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Nuclear densities et excitations of exotic nuclei via direct reactions. ACTIVITIES AND PERSPECTIVES. Neutron-skin structure and shell evolution of weakly-bound neutron-rich SPIRAL / SPIRAL2 / EURISOL nuclei in coupled-reaction channel studies. - PowerPoint PPT Presentation
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Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Neutron-skin structure and shell evolution
of weakly-bound neutron-rich SPIRALSPIRAL/SPIRAL2SPIRAL2/EURISOLEURISOL nuclei
in coupled-reaction channel studies
Probe the structure & spectroscopy at large isospinMeasure unbound states detection devices
n , p
GOAL: extension of systematics of neutron rms radius and of neutron excitation along isotopic chains
Structure studies at the drip-lines : exemples, + exp-theory
NEED FOR AN IMPROVED THEORETICAL FRAMEWORK NEED FOR AN IMPROVED THEORETICAL FRAMEWORK OF STRUCTURE AND REACTIONSOF STRUCTURE AND REACTIONS
ACTIVITIES AND PERSPECTIVES
Nuclear densities et excitations of exotic nuclei via direct reactions
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Nuclear structure towards the drip-lines : phenomena to explore & to understand
Neutron skins
halo,clusters
Change in shell structureNew magic numbersLocal properties (N,Z)
4He
6Hehalo
8He4He
Neutron skin
Evolution of structure
at large isospin ?
2008: what do we know?2016: future explorations
Drip-lines: limit of nuclear binding, large isospinExploration: new exotic structures neutron-skin Tests: nuclear modelling & interactions VNN(Tz)
Weakly bound states ?Continuum coupling ?Isospin dependence ?
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Nuclear landscape towards the drip-lines
2 4 6 8 10 12 14
N
16
2
4
6He
6
Z8
4He
borromeanHe
C
N
O
Hn
pp d t8He
11Li
F 31
Li
Be14Be
B
12
1922
23
24
20020088
Very few drip-line nuclei have their identity card complete Masses, size, densities, neutron excitation, low-lying spectroscopy, shell structure
6He
Drip-line : 8He neutron-skin
SPIRAL 8He (T1/2= 119ms)
I= 104 /s ; E=15.7 A.MeV reaction target CH2
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
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 thevalley of stability
N
Z
halo and neutron-skin
8He
6HeMethod : direct reactions induced by radioactive beamsGANIL/SPIRAL ; SPIRAL2 in 2012
SPhN activities on structure of exotic nuclei via direct reactions
Experimental DevicesDetector of
Charged particlesSi-strips, CsI
x-y-E-DE-TOF
MUST2Collaboration:
DAPNIA, GANIL and IPN-Orsay
Beam detectorCATS-BTD
SEDI-SPhN targ
et
10 cmbeam
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Light nuclei and three-body forces
S. Pieper et al. Nucl Phys. A751(2005), 516c
PRC 70 (2004) 54325
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
SPIRAL 8He +p @ 15.7A.MeV
Structure of Structure of 88He extracted from direct reactions on proton targetHe extracted from direct reactions on proton target
F. Skaza PhD SPhNF. Skaza, N. Keeley, VL et al., PLB 619. 82 (’05)N. Keeley et al., PLB 646,222(’07)
Coupled-channel calc.: N. Keeley (SPhN)
8He(p,p) 8He(p,t)6He(0+)
8He(p,t)6He(2+)
8He(p,d)
CRC calc
Structure of ground state & search for unbound excited states
spectroscopy of light charged particles p,d,t (MUST) measurements of resonances in 8He NPA 788c, 260 (’07) angular distributions ; analysis in coupled reaction channelsPLB 619. 82 (’05) ; 646, 222 (’07)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
[1] 8He(p,d)7He C2S = 4.4 ± 1.3 [CCBAanalysis]CRC (p,p) (p,d) C2S = 3.3 ± 1.3PLB 619, 82 (’05)[2] (p,t) wf. of 8He%6He [8He/6He(0+)] =1 ;[8He/6He(2+)] =0.014
Configuration mixing : (p3/2)4 and (p3/2)2
(p1/2)2
Structure of Structure of 88He extracted from direct reactions on proton targetHe extracted from direct reactions on proton target
Consistent with results from quasi-free scattering of 8He measured at GSI, LV Chulkov et al, NPA759, 43(’05)
Data: SPIRAL-MUST [1] F. Skaza et al., PRC73, 044301(’07)[2] N. Keeley et al, PLB 646, 222(‘07)
CRC Coupled-reaction channel analysis: N. Keeley (SPhN, Inst. A. Soltan)
CRC calc
8He(p,t)6He(0+)
8He(p,t)6He2+
8He(p,d)8He(p,t)6He(0+)
8He(p,t)6He (2+)
Data: A. A.Korsheninnikov et al, PRL 90, 082501 (‘03)
RIKEN 61.3 A.MeV
CRC calc p n1s1/2
1p3/2
1p1/2
p n1s1/2
1p3/2
1p1/2
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Spectroscopy of Spectroscopy of 88He : exp versus theoryHe : exp versus theory
[Kor93] A.A. Korsheninnikov et al., PLB 316 (‘93) 38
[Oer95] W von Oertzen et al., NPA588 (‘95) 129
[Nil95] T. Nilsson et al., NPA583 (‘95) 795
[Boh99] H.G. Bohlen et al., Prog. Part. Nucl. Phys. 42 (‘99) 17
[Mar01] K. Markenroth et al., NPA679 (‘01) 462
[Wir02] R.B. Wiringa & S.C Pieper,
PRL 89 (‘02) 182501
[Nav04] P. Navratil & B.R. Barrett,
PRC 57 (‘98) 3119 +private co.
