Radiation tolerance of straw-tracker read-out system for COMET experiment

The COMET experiment at J-PARC aims to search for the charged lepton flavor violating process of neutrinoless muon to electron conversion. The goal sensitivity is to be improved by a factor of 10000 to the current limit. In order to achieve the goal sensitivity, we have developed a straw tube tracker as an electron detector which has very high momentum resolution. To read out the signal from the tracker precisely, an optimal front-end electronics is also needed, and we have developed the readout electronics board called ROESTI. For the ROESTI, we need to consider radiation tolerance because the board will be installed in neutron and gamma-ray rich environment. We calculated radiation level with PHITS, and radiation tolerant parts have been selected and countermeasure against single event upset in FPGA was considered. Using the prototype, neutron and gamma-ray irradiation tests have been performed and radiation tolerance has been investigated. In this paper, we describe the latest radiation study with PHITS calculation and the results of irradiation tests of the ROESTI prototype.