SiPixelUtils.cc

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#ifndef SI_PIXEL_TEMPLATE_STANDALONE
#include "CondFormats/SiPixelTransient/interface/SiPixelUtils.h"
#else
#include "SiPixelUtils.h"
#endif
 
#include <cmath>
 
namespace SiPixelUtils {
 
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
  float generic_position_formula(int size,                    
                                 int Q_f,                     
                                 int Q_l,                     
                                 float upper_edge_first_pix,  
                                 float lower_edge_last_pix,   
                                 float lorentz_shift,         
                                 float theThickness,          //detector thickness
                                 float cot_angle,             
                                 float pitch,                 
                                 bool first_is_big,           
                                 bool last_is_big,            
                                 float eff_charge_cut_low,    
                                 float eff_charge_cut_high,   
                                 float size_cut               
  ) {
    //cout<<" in PixelCPEGeneric:generic_position_formula - "<<endl; //dk
 
    float geom_center = 0.5f * (upper_edge_first_pix + lower_edge_last_pix);
 
    //--- The case of only one pixel in this projection is separate.  Note that
    //--- here first_pix == last_pix, so the average of the two is still the
    //--- center of the pixel.
    if (size == 1) {
      return geom_center;
    }
 
    //--- Width of the clusters minus the edge (first and last) pixels.
    //--- In the note, they are denoted x_F and x_L (and y_F and y_L)
    float W_inner = lower_edge_last_pix - upper_edge_first_pix;  // in cm
 
    //--- Predicted charge width from geometry
    float W_pred = theThickness * cot_angle  // geometric correction (in cm)
                   - lorentz_shift;          // (in cm) &&& check fpix!
 
    //cout<<" in PixelCPEGeneric:generic_position_formula - "<<W_inner<<" "<<W_pred<<endl; //dk
 
    //--- Total length of the two edge pixels (first+last)
    float sum_of_edge = 2.0f;
    if (first_is_big)
      sum_of_edge += 1.0f;
    if (last_is_big)
      sum_of_edge += 1.0f;
 
    //--- The `effective' charge width -- particle's path in first and last pixels only
    float W_eff = std::abs(W_pred) - W_inner;
 
    //--- If the observed charge width is inconsistent with the expectations
    //--- based on the track, do *not* use W_pred-W_innner.  Instead, replace
    //--- it with an *average* effective charge width, which is the average
    //--- length of the edge pixels.
    //
    //  bool usedEdgeAlgo = false;
    if ((size >= size_cut) || ((W_eff / pitch < eff_charge_cut_low) | (W_eff / pitch > eff_charge_cut_high))) {
      W_eff = pitch * 0.5f * sum_of_edge;  // ave. length of edge pixels (first+last) (cm)
                                           //  usedEdgeAlgo = true;
    }
 
    //--- Finally, compute the position in this projection
    float Qdiff = Q_l - Q_f;
    float Qsum = Q_l + Q_f;
 
    //--- Temporary fix for clusters with both first and last pixel with charge = 0
    if (Qsum == 0)
      Qsum = 1.0f;
 
    //float hit_pos = geom_center + 0.5f*(Qdiff/Qsum) * W_eff + half_lorentz_shift;
    float hit_pos = geom_center + 0.5f * (Qdiff / Qsum) * W_eff;
 
    return hit_pos;
  }
 
}  // namespace SiPixelUtils