Elastic scattering and breakup of 11 Be on deuterons at 26.9 A MeV

PHYSICAL REVIEW C 94, 064620 (2016) Elas ic sca e ing and b eakup o 11Be on deu e ons a 26.9AMeV J. Chen,1J. L. Lou,1,*Y. L. Ye,1J. Rangel,2A. M. Mo o,3D. Y. Pang,4Z. H. Li,1Y. C. Ge, 1Q. T. Li,1J. Li,1W. Jiang,1 Y. L. Sun,1H. L. Zang,1Y. Zhang,1N. Aoi,5E. Ideguchi,5H. J. Ong,5J. Lee,6J. Wu,6H. N. Liu,6C. Wen,6Y. Ayyad,5 K. Ha anaka,5T. D. T an,5T. Yamamo o,5M. Tanaka,5T. Suzuki,5and T. T. Nguyen5 1School o Physics and S a e Key Labo a o y o Nuclea Physics and Technology, Peking Uni e si y, Beijing 100871, China 2Ins i u o de F´ ısica, Uni e sidade Fede al Fluminense, A enida Li o anea s/n, G agoa ´ a, 24210-340, Ni e ´ oi, Rio de Janei o, B azil 3Depa amen o de FAMN, Uni e sidad de Se illa, Apa ado 1065, 41080 Se illa, Spain 4School o Physics and Nuclea Ene gy Enginee ing, Beijing Key Labo a o y o Ad anced Nuclea Ma e ials and Physics, Beihang Uni e si y, Beijing 100191, China 5Resea ch Cen e o Nuclea Physics, Osaka Uni e si y, Osaka, Japan 6RIKEN (Ins i u e o Physical and Chemical Resea ch), 2-1 Hi osawa, Wako, Sai ama 351-0198, Japan (Recei ed 31 Augus 2016; published 30 Decembe 2016) The elas ic sca e ing and b eakup eac ions o he halo nucleus 11Be on deu e ons a an inciden ene gy o 26.9AMeV a e epo ed o he i s ime. Special a en ion has been paid o he de e mina ion and sub ac ion o he p o on con amina ions in he deu e a ed polye hylene (CD2)n a ge (whe e D2deno es 2H2). The c oss sec ions o elas ic sca e ing a e analyzed wi h he sys ema ic op ical po en ials o Daehnick e al. and DA1p, as well as wi h single- olding po en ials, de i ed om he Jeukenne-Lejeune-Mahaux e ec i e nucleon-nucleon in e ac ion. An ex ended e sion o he con inuum-disc e ized coupled-channels (XCDCC) o malism, including dynamic co e exci a ion (DCX) e ec s, is applied o analyze he elas ic sca e ing and b eakup da a. Compa isons o he ull XCDCC calcula ion wi h ha omi ing DCX e ec s indica e ha he co e exci a ion plays a ema kable ole in ep oducing b eakup eac ions o 11Be +d. DOI: 10.1103/PhysRe C.94.064620 I. INTRODUCTION The in es iga ion o exo ic nuclei has con inuously de el- oped since he ea ly 1980s hanks o he a ailabili y o a ious ools o adioac i e beam p oduc ion, including in- ligh agmen a ion, which p o ide e e inc easing accessibili y o he nuclea landscape a om he β-s abili y line [1–3]. 11Be was ex ensi ely s udied as a neu on-halo nucleus. I s small one-neu on sepa a ion ene gy o 504 keV oge he wi h he dominan s-wa e con igu a ion o he alence neu on lead o a e y ex ended neu on-densi y dis ibu ion [4–6]. The pa i y in e sion o i s g ound s a e (1/2+) was p edic ed by Talmi and Unna [7] and con i med by he expe imen al measu emen o Albu ge e al. [8]. Nume ous measu emen s and s uc u e calcula ions sugges ha he g ound s a e o 11Be con ains, in addi ion o he dominan 10Be(0+)+n(s1/2) con igu a ion, a signi ican admix u e (∼20%) o co e exci ed componen s, wi h he alence neu on p e e ably occupying he d5/2o bi [9–11]. The sizable co e exci a ion componen s in he 11Be g ound s a e play an impo an ole in ea u ing he 11Be s uc u e. Fu he mo e, when conside ing he collision o 11Be on a a ge , he coupling be ween he collec i e exci a ions and he co e exci a ions would a ec he eac ion dynamics. Bo h e ec s (s uc u e and dynamics) ha e been imple- men ed in an ex ended e sion o he con inuum-disc e ized coupled-channels (XCDCC) o malism p oposed by Summe s e al. [12], and in a no- ecoil ex ended dis o ed wa e Bo n app oxima ion (XDWBA) model [13]. Co e exci a ion was *[email p o ec ed] shown o ha e a signi ican e ec on he b eakup c oss sec ions in calcula ions using he XCDCC model o he b eakup o 11Be on a p o on a ge a inciden ene gies o 63.7 [13–15] and 26.9AMeV [16]. These wo measu emen s con i med he co e exci a ion e ec s a a ious inciden ene gies. Fu he mo e, co e exci a ion was demons a ed o be impo an on a