The Experts below are selected from a list of 21177 Experts worldwide ranked by ideXlab platform
Masahiro Amenomori - One of the best experts on this subject based on the ideXlab platform.
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first detection of photons with energy beyond 100 tev from an astrophysical source
Physical Review Letters, 2019Co-Authors: Masahiro Amenomori, L K Ding, D Chen, Xu Chen, S W Cui, T L Chen, W Y Chen, Yongjun Bao, Y B Chen, J FangAbstract:We report on the highest energy photons from the Crab Nebula observed by the Tibet Air Shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an Air Shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
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on the solar cycle variation of the solar diurnal anisotropy of multi tev cosmic ray intensity observed with the tibet Air Shower array
EPJ Web of Conferences, 2019Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, Z Y Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Q B GouAbstract:We analyze the temporal variation of the solar diurnal anisotropy of the multi-TeV cosmic-ray intensity observed with the Tibet Air Shower array from 2000 to 2009, covering the maximum and minimum of the 23rd solar cycle. We comfirm that a remarkable additional anisotropy component is superposed on the Compton-Getting anisotropy at 4.0 TeV, while its amplitude decreases at higher energy regions. In constrast to the additional anisotropy reported by the Matsushiro experiment at 0.6 TeV, we find the residual component measured by Tibet at multi-TeV energies is consistent with being stable, with a fAirly constant amplitude of 0.041% ± 0.003% and a phase at around 07.17 ± 00.16 local solar time at 4.0 TeV. This suggests the additional anisotropy observed by the Tibet experiment could result from mechanisms unrelated to solar activities.
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northern sky galactic cosmic ray anisotropy between 10 and 1000 tev with the tibet Air Shower array
The Astrophysical Journal, 2017Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Zhenyong Feng, Q B GouAbstract:We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2σ pre-trial, 5.2σ post-trial) and a deficit (−5.8σ pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube’s results at 400 TeV. Combining the Tibet results in the northern sky with IceCube’s results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.
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test of the hadronic interaction models at around 10 tev with tibet eas core data
32nd International Cosmic Ray Conference ICRC 2011, 2011Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, W Y Chen, Danzeng Luobu, Z Y FengAbstract:A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air Shower Core array) and the Tibet Air-Shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in Air-Shower cores within several meters from the Shower axis, and Tibet-III array measures the total energy and the arrival direction of Air Showers. YAC-I is used to check hadronic interaction models currently used for Air-Shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in Air-Shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
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on temporal variations of the multi tev cosmic ray anisotropy using the tibet iii Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, C Fan, Zhenyong FengAbstract:We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fAirly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
L K Ding - One of the best experts on this subject based on the ideXlab platform.
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first detection of photons with energy beyond 100 tev from an astrophysical source
Physical Review Letters, 2019Co-Authors: Masahiro Amenomori, L K Ding, D Chen, Xu Chen, S W Cui, T L Chen, W Y Chen, Yongjun Bao, Y B Chen, J FangAbstract:We report on the highest energy photons from the Crab Nebula observed by the Tibet Air Shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an Air Shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
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on the solar cycle variation of the solar diurnal anisotropy of multi tev cosmic ray intensity observed with the tibet Air Shower array
EPJ Web of Conferences, 2019Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, Z Y Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Q B GouAbstract:We analyze the temporal variation of the solar diurnal anisotropy of the multi-TeV cosmic-ray intensity observed with the Tibet Air Shower array from 2000 to 2009, covering the maximum and minimum of the 23rd solar cycle. We comfirm that a remarkable additional anisotropy component is superposed on the Compton-Getting anisotropy at 4.0 TeV, while its amplitude decreases at higher energy regions. In constrast to the additional anisotropy reported by the Matsushiro experiment at 0.6 TeV, we find the residual component measured by Tibet at multi-TeV energies is consistent with being stable, with a fAirly constant amplitude of 0.041% ± 0.003% and a phase at around 07.17 ± 00.16 local solar time at 4.0 TeV. This suggests the additional anisotropy observed by the Tibet experiment could result from mechanisms unrelated to solar activities.
