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Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
Progress of Theoretical and Experimental Physics (Internet), 2022(12), p.123H01_1 - 123H01_12, 2022/12
Times Cited Count：2 Percentile：17.35(Physics, Multidisciplinary)In this work, we constructed an experimental setup based on time-resolved laser-induced luminescence spectroscopy to investigate the emission characteristics of Gd
ions in water. The excitation laser wavelength was tuned in the range of 245-255 nm, and large resonant peaks were observed at 246.2 nm and 252.3 nm with measured emission lifetimes of around 3 ms. Good linearity was observed between Gd concentration and emission intensity for these two wavelengths, indicating that our setup is useful for remote monitoring of Gd concentration.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
Nuclear Instruments and Methods in Physics Research A, 797, p.64 - 69, 2015/10
Times Cited Count：4 Percentile：30.91(Instruments & Instrumentation)An ultrasensitive resonance ionization mass spectrometer that can be applied to evaluate krypton (Kr) contamination in xenon (Xe) dark matter detectors has been developed for measuring Kr at the parts-per-trillion (ppt) or sub-ppt level in Xe. The gas sample is introduced without any condensation into a time-of-flight mass spectrometer through a pulsed supersonic valve. Using a nanosecond pulsed laser at 212.6 nm, 
Kr atoms in the sample are resonantly ionized along with other Kr isotopes. Kr ions are then mass separated and detected by the mass spectrometer in order to measure the Kr impurity concentration. With our current setup, approximately 0.4 ppt of Kr impurities contained in pure argon (Ar) gas are detectable with a measurement time of 1,000 s. Although Kr detection sensitivity in Xe is expected to be approximately half of that in Ar, our spectrometer can evaluate Kr contamination in Xe to the sub-ppt level.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
no abstracts in English
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
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no abstracts in English
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 emission lifetime is about 5 ms, and it was found that Gd emission measurement using a pulsed laser at 252.3 nm can be used for remote monitoring of Gd concentration in the range 0.01-0.1%.
ion emission properties in water using laserIwata, 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 quenching effect of sulfate ions is considered negligible. 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.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
no abstracts in English
Sekiya, Hiroyuki*; Iwata, Yoshihiro; Ito, Chikara
no journal, ,
no abstracts in English
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
no abstracts in English
Iwata, Yoshihiro; Sekiya, Hiroyuki*
no journal, ,
no abstracts in English
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
no abstracts in English
Rekimoto, Masafumi; Ando, Masato; Chikazawa, Yoshitaka; Kato, Atsushi; Hamano, Tomoharu; Shiohama, Yasutaka; Miyagawa, Takayuki*; Uzawa, Masayuki*; Hara, Hiroyuki*; Yamauchi, Kanau*; et al.
no journal, ,
no abstracts in English
ion emission lifetime in aqueous solution of Gd sulfateIwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
We are studying the measurement of Gd ion emission lifetime in aqueous solution of Gd sulfate. In this study, a nanosecond pulsed laser at 266 nm was used as the excitation light source, and emission at 312 nm was detected by a photomultiplier tube attached to a monochromator. The emission lifetime was measured to be about 2 ms, which was longer than that of other lanthanoid ions.
ion emission on a water Cherenkov detectorIwata, 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.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
The emission characteristics of gadolinium ions in aqueous solution such as quenching by anions and excitation spectra are studied using laser-induced luminescence spectroscopy. A simulation study is performed to estimate the gadolinium ion emission background rate from cosmic muons in the SK-Gd experiment. We are developing a portable monitoring system based on this spectroscopic technique to enable real-time measurements of gadolinium ion concentration and emission lifetime without contamination during water sampling.
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.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
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. This monitor is equipped with a laser irradiation cell connected to the sample tube, where gadolinium ion luminescence is generated by a ns pulsed laser at 266 nm and detected by a photomultiplier tube with a bandpass filter. Detailed design work is currently underway.
ions in water using laser and its application to portable concentration monitorIwata, 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.
ions in aqueous solution and its application to portable monitoring systemIwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
The emission characteristics of Gd ions in aqueous solution are studied using laser-induced luminescence spectroscopy to estimate the Gd emission background rate from cosmic muons in the SK-Gd experiment. This spectroscopy can also be applied to the development of a portable monitoring system that allows real-time measurements of the concentration and emission lifetime of Gd ions in the detector.
Iwata, Yoshihiro; Sekiya, Hiroyuki*; Ito, Chikara
no journal, ,
The excitation spectrum of gadolinium ion emission in water was measured using laser-induced luminescence spectroscopy, and a simulation study was performed to estimate the gadolinium ion emission background rate in the SK-Gd experiment. A portable gadolinium monitor has been developed using this spectroscopic technique, and the detection sensitivity 
~ppm was confirmed.
