc weaker than f o r U 235. It was planned t o try t o measure below 200 keV.

A t Aldermaston, spot measurements, each covering a fair3.y broad energy band, i n the energy region from K) keV t o '1.5 heV were i n progress. No TOF technique was being used,

There was no recent news from Boldeman (Australia).

The. :C.ommitt&e suggested t h a t ~ o l e i l h a c .mqet the AWRE measurers and t h a t , both, prepare a .short . . , , WDC-dociimeqt . . . . ~ ~ cbmparj.ng t h e i r r e s u l t s f o r - the 'nex

d be useful tha t t h e IAh.

supparted thi.s-proposal..

. .. , . . . . , . , . . . , .

Smith reported ' t h a t :

- Six newsletters had appeared since January 1969 - Preprints , Reports etc... had been exchanged

- Samples had been exchanged (mainly among the U.S. labs) .

The question of cos t ly samples was discussed by the Committee, They could be cos t ly e i t he r because of isotopic requirements or because of fabricat ion costs (or both). Answering Spaepen, Kolstad sa id t h a t b i l a t e r a l agreements applied t o the loan of samples prepared i n the U.S., but the recipient was required t o send the sample back t o ORJVL which was responsible.

It was agreed t ha t Smith ( fo r the US) Cond6 ( for Sweden) and Spaepen ( fo r BCPN) should prepare a l i s t of r a re samples su i table f o r sca t te r ing measurements, which would be available f o r exchanges.

(c) Report of the Standards Sub-committee

This report i s reproduced a s Appendix 2.

Among the conclusions, the need f o r a meeti-ng on Standards was stressed. This should be devoted t o the assessm,cnt af whnt has been accoapliehed i n recent years, and

t o the. . d e f i n i ~ i o n ~ ' o f fu ture need . ~

, ~ : , . . . . , ,.

I I t w a s pro'pbiied'tohol g just before: an M D C . meeting and in ' -a ,no't to6 re . The W D C strongly supported th is proposa-l.

(It was l a t e r agreed t o hold the meeting immediately before the nex5 W D C meeting - see item 11 (b)).

(d) Other areas of in terna t ional cooperation

Spaepen reported on the f i s s i o n f o i l exchange programme between Idaho, Chalk River and Geel. Fo i l s had been prepared and a-counted by BCMN, and sent t o Chalk River and Idaho f o r a-counting and chemical assay (by i so topic di lut ion) . T h i s programme-was under way. People-volunteering t o join were s t i l l welcome.

Hanna ra ised the poss ib i l i ty of internat ional cooperation on the problem of prompt f i s s i on neutron spectra. After some discussion, it was suggested t o Schmidt that t he NDU of the IAEn be l e f t t o co l lec t a l l the data on this problem and possibly i ssue a report on our present knowledge of N(E).

Hanna was a lso asked t o produce a working document f o r the next W D C meeting, compiling the information he had

6. INEORMATION ON OTHER NUCLEAR DATA COMMITTEES

(a) Meeting of the UCRP, London, 10-14 February l969

This was reported by Rae, who attended the meeting a s U D C observer.

A paper by Went (Holland) had been devoted t o a comparative study of Th, U dnd Pu f a s t reactor systems. It pointed out t h a t q (U 233) was more favourable than q (Pu 239) i n the KeV-region, and concluded t h a t the cross sections important f o r the Th f u e l cycles should a lso be looked a t carefully. (Beckurts mentioned that there were some data requests pertaining t o the Th cycle, namely from I t a l y ) .

The usefulness of measurements on separated f i s s i o n products had been discussed but no c lea r conclusion had emerged, except t h a t i n the case of a sample conf l ic t between an integral. and a d i f f e r en t i a l measurement, preference should be given t o the l a t t e r . Beckurts added that f i s s i o n product samples had been requested by EFK f o r d i f f e r en t i a l measurements, but t ha t up t o now no answer from AEC had been received.

(b) Meeting of the I N D C , May 1969 . ~

Good' summarized t h e meeting, and gave . the . . . l is t o f , .

recommendations t h a t were agreed upon. . . .

(1 ) - . . The Goprnittee . recb&nend,<th&t one of i t s members.. or a .sui table a l t e rna te attend., a s an observer a t CODATA:. meekings t o ' keep the C o h i t t e e . informed o<'@DATA a c t i v i t i e s (ip e.. " - : ,. in terna t ional c o o p e r a t i o ~ f o r the compilation of a l l nuclear data , other. . . . than neutron, . . data) .

( 2 ) , ' .:The ?@&ittee stqon publish. a l l of .the. papers I . a c Conference on Nuclear . .-Data . f o r React0.r:~ .. . .~ , . . ~. . ~ .

. , . . . ,

(3 ) - : 1: The . cqmrni c&nmend'ed. :that:, the UEA CO making : budgetary. .provision, f or supplying ,:, especial ly . . developing member, . . ~ . ~ . , .,.. states , , needed samples : f o r , cross,. & measureme'nts. The Committee' w i l l be w i l l i n g , t o advise t Director General on the merit of speci f ic proposals.

,. ,.

