Transverse asymmetry of individual $\gamma$-rays in the $^{139}$La($\vec{n}$, $\gamma$)$^{140}$La reaction

• Main Authors: Okuizumi, M, Auton, C. J, Endo, S, Fujioka, H, Hirota, K, Ino, T, Ishizaki, K, Kimura, A, Kitaguchi, M, Koga, J, Makise, S, Niinomi, Y, Oku, T, Okudaira, T, Sakai, K, Shima, T, Shimizu, H. M, Tada, H, Takada, S, Takahashi, S, Tani, Y, Yamamoto, T, Yoshikawa, H, Yoshioka, T
• Format: Journal Article
• Language: English
• Published: 29-02-2024
• Subjects: Physics - Nuclear Experiment
• DOI: 10.48550/arxiv.2402.18876

The enhancement of the parity-violating asymmetry in the vicinity of $p$-wave
compound nuclear resonances was observed for a variety of medium-heavy nuclei.
The enhanced parity-violating asymmetry can be understood using the $s$-$p$
mixing model. The $s$-$p$ mixing model predicts several neutron
energy-dependent angular correlations between the neutron momentum $\vec k_n$,
neutron spin $\vec\sigma_n$, $\gamma$-ray momentum $\vec k_\gamma$, and
$\gamma$-ray polarization $\vec\sigma_\gamma$ in the $(n,\gamma)$ reaction. In
this paper, the improved value of the transverse asymmetry of $\gamma$-ray
emissions, corresponding to a correlation term $\vec{\sigma}_n\cdot(\vec
k_n\times\vec k_\gamma)$ in the $^{139}\mathrm{La}(\vec
n,\gamma)^{140}\mathrm{La}$ reaction, and the transverse asymmetries in the
transitions to several low excited states of $^{140}\mathrm{La}$ are reported.