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Explaining the large 48 Ca/ 46 Ca in the EK 1-4-1 meteorite through n-capture process

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 ( a -rich freeze-out, n-capt b -decay process) Need to study the N=28 closed shell :

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Explaining the large 48 Ca/ 46 Ca in the EK 1-4-1 meteorite through n-capture process

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  1. Explaining the large 48Ca/46Ca 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 (a-rich freeze-out, n-capt b-decay process) Need to study the N=28 closed shell : b decay Neutron capture rates Use of (d,p) transfer reaction to : Simulate (n,g) capture Constraint the neutron-density value to explain the large 48Ca/46Ca abundance ratio Study the evolution of the N=28 closed shell far from stability. Outlooks

  2. Little story about the EK 1-4-1 inclusion of meteorite No, why ? I heard a big ‘BANG’ ! Did you fall tonight ? 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-abundancesinneutron rich 48Ca-50Ti-54Cr-58Fe-64Ni • Underabundance of 66Zn, r process element present Nd, Sm (A~150) 48Ca/46Ca250 (solar=53)

  3. weak r-process Astrophysical scenarii SNIa a –rich freeze out 28Si 66Zn 64Ni 64Ni 48Ca 66Zn Mass Number A Mass Number A S ~ T3/r Ye = Z/A K.L. Kratz et al. Proc. Della Societa Astronomica Italiana 2000

  4. Understand the 48Ca/46Ca250 isotopic ratio in EK 1-4-1 b-decay lifetimes Short lifetimes in the N=28 43P, 44S, and 45Cl nuclei, T1/2 (48Ar) ~500ms O. Sorlin et al. PRC 47 (1993), S. Grévy et al. PLB 594 (2004), L. Weismann et al. PRC 67 (2003) (n,g) cross sections : use (d,p) reaction in the Ar chain around N=28 see Kraussmann et al. PRC 53 (1996) for 48Ca branching point for 1021cm-1

  5. p d qp f5/2 p1/2 p3/2 28 f7/2 46Ar28 Neutron capture cross sections around N~28 in the Ar isotopic chain E* [MeV] Use of 44,46Ar (d,p) transfer reaction <s>CN 5 CN Sn 46Ar 4 18 DC 3 5/2- (0.23) Usefull parameters for (n,g) cross section for DC : -energy of the states -spin values -spectroscopic factors 2 (0.09) 7/2- (0.82) 1/2- 1 (0.64) 3/2- 0 47Ar F. Nowacki Capture on bound states in final nucleus - cross section depends on Q,ℓand C2S. Thesis work L. Gaudefroy

  6. (d,p) reactions with 40,44,46Ar beams CD2 380mg.cm-2 8 modules MUST 10cm. p SPEG 40,44,46Ar 11A.MeV, 20kHz GANIL/SPIRAL 170° 41,45,47Ar CATS 110° Identification BEAM : ~ parallel optics (size ~ 2 cm , Dq < 2mrad) MUST : -Si Strip detector -Proton impactlocalisation resolution : 1 mm -Proton energy measurement. resolution : 50 KeV CATS : -beam-tracking detector - Proton emission point. resolution : ~0.6 mm SPEG : Energy loss spectrometer : recoil ion identification transfert-like products

  7. Focal Plane Position (mm.) 45Ar18+ 45Ar17+ MUST MUST CATS unbound states in 45Ar17+ Ep (MeV) CATS Beam Stop qlab

  8. Excitation energy spectrum for 47Ar spec. fact. N=28 gap : 4.47(8)MeV spec. fact. p3/2 47Ar ℓ=3 p1/2 f5/2 f7/2 [2p1t] ℓ=3 ℓ=1 ℓ=1

  9. Neutron capture rates on 44,46,48Ar E* [MeV] tn (ms) 106 ℓ=3 46Ar 4 A=48 105 RC 18 Sn 104 (0.46) A=46 5/2- tb 3 103 A=44 DC ℓ=3 (0.21) 5/2- tb 100 2 10 (0.17) 7/2- 1 (0.84) 1/2- 1 0.1 48Ca/46Ca~250 ℓ=1 (0.59) 3/2- 0 47Ar exp 1018 1019 1020 1021 1022 s.f neutron density dn (d,p) access to E*, s.f., spins derive (n,g) stellar rates Direct capture (E1) with ℓn = 0 on p states dominates Speed up neutron-captures at the N=28 closed shell In collab. with T.Rauscher