(4) '. e rec,Qmqenhs t h a t t h e I A E B plan: t o sponsor a s m a l l symposium not l a t e r than 1973 on the col lect ion, compilation,; ;indexing ,,, evalu data , : especzallyi. .. . other . than neutron data,. . , ~ , . .

,~ .,,... ~ . . . . . , . ,

(5) ' . . h e ~'ommittee' rec&meqds t h a t th respons ib i l i ty ; f o r t h e pr in t ing and. .dis t r f rom J,anuary, 1971 onwards.

During the course of" the advanced ~. the . following . sugge

, , , ~ .

Thk: ' f ol1.owing Pan e considered f o r t h

(i) Cross Sections and Standards for High Precision

.. . , . .

( i i i ) Discrepancies between Microscopically and ~nt .%grai ly Measured Quant i t ies . ,

(iv) Properties of Nuclear S ta tes (v) Resonance Parameters

(vi) Transactinium Nuclides

(7) The Agency should have a Liaison Officer i n member s t a t e (which has an i n t e r e s t i n Nuclear Data and individuals technically qualif the assignment)

(8) , The Committee should be supplied f o r consideration.. a t its Third Meeting (in advance) with- a out l ines . an Agen n ' a c t i v i t y t the' Review. of 'Cr a t . . 2200&/s'ec . . . .

(9) The l i s t i n g of non-~uro~ean-~mer i ' ch nee measurements should be t r ea ted , f o r the time,being, a s a separate' .supplement. A new- e f f o r t should be; made t o secure : contributions t o the' supp lementaq ' l i s t .o f requests-envisaging a revised concept, viz. , reques tsshouldbe ' s ta t .e&~in~ependent ly of a p r i ~ r l i s t i n g izl order t ha t r e a l i z ed . Some iden t i f i ca t ion o i n the. pr inted ' li 'sting . . : Measure l i s t e d needs)' should- be, t rea ted ,

. . , , ' measurement- , r eques t s , . , , : . , , . , . . . ,

Regarding,. ite.m (7), a l l EANDC e asked,. . . . r i a t e names t o Good., .

.. . , , . , . . . . . . . . . . . . ~ . , ~, . . .

. . ' ,Regarding' i t e m , ( 3 ) , that: a - budget &ould::be '

provided f o r i n 1971, but ' the anbunt. was still vague, ,and he - . . '

asked f o r suggestions. A t present there was no more- thb 'one request per year, but t h e r e . would cer ta in ly . be g increase if funds were available. QTDC ' would. -act . a s adv5sor t o s demands .'-:,At ' present, a , S& of about $ 1 25.000:,was~ bei considered f o r 1971. Moore and Smith. thought~"tkiis~wo - adequate f o r 2 t

, . , . . p e r , yea , ,, . . . ~.

added: t h a t t he . capabi l i t ies . o.f, .&l :and ORNL.':::; : would be communicated t o a l l IAEA member s2iowedan updated BCMNdocument: on this gn one copy' to': a l l ZAlJDC member's. ' - . .. . . ~

7. INFOFXATIOIY ABOUT DATn IItDMING, COMPILING AND EVALUATION

Good reported on these ac t iv i t i e s . . . . . ,.. . . ' , , ,

A Meeting would be held eib OSCOW, grouping representatives of the Data Cent e r s of Brookhaven., Saclay, Obninsk and Vienna. This . . implied t he *exlying. : - .... :

recognition of 4 major Centers, which was important f o r IAEA. The question of the, exchange format,. would. be extensively discussed. ' T h i s ' c ~ o n ' ~ format should apply, t o the d a t a , . , . . ::.. .

them,selves ,. a n d t o a l l the auxi l iary inf ormatidn needed:'f or . : understand,j+g,::the data. The other point t o bed2scussed was". . . .

and internat ional da ta index, which, should. be i n adequate format f o r r e t r i eva l s by any centre. It would l ist data ' . ; available i n a l l the centres.

The Brookhaven. Panel Heeting (Feb. 1969) had been more concerned with gener,al.information on the working arrangements and capab i l i t i e s of , each , centre. . .

. . . ,

THE CINDU index (i .e . : l is t of exchanged data ' and of data avai lable a t Vienna) would be republish t ed i t ion would appear i n January 1970.

Good raiskd ' the question o f ' the take-oirer of CINDA by the IAEA. The ed i t ing would be done under o o ~ t r a c . t , b y CCDN, and the pr in t ing and d i s t r ibu t ion by Vienna. Anappropriate IAEAbudget would be avai lable in 1971, but wasnot avai lable f o r -1970. From1971 onwards i the subscr ip t ion ' ra tewould l i e between s a n d l 0 $ per copy, but the preselit f r e e d i s t r i b u t i o n

. ,

. ' , . . . . .The problem of - t h e 1 9 7 0 ga

scheme was e headed by '. . .

her study and

rs ion of CIMDA s ions o f r e s u l t s n t r i e s which a r e

l e t e , insofar December 1970,

. . . , , . ,

ding a s ingle . . ,

n t time scale,, n t version,. of CINDA t o conta in

a y , t h e inconveiiience t o users of having multiple , ,

ocuments, w i l l be minimi:zed. A t no ' t ime w i l l ' . there be more than two volumes of CINDA i n current use: CINDA-71 and t h e . current supplement. (As. the current supplement~approaches the . s i z e of CINDA-71, oonside- ration.may be given t o another closing date f o r Volume I1 of CINDA) . , ,

( iv ) The second supplement f o r CINDA-69, perhaps t o be known a s CINDA-70, should a l so be cumulative i n the sense t h a t i t should .contain the e n t r i e s made f o r

' the first:: supplement of CINDA-69.

