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InteractorTests.cpp
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1 // This file is part of the Acts project.
2 //
3 // Copyright (C) 2020 CERN for the benefit of the Acts project
4 //
5 // This Source Code Form is subject to the terms of the Mozilla Public
6 // License, v. 2.0. If a copy of the MPL was not distributed with this
7 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 
9 #include <boost/test/unit_test.hpp>
10 
11 #include "Acts/Geometry/GeometryContext.hpp"
12 #include "Acts/Material/HomogeneousSurfaceMaterial.hpp"
13 #include "Acts/Surfaces/PlaneSurface.hpp"
14 #include "Acts/Tests/CommonHelpers/FloatComparisons.hpp"
15 #include "Acts/Tests/CommonHelpers/PredefinedMaterials.hpp"
16 #include "ActsFatras/Kernel/detail/Interactor.hpp"
17 #include "ActsFatras/Selectors/SurfaceSelectors.hpp"
18 
19 #include <limits>
20 #include <random>
21 
22 using namespace ActsFatras;
23 
24 namespace {
25 
26 constexpr auto eps = std::numeric_limits<Particle::Scalar>::epsilon();
27 
28 struct MockPhysicsList {
29  double energyLoss = 0;
30 
31  template <typename generator_t>
32  bool operator()(generator_t &, const Acts::MaterialSlab &, Particle &particle,
33  std::vector<Particle> &generated) const {
34  generated.push_back(particle);
35  particle.correctEnergy(-energyLoss);
36  // break if particle is not alive anymore
37  return !particle;
38  }
39 };
40 
41 struct MockStepperState {
42  using Scalar = double;
43  using Vector3 = Acts::ActsVector<double, 3>;
44 
45  Vector3 position;
46  Scalar time;
47  Vector3 direction;
48  Scalar momentum;
49 };
50 
51 struct MockStepper {
52  using Scalar = MockStepperState::Scalar;
53  using Vector3 = MockStepperState::Vector3;
54 
55  auto position(MockStepperState &state) const { return state.position; }
56  auto time(MockStepperState &state) const { return state.time; }
57  auto direction(MockStepperState &state) const { return state.direction; }
58  auto momentum(MockStepperState &state) const { return state.momentum; }
59  void update(MockStepperState &state, const Vector3 &position,
60  const Vector3 &direction, Scalar momentum, Scalar time) {
61  state.position = position;
62  state.time = time;
63  state.direction = direction;
64  state.momentum = momentum;
65  }
66 };
67 
68 struct MockPropagatorState {
69  struct {
70  bool targetReached = false;
71  Acts::Surface *currentSurface = nullptr;
72  } navigation;
73  MockStepperState stepping;
74  Acts::GeometryContext geoContext;
75 };
76 
77 template <typename SurfaceSelector>
78 struct Fixture {
79  using Generator = std::ranlux48;
80  using Interactor =
81  typename ActsFatras::detail::Interactor<Generator, MockPhysicsList,
82  SurfaceSelector>;
83  using InteractorResult = typename Interactor::result_type;
84 
85  Generator generator;
86  std::shared_ptr<Acts::Surface> surface;
87  Interactor interactor;
88  InteractorResult result;
89  MockPropagatorState state;
90  MockStepper stepper;
91 
92  Fixture(double energyLoss, std::shared_ptr<Acts::Surface> surface_)
93  : generator(42), surface(std::move(surface_)) {
94  // use zero-mass to simplify the math
95  const auto particle =
96  Particle(Barcode().setVertexPrimary(12u).setParticle(3u),
97  Acts::PdgParticle::eProton, 0, 1)
98  .setPosition4(1, 2, 3, 4)
99  .setDirection(1, 0, 0)
100  .setAbsMomentum(100);
101  interactor.generator = &generator;
102  interactor.physics.energyLoss = energyLoss;
103  interactor.particle = particle;
104  state.navigation.currentSurface = surface.get();
105  state.stepping.position = particle.position();
106  state.stepping.time = particle.time();
107  state.stepping.direction = particle.unitDirection();
108  state.stepping.momentum = particle.absMomentum();
109  }
110 };
111 
112 // make a surface without material.
113 std::shared_ptr<Acts::Surface> makeEmptySurface() {
114  auto surface = Acts::Surface::makeShared<Acts::PlaneSurface>(
115  Acts::Vector3D(1, 2, 3), Acts::Vector3D(1, 0, 0));
116  return surface;
117 }
118 
119 // make a surface with material.
