Study of nuclear correlation effects via 12C(p,n)12N(g.s.,1+) at 296 MeV

Wakasa, T.
Dozono, M.
Ihara, E.
Asaji, S.
Fujita, K.
Hatanaka, K.
Ichimura, M.
Ishida, T.
Kaneda, T.
Matsubara, H.
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We report measurements of the cross section and a complete set of polarization observables for the Gamow--Teller ${}^{12}{\rm C}(\vec{p},\vec{n}){}^{12}{\rm N}({\rm g.s.},1^+)$ reaction at a bombarding energy of 296 MeV. The data are compared with distorted wave impulse approximation calculations employing transition form factors normalized to reproduce the observed beta-decay $ft$ value. The cross section is significantly under-predicted by the calculations at momentum transfers $q \gtrsim $ 0.5 ${\rm fm^{-1}}$. The discrepancy is partly resolved by considering the non-locality of the nuclear mean field. However, the calculations still under-predict the cross section at large momentum transfers of $q$ $\simeq$ 1.6 ${\rm fm^{-1}}$. We also performed calculations employing random phase approximation response functions and found that the observed enhancement can be attributed in part to pionic correlations in nuclei.
Comment: 5 figures, submitted to Phys. Lett. B
Nuclear Experiment