The Chairman wi l l ' in form the Director General of ENEA and the Chairman of INDC about these proposals.

Regarding the f inancia l aspects of the problems, Kolstad informed t h a t the U.S.A.E.C. would take charge of the

care of CINDA-71

Ros6n a s follows:

ear a t the CC has been the introduction of a new data storage and r e t r i e system t o enable f u l l e r and more rapid use t o be made of t SCISRS f i l e . This computer system, which has been cal led NEUDADA, has been developed t o make the f u l l e s t use of the d i rec t access storage fea tures of the 360/30 computer. A t present it i s available f o r use with the current NNCSC/CCDN data l ib ra ry which incorporates the most recent CCDN compil prepared t o the information content l eve l of SCISRS I1 Dissemination of data on request from this i n January 1969 and an extended r e t r i e v a l on a n y combination of a number of r e t r i eva

en incorporated.

supporting system of programmes ng an edited version of the in te rna l data f i l e

index f o r publication as a CCDN Newsletter. This work involved checking and correcting the reference abbreviation and pr incipal author f o r each entry i n the f i l e , required i n order t o know the precise contents of the data l i b r a ry and t o make possible the subsequent automatic correlat ion of t h i s l ib ra ry with CINDA. I n pa r t i cu la r , Newsletter No. 8 was d is t r ibuted i n April 1969 givj.-ng d e t a i l s of t he l ib ra ry ' s contents on 15th March 1969, and a revised edi t ion of t h i s Newsletter w i l l be published i n No~rember 1969 as Newsletter No. 11 giving d e t a i l s of the contents of the data l i b r a ry on 15th October 1969.

I n addit ion, a modified version of the ECSIL biblio- graphic system ca l led CREED (Compilation of REferences t o Experimental Data) has h e n d%reloped f o r u s e a s a book-keeping - system f o r th? CCDN data compilation ac t iv i ty .

I n conjunction with t h i s system development work, there have been discussions among phys ic is t s (both experimen- t a l i s t s and evaluators) on extending and defining the amount of supporting information which should be compiled f o r each data s e t and a lso on the develop

* Retrievals can be made on any comb parameters defining data se ts : Z , A , react ion, s t a tus , method, standard, laboratory, source, year, reference abbreviation and energy range.

classification scheme. It is intended that agreement on these developments will be reached in the forthcoming four-centre meeting to be held in Moscow on 17th-21st November.

In addition, in order to further the exchange of compiled experimental data between the four data centres, the CCDN is engaged in the development of computer programmes for the translation of data between the NWDADA transmission format and the four-centre exchange format. It is hoped that data exchange on the basis of this exchange format will be initiated towards the end of 1969.

2. CINDA ----- In PIarch 1969 a supplement to CINDA 68 was distributed,

while the.ful1 1969 print-out (CINDA 69) was distributed in July. This print-out included all entries received up to the beginning of Y i 1969.

Most of the past year's work on CINDA at the CCDN has been devoted to finding and filling gaps in the coverage before about 1962 and to bringing the last remaining European entries in the old format up to current standards. This has been in preparation for a second attempt during the coming year to consolidate multiple entries for the same work. Back coverage will be extended further, both by systematically checking main journals and by reference to private card files held by IC. Parker and J. Story.

Although other commitments have prevented any changes to the CINDA programmes, much of the necessary ground work for its automatic checking against the data file has been done. As an interim measure, CINDA 69 contained a list of all references from which data had been stored in the CCDN file at the time of the Centre's Newsletter No. 8.

CCDIT proposals for the reprogramming of CINDA have been submitted to the other participating centres, and it is intended to define the physical and operational parts of a new CINDA system before the end of 1969.

3. Evaluated daea ------------- An information sheet giving details of the evaluated

data files which are available at CCDN for distribution in participating countries was circulated at the end of 1968. Although the distribution list for this document was quite small, several copies were sent to each recipient, who was asked to arrange circulation and distribution within individual Laboratories of participating countries.

The CCDN received the KEDAK library in card image format in Piarch 1969, and distribution has now started.

An updated version of the compilation of evaluations of neutron cross sections was published i n May 1969 a s Newsletter No. 9.

A system of programmes has been developed fo r the storage on disc of the United Kingdom Nuclear Data Libra and fo r subsequent r e t r i eva l from t h i s f i l e by nuclide o process. The system a lso includes options f o r p lo t t ing cross sect ion data and f o r the superposition of evaluated cross sect ion data on p lo t s of the available experim retr ieved from the data l ibrary .

