Nuclear densities et excitations of exotic nuclei via

Nuclear densities et excitations of exotic nuclei via direct reactions ACTIVITIES AND PERSPECTIVES Structure studies at the drip-lines : exemples, + exp-theory GOAL: extension of systematics of neutron rms radius and of neutron excitation n , p along isotopic chains Probe the structure & spectroscopy at large isospin Measure unbound states detection devices NEED FOR AN IMPROVED THEORETICAL FRAMEWORK OF STRUCTURE AND REACTIONS Neutron-skin structure and shell evolution of weakly-bound neutron-rich SPIRAL/ SPIRAL 2/ SPIRAL 2 EURISOL nuclei in coupled-reaction channel studies Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Nuclear structure towards the drip-lines : phenomena to explore & to understand Evolution of structure at large isospin ? Drip-lines: limit of nuclear binding, large isospin Exploration: new exotic structures neutron-skin Tests: nuclear modelling & interactions VNN(Tz) Neutron skins Change in shell structure New magic numbers Local properties (N, Z) halo, clusters Neutron skin halo 6 He 4 He Direct reactions to unbound states 8 He Weakly bound states ? Continuum coupling ? Isospin dependence ? 2008: what do we know? 2016: future explorations 4 He ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

2008 Nuclear landscape towards the drip-lines 31 F 24 8 Z 23 6 12 22 19 4 11 Li 2 H 6 He t 2 4 6 8 He N C B Be 14 Be 4 He p d n O Li He borromean N 8 10 12 14 16 Very few drip-line nuclei have their identity card complete Masses, size, densities, neutron excitation, low-lying spectroscopy, shell structure 6 He Drip-line : 8 He neutron-skin SPIRAL 8 He (T 1/2= 119 ms) I= 104 /s ; E=15. 7 A. Me. V reaction target CH 2

SPh. N activities on structure of exotic nuclei via direct reactions Objectives : - evolution of nuclear structure at large N/Z nuclear correlations, p-n interaction -exploration of new phenomena -- tests of the validity of the models Shell structure far from the valley of stability Z Method : direct reactions induced by radioactive beams N GANIL/SPIRAL ; SPIRAL 2 in 2012 6 He halo and neutron-skin 8 He Detector of Charged particles Si-strips, Cs. I x-y-E-DE-TOF Beam detector CATS-BTD SEDI-SPh. N Direct reactions to unbound states MUST 2 Collaboration: DAPNIA, GANIL and IPN-Orsay ESNT 4 -6 Fev. 08 m a be target Experimental Devices CEA-SPh. N 10 cm vlapoux@cea. fr

Light nuclei and three-body forces S. Pieper et al. Nucl Phys. A 751(2005), 516 c PRC 70 (2004) 54325 Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Structure of 8 He extracted from direct reactions on proton target SPIRAL 8 He +p @ 15. 7 A. Me. V 8 He(p, d) F. Skaza Ph. D SPh. N F. Skaza, N. Keeley, VL et al. , PLB 619. 82 (’ 05) N. Keeley et al. , PLB 646, 222(’ 07) 8 He(p, t)6 He(0+) 8 He(p, p) CRC calc Coupled-channel calc. : N. Keeley (SPh. N) 8 He(p, t)6 He(2+) Structure of ground state & search for unbound excited states spectroscopy of light charged particles p, d, t (MUST) measurements of resonances in 8 He NPA 788 c, 260 (’ 07) angular distributions ; analysis in coupled reaction channels PLB 619. 82 (’ 05) ; 646, 222 (’ 07) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Structure of 8 He extracted from direct reactions on proton target CRC Coupled-reaction channel analysis: N. Keeley (SPh. N, Inst. A. Soltan) 8 He(p, d) 8 He(p, t)6 He(0+) [2] (p, t) wf. of 8 He%6 He [8 He/6 He(0+)] =1 ; [8 He/6 He(2+)] =0. 014 8 He(p, t)6 He(0+) RIKEN 61. 3 A. Me. V 8 He(p, t)6 He [1] 8 He(p, d)7 He C 2 S = 4. 4 ± 1. 3 [CCBAanalysis] CRC (p, p) (p, d) C 2 S = 3. 3 ± 1. 3 PLB 619, 82 (’ 05) (2+) 8 He(p, t)6 He 2+ CRC calc Consistent with results from quasi-free scattering of 8 He measured at GSI, LV Chulkov et al, NPA 759, 43(’ 05) p n CRC calc Data: A. A. Korsheninnikov et al, PRL 90, 082501 (‘ 03) p Data: SPIRAL-MUST [1] F. Skaza et al. , PRC 73, 044301(’ 07) [2] N. Keeley et al, PLB 646, 222(‘ 07) Direct reactions to unbound states ESNT 4 -6 Fev. 08 n 1 p 1/2 1 p 3/2 1 s 1/2 Configuration mixing : (p 3/2)4 and (p 3/2)2 (p 1/2)2 CEA-SPh. N vlapoux@cea. fr

