Things cryotarget operators should know
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JP has summarized the main parameters every target operator should be familiar with. If you are not familiar with those parameters you should stop by to another shift before yours come to get acquainted with those with a more experienced target operator. If you have additionnal questions please contact JP Chen email@example.com
Cryotarget for DVCS, due to share cryogenics with Hall C QWeak target, TO must pay attention to the cryogenic situation.
1) Loop 1 for LD2, operating at 22K, ~25 psi
Loop 2 for LH2, operating at 19K, ~25 psi
2) When the target used in beam, set fan to 60 Hz (25%),
and HP heater at beam heat +50 watts (for 10 uA, it is 60+50=110 watts).
When the target not used in beam, set fan to 24 Hz (10%).
and HP heater to 30 watts.
3) Watch loop temperature, pressure, heater power and check fan speed. Watch 15K supply temperature (CTD 673), it should be between 13-14K when Hall C target is cold. Can be 15-16 K when Hall C target is warm. Watch 15K flow (CFI6731A), Hall A should be ~12 g/s when supply is 13-14K (~15 g/s when supply is 15-16K).
4) When target temperature rises (alarm), check the 15K supply temperature and flow. It often is due to 15K supply temperature increasing. In this case, DO NOT increase Hall A flow if Hall C is in full power. Inform the target-on-call. If the target temperature rises significantly (more than 2K), reduce the fan speed to 24 Hz (10%) to protect the fan from burned out.