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