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SimulationActorTests.cpp
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1 // This file is part of the Acts project.
2 //
3 // Copyright (C) 2021 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/Definitions/Algebra.hpp"
12 #include "Acts/Definitions/PdgParticle.hpp"
13 #include "Acts/Definitions/Units.hpp"
14 #include "Acts/Geometry/GeometryContext.hpp"
15 #include "Acts/Material/HomogeneousSurfaceMaterial.hpp"
16 #include "Acts/Material/MaterialSlab.hpp"
17 #include "Acts/Propagator/ConstrainedStep.hpp"
18 #include "Acts/Surfaces/PlaneSurface.hpp"
19 #include "Acts/Surfaces/Surface.hpp"
20 #include "Acts/Tests/CommonHelpers/FloatComparisons.hpp"
21 #include "Acts/Tests/CommonHelpers/PredefinedMaterials.hpp"
22 #include "Acts/Utilities/Logger.hpp"
23 #include "ActsFatras/EventData/Barcode.hpp"
24 #include "ActsFatras/EventData/Particle.hpp"
25 #include "ActsFatras/EventData/ProcessType.hpp"
26 #include "ActsFatras/Kernel/detail/SimulationActor.hpp"
27 #include "ActsFatras/Selectors/SurfaceSelectors.hpp"
28 
29 #include <array>
30 #include <cmath>
31 #include <cstddef>
32 #include <cstdint>
33 #include <limits>
34 #include <memory>
35 #include <random>
36 #include <utility>
37 #include <vector>
38 
39 using namespace Acts::UnitLiterals;
40 using namespace ActsFatras;
41 
42 namespace {
43 
44 constexpr auto tol = 4 * std::numeric_limits<Particle::Scalar>::epsilon();
45 constexpr auto inf = std::numeric_limits<Particle::Scalar>::infinity();
46 
47 struct MockDecay {
48  Particle::Scalar properTimeLimit = inf;
49 
50  template <typename generator_t>
51  constexpr Particle::Scalar generateProperTimeLimit(
52  generator_t & /*generator*/, const Particle &particle) const {
53  return particle.properTime() + properTimeLimit;
54  }
55  template <typename generator_t>
56  constexpr std::array<Particle, 0> run(generator_t & /*generator*/,
57  const Particle & /*particle*/) const {
58  return {};
59  }
60 };
61 
62 struct MockInteractionList {
63  struct Selection {
64  double x0Limit = std::numeric_limits<double>::infinity();
65  double l0Limit = std::numeric_limits<double>::infinity();
66  size_t x0Process = SIZE_MAX;
67  size_t l0Process = SIZE_MAX;
68  };
69 
70  double energyLoss = 0;
71 
72  template <typename generator_t>
73  bool runContinuous(generator_t & /*generator*/,
74  const Acts::MaterialSlab & /*slab*/, Particle &particle,
75  std::vector<Particle> &generated) const {
76  generated.push_back(particle);
77  particle.correctEnergy(-energyLoss);
78  // break if particle is not alive anymore
79  return !particle.isAlive();
80  }
81 
82  template <typename generator_t>
83  Selection armPointLike(generator_t & /*generator*/,
84  const Particle & /*particle*/) const {
85  return {};
86  }
87 
88  template <typename generator_t>
89  bool runPointLike(generator_t & /*generator*/, size_t /*processIndex*/,
90  Particle & /*particle*/,
91  std::vector<Particle> & /*generated*/) const {
92  return false;
93  }
94 };
95 
96 struct MockStepperState {
97  using Scalar = Acts::ActsScalar;
98  using Vector3 = Acts::ActsVector<3>;
99 
100  Vector3 pos = Vector3::Zero();
101  Scalar time = 0;
102  Vector3 dir = Vector3::Zero();
103  Scalar p = 0;
104 };
105 
106 struct MockStepper {
107  using State = MockStepperState;
108  using Scalar = MockStepperState::Scalar;
109  using Vector3 = MockStepperState::Vector3;
110 
111  auto position(const State &state) const { return state.pos; }
112  auto time(const State &state) const { return state.time; }
113  auto direction(const State &state) const { return state.dir; }
114  auto absoluteMomentum(const State &state) const { return state.p; }
115  void update(State &state, const Vector3 &pos, const Vector3 &dir, Scalar qop,
116  Scalar time) {
117  state.pos = pos;
118  state.time = time;
119  state.dir = dir;
120  state.p = 1 / qop;
121  }
122  void setStepSize(State & /*state*/, double /*stepSize*/,
123  Acts::ConstrainedStep::Type /*stype*/) const {}
124 };
125 
126 struct MockNavigatorState {
127  bool targetReached = false;
128  Acts::Surface *startSurface = nullptr;
129  Acts::Surface *currentSurface = nullptr;
130 };
131 
132 struct MockNavigator {
133  bool targetReached(const MockNavigatorState &state) const {
134  return state.targetReached;
135  }
136 
137  const Acts::Surface *startSurface(const MockNavigatorState &state) const {
138  return state.startSurface;
139  }
140 
141  const Acts::Surface *currentSurface(const MockNavigatorState &state) const {
142  return state.currentSurface;
143  }
144 };
145 
146 struct MockPropagatorState {
147  MockNavigatorState navigation;
148  MockStepperState stepping;
149  Acts::GeometryContext geoContext;
150 };
151 
152 template <typename SurfaceSelector>
153 struct Fixture {
154  using Generator = std::ranlux48;
155  using Actor = typename ActsFatras::detail::SimulationActor<
156  Generator, MockDecay, MockInteractionList, SurfaceSelector>;
157  using Result = typename Actor::result_type;
158 
159  // reference information for initial particle
160  Barcode pid = Barcode().setVertexPrimary(12u).setParticle(3u);
161  ProcessType proc = ProcessType::eUndefined;
162  Acts::PdgParticle pdg = Acts::PdgParticle::eProton;
163  Particle::Scalar q = 1_e;
164  Particle::Scalar m = 1_GeV;
165  Particle::Scalar p = 1_GeV;
166  Particle::Scalar e;
167  Generator generator;
168  std::shared_ptr<Acts::Surface> surface;
169  Actor actor;
170  Result result;
171  MockPropagatorState state;
172  MockStepper stepper;
173  MockNavigator navigator;
174 
175  Fixture(double energyLoss, std::shared_ptr<Acts::Surface> surface_)
176  : e(std::hypot(m, p)), generator(42), surface(std::move(surface_)) {
