Simulation of Experimental Background Using Fluka

In November 1997, Experiment T423 began acquiring data with the intentions of understanding the energy spectra of high-energy neutrons generated in the interaction of electrons with lead. The following describes a series of FLUKA simulations studying (1) particle yields in the absence of all background; (2) the background caused from scattering in the room; (3) the effects of the thick lead shielding which surrounded the detector; (4) the sources of neutron background created in this lead shielding; and (5) the ratio of the total background to the ideal yield. In each case, particular attention is paid to the neutron yield. Experiment T423 was conducted in the FFTB (Final Focus Test Beam) facility at SLAC. Neutrons were produced when the 20 GeV electron beam collided with a 2 cm thick lead target. The TOF distance was approximately 6 meters. Neutrons ranging in energies from 2 to 200 MeV were detected in two detectors. A 5 " liquid scintillator was located at 26 degrees and a 2 " plastic scintillator was used at 38 degrees. The following simulations only consider the yield at the 5 " detector and do not incorporate detector efficiencies.