Low-Lying Negative-Parity States inNe21

Angular-distribution measurements have been performed on the ${\mathrm{Ne}}^{22}\mathrm{}(p,d)\mathrm{}{\mathrm{Ne}}^{21}$ and ${\mathrm{Ne}}^{20}\mathrm{}(d,p)\mathrm{}{\mathrm{Ne}}^{21}$ reactions at $E_p=20\mathrm{}$ MeV and $E_d=16.4\mathrm{}$ MeV, respectively. In the ${\mathrm{Ne}}^{22}\mathrm{}(p,d)\mathrm{}{\mathrm{Ne}}^{21}$ reaction studies, formation of the 0-, 350-, and 3664-keV ${\mathrm{Ne}}^{21}$ levels was characterized by respective $l_n=2, 2, \mathrm{and} 1$ 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 $l_n=1\mathrm{}$ component in the associated distorted-wave Born-approximation fit, with evidence for a minor $l_n=0\mathrm{}$ component also being present. Since the 2796-keV level possesses $J^{\pi }={\frac{1}{2}}^{+}$, the present ($p,d$) result implies $J^{\pi }={\frac{1}{2}}^{-} or {\frac{3}{2}}^{-}$ for the 2790-keV ${\mathrm{Ne}}^{21}$ level. The ${\frac{3}{2}}^{-}$, 4730-keV state did not display discernible direct-reaction characteristics in this ($p,d$) study. This was also true of the remaining ${\mathrm{Ne}}^{21}$ levels below $E_x=5\mathrm{}$ MeV, which generally possessed ∼0.1-mb/sr cross sections attributed to second-order direct and/or compound nuclear-reaction mechanisms. The ${\mathrm{Ne}}^{20}\mathrm{}(d,p)\mathrm{}{\mathrm{Ne}}^{21}$ results indicate $l_n=0\mathrm{}$ transfer for the 2790-, 2796-keV ${\mathrm{Ne}}^{21}$ composite, and $l_n=1\mathrm{}$ transfer for the 4730-keV ${\mathrm{Ne}}^{21}$ state. The 3664-keV level did not display discernible direct reaction characteristics in this (