d6/d31/BetheHeitlerTests_8cpp_source.html

// This file is part of the Acts project.

//

// Copyright (C) 2018-2021 CERN for the benefit of the Acts project

//

// This Source Code Form is subject to the terms of the Mozilla Public

// License, v. 2.0. If a copy of the MPL was not distributed with this

// file, You can obtain one at http://mozilla.org/MPL/2.0/.


#include <boost/test/data/test_case.hpp>

#include <boost/test/unit_test.hpp>


#include "Acts/Definitions/Algebra.hpp"

#include "Acts/Definitions/Common.hpp"

#include "Acts/Definitions/PdgParticle.hpp"

#include "Acts/Tests/CommonHelpers/FloatComparisons.hpp"

#include "Acts/Tests/CommonHelpers/PredefinedMaterials.hpp"

#include "ActsFatras/EventData/Particle.hpp"

#include "ActsFatras/Physics/ElectroMagnetic/BetheHeitler.hpp"


#include <array>

#include <random>

#include <utility>


#include "Dataset.hpp"


using Generator = std::ranlux48;


BOOST_DATA_TEST_CASE(

    FatrasBetheHeitler,

    Dataset::momentumPhi* Dataset::momentumLambda* Dataset::momentumAbs ^

        Dataset::rngSeed,

    phi, lambda, p, seed) {

  Generator gen(seed);

  ActsFatras::Particle before =

      Dataset::makeParticle(Acts::PdgParticle::eElectron, phi, lambda, p);

  ActsFatras::Particle after = before;


  ActsFatras::BetheHeitler process;

  const auto outgoing = process(gen, Acts::Test::makeUnitSlab(), after);

  // energy loss changes momentum and energy

  BOOST_CHECK_LT(after.absoluteMomentum(), before.absoluteMomentum());

  BOOST_CHECK_LT(after.energy(), before.energy());

  // energy loss creates no new particles

  BOOST_CHECK_EQUAL(outgoing.size(), 1);

  BOOST_CHECK_GT(outgoing[0].absoluteMomentum(), 0.);

  BOOST_CHECK_EQUAL(outgoing[0].pathInX0(), 0.);

  BOOST_CHECK_EQUAL(outgoing[0].pathInL0(), 0.);


  // Get the four momenta

  Acts::Vector4 p0 = before.fourMomentum();

  Acts::Vector4 p1 = after.fourMomentum();

  Acts::Vector4 k = outgoing[0].fourMomentum();


  // Test for similar invariant masses

  Acts::Vector4 sum = p1 + k;

  double s = sum(Acts::eEnergy) * sum(Acts::eEnergy) -

             sum.template segment<3>(Acts::eMom0).norm() *

                 sum.template segment<3>(Acts::eMom0).norm();

  double s0 = p0(Acts::eEnergy) * p0(Acts::eEnergy) -

              p0.template segment<3>(Acts::eMom0).norm() *

                  p0.template segment<3>(Acts::eMom0).norm();

  CHECK_CLOSE_OR_SMALL(s, s0, 1e-2, 1e-2);

}