  10. e [MeV] Evolution of single particle energies at N=29 0 f5/2 f5/2 ? -2 f5/2 f7/2 p1/2 p3/2 d3/2 -4 s1/2 p1/2 p n Tensor monopole interaction (T.Otsuka) pd3/2 –n( f7/2-f5/2 ) or/and Density dependence effect (J.Piekarewicz) ps1/2 – n( p1/2-p3/2 ) -6 28 p3/2 28 -8 f7/2 28 -10 f7/2 47Ar 51Ti 49Ca 18 20 The N=28 gaphas decreased by 330(80) keV between Ca and Ar Decrease of the f and pspin-orbit splittingsnot predicted by mean field calculations 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 p1/2-p3/2 spin-orbit splitting due to nuclear density term • Reduction of the f7/2 – f5/2 spin-orbit splitting due to tensor force • Determine spectroscopic information to determine (n,g) • specific orbitals (ℓ=0) with high spectroscopic factors, favors DC at N=28 • Find astrophysical conditions to produce 48Ca in excess (dn ~1021cm-3). • Outlooks: • Look at time-dependent calculations • Extent the n-capture calculations to the Ti-Cr region genitors of 58Fe, 64Ni • (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. Gaudefroy1, 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. Rauscher9 , 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. Neutron capture on 46Ar E* [MeV] <s>CN 5 CN Sn 4 46Ar 18 DC 1/2- 9/2- 9/2- 3 (0.23) 5/2- (0.002) 7/2- 2 (0.02) 3/2- (0.09) 7/2- (0.82) 1/2- (0.01) 5/2- 1 (0.64) 3/2- 0 47Ar F. Nowacki s.f L. Gaudefroy, T. Rauscher Nuclear structure of 47Ar 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

  14. shell model: F. Nowacki protons in pf7/2 6 0 2 4 8 N=40 E2, M2 d5/2 fpg g9/2 34 40 p1/2 f5/2 proton number Origin of the deformation in the Cr isotopes Ng Large deformation in Cr: 59mTi37 E2: T1/2 ~ 1.6 ms 22 • rôle of the p-n interaction • presence of j, j-2 valence levels • mid proton shell Re-ordering of the levels in Ti - appearance of N=34 closed shell. time (a.u.) E(keV)

  15. Mo, Zr anomalies in Si-C presolar grains Pellin et al. Lunar Plan. Sci. (2000) Neutron burst iZr/94Zr iMo/96Mo s process s process 97 98 99 100 92 93 94 95 96 Mo Neutron burst 1017cm-3 B. Meyer et al. Ap.J. L 540 (2000) The pg9/2-ng7/2 interaction makes the N=56 subshell closure vanish at Z=42 Different patterns observed in Zr and Mo Nb 91 92 93 94 95 96 97 98 99 Zr 90 91 92 93 94 97 98 95 96 89 90 91 Y 92 93 94 95 96 97 N=56

  16. Te, Xe anomalies in diamond grains 133 139 127 135 137 131 132 134 136 138 128 129 130 126 Xe 133 131 I 132 134 135 126 127 128 129 130 125 Te 124 125 126 127 128 131 132 133 134 129 130 132 123 124 125 130 131 Sb 126 127 128 129 Sn 122 123 124 125 126 127 128 129 130 N=82 Te Xe iTe/124Te iXe/130Xe 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 Nb t [s]

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

  19. Hints for explaining the deformation in 42Si p3/2 d5/2 28 50 Dℓ=2 f7/2 (jn>) g9/2 (jn>) neutrons p1/2 d3/2 neutrons (jp<) s1/2 f5/2 (jp<) p3/2 Dℓ=2 14 28 d5/2 (jp>) f7/2 (jp>) protons protons 42Si 78Ni 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 Dℓ=2 connections with valence states 42Si and 78Ni are mirror systems

  20. Shell Model 1g 50 40 2p 1f 28 20 20 2s 1d H.O. + L² + L.s 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 48Ca The N=28 shell closure

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