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## Problem with local magnetic field

Forum: Fields: Magnetic and Otherwise
Date: 15 Dec, 2011
From: Lukasz Fulek <Lukasz Fulek>

 Hi! I'm new to this forum and GEANT4. I have big problem with my magnetic field. I definded such torus part and I want to attach a local magnetic field to it but it doesn't work. The beam is not in the center of this torus at the end. Below is a part of the code. Any suggestions ```G4double dxlength = 3.700219;//m G4double dxangle = 0.0188608;//rad0.0188608 G4double tiradius = 13.0; //cm``` ``` G4double tsweptradius =dxlength/(2*dxangle); //m G4cout << "swept"<rotateY(180*deg);//180 rotm->rotateX(90*deg);//90 //////////////////////////////////////////////////////////////////////// //Magnetic field torus 1 G4double q = 1.6021765314e-19; G4double mp = 1.6726217129e-27; G4double convertj = 1.60217656525e-19; G4double energystart =100.;``` ``` G4double magtor1val = std::sqrt(2*energystart*convertj*mp)/(tsweptradius*q);//tesla 1st torus G4cout << "field:" << magtor1val << G4endl;``` ``` G4double fieldValue = magtor1val*tesla; G4UniformMagField* myField =new G4UniformMagField(G4ThreeVector(0.,-fieldValue,0.)); G4Mag_UsualEqRhs* myEquation = new G4Mag_UsualEqRhs(myField); G4MagIntegratorStepper* myStepper = new G4ClassicalRK4(myEquation); G4ChordFinder* myChordFinder = new G4ChordFinder(myField,1.0e-5 * mm,myStepper); G4FieldManager* fieldMgr = new G4FieldManager(myField,myChordFinder);``` ` ////////////////////////////////////////////////////////////////////////` ``` G4VSolid* dipoleDXSolid = new G4Torus("dipoleDX_Solid", 0*cm, tiradius*cm, tsweptradius*m, 0.*radian, dxangledx*radian); G4LogicalVolume* dipoleDXLogical = new G4LogicalVolume(dipoleDXSolid, vacuum, "dipoleDX_Logical",fieldMgr,0,0); new G4PVPlacement(rotm, G4ThreeVector(tsweptradius*m,0.,phlengthz*m), dipoleDXLogical, "dipoleDX_Physical", fpWorldLogical, false, 0); ```

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1 Re: Problem with local magnetic field   (Gumplinger Peter - 15 Dec, 2011)
Re: Problem with local magnetic field   (Lukasz Fulek - 15 Dec, 2011)
Re: Problem with local magnetic field   (Gumplinger Peter - 15 Dec, 2011)
Re: Problem with local magnetic field   (Lukasz Fulek - 15 Dec, 2011)
 to: "Problem with local magnetic field"
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