Faculty Profiles - SHIMIZU Hirohiko

Papers - SHIMIZU Hirohiko

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Measurement of UV light emission of the nighttime Earth by Mini-EUSO for space-based UHECR observations Open Access

Shinozaki K., Bolmgren K., Barghini D., Battisti M., Belov A., Bertaina M., Bisconti F., Cambiè G., Capel F., Casolino M., Fenu F., Golzio A., Klimov P., Kungel V., Marcelli L., Miyamoto H., Piotrowski L.W., Plebaniak Z., Przybylak M., Szabelski J., Sakaki N., Takizawa Y., Abdellaoui G., Abe S., Adams J.H., Allard D., Alonso G., Anchordoqui L., Anzalone A., Arnone E., Asano K., Attallah R., Attoui H., Ave Pernas M., Bagheri M., Baláz J., Bakiri M., Bartocci S., Bayer J., Beldjilali B., Belenguer T., Belkhalfa N., Bellotti R., Benmessai K., Bertone P.F., Biermann P.L., Blaksley C., Blanc N., Blin-Bondil S., Bobik P., Bogomilov M., Bozzo E., Briz S., Bruno A., Caballero K.S., Cafagna F., Campana D., Capdevielle J.N., Caramete A., Caramete L., Carlson P., Caruso R., Cassardo C., Castellina A., Catalano O., Cellino A., Černý K., Chikawa M., Chiritoi G., Christl M.J., Colalillo R., Conti L., Cotto G., Crawford H.J., Cremonini R., Creusot A., de Castro Gónzalez A., de la Taille C., del Peral L., Diaz Damian A., Diesing R., Dinaucourt P., Djakonow A., Djemil T., Ebersoldt A., Ebisuzaki T., Eser J., Fernández-González S., Ferrarese S., Filippatos G., Finch W.I., Fornaro C., Fouka M., Franceschi A., Franchini S., Fuglesang C., Fujii T., Fukushima M.

Proceedings of Science Vol. 395 2022.3

Publisher：Proceedings of Science

The JEM-EUSO (Joint Experiment Missions for Extreme Universe Space Observatory) program aims at the realization of the ultra-high energy cosmic ray (UHECR) observation using wide field of view fluorescence detectors in orbit. Ultra-violet (UV) light emission from the atmosphere such as airglow and anthropogenic light on the Earth’s surface are the main background for the space-based UHECR observations. The Mini-EUSO mission has been operated on the International Space Station (ISS) since 2019 which is the first space-based experiment for the program. The Mini-EUSO instrument consists of a 25 cm refractive optics and the photo-detector module with the 2304-pixel array of the multi-anode photomultiplier tubes. On the nadir-looking window of the ISS, the instrument is capable of continuously monitoring a ∼300 km × 300 km area. In the present work, we report the preliminary result of the measurement of the UV light in the nighttime Earth using the Mini-EUSO data downlinked to the ground. We mapped UV light distribution both locally and globally below the ISS obit. Simulations were also made to characterize the instrument response to diffuse background light. We discuss the impact of such light on space-based UHECR observations and the Mini-EUSO science objectives.

