Add data extension class for FCCee Drift Chamber

DDRec/include/DDRec/DCH_info.h

+#ifndef DCH_INFO_H_INCLUDED
+#define DCH_INFO_H_INCLUDED
+
+#include "TMath.h"
+
+#include "DDRec/DetectorData.h"
+#include <map>
+
+namespace dd4hep {  namespace rec {
+
+
+/* Data structure to store DCH geometry parameters
+ *
+ * Global parameters are members of this class
+ *
+ * Parameters of each layer are stored in the helper
+ * class DCH_info_layer.
+ *
+ * The member database is a container which stores one
+ * DCH_info_layer object per layer.
+ *
+ * To use this class, instantiate an object and define the global parameters.
+ * Then call the method BuildLayerDatabase, which calculates
+ * the parameters of each layer based on the global parameters.
+ *
+ * @author A. Tolosa Delgado, CERN
+ * @date April 2024
+ * @version Drift chamber v2
+ *
+ */
+struct DCH_info_struct
+{
+public:
+    // use alias of types to show more clearly what the variable is
+    // if everything is double, the code is not readable
+    /// type for layer number
+    using DCH_layer = int;
+    /// tpye for lengths
+    using DCH_length_t = double;
+    /// tpye for angles
+    using DCH_angle_t = double;
+    /// Half length of the active volume
+    DCH_length_t Lhalf = {0};
+    /// Inner radius of the active volume
+    DCH_length_t rin = {0};
+    /// Outer radius of the active volume
+    DCH_length_t rout = {0};
+
+    /// Inner guard wires radius
+    DCH_length_t guard_inner_r_at_z0 = {0};
+    /// Outer guard wires radius
+    DCH_length_t guard_outer_r_at_zL2 = {0};
+
+    /// number of cells of first layer
+    int ncell0 = {0};
+    /// increment the number of cells for each superlayer as:
+    ///   ncells(ilayer) = dch_ncell0 + increment*superlayer(ilayer)
+    ///   See DCH_info::Get_nsuperlayer_minus_1(ilayer)
+    int ncell_increment = {0};
+
+    /// cells within the same layer may be grouped into sectors, not in use atm
+    int ncell_per_sector = {0};
+
+    /// input number of layers in each superlayer
+    DCH_layer nlayersPerSuperlayer = {0};
+    /// input number of superlayers
+    /// superlayer is an abstract level of grouping layers used to
+    /// parametrize the increment of cells in each layer
+    DCH_layer nsuperlayers = {0};
+    /// Calculated as dch_nlayersPerSuperlayer * dch_nsuperlayers
+    DCH_layer nlayers = {0};
+
+    /// global twist angle
+    /// alternating layers will change its sign
+    DCH_angle_t  twist_angle = {0};
+
+    /// Cell width for the first layer
+    double first_width = {0};
+    /// Cell radius for the first layer
+    DCH_length_t first_sense_r = {0};
+
+    void Set_lhalf(DCH_length_t _dch_Lhalf){Lhalf=_dch_Lhalf;}
+    void Set_rin  (DCH_length_t _dch_rin  ){rin  = _dch_rin; }
+    void Set_rout (DCH_length_t _dch_rout ){rout = _dch_rout;}
+
+    void Set_guard_rin_at_z0  (DCH_length_t _dch_rin_z0_guard  ){guard_inner_r_at_z0  = _dch_rin_z0_guard;   }
+    void Set_guard_rout_at_zL2(DCH_length_t _dch_rout_zL2_guard){guard_outer_r_at_zL2 = _dch_rout_zL2_guard; }
+
+    void Set_ncell0              (int _ncell0              ){ncell0               = _ncell0;              }
+    void Set_ncell_increment     (int _ncell_increment     ){ncell_increment      = _ncell_increment;     }
+
+    void Set_nlayersPerSuperlayer(int _nlayersPerSuperlayer){nlayersPerSuperlayer = _nlayersPerSuperlayer;}
+    void Set_nsuperlayers        (int _nsuperlayers        ){nsuperlayers         = _nsuperlayers;        }
+
+    void Set_ncell_per_sector(int _ncell_per_sector){ncell_per_sector = _ncell_per_sector;}
+
+    void Set_twist_angle (DCH_length_t _dch_twist_angle ){twist_angle = _dch_twist_angle;}
+
+    void Set_first_width  (double _first_width  ){first_width   = _first_width;   }
+    void Set_first_sense_r(double _first_sense_r){first_sense_r = _first_sense_r; }
+
+
+    /// Get number of cells in a given layer
+    ///   ncells = number of wires/2
+    int Get_ncells(int ilayer){return database.at(ilayer).nwires/2;}
+
+    /// Get phi width for the twisted tube and the step (phi distance between cells)
+    DCH_angle_t Get_phi_width(int ilayer){return (TMath::TwoPi()/Get_ncells(ilayer))*dd4hep::rad;}
+
+    /// phi positioning, adding offset for odd ilayers
+    /// there is a staggering in phi for alternating layers, 0.25*cell_phi_width*(ilayer%2);
+    DCH_angle_t Get_cell_phi_angle(int ilayer, int nphi){ return (Get_phi_width(ilayer) * (nphi + 0.25*(ilayer%2)));}
+
+    /// calculate superlayer for a given ilayer.
