Gamma-ray spectroscopy of 131Sn81 via the (9Be,8Be $\gamma )$ reaction*

Nuclear data in the region of the doubly-magic nucleus $^{\mathrm{132}}$Sn$_{\mathrm{82}}$ is useful for benchmarking nuclear structure theories due to the clean single-particle nature of the nuclear wavefunction near the closed shells. At the Holifield Radioactive Ion Beam Facility (HRIBF) neutron-rich beams in the $^{\mathrm{132}}$Sn$_{\mathrm{82}}$ region were produced via proton-induced fission of a Uranium-Carbide target. The CLARION array of HPGe detectors was coupled with the HyBall array of CsI detectors to allow for particle-gamma coincidence measurements. The gamma-ray de-excitation of the four lowest lying single-neutron states has been observed for the first time via the ($^{\mathrm{9}}$Be,$^{\mathrm{8}}$Be $\gamma )$ reaction. The excitation energy of these states have been measured to higher precision than was possible with the previous charged particle measurement.