[819] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // |
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| 27 | // This software was developed by Lawrence Livermore National Laboratory. |
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| 28 | // |
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| 29 | // Redistribution and use in source and binary forms, with or without |
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| 30 | // modification, are permitted provided that the following conditions are met: |
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| 31 | // |
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| 32 | // 1. Redistributions of source code must retain the above copyright notice, |
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| 33 | // this list of conditions and the following disclaimer. |
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| 34 | // 2. Redistributions in binary form must reproduce the above copyright notice, |
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| 35 | // this list of conditions and the following disclaimer in the documentation |
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| 36 | // and/or other materials provided with the distribution. |
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| 37 | // 3. The name of the author may not be used to endorse or promote products |
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| 38 | // derived from this software without specific prior written permission. |
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| 39 | // |
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| 40 | // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
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| 41 | // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
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| 42 | // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
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| 43 | // EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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| 44 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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| 45 | // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
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| 46 | // OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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| 47 | // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
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| 48 | // OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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| 49 | // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 50 | // |
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| 51 | // Copyright (c) 2006 The Regents of the University of California. |
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| 52 | // All rights reserved. |
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| 53 | // UCRL-CODE-224807 |
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| 54 | // |
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| 55 | // |
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| 56 | // $Id: G4SmpTerrell.cc,v 1.2 2007/06/01 13:46:53 gcosmo Exp $ |
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| 57 | // |
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| 58 | |
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| 59 | #include <cmath> |
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| 60 | #include "G4fissionEvent.hh" |
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| 61 | |
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| 62 | #define TWOPI 6.283185307 |
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| 63 | #define SQRT2 1.414213562 |
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| 64 | #define BSHIFT -0.43287 |
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| 65 | #define WIDTH 1.079 |
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| 66 | |
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| 67 | G4double G4fissionEvent::G4SmpTerrell(G4double nubar) { |
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| 68 | /* |
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| 69 | Description |
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| 70 | Sample Fission Number from Terrell's modified Gaussian distribution |
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| 71 | |
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| 72 | method uses Red Cullen's algoritm UCRL-TR-222526 |
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| 73 | */ |
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| 74 | |
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| 75 | /* |
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| 76 | Input |
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| 77 | nubar - average number of neutrons per fission |
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| 78 | Output |
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| 79 | G4SmpTerrell - sampled multiplicity |
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| 80 | |
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| 81 | */ |
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| 82 | |
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| 83 | G4double width; |
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| 84 | G4double temp1, temp2, expo, cshift; |
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| 85 | G4double rw, theta, sampleg; |
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| 86 | |
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| 87 | |
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| 88 | if (nubar < WIDTH) G4fissionerr(6, "SmpTerrell", "fission nubar out of range"); |
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| 89 | |
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| 90 | width = SQRT2 * WIDTH; |
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| 91 | temp1 = nubar + 0.5; |
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| 92 | temp2 = temp1/width; |
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| 93 | temp2 *= temp2; |
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| 94 | expo = std::exp(-temp2); |
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| 95 | cshift = temp1 + BSHIFT * WIDTH * expo/(1. - expo); |
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| 96 | |
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| 97 | do { |
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| 98 | rw = std::sqrt(-std::log(fisslibrng())); |
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| 99 | theta = TWOPI * fisslibrng(); |
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| 100 | sampleg = width * rw * std::cos(theta) + cshift; |
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| 101 | } while (sampleg < 0.0); |
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| 102 | |
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| 103 | return std::floor(sampleg); |
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| 104 | } |
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