PMT HV Monitoring

For Shifters

This document contains useful information for the shifter monitoring the PMT stability, a description of common anomalies, and a list of expert contacts. This document stands as support to the PMT HV Monitoring ECL form which has to be filled up every hour. Always remember to follow the shifter etiquette: to ask the previous shifters about anomalies or ongoing tests, to read the shifter bulletin, and to revise recent ECL entries.

Contact an Expert

PMT experts can be notified on Slack using the @icarus_pmt_experts tag in Slack or by using the channel #pmt_experts. Furthermore, an expert on-call is always ready to answer any PMT-related questions or issues. Expert contacts can be found here, while to know who is the expert on call, please refer to the shifter page on the ECL.

Standard conditions

Once your shift begins you should find the window below open on the DCS server;

If this is not the case, then you are encouraged to jump to the next section of this document to learn how to bring back the main window or notify an expert for help. The main window gives a general overview of the status of the system; it is divided into two sub-windows, one for the EAST and one for the WEST cryostat. Both should appear similar in look and display similar values. The most relevant parts for the shifter are:
1. Bertan Voltage monitors: Accepted values are within 1995V and 2005 V. Some fluctuations are expected, however, the box frame turns orange and red when the reported values differ too much from the set values. Make an ECL entry with a screenshot and notify an expert in case such an event occurs.
2. Bertan Current monitors: Accepted values are within 55uA and 65 uA. Some fluctuations are expected, however, the box frame turns orange and red when the reported values differ too much from the set values. Make an ECL entry with a screenshot and notify an expert in case such an event occurs.
3. Network: the message should report connected at any time. The window turns pink if some errors occur, for these events, it is important to make an ECL entry with a screenshot and call an expert;
4. Epics server: the message should report running at any time. The window turns pink if some errors occur, for these events, it is important to make an ECL entry with a screenshot and call an expert;
5. VME Crate monitor: the message should report ok at any time. If anything different is displayed, please call an expert. For these events, it is important to make an ECL entry with a screenshot;
6. *"Monitor" buttons: by pushing these buttons it is possible to access more detailed information about the status of individual PMTs. The color of the button is expected to be gray, however, it will turn out to red in case an alarm is on one or more PMTs. Regardless of the color of the button, for now, the shifter is asked to push the button and enter the individual channel monitors and check the status of the individual PMTs.
7. Individual PMTs status: by pushing the Monitor button it is possible to access the overview of the status of all PMTs. The page should look like below:

The monitor page has the following information Channels #, PMT ID #, Nominal Voltage, Voltage Monitored(VMON), Status. Active PMTs will be illuminated with a bright green. PMTs which are OFF will be colored in dim green. The VMON box will be colored in orange if the voltage is between +/- 5 V from VSET, and in red if the voltage is between +/- 20 V from VSet. In either case, post a screenshot on the ECL and notify an expert. The status of an active PMT should be ON. Other possible status messages might appear. Call an expert if a PMT shows one of the following statuses: OverCurrent, Undercurrent, Trip. We have three inactive PMTs showing status message disconnected ch 143 on the west side and ch 253 and 290 on the east side. These can be safely ignored. Other PMTS that are disconnected and grayed out can be ignored.

Navigate the windows

Here are some simple commands and tips to navigate the PMT monitoring

1. If this DCS monitor window appears, just press PMT subsystem.

2. To access the pmt channel monitor just press the Channel Monitor button.

3. To go back to Bertan power supply GUI, click on the back button in the upper-left corner of the GUI window.

For experts

Werther you're are a well-navigated PMT expert or a newbie, these instructions will provide a summary of the most common actions requested to shifters and a fully comprehensive list of documents and reference material to weasel one's way out of most uncomfortable situations. It is important to follow the shifter's etiquette and post extensively on the ECL any action taken and inform all relevant people. The Slack tag @icarus_pmt_expert can be used to notify all PMT experts and Slack channels _#pmt_experts and #icarus-shift-operation can be useful for communication as well.

These instructions are updated to November 2020.

Expert tutorial

A tutorial for PMT experts has been held on Nov. 05th 2020. Relevant documentation is archived on docdb for future reference. The material below might be useful to refresh procedures and as a good starting point for new shifters.

1. Overview of the PMT system (Gianluca Raselli): (SSO link)
2. PMT slow control (Niccolo' Moggi): (SSO link)

[Add other relevant material?]

Ramping up and down voltage on PMTs

Given a situation where all the PMTs are OFF and the Bertan power supply is OFF as well:
1) Make sure all the PMTs are OFF, that they hold their correct set voltage, that Channel interlock shows hv enabled, and set ramp field shows 200V
2) Set 1000 V in the Bertan set Voltage field and press enter. Then switch on the Bertan. The power will ramp up to 1000V. During this operation, the PLC alarm will turn to busy.
3) Once the voltage monitor shows 1000V and the busy alarm turns back to idle, it is possible to turn on all the PMTs using the PMT on/off button located over the channel monitor button. Wait 1-2 minutes for the PMTs to ramp up. The PMT channel status should turn orange during ramping up and turn red and display the error Under voltage, once the ramping up to 1000V is terminated.
4) Now increase the voltage in the Bertan in steps of 100V using the jump to voltage button. Voltage will increase on the PMT channels too.
5) Stop once 2000V is reached. The status of all PMTs should be ON and display no message or alarms.

To ramp down the voltage and turn off the Bertan
1) Ramp down the Bertan in steps of 100V using the Set voltage button until 1000 V is reached.
2) Now turn off the PMTs using the general switch and wait until ramp down is completed.
3) Once all PMTs are off and their status is correctly reported Off, Shiwtch off the Bertan switch and wait until current and voltage ramp down to 0.
4) Restore the general DCS control GUI by pressing the back button at the top left of the Power supplier GUI.

