研究者詳細 - 清水　裕彦

Improved accuracy in the determination of the thermal cross section of 14N(n, p) 14C for neutron lifetime measurement Open Access

中性子ビームの速度均等化による高密度超冷中性子生成 Open Access

北口雅暁, 清水裕彦, 岩下芳久

加速器 16 巻 ( 3 ) 頁： 161 - 166 2019年10月

Kitahara R., Hirota K., Ieki S., Ino T., Iwashita Y., Kitaguchi M., Koga J., Mishima K., Morishita A., Nagakura N., Oide H., Otono H., Seki Y., Sekiba D., Shima T., Shimizu H.M., Sumi N., Sumino H., Taketani K., Tomita T., Yamada T., Yamashita S., Yokohashi M., Yoshioka T.

Progress of Theoretical and Experimental Physics 2019 巻 ( 9 ) 2019年9月

記述言語：日本語出版者・発行元：Progress of Theoretical and Experimental Physics

In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of 3He gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of 3He in the mixture. In order to improve the accuracy of the number density of the 3He nuclei, we have suggested using the 14N(n, p)14C reaction as a reference because this reaction involves similar kinetic energy to the 3He(n,p)3 H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the 14N(n,p)14C reaction at a neutron velocity of 2200 m s-1, measured relative to the 3He(n,p)3H reaction. The result was 1.868 \pm 0.003 (stat.) ± 0.006 (sys.) b. Additionally, the cross section of the 17O(n,α)14C reaction at the neutron velocity is also redetermined as 249 ± 6 mb.

DOI： 10.1093/ptep/ptz096

Ultra-violet imaging of the night-time earth by EUSO-Balloon towards space-based ultra-high energy cosmic ray observations Open Access

Abdellaoui G., Abe S., Adams J.H., Ahriche A., Allard D., Allen L., Alonso G., Anchordoqui L., Anzalone A., Arai Y., Asano K., Attallah R., Attoui H., Ave Pernas M., Bacholle S., Bakiri M., Baragatti P., Barrillon P., Bartocci S., Bayer J., Beldjilali B., Belenguer T., Belkhalfa N., Bellotti R., Belov A., Belov K., Benmessai K., Bertaina M., Biermann P.L., Biktemerova S., Bisconti F., Blanc N., Błȩcki J., Blin-Bondil S., Bobik P., Bogomilov M., Bozzo E., Briz S., Bruno A., Caballero K.S., Cafagna F., Campana D., Capdevielle J.N., Capel F., Caramete A., Caramete L., Carlson P., Caruso R., Casolino M., Cassardo C., Castellina A., Catalano C., Catalano O., Cellino A., Chikawa M., Chiritoi G., Christl M.J., Connaughton V., Conti L., Cordero G., Cotto G., Crawford H.J., Cremonini R., Csorna S., Cummings A., Dagoret-Campagne S., de Castro A.J., De Donato C., de la Taille C., De Santis C., del Peral L., Di Martino M., Diaz Damian A., Djemil T., Dutan I., Ebersoldt A., Ebisuzaki T., Engel R., Eser J., Fenu F., Fernández-González S., Ferrarese S., Flamini M., Fornaro C., Fouka M., Franceschi A., Franchini S., Fuglesang C., Fujii T., Fujimoto J., Fukushima M., Galeotti P., García-Ortega E., Garipov G., Gascón E., Genci J., Giraudo G., González Alvarado C., Gorodetzky P., Greg R.

Astroparticle Physics 111 巻頁： 54 - 71 2019年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astroparticle Physics

The JEM-EUSO (Joint Experiment Missions for the Extreme Universe Space Observatory) program aims at developing Ultra-Violet (UV) fluorescence telescopes for efficient detections of Extensive Air Showers (EASs) induced by Ultra-High Energy Cosmic Rays (UHECRs) from satellite orbit. In order to demonstrate key technologies for JEM-EUSO, we constructed the EUSO-Balloon instrument that consists of a ∼1 m 2 refractive telescope with two Fresnel lenses and an array of multi-anode photo-multiplier tubes at the focus. Distinguishing it from the former balloon-borne experiments, EUSO-Balloon has the capabilities of single photon counting with a gate time of 2.3 µs and of imaging with a total of 2304 pixels. As a pathfinder mission, the instrument was launched for an 8 h stratospheric flight on a moonless night in August 2014 over Timmins, Canada. In this work, we analyze the count rates over ∼2.5 h intervals. The measurements are of diffuse light, e.g. of airglow emission, back-scattered from the Earth's atmosphere as well as artificial light sources. Count rates from such diffuse light are a background for EAS detections in future missions and relevant factor for the analysis of EAS events. We also obtain the geographical distribution of the count rates over a ∼780 km 2 area along the balloon trajectory. In developed areas, light sources such as the airport, mines, and factories are clearly identified. This demonstrates the correct location of signals that will be required for the EAS analysis in future missions. Although a precise determination of count rates is relevant for the existing instruments, the absolute intensity of diffuse light is deduced for the limited conditions by assuming spectra models and considering simulations of the instrument response. Based on the study of diffuse light by EUSO-Balloon, we also discuss the implications for coming pathfinders and future space-based UHECR observation missions.

