Circuit and trigger

Circuits for SSD

For the standard Si detectors, we use

  • Preamplifiers (Physikalishe Nachweisgerate CATSA/Clear pulse 528A)
  • Main amplifiers (Phys. Nach. MA8000/ORTEC 572)
  • Fast Amp. or TFA (Clear pulse 16ch Fast amp. 4056, ORTEC 474)
  • CFD (ORTEC 935)
  • ADC/TDC(LeCroy or SILENA 3351/3371, CAEN 775/785).

About 100 channels are available.


Preamplifier (CATSA)

  • Maximum energy...200 MeV (3V)
  • Time constant...10us
  • C=1000pF
  • R_load=200M Ohm (common bias for 16 strips, effectively 12.5 MOhm)

Preamplifier (528A)

  • Time constant...2 - 10 micro-s (customized)
  • R_load=2 to 10M Ohm

Main Amplifier (MA8000)

  • Gain x 100 (1-10 or 10-100)
  • Shaping time...1us

Circuits for PPAC

The following circuits are used for the PPACs.

  • ORTEC 8ch Fast Amp
  • Linear fan in/out
  • Philips 5-ch CFD

The anode signal is charge-inverted and used as the trigger. The position of the beam can be determined by the timing of the cathode signals (X1, X2, Y1, Y2), measured by the TDC.


The triggers we can use in the standard circuits are:

  • F1 PPAC
  • F2 PPAC
  • F2 SSD
  • F3 PPAC A or B (called "beam")
  • SSD OR [OR of arbitrary channels of Si and other detectors]
  • (beam) AND (SSD OR) [PPAC-SSD coincidence]
  • beam/n [downscaled beam]
  • (beam/n) OR (beam AND SSD OR)


  • What is the trigger for your measurement?