Forward Calorimeter Shift
Contents
The Forward Calorimeter
The Forward Calorimeter (FCAL) is a 2800 element lead glass detector consisting of 4cm x 4cm x 45cm bars. The light produced in each element is measured using FEU 84-3 PMTs. The PMTs are readout using custom Cockcroft-Walton bases and operate up to 1800 V. The entire detector exists inside an environmentally controlled and light-tight darkroom on the FCAL platform.
Routine operation
A shift taker will need to monitor the environmental and base sensors through a GUI interface. The darkroom is equipped with 4 sensor boxes, each reads the temperature, humidity, and light conditions inside the darkroom. Each of the 2800 bases are equipped with temperature, high voltage, and current sensors. The following instructions are for non-experts during routine operation. Operations beyond what is specified here shall only be performed by the system expert or under his/her direction. If the expert directs an operation outside the ones described here, a specific note must be entered into the log book.
Control and monitoring of the system is accomplished using the Hall D graphical user interfaces (GUI) to EPICS [1] [2]. A description of how to bring up the GUI screens can be found in Section Slow Controls. We briefly describe the use of these interfaces:
Checking the environment
Environmental sensors record temperatures and humidity conditions inside the dark room and in the photomultiplier tube bases. Automatic alarm systems will be in place in the event an environmental or base sensor reads a value above what is considered safe or normal operating conditions. In the case an alarm system is triggered problem areas of the FCAL will flash red and power to the bases will shutoff. A non-expert user will call an expert user and do nothing else. The FCAL Darkroom environmental variables can be viewed using MyaViewer and selecting the group 'HD_FCAL_ROOM'
Voltage control
The bases generate their own high voltage which can be set through the GUI interface. A non-expert user will only be able to do the following from the non-expert shift taker GUI shown in Figure 2:
- Turn on all bases
- Click 'All FCAL HV' and select 'Turn On All Bases'
- Turn off all bases
- Can be done in 2 ways: 1) At the top of the screen there is a red outline area with 'Turn OFF ALL' written, click the 'HV' button to power off all bases, 2) click 'All FCAL HV' and select 'Turn Off All Bases'
- Restore HV setpoints
- Click 'SAVE/RESTORE' and select 'Restore FCAL HV Setpoints'
- Save HV setpoints
- Click 'SAVE/RESTORE' and select 'Save FCAL HV Setpoints'
- Select 25 bases to display in a table
- This is done by first selecting a quadrant, then selecting a particular strand in that quadrant, and finally choosing which quarter of that strand to display
To turn on all the bases and set them with the appropriate HV a shift taker must do the following: 1) Click 'SAVE/RESTORE' and select 'Restore FCAL HV Setpoints'. From the menu select 'file me in' 2) Click 'All FCAL HV' and select 'Turn On All Bases' When the bases have all been powered the 4 large squares behind the 'Quadrant [1-4]' label will all be GREEN. If any square is RED then some bases in that quadrant where not all turned on. In this situation repeat step 2. If the problem persists call an expert.
Interlocks
Power supplies for the bases are interlocked and will be turned off when a) both doors to the dark room are open simultaneously, b) environmental sensors (light, temperature or humidity) in the dark room exceed preset limits or c) there is a loss of power. Should the interlock system trip, an expert should be called to reset the condition. Changes to the interlock settings are only allowed by an expert, or under his/her guidance.
Expert personnel
The individuals responsible for checking that the FCAL is ready to take data and setting its operating parameters are shown in following table. Problems with normal operation of the FCAL should be referred to those individuals and any changes to their settings must be approved by them. Additional experts may be trained by the system owner and their name and date added to this table.
| Name | Number | Date of qualification |
|---|---|---|
| Manuel Lara | (956) 622-8216 |
