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NA22_1986_I18431

Multiplicity distributions in $pp$, $K^+ p$ and $\pi^+ p$ at $p_{\mathrm{lab}} = 250$ GeV/c
Experiment: NA22 (SPS)
Inspire ID: 18431
Status: VALIDATED
Authors:
  • Christian Bierlich
References:
  • Z.Phys. C32 (1986) 475
Beams: p+ p+, 321 p+, 211 p+
Beam energies: (250.0, 0.0); (250.0, 0.0); (250.0, 0.0) GeV
Run details:
  • Fixed target events with $p$, $K^+$ and $\pi^+$ hitting a proton target.

Charged multiplicity distributions of $pp$, $K^+ p$ and $\pi^+ p$ fixed target collisions, $p_{\mathrm{lab}} = 250$ GeV/c or equivalently $\sqrt{s} = 21.7$ GeV/c (pp).

Source code: NA22_1986_I18431.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {


  /// @brief NA22 min bias multiplicity distributions.
  class NA22_1986_I18431 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(NA22_1986_I18431);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      declare(ChargedFinalState(), "CFS");

      // Figure out beam type
      const ParticlePair& beam = beams();
      int btype = 0;
      if (beam.first.pid() == PID::PIPLUS && beam.second.pid() == PID::PROTON)
        btype = 1;
      else if (beam.first.pid() == PID::KPLUS && beam.second.pid() == PID::PROTON)
        btype = 2;
      else if (beam.first.pid() == PID::PROTON && beam.second.pid() == PID::PROTON)
        btype = 3;
      else {
        MSG_ERROR("Beam error: Not compatible!");
	return;
      }
      book(_h_mult, btype, 1, 1);

    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      int nfs = apply<ChargedFinalState>(event, "CFS").size();
      _h_mult->fill(nfs);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_mult); // normalize to unity

    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _h_mult;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(NA22_1986_I18431);


}