Gamow-Teller transitions in pf-shell nuclei studied in (3He, t) reactions

The Gamow-Teller transition strengths in pf-shell nuclei are important parameters in a presupernova model. A high resolution (3He, t) reaction was performed from Tz = + 1 nuclei (42Ca, 46Ti, 50Cr and 54Fe) to Tz = 0 nuclei (42Sc, 46V, 50Mn and 54Co) at an incident energy of 140 MeV/nucleon and at 0°for the precise study of GT transition strengths B(GT). To derive B(GT) values for these pf-shell nuclei, the R2 value, the ratio between the GT and Fermi unit cross sections, was introduced. The R2 values were studied for various mass nuclei by using the B(GT) values from β-decay studies as standard, and the mass dependence was derived. It was found that GT strengths in these four pf-shell nuclei move to higher excitation energies as the mass number A increases. The obtained GT strength distributions were compared with shell model calculations. © 2007.