Measurements at n_TOF of the neutron capture cross section of minor actinides relevant to the nuclear waste transmutation

Measu emen s a n_TOF o he Neu on Cap u e C oss Sec ion o Mino Ac inides Rele an o he Nuclea Was e T ansmu a ion Ci e as: AIP Con e ence P oceedings 769, 1442 (2005); h ps://doi.o g/10.1063/1.1945275 Published Online: 13 June 2005 D. Cano-O , U. Abbondanno, G. Ae s, H. Ál a ez, F. Àl a ez-Vela de, S. And iamonje, J. And zejewski, P. Assimakopoulos, L. Audouin, G. Badu ek, P. Baumann, F. Beč ář, J. Benlliu e, E. Be houmieux, F. Cal iño, R. Capo e, A. Ca illo de Albo noz, P. Cennini, V. Chepel, E. Chia e i, N. Colonna, G. Co es, D. Co ina, A. Cou u e, J. Cox, S. Da id, R. Dol ini, C. Domingo-Pa do, W. D idi, I. Du an, M. Embid-Segu a, L. Fe an , A. Fe a i, L. Fi zpa ick, R. Fe ei a-Ma ques, H. F ais-Koelbl, K. Fujii, W. Fu man, I. Goncal es, R. Gallino, E. Gonzalez-Rome o, A. Go e do ski, F. G amegna, E. G iesmaye , C. Gue e o, F. Gunsing, B. Haas, R. Haigh , M. Heil, A. He e a-Ma inez, M. Igashi a, S. Isae , E. Je icha, Y. Kadi, F. Käppele , D. Ka amanis, D. Ka adimos, M. Ke eno, V. Ke le o , P. Koehle , V. Kono alo , E. Kossionides, M. K ička, C. Lamboudis, H. Leeb, A. Lindo e, I. Lopes, M. Lozano, S. Lukic, J. Ma ganiec, L. Ma ques, S. Ma one, P. Mas inu, A. Mengoni, P. M. Milazzo, C. Mo eau, M. Mosconi, F. Ne es, H. Obe humme , S. O’B ien, M. Oshima, J. Pancin, C. Papach is odoulou, C. Papadopoulos, T. Papae angelou, C. Pa adela, N. Pa onis, A. Pa lik, P. Pa lopoulos, G. Pe dikakis, L. Pe o , R. Plag, A. Plompen, A. Plukis, A. Poch, C. P e el, J. Quesada, T. Rausche , R. Rei a h, M. Rose i, C. Rubbia, G. Rudol , P. Rullhusen, J. Salgado, L. Sa chiapone, C. S ephan, G. Taglien e, J. L. Tain, L. Tassan-Go , L. Ta o a, R. Te lizzi, G. Vannini, P. Vaz, A. Ven u a, D. Villama in, M. C. Vincen e, V. Vlachoudis, R. Vlas ou, F. Voss, H. Wendle , M. Wiesche , K. Wisshak, and The n_TOF Collabo a ion ARTICLES YOU MAY BE INTERESTED IN Measu emen o he 232Th Neu on Cap u e C oss Sec ion a he CERN n_TOF Facili y AIP Con e ence P oceedings 769, 1470 (2005); h ps://doi.o g/10.1063/1.1945282 New Measu emen o he Cap u e C oss Sec ion o Bismu h and Lead Iso opes AIP Con e ence P oceedings 769, 1521 (2005); h ps://doi.o g/10.1063/1.1945294 The n_TOF Facili y a CERN: Pe o mances and Fi s Physics Resul s AIP Con e ence P oceedings 769, 724 (2005); h ps://doi.o g/10.1063/1.1945110 AIP Con e ence P oceedings 769, 1442 (2005); h ps://doi.o g/10.1063/1.1945275 769, 1442 © 2005 Ame ican Ins i u e o Physics. Measu emen s a n_TOF o he Neu on Cap u e C oss Sec ion o Mino Ac inides Rele an o he Nuclea Was e T ansmu a ion D. Cano-O 20 1 , U. Abbondanno14,G.Ae s 7,H.