Measurement of $γ$ rays from the giant resonances excited by $^{12}$C$(p,p')$ reaction at 392 MeV and 0$^{\circ}$
nucl-ex
/ Authors
M. S. Reen, I. Ou, T. Sudo, D. Fukuda, T. Mori, A. Ali, Y. Koshio, M. Sakuda, A. Tamii, N. Aoi
and 14 more authors
M. Yosoi, E. Ideguchi, T. Suzuki, T. Yamamoto, C. Iwamoto, T. Kawabata, S. Adachi, M. Tsumura, M. Murata, T. Furuno, H. Akimune, T. Yano, T. Suzuki, R. Dhir
/ Abstract
We measured both the differential cross section ($σ_{p,p^\prime}$ $=d^2σ/dΩdE_{x}$) and the $γ$-ray emission probability ($R_γ(E_x)$ $=σ_{p,p^\primeγ}$/$σ_{p,p^\prime}$) from the giant resonances excited by $\rm^{12}C$(\textit{p,p}$^\prime$) reaction at 392 MeV and 0$^\circ$, using a magnetic spectrometer and an array of NaI(Tl) counters. The absolute value of $R_γ(E_x)$ was calibrated by using the well-known $γ$-ray emission probability from $\rm^{12}C^* ( 15.11$ MeV, $ 1^+$, $T=1$) and $\rm^{16}O^* ( 6.9$ MeV, $2^+$, $T=0$) states within 5\% uncertainty. We found that $R_γ(E_x)$ starts from zero at $E_x=16$ MeV, increases to a maximum of 53.3$\pm$0.4$\pm$3.9\% at $E_x=27$ MeV and then decreases. We also compared the measured values of $R_γ(E_x)$ with statistical model calculation based on the Hauser-Feshbach formalism in the energy region $E_x=$ 16-32 MeV and discussed the features of $γ$-ray emission probability quantitatively.