Accurate masses and β-decay schemes for 34P and 33Si

By using delayed β-γ coincidence techniques, the mass excesses of ³⁴P and ³³Si have been measured to be -24 546 ± 45 and -20 569 ± 50 keV, respectively, representing improvements in precision of a factor of 2 for ³⁴P and a factor of 4 for ³³Si over previous measurements. The first measurements of the high-energy γ rays from ³⁴P decay with a Ge(Li) detector are presented, revealing three new β branches. γ-ray energies (in keV) and relative intensities for the ³⁴S daughter transitions are 1787 ± 1 (0.30 ± 0.10), 1947.1 ± 1.5 (0.28 ± 0.10), 1987.2 ± 1.0 (1.0 ± 0.2), 2127.4 (100.0 ± 0.3), 4073.4 ± 1.5 (0.46 ± 0.06), and 4114.0 ± 1.5 (1.2 ± 0.2). The ³⁴S excitation energies and relative β branches are 2127.4 (100 ± 0.3), 3303.7 (0.26), 3914.2 (0.30 ± 0.10), 4073.0 (0.76 ± 0.12), and 4114.5 (2.2 ± 0.3). For the decay of ³³Si, energies and relative intensities of γ rays were measured to be 415.8 ± 0.6 (6.7 ± 0.6), 1431.4 (13.1 ± 1.0), 1847.5 (100 ± 1), and 2537.5 (9.3 ± 0.8), representing excitation energies and relative β-ray intensities to the ³³P daughter states of 1431.4 (${5.1}_{-2.4}^{+1.0}$), 1847.5 (${100}_{-2.8}^{+1.0}$), and 2537.6 (10.5 ± 1.0). The half-lives of ³⁴P and ³³Si were determined by multiscaling γ-ray yields to be 12.45 ± 0.10 and 6.11 ± 0.21 sec, respectively. Combined with an earlier result, a half-life of 6.18 ± 0.18 sec is adopted for ³³Si. The transverse mass relationship of Garvey, using the present measurements for ³⁴P and ³³Si, predicts a mass excess of -20 251 ± 90 keV for the $T_z=3$ nuclide ³⁴Si.