Cons.cc

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#include "DetectorDescription/Core/src/Cons.h"
#include "CLHEP/Units/GlobalSystemOfUnits.h"
#include "CLHEP/Units/GlobalPhysicalConstants.h"
#include <cmath>
#include <ostream>

DDI::Cons::Cons(double zhalf,
     double rInMinusZ,
     double rOutMinusZ,
     double rInPlusZ,
     double rOutPlusZ,
     double startPhi,
     double deltaPhi)
 : Solid(ddcons)      
{
  p_.push_back(zhalf);
  p_.push_back(rInMinusZ);
  p_.push_back(rOutMinusZ);
  p_.push_back(rInPlusZ);
  p_.push_back(rOutPlusZ);
  p_.push_back(startPhi);
  p_.push_back(deltaPhi);

}    


void DDI::Cons::stream(std::ostream & os) const
{
   os << " zhalf=" << p_[0]/cm
      << " rIn-Z=" << p_[1]/cm
      << " rOut-Z=" << p_[2]/cm
      << " rIn+Z=" << p_[3]/cm
      << " rOut+Z=" << p_[4]/cm
      << " startPhi=" << p_[5]/deg
      << " deltaPhi=" << p_[6]/deg;
}

double DDI::Cons::volume() const
{
  /* zhalf is the half length of the cone,
     phiTo is always clockwise rotated from phiFrom 
     rInMinusZ is always smaller than rOutMinusZ (same for r*PlusZ)
     They are the distances relative to the rotation axes */

  /* calculation normalize from 0 to z */

  /* The function f=rInMinusZ+((rInPlusZ-rInMinusZ)/z)*x defines
     the radius of the the rotation from 0 to z. Raised to the power
     of 2 integrated on x from 0 to z. Multiplied by pi, gives the
     volume that needs to substracted from the other volume */ 
     
  /* f^2=rInMinusZ*rInMinusZ+2*rInMinusZ*((rInPlusZ-rInMinusZ)/z)*x+((rInPlusZ-rInMinusZ)*(rInPlusZ-rInMinusZ)*x*x)/(z*z) */

  /* primitive of f^2 is: rInMinusZ*rInMinusZ*x+rInMinusZ*((rInPlusZ-rInMinusZ)/z)*(x*x)+(rInPlusZ-rInMinusZ)*(rInPlusZ-rInMinusZ)*(x*x*x)/(3*z*z) */

  /*integration from 0 to z yields: pi*( rInMinusZ*rInMinusZ*z+rInMinusZ*(rInPlusZ-rInMinusZ)*z+((rInPlusZ-rInMinusZ)*(rInPlusZ-rInMinusZ)*z)/(3) ) */

   double zhalf=p_[0]; 
   double rInMinusZ=p_[1]; 
   double rOutMinusZ=p_[2]; 
   double rInPlusZ=p_[3]; 
   double rOutPlusZ=p_[4];
   //double phiFrom=p_[5]/rad;
   double deltaPhi=fabs(p_[6]/rad); 
   double z=2*zhalf;

  double volume1=pi*(rInPlusZ*rInPlusZ+rInMinusZ*rInMinusZ+rInMinusZ*rInPlusZ)*z/3;

  double volume2=pi*(rOutPlusZ*rOutPlusZ+rOutMinusZ*rOutMinusZ+rOutMinusZ*rOutPlusZ)*z/3;
  
  double slice=deltaPhi/(2*pi);
  double volume=slice*(volume2-volume1);

  return volume;

}