Motoki Hayashi

Shinshu University

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Y. Tameda

Osaka Electro-Communication University

Y. Tsunesada

Osaka Metropolitan University

Toshihiro Fujii

University of Chicago

T. Seki

Shinshu University

Jon Paul Lundquist

University of Nova Gorica

T. Nonaka

The University of Tokyo

K. Kadota

Tokyo City University

M. Tanaka

High Energy Accelerator Research Organization

R. Cady

University of Utah

S. Kawakami

Tokyo Metropolitan University

Cooperative Institutions

Consejo Nacional de Investigaciones Científicas y Técnicas

444

Instituto de Tecnologías en Detección y Astropartículas

401

University of Buenos Aires

388

Universidad Nacional de La Plata

379

National Technological University

359

Pierre Auger Observatory

353

Institute of Astronomy and Space Physics

352

National University of General San Martín

346

Institute of Scientific and Technical Research for Defense

255

The University of Tokyo

179

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Joint analysis of the energy spectrum of ultra-high-energy cosmic rays as measured at the Pierre Auger Observatory and the Telescope Array

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2021)

Y. Tsunesada Rasha Abbasi T. Abu‐Zayyad Monica Allen Yuto Arai

The measurement of the energy spectrum of ultra-high-energy cosmic rays (UHECRs) is of crucial importance to clarify their origin and acceleration mechanisms. The Pierre Auger Observatory in Argentina and the Telescope Array (TA) in the US have reported their measurements of UHECR energy spectra observed in the southern and northern hemisphere, respectively. The region of the sky accessible to both Observatories ($[-15,+24]$ degrees in declination) can be used to cross-calibrate the two spectra. The Auger-TA energy spectrum working group was organized in 2012 and has been working to understand the uncertainties in energy scale in both experiments, their systematic differences, and differences in the shape of the spectra. In previous works, we reported that there was an overall agreement of the energy spectra measured by the two observatories below 10 EeV while at higher energies, a remaining significant difference was observed in the common declination band. We revisit this issue to understand its origin by examining the systematic uncertainties, statistical effects, and other possibilities. We will also discuss the differences in the spectra in different declination bands and a new feature in the spectrum recently reported by the Auger Collaboration.

Pierre Auger Observatory

Right ascension

10.22323/1.395.0337

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Citations (27)

Search for point sources of ultra-high-energy photons with the Telescope Array surface detector

Monthly Notices of the Royal Astronomical Society (2019)

Rasha Abbasi Mitsuru Abe T. Abu‐Zayyad M. Allen R. Azuma

The surface detector (SD) of the Telescope Array (TA) experiment allows one to indirectly detect photons with energies of order $10^{18}$ eV and higher and to separate photons from the cosmic-ray background. In this paper we present the results of a blind search for point sources of ultra-high energy (UHE) photons in the Northern sky using the TA SD data. The photon-induced extensive air showers (EAS) are separated from the hadron-induced EAS background by means of a multivariate classifier based upon 16 parameters that characterize the air shower events. No significant evidence for the photon point sources is found. The upper limits are set on the flux of photons from each particular direction in the sky within the TA field of view, according to the experiment's angular resolution for photons. Average 95% C.L. upper limits for the point-source flux of photons with energies greater than $10^{18}$, $10^{18.5}$, $10^{19}$, $10^{19.5}$ and $10^{20}$ eV are $0.094$, $0.029$, $0.010$, $0.0073$ and $0.0058$ km$^{-2}$yr$^{-1}$ respectively. For the energies higher than $10^{18.5}$ eV, the photon point-source limits are set for the first time. Numerical results for each given direction in each energy range are provided as a supplement to this paper.