ious igh ly bound a ge s, like 1H[13–15], 12C[11], 64Zn [17,18], and 208Pb [11]. I is in e es ing o examine he co e exci a ion e ec on he weakly bound a ge s, such as a deu e on a ge . His o ically, he deu e on, as a ypical weakly bound nucleus, is o g ea impo ance in nuclea eac ion s udy. Mos di ec nuclea eac ions, such as s ipping, ans e , and pickup, we e i s s udied wi h deu e on beams due o hei easy access by accele a o s. Deu e on-induced eac ions ha e been one o he mos powe ul spec oscopic ools o ex ac s uc u e in o ma ion o s able nuclei. These s udies can be ex ended o he case o uns able nuclei, using expe imen s in in e se kinema ics. Fo uns able p ojec iles close o he d ip lines, he desc ip ion o hese eac ions is, howe e , challenging because one has o ea coupling a ising om bo h he p ojec ile and a ge b eakup. The measu emen o hese kinds o da a, along wi h he modi ica ion o ela ed eac ion o malisms o desc ibe hem, is he e o e a opic o imely in e es o eliably ex end he spec oscopic s udies wi h deu e ons o egions a om he s abili y line. In his wo k, we p esen he da a o elas ic sca e ing and b eakup o 11Be, o he i s ime, on a deu e on a ge a 26.9AMeV. The beam ene gy was chosen conside ing he alidi y o bo h b eakup and ans e eac ion mechanisms, he a ailabili y o he beam, he e ec i e de ec ion o ecoil ligh cha ged pa icles a la ge angles, and he complemen o he p e ious b eakup eac ion wo k a highe ene gy [19] 2469-9985/2016/94(6)/064620(8) 064620-1 ©2016 Ame ican Physical Socie y J. CHEN e al. PHYSICAL REVIEW C 94, 064620 (2016) and ans e eac ion expe imen s a lowe ene gies [20,21]. The pape is o ganized as ollows. In Sec. II we p esen he de ails o he expe imen , and he da a analysis. Special a en ion is paid o he de e mina ion and sub ac ion o he p o on con amina ions in he (CD2)n a ge (whe e D2 deno es 2H2). In Sec. III we show an op ical model analysis o he elas ic sca e ing da a in e ms o phenomenological op ical po en ials. In Sec. IV he angula dis ibu ions o elas ic sca e ing and b eakup a e compa ed wi h he XCDCC calcula ions, and he impo ance o he co e exci a ion e ec is also discussed. Finally, in Sec. Vwe summa ize he main esul s o his wo k. II. EXPERIMENTAL RESULTS The expe imen was pe o med on he EN-cou se beam line a he Resea ch Cen e o Nuclea Physics (RCNP), Osaka Uni e si y, Japan [22]. The p ima y beam 13Ca 60AMeV impinged on a hick 9Be a ge o p oduce a seconda y beam o 11Be, which was sepa a ed and pu i ied by he elec omagne ic sepa a o . The beam in ensi y and pu i y o 11Be was app oxi- ma ely 1 ×104pa icles pe second and 95%, espec i ely. The momen um sp ead was limi ed, by a sli a he dispe sion plane, down o P/P=1% o educe he ene gy sp ead o he beam. The beam spo size on he physical a ge is less han φ20 mm. The expe imen al se up can be ound in Re . [16], and only de ec o s ele an o he elas ic sca e ing and b eakup o 11Be +da e desc ibed he e. Telescopes TELE0 and TELE1 we e employed o de ec he p ojec like iso opes and he ecoil ligh pa icles, espec i ely. TELE0, comp ising a double-sided silicon s ip de ec o (DSSD) wi h a hickness o 1000 μm and wo la ge su ace silicon de ec o s (SSDs) 1500 μm hick, was ins alled a a ound 0◦ ela i e o he beam di ec ion. TELE1 is composed o a 300-μm DSSD, a 1500-μm SSD, and a laye o ou CsI(Tl) c ys als ead ou by pho odiodes. The ac i e a ea and s ip wid h o each DSSD is 62.5 ×62.5 mm2and 2 mm, espec i ely. The dis ance be ween he cen e o he a ge and TELE0 (TELE1) is 200 (170) mm. A (CD2)n a ge wi h a hickness o 4 mg/cm2 was moun ed as he physical a ge , oge he wi h a ca bon ilm (12 mg/cm2) and also a (CH2)n oil (4 mg/cm2)used o backg ound measu emen s. The (CD2)n a ge hickness is op imized in o de o ha e enough ecoil deu e on yield while e aining good esolu ion o exci a ion ene gies in 11Be deduced om he ecoil deu e ons. Ta ge s we e il ed 15◦ o es ic he ene gy loss o he ecoil ligh pa icles in he