DOI： 10.22323/1.395.0385

Expected performance of the K-EUSO space-based observatory Open Access

Bianciotto M., Abdellaoui G., Abe S., Adams J.H., Allard D., Alonso G., Anchordoqui L., Anzalone A., Arnone E., Asano K., Attallah R., Attoui H., Ave Pernas M., Bagheri M., Baláz J., Bakiri M., Barghini D., Bartocci S., Battisti M., Bayer J., Beldjilali B., Belenguer T., Belkhalfa N., Bellotti R., Belov A.A., Benmessai K., Bertaina M., Bertone P.F., Biermann P.L., Bisconti F., Blaksley C., Blanc N., Blin-Bondil S., Bobik P., Bogomilov M., Bolmgren K., Bozzo E., Briz S., Bruno A., Caballero K.S., Cafagna F., Cambié G., Campana D., Capdevielle J.N., Capel F., Caramete A., Caramete L., Carlson P., Caruso R., Casolino M., Cassardo C., Castellina A., Catalano O., Cellino A., Černý K., Chikawa M., Chiritoi G., Christl M.J., Colalillo R., Conti L., Cotto G., Crawford H.J., Cremonini R., Creusot A., de Castro Gónzalez A., de la Taille C., del Peral L., Diaz Damian A., Diesing R., Dinaucourt P., Djakonow A., Djemil T., Ebersoldt A., Ebisuzaki T., Eser J., Fenu F., Fernández-González S., Ferrarese S., Filippatos G., Finch W.I., Fornaro C., Fouka M., Franceschi A., Franchini S., Fuglesang C., Fujii T., Fukushima M., Galeotti P., García-Ortega E., Gardiol D., Garipov G.K., Gascón E., Gazda E., Genci J., Golzio A., González Alvarado C., Gorodetzky P., Green A., Guarino F., Guépin C.

Proceedings of Science Vol. 395 2022.3

Publisher：Proceedings of Science

K-EUSO is a planned mission of the JEM-EUSO program for the study of ultra-high energy cosmic rays (UHECR) from space, to be deployed on the International Space Station. The K-EUSO observatory consists of a UV telescope with a wide field of view, which aims at the detection of fluorescence light emitted by extensive air showers (EAS) in the atmosphere. The EAS events will be sampled with a time resolution of 1-2.5 μs to reconstruct the entire shower profile with high precision. The detector consisting of ∼ 105 independent pixels will allow a spatial resolution of ∼700 m on ground. From a 400 km altitude, K-EUSO will achieve a large and full sky exposure to sample the highest energy range of the UHECR spectrum. In this contribution, we present estimates of the performance of the observatory: an estimation of the expected exposure and triggered event rate as a function of energy and the event reconstruction performance, including resolution of arrival directions and energy of UHECRs.

DOI： 10.22323/1.395.0409

Expected Performance of the EUSO-SPB2 Fluorescence Telescope Open Access

Heaton C., Abdellaoui G., Abe S., Adams J.H., Allard D., Alonso G., Anchordoqui L., Anzalone A., Arnone E., Asano K., Attallah R., Attoui H., Ave Pernas M., Bagheri M., Baláz J., Bakiri M., Barghini D., Bartocci S., Battisti M., Bayer J., Beldjilali B., Belenguer T., Belkhalfa N., Bellotti R., Belov A.A., Benmessai K., Bertaina M., Bertone P.F., Biermann P.L., Bisconti F., Blaksley C., Blanc N., Blin-Bondil S., Bobik P., Bogomilov M., Bolmgren K., Bozzo E., Briz S., Bruno A., Caballero K.S., Cafagna F., Cambié G., Campana D., Capdevielle J.N., Capel F., Caramete A., Caramete L., Carlson P., Caruso R., Casolino M., Cassardo C., Castellina A., Catalano O., Cellino A., Černý K., Chikawa M., Chiritoi G., Christl M.J., Colalillo R., Conti L., Cotto G., Crawford H.J., Cremonini R., Creusot A., de Castro Gónzalez A., de la Taille C., del Peral L., Diaz Damian A., Diesing R., Dinaucourt P., Djakonow A., Djemil T., Ebersoldt A., Ebisuzaki T., Eser J., Fenu F., Fernández-González S., Ferrarese S., Filippatos G., Finch W.I., Fornaro C., Fouka M., Franceschi A., Franchini S., Fuglesang C., Fujii T., Fukushima M., Galeotti P., García-Ortega E., Gardiol D., Garipov G.K., Gascón E., Gazda E., Genci J., Golzio A., González Alvarado C., Gorodetzky P., Green A., Guarino F., Guépin C.

