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Search Results: 1 - 10 of 324939 matches for " S. Kabuki "
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Development of an atmospheric Cherenkov imaging camera for the CANGAROO-III experiment
S. Kabuki,K. Tsuchiya,K. Okumura,R. Enomoto,T. Uchida,H. Tsunoo,Shin. Hayashi,Sei. Hayashi,F. Kajino,A. Maeshiro,I. Tada,C. Itoh,CANGAROO-II collaboration
Physics , 2002, DOI: 10.1016/S0168-9002(03)00331-0
Abstract: A Cherenkov imaging camera for the CANGAROO-III experiment has been developed for observations of gamma-ray induced air-showers at energies from 10$^{11}$ to 10$^{14}$ eV. The camera consists of 427 pixels, arranged in a hexagonal shape at 0.17$^\circ$ intervals, each of which is a 3/4-inch diameter photomultiplier module with a Winston-cone--shaped light guide. The camera was designed to have a large dynamic range of signal linearity, a wider field of view, and an improvement in photon collection efficiency compared with the CANGAROO-II camera. The camera, and a number of the calibration experiments made to test its performance, are described in detail in this paper.
Performance of a new electron-tracking Compton camera under intense radiations from a water target irradiated with a proton beam
Yoshihiro Matsuoka,T. Tanimori,H. Kubo,A. Takada,J. D. Parker,T. Mizumoto,Y. Mizumura,S. Iwaki,T. Sawano,S. Komura,T. Kishimoto,M. Oda,T. Takemura,S. Miyamoto,S. Sonoda,D. Tomono,K. Miuchi,S. Kabuki,S. Kurosawa
Physics , 2014, DOI: 10.1088/1748-0221/10/01/C01053
Abstract: We have developed an electron-tracking Compton camera (ETCC) for use in next-generation MeV gamma ray telescopes. An ETCC consists of a gaseous time projection chamber (TPC) and pixel scintillator arrays (PSAs). Since the TPC measures the three dimensional tracks of Compton-recoil electrons, the ETCC can completely reconstruct the incident gamma rays. Moreover, the ETCC demonstrates efficient background rejection power in Compton-kinematics tests, identifies particle from the energy deposit rate (dE/dX) registered in the TPC, and provides high quality imaging by completely reconstructing the Compton scattering process. We are planning the "Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment" (SMILE) for our proposed all-sky survey satellite. Performance tests of a mid-sized 30 cm-cubic ETCC, constructed for observing the Crab nebula, are ongoing. However, observations at balloon altitudes or satellite orbits are obstructed by radiation background from the atmosphere and the detector itself. The background rejection power was checked using proton accelerator experiments conducted at the Research Center for Nuclear Physics, Osaka University. To create the intense radiation fields encountered in space, which comprise gamma rays, neutrons, protons, and other energetic entities, we irradiated a water target with a 140 MeV proton beam and placed a SMILE-II ETCC near the target. In this situation, the counting rate was five times than that expected at the balloon altitude. Nonetheless, the ETCC stably operated and identified particles sufficiently to obtain a clear gamma ray image of the checking source. Here, we report the performance of our detector and demonstrate its effective background rejection based in electron tracking experiments.
Development of a 30 cm-cube Electron-Tracking Compton Camera for the SMILE-II Experiment
Y. Mizumura,T. Tanimori,H. Kubo,A. Takada,J. D. Parker,T. Mizumoto,S. Sonoda,D. Tomono,T. Sawano,K. Nakamura,Y. Matsuoka,S. Komura,S. Nakamura,M. Oda,K. Miuchi,S. Kabuki,Y. Kishimoto,S. Kurosawa,S. Iwaki
Physics , 2013, DOI: 10.1088/1748-0221/9/05/C05045
Abstract: To explore the sub-MeV/MeV gamma-ray window for astronomy, we have developed the Electron-Tracking Compton Camera (ETCC), and carried out the first performance test at room condition using several gamma-ray sources in the sub-MeV energy band. Using a simple track analysis for a quick first test of the performance, the gamma-ray imaging capability was demonstrated by clear images and 5.3 degrees of angular resolution measure (ARM) measured at 662 keV. As the greatest impact of this work, a gamma-ray detection efficiency on the order of $10^{-4}$ was achieved at the sub-MeV gamma-ray band, which is one order of magnitude higher than our previous experiment. This angular resolution and detection efficiency enables us to detect the Crab Nebula at the 5 sigma level with several hours observation at balloon altitude in middle latitude. Furthermore, good consistency of efficiencies between this performance test and simulation including only physical processes has a large importance; it means we achieve nearly 100% detection of Compton recoil electrons. Thus, our estimation of enhancements by upgrades of the detector is more dependable. We are planning to confirm the imaging capability of the ETCC by observation of celestial objects in the SMILE-II (Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment II). The SMILE-II and following SMILE-III project will be an important key of sub-MeV/MeV gamma-ray astronomy.
