Cherenkov counters settings
Cherenkov Settings:
Electron runs:
- Discriminator threshold: C1=140 mV, C2=150mV
- Pressure settings:
Energy |
C1 pressure |
C2 pressure |
|---|---|---|
0.5 GeV |
0.9 bars |
0.95 bars |
1 |
0.9 |
0.95 |
2 |
0.8 |
0.95 |
3 |
0.8 |
0.95 |
4 |
0.5 |
0.6 |
5 |
0.4 |
0.4 |
6 |
0.22 |
0.22 |
7 |
0.18 |
0.18 |
|
|
|
|
|
|
Proton runs:
- Discriminator threshold: C1= 30 mV, C2 = 30 mV
- Pressure settings
Energy |
C1 pressure |
C2 pressure |
|---|---|---|
6 - 10 GeV |
2 bars |
2 bars |
Instructions to set Cherenkov counters pressure
Note: at least once a day the cherenkov counters need to be completely evacuated and refilled. This operation takes about half an hour.
The Cherenkov rack is divided in two parts: the upper part for C1, the lower part for C2. All the operations must be performed on both Cs.
How to empty Cherenkov counters:
- Look at the pressure values: if they exceed 1 bar (after a proton run), use the yellow lever to reduce the pressure to about 1 bar by slowly rotating it in anticlockwise direction. You don't need to completely open it.
If the pressure is <1 bar follow the instructions below:
- Turn on the pump power switch located on the wall just behind the Cherenkov rack
- Rotate the red valves located on the bottom back of the Cherenkov rack (named BCA and BCB)
- Open the pump by rotating in anticlock wise direction the lever n.5. if you are going to completely empty the cherenkovs open the pump (lever in vertical position). To check the pressure value just close the pump (lever in horizontal position) and look at the value on the display.
- When you have reached the pressure value you want (or the Cherenkovs are empty) close lever n.5 (horizontal position)
- Close the red valves on the bottom back of the rack (BCA and BCB)
- Turn off the pump power switch
How to fill Cherenkov counters:
- Open the general T9 Cherenkov (CO2) pump located on the upper part of the rack that you find just in front of the door of the Cherenkov area. On the first line there are four red levers. Open the lever at the right of the line (just above the yellow notice "T9 cherenkov"), by turning it anticlockwise in the vertical position.
- In the C1 and C2 Cherenkov rack, open completely levers n.1 and n.2 (for both cherenkovs) then very slowly open lever n.3 to let gas go into the pump. Do NOT open lever n.3 completely but adjust it always at a small angle with respect to the horizontal.
- Remember to check often the pressure value during the filling operation by closing lever n.3 (horizontal position).
- Once you have reached the pressure value you want close levers n.3, n.2, n.1
- Go back to the general Cherenkov rack and close the main T9 cherenkov lever (horizontal position)