M. Arimoto
A5086879935- Gamma-ray bursts and supernovae
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Medical Imaging Techniques and Applications
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Advanced X-ray and CT Imaging
- SAS software applications and methods
- Nuclear Physics and Applications
- Radiation Detection and Scintillator Technologies
- Astronomy and Astrophysical Research
- Radiation Dose and Imaging
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Radiation Therapy and Dosimetry
- Solar and Space Plasma Dynamics
- Spacecraft Design and Technology
- Atomic and Subatomic Physics Research
- Statistical and numerical algorithms
- CCD and CMOS Imaging Sensors
- Advanced Radiotherapy Techniques
- Particle physics theoretical and experimental studies
- Particle Accelerators and Free-Electron Lasers
- Spacecraft and Cryogenic Technologies
Kanazawa University
2018-2024
Waseda University
2016-2024
Tokyo Institute of Technology
2005-2017
Stanford University
2017
KTH Royal Institute of Technology
2008
École Polytechnique
2007
Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Burst Monitor and Large Area Telescope onboard Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades gammaray energy. In September 2008, observed exceptionally luminous GRB 080916C, with largest apparent release yet measured. high-energy gamma rays to start later persist longer than lower photons. A simple spectral form fits entire...
Abstract The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present second catalog of LAT-detected GRBs, covering first 10 yr operations, 2008 to 2018 August 4. A total 186 GRBs are found; these, 91 show in range 30–100 MeV (17 which seen only this band) and 169 detected above 100 MeV. Most these sources were discovered by other instruments ( /GBM, Swift /BAT, AGILE, INTEGRAL ) or reported Interplanetary...
Abstract We report the discovery of GRB 221009A, highest flux gamma-ray burst (GRB) ever observed by Fermi Gamma-ray Burst Monitor (Fermi-GBM). This has continuous prompt emission lasting more than 600 s, which smoothly transitions to afterglow visible in Fermi-GBM energy range (8 keV–40 MeV), and total energetics higher any other sample. By using a variety new existing analysis techniques we probe spectral temporal evolution 221009A. find no prior trigger time ( t 0 ; 2022 October 9 at...
ABSTRACT The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mn>5</mml:mn> </mml:math> the sky and it completes a survey entire in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these could be...
Abstract We report on the observations of gamma-ray burst (GRB) 190114C by Fermi Gamma-ray Space Telescope and Neil Gehrels Swift Observatory . The prompt emission was detected GRB Monitor (GBM), Large Area (LAT), Burst Alert (BAT) long-lived afterglow subsequently observed GBM, LAT, X-ray (XRT), UV Optical Telescope. early-time reveal multiple components that evolve independently, with a delayed power-law component exhibits significant spectral attenuation above 40 MeV in first few seconds...
Cerium-doped Gd3(Ga, Al)5O12 (GAGG:Ce) is a promising novel scintillator for gamma-ray detectors. While GAGG:Ce has already been implemented in various commercial products, its detailed characteristics and response to high-energy particles gamma rays remain unknown. In particular, knowledge lacking on the radiation tolerance of this against proton irradiation expected future space satellite mission applications. study, we first investigate light-yield energy dependence, resolution, decay...
We set conservative constraints on decaying dark matter particles with masses spanning a very wide range (104−1016 GeV). For this we use multimessenger observations of cosmic-ray (CR) protons/antiprotons, electrons/positrons, neutrinos/antineutrinos and gamma rays. Focusing decays into the b channel, simulate spectra yields by using Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equations Pythia package. then propagate CRs origin till Earth state-of-the-art numerical frameworks CRPropa, GALPROP...
Considerable amounts of radioactive substances (mainly 137Cs and 134Cs) were released into the environment after Japanese nuclear disaster in 2011. Some restrictions on residence areas lifted April 2017, owing to successive effective decontamination operations. However, distribution vast mountain, forest satoyama close city is still unknown; thus, operations such are being hampered. In this paper, we report first aerial gamma-ray imaging a schoolyard Fukushima using drone that carries high...
We present a complete analysis of Fermi Large Area Telescope (LAT) data GRB 221009A, the brightest Gamma-Ray Burst (GRB) ever detected. The burst emission above 30 MeV detected by LAT preceded 1 s low-energy (< 10 MeV) pulse that triggered Monitor (GBM), as has been observed in other GRBs. prompt phase 221009A lasted few hundred seconds. It was so bright we identify Bad Time Interval (BTI) 64 seconds caused extremely high flux hard X-rays and soft gamma rays, during which event...