Ál a ez 24, F. Àl a ez-Vela de20, S. And iamonje7, J. And zejewski33, P. Assimakopoulos9, L. Audouin 5G. Badu ek1,P.Baumann 6,F.Beˇc ᡠ31, J. Benlliu e24, E. Be houmieux7, F. Cal iño25, R. Capo e23, A. Ca illo de Albo noz30, P. Cennini4, V. Chepel17,E.Chia e i 4, N. Colonna13,G.Co es 25,D.Co ina 24, A. Cou u e29,J.Cox 29,S.Da id 5,R.Dol ini 15, C. Domingo-Pa do21, W. D idi7,I.Du an 24, M. Embid-Segu a20,L.Fe an 5, A. Fe a i4, L. Fi zpa ick4,R.Fe ei a-Ma ques 17, H. F ais-Koelbl3,K.Fujii 13,W.Fu man 18, I. Goncal es30, R. Gallino36, E. Gonzalez-Rome o20, A. Go e do ski19, F. G amegna12,E.G iesmaye 3, C. Gue e o20, F. Gunsing7, B. Haas32, R. Haigh 27,M.Heil 8, A. He e a-Ma inez4, M. Igashi a37,S.Isae 5,E.Je icha 1,Y.Kadi 4, F. Käppele 8, D. Ka amanis9, D. Ka adimos9, M. Ke eno,6, V. Ke le o 19, P. Koehle 28, V. Kono alo 18, E. Kossionides39,M.K iˇcka31, C. Lamboudis10, H. Leeb1, A. Lindo e17, I. Lopes17,M.Lozano 23, S. Lukic6, J. Ma ganiec33, L. Ma ques30, S. Ma one13,P.Mas inu 12, A. Mengoni4, P.M. Milazzo14, C. Mo eau14, M. Mosconi8,F.Ne es 17,H.Obe humme 1, S. O’B ien29, M. Oshima38,J.Pancin 7, C. Papach is odoulou9, C. Papadopoulos40, T. Papae angelou4, C. Pa adela24, N. Pa onis9, A. Pa lik2, P. Pa lopoulos34, G. Pe dikakis40,L.Pe o 7,R.Plag 8,A.Plompen 16, A. Plukis7,A.Poch 25,C.P e el 25, J. Quesada23,T.Rausche 26, R. Rei a h27,M.Rose i 11, C. Rubbia15, G. Rudol 6,P.Rullhusen 16, J. Salgado30, L. Sa chiapone4, C. S ephan5, G. Taglien e13,J.L.Tain 21, L. Tassan-Go 5,L.Ta o a 30, R. Te lizzi13, G. Vannini35, P. Vaz30,A.Ven u a 11, D. Villama in20,M.C.Vincen e 20, V. Vlachoudis4,R.Vlas ou 40 F. Voss8, H. Wendle 4, M. Wiesche 29,K.Wisshak 8 The n_TOF Collabo a ion 1A omins i u de Ös e eichischen Uni e si ä en,Technische Uni e si ä Wien, Aus ia  2Ins i u ü Iso open o schung und Ke nphysik, Uni e si ä Wien, Aus ia  3Fachhochschule Wiene Neus ad , Wiene Neus ad , Aus ia  4CERN, Gene a, Swi ze land  5Cen e Na ional de la Reche che Scien i ique/IN2P3 - IPN, O say, F ance  6Cen e Na ional de la Reche che Scien i ique/IN2P3 - IReS, S asbou g, F ance  7CEA/Saclay - DSM, Gi -su -Y e e, F ance  8Fo schungszen um Ka ls uhe GmbH (FZK), Ins i u ü Ke nphysik, Ge many  9Uni e si y o Ioannina, G eece  10A is o le Uni e si y o Thessaloniki, G eece  11ENEA, Bologna, I aly  12Labo a o i Nazionali di Legna o, I aly  13Is i u o Nazionale di Fisica Nuclea e, Ba i, I aly  14Is i u o Nazionale di Fisica Nuclea e, T ies e, I aly  15Uni e si à degli S udi Pa ia, Pa ia, I aly  16CEC-JRC-IRMM, Geel, Belgium  17LIP - Coimb a & Depa amen o de Fisica da Uni e sidade de Coimb a, Po ugal  18Join Ins i u e o Nuclea Resea ch, F ank Labo a o y o Neu on Physics, Dubna, Russia  19Ins i u e o Physics and Powe Enginee ing, Kaluga egion, Obninsk, Russia  20Cen o de In es igaciones Ene ge icas Medioambien ales y Technològicas, Mad id, Spain  21Consejo Supe io de In es igaciones Cien i icas - Uni e si y o Valencia, Spain  22Uni e sidad Poli ecnica de Mad id, Spain  23Uni e sidad de Se illa, Spain  24Uni e sidade de San iago de Compos ela, Spain  25Uni e si a Poli ecnica de Ca alunya, Ba celona, Spain  26Depa men o Physics and As onomy - Uni e si y o Basel, Basel, Swi ze land  27Los Alamos Na ional Labo a o y, New Mexico, USA  28Oak Ridge Na ional