Proceedings of Science Vol. 395 2022.3

Publisher：Proceedings of Science

The Extreme Universe Space Observatory Super Pressure Balloon 2 (EUSO-SPB2) is under development, and will prototype instrumentation for future satellite-based missions, including the Probe of Extreme Multi-Messenger Astrophysics (POEMMA). EUSO-SPB2 will consist of two telescopes. The first is a Cherenkov telescope (CT) being developed to identify and estimate the background sources for future below-the-limb very high energy (E>10 PeV) astrophysical neutrino observations, as well as above-the-limb cosmic ray induced signals (E>1 PeV). The second is a fluorescence telescope (FT) being developed for detection of Ultra High Energy Cosmic Rays (UHECRs). In preparation for the expected launch in 2023, extensive simulations tuned by preliminary laboratory measurements have been performed to understand the FT capabilities. The energy threshold has been estimated at 1018.2 eV, and results in a maximum detection rate at 1018.6 eV when taking into account the shape of the UHECR spectrum. In addition, onboard software has been developed based on the simulations as well as experience with previous EUSO missions. This includes a level 1 trigger to be run on the computationally limited flight hardware, as well as a deep learning based prioritization algorithm in order to accommodate the balloon's telemetry budget. These techniques could also be used later for future, space-based missions.

DOI： 10.22323/1.395.0405

Measurement of nuclear spin relaxation time in lanthanum aluminate for development of polarized lanthanum target Open Access

Ishizaki K., Hotta H., Ide I., Iinuma M., Iwata T., Kitaguchi M., Kohri H., Miura D., Miyachi Y., Ohta T., Shimizu H.M., Yoshikawa H., Yosoi M.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Vol. 1020 2021.12

Language：Japanese Publisher：Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The nuclear spin–lattice relaxation time (T1) of lanthanum and aluminum nuclei in a single crystal of lanthanum aluminate doped with neodymium ions is studied to estimate the feasibility of the dynamically polarized lanthanum target applicable to beam experiments. The application of our interest is the study of fundamental discrete symmetries in the spin optics of epithermal neutrons. This study requires a highly flexible choice of the applied magnetic field for neutron spin control and favors longer T1 under lower magnetic field and at higher temperature. The T1 of 139La and 27Al was measured under magnetic fields of 0.5–2.5 T and at temperatures of 0.1–1.5 K and found widely distributed up to 100 h. The result suggests that the T1 can be as long as T1∼ 1 h at 0.1 K with a magnetic field of 0.1 T, which partially fulfills the requirement of the neutron beam experiment. Possible improvements to achieve a longer T1 are discussed.

DOI： 10.1016/j.nima.2021.165845

Pendellösung interferometry probes the neutron charge radius, lattice dynamics, and fifth forces Open Access

Heacock B., Fujiie T., Haun R.W., Henins A., Hirota K., Hosobata T., Huber M.G., Kitaguchi M., Pushin D.A., Shimizu H., Takeda M., Valdillez R., Yamagata Y., Young A.R.

Science Vol. 373 ( 6560 ) page： 1239 - 1243 2021.9

Language：Japanese Publisher：Science

Structure factors describe how incident radiation is scattered from materials such as silicon and germanium and characterize the physical interaction between the material and scattered particles. We used neutron Pendellösung interferometry to make precision measurements of the (220) and (400) neutron-silicon structure factors and achieved a factor-of-four improvement in the (111) structure factor uncertainty. These data provide measurements of the silicon Debye-Waller factor at room temperature and the mean square neutron charge radius 〈rn2 〉 ¼ -0:1101T0:0089 square femtometers. Combined with existing measurements of the Debye-Waller factor and charge radius, the measured structure factors also improve constraints on the strength of a Yukawa modification to gravity by an order of magnitude over the 20 picometer–to–10 nanometer length scale range.

