Low-lying levels ofMn57from theCr54(α,p)reaction

Proton energy spectra from the ${}_{}{}^{54}{}_{}{}^{}\mathrm{Cr}(\alpha ,p){}_{}{}^{57}{}_{}{}^{}\mathrm{Mn}$ reaction at 15, 21, and 24 MeV and at several angles have been measured with the 100-cm broad-range spectrograph. Both NaI(Tl) and Ge(Li) detectors have been used to study $\gamma$ rays, in coincidence with protons in a particle detector, from the same reaction. From the spectrograph measurements, the ground-state $Q$ value is found to be -4308 ± 8 keV. Excited levels have been found at 84.1 ± 1.0, 851.1 ± 1.0, 1059.2 ± 2.0, 1073.8 ± 2.0, 1227.1 ± 1.0, 1376.5 ± 1.3, 2188.2 ± 1.1, and 2234.3 ± 1.7 keV. Ten $\gamma$-ray transitions have been observed. From particle-γ coincidence and angular-correlation measurements the spins of some levels can be limited as follows: 84 keV, 3/2-7/2; 851 keV, 3/2 or 5/2; 1059 keV, 1/2-5/2. Probable spin assignments for these three levels suggested on the basis of cross-section and relative transition-strength considerations are (7/2), (3/2), and (1/2), respectively. Other tentative spin assignments, and the comparison of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Mn}$ with other odd Mn isotopes, are discussed.