I n reply t o questions Rosen prodded the following addit ional information. Regarding the format used f o r the exchange of data, NEUDADA was being used by CCGN, but the Brookhaven Centre had complained t h a t t h i s was very inconvenient. I n the case of US data, they were received by CCDN i n SCISRS 11 format and t rans la ted i n to NEUDADA. For the evaluated data , the question of the format was s t i l l a serious obstacle fo r

n t posi t ion being t ha t they were exchan

ersonnel, Rosen said t h a t Liskien ( BCMN) would be replacing Schwartz, who was leaving E m . Centre was a t present short of programmers (some work was having t o be contracted out) but t h i s problem would probab be solved i n the near future .

(c) U.S. a c t i v i t i e s . . I . ' . . .

These were reporte . . . . , . . .

NNCSC Computer . .

A Digi ta l Equipment Corporation PDP-10 computer has been i n s t a l l ed i n the National Neutron Cross Section Center. The new computer w i l l improve the accuracy and r e l i a b i l i t y of the NNCSC data f i l e s . The addition of in terac t ive graphics equipment i s planned t o f a c i l i t a t e the evaluation of neutron data.

SCISRS ~- ~ - ~ - - ~-

,~ . . . , ,

. . A l l o l d ' da ta ' a re now' stored on- tape.. uthor proof

system: consisting o f l i s t i n g s and computer: p lo t s sent t o ..the , . :

experimenterhas been i n e f fec t sin'ce January 1969. Therehak . . been excellent cooperation from the. experimenters:, , w i t h . response times averaging two weeks. New,data are being compiled i n the . new Center-tp-Center.Transmission Format. these d a t a w i l l b e ' : sent t o the other Centers and w i l l a lso serve as input t o the SCISRS-IILsystem. A proposal f o r . t h e conbent of the Transmission Fornat' has been. submitted f o r approval a t the forthcoming . :,-

4-Center Meeting, November 47-21, 1969.

ENDF

The second version of the ENDF/B library will be issued during the fall of 1969. The revised files will include new data for D, 0, C, Fe, Ni, Cr, U 235, U 238, Fu 239, PU 240 and Pu 241. The fissile and fertile elements were evaluated simultaneously in order to provide self-consistent data sets by a special Task Force of e erimenters and evaluators. The simultaneous display of ENDF % evaluated data and SCISRS experimental data on 35 mm film was used to assist the re-eva- luation of the ENDF/B library.

In a September 24-26 meeting of the Cross Section Evaluation Working Group, a draft was prepared to revise ENDF/B specifications and a description of its content (BNL 50066).

Joly asked if the U 235 and Eu 239 data included in the ENDF/B we recent Los Alamos evaluations. The answer was negative.

(d) Other activities

Schmidt presented briefly two KFK reports, namely :

- (~)112-U (K?K 880) describing the translation of the internal. format of the KEDAK magnetic tape file into a "card-image" format for external use.

- (E)114-U (KFK 941) giving some requirements for advanced neutron data storage and retrieval systems (physical documentation of the data held in the file, etc. ..)

A general discussion took place about the number of Data requests for the regions covered by the various Data Centres.

The IAEA-NDU had an average of about 100 data requests per year; for BNL, it was about 10 times higher. On the other hand, it seemed that on the average each Centre received about 500 CINDA entries per year, meaning about 500 "neutron data producer^'^ for each area.

The U.S. delegation and the EKFA representative were asked to be prepared to give details at the next M D C meeting of the number of CINDA entries and of Data entries and requests for the last year for the Brookhaven and Saclay Centres.

The Committee was of the opinion t h a t discuss ' of t h e next RENDA should be an important item of t h e meeting. The way t h i s had been dea l t with a t previ meetings ( i . e . discussion of the items sor ted out according t o t h e nature of the data requested), was s t i l l thought t o be the most useful one. But ins tead of asking each reviewer t o do most of the work, it was decided t o t r y t o have t h i s work done l a rge ly by the various Local Data Committees.

I n accordance with these views, t h e following s e r i e s of act ions were agreed : . ,

, , ' . ,. ,' , ,

d 'd i s t r ibute (U--distr ibutio should be given) the new RENDa not l a t e r than April. 1970 .(see .act ion V1.1). , . 'This do.c.umerit . .

would only l i s t the requests according t o ,Z an A e . ; : l i k e pages 1 80 of .WNDC-78 "AL"). , . , .

2. A t t he same time ENEA should prepare a l i s t i n g i n the computer output format of the requests according t o the c lasses given hereunder (c f r . s tep 4). A number of copies w i l l be needed and should be sent t o :

- J. Spaepen (2 copies), f o r Euratom

- E. Rae (2 copies), f o r the U.K.

- G. Ranna (1 copy) f o r Canada

- P. Weinzierl (2 copies), f o r t h i e s

- M. Moore (who w i l l inform EDEA of the number of copies needed) f o r t h e U.S.

3 Each of these persons w i l l ensure t h a t t h e loca l data committee of h i s respect ive area :

-.. comments on current work performed i n i t s area about requests from any area.

- screens ( i . e . eventually de le tes o r changes) the requests f r o m i ts own area.