Spectroscopy of 8 He : exp versus theory p n 1 p 1/2 1 p 3/2 1 s 1/2 COSMA model +4 n M. Zhukov et al. PRC 50, 1(‘ 94) experiments theories (p, p’) [Kor 93] [0 er 95] [Nil 95] [Boh 99] [Mar 01] [Kor 93] A. A. Korsheninnikov et al. , PLB 316 (‘ 93) 38 [Wir 02] R. B. Wiringa & S. C Pieper, [Oer 95] W von Oertzen et al. , NPA 588 (‘ 95) 129 PRL 89 (‘ 02) 182501 [Nil 95] T. Nilsson et al. , NPA 583 (‘ 95) 795 [Boh 99] H. G. Bohlen et al. , Prog. Part. Nucl. Phys. 42 (‘ 99) 17 [Mar 01] K. Markenroth et al. , NPA 679 (‘ 01) 462 Direct reactions to unbound states [Nav 04] P. Navratil & B. R. Barrett, PRC 57 (‘ 98) 3119 ESNT 4 -6 Fev. 08 +private co. CEA-SPh. N vlapoux@cea. fr

Spectroscopy of 8 He : exp versus theory E(Me. V) 2+ 3. 62 ± 0. 14 ? 5. 4 ± 0. 5 SPIRAL (p, p’) Γ (Me. V) 0. 3 ± 0. 2 0. 5 ± 0. 3 And the specific treatment of resonant states ? Wigner : « Beautiful theories have to face ugly facts » experiments theories (p, p’) [Kor 93] [0 er 95] [Nil 95] [Bohl 99] [Mark 01] Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Spectroscopy of 8 He : exp versus theory P. Navrátil & B. R. Barrett, PRC 57, 3119 (‘ 98). “The 8 He nucleus is a weakly bound system, where scattering to the continuum will play an important role in the structure of higher-lying states. ” Gamow Shell Model (GSM): consistent description of bound states and the particle continuum (resonances and the non-resonant scattering background). N. Michel et al. , PRL 89, 042502 (‘ 02) PRC 67, 054311 (‘ 03) The gs is bound by CC correlations Continuum Shell Model (CSM): Discrete and Continuum Spectra in the Unified Shell Model Approach, A. Volya & V. Zelevinsky, PRL 94, 052501 (‘ 05) Direct reactions to unbound states [QMC] [NCSM] [GSM] [CSM] ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

n , p (p, p’) Conclusion s Test of the validity of 8 He gs densities using (p, p) : neutron-skin features close to NCSM densities COSMA not valid Rms (fm) 8 He Alpha + 4 n Proton Neutron Matter COSMA 5 -body 1. 69 2. 74 2. 52 HF+corr Sagawa 1. 95 2. 67 2. 51 NCSM, Navrátil 2. 00 2. 59 2. 46 NCSM No core Shell model NCSM (No Core Shell Model) (V 3 eff 4 hw, 13 Me. V ) COSMA: Alpha+4 n Validation of no-core shell model calculations (NCSM) for gs (p, p’) mainly sensitive to the neutron excitation ; Transition densities 2+ 0+ : NCSM calc. overestimate the p & n excitations Test of transition densities ; Analysis in progress CRC (p, p’) Coupling with the (p, t) NEUTRON-SKIN THICKNESS: ~ 0. 6 +/- 0. 05 fm Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Participants of the experiment 8 He(p, p’) CEA-SACLAY DSM/DAPNIA/SPh. N : N. Alamanos, F. Auger, A. Drouart, A. Gillibert, V. Lapoux, L. Nalpas, E. Pollacco, R. Raabe, J-L. Sida, F. SKAZA (Ph. D). IPN-Orsay : D. Beaumel, Y. Blumenfeld, F. Delaunay, E. Becheva, J-A. Scarpaci Ganil : L. Giot, P. Roussel-Chomaz FLNR - Dubna : S. Stepantsov, R. Wolski University of Ioannina : A. Pakou ANALYSIS : Microscopic densities P. Navrátil + interaction Argonne H. Sagawa HF +correlations Futur : cf M. Ploszajczak Ganil JLM potential: code Dietrich (Livermore) ; form factors (home made, VL) + CRC calc. N. KEELEY With the Fresco code (IJ Thompson, Surrey Univ). CEA DAPNIA, GANIL, IPN-Orsay • DAPNIA SEDI E. Atkin, P. Baron, F. Druillole, F. Lugiez, B. Paul, M. Rouger ; • SPh. N : A. Drouart, A. Gillibert, V. Lapoux, L. Nalpas, E. Pollacco • IPN-Orsay SED: P. Edelbruck, L Lavergne, L. Leterrier, A. Richard, M. Vilmay, E. Wanlin, • Structure Y. Blumenfeld, D. Beaumel, E. Becheva • GANIL GIP M. Boujrad, L. Olivier, B. Raine, F. Saillant M. Tripon, Physics P. Roussel Chomaz Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Collaboration Structure & spectroscopy of exotic nuclei 6 He low-lying spectroscopy via 8 He(p, t)6 He DAPNIA/SPh. N : N. Alamanos, F. Auger, A. Drouart, A. Gillibert, N. Keeley, V. Lapoux, X. Mougeot (TH), L. Nalpas, E. Pollacco, C. Simenel IPN-Orsay : D. Beaumel, Y. Blumenfeld, J. Guillot, J-A. Scarpaci Visiteurs à Orsay : H. Iwasaki, D. Suzuki GANIL : P. Roussel-Chomaz, C. Force, L. Gaudefroy, T. Kalanee, T. Roger A. Soltan, Varsovie : K. Rusek, I. Strojek FLNR - Dubna : R. Wolski University of Ioannina : A. Pakou, T. Mermizedakis Technical and software support: ASIC DAPNIA/SEDI E. Atkin, P. Baron, F. Druillole, F. Lugiez, B. Paul, M. Rouger Technical and software support: SPEG P. Gangnant, JF Libin Ganil, services techniques J. Cacitti, G. Fremont, C. Spitaels GIA ex GIP : C. Houaner, G. Leberthe, L. Légeard, L. Olivier, M. Tripon, B. Raine, F. Saillant Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Near future projects plans Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

