Meteorological effects on the counting rates with KM2A in scaler mode

LHAASO Collaboration

doi:10.22323/1.501.0280

Meteorological effects on the counting rates with KM2A in scaler mode

LHAASO Collaboration

Institute of High Energy Physics, Chinese Academy of Sciences
University of Chinese Academy of Sciences
TIANFU Cosmic Ray Research Center
University of Science and Technology of China
Yerevan State University
Max-Planck-Institut for Nuclear Physics
Shanghai Jiao Tong University
Guangzhou University
Institute for Nuclear Research of the Russian Academy of Sciences
Southwest Jiaotong University
State Key Laboratory of Particle Detection and Electronics
Purple Mountain Observatory Chinese Academy of Sciences
Zhejiang Lab
Shanghai Astronomical Observatory Chinese Academy of Sciences
Yunnan University
Key Laboratory of Cosmic Rays (Tibet University)
Nanjing University
Chinese University of Hong Kong
Hebei Normal University
National Astronomical Observatories Chinese Academy of Sciences
Sun Yat-Sen University
School of Physics
Mahidol University
Shandong University
CNRS/IN2P3
Tsinghua University
Zhengzhou University
Yunnan Observatories
China Center of Advanced Science and Technology World Laboratory
Sichuan University
Nanchang University
Peking University
Guangxi University
Nanjing Normal University
Moscow Institute of Physics and Technology
National Space Science Center
Huazhong University of Science and Technology

Research output: Contribution to journal › Conference article › peer-review

Abstract

The Large High Altitude Air Shower Observatory (LHAASO) consists of three sub-arrays: KM2A, WCDA and WFCTA. The KM2A contains 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). There are two common independent data acquisition systems, corresponding to the shower and scaler operation modes. In scaler mode, the KM2AED array is divided into 61 clusters. One cluster consists of 64 EDs (8 EDs × 8 EDs). For each cluster, the event rates of showers having a number of fired EDs within a time coincidence of 100 ns (particle multiplicities m) = 1, 2, 3, 4.. are recorded every 0.1 s. The scaler mode began acquiring data on June 21, 2023. In this study, we analyze the scaler mode data to study the meteorological effects on the counting rates with different multiplicities. Over long time periods, the distributions for all C_i (means the counting rate for m = i) are influenced by meteorological parameters, such as the atmospheric pressure (P) and temperature (T). The counting rates decrease with increasing P and T. The correlation coefficients between the counting rates and the meteorological parameters are studied in this work. After correcting for meteorological effects, the counting rates become stable over long time periods, with C₁ following a Gaussian distribution and C₂, C₃ and C₄ following Poisson distributions.

Original language	English
Article number	280
Journal	Proceedings of Science
Volume	501
DOIs	https://doi.org/10.22323/1.501.0280
Publication status	Published - 30 Dec 2025
Externally published	Yes
Event	39th International Cosmic Ray Conference, ICRC 2025 - Geneva, Switzerland Duration: 15 Jul 2025 → 24 Jul 2025

Keywords

Cosmic rays
LHAASO-KM2A
Meteorological effects
Scaler mode

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10.22323/1.501.0280

Cite this

@article{ab094c831a404fc8a4f60148862e7d64,

title = "Meteorological effects on the counting rates with KM2A in scaler mode",

abstract = "The Large High Altitude Air Shower Observatory (LHAASO) consists of three sub-arrays: KM2A, WCDA and WFCTA. The KM2A contains 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). There are two common independent data acquisition systems, corresponding to the shower and scaler operation modes. In scaler mode, the KM2AED array is divided into 61 clusters. One cluster consists of 64 EDs (8 EDs × 8 EDs). For each cluster, the event rates of showers having a number of fired EDs within a time coincidence of 100 ns (particle multiplicities m) = 1, 2, 3, 4.. are recorded every 0.1 s. The scaler mode began acquiring data on June 21, 2023. In this study, we analyze the scaler mode data to study the meteorological effects on the counting rates with different multiplicities. Over long time periods, the distributions for all Ci (means the counting rate for m = i) are influenced by meteorological parameters, such as the atmospheric pressure (P) and temperature (T). The counting rates decrease with increasing P and T. The correlation coefficients between the counting rates and the meteorological parameters are studied in this work. After correcting for meteorological effects, the counting rates become stable over long time periods, with C1 following a Gaussian distribution and C2, C3 and C4 following Poisson distributions.",

keywords = "Cosmic rays, LHAASO-KM2A, Meteorological effects, Scaler mode",

author = "\{LHAASO Collaboration\} and Zhen Cao and F. Aharonian and Bai, \{Y. X.\} and Bao, \{Y. W.\} and D. Bastieri and Bi, \{X. J.\} and Bi, \{Y. J.\} and W. Bian and Bukevich, \{A. V.\} and Cai, \{C. M.\} and Cao, \{W. Y.\} and Zhe Cao and J. Chang and Chang, \{J. F.\} and Chen, \{A. M.\} and Chen, \{E. S.\} and Chen, \{G. H.\} and Chen, \{H. X.\} and Liang Chen and Long Chen and Chen, \{M. J.\} and Chen, \{M. L.\} and Chen, \{Q. H.\} and S. Chen and Chen, \{S. H.\} and Chen, \{S. Z.\} and Chen, \{T. L.\} and Chen, \{X. B.\} and Chen, \{X. J.\} and Y. Chen and N. Cheng and Cheng, \{Y. D.\} and Chu, \{M. C.\} and Cui, \{M. Y.\} and Cui, \{S. W.\} and Cui, \{X. H.\} and Cui, \{Y. D.\} and Dai, \{B. Z.\} and Dai, \{H. L.\} and Dai, \{Z. G.\} and Danzengluobu and Diao, \{Y. X.\} and Dong, \{X. Q.\} and Duan, \{K. K.\} and Fan, \{J. H.\} and Fan, \{Y. Z.\} and J. Fang and W. Mitthumsiri and P. Pattarakijwanich and D. Ruffolo",

