Dealtry, T. and Doyle, T. A. and Finch, A. J. and Hatzikoutelis, A. and Kormos, L. L. and James, M. Lamers and Lamont, I. and Lawe, M. and O'Keeffe, H. M. and Ratoff, P. N. and Walsh, J. G. and Xu, Yongheng (2022) Scintillator ageing of the T2K near detectors from 2010 to 2021. Working Paper. Institute of Physics.
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Abstract
The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9--2.2\% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator.