LOW-LYING NEGATIVE-PARITY STATES IN NE21

Angular-distribution measurements have been performed on the Ne22(p,d)Ne21 and Ne20(d,p)Ne21 reactions at Ep=20 MeV and Ed=16.4 MeV, respectively. In the Ne22(p,d)Ne21 reaction studies, formation of the 0-, 350-, and 3664-keV Ne21 levels was characterized by respective ln=2,2,and1 neutron pickup transfers. The composite (p,d) angular distribution observed for the experimentally unresolved 2790- and 2796-keV states is shown to require a dominant ln=1 component in the associated distorted-wave Born-approximation fit, with evidence for a minor ln=0 component also being present. Since the 2796-keV level possesses Jπ=12+, the present (p,d) result implies Jπ=12-or32- for the 2790-keV Ne21 level. The 32-, 4730-keV state did not display discernible direct-reaction characteristics in this (p,d) study. This was also true of the remaining Ne21 levels below Ex=5 MeV, which generally possessed ∼0.1-mb/sr cross sections attributed to second-order direct and/or compound nuclear-reaction mechanisms. The Ne20(d,p)Ne21 results indicate ln=0 transfer for the 2790-, 2796-keV Ne21 composite, and ln=1 transfer for the 4730-keV Ne21 state. The 3664-keV level did not display discernible direct reaction characteristics in this (d,p) study. The present findings establish that the major 1p-shell strength is located in the 2790- and 3664-keV Ne21 levels, whereas the major 2p32 particle strength is associated with the 4730-keV Ne21 state. These low-lying non-normal parity states are discussed within the framework of the Nilsson strong-coupling collective model. © 1969 The American Physical Society.