CDC Hit Generation

CDC Hits from CDCDigi Hits

• the code that converts raw hits from the fADC125s of the CDC into actual CDC Hits is done in several steps:
  • the code DCDCHit_factory_Calib.cc takes the raw CDCDigiHits and create CDCHits based on the raw information. In this process the pedestal is subtracted from the signal peak amplitude and the integral and in addition the amplitude is converted into an energy based on calibration data. A code snipet of this procedure is shown here:
    double amp = amp_a_scale*gain*double(maxamp);
  • In the following pictures the top row of 3 histograms shows the signal amplitude in ADC counts vs drift-time converted to ns (but not corrected for timing offsets) as reported by the FPGA of the fADC125. The left most graph shows the hits of channels in the same preamp crard if the total number of the hits in that card surpasses 14 hits. The middle one is the same for preamp hit multiplicity 10 to 14 while the right most shows hits from preamp carts with hits less than 10. The raw data is taken from DCDCDigiHit objects generated from DCDCPulse objects. The 2d histogram in the bottom row on the left is the signal amplitude vs drift time again, however these data were taken from the DCDCHit objects where a scale factor and gain correction is applied to the signal amplitude. That move the t0 peak close to 0 drift time.

Example Run 120594 without(left) and with(right) cut at 180 for raw adc signal peak

Example Run 72780 without(left) and with(right) cut at 180 for raw adc signal peak

Example Run 72840 without(left) and with(right) cut at 180 for raw adc signal peak