Labo a o y, Physics Di ision, Oak Ridge, USA  29Uni e si y o No e Dame, No e Dame, USA  30Ins i u o Tecnológico e Nuclea , Lisbon, Po ugal  31Cha les Uni e si y, P ague, Czech Republic  32Cen e Na ional de la Reche che Scien i ique/IN2P3 - CENBG, Bo deaux, F ance  33Uni e si y o Lodz, Lodz, Poland  34Pôle Uni e si ai e Léona d de Vinci, Pa is La Dé ense, F ance  35Dipa imen o di Fisica, Uni e si à di Bologna, and Sezione INFN di Bologna, I aly  36Dipa imen o di Fisica Gene ale, Uni e si à di To ino and Sezione INFN di To ino, I-10125 To ino, I aly  37Tokyo Ins i u e o Technology, Tokyo, Japan  38Japan A omic Ene gy Resea ch Ins i u e, Tokai-mu a, Japan  39NCSR, A hens, G eece  40Na ional Technical Uni e si y o A hens, G eece Abs ac . Accu a e and eliable neu on-cap u e c oss-sec ion da a o ac inides a e necessa y o he p ope design, sa e y egula ion, and p ecise pe o mance assessmen o ansmu a ion de ices such as Fas C i ical Reac o s o Accele a o D i en Sys ems. In pa icula , he neu on-cap u e c oss sec ions o 237Np, 240Pu, and 243Am play a key ole in he design and op imiza ion o a s a egy o he Nuclea Was e T ansmu a ion. The lis ed c oss sec ions ha e been measu ed in 2004 a n_TOF wi h a high accu acy due o a combina ion o ea u es unique in he wo ld: high ins an aneous neu on luence and excellen ene gy esolu ion o he n_TOF acili y, inno a i e Da a Acquisi ion Sys em based on lash ADCs, and he use o a high-pe o mance BaF2To al Abso p ion Calo ime e as a de ec ion de ice. 1442 CP769, In e na ional Con e ence on Nuclea Da a o Science and Technology, edi ed by R. C. Haigh , M. B. Chadwick, T. Kawano, and P. Talou © 2005 Ame ican Ins i u e o Physics 0-7354-0254-X/05/$22.50 INTRODUCTION Nuclea was e is one he main issues o he public pe - cep ion o nuclea -ene gy p oduc ion and o he sus ain- abili y o his ene gy sou ce. Nuclea was e ansmu a- ion has been p oposed as a way o educe subs an ially (by a ac o o 1/100 o mo e) he adio oxici y in en o y o he long-li edcomponen o he nuclea was e, mainly he ans-u anium ac inides. Ac inide ansmu a ion is p oposed o ake place by ission in nuclea sys ems like c i ical eac o s o sub- c i ical Accele a o D i en Sys ems (ADS). In mos o he scena ios, he use o as -neu on ene gy spec a and speci ic uel composi ions, highly en iched in high-mass ans-u anium ac inides, is p oposed. 2000 40000 8000 100006000 0 50 100 150 200 250 Pulse shape econs uc ions o he BaF2 signals Digi ised BaF2 signals ime (ns) signal ampli ude ( lash ADC coun s) FIGURE 1. Digi ised BaF2signals and he co esponding econs uc ion a e he pulse-shape analysis. The de ailed enginee ing designs, sa e y e alua ions, and he de ailed pe o mance assessmen o dedica ed ansmu a ion ADS and c i ical eac o s (i.e., wi h uels highly en iched in ansu anic iso opes) equi e mo e p ecise and comple e basic nuclea da a [1]. O c ucial impo ance is he composi ion o he uels p oposed o ansmu a ion de ices, wi h a la ge concen- a ion o mino ac inides and high-mass plu onium iso- opes. These iso opes wi h smalle ele ance o he op- e a ion o p esen eac o s will play an impo an ole in he neu onics o he ansmu e s and o i s ansmu a- ion pe o mance. 