研究者業績
基本情報
受賞
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2022年2月
論文
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UHECR 2012 - INTERNATIONAL SYMPOSIUM ON FUTURE DIRECTIONS IN UHECR PHYSICS 53 2013年 査読有りThe Large Hadron Collider forward (= LHCf) experiment has successfully finished the first phase of data taking at LHC root s = 0.9 and 7 TeV proton- proton collisions in 2010. As current status, we concentrate on analyzing the obtained data. As the first result, the energy spectra of photon measured by LHCf during = 7 TeV p-p collision has been published recently. Also the study of the upgraded version of LHCf detector for future = 14 TeV run scenario is developed with the GSO scintillator. Another possible plan of p-A(nuclear) collision in LHC is also studied. In this paper, as the current status of the experiment, analyses, and works for foreseen detector upgrade are summarized.
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UHECR 2012 - INTERNATIONAL SYMPOSIUM ON FUTURE DIRECTIONS IN UHECR PHYSICS 53 2013年 査読有りLHCf is planning to measure very forward particle emission in the LHC p-Pb collisions foreseen at the end of 2012. The measurement is expected to constrain the nuclear effect in the forward particle emission relevant to the CR-Air interaction. Model discrimination power of this measurement is presented together with some detail in technical feasibility.
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PHYSICAL REVIEW D 86(9) 2012年11月The inclusive production rate of neutral pions in the rapidity range greater than y = 8.9 has been measured by the Large Hadron Collider forward (LHCf) experiment during root s = 7 TeV proton-proton collision operation in early 2010. This paper presents the transverse momentum spectra of the neutral pions. The spectra from two independent LHCf detectors are consistent with each other and serve as a cross-check of the data. The transverse momentum spectra are also compared with the predictions of several hadronic interaction models that are often used for high-energy particle physics and for modeling ultrahigh-energy cosmic ray showers.
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PHYSICS LETTERS B 715(4-5) 298-303 2012年9月The inclusive photon energy spectra measured by the Large Hadron Collider forward (LHCf) experiment in the very forward region of LHC proton-proton collisions at root s = 900 GeV are reported. The results from the analysis of 0.30 nb(-1) of data collected in May 2010 in the two pseudorapidity regions of eta > 10.15 and 8.77 < eta <9.46 are compared with the predictions of the hadronic interaction models DPMJET 3.04, EPOS 1.99, PYTHIA 8.145, QGSJET II-03 and SIBYLL 2.1, which are widely used in ultra-high energy cosmic ray experiments. EPOS 1.99 and SIBYLL 2.1 show a reasonable agreement with the spectral shape of the experimental data, whereas they predict lower cross-sections than the data. The other models. DPMJET 3.04, QGSJET II-03 and PYTHIA 8.145, are in good agreement with the data below 300 GeV but predict harder energy spectra than the data above 300 GeV. The results of these comparisons exhibited features similar to those for the previously reported data for root s = 7 TeV collisions. (c) 2012 Elsevier B.V. All rights reserved.
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AIP Conference Proceedings 1505 578-581 2012年The Perseus cluster of galaxies is a nearby cool-core cluster with an intra-clustermedium (ICM) characterized by very high central densities. The observation of the Perseus cluster with the MAGIC telescopes, during 85 h from 2009 to 2011, resulted in the discovery of 2 point-like sources at very high energy (>100 GeV, VHE) coinciding with the central radio galaxy NGC1275 and the radio galaxy IC310. The γ-ray properties of these 2 sources are presented, taking into account contemporaneous Fermi-LAT as well as multi-wavelength data. Flux variability and spectral energy distribution shapes indicate that the VHE γ-rays do not originate from large-scale interaction of the radio galaxies with ICM but more likely from the active nuclei of these two galaxies. They could be both misaligned version of BL Lac objects, the most common TeV AGN. Our results provide vital clues to understand emission mechanisms of such misaligned objects, and how they may be related to the beamed emission seen in BL Lacs. No evidence of large-scale VHE γ-ray emission from hadronic cosmic ray (CR) interactions with the ICM has been found. The flux upper limit above 1 TeV reaches the signal expected by some theoretical models, constraining the cluster CR physics. In the framework of the hadronicmodel of the radiomini-halos, this limit implies aminimal magnetic field ranging from 4-9μG for the central cluster region. © 2012 American Institute of Physics.
