Dependence of the GRAPES-3 EAS particle density and trigger rate on atmospheric pressure and temperature

Zuberi, M.; Ahmad, S.; Arunbabu, K. P.; Chandra, Anuj; Dugad, S.R.; Gupta, Sunil; Hariharan, B.; Hayashi, Y.; Jagadeesan, P.; Jhansi, V.B.; Kawakami, S.; Kojima, Hiroshi; Mohanty, P. K.; Morris, S. D.; Nayak, P.K.; Oshima, A.; Rao, Balkrishna C.; Reddy, L.V.; Shibata, Sho

doi:10.22323/1.301.0302

Cited by 4 publications

(2 citation statements)

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“…We set the parameter nside = 64, which divides the sky into 45,192 pixels of equal area of about (0°.92) 2 in α and δ. The EAS trigger rate exhibits variations caused by atmospheric pressure and temperature on a daily timescale at the level of 3%-5% (Zuberi et al 2017). Further, there are gaps in the data produced due to either scheduled maintenance activity or failure of electronics or the data acquisition system.…”

Section: Analysis and Resultsmentioning

confidence: 99%

Small-scale Cosmic-Ray Anisotropy Observed by the GRAPES-3 Experiment at TeV Energies

Chakraborty,

Ahmad,

Chandra

et al. 2024

ApJ

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GRAPES-3 is a mid-altitude (2200 m) and near-equatorial (11.°4N) air shower array, overlapping in its field of view for cosmic-ray observations with experiments that are located in the Northern and Southern Hemispheres. We analyze a sample of 3.7 × 109 cosmic-ray events collected by the GRAPES-3 experiment between 2013 January 1 and 2016 December 31 with a median energy of ∼16 TeV for study of small-scale (<60°) angular-scale anisotropies. We observed two structures, labeled A and B, that deviate from the expected isotropic distribution of cosmic rays in a statistically significant manner. Structure A spans 50°–80° in R.A. and from −15° to 30° in decl. The relative excess observed in structure A is at the level of (6.5 ± 1.3) × 10−4 with a statistical significance of 6.8 standard deviations. Structure B is observed in the R.A. range 110°–140° and at decl. from −10° to 30°. The relative excess observed in this region is at the level of (4.9 ± 1.4) × 10−4 with a statistical significance of 4.7 standard deviations. These structures are consistent with those reported by Milagro, ARGO-YBJ, and HAWC. These observations could provide a better understanding of the sources of cosmic rays, their propagation, and the magnetic structures in our Galaxy.

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Section: Analysis and Resultsmentioning

confidence: 99%

Small-scale Cosmic-Ray Anisotropy Observed by the GRAPES-3 Experiment at TeV Energies

Chakraborty,

Ahmad,

Chandra

et al. 2024

ApJ

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“…On the other hand, environmental changes can alter the performance of the detectors, which should be taken into consideration in the data analysis. Some of these effects have been reported by various groups, including ARGO-YBJ [2], Pierre Auger [3], and GRAPES-3 [4]. This paper will primarily focus on analyzing the influence of temperature, air pressure, and precipitation on the trigger rate of LHAASO-KM2A.…”

Section: Introductionmentioning

confidence: 97%

Effects of environmental factors on the LHAASO-ED array

Zhang,

Fu,

Qiao

et al. 2023

Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)

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KM2A is a sub-array of the Large High Altitude Air Shower Observatory (LHAASO) which comprising 5195 electromagnetic detectors (EDs) and 1188 muon detectors (MDs). The array is affected by various environmental factors, such as temperature, atmospheric pressure, and precipitation, particularly for the EDs which are installed in an open-air configuration. In this study, we analyse and compare the KM2A data of the full array with meteorological records to investigate the variations in the trigger rate array. The temperature and pressure coefficients are found to be stable over a year and half. After applying temperature and atmospheric pressure corrections, sudden changes in trigger related to atmospheric electric fields during thunderstorms are examined.

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