DOI： 10.1016/j.astropartphys.2018.10.008

Generation of 4 He 2∗ Clusters via Neutron- 3 He Absorption Reaction Toward Visualization of Full Velocity Field in Quantum Turbulence

Matsushita T., Sonnenschein V., Guo W., Hayashida H., Hiroi K., Hirota K., Iguchi T., Ito D., Kitaguchi M., Kiyanagi Y., Kokuryu S., Kubo W., Saito Y., Shimizu H.M., Shinohara T., Suzuki S., Tomita H., Tsuji Y., Wada N.

Journal of Low Temperature Physics 196 巻 ( 1-2 ) 頁： 275 - 282 2019年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Low Temperature Physics

For flow visualization study of quantum turbulence in superfluid 4He, He2∗ excimers are unique tracers which follow only normal-fluid component flow above 1 K. To generate detectable small He2∗ clouds (clusters) required for full-space velocity field measurements, we have adopted a new method based on neutron absorption reaction of 3He impurities in 4He and conducted proof-of-principle experiments. Generation of the He2∗ excimers was detected by laser-induced fluorescence using photomultiplier tubes. The fluorescence was observed to increase proportionally to the neutron flux, suggesting that a sufficient amount of He2∗ excimers were generated by neutrons. We also estimated the number of He2∗ excimers possibly generated by γ-rays and found that the relevant contribution was less than 40%. Thus, the majority of the He2∗ excimers was confirmed to be generated via n-3He absorption reactions.

DOI： 10.1007/s10909-018-02112-3

First ultracold neutrons produced at TRIUMF Open Access

Ahmed S., Altiere E., Andalib T., Bell B., Bidinosti C.P., Cudmore E., Das M., Davis C.A., Franke B., Gericke M., Giampa P., Gnyp P., Hansen-Romu S., Hatanaka K., Hayamizu T., Jamieson B., Jones D., Kawasaki S., Kikawa T., Kitaguchi M., Klassen W., Konaka A., Korkmaz E., Kuchler F., Lang M., Lee L., Lindner T., Madison K.W., Makida Y., Mammei J., Mammei R., Martin J.W., Matsumiya R., Miller E., Mishima K., Momose T., Okamura T., Page S., Picker R., Pierre E., Ramsay W.D., Rebenitsch L., Rehm F., Schreyer W., Shimizu H.M., Sidhu S., Sikora A., Smith J., Tanihata I., Thorsteinson B., Vanbergen S., Van Oers W.T.H., Watanabe Y.X.

Physical Review C 99 巻 ( 2 ) 2019年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review C

We installed a source for ultracold neutrons at a new, dedicated spallation target at TRIUMF. The source was originally developed in Japan and uses a superfluid-helium converter cooled to 0.9K. During an extensive test campaign in November 2017, we extracted up to 325000 ultracold neutrons after a one-minute irradiation of the target, over three times more than previously achieved with this source. The corresponding ultracold-neutron density in the whole production and guide volume is 5.3cm-3. The storage lifetime of ultracold neutrons in the source was initially 37 s and dropped to 24 s during the 18 days of operation. During continuous irradiation of the spallation target, we were able to detect a sustained ultracold-neutron rate of up to 1500s-1. Simulations of UCN production, UCN transport, temperature-dependent UCN yield, and temperature-dependent storage lifetime show excellent agreement with the experimental data and confirm that the ultracold-neutron-upscattering rate in superfluid helium is proportional to T7.

DOI： 10.1103/PhysRevC.99.025503

Corrigendum to “Pendellösung interferometry by using pulsed neutrons” (Nuclear Inst. and Methods in Physics Research, A (2018) 908 (78–81), (S0168900218309963) (10.1016/j.nima.2018.08.043)) Open Access

Itoh S., Nakaji M., Uchida Y., Kitaguchi M., Shimizu H.

