Proton Radiation Test of Gamma-Ray Transients Monitor (GTM) on Board Formosat-8B

The Gamma-ray Transients Monitor (GTM) is a secondary payload on board Formosat-8B (FS-8B), a Taiwanese remote-sensing satellite, to monitor Gamma Ray Bursts (GRBs) and other bright gamma-ray transients in the energy range from 50 keV to 2 MeV. The readout module of GTM was built with all commercial-off-the-shelf (COTS) components to meet very restricted power and size requirements, including frontend analog devices, switching and linear regulators, interface devices and field programmable gate array (FPGA). Therefore, a 221 MeV proton radiation test in the Proton and Radiation Therapy Center of Chang Gung Memorial Hospital, Taiwan was conducted to ensure the reliability of GTM readout module operated in the low earth orbit (LEO) environment. The accumulated 221 MeV proton fluence in this test was 1.03×10¹¹ proton/cm², equivalent to 5.6 krad(Si), with average proton flux 2.50×10⁷ proton/cm²/sec. There was not any catastrophic event observed in this proton radiation test. Only soft error events were seen with reasonably low cross-sections.