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Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.
Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11
Times Cited Count：0 Percentile：0.00(Optics)It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be 
m.
isomers in 
CfOrlandi, R.; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Ito, Yuta; Suzaki, Fumi; Nagame, Yuichiro*; et al.
Physical Review C, 106(6), p.064301_1 - 064301_11, 2022/12
Times Cited Count：1 Percentile：28.09(Physics, Nuclear)Nakamura, Tatsuya; To, Kentaro; Koizumi, Tomokatsu; Kiyanagi, Ryoji; Ohara, Takashi; Ebine, Masumi; Sakasai, Kaoru
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 2 Pages, 2022/11
A new thin position-sensitive scintillation neutron detectors have been developed to replace present scintillation detectors in SENJU diffractometer at J-PARC MLF. The SENJU diffractometer originally composed of 37 position-sensitive detectors, where each detector has neutron sensitive area of 256 256 mm with a pixel size of 4 4 mm. To renew some original detectors the new detectors have been developed based on ZnS scintillator and wavelength-shifting fibers technology. The developed replacement detectors were designed with a thin thickness of 12 cm, which is 40% of the original detector. The new detectors have also improved detector performances to the original ones in terms of detection efficiency (
60% for 2-A neutrons) and count uniformity (5-8%). The produced six detector modules have been implemented to the beamline after checking their detector performances in the lab.
To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*
Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 3 Pages, 2022/11
A real-time data display and storage module was developed for time-of-flight neutron measurement. The module can display real-time experimental data from two-dimensional neutron detector in a two-dimensional image, one-dimensional projection images in X- and Y-axis, and time-of-flight spectra. The module has two modes of operation: standard mode, and simple-display mode. The simple-display mode only displays the experimental results on the monitor and can operate faster than that in the standard mode because the module uses the limited function. Therefore, the simple-display mode is also useful for measurement of high-counting rate neutrons. Operation test using test pulses were performed to confirm the operating speed of the module. The module in standard and simple-display mode could measure the continuous test pulses without counting losses with a frequency of 1.0 and 1.6 MHz, respectively.
Nakamura, Tatsuya; To, Kentaro; Koizumi, Tomokatsu; Kiyanagi, Ryoji; Ohara, Takashi; Ebine, Masumi; Sakasai, Kaoru
Proceedings of 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2020), Vol.1, p.483 - 484, 2021/09
Two-dimensional neutron detectors were developed for the extension of SENJU time-of-flight Laue single crystal neutron diffractometer in J-PARC MLF. The detectors are to be installed at the additional detector bank for the SENJU instrument. The detector module is made based on ZnS scintillator and wavelength-shifting fiber technology, where each detector module maintains a neutron-sensitive area of 256256 mm with a pixel size of 44 mm. To meet the tight space limitation in the instrument, the detector was designed as compact as possible. The detector has a depth of 170 mm, which is about 40% smaller than that of the original SENJU detector. All four produced detectors exhibited similar detector performances: detection efficiency 50-60% for 2-
neutron, 
Co gamma-ray sensitivity 110
, count uniformity 3-6%.
Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
Times Cited Count：3 Percentile：21.36(Chemistry, Multidisciplinary)The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 
C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl
TaOCl
DbOCl. From the obtained experimental results, thermochemical data for DbOCl were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
Nakamura, Tatsuya; Kawasaki, Takuro; To, Kentaro; Harjo, S.; Sakasai, Kaoru; Aizawa, Kazuya
JPS Conference Proceedings (Internet), 33, p.011097_1 - 011097_6, 2021/03
A large area, two-dimensional scintillation neutron detector was developed for Takumi diffractometer in the J-PARC MLF. The detector is made based on a scintillator/wavelength shifting fiber technology. The detector has a neutron-sensitive area of 32 32 cm with a pixel size of 5 5 mm, which is about 1.5-fold larger than the SENJU detector TAKUMI is one of the neutron diffractometers in the MLF dedicated to use for engineering material research. The developed detector array adds new capabilities to the instrument to measure two-dimensional data collection at the back-scattering angles with a better time-of-flight resolution.
)Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.
Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03
Times Cited Count：9 Percentile：85.28(Agriculture, Dairy & Animal Science)We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.
To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*
Proceedings of 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2019), Vol.1, p.447 - 449, 2020/08
Times Cited Count：0 Percentile：0.08(Nuclear Science & Technology)A real-time data display and storage device was developed for pulsed neutron scattering experiments using the time-of-flight method. The device contains two sets of field programmable gate arrays and on-board microcomputers for data display and storage. The developed device can determine the time-of-flight and time-resolved neutron position data with a time range from 0 to 40 ms using a beam of pulsed neutrons at 25 Hz from an experimental facility. Operation tests were performed using test signals that simulate the neutron detector output signals. It was found that the device could separate double pulses with a time interval of 1 
s; furthermore, it could measure the continuous pulses with a frequency of 1 MHz. Consequently, it was confirmed that the developed device demonstrated a counting rate capability of beyond 1 Mcps.
Nakamura, Tatsuya; To, Kentaro; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru
Proceedings of 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2019), Vol.1, p.735 - 736, 2020/08
Times Cited Count：0 Percentile：0.08(Nuclear Science & Technology)A large area, position-sensitive scintillation neutron detector was developed for upgrading the SENJU, time-of-flight Laue single crystal neutron diffractometer, in J-PARC MLF. The detector has a neutron-sensitive area of 512 512 mm with a pixel size of 4 4 mm. The detector was developed for upgrading of the SENJU instrument. The large area detector is to be installed below the vacuum tank to enlarge a covering solid angle. A 
Li:ZnS (Ag) scintillator and wavelength-shifting fiber technologies are employed. Each fiber channel is read out individually with photon counting mode. The electronics boards are implemented at the backside of the detector, enabling the detector depth as short as 20 cm. The detector exhibited a detection efficiency of 45% for thermal neutron. No degradation in fiber position and in neutron sensitivity has been observed over one year after production. In this paper, detector design and detector performances are presented.
and 3
two-proton states in 
Po
populated by two-proton transferDupont, E.*; Astier, A.*; Petrache, C. M.*; Lv, B. F.*; Deloncle, I.*; Kiener, J.*; Orlandi, R.; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; et al.
Physical Review C, 101(1), p.014309_1 - 014309_6, 2020/01
Times Cited Count：2 Percentile：24.58(Physics, Nuclear)Nakamura, Tatsuya; Kawasaki, Takuro; To, Kentaro; Tsutsui, Noriaki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru
Proceedings of 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2018) (Internet), 3 Pages, 2019/10
A two-dimensional scintillation neutron detector with a submillimeter spatial resolution was developed for pulsed neutron diffraction imaging at the J-PARC MLF. The detector comprised the thin, single ZnS/LiF scintillator screen coupled with the crossed wavelength-shifting fiber array for light collection. For a high spatial resolution, the wavelength shifting fibers with diameter of 0.1 mm were used them for assembling the detector. The prototype detector that has a neutron-sensitive area of 24 24 mm exhibited a spatial resolution of 0.20
0.06 mm and 0.160.06 mm for x and y directions, respectively. The detector had a detection efficiency of 7
for thermal neutrons with a Co 
-ray sensitivity in the order of 10
. In this paper detailed detector design is presented together with experimental results using the pulsed neutron beam.
decay of 
Te with a novel recoil-decay scintillation detectorXiao, Y.*; Go, S.*; Grzywacz, R.*; Orlandi, R.; Andreyev, A. N.; Asai, Masato; Bentley, M. A.*; de Angelis, G.*; Gross, C. J.*; Hausladen, P.*; et al.
