Electromagnetic properties of levels in 55Mn

Excited levels of ⁵⁵Mn were produced by the reaction ⁵²Cr(α, p) at 10.5 and 11.1 MeV beam energy. A series of γ-ray measurements was made, all in coincidence with protons detected near 180°. A Ge(Li) γ-ray detector was used at 4 angles, and extensive angular-correlation measurements were made with an array of NaI(Tl) detectors. Excitation energies of 25 levels up to 3161 keV were determined, including a new level at 2215 keV. Only the level at 2285 keV and the $\text{1}\text{2}{}^{\mathrm{?}}$ state near 1290 keV were not observed in this range. From Doppler-shift attenuations, the mean lifetimes of 14 levels up to 2565 keV were deduced. Branching ratios and multipole mixing ratios were obtained for most of these levels. The following spin assignments were determined: 1530 keV, $\text{J =}\text{3}\text{2}$; 1885 keV, $\text{J =}\text{7}\text{2}$ or $\text{5}\text{2}$; 2565 keV, $\text{J =}\text{3}\text{2}$. Reduced transition probabilities, B (M1) and B (E2), of many transitions were calculated from these experimental results and are compared with the available theoretical values.