Photomultiplier with NaI Scintillators.

In the "classical set-up", we use two PMs with NaI crystal scintillators with their electronic suply from Cyberstar (a local company F38435 Echirolles, 33-4-7640-3591, fax 3926).

They can count up to 1e5 photons/s. Filters can be inserted after the monitor to prevent saturation on the detector. To adjust the count rate in the monitor, it is more satisfactory to adjust its aperture. There is a slit between the diffusing Kapton foil and the monitor where a "calibrated aperture" can be inserted. The macro flux in spec can be used to calculate the ratio between the monitor counts and the beam incoming flux.

Front Pannel from left to right: 
   HV supply (800V< HV < 1150V)
   PEAKING TIME (0.25 microsec) and GAIN (10)
   WINDOW: LOWER and UPPER LIMITS
        n : NORMAL
        in : no UPPER limit
        AS : from LOWER LIMIT With WINDOW = UPPER LIMIT/10
        S : WINDOW centered on the LOWER LIMIT
   RATEMETER 10, 100, 1000, 100000, 1000000cts full range
   integration time from 0.3s to 10s
   
MIND:  --> BAD COUNTING ( check it by the Oscilloscope signal), if:
   * the GAIN is such that AMPLI saturates (<14V);
    in practise, do not exceed 4V in order to well suppress lambda/3
   * there is saturation in the counting;
    if any doubt, check the coherency of acquisition by inserting an
    attenuator or a pin-hole
    
STARTING
   - connect the oscillo to the ampli output
   - put window to IN and LOWER limit to 1.5V
   - adjust HV for 3V signals
   - which scatter?
   - LOWER LIMIT between 0.5 and 1.5V depending of noise acceptable
   ***(RECORD the dark counting)
   - HIGHER LIMIT about 4.5V (check no counts lost)

  Updated by jpsimon on Sept. 14, 1999