β decay of In133 : γ emission from neutron-unbound states in Sn

Abstract

Excited states in 133 Sn were investigated through the β decay of 133 In at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for 133 In, allowing us to study separately, and in detail, the β-decay branch of 133 In J π = (9/2 +) ground state and its J π = (1/2 −) isomer.

Detailed spectroscopy of doubly magic Sn132

“…The states located at 5766 and 5446 keV were previously observed in the β-delayed neutron emission of 133 In [16]. The assignment is confirmed in this work with the uncovering of new cascades in the 132 In decay involving both levels.…”

“…The large Q β = 13.4(2) MeV value along with the low neutron separation energy in 133 Sn, S n = 2.399(3) MeV [10], favor the 133 In decay via β-delayed neutron emission to 132 Sn. This gives rise to the large P n values for both 133 In β-decaying isomers [16]. The lower spin of the 133 In (9/2 + ) ground state and (1/2 − ) isomer, in comparison with 132 In (7 − ), is expected to favor the population of low spin p-h excited states that are not fed in the β decay of 132 In due to the large spin of the parent (7 − ).…”

“…The results from the β-decay study of the 133 In isomers have been partially covered in Ref. [16]. Details on the experimental method used in the present work are provided in Sec.…”

“…One of the signatures of its doubly magic nature is the high lying first-excited state at 4041.6 keV [1][2][3]. This value, once scaled by a factor of A 1/3 to account for the size of the nucleus, is large in comparison to other doubly magic nuclei such as 208 Pb and 16 O, which points to a strong double shell closure. The 132 Sn doubly magic structure is also manifested by the almost pure single-particle nature of the levels in 133 Sn.…”

“…[10] and the excitation spectra from 131 Sn, 133 Sn, 133 Sb, and 131 In. In particular, the neutron single-particle orbits above the N = 82 shell gap have been taken from low-lying states in 133 Sn: the ν f 7/2 ground state and the ν p 3/2 , ν p 1/2 , νh 9/2 , and ν f 5/2 states at 854-, 1367-, 1561-, and 2005-keV excitation energy [4,[11][12][13][14][15][16]. The νi 13/2 single-particle state has not been experimentally identified to date [17].…”