Turn FDC ON

Procedure for turning OFF the FDC

1. Find the FDC HV & LV control window, or start a new one following the instructions here.
2. Turn off all the positive HV: left click on the "ALL HV" icon and chose "FDC: Turn OFF ALL HV+ Channels".
3. Turn off all the negative HV: left click on the "ALL HV" icon and chose "FDC: Turn OFF ALL HV- Channels".
4. Do NOT turn off the LV, unless instructed by the expert in which case do left click on the "ALL LV" icon and chose "FDC: Turn OFF LV Channels"

Standard procedure for turning ON the FDC

1. Find the FDC HV & LV control window, or start a new one following the instructions here.
2. Turn on all the LV channels (if they are not on yet): left click on the "ALL LV" icon and chose "FDC: Turn ON LV Channels".
3. Turn on all the negative HV: left click on the "ALL HV" icon and chose "FDC: Turn ON ALL HV- Channels". Wait till all "HV-" buttons are green. In case some of the HV- channels trip, click twice on the corresponding HV- button, once to a acknowledge the trip and second to turn on HV again. If this still doesn't work follow the "Individual HV channel setting" procedure below.
4. Turn on all the positive HV: left click on the "ALL HV" icon and chose "FDC: Turn ON ALL HV+ Channels". Wait till all "HV+" buttons are green. In case some of the HV+ channels trip, click twice on the corresponding HV- button, once to a acknowledge the trip and after you see the "ON" label click second time to turn on HV again. If this still doesn't work follow the "Individual HV channel setting" procedure below.
5. In case, after trying the above procedures, there are still channels with high (above the trip value) current, call the expert.

Special procedure for turning ON the FDC after beam alignment

This is a procedure to be followed when the photon beam has been aligned and we want to apply HV on the chambers. There is no need to follow this procedure once the beam has been established and the HV settings adjusted in which case use the "Standard procedure for turning on the FDC".

1. Find the FDC HV & LV control window, or start a new one following the instructions here.
2. Turn on all the LV channels (if they are not on yet): left click on the "ALL LV" icon and chose "FDC: Turn ON LV Channels".
3. Turn on all the negative HV: left click on the "ALL HV" icon and chose "FDC: Turn ON ALL HV- Channels". Wait till all "HV-" buttons are green. In case some of the HV- channels trip, click twice on the corresponding HV- button, once to a acknowledge the trip and second to turn on HV again. If this still doesn't work follow the "Individual HV channel setting" procedure below.
4. For each package at the left panel, FDC1 ... FDC4, and each cell within the package, Cell 1 ... Cell 6, do the following one cell at a time, starting from (FDC 1,cell 1):
   • Click on the first and fourth (outer) positive HV+ sectors and wait till the buttons are green which may take several minutes. Monitor the currents on the corresponding channels: the bottom histogram. If the currents exceed the trip level the channel will trip. If this is the case, click on the corresponding HV+ channels twice, once to a acknowledge the trip and second to turn on HV again. If this still doesn't work follow the "Individual HV channel setting" procedure below.
   • Do the same for the two inner positive HV sectors of the same cell, second and third HV+ buttons.
5. In case, after trying the above procedures, there are still channels with high (above the trip value) current, call the expert.
6. If the reason for the high currents is the beam alignment, before working on the beam, turn off all the HV channels following the procedure described above. After the beam is re-aligned follow the same procedure.

Individual HV channel setting

If you want to turn on an individual channel that by some reasons, like current trip, has not been turned on using the above procedure, first just click on the "ON" button for the corresponding channel in the main HV window. If the channel still trips, follow the procedure below:

1. On the FDC HV control window, do left click on the corresponding package (FDC1,..., FDC4) and chose "Show HV+ Channels" or "Show HV- Channels" depending on the polarity of the channel you want to set.
2. On the new window find the corresponding channel line, all the operations that will follow should be done only for that channel.
3. If there was a trip, click once on the "ON/OFF" button to acknowledge it.
4. In the "Voltage Setpoint" column, record the current value, to be called here "target voltage".
5. Set the "Voltage Setpoint" to +1200V (or -300V for the negative HV channels) and hit "Enter". You should see the same value in the "Voltage Setpoint Readback" column (if that is not the case, most likely the IOC has to be rebooted: for further instructions go to the "Controls" section in the main document).
6. Press the "ON" button, the HV should start ramping up. After it reaches the set value, wait 5 minutes, then add 200V to the set voltage (don't forget to hit "Enter").
7. Repeat the above line till you reach the "target voltage". In case of trips you may reduce the voltage step from 200V to 100V or 50V, especially for voltages above 1900V.
8. If the above procedure doesn't work, call the expert.