High-resolution (3He,t) reaction on the double-β decaying nucleus 136Xe

A (He-3, t) charge-exchange reaction experiment on the double-beta decaying nucleus Xe-136 has been performed at an incident energy of 420 MeV with the objective to measure the Gamow-Teller (GT) strength distribution in Cs-136. The measurements have been carried out at the dispersion-matched WS beam line and the Grand Raiden spectrometer of the Research Center for Nuclear Physics in Osaka, where an energy resolution of 42 keV was achieved. A new gas cell with thin windows made of polyethylene naphthalate has been employed as a target. The extracted GT strength distribution is confronted with the rather long 2 nu beta beta decay half-life of Xe-136.