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installation_fp_sci [2017/06/13 12:07] pereira [Pumping focal-plane chamber] |
installation_fp_sci [2019/07/01 09:45] pereira [Pumping focal-plane chamber] |
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====== Installation of focal-plane scintillator ====== | ====== Installation of focal-plane scintillator ====== | ||
- | ==== Vent focal-plane chamber ==== | + | In June 2019, a new Turbo Pump with magnetically-levitating bearings (Leybold MAG 2200iP) was installed in the S800 focal-plane chamber. This pump has a dry-N line connected to it that is purging continuously the bearings. This creates an extra pressure in the foreline, which must be pumping down continuously. Therefore, it is critical turn off the turbo pump whenever the foreline valve needs to be closed. |
+ | |||
+ | Instructions on how to vent/ | ||
+ | ===== Vent focal-plane chamber | ||
* Open the [[hv_bias|HV Remote Control]] GUI and ensure that the focal-plane detectors are unbiased | * Open the [[hv_bias|HV Remote Control]] GUI and ensure that the focal-plane detectors are unbiased | ||
- | * Open the [[gas_handling_system# | + | * Open the [[gas_handling_system# |
* Ensure that the manual venting valve located on the south side of the chamber is closed (see figures below) | * Ensure that the manual venting valve located on the south side of the chamber is closed (see figures below) | ||
* Ensure that the FP ion gauge (I264IG) is off (see details [[vacuum_control|here]]) | * Ensure that the FP ion gauge (I264IG) is off (see details [[vacuum_control|here]]) | ||
- | * Open PanelMate and select **S800vac** file in directory \\exp\files\control\ncsdata\General\Qt\Templates. Go to page 07, click on the **VENT STATUS** window and begin the venting procedure. The **VENT VALVE I260VV** window will turn red and display " | + | * Open PanelMate and select **S800vac** file in directory \\exp\files\control\ncsdata\General\Qt\Templates, and go to page 07 (see figure below) |
+ | {{: | ||
+ | * Close I265GV (gate valve separating FP box from rest of beam line) is closed. | ||
+ | * Click on the **VENT STATUS** window and begin the venting procedure. The **VENT VALVE I260VV** window will turn red and display " | ||
* Gently open the manual venting valve until the pressure displayed in the Pirani Gauge (see figure below) increases by ~1 torr every 15 seconds (see figures below) | * Gently open the manual venting valve until the pressure displayed in the Pirani Gauge (see figure below) increases by ~1 torr every 15 seconds (see figures below) | ||
{{: | {{: | ||
+ | * Make sure that pressure inside the CRDCs and IC detectors (LabView) increase at the same rate than the pressure in the chamber. Otherwise, stop the venting process inmediately. | ||
* Wait until the chamber is vented (few hours). The **I261PG** Pirani Gauge should read slightly above atmospheric pressure (due to the dry N2 flow pumped to the chamber). The window **VENT STATUS** in PanelMate should display "VENT VALVE OPEN". The window **PUMPDOWN STATUS** should display " | * Wait until the chamber is vented (few hours). The **I261PG** Pirani Gauge should read slightly above atmospheric pressure (due to the dry N2 flow pumped to the chamber). The window **VENT STATUS** in PanelMate should display "VENT VALVE OPEN". The window **PUMPDOWN STATUS** should display " | ||
+ | * Meanwhile, turn the turbo pump off using PanelMate **S800vac**: | ||
+ | * When the Turbo pump is fully stopped, switch off the chiller located near the S800 electronics rack | ||
+ | * When the chamber is fully vented, select **VENT STATUS** and click **STOP VENTING PROCEDURE**. This will automatically close the vent valve **I260VV** | ||
+ | * Close the manual vent valve | ||
- | ==== Open focal-plane chamber ==== | + | ===== Open focal-plane chamber |
* After venting the FP chamber, the pressure inside the chamber is slightly above atmospheric due to the dry N2 pumped. Before opening the chamber, it is recommended to vent the extra N2 by " | * After venting the FP chamber, the pressure inside the chamber is slightly above atmospheric due to the dry N2 pumped. Before opening the chamber, it is recommended to vent the extra N2 by " | ||
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- | ==== Installing FP scintillator ==== | + | ===== Installing FP scintillator |
* The figure below shows the FP chamber open, with the " | * The figure below shows the FP chamber open, with the " | ||
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- | ==== Closing focal-plane chamber ==== | + | ===== Closing focal-plane chamber |
