Different Dose Rate Radiation Effects on Linear CCDs

Charge coupled devices (CCD) have been tested at widely differing dose rates to examine the radiation tolerance dependence on the dose rates. The test results show a maximum tolerance of CCDs at 10.2 rad(Si)/sec, a slight reduction in tolerance at 34.8 rad(Si)/sec and a quite precipitous roll off when moving down to 1 rad(Si)/sec and 0.1 rad(Si)/sec. The degradation of the dummy output voltages and the dark signal voltages are compared at the dose rates of 0.1,1.0,10.2 and 34.8 rad(Si)/sec, respectively. It shows that the degradation levels depend on the dose rates. The CCDs are divided into two groups during ⁶⁰Co γ irradiation. Either the output amplifiers or the photo sensing and the shift register areas are shielded with Pb during the irradiation tests.