177  const auto particle = Particle(pid, pdg, q, m)
178  .setProcess(proc)
179  .setPosition4(1_mm, 2_mm, 3_mm, 4_ns)
180  .setDirection(1, 0, 0)
181  .setAbsoluteMomentum(p);
182  actor.generator = &generator;
183  actor.interactions.energyLoss = energyLoss;
184  actor.initialParticle = particle;
185  state.navigation.currentSurface = surface.get();
186  state.stepping.pos = particle.position();
187  state.stepping.time = particle.time();
188  state.stepping.dir = particle.direction();
189  state.stepping.p = particle.absoluteMomentum();
190  }
191 };
192 
193 // make a surface without material.
194 std::shared_ptr<Acts::Surface> makeEmptySurface() {
195  auto surface = Acts::Surface::makeShared<Acts::PlaneSurface>(
196  Acts::Vector3(1, 2, 3), Acts::Vector3(1, 0, 0));
197  return surface;
198 }
199 
200 // make a surface with 1% X0/L0 material.
201 std::shared_ptr<Acts::Surface> makeMaterialSurface() {
202  auto surface = makeEmptySurface();
203  auto slab = Acts::Test::makeUnitSlab();
204  surface->assignSurfaceMaterial(
205  std::make_shared<Acts::HomogeneousSurfaceMaterial>(slab));
206  return surface;
207 }
208 
209 } // namespace
210 
211 BOOST_AUTO_TEST_SUITE(FatrasSimulationActor)
212 
213 BOOST_AUTO_TEST_CASE(HitsOnEmptySurface) {
214  Fixture<EverySurface> f(125_MeV, makeEmptySurface());
215 
216  // input reference check
217  BOOST_CHECK_EQUAL(f.actor.initialParticle.particleId(), f.pid);
218  BOOST_CHECK_EQUAL(f.actor.initialParticle.process(), f.proc);
219  BOOST_CHECK_EQUAL(f.actor.initialParticle.pdg(), f.pdg);
220  BOOST_CHECK_EQUAL(f.actor.initialParticle.mass(), f.m);
221  BOOST_CHECK_EQUAL(f.actor.initialParticle.absoluteMomentum(), f.p);
222  BOOST_CHECK_EQUAL(f.actor.initialParticle.energy(), f.e);
223 
224  // call.actor: surface selection -> one hit, no material -> no secondary
225  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
226  BOOST_CHECK(f.result.isAlive);
227  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
228  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
229  BOOST_CHECK_EQUAL(f.result.hits.size(), 1u);
230  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
231  // proper time must be non-NaN, but is zero since no time has passed
232  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
233  // empty surfaces adds no material
234  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 0);
235  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 0);
236  // no processes are configured, so none can be selected
237  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
238  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
239  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
240  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
241  // check consistency between particle and stepper state
242  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
243  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
244  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
245  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
246 
247  // call.actor again: one more hit, still no secondary
248  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
249  BOOST_CHECK(f.result.isAlive);
250  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
251  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
252  BOOST_CHECK_EQUAL(f.result.hits.size(), 2u);
253  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
254  BOOST_CHECK_EQUAL(f.result.hits[1].index(), 1u);
255  // proper time must be non-NaN, but is zero since no time
256  // has passed
257  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
258  // empty surfaces adds no material
259  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 0);
260  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 0);
261  // no processes are configured, so none can be selected
262  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
263  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
264  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
265  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
266  // check consistency between particle and stepper state
267  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
268  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
269  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
270  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
271 
272  // particle identity should be the same as the initial input
273  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
274  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
275  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
276  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
277  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
278 }
279 
280 BOOST_AUTO_TEST_CASE(HitsOnMaterialSurface) {
281  Fixture<EverySurface> f(125_MeV, makeMaterialSurface());
282 
283  // input reference check
284  BOOST_CHECK_EQUAL(f.actor.initialParticle.particleId(), f.pid);
285  BOOST_CHECK_EQUAL(f.actor.initialParticle.process(), f.proc);
286  BOOST_CHECK_EQUAL(f.actor.initialParticle.pdg(), f.pdg);
287  BOOST_CHECK_EQUAL(f.actor.initialParticle.mass(), f.m);
288  BOOST_CHECK_EQUAL(f.actor.initialParticle.absoluteMomentum(), f.p);
289  BOOST_CHECK_EQUAL(f.actor.initialParticle.energy(), f.e);
290 
291  // call.actor: surface selection -> one hit, material -> one secondary
292  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
293  BOOST_CHECK(f.result.isAlive);
294  CHECK_CLOSE_REL(f.result.particle.energy(), f.e - 125_MeV, tol);
295  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 1u);
296  BOOST_CHECK_EQUAL(f.result.hits.size(), 1u);
