Gabriele Cosmo
198 lines
7.6 KiB
C++
198 lines
7.6 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// $Id: G4KalbachCrossSection.hh 66241 2012-12-13 18:34:42Z gunter $
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//
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// V.Ivanchenko 13.04.2015
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//
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// J.M. Quesada 22.04.2015 several fixes
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#ifndef G4KalbachCrossSection_h
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#define G4KalbachCrossSection_h 1
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#include "globals.hh"
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#include "G4Exp.hh"
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#include "G4Pow.hh"
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//from subroutine sigpar of PRECO-2000 by Constance Kalbach Walker
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// Calculate optical model reaction cross sections
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// using the empirical parameterization
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// of Narasimha Murthy, Chaterjee, and Gupta
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// going over to the geometrical limit at high energy.
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//
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// Proton cross sections scaled down with signor for a<100
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// (appropriate for becchetti-greenlees potential).
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// p2 reduced and global red'n factor introduced below Bc
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// Neutron cross sections scaled down with signor for a<40
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// Scaled up for A>210 (added June '98 to conform with
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// my published papers)
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// (appropriate for Mani et al potential)
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//
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// index: 0-neutron, 1-proton, 2-deuteron, 3-triton, 4-He3, 5-He4
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// parameters: p0, p1, p2, lambda0, lambda1, mu0, mu1, nu0, nu1, nu2, ra
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static const G4double paramK[6][11] = {
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// n from mani, melkanoff and iori
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{-312., 0., 0., 12.10, -11.27, 234.1, 38.26, 1.55, -106.1, 1280.8, 0.0},
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// p from becchetti and greenlees (but modified with sub-barrier
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// correction function and p2 changed from -449)
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{15.72, 9.65, -300., 0.00437,-16.58, 244.7, 0.503, 273.1, -182.4, -1.872, 0.0},
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// d from o.m. of perey and perey
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{0.798, 420.3,-1651., 0.00619, -7.54, 583.5, 0.337, 421.8, -474.5, -3.592, 0.8},
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// t from o.m. of hafele, flynn et al
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{-21.45,484.7,-1608., 0.0186, -8.9, 686.3, 0.325, 368.9, -522.2, -4.998, 0.8},
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// 3he from o.m. of gibson et al
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{-2.88,205.6, -1487.,0.00459,-8.93, 611.2, 0.35 , 473.8, -468.2, -2.225, 0.8},
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// alpha from huizenga and igo
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{ 10.95,-85.2, 1146., 0.0643,-13.96, 781.2, 0.29, -304.7,-470.0, -8.580, 1.2}
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};
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class G4KalbachCrossSection
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{
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public:
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static G4double ComputePowerParameter(G4int resA, G4int idx)
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{
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return G4Pow::GetInstance()->powZ(resA, paramK[idx][6]);
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}
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static G4double ComputeCrossSection(G4double K, G4double cb,
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G4double resA13, G4double amu1,
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G4int idx, G4int Z, G4int A,
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G4int resA)
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{
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G4double sig = 0.0;
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G4double signor = 1.0;
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G4double lambda, mu, nu;
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G4double ec = 0.5;
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if(0 < Z) { ec = cb; }
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//JMQ 13.02.2009 tuning for improving cluster emission ddxs
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// (spallation benchmark)
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/*
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G4double xx = 1.7;
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if(1 == A) { xx = 1.5; }
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ec = 1.44 * Z * resZ / (xx*resA13 + paramK[idx][10]);
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}
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*/
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G4double ecsq = ec*ec;
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G4double elab = K * (A + resA) / G4double(resA);
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if(idx == 0) { // parameterization for neutron
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if(resA < 40) { signor =0.7 + resA*0.0075; }
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else if(resA > 210) { signor = 1. + (resA-210)*0.004; }
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lambda = paramK[idx][3]/resA13 + paramK[idx][4];
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mu = (paramK[idx][5] + paramK[idx][6]*resA13)*resA13;
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// JMQ 20.11.2008 very low energy behaviour corrected
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// (problem for A (apprx.)>60) fix for avoiding
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// neutron xs going to zero at very low energies
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nu = std::abs((paramK[idx][7]*resA + paramK[idx][8]*resA13)*resA13
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+ paramK[idx][9]);
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} else { // parameterization for charged
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// proton correction
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if(idx == 1) {
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if (resA <= 60) { signor = 0.92; }
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else if (resA < 100) { signor = 0.8 + resA*0.002; }
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}
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lambda = paramK[idx][3]*resA + paramK[idx][4];
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mu = paramK[idx][5]*amu1;
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nu = amu1* (paramK[idx][7] + paramK[idx][8]*ec + paramK[idx][9]*ecsq);
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}
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/*
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G4cout << "## idx= " << idx << " K= " << K << " elab= " << elab << " ec= " << ec
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<< " lambda= " << lambda << " mu= " << mu << " nu= " << nu << G4endl;
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*/
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// threashold cross section
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if(elab < ec) {
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G4double p = paramK[idx][0];
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if(0 < Z) { p += paramK[idx][1]/ec + paramK[idx][2]/ecsq; }
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G4double a = -2*p*ec + lambda - nu/ecsq;
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G4double b = p*ecsq + mu + 2*nu/ec;
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G4double ecut;
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G4double det = a*a - 4*p*b;
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if (det > 0.0) { ecut = (std::sqrt(det) - a)/(2*p); }
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else { ecut = -a/(2*p); }
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//G4cout << " elab= " << elab << " ecut= " << ecut << " sig= " << sig
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// << " sig1= " << (p*elab*elab + a*elab + b)*signor << G4endl;
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// If ecut>0, sig=0 at elab=ecut
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if(0 == idx) {
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sig = (lambda*ec + mu + nu/ec)*signor*std::sqrt(elab/ec);
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} else if(elab >= ecut) {
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sig = (p*elab*elab + a*elab + b)*signor;
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// extra proton correction
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if(1 == idx) {
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// c and w are for global correction factor for
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// they are scaled down for light targets where ec is low.
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G4double cc = std::min(3.15, ec*0.5);
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G4double signor2 = (ec - elab - cc) *3.15/ (0.7*cc);
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sig /= (1. + G4Exp(signor2));
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}
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}
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//G4cout << " ecut= " << ecut << " a= " << a << " b= " << b
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// << " signor= " << signor << " sig= " << sig << G4endl;
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// high energy cross section
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} else {
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// etest is the energy above which the rxn cross section is
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// compared with the geometrical limit and the max taken.
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// neutron parameters
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G4double etest = 32.;
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G4double xnulam = 1.0;
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// parameters for charged
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static const G4double flow = 1.e-18;
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static const G4double spill= 1.e+18;
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if(0 < Z) {
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etest = 0.0;
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xnulam = nu / lambda;
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xnulam = std::min(xnulam, spill);
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if (xnulam >= flow) {
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if(1 == idx) { etest = std::sqrt(xnulam) + 7.; }
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else { etest = 1.2 *std::sqrt(xnulam); }
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}
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}
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// ** For xnulam.gt.0, sig reaches a maximum at sqrt(xnulam).
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sig = (lambda*elab + mu + nu/elab)*signor;
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if (xnulam >= flow && elab >= etest) {
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G4double geom = std::sqrt(A*K);
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geom = 1.23*resA13 + paramK[idx][10] + 4.573/geom;
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geom = 31.416 * geom * geom;
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sig = std::max(sig, geom);
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}
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}
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sig = std::max(sig, 0.0);
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//G4cout << " ---- sig= " << sig << G4endl;
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return sig;
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}
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};
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#endif
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