Spectroscopy of the ODD-ODD nucleus ⁷⁶As and its supersymmetric description

Gamma rays and conversion electrons following thermal-neutron capture in ⁷⁵As have been measured using the Ge pair spectrometer PN4, the bent crystal spectrometers GAMS and the β-spectrometer BILL at the ILL. Coincident γ-rays were recorded at the CEN/SCK Mol, and average resonance capture at E_n = 2 and 24 keV has been studied at the HFBR of BNL. The neutron binding energy in ⁷⁶As was determined to be 7328.498 ± 0.075 keV. The resulting level scheme for ⁷⁶As greatly improves the knowledge on this odd-odd nucleus. The low-lying positive-parity states are discussed in the U(5) limit of the U_v(6/12)⊗U_π(6/12) supersymmetry using the same hamiltonian to describe the quartet ⁷⁶Se-⁷⁷Se-⁷⁵As-⁷⁶As having the same total number of bosons plus fermions.