Nuclear Structure ofNa22: TheNa23(He3,α)Reaction

Abstract

The states of Na22 below 7.5 MeV have been studied using the Na23(He3,α)Na22 reactions at a bombarding energy of 18 MeV. Angular distributions of the reaction products have been compared with distorted-wave Born-approximation predictions. The resulting spectroscopic factors are compared with those calculated using the rotational model and with experimental spectroscopic factors from the Na23(p,d) and Na23(d,t) reactions. The results suggest a Kπ=1− T=0 rotational band (2.21 MeV, 1−; 2.57 MeV, 2−; and 3.52 MeV, 3−) and a Kπ=2−, T=0 band [4.58 MeV, 2− (0−, 1−, 3−) and 5.44 MeV, 3− (0−, 1−, 2−)] based on neutron pickup from the 12−[101] Nilsson orbit. A comparison of the l=1 Na23(He3,α) transition to the 5.95-MeV level in Na22 with the Na23(d,He3)Ne22 results suggests that this state is the analog of the 5.14-MeV, 2− state in Ne22 and that these levels correspond to the Kπ=2−, T=1 band head based on nucleon pickup from the 12−[101] Nilsson orbit. The results of the present study and a previous Ne21(He3,d)Na22 study are discussed in terms of Nilsson configurations and associated rotational bands. It is found that the rotational model provides a reasonably adequate explanation for the observed spectroscopic factors of the negative-parity states up to 7.5 MeV and for the positive-parity states based on the (32+[211])2 configuration if a deformation of δ≈0.5 is assumed. The simple rotational model, however, is unable to account for the observed single-nucleon-transfer spectroscopic factors for the other positive-parity configurations.