1co espondingau ho :daniel.cano@ciema .es EXPERIMENT Iso opically en iched a ge s o mino ac inides a e a ail- able only in small amoun s, ypically o he o de o 1- 100 mg. E en o hese small amoun s, he ac i i y o he samples ep esen s majo di icul ies ela ed bo h o he expe imen al echniques and he adiop o ec ion aspec s. FIGURE 2. View o he To al Abso p ion Calo ime e as i is implemen ed in he code GEANT4 [8] used o he MC simula ions. The a ge s o 237Np (43.3 mg, 1.29 MBq), 240Pu (51.2 mg, 458 MBq), and 243Am (10 mg, 75 MBq) mea- su ed a n_TOF ha e been all assembled in hesame way: he adioac i e ma e ial is sandwiched by wo hin Al laye s ( o al mass < 75 mg) and canned inside a 0.35- mm- hick Ti canning wi h ISO 2919 ce i ica ion ( e- ques ed by he sa e y egula ions a CERN). Thei iso- opic pu i y has been de e mined by γ - ay spec ome y and is >98% in all cases. In cap u e measu emen s a n_TOF [2] wi h a 4-cm- diame e neu on beam spo , he ins an aneous luence amoun s o 105neu ons/cm2/pulse o neu on ene gies be ween 0.1 eV and 20 GeV. This is one o he key ea u es o measu ing he (n, γ ) c oss sec ion o low- mass and highly adioac i e iso opes wi h a good signal- o-noise a io. Du ing he measu emen s, he epe i ion a e o he PS was on a e age 3-4 p o on pulses o a PS supe cycle o 16.4 s. In addi ion, he n_TOF acili y p o ides an excellen ene gy esolu ion o 10  3 o 10  4 a a 185-m ligh pa h be ween he Pb spalla ion a ge and he coun ing s a ion. The cap u e c oss-sec ion measu emen s a n_TOF ha e been done ela i e o he s anda d cap u e c oss 1443 sec ion 197Au(n, γ ). Fo his eason, se e al independen moni o s we e used pe manen ly o a p ope no maliza- ion be ween he 197Au(n, γ ) and main measu emen s. (eV) n E 2 10 3 10 -5 10 -4 10 -3 10 coun s (no malised o he lux moni o a e) RAW DATA om he 237Np(n,γ) measu emen a n_TOF 2.) Backg ound due o he Ti canning + 1.) 1.) Room + a ge ame backg ound 3.) 43.3 mg o 237Np + 2.) 3000 bins/decade FIGURE 3. Raw da a om he 237Np (n, γ ) measu emen in he esol ed esonance egion be ween 10 eV and 1 keV. Below, he backg ound due o he Ti canning and he emp y TAC (wi hou any sample in he beam). (eV) n E 2 10 3 10 -5 10 -4 10 -3 10 coun s (no malised o he lux moni o a e) RAW DATA om he 240Pu(n,γ) measu emen a n_TOF 2. ) Backg ound due o he Ti canning + 1.) 1.) Room + a ge ame backg ound 3.) 51.2 mg o 240Pu + 2.) 