Collective 2p-2h intruder states in Sn 118 studied via β decay of in 118 using the GRIFFIN spectrometer at TRIUMF

Abstract

The low-lying structure of semimagic Sn118 has been investigated through the β decay of In118 (T1/2=4.45 min) to study shape coexistence via the reduced transition probabilities of states in the 2p-2h proton intruder band. This high-statistics study was carried out at TRIUMF-ISAC with the GRIFFIN spectrometer. In total, 99 transitions have been placed in the level scheme with 43 being newly observed. Three low-lying γ-ray transitions with energies near 285 keV have been resolved from which the 2intr.+→0intr.+ 284.52-keV transition was determined to have half of the previous branching fraction leading to a B(E2;22+→02+) of 21(4) W.u. compared to 39(7) W.u. from the previous measurement. Calculations using sd IBM-2 with mixing have also been made to compare the experimental B(E2) values to the theoretical values and to make comparisons to the Sn114,116 isotopes previously studied using the same theoretical model.