a ge . Fo deu e ons elas ically sca e ed o 81.5◦, co esponding o he minimum de ec ion angle in he cen e -o -mass sys em (16.5◦) o 11Be, he ecoil deu e on ene gy is 3.3 MeV while i s ene gy loss in he a ge is abou 1.19 MeV, assuming he eac ion poin a he middle o he il ed a ge , which is good enough o mee he de ec ion and esolu ion equi emen s. In coincidence wi h he ecoil ligh pa icles, he esidual agmen s we e iden i ied wi h E −Eme hod. 10Be is well sepa a ed om 11Be as shown in he pa icle iden i ica ion (PID) spec um in Fig. 1. The di e en ial c oss sec ions o he 11Be +delas ic sca e ing and b eakup can be ex ac ed om he ecoil deu e ons in coincidence wi h 11Be and 10Be, espec i ely. E (MeV) 120 140 160 180 200 220 240 260 280 300 E (MeV) 55 60 65 70 75 80 85 90 11Be 10Be FIG. 1. The PID using da a aken by TELE0 in coincidence wi h ligh pa icles measu ed by TELE1. Figu es 2(a) and 2(b) illus a e ene gies e sus angles o he ecoil ligh pa icles (p o on and deu e on) measu ed by TELE0 in coincidence wi h 11Be and 10Be de ec ed by TELE1, espec i ely. The ene gy losses o deu e ons in he a ge we e co ec ed o he deduced exci a ion ene gy spec a in Fig. 2, assuming a eac ion poin a he middle o he a ge . A cu o labo a o y angles smalle han 80◦was applied due o he ene gy de ec ion h eshold o he ecoil ligh pa icles. Mos e en s lie along he kinema ic cu es o he 11Be +d elas ic (solid cu e) and inelas ic sca e ing (dashed and do ed cu es), bu a small po ion o e en s dis ibu e a ound he kinema ic lines o 11Be +p(do -do -dashed cu e). The eason is ha he deu e a ed compounds a e usually con amina ed by some hyd ogen componen , whose con ibu ions should be sub ac ed om he expe imen al da a o 11Be sca e ed om he (CD2)n a ge . In addi ion, hese e en s could also 66 70 74 78 0 5 10 15 20 25 30 E (MeV) E (MeV) (a) 66 70 74 78 0 5 10 15 20 25 30 (b) (a) Be + d 11 Be + p 11 s ipping 1.78 MeV 3.41 MeV FIG. 2. Plo o ene gy s angle o he ecoil ligh pa icles in coincidence wi h (a) 11Be and (b) 10Be o (CD2)n(colo pale es) and (CH2)n(black do s and iangles) a ge s. The calcula ed kinema ic loci o he elas ic sca e ing o 11Be +dand 11Be +pa e shown as solid and do -do -dashed cu es in (a), while ha o he 11Be +d inelas ic sca e ing o he 1.78- and 3.41-MeV esonances o 11Be a e ep esen ed as dashed and do ed cu es in (b), espec i ely. The do -dashed line s ands o he kinema ic cu e o he n-delas ic sca e ing. 064620-2 ELASTIC SCATTERING AND BREAKUP OF 11Be ON . . . PHYSICAL REVIEW C 94, 064620 (2016) 65 70 75 80 85 012345678 65 70 75 80 85 012345 678 (a) (b) Be + d 11 Be + p 11 1.78 MeV 3.41 MeV s ipping FIG. 3. Angula co ela ion spec a o he ecoil ligh pa icles and he elas ic sca e ed (a) 11Be, and (b) 10Be om he b eakup eac ion, espec i ely, on he impu e (CD2)n a ge . The de ini ions o kinema ic cu es a e he same as hose in Fig. 2. The a ea ma ked by do ed cu es in (a) shows he cu applied o he calcula ion o p o on con amina ions. The black do -dashed ci cle in (b) ep esen s he a ea o he 1ns ipping eac ion om 11Be by he (CD2)n a ge . be obse ed on he angula co ela ion spec a o he ecoil ligh pa icles and 11Be [see do -do -dashed cu e in Fig. 3(a)]. Conside ing ha he Ru he o d c oss sec ion o 11Be +pis abou ou imes la ge han ha o 11Be +da he same labo a o y angles, we could in e ha he 11Be +pelas ic sca e ing c oss sec ion is much la ge han ha o 11Be +d. As a esul , e en i he hyd ogen con amina ion is small in he (CD2)n a ge , i s in luence should no be igno ed, especially in he small cen e -o -mass angles o 11Be o la ge labo a o y angles o deu e ons [see Fig. 3(a)], whe e he sca e ed p o ons a e mixed wi h deu e ons. This e ec can be emo ed by sub ac ing he (CH2)n a ge expe imen al da a om he (CD2)nda a as long as we know he ac ion o p o on con aminan in he (CD2)n a ge . Based on he ac ha 11Be +pelas ic sca e ing di e en ial c oss sec ions a e he same o p o ons in (CH2)nand impu e (CD2)n a