3000 bins/decade FIGURE 4. Raw da a om he 240Pu (n, γ ) measu emen in he esol ed esonance egion be ween10 eV and1 keV. Below, he backg ound due o he Ti canning and he emp y TAC (wi hou any sample in he beam). The Da a Acquisi ion sys em (DAQ) [3] used in he measu emen s consis s o 54 channels o high- pe o mance lash ADCs [4]. Each channel has 8 Mby es o memo y and was ope a ed a a sampling a e o 500 M samples/s, hus allowing eco ding o he ull de ec o his o y o neu on ene gy anges be ween 0.3 eV and 20 GeV. A e ze o supp ession and da a o ma ing, he aw da a a e sen o CERN’s massi e s o age acili y CASTOR [5] ia se e al Gigabi links. In pa allel, es- pecially designed pulse-shape analysis ou ines un on a PC a m and ex ac om he digi ized de ec o signals he necessa y in o ma ion o he da a analysis. The n_TOF DAQ o e s unique ea u es such as an ex- emely low dead ime (< 10 ns), good signal analysis, and pileup disc imina ion among o he s, esul ing in an excellen mechanism o con ollingall kinds o sys em- a ic unce ain ies associa ed wi h he de ec o ’s beha - io . The quali y o he econs uc ion o digi ised BaF2 signals ( wo scin illa ion componen s τ sho =0.7 ns and τ long=620 ns) is shown in Fig. 1. The neu on cap u e de ec ion sys em consis s o a segmen ed To al Abso p ion Calo ime e made o 40 BaF2c ys als wi h 10B loaded ca bon ib e capsules and placed a a 185-m ligh pa h om he spalla ion sou ce. The TAC has a nea ly 100% de ec ion e iciency o elec- omagne ic cascades (i.e., cap u e e en s) and good en- e gy esolu ion (14% a 662 keV and 6% a 6.1 MeV). The adioac i e a ge s a e placed a he geome ic cen e o he TAC and su ounded by a C12H2004(6Li)2neu on abso be placed inside he inne hole o he TAC. The neu on abso be and he 10B loaded ca bon ib e cap- sules educe he sensi i i yo he de ec o o he sca e ed neu ons, do no educe he cap u e de ec ion e iciency (e en hough hey lowe he o al abso p ion e iciency), and also help in a enua ing he low-ene gy componen (10-100 keV) o he sample adioac i i y. Fo he mea- su emen o 243Am, a cylind ical Pb shielding o 1 mm hickness a ound he a ge and ou side he beam was necessa y o supp essing he s ong γ -ac i i y wi h en- e gies abou 100-200 keV. Figu e 2 shows a iew o he expe imen al se up as i is implemen ed in he code GEANT4 [8] used o he de- ailed MC simula ions o he TAC. The pe o mance o he TAC has been in es iga ed bo h expe imen ally (wi h s anda d calib a ion sou ces and he e e ence 197Au(n, γ ) c oss sec ion) and by Mon e Ca lo simula ions [6, 7]. Fu he mo e, all sou ces o backg ound ha e been mea- su ed and a e being simula ed o pe o ming he back- g ound co ec ions necessa y o an accu a e cap u e c oss-sec ion analysis. RESULTS The cap u e da a o 237Np, 240Pu we e aken du ing Au- gus and Sep embe 2004, and he 243Am measu emen is expec ed o inish in Oc obe 2004. Fo his eason, he da a analysis is a a e y ea ly s age. Howe e , a simple analysis o he aw da a wi h ull s a is ics indi- ca es p omising esul s. In he esol ed esonance egion, a la ge numbe o esonances a e obse ed wi h good s a is ics in bo h he aw da a o 237Np and 240Pu shown in Fig. 3 and 4, espec i ely. Fu he mo e, he le el o he backg ound he e is ai ly low, hus allowing us o con- clude al eady ha he ex ac ion o accu a e esonance pa ame e s is possible. As is shown in Fig. 5 and 6, he c oss-sec ion analysis in he un esol ed esonance egion will equi e a