Yrast 6(+) Seniority Isomers of Sn-136,Sn-138

Simpson, GS; Gey, G; Jungclaus, A; Taprogge, J; Nishimura, S; Sieja, K; Doornenbal, P; Lorusso, G; Soederstroem, P-A; Sumikama, T; Xu, ZY; Baba, H; Browne, F; Fukuda, N; Inabe, N; Isobe, T; Jung, HS; Kameda, D; Kim, GD; Kim, Y-K; Kojouharov, I; Kubo, T; Kurz, N; Kwon, YK; Li, Z; Sakurai, H; Schaffner, H; Shimizu, Y; Suzuki, H; Takeda, H; Vajta, Z; Watanabe, H; Wu, J; Yagi, A; Yoshinaga, K; Boenig, S; Daugas, J-M; Drouet, F; Gernhaeuser, R; Ilieva, S; Kroell, T; Montaner-Piza, A; Moschner, K; Muecher, D; Naidja, H; Nishibata, H; Nowacki, F; Odahara, A; Orlandi, Riccardo; Steiger, K; Wendt, A

doi:10.1103/PhysRevLett.113.132502

Yrast 6(+) Seniority Isomers of Sn-136,Sn-138

Author:

Simpson, GS

Gey, G ; Jungclaus, A ; Taprogge, J ; Nishimura, S ; Sieja, K ; Doornenbal, P ; Lorusso, G ; Soederstroem, P-A ; Sumikama, T ; Xu, ZY ; Baba, H ; Browne, F ; Fukuda, N ; Inabe, N ; Isobe, T ; Jung, HS ; Kameda, D ; Kim, GD ; Kim, Y-K ; Kojouharov, I ; Kubo, T ; Kurz, N ; Kwon, YK ; Li, Z ; Sakurai, H ; Schaffner, H ; Shimizu, Y ; Suzuki, H ; Takeda, H ; Vajta, Z ; Watanabe, H ; Wu, J ; Yagi, A ; Yoshinaga, K ; Boenig, S ; Daugas, J-M ; Drouet, F ; Gernhaeuser, R ; Ilieva, S ; Kroell, T ; Montaner-Piza, A ; Moschner, K ; Muecher, D ; Naidja, H ; Nishibata, H ; Nowacki, F ; Odahara, A ; Orlandi, Riccardo ; Steiger, K ; Wendt, A

Keywords:

Science & Technology, Physical Sciences, Physics, Multidisciplinary, Physics, SHELL-MODEL CALCULATIONS, FISSION, RIKEN, IDENTIFICATION, SEPARATOR, BIGRIPS, SN-132, 01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering, General Physics, 40 Engineering, 49 Mathematical sciences, 51 Physical sciences

Abstract:

Delayed γ-ray cascades, originating from the decay of ð6þÞ isomeric states, in the very neutron-rich, semimagic isotopes 136;138Sn have been observed following the projectile fission of a 238U beam at RIBF, RIKEN. The wave functions of these isomeric states are proposed to be predominantly a fully aligned pair of f7=2 neutrons. Shell-model calculations, performed using a realistic effective interaction, reproduce well the energies of the excited states of these nuclei and the measured transition rates, with the exception of the BðE2; 6þ → 4þÞ rate of 136Sn, which deviates from a simple seniority scheme. Empirically reducing the νf2 7=2 orbit matrix elements produces a 4 þ 1 state with almost equal seniority 2 and 4 components, correctly reproducing the experimental BðE2; 6þ → 4þÞ rate of 136Sn. These data provide a key benchmark for shell-model interactions far from stability.