120 std::shared_ptr<Acts::Surface> makeMaterialSurface() {
121  auto surface = makeEmptySurface();
122  auto slab = Acts::Test::makePercentSlab();
123  surface->assignSurfaceMaterial(
124  std::make_shared<Acts::HomogeneousSurfaceMaterial>(std::move(slab)));
125  return surface;
126 }
127 
128 } // namespace
129 
130 BOOST_AUTO_TEST_SUITE(FatrasInteractor)
131 
132 BOOST_AUTO_TEST_CASE(HitsOnEmptySurface) {
133  Fixture<EverySurface> f(0.5, makeEmptySurface());
134 
135  // call interactor: surface selection -> one hit, no material -> no secondary
136  f.interactor(f.state, f.stepper, f.result);
137  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
138  BOOST_CHECK_EQUAL(f.result.hits.size(), 1u);
139  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
140 
141  // call interactor again: one more hit, still no secondary
142  f.interactor(f.state, f.stepper, f.result);
143  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
144  BOOST_CHECK_EQUAL(f.result.hits.size(), 2u);
145  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
146  BOOST_CHECK_EQUAL(f.result.hits[1].index(), 1u);
147 
148  // particle identity should be the same as the initial input
149  BOOST_CHECK_EQUAL(f.result.particle.particleId(),
150  f.interactor.particle.particleId());
151  BOOST_CHECK_EQUAL(f.result.particle.process(),
152  f.interactor.particle.process());
153  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.interactor.particle.pdg());
154  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.interactor.particle.charge());
155  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.interactor.particle.mass());
156  // particle energy has not changed since there were no interactions
157  CHECK_CLOSE_REL(f.result.particle.energy(), f.interactor.particle.energy(),
158  eps);
159 }
160 
161 BOOST_AUTO_TEST_CASE(HitsOnMaterialSurface) {
162  Fixture<EverySurface> f(0.5, makeMaterialSurface());
163 
164  // call interactor: surface selection -> one hit, material -> one secondary
165  f.interactor(f.state, f.stepper, f.result);
166  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 1u);
167  BOOST_CHECK_EQUAL(f.result.hits.size(), 1u);
168  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
169 
170  // call interactor again: one more hit, one more secondary
171  f.interactor(f.state, f.stepper, f.result);
172  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 2u);
173  BOOST_CHECK_EQUAL(f.result.hits.size(), 2u);
174  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
175  BOOST_CHECK_EQUAL(f.result.hits[1].index(), 1u);
176 
177  // particle identity should be the same as the initial input
178  BOOST_CHECK_EQUAL(f.result.particle.particleId(),
179  f.interactor.particle.particleId());
180  BOOST_CHECK_EQUAL(f.result.particle.process(),
181  f.interactor.particle.process());
182  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.interactor.particle.pdg());
183  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.interactor.particle.charge());
184  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.interactor.particle.mass());
185  // particle energy has changed due to interactions
186  CHECK_CLOSE_REL((f.result.particle.energy() + 1),
187  f.interactor.particle.energy(), eps);
188 }
189 
190 BOOST_AUTO_TEST_CASE(NoHitsEmptySurface) {
191  Fixture<NoSurface> f(0.5, makeEmptySurface());
192 
193  // call interactor: no surface sel. -> no hit, no material -> no secondary
194  f.interactor(f.state, f.stepper, f.result);
195  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
196  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
197 
198  // call interactor again: no hit, still no secondary
199  f.interactor(f.state, f.stepper, f.result);
200  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
201  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
202 
203  // particle identity should be the same as the initial input
204  BOOST_CHECK_EQUAL(f.result.particle.particleId(),
205  f.interactor.particle.particleId());
206  BOOST_CHECK_EQUAL(f.result.particle.process(),
207  f.interactor.particle.process());
208  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.interactor.particle.pdg());
209  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.interactor.particle.charge());
210  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.interactor.particle.mass());
211  // particle energy has not changed since there were no interactions
212  CHECK_CLOSE_REL(f.result.particle.energy(), f.interactor.particle.energy(),
213  eps);
214 }
215 
216 BOOST_AUTO_TEST_CASE(NoHitsMaterialSurface) {
217  Fixture<NoSurface> f(0.5, makeMaterialSurface());
218 
219  // call interactor: no surface sel. -> no hit, material -> one secondary
220  f.interactor(f.state, f.stepper, f.result);
221  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 1u);
222  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
223 
224  // call interactor again: still no hit, one more secondary
225  f.interactor(f.state, f.stepper, f.result);
226  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 2u);
227  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
228 
229  // particle identity should be the same as the initial input
230  BOOST_CHECK_EQUAL(f.result.particle.particleId(),
231  f.interactor.particle.particleId());
232  BOOST_CHECK_EQUAL(f.result.particle.process(),
233  f.interactor.particle.process());
234  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.interactor.particle.pdg());
235  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.interactor.particle.charge());
236  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.interactor.particle.mass());
237  // particle energy has changed due to interactions
238  CHECK_CLOSE_REL((f.result.particle.energy() + 1),
239  f.interactor.particle.energy(), eps);
240 }
241 
242 BOOST_AUTO_TEST_SUITE_END()