* Turn the switch to move the chamber to position " | * Turn the switch to move the chamber to position " | ||
- | * When the chamber is almost | + | * Check the display indicating the weight lift by the hydraulic system. |
+ | * Turn the knob to close the clamps | ||
+ | * Inspect the clamps and chamber flange (no gaps) to ensure that the chamber is properly sealed | ||
* Before pumping the chamber down, make sure that the scintillator is properly connected. This can be done by biasing the detector and checking the signals, either from the scalers or with a scope. One should clearly see cosmic rays; if that is not the case, the phototubes are likely miss connected | * Before pumping the chamber down, make sure that the scintillator is properly connected. This can be done by biasing the detector and checking the signals, either from the scalers or with a scope. One should clearly see cosmic rays; if that is not the case, the phototubes are likely miss connected | ||
- | ==== Pumping focal-plane chamber ==== | + | ===== Pumping focal-plane chamber |
- | * In order to pumpdown the chamber, make sure that the manual vent valve is closed and the pressure-relief valve is properly | + | * Make sure that the pressure-relief valve and the manual vent valve (see above) are closed. |
- | * Start manual pump to get a pressure below 50 mtorr | + | * Make sure that manual |
- | {{: | + | * Open the gas-handling-system LabView control and make sure that the only open detector valves are **4** (IC supply), **5** (IC bypass), **6** (IC focal-plane bypass), **7** (Ion Chamber vent), **20** (CRDC supply), **21** (CRDC bypass), and **22** (CRDC focal-plane bypass) and **23** (CRDC vent). The rest of the valves should be closed. The pressure inside the detectors should be ~760 Torr. |
- | * Close the manual pump; open PanelMate **S800vac** and go to page 07. Select window **PUMPDOWN STATUS** and click on button **START PUMPDOWN**. The **PUMPDOWN STATUS** and **VENT STATUS** windows should display " | + | * Open PanelMate **S800vac** and go to page 07. Make sure that the venting valve **I260VV** is closed (see last step of the [[#Vent focal-plane chamber|venting process]] described above) |
- | * Wait for some hours until vacuum is good | + | * Make sure that the turbo pump is off (as seen in PanelMate **s800vac**, |
+ | * Select window **PUMPDOWN STATUS** and click on button **START PUMPDOWN**. The **PUMPDOWN STATUS** and **VENT STATUS** windows should display " | ||
+ | * The vent valve **I260VV** and foreline valve **I260FV** will be automatically closed | ||
+ | * After the rough valve **I260RV** is automatically open, the mechanical pump will start pumping. | ||
+ | * The pressures in the mechanical pump (from **I259PG**) and beam chamber (from **I261PG**) will jump momentarily to very high values. They should go down slowly after few seconds (otherwise, the chamber is not properly closed). | ||
+ | * Make sure that pressure inside the CRDCs and IC (LabView) decrease at the same rate as the chamber. Otherwise, stop the pump-down sequence immediately. | ||
+ | * Note that during the rough pump-down sequence, pressure in the foreline I260PG will increase to few torr due to the purge line connected to the turbo pump. This is ok, as long as the turbo pump is OFF | ||
+ | * When pressure in **I261PG** is ~95 mTorr, turn on the chiller providing cooling water to the turbo pump. | ||
+ | * When pressure in the chamber (from **I261PG**) gets below 90 mTorr (at least 45 min), **I260RV** will close. | ||
+ | * Open the foreline valve **I260FV** using PanelMate box **Foreline vlve I260FV ** and clicking " | ||
+ | * When pressure in the foreline (**I260PG**) is below 200 mTorr, turn on the turbo pump. You will see the speed increasing in the PanelMate box " | ||
+ | * It takes about 8 min to get the turbo pump "At Speed" (as read in box **Turbo pump focal plane detector I260TP**). During that time, the pressure in the focal-plane chamber will slowly increase (it is not being pump down) by few mTorr | ||
+ | * When the turbo pump is "At Speed" and pressure in the chamber (as read in **I261PG**) is below 175 mTorr, the turbo-pump gate valve **I260GV** will open | ||
+ | * After **I260GV** gets opened, you will see a pressure spike in the foreline **I260PG** up to ~1 Torr. This is normal behavior. This pressure will slowly decrease below 200 mTorr in about 2 minutes. It will take at least 30 min to reach the nominal value (~60 mTorr). | ||
+ | * Wait for few hours until vacuum is good. You can then turn on the ion gauge **I264IG** | ||
+ |