MUST 2 MUr à STrips 2, new generation of MUST MEASUREMENTS AND ANALYSIS OF REACTIONS IN COUPLED- CHANNELS 2004 -6 MUST 2 Si(Li) 4. 5 mm collaboration : CEA-DAPNIA, GANIL, IPN-Orsay Developed by : Ø DAPNIA/SEDI : µ-electronics R&D ASIC Ø GANIL ØIPN Orsay Si strips 300 m DE 2 100 x 100 mm X, Y , T, E 128 X 128 Y Cs. I 3 cm 4 x 4 segments Increased compacity due to the ASIC technology (Application Specific Integrated Circuit) coïncidences particle - MUST 1 MUST 2: improvments Ø factor 3 in active area Ø smaller volume of PAmp : x 6 Ø better time resolution 100 collaboration MUST 2: SPIRAL + Futur SPIRAL 2 mm Exotic shapes and resonances One-particle state Spectroscopic factors Evolution of neutron excitation Mn vs N along isotopic chains MUST 2 Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

States between 2 and 10 Me. V ? Spectroscopy of 6 He Positions 2+2, 0+2 VNN +VNNN Correlations in light neutron-rich nuclei THEORIES 0+ 6 1+ 2+ ~5 0+ 2 8. 54 1+ 6. 50 2+ 2 5. 79 0+ 2 5 1+ 4. 5 4. 3 2+ 2 G (2+2) = 1. 2 2+ 2+ 2. 53 1. 8 0+ Pieper et al. NN+NNN IL 2 PRC 70, 054325(’ 04) Direct reactions to unbound states 2+ 0+ Navratil et al. No Core shell Model 10 hw V 2 eff ESNT 4 -6 Fev. 08 1. 8 0+ Danilin et al. Few-Body model PRC 55, 577 (’ 97) CEA-SPh. N vlapoux@cea. fr

Experimental set-up with MUST 2 Identification A, Z : SPEG SISSI-SPIRAL Beams 8 He, 20, 22 O, 14 O I = 104 - 105 /s CH 2 target 1 mg/cm 2 CATS 2 p, d, t CATS 1 MUST 2 @ d=15 cm 5 -25 deg lab (15 -80 c. m. ) Sect. Eff (p, t) ~ 5 10 -3 – 0. 5 mb/sr CATS 2 Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Structure of exotic nucleiparticle via direct Transfer reactions ; coupling between andreactions gamma spectroscopy Charged-particle spectroscopy Thin target CH 2 , CD 2 1 mg/cm 2 Complete kinematical reconstruction access to bound and unbound states I (> 5. 103/s) ex : SPIRAL 2 96 Kr @ 10 Me. V/n I= 104 /s 96 Kr(d, p)97 Kr, (d, d’) (d, t) EURISOL n-rich Ne, Ca, Ni, Kr, Sn @ 20 -50 Me. V/n I > 105 /s AZ(d, p)A+1 Z Beam tracking BTD p AZ CD 2 (d, p ) Gamma detection Identification : VAMOS Particle-spectroscopy (d, p ) Ex: MUST 2 -like array VAMOS A+1 Z (d, p ) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

2008 Nuclear landscape towards the drip-lines 18 Next drip-line nuclei ? Z 07 : 125 Pd (Z=46) found at RIBF 16 43 Si 44 Si 14 12 33 Na 10 38 Mg 39 34 Mg 4 He 30, 31, 32 Ne 36 33 34 Ne 23 N 22 C 16 structure of 24 O ? Drip-line 24 O 40 Mg 37 Na 31 F 8 Low-lying resonances ? Neutron skin ? Neutron excitation ? Density Profiles ? New shell effects ? Tarasov 97 Sakurai PLB 448, (99) Notani PLB 542 (02), Lukyanov 02 Tarasov PRC 75 (’ 07) Complete the Identity card of drip-line nuclei N 18 20 22 24 26 28 30

