TOF HV SCAN 2025

The TOF HV scan will follow similar procedure as in the past, TOF HV SCAN 2022 which followed TOF HV SCAN FALL 2019.

Proposed Scan Procedure for TOF

• Beam conditions: 100nA and 4.5e-4 amo radiator if one can run 150nA the better.
• set the HV of all TOF PMTs to the same values:
  • HV steps of 25V if time permits, else steps of 50V but include 1050 and 1425.
    • First pass: 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1425
    • Second pass: 1075, 1125, 1175, 1225, 1275, 1325, 1375
  • each run (HV setting) should last for about 20 evio files
  • change HV setting by using GUI, in menu "North-South" select "Set Parameters for North Channels" and set the desired value for "Voltage" the left most tab. And similarly for all other sectors of the TOF. All HV should be the same before taking data.

After the scan the nominal HV can be restored using the "Save/Restore" button at the top right of the GUI and selecting the "TOF: restore..." option. Choose the latest (topmost) file.

Notes from RC

• This scan can disruptive to other data taking because it requires frequent starting and stopping of the DAQ.
• Setting the voltages took a long time (~15 minutes) sometimes. While the voltages are stabilizing the DAQ doesn't run. We moved to a mode of noting down the evio files when things changes to improve efficiency.
• It wasn't clear but 150 nA isn't a limit so we moved to 200 nA at some point.
• How was the number of evio files determined? Was it for the current production trigger?