Broad line radio galaxies (BLRGs) are a rare type of radio-loud AGN, in which the broad optical permitted emission lines have been detected addition to extended jet emission. Here we report on deep (40ksec x4) observations bright BLRG 3C~120 using Suzaku. The were spaced week apart, and sample range continuum fluxes. An excellent broadband spectrum was obtained over two decades frequency (0.6 50 keV) within each 40 ksec exposure. We clearly resolved iron K complex, finding that it consists...
Monitoring the in vivo dose distribution proton therapy is desirable for accurate irradiation of a tumor. Although positron emission tomography (PET) widely used confirmation, obtained emitters produced by protons does not trace due to different physical processes. To estimate from PET image, cross sections nuclear reactions that produce are important yet far being sufficient. In this study, we measured 16O(p,x)15O, 16O(p,x)13N, and 16O(p,x)11C with wide-energy range (approximately 5-70 MeV)...
We are developing a wide-field X-ray monitor onboard the HiZ-GUNDAM mission. is future satellite mission for gamma-ray burst observation to lead time domain astronomy and multi-messenger astronomy. The pnCCD detectors will be used as focal plane detector, which back-illuminated CCD fully depleted by reverse-biased pn-junctions on front back sides. It has high sensitivity low-energy X-rays achieves frame rate with column-parallel readout. was originally developed astronomy, its radiation...
HiZ-GUNDAM is a future satellite mission whose concept was approved by ISAS/JAXA, and it one of the candidates JAXA's competitive medium-class mission. will lead time-domain astronomy in 2030s, its key sciences are (1) exploration early universe with high-redshift gamma-ray bursts, (2) contribution to multi-messenger astronomy. Two payloads aboard realize these two scientific issues. The wide field X-ray monitors which consist Lobster Eye optics array focal imaging sensor, monitor ~0.5...
The HiZ-GUNDAM mission is one of the candidates for JAXA's competitive M-class missions. revolutionizes our understanding high redshift universe and promotes multi-messenger astronomy. Combining a highly sensitive wide-field X-ray monitor, near-infrared telescope, autonomous spacecraft slew capability makes powerful machine to hunt interesting transients immediately identify their counterparts in near-infrared. Wide Field Monitor (WFXM) main instrument search soft band. WFXM comprises...
Abstract Temporal and spectral studies of short bursts ($\lesssim$ a few hundred milliseconds) are presented for the soft gamma repeaters (SGRs) 1806$-$20 1900$+$14 using HETE-2 samples. In five years from 2001 to 2005, localized 50 SGR1806$-$20 5 SGR 1900 $+$14. The cumulative number–intensity distribution in active year 2004 is well described by power-law model with an index $-$1.1$\pm$0.6. It consistent previous studies, but burst data taken other clearly give steeper distribution. This...
Abstract We have measured the linear polarization of hard X-ray emission from Crab in a previously unexplored energy interval, 20–120 keV. The introduction two new observational parameters, fraction and angle stands to disentangle geometrical physical effects, thereby providing information on pulsar wind geometry magnetic field environment. Measurements are conducted using PoGOLite Pathfinder – balloon-borne polarimeter. Polarization is determined by measuring azimuthal Compton scattering...
Abstract We present an analysis of eight years Fermi -LAT (>0.1 GeV) γ -ray data obtained for the radio galaxy NGC 1275. The flux from 1275 is highly variable on short (∼days to weeks) timescales, and has steadily increased over this year timespan. By examining changes in its spectral shape LAT energy band entire set, we found that behavior changed around 2011 February (∼MJD 55600). spectra at early times evolved largely high energies, while photon indices were unchanged later despite...
We developed an FPGA-based high-speed readout system for a complementary metal-oxide-semiconductor (CMOS) image sensor to observe soft X-ray transients in future satellite missions, such as HiZ-GUNDAM. Our previous research revealed that the CMOS has low-energy detection capability (0.4-4 keV) and strong radiation tolerance, which satisfies requirements of HiZ-GUNDAM mission. However, sensors typically have small pixel sizes (e.g., $\sim$10 ${\rm \mu m}$), resulting large volumes data....
HiZ-GUNDAM is a future satellite mission for gamma-ray burst observations. One of the instruments wide-field X-ray monitor with field view (FoV) 0.6 steradian at 0.4–4.0 keV, consisting Lobster Eye Optics (LEO) and pnCCD image sensors. LEOs need to be spatially well-aligned achieve both wide FoV fine position accuracy < 3 arcmin. To address this challenge, we explored an alignment method X-rays developed optical frame. This study reports on evaluation frame, our method, x-ray performance system.