297  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
298  // proper time must be non-NaN, but is zero since no time
299  // has passed
300  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
301  // test material is a unit slab
302  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 1);
303  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 1);
304  // no processes are configured, so none can be selected
305  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
306  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
307  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
308  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
309  // check consistency between particle and stepper state
310  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
311  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
312  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
313  CHECK_CLOSE_REL(f.state.stepping.p, f.result.particle.absoluteMomentum(),
314  tol);
315 
316  // call.actor again: one more hit, one more secondary
317  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
318  BOOST_CHECK(f.result.isAlive);
319  CHECK_CLOSE_REL(f.result.particle.energy(), f.e - 250_MeV, tol);
320  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 2u);
321  BOOST_CHECK_EQUAL(f.result.hits.size(), 2u);
322  BOOST_CHECK_EQUAL(f.result.hits[0].index(), 0u);
323  BOOST_CHECK_EQUAL(f.result.hits[1].index(), 1u);
324  // proper time must be non-NaN, but is zero since no time
325  // has passed
326  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
327  // test material is a unit slab that was passed twice
328  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 2);
329  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 2);
330  // no processes are configured, so none can be selected
331  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
332  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
333  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
334  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
335  // check consistency between particle and stepper state
336  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
337  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
338  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
339  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
340 
341  // particle identity should be the same as the initial input
342  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
343  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
344  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
345  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
346  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
347 }
348 
349 BOOST_AUTO_TEST_CASE(NoHitsEmptySurface) {
350  Fixture<NoSurface> f(125_MeV, makeEmptySurface());
351 
352  // input reference check
353  BOOST_CHECK_EQUAL(f.actor.initialParticle.particleId(), f.pid);
354  BOOST_CHECK_EQUAL(f.actor.initialParticle.process(), f.proc);
355  BOOST_CHECK_EQUAL(f.actor.initialParticle.pdg(), f.pdg);
356  BOOST_CHECK_EQUAL(f.actor.initialParticle.mass(), f.m);
357  BOOST_CHECK_EQUAL(f.actor.initialParticle.absoluteMomentum(), f.p);
358  BOOST_CHECK_EQUAL(f.actor.initialParticle.energy(), f.e);
359 
360  // call.actor: no surface sel. -> no hit, no material -> no secondary
361  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
362  BOOST_CHECK(f.result.isAlive);
363  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
364  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
365  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
366  // proper time must be non-NaN, but is zero since no time
367  // has passed
368  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
369  // empty surfaces adds no material
370  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 0);
371  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 0);
372  // no processes are configured, so none can be selected
373  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
374  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
375  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
376  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
377  // check consistency between particle and stepper state
378  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
379  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
380  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
381  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
382 
383  // call.actor again: no hit, still no secondary
384  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
385  BOOST_CHECK(f.result.isAlive);
386  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
387  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 0u);
388  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
389  // proper time must be non-NaN, but is zero since no time
390  // has passed
391  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
392  // empty surfaces adds no material
393  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 0);
394  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 0);
395  // no processes are configured, so none can be selected
396  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
397  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
398  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
399  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
400  // check consistency between particle and stepper state
401  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
402  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
403  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