DOI： 10.1126/science.abc2794

New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the HIBEAM/NNBAR experiment at the European Spallation Source Open Access

Addazi A., Anderson K., Ansell S., Babu K.S., Barrow J.L., Baxter D.V., Bentley P.M., Berezhiani Z., Bevilacqua R., Biondi R., Bohm C., Brooijmans G., Broussard L.J., Cederc ll J., Crawford C., Dev P.S.B., Dijulio D.D., Dolgov A.D., Dunne K., Fierlinger P., Fitzsimmons M.R., Fomin A., Frost M.J., Gardiner S., Gardner S., Galindo-Uribarri A., Geltenbort P., Girmohanta S., Golubev P., Golubeva E., Greene G.L., Greenshaw T., Gudkov V., Hall-Wilton R., Heilbronn L., Herrero-Garcia J., Holley A., Ichikawa G., Ito T.M., Iverson E., Johansson T., Jönsson L., Jwa Y.J., Kamyshkov Y., Kanaki K., Kearns E., Kokai Z., Kerbikov B., Kitaguchi M., Kittelmann T., Klinkby E., Kobakhidze A., Koerner L.W., Kopeliovich B., Kozela A., Kudryavtsev V., Kupsc A., Lee Y.T., Lindroos M., Makkinje J., Marquez J.I., Meirose B., Miller T.M., Milstead D., Mohapatra R.N., Morishima T., Muhrer G., Mumm H.P., Nagamoto K., Nepomuceno A., Nesti F., Nesvizhevsky V.V., Nilsson T., Oskarsson A., Paryev E., Pattie R.W., Penttil S., Perrey H., Pokotilovski Y.N., Potashnikovav I., Ramic K., Redding C., Richard J.M., Ries D., Rinaldi E., Rizzi N., Rossi N., Ruggles A., Rybolt B., Santoro V., Sarkar U., Saunders A., Senjanovic G., Serebrov A.P., Shimizu H.M., Shrock R., Silverstein S., Silvermyr D., Snow W.M., Takibayev A.

Journal of Physics G: Nuclear and Particle Physics Vol. 48 ( 7 ) 2021.7

Language：Japanese Publisher：Journal of Physics G: Nuclear and Particle Physics

The violation of baryon number, is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the Universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation Source to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron-antineutron oscillation via mixing, neutron-antineutron oscillation via regeneration from a sterile neutron state , and neutron disappearance (n → n′); the effective process of neutron regeneration is also possible. The program can be used to discover and characterize mixing in the neutron, antineutron and sterile neutron sectors. The experiment addresses topical open questions such as the origins of baryogenesis and the nature of dark matter, and is sensitive to scales of new physics substantially in excess of those available at colliders. A goal of the program is to open a discovery window to neutron conversion probabilities (sensitivities) by up to three orders of magnitude compared with previous searches. The opportunity to make such a leap in sensitivity tests should not be squandered. The experiment pulls together a diverse international team of physicists from the particle (collider and low energy) and nuclear physics communities, while also including specialists in neutronics and magnetics.

DOI： 10.1088/1361-6471/abf429

Energy-dependent angular distribution of individual γ rays in the la 139 (n,γ) la 140 ∗ reaction Open Access

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

Physical Review C Vol. 104 ( 1 ) 2021.6

Language：Japanese Publisher：Physical Review C

Neutron energy-dependent angular distributions were observed for individual γ rays from the 0.74 eV p-wave resonance of La139+n to several lower excited states of La140. The γ-ray signals were analyzed in a two-dimensional histogram of the γ-ray energy, measured with distributed germanium detectors, and neutron energy, determined with the time-of-flight of pulsed neutrons, to identify the neutron energy dependence of the angular distribution for each individual γ rays. The angular distribution was also found for a photopeak accompanied with a faint p-wave resonance component. Our results can be interpreted as interference between s- and p-wave amplitudes, which may be used to study discrete symmetries of fundamental interactions.

DOI： 10.1103/PhysRevC.104.014601

Measurement of γ rays from <sup>6</sup>LiF tile as an inner wall of a neutron-decay detector Open Access

Koga J., Ieki S., Kimura A., Kitaguchi M., Kitahara R., Mishima K., Nagakura N., Okudaira T., Otono H., Shimizu H.M., Sumi N., Takada S., Tomita T., Yamada T., Yoshioka T.

