Acts/Seeding/GbtsSeedFit.hpp

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 #pragma once
0010
0011 #include "Acts/Definitions/Algebra.hpp"
0012 #include "Acts/Definitions/TrackParametrization.hpp"
0013
0014 #include <optional>
0015
0016 namespace Acts::Experimental {
0017
0018 /// Fit of the GBTS tracking filter to a seed, at its innermost space point.
0019 struct GbtsSeedFit final {
0020   /// Position at the innermost space point.
0021   Vector3 position{Vector3::Zero()};
0022   /// Azimuthal angle of the direction.
0023   double phi{0};
0024   /// dz/dr of the direction.
0025   double cotTheta{0};
0026   /// Signed curvature in the transverse plane.
0027   double curvature{0};
0028 };
0029
0030 /// Estimate free track parameters from the fit of the GBTS tracking filter.
0031 ///
0032 /// The momentum uses the field bending the seed in the transverse plane,
0033 /// Bz - cot(theta) * Bt, with Bt the transverse field along the seed.
0034 ///
0035 /// @param fit Fit of the tracking filter
0036 /// @param bField Magnetic field at a point along the seed
0037 /// @return Free track parameters, or nothing without a bending field
0038 std::optional<FreeVector> freeParametersFromGbtsSeedFit(const GbtsSeedFit& fit,
0039                                                         const Vector3& bField);
0040
0041 }  // namespace Acts::Experimental