1. Explaining the large 48 Ca/ 46 Ca in the EK 1-4-1 meteorite through n-capture process Basic charateristics / abundance patterns of the EK 1-4-1 meteorite Astrophysical scenari to produce these abundances (  -rich freeze-out, n-capt  -decay process) Need to study the N=28 closed shell :  decay Neutron capture rates Use of (d,p) transfer reaction to : Simulate (n,  ) capture Constraint the neutron-density value to explain the large 48 Ca/ 46 Ca abundance ratio Study the evolution of the N=28 closed shell far from stability. Outlooks

2. Did you fall tonight ? No, why ? I heard a big ‘BANG’ ! Little story about the EK 1-4-1 inclusion of meteorite Allende meteorite: fell in 1969 weight 2t chondraneous carbide several CaAl-rich inclusions EK1-4-1 inclusion : spherical shape, white colour diametre 1cm Fusion temperature1500-1900K Correlated over-abundances in neutron rich 48 Ca- 50 Ti- 54 Cr- 58 Fe- 64 Ni Underabundance of 66 Zn, r process element present Nd, Sm (A~150) 48 Ca/ 46 Ca  250 (solar =53)

3. Mass Number A 64 Ni 48 Ca 66 Zn 64 Ni K.L. Kratz et al. Proc. Della Societa Astronomica Italiana 2000 Astrophysical scenarii S ~ T 3 /  Y e = Z/A SNIa  –rich freeze out 28 Si weak r-process

4. branching point for 10 21 cm -1 Understand the 48 Ca/ 46 Ca  250 isotopic ratio in EK 1-4-1  -decay lifetimes Short lifetimes in the N=28 43 P, 44 S, and 45 Cl nuclei, T 1/2 ( 48 Ar) ~500ms O. Sorlin et al. PRC 47 (1993), S. Grévy et al. PLB 594 (2004), L. Weismann et al. PRC 67 (2003) (n,  ) cross sections : use (d,p) reaction in the Ar chain around N=28 see Kraussmann et al. PRC 53 (1996) for 48 Ca

5. d p pp 28 f 7/2 p 3/2 p 1/2 f 5/2 46 Ar 28 Thesis work L. Gaudefroy Usefull parameters for (n,  ) cross section for DC : -energy of the states -spin values -spectroscopic factors 3/2 - 1/2 - 7/2 - 5/2 - (0.64) (0.82) (0.09) (0.23) 47 Ar F. Nowacki 46 Ar SnSn 0 1 2 3 4 5 E* [MeV] CN  CN 18 DC Capture on bound states in final nucleus - cross section depends on Q, ℓ and C 2 S. Neutron capture cross sections around N~28 in the Ar isotopic chain Use of 44,46 Ar (d,p) transfer reaction

6. CD 2 380  g.cm -2 40,44,46 Ar 11A.MeV, 20kHz GANIL/SPIRAL BEAM : ~ parallel optics ( size ~ 2 cm,  < 2mrad ) CATS CATS : -beam-tracking detector - Proton emission point. resolution : ~0.6 mm 10cm. (d,p) reactions with 40,44,46 Ar beams 170° 110° 8 modules MUST MUST : -Si Strip detector -Proton impact localisation resolution : 1 mm -Proton energy measurement. resolution : 50 KeV p SPEG 41,45,47 Ar Identification SPEG : Energy loss spectrometer : recoil ion identification transfert-like products

7. CATS MUST CATS MUST  lab E p (MeV) Focal Plane Position (mm.) 45 Ar 18+ 45 Ar 17+ Beam Stop unbound states in 45 Ar 17+

8. Excitation energy spectrum for 47 Ar N=28 gap : 4.47(8)MeV p 3/2 p 1/2 f 7/2 f 5/2 47 Ar spec. fact. ℓ=1 ℓ=3 [2p1t]

9. 3/2 - 1/2 - 7/2 - 5/2 - (0.59) (0.84) (0.17) (0.21) 47 Ar exp 46 Ar SnSn 0 1 2 3 4 E* [MeV] RC 18 DC s.f 5/2 - (0.46) ℓ=1 ℓ=3 ℓ=  3 (d,p) access to E*, s.f., spins derive (n,  ) stellar rates Direct capture (E1) with ℓ n = 0 on p states dominates Speed up neutron-captures at the N=28 closed shell Neutron capture rates on 44,46,48 Ar t n (ms) neutron density d n A=44 A=46 A=48 10 18 10 19 10 20 10 21 10 22 0.1 1 10 100 10 3 10 4 10 5 tt tt 10 6 48 Ca/ 46 Ca~250 In collab. with T.Rauscher

10. f 7/2 p 3/2 p 1/2 f 5/2 28 Decrease of the f and p spin-orbit splittings not predicted by mean field calculations The N=28 gap has decreased by 330(80) keV between Ca and Ar 47 Ar 18 51 Ti 49 Ca 0 -2 -4 -6 -8 -10 f 7/2 p 3/2 p 1/2 f 5/2 ?  [MeV] 28 20 Evolution of single particle energies at N=29 d 3/2 f 5/2 f 7/2  Tensor monopole interaction (T. Otsuka)  d 3/2 – ( f 7/2 -f 5/2 ) or/and Density dependence effect (J. Piekarewicz)  s 1/2 – ( p 1/2 -p 3/2 ) s 1/2 First evidence of the tensor force in nuclei !

