Measurement of the 244Cm and 246Cm neutron-induced capture cross sections at the n_TOF facility

Measu emen o he 244Cm and 246Cm neu on-induced cap- u e c oss sec ions a he n_TOF acili y V. Alcayne1, A. Kimu a2, E. Mendoza1, D. Cano-O 1, T. Ma ínez1, O. Abe le3, J. And zejewski4, L. Audouin5, V. Béca es1, M. Bacak3,6,7, M. Ba bagallo3,8, F. Beˇ c ᡠ9, G. Bellia10,11, E. Be houmieux7, J. Billowes12, D. Bosna 13, A. B own14, M. Busso8,15,16, M. Caamaño17, L. Caballe o-On anaya18, F. Cal iño19, M. Cal iani3, A. Casano as19, F. Ce u i3, Y. H. Chen5, E. Chia e i3,12,20, N. Colonna8, G. Co és19, M. A. Co és-Gi aldo20, L. Cosen ino10, S. C is allo8,15,21, L. A. Damone8,22, M. Diakaki23,3, M. Die z24, C. Domingo- Pa do18, R. D essle 25, E. Dupon 7, I. Du án17, Z. Eleme26, B. Fe nández-Domínguez17, A. Fe a i3, P. Finocchia o10, V. Fu man27, K. Göbel28, A. Gawlik4, S. Gila doni3, T. Gloda iu29, I. F. Gonçal es30, E. González-Rome o1, C. Gue e o20, F. Gunsing7, H. Ha ada2, S. Heini z25, J. Heyse31, D. G. Jenkins14, F. Käppele 32, Y. Kadi3, T. Ka abuchi33, N. Ki el25, I. Knapo a9, M. Kokko is23, Y. Kopa ch27, M. K iˇ cka9, D. Ku ulgil28, I. Lada escu18, C. Lede e -Woods24, J. Le endegui-Ma co20, S. Lo Meo34,35, S. J. Lonsdale24, D. Macina3, A. Manna35,36, A. Masi3, C. Massimi35,36, P. Mas inu37, M. Mas oma co3, F. Ma eucci38,39, E. A. Mauge i25, A. Mazzone8,40, A. Mengoni34, V. Michalopoulou23, P. M. Milazzo38, F. Ming one3, A. Musuma a10,11, A. Neg e 29, R. Nol e41, F. Ogálla 42, A. Op ea29, N. Pa onis26, A. Pa lik43, J. Pe kowski4, L. Pe san i8,15,21, I. Po as42, J. P aena42, J. M. Quesada20, D. Radeck41, D. Ramos-Do al5, T. Rausche 44,45, R. Rei a h28, D. Rochman25, M. Saba é-Gila e3,20, A. Saxena46, P. Schillebeeckx31, D. Schumann25, S. Simone10, A. G. Smi h12, N. V. Sosnin12, A. S ama opoulos23, G. Taglien e8, J. L. Tain18, T. Talip25, A. Ta i eño-Saldi ia19, L. Tassan-Go 3,23,5, A. Tsinganis3, J. Ul ich25, S. U lass3,47, S. Valen a9, G. Vannini35,36, V. Va iale8, P. Vaz30, A. Ven u a35, D. Vesco i8,15, V. Vlachoudis3, R. Vlas ou23, A. Wallne 48, P. J. Woods24, T. W igh 12, and P. Žugec13 1Cen o de In es igaciones Ene gé icas Medioambien ales y Tecnológicas (CIEMAT), Spain 2Japan A omic Ene gy Agency (JAEA), Tokai-mu a, Japan 3Eu opean O ganiza ion o Nuclea Resea ch (CERN), Swi ze land 4Uni e si y o Lodz, Poland 5Ins i u de Physique Nucléai e, CNRS-IN2P3, Uni . Pa is-Sud, Uni e si é Pa is-Saclay, F-91406 O - say Cedex, F ance 6Technische Uni e si ä Wien, Aus ia 7CEA I u, Uni e si é Pa is-Saclay, F-91191 Gi -su -Y e e, F ance 8Is i u o Nazionale di Fisica Nuclea e, Sezione di Ba i, I aly 9Cha les Uni e si y, P ague, Czech Republic 10INFN Labo a o i Nazionali del Sud, Ca ania, I aly 11Dipa imen o di Fisica e As onomia, Uni e si à di Ca ania, I aly 12Uni e si y o Manches e , Uni ed Kingdom 13Depa men o Physics, Facul y o Science, Uni e si y o Zag eb, Zag eb, C oa ia 14Uni e si y o Yo k, Uni ed Kingdom 15Is i u o Nazionale di Fisica Nuclea e, Sezione di Pe ugia, I aly 16Dipa imen o di Fisica e Geologia, Uni e si à di Pe ugia, I aly 17Uni e si y o San iago de Compos ela, Spain 18Ins i u o de Física Co puscula , CSIC - Uni e sidad de Valencia, Spain ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 © The Au ho s, published by EDP Sciences. This is an open access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License 4.0 (h p://c ea i ecommons.o g/licenses/by/4.0/). 