Decay Scheme ofMg28

Abstract

The 21.3-h half-life $\beta$-ray emitter ${\mathrm{Mg}}^{28}$ was produced in the ${\mathrm{Mg}}^{26}(t, p){\mathrm{Mg}}^{28}$ reaction and the subsequent $\gamma$ radiations were studied with Ge(Li) and NaI(Tl) detectors. Strong $\gamma$ rays with measured energies of 400.6±0.2, 941.7±0.4, and 1342.2±0.2 keV were found to be in coincidence with the 30.6-keV $\gamma$ rays from the ${\mathrm{Al}}^{28}$ first excited state, in agreement with earlier results. Four additional weak $\gamma$ rays detected in ${\mathrm{Mg}}^{28}$ decay include a $\gamma$-ray energy of 1589.4±0.4 keV in coincidence with the 30.6-keV $\gamma$ ray, a $\gamma$-ray energy of 648.1±0.5 keV in coincidence with the 941.7-keV $\gamma$ ray, and two ground-state $\gamma$-ray transitions having energies of 1620.0±0.4 and 1372.8±0.2 keV. In the proposed level scheme, ${\mathrm{Mg}}^{28}$ decays with a 95±1% $\beta$-ray branch ($logft=4.49\mathrm{}\pm 0.03$) to the $J^{\pi }=1^{+}$ 1372.8 ± 0.2-keV level of ${\mathrm{Al}}^{28}$, and with a 5±1% $\beta$-ray branch ($logft=4.59\mathrm{}\pm 0.08$) to a 1620.0±0.4-keV level which we assign a spin parity of $J^{\pi }=1^{+}$.