ge s, and he de ec o s (solid angles) a e he same du ing (CH2)nand (CD2)n a ge expe imen s, he ollowing equa ion can be es ablished: ρH-CD2 ρH-CH2 =NSH-CD2 NSH-CH2 Nin-CH2 Nin-CD2 ,(1) whe e ρH-CH2(ρH-CD2), NSH-CH2(NSH-CD2), and Nin-CH2 (Nin-CD2) s and o he p o on a eal densi y (mg/cm2), he elas ically sca e ed p o on numbe , and he incoming 11Be beam pa icle numbe o he (CH2)n[(CD2)n] a ge , e- spec i ely. Since he hickness o he (CH2)n a ge is known (4.0 mg/cm2), he densi y o p o on con amina ions in he (CD2)n a ge can be de e mined by he a io o he sca e ed p o ons in (CH2)nand (CD2)n a ge s wi h he no malized 11Be pa icle numbe . In o de o calcula e ρH-CD2we applied a cu (black do ed a ea) on Fig. 3(a) whe e he p o ons a e clea ly sepa a ed om he deu e ons and mos e en s ollow he kinema ic cu e o he 11Be +pangula co ela ions (do -do -dashed cu e). Wi h his cu , he 11Be exci a ion ene gy spec a a e deduced om ene gies and angles o he p o ons measu ed om he (CH2)nand he con amina ed (CD2)n a ge s. Finally, o he con amina ed (CD2)n a ge wi h a o al hickness o 4.0 mg/cm2used in his expe imen , he a io o p o on and deu e on numbe is de e mined o be 9.5±0.6%. The e o 0.6% is ob ained om he s a is ics o he sca e ed ligh pa icles numbe , and he incoming beam pa icles numbe . The sys ema ic e o is es ima ed o be 1.2% mainly esul ing om he di e en cu s in Fig. 3(a) and he unce ain ies in a ge hickness. In Sec. IV, he measu ed b eakup da a a e compa ed wi h XCDCC calcula ions. Because his me hod p o ides only he elas ic b eakup c oss sec ions, he con ibu ions om o he eac ion p ocesses should be emo ed om he b eakup expe imen al esul s. Simila ly o Re . [16], he coinciden measu emen o he ecoil deu e ons and 10Be can help us exclude he con ibu ions o 1ns ipping om 11Be using he kinema ic condi ions. Some de ails can be seen in Figs. 2(b) and 3(b). Fi s , he neu on s ipped om he 11Be p ojec ile by he deu e on a ge would app oxima ely ollow he kinema ics o he n-delas ic sca e ing, as shown by he black do -dashed cu e in Fig. 2(b). Second, a e he 1ns ipping eac ion, he esidual 10Be agmen s would be emi ed a ound 0◦ ela i e o he beam di ec ion. A labo a o y angles smalle han 1.2◦,a small ac ion o e en s a e clea ly sepa a ed om he angula co ela ion cu es o he 11Be +dinelas ic sca e ing; see black do -dashed ci cle a ea in Fig. 3(b). In p inciple, using he coinciden measu emen , we could ba ely de ec he 10Be om b eakup eac ion a angles smalle han 1.2◦due o he ene gy h eshold o he ecoil ligh pa icles. The e o e, he e en s in he black do -dashed ci cle in Fig. 3(b) should mainly come om he 1ns ipping eac ion o 11Be. As a esul , a cu o 10Be labo a o y angles la ge han 1.2◦was applied o ex ac he b eakup c oss sec ions. O he p ocesses, such as e apo a ion and abso p ion, can also be elimina ed using he coinciden measu emen , because he low ene gy deu e ons om hose eac ions would be emi ed a he smalle labo a o y angles [16]. Figu es 4(a) and 4(b) display he exci a ion ene gy spec a o he g ound s a e (g.s.) and he con inuum s a es o 11Be, which a e deduced om ene gies and angles o he elas ically and inelas ically sca e ed deu e ons in coincidence wi h 11Be and 10Be, espec i ely. The backg ound con ibu ions a ising om 12Cand 1Hha e been sub ac ed using he da a aken om he ca bon and (CH2)n a ge s no malized o he same numbe o beam pa icles and he equi alen ca bon and hyd ogen componen as o he (CD2)n a ge . The ull wid h a hal maximum (FWHM) o he exci a ion ene gy spec um o he elas ic sca e ing is abou 2.3 MeV [Fig. 4(a)], esul ing om he ene gy dispe sion o he 11Be beam, he ene gy losses and s aggling o he ecoil deu e ons in he a ge s, as well as he ene gy and angula esolu ion o TELE1. This alue ag ees wi h he simula ion esul using he GEANT4 package [23]. Two egions o exci a ion ene gy o he con inuum s a es we e selec ed due o he poo esolu ion. The i s one, anging om 0.5 o 3.0 