experiments
theories
(p,p’)
[Kor93] [0er95] [Nil95] [Boh99] [Mar01]
COSMA model +4nM. Zhukov et al. PRC50,
1(‘94)
p n1s1/2
1p3/2
1p1/2
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Spectroscopy of Spectroscopy of 88He : exp versus theoryHe : exp versus theory
Wigner : « Beautiful theories
have to face ugly facts »
And the specific treatment of resonant states ?
experiments theories
[Kor93] [0er95] [Nil95] [Bohl99] [Mark01]
(p,p’)
SPIRAL(p,p’)
E(MeV) Γ (MeV)2+ 3.62 ± 0.14 0.3 ± 0.2? 5.4 ± 0.5 0.5 ± 0.3
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Spectroscopy of Spectroscopy of 88He : exp versus theoryHe : exp versus theory
P. Navrátil & B. R. Barrett,
PRC 57, 3119 (‘98).“The 8He nucleus is a weakly bound
system, where scattering to the continuum
will play an important role in the structure of higher-lying states.”
Continuum Shell Model (CSM):Discrete and Continuum Spectra in the Unified Shell Model
Approach, A.Volya & V. Zelevinsky, PRL 94, 052501 (‘05)
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
[QMC] [NCSM] [GSM] [CSM]
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Alpha + 4 n
No coreShell model
Conclusions
Test of the validity of 8He gs densities using (p,p) : neutron-skin features close to NCSM densities COSMA not valid
(p,p’) mainly sensitive to the neutron excitation ; Transition densities 2+ 0+ : NCSM calc. overestimate the p & n excitations
n , p
(p,p’)(p,p’)
NCSM2.462.592.00NCSM, Navrátil
2.512.671.95HF+corr Sagawa
2.522.741.69 COSMA 5-body
MatterNeutronProton
Rms (fm)8He
NCSM (No Core Shell Model) (V3eff 4hw, 13MeV )
Test of transition densities ; Analysis in progress
CRC (p,p’) CRC (p,p’) Coupling with the Coupling with the (p,t)(p,t)
NEUTRON-SKIN THICKNESS: ~ 0.6 +/- 0.05 fmNEUTRON-SKIN THICKNESS: ~ 0.6 +/- 0.05 fm
Validation of no-core shell model calculations (NCSM) for gs
COSMA:Alpha+4n
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
CEA-SACLAY DSM/DAPNIA/SPhN : N. Alamanos, F. Auger, A. Drouart, A. Gillibert, V. Lapoux, L. Nalpas, E. Pollacco, R. Raabe, J-L. Sida, F. SKAZA (PhD).IPN-Orsay : D. Beaumel, Y. Blumenfeld, F. Delaunay, E. Becheva, J-A. ScarpaciGanil : L. Giot, P. Roussel-ChomazFLNR - Dubna : S. Stepantsov, R. Wolski University of Ioannina : A. Pakou
Participants of the experiment 8He(p,p’)
ANALYSIS : Microscopic densitiesMicroscopic densities P. Navrátil + interaction Argonne
H. Sagawa HF +correlationsFutur : cf M . Ploszajczak Ganil
JLM potential:JLM potential: code Dietrich (Livermore) ; form factors (form factors (home madehome made, VL), VL) + CRC 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 ;• SPhN : 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 4-6Fev. 08 CEA-SPhN [email protected]
Collaboration
DAPNIA/SPhN : 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. ScarpaciVisiteurs à Orsay : H. Iwasaki, D. SuzukiGANIL : P. Roussel-Chomaz, C. Force, L. Gaudefroy, T. Kalanee, T. RogerA. Soltan, Varsovie : K. Rusek, I. StrojekFLNR - Dubna : R. Wolski University of Ioannina : A. Pakou, T. Mermizedakis
