Conclusions

Nearly all mechanical and electronical components in CCD cryostats were measured. Which probes show a similar spectral feature as the contaminated CCD and could be the origin of the contaminants?

The lines of the contaminated chip at 50 amu, 55 amu, 56 amu, 57 amu and 69 amu appear for a large variety of probes and may be caused by various components. 51 amu and 73 amu occasionally appear in the background as well, but their occurence for the probes should not be overestimated. Against that the lines at 53 amu, 67 amu and 71 amu are relatively infrequent and therefore they are important clues.

53 amu is only emitted by the Master Bond glue, finger grease, the painted shields and an improperly baked VITON^™ O-ring. 67 amu appears for the Master Bond glue, finger grease and well baked VITON^™ O-rings. Glue and O-ring are the only origins for the line at 71 amu.

Actually the contaminated CCD was located in a cryostat where "Honey Glue" was used instead of Master Bond glue. Therefore our probe of glue cannot be regared directly as the cause of the contamination, even though it exhibits all those spectral features known from the contaminated chip.

These features may also be evoked respectively by finger grease or the O-ring itself which shows nearly all the lines in question. However it is more likely that the contamination is caused by the overall outgassing of several components.