We perform irradiations of space electronics in a free-field cobalt-60 gamma source. Typically, a 200 Gy Total Irradiation Dose (TID) is delivered in the low dose-rate window: 0.36 - 3.6 Gy/h defined by ESA in the "Total Dose Steady-state irradiation test method" (ESCC basic specification no. 22900). However, irradiations up to a dose rate of about 30 Gy/h can be performed.
The dose to silicon on the back side of the device is computed on the basis of an air-kerma measurement at the position of the electronics and a Monte-Carlo model of the device under irradiation.
Validation measurements of the specific model of the device can be carried out with a large array of detectors. We measure the attenuation of the device along a line of detectors across the device (3 mm resolution ) and compare that with the Monte Carlo model results. The validation procedure may be supplemented with a 100 kV x-ray image of the device.
Online measurements of power consumption (voltage and/or current) to the electronics, low-level bias currents (pA) for semiconductors or other parameters can be monitored by DTU during the irradiation.
Typically an irradiation takes 3 days. The environmental conditions of the irradiation room are normally controlled to be 21 degC and 45 % relative humidity.