To modify the voltage on an individual PMT:
1) Press on the channel control button to open the PMT control button
2) Set the voltage for your PMT in the Vset box and press ENTER
3) Wait until Ramping up is completed. An error message Overvoltage or Undervoltage might appear at the end of this procedure. Don't forget to inform the shifter and post this action on the ECL.

More detailed instruction and debugging can be found here

Common troubleshooting and FAQs

This page is kept updated with feedbacks from other PMT experts and shifters. Please, share your feedbacks within the pmt experts slack group for improvements.

1. Inactive channels: We have three inactive PMTs: ch 143 on the west side and ch 253 and ch 290 on the east side. The alarm message displayed for those channels is disconnected. This does not mean the slow control does not measure the voltage values for these PMTs, but they are not marked as relevant for the shifters to monitor.

2. Fluctuating voltage: During the past month (December 2020), we have been observed voltage fluctuations on many PMTs. Now this problem is in large part solved, but only PMT 224 results still fluctuating in voltage. These fluctuations are sometimes up to +/- 20V from its set voltage. For any new oscillating PMT, an expert should monitor said PMT and lower the voltage to 1100V in case the oscillations frequently surpass +/- 20V from the set voltage (frame box turns red when this happens). The frequency of the fluctuations can be controlled on the EPICS webpage of the OM. Sporadic oscillations can be ignored, but frequent and large oscillations should be addressed.

3 Trip and overcurrent alarms PMTs who tripped or show the overcurrent alarms should be brought back to 1100V and inspected on the scope.

4 Server down: The server label will be disconnected and the box will turn pink. This means that the server that provides communication with Epics is down. Easy solution: restart the Epics IOC by pressing the "IOC restart" button.

5 Problem: lost network connection. The network label will be disconnected and the box will turn pink. When this happens, all communications with the distributor are lost and the monitor will not update, but the PMTs are (likely) ok. To issue a reset command, open the expert control panel (button on top right of the standard shifter interface) and press the "Reset" button on the right of the one "Network" box that is "disconnected". Allow some time for the reset to complete.

6 Re-open CSS-Studio with the PMT GUI: if the CSS studio window where the HV monitoring is located is closed, one can simpy type `csspmt` in a fresh terminal on the DCS machine to recover it.

7 Impossible to connect to the DCS server: this might happen, but it is not strictly related to the PMT subsystem. If you're informed of this problem by the shifter or happens to yourself it is probably necessary to report to the shift experts on-call or @icarus_shift_expert on Slack.

8 Irresponsive GUI or command line controls: a full list of command lines to be used in case the PMT GUI becomes irresponsive. For this, you must connect to the `icarus-dcs01` machine. If outside the Fermilab network you must first ssh to the gateway as the `icarusdcs` user. for example:

ssh -K

ssh icarus-dcs01

A list of the most important command lines to control and find information about the PMT system can be found here

Legacy expert information

Login ssh -KL 
Login through browser  https://localhost:5443

There are also icons/scripts for the other monitoring tools in the SBN_CR package on GitHub. Right now these are available from the feature branch fb-pmtmon (
1. On-off Switch : An ON switch points to the sign ON and it is colored in bright green. An OFF switch points to off and it is colored in dark green. The switch should be ON, please call an expert if this is not the case.
3. Voltage Monitor : Voltage values within the blue box (Voltage meter) should be (2000+/- 10) Volt. If the value recorded is 50 V more or less than VSet, then the box frame will turn orange. If it is 100 V more or less than VSet, the box will turn red. In either case, post a screenshot of the GUI on the ECL and send an email to or and .
4. Current Monitor : The expected value for 180 PMTs powered up should be between 60 mA. If the value recorded is within +/-10 mA around the nominal value, then the box frame will turn orange. If it is +/- 20 mA around the nominal, the box will turn red. In either case please notify an expert
5. The PLC text box shows the status of the plc that controls the power supply. It is usually in idle except when the plc is working to ramp up/down the voltage: during this timelapse, it shows busy: wait! (over yellow background) to indicate that no other operation should be done before it returns to the idle state. Should it not go back into idle after about 10 minutes, call an expert.
6. The Channel Interlock text box shows HV enabled. This tells the power supply is on and distributing voltage. For experts when the channel interlock is HV enabled you may turn on the power supply. If it shows HV inhibited (red frame) this means that one or more HV channel is on and the Bertan primary power supply cannot be turned on. Actions: 1) turn off the Bertan power supply; 2) turn off all channels in the HV Distributor panel; 3) finally turn on the Bertan primary power supply.
8. Do NOT Click on the Jump to Set Voltage option (for Experts Only)
9. Channel monitor button: click on this button to open the HV distributor monitoring ( to monitor status for each PMT tube ).If during you see this button colored red please notify an expert.
10. Network: should be "Connected". If the SY1527 distributor becomes not reachable anymore over the network, the text will change to disconnected and framed red. Please email to an expert and to . While the network is disconnected the GUI will not be updated but if there are no other problems the pmt will continue to be powered.
11. Server : should be "running". If the SY1527 server crashes, the text changes to down and the channels monitor will not update anymore. How to react: 1) ask an expert if available during his daytime, or 2) try press the "IOC restart" button: the GUI will show 'disconnected' for about one minute and then should be back. If there is any problem send an email to
12. HV Configuration Files: to be used by experts for calibrations. The file selector allows to pick a file with the voltage configuration; the Load button will move this file into the Epics SY1527/db folder so that the IOC will read it at first restart. This is for experts only
13. PMT Digitizer: the "Crate Monitor" button will open the VME_monitor panel where all the internal voltages of the digitizer vme crates are shown. If any of such values is different than nominal value the button will become red and the text box will go into alarm!: please call an expert._