6He low-lying spectroscopy via 8He(p,t)6He
Structure & spectroscopy of exotic nuclei
Technical and software support:SPEG P. Gangnant, JF Libin Ganil, services techniques J. Cacitti, G. Fremont, C. SpitaelsGIA ex GIP : C. Houaner, G. Leberthe, L. Légeard, L. Olivier, M. Tripon, B. Raine, F. Saillant
Technical and software support:ASIC DAPNIA/SEDI E. Atkin, P. Baron, F. Druillole, F. Lugiez, B. Paul, M. Rouger
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Nearfar
future
projectsplans
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
100 mm
MUST1 MUST2: improvments factor 3 in active area smaller volume of PAmp : x 6 better time resolution
MUST2 MUr à STrips 2, new generation of MUST
Increased compacity due to the ASIC technology (Application Specific Integrated Circuit) coïncidences particle -
Si(Li)Si(Li)4.5 4.5 mmmm
CsI 3 cmCsI 3 cm4 x 4 4 x 4 segmentssegments
Si stripsSi strips300 300 mm100 x 100 mm100 x 100 mm22
X, Y , T, E128X128Y
E
MUST2MUST22004-62004-6Developed by : DAPNIA/SEDI : µ-electronics R&D ASIC GANIL IPN Orsay
collaboration : CEA-DAPNIA, GANIL, IPN-Orsay
MEASUREMENTS AND ANALYSIS OF REACTIONS IN COUPLED- CHANNELS
collaboration MUST2:SPIRAL +Futur SPIRAL2
Evolution of neutron excitationMn vs N along isotopic chains
Exotic shapes and resonances
One-particle stateSpectroscopic factors
MUST2MUST2
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Danilin et al.Few-Body modelPRC 55, 577 (’97)
0+
2+ 1.8
4.3
(2+2) = 1.2
2+2
5
4.51+
0+2
THEORIES
States between 2 and 10 MeV ?
Positions 2+2, 0+
2 VNN +VNNN
Correlations in light neutron-rich nuclei
Navratil et al.No Core shell Model10hw V2eff
0+
2+ 2.53
5.79
2+2
0+2 8.5
4
6.50
1+
Pieper et al.NN+NNN IL2 PRC70,054325(’04)
0+
2+ 1.8
~51+
2+
0+ 6
Spectroscopy of 6He
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Experimental set-up with MUST2
CH2 target1mg/cm2
CATS2 CATS1
SISSI-SPIRAL Beams8He, 20,22O, 14OI = 104 - 105 /s
p,d,t
Identification A,Z : SPEG
MUST2
CATS2
MUST2 @ d=15 cm
5-25 deg lab (15-80 c.m.)Sect. Eff (p,t) ~ 5 10-3 – 0.5 mb/sr
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Structure of exotic nuclei via direct reactions
BTD
Beam tracking
ex : SPIRAL2 96Kr @ 10MeV/n I= 104 /s 96Kr(d,p)97Kr, (d,d’) (d,t)
EURISOL n-rich Ne, Ca, Ni, Kr, Sn @ 20-50MeV/n I > 105 /s
Complete kinematical Complete kinematical reconstruction reconstruction access to bound and unbound access to bound and unbound statesstates
Ex: MUST2-like arrayParticle-spectroscopy (d,p)
VAMOS
Identification : VAMOS
(d,p) A+1Z
Charged-particle spectroscopyThin target CH2 , CD2 1 mg/cm2
I (> 5. 103/s)
(d,p) Gamma detection
AZ(d,p)A+1Z
AZCD2
p
Transfer reactions ; coupling between particle and gamma spectroscopy
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Nuclear landscape towards the drip-lines
16 18 20 22 24 26 28
N
30
18
Z
4He
20020088
10
12
14
16
8 structure of 24O ? 24O23N22C
31F
30,31,32Ne
33Na
34Mg 38Mg
Next drip-line nuclei ?
