Trigger and noise filtering algorithms for the LHAASO water Cherenkov detector array

Wang, X.; Yao, Z. G.; Zha, M.; Chen, Mingjun; Gao, Bo; Huang, Dezhi; Li, Huicai; Liu, Jinyan; Liao, Wen-Ying; Wu, H. R.

doi:10.1007/s41605-017-0015-1

Cited by 5 publications

(4 citation statements)

References 14 publications

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“…As described in ref. [6], more than 45% of particle energy induced by a vertical 100 GeV gammas statistically falls into the region with radius of 30 m around the shower core; the percentage increases with increasing energy. Given this feature a trigger algorithm counting the hit multiplicity in every of tens of half-overlapped trigger clusters is implemented to eliminate the high-rate background noises of each detector.…”

Section: Time Calibration System 21 Precision Requirementmentioning

confidence: 95%

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Test bench for fibers of the LHAASO-WCDA time calibration system

Liu

Gao

et al. 2017

J. Inst.

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A: The Water Cherenkov Detector Array (WCDA), which is one of the main components of the Large High Altitude Air Shower Observatory (LHAASO), functions in surveying the northern sky for high-energy gamma ray sources at the energy range around of 100 GeV-30 TeV. The precision of the time measurement for shower particles hitting every detector in the array is directly associated with the detection sensitivity for the sources. The calibration precision of the time offsets among the detector cells should be less than 0.1 ns to obtain less than 0.1 • pointing error of the detector to any point source. In this regard, "cross calibration" is employed for the detector array, with 180 bundles of fiber systems guiding the lights of LEDs to each PMT. A test bench comprising fast PMTs and an one-dimensional slide platform is set up in the laboratory to test the fiber bundles. The test bench and the test procedure is described in this paper, and the test results are presented.

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Section: Time Calibration System 21 Precision Requirementmentioning

confidence: 95%

“…A fast iteration method searching for the the best sky cells in ref. [6] is employed to calculate angular resolution δθ, in which the degree-of-freedom for shower plane fitting is N − 2 because of two unknown parameters, i.e., zenith and azimuth for the direction.…”

Section: Time Calibration System 21 Precision Requirementmentioning

confidence: 99%

Test bench for fibers of the LHAASO-WCDA time calibration system

Liu

Gao

et al. 2017

J. Inst.

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“…Taken into account the features of lateral distribution of air showers, in order to reach a low energy threshold, a natural consideration on the trigger algorithm is to use the multiple zoned pattern. Once the number of fired cells in any of these zone exceeds a certain number within a short time window, the whole array is then set to be triggered [8]. For the 1/2 WCDA arrays, the EAS event trigger rate is about 80 kHz and the raw data is about 15 TB/day.…”

Section: Half Array (2020/3/16 − 2021/3/4)mentioning

confidence: 99%

Operations of the LHAASO-WCDA

Liu¹,

Chen²,

Gu³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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The Water Cherenkov Detector Array (WCDA) is one of the components of the Large High Altitude Air Shower Observatory (LHAASO). WCDA, divided into 3 separate arrays, will make survey observation on the gamma-ray sky of 100 GeV -30TeV. The first array (150m × 150m), denoted as WCDA-1, has already be operated since April 2019 and one more array of the same size, referred to as WCDA-2, has also been in operation since November 2019. The third array, WCDA-3, with a size of 300m × 110m, has been tested at beginning of 2021 and the full array of WCDA is being in the testing since March 2021. This paper will describe the operation status of the LHAASO-WCDA since April 2019.

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“…The curtains that separate the cells and bottom of the pool are made of black plastic to minimise reflections of the Cherenkov light. Most of secondaries are deposited in a limited area according to [4]. Hence, the full detector arrays is divided into 72 trigger clusters, whose dimension are 60 m×60 m, as shown in figure 2.…”

Section: Introductionmentioning

confidence: 99%

LHAASO-WCDA time calibration using high-statistic low-energy cosmic rays

et al. 2019

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A: The Large High Altitude Air Shower Observatory (LHAASO) is a multi-component experiment to study cosmic ray physics, which is under construction near Mt. Haizishan (4410 m a.s.l.) in Southwest China. The 78,000 m 2 Water Cherenkov Detector Array (WCDA), which is one of the main components of the LHAASO, will be able to survey the gamma-ray sky continuously in the energy range from 100 GeV to PeV. The precision of the time measurement in the detector cells of WCDA determines the sensitivity to the direction of gamma ray sources, necessitating a hardware calibration system to be deployed in the WCDA. Effects such as environment temperature variations will introduce time offsets between detector cells. In order to calibrate the time offset, a method using high-statistics low-energy cosmic rays has been developed. The detector cells are divided into clusters of 6×6 cells which are calibrated locally. This paper then describes the technique combining all the detector cells and demonstrates that the performance meets the requirements. The high-statistics of low-energy cosmic rays makes it possible to calibrate the detector in real time. K: Data processing methods; Pattern recognition, cluster finding, calibration and fitting methods 1Corresponding author.

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Trigger and noise filtering algorithms for the LHAASO water Cherenkov detector array

Cited by 5 publications

References 14 publications

Test bench for fibers of the LHAASO-WCDA time calibration system

Test bench for fibers of the LHAASO-WCDA time calibration system

Operations of the LHAASO-WCDA

LHAASO-WCDA time calibration using high-statistic low-energy cosmic rays

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