Summer 2022 detector checkout + CDC scans

From Hall D Ops Wiki
Revision as of 10:29, 10 June 2022 by Njarvis (Talk | contribs) (How to set the CDC HV and switch AI on/off)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

General detector calibration

  • Use 3×10-4 Al. radiator. Beam current 100nA. GlueX trigger. CDC at its default 2125V with the AI OFF (see below).
  • 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. CDC's HV AI switched OFF (see below).

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 (EPICS variable RESET:i:GasPanelBarPress1, 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 and switch AI on/off

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.

The AI is switched on/off using the button in the top middle of the CDC's HV GUI. It should only be toggled at the request of the detector expert or RC. When the AI is on, the CDC HV might be changed when the DAQ starts a run. When the AI is switched off the HV is unchanged - it does NOT set the HV back to the default 2125 automatically.