The energy levels of ${}_{}{}^{25}{}_{}{}^{}\mathrm{Si}$ have been measured by detecting ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ particles from the reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{He}$)${}_{}{}^{25}{}_{}{}^{}\mathrm{Si}$ in photographic plates on the focal plane of a spectrometer. 12 excited states were observed. The observation of a weak state at 40-keV excitation leads to a new ${}_{}{}^{25}{}_{}{}^{}\mathrm{Si}$ ground-state mass excess, 3.824 ± 0.010 MeV. The observed levels are discussed in terms of the isobaric multiplet mass equation and the shell model.

• Received 6 December 1971

DOI:https://doi.org/10.1103/PhysRevC.5.1426