Contact Name

Nathaniel Tagg.


DetSim is responsible for Monte-Carlo simulation of the PMTs, front-end electronics, and DAQ for both the near detector and far detector.  The package tracks photoelectons through the PMT to electrical signals to front-end digits, and simulated DAQ triggers.

The most interesting features of this simulation are:
- PMT crosstalk
- PMT nonlinearity
- VA and QIE nonlinearity
- Noise (PMT dark noise or random green fibrelight)
- VA dead time
- VARC pretrigger (i.e. the 2/36 trigger)
- DAQ 4/5 trigger


Input Objects

DetSim looks for an array of DigiPE objects in the SimSnarlRecord in Mom. These DigiPEs (specified in the Digitization package) are usually created by PhotonTransport.

Output Objects

DetSim creates a RawRecord, if one does not already exist, and places one (or more) RawDigitDataBlock full of RawDigits in the RawRecord.

In addtion, DetSim will create an array of DigiSignals in the SimSnarlRecord, which serve as truth information, allowing one to backtrack from RawDigit to the DigiScintHit that created them.

Finally, DetSim creates a SimEventResult object in the SimSnarlRecord which records statitics on the current event, such as true number of PEs created, true ADC counts before triggering, etc.

Database Access

DetSim makes heavy use of databases through the Plex and Calibrator packages. In addition, it has a few custom tables ("SIM*") that are used as look-ups for monte-carlo generation. At present, the two tables are SIMPMTM64CROSSTALK and SIMPMTM16CROSSTALK, which hold the crosstalk parameterizations for the M64 and M16 PMTs respectively.

Configuring & Running

Most users will not need to tweak the DetSim options. Running instructions for running PhotonTransport and DetSim are given in the macro file $SRT_PUBLIC_CONTEXT/PhotonTransport/macros/simple.C

DetSim has many configurable options. All the options for PhotonTransport and DetSim are listed, with their defaults, in $SRT_PUBLIC_CONTEXT/PhotonTransport/macros/mc.C

These two macro files are always kept up-to-date and serve as the basic documentation for configuring the module.

Further Links

See also:
    PhotonTransport Overview
    Digitization Overview  
    Description of DetSim and PhotonTransport (older)
    Also, see the slides of my talks at the June 2004 (Ely) and Sept 2004 (FermiLab)

Nathaniel Tagg Last Modified: $Date: 2005/02/02 11:56:17 $