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northern sky galactic cosmic ray anisotropy between 10 and 1000 tev with the tibet Air Shower array
The Astrophysical Journal, 2017Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Zhenyong Feng, Q B GouAbstract:We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2σ pre-trial, 5.2σ post-trial) and a deficit (−5.8σ pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube’s results at 400 TeV. Combining the Tibet results in the northern sky with IceCube’s results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.
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test of the hadronic interaction models at around 10 tev with tibet eas core data
32nd International Cosmic Ray Conference ICRC 2011, 2011Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, W Y Chen, Danzeng Luobu, Z Y FengAbstract:A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air Shower Core array) and the Tibet Air-Shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in Air-Shower cores within several meters from the Shower axis, and Tibet-III array measures the total energy and the arrival direction of Air Showers. YAC-I is used to check hadronic interaction models currently used for Air-Shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in Air-Shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
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on temporal variations of the multi tev cosmic ray anisotropy using the tibet iii Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, C Fan, Zhenyong FengAbstract:We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fAirly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
X H Ding - One of the best experts on this subject based on the ideXlab platform.
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test of the hadronic interaction models at around 10 tev with tibet eas core data
32nd International Cosmic Ray Conference ICRC 2011, 2011Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, W Y Chen, Danzeng Luobu, Z Y FengAbstract:A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air Shower Core array) and the Tibet Air-Shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in Air-Shower cores within several meters from the Shower axis, and Tibet-III array measures the total energy and the arrival direction of Air Showers. YAC-I is used to check hadronic interaction models currently used for Air-Shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in Air-Shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
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on temporal variations of the multi tev cosmic ray anisotropy using the tibet iii Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, C Fan, Zhenyong FengAbstract:We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fAirly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
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observation of tev gamma rays from the fermi bright galactic sources with the tibet Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, C Feng, Shuwang Cui, C Fan, Zhenyong FengAbstract:Using the Tibet-III Air Shower array, we search for TeV γ-rays from 27 potential Galactic sources in the early list of bright sources obtained by the Fermi Large Area Telescope at energies above 100 MeV. Among them, we observe seven sources instead of the expected 0.61 sources at a significance of 2σ or more excess. The chance probability from Poisson statistics would be estimated to be 3.8 × 10–6. If the excess distribution observed by the Tibet-III array has a density gradient toward the Galactic plane, the expected number of sources may be enhanced in chance association. Then, the chance probability rises slightly, to 1.2 × 10–5, based on a simple Monte Carlo simulation. These low chance probabilities clearly show that the Fermi bright Galactic sources have statistically significant correlations with TeV γ-ray excesses. We also find that all seven sources are associated with pulsars, and six of them are coincident with sources detected by the Milagro experiment at a significance of 3σ or more at the representative energy of 35 TeV. The significance maps observed by the Tibet-III Air Shower array around the Fermi sources, which are coincident with the Milagro ≥3σ sources, are consistent with the Milagro observations. This is the first result of the northern sky survey of the Fermi bright Galactic sources in the TeV region.