Shell effects far away from stability with new generations of RIB s systematics of neutron excitations vs N Search for new magic numbers neutrons stability p 3/2 f 7/2 fp sd-fp 20 sd d 3/2 s 1/2 d 5/2 8 p 1/2 p 3/2 s 1/2 82 (f 7/2) (1 h 11/2 -)12 drip-line N = 16, Z=8, neutrons p 3/2 f 7/2 d 3/2 fp sd-fp N = 20 24 O sd 16 s 1/2 N = 16 Z=14 30 Si d 5/2 N=8 N = 16 N = 14 22 O N=8 N=16 Learnt from 1 st generation of RIBs Local properties (Z, N) N=34, 40, 70 instead of N=50, 82 ? RIBF, SPIRAL 2 EURISOL Extension of the systematics of neutron excitation along isotopic chains Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Spectroscopy of unbound states in neutron-rich beams close to the drip-lines Which beams ? We want to gain in exoticity Complete the (p, p’) chains O (24 O), Ne + Mg, Si, S, Ar +spectroscopy of neutron-rich nuclei: around doubly magic Z=28, N=40, 50 ; Z=50, N=82 around N=28, N=40 (possible new magic), N=50, N=70 (new) Examples : 34 Ne , 38 Ne (if not unbound), 60 -70 Ca, 104 Se (Z=34, N=70) Z L O S I R U E E L O S I R U If the beams are new (36 Ne ? 60 -68 Ca ? ) or rare at present (24 O few/s at GANIL, RIKEN) with EURISOL : counting rates less or around 103 -105 /s N

Letter of Intent for SPIRAL 2 o Single-particle structure o Nuclear pairing o Spectroscopy of very-neutron rich nuclei o Cluster studies o Direct reaction mechanisms o Applications to astrophysics cf LOI r process nucleosynthesis Cf GENERAL LOI : Direct Reactions Studies of Exotic Nuclear Structure E (Me. V) ? Sn () LOI-16 unbound states in n-rich nuclei SPECTROSCOPY of bound and unbound states Transfer (d, p) & (p, d) Elastic & Inelastic scattering (p, p’) (d, d’) - Experimental conditions and requirements: BEAM, DETECTION, THEORY - SPECIFICITY Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Going closer to driplines with higher intensities : opened physics fields Exotic shapes and resonances Skin and halos Soft collective modes One-particle state Spectroscopic factors Z Alpha-clusters states Evolution of neutron excitation Mn vs N along isotopic chains 2012+ N 2020+ Far. . far away e. g. Ni, 30 Zn, 34 Se, 36 Kr, Sn Beams Variety A, Z Limit of nuclear binding, I Me. V Sn -Exc spectra, density distributions via (p, p’) - Shell structure, s. p states, J via nucleon-transfer (p, p’), (p, d) (p, t) (d, d’) (d, p) (d, t) Unbound states 5 4 3 2 1 94 -96 Zn - Prénom Nom - [Titre de la présentation] 94 -96 Kr 96 -98 Sr ("pied de page" et "date" -> onglet menu Affichage/En-tête) 134 -136 Sn

Low-lying spectroscopy of n-rich Kr isotopes neutrons (g 7/2) 50 (1 g 9/2)10 Neutron excitation of 96 Kr via (p, p’) and shell structure of 97 Kr via 96 Kr(d, p) Bound and unbound states full reconstruction of the kinematics (p, p’) or (d, p) excitation spectrum +Spectroscopic factors (2 p 1/2) (1 f 5/2) S 2 n E (Me. V) 8. 03# 2+ , 4+, 6+ ? ? 6+ ? Sn 4+ ? 2 0 Q-value ? 4 Sn 2. 96# 2+ ? 1/2(-) gs 94 Kr(d, p) 95 ISPIRAL 2 8 ? Sn 5. 06# 2. 97# S 2 n 8. 02# 0. 78 s Kr (7/2 -) ? 0+ 95 Kr(d, p) 96 94 Kr I > 109 0. 75 Me. V Direct reactions to unbound states Kr 95 Kr I > 9. 108 2. 84 Me. V ESNT 4 -6 Fev. 08 96 Kr(d, p) 97 0 Kr 96 Kr I > 104 0. 74 Me. V CEA-SPh. N vlapoux@cea. fr

