parse the data.

Generator/src/BeamBackgroundFileParserV0.cpp

 
 #include "BeamBackgroundFileParserV0.h"
+#include <sstream>
+#include <cmath>
 
-BeamBackgroundFileParserV0::BeamBackgroundFileParserV0(const std::string& filename) {
+BeamBackgroundFileParserV0::BeamBackgroundFileParserV0(const std::string& filename,
+                                                       int pdgid,
+                                                       double beam_energy) {
     m_input.open(filename.c_str());
+    m_pdgid = pdgid;
+    m_beam_energy = beam_energy;
 }
 
 bool BeamBackgroundFileParserV0::load(IBeamBackgroundFileParser::BeamBackgroundData& result) {
-    return true;
+
+    if (not m_input.good()) {
+        return false;
+    }
+
+    // read one record
+    std::string tmpline;
+    // the format
+    double generation_point;
+    int loss_turn;
+    double z; // unit: m
+    double x; // unit: m
+    double y; // unit: m
+    double cosx; // 
+    double cosy; //
+    double dz; // unit: m
+    double dp; // unit: relative to the E
+
+    while(m_input.good()) {
+        std::getline(m_input, tmpline);
+        std::stringstream ss;
+        ss << tmpline;
+        ss >> generation_point; if (ss.fail()) { continue; }
+        ss >> loss_turn;        if (ss.fail()) { continue; }
+        ss >> z;                if (ss.fail()) { continue; }
+        ss >> x;                if (ss.fail()) { continue; }
+        ss >> y;                if (ss.fail()) { continue; }
+        ss >> cosx;             if (ss.fail()) { continue; }
+        ss >> cosy;             if (ss.fail()) { continue; }
+        ss >> dz;               if (ss.fail()) { continue; }
+        ss >> dp;               if (ss.fail()) { continue; }
+
+        double p = m_beam_energy*(1+dp);
+
+        // Now, we get a almost valid data
+        const double m2mm = 1e3; // convert from m to mm
+        result.pdgid = m_pdgid;
+        result.x     = x * m2mm; 
+        result.y     = y * m2mm; 
+        result.z     = (z+dz) * m2mm;
+
+        result.px    = p * cosx;
+        result.py    = p * cosy;
+        result.pz    = p * std::sqrt(1-cosx*cosx-cosy*cosy);
+
+        result.mass  = 0.000511; // assume e-/e+, mass is 0.511 MeV
+
+        return true;
+    }
+    return false;
 }

Generator/src/BeamBackgroundFileParserV0.h

@@ -7,11 +7,14 @@
 
 class BeamBackgroundFileParserV0: public IBeamBackgroundFileParser {
 public:
-    BeamBackgroundFileParserV0(const std::string& filename);
+    BeamBackgroundFileParserV0(const std::string& filename, int pdgid, double beam_energy);
 
     bool load(IBeamBackgroundFileParser::BeamBackgroundData&);
 private:
     std::ifstream m_input;
+
+    int m_pdgid;
+    double m_beam_energy;
 };
 
 #endif