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multi tev gamma ray observation from the crab nebula using the tibet iii Air Shower array finely tuned by the cosmic ray moon s shadow
The Astrophysical Journal, 2009Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, C Feng, Zhenyong Feng, Shuwang Cui, C Fan, X Y GaoAbstract:The Tibet-III Air Shower array, consisting of 533 scintillation detectors, has been operating successfully at Yangbajing in Tibet, China since 1999. Using the data set collected by this array from 1999 November through 2005 November, we obtained the energy spectrum of γ-rays from the Crab Nebula, expressed by a power law as (dJ/dE) = (2.09 ± 0.32) × 10–12(E/3 TeV)–2.96±0.14 cm–2 s–1 TeV–1 in the energy range of 1.7-40 TeV. This result is consistent with other independent γ-ray observations by imaging Air Cherenkov telescopes. In this paper, we carefully checked and tuned the performance of the Tibet-III array using data on the Moon's shadow in comparison with a detailed Monte Carlo (MC) simulation. The shadow is shifted to the west of the Moon's apparent position as an effect of the geomagnetic field, although the extent of this displacement depends on the primary energy of positively charged cosmic rays. This finding enables us to estimate the systematic error in determining the primary energy from its Shower size. This error is estimated to be less than ±12% in our experiment. This energy scale estimation is the first attempt among cosmic ray experiments at ground level. The systematic pointing error is also estimated to be smaller than 0011. The deficit rate and the position of the Moon's shadow are shown to be very stable within a statistical error of ±6% year by year. This guarantees the long-term stability of pointlike source observation with the Tibet-III array. These systematic errors are adequately taken into account in our study of the Crab Nebula.
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the all particle spectrum of primary cosmic rays in the wide energy range from 1014 to 1017 ev observed with the tibet iii Air Shower array
The Astrophysical Journal, 2008Co-Authors: Masahiro Amenomori, Cunfeng Feng, Q X Geng, L K Ding, X H Ding, Zhaoyang Feng, Z Y Feng, Xiaojun Bi, D Chen, Haoning HeAbstract:We present an updated all-particle energy spectrum of primary cosmic rays in a wide range from 10 14 to 10 17 eVusing 5:5 ; 10 7 events collected from 2000 November through 2004 October by the Tibet-III Air-Shower array located 4300 m abovesealevel(anatmosphericdepthof 606gcm � 2 ).Thesizespectrumexhibitsasharpkneeatacorrespondingprimary energy around 4 PeV. This work uses increased statistics and new simulation calculations for the analysis. We discuss our extensive Monte Carlo calculations and the model dependencies involved in thefinal result, assuming interaction models QGSJET01c and SIBYLL2.1, and heavy dominant (HD) and proton dominant (PD) primary composition models. Pure protonandpureironprimarymodelsarealsoexaminedasextremecases.A detector simulationwasalsoperformedtoimproveouraccuracyindeterminingthesizeof theAirShowersandtheenergyof theprimaryparticle.Weconfirmedthatthe all-particle energy spectra obtained under various plausible model parameters are not significantly different from each other, which was the expected result given the characteristics of the experiment at high altitude, where the Air Showers of the primary energy around the knee reach near-maximum development, with their features dominated by electromagnetic components,leadingtoaweakdependenceontheinteractionmodel or theprimarymass.Thisisthehighest statistical and the best systematics-controlled measurement covering the widest energy range around the knee energy region.
D Chen - One of the best experts on this subject based on the ideXlab platform.
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first detection of photons with energy beyond 100 tev from an astrophysical source
Physical Review Letters, 2019Co-Authors: Masahiro Amenomori, L K Ding, D Chen, Xu Chen, S W Cui, T L Chen, W Y Chen, Yongjun Bao, Y B Chen, J FangAbstract:We report on the highest energy photons from the Crab Nebula observed by the Tibet Air Shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an Air Shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
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on the solar cycle variation of the solar diurnal anisotropy of multi tev cosmic ray intensity observed with the tibet Air Shower array
EPJ Web of Conferences, 2019Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, Z Y Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Q B GouAbstract:We analyze the temporal variation of the solar diurnal anisotropy of the multi-TeV cosmic-ray intensity observed with the Tibet Air Shower array from 2000 to 2009, covering the maximum and minimum of the 23rd solar cycle. We comfirm that a remarkable additional anisotropy component is superposed on the Compton-Getting anisotropy at 4.0 TeV, while its amplitude decreases at higher energy regions. In constrast to the additional anisotropy reported by the Matsushiro experiment at 0.6 TeV, we find the residual component measured by Tibet at multi-TeV energies is consistent with being stable, with a fAirly constant amplitude of 0.041% ± 0.003% and a phase at around 07.17 ± 00.16 local solar time at 4.0 TeV. This suggests the additional anisotropy observed by the Tibet experiment could result from mechanisms unrelated to solar activities.
