Low spin spectroscopy of N=Z nuclei: Quasi-deuteron states in odd-odd nuclei

Abstract

Isovector M1 transitions between low-lying T=1 and T=0 states in odd-odd N=Z nuclei are discussed. Simple analytical expressions for M1 transition strengths are given in single-j-shell approximation. The large B(M1) values for the j=l+1/2 case are attributed to quasi-deuteron configurations. The B(M1) values for the j=l−1/2 case are found to be small due to a cancellation of spin and orbital parts of the M1 matrix element. The experimental data on low spin states in the odd-odd nucleus 54Co investigated with the 54Fe(p,nγ)54Co fusion reaction at the FN-TANDEM accelerator in Cologne are reported. The Jπ=01+, 21+, 41+ T=1 and Jπ=11+, 31+, T=0 states are identified as predominantly πf7/2−1×ν7/2−1 quasi-deuteron states.