Radiation Hardness Assurance for the JEM-EUSO Space Mission

This analysis documents the process and results of reliability determination of the PhotoMultiplier Tube (PMT) components of the JEM-EUSO telescope under the different radiation sources, UV radiation, Total Ionizing Doses (TIDs), and Single Event Transients. In terms of UV Ionization, the transmittance of the glass of the PMTs during the 5-year duration of the mission is greater than 99.98%, thereby ensuring the desired 20% value for quantum efficiency. Of the 4932 PMTs covering the focal surface of the telescope, we estimate that of order 7 may fail due to TID and about 16 may fail due to SET. Therefore, it can be concluded that around 99% of the PMTs will complete their operation without failure, ensuring the success of the mission as far as TIDs and SETs radiation is concerned. PMTs suffer basically due to high brightness effects, reducing the transmittance of the crystal window. However, the result of this study, taking into account the values produced by the model based on the TID, as well as the darkening of the glass, show similar values in terms of degradation. Therefore, as a preliminary result, it is possible to conclude that the TID model proposed here for PMTs can be “validated”. & 2014 Elsevier Ltd. All rights reserved.