37Na36
33
39
Tarasov97Sakurai PLB448, (99)Notani PLB 542 (02),Lukyanov02Tarasov PRC 75 (’07)
43Si
40Mg
44Si
Low-lying resonances ?Neutron skin ?Neutron excitation ?Density Profiles ?New shell effects ?
Complete the Identity card of drip-line nuclei
34Ne
Dri
p-l
ine
Dri
p-l
ine
07 :07 : 125 125Pd (Z=46) found at RIBFPd (Z=46) found at RIBF
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
neutrons
fp
sd
d5/2
d3/2
s1/2
stability
f7/2
p3/2
sd-fpsd-fp 2020
N = 16Z=14 30Si
N = 20
88
N = 8p3/2
p1/2
s1/2
Shell effects far away from stability with new generations of RIB s
systematics of neutron excitations vs N Search for new magic numbers
neutrons
fp
sd
d5/2
d3/2
s1/2
drip-line N = 16, Z=8, 24O
f7/2
p3/2
sd-fp
N = 14 22O
N = 16
N = 8
16
N=16 Learnt from 1st generation of RIBs
(1h11/2-)1
2
82(f7/2) Local properties (Z,N)
N=34,40,70 instead of N=50,82 ?
RIBF, SPIRAL2 EURISOL
Extension of the systematics of neutron excitation along isotopic chains
EURISOL
EURISOL
If the beams are new (36Ne ? 60-68Ca ?) or rare at present (24O few/s at GANIL, RIKEN) with EURISOL : counting rates less or around 103-105 /s
Spectroscopy of unbound states in neutron-rich beams close to the drip-linesWhich beams ? We want to gain in exoticity Which beams ? We want to gain in exoticity
Complete the (p,p’) chains O (24O), 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 :34Ne , 38Ne (if not unbound), 60-70Ca, 104Se (Z=34, N=70)
Z
N
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Letter of Intent for SPIRAL2
o Single-particle structureo Nuclear pairingo Spectroscopy of very-neutron rich nucleio Cluster studieso Direct reaction mechanismso Applications to astrophysics cf LOI r process nucleosynthesis
- Experimental conditions and requirements: BEAM, DETECTION, THEORY- SPECIFICITY
Cf GENERAL LOI : Direct Reactions Studies of Exotic Nuclear Structure
LOI-16 unbound states unbound states in n-rich nucleiin n-rich nuclei
SPECTROSCOPY SPECTROSCOPY of of bound and bound and unboundunbound states states
()
Sn
?E (MeV)
Transfer (d,p) & (p,d)Elastic & Inelastic scattering(p,p’) (d,d’)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Evolution of neutron excitationMn vs N along isotopic chains
Exotic shapes and resonances
One-particle stateSpectroscopic factors
Beams Variety A,ZLimit of nuclear binding, I
2012+ 2020+
Alpha-clustersstates
Skin and halos
Soft collective modesZ
N
Going closer to driplines with higher intensities : opened physics fields
Far ..far away
Sn
134-136Sn94-96Kr94-96Zn 96-98Sr
5
3
4
1
2
Unbound statesMeV
(p,p’), (p,d) (p,t) (d,d’) (d,p) (d,t)
e.g. Ni, 30Zn, 34Se, 36Kr, Sn
-Exc spectra, density distributions via (p,p’)- Shell structure, s.p states, J
via nucleon-transfer
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
ISPIRAL2 94Kr I > 109
0.75 MeV
95Kr I > 9. 108
2.84 MeV
96Kr I > 104
0.74 MeVQ-value
2.97#
1/2(-)
94Kr(d,p) 95Kr
E
(MeV
)
Sn
gs0
2
95Kr(d,p) 96Kr 96Kr(d,p) 97Kr
S2n
Sn
(7/2-) ?
2.96#
4
00+
4+ ?
2+ ?
6+ ?
?
?
88.03#
Sn5.06#
2+ , 4+, 6+ ?
?
S2n8.02#
0.78s
Bound and unbound states full reconstruction of the kinematics full reconstruction of the kinematics (p,p’) or (d,p) excitation spectrum (p,p’) or (d,p) excitation spectrum ++Spectroscopic factors
Low-lying spectroscopy of n-rich Kr isotopes
(2p1/2) (1f5/2)
(1g9/2)1
0
50(g7/2)
neutrons Neutron excitation of 96Kr via (p,p’) and shell structure of 97Kr via 96Kr(d,p)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
BTD +particle-gamma coupling + Detection at the focal plane for (Z,A) identification
separation of excited states with high-density levelcf LOI-direct ReactionsLOI-direct Reactions Future 4 GASPARD array GAmma Spectroscopy & PArticle Detectionsimulation of exp set-up
PREPARATION OF THE EXPERIMENTAL SET-UP
EXOTICPREPARATION OF THE THEORETICAL FRAMEWORK
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 reactionsbenchmark reactions
SP2 Beams : larger incident energies required (cf L window & access to excited states)
CD2target -ray detector exotic beamexotic beam
SPIRAL2SPIRAL2AAZZ
identification
A+1A+1ZZp
beam trackingdevices
particle
detection
LOI “Unbound states”
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Collaboration LOI SPIRAL2 “Unbound states”
CEA-SACLAY DSM/DAPNIA/SPhN: 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. PetracheGANIL: L. Gaudefroy, W. Mittig, F. de Oliveira, P. Roussel-Chomaz, H. Savajols, O. SorlinHMI Berlin, Germany: H.G. Bohlen, Tz. Kokolova, W. Von Oertzen, C. WheldonJINR, FLNR Dubna, Russia: A. Fomichev, M.S. Golovkov , A. Rodin, S. Sidorchuk, S. Stepantsov, G. Ter-Akopian, R. WolskiIKS University of Leuven, Belgium: R. RaabeIPHC Université Louis Pasteur, Strasbourg: Ch. Beck, S. Courtin, A. KhouajaINFN-Catania, Italy: A. MusumarraKVI, Netherlands: M.N. Harakeh, H.G. Wortche Florida State University, US: K.KemperUniversity of Huelva, Spain: I. MartelUniversity of Ioannina, Greece: : T.J. Merzimekis, A. Pakou, D. RoubosUniversity of Santiago de Compostela, Spain: M.D Cortina-GilTheoretical support :CEA-Bruyères-le-Châtel DAM/DIF/SPN: E. Bauge, P. Chau Huu-Tai, J.P. Delaroche, H. Goutte, S.PéruCENBG: M. BenderIPN-Lyon: K. BennaceurIST, Lisboa, Portugal: R. CrespoThe A. Soltan Institute for Nuclear Studies, Hoza, Warsaw, Poland: K. RusekNSCL, MSU, USA: T. DuguetUniversity of Pisa-INFN-Pisa: G. Blanchon, A. BonnacorsoThe 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 4-6Fev. 08 CEA-SPhN [email protected]
DO THE BEST POSSIBLE CALCULATIONS !!!!DO THE BEST POSSIBLE CALCULATIONS !!!!DWBA is a limited framework, turns out to be WRONG for strongly-coupled channelscf CRC calculations, CDCC: Nick Keeley’s lecture at ECOLE JOLIOT-CURIE ’07les réactions nucléaires comme sonde de la structure
ANALYSIS OF (D,P) CROSS SECTIONS...
Once upon a time…
Successful analysis for the stable nuclei [cf 40Ca(d,p) ]: E=7, 8, 9,10, 11, 12 MeV Lee,..Schiffer, Satchler, Drisko, PR 136 4B (’64) 40Ca(d,p) 41Ca a test of the validity of the DWBAR. Satchler Direct nuclear reactions, Clarendon Press, Oxford Univ Press 1983
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 …
Ex : N. Timofeyuk & RC Johnson, PRC 59, 1545 (‘ 99) : d break-up included within the adiabatic approach from Johnson & Soper
Analysis of the 16O(d,p)17O,10Be(d,p)11Be, and 11Be(p,d)10Be reactions.
