Kazuhiro Machida

University of Yamanashi

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Y. Tameda

Osaka Electro-Communication University

Toshihiro Fujii

University of Chicago

Y. Tsunesada

Osaka Metropolitan University

I. Myers

University of Utah

M. Ono

RIKEN

D. R. Bergman

University of Utah

O. Kalashev

Institute for Nuclear Research

W. Hanlon

University of Utah

МС

М. С. Пширков

Institute for Nuclear Research

Jon Paul Lundquist

University of Nova Gorica

Cooperative Institutions

Consejo Nacional de Investigaciones Científicas y Técnicas

527

Instituto de Tecnologías en Detección y Astropartículas

445

University of Buenos Aires

419

Universidad Nacional de La Plata

417

National University of General San Martín

389

Pierre Auger Observatory

378

Institute of Astronomy and Space Physics

377

National Technological University

374

Institute of Scientific and Technical Research for Defense

271

Karlsruhe Institute of Technology

193

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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)

ChemInform Abstract: Hydroformylation of ω‐Functionalized 1,1‐Disubstituted Alkenes and Its Use Toward the Synthesis of (.+‐.)‐Muscone.

ChemInform (1998)

Takashi Takahashi Kazuhiro Machida Yuki Kido Kensuke Nagashima Satoshi Ebata

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

10.1002/chin.199816264

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Citations (1)

[Viral isolation and identification].

PubMed (1998)

Kazuhiro Machida

Isolation

Identification

Source

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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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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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Citations (0)

Recent Development of Synthesizers for Combinatorial Chemistry.

触媒 (2001)

Kazuhiro Machida

Source

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UHECR mass composition from anisotropy of their arrival directions with the Telescope Array SD

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

M. Kuznetsov P. Tinyakov Rasha Abbasi T. Abu‐Zayyad Monica Allen

We propose a new method for the estimation of ultra-high energy cosmic ray (UHECR) mass composition from a distribution of their arrival directions. The method employs a test statistic (TS) based on a characteristic deflection of UHECR events with respect to the distribution of luminous matter in the local Universe modeled with a flux-weighed 2MRS catalog. Making realistic simulations of the mock UHECR sets, we show that this TS is robust to the presence of galactic and non-extreme extra-galactic magnetic fields and sensitive to the mass composition of events in a set. We apply the method to Telescope Array surface detector data for 11 years and derive new independent constraints on fraction of protons and iron in p-Fe mix at $E > 10$ EeV. At $10 < E < 100$ EeV the data favors increase of allowed proton fraction and decrease of allowed iron fraction, while at $E > 100$ EeV --- pure iron or even more massive composition. This result is in tension with Auger composition model inferred from spectrum-$X_{max}$ fit at $2.7\sigma$ ($2.0\sigma$) for PT'11 (JF'12) regular GMF model.

Mass fraction

10.22323/1.395.0294

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Citations (1)

Regioselective biooxidation of (+)-valencene by recombinant E. coli expressing CYP109B1 from Bacillus subtilis in a two-liquid-phase system

Microbial Cell Factories (2009)

Marco Girhard Kazuhiro Machida Masashi Itoh Rolf D. Schmid Akira Arisawa

(+)-Nootkatone (4) is a high added-value compound found in grapefruit juice. Allylic oxidation of the sesquiterpene (+)-valencene (1) provides an attractive route to this sought-after flavoring. So far, chemical methods to produce (+)-nootkatone (4) from (+)-valencene (1) involve unsafe toxic compounds, whereas several biotechnological approaches applied yield large amounts of undesirable byproducts. In the present work 125 cytochrome P450 enzymes from bacteria were tested for regioselective oxidation of (+)-valencene (1) at allylic C2-position to produce (+)-nootkatone (4) via cis- (2) or trans-nootkatol (3). The P450 activity was supported by the co-expression of putidaredoxin reductase (PdR) and putidaredoxin (Pdx) from Pseudomonas putida in Escherichia coli.Addressing the whole-cell system, the cytochrome CYP109B1 from Bacillus subtilis was found to catalyze the oxidation of (+)-valencene (1) yielding nootkatol (2 and 3) and (+)-nootkatone (4). However, when the in vivo biooxidation of (+)-valencene (1) with CYP109B1 was carried out in an aqueous milieu, a number of undesired multi-oxygenated products has also been observed accounting for approximately 35% of the total product. The formation of these byproducts was significantly reduced when aqueous-organic two-liquid-phase systems with four water immiscible organic solvents - isooctane, n-octane, dodecane or hexadecane - were set up, resulting in accumulation of nootkatol (2 and 3) and (+)-nootkatone (4) of up to 97% of the total product. The best productivity of 120 mg l-1 of desired products was achieved within 8 h in the system comprising 10% dodecane.This study demonstrates that the identification of new P450s capable of producing valuable compounds can basically be achieved by screening of recombinant P450 libraries. The biphasic reaction system described in this work presents an attractive way for the production of (+)-nootkatone (4), as it is safe and can easily be controlled and scaled up.

Dodecane

Hexadecane

Aqueous two-phase system

10.1186/1475-2859-8-36

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Citations (93)

Octocopter Light Source Test at the Telescope Array Site

International Cosmic Ray Conference (2013)

Kazuhiro Machida K. Honda M. Takeda Toshihiro Fujii D. Ikeda

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