Configuration file "test_xtal1.py" 

Set number of events to simulate :

> process.maxEvents = cms.untracked.PSet(
>     input = cms.untracked.int32(1000)
> )


Set 

> process.generator = cms.EDProducer("FlatRandomEGunProducer",
>    PGunParameters = cms.PSet(

Particle type (check on http://geant4.web.cern.ch/geant4/G4UsersDocuments/UsersGuides/ForApplicationDeveloper/html/TrackingAndPhysics/particle.html) :

>        PartID = cms.vint32(111),

Define eta, phi and energy range :

>        MaxEta = cms.double(0.138424),
>        MaxPhi = cms.double(-0.0257494),
>        MinEta = cms.double(0.138424),
>        MinE = cms.double(10.00),
>        MinPhi = cms.double(-0.0257494),
>        MaxE = cms.double(10.00)
>    ),