19Uni e si a Poli ècnica de Ca alunya, Spain 20Uni e sidad de Se illa, Spain 21Is i u o Nazionale di As o isica - Osse a o io As onomico di Te amo, I aly 22Dipa imen o di Fisica, Uni e si à degli S udi di Ba i, I aly 23Na ional Technical Uni e si y o A hens, G eece 24School o Physics and As onomy, Uni e si y o Edinbu gh, Uni ed Kingdom 25Paul Sche e Ins i u (PSI), Villingen, Swi ze land 26Uni e si y o Ioannina, G eece 27Join Ins i u e o Nuclea Resea ch (JINR), Dubna, Russia 28Goe he Uni e si y F ank u , Ge many 29Ho ia Hulubei Na ional Ins i u e o Physics and Nuclea Enginee ing, Romania 30Ins i u o Supe io Técnico, Lisbon, Po ugal 31Eu opean Commission, Join Resea ch Cen e, Geel, Re ieseweg 111, B-2440 Geel, Belgium 32Ka ls uhe Ins i u e o Technology, Campus No h, IKP, 76021 Ka ls uhe, Ge many 33Tokyo Ins i u e o Technology, Japan 34Agenzia nazionale pe le nuo e ecnologie (ENEA), Bologna, I aly 35Is i u o Nazionale di Fisica Nuclea e, Sezione di Bologna, I aly 36Dipa imen o di Fisica e As onomia, Uni e si à di Bologna, I aly 37Is i u o Nazionale di Fisica Nuclea e, Sezione di Legna o, I aly 38Is i u o Nazionale di Fisica Nuclea e, Sezione di T ies e, I aly 39Dipa imen o di As onomia, Uni e si à di T ies e, I aly 40Consiglio Nazionale delle Rice che, Ba i, I aly 41Physikalisch-Technische Bundesans al (PTB), Bundesallee 100, 38116 B aunschweig, Ge many 42Uni e si y o G anada, Spain 43Uni e si y o Vienna, Facul y o Physics, Vienna, Aus ia 44Depa men o Physics, Uni e si y o Basel, Swi ze land 45Cen e o As ophysics Resea ch, Uni e si y o He o dshi e, Uni ed Kingdom 46Bhabha A omic Resea ch Cen e (BARC), India 47Helmhol z-Zen um D esden-Rossendo , Ge many 48Aus alian Na ional Uni e si y, Canbe a, Aus alia Abs ac . The neu on cap u e eac ions o he 244Cm and 246Cm iso opes open he pa h o he o ma ion o hea ie Cm iso opes and hea ie elemen s such as Bk and C in a nuclea eac o . In addi ion, bo h iso opes belong o he mino ac inides wi h a la ge con ibu ion o he decay hea and o he neu on emission in i adia ed uels. The e a e only wo p e ious 244Cm and 246Cm cap u e c oss sec ion measu emen s: one in 1969 using a nuclea explosion [1] and he mos ecen da a measu ed a J-PARC in 2010 [2]. The da a o bo h iso opes a e e y sca ce due o he di icul ies in pe o ming he measu emen s: high in insic ac i i y o he samples and limi ed acili ies capable o p o iding iso opically en iched samples. We ha e measu ed bo h neu on cap u e c oss sec ions a he n_TOF Expe i- men al A ea 2 (EAR-2) wi h h ee C6D6de ec o s and also a A ea 1 (EAR-1) wi h he TAC. P elimina y esul s assessing he quali y and limi a ions (back- g ound sub ac ion, measu emen echnique and coun ing s a is ics) o his new expe imen al da ase s a e p esen ed and discussed. 1 In oduc ion Accu a e neu on cap u e c oss sec ion da a o mino ac inides (MAs) a e equi ed o es i- ma e he p oduc ion and ansmu a ion a es o MAs in ligh -wa e eac o s (LWR) wi h a high bu nup, c i ical as eac o s like Gen-IV sys ems and o he inno a i e de ices such as ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 2 accele a o d i en sys ems (ADS) [3]. The 244Cm (T1/2=18.1 yea s) and 246Cm (T1/2=4730 yea s) iso opes a e among he mos impo an MAs due o he di icul ies in hei ansmu a- ion and hei con ibu ion o he adio oxici y o he i adia ed nuclea uels. In pa icula , e en a e h ee yea s o cooling, 244Cm sha es nea ly 50% o he o al ac inide decay hea in i adia ed eac o uels wi h a high bu nup. In addi