Journal of Instrumentation Vol. 16 ( 2 ) 2021.2

Language：Japanese Publisher：Journal of Instrumentation

A neutron lifetime measurement conducted at the Japan Proton Accelerator Research Complex (J-PARC) is counting the number of electrons from neutron decays with a time projection chamber (TPC). The γ rays produced in the TPC cause irreducible background events. To achieve the precise measurement, the inner walls of the TPC consist of 6Li-enriched lithium-fluoride (6LiF) tiles to suppress the amount of γ rays. In order to estimate the amount of γ rays from the 6LiF tile, prompt gamma ray analysis (PGA) measurements were performed using germanium detectors. We reconstructed the measured γ-ray energy spectrum using a Monte Carlo simulation with the stripping method. Comparing the measured spectrum with a simulated one, the number of γ rays emitted from the6LiF tile was (2.3+0.7-0.3) × 10-4 per incident neutron. This is 1.4+0.5-0.2 times the value assumed for a mole fraction of the 6LiF tile. We concluded that the amount of γ rays produced from the 6LiF tile is not more twice the originally assumed value.

DOI： 10.1088/1748-0221/16/02/P02001

Neutron Imaging Using a Fine-Grained Nuclear Emulsion Open Access

Hirota K., Ariga T., Hino M., Ichikawa G., Kawasaki S., Kitaguchi M., Mishima K., Muto N., Naganawa N., Shimizu H.M.

Journal of Imaging Vol. 7 ( 1 ) 2021.1

Language：Japanese Publisher：Journal of Imaging

A neutron detector using a fine-grained nuclear emulsion has a sub-micron spatial resolution and thus has potential to be applied as high-resolution neutron imaging. In this paper, we present two approaches to applying the emulsion detectors for neutron imaging. One is using a track analysis to derive the reaction points for high resolution. From an image obtained with a 9 µm pitch Gd grating with cold neutrons, periodic peak with a standard deviation of 1.3 µm was observed. The other is an approach without a track analysis for high-density irradiation. An internal structure of a crystal oscillator chip, with a scale of approximately 30 µm, was able to be observed after an image analysis.

DOI： 10.3390/jimaging7010004

Neutron lifetime measurement with pulsed cold neutrons Open Access

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

Progress of Theoretical and Experimental Physics Vol. 2020 ( 12 ) 2020.12

Language：Japanese Publisher：Progress of Theoretical and Experimental Physics

The neutron lifetime has been measured by comparing the decay rate with the reaction rate of 3He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the 3He(n,p)3H reaction using a gas chamber, the working gas of which contains diluted 3He. The measured neutron lifetime was 898 ± 10stat+15-18 sys s.

DOI： 10.1093/ptep/ptaa169

Proof-of-principle Experiment of <sup>4</sup>He Excimer Cluster Generation via Neutron-<sup>3</sup>He Absorption Reaction for Visualization of Velocity Fields in Superfluid <sup>4</sup>He

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

hamon Vol. 30 ( 4 ) page： 192 - 196 2020.11

Language：Japanese Publisher：The Japanese Society for Neutron Science

<p>For visualization of flows in superfluid <sup>4</sup>He, an excited helium molecule (excimer) <sup>4</sup>He<sub>2</sub><sup>*</sup> is an ideally suitable flow tracer, because it has a molecular size with a minimum influence to flow, and follows only normal-component flow around 1K but only vortices below 0.5 K. However, to visualize flow fields in 3D, small clouds (clusters) of <sup>4</sup>He<sub>2</sub><sup>*</sup> are required, whose generation method has not been established. To generate such clusters, we proposed the use of neutron-<sup>3</sup>He absorption reaction. In the proof-of-principle experiments, we have confirmed the <sup>4</sup>He<sub>2</sub><sup>*</sup> generation, while the detail of clusters still remains undetermined. The concept, methods, progress, and present status are shown.</p>

DOI： 10.5611/hamon.30.4_192

A Multi-Center Contouring Study of Spinal Cord Comparing MRI and Myelo-CT Fusion

Tanaka H., Aoyama T., Shimizu H., Tachibana H., Koide Y., Miyauchi R., Wakabayashi K., Ooshima Y., Adachi S., Kozai Y., Kodaira T.

INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Vol. 108 ( 3 ) page： E377 - E377 2020.11

Development and application of a <sup>3</sup>He Neutron Spin Filter at J-PARC Open Access

Okudaira T., Oku T., Ino T., Hayashida H., Kira H., Sakai K., Hiroi K., Takahashi S., Aizawa K., Endo H., Endo S., Hino M., Hirota K., Honda T., Ikeda K., Kakurai K., Kambara W., Kitaguchi M., Oda T., Ohshita H., Otomo T., Shimizu H.M., Shinohara T., Suzuki J., Yamamoto T.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Vol. 977 2020.10

Language：Japanese Publisher：Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

We are developing a neutron polarizer with polarized 3He gas, referred to as a 3He spin filter, based on the Spin Exchange Optical Pumping (SEOP) for polarized neutron scattering experiments at Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC). A 3He gas-filling station was constructed at J-PARC, and several 3He cells with long spin relaxation times have been fabricated using the gas-filling station. A laboratory has been prepared in the MLF beam hall for polarizing 3He cells, and compact pumping systems with laser powers of 30 W and 110 W, which can be installed onto a neutron beamline, have been developed. A 3He polarization of 85% was achieved at a neutron beamline by using the pumping system with the 110 W laser. Recently, the first user experiment utilizing the 3He spin filter was conducted, and there have been several more since then. The development and utilization of 3He spin filters at MLF of J-PARC are reported.

DOI： 10.1016/j.nima.2020.164301

A candidate secular variation model for IGRF-13 based on MHD dynamo simulation and 4DEnVar data assimilation

Minami Takuto, Nakano Shin'ya, Lesur Vincent, Takahashi Futoshi, Matsushima Masaki, Shimizu Hisayoshi, Nakashima Ryosuke, Taniguchi Hinami, Toh Hiroaki

EARTH PLANETS AND SPACE Vol. 72 ( 1 ) 2020.9

Language：Japanese Publisher：Earth, Planets and Space

We have submitted a secular variation (SV) candidate model for the thirteenth generation of International Geomagnetic Reference Field model (IGRF-13) using a data assimilation scheme and a magnetohydrodynamic (MHD) dynamo simulation code. This is the first contribution to the IGRF community from research groups in Japan. A geomagnetic field model derived from magnetic observatory hourly means, and CHAMP and Swarm-A satellite data, has been used as input data to the assimilation scheme. We adopt an ensemble-based assimilation scheme, called four-dimensional ensemble-based variational method (4DEnVar), which linearizes outputs of MHD dynamo simulation with respect to the deviation from a dynamo state vector at an initial condition. The data vector for the assimilation consists of the poloidal scalar potential of the geomagnetic field at the core surface and flow velocity field slightly below the core surface. Dimensionless time of numerical geodynamo is adjusted to the actual time by comparison of secular variation time scales. For SV prediction, we first generate an ensemble of dynamo simulation results from a free dynamo run. We then assimilate the ensemble to the data with a 10-year assimilation window through iterations, and finally forecast future SV by the weighted sum of the future extension parts of the ensemble members. Hindcast of the method for the assimilation window from 2004.50 to 2014.25 confirms that the linear approximation holds for 10-year assimilation window with our iterative ensemble renewal method. We demonstrate that the forecast performance of our data assimilation and forecast scheme is comparable with that of IGRF-12 by comparing data misfits 4.5 years after the release epoch. For estimation of our IGRF-13SV candidate model, we set assimilation window from 2009.50 to 2019.50. We generate our final SV candidate model by linear fitting for the weighted sum of the ensemble MHD dynamo simulation members from 2019.50 to 2025.00. We derive errors of our SV candidate model by one standard deviation of SV histograms based on all the ensemble members.[Figure not available: see fulltext.].

