Description
The coherent muon to electron transition (COMET) experiment is searching for evidence of new physics via direct muon to electron decays in muonic aluminium, aiming to reach a sensitivity of $3\times10^{-15}$ in Phase-I and $1\times10^{-17}$ in Phase-II, a factor 10000 improvement. The detector system for Phase-I, currently under construction at the J-PARC facility in Japan, is comprised of a cylindrical drift chamber (CDC) and cylindrical trigger hodoscope (CTH), which provide $<200\,\mathrm{keV/c}$ momentum and $<1\,\mathrm{ns}$ timing resolution respectively to identify this process. In order to achieve this goal, the radiation exposure and background trigger rate in the CTH detector needs to be understood and minimised, particularly for the scintillator counters and optical fibres for the CTH which are inside the high radiation environment. High radiation exposure can reduce the light yield of these counters and fibres substantially across the data collection period, and we use ICEDUST, the simulation and analysis toolkit for COMET, to measure these effects. In this talk, I will discuss the implementation of updated and realistic optical fibre geometries and new radiation shielding geometry and material options to minimise the radiation dosage. This allowed for measurements and optimisation of the neutron fluence and total ionisation dose experienced by the scintillator counters and optical fibres in the CTH. Additionally, we combined this study with improvements in our detector response simulation to measure the realistic background trigger rate, ensuring that our detector meets its operational requirements and achieves the physics goal of Phase-I.
| I am the presenting author | Yes |
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