LOI “Unbound states” PREPARATION OF THE EXPERIMENTAL SET-UP BTD +particle-gamma coupling + Detection at the focal plane for (Z, A) identification CD 2 target exotic beam SPIRAL 2 -ray detector ide AZ nti beam tracking devices p icle part tion c dete A+1 Z fic ati on separation of excited states with high-density level cf LOI-direct Reactions Future 4 GASPARD array GAmma Spectroscopy & PArticle Detection simulation of exp set-up SP 2 Beams : larger incident energies required (cf L window & access to excited states) PREPARATION OF THEORETICAL FRAMEWORK EXOTIC Coupled-reaction channel analysis: - treatment of direct reactions for structure embedded in the continuum -proton-nucleus, deuteron-nucleus optical potentials -Microscopic form factors for (p, p’) reactions -Study of benchmark reactions Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Collaboration LOI SPIRAL 2 “Unbound states” CEA-SACLAY DSM/DAPNIA/SPh. N: N. Alamanos, F. Auger, R. Dayras, A. Drouart, A. Gillibert, N. Keeley, V. Lapoux, L. Nalpas, E. Pollacco, C. Simenel, X. Mougeot. IPN-Orsay : D. Beaumel, S. Fortier, F. Hammache, E. Khan, C. Petrache GANIL: L. Gaudefroy, W. Mittig, F. de Oliveira, P. Roussel-Chomaz, H. Savajols, O. Sorlin HMI Berlin, Germany: H. G. Bohlen, Tz. Kokolova, W. Von Oertzen, C. Wheldon JINR, FLNR Dubna, Russia: A. Fomichev, M. S. Golovkov , A. Rodin, S. Sidorchuk, S. Stepantsov, G. Ter-Akopian, R. Wolski IKS University of Leuven, Belgium: R. Raabe IPHC Université Louis Pasteur, Strasbourg: Ch. Beck, S. Courtin, A. Khouaja INFN-Catania, Italy: A. Musumarra KVI, Netherlands: M. N. Harakeh, H. G. Wortche Florida State University, US: K. Kemper University of Huelva, Spain: I. Martel University of Ioannina, Greece: : T. J. Merzimekis, A. Pakou, D. Roubos University of Santiago de Compostela, Spain: M. D Cortina-Gil Theoretical support : CEA-Bruyères-le-Châtel DAM/DIF/SPN: E. Bauge, P. Chau Huu-Tai, J. P. Delaroche, H. Goutte, S. Péru CENBG: M. Bender IPN-Lyon: K. Bennaceur IST, Lisboa, Portugal: R. Crespo The A. Soltan Institute for Nuclear Studies, Hoza, Warsaw, Poland: K. Rusek NSCL, MSU, USA: T. Duguet University of Pisa-INFN-Pisa: G. Blanchon, A. Bonnacorso The Open University, UK: R. S. Mackintosh University of Sevilla, Spain: A. M. Moro VAEC Hanoï, Vietnam: Dao. T. Khoa; INST Hanoï: Hoang S. Than Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

ANALYSIS OF (D, P) CROSS SECTIONS. . . Once upon a time… Successful analysis for the stable nuclei [cf 40 Ca(d, p) ]: E=7, 8, 9, 10, 11, 12 Me. V Lee, . . Schiffer, Satchler, Drisko, PR 136 4 B (’ 64) 40 Ca(d, p) 41 Ca a test of the validity of the DWBA R. Satchler Direct nuclear reactions, Clarendon Press, Oxford Univ Press 1983 « The DWBA was shown to be inappropriate for the analysis of (d, p) reactions some 30 years ago, due to the importance of the deuteron breakup channel. » Ex : N. Timofeyuk & RC Johnson, PRC 59, 1545 (‘ 99) : d break-up included within the adiabatic approach from Johnson & Soper Analysis of the 16 O(d, p)17 O, 10 Be(d, p)11 Be, and 11 Be(p, d)10 Be reactions. Comprehensive analysis method for (d, p) stripping reactions ; test calc. : 12 C(d, p)@ 25 Me. V 10 Be(d, p) @ 12 and 25 Me. V , N. Keeley, * N. Alamanos, and V. L, PRC 69, 064604 (‘ 04) We know that average properties & parameterizations are working for stable beams (~300 species) ONLY SMALL PART of all 2000 RIB, even more 3000 possible ones … MEASURE ELASTIC SCATTERING to estimate coupling effects (virtual coupling potential related to excited states, compound nucleus effects… needed for coupling scheme … MEASURE INELASTIC SCATTERING (d, d ’) (p, p ’) DO THE BEST POSSIBLE CALCULATIONS !!!! DWBA is a limited framework, turns out to be WRONG for strongly-coupled channels cf CRC calculations, CDCC: Nick Keeley’s lecture at ECOLE JOLIOT-CURIE ’ 07 les réactions nucléaires comme sonde de la structure Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

EURISOL : a new theoretical framework Probe for the structure : (p, p’) But flux shared between several reaction channels elastic and transfer reactions + competition between main reaction channels NEED TO DEFINE THE APPROPRIATE SCATTERING THEORY State of the art : Coupled reaction channel analysis explicit channel coupling +Microscopic potentials • • • Accurate data covering a large angular domain Elastic : entrance OM potential under control (p, p) Check role of continuum coupling Sensitivity to the detailed structure of exotic nuclei, Test unusual shape +unbound states Compare to models (SM, HFB, BCS+QRPA, AMD) FUTURE: Structure and reaction on the same footing Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