Air shower

Point source

10.1093/mnras/stz3618

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Citations (9)

Development of the Cosmic Ray Air Fluorescence Fresnel lens Telescope for a Next Generation UHECR Observatory

Y. Tameda Takayuki Tomida Motoki Hayashi Mashu Yamamoto D. Ikeda

Fresnel lens

10.7566/jpscp.19.011037

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Citations (1)

The UHECR dipole and quadrupole in the latest data from the original Auger and TA surface detectors

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2021)

P. Tinyakov Rogério de Almeida Rasha Abbasi T. Abu‐Zayyad Monica Allen

The sources of ultra-high-energy cosmic rays are still unknown, but assuming standard physics, they are expected to lie within a few hundred megaparsecs from us. Indeed, over cosmological distances cosmic rays lose energy to interactions with background photons, at a rate depending on their mass number and energy and properties of photonuclear interactions and photon backgrounds. The universe is not homogeneous at such scales, hence the distribution of the arrival directions of cosmic rays is expected to reflect the inhomogeneities in the distribution of galaxies; the shorter the energy loss lengths, the stronger the expected anisotropies. Galactic and intergalactic magnetic fields can blur and distort the picture, but the magnitudes of the largest-scale anisotropies, namely the dipole and quadrupole moments, are the most robust to their effects. Measuring them with no bias regardless of any higher-order multipoles is not possible except with full-sky coverage. In this work, we achieve this in three energy ranges (approximately 8--16 EeV, 16--32 EeV, and 32--$\infty$ EeV) by combining surface-detector data collected at the Pierre Auger Observatory until 2020 and at the Telescope Array (TA) until 2019, before the completion of the upgrades of the arrays with new scintillator detectors. We find that the full-sky coverage achieved by combining Auger and TA data reduces the uncertainties on the north-south components of the dipole and quadrupole in half compared to Auger-only results.

Pierre Auger Observatory

10.22323/1.395.0375

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Citations (13)

Friction characteristics between two micro/nano groove patterns

The Proceedings of Mechanical Engineering Congress Japan (2021)

Yasuhisa ANDO Toshifumi SHINYA Motoki Hayashi

In order to clarify friction characteristics by a combination of periodic surface patterns, friction tests were carried out using micro/nano groove patterns prepared on cylindrical surfaces. For the combinations between microgroove surfaces, the friction coefficients were affected by not only the groove geometry but direction of sliding. For the combinations between two nanostripe surfaces, the maximum friction coefficients were measured for the configuration that the grooves of the nanostripe on both surfaces are perpendicular to the sliding direction, and for the configuration that the grooves of the nanostripe on both surfaces are orthogonal to each other. For the former configuration, the sticking force generated by the slope of the microgroove was dominant in the measured friction force.

Groove (engineering)

10.1299/jsmemecj.2021.j111-17

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Citations (0)

EROSION EXPANSION MECHANISM OF COHESIVE (SILT) BANK BY THE STREAM FLOW

PROCEEDINGS OF HYDRAULIC ENGINEERING (1999)

Shoji FUKUOKA Akihide Watanabe Toshio KATAYAMA Eiji ITAYA Yukinori KASHIWAGI

It is important subject for controlling flood to estimate erosive resistance of natural riverbank. Several studies on the erosion of consisting of cohesive soil have been made in recent years. In those studies, only cross sectional erosion depth has been paid attention to. But, bank erosion depth increases with widening its area. And, failure of overhanging bank comes about by large erosion area.The point of this paper is that expansion mechanism of erosion area is examined. Indoor erosion experiments were given using undisturbed floodplain soil of the Yoshino River, Shikoku, Japan. In addition, overhanging banks are reproduced by hydraulic model to examine the longitudinal change of flow characteristics. As the consequence of those experiments, erosion process of cohesive bank and mechanism of failure of overhanging bank are clarified.