MeV, is cen e ed a ound he known 5/2+ esonance a Eex =1.778 MeV. The second egion, om 3.0 o 5.5 MeV, con ains o he highe ene gy esonan s a es, such as he 3/2+s a e a Eex =3.41 MeV. The c oss sec ions o he second egion could no be ex ac ed om he 11Be +p b eakup eac ion in Re . [16] because he solid angle o TELE1 dec eases e y quickly as he exci a ion ene gy inc eases o ha eac ion. Fo he 11Be +db eakup eac ion, simula ions 064620-3 J. CHEN e al. PHYSICAL REVIEW C 94, 064620 (2016) E* MeV -20246810 Coun s / 300keV 0 20 40 60 80 100 120 140 160 E* MeV -4 -2 0 2 4 6 8 10 Coun s / 300keV 0 100 200 300 400 500 600 (a) (b) ( ( ) ) (s ) FIG. 4. Exci a ion ene gy spec um o (a) he g ound s a e and (b) unbound exci ed s a es o 11Be deduced om he sca e ed deu e ons in coincidence wi h 11Be and 10Be, espec i ely. The backg ound con ibu ions a ising om 12Cand (CH2)nha e been sub ac ed. The dashed cu e in (b) wi h he e ical axis on he igh -hand side s ands o he solid angle o TELE1. o he solid angle o TELE1 as a unc ion o exci a ion ene gy (Eex) we e pe o med wi h he GEANT4 package, and he esul s a e shown by he dashed line in Fig. 4(b) wi h he e ical axis on he igh -hand side. The solid angle emains nea ly a cons an om Eex =0–4.5 MeV, and dec eases abou 10% om Eex =4.5–5.5 MeV. Fo Eex >5.5 MeV, he solid angle dec eases quickly, so he b eakup c oss sec ions we e no ex ac ed. The di e en ial c oss sec ions o he 11Be +delas ic sca e ing, as a a io o he Ru he o d c oss sec ions, a e displayed in Fig. 5. The angula dis ibu ions o b eakup c oss sec ions o he exci a ion ene gy in e als o 0.5<E ex < 3.0 MeV and 3.0<E ex <5.5 MeV a e displayed in Figs. 7(a) and 7(b), espec i ely. The e o ba s a e pu ely s a is ics only aking in o conside a ion he backg ound sub ac ion o ca bon and p o on con amina ions in he (CD2)n a ge . The sys ema ic e o is less han 10%, a ising om he unce ain ies in solid angles (5%), he hickness o he a ge (2%), he cu s on he h eshold and he pa icle iden i ica ion spec um measu ed by TELE0 (4%), and he cu s applied on he exci a ion ene gy spec a (5%). To moni o he possible deu e on leakage om he (CD2)nplas ic a ge , we checked he de ec ed numbe o ecoil deu e ons a he beginning and close o he end o FIG. 5. Compa isons be ween he expe imen al di e en ial c oss sec ions (as a a io o Ru he o d) and op ical model calcula ions o he 11Be +delas ic sca e ing a 26.9AMeV. The do -dashed, do ed, as well as dashed and solid cu es ep esen he calcula ions wi h op ical po en ials o DA1p, Daehnick e al. [24], as well as he olding po en ial gene a ed wi h he JLM nucleon-nucleon in e ac ion, wi h ene gy-dependence pa ame e s o se I and se II, espec i ely. he expe imen , espec i ely, o he same numbe o inciden pa icles and he same a ge se up, and ound a change o less han 2.0%. This de ia ion is wi hin he s a is ical unce ain y. The e o e, he change o C/D a io in he a ge is negligible o he p esen expe imen . III. PHENOMENOLOGICAL OPTICAL MODEL ANALYSIS In his sec ion, he measu ed elas ic sca e ing angula dis ibu ion is analyzed in he amewo k o he op ical model (OM). The e exis in he li e a u e se e al global deu e on op ical model po en ials o deu e on sca e ing, such as ha ob ained om he comp ehensi e analysis o Daehnick e al. [24]. Howe e , p e ious analyses ha e e idenced ha hese pa ame iza ions ail o p ope ly desc ibe he da a when ex apola ed ou side hei ini ial domain o alidi y, pa icula ly o ligh a ge s and a la ge sca e ing angles [25– 27]. Fo his eason, a new global deu e on po en ial, called DA1p [28], was ecen ly de eloped, based on 67 se s o expe imen al da a o deu e on elas ic sca e ing om 1p-shell nuclei wi h inciden ene gies be ween 5.25 and 170 MeV. This global po en ial is employed o he p esen da a. A single- olding model (SFM) analysis was also pe o med o he elas ic sca e ing da a using he Lane-consis en B uy` e es Jeukenne-Lejeune-Mahaux (JLM) model nucleon- nucleon in e ac ion. Two se s o ene gy-dependen pa ame e s, designa ed as JLM Se I [29] and JLM Se II [30], we e applied. The nucleon densi y dis ibu ion o 11Be was calcula ed wi h he Ha ee-Fock me hod using he SkX in e ac ion [31]. The calcula ions om he JLM model, oge he wi h hose om he sys ema ic op ical po en ials o DA1p and Daehnick e al., a e compa ed wi h he expe imen al angula dis ibu ions in Fig. 5. 