Comprehensive analysis method for (d,p) stripping reactions ; test calc. : 12C(d,p)@ 25 MeV 10Be(d, p) @ 12 and 25 MeV , N. Keeley,* N. Alamanos, and V. L, PRC 69, 064604 (‘04)
« 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. »
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 ’)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
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 channelsNEED TO DEFINE THE APPROPRIATE SCATTERING THEORY
State of the art :Coupled reaction channel analysis explicit channel coupling+Microscopic potentials
FUTURE: Structure and reaction on the same footing
• 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)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
EURISOL : a new theoretical framework
Data+ Virtual coupling potential for elastic scattering of 10,11Be on p V. L et al., PLB 658, 198 (’08)
Strong pickup-coupling effect on p+11Be elastic scatteringN. Keeley and V. L PRC 77, 014605 (‘08)
CRC calc :11Be(p,d)10Be* pickup to the 5.960 MeV 1- and 6.263 MeV 2- doublet of excited states in 10Be
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Drip-line studies
Drip-lines : limit of nuclear binding, large isospinExploration : new structures of exotic nuclei Tests : nuclear modelling & interactions VNN(Tz)
SIMPLE PROBE : (p,p’) combined to Coulex informationdirect reactions in inverse kinematics, missing mass method
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(E2) S2n, and evolution of neutron excitation
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 chainsMEANS to Probe the structure & spectroscopy at large isospin Measure unbound states
EXPLORATION:
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
spectroscopy of low-lying states of neutron-rich isotopes via (p,p’), (p,d) (p,t), (d,p)spectroscopy of low-lying states of neutron-rich isotopes via (p,p’), (p,d) (p,t), (d,p)
Measurement to unbound states:Particle-spectroscopyLarge enough intensitiesintensities EURISOLEURISOL
Large angular coverage all reactions measured simultaneously Elastic and transferLow particle threshold :small c.m. angles
Possible to carry out full coupled-reaction channel analysis
EXTRACT form factors from (p,p’) spectroscopic factors from (d,p)
suitable range of beam energiesfor (p,p’) and (d,p) : E ~ 10-30 MeV/n
In 2016+: new beams of neutron-rich Ne, Ca, Ni, Kr, Sn isotopes… Access to neutron-thickness evolution + change in shell structure
Present (1st generation) intensities : few part/sNeeded : (at least) 103-105 /s
34Ne+p @ 25 A.MeV
tt
ppdd
40c.m.
20c.m.
10c.m.
Improvment of exp set-up + Theoretical framework
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Theoretical framework for the analysis of direct reactions
Enhanced effects in the case of weakly-bound exotic nuclei: Coupling to continuum, 3-body, many-body correlations Shell structure embedded in the continuumUse the predictions of improved structure theories Use the predictions of improved structure theories to take into accountto take into account these effects and the isospin-dependence of the nuclear interaction
PROTOTYPE-STUDY: 8He(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 nucleimust be put into question A PRIORI How good (potential, framework) is really good for exotic beams ?How good (potential, framework) is really good for exotic beams ?Validity of optical potentials ? 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
FORMALISM in COUPLEDFORMALISM in COUPLED REACTION CHANNELSREACTION CHANNELS
To include the coupling to excitations AND to reaction channels
COMPLEX MICROSCOPIC POTENTIALSCOMPLEX MICROSCOPIC POTENTIALS
to test the validity of nuclear density
Improved approach (best we can do today)
To be scheduled in 2008 ESNT WorkshopTo be scheduled in 2008 ESNT Workshop STRUCTURE AND REACTIONS IN COUPLED REACTION CHANNELSSTRUCTURE AND REACTIONS IN COUPLED REACTION CHANNELS
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Structure and spectroscopy Structure and spectroscopy of exotic nuclei via direct reactionsof exotic nuclei via direct reactions
Conclusions Conclusions PerspectivesPerspectives
Powerful tool for the study of unbound states :DIRECT REACTIONS IN COUPLED CHANNELS
()
Sn
?E (MeV)
Isospindependence
Roleof coupling
to continuum
Beyond mean-fieldrole of many-body
correlationspairing
Effective interaction NN
GOALS
find new aspects de structure weakly-bound exotic nuclei,
new constraints for the nuclear modelsof 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
observable
Experimen-talist
theorist
« MOSAÏQUE DES NOYAUX », P. BONCHE, CEA-SPhT
Studies of exotic nuclei need to combine several probes & Require systematics along extended isotopic chains
StructureBound states
Role of the coupling to the
continuum
ReactionsScattering
states
Nuclear Models
PCV
PHYSICS OF THE PUZZLE AND OF THE INTERPLAY
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Discussions - Questions
« On the 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) R69-R108
the force ?the force ?
sp states + Couplings + collective degrees of freedom ?sp states + Couplings + collective degrees of freedom ?
Treatment of the structure embedded in the continuum, of the unbound states ?Extended framework treating on the same footing bound and scattering states ?
« 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? Reaction +structure? Revisit scattering theory?
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Open questions
Reactions involving states close to continuum ?
STRUCTURE ?
INTERACTION ?