4. Following t h i s s t ep , the same persons w i l l ensure t h a t a l l these comments a r e sent (not l a t e r than September 1 s t ) t o the following people : - - regarding U requests, t o H. Cond6

- regarding moderators, t o J. Story

- regarding thermal cross-sections, t o G. Hanna

- regarding resonance parameters, non f i s s i l e elements, t o E. Rae

- regarding f i s s i l e elements, resonance parameters and f a s t neutron f i s s i o n , t o R. Joly

- regarding f a s t neutron capture, t o K. Beckurts

- regarding s c a t t e r i n g cross-sections, t o A.B. Smith

- regarding threshold react ions , t o J. Spaepen

5. Those indicated should prepare wr i t ten repor ts on the respect ive items f o r d i s t r i b u t i o n a t the next EANDC neeting.

Following a review of t h e s i t u a t i o n a t t h a t time E N E A w i l l proceed with the prepara.tion of a conprehensive document containing a l l t he r e t r i e v a l s and a list of the requests deleted with respect t o t h e previous RENDA

f EANDC-78 "AL) together with the reason f o r de le t ion implemented, programme changed, e tc . ) .

The following subsidiary act ions were a l so discussed and agreed :

- The ENEA should send 60 copies of the next RENDA t o the IAEA.

- The Chairman should ask the INDC Chairman t o include a discussion of the new BE5TDA i n the agenda f o r the next INDC meeting.

(b) Place, Date, Topical Discussion

According to the pattern followed in the past; the next meeting should take place in the U.S., and the U.S. delegation proposed to hold it at Argonne.

Considering that a meeting of the Nuclear Physics Division of the A.P.S. will be taking place at Houston (Texas) on the 14-16 October, it was decided that the ELNDC meeting should take place on the 26-29 October (with possibility of extending it to the 3Oth), the SuU-Committee meetings taking place on Saturb3y 24th, and the topical discussion being a small 3-day symposium on "Standardsu on the 21-23 October.

APPENDIX 1

LIST OF EANDC DOCUPE'NTS ISSUED SINCE THE

)

(a) Committee Paper EANDC-X

81-A Complete Minutes of the Twelfth Meeting of the Committ.ee

~ e c h n i k a l ' Minutes of the Twelfth Meeting of the Committee ~ : ; . :,

.. .

. . . .

(b) ~ a l a d i a n Document's - , FXNDC(Can)-X , ,

Pr0gres.s Report, January 1969 t o September 969, co'mpiled by G.C. Hanna . .

. . . . . I

Study of t h e Accuracy of g-Pactors f o r Room Temiserature Maxwellian Spectra f o r U and Pu i sotopes , by C,H. Westcot

. . , . 3255: . . . . . . ..

( c ) Euratom Documents - EANDC(E)-X

(E)ll2-U Card Image Format of the .Ear l smhe Eva1uai;ed Nuclear Data F i l e KEDAK, by D. Woll ,, . . . . , . . . . ,

I . ., . , . .. . , . . . . .

(E) 11 3-U Analysis of 'Fast C r i t i c a l , Assemblies and L a r g e Past Power Reactors with Group-Constant

, . . ,

' ' ' ' Sets Eec.ently Evaluated a t Karlsruhe, by

, , , . - . H. KEsters; JIJ. Schmidt, C.H.M. Breeders, E. Eisemanii, M . Metzenroth, K.E. Schroeter, D. Thiem

(E) 11 i c Requirements of Advanced Neutron Data Storage and Retr ieval Systems (CSISXS), by J.J. Schmidt

(E) 11 5-U Progress Report on Nuclear Data Research i n the Euratom Community fo r the period January 1 t o December 31, 1968

(E) 1 1 7-U Aktueller stand der physikalischen kenritnis der wichtigsten reaktor kerndaten, by J . J . Schmidt (KFE-966, EUR-4172 D)

(E)118-U Evaluation of fast critical experiments by use of recent methods and data, by E. Kiefhaber, H. Kuesters, J.J. Schmidt, H. Bachmann, B. Krieg, E. Stein, D. Thiem and K. Wagner (ICFK-969, W R 4173 E)

(E) l l 9-IJ Influence des incertitudes dans les donnges neutroniques sur quelques paramgtres caractgristiques d'un r6acteur 2 neutrons rapides, by J.Y. Barre

(E) 120-L Utilisation d1exp6riences intggrales pour am6liorer le jeu de sections efficaces Cadarache - Jeu version 2 - Application A PhBnix, by J.Y. Barre, J. Ravier

(E) 12 1 -AL Measurement of fission cross section ratios Pu 239: U 235, U 233: U 235, by E. Pfletschinge~ F. Kgppeler

(E) 122-AL Trends in Neutron Total Cross Section Data, by S. Cierjacks

. . .

(E)I 2 3 - ~ ~ Variation of the.' ~inary-to-Ternary ~ission Ratio for U 235 in the Resonance Region, by A. J.:,Deruytter, C.. Wagemans.. :. . .. .. , . .

.. .

(d) . .

(J)q3-L Progress Report (November.l968to.July 1969; inclusive), by T. Momota, F. Fuketa and' K. Okamoto. . ,. , . .

, . . . ..