ion, bo h o hem a e in he pa h o he c ea ion o any hea ie Cm iso opes and hea ie elemen s like Bk and C . Only wo p e ious cap u e measu emen s we e done be o e he n_TOF measu emen s. The i s one, done in 1969 [1], used he neu ons p oduced in an unde -g ound nuclea explo- sion. The 244Cm (n,γ) c oss sec ion was measu ed in a ange om 20 eV o 1 keV and o he 246Cm(n,γ) om 20 eV o 400 eV. The second cap u e measu emen was pe o med in 2010 wi h a la ge co e age Ge-a ay in he Accu a e Neu on Nucleus Reac ion Measu e- men Ins umen (ANNRI) a J-PARC [2]. In his second measu emen he da a ob ained o bo h iso opes ange om 2 eV o 300 eV. The esonance analysis was done up o 30 eV. The sca ci y o he a ailable da a and he many expe imen al challenges in ol ed in he wo p e- ious measu emen s mo i a ed an addi ional measu emen unde di e en condi ions, i.e., in a di e en acili y, wi h di e en de ec o s and moni o s and wi h a di e en me hodology. 2 Expe imen The same samples used a J-PARC ha e been measu ed a n_TOF. In his acili y, he neu on beam is gene a ed h ough spalla ion o 20 GeV/c p o ons, which a e ex ac ed in pulses om he CERN P o on Synch o on and impinging on a lead a ge . The pulses ha e a nominal in ensi y o 7×1012 p o ons and a ime sp ead o 7 ns ( ms). The neu ons a el along wo beam lines owa ds he wo expe imen al a eas along : EAR-1 ligh leng h o 185 m [4] (ho izon al) and EAR-2 ligh leng h o 19 m [5] ( e ical). The neu on lux is la ge in he EAR-2 and he ene gy esolu ion is be e in he EAR-1. The samples ha e been measu ed in bo h expe imen al a eas. The measu emen in EAR-2 has been done wi h h ee C6D6de ec o s and he To al Ene gy De ec ion (TED) [6] echnique, and he measu emen in EAR-1 wi h he n_TOF To al Abso p ion Calo ime e (TAC) [7], designed o de ec he comple e γ- ay cascade. Measu ing in bo h expe imen al a eas wi h di e en de ec o s and echniques will allow o c osscheck esul s and, p esumably, o educe he inal unce ain ies. The a ge s used o he expe imen consis in wo samples o 244Cm and one o 246Cm. The e we e 0.4 mg o 244Cm in each o he 244Cm samples and 1.1 mg o 246Cm in he 246Cm sample. The iso opic abundances o he di e en ac inides a e p esen ed in Table 1. Table 1. Iso opic composi ion (% a oms) o he 244Cm and 246Cm samples. 244Cm sample 246Cm sample 244Cm 60.3±1.1 20.3±0.5 245Cm 2.4±0.3 1.1±0.3 246Cm 6.3±0.6 57.7±1.5 247Cm - 2.8±0.4 248Cm - 8.8±0.2 240Pu 31.0±0.6 9.3±0.2 2.1 Measu emen a he EAR-2 The h ee C6D6de ec o s we e placed a 5 cm om he sample and pe pendicula o he beam. In addi ion, h ee addi ional de ec o s we e used o moni o ing he beam. Two o ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 3 hem measu ed he in ensi y o he p o on beam. The hi d one was he SiMon [8], an a ay o ou silicon de ec o s acing a hin en iched li hium luo ide oil, o moni o ing he neu on beam. To ob ain accu a e weigh ing unc ions equi ed o he PHWT [9] echnique, a e y de ailed desc ip ion o he expe imen al se -up has been implemen ed in he Gean 4 oolki [10]. The simula ed esponse unc ions ha e been alida ed wi h expe imen al da a ob ained wi h se e al calib a ion sou ces ( 133Ba, 137Cs, 60Co, 88Y, AmBe and CmC). The geome y implemen ed in Gean 4 and one o he simula ed esponse unc ions a e shown in Figu e 1. The da a ob ained a n_TOF a e p ocessed wi h he Pulse Shape Analysis (PSA) ou ine [11]. (MeV) dep E 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 coun s/second/BinWid h 1000 