Generating single particle MC in CMSSW (A. Askew):
This is based on the newest CMSSW_0_6_0 release.
Producing single particles is fairly easy at the moment.  There
is a sample cfg file in SimG4Core/Application/test/EvtGen+DetSim+Digi.cfg

To Check it out and run it, log into the UAF and do the following:
(note:  Make sure that you have issued source /afs/fnal.gov/files/code/cms/setup/cshrc uaf)
In an area where you have space, make a new CMSSW project area:
> scramv1 project CMSSW CMSSW_0_6_0
> cd CMSSW_0_6_0
> eval `scramv1 runtime -csh`
> cd src
> cmscvsroot CMSSW
> cvs login (password 98passwd)
> cvs checkout -r CMSSW_0_6_0 SimG4Core/Application
> cd SimG4Core/Application/test

To run it out of the box (which works, I checked)
> cmsRun EvtGen+DetSim+Digi.cfg

By default, this is set to run the generation of single muon events flat
in E at 20 GeV, and run the GEANT4 simulation and digitization.  If you don't want
single muons, we'll need to edit this cfg file.  Open it with your favorite editor 
(mine is xemacs):

> xemacs EvtGen+DetSim+Digi.cfg &

The first two blocks of this cfg file handle the message logger and the random number
generation service.  For reference, the random number generation service is where you can 
alter the seed if you wish.  Scroll down to:

   source = FlatRandomEGunSource
   {
      untracked int32 maxEvents = 1000
      PSet PGunParameters =
      {
         # you can request more than 1 particle
         #vint32  PartID = {211,11}
         vint32 PartID = { 13 }
         double MinEta = -3.5
         double MaxEta = 3.5
         double MinPhi = -3.14159265358979323846 # must be in radians
         double MaxPhi =  3.14159265358979323846
         double MinE  = 19.99
         double MaxE  = 20.01
      }
      untracked int32 Verbosity = 0 # set to 1 (or greater)  for printouts
   }

This is where you can alter the kinematics and identity of the particles that you are
generating.  PartID is the PDG Particle ID of the particle you want.  The other
paramters should be fairly obvious.  The Z-vertex of these particles is randomly
spread out in a gaussian, the parameters of which are in the next block.

This only runs the digitization, which does not get you to calibrated EcalRecHits, which
is probably what people are interested in in the ElectronPhoton group.  If you want
to go ahead and make the EcalRecHits, you need to add the following block to this
cfg file:

   ###################################################################
   # Get hardcoded conditions the same used for standard digitization
    es_source = EcalTrivialConditionRetriever {
         #untracked double adcToGeVEBConstant = 0.0286
        untracked double adcToGeVEBConstant = 0.0636
    }
   ###################################################################
  
   include "RecoLocalCalo/EcalRecProducers/data/EcalWeightUncalibratedRecHitProducer.cfi"
   include "RecoLocalCalo/EcalRecProducers/data/EcalRecHitProducer.cfi"   
   ####
You will also have to alter what modules are executed (this is at the bottom of the
file).  They should look like this:
   sequence trDigi = { pixdigi & stripdigi }
   sequence calDigi = { ecaldigi & hcaldigi }
   sequence muonDigi = { muoncscdigi & muondtdigi  }
   sequence doDigi = { trDigi & calDigi & muonDigi   }
   sequence doURec = { ecaluncalibrechit }
   sequence doRec  = { ecalrechit }
   path p1 = { VtxSmeared, SimG4Object, mix, doDigi, doURec, doRec }
   endpath outpath = { GEN-SIM-DIGI }

I've put my example cfg file in /uscms_data/d1/askew/Examples_SingleParticle_withEcalRecHits.cfg
if you want to compare.  That's it!  You now have a file that you can feed in to the EcalClustering,
or make plots of the rechits.