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Evolution of N=50 towards 78 Ni: recent inputs from experiments

Workshop Espace de Structure Nucléaire Théorique Saclay 3-5 May 2010. Evolution of N=50 towards 78 Ni: recent inputs from experiments. D. Verney, IPN Orsay. Introduction: recent progress in experiment north north-east to 78 Ni. 0.

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Evolution of N=50 towards 78 Ni: recent inputs from experiments

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  1. Workshop Espace de Structure Nucléaire Théorique Saclay 3-5 May 2010 Evolution of N=50 towards 78Ni: recent inputs from experiments D. Verney, IPN Orsay Introduction: recent progress in experiment north north-east to 78Ni 0 Position of the problem : why should we worry about N=50 ? 1 N=50 shell gap evolution: salient features from experimental data 2 deeper into nuclear structure close to 78Ni : valence space, single particle state effective sequence 3

  2. Introduction: recent progress in experiment north north-east to 78Ni 0

  3. N=50 : recent experimental breakthrough Experimental status in year 2003 Zr90 Zr91 Z=40 Y89 Sr84 Sr86 Sr87 Sr88 Rb85 Rb87 Kr78 Kr80 Kr82 Kr83 Kr84 Kr85 Kr86 Br79 Br81 Br85 Se74 Se75 Se76 Se77 Se78 Se79 Se80 Se81 Se82 Se83 Se84 As75 As83 Ge70 Ge72 Ge73 Ge74 Ge76 Ge82 Ga69 Ga71 Ga79 Ga80 Ga81 Zn66 Zn67 Zn68 Zn70 Zn75 Zn76 Zn77 Zn78 Zn80 Cu65 Cu74 Cu79 Ni64 Ni65 Ni66 Ni67 Ni68 Ni69 Ni70 Ni71 Ni72 Ni73 Ni74 Ni75 Ni76 Ni77 Ni78 28 50 N=40 main nuclear mechanisms used : -fragmentation of stable beams -fission b-decay (d,3He) Zendel et al Inorg Nucl Chem 42, 1387 (1980) (t,p) Chimical separation Kratz et al Nucl Phys A 250, 13 (1975) Del Marmol et al Nucl Phys A 194, 140 (1972) fission Hoff -Fogelberg Nucl Phys A 368, 210 (1981) OSIRIS /Studsvik fragmentation Ge83 Winger et al Phys Rev C 36, 758 (1987) On-line mass separation TRISTAN /Brookhaven Beginning of b-decay studies at PARRNe « border » of the knowledge on nuclear structure First structure data (g’s) came from b-decay (for N=50) 1 Fission + ISOL technique D. Verney Page 3/52 ESNT Workshop – Saclay – 3-5 May 2010

  4. N=50 : recent experimental breakthrough Experimental status in year 2010 main nuclear mechanisms used : -fragmentation of stable beams -fission -deep inelastic collisions Zr90 Zr91 Z=40 Y89 Sr84 Sr86 Sr87 Sr88 Rb85 Rb87 Kr78 Kr80 Kr82 Kr83 Kr84 Kr86 Br79 Br81 Br85 b -decay Orsay b -decay Orsay Se74 Se76 Se77 Se78 Se80 Se82 Se84 Se85 Se86 As84 As75 As83 direct reaction in inverse kinematics : Oak Ridge Ge70 Ge72 Ge73 Ge74 Ge76 Ge82 Ge83 Ge84 Ga69 Ga71 Ga81 DIC at Legnaro DIC at Legnaro Fusion-fission Spontaneous fission Zn66 Zn67 Zn68 Zn70 Zn80 Zn78 Zn79 radioactive beam: REX ISOLDE Cu65 Cu79 Cu77 Ni64 Ni65 Ni66 Ni67 Ni68 Ni69 Ni70 Ni71 Ni72 Ni73 Ni74 Ni75 Ni76 Ni77 Ni78 28 ISOLDE laser JYFLTRAP IGISOL 50 isomeric decay: LISE-GANIL b-decay is still in the competition, good complementarities with DIC 2 Fission + ISOL technique + post acceleration BE(2) Spectroscopic factors D. Verney Page 4/52 ESNT Workshop – Saclay – 3-5 May 2010

