VolumeMaterialInteraction.hpp

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// This file is part of the Acts project.
//
// Copyright (C) 2019-2020 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/.

#pragma once

#include "Acts/Definitions/Algebra.hpp"
#include "Acts/Definitions/PdgParticle.hpp"
#include "Acts/Geometry/TrackingVolume.hpp"
#include "Acts/Material/ISurfaceMaterial.hpp"
#include "Acts/Material/MaterialInteraction.hpp"
#include "Acts/Material/MaterialSlab.hpp"
#include "Acts/Surfaces/Surface.hpp"

namespace Acts {
namespace detail {

struct VolumeMaterialInteraction {
  InteractionVolume volume{};
  const Vector3 pos = Vector3::Zero();
  const double time = 0;
  const Vector3 dir = Vector3::Zero();
  const float qOverP = 0;
  const float absQ = 0;
  const float momentum = 0;
  const float mass = 0;
  const PdgParticle absPdg = eInvalid;
  const bool performCovarianceTransport = false;
  const Direction navDir;

  MaterialSlab slab;
  double pathCorrection = 0;

  template <typename propagator_state_t, typename stepper_t>
  VolumeMaterialInteraction(const TrackingVolume* vVolume,
                            const propagator_state_t& state,
                            const stepper_t& stepper)
      : volume(vVolume),
        pos(stepper.position(state.stepping)),
        time(stepper.time(state.stepping)),
        dir(stepper.direction(state.stepping)),
        qOverP(stepper.qOverP(state.stepping)),
        absQ(stepper.particleHypothesis(state.stepping).absoluteCharge()),
        momentum(stepper.absoluteMomentum(state.stepping)),
        mass(stepper.particleHypothesis(state.stepping).mass()),
        absPdg(stepper.particleHypothesis(state.stepping).absolutePdg()),
        performCovarianceTransport(state.stepping.covTransport),
        navDir(state.options.direction) {}

  template <typename propagator_state_t, typename navigator_t>
  bool evaluateMaterialSlab(const propagator_state_t& state,
                            const navigator_t& navigator) {
    pathCorrection = 0;
    if (navigator.currentVolume(state.navigation) != nullptr &&
        navigator.currentVolume(state.navigation)->volumeMaterial() !=
            nullptr) {
      slab = MaterialSlab(navigator.currentVolume(state.navigation)
                              ->volumeMaterial()
                              ->material(pos),
                          1);  // state.stepping.StepSize
    } else {
      slab = MaterialSlab();
    }
    return slab;
  }
};

}  // namespace detail
}  // end of namespace Acts