Gabriele Cosmo
180 lines
10 KiB
C++
180 lines
10 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: G4VCrossSection.hh,v 1.1 2009-11-16 18:15:42 mkossov Exp $
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// GEANT4 tag $Name: not supported by cvs2svn $
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//
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//
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// GEANT4 virtual class: G4VCrossSection -- header file
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// M.V. Kossov, CERN-ITEP(Moscow), 4-FEB-2004
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// The last update: M.V. Kossov, CERN/ITEP (Moscow) 27-Nov-04
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//
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// This class has been extracted from the CHIPS model.
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// All the dependencies on CHIPS classes have been removed.
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//
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// Original description by M.K. follows.
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// Short description: this G4 virtual class is made for the cross section
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// classes of the CHIPS model, which calculate the cross section for the
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// particular Element (virtual GetCrossSection member function). Each of the
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// CHIPS cross section classes creates its own Dynamic Associative Memory
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// Data Base (DAMDB) for the already used isotopes. For all of them thay use the
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// same algorithm. Common member functions of this algorithm can be in this
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// basic virtual class. Any CHIPS cross section class MUST inherit from this virtual
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// G4VCrossSection class. In the G4QCollision class the general G4VCrossSection*
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// pointer is connected to this or that CHIPS cross section class (depending on the
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// projectile particle), so each of the CHIPS cross section class must be
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// an evolving singletone. The singletone nature can not be realized in the
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// virtual class. So each derived CS class must have
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// static G4VCrossSection* GetPointer(); // Gives a pointer to the singletone
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// static function, which is defined in the *.cc file as
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// // Returns Pointer to the G4VCrossSection class
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// G4VCrossSection* G4VCrossSection::GetPointer()
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// {
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// static G4QXCrossSection theCrossSection; //***Static body of the Cross Section***
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// return &theCrossSection;
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// }
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// the line
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// //virtual static G4VCrossSection* GetPointer(); // Gives a pointer to the singletone
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// Reminds about this necesity, but in C++ the virtual static function can not be
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// realised, so the static function can not be realised in the interface. Developers
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// must take care of this themselves because this member fuction is called to get a pointer
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// to the singletone in the G4QCollision class. So there is an agreement to
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// make a separate CS class for each projectile particle, e.g. while the (pi-)d
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// and (pi+)d (as well as [n,z] and [z,n]) cross sections) are almost equal,
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// they must be calculated in different classes: G4QPiMinusCrossSection and
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// G4QPiPlusCrossSections. For the ion-nuclear cross sections there should exist only
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// one G4QIonCrossSection class with a huge (#0f isotopes times #of already produced
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// ions) DAMDB or a general analitic formula with parameters. --- December 2004 ---
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// -----------------------------------------------------------------------
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// At present (25.11.04) for the test purposes this virtual class is created
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// for ohly G4QPhotonCrossSection, G4QElectronCrossSection, G4QMuonCrossSection,
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// G4QTauCrossSection and G4QProtonCrossSection (only for pp collisions now).
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// -----------------------------------------------------------------------
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#ifndef G4VCrossSection_h
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#define G4VCrossSection_h 1
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#include "G4ParticleTable.hh"
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#include "G4NucleiProperties.hh"
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#include <vector>
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#include "Randomize.hh"
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class G4VCrossSection
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{
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protected:
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G4VCrossSection() {;} // for each particle a separate instance of G4QCollision should be
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// used (and inside use a separate instance of G4Q*CrossSection)
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public:
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virtual ~G4VCrossSection() {;}// for each particle separate instance of G4QXCrossSection
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//@@ can be improved in future)// should be used and inside a separate istance of CS's
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// Set the new tolerance (abs(p_old/p_new-1)<tolerance)
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static void setTolerance(G4double tol){tolerance=tol;}// Set NewTolerance for SameCrosSec
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// At present momentum (pMom) must be in GeV (@@ Units)
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virtual G4double GetCrossSection(G4bool, G4double, G4int, G4int, G4int pPDG=0)
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{return G4double(pPDG);}
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virtual G4double ThresholdEnergy(G4int Z, G4int N, G4int PDG=0); // Gives 0 by default
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// Define in the derived class, F=0 - create AMDB, F=-1 - read AMDB, F=1 - update AMDB
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virtual G4double CalculateCrossSection(G4bool CS, G4int F, G4int I, G4int PDG, G4int tgZ,
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G4int tgN, G4double pMom)=0;//*** PURE VIRTUAL ***
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virtual G4double GetLastTOTCS(); // LastCalculated total cross-section (total elastic)
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virtual G4double GetLastQELCS(); // LastCalculated quasielastic cross-section (quasifree)
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virtual G4double GetDirectPart(G4double Q2); // DirectInteraction with QuarkPartons (nuA)
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virtual G4double GetNPartons(G4double Q2); // #ofQuarkPartons in nonPerturbatPhaseSp(nuA)
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// Subroutines for the t-chanel processes with a leader (DIS, Elastic, Quasielastic etc.)
