$\star$ Ageing of the cameras and inefficiency of transfer of load

Studies showed and characterized the effects of temperature and ageing of the camera (holtzman199ä). The camera is permanently bombarded cosmic rays which influence the performances of the camera and involves an accelerated ageing of CCDs. The principal effect is a progressive decrease of the effectiveness of transfer of load during the reading.

The problem is posed by a mechanism of trapping of the loads because of the presence of chemical impurities in silicon or a bad surface quality on the level of the interfaces due to the ageing caused by the cosmic ones.

This effect is all the more significant as the pixels concerned are loins character sensing field of CCDs. the existence of this problem of inefficiency of transfer of load has in party solved by the fall in the temperature of CCDs holtzman1995b.

Despite everything, these defects are extremely well known and studied, their influence is foreseeable and thus corrigible a posteriori for more precision on these corrections to refer to dolphin2000a.