  5. Position of the problem : why should we worry about N=50 ? 1

  6. Why should we worry about N=50 ? Historically from astrophysical considerations (and b-decay experiments) 1 By Winger et al. PRC 36 (1987) By Kratz et al. PRC 38 (1988) «  »  « it’s a joke » M. Bernas, private communication (2001) Waiting point nucleus at N=50 80Zn D. Verney Page 6/52 ESNT Workshop – Saclay – 3-5 May 2010

  7. Why should we worry about N=50 ? ground state of 42Si N=28 is observed deformed B. Bastin et al., Phys. Rev. Lett. 99 (2007) 022503 spin-orbit origin “A full treatment of Hm shows no magicity at 30Ne and 32Mg, while 34Si (or any other Si isotope) exhibits a clear shell effect. It just so happens that the full Hm reproduces the observed robustness of the SO closures, and the fragility of those of other origins. Whether they survive or not depends mainly on the possibility of developing quadrupole coherence in a given space.” A.P. Zuker PRL 91 (2003) D. Verney Page 7/52 ESNT Workshop – Saclay – 3-5 May 2010

  8. Why should we worry about N=50 ? O. Sorlin, M. Porquet Prog. Part. Nucl. Phys. 61 (2008) 602 T. Otsuka et al. PRL95, 232502 (2005) 78Ni 56Ni 100Sn 44 48 46 50 N=50 gap extrapolation → 78Ni =3.0(5) MeV 78Ni from binding energies of the states below and above Z=28 and N=50 Z=28 gap extrapolation → 78Ni =2.5 MeV D. Verney Page 8/52 ESNT Workshop – Saclay – 3-5 May 2010

  9. Why should we worry about N=50 ? extracted from J. Van de Walle et al PRC 70 (2009) 014309 Their is a N=50 shell effect with strong influence on nuclear structure close to 78Ni Now, the real question becomes : how the shell gap associated to the N=50 magic number evolves towards 78Ni or is there any evolution at all ? D. Verney Page 9/52 ESNT Workshop – Saclay – 3-5 May 2010

  10. N=50 shell gap evolution: prominent features from experimental data 2

  11. Evolution of the N=50 shell gap d5/2 + 50 g9/2 g9/2 + + 40 p1/2 p1/2 p3/2 - p3/2 - f5/2 f5/2 28 f7/2 f7/2 protons neutrons Yrast structure studies (fusion-fission mechanism) A Prévost et al. EPJ A 22 (2004) 391 Medium/high spin states obtained from fusion/fission at the Vivitron (Euroball IV) conclusion : N=50 shell gap decrease : yes D. Verney Page 11/52 ESNT Workshop – Saclay – 3-5 May 2010

  12. Evolution of the N=50 shell gap Yrast structure studies (spontaneous fission mechanism) T. Rza˛ca-Urban et al. PRC 76 (2007) 027302 Medium/high spin states fed in 248Cm spontaneous fission conclusion : N=50 shell gap decrease : yes 2 levels added : one of the two “must be” 1p-1h across N=50 32 D. Verney Page 12/52 ESNT Workshop – Saclay – 3-5 May 2010

  13. Evolution of the N=50 shell gap Yrast structure studies (deep inelastic mechanism) Y.H. Zhang et al. PRC 70 (2004) 024301 Medium/high spin states fed in DIC at Legnaro (GASP) conclusion : N=50 shell gap decrease : no (same conclusion as Kamila) The gap used in the calculation has the good size d5/2 50 4 MeV g9/2 g9/2 84Se p1/2 p1/2 p3/2 f5/2 SM calculation proton valence space + neutron 1ph SM calculation proton valence space 28 f7/2 protons neutrons D. Verney Page 13/52 ESNT Workshop – Saclay – 3-5 May 2010

  14. Evolution of the N=50 shell gap Mass measurements (IGISOL Jyvaskyla) D. Verney Page 14/52 ESNT Workshop – Saclay – 3-5 May 2010

  15. Evolution of the N=50 shell gap Mass measurements (IGISOL Jyvaskyla) D=S2n(52)-S2n(50) (this quantity is the one traditionnally used to extract shell gaps from mass measurements) Local minimum at Z=32 D. Verney Page 15/52 ESNT Workshop – Saclay – 3-5 May 2010

  16. Evolution of the N=50 shell gap Mass measurements : what quantity is truly relevant for nuclear structure NPA466 (1987) 189 ejn Z gap in the single particle levels 50 Sn(Z,N)-Sn(Z,N+1) ej’n Sn(Z,N)-Sn(Z,Nextr) n Koopmans theorem : -ej’n= Sn(Z,N) N+5 N+7 N N+3 N+1 neutron number but Sn(Z,N+1) is not a good prescription for for the evaluation of ejn one has to estimate ej’n and ejn in the same nucleus ejn—ej’n = Sn(Z,N) —Sn(Z,Nextr) then the good prescription becomes : D. Verney Page 16/52 ESNT Workshop – Saclay – 3-5 May 2010