+    /// WARNING: division of integers on purpose!
+    int Get_nsuperlayer_minus_1(int ilayer){ return int((ilayer-1)/nlayersPerSuperlayer);}
+
+    /// Calculate radius at z=L/2 given at z=0
+    DCH_length_t Radius_zLhalf(DCH_length_t r_z0) const {
+        return r_z0/cos(twist_angle/2/dd4hep::rad);
+    }
+
+    /// tan(stereoangle) = R(z=0)   / (L/2) * tan( twist_angle/2)
+    DCH_angle_t stereoangle_z0(DCH_length_t r_z0) const {
+        return atan( r_z0/Lhalf*tan(twist_angle/2));
+    }
+
+    /// tan(stereoangle) = R(z=L/2) / (L/2) * sin( twist_angle/2)
+    DCH_angle_t stereoangle_zLhalf(DCH_length_t r_zLhalf) const {
+        return atan( r_zLhalf/Lhalf*sin(twist_angle/2));
+    }
+
+    /// WireLength = 2*dch_Lhalf/cos(atan(Pitch_z0(r_z0)/(2*dch_Lhalf)))/cos(stereoangle_z0(r_z0))
+    DCH_length_t WireLength(int nlayer, DCH_length_t r_z0) const {
+        auto Pitch_z0 = database.at(nlayer).Pitch_z0(r_z0);
+        return  2*Lhalf/cos(atan(Pitch_z0/(2*Lhalf)))/cos(stereoangle_z0(r_z0)) ;
+    };
+
+    /// Internal helper struct for defining the layer layout
+    struct DCH_info_layer
+    {
+        /// layer number
+        DCH_layer layer = {0};
+        /// 2x number of cells in that layer
+        int nwires = {0};
+        /// cell parameter
+        double height_z0 = {0.};
+        /// cell parameter
+        double width_z0 = {0.};
+
+        /// radius (cylindral coord) of sensitive wire
+        DCH_length_t radius_sw_z0 = {0.};
+
+        /// radius (cylindral coord) of 'down' field wires
+        DCH_length_t radius_fdw_z0 = {0.};
+
+        /// radius (cylindral coord) of 'up' field wires
+        DCH_length_t radius_fuw_z0 = {0.};
+
+        /// some quantities are derived from previous-layer ones
+        ///  stereo angle is positive for odd layer number
+        bool IsStereoPositive() const {
+            return (1 == layer%2);
+        }
+        /// calculate sign based on IsStereoPositive
+        int StereoSign() const {
+            return (IsStereoPositive()*2 - 1);
+        }
+
+        /// separation between wires (along the circle)
+        DCH_length_t Pitch_z0(DCH_length_t r_z0) const {
+            return TMath::TwoPi()*r_z0/nwires;
+        };
+
+    };
+    /// map to store parameters for each layer
+    std::map<DCH_layer, DCH_info_layer> database;
+    bool IsDatabaseEmpty() const { return database.empty(); }
+
+    inline void BuildLayerDatabase();
+    inline void Show_DCH_info_database(std::ostream& io) const;
+
+
+};
+typedef StructExtension<DCH_info_struct> DCH_info ;
+std::ostream& operator<<( std::ostream& io , const DCH_info& d ){d.Show_DCH_info_database(io); return io;}
+
+inline void DCH_info_struct::BuildLayerDatabase()
+{
+    // do not fill twice the database
+    if( not this->IsDatabaseEmpty() ) return;
+
+    auto ff_check_positive_parameter = [](double p, std::string pname) -> void {
+        if(p<=0)throw std::runtime_error(Form("DCH: %s must be positive",pname.c_str()));
+        return;
+    };
+    ff_check_positive_parameter(this->rin  ,"inner radius");
+    ff_check_positive_parameter(this->rout ,"outer radius");
+    ff_check_positive_parameter(this->Lhalf,"half length" );
+
