TY - JOUR
T1 - Pionic enhancement in quasielastic (p→,n→) reactions at 345 MeV
AU - Wakasa, T.
AU - Sakai, H.
AU - Ichimura, M.
AU - Hatanaka, K.
AU - Greenfield, M. B.
AU - Hatano, M.
AU - Kamiya, J.
AU - Kato, H.
AU - Kawahigashi, K.
AU - Maeda, Y.
AU - Nakaoka, Y.
AU - Okamura, H.
AU - Ohnishi, T.
AU - Otsu, H.
AU - Sekiguchi, K.
AU - Suda, K.
AU - Tamii, A.
AU - Uesaka, T.
AU - Yagita, T.
AU - Yako, K.
N1 - Funding Information:
We thank Professor H. Toki for encouragement throughout the work, and the RCNP cyclotron crew for their efforts in providing a high quality polarized proton beam. The experiment was performed at RCNP under Program Number E131. This work was supported in part by the Grants-in-Aid for Scientific Research Nos. 12640294, 12740151, and 14702005 of the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
PY - 2004/5
Y1 - 2004/5
N2 - Differential cross sections and a complete set of polarization observables have been measured for quasielastic (p→,n→) reactions on 12C and 40Ca at a bombarding energy of 345 MeV. The laboratory momentum transfers are qlab ≃ 1.2, 1.7, and 2.0 fm-1 for 12C and qlab≃ 1.7 fm -1 for 40Ca. In these momentum transfer regions, the isovector spin-longitudinal interaction is attractive where the one-pion exchange is dominant. The spin-longitudinal and spin-transverse polarized cross sections, IDq and IDp, are deduced. The theoretically expected enhancement in the spin-longitudinal mode is observed at q lab≃1.7 and 2.0 fm-1. The observed IDq is consistent with the pionic enhanced IDq evaluated in distorted wave impulse approximation (DWIA) calculations employing random phase approximation (RPA) response functions. The enhanced IDq implies the existence of a precursor to pion condensation in nuclei. On the other hand, the theoretically predicted quenching in the spin-transverse mode is not observed. The observed IDp is not quenched, but rather enhanced relative to that predicted via the DWIA+RPA calculations. Two-step contributions are responsible in part for the enhancement of IDp.
AB - Differential cross sections and a complete set of polarization observables have been measured for quasielastic (p→,n→) reactions on 12C and 40Ca at a bombarding energy of 345 MeV. The laboratory momentum transfers are qlab ≃ 1.2, 1.7, and 2.0 fm-1 for 12C and qlab≃ 1.7 fm -1 for 40Ca. In these momentum transfer regions, the isovector spin-longitudinal interaction is attractive where the one-pion exchange is dominant. The spin-longitudinal and spin-transverse polarized cross sections, IDq and IDp, are deduced. The theoretically expected enhancement in the spin-longitudinal mode is observed at q lab≃1.7 and 2.0 fm-1. The observed IDq is consistent with the pionic enhanced IDq evaluated in distorted wave impulse approximation (DWIA) calculations employing random phase approximation (RPA) response functions. The enhanced IDq implies the existence of a precursor to pion condensation in nuclei. On the other hand, the theoretically predicted quenching in the spin-transverse mode is not observed. The observed IDp is not quenched, but rather enhanced relative to that predicted via the DWIA+RPA calculations. Two-step contributions are responsible in part for the enhancement of IDp.
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U2 - 10.1103/PhysRevC.69.054609
DO - 10.1103/PhysRevC.69.054609
M3 - Article
AN - SCOPUS:3142761537
SN - 0556-2813
VL - 69
SP - 054609-1-054609-10
JO - Physical Review C - Nuclear Physics
JF - Physical Review C - Nuclear Physics
IS - 5
M1 - 054609
ER -