Background Rate Studies

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Revision as of 15:29, 15 January 2007 by Mashephe (Talk | contribs) (Simulation Information)

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This page summarizes various studies used to try to understand backgrounds produced in the detector from the 9 GeV coherent brem. beam that enters Hall D.

Simulation Information

A total of 108 9 GeV beam photons were generated using the geometry and simulation current as of January 12. Note that various hit thresholds exist for each detector system. Noise count rates are highly dependent on these thresholds. The 108 beam photons is approximately 1/110 of second of beam time. The raw plots below have therefore been scaled by a factor of 110 in order to plot the hit rate in Hz.

CDC

Detector Configuration:

  • Double-Hit Resolution: 250 ns
  • Threshold: 1 keV
  • Maximum Number of Hits (per Event): 100


The average background rate per straw in Hz as a function of ring number in the CDC.
A double-log plot of the energy of all hits in the CDC. The spectrum cuts off at 1 keV due to the GEANT threshold.

FDC

Detector Configuration:

  • Double-Hit Resolution: 250 ns
  • Threshold: 1 keV
  • Strip Threshold: 5 mV
    • Where is this applied? What is assumed about electronics?
  • Maximum Number of Hits: 100
    • Is this at the event level? If so, 100 is probably not large enough.
A plot of the rate as a function of anode wire number for the most dowstream anode plane (blue), the most upstream anode plane (red), and the average rate (black).
A plot of the rate as a function of cathode strip number for the most dowstream cathode plane (blue), the most upstream cathode plane (red), and the average rate (black).
A plot of the rate within 5 cm of the beam axis as a function of the plane number if the FDC. Planes for which N%3 == 2 are anodes, all other planes are cathodes. The notable increase in rate for the downstream chambers could be due to opening of charged particles in the relatively weaker field.
A double-log plot of the energy of all hits in the FDC. The spectrum cuts off at 1 keV due to the GEANT threshold.