Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

The ANNRI-Gd collaboration studied in detail the single $\gamma$-ray spectrum produced from the thermal neutron capture on $^{155}$Gd and $^{157}$Gd in our previous publications. Gadolinium targets were exposed to a neutron beam provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the present analysis, one new additional coaxial germanium crystal was used in the analysis in combination with the fourteen germanium crystals in the cluster detectors to study the angular correlation of the two $\gamma$ rays emitted in the same neutron capture. We present for the first time angular correlation functions for two $\gamma$ rays produced during the electromagnetic cascade transitions in the (n, $\gamma$) reactions on $^{\rm 155}$Gd and $^{\rm 157}$Gd. As expected, we observe the mild angular correlations for the strong, but rare transitions from the resonance state to the two energy levels of known spin-parities. Contrariwise, we observe negligibly small angular correlations for arbitrary pairs of two $\gamma$ rays produced in the majority of cascade transitions from the resonance state to the dense continuum states.Comment: 21 pages, 13 figure

Gamma Ray Spectra from Thermal Neutron Capture on Gadolinium-155 and Natural Gadolinium

Abstract Natural gadolinium is widely used for its excellent thermal neutron capture cross section, because of its two major isotopes: $^{\rm 155}$Gd and $^{\rm 157}$Gd. We measured the $\gamma$-ray spectra produced from the thermal neutron capture on targets comprising a natural gadolinium film and enriched $^{\rm 155}$Gd (in Gd$_{2}$O$_{3}$ powder) in the energy range from 0.11 MeV to 8.0 MeV, using the ANNRI germanium spectrometer at MLF, J-PARC. The freshly analyzed data of the $^{\rm 155}$Gd($n, \gamma$) reaction are used to improve our previously developed model (ANNRI-Gd model) for the $^{\rm 157}$Gd($n, \gamma$) reaction [K. Hagiwara et al. [ANNRI-Gd Collaboration], Prog. Theor. Exp. Phys. 2019, 023D01 (2019)], and its performance confirmed with the independent data from the $^{\rm nat}$Gd($n, \gamma$) reaction. This article completes the development of an efficient Monte Carlo model required to simulate and analyze particle interactions involving the thermal neutron captures on gadolinium in any relevant future experiments

Sulle famiglie nobili della monarchia di Savoia;

Alphabetical index of names: v. 4, pt. 2, p. [1589]-1599."Per la morte avvenuta il 19 marzo scorso, del sacerdote Vittorio Angius, autore di quest'opera, non se pote continuare la narrazione di parecchie famiglie": v. 8, p. [1573]Imprint of v. 4: Torino, Tipografia di G. Cassone, 1857.Atlas (without t.-p.) has illustrated half-title: Album delle principali castella feudali della monarchia di Savoja.Mode of access: Internet

Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

International audienceThe ANNRI-Gd collaboration studied in detail the single $\gamma$-ray spectrum produced from the thermal neutron capture on $^{155}$Gd and $^{157}$Gd in the previous publications~\cite{Hagiwara, Tanaka}. Gadolinium targets were exposed to a neutron beam provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the present analysis, one new additional coaxial germanium crystal was used in the analysis in combination with the fourteen germanium crystals in the cluster detectors to study the angular correlation of the two $\gamma$ rays emitted in the same neutron capture. We present for the first time angular correlation functions for two $\gamma$ rays produced during the electromagnetic cascade transitions in the (n, $\gamma$) reactions on $^{\rm 155}$Gd and $^{\rm 157}$Gd. As expected, we observe the mild angular correlations for the strong, but rare transitions from the resonance state to the two energy levels of known spin-parities. Contrariwise, we observe negligibly small angular correlations for arbitrary pairs of two $\gamma$ rays produced in the majority of cascade transitions from the resonance state to the dense continuum states

Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

International audienceThe ANNRI-Gd collaboration studied in detail the single $\gamma$-ray spectrum produced from the thermal neutron capture on $^{155}$Gd and $^{157}$Gd in the previous publications~\cite{Hagiwara, Tanaka}. Gadolinium targets were exposed to a neutron beam provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the present analysis, one new additional coaxial germanium crystal was used in the analysis in combination with the fourteen germanium crystals in the cluster detectors to study the angular correlation of the two $\gamma$ rays emitted in the same neutron capture. We present for the first time angular correlation functions for two $\gamma$ rays produced during the electromagnetic cascade transitions in the (n, $\gamma$) reactions on $^{\rm 155}$Gd and $^{\rm 157}$Gd. As expected, we observe the mild angular correlations for the strong, but rare transitions from the resonance state to the two energy levels of known spin-parities. Contrariwise, we observe negligibly small angular correlations for arbitrary pairs of two $\gamma$ rays produced in the majority of cascade transitions from the resonance state to the dense continuum states

Gamma-ray spectra from thermal neutron capture on gadolinium-155 and natural gadolinium

Natural gadolinium is widely used for its excellent thermal neutron capture cross section, because of its two major isotopes: Gd-155 and Gd-157. We measured the gamma-ray spectra produced from the thermal neutron capture on targets comprising a natural gadolinium film and enriched Gd-155 (in Gd2O3 powder) in the energy range from 0.11 MeV to 8.0 MeV, using the ANNRI germanium spectrometer at MLF, J-PARC. The freshly analyzed data of the Gd-155(n,gamma) reaction are used to improve our previously developed model (ANNRI-Gd model) for the Gd-157(n,gamma) reaction [K. Hagiwara et al. [ANNRI-Gd Collaboration], Prog. Theor. Exp. Phys. 2019, 023D01 (2019)], and its performance confirmed with the independent data from the Gd-nat(n,gamma) reaction. This article completes the development of an efficient Monte Carlo model required to simulate and analyze particle interactions involving the thermal neutron captures on gadolinium in any relevant future experiments