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G0 HV Users Guide

G0 Detector High Voltage Control

Users' Guide and Shift Crew Tutorial

V. Papavassiliou (pvs@nmsu.edu) and Aamer Rauf (aamer@jlab.org)

Version 1.0

October 23, 2002

This document  contains the instructions for the shift crew on how to run the software that controls the high voltage for the G0 detector during the 2002-2003 run. The program should only be run by shift people in the manner described here. This will minimize the risk of interference due to multiple instances of the program running simultaneously on different displays by different persons. High-voltage experts, defined as anyone having a legitimate need to have access to the high-voltage controls in a different way, from a different  console or remotely, or to change the software, should consult the Experts' Guide for High Voltage Control and take responsibility for avoiding interference with normal shift operations. Questions and comments should be addressed to the authors, at the e-mail addressess shown above.

Starting the HV Control Program

The program must be run only directly (not through a remote connection) on the console of the cdaqh1 HP workstation in the Hall C control room, situated on the right side of the main control panel. It should be started from the "G0 General Tools" window, which should always be present on this console, since it contains a useful summary of the slow controls. If it is not present, it can be started by choosing the appropriate item on the desktop menu, available by clicking the left mouse button anywhere on the screen background, outside any windows. The menu for starting the HV program is available by pressing the button at the bottom right of the screen, labelled HV GUI.
G0 General Tools screen
Selecting the HV menu item initiates a remote connection to cdaqs2 using secure shell with a key. No password is needed by the user. It will check whether the program is already running and will not start a second instance, returning instead an error message. If the program is not running, the message "Starting" will be displayed and the main screen of the HV program should appear in a few seconds, depending on network and CPU loads.

Main Screen of the HV Program

The main screen of the HV program shows two histograms. The top one displays the HV values in Volts for all 512 photomultiplier tube channels and the bottom one the currents in nAmps (log scale). The eight groups (octants) are distinguished by different colors.
HV main screen
The groups 31-38 correspond to octants 1-8. This numbering convention has been chosen to avoid overlap with EPICS names used by other systems at Jefferson Lab. The channels within a group are numbered 0-63; so the notation hv_31_57 above refers to the 58th channel of the 1st octant. The actual name of a channel, which describes its exact position (front/back, left/right, and detector number) can be found from the "Group" display screen; for reference, the names are also given in the Appendix.

The HV OFF button provides a quick way to turn all the high voltages off. It is meant to be used only in an emergency.

The Silence/Unsilence button is used to turn off/on the audible alarm that signals a channel trip. It only applies to the current alarms; a new trip will always produce a beep even if the Silence button has been previously pressed. Of course hearing the sound requires that the audio capabilities of the workstation have not been suppressed. Always make sure you can hear the sound before relying on it.

Group Displays

The Group button of the main screen produces a menu from which one can select an octant to display and control. This results in the display below.
Octant display
The names of the channels are an abbreviated form of the official G0 naming scheme and are self-explanatory. The first number refers to octant (1-8), the second to detector number (01-16), the first letter signifies Front/Back and the second Left/Right.
The Vmon and Imon columns display the current values of voltage and current, the same that appear on the main screen. Values appearing in receded fields can be edited. Normally, the only values that the shift crew may ever have to modify are the set high voltages, in the Vset column. If you do change a value, by typing a new number over it, make sure to hit return, and watch the return value (Vmon) to make sure the change took effect.
The buttons in the second column, next to the channel names, can be used to turn a single channel off or on. They are green when the corresponding channels are on.

Saving a Configuration to a Backup File

To make a backup of the current high voltage (and everything else) setting, click on the File button on the top of the main screen and select Backup... This will produce the following menu.
Backup dialog
The filename for the backup file is formed using the date and time of the backup. You can add a comment. You can also select a different filename by clicking on File on this window and choosing Select Backup File ... which will give you a window, either to select (and overwrite) an existing file, or type a new filename in the appropriate field.
Chose a file for backing up configuration
Unless you have a good reason, leave the extension as .hvc (high voltage configuration) so that it shows up automatically when someone attempts to restore a saved configuration. Push the "Perform Backup" button when you are satisfied.
Note that the configuration files are text files that can be created or edited by hand. The shift crew should not normally ever have to that.

Restoring a Configuration from Backup

To restore, also choose File and then Restore... on the main screen. This produces the following window.
Restore dialog
Clicking on File and then Select Restore File ... produces a similar window as when doing a backup from which you can select an existing configuration file to load. You can select from the list, or type in a name.
Select restore file
The default name is defaultg0.hvc, which should be a link to the latest high voltage values set by the experts. Click on OK after the proper filename has been selected and then, after verifying that the right name has appeared there, click "Perform Restore" on the Restore screen.
Restore default configuration

History

The earliest known (to the authors) version of this program, written in the Tcl/tk language, appeared almost a decade ago when it was used for the slow controls of a cryogenic target. In its current form it has been used for many years in Hall C for high-voltage control. It is produced automatically by a PERL script that reads a configuration file (.hvc) of the same format as the backup files above. The program should never, under any circumstances, be modified by hand. Any such modifications will be lost the next time the program is automatically recreated. Instructions on recreating the program for any reason, typically because the detector configuration (number of channels, not voltage values) has changed, can be found in the Experts' Guide.

Appendix: Channel Order and Numbering

The following table shows the correspondence between channel number and name. Note that the actual name also includes the octant number. For example, 16-BR is in fact N-16-BR, where N=1-8.

Channel Number
 Phototube Name
 Channel Number
 Phototube Name
 Channel Number
 Phototube Name
 Channel Number
 Phototube Name
0
 01-FR
 16
 01-BR
 32
 01-FL
 48
 01-BL
1
 02-FR
 17
 02-BR
 33
 02-FL
 49
 02-BL
2
 03-FR
 18
 03-BR
 34
 03-FL
 50
 03-BL
3
 04-FR
 19
 04-BR
 35
 04-FL
 51
 04-BL
4
 05-FR
 20
 05-BR
 36
 05-FL
 52
 05-BL
5
 06-FR
 21
 06-BR
 37
 06-FL
 53
 06-BL
6
 07-FR
 22
 07-BR
 38
 07-FL
 54
 07-BL
7
 08-FR
 23
 08-BR
 39
 08-FL
 55
 08-BL
8
 09-FR
 24
 09-BR
 40
 09-FL
 56
 09-BL
9
 10-FR
 25
 10-BR
 41
 10-FL
 57
 10-BL
10
 11-FR
 26
 11-BR
 42
 11-FL
 58
 11-BL
11
 12-FR
 27
 12-BR
 43
 12-FL
 59
 12-BL
12
 13-FR
 28
 13-BR
 44
 13-FL
 60
 13-BL
13
 14-FR
 29
 14-BR
 45
 14-FL
 61
 14-BL
14
 15-FR
 30
 15-BR
 46
 15-FL
 62
 15-BL
15
 16-FR
 31
 16-BR
 47
 16-FL
 63
 16-BL