'Japanese List bf for Measurement (September 1969) . . . ,

valuation of Pu 239, in keV and resolved esonance region. 6 2 ) , by C. Durston nd' S. $at suragi . .

i

(ej Documents for Other OECD Countries - EANDC(0R)-X, ~ ,-.;'

. . , . . ; . (0~)85-L ,' Prbgress ~ e ~ o r t : ~O.'WDC. from Danish AEC

Research ~stablishment Risb , by B. B j errum 1.bller (March. ,1969:) : ., .. , , . , . , . . .: .. , , . , ,, , \. ,

~rogress Report to:. MDC from Spain

Progress Report to EANDC from Greece, by M. Dritsa (Sept. 1969)

(0~)88-L Progress Report to W D C from Norway

(O~)89-L Progress Report t o M D C from Turkey

(oR)~o-L Progress Report t o M D C from Switzerland, by T. Hiirlimann (June 1969)

(0R)ql-L Progress Report t o M D C from Portugal, by F. Gamma Carvalho (August 1969)

(0~)92-L Neutron e l a s t i c sca t t e r ing cross section experimental data and op t i ca l model cross sect ion ca lcu la t ions , by B. Holmqvist and

( f ) U.K. Documents - WDC(UK)-X

(UR)110-P.L U.K. Nuclear Data Progress Report up t o mid- 1968, by E A . Rae

@K) l1 1-AL Gamma-ray spectrometric measurement S of the capture cross sec t ion of gold-198 f o r reactor neutrons, by M.J. Cabell and M. Wilkins

The lowenergy sca t t e r ing cross sect ion of B 10, byA. Asami'and M.C. Moxon (Am-R 5980)

The' neutron capture' cross sect ion of U 238 i n t h e ener range 0.5 t o 100 keV, by M. C. MoxOn , &RE-R, 6074)

.. , . . . .

(UK)ll4-AL Slow' neutron' kcatteking by deuterium, D20 and oxygen, by J .S .S t0ry

@K) 1 15-U Energy released i n f i s s i o n , by M.F. James ( A M - M 863)

(m) 1 l 6-U An evaluation of the neutron cross section da ta f o r zirconium and i t s s tab le isotopes, i n the resolved resonance range, by J.S. Story and A.L. Pope (Am-M 921)

(UK) 11 7-U The thermal neutron absorption cross sections, resonance i n t e g r a l s and resonance parameters of s i l i c o n and i t s s t ab le isotopes, by J.S. Story ( W - M 933)

(g) Documents from t h e United S t a t e s - EANDC(US)-X

(US) 120-U Reports t o the AEC Nuclear Cross Sections Advisory Committee, compiled by M.S. Moore

(US)121-U Proceedings of Conference on Use of Computers i n Experimental Nuc1.ear Physics, Skytop, Penn,, March 1969. (This document w i l l not be avai lable u n t i l l a t e Novenber)

(US) 122-U Reports t o the NCSAC, Houston, Texas

(US) 1 2 3 - ~ R4swn6 of impressions of the Skytop Conferewe Conference on corn-outer systems i n emerimental

A

nuclear physics, ;Skytop," ~ e n n . , 3-6 March 1969

(US ) l 24-A The alpha ha l f - l i f e of U 234, by J . W . Meadows

(US) l 25-A Determination of the Branching Ratio of Be 7, by W.P. Poenitz and A. Devolpi

(US) 126-A The Thermal Absorption Cross Section of L i 6, by J . W , Meadows and J.F. Whalen

(US) 127-A Multi level parameters f o r the Pu 239 Fiss ion Cross Section from 40 t o 100 eV, by P. Lambropoulo S

(US) 128-A Measurement of the Cross Section Ratios of U 235 (n, f ) , U 238 (n, Y and Pu 239 (n, f ) i n the Energy Range 130-1400 keV, by W.P. Poenitz

(US) 129-A Gamma-ray Production Cross Sections f o r Nitrogen and Oxygen, by V.J. Orphan and C . J q Hoot, January 1969 (GA-8006)

High Resolution Measurements of the Total Cross Sections of Nitrogen and Iron, by A.D. Carlson and 8.J. Cerbone, March 1969 (GA-9147)

(US)131-A F i s s i o n Bar r i e r and Trans i t ion .Sta te Spectra f o r Th 232, Th 234, U 238, U 240, ; 242 and Pu 244 from (t , f ) react ions , by

. . J. D., Cramer . .. . , ( ~ ~ 4 1 9 8 7

re l imina ry i io tope inventory, October 1969 , ,

. , ~ . .

. , APPENDIX. 2 . . m

: , . . . . . , . . '

EANDC - .SUB-COMMITTEE ON.. STAi'IDARDS FOR NEUTRON 'MEASUREKENTS

Report o f the' Meeting held a t .~ou~n$mouth (0ctober ... 8 , 1969) '

. . .

, . . . , . . . . .

. .

chklor ; ' Beckurts, ~knna,

. , . . ux standards in the 1 . 1' , , 700 keV region ( ~ a e ) . . .

2,. ~ e u t r o n f lux standards above 100 ' k e i (spaepen). . . ,

3.. Precisethermal . . . . . . , d ,

'4. Compilatibn cif s t a d a r d cross ' . .

5. I I so top ic standard:^ . .

6. f i s ~ i i l a n e q u s .. . . . ~ . . . . . .

. , , , . . , .

