Hall C Drift Chamber Threshold Controls

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Basic controls


Run 'jmenu' and search for 'threshold', and select the 'HallC Drift Chamber Thresholds' item.


If the readbacks ('Read' fields) are white instead of the green, then there is a communications issue.

  • Usually this can be resolved by clicking the 'Remote' button a few times.

If the readback is green, but reads zero and it won't respond to changes in the set value then you need to go into the Hut and push the 'Output On/Off' button on the front of the HP E3631A threshold supply (near the Acopian drift chamber power supply rack).

  • NOTE: You may have to switch to 'Local' control to do this
    • Look for the button on the front panel that has 'Local' underneath it and press it, then press the 'Output On/Off' button.
    • You will then need to switch back to 'Remote' mode using the GUI.

Resetting communications

If that doesn't work, then the IOC may need to reset/resync itself.

  • Go into the detector hut and find the HP E3631A threshold supply (near the Acopian drift chamber power supply rack) and you should see a small black Portserver attached to it via an 'ethernet' cable (really a serial connection).
    • You will likely be hearing beeps coming from the power supply as it rejects commands that it doesn't know how to deal with.
  • Powercycle the Portserver by unplugging its power cord for a moment.
    • The beeping should pause for a while and will then restart.
  • Open the 'Thresholds' GUI and try beating on the 'Remote' button a couple times and the readbacks should go green.
    • Verify that the setpoints and readbacks are correct before leaving the hut in case you need to enable the power supply output. (See Troubleshooting above.)