H. Tomida et al., RADIATION-DAMAGE ON X-RAY CCDS AND RESTORATION TECHNIQUE FOR SPACE ASTRONOMY, Publications of the Astronomical Society of Japan, 49(3), 1997, pp. 405-412
We studied the proton damage effects of the X-ray CCD, and searched fo
r a possible restoration technique in orbit. We measured the X-ray CCD
performances after irradiation at energies of 2 and 9.5 MeV, and conf
irmed a clear degradation of the charge transfer efficiency (CTE) and
the energy resolution. To restore the degraded CTE and energy resoluti
on, we tried a charge injection technique, and found the improvement i
n the CTI (= 1 - CTE) and energy resolution to be 1/4 and 1/3, respect
ively. We also estimated the energy level of the deep trap, which caus
es a quantization of the dark current from the radiation-damaged pixel
s. The trap energy level was about 0.57 eV, or near to the center of f
orbidden band.