  17. Evolution of the N=50 shell gap Mass measurements : what quantity is truly relevant for nuclear structure using data taken from mass evaluation 2010 with kind authorization by G. Audi (AME2010 unpublished - G. Audi private communication) neutron pairing gain = 2Sn(Z,N+1) —S2n(Z,N+2) Duflo Zuker gap 78Ni =5,7 MeV Duflo Zuker gap PRC59 (1999) 90Zr =4,7 MeV AME2010 extrapolation gap « rough » pairing gain(MeV) « prescripted » gap ed5/2 – eg9/2 (MeV) local minimum at Z=32 Ge Se Zn Kr Sr Ni conclusion : N=50 becomes somewhat “porous” relative to pair promotions (towards 78Ni) • what will be the result on structure? • what is the microscopic mechanism at play which could explain this local minimum ? Zn Ge Ni Se Kr Sr Zr D. Verney Page 17/52 ESNT Workshop – Saclay – 3-5 May 2010

  18. Evolution of the N=50 shell gap in particular : could provide a simple explanation to the Yrast structure behavior 32 D. Verney Page 18/52 ESNT Workshop – Saclay – 3-5 May 2010

  19. Evolution of the N=50 shell gap and also the peculiar evolution of the E(2+) of the even-even N=50 isotones Local minimum, not at mid distance Z=28-40 90Zr 88Sr 86Kr 84Se 80Zn 82Ge J. Van de Walle et al. PRL 99, 142501 (2007) REX-ISOLDE D. Verney Page 19/52 ESNT Workshop – Saclay – 3-5 May 2010

  20. Evolution of the N=50 shell gap from b-decay at ALTO 52 D. Verney Page 20/52 ESNT Workshop – Saclay – 3-5 May 2010

  21. Evolution of the N=50 shell gap 0 0 0 0 0 0 0 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.4 O Perru thesis Paris-Sud XI (2004) & J. Libert and M. Girod private communication D1S Gogny HFB calculation GCM  Bohr dynamics N=44 N=42 and connection with collectivity Ge isotopic chain N=48 N=46 N=50 N=52 N=54 D. Verney Page 21/52 ESNT Workshop – Saclay – 3-5 May 2010

  22. Evolution of the N=50 shell gap and connection with collectivity Ge HFB + GCM (GOA) D. Verney Page 22/52 ESNT Workshop – Saclay – 3-5 May 2010

  23. Collectivity close to 78Ni Evolution of the N=50 shell gap N=52 even-even nuclei and connection with collectivity Z=40 subshell effect N=52 Z=28 shell closure D. Verney Page 23/52 ESNT Workshop – Saclay – 3-5 May 2010

  24. deeper into nuclear structure close to 78Ni : valence space, single particle state effective sequence 3

  25. Proton structure above 78Ni Proton structure above 78Ni K. Flanagan et al. E (MeV) Proton single particles 50 -7,121 g9/2 40 -11,831 but already hinted at in the 80’s !! (from shell model, empirical interaction) p1/2 -13,233 p3/2 N=46 N=48 N=44 N=40 N=42 N=50 f5/2 -14,386 28 From Ji et Wildenthal Phys. Rev. C 38, 2849 (1988) D. Verney Page 25/52 ESNT Workshop – Saclay – 3-5 May 2010

  26. Proton structure above 78Ni shell model calculation : Ji et Wildenthal Phys. Rev. C 38, 2849 (1988) TBME and SP energies fitted to the data E (MeV) Proton single particles 50 -7,121 g9/2 Kr 40 Se Ge -11,831 p1/2 Zn -13,233 p3/2 f5/2 -14,386 28 D. Verney Page 26/52 ESNT Workshop – Saclay – 3-5 May 2010

  27. Proton structure above 78Ni A. Pfeiffer et al. NPA 455 (1986) 381 E (MeV) Proton single particles 50 -7,121 g9/2 40 -11,831 p1/2 -13,233 p3/2 f5/2 -14,386 28 From Ji et Wildenthal Phys. Rev. C 38, 2849 (1988) D. Verney Page 27/52 ESNT Workshop – Saclay – 3-5 May 2010