EURISOL : a new theoretical framework Data+ Virtual coupling potential for elastic scattering of 10, 11 Be on p V. L et al. , PLB 658, 198 (’ 08) Direct reactions to unbound states Strong pickup-coupling effect on p+11 Be elastic scattering N. Keeley and V. L PRC 77, 014605 (‘ 08) CRC calc : 11 Be(p, d)10 Be* pickup to the 5. 960 Me. V 1 and 6. 263 Me. V 2 - doublet of excited states in 10 Be ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Drip-line studies Drip-lines : limit of nuclear binding, large isospin Exploration : new structures of exotic nuclei Tests : nuclear modelling & interactions VNN(Tz) FIND NEW REGIONS OF INTEREST Nuclei with large matter extension (neutron-skin, superdeformation…) New shell gaps EXTENSION OF the systematics of neutron excitation along isotopic chains MEANS to Probe the structure & spectroscopy at large isospin Measure unbound states EXPLORATION: Spectroscopy of low-lying resonances, unbound states, neutron excitation, exotic excitation modes soft dipole resonance and transition densities Halo, skin features of weakly-bound exotic nuclei n , p local shell change : like N=16 (34, 70. . ) indicated by Ex(2+), B(E 2) S 2 n, and evolution of neutron excitation SIMPLE PROBE : (p, p’) combined to Coulex information direct reactions in inverse kinematics, missing mass method Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

spectroscopy of low-lying states of neutron-rich isotopes via ( p, p’), (p, d) (p, t), (d, p) Improvment of exp set-up + Theoretical framework Present (1 st generation) intensities : few part/s Needed : (at least) 103 -105 /s 34 Ne+p @ 25 A. Me. V Measurement to unbound states: Particle-spectroscopy Large enough intensities EURISOL Large angular coverage all reactions measured simultaneously Elastic and transfer Low particle threshold : small c. m. angles 40 c. m. t Possible to carry out full coupled-reaction channel analysis 20 c. m. d 10 c. m. p EXTRACT form factors from (p, p’) spectroscopic factors from (d, p) suitable range of beam energies for (p, p’) and (d, p) : E ~ 10 -30 Me. V/n In 2016+: new beams of neutron-rich Ne, Ca, Ni, Kr, Sn isotopes… Access to neutron-thickness evolution + change in shell structure Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Theoretical framework for the analysis of direct reactions PROTOTYPE-STUDY: 8 He(p, p’) & (p, d) : PLB 619, 82(’ 05) Usual framework: DWBA, not valid, need to operate with CRC The usual ingredients and models based on past studies for stable nuclei must be put into question A PRIORI How good (potential, framework) is really good for exotic beams ? Validity of optical potentials ? Examine the assumptions in the case of weakly-bound nuclei or for specific coupling (large spectroscopic factors, enhanced excitation etc. . ) To be checked by measuring carefully the elastic scattering , TESTING GROUND FOR THE INTERACTION POTENTIAL AND THE REACTION MODEL Enhanced effects in the case of weakly-bound exotic nuclei: Coupling to continuum, 3 -body, many-body correlations Shell structure embedded in the continuum Use the predictions of improved structure theories to take into account these effects and the isospin-dependence of the nuclear interaction Improved approach (best we can do today) COMPLEX MICROSCOPIC POTENTIALS to test the validity of nuclear density FORMALISM in COUPLED REACTION CHANNELS To include the coupling to excitations AND to reaction channels To be scheduled in 2008 ESNT Workshop STRUCTURE AND REACTIONS IN COUPLED REACTION CHANNELS Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Conclusions Perspectives E (Me. V) ? () Sn Structure and spectroscopy of exotic nuclei via direct reactions Powerful tool for the study of unbound states : DIRECT REACTIONS IN COUPLED CHANNELS PHYSICS OF THE PUZZLE AND OF THE INTERPLAY « MOSAÏQUE DES NOYAUX » , P. BONCHE, CEA-SPh. T Studies of exotic nuclei need to combine several probes & Require systematics along extended isotopic chains theorist Experimentalist observable GOALS Nuclear Models find new aspects de structure Structure Bound states weakly-bound exotic nuclei, new constraints for the nuclear models of structure and reaction modelling of strong interaction in the nucleus for extreme isospin cases test bench for the unification of the future models for structure and reaction with explicit contribution of the coupling effects Direct reactions to unbound states ESNT 4 -6 Fev. 08 Role of the coupling to the continuum Reactions Scattering states PCV Effective interaction NN Isospin dependence Role of coupling to continuum CEA-SPh. N Beyond mean-field role of many-body correlations pairing vlapoux@cea. fr

