HV Control

HV Control Document

This document describes the HV Control interface.

/online/config/fpd/hv/fpd.hv & (you need to be on node d0ol49 logged in as d0fpd to have control.

This will open the HV gui from which we can control the voltage to the L0 PMTs, the MAPMTs and the Veto Counters.

At the top are two tabs: Trigger and MAPMT. By choosing a tab you control those tubes to which you will be giving the voltage. Trigger is for L0 and Veto tubes, MAPMT is for the detector planes.

Trigger Tab: We can only control L0 at the castle level so when we turn these on, we are supplying HV to all L0 tubes in the castle (up to 4 tubes). These are PMTDI (both D1 and D2), PMTA1 (A1 castle), PMTA2 (A2 castle), PMTP1 (P1 castle), PMTP2 (P2 castle) and 2 spares. This will provide the same voltage to all L0 PMTs at that location. We can also control the North and South veto counters. VetoN controls the North counters (P side) and VetoS controls the South counters (A side).

MAPMT Tab: We can control each location of the MAPMTs separately so we have MAP1U, MAP1D, MAP2I, MAP2O and similar for P2, A1 and A2 as well as MADI1 and MADI2. This will provide the same voltage to all 7 MAPMTs at that location.

On the right of the list is the state control button. When the program is first turned on, this should be off (blue) for all tubes.

Go to the Trigger tab first. (DO NOT turn on any MAPMTs until you have verified rates from the L0 tubes)

Choose which L0 tubes you want to turn on by clicking on the state button. This will give you a drop down list from which you select on. This should turn the button orange.

Next set the voltage to which you want to go. Then turn the tubes as close to operating voltage as you can. Rates at home will increase by ~50% when the pots are in operating position. Voltage can be turned on in two ways:

Click on Set HV at the very top. This will open a drop down menu from which you can select a percentage value of the maximum allowed voltage (100% is the standard operating voltage for each channel). All channels that you have turned on will be set to this value. You can see the actual voltage by looking in the V_Set column. (There is also a standby voltage setting that is set to 0%. We use this when the tubes are in the home position between stores.)

You can also set a different voltage for each channel. To do this, click on the V_Set box for the channel of interest and type in the value of the voltage you want (this should be a negative value with magnitude less than or equal to 2000V for L0 and 1000V for MAPMTs). Hit enter for the value to be accepted.

When the voltages are set, click on the ramp button at the bottom. This will ramp the voltages on the tubes up to the desired level at 50V / second. The control button will turn yellow and read average or ramp then it will turn green and be labeled holding when the desired voltage is reached. If too much current or too much voltage is being drawn, the button will turn red. If this happens you press the reset button, this will take the voltage back down to zero. This probably means there is something wrong with the tube in that location.

Verify that the number of tubes you expect to be drawing current is actually the case by looking at I_Read. Each tube in that channel should draw the about the same amount of current (this will increase with increased voltage). Compare with other channels with the same number of tubes that you have turned on. If you notice a discrepancy (i.e. one of the channels is not drawing as much current as another channel with the same number of tubes at the same voltage) there is a problem in that location. You can look at the signals from that location to determine which tube it is. The rough expected currents for the current configuration are on operating values page:
When the tubes are operating at the desired voltage, press the control button and choose locked from the drop down menu. This will prevent the voltage from being accidentally changed.

Verify the rates from the L0 tubes, it should not exceed ~350kHz for the singles rates as shown in the hardware scalers. If safe, you can now repeat this procedure for the MAPMTs you want to turn on. Do not turn on any MAPMTs until you have verified the rate from its associated L0 tube.

When finished collecting data, and pots are in home position, you can follow a similar procedure to turn off the voltage by setting it to standby. Unlock the tubes, choose the voltage and select ramp.

To change the epics database for our HV system requires a few steps.

Edit the channels to be changed. They are named: FPD_HVC_xxx where xxx is the channel of interest. For MAPMTs the format is MAyyy where yyy is the castle arm (ie A1I, P1D etc.). For L0 the format is PMTyy where yy is the castle name (A1, A2, DI, P1, P2 and SPARE). Finally we have VETON and VETOS. The values that will likely be edited are $(oc) for the current trip, $(ov) for overvoltage and $(uv) for undervoltage. The ov and uv values are set at +20 and -20 of the voltage limit which is 2000V for L0 tubes and 1000V for MAPMTs.

After all channels have been edited, contact Vladimir Sirotenko (sirotenko@fnal.gov) (x4802) to update the epics.db file located at /online/ioc/ppc/mv2300/d0olctl45 or /online/ioc/mv2300/d0olctl33

After he has updated this file, look at it and make sure the changes have been properly reflected.

The fpd.hv and fpd.hvc files in /online/config/fpd/hv need to be modified to reflect changes using the d0run account. From d0ol49 you can use d0ssh -l d0run d0ol49. The only thing that will actually change is the tabs and standby values.

If they are not using the HV then notify Vladimir that he can reset the crate after ramping our HV to 0 and turning off tubes.

If nothing has been changed and HV is not running correctly (wrong limits) after issuing an /online/config/fpd/hv/fpd.hv (for instance after a power outage) you can reinitialize the crate with the command $ONL_APPS_DIR/src/hv/HvCurrSet.py /online/config/fpd/hv/fpd.hvc. Then try running the HVCGui again.

If you have any questions or comments, please mail me at: strang@fnal.gov

This page last updated: 08-Jul-2004 12:09 PM (GMT -06:00)