From 57c4c609a249d519f43c661d2dd62a37c3179049 Mon Sep 17 00:00:00 2001 From: Alvaro Tolosa Delgado Date: Fri, 22 Nov 2024 11:27:00 +0100 Subject: [PATCH] functions to calculate wire position added --- DDRec/include/DDRec/DCH_info.h | 93 ++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) diff --git a/DDRec/include/DDRec/DCH_info.h b/DDRec/include/DDRec/DCH_info.h index 3d8513789..bccd49022 100644 --- a/DDRec/include/DDRec/DCH_info.h +++ b/DDRec/include/DDRec/DCH_info.h @@ -5,6 +5,7 @@ #include "DDRec/DetectorData.h" #include +#include "TVector3.h" namespace dd4hep { namespace rec { @@ -180,6 +181,16 @@ struct DCH_info_struct inline void BuildLayerDatabase(); inline void Show_DCH_info_database(std::ostream& io) const; + /// Check if outer volume is not zero (0 < Lhalf*rout), and if the database was filled + inline bool IsValid() const {return ((0 < Lhalf*rout) && (not IsDatabaseEmpty() ) ); } + //-------- + // The following functions are used in the digitization/reconstruction + // Notation: ILayer is the correlative number of the layer. Layer is reserved to number within a superlayer + inline DCH_layer CalculateILayerFromCellIDFields(int layer, int superlayer) const { DCH_layer ilayer = layer + (this->nlayersPerSuperlayer)*superlayer + 1; return ilayer;} + inline TVector3 Calculate_hitpos_to_wire_vector(int ilayer, int nphi, const TVector3& hit_position /*in cm*/) const; + inline TVector3 Calculate_wire_vector_ez (int ilayer, int nphi) const; + inline TVector3 Calculate_wire_z0_point (int ilayer, int nphi) const; + inline double Calculate_wire_phi_z0 (int ilayer, int nphi) const; }; typedef StructExtension DCH_info ; @@ -343,6 +354,88 @@ inline void DCH_info_struct::Show_DCH_info_database(std::ostream & oss) const } return; } + + +/////////////////////////////////////////////////////////////////////////////////////// +///// Ancillary functions for calculating the distance to the wire //////// +/////////////////////////////////////////////////////////////////////////////////////// + +inline TVector3 DCH_info_struct::Calculate_wire_vector_ez(int ilayer, int nphi) const { + auto& l = this->database.at(ilayer); + + // See original paper Hoshina et al, Computer Physics Communications 153 (2003) 3 + // eq. 2.9, for the definition of ez, vector along the wire + + // initialize some variables + int stereosign = l.StereoSign(); + double rz0 = l.radius_sw_z0; + double dphi = this->twist_angle; + // kappa is the same as in eq. 2.9 + double kappa = (1. / this->Lhalf) * tan(dphi / 2); + + //--- calculating wire position + // the points p1 and p2 correspond to the ends of the wire + + // point 1 + double x1 = rz0; // m + double y1 = -stereosign * rz0 * kappa * this->Lhalf; // m + double z1 = -this->Lhalf; // m + + TVector3 p1(x1, y1, z1); + + // point 2 + double x2 = rz0; // m + double y2 = stereosign * rz0 * kappa * this->Lhalf; // m + double z2 = this->Lhalf; // m + + TVector3 p2(x2, y2, z2); + + // calculate phi rotation of whole twisted tube, ie, rotation at z=0 + double phi_z0 = Calculate_wire_phi_z0(ilayer, nphi); + p1.RotateZ(phi_z0); + p2.RotateZ(phi_z0); + + //--- end calculating wire position + + return (p2 - p1).Unit(); +} + +inline TVector3 DCH_info_struct::Calculate_wire_z0_point(int ilayer, int nphi) const { + auto& l = this->database.at(ilayer); + double rz0 = l.radius_sw_z0; + TVector3 p1(rz0, 0, 0); + double phi_z0 = Calculate_wire_phi_z0(ilayer, nphi); + p1.RotateZ(phi_z0); + return p1; +} + +// calculate phi rotation of whole twisted tube, ie, rotation at z=0 +inline double DCH_info_struct::Calculate_wire_phi_z0(int ilayer, int nphi) const { + auto& l = this->database.at(ilayer); + int ncells = l.nwires / 2; + double phistep = TMath::TwoPi() / ncells; + double phi_z0 = (nphi + 0.25 * (l.layer % 2)) * phistep; + return phi_z0; +} + +/////////////////////////////////////////////////////////////////////////////////////// +/////////////////////// Calculate vector from hit position to wire ///////////////// +/////////////////////////////////////////////////////////////////////////////////////// +inline TVector3 DCH_info_struct::Calculate_hitpos_to_wire_vector(int ilayer, int nphi, const TVector3& hit_position /*in cm*/) const { + // Solution distance from a point to a line given here: + // https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Vector_formulation + TVector3 n = this->Calculate_wire_vector_ez(ilayer, nphi); + TVector3 a = this->Calculate_wire_z0_point(ilayer, nphi); + // Remember using cm as natural units of DD4hep consistently! + // TVector3 p {hit_position.x()*MM_TO_CM,hit_position.y()*MM_TO_CM,hit_position.z()*MM_TO_CM}; + + TVector3 a_minus_p = a - hit_position; + double a_minus_p_dot_n = a_minus_p.Dot(n); + TVector3 scaled_n = a_minus_p_dot_n * n; + //hit_to_wire_vector = a_minus_p - scaled_n; + return (a_minus_p - scaled_n); +} + }} // end namespace dd4hep::rec:: #endif // DDREC_DCH_INFO_H