Merge branch 'add_pdf_evaluator' into 'master'

Add geane and pdf evaluator

See merge request !7

src/jpp/JPhysics/JGeane.hh

+#ifndef __JPHYSICS__JGEANE__
+#define __JPHYSICS__JGEANE__
+
+#include <cmath>
+#include <map>
+
+#include "JPhysics/JConstants.hh"
+
+
+/**
+ * \file
+ * Energy loss of muon.
+ * \author mdejong
+ */
+
+namespace JPHYSICS {}
+namespace JPP { using namespace JPHYSICS; }
+
+namespace JPHYSICS {
+
+  /**
+   * Equivalent muon track length per unit shower energy.
+   *
+   * \return        equivalent muon track length [m/Gev]
+   */
+  inline double geanc()
+  {
+    return 4.7;                   // dx/dE [m/GeV]
+  }
+
+
+  /**
+   * Interface for muon energy loss.
+   *
+   * This interface provides for the various function object operators.
+   */
+  class JGeane {
+  public:
+   /**
+     * Get energy loss constant.
+     *
+     * \return         Energy loss due to ionisation [GeV/m]
+     */
+    virtual double getA() const = 0;
+
+
+    /**
+     * Get energy loss constant.
+     *
+     * \return         Energy loss due to pair production and Bremstrahlung [m^-1]
+     */
+    virtual double getB() const = 0;
+
+
+    /**
+     * Get energy of muon after specified distance.
+     *
+     * \param  E       Energy of muon [GeV]
+     * \param  dx      distance traveled [m]
+     * \return         Energy of muon [GeV]
+     */
+    virtual double getE(const double E, const double dx) const = 0;
+
+
+    /**
+     * Get distance traveled by muon.
+     *
+     * \param  E0      Energy of muon at start [GeV]
+     * \param  E1      Energy of muon at end   [GeV]
+     * \return         distance traveled [m]
+     */
+    virtual double getX(const double E0, 
+			const double E1) const = 0;
+
+
+    /**
+     * Energy of muon after specified distance.
+     *
+     * \param  E       Energy of muon [GeV]
+     * \param  dx      distance traveled [m]
+     * \return         Energy of muon [GeV]
+     */
+    double operator()(const double E, const double dx) const
+    {
+      return this->getE(E, dx);
+    }
+    
+
+    /**
+     * Range of muon.
+     *
+     * \param  E       Energy of muon [GeV]
+     * \return         range [m]
+     */
+    double operator()(const double E) const
+    {
+      return this->getX(E, 0.0);
+    }
+
+
+    /**
+     * Equivalent unit track length per unit shower energy and per unit track length.
+     *
+     * \return        equivalent unit track length [Gev^-1]
+     */
+    double operator()() const
+    {
+      return this->getB() * geanc();
+    }
+  };
+
+
+  /**
+   * Function object for the energy loss of the muon.\n
+   * The energy loss can be formulated as:
+   *
+   *     \f[ -\frac{dE}{dx}  =  a + bE\f]
+   *
+   * N.B:
+   * \f$a\f$ and \f$b\f$ are assumed constant (internal units m and GeV, respectively).
+   */
+  class JGeane_t :
+    public JGeane
+  {
+  public:
+    /**
+     * constructor
+     * \param  __a     Energy loss due to ionisation [GeV/m]
+     * \param  __b     Energy loss due to pair production and Bremstrahlung [m^-1]
+     */ 
+    JGeane_t(const double __a,
+	     const double __b) :
+      a(__a),
+      b(__b)
+    {}
+    
+
+    /**
+     * Get energy loss constant.
+     *
+     * \return         Energy loss due to ionisation [GeV/m]
+     */
+    virtual double getA() const override 
+    {
+      return a;
+    }
+
+
+    /**
+     * Get energy loss constant.
+     *
+     * \return         Energy loss due to pair production and Bremstrahlung [m^-1]
+     */
+    virtual double getB() const override 
+    {
+      return b;
+    }
+
+
+    /**
+     * Get energy of muon after specified distance.
+     *
+     * \param  E       Energy of muon [GeV]
+     * \param  dx      distance traveled [m]
+     * \return         Energy of muon [GeV]
+     */