note = "Publisher Copyright: {\textcopyright} Copyright owned by the author(s); 39th International Cosmic Ray Conference, ICRC 2025 ; Conference date: 15-07-2025 Through 24-07-2025",

year = "2025",

month = dec,

day = "30",

doi = "10.22323/1.501.0280",

language = "English",

volume = "501",

journal = "Proceedings of Science",

issn = "1824-8039",

publisher = "Sissa Medialab Srl",

}

TY - JOUR

T1 - Meteorological effects on the counting rates with KM2A in scaler mode

AU - LHAASO Collaboration

AU - Cao, Zhen

AU - Aharonian, F.

AU - Bai, Y. X.

AU - Bao, Y. W.

AU - Bastieri, D.

AU - Bi, X. J.

AU - Bi, Y. J.

AU - Bian, W.

AU - Bukevich, A. V.

AU - Cai, C. M.

AU - Cao, W. Y.

AU - Cao, Zhe

AU - Chang, J.

AU - Chang, J. F.

AU - Chen, A. M.

AU - Chen, E. S.

AU - Chen, G. H.

AU - Chen, H. X.

AU - Chen, Liang

AU - Chen, Long

AU - Chen, M. J.

AU - Chen, M. L.

AU - Chen, Q. H.

AU - Chen, S.

AU - Chen, S. H.

AU - Chen, S. Z.

AU - Chen, T. L.

AU - Chen, X. B.

AU - Chen, X. J.

AU - Chen, Y.

AU - Cheng, N.

AU - Cheng, Y. D.

AU - Chu, M. C.

AU - Cui, M. Y.

AU - Cui, S. W.

AU - Cui, X. H.

AU - Cui, Y. D.

AU - Dai, B. Z.

AU - Dai, H. L.

AU - Dai, Z. G.

AU - Danzengluobu,

AU - Diao, Y. X.

AU - Dong, X. Q.

AU - Duan, K. K.

AU - Fan, J. H.

AU - Fan, Y. Z.

AU - Fang, J.

AU - Mitthumsiri, W.

AU - Pattarakijwanich, P.

AU - Ruffolo, D.

PY - 2025/12/30

Y1 - 2025/12/30

N2 - The Large High Altitude Air Shower Observatory (LHAASO) consists of three sub-arrays: KM2A, WCDA and WFCTA. The KM2A contains 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). There are two common independent data acquisition systems, corresponding to the shower and scaler operation modes. In scaler mode, the KM2AED array is divided into 61 clusters. One cluster consists of 64 EDs (8 EDs × 8 EDs). For each cluster, the event rates of showers having a number of fired EDs within a time coincidence of 100 ns (particle multiplicities m) = 1, 2, 3, 4.. are recorded every 0.1 s. The scaler mode began acquiring data on June 21, 2023. In this study, we analyze the scaler mode data to study the meteorological effects on the counting rates with different multiplicities. Over long time periods, the distributions for all Ci (means the counting rate for m = i) are influenced by meteorological parameters, such as the atmospheric pressure (P) and temperature (T). The counting rates decrease with increasing P and T. The correlation coefficients between the counting rates and the meteorological parameters are studied in this work. After correcting for meteorological effects, the counting rates become stable over long time periods, with C1 following a Gaussian distribution and C2, C3 and C4 following Poisson distributions.

AB - The Large High Altitude Air Shower Observatory (LHAASO) consists of three sub-arrays: KM2A, WCDA and WFCTA. The KM2A contains 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). There are two common independent data acquisition systems, corresponding to the shower and scaler operation modes. In scaler mode, the KM2AED array is divided into 61 clusters. One cluster consists of 64 EDs (8 EDs × 8 EDs). For each cluster, the event rates of showers having a number of fired EDs within a time coincidence of 100 ns (particle multiplicities m) = 1, 2, 3, 4.. are recorded every 0.1 s. The scaler mode began acquiring data on June 21, 2023. In this study, we analyze the scaler mode data to study the meteorological effects on the counting rates with different multiplicities. Over long time periods, the distributions for all Ci (means the counting rate for m = i) are influenced by meteorological parameters, such as the atmospheric pressure (P) and temperature (T). The counting rates decrease with increasing P and T. The correlation coefficients between the counting rates and the meteorological parameters are studied in this work. After correcting for meteorological effects, the counting rates become stable over long time periods, with C1 following a Gaussian distribution and C2, C3 and C4 following Poisson distributions.

KW - Cosmic rays

KW - LHAASO-KM2A

KW - Meteorological effects

KW - Scaler mode

UR - https://www.scopus.com/pages/publications/105029066770

U2 - 10.22323/1.501.0280

DO - 10.22323/1.501.0280

M3 - Conference article

AN - SCOPUS:105029066770

SN - 1824-8039

VL - 501

JO - Proceedings of Science

JF - Proceedings of Science

M1 - 280

T2 - 39th International Cosmic Ray Conference, ICRC 2025

Y2 - 15 July 2025 through 24 July 2025

ER -

Meteorological effects on the counting rates with KM2A in scaler mode

Abstract

Keywords

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