Neutron imaging detector based on the muPIC micro-pixel chamber
J. D. Parker,K. Hattori,H. Fujioka,M. Harada,S. Iwaki,S. Kabuki,Y. Kishimoto,H. Kubo,S. Kurosawa,K. Miuchi,T. Nagae,H. Nishimura,T. Oku,T. Sawano,T. Shinohara,J. Suzuki,A. Takada,T. Tanimori,K. Ueno
Physics , 2012, DOI: 10.1016/j.nima.2012.08.036
Abstract: We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds.
Searches for very high energy gamma rays from blazars with CANGAROO-III telescope in 2005-2009
Y. Mizumura,J. Kushida,K. Nishijima,G. V. Bicknell,R. W. Clay,P. G. Edwards,S. Gunji,S. Hara,S. Hayashi,S. Kabuki,F. Kajino,A. Kawachi,T. Kifune,R. Kiuchi,K. Kodani,Y. Matsubara,T. Mizukami,Y. Mizumoto,M. Mori,H. Muraishi,T. Naito,M. Ohishi,V. Stamatescu,D. L. Swaby,T. Tanimori,G. Thornton,F. Tokanai,T. Toyama,S. Yanagita,T. Yoshida,T. Yoshikoshi
Physics , 2012, DOI: 10.1016/j.astropartphys.2012.01.002
Abstract: We have searched for very high energy (VHE) gamma rays from four blazars using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C 279, performed from 2005 to 2009, applying a new analysis to suppress the effects of the position dependence of Cherenkov images in the field of view. No significant VHE gamma ray emission was detected from any of the four blazars. The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT archival data. Non-simultaneous wide range (radio to VHE gamma-ray bands) spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV gamma-ray spectra, and archival data are discussed using a one-zone synchrotron self-Compton (SSC) model in combination with a external Compton (EC) radiation. The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model, and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC model. We find a consistency with the blazar sequence in terms of strength of magnetic field and component size.
CANGAROO-III Observation of TeV Gamma Rays from the vicinity of PSR B1 706-44
R. Enomoto,J. Kushida,T. Nakamori,T. Kifune,G. V. Bicknell,R. W. Clay,P. G. Edwards,S. Gunji,S. Hara,T. Hara,T. Hattori,S. Hayashi,Y. Higashi,Y. Hirai,K. Inoue,H. Ishioka,S. Kabuki,F. Kajino,H. Katagiri,A. Kawachi,R. Kiuchi,H. Kubo,T. Kunisawa,T. Matoba,Y. Matsubara,I. Matsuzawa,T. Mizukami,Y. Mizumura,Y. Mizumoto,M. Mori,H. Muraishi,T. Naito,S. Nakano,K. Nishijima,M. Ohishi,Y. Otake,S. Ryoki,K. Saito,Y. Sakamoto,A. Seki,V. Stamatescu,T. Suzuki,D. L. Swaby,T. Tanimori,G. Thornton,F. Tokanai,K. Tsuchiya,S. Watanabe,E. Yamazaki,S. Yanagita,T. Yoshida,T. Yoshikoshi,Y. Yukawa
Physics , 2009, DOI: 10.1088/0004-637X/703/2/1725
Abstract: Observation by the CANGAROO-III stereoscopic system of the Imaging Cherenkov Telescope has detected extended emission of TeV gamma rays in the vicinity of the pulsar PSR B1706$-$44. The strength of the signal observed as gamma-ray-like events varies when we apply different ways of emulating background events. The reason for such uncertainties is argued in relevance to gamma-rays embedded in the "off-source data", that is, unknown sources and diffuse emission in the Galactic plane, namely, the existence of a complex structure of TeV gamma-ray emission around PSR B1706$-$44.