+    virtual double getE(const double E, const double dx) const override 
+    {
+      const double y = (a/b + E) * exp(-b*dx)  -  a/b;
+
+      if (y > 0.0)
+	return y;
+      else
+	return 0.0;
+    }
+
+
+    /**
+     * Get distance traveled by muon.
+     *
+     * \param  E0      Energy of muon at start [GeV]
+     * \param  E1      Energy of muon at end   [GeV]
+     * \return         distance traveled [m]
+     */
+    virtual double getX(const double E0, 
+			const double E1) const override
+    {
+      return -log((a + b*E1) / (a+b*E0)) / b;
+    }
+
+  protected:
+    const double a;
+    const double b;
+  };
+
+
+  /**
+   * Function object for energy dependent energy loss of the muon.
+   *
+   * Approximate values of energy loss parameters taken from reference:
+   * Proceedings of ICRC 2001, "Precise parametrizations of muon energy losses in water",
+   * S. Klimushin, E. Bugaev and I. Sokalski.
+   */
+  class JGeaneWater : 
+    public JGeane,
+    protected std::map<double, JGeane_t>
+  {
+  public:
+    /**
+     * Default constructor.
+     */
+    JGeaneWater()
+    {
+      using namespace std;
+
+      this->insert(make_pair( 0.0e0,  JGeane_t( 2.30e-1 * DENSITY_SEA_WATER, 15.50e-4 * DENSITY_SEA_WATER)));
+      this->insert(make_pair(30.0e0,  JGeane_t( 2.67e-1 * DENSITY_SEA_WATER,  3.40e-4 * DENSITY_SEA_WATER)));
+      this->insert(make_pair(35.3e3,  JGeane_t(-6.50e-1 * DENSITY_SEA_WATER,  3.66e-4 * DENSITY_SEA_WATER)));
+    }
+    
+
+    /**
+     * Get energy loss constant.
+     *
+     * N.B. The return value corresponds to the low-energy regime.
+     *
+     * \return         Energy loss due to ionisation [GeV/m]
+     */
+    virtual double getA() const override 
+    {
+      return 2.30e-1 * DENSITY_SEA_WATER; //This is the value for low energy (<30 GeV), the value used for step(ds) and getRange())
+    }
+
+
+    /**
+     * Get energy loss constant.
+     *
+     * N.B. The return value corresponds to the medium-energy regime.
+     *
+     * \return         Energy loss due to pair production and Bremstrahlung [m^-1]
+     */
+    virtual double getB() const override 
+    {
+      return 3.40e-4 * DENSITY_SEA_WATER;
+    }
+
+
+    /**
+     * Get energy of muon after specified distance.
+     *
+     * \param  E       Energy of muon [GeV]
+     * \param  dx      distance traveled [m]
+     * \return         Energy of muon [GeV]
+     */
+    virtual double getE(const double E, const double dx) const override 
+    {
+      double E1 = E;
+      double x1 = dx;
+
+      if (E1 > MASS_MUON) {
+
+	const_iterator p = this->lower_bound(E1);
+
+	do {
+
+	  --p;
+
+	  const double x2 = p->second.getX(E1, p->first);
+
+	  if (x2 > x1) {
+	    return p->second.getE(E1, x1);
+	  }
+
+	  E1  = p->first;
+	  x1 -= x2;
+
+	} while (p != this->begin());
+      }
+
+      return E1;
+    }
+
+
+    /**
+     * Get distance traveled by muon.
+     *
+     * \param  E0      Energy of muon at start [GeV]
+     * \param  E1      Energy of muon at end   [GeV]
+     * \return         distance traveled [m]
+     */
+    virtual double getX(const double E0, 
+			const double E1) const override
+    {
+      double E  = E0;
+      double dx = 0.0;
+
+      if (E > MASS_MUON) {
+
+	const_iterator p = this->lower_bound(E);
+
+	do {
+
+	  --p;
+
+	  if (E1 > p->first) {
+	    return dx + p->second.getX(E, E1);
+	  }
+
+	  dx += p->second.getX(E, p->first);
+	  E   = p->first;
+
+	} while (p != this->begin());
+      }
+
+      return dx;
+    }
+  };
+
+
+  /**
+   * Function object for energy loss of muon in sea water.
+   */
+  static const JGeaneWater gWater;
+
+
+  /**
+   * Function object for energy loss of muon in rock.
+   */
+  static const JGeane_t    gRock(2.67e-1 * 0.9 * DENSITY_ROCK, 
+				 3.40e-4 * 1.2 * DENSITY_ROCK);
+
+}
+
+#endif