Discussions - Questions the force ? « On theoretical side, we are lacking a derivation of the nuclear force that is based upon theory (in the true sense of the word) and produces a quantitative NN potential » R. Machleidt and I. Slaus, The nucleon-nucleon interaction, TOPICAL REVIEW J. Phys. G : Nucl. Part. Phys. 27 (2001) R 69 -R 108 sp states + Couplings + collective degrees of freedom ? « In all the recent works devoted to the single-particle states the particle-vibration coupling is mentioned but not taken into account so far within the same framework. A serious step forward in this direction has to be made. » W. Zou, G. Col`o, Z. Ma, H. Sagawa and PF Bortignon, Tensor correlations and evolution of single-particle energies in medium-mass nuclei, Phys. Rev. C 77, 014314(2008) Reaction +structure? Revisit scattering theory? Treatment of the structure embedded in the continuum, of the unbound states ? Extended framework treating on the same footing bound and scattering states ? Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Open questions V(r), STRUCTURE ? INTERACTION ? (r) N N Reactions involving states close to continuum ? Structure theories for states embedded in the continuum ? We need theories with structure and reaction embedded in the continuum Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Conclusion s Ocean of weakly binding energies Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Compléments (I) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Structure of exotic nuclei Rules of the evolution of nuclear structure at large isospin ? Explore Shell quenching Nuclear structure ? Which interactions ? How to model? n p p n T. Otsuka et al Z N VNN +VNNN : S. Pieper, Wiringa et al continuum-coupling (CC) effects: K. Bennaceur, M. Ploszajczak, …. A. Volya et al. Density-dependent pairing effects, DFT : T. Duguet et al. Nuclear potential ; nuclei at larger N/Z weaker binding energy more diffuse nuclear potential (J. Dobaczewski et al. isospin-dependent terms, p-n tensor interaction enhanced nuclear correlations, CC effects change of SO potential (B. Todd-Rutel et al. ) Direct reactions to unbound states ESNT 4 -6 Fev. 08 Theoretical challenges: Interplay between these effects Experimental exploration CEA-SPh. N vlapoux@cea. fr

Predictions of the Drip-lines RMF 31 F 8 Z 24 23 1 2 6 4 2 H 14 4 He 11 p d t n 6 2 H 4 e 6 Li 8 H e 8 1 9 B e He O N C B Be Li borromean N 10 12 14 16 HFB-Gogny HFB-Skyrme Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Predictions of the drip-lines, HFB-Skyrme microscopic predictions for S 2 n energy and deformation throughout the mass table Density functional method + Sly 4 Skyrme NN interaction J. Dobaczewski et al. Ni isotopes M. V. Stoitsov, et al. , PRC 68, 054312 (‘ 03) Direct reactions to unbound states Kr isotopes ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Reference : calc from PRC[Stoit 03] Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

S 2 n =8. 5 ? Sn = 5. 2 4+ 2+ 0+ 1. 52 0. 67 Me. V 94 Kr S 2 n =7. 91 2+ ? 6? Me. V Sn = 4. 95 0+ 96 Kr Similar trend for neutron-rich SPIRAL 2 beams : few bound states Calc : M. V. Stoitsov, et al. , Phys. Rev. C 68, 054312 (‘ 03) Data AME 2003 Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Predictions of the Drip-lines, HFB-Gogny M. Girod et al, CEA-DAM Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Predictions of the Drip-lines, RMF 125 Pd (Z=46) found at RIBF, N=79 Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Compléments (II) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Nuclear structure explored via elastic and inelastic scattering (p, p’) ES Testing ground : weakly-bound light nuclei I IT S N DE exploring… Weakly bound states ? Continuum coupling ? Isospin dependence ? Stable nuclei : (e, e’) probe Radioactive beams : no direct access to protons but to integrated value B(E 2) from Coulex Mn, Mp B(E 2; , i f)=|Mp|2/(2 Ji+1) Direct reactions to unbound states gs proton densities & excitation EM probe Microscopic potential nucleus- nucleon U(rho, E) tr =< i| (r-r’)| f> n, p 2+ 0+ (p, p’) probe : sensitive to densities, excitation of neutrons & protons Ex : local microscopic complex potential JLM, J. P. Jeukenne, A. Lejeune & C. Mahaux, PRC 16 (‘ 77) 80 valid for Ep, En up to 160 Me. V U( , E) = v V ( , E) +i w W( , E) ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Search for low-lying resonances and study of neutron excitations (p, p’) probe Particle spectroscopy MUST (8 in a wall) structure studies by (p, p’) & (p, d) reactions using GANIL/SISSI or SPIRAL beams and MUST+CATS Elastic scattering sensitive to the matter rms Nuclear densities, neutron excitation + CATS Inelastic scattering : sensitive to the shape of the density C. Jouanne, VL. et al. , 10, 11 C(p, p’) PRC 72, 014308 (’ 05) rmsm (10 C) : 2. 42 0. 1 fm ; rmsm (11 C) : 2. 33 0. 1 fm [rmsm (12 C) : 2. 30 (3) fm] beam Weakly-bound nuclei 2+ Unbound excited states low-lying resonances + 0 1. 8 Me. V S 2 n = 0. 975 6 He MUST : Y. Blumenfeld et al. , NIM A 421, 421 (‘ 99) CATS : S. Ottini et al. , NIM A 431, 476 (‘ 99). Direct reactions to unbound states Halo, Neutron-skin structure ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Prototype of (p, p’) & direct reactions at low energy: 8 He(p, p’) (T 1/2= 119 ms) I= 104 /s reaction target CH 2 8 He set-up at GANIL ? S 3. 6 Me. V 2+ Si Strips 300 m MUST Sn =2. 5 neutron-skin ? + 0 Resonances Si(Li) 3 mm X, Y, T, E 4 n =3. 1 Si Strip 6 x 6 cm 2 S 2 n = 2. 1 8 He Cs. I 1. 5 cm T 1/2 =119 ms p wave fct 8 He PROBE : 8 He(p, p’)8 He* SPIRAL 8 He He test of the validity of the densities eg 6 He(p, p’) @ 40. 9 Me. V/n GANIL-MUST A. Lagoyannis et al. , PLB 518, 27 (‘ 01) 2 n-Halo features 6 He NPA 722, 49 c(‘ 03) @ 15. 7 A. Me. V 14000 /s [1 ary beam: 13 C @ 75 A. Me. V] CH 2 target Beam detector CATS 2 CATS 1 Collaboration : SPh. N, GANIL, IPN-Orsay, FLNR-Dubna, Univ. Ioannina (Greece) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Structure of 8 He p n 1 p 1/2 1 p 3/2 1 s 1/2 V 3 eff 4ħω ħΩ=13 Me. V COSMA SAGAWA models p B(E 2) = 0. 25 e²fm 4 Mn/Mp = 13. 5 n COSMA: M. V. Zhukov, A. A Korsheninnikov & M. H Smedberg, PRC 50 (‘ 94) R 1 H. Sagawa, PLB 286 (‘ 92) 7 P. Navratil & W. E. Ormand, PRL 88, 152502 (‘ 02) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N priv. Co. vlapoux@cea. fr

