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Shell-model calculations of psd -shell nuclei Furong Xu School of Physics, Peking University. Introduction Shell-model calculations The role of nn interaction and configuration mixing in N=14 and 1 6 shell evolutions;
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Shell-model calculations of psd-shell nucleiFurongXuSchool of Physics, Peking University • Introduction • Shell-model calculations • Therole of nninteraction and configuration mixing in N=14 and 16 shell evolutions; 2. Increase model space with fitting a new effective interaction • Summary
Introduction T. Otsukaet al., PRL 105, 032501 (2010) N=16 N=14
0d3/2 0d3/2 16 1s1/2 1s1/2 14 0d5/2 0d5/2 8 8 0p1/2 0p1/2 6 6 0p3/2 0p3/2 proton neutron 2+ 2+
Doubly magic nature of 24O R.V.F. Janssens, Nature 459, 1069 (2009) C.R. Hoffman et al., PLB 672, 17 (2009) Shell-model calculations are very dependent on interactions used! R. Kanungoet al., PRL 102, 152501 (2009)
0d3/2 0d3/2 16 1s1/2 1s1/2 14 0d5/2 0d5/2 8 8 0p1/2 0p1/2 6 6 0p3/2 0p3/2 proton neutron Experiments: 0d3/2 neutrons unbound in C, N, O T. Otsukaet al., PRL 105, 032501 (2010) Unbound 0d3/2 1s1/2 C.R. Hoffman et al., PRL 100, 152502 (2008)
II. Shell-model calculations N=14 and 16 shell closures Otsukaet al., PRL 87, 082502 (2001). C.X. Yuan, C. Qi, F.R. Xu, NPA 883, 25 (2012)
Interaction matrix elements of couplings Vj=0 and Vj=2 + =0+ + =2+ core core V j=0= -2.82MeV V j=0= -2.12MeV core core V j=2= -1.00MeV V j=2= -0.82MeV
8 8 6 6 0d3/2 0d3/2 16 1s1/2 repulsive tensor 1s1/2 repulsive spin-orbit 14 0d5/2 0d5/2 attractive tensor 0p1/2 0p1/2 0p3/2 0p3/2 proton neutron The neutron-proton interaction reduced when going from oxygen to carbon attractive T. Otsukaet al., PRL 95, 232502 (2005)
0d3/2 16 1s1/2 14 repulsive LS 0d5/2 8 attractive tensor 0p1/2 0p1/2 6 6 0p3/2 0p3/2 proton neutron attractive , important!22O: small effect20C: big (1s1/2 and 0d5/2 degenerate) 8 C.X. Yuan, C. Qi, F.R. Xu, NPA 883, 25 (2012)
C, N, Owave-function analysis for g.s. N=14 core core N=14 Excited configurations are more important in C isotopes
16 p n 14 16 14
N=11 isotones: 5/2+, 3/2+inversion related to N=14 shell + 3/2+ 3/2+ core core
Carbon WBT (2011): M. Petri et al., PRL 107, 102501 (2009): Z. Elekeset al., PRC 79, 011302 (R) Calculation is sensitive to effective charges used.
C isotopes The effective charges taken from: H. Sagawa et al., PRC 70, 054316 (2004)
attractive tensor The gap is reduced with increasing neutrons on 0d5/2. This increases the proton excitation. WBT 0hω
Generally agree well, but still model dependent! Increase model space; Improve interaction.
III. Summary • Thenninteraction and configuration mixing play also important roles in shell evolutions of N=14, 16. • Large model space and suitable effective interaction are important factors as well.
Collaborators: C.X. Yuan C. Qi T. Otsuka T. Suzuki X.B. Wang N. Tsunoda
Thank you! NN2012 San Antonio, Texas 29 May, 2012