' Although during the important new work '' has been accomplished (such as L i and B cross sections. below

100 keV and n-p cross sections a t higher energies) the accuracy needed f o r some requested measurements has n o t g e t ,been reached. Plans f o r improvement of standards and 'of- the methbds

i s found to ' deviate by 5% below the' ?/v l a w i n the energy range 20 - 30 keV, returning t o tkie l / V curve a t a round 100 keV. Thus the statement i n an e a r l i e r report of the Standards Sub- Committee t ha t the cross section follows the l /v law t o ? 5%

. was essent ia l ly corre.ct'r: i s now thought t o be. known t o a n accurac , . the ' accuracy

t 100 keV.

...

4 i - 6 1 ~ 2 , ~ ) The L i 6 absorption cross section has been determined

by Uttley from a theoret ical - f i t t o an accurate t o t a l c r o s s section measurement. Phe structure bf the L i 6 cross section i s extremely simple compared t o t ha t of B 10, which permits an easy in terpre ta t ion o f t h e shape of the cross section below 100 keV i n terms o f a ?/v cbm~onent , a potent ia1,scat ter ing component, the t a i l o f the ,p-wave resonance a t . 250 ,keV, - , a d a very small ItShapiro-' constant" ' i n the reaction cross section. Uttley regards the L i 6 cross section a s forming a muckbetter bas is f o r a st&dard t h a n t h a t of B 10 on account of i t s simple s tructure, and estimates t ha t h i s f i t t i n g procedure gives the shape of the L i 6 cross section t o $ 3% up t o 100 keV, and the value a t thermal energy a s 940 + 3 b. 'Phis l a t t e r value has now been CO Meado,ws and Whalen, who obtain the value 9~34 2 6 b. . .

Using Ut t ley l s determination of the L i 6 cross section, together with the B '10/Li 6 r a t i o measurc2ments of Sowerby and Patrick, gives independent information on the shape of ,the B 10' absorpti'oncross section. This confirms :the departure from l /v i n the 20-39 key region and. agrees. with the. % ~ - 4 ~ ~ . , measurement -within the errors of the measurements.

We note with i n t e r e s t tha t a second accurate' high ' . reso1utio.n measurement. of, the t o t a l cross s ec t ion of L i 6 i s planned a t ANL. AtGeel i t i s lanned t o use detection of the a-particles from B 'l0 (n, . ay and L i 6. (n , . a) t o , perform a d i rec t r a t i o measurement of the two cross sections', possibly using the Harwell booster a s a pulsed neutron source, t o minimise gamma f lash problems. A t Harwell , the, B.-10-vaseline sphere detector has .beenconstructed and r dis t r ibut ion measurements: on t h e $-rays from the B 10

. . , , . . . e

star t ing, ." , . : . ~, . . . .. . .., . . .. , ,... . ..

. . . , . . .. . , . . . . Pissio,n, cross sections ---I-,----------,- -,--

. . , While recognising tha t t h

(n, fj cross section render it ra ther unsuitable f o r use, .as. a standard, the sub-committee f e l t reluctant t o drop the use of a f i s s ion cross section a s a subsidiary standard on account of i t s simplicity i n pract ica l use. Consequently it was f e l t tha t it might be worth considering the sus t i tu t ion of U 233 f@ U235 i n t h i s role. This cross section should be re la t ively f ree from intermediate s tructure because both of i t s spin s t a t e s have fu l ly open f i s s ion channels. If U 233 i s t o be used as a standard, however, i t s cross section w i l l have t o be careful ly studied.

. . , . . . . Poeni t i GreZ ------- Detect . . , . Two new measurements have been made a t ANL and Chalk

River o f the Be 7 branching r a t i o following the L i 7 (p, n) reaction. These are confirmed by the preliminary measurements from Gee1 thus removing the source of uncertainty ill the cal ibrat ion of the Grey Detector. This has now been calibrated

over the energy range from 30 keV points agree with the theoret ical (Nucl.. Ins t r . Meth.. E, : 120,

.... . , . , , , . <

2. Blux above.100 keV .(Spakh .. . . . . . . - 2 . .i.,, . .

&W,'; mka,sur&m&~titsi p.&n;:pe$f d&ed, ;by'. '~angsfp~d and f t h & . h'eutrbn-~r~dton ,,,. . . 'tcital',:ciygB "section 'in- t K e ' energy

r.ang$ betwe,&= .0,. 8 t b 5-.8,.-Mef,7, -with:- ,a -qyi~r&cy: between' about 0 ; 3 an&.^ *5%. . .rphe result&' :bear. out' "thog@ bf :, agelkk et:; .::

a t Columbia i n lying 0 .-7o%'.Mgher: %b.&. tue: earl ier- data. The new values are given i n t

... wdrk: is:, un@&bi:way oi-:~ an ' al.+epn&ive: detecto . . . . . . . . . it Ts hbp;ed'. , . e measurements:: t o be . . . . . . . . 'made down.

.~ . ~ ~ . , . c. ,;; . : .-, .. : eV.

, ' ' : . , . , , , . , . . . . , . . . . . . . . . , . '

-autho-& have submitted: a . l e t t e r t b .ph Letters concerriing t h e repor ted oscillatibn's : in- : th 1 cross, section,: sliowing:that ,if .such.oscillationS:'are..p >

' t h e i r magnitude must be - less . than 6 , mb ..c,: Results:. 'Liskien azid:Paul.+ f i rr ther-at NBS, d id

,. ,

n, n ) . angular distributions between 0.75 and 2 MeV, obtained by comparison. with H (n, n). Data are being:. completed,.down. ~ . .

to 9 0 keV.