2000 3000 4000 5000 6000 MC Exp-Backg ound Figu e 1. Geome y o he EAR-2 se up as implemen ed in Gean 4 (le ). Compa ison be ween simu- la ed (MC) and expe imen al esponse unc ion o an 88Y sou ce ( igh ). The esul s o he i s a e s o ed in ROOT iles [12]: signal ampli udes, signal a eas, imes, e c.. Also he con e sion om ime-o - ligh o neu on ene gy is done. Accu a e ampli ude- o-ene gy calib a ions and gain s abili y checks we e pe o med on a weekly basis o he h ee C6D6de ec o s using 133Ba, 137Cs, 60Co, 88Y, AmBe and CmC calib a ion sou ces. Small gain shi s ( 8%) a e obse ed and co ec ed as a unc ion o ime. The o al numbe o coun s as a unc ion o neu on ene gy measu ed wi h he Cm samples in place a e shown in Figu e 2. Also shown a e he es ima ed o al backg ound, he beam ela ed backg ound, and he no-beam ela ed backg ound. These backg ounds ha e been ob ained om dedica ed measu emen s. A p elimina y bu a he comple e analysis o he da a measu ed a he EAR-2 has been pe o med and wo p elimina y cap u e yields (no backg ound sub ac ed) ha e been ob- ained, one o he 244Cm samples and he o he o he 246Cm sample. Bo h yields (no backg ound sub ac ed) a e p esen ed in Figu e 3 oge he wi h he yields ob ained om he JEFF-3.3 [13] c oss sec ions wi h he expe imen al backg ound and he cha ac e is ics o he EAR-2 neu on beam (neu on lux + esolu ion unc ion)[14]. The ela i e di e ences be- ween he expe imen al and he e alua ed yields (in %) a e shown a he bo om o each panel, in eg a ed o each esonance. The esul s ha e been no malized o he i s la ge esonance o 240Pu a 1 eV. ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 4 Neu on ene gy(eV) 2− 10 1− 10 1 10 2 10 Coun s 4 10 5 10 Cm sample 244 Beam bkg. No beam bkg. To al bkg. Neu on ene gy(eV) 2− 10 1− 10 1 10 2 10 Coun s 4 10 5 10 Cm sample 246 Beam bkg. No beam bkg. To al bkg. Figu e 2. To al numbe o coun s (750 bins pe decade) and es ima ed backg ounds egis e ed in he 244Cm (le ) and 246Cm ( igh ) EAR-2 measu emen s. ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 5 (eV) n E 1 2 3 4 5 6 7 8 9 10 Cap u e Yield + bkg 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm - 1000 bins pe decade 244 1 2 3 4 5 6 7 8 9 10 2− 1.5− 1− 0.5− 0 0.5 1 1.5 2 (eV) n E 1 2 3 4 5 6 7 8 9 10 Cap u e Yield + bkg 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm-245 (n, ) Cm-247 (n, ) )γCm-248 (n, )γAm-243 (n, Cm sample - 1000 bins pe decade 246 1 2 3 4 5 6 7 8 9 10 15− 10− 5− 0 5 10 15 (eV) n E 10 20 30 40 50 60 70 Cap u e Yield + bkg 14 16 18 20 22 24 26 28 3− 10× Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm - 1000 bins pe decade 244 10 20 30 40 50 60 70 50− 40− 30− 20− 10− 0 10 20 30 40 50 (eV) n E 10 20 30 40 50 60 70 Cap u e Yield + bkg 12 14 16 18 20 3− 10× Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm-245 (n, ) Cm-247 (n, ) )γCm-248 (n, )γAm-243 (n, Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm-245 (n, ) Cm-247 (n, ) )γCm-248 (n, )γAm-243 (n, Cm sample - 1000 bins pe decade 246 10 20 30 40 50 60 70 15− 10− 5− 0 5 10 15 (eV) n E 80 100 120 140 160 180 200 Cap u e Yield + bkg 11 12 13 14 15 16 17 18 19 20 3− 10× Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm - 750 bins pe decade 244 80 100 120 140 160 180 200 60− 40− 20− 0 20 40 60 (eV) n E 80 100 120 140 160 180 200 Cap u e Yield + bkg 10 12 14 16 18 3− 10× Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm-245 (n, ) Cm-247 (n, ) )γCm-248 (n, )γAm-243 (n, Expe