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PHYSICS LETTERS B 703(2) 128-134 2011年9月In early 2010. the Large Hadron Collider forward (LHCf) experiment measured very forward neutral particle spectra in LHC proton-proton collisions. From a limited data set taken under the best beam conditions (low beam-gas background and low occurrence of pile-up events), the single photon spectra at root s = 7 TeV and pseudo-rapidity (eta) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this Letter. The spectra from two independent LHCf detectors are consistent with one another and serve as a cross check of the data. The photon spectra are also compared with the predictions of several hadron interaction models that are used extensively for modeling ultra-high energy cosmic-ray showers. Despite conservative estimates for the systematic errors, none of the models agree perfectly with the measurements. A notable difference is found between the data and the DPMJET 3.04 and PYTHIA 8.145 hadron interaction models above 2 TeV where the models predict higher photon yield than the data. The QGSJET II-03 model predicts overall lower photon yield than the data, especially above 2 TeV in the rapidity range 8.81 < eta < 8.99. (C) 2011 CERN for the benefit of the LHCf collaboration
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ASTROPHYSICAL JOURNAL LETTERS 736(1) 2011年7月We report the first observational search for tau neutrinos (nu(tau)) from gamma-ray bursts (GRBs) using one of the Ashra light collectors. The Earth-skimming nu(tau) technique of imaging Cherenkov tau showers was applied as a detection method. We set stringent upper limits on the nu(tau) fluence in PeV-EeV region for 3780 s (between 2.83 and 1.78 hr before) and another 3780 s (between 21.2 and 22.2 hr after) surrounding GRB081203A triggered by the Swift satellite. This first search for PeV-EeV nu(tau) complements other experiments in energy range and methodology, and suggests the prologue of "multi-particle astronomy" with a precise determination of time and location.
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Astrophysical Journal Letters 730(1) 2011年3月20日Very high energy (VHE) γ-ray emission from the flat spectrum radio quasar (FSRQ) PKS1222+21 (4C21.35, z = 0.432) was detected with the MAGIC Cherenkov telescopes during a short observation (0.5hr) performed on 2010 June 17. The MAGIC detection coincides with high-energy MeV/GeV γ-ray activity measured by the Large Area Telescope (LAT) on board the Fermi satellite. The VHE spectrum measured by MAGIC extends from about 70GeV up to at least 400GeV and can be well described by a power-law dN/dE E -Γ with a photon index Γ = 3.75 0.27stat 0.2syst. The averaged integral flux above 100GeV is (4.6 0.5) × 10-10 cm-2 s-1 (1 Crab Nebula flux). The VHE flux measured by MAGIC varies significantly within the 30 minute exposure implying a flux doubling time of about 10 minutes. The VHE and MeV/GeV spectra, corrected for the absorption by the extragalactic background light (EBL), can be described by a single power law with photon index 2.72 0.34 between 3GeV and 400GeV, and is consistent with emission belonging to a single component in the jet. The absence of a spectral cutoff constrains the γ-ray emission region to lie outside the broad-line region, which would otherwise absorb the VHE γ-rays. Together with the detected fast variability, this challenges present emission models from jets in FSRQs. Moreover, the combined Fermi/LAT and MAGIC spectral data yield constraints on the density of the EBL in the UV-optical to near-infrared range that are compatible with recent models. © 2011. The American Astronomical Society. All rights reserved.
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NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS 212-13 270-276 2011年3月LHCf is an experiment dedicated to the measurement of neutral particles<br /> emitted in the very forward region of LHC collisions. The physics goal is to<br /> provide data for calibrating hadron interaction models that are used in the<br /> study of Extremely High-Energy Cosmic-Rays. The LHCf experiment acquired data<br /> from April to July 2010 during commissioning time of LHC operations at low<br /> luminosity. Production spectra of photons and neutrons emitted in the very<br /> forward region ($\eta>$ 8.4) have been obtained. In this paper preliminary<br /> results of the photon spectra taken at $\sqrt{s}$ = 7TeV are reported.
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Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 5 63-66 2011年 査読有りThe Large Hadron Collider forward (LHCf) experiment measured the energy spectra of the neutral particles from the LHC proton-proton collisions into the very forward region. The analysis results of single-photon spectra at vs=7 TeV taken in May 15, 2010 are presented in this paper. The spectra from two independent LHCf detectors are consistent with one another. The photon spectra are also compared with the predictions of several hadronic interaction models that are employed in many experiments aiming for measuring high-energy cosmic-ray showers.
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Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 5 27-30 2011年 査読有りThe performance of the LHCf detectors was studied at the CERN SPS beam line in 2007 using 50-200GeV electron, 150-350GeV proton and 150GeV muon beams. Full Monte Carlo calculations of the SPS beam test were performed by using the Cosmos and Epics MC code and very good agreements were obtained between data and MC. The detector performance such as the radiation damage were monitored during the 2009-2010 operation by using the π0 mass. In this paper, we will present performance of the LHCf detectors studied at the SPS beam and the LHC condition.