V(r),(r)
NN
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 4-6Fev. 08 CEA-SPhN [email protected]
Conclusions
Ocean of weakly binding energiesOcean of weakly binding energies
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Compléments (I)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Structure of exotic nuclei
Experimental explorationExperimental exploration
Rules of the evolution of nuclear structure at large isospin ?
Explore Shell quenchingNuclear structure ?Which interactions ?How to model?
N
ZVNN +VNNN : S. Pieper, Wiringa et al
p
p
nn
T. Otsuka et al
continuum-coupling (CC) effects:K. Bennaceur, M. Ploszajczak, …. A.Volya et al.Density-dependent pairing effects, DFT : T. Duguet et al.
Theoretical challenges: Interplay between these effects
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 4-6Fev. 08 CEA-SPhN [email protected]
Predictions of the Drip-lines
2 4 6 8 10 12 14
N
16
2
4
6
He
6
Z8
4HeborromeanHe
C
NO
Hn
pp d t8
He
11
Li
F 31
Li
Be14
Be
B
12
19
23
24
RMF
HFB-GognyHFB-Skyrme
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Density functional method + Sly4 Skyrme NN interaction
M.V. Stoitsov, et al., PRC68, 054312 (‘03)
microscopic predictions formicroscopic predictions for SS2n2n energy and deformation throughout the mass table energy and deformation throughout the mass table
J. Dobaczewski et al.
Predictions of the drip-lines, HFB-Skyrme
Ni isotopes
Kr isotopes
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Reference : calc from PRC[Stoit03]
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
0+
2+
S2n =7.91
Sn = 4.95
96Kr
6? MeV?
Calc : M.V. Stoitsov, et al., Phys. Rev. C68, 054312 (‘03)Data AME2003
0+
4+
S2n =8.5
Sn = 5.2
94Kr
?
0.67 MeV
1.52
2+
Similar trend forneutron-rich SPIRAL2 beams :few bound states
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Predictions of the Drip-lines, HFB-Gogny
M. Girod et al, CEA-DAM
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Predictions of the Drip-lines, RMF
125Pd (Z=46) found at RIBF, N=79
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Compléments (II)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Nuclear structure explored via elastic and inelastic scattering (p,p’)
0+
2+ (p,p’) probe : sensitive tosensitive to densities, excitation of densities, excitation of
neutrons & protonsneutrons & protons
proton densities & excitation EM probeStable nuclei : (e,e’) probe
Radioactive beams : no direct access to protons but to integrated value B(E2) from Coulex
Weakly bound states ?Continuum coupling ?Isospin dependence ?
Testing ground : weakly-bound light nuclei
Microscopic potential nucleus- nucleon U(rho,E)
drrr Lnpfi
2)( )( Mn, Mp
B(E2;,if)=|Mp|2/(2Ji+1)
Ex : local microscopic complex potential JLM,J.P. Jeukenne, A. Lejeune & C. Mahaux, PRC 16 (‘77) 80 valid for Ep, En up to 160 MeV
n, p
U(,E) = v V (,E) +i w W(,E)
gs
gs
excDENSITIES
tr =<i|(r-r’)|f>exploring…
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Search for low-lying resonances and study of neutron excitations
MUST : Y.Blumenfeld et al., NIM A421, 421 (‘99)
CATS : S. Ottini et al., NIM A431, 476 (‘99).
beam
MUST (8 in a wall)
+ CATS
((p,p’) probep,p’) probeParticle spectroscopy
C.Jouanne, VL. et al., 10,11C(p,p’)PRC 72, 014308 (’05)
Nuclear densities, neutron excitation
structure studies by (p,p’) & (p,d) reactions using GANIL/SISSI or SPIRAL beams
and MUST+CATS
Weakly-bound nucleiUnbound excited
stateslow-lying resonances
Inelastic scattering : sensitive to the
shape of the density
Halo, Neutron-skin structure
Elastic scatteringsensitive to the
matter rms
S2n = 0.9750+
2+
6He
1.8 MeV
rmsm (10C) : 2.42 0.1 fm ; rmsm (11C) : 2.33 0.1 fm[rmsm (12C) : 2.30 (3) fm]
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
PrototypePrototype of (p,p’) & direct reactions at low energy: of (p,p’) & direct reactions at low energy: 88He(p,p’)He(p,p’)
Collaboration : SPhN, GANIL, IPN-Orsay, FLNR-Dubna, Univ. Ioannina (Greece)
PROBE : 8He(p,p’)8He*
MUST
X, Y, T, E
Si Strip 6 x6 cm2
Si Strips 300 m
Si(Li) 3mm
CsI1.5 cm
pp
He
SPIRAL 8He
@ 15.7 A.MeV
14000 /s[1ary beam:
13C @ 75 A.MeV]
CH2 target
Beam detector CATS2
CATS1
test of the validity of the densitieseg 6He(p,p’) @ 40.9 MeV/n GANIL-MUST A. Lagoyannis et al., PLB 518, 27 (‘01)2n-Halo features 6He NPA722, 49c(‘03)