+    ff_check_positive_parameter(this->guard_inner_r_at_z0 ,"inner radius of guard wires" );
+    ff_check_positive_parameter(this->guard_outer_r_at_zL2,"outer radius of guard wires" );
+
+
+    ff_check_positive_parameter(this->ncell0,"ncells in the first layer" );
+    ff_check_positive_parameter(this->ncell_increment,"ncells increment per superlayer" );
+    ff_check_positive_parameter(this->ncell_per_sector,"ncells per sector" );
+
+    // if dch_ncell_per_sector is not divisor of dch_ncell0 and dch_ncell_increment
+    // throw an error
+    if( 0 != (ncell0 % ncell_per_sector) || 0 != (ncell_increment % ncell_per_sector) )
+        throw std::runtime_error("dch_ncell_per_sector is not divisor of dch_ncell0 or dch_ncell_increment");
+
+    ff_check_positive_parameter(this->nsuperlayers,"number of superlayers" );
+    ff_check_positive_parameter(this->nlayersPerSuperlayer,"number of layers per superlayer" );
+
+    /// nlayers = nsuperlayers * nlayersPerSuperlayer
+    /// default: 112 = 14 * 8
+    this->nlayers = this->nsuperlayers * this->nlayersPerSuperlayer;
+
+    ff_check_positive_parameter(this->first_width,"width of first layer cells" );
+    ff_check_positive_parameter(this->first_sense_r,"radius of first layer cells" );
+
+
+    // intialize layer 1 from input parameters
+    {
+        DCH_info_layer layer1_info;
+        layer1_info.layer         = 1;
+        layer1_info.nwires        = 2*this->ncell0;
+        layer1_info.height_z0     = first_width;
+        layer1_info.radius_sw_z0  = first_sense_r;
+        layer1_info.radius_fdw_z0 = first_sense_r - 0.5*first_width;
+        layer1_info.radius_fuw_z0 = first_sense_r + 0.5*first_width;
+        layer1_info.width_z0      = TMath::TwoPi()*first_sense_r/this->ncell0;
+
+        this->database.emplace(layer1_info.layer, layer1_info);
+    }
+
+    // some parameters of the following layer are calculated based on the previous ones
+    // the rest are left as methods of DCH_info or DCH_info_layer class
+    // loop over all layers, skipping the first one
+    for(int ilayer = 2; ilayer<= this->nlayers; ++ilayer)
+    {
+        // initialize empty object, parameters are set later
+        DCH_info_layer layer_info;
+
+        // the loop counter actually corresponds to the layer number
+        layer_info.layer = ilayer;
+        // nwires is twice the number of cells in this particular layer (ilayer)
+        layer_info.nwires = 2*(this->ncell0 + this->ncell_increment*Get_nsuperlayer_minus_1(ilayer) );
+
+        // the previous layer info is needed to calculate parameters of current layer
+        const auto& previousLayer = this->database.at(ilayer-1);
+
+        //calculate height_z0, radius_sw_z0
+        {
+            double h  = previousLayer.height_z0;
+            double ru = previousLayer.radius_fuw_z0;
+            double rd = previousLayer.radius_fdw_z0;
+
+            if(0 == Get_nsuperlayer_minus_1(ilayer))
+                layer_info.height_z0 = h*ru/rd;
+            else
+                layer_info.height_z0 = TMath::TwoPi()*ru/(0.5*layer_info.nwires - TMath::Pi());
+
+            layer_info.radius_sw_z0 = 0.5*layer_info.height_z0 + ru;
+        }
+