CANGAROO-III search for TeV Gamma-rays from two clusters of galaxies
R. Kiuchi,M. Mori,G. V. Bicknell,R. W. Clay,P. G. Edwards,R. Enomoto,S. Gunji,S. Hara,T. Hara,T. Hattori,S. Hayashi,Y. Higashi,Y. Hirai,K. Inoue,C. Itoh,S. Kabuki,F. Kajino,H. Katagiri,A. Kawachi,T. Kifune,H. Kubo,J. Kushida,Y. Matsubara,T. Mizukami,Y. Mizumoto,R. Mizuniwa,H. Muraishi,Y. Muraki,T. Naito,T. Nakamori,S. Nakano,D. Nishida,K. Nishijima,M. Ohishi,Y. Sakamoto,A. Seki,V. Stamatescu,T. Suzuki,D. L. Swaby,T. Tanimori,G. Thornton,F. Tokanai,K. Tsuchiya,S. Watanabe,Y. Yamada,E. Yamazaki,S. Yanagita,T. Yoshida,T. Yoshikoshi,Y. Yukawa
Physics , 2009, DOI: 10.1088/0004-637X/704/1/240
Abstract: Because accretion and merger shocks in clusters of galaxies may accelerate particles to high energies, clusters are candidate sites for the origin of ultra-high-energy (UHE) cosmic-rays. A prediction was presented for gamma-ray emission from a cluster of galaxies at a detectable level with the current generation of imaging atmospheric Cherenkov telescopes. The gamma-ray emission was produced via inverse Compton upscattering of cosmic microwave background (CMB) photons by electron-positron pairs generated by collisions of UHE cosmic rays in the cluster. We observed two clusters of galaxies, Abell 3667 and Abell 4038, searching for very-high-energy gamma-ray emission with the CANGAROO-III atmospheric Cherenkov telescope system in 2006. The analysis showed no significant excess around these clusters, yielding upper limits on the gamma-ray emission. From a comparison of the upper limit for the north-west radio relic region of Abell 3667 with a model prediction, we derive a lower limit for the magnetic field of the region of ~0.1 micro G. This shows the potential of gamma-ray observations in studies of the cluster environment. We also discuss the flux upper limit from cluster center regions using a model of gamma-ray emission from neutral pions produced in hadronic collisions of cosmic-ray protons with the intra-cluster medium (ICM). The derived upper limit of the cosmic-ray energy density within this framework is an order of magnitude higher than that of our Galaxy.
CANGAROO-III observation of TeV gamma rays from the unidentified gamma-ray source HESS J1614-518
T. Mizukami,H. Kubo,T. Yoshida,T. Nakamori,R. Enomoto,T. Tanimori,M. Akimoto,G. V. Bicknell,R. W. Clay,P. G. Edwards,S. Gunji,S. Hara,T. Hara,S. Hayashi,H. Ishioka,S. Kabuki,F. Kajino,H. Katagiri,A. Kawachi,T. Kifune,R. Kiuchi,T. Kunisawa,J. Kushida,T. Matoba,Y. Matsubara,I. Matsuzawa,Y. Mizumura,Y. Mizumoto,M. Mori,H. Muraishi,T. Naito,K. Nakayama,K. Nishijima,M. Ohishi,Y. Otake,S. Ryoki,K. Saito,Y. Sakamoto,V. Stamatescu,T. Suzuki,D. L. Swaby,G. Thornton,F. Tokanai,Y. Toyota,K. Tsuchiya,S. Yanagita,Y. Yokoe,T. Yoshikoshi,Y. Yukawa
Physics , 2011, DOI: 10.1088/0004-637X/740/2/78
Abstract: We report the detection, with the CANGAROO-III imaging atmospheric Cherenkov telescope array, of a very high energy gamma-ray signal from the unidentified gamma-ray source HESS J1614-518, which was discovered in the H.E.S.S. Galactic plane survey. Diffuse gamma-ray emission was detected above 760 GeV at the 8.9 sigma level during an effective exposure of 54 hr from 2008 May to August. The spectrum can be represented by a power-law: 8.2+-2.2_{stat}+-2.5_{sys}x10^{-12}x (E/1TeV)^{-Gamma} cm^{-2} s^{-1} TeV^{-1} with a photon index Gamma of 2.4+-0.3_{stat}+-0.2_{sys}, which is compatible with that of the H.E.S.S. observations. By combining our result with multi-wavelength data, we discuss the possible counterparts for HESS J1614-518 and consider radiation mechanisms based on hadronic and leptonic processes for a supernova remnant, stellar winds from massive stars, and a pulsar wind nebula. Although a leptonic origin from a pulsar wind nebula driven by an unknown pulsar remains possible, hadronic-origin emission from an unknown supernova remnant is preferred.
