New Isotope of Silicon: 6.3-secSi33

Abstract

${}_{}{}^{33}{}_{}{}^{}\mathrm{Si}$ has been produced via the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}+{}_{}{}^{18}{}_{}{}^{}\mathrm{O}\to {}_{}{}^{33}{}_{}{}^{}\mathrm{Si}+2p+n$ reaction using 23-40-MeV ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ions. Identification is made from the observed $\gamma$ rays of 1431.3 ± 0.5, 1847.69 ± 0.25, and 2538 ± 2 keV which agree with the first three excited states of ${}_{}{}^{33}{}_{}{}^{}\mathrm{P}$. By means of the reaction ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}\mathrm{}(t,p)\mathrm{}{}_{}{}^{33}{}_{}{}^{}\mathrm{P}$, $\gamma$ rays from the first two excited states of ${}_{}{}^{33}{}_{}{}^{}\mathrm{P}$ have been measured as 1431.4 ± 0.3 and 1847.60 ± 0.15 keV. The three ${}_{}{}^{33}{}_{}{}^{}\mathrm{Si}$ $\gamma$ rays decay together and a value of $T_{\frac{1}{2}}=6.3\mathrm{}\pm 0.3$ sec is obtained from the 1848-keV line. Relative $\gamma$ intensities correspond to ${}_{}{}^{33}{}_{}{}^{}\mathrm{Si}$ $\beta$ branches to the 1431-, 1848-, and 2539-keV states of ${}_{}{}^{33}{}_{}{}^{}\mathrm{P}$ in the ratios 0.06 ± 0.06: 1: 0.10 ± 0.02. No information was obtained on a possible ${}_{}{}^{33}{}_{}{}^{}\mathrm{Si}$ ground-state $\beta$ branch. The results are consistent with the expected mass and spin-parity ($J^{\pi }={\frac{3}{2}}^{+}$) of the ${}_{}{}^{33}{}_{}{}^{}\mathrm{Si}$ ground state.