Summer 2022 detector checkout + CDC scans
General detector calibration
- Use 3×10-4 Al. radiator. Beam current 100nA. GlueX trigger. CDC at its default 2125V
- Run 15 min (solid time) in Long Mode (Mode 10)
- Run 15 min (solid time) in Production Mode (Mode 9).
Note the barometric pressure (EPICS variable RESET:i:GasPanelBarPress1, listed in RCDB as cdc_gas_pressure) when starting the production mode run.
- During one of these runs, when the beam current is steady, run the script below as hdops on one of the gluons. This will save some EPICS values that the CDC's AI will use later on.
/group/halld/AIEC/utilities/CDC_control_ai/cpp/AIEC_CDC_init.sh
The (rather lengthy) output messages should end with ‘Writing new config file...’. If there are any problems with the script, send Thomas an email, tbritton@jlab.org
Short CDC HV scan
- Use 3×10-4 Al. radiator. Beam current 100nA. GlueX trigger.
Please collect 9M triggers at the following HV settings (in V) for ALL CDC, in the order given below. In the logbook, please note the run number, HV and the pressure (listed in RCDB as cdc_gas_pressure) at the start of each run.
- 2150
- 2125 - you can skip this measurement if the pressure is within 0.02kPa of that for the production mode run for the general calibration
- 2100
If the pressure is changing by 0.05+ kPa between measurements, give up. We can try again after the empty target run.
Set the HV back to 2125V after the scan.
If the beam is steady then the whole procedure should take a few hours at most. If there are any problems, please contact the CDC experts (Beni and Naomi)
How to set the CDC HV
Find the main action bar (vertical menu), click CDC voltages.
In the middle of the circle on the left, click ALL HV, then select from the dropdown menu "CDC: Set CDC HV parameters" Change voltage to what you want in the left column, hit return.