mo e de ailed s udy and sub ac ion o he backg ound, domina ed mainly by he e ec o he Ti 1444 canning o he samples. Howe e , clea cap u e signals a e isible in he TAC ene gy-deposi ion spec a. The backg ound due o he emp y Ti canning and o he mino sou ces has been measu ed wi h high s a is ics and will be sub ac ed om he main measu emen , hus leading o an accu a e alue o he cap u e c oss sec ion up o 100 keV. (eV) n 1 10 2 10 3 10 4 10 5 10 E coun s (no malised o he lux moni o a e) -4 10 -3 10 -2 10 RAW DATA om he 237Np(n,γ) measu emen a n_TOF 200 bins/decade 2.) Backg ound due o he Ti canning + 1.) 1.) Room + a ge ame backg ound 3.) 43.3 mg o 237Np + 2.) FIGURE 5. Raw da a om he 237Np (n, γ ) measu emen in he ene gy ange be ween 0.7 eV and 300 keV. Below, he backg ound due o he Ti canning and he emp y TAC (wi hou any sample in he beam). (eV) n E 1 10 2 10 3 10 4 10 5 10 -4 10 -3 10 -2 10 -1 10 RAW DATA om he 240Pu(n,γ) measu emen a n_TOF coun s (no malised o he lux moni o a e) 2. ) Backg ound due o he Ti canning + 1.) 1.) Room + a ge ame backg ound 3.) 51.2 mg o 240Pu + 2.) 200 bins/decade FIGURE 6. Raw da a om he 240Pu (n, γ ) measu emen in he ene gy ange be ween 0.7 eV and 300 keV. Below, he backg ound due o he Ti canning and he emp y TAC (wi hou any sample in he beam). CONCLUSIONS The neu on cap u e c oss-sec ion measu emen s o 237Np, 240Pu, and 243Am ha e been pe o med a he n_TOF acili y a CERN. A high-pe o mance To al Ab- so p ion Calo ime e made o 40 BaF2c ys als was used o his pu pose. The aw da a o 237Np and 240Pu a e ex emely p omising in he esol ed esonance egion, whe e a la ge numbe o esonances has been obse ed wi h good s a is ics o bo h iso opes. Fu he mo e, he cap u e e en s can be clea ly dis inguished om he backg ound a neu on ene gies up o 100 keV, hus al- lowing he conclusion ha i will be possible o ex ac he cap u e c oss sec ion up o 100 keV a e a ca e ul backg ound sub ac ion. Las , 237Np and 240Pu a e he i s wo cap u e c oss- sec ion measu emen s on highly adioac i e and low- mass ac inides wi h he To al Abso p ion Calo ime e a n_TOF . They a e a clea expe imen al alida ion o he good pe o mance o he n_TOF acili y, da a acquisi ion sys em, and TAC and allow design o e en mo e ambi ious expe imen s o he nea u u e. ACKNOWLEDGMENTS This wo k is pa o he Eu opean Commission 5 h F amewo k P og amme p ojec NTOF-ND-ADS unde con ac FIKW-CT-2000-00107. REFERENCES 1. Accele a o D i en Sys ems and Fas Reac o s in Ad anced Nuclea Fuel Cycles, ISBN 92-64-18482-1 ENEA/OECD Repo , 2002 2. U. Abbondanoe al., "n_TOF Pe o mance Repo ,” CERN/INTC- O-011, INTC-2002-037 3. R. Plag e al., submi ed o Nucl. Ins um. Me hods A (2004). 4. h p://www.acqi is.com 5. h p://cas o .web.ce n.ch/cas o 6. M. Heil e al. Nucl. Ins um. Me hods A 459(2001) 229 7. D. Cano-O e al., "Mon e Ca lo Simula ion o he 4 π To al Abso p ion Calo ime e a n_TOF,” n_TOF in e nal epo (2003) 8. S.Agos inelli e al.,Nucl. Ins um. Me hods A, 506, (2003), p. 250-303. 1445