Spectroscopy of the Lower Excited States ofCo59

Abstract

We have investigated the low-lying states of ${\mathrm{Co}}^{59}$ by means of the (${\mathrm{He}}^{3}$, $d$) reaction on ${\mathrm{Fe}}^{58}$, using an incident beam whose energy was 22 MeV. In addition to strong $l=3$ transitions to the ${\frac{7}{2}}^{\ensuremath{-}}$ ground state and a group of states centered at 2.08 MeV, strong $l=1$ transitions to the first, third, and fourth excited states were observed. From these results and the results of previous experiments, the first and third excited states can each be assigned spin and parity of ${\frac{3}{2}}^{\ensuremath{-}}$. These assignments are consistent with the results from our study of the ${\mathrm{Ni}}^{60}(d, {\mathrm{He}}^{3}){\mathrm{Co}}^{59}$ reaction. The present results are in agreement with previous assignments of either ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$ or ${\frac{3}{2}}^{\ensuremath{-}}$ for the fourth excited state, but cannot distinguish between these values. Spectroscopic factors for these transitions were obtained from a comparison of the experimental data with the predictions of a distorted-wave calculation.