Last Updated on Monday, March 31, 2003 at 14:59:26. by Author: Edmundo

Trigger Monitoring, Expert

(General)

Contents

• Changing the high voltage of Paddles and Cerenkov counters
• Changing the high voltage of ZDC
• Turning off the high voltage of ZDC
• Lumiscalar page on RHIC X-term
• Beam Synch page on RHIC X-term
• Phobos Triggers page on RHIC X-term
• zcal page on RHIC X-term
• zcal HV (pet) page on RHIC X-Term

Changing the high voltage Paddles and Cerenkov Counters

    -The high voltage is controlled using the high voltage control VI on the Plastic HV & Camac Controls computer. (The operator's manual is on         the desktop with a help button on the VI front panel.)
    - High voltage to the mainframe should always be on.
    - All active Trigger channels need to be enabled, showing green in the status field.
    - If any channels are disabled, determine why by looking at the status field and make a note in the logbook.
    - If an alarm occurs, call Erik at 1036 or at beeper number 7604. Also, inform Edmundo, and note the alarm in the logbook.
    -Turn off the alarm by clicking the alarm button.

Changing the high voltage ZDC

   -Ensure "zcal" and "HV" (zcalHV) are both open (click on right mouse button to get pull down menu)
   -In zcal window, click on PHOBOS menu and select "open window" (only option)
   -In new "PHOBOS" window, click on HV menu and select "voltages" (only option)
   -In new "zcal HV little popup" click on "load file" button, select one of the files (call expert):
     biraHvps.default.jun99.calXXX
   where  XXX is a calibration number , then click ok. After few moments check original HV window, if ok close new windows.Write in logbook this  proceedure.

Turning Off the high voltage ZDC

-Go to RHIC X-terminal, look for the "HV"window, If you don's see one, look for the high voltage icon, "HV" in the gray "icons" window on the right. Double click on it to open the window. If you don't see either, click the right mouse button on a black area of the screen and choose "ZCAL HV(pet)". option from the menu that appears.

       -Click on the ZDC HV current status, select from the menu Stand By, repeat for all the modules

       -Select form the main menu Data and then "Send all"

       -You will observe that the actual voltage of the tubes will go down to around zero (+- 20 V offet)

Lumiscalar page on RHIC X-term

Beam Synch page on RHIC X-term

Phobos Triggers page on RHIC X-term

This shows the scalar information we are currently sending RHIC as a function of time. The legend describes each line. 

zcal page on RHIC X-term

This RHIC interface is a diagnostic tool for the ZDC. When this window is openedm

zcal HV (pet) page on RHIC X-Term

This window provides information on the HV state of the tubes for the ZDC. to open this window:

• Go to the"RHIC Interface X-Term" look for an open "HV" window. If you don's see one, look for the high voltage icon, "HV" in the gray "icons" window on the right. Double click on it to open the window. If you don't see either, click the right mouse button on a black area of the screen and choose "ZCAL HV(pet)". option from the menu that appears.

Observing the synchronization of the crossing clock

The beams are synchronized when ZP, ZN, and CC (blue) are aligned.  ZP*ZN (wide), which passes through several more modules arrives slightly later.  At injection energy, the shift crew will want to observe oscilloscope triggering on channel 1 ( ZP*ZN wide ).  As the beams are cogged, however, it would is useful to trigger on the external signal ( ZP * ZN narrow ).  ZP and ZN currently (7/20/01) fall near the end of coincidence.

Setting and Checking the Crossing clock time

Whenever the beam changes energy, the crossing clock needs to be changed correspondingly.  If it is not changed, then the triggers involving the crossing clock will not work!  If the beam is stable (i.e. for > 15 minutes) at one of the energies below, then the following procedures should be used to check that the crossing clock is correct and change it if necessary. Before changing, stop the current run, start another run, do the change during this run, and when the change is done wait a couple of minutes, stop the run and start a new one. Note in the runlog of the transition run what was done. Also, note in the general notebook the changes.

There are three different settings for the crossing clock, depending on the energy of the beam.

• Beam injection energy (10.73)
• Beam gamma = 30
• Beam gamma = 70

The settings of the cc (crossing clock) should be changed only when there is a beam is stable (5 minutes) at one of the above gamma. The gamma of the beam is displayed in the RHIC commissioning monitor (forth row blue and yellow respectively).

To change the settings of the crossing clock go to the RHIC interface Xterm. Open the window Beam Sync Blue (pet) and the yellow Beam Sync Blue (pet). They window looks like this (yellow with yellow line):

To change the settings click in the corresponding box write the number and hit return;

The settings for gamma at injection (10.25)  are for the:

1. position delay = blue: 191,  yellow: 198
2. fine delay = blue: 20,  yellow: 54

The settings for gamma 30:

1. position delay = blue 189,  yellow: 197
2. fine delay = blue: 55,  yellow: 40

The settings for gamma 70:

1. position delay = blue: 189, yellow: 197
2. fine delay = blue: 45,  yellow: 30

The rest of the numbers should remain the same.

To check this time, look at the oscilloscope between the silicon and on line monitors. The upper signal is the PP. The lower signal is the crossing clock. The crossing clock should lay approximately around either of the vertical lines.