Real-time monitoring method for gadolinium concentration in a water Cherenkov detector

Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara

Applied Physics A, 131, p.165_1 - 165_8, 2025/00

https://doi.org/10.1007/s00339-025-08283-7

Among various analytical methods for liquid samples, time-resolved laser-induced luminescence spectroscopy enables real-time measurements of Gd ion concentrations in aqueous solution without sample introduction into the spectrometer. In this work, we have developed a real-time monitoring method for Gd concentration in water. The detection limit was determined to be 60 ppb for Gd sulfate in ultrapure water. This value is about two orders of magnitude better than the reported value using laser-induced breakdown spectroscopy, and is close to that using inductively coupled plasma optical emission spectrometry which requires sample introduction into the spectrometer.

Production rates of long-lived radionuclides Be and Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxes

Sakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.

Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05

https://doi.org/10.1103/PhysRevD.109.102005

Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.

MIRS: an imaging spectrometer for the MMX mission

Barucci, M. A.*; Reess, J.-M.*; Bernardi, P.*; Doressoundiram, A.*; Fornasier, S.*; Le Du, M.*; Iwata, Takahiro*; Nakagawa, Hiromu*; Nakamura, Tomoki*; Andr, Y.*; et al.

Earth, Planets and Space (Internet), 73(1), p.211_1 - 211_28, 2021/12

https://doi.org/10.1186/s40623-021-01423-2

The MMX InfraRed Spectrometer (MIRS) is an imaging spectrometer on board of MMX JAXA mission. MIRS is built at LESIA-Paris Observatory in collaboration with four other French laboratories, collaboration and financial support of CNES and close collaboration with JAXA and MELCO. The instrument is designed to fully accomplish MMX's scientific and measurement objectives. MIRS will remotely provide near-infrared spectral maps of Phobos and Deimos containing compositional diagnostic spectral features that will be used to analyze the surface composition and to support the sampling site selection. MIRS will also study Mars atmosphere, in particular to spatial and temporal changes such as clouds, dust and water vapor.

scattering length from photoproduction on the proton near the reaction threshold

Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.

Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05

https://doi.org/10.1103/PhysRevC.101.052201

Radioactive Cs in the severely contaminated soils near the Fukushima Daiichi Nuclear Power Plant

Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.

Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09

https://doi.org/10.3389/fenrg.2015.00037

The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.

Design study around beam window of ADS

Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Kikuchi, Kenji; Kurata, Yuji; Sasa, Toshinobu; Umeno, Makoto*; Nishihara, Kenji; Saito, Shigeru; Mizumoto, Motoharu; Takano, Hideki*; et al.

Proceedings of 4th International Workshop on the Utilisation and Reliability of High Power Proton Accelerators, p.325 - 334, 2005/11

The Japan Atomic Energy Research Institute (JAERI) is conducting the research and development (R&D) on the Accelerator-Driven Subcritical System (ADS) for the effective transmutation of minor actinides (MAs). The ADS proposed by JAERI is the 800 MWth, Pb-Bi cooled, tank-type subcritical reactor loaded with (MA+Pu) nitride fuel. The Pb-Bi is also used as the spallation target. In this study, the feasibility of the ADS was discussed with putting the focus on the design around the beam window. The partition wall was placed between the target region and the ductless-type fuel assemblies to keep the good cooling performance for the hot-spot fuel pin. The flow control nozzle was installed to cool the beam window effectively. The thermal-hydraulic analysis showed that the maximum temperature at the outer surface of the beam window could be repressed below 500 C even in the case of the maximum beam power of 30 MW. The stress caused by the external pressure and the temperature distribution of the beam window was also below the allowable limit.

Evaluation of the effect of Gd ion emission on a water Cherenkov detector

Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ieki, Kei*; Ito, Chikara

no journal, , 

Emission characteristics of gadolinium ions (Gd) in water are studied to estimate the effect of ion emission on the water Cherenkov detector. The excitation spectrum of Gd was measured in the wavelength range of 245-255 nm, and it was confirmed that the ion emission intensity was proportional to the Gd concentration.

Emission spectroscopy of Gd ions in water using laser and its application to portable concentration monitor

Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara

no journal, , 

Emission characteristics of gadolinium ions (Gd) in water are studied to estimate the effect of ion emission on the water Cherenkov detector. While strong quenching by nitrate ions was observed, the effect of quenching by sulfate ions is considered negligible. The excitation spectrum of Gd was measured in the wavelength range of 245-255 nm, and the emission intensity increased by two orders of magnitude at resonance wavelengths. We are currently developing a portable Gd concentration monitor using this Gd ion emission.

Development of a portable gadolinium concentration monitor using laser-induced luminescence

Iwata, Yoshihiro; Sekiya, Hiroyuki*

no journal, , 

A portable monitor using laser-induced luminescence of gadolinium ions in water is under development for real-time measurements of gadolinium ion concentration and emission lifetime without water sampling. By using a photomultiplier tube with a bandpass filter instead of a monochromator, a detection sensitivity below 1 ppm can be expected.

Development status of a portable gadolinium monitor using laser-induced luminescence, 2

Iwata, Yoshihiro; Sekiya, Hiroyuki*

no journal, , 

A portable monitor using laser-induced luminescence of gadolinium ions in water is under development for real-time measurements of gadolinium concentration and emission lifetime without water sampling. A ns-pulsed laser, optical cell, photomultiplier tube (PMT), and power meter are mounted on a 450 mm 600 mm breadboard. The gadolinium concentration and emission lifetime are evaluated from the PMT signal of gadolinium ion emission at 312 nm generated in the optical cell. Using a simulated water circulation system, we successfully observed gadolinium ion emission signals at a concentration of 0.03%.