Progress report on the SVT fast simulation in Bogus

The fast simulation of the SVT was developed as a standalone program, written entirely in C++, using no code from other software packages. After installation of the current version into example parametrization code provided by Marc Verderi, it was recently installed in Bogus by Bill Lockman.

The current version has the following features:

• It tracks particles through all 340 wafers. Wafers are approximated by planar rectangles and trapezoids, consisting of 330 microns of Si. This thickness includes 10% extra material to account, approximately, for the support structures and other material which is not simulated in detail. The configuration is read in from ssvd.db, although the standalone program does not use dbio to parse the file. See this picture of the simulated SVT.
• It tracks charged particles through a uniform magnetic field in the Z direction. Inside Bogus, the field value is taken to be the Z component of the magnetic field at the origin.
• It performs (gaussian) multiple scattering using Gerry Lynch and Orin Dahl's algorithm (accurate to about 2%).
• It performs deterministic energy loss computation using Bethe Bloch, including density effect.
• No secondaries are produced in the simulation.
• Hadronic interactions are not simulated.
• There is one tunable parameter, the maximum sagitta allowed during each tracking step.

• Tracks uncharged particles ("geantinos") of 1 GeV at about 4400 tracks/second, randomly generated in 4Pi.
• Tracks charged muons of 1 GeV through zero magnetic field at about 1900 tracks/second. This includes multiple scattering and energy loss.
• Tracks charged muons of 1 GeV through a 1 Tesla magnetic field at about 940 tracks/second (with maximum sagitta set to 2 microns).

Examples:

• Muon of 27 MeV.
• Muon of 27 MeV.
• Muon of 27 MeV.
• Muon of 27 MeV.
• Muon of 4.5 MeV.
• 100 muons of 1 GeV.
• Electron of 20 MeV.