DOI： 10.1186/s40623-020-01253-8

Fluorescence Imaging of He<sub>2</sub><i><sup>* </sup></i>Excimers generated by neutron and gamma irradiation of superfluid Helium using a cold neutron beamline at J-PARC / MLF

Sonnenschein Volker Thomas, Matsushita Taku, Tsuji Yoshiyuki, Guo Wei, Hayashida Hiroshi, Hirota Katsuya, Kosuke Hiroi, Maruyama Takumi, Hishida Mayu, Tomita Hideki, Ito Daisuke, Kitaguchi Masaaki, Kiyanagi Yoshiaki, Sou Suzuki, Saito Yasushi, Shimizu Hirohiko, Shinohara Takenao, Wada Nobuo

JSAP Annual Meetings Extended Abstracts Vol. 2020.2 ( 0 ) page： 287 - 287 2020.8

3-D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan

Shito A., Matsumoto S., Ohkura T., Shimizu H., Sakai S., Iio Y., Takahashi H., Yakiwara H., Watanabe T., Kosuga M., Okada T., Yoshimi M., Asano Y.

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH Vol. 125 ( 8 ) 2020.8

Language：Japanese Publisher：Journal of Geophysical Research: Solid Earth

The attenuation of seismic wave energy is caused by intrinsic absorption and scattering. The former involves the conversion of seismic wave energy to heat energy via internal friction due to the anelasticity of the medium, whereas the latter involves the scattering of seismic wave energy due to random elastic heterogeneities in the medium. Quantifying both intrinsic ((Formula presented.)) and scattering ((Formula presented.)) attenuation is therefore important for understanding the physical properties of the Earth's interior and predicting seismic wave propagation. Here we develop a new procedure to separately map three-dimensional (3-D) (Formula presented.) and (Formula presented.) structures. The path-averaged (Formula presented.) and (Formula presented.) values are obtained via an envelope-fitting approach that employs a multiple-scattering model. The path-averaged (Formula presented.) and (Formula presented.) structures are then mapped into 3-D space using a tomographic inversion technique based on sensitivity kernels, which are calculated from a Monte Carlo simulation of the radiative transfer equations. We apply this method to map the crustal structure beneath Kyushu, Japan, and obtain 3-D (Formula presented.) and (Formula presented.) structures for the 1–2, 2–4, and 4–8 Hz frequency bands. The spatial attenuation patterns are similar for each of the analyzed frequency bands, with the spatial variability in (Formula presented.) being more pronounced than that in (Formula presented.). The high- (Formula presented.) and (Formula presented.) regions correspond to the locations of active volcanoes. Conversely, the northern Kyushu area possesses low- (Formula presented.) and (Formula presented.) zones that correspond to low heat flow and Cretaceous granite, respectively. The overall (Formula presented.) and (Formula presented.) distributions correlate with thermal and geological structures, respectively.

DOI： 10.1029/2019JB018742

Neutron spin dynamics in polarized targets Open Access

Gudkov V., Shimizu H.M.

Physical Review C Vol. 102 ( 1 ) 2020.7

Language：Japanese Publisher：Physical Review C

We present the neutron elastic scattering amplitude for an arbitrarily polarized target in an irreducible spherical-tensor representation. The general approach for the description of neutron spin dynamics for propagation through the medium with an arbitrary polarization is discussed in relation to the search for a time-reversal invariance violation in neutron scattering.

DOI： 10.1103/PhysRevC.102.015503

Transverse asymmetry of γ rays from neutron-induced compound states of La 140 Open Access

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

Physical Review C Vol. 101 ( 6 ) 2020.6

Language：Japanese Publisher：Physical Review C

An sp-mixing model, which describes a compound nuclear reaction by mixing partial waves, predicts a correlation term in this reaction. A detailed study of the sp-mixing model is required to study the feasibility of a new type of time reversal symmetry violation search experiment. The correlation term σn·(kn×kγ) in the La139(n - ,γ) reaction has been studied by measuring γ-ray and neutron energies utilizing epithermal polarized neutrons and germanium detectors. The transverse asymmetry for single γ-ray transition was measured to be 0.60±0.19 in the p-wave resonance.

