arXiv subjects

M. Okuizumi

Publications and source records attributed to M. Okuizumi.

3 recordsLinked to original sources

arXiv2024

Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons

Measurements of circular polarization of $γ$-ray emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the $γ$-ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The $γ$-ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized $γ$-ray beam. Furthermore, as a demonstration, the $γ$-ray circular polarization was measured in $^{32}$S($\vec{\textrm{n}}$,$γ$)$^{33}$S reactions with polarized neutrons.

physics.ins-det↗

arXiv2024

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

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 $\vecσ_n$, $γ$-ray momentum $\vec k_γ$, and $γ$-ray polarization $\vecσ_γ$ in the $(n,γ)$ reaction. In this paper, the improved value of the transverse asymmetry of $γ$-ray emissions, corresponding to a correlation term $\vecσ_n\cdot(\vec k_n\times\vec k_γ)$ in the $^{139}\mathrm{La}(\vec n,γ)^{140}\mathrm{La}$ reaction, and the transverse asymmetries in the transitions to several low excited states of $^{140}\mathrm{La}$ are reported.

nucl-ex↗

arXiv2023

High sensitivity of a future search for P-odd/T-odd interactions on the 0.75 eV $p$-wave resonance in $\vec{n}+^{139}\vec{\rm La}$ forward transmission determined using pulsed neutron beam

Neutron transmission experiments can offer a new type of highly sensitive search for time-reversal invariance violating (TRIV) effects in nucleon-nucleon interactions via the same enhancement mechanism observed for large parity violating (PV) effects in neutron-induced compound nuclear processes. In these compound processes, the TRIV cross-section is given as the product of the PV cross-section, a spin-factor $κ$, and a ratio of TRIV and PV matrix elements. We determined $κ$ to be $0.59\pm0.05$ for $^{139}$La+$n$ using both $(n, γ)$ spectroscopy and ($\vec{n}+^{139}\vec{\rm La}$) transmission. This result quantifies for the first time the high sensitivity of the $^{139}$La 0.75~eV $p$-wave resonance in a future search for P-odd/T-odd interactions in ($\vec{n}+^{139}\vec{\rm La}$) forward transmission.

nucl-ex↗