00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // This software was developed by Lawrence Livermore National Laboratory. 00028 // 00029 // Redistribution and use in source and binary forms, with or without 00030 // modification, are permitted provided that the following conditions are met: 00031 // 00032 // 1. Redistributions of source code must retain the above copyright notice, 00033 // this list of conditions and the following disclaimer. 00034 // 2. Redistributions in binary form must reproduce the above copyright notice, 00035 // this list of conditions and the following disclaimer in the documentation 00036 // and/or other materials provided with the distribution. 00037 // 3. The name of the author may not be used to endorse or promote products 00038 // derived from this software without specific prior written permission. 00039 // 00040 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 00041 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 00042 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 00043 // EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 00044 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 00045 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 00046 // OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 00047 // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 00048 // OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 00049 // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00050 // 00051 // Copyright (c) 2006 The Regents of the University of California. 00052 // All rights reserved. 00053 // UCRL-CODE-224807 00054 // 00055 // 00056 // $Id: G4SmpTerrell.cc 69860 2013-05-16 14:39:02Z gcosmo $ 00057 // 00058 00059 #include <cmath> 00060 #include "G4fissionEvent.hh" 00061 00062 #define TWOPI 6.283185307 00063 #define SQRT2 1.414213562 00064 #define BSHIFT -0.43287 00065 #define WIDTH 1.079 00066 00067 G4double G4fissionEvent::G4SmpTerrell(G4double nubar) { 00068 /* 00069 Description 00070 Sample Fission Number from Terrell's modified Gaussian distribution 00071 00072 method uses Red Cullen's algoritm UCRL-TR-222526 00073 */ 00074 00075 /* 00076 Input 00077 nubar - average number of neutrons per fission 00078 Output 00079 G4SmpTerrell - sampled multiplicity 00080 00081 */ 00082 00083 G4double width; 00084 G4double temp1, temp2, expo, cshift; 00085 G4double rw, theta, sampleg; 00086 00087 00088 if (nubar < WIDTH) G4fissionerr(6, "SmpTerrell", "fission nubar out of range"); 00089 00090 width = SQRT2 * WIDTH; 00091 temp1 = nubar + 0.5; 00092 temp2 = temp1/width; 00093 temp2 *= temp2; 00094 expo = std::exp(-temp2); 00095 cshift = temp1 + BSHIFT * WIDTH * expo/(1. - expo); 00096 00097 do { 00098 rw = std::sqrt(-std::log(fisslibrng())); 00099 theta = TWOPI * fisslibrng(); 00100 sampleg = width * rw * std::cos(theta) + cshift; 00101 } while (sampleg < 0.0); 00102 00103 return std::floor(sampleg); 00104 }