Cluster states in 11B

This is an elec onic ep in o he o iginal a icle. This ep in may di e om he o iginal in pagina ion and ypog aphic de ail. Au ho (s): Ti le: Yea : Ve sion: Please ci e he o iginal e sion: All ma e ial supplied ia JYX is p o ec ed by copy igh and o he in ellec ual p ope y igh s, and duplica ion o sale o all o pa o any o he eposi o y collec ions is no pe mi ed, excep ha ma e ial may be duplica ed by you o you esea ch use o educa ional pu poses in elec onic o p in o m. You mus ob ain pe mission o any o he use. Elec onic o p in copies may no be o e ed, whe he o sale o o he wise o anyone who is no an au ho ised use . Clus e s a es in 11B Danilo , A.N.; Demyano a, A.S.; Ogloblin, A.A.; Dmi ie , S.V.; Belyae a, T.L.; Goncha o , S.A.; Gu o , Yu.B.; Maslo , V.A.; Sobole , Yu.G.; T zaska, Wladyslaw; Khlebniko , S.V.; Bu ebae , N.; Zholdybaye , T.; Saduye , N.; Heikkinen, Pauli; Julin, Rauno; Tyu in, G igo y Danilo , A.N., Demyano a, A.S., Ogloblin, A.A., Dmi ie , S.V., Belyae a, T.L., Goncha o , S.A., Gu o , Yu.B., Maslo , V.A., Sobole , Yu.G., T zaska, W., Khlebniko , S.V., Bu ebae , N., Zholdybaye , T., Saduye , N., Heikkinen, P., Julin, R., & Tyu in, G. (2014). Clus e s a es in 11B. In S. Luna di, P. Bizze i, S. Kabana, C. Bucci, M. Chia i, A. Dainese, P. D. Nezza, R. Menegazzo, A. Nannini, & C. S. A. J. Valien e-Dobon (Eds.), INPC 2013 – In e na ional Nuclea Physics Con e ence Fi enze, I aly, June 2-7, 2013 (A icle 03007). EDP Sciences. EPJ Web o Con e ences, 66. h ps://doi.o g/10.1051/epjcon /20146603007 2014 Clus e s a es in 11B A.N. Danilo 1a, A.S. Demyano a1, A.A. Ogloblin1, S.V. Dmi ie 1, T.L.Belyae a2, S.A.Goncha o 3, Yu.B. Gu o 4, V.A. Maslo 5, Yu.G. Sobole 5, W. T zaska6, S.V. Khlebniko 7, N. Bu ebae 8, T. Zholdybaye 8, N. Saduye 9, P. Heikkinen6, R. Julin6, G.P. Tyu in6 1 NRC Ku cha o Ins i u e, Moscow 123182, Russia 2 Uni e sidad Au onoma del Es ado de Mexico, Codigo Pos al 50000, Toluca, Mexico 3 Lomonoso Moscow S a e Uni e si y, Moscow, Russia 4 MEPhi, Moscow, Russia 5 JINR, Moscow egion, Russia 6 JYFL, Jy askyla, Finland 7 Khlopin Radium Ins i u e, S .-Pe e sbu g, Russia 8 Nuclea Physics Ins i u e, Alma y, Kazakhs an 9 Al-Fa abi Kazakh Na ional Uni e si y, Kazakhs an Abs ac . The di e en ial c oss-sec ions o he elas ic and inelas ic 11B + α sca e ing was measu ed a E(α) = 65 MeV. The analysis o he da a by Modi ied di ac ion model (MDM) showed ha he RMS adii o he 11B s a e 3/2-, E* = 8.56 MeV is ~ 0.6 m la ge han ha o he g ound s a e. The 12.56 MeV s a e was no obse ed con a y o he p edic ions o he α-condensa e model. The 13.1 MeV s a e was exci ed wi h he angula momen um ans e L = 4 con i ming i s belonging o he o a ional band wi h he 8.56 MeV s a e as a head. 1 In oduc ion P og ess in he heo y o clus e physics, in pa icula , he hypo hesis abou possible exis ence o he alpha-pa icle condensa e in nuclei ini ia ed wo k o ind nuclea s a es wi h ex emely la ge size. I was p edic ed ha wo le els in 11B: ½-, E * = 8.56 MeV and ½+ (possibly a 12.56 MeV) ha e he oo mean squa e adii R ms = 3.1 m [1] and ~ 6 m [2] co espondingly, while he g ound s a e has R ms = 2.29 m. Fo checking hese p edic ions di e en ial c oss sec ions o he inelas ic sca e ing α + 11B a E(α) = 65 MeV we e measu ed and analyzed