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northern sky galactic cosmic ray anisotropy between 10 and 1000 tev with the tibet Air Shower array
The Astrophysical Journal, 2017Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Zhenyong Feng, Q B GouAbstract:We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2σ pre-trial, 5.2σ post-trial) and a deficit (−5.8σ pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube’s results at 400 TeV. Combining the Tibet results in the northern sky with IceCube’s results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.
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test of the hadronic interaction models at around 10 tev with tibet eas core data
32nd International Cosmic Ray Conference ICRC 2011, 2011Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, W Y Chen, Danzeng Luobu, Z Y FengAbstract:A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air Shower Core array) and the Tibet Air-Shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in Air-Shower cores within several meters from the Shower axis, and Tibet-III array measures the total energy and the arrival direction of Air Showers. YAC-I is used to check hadronic interaction models currently used for Air-Shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in Air-Shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
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on temporal variations of the multi tev cosmic ray anisotropy using the tibet iii Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, C Fan, Zhenyong FengAbstract:We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fAirly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
S W Cui - One of the best experts on this subject based on the ideXlab platform.
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first detection of photons with energy beyond 100 tev from an astrophysical source
Physical Review Letters, 2019Co-Authors: Masahiro Amenomori, L K Ding, D Chen, Xu Chen, S W Cui, T L Chen, W Y Chen, Yongjun Bao, Y B Chen, J FangAbstract:We report on the highest energy photons from the Crab Nebula observed by the Tibet Air Shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an Air Shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
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on the solar cycle variation of the solar diurnal anisotropy of multi tev cosmic ray intensity observed with the tibet Air Shower array
EPJ Web of Conferences, 2019Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, Z Y Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Q B GouAbstract:We analyze the temporal variation of the solar diurnal anisotropy of the multi-TeV cosmic-ray intensity observed with the Tibet Air Shower array from 2000 to 2009, covering the maximum and minimum of the 23rd solar cycle. We comfirm that a remarkable additional anisotropy component is superposed on the Compton-Getting anisotropy at 4.0 TeV, while its amplitude decreases at higher energy regions. In constrast to the additional anisotropy reported by the Matsushiro experiment at 0.6 TeV, we find the residual component measured by Tibet at multi-TeV energies is consistent with being stable, with a fAirly constant amplitude of 0.041% ± 0.003% and a phase at around 07.17 ± 00.16 local solar time at 4.0 TeV. This suggests the additional anisotropy observed by the Tibet experiment could result from mechanisms unrelated to solar activities.
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northern sky galactic cosmic ray anisotropy between 10 and 1000 tev with the tibet Air Shower array
The Astrophysical Journal, 2017Co-Authors: Masahiro Amenomori, L K Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, T L Chen, W Y Chen, Zhenyong Feng, Q B GouAbstract:We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2σ pre-trial, 5.2σ post-trial) and a deficit (−5.8σ pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube’s results at 400 TeV. Combining the Tibet results in the northern sky with IceCube’s results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.
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test of the hadronic interaction models at around 10 tev with tibet eas core data
32nd International Cosmic Ray Conference ICRC 2011, 2011Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, W Y Chen, Danzeng Luobu, Z Y FengAbstract:A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air Shower Core array) and the Tibet Air-Shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in Air-Shower cores within several meters from the Shower axis, and Tibet-III array measures the total energy and the arrival direction of Air Showers. YAC-I is used to check hadronic interaction models currently used for Air-Shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in Air-Shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
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on temporal variations of the multi tev cosmic ray anisotropy using the tibet iii Air Shower array
The Astrophysical Journal, 2010Co-Authors: Masahiro Amenomori, L K Ding, X H Ding, Zhaoyang Feng, D Chen, S W Cui, C Feng, C Fan, Zhenyong FengAbstract:We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fAirly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
