BLBeam.hh

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//      BLBeam.hh
/*
This source file is part of G4beamline, http://g4beamline.muonsinc.com
Copyright (C) 2003,2004,2005,2006 by Tom Roberts, all rights reserved.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

http://www.gnu.org/copyleft/gpl.html
*/

#ifndef BLBEAM_HH
#define BLBEAM_HH

#include "globals.hh"
#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleDefinition.hh"
#include "Randomize.hh"

#include "BLManager.hh"
#include "BLCommand.hh"
#include "BLTime.hh"

/**     class BLBeam is an interface class for a beam.
 *
 *      NOTE: all functions are either inline or abstract, so no .cc file is 
 *      needed.
 **/
class BLBeam {
protected:
        G4int nEvents;
public:
        /// Constructor.
        BLBeam() { nEvents = 0; }

        /// Utility: setRandomSeedToGenerate() sets the random seed for
        /// the generation of an event.
        static void setRandomSeedToGenerate(int evid) // reference has evid<0
                { switch(BLManager::getObject()->getPRNGSeedMethod()) {
                  case EVENT_NUMBER:
                        CLHEP::HepRandom::setTheSeed(evid>=0? evid : 0);
                        break;
                  case TIME_US:
                        CLHEP::HepRandom::setTheSeed(BLTime::timems() &
                                                                0x7FFFFFFFL);
                        // do it only once, to avoid duplication
                        BLManager::getObject()->setPRNGSeedMethod(NO_SEED);
                        break;
                  case NO_SEED:
                        return;
                  }
                  CLHEP::RandGauss::setFlag(false);
                  G4UniformRand(); // eat one for luck (don't get seed back)
                }

        /// Utility: setRandomSeedToTrack() sets the random seed for
        /// the tracking of an event.
        static void setRandomSeedToTrack(int evid) // reference has evid<0
                { setRandomSeedToGenerate(evid);
                  // allow 16 random numbers for generation
                  for(int i=0; i<16; ++i)
                        G4UniformRand();
                }

        /// getNEvents() returns the # events to process.
        virtual int getNEvents() const { return nEvents; }

        /// init() will initialize internal variables.
        virtual void init() = 0;

        /// generateReferenceParticle() generates the reference particle.
        /// BLManager calls this once for the TuneParticle during event -2,
        /// and once for the ReferenceParticle during event -1.
        /// Should always call setRandomSeedToTrack() before returning.
        /// Returns true if event generated; false if not.
        virtual bool generateReferenceParticle(G4Event *event) = 0;

        /// nextBeamEvent() generates the next beam event.
        /// If generating randomly, should call setRandomSeedToGenerate()
        /// and use no more than 16 random numbers.
        /// If read from a file, it should call event->SetEventID().
        /// Should always call setRandomSeedToTrack() before returning.
        /// Returns true if event generated; false if no more events.
        virtual bool nextBeamEvent(G4Event *event) = 0;

        /// summary() will print a summary, if necessary.
        virtual void summary() { }
};

#endif// BLBEAM_HH