oge he wi h he da a ob ained a di e en ene gies. The analysis was done by he Modi ied Di ac ion Model (MDM) [3]. This me hod allows de e mining he adii R* ms o he exci ed s a es ia he di e ence o he di ac ion adii o he exci ed and he g ound s a es using he exp ession: R*= R0 + [R* di − Rdi (0)] (1) He e R0 is he RMS o he g ound s a e o he nucleus unde discussion, R* di and Rdi (0) a e he di ac ion adii de e mined om he posi ions o he minima and maxima o he expe imen al angula dis ibu ions o he inelas ic and elas ic sca e ing co espondingly. Such app oach allowed inding he a Co esponding au ho : danilo 1987@mail. u DOI: 10.1051/ C Owned by he au ho s, published by EDP Sciences, 2014 , / 03007 (2014) 201 66 epjcon EPJ Web o Con e ences 46603007 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 2.0, which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed. A icle a ailable a h p://www.epj-con e ences.o g o h p://dx.doi.o g/10.1051/epjcon /20146603007 consis en alues o he RMS adius o he Hoyle s a e om 2H, 3He, 4He, 6Li, 12C inelas ic sca e ing measu ed on he 12C a ge in a wide ene gy ange [4]. The goal o he expe imen was o de e mine he adii alues o he exci ing s a es in 11B using MDM. 2 Expe imen al da a We measu ed he di e en ial c oss-sec ions o he inelas ic α + 11B sca e ing wi h exci a ion he s a es o 11B up o E* ~ 14 MeV. The expe imen was done a he JYFL cyclo on K130, Jy askyla Uni e si y, Finland using LSC (La ge Sca e ing Chambe ) wi h ΔE-E elescopes o semiconduc o coun e s. The a ge was an 11B sel -suppo ed ilm o 0.275 mb/cm2 hickness. The only signi ican impu i y was 12C. The beam monoch oma iza ion sys em was used allowing p o iding he o al ene gy esolu ion o he expe imen o be 150 keV. A sample spec um is shown on Fig. 1. 40 45 50 0 80 160 240 11.6 coun s E (MeV) g.s.12C 4.4412C 2.12 4.44 5.02 6.74 7.29 7.98 8.56 9.27 10,34 10.6 11.27 12.6 12.92 13.1 g.s. Figu e 1. A sample α-pa icles spec um a E (α) =65 MeV, Θ=53.5 deg. 3 Resul s and discussions 3.1 8.56 MeV s a e The alue o he 8.56MeV s a e adius was de e mined o be R ms = 2.87 ± 0.12 m, which is 0.6 m la ge han he adius o he g ound s a e being in ag eemen wi h he p e ious da a (R ms = 2.99 ± 0.18 m om Re . [5]). The ob ained adius is p ac ically equal o he adius o he second exci ed s a e o 12C, he Hoyle s a e. The adius o he Hoyle s a e was de e mined o be R ms = 2.89 ± 0.04 m [3]. So he ob ained esul oge he wi h he simila i y o he shapes o he angula dis ibu ions (Fig. 2) and he simila i y o he ene gy dependence o di ac ion adii (Fig. 3) clea ly indica es o he simila i y o he s uc u es o he 8.56 MeV s a e o 11B and he Hoyle s a e o 12C. The 8.56 MeV s a e can be conside ed as an analogue o he Hoyle s a e in neighbo ing nuclei. EPJ Web o Con e ences 03007-p.2 0 10 20 30 40 50 60 70 80 90 0,01 0,1 1 10 d/dΩ (mb/s ) CM Figu e 2. Di e en ial c oss-sec ions o inelas ic sca e ing α + 11B a Eα=65 MeV leading o 8.56 MeV s a e ( ed poin s) and inelas ic sca e ing α + 12C a Eα=65 MeV leading o 7.65 MeV s a e (black poin s) 0 100 200 300 4,0 4,5 5,0 5,5 6,0 6,5 Rdi ( m) Ec.m.