The M1 Transition Strength from the 3/2⁻ Isobaric Analogue State in ⁴⁹Sc

Abstract

Gamma rays from the strongest five of seven resonances associated with the ⁴⁹Ca ground-state analogue in the reaction ⁴⁸Ca(p, γ)⁴⁹Sc have been measured. The B(M1) for the gamma decay of the isobaric analogue state (IAS) to the 3082 keV anti-isobaric analogue state (AIAS) is found to be 1.2×10⁻² W. U., which is hindered by a factor of ∼1.7×10⁻² with respect to a simple shell model prediction. This hindrance has been found to be due to the fact that several levels at around 6.5 MeV, which presumably arise from the core-polarization configuration, absorb most of the M1 strength. The correspondence between the strength of the Gamow-Teller (GT) beta transition from the ⁴⁹Ca g. s. to the 3082 keV state in ⁴⁹Sc and the strength of the σ-part of the M1 transition from the IAS to the AIAS is discussed.