$\beta -$delayed $\gamma $-ray spectroscopy of 196Hg

Recent experimental results on the nucleus 196Hg -- especially newly determined level spins and multipole mixing ratios of $\gamma $ transitions between low-energy states -- show a good agreement with supersymmetrical predictions, describing 196Hg as the two-fermion, five-boson member of the supermultiplet around 194Pt. To complete the data of a previous 194Pt($\alpha $,2n) experiment, and to search for further low-lying low-spin states that might not be populated by that reaction, we chose to perform a new experiment on 196Hg. This time we approached 196Hg via $\beta $ decay. We used a 35 MeV proton beam at the Wright Nuclear Structure Laboratory to induce the reaction 198Hg(p,3n)196Tl. Our target consisted of highly enriched 198HgS. One $\beta $ decay branch populates preferably the low-spin states we are interested in. The 196Hg $\gamma $ transitions were detected with the highly efficient YRAST Ball $\gamma $ spectrometer. We present first preliminary results and discuss the description of the even-even mercury isotopes in the context of the nuclear structure supersymmetry. Supported by DFG grants Jo391/2-3, Jo391/3-2, and by U.S. DOE grant DE-FG02-91ER40609.