MCA peak drift due to NaI+PMT component of an Oxford 3" detector

[LAM HOI CHING <lamhc@hkusua.hku.hk>]

Subject : MCA peak drift in Oxford 3" crystal combined with PMT

Thank you for the Radsafe advices last time,my final investigation showed
High Volt and Low volt supply are both all right. Luckily I kept the last
Bicron 2" crystal and PMT in the year 96 . The replacement by the old 2"
Bicron crystal+PMT from current used 3" Oxford crystal &PMT  have
eliminated the gain shift problem. The current preamplifier and amplifier
are embedded in the Oxford Model 5000 system. So I don't think any problem
with that system. But I still wonder why the 3" Oxford crystal and PMT is
such short life in a controlled temperature and humidity environment.
	Thank you very much for those helpful guidance.