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Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 5 55-58 2011年 査読有りGd2SiO5 (GSO) scintillator has very excellent radiation resistance with fast decay time and large amount of light yield. The radiation hardness of GSO was examined by using Carbon ion beams at Heavy Ion Medical Accelerator in Chiba (HIMAC). Through two nights of irradiation a GSO scintillator was received 7 × 105 Gy of total dose and no decrease of light yield was observed. On the other hand an increase of light yield by 25% was observed. The increase is marginally proportional to the total dose at the rate of 0.025%/Gy and it is saturated at 1 kGy. Recovery to the initial light yield was also observed during the day between two nights. The time scale of recovery is about 15,000 seconds. In case of the LHCf experiment, very forward region (pseudo-rapidity > 8.4) experiment at the LHC, the irradiation rate is expected to about 100Gy for 10nb-1 of data taking at vs = 14TeV proton-proton collisions. Expected increase of less than a few % will not be a big problem for the LHCf experiment.
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AIP Conference Proceedings 1367 58-63 2011年 査読有りWe give a brief description of the purpose of the LHCf experiment, detectors and their performance, and what has been done in the first year experiment. A short summary of results at √s=900 GeV is given although the energy is not an "intrinsic" LHC energy. Since detailed results at √s=7 TeV will appear soon elsewhere, here we limit ourselves to giving also a brief account of what will come in that paper. © 2011 American Institute of Physics.
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Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 5 35-38 2011年 査読有りLHCf is a collider experiment dedicated to obtaining information relevant to ultra-high-energy cosmic-ray physics. One of the two LHCf detectors has position-sensitive silicon microstrip layers that are read out with front end electronics. These electronics saturate for high energy photon showers because of the limited dynamic range of the preamplifier. Consequently we are planning an upgrade of the processing circuits in anticipation of LHC operation at increased collision energy, and we are developing an analysis method to correct for the saturation effect. An overview of these data analysis methods will be given in this paper.
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日本物理学会講演概要集 66 105-105 2011年 査読有り
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日本物理学会講演概要集 63 82-82 2008年 査読有り
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日本物理学会講演概要集 63 82-82 2008年 査読有り
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日本物理学会講演概要集 62 92-92 2007年 査読有り
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日本物理学会講演概要集 62 92-92 2007年 査読有り
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日本物理学会講演概要集 62 98-98 2007年 査読有り
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日本物理学会講演概要集 61 94-94 2006年 査読有り
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日本物理学会講演概要集 61 94-94 2006年 査読有り
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日本物理学会講演概要集 61 95-95 2006年 査読有り
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日本物理学会講演概要集 61 59-59 2006年 査読有り
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日本物理学会講演概要集 60 94-94 2005年 査読有り
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日本物理学会講演概要集 60 95-95 2005年 査読有り
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日本物理学会講演概要集 60 26-26 2005年 査読有り
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日本物理学会講演概要集 60 26-26 2005年 査読有り
MISC
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Proceedings of Science 395 787 2022年3月 査読有り
講演・口頭発表等
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HIGH ENERGY GAMMA-RAY ASTRONOMY 2017年 AMER INST PHYSICSThe MAGIC telescopes are strongly involved in several multimessenger programs. One of them are follow-up observations of astrophysical neutrino events, to search for hadronic gamma-ray emission from the neutrino direction and identify potential neutrino sources. In 2013 the IceCube collaboration reported the first detection of astrophysical neutrinos and up to now 55 events, which interact inside the IceCube detector active volume, dubbed High Energy Starting Events (HESE), have been reported. These include 13 track-like events, caused usually by muon neutrino charge current interactions. The track-like events ( as opposed to cascade-like neutral current interactions) are characterised by a very good angular resolution of < 1 deg, which facilitates follow-up observations and potential source identification. The MAGIC telescopes performed follow-up observations of 4 HESE track-like events from the Northern hemisphere: HESE-37, HESE-38, HET (ATel #7856) and the GCN HESE alert from 27/04/2016 (GCN #19363). No signal was detected. Here we present the results of those observations and discuss the implications for the constraints on the density of the astrophysical neutrino sources.
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日本物理学会講演概要集 2014年8月22日 一般社団法人日本物理学会
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日本物理学会講演概要集 2014年8月22日 一般社団法人日本物理学会
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 2023年4月 - 2028年3月
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日本学術振興会 科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B)) 2020年10月 - 2025年3月
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日本学術振興会 科学研究費助成事業 研究活動スタート支援 2019年4月 - 2020年3月
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日本学術振興会 科学研究費助成事業 特別研究員奨励費 2006年 - 2008年