The radiation environment experienced by MPTB

We have been making continuous radiation dose measurements in HEO (Molniya) orbit aboard the same spacecraft as the MPTB (microelectronics and photonics test bed) experiment. In addition we have been making additional measurements since the Spring of 1994 in the same orbit. The nominal shielding thicknesses of the suite of sensors range from 5 mil (0.2 mm) of aluminum to 650 mil (16.5 mm) of aluminum in 9 channels. A figure shows the time history of the total dose per orbit for several shielding thicknesses, another figure presents a comparison of the observations with the predictions of the AE-8 and AP-8 models for the MPTB orbit. 2 main conclusions can be made: -) the HEO radiation dose measurements are in good agreement with the predictions of AP-8 and -) the predictions of AE-8 substantially exceed the measurements