064620-4 ELASTIC SCATTERING AND BREAKUP OF 11Be ON . . . PHYSICAL REVIEW C 94, 064620 (2016) AsshowninFig.5, he calcula ions wi h he DA1p po en ial and he olding po en ial gene a ed wi h bo h JLM po en ials show easonable ag eemen wi h he expe imen al di e en ial c oss sec ions. By con as , he calcula ion wi h he Daehnick e al. po en ial o e es ima es he da a. This migh indica e ha he elas ic sca e ing o deu e ons on he weakly bound nuclei could be ep oduced by he OM wi h po en ials specially de eloped o he co esponding inciden ene gy and mass egion, o by he SFM including he densi y o weak-binding nuclei. IV. XCDCC CALCULATIONS In his sec ion we compa e he measu ed elas ic and b eakup c oss sec ions wi h XCDCC calcula ions [12,15]. The XCDCC me hod is a gene aliza ion o he s anda d con inuum- disc e ized coupled-channels (CDCC) o malism which akes in o accoun he e ec s o co e exci a ion in he s uc u e o he p ojec ile, by including co e-exci ed componen s in he p ojec ile s a es, and also in he dynamics o he eac ion, by allowing co e exci a ions and deexci a ions du ing he collision. In he p esen wo k, his is done by including explici ly he de o ma ion o he 10Be co e, wi hin a collec i e model. The 11Be s uc u e is desc ibed by he pa icle- o o model using he Hamil onian o Re . [32] (model Be12-b), comp ised o cen al and spin-o bi pa s, wi h he usual Woods-Saxon olume and de i a i e shapes, espec i ely. The cen al pa has a ixed geome y (R0=2.483 m, a=0.65 m) and a pa i y- dependen s eng h (Vc=−54.24 MeV and −49.67 MeV, o posi i e and nega i e pa i y s a es, espec i ely). The spin-o bi pa uses he same adius and di useness as he cen al pa and a ixed s eng h Vso =8.5 MeV. Fo he 10Be co e, his model assumes a pe manen quad upole de o ma ion β2=0.67, (i.e., δ2=β2R0=1.664 m). This model ep oduces he sepa a ion ene gies o he wo bound s a es o 11Be as well as he posi ions o he low-lying na ow 5/2+and 3/2+ esonances. To calcula e he ene gies and wa e unc ions o 11Be we use a pseudos a e (PS) me hod [15], which consis s in diagonaliz- ing he Hamil onian o his composi e sys em in a con enien basis o squa e-in eg able unc ions. In his wo k, we use he ans o med ha monic oscilla o (THO) basis, which is ob ained by applica ion o a local scaled ans o ma ion (LST) o he adi ional ha monic oscilla o (HO) basis. The pu pose o he LST is o ans o m he Gaussian asymp o ic beha io in o an exponen ial o m, which is mo e con enien o he desc ip ion o he bound s a es o he sys em. In pa icula , we use he analy ical LST p oposed in Re . [33], which was al eady applied o 11Be in Re s. [15,16,34], and he pa ame e s used in he p esen calcula ions a e simila o hose employed in hose e e ences. The size o he basis is de e mined by he numbe o oscilla o unc ions (N), he maximum o bi al angula momen um o he co e- alence mo ion (), and he numbe o co e s a es. In he p esen calcula ions we use N=12 and max =3 and he i s wo s a es o he co e ( he g.s. and he i s exci ed s a e). Con inuum s a es wi h o al angula momen um Jπ p=1/2±,3/2±, and 5/2+we e conside ed in he calcula ions. We e i ied ha using a la ge alue o No highe alues o Jpdid no change app eciably he calcula ed obse ables. Fu he mo e, only eigen alues wi h ene gies below 7 MeV we e e ained in he coupled-channels calcula ions, since he e ec o highe eigen alues was ound o be negligible. The XCDCC calcula ions equi e also he alence- a ge and co e- a ge in e ac ions. In XCDCC, he co e- a ge in e - ac ion (10Be +din he p esen case) con ains noncen