Resolve "Add BTOF benchmarks"

Closes #59

benchmarks/tof/scripts/gen_tof_backward_hits.cxx

+#include "HepMC3/GenEvent.h"
+#include "HepMC3/ReaderAscii.h"
+#include "HepMC3/WriterAscii.h"
+#include "HepMC3/Print.h"
+
+#include <iostream>
+#include <random>
+#include <cmath>
+#include <math.h>
+#include <TMath.h>
+
+using namespace HepMC3;
+
+/** Generate multiple electrons/positron tracks in the central region.
+ *  This is for testing detectors in the "barrel" region.
+ */
+void gen_tof_backward_hits(int n_events = 100,
+                         const char* out_fname = "tof_backward_hits.hepmc",
+                         int n_parts = 4)
+{
+  double cos_theta_min = std::cos( 1.0*(M_PI/180.0));
+  double cos_theta_max = std::cos(189.0*(M_PI/180.0));
+
+  WriterAscii hepmc_output(out_fname);
+  int events_parsed = 0;
+  GenEvent evt(Units::GEV, Units::MM);
+
+  // Random number generator
+  TRandom *r1 = new TRandom();
+
+  for (events_parsed = 0; events_parsed < n_events; events_parsed++) {
+    // FourVector(px,py,pz,e,pdgid,status)
+    // type 4 is beam
+    // pdgid 11 - electron
+    // pdgid 111 - pi0
+    // pdgid 2212 - proton
+    Double_t p     = r1->Uniform(0, 8);
+    Double_t costh = -1*cos((180-12.033)/180*3.1415926); //r1->Uniform(cos_theta_min, cos_theta_max);
+    Double_t th    = std::acos(costh);
+    Double_t phi   = r1->Uniform(0.0, 2.0 * M_PI);
+    Double_t px    = p * std::cos(phi) * std::sin(th);
+    Double_t py    = p * std::sin(phi) * std::sin(th);
+    Double_t pz    = p * std::cos(th);
+
+    for (int ip = 0; ip < n_parts; ip++) {
+      GenParticlePtr p1 = std::make_shared<GenParticle>(FourVector(0.0, 0.0, 10.0, 10.0), 11, 4);
+      GenParticlePtr p2 = std::make_shared<GenParticle>(FourVector(0.0, 0.0, 0.0, 0.938), 2212, 4);
+
+      // Define momentum
+      phi   = r1->Uniform(0.0, 2.0 * M_PI);
+      px    = p * std::cos(phi) * std::sin(th);
+      py    = p * std::sin(phi) * std::sin(th);
+      pz    = p * std::cos(th);
+      GenParticlePtr p3 = std::make_shared<GenParticle>(FourVector(px, py, pz, sqrt(p * p + (0.000511 * 0.000511))),
+                                                          ((ip % 2 == 0) ? 11 : -11), 1);
+
+      phi   = r1->Uniform(0.0, 2.0 * M_PI);
+      px    = p * std::cos(phi) * std::sin(th);
+      py    = p * std::sin(phi) * std::sin(th);
+      pz    = p * std::cos(th);
+      GenParticlePtr p4 = std::make_shared<GenParticle>(FourVector(px, py, pz, sqrt(p * p + (0.938272 * 0.938272))),
+                                                          ((ip % 2 == 0) ? 2212 : -2212), 1);
+
+      phi   = r1->Uniform(0.0, 2.0 * M_PI);
+      px    = p * std::cos(phi) * std::sin(th);
+      py    = p * std::sin(phi) * std::sin(th);
+      pz    = p * std::cos(th);
+      GenParticlePtr p5 = std::make_shared<GenParticle>(FourVector(px, py, pz, sqrt(p * p + (0.493677 * 0.493677))),
+                                                          ((ip % 2 == 0) ? 321 : -321), 1);
+      phi   = r1->Uniform(0.0, 2.0 * M_PI);
+      px    = p * std::cos(phi) * std::sin(th);
+      py    = p * std::sin(phi) * std::sin(th);
+      pz    = p * std::cos(th);
+      GenParticlePtr p6 = std::make_shared<GenParticle>(FourVector(px, py, pz, sqrt(p * p + (0.139570 * 0.139570))),
+                                                          ((ip % 2 == 0) ? 211 : -211), 1);
+
+      GenVertexPtr v1 = std::make_shared<GenVertex>();
+      v1->add_particle_in(p1);
+      v1->add_particle_in(p2);
+      v1->add_particle_out(p3);
+      v1->add_particle_out(p4);
+      v1->add_particle_out(p5);
+      v1->add_particle_out(p6);
+      evt.add_vertex(v1);
+    }
+
+    if (events_parsed == 0) {
+      std::cout << "First event: " << std::endl;
+      Print::listing(evt);
+    }
+
+    hepmc_output.write_event(evt);
+    if (events_parsed % 10000 == 0) {
+      std::cout << "Event: " << events_parsed << std::endl;
+    }
+    evt.clear();
+  }
+  hepmc_output.close();
+  std::cout << "Events parsed and written: " << events_parsed << std::endl;
+}