Instructions for the Luminosity HV

When the solenoid magnet is ON the gain of the PMTs is affected. Therefore one has to change the HV to 100% of the maximum value on the Luminosity HV screen. There is no effect by the Toroid magnet.

When the solenoid is OFF the gain of the PMTs is increased. To reduce damage done by HV supplies in operating over the optimum voltage value, the HV should be set to 70% of the maximum value.

During a store, the HV of the luminosity counters will be at the normal 100% value, but while we are out of a store the HV will be ramped down to 70%. The effect of this is that if there is beam, but we are not in a store, the luminosity we will report will be approximately half.

If a channel trips then try to reset it. If one or more HV channels trip repeatedly (3 or more times), and the cause does not appear to be related to intense beam losses, contact Brendan Casey or Rich Partridge - see General Personnel Call Lists in Control Room. Record any and all trips in the Online Logbook.

Setting voltage for all PMTs at once

If the high voltage is already on click on the top of the HV screen on the Set HV button and by holding on it drag to the desired value (in % relative of the max).

DO NOT turn OFF HV without ramping down to zero first. There is no STANDBY on Luminosity System.

Ramping all PMTs at once

Click on the bottom of the panel on the Ramp button. Observe how voltages change. If there are trips or it fails the first time check if voltage was selected properly. First click on Reset on the top of the panel then try to Ramp once again. If the problem remains then contact Luminosity Experts (see below). If individual channels trip then see the next section below

Paused: If the HV value gets paused during ramping then click on the channel under Status column and pick Ramping

Locked: To change the HV if everything is locked simply click on unlock button on the bottom of the GUI

Frozen: If the channel is oscillating or stops ramping above a certain value try to restart the luminosity HV GUI (see below). If problem remains contact Experts.

If the Luminosity HV panel dies/freezes (click on Quit then) or was accidentally closed then to start it again follow these steps. From d0lum xterm window type:

cd /home/d0lum/operations/config/

./show_hv &

Click on the top of the screen to ON HV on PMTs on. Then follow instructions above on how to select voltages.