摘要
Introduction The water Cherenkov detector array(WCDA)is an important detector in the Large High Altitude Air Shower Observatory(LHAASO),which is tasked with continuously surveying VHE gamma-rays sky.The WCDA covers an area of 78,000 m2 and contains 350,000 tons of purified water.The water quality and its stability are critical for its performance and long-term operation.Method Light is exponentially attenuated when propagating in water.Water attenuation length can be obtained by comparing light intensities at different optical path lengths,which is the basic principle of direct measurements.Here,a cylindrical device was designed to continuously monitor and measure water quality in the LHAASO-WCDA.Conclusion The systematic error of the cylindrical device was about 4.1%,indicating it is capable of measuring the water attenuation length in WCDA.Furthermore,suspended particle number and turbidity were confirmed as significantly related to the measured attenuation length.
基金
supported by the National Natural Science Foundation of China[Grant Nos.12005246 and 12173039]
the Department of Science and Technology of Sichuan Province[Grant No.2021YFSY0030]
the Key R&D Program of SiChuan Province[Grant No.2019ZYZF0001]
the Xie Jialin Foundation of IHEP.
