110 lines
4.8 KiB
C++
110 lines
4.8 KiB
C++
/***************************************************************************
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* musrSim - the program for the simulation of (mainly) muSR instruments. *
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* More info on http://lmu.web.psi.ch/simulation/index.html . *
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* musrSim is based od Geant4 (http://geant4.web.cern.ch/geant4/) *
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* *
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* Copyright (C) 2009 by Paul Scherrer Institut, 5232 Villigen PSI, *
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* Switzerland *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the Free Software *
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. *
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***************************************************************************/
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#include "musrQuadrupole.hh"
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#include "musrParameters.hh"
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musrQuadrupole::musrQuadrupole(G4double halflengthVal, G4double fieldRadiusVal, G4double gradientVal, G4double fringeFactorVal, G4LogicalVolume* logVolume, G4ThreeVector positionOfTheCenter) : F04ElementField(positionOfTheCenter, logVolume)
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{
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G4cout << "\n-----------------------------------------------------------"
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<< "\n Quadrupole field "
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<< "\n-----------------------------------------------------------"
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<< G4endl;
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gradient = gradientVal; //*(tesla/m);
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fieldRadius = fieldRadiusVal; //*mm;
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halflength = halflengthVal; //*mm;
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enge = BLEngeFunction(ENGE_QUAD);
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G4double fringeFactor = fringeFactorVal; // the default should be 1.
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G4bool fringe = true; if (fringeFactor==0.) {fringe=false;}
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fringeDepth = fringeFactor * fieldRadius * 2.0;
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if (!fringe) {
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enge.set(0,0,0,0,0,0);
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fringeMaxZ = halflength;
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}
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else {
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for(int i=0; i<1000; ++i) {
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fringeMaxZ = i*fieldRadius/10.0 + halflength;
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if(enge((fringeMaxZ-halflength)/fringeDepth) < FRINGE_ACCURACY) break;
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}
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}
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G4cout << " Field gradient set to "<< gradient/(CLHEP::tesla/CLHEP::m) << " T/m"<< G4endl;
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G4cout << " Field radius set to " << fieldRadius/CLHEP::mm << " mm"<< G4endl;
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G4cout << " Field halflength set to " << halflength/CLHEP::mm << " mm"<<G4endl;
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G4cout << " Field fringeDepth set to " << fringeDepth/CLHEP::mm << " mm"<<G4endl;
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G4cout << " Field fringeMaxZ set to " << fringeMaxZ/CLHEP::mm << " mm"<<G4endl;
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G4cout << "\n-----------------------------------------------------------" << G4endl;
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}
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void musrQuadrupole::addFieldValue(const G4double point[4], G4double *field ) const {
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G4ThreeVector global(point[0],point[1],point[2]);
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G4ThreeVector local;
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local = global2local.TransformPoint(global);
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G4double r = sqrt(local[0]*local[0]+local[1]*local[1]);
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if (r > fieldRadius || fabs(local[2]) > fringeMaxZ) { return;}
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// apply enge() to the scalar potential phi=-G0*x*y*enge(z);
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// B is minus its gradient. Handle both edges properly.
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G4double G0 = gradient;
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G4double f,fp;
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if (fringeDepth!=0) {
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double fringeZ = (fabs(local[2])-halflength)/fringeDepth;
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f = enge(fringeZ);
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fp = enge.prime(fringeZ)/fringeDepth;
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}
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else {
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f = ( fabs(local[2]) > halflength) ? 0:1;
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fp = 0;
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}
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G4ThreeVector B(G0*f*local[1],G0*f*local[0],G0*fp*local[0]*local[1]);
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if(local[2] < 0.0) B[2] = -B[2];
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G4ThreeVector finalField(B[0],B[1],B[2]);
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finalField = global2local.Inverse().TransformAxis(finalField);
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field[0] += finalField.x();
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field[1] += finalField.y();
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field[2] += finalField.z();
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// G4cout<<"musrQuadrupole.cc: field: ("<<field[0]/tesla<<","<<field[1]/tesla<<","<<field[2]/tesla<<")"<<G4endl;
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}
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G4double musrQuadrupole::GetNominalFieldValue() {
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return gradient;
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}
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void musrQuadrupole::SetNominalFieldValue(G4double newFieldValue) {
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// // Rescale the magnetic field for a new value of the magnetic field
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gradient=newFieldValue;
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G4cout<<"musrQuadrupole.cc: gradient changed to="<< gradient/(CLHEP::tesla/CLHEP::m)<<" T/m"<<G4endl;
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}
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