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Venting/pumping II chamber & emptying/filling gaseous detectors

General information

The procedures to vent/pump the S800 Intermediate Image box, and/or filling the PPAC detectors with gas must be done carefully to ensure that the PPACs are not damaged. For instance, before venting the chamber, we have to make sure that the PPACs are empty and equalized with respect to the vacuum in the chamber. In order to avoid errors, an automated gas handling system (II-GHS) was designed to perform these tasks safely. The II-GHS equipment (valves, flow-meter, pipes, isobutane gas bottle. etc.) are located on the west balcony of the top level in the S3 vault (see figure below):

Gas Handling System of S800 Intermediate Image

The GHS is operated remotely through CS studio. Its page can be found on the EXP network through FRIB EXP Main → S800 → GHS Pages (Secondary Pages) → Intermediate Image PPAC and is shown below.

The layout of the II-GHS is shown below.

The operational states of the II-GHS are shown in the diagram below.

Emptying Detectors

  1. Set “PPAC Setpoint” to 0 Torr.
  2. Click EMPTY on the “GHS_II-PPAC_Main” page to begin pumping out the gas quickly.
  3. When “PPAC Pressure” reads < 0.1 Torr, click MAN and then AUTO. This will release the remaining gas into the diagnostics box.
  4. Monitor D2340 pumping station and ensure the TMP stays on and TGV remains open. If not, contact the Vacuum Operation group.
  5. Valves #1-5 should be closed and valve #6 should remain open. From this state click PUMP to enter pump mode and leave the system in this state until it is ready to be filled.
    • Jorge noted on 2/12/2023 that this step did not work; he reported that when he clicked PUMP nothing happened. Instead, he had to “manually” enter the PV name associated with this command and changed from 0 to 1. He speculated that this was most likely due to a CS Studio problem.

Filling and Running Detectors

  1. If in Vent Mode, click PUMP then click RUN to enter Run Mode.
  2. If in Pump Mode, click RUN to enter Run Mode.
  3. Plot and monitor IG_D2430:VP_RD while filling. Ion gauge reading will increase but should remain <1E-5 Torr when PPACs are running at full pressure.
  4. Step up “PPAC Setpoint” by 1 Torr from 0 to 6 Torr. Allow the “PPAC Pressure” to stabilize for 15 seconds at each step. This should be a quick process but DO NOT simply set the “PPAC Setpoint” to 6 Torr as the gas flow could overwhelm the system.
  5. PPAC pressure should stabilize after ~1 min. HV may now be turned on to operate the PPACs.


  1. If any issues are encountered during filling, running, or emptying, contact the Vacuum Operation group for assistance.
venting_pumping_intermediate_image_box.txt · Last modified: 2023/02/13 14:40 by noji