Multiple mechanisms in proton-induced nucleon removal at 100 MeV/nucleon

Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.

Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04

https://doi.org/10.1103/PhysRevLett.130.172501

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.

Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes; Coulomb excitation of Hg, Hg, Hg and Hg

Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieliska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.

European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08

https://doi.org/10.1140/epja/i2019-12815-2

Shape coexistence in Hg

Mller-Gatermann, C.*; Dewald, A.*; Fransen, C.*; Auranen, K.*; Badran, H.*; Beckers, M.*; Blazhev, A.*; Braunroth, T.*; Cullen, D. M.*; Fruet, G.*; et al.

Physical Review C, 99(5), p.054325_1 - 054325_7, 2019/05

https://doi.org/10.1103/PhysRevC.99.054325

no abstracts in English

Uncertainty analysis of far-field precipitation from used nuclear fuel

Salazar, A.*; Fratoni, M.*; Ahn, J.*; Hirano, Fumio

Proceedings of 2017 International High-Level Radioactive Waste Management Conference (IHLRWM 2017) (CD-ROM), p.600 - 607, 2017/04

Effects of random geometry on post-closure repository criticality safety

Liu, X.*; Fratoni, M.*; Ahn, J.*; Hirano, Fumio

Proceedings of 2017 International High-Level Radioactive Waste Management Conference (IHLRWM 2017) (CD-ROM), p.595 - 599, 2017/04

Cosmic-ray test of a time-of-flight detector for double-strangeness experiments at J-PARC

Kim, S. H.*; Hwang, S.; Ahn, J. K.*; Ekawa, Hiroyuki; Hayakawa, Shuhei; Hong, B.*; Hosomi, Kenji; Imai, Kenichi; Kim, M. H.*; Lee, J. Y.*; et al.

Nuclear Instruments and Methods in Physics Research A, 795, p.39 - 44, 2015/09

https://doi.org/10.1016/j.nima.2015.05.046

A Criticality safety study for the disposal of damaged fuel debris

Liu, X.*; Ahn, J.*; Hirano, Fumio

Proceedings of 2015 International High-Level Radioactive Waste Management Conference (IHLRWM 2015) (CD-ROM), p.879 - 886, 2015/04

The present work focuses on neutronics analysis for the disposal of damaged fuels from Fukushima Nuclear Power Plants. MCNP calculations were performed for a canister containing fuel debris surrounded by buffer in deep geologic repository in a water-saturated reducing environment at different times after canister emplacement. The damaged fuel debris is modeled as spherical particles in a hexagonal lattice. Four different cases were compared based on various assumptions about moderation and fuel relocation. Based on the numerical results, the key findings include, (a) the calculated neutron multiplication factor () is sensitively dependent on assumptions related with moderation, (b) the carbon steel canister plays an important role in reducing the likelihood of criticality, (c) the maximum of the canister-buffer system could be achieved after a certain fraction of fissile nuclides has been released from the canister, and (d) under several assumptions, the maximum of the canister-buffer system could be only determined by the dimension and composition of the canister rather than the initial fuel loading.

Development of a prototype GEM TPC with a gating grid for an H-dibaryon search experiment at J-PARC

Sako, Hiroyuki; Sugimura, Hitoshi; Ahn, J. K.*; Han, Y.*; Hasegawa, Shoichi; Hwang, S. H.*; Ichikawa, Yudai; Imai, Kenichi; Kiuchi, Ryuta*; Ozawa, Kyoichiro; et al.

Nuclear Instruments and Methods in Physics Research A, 763, p.65 - 81, 2014/11

https://doi.org/10.1016/j.nima.2014.06.007

We developed a prototype TPC for an H-dibaryon search experiment at J-PARC. To investigate its performance, we conducted tests with Ar-CH (90:10) and Ar-CF (95:5), where the former is mainly used. The detection efficiency was measured to be 98% at the beam rate up to cps/cm, and 90% at the rate of cps/cm. Based on the measured horizontal resolution of 0.19-0.46 mm at the drift length of 5-20 cm, the position resolution of better than 0.3 mm is estimated in 1 T magnetic field. The ion backflow fraction was measured to be 5% and reduced up to 3% at the gain of . The horizontal position distortion due to ion backflow in the gate operation was suppressed within mm at the beam rates up to cps/cm. On the other hand, the distortion with the gate open was measured to be mm. The distortion in the final experiment is estimated to be mm.

Development of Hyperon Time-Projection-Chamber (HypTPC) for the -dibaryon search experiment at J-PARC

Hwang, S. H.*; Imai, Kenichi; Ahn, J. K.*

JPS Conference Proceedings (Internet), 1, p.013062_1 - 013062_4, 2014/03

https://doi.org/10.7566/jpscp.1.013062

Double- hypernuclei observed in a hybrid emulsion experiment

Ahn, J. K.*; Imai, Kenichi; Tanida, Kiyoshi; KEK-PS E373 Collaboration*

Physical Review C, 88(1), p.014003_1 - 014003_10, 2013/07

https://doi.org/10.1103/PhysRevC.88.014003

A hybrid experiment with nuclear emulsion and scintillating-fiber detectors (KEK-E373) has been performed to search for double-strangeness systems. Among about events of hyperons captured at rest by emulsion nuclei, we have observed four events which clearly show the topology of cascade weak decays of double- hypernuclei including event. We have revised the values of the two binding energy for event due to the recent change of the mass value. For another three events, we have determined possible species of double- hypernuclei together with their binding energies.