  28. Proton structure above 78Ni PARRNe Zr96 Zr94 Zr95 Zr92 Zr93 Zr92 Zr93 Zr90 Zr91 Y89 81 3 protons out of a 78Ni core Ga Sr88 31 50 Rb87 Kr86 Br85 Se84 Se85 Se86 1236 (9/2-) As83 As84 observed in b-decay at Orsay (PARRNe) D. Verney et al PRC 76 (2007) 054312 Ge82 Ge83 Ge84 Ga81 Zn81 Zn80 hot subject - b-decay experiment redone at ISOLDE and Oak Ridge (same lines as us) Cu79 Ni78 50 observed in DIC experiments at Legnaro G. De Angelis et al. NPA 787 (2007) 74c D. Verney Page 28/52 ESNT Workshop – Saclay – 3-5 May 2010

  29. Proton structure above 78Ni keV 83As Z=33 N=50 1800 9/2- 1985 keV 3/2- 7/2- 1977.9 keV 1879 keV 1897 keV 1/2- 3/2- 1857 keV 1600 1804.76 keV 1845 keV 9/2- 1643 keV 1400 1525.52 keV 5/2- 1434.92 keV 1455 keV 5/2- 1/2- 1415.11 keV 1200 1368 keV 1382 keV 1329.87 keV 1/2- 1279 keV 3/2- 1253 keV 1256.76 keV 1000 5/2- 1196.53 keV 1115 keV 1193.7 keV 7/2- 990 keV 800 600 3/2- 711.66 keV 679 keV 3/2- 589 keV 400 (3/2-) 1/2- 353 keV 306.51 keV 200 3/2- 189 keV 5/2- 64 keV 0 3/2- 0 keV 5/2- 0 keV 0 keV (5/2-) Theory Experiment Theory Ji & Wildenthal, PRC 40, 389 (1989) Winger et al, PRC 38, 285 (1988) 81Ga Z=31 N=50 (9/2-) 1236 keV (3/2-) 802.8 keV 451.7 keV (3/2-) 351.1 keV 351.1 keV (5/2-) 0 keV Experiment empirical effective interaction : fit on a series of carefully selected states Valence space N=50 closed & Z=28 closed (the doubly magical nature of 78Ni is assumed) The valence space is reduced to proton orbitals D. Verney Page 29/52 ESNT Workshop – Saclay – 3-5 May 2010

  30. Proton structure above 78Ni what to do ? remember the textbooks and assume p1f5/2 is indeed the first proton orbit filled above 78Ni for identical particles in j<=7/2 there exists a closed formula expressing the configuration energy (by Talmi) Talmi : <VJ>= seniority number single particle (binding) energy number of particles in the configuration 82Ge 81Ga 80Zn (p1f5/2)4 (p1f5/2)3 (p1f5/2)2 n=2, =0 n=3, =3 n=4, =0 n=2, =2 n=3, =1 BE(f5/2)= -13.576 MeV………JW give -14.386 MeV 1492 keV 3/2+ 2+ 803 keV E(9/2-) in 81Ga=1250 keV ……experiment :1236 keV 5/2+ E(4+) in 80Zn=1809 keV ………experiment :? 0+ but also extract : <f5/2f5/2|V|f5/2f5/2>J=0 <f5/2f5/2|V|f5/2f5/2>J=2 <f5/2f5/2|V|f5/2f5/2>J=4 0+ D. Verney Page 30/52 ESNT Workshop – Saclay – 3-5 May 2010

  31. Proton structure above 78Ni f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 f5/2 back to the Ji Wildenthal proton-proton residual interaction : pairing looks small ! Is it possible to find a simple cure to the interaction ? D. Verney Page 31/52 ESNT Workshop – Saclay – 3-5 May 2010

  32. Proton structure above 78Ni Ji & Wildenthal, PRC 40, 389 (1989) Z=31 N=50 A.F. Lisetskiy et al., PRC 70 (2004) v=3(pf5/2)3 1qp pp3/2 1qp pf5/2 JW+rustine D. Verney Page 32/52 ESNT Workshop – Saclay – 3-5 May 2010

  33. Proton structure above 78Ni A.F. Lisetskiy et al., PRC 70 (2004) Z=33 N=50 Ji & Wildenthal, PRC 40, 389 (1989) 1qp pp1/2 711 keV 1qp pf5/2 1qp pp3/2 JW+rustine D. Verney Page 33/52 ESNT Workshop – Saclay – 3-5 May 2010

