Mass measurements of neutron-rich indium isotopes toward the N=82 shell closure

Abstract

Precise mass measurements of the neutron-rich 125−130 In isotopes have been performed with the TITAN Penning trap mass spectrometer. TITAN's electron beam ion trap was used to charge breed the ions to charge state q = 13+ thus providing the necessary resolving power to measure not only the ground states but also isomeric states at each mass number. In this paper, the properties of the ground states are investigated through a series of mass differentials, highlighting trends in the indium isotopic chain as compared to its proton-magic neighbor, tin (Z = 50). In addition, the energies of the indium isomers are presented. The (8 −) level in 128 In is found to be 78 keV lower than previously thought and the (21/2 −) isomer in 127 In is shown to be lower than the literature value by more than 150 keV.

β decay of Cd127 and excited states in In127Lorenz1, Sarmiento2, Rudolph3 et al. 2019Phys. Rev. C100110View full textAdd to dashboardCite

“…The resulting excitation energy of the (1/2 − ) isomer is 408.0(3) keV. This is in very good agreement with the value of 408.9(3) keV suggested by Arndt et al [14,15] and recent mass measurements, which reported an excitation energy of 390 (18) keV [17].…”

“…The result agrees well with the value of 420(65) keV reported by Gausemel et al [16]. A recent mass measurement yielded a consistent excitation energy of 390 (18) keV [17]. In addition to the 1/2 − isomer, another β-decaying isomer at 1697 (49) keV with a tentative spin-parity assignment of I π = 21/2 − and T 1/2 = 1.04 (10) s has been identified [16,17].…”

“…Furthermore, jj45 also places the yrast 23/2 − above the 29/2 + , which in that case would be β decaying, at variance with the observations. Finally, both calculations predict an isomeric 21/2 − state, now settled at an excitation energy of 1697(49) keV [17]. In comparison with 129 In, this single isomer is seemingly replacing the 17/2 − -23/2 − "isomeric doublet."…”

“…In each case, a selection of states is shown, primarily experimentally known isomeric states, indicated by thick horizontal lines in the figure, as well as some high-spin states through which some of these isomers decay, i.e., states which are experimentally rather well established. The experimental sequences are based on information available in evaluated nuclear structure data files (ENSDF) [15,45,58] [17,19], 127 In [17,19], and 129 In [13,16,19].…”

“…A recent mass measurement yielded a consistent excitation energy of 390 (18) keV [17]. In addition to the 1/2 − isomer, another β-decaying isomer at 1697 (49) keV with a tentative spin-parity assignment of I π = 21/2 − and T 1/2 = 1.04 (10) s has been identified [16,17]. Evidence for a short-lived, T 1/2 = 9(2) μs, high-spin isomer feeding this 21/2 − isomer has been found as well, with a tentative 29/2 + spin-parity assignment [18,19].…”