James Bellinger 22-April-1997

IMU Backgrounds Overview

I used ISAJET to generate 20000 minimum bias events. These I fed to GEANT, using a threshold of 5 MeV for particle transport. To keep from wasting time I cut out non-muons and non-neutrons below 20 MeV when they were more than 10 cm inside a calorimeter. I stored hit information for the IMU drift chambers, the wall counters, the barrel counters, and the toroid counters.

There were two main GEANT models:

  • The old baseline model with the toroid front face at 525 cm, the Kephard snout of 60x60 cm, and a life-saver shield between the toroids 100 cm thick. I fed 20000 events to this model.
  • A new long snout model with the toroid front face at 510 cm, a snout 40 cm thick and 140 cm long, starting at 331 cm radius; and a life-saver shield between the toroids 60 cm thick.

    The GEANT model includes the IMU system, the beampipe, the central E/M and hadron calorimeters, the Wall calorimeter, and the hadronic plug calorimeter. The silicon is also present but not turned on. It uses the Run I solenoid magnetic field map. I did not include beam line shielding, since I did not expect backscatter to play a major role, nor did I include the CMEX. See Figure 1.