BeamSmearingUtils.cxx

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// SPDX-License-Identifier: LGPL-3.0-or-later
// SPDX-FileCopyrightText: Copyright CERN for the benefit of the SHiP
// Collaboration
 
#include "BeamSmearingUtils.h"
 
#include "TMath.h"
#include "TRandom.h"
 
std::pair<Double_t, Double_t> CalculateBeamOffset(Double_t smearBeam,
                                                  Double_t paintBeam) {
  Double_t dx = 0.0;
  Double_t dy = 0.0;
 
  // Gaussian beam smearing
  if (smearBeam > 0) {
    dx = gRandom->Gaus(0, smearBeam);
    dy = gRandom->Gaus(0, smearBeam);
  }
 
  // Uniform circular beam painting
  if (paintBeam > 0) {
    Double_t phi = gRandom->Uniform(0., 2 * TMath::Pi());
    dx += paintBeam * TMath::Cos(phi);
    dy += paintBeam * TMath::Sin(phi);
  }
 
  return {dx, dy};
}