imen al Yield To al Sammy Yield )γPu-240 (n, )γCm-244 (n, )γCm-246 (n, Cm-244 (n, ) Cm-245 (n, ) Cm-247 (n, ) )γCm-248 (n, )γAm-243 (n, Cm sample - 750 bins pe decade 246 80 100 120 140 160 180 200 60− 40− 20− 0 20 40 60 Figu e 3. P elimina y expe imen al yields (no backg ound sub ac ed) o he measu ed 244Cm (le ) and 246Cm ( igh ) samples. Toge he wi h he expe imen al da a poin s, we show an es ima ion o he con ibu ion o he cap u e and ission eac ions in each iso ope p esen in he samples. These con ibu- ions ha e been ob ained using he SAMMY compu e code o calcula e he eac ion yields aking in o accoun he expe imen al condi ions such as Dopple and esolu ion b oadening, and aking he eac ion c oss sec ions om JEFF-3.3. The esul ing yields we e hen no malized o i he expe imen al esul s and added o he backg ound, ob ained om dedica ed measu emen s. ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 6 2.2 Measu emen a he EAR-1 The measu emen in EAR-1 was pe o med wi h he TAC, which is an a ay o 40 BaF2 c ys als designed o de ec he ull cap u e γ- ay cascades. The da a analysis is ongoing and i will ollow simila p ocedu es han he ones pe o med in p e ious TAC expe imen s [15] [16]. Signals a e g ouped in o TAC e en s wi h a 20 ns coincidence window, and cu s in o al deposi ed ene gy and de ec ion mul iplici y allow o imp o e he signal o backg ound a io. The o al numbe o coun s as a unc ion o neu on ene gy measu ed wi h he 244Cm samples in place a e shown in Figu e 4, oge he wi h he es ima ed backg ounds. The be e ene gy esolu ion and smalle ins an aneous neu on luence in EAR-1 esul s in a na owe esonan s uc u e and a la ge con ibu ion o he no-beam ela ed backg ound. Neu on ene gy(eV) 1 10 2 10 Coun s 2 10 3 10 4 10 Cm sample 244 Beam bkg. No beam bkg. To al bkg. Figu e 4. To al numbe o coun s (1000 bins pe decade) and es ima ed backg ounds egis e ed in he 244Cm EAR-1 measu emen . 3 Conclusions The cap u e c oss sec ions o 244Cm and 246Cm a e equi ed o es ima e he p oduc ion and ansmu a ion a es o MAs in LWR and also o new eac o ypes. The e a e only wo p e ious cap u e measu emen s o hese wo iso opes, bo h o hem wi h many expe imen- al di icul ies.The e o e, a new measu emen has been pe o med a n_TOF using he wo expe imen al a eas and p elimina y cap u e yields ha e been ob ained. Re e ences [1] M. S. Moo e e . al., Phys. Re . C, 3, 1656 (1971) [2] A. Kimu a e . al., Jou . Nucl. Sc. Tech. 49, 708 (2012) [3] G. Alibe i e . al., , Ann. Nucl. Ene . 33, 700 (2006) [4] C. Gue e o e al., Eu . Phys. J. A 49, 27 (2013) [5] C. Weiss e al., Nucl. Ins um. Me h. A 799, 90 (2015) [6] R.L. Macklin and J.H. Gibbons,Phys. Re . 159, 1007 (1967) [7] C.Gue e o e al., Nucl. Ins um. Me h. A 608, 424 (2009) [8] S. Ma one e al., Nucl. Ins um. Me h. A 517, 389 (2004) ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 7 [9] Abondano e al., Nucl. Ins um. Me h. A 521, 454 (2004) [10] S. Agos inelli e al., Nucl. Ins um. Me h. A 506, 250 (2003) [11] P. Žugec e al., Nucl. Ins um. Me h. A 812, 134 (2016) [12] h ps:// oo .ce n.ch/ [13] A. Koning e al., J. Ko ean Phys. Soc. 59, 1057 (2011); The JEFF lib a y is a ailable om h ps://www.oecd-nea.o g/dbda a/je [14] M. Saba é-Gila e e al., Eu . Phys. J 53, 10 (2017) [15] C. Gue e o e al., Phys. Re . C 85, 044616 (2012) [16] E. Mendoza e al., Phys. Re . C 90, 034608 (2014) ,(201 E Web o Con e ences h ps://doi.o g/10.1051/e on /20192 PJ pjc 9) 211 000811030 WONDER-2018 30 8 8