| How to switch on the electron detector ? |
- Turning the system on
The detector system needs to be powered. In hall A there is an
electrical box called A-UH-B1 left of the stairs going to the tunnel (see map below).
In this box, the main power switch for the electron detector is number 21 (it says electron
detector on it). It must be on turned ON. In the tunnel,
there is a crate attached to the wall above the electron detector, it also needs to be turned ON.
When it is ON a red LED is lit (at the right end of the crate). Below this crate there is a black electrical
box controlling the displacement system. On the left side of this box it should say "Idle".
|
|
|
Slow control of the electron detector
To perform operations on the electron detector. Open the MISC... screen from the main Polarimeter EPICS screen
and then choose "Electron Detector". On this screen, active buttons appear in blue
and readback values appear on a yellow background. This screen is also reachable, by loading the file ComptonElectron.adl located
under the home directory of hacuser on the hac computer.
|
To use the electron detector a high voltage
(80 V) must be applied to polarize the silicon
microstrips and a low voltage must be provided to the preamplifier
circuit board and some threshold must be set for each plane for
the detection of the signals. To do this execute the following operations :
- Turn the low voltage ON
- Turn the high voltage ON. The return value should increase gently to 80.
- Set thresholds to 35. The return value should read 35.
- Turn calibration OFF.
The electron detector can be put in data
taking position remotely. When the detector is inserted the chicane must be ON,
when it is being moved the beam must be OFF too. If it is not the case the detector will eventually be destroyed.
- Click on either "garage" or "beam" depending on where you want to put the detector.
- To make sure the detector is where you want watch the detector move on the TV screen (there is one
in tha Hall A counting house and one in the back room). The switches readback must oscillate a
little bit if the system is running properly.
|
|
|
|
|
