Nathaniel Tagg. firstname.lastname@example.org
PhotonTransport provides the Monte-Carlo simulation of scintillator and
optical fibre in the MINOS detectors. Either GMINOS or the new
MinosMC package tracks particles through the detector, depositing
energy in the scintillator. These energy depositions are taken by
PhotonTransport, which computes how much light is created by each hit,
tracks the scintillator light through the strip until it hits a
wavelength shifting fibre. Then it tracks the photon refraction into
the WLS fibre core, where the photon is (probably) absorbed. The
WLS fluror then decays, emitting photons isotropically, some of which
are trapped in the fibre and transmitted down it. Photons are
attenuated in the fibre and finally reach the PMT photocathode, where
they generate photoelectrons.
Each of these steps can be done by pluggable modules which are configured at run-time.
PhotonTransport looks for a list of DigiScintHits in the SimSnarlRecord in Mom.
These Hits are used to generate the resulting light. PhotonTransport
doesn't use any other information (besides the SimSnarlRecordHeader).
PhotonTransport creates a list of DigiPEs in the SimSnarlRecord as it's output. In addition, it creates a PhotonEventResult record in the SimSnarl which can be used to compile statistics on things like tracking errors.
PhotonTransport makes heavy use of databases through the Plex, UgliGeometry, and Calibrator
packages. It also uses several custom tables for things such as
spectral information and PMT quantum efficiency as functions of
wavelength. At present, these tables include:
Last, the PHOTONPROTONRANGE table is used to compute the range of
protons in scintillator. (This is done as a fix to the problem that
GEANT does not properly track very small track lengths, resulting in
infinite dE/dx when calculating Birk's supression.)
There are many ways of running PhotonTransport. In particular, the
package can be set up for "fast" simulation, "simple" simulation
(meaning straightforward algorithms, not simple to use), and "full"
simulation. Most users will want to run the simulation in the "fast"
mode, the default. The other modes are useful mostly for
cross-checking and validation of the fast mode.
PhotonTransport has many configurable options, but the defaults should
be sufficient for most users. The simplest macro for setting up DetSim
and Photon Transport is available at $SRT_PUBLIC_CONTEXT/PhotonTransport/macros/simple.C.
Configurable options are fully described in the macro file $SRT_PUBLIC_CONTEXT/PhotonTransport/macros/mc.C, which lists all the available options, set to their defaults.
These two macro files are always kept up-to-date and serve as the basic documentation for configuring the package
Description of DetSim and PhotonTransport (older)
Also, see the slides of my talks at the June 2004 (Ely) and Sept 2004 (FermiLab)
Last Modified: $Date: 2004/10/05 14:33:54 $