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HOW TO CHANGE HV FILES  

Quick HV guide.

updated 11-03-02 by J. Roche

a not so up to date  guide on HV handling
 
 

To start the HV :

  • Turn on the crates : in the cage for each crate, turn the key on the front panel to the left (the crate display panel should react, the square light should come on). Be carrefull, once you flip the "enable" switch, if one channel is on the HV will start to ramp up. On the front pannel, choose "Modify channel", check that all channel are off. flip "enable" switch to the up position (the led up from the switchshould go on, do not panic if not some time it append). To operate the crate manually, read the CAEN manual left around the crates.
  • Remotely connect to the crates : log on on cdaqs1as cvxwrks ;  cd $EPG0HV/tk ;  hv.tcl (at that point a window called "G0 HV CONTROLS" will pop up, I suggest you extend this window at maximum on the vertical direction)
  • Load the correct HV input file :
  • Click on the "File" word at the top left of the window, choose "Restore" (a new window pops up called CAEN Restore)
  • In the new window, click on the word "File", choose "Select Restore File" ( a new window pops up called File select box)
  • Click on the file you want to restore, click on "OK" to exit the File select box (the name of the file you just select appears at the top left in the window CAEN Restore) 
  • Click on the "Perform Restore" button (A red window pops up, it remind you that the HV values previously on the carte are going to be lost and offering you to save them before restoring new values in the crates.  If  you choose to save the old values, click on "cancel" and proceed to the restore process. If you do not want to save the old values, click "ok")
  • Once the restore is over, to exit the CAEN Restore window, click on "File" and  choose "Quit"
  • At that time, the new values you have loaded are sent to the CAEN crates
  • Turn on HV :
  • Click on "Group" on the top of the G0 HV CONTROLS window (there are 8 crates powering the full Ferris Wheel)
  • Click on the group connected to the octant you want to power (for example on G0 Octant 1 to power octant 1, a new window pops up)
  • In the new window, click on "Group" and choose "HV ON"  (check the status message in the window, also examine the graphical display in window G0 HV CONTROLS). This power all the pmts of this group at once. If you want to power only one pmt, click on the square button at the right of the pmt name.


    • To stop the HV :

  • Turn off HV : click on "HV OFF" button on the bottom of the window G0 HV CONTROLS  (watch HV going down).
  • Turn off crate : in the cage push down the "Enable" switch, trun the key to the right. NEVER DO THAT BEFORE TURNING OFF  ALL CHANNEL HV BY SOFTWARE


    • Tips :

  • The interface is  (very) slow, do not panic if the update of your new values do not appear right away, give it some time. Also the windows freezes when the program thinks...
  • The alarm handler of the system is erratic, please check visually the status of the HV on a regular basis, do not trust the software. If one HV tripped  a bip should start to bug you.
  • Trouble shooting :
  • over voltage  (usually on channel 16 of a given card) : that appears nicely on the graphical display as a peak higher than the other one. In that case turn all group off by software, go and power cycle the given crate, restart and document your observation, actions and produced results. Many over voltage of one card call for a new card.
  • no intensity read back : that is indicated by the lower graphical display of window "G0 HV CONTROLS". usually this indicated a dead base or a loose cable. Turn off the HV, document your observation, be sure the detector expert is informed.
  • if the current drawn by a base at a given time is to high, the card is going to trip. Before being able to restart HV you may have to click in "Command" and then to choose  "Trip reset"
  • under voltage : most usually you are trying to turn on HV remotely but the switch "Enable" is still on the down position. Though it could also be that you ask for an HV that exceed the hardware maximum set on the card. To check the hardware maximum, from the first menu on the crate front panel, choose "crate map". The typical maximum hardware HV, for the G0 experiment, is 2300 V. The default maximum HV for the CAEN crate is 3000V, the maximum as been adjusted down with a small potentio meter located on the back of the cards.
  • Changing HV input to the crate : there are three ways to do that, each of them has its avantage/disavantage :
  • on the front panel of the crate, go to modify channel. Attention the new value you enter that way is not backup unless you go through the back up process of the software interface
  • on the software interface directly : that is very impractical but if you want to do it... open the group you interested by, type the new values in VSet, do not forget to type return TWICE in the box you changed. Again your changes are not back up, up to the point where you go through the back up process of the software interface
  • Change directly the input file that you load to the crate through the software. They are ascii file with extension ".hvc" . They are very easy to read. Go open one look at it, do not be afraid, you will find out how to do the changes by your self. Once your done, load your new file as explained upper in the page. Also read the following for automatic changes.
  • $EPG0HV = /net/cdaqfs/epics/dvlepics/llapp/CaenHV/1-0/G0/

    • PERL scripts to change HV files :

    P. Clore,  07-24-02

    The programs describe in this HOW TO allow one to produce new input files for the hv.tcl program. Using these input files allows to load back a set of HV values to be applied to the tubes. For the g0 experiment there are 512 values in those files. The followings scripts allow you to modify the HV values contains in those input files in an automated way rather than opening by hand  the input files and changing by hand numerous characters.
    Three ways of modifying the HV on the tubes have been identified :
    - changing the gain of all the tubes of one octant such their gains are modified by a common factor
    - changing the gain of some tubes by a specific factor
    - changing the HV applied on the tube by a step in HV (same step for all tube of one octant)

    The perl scripts are installed on cdaqs1 (user account : cvxwrks) under the directory $EPG0HV/tk

    Changes HV of specified octant(s) by  specific gain, given by a factor f (f < or > 1)

    The program prompts for octant number and gain change until "q" is entered for octant number
    The variation of gain as a function of HV is the following :
    - for NA tubes (octants 1,3,5 and 7) : g1/g2=(hv1-750)/(hv2-752)**8
    -for French tubes (octants 2,4,6 and 8) : g1/g2=(hv1/hv2)**8
    Those two different relations reflects two different kind of voltage divider in the bases as well as two different number of dynodes in PMTs.

    The  script (change_gain.pl ) needs two arguments
         filein = file containing actual HV
         fileout= output file

     To run it type : perl  change_HV/change_gain.pl filein fileout

    Changes HV of specified octant(s) by  specific HV step.
     Each PMT is checked with a reference to ensure the final HV does not exceed the reference HV. If the Max HV is exceeded by the request, the HV is set at the maximum and a message is sent to the screen. The program prompts for octant number and HV step until q is entered for octant number.  The  standard current reference file with maximum hardware settings is:  change_HV/max_hv_settings.hvc , it contains the maximum HV set by hardware for each card as read on the crate in July  16th '02. In any case the format of the reference file is  (for each line ) : crate number, channel range, max.hv, and it should follow the following rules :
      -> program ignores comment and blank lines
      -> needs to be a leading space before crate number
      -> at least one space between columns

    The  script needs 3 arguments
         filein = file containing actual HV
         fileout= output file
         fileref= file containing reference HV

     To run it type : perl  change_HV/step_hv.pl filein fileout fileref


    Changes HV of individual PMT's gain  by specific  factor read from a file.

    The file of changes must follow these format specifications :
      -> PMT name must contain capital letters
      -> there should be at least one leading space before PMT name
      -> the program ignores comment lines  and blank lines
      -> if the factor is not > 0, no change will be made to the corresponding PMT and a message is sent to screen
    There is an example of the filechange under the change_HV directory.

    The  changes will only occurs  for the PMTs specified in the file.

    To run it type : perl  change_HV/change_pmt_gain.pl filein fileout filechange
     

    You can also read the following guide for HV slow control :
     http://www.jlab.org/~pvs/writeups/SlowControls/UsersGuide/html/