Conclusions: structure and spectroscopy of 8 He (p, p’) (p, d) (p, t) @ 15. 7 A. Me. V 8 He(p, p’) SPIRAL a new resonance Structure models overestimate Eexc for unbound excited states Understanding of the weakly bound & unbound states requires calculations including the continuum coupling 8 He(p, p’) E* : 2 states 8 He(p, d)7 He transfert 1 n Resonant states of 7 He Indication of a possible 1/2 - resonance at low energy PRC 73, 044301(’ 06) E(Me. V) Γ (Me. V) 2+ 3. 62 ± 0. 14 ? 5. 4 ± 0. 5 0. 3 (2) 0. 5 (3) NP A 788, 260 (2007) Coupling to the (p, d) channel to understand the (p, p) PLB 619, 82(’ 05) C 2 S = 4. 4 ± 1. 3 mixing : (p 3/2)4 + (p 3/2)2 (p 1/2)2 8 He 2+ p l=0 l=2 7 He 8 He(p, d)7 He 8 He p d p n 1 p 1/2 1 p 3/2 1 s 1/2 PLB 646, 222(’ 07) All direct reactions at the same energy : a need for a complete coupled-channel analysis Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

SPh. N - Exotic nuclei Structure and spectroscopy of 8 He via direct reactions on proton SPIRAL 8 He (T 1/2= 119 ms) I= 104 /s ; E=15. 7 A. Me. V reaction target CH 2 wave function 8 He Structure de l’état fondamental & recherche d’états excités non liés spectroscopie de particules légères chargées p, d, t (MUST) mesures des résonances de 8 He NPA 788 c, 260 (’ 07) distributions angulaires analyse en voies couplées des réactions PLB 619. 82 (’ 05) ; 646, 222 (’ 07) COSMA: Alpha+4 n NCSM Calculs en couches sans cœur (NCSM) validés Direct reactions to unbound states (p, t) fonction d’onde de l’ 8 He % 6 He [8 He/6 He(0+)] =1 ; [8 He/6 He(2+)] =0. 014 mélange : (p 3/2)4 + (p 3/2)2 (p 1/2)2 ESNT 4 -6 Fev. 08 CEA-SPh. N p n vlapoux@cea. fr 1 p 1/2 1 p 3/2 1 s 1/2

Evolution of the neutron skin thickness : ex of Neon isotopes Density functional. calc. with R. Lombard’s code Similar trend in HFB-def (Sly 4) calc of J Dobaczewski, M. V. Stoitsov, et al. , PRC 68, 054312(‘ 03) Direct reactions to unbound states ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr

Neutron-skin structure of 34 Ne via direct reactions on proton target 30 Ne 31, 33 Ne unbound 34 Ne 32 Ne 20 2+ Weakly-bound nuclei Small Sn, S 2 n Searching for low-lying states unbound states neutron excitations… S 2 n 1. 97 1. 63 Me. V 0+ 22 Sn N/Z=2. 4 24 26 N 2+ 947 300 ke. V 0+ 32 Ne Sn 34 Ne S 2 n 34 Ne(p, p’)34 Ne* 34 Ne Direct reactions to unbound states +p p’ + 34 Ne* p + 32 Ne + 2 n p’ + 34 Ne* p + 30 Ne + 4 n ESNT 4 -6 Fev. 08 CEA-SPh. N vlapoux@cea. fr