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virtual G4double GetExchangeEnergy(); // Returns energy of the t-chanel particle (gam,pi)
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virtual G4double GetExchangeT(G4int tZ, G4int tN, G4int pPDG); // -t=Q2 for hadronic
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virtual G4double GetSlope(G4int tZ, G4int tN, G4int pPDG); // B-slope of the maim maximum
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virtual G4double GetHMaxT(); // max(-t=Q2)/2 for hadronic (MeV^2)
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virtual G4double GetExchangeQ2(G4double nu=0); // Q2 for lepto-nuclear reactions
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virtual G4double GetVirtualFactor(G4double nu, G4double Q2); // ReductionFactor (leptA)
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virtual G4double GetQEL_ExchangeQ2(); // Get randomized Q2 for quasi-elastic scattering
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virtual G4double GetNQE_ExchangeQ2(); // Get randomized Q2 for non quasi-elastic scat.
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virtual G4int GetExchangePDGCode(); // PDGCode of the Exchange Particle (Pi0 by default)
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// Body: Basic Parameters of DAMDB (each derived class can add it's own values)
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// -----------------------------------------------------------------------------
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// The basic scheme of the DAMDB coveres the cross section for isotopes with fixed
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// Z (lastZ - number of protons) and N (lastN - number of neutrons) from the
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// Threshold momentum (TH) up to infinity. The cross section is first (Tab.1)
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// tabulated from the threshold till the boundary momentum (BP). The Tab.1 is
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// the function of the momentum (p) with the N1 elements. The N1 elements can be
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// not all different from zero. The first non-zero element is F1, the last non-zero
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// element is L1. If TH#0 the Tab.1 can be skipped. It is defined by N1=F1=L1=0 and
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// BP=TH. The Tab.1 is the function of the ln(p) with N2 elements (F2 is the first
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// non-zero element, L2 is the last non-zero element) from BP up tp MP. Both Tab.1
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// and Tab.2 are calculated when the projectile of the class meet the corresponding
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// ion. After that the tables are stored in the DAMDB for the fast calculations. To
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// avoid a complete calculation of the tables in the low energy calculation case,
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// the lastP momentum is used. The tables are calculated only till the momentum,
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// which already appeared in the simulation for this projectile and this isotope.
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// If the momentum above MP appeared, then the extrapolation function is calculated.
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// So, if lastP>MP it means that the cross section is defined for all energies above
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// TH. All parameters and pointers to arrays MUST be stored (F=0), updated (F=1) and
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// retrieved (F=-1) by the derived class in the CalculateCrossSection(F,I,N,Z,P)
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// function. The parameters are used for the immediate result: if the cross section is
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// calculated for the same Z, N, and fabs(p-lastP)/lastP<.001 (? - a parameter), the same
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// cross section (lastCS) is returned, if p<lastTH, then the 0 cross section is returned.
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// It helps to avoid double counting. The derived class can have only the approximation
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// functions, but such class is too slow, as it calculates the arythmetic equations each
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// time, when it is necessary to get a new cross section. So it is reasonable to
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// precalculate the tables, store them in memory, remember the pointers to these
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// functions and just interpolate them in the range of the most frequent energies (use
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// a LinearFit inline function of this virtual class for that). Starting some high
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// momentum (PM) the functional calculations are unavoidable, but fortunately they are
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// not frequent. In case of the ion-nuclear cross section the functional approach can
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// be reasonable, because tabulated cross-sections demand too much memory.
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//
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// -----------------------------------------------------------------------------
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protected:
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G4double LinearFit(G4double X, G4int N, G4double* XN, G4double* YN);
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G4double EquLinearFit(G4double X, G4int N, G4double X0, G4double DX, G4double* Y);
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static G4double tolerance;// relative tolerance in momentum to get old CroSec
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};
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#endif
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