Structure of 135Xe from the (d,pγ) reaction with 134Xe beams and GODDESS*

About half of the elements heavier than iron are synthesized during the r-process that proceeds via (n,γ) reactions on neutron-rich nuclei. Direct-semidirect neutron captures are important, if not dominant, near the N=82 closed shell and are expected to have a significant impact during the late stages of the r-process, for example through ¹³⁰Sn(n,γ)¹³¹Sn. Therefore, the evolution of the shell gap at N=82 and the single neutron 3p_3/2 and 3p_1/2 states are keys to a better understanding of the r-process and for constraining model parameters. To probe the 2f-3p single-neutron configurations in the N=81 isotone ¹³⁵Xe, we have measured the ¹³⁴Xe(d,pγ)¹³⁵Xe reaction in inverse kinematics using GODDESS (Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies). The ¹³⁴Xe beam was produced at ATLAS (Argonne National Laboratory) and impinged on a C₂D₄ target. Reaction protons were measured (ORRUBA) in coincidence with gamma rays (Gammasphere). Several single-neutron states, corresponding to the transfer of a neutron to the p-f configurations above the N=82 shell gap, have been observed for the first time.

In collaboration with the GODDESS team.