ROUTINE use of the PHOTON TV.

     The photon beam passed through an scintillator screen which is
     viewed (through a mirror on the beamline) by an image
     intensified camera.

     If the system has been set up it is usually only necessary to

     1) Check that the INTENSIFIER GAIN is at minimum (1) and that the
        VIDEO GAIN is at 3.

     2) Check the tv monitor is on and the brightness and contrast are
         high enough to see a 'raster'.

     3) Check that the FRAMESTORE is set up to average a reasonable number
        (16 for example) of frames and is NOT FROZEN - see below.

     4) Turn on the camera at the control box and wait about 7 seconds. Then
        slowly increase the INTENSIFIER GAIN.  Check that what you see
        on the monitor is sensible. IF NOT SWITCH CAMERA OFF IMMEDIATELY.

     5) If you increase the intesifier gain too much the camera will
        trip off. Decrease the intensifier gain to zero and push reset
        (on the smaller box).
        The camera should come on again after about 7 seconds.

     6) SWITCH OFF if not needed for more than a few minutes.
 

     The (Oggitronics) FRAMESTORE.

       1) If necessary switch on the framestore. The switch is at the
           back underneath the mains plug.
          The unit  goes through it's own setup procedure in about
          3 seconds ending with 'READY' on the touch panel display.

       2) Push the 'AVERAGE' button once to get 'NORMAL'. The 'FREEZE' button
          light MUST BE OFF; if it's ON push 'FREEZE' once.

       3) You can perform various functions with the framestore - see manual,
           but the useful ones are the 'recursive' averaging and the 'jumping'
           averaging. To get these push 'AVERAGE' 3 or 4 times respectively.
           The number of frames averaged over can be changed using 'ENTER' to
           increase and '-' to decrease (factor of 2 per push, max is 256).
           To get back to 'NORMAL' push 'AVERAGE' 2 or 1 times more.

           The 'jumping' average is recommended so that you can see something
           changing. Be patient - remember 256 frames is about 10 seconds, and
           the screen may show nonsense until the first average is done.

       4) WARNING. It is possible to inadvertently push the 'FREEZE' button.
            The framestore then displays the same frame for ever. It is
            dangerous to turn on the camera in this state.
 

      SWITCHING ON FOR TEST WITHOUT BEAM.

      1) Check the FRAMESTORE is on and correctly set up (see above)

      2) Check the video gain is at 3 and the intensifier gain zero.

      3) Check the tv monitor is on and the brightness and contrast are
         high enough to see a 'raster'.

      4) WHILE WATCHING THE TV MONITOR turn on the camera and slowly
         increase the intensifier gain. You should see many flashing
         white dots like 'snow'. IF NOT and especially if
         the screen goes white turn the camera off by pushing the switch once
         more. OVEREXPOSURE TO LIGHT WILL DAMAGE THE CAMERA and shorten it's
         life so ALWAYS TURN OFF when 'thinking' etc.

      5) CHECK that the power supply for the light is switched to 'V',
         that the coarse control is at minimum (fully anticlockwise)
         and the AMPS knob is at the point marked.Turn on and adjust the
         'fine' control until you can see 'snowy' crosswires.
         DO NOT EXCEED 6 volts. You should see it at 1-2 volts.
 
 

     WARNINGS

     According to the manufacturer the camera can be expected to run for
     at least 15000 hours AT LOW LIGHT LEVELS. The biggest danger comes from
     operating at higher levels - even ROOM lighting will reduce the camera
     life. Too bright a beam spot for a long time could also cause local
     damage.

     The following precautions are therefore necessary:
 
     1) DON'T turn the camera on without having CHECKING THE FRAMESTORE
        is set uo correctly AND NOT FROZEN, and that the tv monitor is
        working.

     2) Always turn the INTENSIFIER GAIN control to minimum (1) before turning
     the camera  on.

     3) Increase the INTENSIFIER GAIN slowly checking whats happening on the
     monitor.
     If the monitor shows anything other than what you expect, turn off
     immediately.

     4) Switch camera off if INCREASING the electron beam current, or if
        not needed for more than a few minutes.

     5) Check that the camera is OFF at the CONTROL BOX in the counting room
     BEFORE attempting to do anything to the camera (EXPERTS ONLY!) or
     the mirror box. To be doubly sure unplug the power cable FROM THE
     SMALL BOX at the camera.
 
 

JCM 18/1/02.