DOI： 10.1103/PhysRevC.101.064624

An experimental setup for creating and imaging <sup>4</sup> He 2∗ excimer cluster tracers in superfluid helium-4 via neutron-<sup>3</sup>He absorption reaction

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

Review of Scientific Instruments Vol. 91 ( 3 ) 2020.3

Language：Japanese Publisher：Review of Scientific Instruments

For the purpose of future visualization of the flow field in superfluid helium-4, clusters of the triplet state excimer 4He2* are generated along the micro-scale recoil tracks of the neutron-absorption reaction n + 3He → 3T + p. This reaction is induced by neutron irradiation of the 3He fraction contained in natural isotopic abundance liquid helium with neutron beams either from the Japan Proton Accelerator Research Complex, Materials and Life Science Experimental Facility (JPARC)/Materials and Life Science Experimental Facility or from the Kyoto University Institute for Integrated Radiation and Nuclear Science. These 4He2* clusters are expected to be ideal tracers of the normal-fluid component in superfluid helium with several advantageous properties. Evidence of the excimer generation is inferred by detection of laser induced fluorescence emitted from the 4He2* clusters excited by a purpose-built short pulse gain-switched titanium:sapphire (Ti:sa) laser operating at a wavelength of 905 nm. The setup and performance characteristics of the laser system including the Ti:sa and two continuous wave re-pumping lasers are described. Detection at the fluorescence wavelength of 640 nm is performed by using optical bandpass filtered photomultiplier tubes (PMT). Electrical noise in the PMT acquisition traces could successfully be suppressed by post-processing with a simple algorithm. Despite other laser-related backgrounds, the excimer was clearly identified by its fluorescence decay characteristics. Production of the excimer was found to be proportional to the neutron flux, adjusted via insertion of different collimators into the neutron beam. These observations suggest that the apparatus we constructed does function in the expected manner and, therefore, has the potential for groundbreaking turbulence research with superfluid helium.

DOI： 10.1063/1.5130919

New energy-degrading beamline for in-flight RI beams, OEDO

Michimasa S., Imai N., Dozono M., Hwang J.W., Yamada K., Ota S., Yoshida K., Yanagisawa Y., Kusaka K., Ohtake M., Matsushita M., Ahn D.S., Beliuskina O., Chiga N., Chikaato K., Fukuda N., Hayakawa S., Ideguchi E., Iribe K., Iwamoto C., Kawase S., Kawata K., Kitamura N., Masuoka S., Miyatake H., Nagae D., Nakajima R., Nakamura T., Nakano K., Omika S., Otsu H., Sakurai H., Schrock P., Shimizu H., Shimizu Y., Sumikama T., Sun X., Suzuki D., Suzuki H., Takaki M., Takechi M., Takeda H., Takeuchi S., Teranishi T., Tsunoda R., Wang H., Watanabe Y., Watanabe Y.X., Wimmer K., Yako K., Yamaguchi H., Yang L., Yoshida H., Shimoura S.

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms Vol. 463 page： 143 - 147 2020.1

Publisher：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

The Optimized Energy Degrading Optics (OEDO) beamline was constructed at RIBF to produce slowed-down, well-focused radioactive-isotope beams at 10–50 MeV/u, and began operation in June 2017. We examined the performance of the OEDO system by decelerating high-energy medium-mass radioactive ions. The main components of the OEDO beamline are two superconducting quadrupole triplet magnets and one radio-frequency deflector. This paper introduces the unique design of the ion optics of the beamline and describes the achieved performance of the beamline in the commissioning and following physics experiments. We will discuss the properties of energy-degraded beams produced by the OEDO beamline by comparison of simulations and the achieved performance.

DOI： 10.1016/j.nimb.2019.06.006

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