al e ms which a e esponsible o he dynamic co e exci a ion (DCX) mechanism o he co e du ing he collision. To gene a e his po en ial, we s a om he DA1p pa ame iza ion in oduced in he p e ious sec ions. This po en ial is de o med wi h a quad upole de o ma ion leng h o δ2=1.9 m, and expanded in mul ipoles, e aining he monopole and quad upole e ms. The la e one accoun s o he diagonal 2+→2+and o - diagonal 0+→2+coupling po en ials among he conside ed 10Be s a es. To a oid double coun ing o he 10Be exci a ion, all pa ame e s a e sligh ly adjus ed in o de o eco e he o iginal desc ip ion o he 10Be +delas ic sca e ing da a. In pa ame izing he n+dpo en ial one has o deal wi h he complica ions a ising om he p esence o angula -momen um and spin-dependen e ms, including enso o ces. Cu en implemen a ions o he CDCC and XCDCC me hods do no allow o hese kinds o in e ac ion, so we jus de i e a simple cen al n+dpo en ial ep oducing some key ea u es o his sys em. Fo ha , wo di e en p esc ip ions a e used in his wo k. In ou i s p esc ip ion, he n+dpo en ial is calcula ed as he olding o n+pand n+npo en ials wi h he g ound s a e o he deu e on. Fo ha , he n+pand n+nin e ac ions we e desc ibed wi h he po en ials o Man lie and Tjon [35]. In ou second p esc ip ion, we pa ame ize he n+din e ac ion using he simple Gaussian o m Und ( )=VGexp[−( /a )2]+iWGexp[−( /aw)2],(2) wi h ou pa ame e s VG,WG,a , and awadjus ed o ep oduce he expe imen al elas ic sca e ing and eac ion c oss sec ions o his sys em a En=27.5MeV[36]. The di e ences be ween he 11Be +dobse ables calcula ed wi h hese wo p esc ip ions will p o ide us wi h an idea o he sensi i i y o hese obse ables on he choice o he n+din e ac ion. The compu a ion o he coupling po en ials en e ing he XCDCC coupled equa ions and he esolu ion o hese equa ions we e done employing he o malism and codes de eloped in Re . [15]. The calcula ed di e en ial c oss sec ions o he 11Be +d elas ic sca e ing a e compa ed wi h he expe imen al da a in Fig. 6. The solid and dashed lines a e he ull XCDCC cal- cula ions wi h he wo p esc ip ions o he n+din e ac ion, as indica ed by he labels. We ind a good ag eemen wi h he da a o c.m. angles up o 30◦, and an unde es ima ion beyond his angle. Fu he mo e, we see ha he wo p esc ip ions o he n+din e ac ion lead o simila esul s, and hei di e ences canno explain he obse ed disc epancy wi h he da a a he la ges angles. We also include in his igu e he XCDCC calcula ion omi ing he DCX mechanism (do ed line). The sizable di e ence be ween his calcula ion and he ull calcula ion a la ge c.m. angles indica es ha he DCX has a clea impac on he elas ic sca e ing c oss sec ions o his eac ion. 064620-5 J. CHEN e al. PHYSICAL REVIEW C 94, 064620 (2016) FIG. 6. Expe imen al and calcula ed elas ic di e en ial c oss sec ions, a io o Ru he o d, o he eac ion 11Be +da 26.9AMeV. FIG. 7. Expe imen al and calcula ed b eakup c oss sec ions, as a unc ion o he c.m. sca e ing angle, o he eac ion 11Be +da 26.9AMeV. The meaning o he lines is he same as in Fig. 6.The inse in (a) ampli ies he egion con aining he expe imen al da a. FIG. 8. Ene gy di e en ial c oss sec ion, as a unc ion o he n-10Be ela i e ene gy, calcula ed wi h he XCDCC me hod. The solid line is he ull XCDCC calcula ion, whe eas he dashed line is he calcula ion omi ing he 10Be +dexci a ion mechanism. The a ow indica es he exci a ion ene gy o he n+10Be(2+) h eshold. The co esponding b eakup angula dis ibu ions a e com- pa ed wi h he expe imen al da a in Fig. 7. The op and bo om panels co espond o he exci a ion ene gy in e als Ex=0.5–3.0 MeV and Ex=3.0–5.5 MeV o 11Be. The meaning o he igu es is he same as in Fig. 6. We obse e ha he wo p esc ip ions o he n+dpo en ial lead o e y simila esul s, pa icula ly a he measu ed angles. I becomes also appa en ha he maximum o he b eakup c oss sec ion occu s a θc.m.