2021/01/10 by LHAASO collaboration, LHAASO Collaboration · 2 citations
Earth and Planetary Sciences · #FOS: Physical sciences #Geological and Geophysical Studies #Geophysics and Gravity Measurements #High Energy Physics - Experiment (hep-ex) #Instrumentation and Detectors (physics.ins-det) #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Oceanographic and Atmospheric Processes
paper · pdf · doi:10.48550/arxiv.2101.03508
openalex publication_date 2021/01/10 · openalex created_date 2022/07/25 · openalex updated_date 2026/08/01
The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April, 2019. The first 10 months of data have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves the sensitivity of 65 mCU per year with a statistical threshold of 5 σ. In order to do so, 97.7% cosmic ray background rejection rate around 1 TeV and 99.8% around 6 TeV with an approximately photon acceptance about 50% by using the compactness of the shower footprints to be greater than 10 as the discriminator between gamma induced showers and the cosmic ray backgrounds. The angular resolution is measured using the Crab Nebula as a point source about 0.45^∘ at 1 TeV and better than 0.2^∘ above 6 TeV with the pointing accuracy better than 0.05^∘. They are all matching the design specifications. The energy resolution is found 33% for gamma rays around 6 TeV. The spectral energy distribution of the Crab Nebula in the range from 500 GeV and 15.8 TeV is measured and in agreement with results of other TeV gamma ray observatories.