Spin-isospin strength distributions forfpshell nuclei: Results for theMn55(n,p),

Abstract

Cross sections for the reactions Mn(n, p), Fe(n, p), and Ni(n, p) have been measured at an incident energy of 198 MeV, with protons observed over a range of energies corresponding to excitations of up to about 35 MeV in the residual nuclei Cr, Mn, and Co, respectively. Measurements were carried out at center-of-mass angles between 1. 6' and 19. 9'. A multipole analysis of the results yielded the distribution of Gamow-Teller (GT) and spin-dipole strength for each target. The total GT strength below an excitation energy of 8.5 MeV was 1.? units for Mn, 2.9 units for Fe, and 3.8 units for Ni. Shell model calculations of the GT strength distribution, carried out in a restricted vector space, show fair to good agreement with the data up to an excitation energy of 8.5 MeV, but overestimate the total strength by a factor of between 3 and 4.

Contribution of excited states to stellar weak-interaction rates in odd-Anuclei

“…The GT distribution of the ground state is compared with (n,p) data from Ref. [33]. The measured strength has a broad peak centered at 4 MeV, which is at somewhat lower energy than the calculations.…”

“…The calculations correspond to QRPA results with SLy4 Skyrme force. Data from different charge-exchange reaction experiments [30][31][32][33] are also shown when available.…”

“…1. There is also experimental information [30][31][32][33] on the GT strength distributions in 45 Sc, 51 V, and 55 Mn obtained from charge-exchange reactions that will be used for comparison.…”

Stellar electron-capture rates on nuclei based on a microscopic Skyrme functional

“…New experimental data carried out in the iron mass region (see, e.g., Ref. [5]) showed that the GT transitions are quenched with respect to the calculations based on the IPM and fragmented over many states in the daughter nucleus, because of the effect of the residual interaction which is neglected in the IPM. Then, Caurier et al [6] performed shell-model (SM) calculations for iron group nuclei.…”

Low-energy magnetic dipole response in 56Fe from high-resolution electron scattering

“…The GT + and GT − strengths in 56 Fe have been studied with the (p, n) [18] and (n, p) [19] charge-exchange reactions, respectively. A study of the M1 response in 56 Fe serves as an interesting test of the theoretical approaches.…”