0+
2+
Sn =2.5
S4n =3.1
S2n = 2.1
8He
3.6 MeV?
T1/2 =119 ms
neutron-skin ?Resonances
8He (T1/2= 119ms) I=
104 /s reaction target CH2
set-up at GANILset-up at GANIL
wave fct 8He
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Structure of Structure of 88He He
modelsmodels
P. Navratil & W.E. Ormand, PRL88, 152502 (‘02)
V3eff4ħω
ħΩ=13 MeV
B(E2) = 0.25e²fm4
Mn/Mp = 13.5
p n1s1/2
1p3/2
1p1/2
COSMA
SAGAWA
p
n
COSMA: M.V. Zhukov, A.A Korsheninnikov & M.H Smedberg, PRC 50 (‘94) R1H. Sagawa, PLB 286 (‘92) 7
priv. Co.
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
All direct reactions at the same energy : a need for a complete coupled-channel analysis
Conclusions: structure and spectroscopy of Conclusions: structure and spectroscopy of 88He He (p,p’) (p,d) (p,t) @ 15.7 (p,p’) (p,d) (p,t) @ 15.7 A.MeVA.MeV
8He(p,d)7He transfert 1nResonant states of7HeIndication of a possible 1/2- resonance at low energy PRC73, 044301(’06)
8He(p,p’)E* : 2 states
88HeHe p
77HeHe d
88HeHe2+2+ pl=0l=2
SPIRAL
Coupling to the (p,d) channel to understand the (p,p) PLB 619, 82(’05)
8He(p,d)7He C2S = 4.4 ± 1.3mixing : (p3/2)4 + (p3/2)2 (p1/2)2
2+ 3.62 ± 0.14 0.3 (2)? 5.4 ± 0.5 0.5 (3)
Γ (MeV)E(MeV)
NP A788, 260 (2007)
p n1s1/2
1p3/2
1p1/2
PLB 646, 222(’07)
8He(p,p’) a new resonance
Structure models overestimate Eexc for unbound excited states Understanding of the weakly bound & unbound states requires calculations including the continuum coupling
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
SPhN - Exotic nuclei Structure and spectroscopy of8He via direct reactions on proton
SPIRAL 8He (T1/2= 119ms)
I= 104 /s ; E=15.7 A.MeV reaction target CH2
wave function 8He
(p,t) fonction d’onde de l’8He % 6He [8He/6He(0+)] =1 ;[8He/6He(2+)] =0.014mélange : (p3/2)4 + (p3/2)2 (p1/2)2
p n1s1/2
1p3/2
1p1/2
Structure de l’état fondamental & recherche d’états excités non liés
spectroscopie de particules légères chargées p,d,t (MUST) mesures des résonances de 8He NPA 788c, 260 (’07) distributions angulaires analyse en voies couplées des réactionsPLB 619. 82 (’05) ; 646, 222 (’07)
NCSM
Calculs en couches sans cœur (NCSM)validés
COSMA:Alpha+4n
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Evolution of the neutron skin thickness : ex of Neon isotopes
Density functional.calc. with R. Lombard’s code
Similar trend in HFB-def (Sly4) calc ofJ Dobaczewski, M.V. Stoitsov, et al., PRC68, 054312(‘03)
Direct reactions to unbound states ESNT 4-6Fev. 08 CEA-SPhN [email protected]
Neutron-skin structure of 34Ne via direct reactions on proton target
34Ne +p p’ + 34Ne* p + 32Ne + 2n p’ + 34Ne* p + 30Ne + 4n
34Ne(p,p’)34Ne*
20 22 24 26
32Ne
30Ne
34Ne N/Z=2.4 N
31,33Ne unbound
Sn
0+
2+
32Ne
S2n
1.63MeV1.97
S2n0+
2+
34Ne
Sn300keV
947
Searching for low-lying states unbound statesneutron excitations…
Weakly-bound nucleiSmall Sn, S2n