High altitude water cherenkov detector performance

Experimental data on the temporal profile of signals from a Water Cherenkov Detector (WCD) of the CHARM Observatory (High Altitude Cosmic Radiation Monitor) are presented. CHARM is a hybrid array of Water and Air Cherenkov detectors located at 4300 meters under construction. The observatory is designed to study high-energy cosmic rays in the range of 10¹⁶-10 ¹⁸ eV, with the advantage of observing the maximum of the secondary particles shower generated by cosmic rays. This paper presents the results of temporal structure studies of two Water Cherenkov Detectors, one at 2200 m (at laboratory) and another one at 4300 m (at the CHARM site). We study the time rise parameter, peak amplitude and integrated charge of the signals obtained from the detector. This study is performed using secondary particles from the background. In both detectors we are using a photomultiplier tube (EMI- 9530A) on the top. The WCD containers are covered in the inner walls with a high UV reflectivity material called Tyvek and filled with pure water.