Speaker
Description
For long-term UHECR observations, the gain calibration of photo-multiplier tubes (PMTs) in the Fluorescence Detector (FD) of the Telescope Array (TA) is crucially important to determine UHECR energies. Current uncertainty of PMT gain in TA FD is estimated to be 11% by adding 8% uncertainty of gain calibration using CRAYS in 2008 and 8% uncertainty of on-site monitoring using YAP pulser in quadrature. Here CRAYS is the system of Calibration using RAYleigh Scattering. We calibrate FD PMT using CRAYS again with more accurate laser and probe to achieve 3~4% calibration accuracy. And we have three application plans, the first is to provide calibrated PMTs to fluorescence measurement using electron beams in SLAC, named sFLASH, the second is to crosscheck with the end-to-end calibration result by ELS (on-site Electron Light Source) with calibrated PMTs, and the last plan is the calibration of PMTs of NICHE using CRAYS. Here NICHE is a low energy extension of TA and TALE using Cherenkov light. We will report the status and plan of the calibration.
| Presentation type | poster |
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