Physical Review C, 100(3), p.034315_1 - 034315_8, 2019/09
Times Cited Count：16 Percentile：83.79(Physics, Nuclear)Nakamura, Tatsuya; To, Kentaro; Tsutsui, Noriaki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru
Proceedings of 2016 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2016), Vol.2, p.1506 - 1508, 2018/01
Position-dependent neutron sensitivity within an element of the scintillator / wavelength-shifting fiber coil (SFC) was evaluated by using a collimated pulsed neutron beam at the J-PARC/MLF. The collimated beam that has a size of 1 1 mm was scanned over the SFC element. The neutron counts were recorded and plotted in each incident position. The scanning results showed less neutron sensitivity at the juncture of the rolled scintillator, suggesting less light collection efficiency or a lack of scintillator materials due to imperfect manufacturing process.
To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*
Journal of Instrumentation (Internet), 12(12), p.C12011_1 - C12011_8, 2017/12
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)A neutron-detection element using circular cathode bumps was developed for two-dimensional neutron measurement, and an irradiation experiment was performed using a 
Cf neutron source. The element has triangularly arranged small-sized circular cathode bumps, and the bumps are linked together in the x- and y-directions for the detection of incident neutrons. The element was arranged in the pressure vessel with a fill gas of composition He/(15%)CF
at 0.7 MPa. The detector system using bump cathode element exhibited a two-dimensional uniformity with a response of 10.1%. The average intrinsic spatial resolution was 1.89 mm full width at half maximum in the sensitive region, calculated by taking into account the track lengths of the secondary particles.
Nakamura, Tatsuya; To, Kentaro; Tsutsui, Noriaki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru
Journal of Instrumentation (Internet), 12(12), p.C12025_1 - C12025_9, 2017/12
Times Cited Count：2 Percentile：10.63(Instruments & Instrumentation)A high-spatial-resolution, large-area position-sensitive scintillation-based neutron detector module has been developed for a new time-of-flight Laue single-crystal diffractometer to be constructed at J-PARC MLF. A first prototype detector implementing commercial Li:ZnS screens was produced based on a scintillator/wavelength-shifting fibre technology. The detector exhibited a spatial resolution of 2.5 mm with a neutron-sensitive area of 320 320 mm. We report on an initial evaluation of the detector performance, including its spatial resolution, detection efficiency and long-term background measurement, and also provide a brief description of a new neutron instrument.
Nishio, Katsuhisa; Hirose, Kentaro; Vermeulen, M. J.; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Sato, Tetsuya; Nagame, Yuichiro; et al.
EPJ Web of Conferences, 163, p.00041_1 - 00041_6, 2017/11
Times Cited Count：1 Percentile：60.69(Nuclear Science & Technology)Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.
Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09
Neutron devices such as neutron detectors, optical devices including supermirror devices and 
He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.
Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru
Hamon, 27(1), p.4 - 7, 2017/01
Development of scintillation neutron detectors using wavelength-shifting fiber (WLSF) technology at J-PARC MLF is briefly reviewed. The neutron-detecting head of this type detector comprises neutron-sensitive scintillator screens and WLSFs for light read out. The light collection using WLSFs enables us to design a detector with great flexibility. Detector specifications such as pixel size, spatial resolution, and neutron-sensitive area can be optimized to requirements in specific applications. We have intensively developed these detectors since 2005. A large number of detector modules have been produced and delivered to the neutron scattering instruments in the MLF. In this paper the design of SENJU detector is presented in detail together with recent development effort for detector technology alternative to helium-3 gas detectors.
64 cm area position-sensitive scintillation neutron detector as an alternative to helium-3 gas based detectorNakamura, Tatsuya; To, Kentaro; Honda, Katsunori; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru
Proceedings of 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2015), Vol.1, p.680 - 683, 2016/11
A two-dimensional scintillation neutron detector that has neutron-sensitive area of 64 64 cm was developed for neutron scattering instruments by using wavelength shifting fibers technology. We designed the detector to have a pixel size of 20 20 mm. In order to compensate light attenuation occurred travelling along the wavelength-shifting fiber the scintillation light was read out from both sides of the fiber. The prototype detector exhibited a detection efficiency of 40% for 1.8 neutrons, which was similar to previously developed detector with a smaller size of 32 32 cm. The detailed detector design and experimental results measured by using the pulsed neutrons at the J-PARC/MLF are presented.
