The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard ...The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle.The WCDA-1 achieves a sensitivity of 65 mCU per year,with a statistical threshold of 5 cr.To accomplish this,a 97.7%cosmic-ray background rejection rate around 1 TeV and 99.8%around 6 TeV with an ap proximate photon acceptance of 50%is achieved after applying an algorithm to separate gamma-induced showers.The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45°at 1 TeV and better than 0.2°above 6 TeV,with a pointing accuracy better than 0.05°.These values all match the design specifications.The energy resolution is found to be 33%for gamma rays around 6 TeV.The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.展开更多
The Water Cherenkov Detector Array(WCDA) is a major component of the Large High Altitude Air Shower Array Observatory(LHAASO), a new generation cosmic-ray experiment with unprecedented sensitivity, currently under con...The Water Cherenkov Detector Array(WCDA) is a major component of the Large High Altitude Air Shower Array Observatory(LHAASO), a new generation cosmic-ray experiment with unprecedented sensitivity, currently under construction. WCDA is aimed at the study of TeV γ-rays. In order to evaluate the prospects of searching for TeV γ-ray sources with WCDA, we present a projection of the one-year sensitivity of WCDA to TeV γ-ray sources from TeVCat using an all-sky approach. Out of 128 TeVCat sources observable by WCDA up to a zenith angle of 45°, we estimate that 42 would be detectable in one year of observations at a median energy of 1 TeV. Most of them are Galactic sources, and the extragalactic sources are Active Galactic Nuclei(AGN).展开更多
基金Supported by the following grants:the National Key R&D program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203)the National Natural Science Foundation of China(12022502,11905227,U1931112,11635011,11761141001,Y811A35,11675187,U1831208,U1931111)in Thailand by RTA6280002 from Thailand Science Research and Innovation。
文摘The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April 2019.The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle.The WCDA-1 achieves a sensitivity of 65 mCU per year,with a statistical threshold of 5 cr.To accomplish this,a 97.7%cosmic-ray background rejection rate around 1 TeV and 99.8%around 6 TeV with an ap proximate photon acceptance of 50%is achieved after applying an algorithm to separate gamma-induced showers.The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45°at 1 TeV and better than 0.2°above 6 TeV,with a pointing accuracy better than 0.05°.These values all match the design specifications.The energy resolution is found to be 33%for gamma rays around 6 TeV.The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.
基金Supported by National Natural Science Foundation of China(11761141001,11635011,11873005)The LHAASO project is supported by the National Key R&D Program of China(2018YFA0404200),the Chinese Academy of Sciences,the Key Laboratory of Particle Astrophysics,IHEP,CAS。
文摘The Water Cherenkov Detector Array(WCDA) is a major component of the Large High Altitude Air Shower Array Observatory(LHAASO), a new generation cosmic-ray experiment with unprecedented sensitivity, currently under construction. WCDA is aimed at the study of TeV γ-rays. In order to evaluate the prospects of searching for TeV γ-ray sources with WCDA, we present a projection of the one-year sensitivity of WCDA to TeV γ-ray sources from TeVCat using an all-sky approach. Out of 128 TeVCat sources observable by WCDA up to a zenith angle of 45°, we estimate that 42 would be detectable in one year of observations at a median energy of 1 TeV. Most of them are Galactic sources, and the extragalactic sources are Active Galactic Nuclei(AGN).
