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A total of 5195 electromagnetic particle detectors (EDs) are used in the 1-square-kilometer extensive air shower array (KM2A), which is a subarray of the Large High Altitude Air Shower Observatory (LHAASO). As the detection sensitive medium of the EDs, more than 20,000 plastic scintillator units (BC-408), produced by Saint-Gobain, are used in LHAASO. It is important to monitor the light output of the scintillator units among the units. To improve the efficiency, a sampling inspection scheme (misjudgment rate of less than 5%) was designed, and a batch test system was developed. Ten units of scintillator units can be measured at a time. The test system selects the single muon events of cosmic rays to measure the light output values of the plastic scintillator units. The measurement has an uncertainty of less than 2%. By pretest calibration, the difference between different channels can be eliminated. The calibration was implemented approximately every 3 months, and the test system had been running stably for 28 months. By measuring the ratio of the signals of selected far and near probe events, the changes in the quality of different batches of plastic scintillator units can be demonstrated. The test system realized accurate measurement of the light output, and all batches satisfied the requirements of the experiment.

A wide field-of-view (FoV) is one of the most important goals for future ground-based γ -ray astronomy, and it is especially crucial for detailed studies of temporal and spectral characteristics of solitary events, such as γ -ray bursts (GRBs), highly variable sources like blazars, or potential very high energy (VHE) electromagnetic counterparts of gravitational waves (GWs). Atmospheric Cherenkov Telescope (ACT) based on refractive optics and operated at a very high altitude observatory may be an appropriate solution. In the present study, we report the characteristics and performance of a large FoV ACT prototype based on a refractive convex water lens. A reconstruction method for estimating the arrival direction of the air shower was developed by combining the water-lens telescope and the Extensive Air Shower (EAS) array. The Cherenkov images of the air showers were obtained by a water-lens prototype with 48 pixels, an FoV of 15 ° × 13 ° , and a median angular resolution of ∼ 0 . 9 ° .

A scintillation detector array composed of 115 detectors and covering an area of about 20000 m2 was installed at the end of 2016 at the Yangbajing international cosmic ray observatory and has been taking data since then. The array is equipped with electronics from Large High Altitude Air Shower Observatory Square Kilometer Complex Array (LHAASO-KM2A) and, in turn, currently serves as the largest debugging and testing platform for the LHAASO-KM2A. Furthermore, the array was used to study the performance of a wide field-of-view air Cherenkov telescope by providing accurate information on the shower core, direction and energy, etc. This work is mainly dealing with the scintillation detector array. The experimental setup and the offline calibration are described in detail. Then, a thorough comparison between the data and Monte Carlo (MC) simulations is presented and a good agreement is obtained. With the even-odd method, the resolutions of the shower direction and core are measured. Finally, successful observations of the expected Moon’s and Sun’s shadows of cosmic rays (CRs) verify the measured angular resolution.

GRANDProto35 is the first stage of the GRAND project. It will be composed of an array of 35 radio antennas and 24 scintillation detectors in which the radio and scintillating subarrays will be triggered independently. The scintillation detector array allows to cross-check the radio array, thus quantitatively determine its detection efficiency. The photomultiplier of Hamamatsu R7725 is a candidate for the scintillation detector. The characteristics of the PMT will directly affect the resolution of the time and energy measurements and the dynamic detection range of a scintillation detector. A voltage divider circuit featured with dual-readout was designed for the PMT to cover a larger linear dynamic range (LDR). Some characteristics of the PMT were calibrated and investigated: the absolute gain, single photoelectron (SPE) energy resolution, transit time spread (TTS), linear dynamic range, and temperature dependence of the PMT gain. In this paper, details about the system setup, measurement methods, and results will be described.

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads onboard China's Space Station, which is planned for operation starting around 2025 for about 10 ...

We are developing a wide field-of-view Cherenkov telescope with large dimensional refractive lens for sub-100 GeV to TeV gamma ray astronomy. A prototype of the refractive telescope with a camera composing of 48 PMTs and the front-end electronics is designed, assembled, and tested to demonstrate the feasibility of the concept. In this work, we report some preliminary results on the detection of high energy Cosmic Rays (CRs) using the prototype telescope which was operated in coincidence with a scintillator detector array at the Yangbajing Observatory in Tibet.The prototype telescope can achieve a $15^{\circ} \times 11^{\circ}$ FoV and a ${\sim}0.8^{\circ}$ angular resolution which is suitable to take certain Cherenkov images for air showers.

International audience; The very low flux of ultra-high-energy cosmic-rays (UHECRs) requires detectors with a large effective area and high duty cycle to obtain a statistically relevant sample. Radio detection of extensive air showers (EAS) presents attractive aspects for future giant detectors of high energy cosmic particles, with very low cost per detection unit, easiness of deployment over large areas, and a duty cycle close to 100%. However autonomous detection of EAS -a necessary step towards the realization of this type of ambitious detectors- remains a challenge.GRANDproto35 aims at demonstrating that radio-detection of air showers can be performed with very good background rejection, high efficiency, and an almost 100% duty cycle. The 35 GRANDproto antennas will perform a full measurement of the detected wave polarization. This makes GRANDproto35 uniquely qualified for the investigation of polarization characteristics of the radio emission from EAS, which may contribute to discriminate them from background signals. In addition, an array of 24 scintillators will allow offline cross-checks of the nature of the selected radio-candidates. We detail here the principle, progress and prospects of GRANDproto35, which serves as a step towards the Giant Radio Array for Neutrino Detection (GRAND) project. GRAND will consist of an array of ∼ 10^5 radio antennas deployed over ∼ 200, 000 km^2 in mountainous sites.