  34. Proton structure above 78Ni Z=35 N=50 1qp pp1/2 1qp pf5/2 1qp pp3/2 JW+rustine D. Verney Page 34/52 ESNT Workshop – Saclay – 3-5 May 2010

  35. Proton structure above 78Ni the conclusion is : this proton sequence is confirmed and the observed structure of the odd-proton N=50 isotones simply (and naturally) reflects the change of the Fermi level E (MeV) 2p1/2 2p1/2 2p1/2 Proton single particles 50 -7,121 g9/2 2p3/2 2p3/2 2p3/2 40 -11,831 p1/2 1f5/2 1f5/2 1f5/2 -13,233 p3/2 81Ga Z=31 N=50 83As Z=33 N=50 85Br Z=35 N=50 f5/2 -14,386 28 From Ji et Wildenthal Phys. Rev. C 38, 2849 (1988) D. Verney Page 35/52 ESNT Workshop – Saclay – 3-5 May 2010

  36. Neutron structure above 78Ni SM calculations in valence space above 78Ni THEORY (SM) EXPERIMENT K. Sieja et al. PRC 79, 064310 (2009) 89Sr g7/2 nearly constant g7/2 goes up 91Zr From Duflo Zuker PRC 59, R2347 (1999) O. Sorlin, M. Porquet Prog. Part. Nucl. Phys. 61 (2008) 602 centroides from (d,p) g7/2 goes down D. Verney Page 36/52 ESNT Workshop – Saclay – 3-5 May 2010

  37. Neutron structure above 78Ni experiment and theory agree close to stability in 89Sr E (MeV) Neutron single particles 82 ? h11/2 g7/2 3.04 2.45 d3/2 s1/2 1.00 d5/2 0.00 50 From T.A. Hughes Phys. Rev. 181, 1586 (1969) but in fact the problem of the position of h11/2 remains unsolved → need for the observation of negative parity Yrast states in N=51 D. Verney Page 37/52 ESNT Workshop – Saclay – 3-5 May 2010

  38. Neutron structure above 78Ni Zr96 Zr94 Zr95 Zr92 Zr93 Zr92 Zr93 experiment and theory agree close to stability ? Zr90 Zr91 Y89 83 Ge 4 protons + 1 neutron au dessus de 78Ni Sr88 32 51 Rb87 Kr86 Br85 Se84 Se85 Se86 As83 As84 observé en décroissance b-decay à PARRNe O. Perru et al. EPJ A 28 (2006) 307 et thèse Paris 11 Ge82 Ge83 Ge84 Ga83 Ga84 Ga81 Zn80 (3/2,5/2+) Cu79 Ni78 observé en décroissance bn avec ALTO M. Lebois et al. PRC 80 (2009) 044308 et thèse Paris 11 7/2+ 50 1/2+ observé en2H(82Ge,p)83Ge à Oak Ridge Thomas et al. PRC 71 (2005) 021302 247.8 n3s1/2 n2d5/2 D. Verney Page 38/52 ESNT Workshop – Saclay – 3-5 May 2010

  39. Neutron structure above 78Ni systematics for the odd-neutron N=51 isotones (1/2+)? E(2+) of the even-even core(semi-magic N=50) D. Verney Page 39/52 ESNT Workshop – Saclay – 3-5 May 2010

  40. Neutron structure above 78Ni Even-even semi-magic core Q>0 Q=0 Q<0 single particle J=1/2 J=9/2 J=3/2 2+1 2d5/2 J=5/2 J=7/2 D. Verney Page 40/52 ESNT Workshop – Saclay – 3-5 May 2010

  41. Neutron structure above 78Ni N=51 (1/2+)? E(2+) of the even-even core(semi-magic N=50) D. Verney Page 41/52 ESNT Workshop – Saclay – 3-5 May 2010

  42. Neutron structure above 78Ni first 7/2 state is 2+*d5/2 coupled state, g7/2 is higher in energy from J. S. Thomas et al.PRC 76, 044302 (2007) S=0.84 S=0.49 d3/2 S=0.06±0.02 g7/2 S=0.77±0.27 (1/2+)? S=0.016 non-stripped not observed in (d,p) D. Verney Page 42/52 ESNT Workshop – Saclay – 3-5 May 2010

