Characterization of the thorium-229 defect structure in CaF crystals

Takatori, Sayuri*; Pimon, M.*; Pollitt, S.*; Bartokos, M.*; Beeks, K.*; Grneis, A.*; Hiraki, Takahiro*; Homma, Tetsuo*; Hosseini, N.*; Leitner, A.*; et al.

New Journal of Physics (Internet), 27(4), p.043024_1 - 043024_10, 2025/04

https://doi.org/10.1088/1367-2630/adce22

Recent reports on laser excitation of the low-energy thorium-229 (Th) nuclear isomeric state in calcium fluoride single crystals render this system a promising candidate for a solid-state nuclear clock. However, experimental characterization of the microscopic ion arrangement around the doped Th and its electronic charge state, crucial for the precise control of the clock transition and assessing the solid-state clock's performance, remains an unresolved task. This study uses X-ray absorption fine structure spectroscopy of Th:CaF to investigate the charge state and coordination environment of doped Th. The results indicate that Th is doped with a 4+ valence at the substitutional site of the Ca ion, with charge compensated provided by two F ions located at interstitial sites adjacent to Th.

Pulse shape discrimination in JSNS

Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; Suzuya, Kentaro; et al.

Progress of Theoretical and Experimental Physics (Internet), 2025(2), p.023H02_1 - 023H02_8, 2025/02

https://doi.org/10.1093/ptep/ptaf016

Stability enhancement by hydrophobic anchoring and a cross-linked structure of a phospholipid copolymer film for medical devices

Uchida, Kazuto*; Masuda, Tsukuru*; Hara, Shintaro*; Matsuo, Yoichi*; Liu, Y.*; Aoki, Hiroyuki; Asano, Yoshihiko*; Miyata, Kazuki*; Fukuma, Takeshi*; Ono, Toshiya*; et al.

ACS Applied Materials & Interfaces, 16(30), p.39104 - 39116, 2024/07

https://doi.org/10.1021/acsami.4c07752

The Acrylic vessel for JSNS-II neutrino target

Shin, C. D.*; Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; et al.

Journal of Instrumentation (Internet), 18(12), p.T12001_1 - T12001_9, 2023/12

https://doi.org/10.1088/1748-0221/18/12/T12001

Unified mercury radioactivity monitoring system at J-PARC and its operation experiences

Harada, Masahide; Sekijima, Mitsuaki*; Morikawa, Noriyuki*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Kai, Tetsuya; Kasugai, Yoshimi; Muto, Giichi*; Suzuki, Akio*; et al.

JPS Conference Proceedings (Internet), 33, p.011099_1 - 011099_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011099

In MLF at J-PARC, a unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a -ray energy analysis with Germanium semi-conductor detectors (Ge detectors). It is composed of three units of sampling port and radiation monitors: (1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, (2) CAM for atmosphere in the hot cell where the target loop is operated and (3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In April 2015, the UHAM activated when a small water coolant leakage from the water shroud of the mercury target occurred. VAM detected an abnormal increase of the counting rate in the helium vessel. It was also indicated that the measured radioactive nuclides were generated from the activation of the coolant (water) in the water shroud and not from the mercury.

Reaction-yield dependence of the (, ') reaction of U on the target thickness

Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Zen, H.*; Kii, Toshiteru*; Masuda, Kai*; Hori, Toshitada*; Hajima, Ryoichi; Shizuma, Toshiyuki; et al.

Journal of Nuclear Science and Technology, 52(6), p.811 - 820, 2015/06

https://doi.org/10.1080/00223131.2014.980348

The dependence of the nuclear resonance fluorescence (NRF) yield on the target thickness was studied. To this end, an NRF experiment was performed on U using a laser Compton back-scattering (LCS) -ray beam at the High Intensity -ray Source facility at Duke University.

The Spin state of iron in Fe-bearing Mg-perovskite and its crystal chemistry at high pressure

Mashimo, Izumi*; Otani, Eiji*; Hirao, Naohisa*; Mitsui, Takaya; Masuda, Ryo*; Seto, Makoto*; Sakai, Takeshi*; Takahashi, Suguru*; Nakano, Satoshi*

American Mineralogist, 99(8-9), p.1555 - 1561, 2014/08

https://doi.org/10.2138/am.2014.4659

Analysis of nuclear resonance fluorescence excitation measured with LaBr(Ce) detectors near 2 MeV

Omer, M.*; Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Bakr, M.*; Zen, H.*; Hori, Toshitada*; Kii, Toshiteru*; Masuda, Kai*; et al.

Nuclear Instruments and Methods in Physics Research A, 729, p.102 - 107, 2013/11

https://doi.org/10.1016/j.nima.2013.06.083

The performance of LaBr (Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussedin terms of limits of detection and in comparison with high-purity germanium (HPGe)detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity Gamma-ray Source (HIGS) facility of Duke University. The incident -rays, of 2.12 MeV energy, hit a BC target to excite the B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate theback ground and enhance the limits of detection for the spectra measured with LaBr (Ce). Both detection and determination limits were deduced from the experimental data.

Splash plasma channels produced by picosecond laser pulses in argon gas for laser wakefield acceleration

Mizuta, Yoshio*; Hosokai, Tomonao*; Masuda, Shinichi*; Zhidkov, A.*; Makito, Keigo*; Nakanii, Nobuhiko*; Kajino, Shohei*; Nishida, Akinori*; Kando, Masaki; Mori, Michiaki; et al.

Physical Review Special Topics; Accelerators and Beams, 15(12), p.121301_1 - 121301_10, 2012/12

https://doi.org/10.1103/PhysRevSTAB.15.121301

Analysis of ECRH pre-ionization for plasma start-up in JT-60SA

Hada, Kazuyoshi*; Nagasaki, Kazunobu*; Masuda, Kai*; Kinjo, Ryota*; Ide, Shunsuke; Isayama, Akihiko

Plasma and Fusion Research (Internet), 7(Sp.1), p.2403104_1 - 2403104_5, 2012/07

https://doi.org/10.1585/pfr.7.2403104

no abstracts in English