High-resolution study of Fe-56 -> Mn-56 Gamow-Teller transition by the combined analysis of Fe-56(He-3,t)Co-56 and Fe-56(p,p ')Fe-56 reactions

Abstract

Gamow-Teller (GT) transitions in the beta(+) (electron capture) direction from the ground state of Fe-56 to the excited states of Mn-56 play an important role in the core collapse of presupernova. Assuming that isospin analogous transitions in isobars have corresponding strengths, we deduced these GT strengths by combining the results of the Fe-56(p,p')Fe-56 experiment performed at 200 MeV and 0 degrees and the Fe-56(He-3,t)Co-56 experiment in the beta direction at 140 MeV/u and 0 degrees. The ground state of Fe-56 has the isospin value of T = 2, while the GT states in Mn-56 have T = 3. In order to identify the analogous T = 2 -> 3, UT transitions in the Fe-56(p,p')Fe-56 and the Fe-56(He-3,t)Co-56 measurements, we used the fact that the isospin Clebsch-Gordan (CG) coefficients for these T = 2 -> 3 transitions are different in these measurements. Then the UT transition strengths B(GT) in the beta(+) direction can be deduced from the B(GT) values of the corresponding transitions well determined in the Fe-56(He-3,t)Co-56 measurement assuming the isospin symmetry and correcting the difference of CG coefficients.