Core/MagneticField/SolenoidBFieldTests.cpp

0001 // This file is part of the ACTS project.
0002 //
0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project
0004 //
0005 // This Source Code Form is subject to the terms of the Mozilla Public
0006 // License, v. 2.0. If a copy of the MPL was not distributed with this
0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
0008
0009 #include <boost/test/unit_test.hpp>
0010
0011 #include "Acts/Definitions/Algebra.hpp"
0012 #include "Acts/Definitions/Units.hpp"
0013 #include "Acts/MagneticField/MagneticFieldContext.hpp"
0014 #include "Acts/MagneticField/SolenoidBField.hpp"
0015 #include "Acts/Utilities/Result.hpp"
0016 #include "ActsTests/CommonHelpers/FloatComparisons.hpp"
0017
0018 #include <cstddef>
0019
0020 using namespace Acts;
0021 using namespace Acts::UnitLiterals;
0022
0023 namespace ActsTests {
0024
0025 BOOST_AUTO_TEST_SUITE(MagneticFieldSuite)
0026
0027 BOOST_AUTO_TEST_CASE(TestSolenoidBField) {
0028   // Create a test context
0029   MagneticFieldContext mfContext = MagneticFieldContext();
0030
0031   SolenoidBField::Config cfg{};
0032   cfg.length = 5.8_m;
0033   cfg.radius = (2.56 + 2.46) * 0.5 * 0.5_m;
0034   cfg.nCoils = 1154;
0035   cfg.bMagCenter = 2_T;
0036   SolenoidBField bField(cfg);
0037
0038   auto cache = bField.makeCache(mfContext);
0039   CHECK_CLOSE_ABS(bField.getField({0, 0, 0}, cache).value(),
0040                   Vector3(0, 0, 2.0_T), 1e-6_T);
0041
0042   // std::ofstream outf("solenoid.csv");
0043   // outf << "x;y;z;B_x;B_y;B_z" << std::endl;
0044
0045   double tol = 1e-6;
0046   double tol_B = 1e-6_T;
0047   std::size_t steps = 20;
0048   for (std::size_t i = 0; i < steps; i++) {
0049     double r = 1.5 * cfg.radius / steps * i;
0050     BOOST_TEST_CONTEXT("r=" << r) {
0051       Vector3 B1 = bField.getField({r, 0, 0}, cache).value();
0052       Vector3 B2 = bField.getField({-r, 0, 0}, cache).value();
0053       CHECK_SMALL(B1.x(), tol);
0054       CHECK_SMALL(B1.y(), tol);
0055       BOOST_CHECK_GT(std::abs(B1.z()), tol_B);  // greater than zero
0056       // check symmetry: at z=0 it should be exactly symmetric
0057       CHECK_CLOSE_ABS(B1, B2, tol_B);
0058
0059       // at this point in r, go along the length
0060       for (std::size_t j = 0; j <= steps; j++) {
0061         // double z = cfg.L/steps * j - (cfg.L/2.);
0062         double z = (1.5 * cfg.length / 2.) / steps * j;
0063         BOOST_TEST_CONTEXT("z=" << z) {
0064           Vector3 B_zp_rp = bField.getField({r, 0, z}, cache).value();
0065           Vector3 B_zn_rp = bField.getField({r, 0, -z}, cache).value();
0066           Vector3 B_zp_rn = bField.getField({-r, 0, z}, cache).value();
0067           Vector3 B_zn_rn = bField.getField({-r, 0, -z}, cache).value();
0068
0069           // outf << r << ";0;" << z << ";" << B_zp_rp.x() << ";" <<
0070           // B_zp_rp.y() << ";" << B_zp_rp.z() << std::endl;
0071           // if(j>0) {
0072           // outf << r << ";0;" << -z << ";" << B_zn_rp.x() << ";" <<
0073           // B_zn_rp.y() << ";" << B_zn_rp.z() << std::endl;
0074           //}
0075           // if(i>0) {
0076           // outf << -r << ";0;" << z << ";" << B_zp_rn.x() << ";" <<
0077           // B_zp_rn.y() << ";" << B_zp_rn.z() << std::endl;
0078           //}
0079           // if(i>0 && j>0) {
0080           // outf << -r << ";0;" << -z << ";" << B_zn_rn.x() << ";" <<
0081           // B_zn_rn.y() << ";" << B_zn_rn.z() << std::endl;
0082           //}
0083
0084           // non-zero z
0085           BOOST_CHECK_GT(std::abs(B_zp_rp.z()), tol_B);
0086           BOOST_CHECK_GT(std::abs(B_zn_rp.z()), tol_B);
0087           BOOST_CHECK_GT(std::abs(B_zn_rn.z()), tol_B);
0088           BOOST_CHECK_GT(std::abs(B_zp_rn.z()), tol_B);
0089           if (i > 0) {
0090             // z components should be the same for +- r
0091             CHECK_CLOSE_ABS(B_zp_rp.z(), B_zp_rn.z(), tol_B);
0092             CHECK_CLOSE_ABS(B_zn_rp.z(), B_zn_rn.z(), tol_B);
0093             // x components should be exactly opposite
0094             CHECK_CLOSE_ABS(B_zp_rp.x(), -B_zp_rn.x(), tol_B);
0095             CHECK_CLOSE_ABS(B_zn_rp.x(), -B_zn_rn.x(), tol_B);
0096           }
0097           if (j > 0) {
0098             // z components should be the same for +- z
0099             CHECK_CLOSE_ABS(B_zp_rp.z(), B_zn_rp.z(), tol_B);
0100             CHECK_CLOSE_ABS(B_zp_rn.z(), B_zn_rn.z(), tol_B);
0101             // x components should be exactly opposite
0102             CHECK_CLOSE_ABS(B_zp_rp.x(), -B_zn_rp.x(), tol_B);
0103             CHECK_CLOSE_ABS(B_zp_rn.x(), -B_zn_rn.x(), tol_B);
0104           }
0105         }
0106       }
0107     }
0108   }
0109   // outf.close();
0110 }
0111
0112 BOOST_AUTO_TEST_SUITE_END()
0113
0114 }  // namespace ActsTests