Deeply-bound hole states in 57Co and the spreading of the 1d [formula omitted] hole strength distribution

Abstract

In an attempt to locate the 1 d 5 2 proton hole state in 57Co we have measured the 58Ni( d , 3He) 57Co reaction with 79.6 MeV vector polarized deuterons. An overall energy resolution of 50 keV was achieved with a magnetic spectrometer. The spectra show fine structure up to E x = 11 MeV; this fact was used to define energy bins for which cross sections and analyzing powers were obtained. The latter allowed spin and parity assignments for deep-lying hole states in 57Co. Spectroscopic factors were obtained by applying standard DWBA calculations. Most of the strength above 6.6 MeV was identified as being 1 d 5 2 in nature. The running sum of Spectroscopic factors shows a linear increase implying a nearly uniform spread of the 1 d 5 2 Spectroscopic strength or a width of the 1 d 5 2 hole state comparable to the excitation energy.