11. Conclusions and Outlooks Use of (d,p) transfer reaction to study the N=28 shell closure : -weakening of the N=28 shell-gap (to be continued for lighter isotones) -Vanishing of the p 1/2 -p 3/2 spin-orbit splitting due to nuclear density term -Reduction of the f 7/2 – f 5/2 spin-orbit splitting due to tensor force -Determine spectroscopic information to determine (n,  ) -specific orbitals ( ℓ =0) with high spectroscopic factors, favors DC at N=28 - Find astrophysical conditions to produce 48 Ca in excess (d n ~10 21 cm -3 ). -Outlooks: -Look at time-dependent calculations -Extent the n-capture calculations to the Ti-Cr region genitors of 58 Fe, 64 Ni ( only f and g valence orbitals are present ) -Other anomaleous abundances: Presolar grains SiC type X, Mo/Zr : rôle of the N=56 subshell closure? Diamond grains, Te/Xe, rôle of the N=82 shell closure ?

12. Collaborators : L. Gaudefroy 1, D. Beaumel 1, Y.Blumenfeld 1, Z.Dombràdi 3, S. Fortier 1, S. Franchoo 1, M. Gélin 2, J. Gibelin 1,S. Grévy 2, F. Hammache 1, F. Ibrahim 1, K.Kemper 4, K.L. Kratz 5, S.M.Lukyanov 6,C. Monrozeau 1, L. Nalpas 7, F. Nowacki 8, A.N. Ostrowski 5, Yu.- E.Penionzhkevich 6,E. Pollaco 7, T. Rauscher 9, P. Roussel-Chomaz 2, E. Rich 1, J.A.Scarpaci 1,M.G. St. Laurent 2, D. Sohler 3, M. Stanoiu 1, E. Tryggestadt 1 and D. Verney 1 1 IPN, IN2P3-CNRS,F- 91406 Orsay Cedex, France 2 GANIL, BP 55027, F-14076 Caen Cedex 5, France 3 Institute of Nuclear Research, H-4001 Debrecen, Pf. 51, Hungary 4 Department of Physics, Florida State University, Tallahassee,Florida 32306, USA 5 Institut für Kernchemie, Universität Mainz, D-55128 Mainz, Germany 6 FLNR/JINR, 141980 Dubna, Moscow region, Russia 7 CEA-Saclay, DAPNIA-SPhN, F-91191 Gif sur Yvette Cedex, France 8 IReS, Univ. Louis Pasteur, BP~28, F-67037 Strasbourg Cedex, France 9 Dep. Of Physik and Astronomie, Universität Basel, CH4056 Switzeland

13. 3/2 - 1/2 - 5/2 - 7/2 - 3/2 - 7/2 - 5/2 - 9/2 - 1/2 - (0.64) (0.82) (0.01) (0.09) (0.02) (0.002) (0.23) 47 Ar F. Nowacki 46 Ar SnSn 0 1 2 3 4 5 E* [MeV] CN  CN 18 DC L. Gaudefroy, T. Rauscher Nuclear structure of 47 Ar favors s-wave Direct Capture Speed up the neutron captures at the N=28 closed shell (d,p) access to E*, spec. fact., spins, unbound states s.f Neutron capture on 46 Ar

14. E(keV) Origin of the deformation in the Cr isotopes - rôle of the p-n interaction - presence of j, j-2 valence levels - mid proton shell Large deformation in Cr: p 1/2 d 5/2 g 9/2 f 5/2 40 E2, M2 0 48 6 2 protons in  f 7/2 proton number N=40 34 NN time (a.u.) E2: T 1/2 ~ 1.6  s 59m Ti 37 22 shell model: F. Nowacki fpg Re-ordering of the levels in Ti - appearance of N=34 closed shell.

15. Mo, Zr anomalies in Si-C presolar grains 93 929091 9392 95969492 93 94 Zr Nb Mo 94 100 99 9798 959796 9899 95 96 9798 N=56 89 9190 92 939594 9697 Y i Mo/ 96 Mo s process i Zr/ 94 Zr s process Pellin et al. Lunar Plan. Sci. (2000) Neutron burst 10 17 cm -3 B. Meyer et al. Ap.J. L 540 (2000) The  g 9/2 - g 7/2 interaction makes the N=56 subshell closure vanish at Z=42 Different patterns observed in Zr and Mo Neutron burst

16. 127 126124125 127126 129130128 126 127 128 Te I Xe 128 134 133 131132 129 131 130 132 133 129 130 131132 123 125124 126 127129128 130131 Sb 136 135 134135 137 138 139 133134 132 127126 124 125128 129 130 122 123 Sn N=82 i Xe/ 130 Xe i Te/ 124 Te Xe Te Te, Xe anomalies in diamond grains r r r Neutron-rich scenario Influence of N=82 shell closure Abundances differ from solar r  Neutron burst?

17. Half-lives in the Ti isotopic chain NN t [s]

18. Half-lives in the Cr isotopic chain NN t [s]

19. f 5/2 g 9/2 neutrons f 7/2 p 3/2 p 1/2 28 protons (j p <) (j p >) (j n >) 50 d 5/2 78 Ni 42 Si and 78 Ni are mirror systems Hints for explaining the deformation in 42 Si Doubly magic numbers originating from spin-orbit interaction The size of the proton gaps is sensitive to the strength of the tensor monopole force The proton and neutron gaps have  ℓ=2 connections with valence states d 3/2 f 7/2 neutrons d 5/2 s 1/2 14 protons (j p <) (j p >) (j n >) 28 p 3/2 42 Si  ℓ=2

20. 28 Shell Model 2p 1f 2s 1d 20 H.O. + L²+ L.s 1g 50 40 Is it due to a weakening of N=28 shell closure ? Modification of the spin-orbit term, for which reason ? Many hints for the onset of collectivity at N=28 far from stability, below 48 Ca The N=28 shell closure