Angular distribution of γ rays from neutron-induced compound states of La140
| Autor: | A. Kimura, Hirohiko M. Shimizu, Kenji Sakai, Takuya Okudaira, Anju Okada, T. Yamamoto, Masaaki Kitaguchi, Jun Koga, K. Nagamoto, T. Nakao, Shusuke Takada, Katsuya Hirota, Tamaki Yoshioka |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
010308 nuclear & particles physics Astrophysics::High Energy Astrophysical Phenomena media_common.quotation_subject Resonance chemistry.chemical_element Context (language use) Germanium 01 natural sciences Asymmetry Neutron temperature Amplitude chemistry Total angular momentum quantum number 0103 physical sciences Neutron Atomic physics 010306 general physics media_common |
| Zdroj: | Physical Review C. 97 |
| ISSN: | 2469-9993 2469-9985 |
| DOI: | 10.1103/physrevc.97.034622 |
| Popis: | Angular distribution of individual $\gamma$-rays, emitted from a neutron-induced compound nuclear state via radiative capture reaction of ${}^{139}$La(n,$\gamma$) has been studied as a function of incident neutron energy in the epithermal region by using germanium detectors. An asymmetry $A_{\mathrm{LH}}$ was defined as $(N_{\mathrm L}-N_{\mathrm H})/(N_{\mathrm L}+N_{\mathrm H})$, where $N_{\mathrm L}$ and $N_{\mathrm H}$ are integrals of low and high energy region of a neutron resonance respectively, and we found that $A_{\mathrm{LH}}$ has the angular dependence of $(A\cos\theta_\gamma+B)$, where $\theta_\gamma$ is emitted angle of $\gamma$-rays, with $A= -0.3881\pm0.0236$ and $B=-0.0747\pm0.0105$ in 0.74 eV p-wave resonance. This angular distribution was analyzed within the framework of interference between s- and p-wave amplitudes in the entrance channel to the compound nuclear state, and it is interpreted as the value of the partial p-wave neutron width corresponding to the total angular momentum of the incident neutron combined with the weak matrix element, in the context of the mechanism of enhanced parity-violating effects. Additionally we used the result to quantify the possible enhancement of the breaking of the time-reversal invariance in the vicinity of the p-wave resonance. |
| Databáze: | OpenAIRE |
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