Bank erosion

Silt

Bank

10.2208/prohe.43.695

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Citations (7)

Studies on No-till Direct Seeding Culture of Rice on Well-Drained Paddy Field in Anjo Region : 3. No-tilled Rice Culture on Paddy Field Puddled in Winter Season

日本作物学会東海支部会報 (1996)

Yukihiro Hamada Ichiro Shaku Motoki Hayashi Yasuhiko Sawada

Paddy field

Source

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Citations (0)

Mass composition of ultrahigh-energy cosmic rays with the Telescope Array Surface Detector data

Physical review. D/Physical review. D. (2019)

Rasha Abbasi Mitsuru Abe T. Abu‐Zayyad M. Allen R. Azuma

The results on ultrahigh-energy cosmic rays (UHECR) mass composition obtained with the Telescope Array surface detector are presented. The analysis employs the Boosted Decision tree (BDT) multivariate analysis built upon 14 observables related to both the properties of the shower front and the lateral distribution function. The multivariate classifier is trained with Monte-Carlo sets of events induced by the primary protons and iron. An average atomic mass of UHECR is presented for energies $1{0}^{18.0}--1{0}^{20.0}\text{ }\text{ }\mathrm{eV}$. The average atomic mass of primary particles shows no significant energy dependence and corresponds to $⟨\mathrm{ln}A⟩=2.0\ifmmode\pm\else\textpm\fi{}0.1(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.44(\mathrm{syst}.)$. The result is compared to the mass composition obtained by the Telescope Array with ${\mathrm{X}}_{\mathrm{max}}$ technique along with the results of other experiments. Possible systematic errors of the method are discussed.

10.1103/physrevd.99.022002

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Citations (48)

A study of analysis method for the identification of UHECR source type

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2021)

Fugo Yoshida Rasha Abbasi T. Abu‐Zayyad Monica Allen Yuto Arai

The autocorrelation analysis using the arrival direction of Ultra High Energy Cosmic Rays (UHECRs) has been previously reported by the Telescope Array (TA) experiment. It is expected that the autocorrelation function reflects the source distribution. We simulate the expected arrival direction distribution of the cosmic rays using the catalogs of candidate sources. We take into account random deflection in the magnetic fields, with the magnitude of deflection determined by the charge and energy of the cosmic rays, coherence length and magnitude of the extragalactic magnetic field (EGMF), and by distance to source. In addition, in order to compare with the results of TA experiment, we consider the TA exposure. We compare the autocorrelation of the arrival directions corresponding to different source catalogs with the isotropic distribution. We calculate the autocorrelation function for each type of source candidates using this procedure. We will discuss the ability of this method to identify the source type of UHECRs.

10.22323/1.395.0242

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Comparison of microbial communities in percolating water from plow layer and subsoil layer estimated by phospholipid fatty acid (PLFA) analysis

Soil Science & Plant Nutrition (2002)

Miho Shimizu Motoki Hayashi Kazuo Matsuya Jun Murase Makoto Kimura

Abstract The amount and composition of phospholipid fatty acids (PLFAs) in the percolating water taken from different depths of soil (10 cm, PW10; 40 cm, PW40) and floodwater (FW) in a paddy field were compared during the period of rice cultivation. The amounts of PLFAs in PW10, PW40, and FW ranged from 22.6 to 46.2 μg L−1, from 22.3 to 54.5 μg L−1, and from 82.9 to 179.0 μg L−1, respectively. The PLFA profiles in PW10, PW40, and FW were similar to each other and 16 : 1ω7c, 18 : 1ω7, and 16 : 0 PLFAs were dominant components, irrespective of the sampling site and sampling time. High proportions of straight mono-unsaturated PLFAs ranging from 42.0 to 76.5% suggested that Gram-negative bacteria were the major members in the microbial communities of the water samples studied. A potential indicator of the environmental stresses imposed upon the microbiota that was represented by the trans vs. cis ratio of 16 : 17 PLFA was constantly low (< 0.05), indicating that the microbial communities at these sites were hardly stressed.

Subsoil

Plough

Paddy field

10.1080/00380768.2002.10408715

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Citations (8)