/* University College London Dept of Physics Course in C++ 3C59 
| all rights reserved 2000 
|
| Utility: The Photomultiplier class
|
|   This file contains the implementation of the methods of the class
|
| Author: P.Clarke 
*/
#include <iostream>
#include <cmath>
#include "PhotoMultiplier.h"

#define M_PI 3.14159

//...........................................................
//Constructor

PhotoMultiplier::PhotoMultiplier( float centre, float dist, float window, float res )
{

  //Set the central position of the PMT
  m_centralAngle = centre ;
  
  //Set the acceptance angles 
  float halfAngle = ( atan( window/2.0/dist ) ) * 180.0 / M_PI ; 
  m_lolim = m_centralAngle - halfAngle;
  m_hilim = m_centralAngle + halfAngle ;

  //Set the resolution
  m_resolution = res ;

  // statistic counters
  m_totalEnergy = 0.;
  m_numberDetectedParticles = 0;
}


//..............................................................
// Method to fire a Photn at the detector

void PhotoMultiplier::tryit( Photon& p ) 
{
  //Does the supplied particle fall within this range

  if( (p.angle() > m_lolim) && (p.angle() < m_hilim) )
  {
    //Great - it is accepted. To keep the code simple I delegate the operations
    //to do with adding this particle to the totals to a private method
    this->assimilate( p ) ;
  }

} 

  


//....................................................................
// Private assimilate method

void PhotoMultiplier::assimilate( Photon& p ) 
{

  //First increment the number of detected particles
  m_numberDetectedParticles++ ;

  //Now smear the energy using the Gaussian class
  float detectedEnergy ;
  detectedEnergy = p.energy() + ( m_generator.gauss() * m_resolution );

  //Now add this smeared energy to the total
  m_totalEnergy += detectedEnergy ;

}



// ..............................
// Method to return total number of particles detected

int PhotoMultiplier::numberAccepted( )
{
  return m_numberDetectedParticles ;
}


// ..............................
// Method to return central angle

float PhotoMultiplier::angle( )
{
  return m_centralAngle ;
}


// ..............................
// Method to return average energy

float PhotoMultiplier::averageEnergy( )
{
  float average ;

  if( m_numberDetectedParticles > 0 )
  {
    average = m_totalEnergy / float(m_numberDetectedParticles) ;
  }
  else
  {
    average = 0. ;
  }

  return average ;
}