Observation of gamma-rays greater than 10 TeV from Markarian 421
K. Okumura,A. Asahara,G. V. Bicknell,P. G. Edwards,R. Enomoto,S. Gunji,S. Hara,T. Hara,S. Hayashi,C. Itoh,S. Kabuki,F. Kajino,H. Katagiri,J. Kataoka,A. Kawachi,T. Kifune,H. Kubo,J. Kushida,S. Maeda,A. Maeshiro,Y. Matsubara,Y. Mizumoto,M. Mori,M. Moriya,H. Muraishi,Y. Muraki,T. Naito,T. Nakase,K. Nishijima,M. Ohishi,J. R. Patterson,K. Sakurazawa,R. Suzuki,D. L. Swaby,K. Takano,T. Takano,T. Tanimori,F. Tokanai,K. Tsuchiya,H. Tsunoo,K. Uruma,A. Watanabe,S. Yanagita,T. Yoshida,T. Yoshikoshi
Physics , 2002, DOI: 10.1086/344831
Abstract: We have observed Markarian 421 in January and March 2001 with the CANGAROO-II imaging Cherenkov telescope during an extraordinarily high state at TeV energies. From 14 hours observations at very large zenith angles, $\sim70^\circ$, a signal of 298 $\pm$ 52 gamma-ray--like events (5.7 $\sigma$) was detected at $E>10$ TeV, where a higher sensitivity is achieved than those of usual observations near the zenith, owing to a greatly increased collecting area. Under the assumption of an intrinsic power-law spectrum, we derived a differential energy spectrum $dN/dE = (3.3 \pm 0.9_{stat.} \pm 0.3_{syst.})\times10^{-13} (E/10 {Te V})^{-(4.0 ^{+0.9}_{-0.6}_{stat.} \pm 0.3_{syst.})}$ ph./cm$^2$/sec/TeV, which is steeper than those previously measured around 1 TeV, and supports the evidence for a cutoff in the spectrum of Markarian 421. However, the 4 $\sigma$ excess at energies greater than 20 TeV in our data favors a cutoff energy of $\sim$8 TeV, at the upper end of the range previously reported from measurements at TeV energies.
The CANGAROO-III Project: Status report
M. Mori,A. Asahara,G. V. Bicknell,R. W. Clay,P. G. Edwards,R. Enomoto,S. Gunji,S. Hara,T. Hara,S. Hayashi,C. Itoh,S. Kabuki,F. Kajino,H. Katagiri,A. Kawachi,T. Kifune,H. Kubo,J. Kushida,S. Maeda,A. Maeshiro,Y. Matsubara,Y. Mizumoto,H. Muraishi,Y. Muraki,T. Naito,T. Nakase,K. Nishijima,M. Ohishi,K. Okumura,J. R. Patterson,R. J. Protheroe,K. Sakurazawa,R. Suzuki,D. L. Swaby,T. Tanimori,F. Tokanai,K. Tsuchiya,H. Tsunoo,K. Uruma,A. Watanabe,S. Yanagita,T. Yoshida,T. Yoshikoshi
Physics , 2001,
Abstract: We report on the status of the construction of an array of four 10 m atmospheric Cherenkov telescopes for gamma-ray astronomy, near Woomera, in South Australia -- the CANGAROO-III project. The first telescope of this array is the upgraded version of the CANGAROO-II 7 m telescope and has been in operation since March 2000. The second telescope, an improved version of the first, is being constructed for installation in late 2001. Stereoscopic observation of sub TeV gamma-rays with the two 10 m telescopes will begin in 2002 and the full array will be operational in 2004.
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