. , . . ANL ,(Meadows .and Whalen) has obtained the SS ection of. carbon between 0.1 and 1.5 MeV with, an accuracy o f . ~ t t 1 e y : : a t Harwell .has ,measured the .same cross section

between 100 ,eVY.and 30 MeV.., Rae w i l l ask Uttley to draft t h e results: of , this work i n a ..!Cinal form. . .

. . ~ . . . . . . . , , . . ,. .

The new measurements obtained by Poenitz (ANL) and Pfletschin e r e t al. (Xarlsruhe) were discussed by the f u l l Committee f see item 2 (e)) ,

6 (n, a ) by Meadows 8 2 4- b by a neutron r 934 2 6 b i f ,the cluded) ; previously

by about 2 i3%. Meadows.' result i s in.. ex.cellent agreement with the value of 9w.3,>+ 3.2 b obtained . from , linac measurements a t AERE (EANDC

. . ., .~ 87 page: 35). , . . . . , - . . ,. . . . . , . . , .,

In a s i m i l eriment ~eadoiw bbtained a 'value of 3855'?:26 b for the a1 B 10 (n, a). cross section, 'which agrees with the more precise Geel evaluation 3834 5 5 b , . ,

(l& error). Hanna presented the resul ts of the revised L$EA. least squares f i t of '2200 m / s data for . U ' 233, U 235, Pu. 239 a ~ ~ d Pu 241. They agree, with the ear l ie r . (1965) f i t within t hee r ro r s of that set. For Pu 241, new experimental.' measure'rhents have led t o - . a significant iinprovement inpthe accuracy, but for the o$her three nuclei the errors of most of

"the' output values have not improve& much,,because. the , effect of some new accurate measurements has been offset by increases &;the wcertaintie,s assigned. t o a-decay, half l i ~ e s and to the

, , g ;factor of .h,- 239. . The rsethods, of ch&cal.' analysis . fo r ..

U r a n i u m i n use a t Geel (CPC, isotopic dilution, weyghing of vacuum evaporated- sources.); on the ., accuracy, of which the U 2% half l i f e depends ::(as .on the other. hand i on low, ,geometry.,.a+d

., l iquid -scintillation:sounting), : are {being checked; by. ,..::.. :, international comparison. These. samples; standardized by: alpha countingare being sent t oo the r laborato~ies.forUra~~.mass determination, Work .has. already s t a r t ed , a t . Chalk River,, , and Idaho Falls w i l l receive samples shortly.

The spread of 5 (Cf) values i s even wider than i n 1965: they range from j:&$!l ;i: 0.057 (Asplund - Nilsson e t a l e 1963) t o 3.700 + 0.020 (Axton e t a l . 1969). The necessarily a rb i t ra ry treatment-of t h i s very discordant s e t of data gives a weighted-mean input value of U (Cf) of 5.743 2 0.016 and the output value 3.765 2 0 . 0 1 6 ~ ~ ? ~ the t ab le of recommended values a11 er rors a re increased by 12.533 and t h i s e r ror becomes 2 0*012). Omitting a l l absolute v' measurements from the input data ( i i e . relying en t i re ly on measurements f o r absolute neutron emission probabi l i t ies ) leads t o 5 t o t a l (Cf) = 3.784 2 0.014.

The IAU least-squares f i t (LSF) assumed a value of 2.488 X 1 0 5 ~ f o r the U 234 ha l f - l i f e , but recent measurements a t Geel reported by Spaepen, and a t ANL by Ncadows (vDC(Us)-124) strongly indicate a value of 2.44 X 1 0 5 ~ . Malrlng t h i s change would increase Deruytter 's 1968 measurement of of (235) by (i.e. t o 589 + 5 b) , and the LSF output value by about 1 b (from 580.2 + 1.8 b). A similar 2% decrease i n the U 233 hal f - l i fe would fur ther increase the LSF value by about 1 b. Hanna pointed out t h a t a value of of (235) a s high a s 589 b would be very d i f f i c u l t t o reconcile with the apparently well established (transmission) measurements of o to t a l 12353 or (because of the accurate of r a t i o data) with Otot 233 . On the other hand the very preliminary Gee1 resu@ f o r of (239) i s not i n disagreement with the LSF value.

4. Compilation of standard cross sections (~paepen)

The sub-committee has taken note of the compilation of the t o t a l cross sect ion of carbon by a Japanese Group and the members w i l l report t o the Chairman a f t e r they have had the opportunity of studying the compilation i n de ta i l .

5. Isotopic standards (Spaepen)

. The NBS i s preparing a s e r i e s of depleted isotopic 'standards of uranium.

The sub-committee would l i k e t o see a symposium organised, devoted t o the assessment of what has been accomplished i n recent years and t o help t o define the needs f o r the future. Such a symposium would have to be held jus t before an WDC-meeting. The attendance should be of the order of 30 people. It would probably r e f e r t o 6 t h e 1 - 1000 keV-region.