≈10◦, which is ou side he ange o he measu ed da a. Consequen ly, he conclusions on he compa ison o he calcula ed and measu ed b eakup da a mus be aken wi h he same cau ion because hey a e based on a egion whe e he b eakup c oss sec ion is ela i ely small and s uc u eless. No wi hs anding hese conside a ions, one can see ha he ag eemen be ween he calcula ions and he da a is e y easonable. Mo e in e es ing is he e ec o he DCX mechanism, which can be in e ed om he compa ison o he ull XCDCC calcula ion wi h ha omi ing his e ec (do ed line). I is clea ly seen ha he omission o he DCX gi es signi ican ly ewe b eakup c oss sec ions. The e ec is pa icula y no iceable o he highe ene gy in e al [Fig. 7(b)], o which he calcula ion igno ing he DCX mechanism clea ly unde es ima es he da a. These e ec s a e quali a i ely simila o hose ound o he p+11Be eac ions a 63.7AMeV [15] and 26.9 MeV [16]. This ein o ces he idea ha he impo ance o dynamic co e exci a ions is a gene al ea u e o 11Be sca e ing on ligh a ge s. To ge u he insigh in o hese esul s we in es iga ed he b eakup c oss sec ions as a unc ion o he ela i e ene gy (E el)o he11Be sys em, wi h espec o he n+10Be (g.s.) b eakup h eshold. This is shown in Fig. 8. No e ha he XCDCC me hod p o ides only a disc e e b eakup dis ibu ion, co esponding o he b eakup c oss sec ion o each inal pseudos a e. To ob ain a con inuous dis ibu ion, we con olu e 064620-6 ELASTIC SCATTERING AND BREAKUP OF 11Be ON . . . PHYSICAL REVIEW C 94, 064620 (2016) his disc e e dis ibu ion wi h he 11Be con inuum (sca e ing) s a es [37]. The solid line is he esul o such a con olu ion o he ull XCDCC calcula ion. One can see e y clea ly he wo na ow peaks a E el ≃1.15 MeV and E el ≃3MeV, which co espond espec i ely o he low-lying 5/2+and 3/2+ esonances. Also no iceable is he sudden inc ease o he c oss sec ion when he exci a ion ene gy c osses he h eshold n+10Be(2+). Fo exci a ion ene gies abo e his h eshold, he sys em can decay ei he o he 10Be g.s. o o i s i s exci ed s a e (2+). We include also in his igu e he calcula ion omi ing he DCX mechanism (dashed line). The sizable educ ion o he c oss sec ion is appa en , pa icula ly in he egion o he 3/2+ esonance, as we obse ed o he co esponding angula dis ibu ions. These esul s show e y clea ly he key impo ance o he DCX mechanism in he 11Be +d eac ion. V. SUMMARY We measu ed he elas ic sca e ing and b eakup eac ion o 11Be on deu e ons o he i s ime a an inciden ene gy o 26.9AMeV. The p o on con amina ion in he (CD2)n a ge was de e mined by compa ing he p o on elas ic sca e ing da a o 11Be on he (CD2)nand (CH2)n a ge s. The measu ed elas ic sca e ing da a we e compa ed wi h se e al op ical model calcula ions. We ound ha he da a a e well desc ibed wi h a ecen ly de eloped deu e on po en ial o 1p-shell nuclei (named DA1p), as well as wi h single- olding po en ials gene a ed wi h he JLM nucleon- nucleon in e ac ion. On he con a y, he global deu e on po en ial o Daehnick e al. ailed o ep oduce he da a sa is ac o ily. An ex ended e sion o he XCDCC me hod, which includes he DCX e ec s, was also applied o analyze he elas ic and b eakup da a o 11Be +d. In he case o he elas ic sca e ing, he ull XCDCC calcula ions including he DCX mechanism easonably ep oduced he expe imen al c oss sec ions. Fo he b eakup eac ion, he ull XCDCC calcu- la ions signi ican ly inc ease he calcula ed c oss sec ions and signi ican ly imp o e he desc ip ion o he expe imen al da a wi h espec o he calcula ed esul s omi ing DCX e ec s. The DCX e ec is pa icula ly no iceable o he highe exci a ion ene gy in e al (Ex=3–5.5 MeV), o which he calcula ion igno ing he DCX mechanism clea ly unde es ima es he da a. These esul s con i m he ele ance o he DCX e ec s in he sca e ing o weakly bound de o med sys ems on ligh a ge s. ACKNOWLEDGMENTS We g a e ully acknowledge he s a o he RCNP accel- e a o g oup o p o iding he 13Cp ima y beam and he s a o EN-cou se o assis ance and local suppo . 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