(MeV) Figu e 3. Ene gy dependence o di ac ion adii: black dashed line – di ac ion adii o elas ic sca e ing α + 12C, ed dashed line – o 7.65 Hoyle s a e, black poin s – o elas ic α + 11B, black solid line – linea i o black poin s, ed poin s – o 8.56 MeV s a e, ed solid line – linea i o ed poin s 3.2 Ro a ional band based on 8.56 MeV s a e We go p elimina y esul s o he di e en ial c oss-sec ion o he inelas ic sca e ing leading o 10.34 MeV (5/2-) and 13.1 MeV (9/2-) s a es. These s a es a e p edic ed [6,7] as he second and he ou h membe s o he o a ional band based on he 8.56 MeV s a e. The beha io o he angula dis ibu ion o he inelas ic sca e ing wi h he exci a ion o he 13.1 MeV s a e is he same as o he inelas ic sca e ing o α + 12C wi h he exci a ion o he 14.08 MeV (Fig. 4). The las is well known o be exci ed by ansi ion L=4. The MDM was used o es ima ing he adius o he 13.1 MeV s a e. The bes i was ob ained wi h he di ac ion adius Rdi =4.5 m, he alue which coincides wi h ha o he L = 4 ansi ion in he 12C (α, α’) eac ion o a new s a e o 12C a E* = 13.75 MeV [8] belonging o he o a ional band based on he Hoyle s a e. In some a icles [6] he e a e assump ions ha he 13.1 MeV s a e is he membe o he hypo he ical o a ional band based on he g ound s a e. Wi hin hese assump ions he p e ious membe o his band is he 6.74 MeV s a e wi h abno mally la ge ine ia momen um. We ha e go he angula dis ibu ion wi h he exci a ion o his s a e and didn’ obse e any RMS adius enla gemen , wha is na u ally can be expec ed in acco dance wi h sha p inc ease o ine ia momen um. I is qui e possible ha abo emen ioned o a ional band doesn’ exis and low- lying s a es o 11B ha e no mal shell-model s uc u e. So he 13.1 MeV is mo e p obable o be he membe o he band based on he 8.56 MeV s a e. INPC 2013 03007-p.3 0 20 40 60 80 0,01 0,1 1 10 d  /dΩ (mb/s ) CM Figu e 4. Di e en ial c oss-sec ions o inelas ic sca e ing α + 11B a Eα = 65 MeV leading o 13.1 MeV s a e ( ed poin s) and inelas ic sca e ing α + 12C a Eα = 65 MeV leading o 14.08 MeV s a e (black poin s) 3.3 12.56 MeV s a e Fo he 12.56 MeV (½+, T=3/2) s a e [9] o 11B he e exis s con adic o y in o ma ion conce ning i s isospin. The model [2] sugges ha Jπ=½+, T = ½. In ou expe imen we obse ed a g oup o s a es, among hem is he s a e wi h exci a ion ene gy 12.6 MeV. Also such s a e was de ec ed in he esonance eac ion 7Li + α [6]. A T = 3/2 s a e is unexpec ed o be obse ed in he inelas ic alpha pa icle sca e ing, so isospin o his s a e is T = ½. P elimina y analysis o angula dis ibu ion indica es o angula ans e ed momen um L=1, so spin o his s a e is 3/2+, in ag eemen wi h [6]. Thus, we can conclude ha he p edic ions [2] we e no con i med. Theo e ical calcula ions a e in a p og ess. The wo k was suppo ed by he G an o RFBR, No 12-02-000927-a. Re e ences 1. Y. Kanada-En’yo, Phys. Re . C 75, 024302 (2007) 2. T. Yamada and Y. Funaki, Phys. Re . C 82, 064315 (2010) 3. A.N. Danilo e al., Phys.Re . C 80, 054603 (2009) 4. A.S. Demyano a e al., Nucl. Phys. A 805, 489 (2008) (P oceedings o he 23 d In e n. Nuclea Physics Con e ence (INPC2007), Tokyo, Japan, 3-8 June, 2007 5. A.S.Demyano a e al., In . J. o Mode n Physics E 20, 915 (2011) 6. H. Yamaguchi e al., Phys. Re . C 83, 034306 (2011) 7. T. Saha a and Y. Kanada-En’yo, Phys. Re . C 85, 054320, (2012) 8. A.A. Ogloblin e al., P oceeding o his con . INPC2013, pos e numbe - NS 160 9. F. Ajzenbe g-Selo e, Nucl. Phys. A 506, 1 (1990) EPJ Web o Con e ences 03007-p.4