CDF Detector Simulation
Last modified: Fri Aug 26 13:33:43 CDT 2005
Standalone MC Production: MC@NLO

Contact: Jason Galyardt

Note: MC@NLO is a standalone matrix element generator which matches Next-to-Leading-Order calculations of rates for QCD processes with a parton shower Monte Carlo event generator (HERWIG). Currently, the recommended method for generating MC events which can be imported into the CDF Run II simulation framework is to run MC@NLO with standalone HERWIG, write the output in StdHep format, then use the LesHouches package to read the StdHep files into cdfSim for re-decay and detector simulation. The megenConfig package should be used to process multi-file StdHep samples with the luminosity weighted, run-dependent MC scheme, mcProduction. This path allows the option of using JIMMY for simulating the underlying event instead of the HERWIG internal code, since JIMMY should run seamlessly with standalone HERWIG (this might not be the case for CDF HERWIG).

Documentation: Useful Links: Examples:

Event Weights: MC@NLO produces "unweighted" events in the sense that the magnitude of the event weights may be configured to be 1.0. The sign of these weights is however important and should be kept through detector simulation and reconstruction, then used when observables are histogrammed. There are two ways of storing the event weight: encode the sign of the weight in the energy of the colliding proton, recorded in the HEPG bank (see the first example below), or store the weight in the event record. A UserInfo object may be used to employ the latter method, as is done in cdfSim by MCInfoModule (see CDF 7769).

  • An example of how to install and run MC@NLO with StdHep output courtesy of David Waters (update coming soon).
  • An updated example (for v3.1), based upon David Waters' code (see the previous example), can be found here. This example also includes modifications which allow one to set the HERWIG random generator seeds in the top-level MC@NLO script.
  • How (and why) to process multi-file StdHep format samples with mcProduction using the megenConfig package.

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