Spectroscopy of states in 136Ba using the 138Ba(p,t) reaction
Abstract
Background: The 136Ba isotope is the daughter nucleus in 136Xe ββ decay. It also lies in a shape transitional region of the nuclear chart, making it a suitable candidate to test a variety of nuclear models. Purpose: To obtain spectroscopic information on states in 136Ba, which will allow a better understanding of its low-lying structure. These data may prove useful to constrain future 136Xe 136Ba neutrinoless ββ decay matrix element calculations. Methods: A 138Ba(p,t) reaction was used to populate states in 136Ba up to approximately 4.6 MeV in excitation energy. The tritons were detected using a high-resolution Q3D magnetic spectrograph. A distorted wave Born approximation (DWBA) analysis was performed for the measured triton angular distributions. Results: One hundred and two excited states in 136Ba were observed, out of which fifty two are reported for the first time. Definite spin-parity assignments are made for twenty six newly observed states, while previously ambiguous assignments for twelve other states are resolved.