G4SmpNVel.cc

Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file G4SmpNVel.cc

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// This software was developed by Lawrence Livermore National Laboratory.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
// 3. The name of the author may not be used to endorse or promote products
//   derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2006 The Regents of the University of California.
// All rights reserved.
// UCRL-CODE-224807
//
//
//

#include <cmath>
#include "G4fissionEvent.hh"

G4double G4fissionEvent::G4SmpNVel(G4double eng, G4double* cosdiru, G4double* cosdirv, G4double* cosdirw) {

/*
  Description
    Knowing the neutron energy, determine its velocity and the 3 direction cosines
*/

/*
  Input
    eng     - energy of neutron
  Output
            - velocity
            - 3 components of the neutron velocity
              in arguments (cosdiru, cosdirv, cosdirw)
*/

   const G4double rme = 939.56563; /* Rest Mass Energy equivalents for neutrons (MeV) */
   const G4double cspeed = 2.99792458e+8; /* speed of light (m/sec) */

   G4double vel;
   G4double ratio = eng/rme;

   if (ratio > 1.e-8) {
/*    Relativistic vel calculation */
      vel = cspeed*std::sqrt(1.-rme*rme/((rme+eng)*(rme+eng)));
   } else {
/*    Non-relativistic vel calculation */
      vel = cspeed*std::sqrt(2.*eng/rme);
   }

   G4SmpIsoDir(cosdiru, cosdirv, cosdirw);

   return vel;
}