Design and performances of prototype muon detectors of LHAASO-KM2A

Zuo, Xin; Xiao, Gang; Feng, S. H.; Li, Xiurong; Liu, Cong; Hong, B.; Chang, J. F.; Wang, Wei; Gu, M. H.; Li, Fēi; Liu, Jia; Lv, Hongkui; Sheng, X. D.; Zhang, Shaoru; Li, Hongming; Gong, Guanghua; He, H. H.

doi:10.1016/j.nima.2015.04.010

Cited by 33 publications

(26 citation statements)

References 9 publications

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“…CutV alue(H) = 0.09 × lg(Energy/T eV ) + 0.55 (19) CutV alue(H&He) = 0.33 × lg(Energy/T eV ) − 0.26 (20) XXXXXX-12 After the cut described above, the aperture and contamination of hybrid observation are calculated. The aperture of pure proton is about 900m 2 Sr and the aperture of H&He is about 1800m 2 Sr, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Expected energy spectrum of cosmic ray protons and helium below 4 PeV measured by LHAASO *

Yin¹,

Zhang²,

Cao³

et al. 2019

Chinese Phys. C

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Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array (KM2A) which includes the electromagnetic detector array and muon detector array, water Cherenkov detector array (WCDA) and wide field of view Cherenkov telescope array (WFCTA). One of the main scientific objectives of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 10 14 eV to 10 18 eV. The hybrid observation will be employed by LHAASO experiment, in which the lateral and longitudinal distributions of the extensive air shower can be observed simultaneously. Thus many kinds of parameters can be used for primary nuclei identification. In this paper, high purity cosmic ray simulation samples of light nuclei component are obtained through Multi-Variable Analysis. The apertures of 1/4 LHAASO array for pure proton and mixed proton and helium (H&He) samples are 900 m 2 Sr and 1800 m 2 Sr respectively. A prospect of proton and H&He spectra from 100 TeV to 4 PeV is discussed.

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Section: Resultsmentioning

confidence: 99%

“…As its name describes, the ED detects the electromagnetic particles in the EAS. MD array is an underground water Cherenkov detector array [19]. There are 1171 muon detectors also covering 1 km 2 area with a spacing of 30 meters.…”

Section: The Hybrid Experimentsmentioning

confidence: 99%

Expected energy spectrum of cosmic ray protons and helium below 4 PeV measured by LHAASO *

Yin¹,

Zhang²,

Cao³

et al. 2019

Chinese Phys. C

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“…13(left)). All the prototypes have been in operation for more than 2 years, and their performance fully meets the design requirements, see [18][19][20][21][22][23] for details.…”

Section: Lhaaso Prototype Arraysmentioning

confidence: 99%

Design of the LHAASO detectors

2018

Radiat Detect Technol Methods

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Introduction The Large High Altitude Air Shower Observatory plans to build a hybrid extensive air shower array with an area of about 1 km 2 at an altitude of 4,410 m a.s.l. in Sichuan province, China, to explore the origin of high-energy cosmic rays. KM2A LHAASO-KM2A will detect gamma ray sources with a sensitivity of about 1% Crab Unit at 100 TeV. It covers an area of 1 km 2 with a total of 5195 scintillation detectors. Its angular resolution reaches about 0.3 degrees, and the energy resolution is better than 25%. With the help of 1171 muon detectors, cosmic nuclei background will be rejected to a level of 10-4 at 50 TeV. The design and performances of the scintillation detectors and muon detectors are described in detail. WCDA LHAASO-WCDA focuses on surveying the northern sky for steady and transient sources from 100 GeV to 20 TeV, with a very high background rejection power and a good angular resolution. The WCDA consists of three water ponds with a total area of 78,000 m 2 , and the effective water depth is 4 m. Each water pond is divided into 5m × 5m cells partitioned by black plastic curtains to prevent penetration of the light from neighboring cells. An 8-inch PMT sits at the bottom center of each cell, looking upward to collect Cherenkov light generated by shower secondary particles in water. WFCTA LHAASO-WFCTA is composed of 12 wide-field-of-view Cherenkov/fluorescence telescopes. Each telescope consists of a spherical light collector of about 4.7 m 2 and focal plane camera of 32 × 32 pixels with a pixel size of 0.5 degree. LHAASO prototype arrays A prototype array about 1% of LHAASO has been constructed at Yangbajing Cosmic Ray Observatory and has been in operation for more than 2 years. Its performance fully meets the design requirements. Conclusion The LHAASO detectors are designed to fulfill the physical goals in gamma ray astronomy and cosmic ray physics. One-fourth of LHAASO will be constructed and put into operation to produce physical data by the end of 2018. The whole array will be finished in the beginning of 2021.

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“…Two MD prototypes of the same design, have been constructed at the Yangbajing Cosmic Ray Observatory (4300 m a.s.l.). Data analysis [7] and detailed GEANT4 simulation [8] have been performed to understand the signals of the MD prototypes, and the theory of photon propagation has fully been studied. When a charged particle passes through the water Cherenkov detector faster than the phase velocity of light in water, it generates approximately 300 Cherenkov photons per cm with wavelengths in the range of 300-600 nm.…”

Section: Introductionmentioning

confidence: 99%

Novel methods for measuring the optical parameters of the water Cherenkov detector

Xiao

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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In this paper, novel methods are presented to measure the optical properties of muon detectors (MDs) in the Large High-Altitude Air Shower Observatory (LHAASO), which can also be used by other experiments. Each MD consists of a cylindrical water Cherenkov detector, with a Tyvek liner containing pure water, and a photomultiplier tube (PMT) mounted on the top. The time distribution of the photons collected by the PMT in the water Cherenkov detector have an approximately exponential distribution, and their decay factor is determined by the photon absorption length in the water, the reflectivity of the inner Tyvek surface, the mean reflecting step length of photons reflected by the inner surface, and the ratio of reflectional Tyvek area to the total inner surface area. By considering the principles of photon propagation in the water Cherenkov detector, we have developed novel methods to measure the water absorption length, the Tyvek reflectivity, and the mean step length of photons. The step length of photons can be determined by measuring the time distribution of the reflected photons hitting the PMT after multiple photons with single wavelength are generated in the tank, with slightly different ratios of the inner Tyvek to the total inner area. The water absorption length and Tyvek reflectivity can be measured simultaneously by the PMT by changing the height of the water, while the step length and Tyvek reflectivity in air can also be measured simultaneously. The proposed novel methods are supported by deduction of formulae and verified by GEANT4 simulations and the prototype experiment.

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Design and performances of prototype muon detectors of LHAASO-KM2A

Cited by 33 publications

References 9 publications

Expected energy spectrum of cosmic ray protons and helium below 4 PeV measured by LHAASO *

Expected energy spectrum of cosmic ray protons and helium below 4 PeV measured by LHAASO *

Design of the LHAASO detectors

Novel methods for measuring the optical parameters of the water Cherenkov detector

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