+        //calculate radius_fdw_z0, radius_fuw_z0, width_z0
+        layer_info.radius_fdw_z0 = previousLayer.radius_fuw_z0;
+        layer_info.radius_fuw_z0 = previousLayer.radius_fuw_z0 + layer_info.height_z0;
+        layer_info.width_z0 = TMath::TwoPi()*layer_info.radius_sw_z0/(0.5*layer_info.nwires);
+
+        // according to expert prescription, width_z0 == height_z0
+        if(fabs(layer_info.width_z0 - layer_info.height_z0)>1e-4)
+            throw std::runtime_error("fabs(l.width_z0 - l.height_z0)>1e-4");
+
+
+
+        this->database.emplace(ilayer, layer_info);
+    }
+
+    std::cout << "\t+ Total size of DCH database = " << database.size() << std::endl;
+    return;
+}
+
+inline void DCH_info_struct::Show_DCH_info_database(std::ostream & oss) const
+{
+    oss << "\n";
+    oss << "Global parameters of DCH:\n";
+    oss << "\tGas, half length/mm = " << Lhalf/dd4hep::mm << '\n';
+    oss << "\tGas, radius in/mm  = " << rin/dd4hep::mm << '\n';
+    oss << "\tGas, radius out/mm = " << rout/dd4hep::mm<< '\n';
+    oss << "\tGuard, radius in(z=0)/mm  = " << guard_inner_r_at_z0/dd4hep::mm << '\n';
+    oss << "\tGuard, radius out(z=L/2)/mm = " << guard_outer_r_at_zL2/dd4hep::mm << '\n';
+    oss << "\n";
+    oss << "\tTwist angle (2*alpha) / deg = " << twist_angle/dd4hep::deg << '\n';
+    oss << "\n";
+    oss << "\tN superlayers = " << nsuperlayers << '\n';
+    oss << "\tN layers per superlayer = " << nlayersPerSuperlayer << '\n';
+    oss << "\tN layers = " << nlayers << '\n';
+    oss << "\n";
+    oss << "\tN cells layer1 = " << ncell0 << '\n';
+    oss << "\tN cells increment per superlayer = " << ncell_increment << '\n';
+    oss << "\tN cells per sector = " << ncell_per_sector << '\n';
+    oss << "\n";
+    oss << "Layer parameters of DCH:\n";
+    oss
+            << "\t" << "layer"
+            << "\t" << "nwires"
+            << "\t" << "height_z0/mm"
+            << "\t" << "width_z0/mm"
+            << "\t" << "radius_fdw_z0/mm"
+            << "\t" << "radius_sw_z0/mm"
+            << "\t" << "radius_fuw_z0/mm"
+            << "\t" << "stereoangle_z0/deg"
+            << "\t" << "Pitch_z0/mm"
+            << "\t" << "radius_sw_zLhalf/mm"
+            << "\t" << "WireLength/mm"
+            << "\n" << std::endl;
+
+    if( this->IsDatabaseEmpty() )
+    {
+        oss << "\nDatabase empty\n";
+        return;
+    }
+
+    for(const auto& [nlayer, l]  : database )
+    {
+        oss
+                << "\t" << l.layer
+                << "\t" << l.nwires
+                << "\t" << l.height_z0/dd4hep::mm
+                << "\t" << l.width_z0/dd4hep::mm
+                << "\t" << l.radius_fdw_z0/dd4hep::mm
+                << "\t" << l.radius_sw_z0/dd4hep::mm
+                << "\t" << l.radius_fuw_z0/dd4hep::mm
+                << "\t" << l.StereoSign()*this->stereoangle_z0(l.radius_sw_z0)/dd4hep::deg
+                << "\t" << l.Pitch_z0(l.radius_sw_z0)/dd4hep::mm
+                << "\t" << this->Radius_zLhalf(l.radius_sw_z0)/dd4hep::mm
+                << "\t" << this->WireLength(l.layer,l.radius_sw_z0)/dd4hep::mm
+                << "\n" << std::endl;
+    }
+    return;
+}
+}} // end namespace dd4hep::rec::
+
+#endif // DCH_INFO_H_INCLUDED