  43. Neutron structure above 78Ni down sloping of the s1/2 is firmly established d’après J. S. Thomas et al.PRC 76, 044302 (2007) S=0.18 non-stripped (1/2+)? not observed (dp) S=0.905 s1/2 S=0.46 S=0.31 S=0.52 s1/2 s1/2 s1/2 D. Verney Page 43/52 ESNT Workshop – Saclay – 3-5 May 2010

  44. L. S. Kisslinger & R. A. Sorensen Rev. Mod. Phys., 35, 853, (1963) Neutron structure above 78Ni how to extract (at least approximately) effective single particle energies when no direct reaction data is available ? use a simple empirical model Core – particle coupling model Thankappan & True Phys. Rev. B, 137, 793 (1965) Neutron single particle Even-even semi-magic core Vector space : 0+1 2d5/2 2+1 2d5/2 2+1 3s1/2 Etc… Core excitation energies taken from experiment : E(2+) c2 c1 = Parameters : = Quadrupole moment of the 2+ state  Phenomenological model with a clear underlying physical image. All parameters with straightforward interpretation: Example : harmonic vibrator : Q2+=0  c2=0 D. Verney Page 44/52 ESNT Workshop – Saclay – 3-5 May 2010

  45. 89Sr t1/2 calculated assuming only M1 and E2 transitions e(n)=1 and gs=0.6 gsfree core-particle coupling experiment Qcalc= -0.27 eb mcalc= -1.020 n.m. Qexp= -0.28(3) eb / -0.32(2) ebmexp= -1.1481 n.m. not included in the model space S=0.84 S=0.74 S=0.34 S=0.15 0.21ps 0.09ps S=0.64 0.10ps 0.02ps S=0.46 0.19ps S=0.053 0.16ps S=0.091 0.11ps 0.26ps S=0.016 d2=0.87 (M1+E2) d2=0.56 (M1+E2) >1 ps S=0.78 1.85ps S=0.905 1 9 5 5 7 7 5 3 7 5 1 5 5 1 7 5 3 3 3 1 9 7 5 3 1 7 1 3 5 9 3 9 3 7 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0+ d3/2 0+ g7/2 2+ s1/2 2+ d5/2 0+ d5/2 02+ d5/2 0+ s1/2 22+ d5/2 S=0.79 S=0.88 theory unperturbed experiment

  46. 87Kr S=0.03 S=0.84 S=0.49 S=0.3 11 S=0.27 2 S=0.18 S=0.43 S=0.09 S=0.02 S=0.06 S=0.02 S=0.23 S=0.20 S=0.68 3 9 7 5 5 5 5 1 3 1 1 5 7 1 3 7 3 3 9 7 3 5 5 9 5 7 9 9 3 5 1 3 3 3 9 7 7 5 5 3 1 1 7 5 5 13 11 S=0.46 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0+ d5/2 0+ s1/2 2+ s1/2 0+ d3/2 0+ g7/2 2+ d5/2 22+ d5/2 4+ d5/2 S=0.90 S=0.56 theory unperturbed experiment

  47. 85Se ? 11 11 13 ? 2 2 2 ? - 7 ? 1 2 ? 2 S=0.09 S=0.77 or 0.06 S=0.86 5 7 3 5 5 3 7 1 9 5 7 5 3 3 9 5 1 3 3 3 3 5 9 7 1 7 5 9 9 1 1 7 7 5 5 5 9 3 5 3 7 1 1 3 13 11 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 S=0.31 0+ g7/2 0+ d5/2 0+ s1/2 0+ d3/2 2+ s1/2 2+ d5/2 02+ d5/2 4+ d5/2 S=0.90 S=0.38 theory unperturbed experiment

  48. Neutron structure above 78Ni on the overall neutron single particle sequence appears to be : g7/2 d3/2 s1/2 d5/2 D. Verney Page 48/52 ESNT Workshop – Saclay – 3-5 May 2010

  49. Neutron structure above 78Ni if we extract the effective single particle energies using the core-particle coupling model : MeV g7/2 d3/2 s1/2 N=58 ? d5/2 conclusion : appearance of a new neutron subshell gap close to 78Ni ? D. Verney Page 49/52 ESNT Workshop – Saclay – 3-5 May 2010

  50. Neutron structure above 78Ni is there a simple explanation to the s1/2 down sloping ? MeV g7/2 ? d3/2 N=58 ? s1/2 d5/2 D. Verney Page 50/52 ESNT Workshop – Saclay – 3-5 May 2010

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