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 918 巻頁： 99 - 99 2019年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment

Miller indices that the Pendellösung fringes were observed was not [Formula presented], but [Formula presented]. Therefore the description of [Formula presented] should be replaced to [Formula presented] for all in the statement and figures. In connection with this, the sentences from second line to fifth line in section 3 of 80 page should be renewed as follows. “Four diffraction peaks were observed for the [Formula presented], [Formula presented], [Formula presented], [Formula presented] planes. The diffraction peak of the [Formula presented] plane, which was in the Laue geometry condition, was analyzed for the demonstration of the Pendellösung fringes”. And Fig. 4 is replaced. The conclusion of this article is not affected due to these corrections.

DOI： 10.1016/j.nima.2018.10.218

清水裕彦

波紋 29 巻 ( 1 ) 頁： 41 - 43 2019年2月

記述言語：日本語出版者・発行元：日本中性子科学会

Analytic framework to quantitatively evaluate the performance of existing neutron scattering instruments would be valuable to find out new possibilities and potentials of slow neutron beams. A conceptual introduction of ongoing exploration for building up a framework is discussed.

DOI： 10.5611/hamon.29.1_41

CiNii Research

Verification of the compound nuclear model for T-violation search Open Access

Yamamoto T., Shimizu H.M., Ishizaki K., Niinomi Y., Kitaguchi M., Takada S., Koga J., Makise S., Yoshioka T., Kimura A., Sakai K., Oku T., Okudaira T., Endo S., Tani Y., Fujioka H., Yoshikawa H., Hirota K., Shima T.

Proceedings of Science 356 巻 2019年

記述言語：日本語出版者・発行元：Proceedings of Science

Large sources of parity violation have been observed in compound nuclear reactions. These enhancements are described by the compound nuclear model, which can be used to describe the angular correlation of γ-rays produced in (n; γ) reactions in medium-heavy nuclei. It has also been suggested that these same reactions could lead to a similar enhancement in time reversal violating processes. Therefore, we are interested in verifying the compound nuclear model by studying the (n; γ) reaction using polarized neutrons. In this paper, we discuss the installation and characterization of a neutron polarizer used in the (n; γ) measurement with transversely polarized neutrons.

DOI： 10.22323/1.356.0042

Polarized lanthanum target for the t-violation search in slow neutron transmission Open Access

Ishizaki K., Shimizu H.M., Kitaguchi M., Matsushita T., Iinuma M., Kohri H., Yoshikawa H., Yosoi M., Shima T., Iwata T., Miyachi Y., Ishimoto S., Fujita M., Ikeda Y.

Proceedings of Science 379 巻 2019年

記述言語：日本語出版者・発行元：Proceedings of Science

The Nd3+ doped LaAlO<inf>3</inf> crystal is a good candidate of a polarized 139La target for the search of the P-odd and T-odd interaction in the low-energy neutron absorption of 139La. As the first step for realizing the polarized 139La target, we grow the undoped LaAlO<inf>3</inf> crystal and the La<inf>1−x</inf>Nd<inf>x</inf>AlO<inf>3</inf> (x = 5 ×10−4) crystal by floating-zone method with four halogen lamps. The ESR measurements of Nd3+ in the latter crystal indicated that the linewidth was about 6 gauss, whose value is the same as the crystal in which 50 % 139La polarization was achieved in the previous DNP experiment. As the result, the crystals grown by this method can be applicable to the target study for the T-violation search.

DOI： 10.22323/1.379.0061

Development of the neutron polarizer for the T-violation search using compound nuclei Open Access

Okudaira T., Oku T., Sakai K., Ino T., Hayashida H., Hiroi K., Shinohara T., Kakurai K., Aizawa K., Shimizu H.M., Kitaguchi M., Yamamoto T.

Proceedings of Science 356 巻 2019年

記述言語：日本語出版者・発行元：Proceedings of Science

The fundamental parity violation is enhanced by 106 times at maximum in several neutron induced compound nuclei. There is a theoretical prediction that fundamental T-violating effects can be also largely enhanced in compound nuclei implying that T-violation can be searched for by making very sensitive measurements. A T-violation search experiment using compound nuclei is planned at J-PARC. Polarized epithermal neutron beam, polarized nuclear target, and high count rate neutron detector are necessary for the experiment, and therefore a development of the neutron polarizer using polarized 3He is ongoing at J-PARC in JAEA. Recently, a clean vacuum system to fabricate 3He spin filters was constructed, and several 3He spin filters were fabricated. The current status of the development of the 3He spin filter was reported.

DOI： 10.22323/1.356.0029