404  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
405 
406  // particle identity should be the same as the initial input
407  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
408  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
409  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
410  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
411  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
412 }
413 
414 BOOST_AUTO_TEST_CASE(NoHitsMaterialSurface) {
415  Fixture<NoSurface> f(125_MeV, makeMaterialSurface());
416 
417  // call.actor: no surface sel. -> no hit, material -> one secondary
418  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
419  BOOST_CHECK(f.result.isAlive);
420  CHECK_CLOSE_REL(f.result.particle.energy(), f.e - 125_MeV, tol);
421  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 1u);
422  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
423  // proper time must be non-NaN, but is zero since no time
424  // has passed
425  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
426  // test material is a unit slab
427  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 1);
428  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 1);
429  // no processes are configured, so none can be selected
430  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
431  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
432  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
433  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
434  // check consistency between particle and stepper state
435  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
436  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
437  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
438  CHECK_CLOSE_REL(f.state.stepping.p, f.result.particle.absoluteMomentum(),
439  tol);
440 
441  // call.actor again: still no hit, one more secondary
442  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
443  BOOST_CHECK(f.result.isAlive);
444  CHECK_CLOSE_REL(f.result.particle.energy(), f.e - 250_MeV, tol);
445  BOOST_CHECK_EQUAL(f.result.generatedParticles.size(), 2u);
446  BOOST_CHECK_EQUAL(f.result.hits.size(), 0u);
447  // proper time must be non-NaN, but is zero since no time
448  // has passed
449  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0);
450  // test material is a unit slab that was passed twice
451  BOOST_CHECK_EQUAL(f.result.particle.pathInX0(), 2);
452  BOOST_CHECK_EQUAL(f.result.particle.pathInL0(), 2);
453  // no processes are configured, so none can be selected
454  BOOST_CHECK_EQUAL(f.result.x0Limit, inf);
455  BOOST_CHECK_EQUAL(f.result.x0Process, SIZE_MAX);
456  BOOST_CHECK_EQUAL(f.result.l0Limit, inf);
457  BOOST_CHECK_EQUAL(f.result.l0Process, SIZE_MAX);
458  // check consistency between particle and stepper state
459  BOOST_CHECK_EQUAL(f.state.stepping.pos, f.result.particle.position());
460  BOOST_CHECK_EQUAL(f.state.stepping.time, f.result.particle.time());
461  BOOST_CHECK_EQUAL(f.state.stepping.dir, f.result.particle.direction());
462  BOOST_CHECK_EQUAL(f.state.stepping.p, f.result.particle.absoluteMomentum());
463 
464  // particle identity should be the same as the initial input
465  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
466  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
467  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
468  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
469  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
470 }
471 
472 BOOST_AUTO_TEST_CASE(Decay) {
473  // configure no energy loss for the decay tests
474  Fixture<NoSurface> f(0_GeV, makeEmptySurface());
475 
476  // inverse Lorentz factor for proper time dilation: 1/gamma = m/E
477  const auto gammaInv = f.m / f.e;
478 
479  // first step w/ defaults leaves particle alive
480  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
481  BOOST_CHECK(f.result.isAlive);
482  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
483  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
484  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
485  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
486  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
487  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
488  BOOST_CHECK_EQUAL(f.result.particle.properTime(), 0_ns);
489 
490  // second step w/ defaults increases proper time
491  f.state.stepping.time += 1_ns;
492  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
493  BOOST_CHECK(f.result.isAlive);
494  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
495  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
496  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
497  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
498  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
499  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
500  CHECK_CLOSE_REL(f.result.particle.properTime(), gammaInv * 1_ns, tol);
501 
502  // third step w/ proper time limit decays the particle
503  f.state.stepping.time += 1_ns;
504  f.result.properTimeLimit = f.result.particle.properTime() + gammaInv * 0.5_ns;
505  f.actor(f.state, f.stepper, f.navigator, f.result, Acts::getDummyLogger());
506  BOOST_CHECK(not f.result.isAlive);
507  BOOST_CHECK_EQUAL(f.result.particle.particleId(), f.pid);
508  BOOST_CHECK_EQUAL(f.result.particle.process(), f.proc);
509  BOOST_CHECK_EQUAL(f.result.particle.pdg(), f.pdg);
510  BOOST_CHECK_EQUAL(f.result.particle.charge(), f.q);
511  BOOST_CHECK_EQUAL(f.result.particle.mass(), f.m);
512  CHECK_CLOSE_REL(f.result.particle.energy(), f.e, tol);
513  CHECK_CLOSE_REL(f.result.particle.properTime(), gammaInv * 2_ns, tol);
514 }
515 
516 BOOST_AUTO_TEST_SUITE_END()