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UA5_1989_S1926373

UA5 charged multiplicity measurements
Experiment: UA5 (CERN SPS)
Inspire ID: 267179
Status: VALIDATED
Authors:
  • Holger Schulz
  • Christophe L. J. Vaillant
  • Andy Buckley
References: Beams: p- p+
Beam energies: (100.0, 100.0); (450.0, 450.0) GeV
Run details:
  • Minimum bias events at $\sqrt{s} = 200$ and 900 GeV. Enable single and double diffractive events in addition to non-diffractive processes.

Multiplicity distributions of charged particles produced in non-single-diffractive collisions between protons and antiprotons at centre-of-mass energies of 200 and 900 GeV. The data were recorded in the UA5 streamer chambers at the CERN collider, which was operated in a pulsed mode between the two energies. This analysis confirms the violation of KNO scaling in full phase space found by the UA5 group at an energy of 546 GeV, with similar measurements at 200 and 900 GeV.

Source code: UA5_1989_S1926373.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/TriggerUA5.hh"

namespace Rivet {


  /// @brief UA5 min bias charged multiplicities in central \f$ \eta \f$ ranges
  class UA5_1989_S1926373 : public Analysis {
  public:

    /// Constructor
    UA5_1989_S1926373() : Analysis("UA5_1989_S1926373") {
      _sumWPassed = 0;
    }


    /// @name Analysis methods
    //@{

    /// Book histograms and projections
    void init() {
      declare(TriggerUA5(), "Trigger");
      declare(ChargedFinalState(-0.5, 0.5), "CFS05");
      declare(ChargedFinalState(-1.5, 1.5), "CFS15");
      declare(ChargedFinalState(-3.0, 3.0), "CFS30");
      declare(ChargedFinalState(-5.0, 5.0), "CFS50");

      // NB. _hist_nch and _hist_ncheta50 use the same data but different binning
      if (fuzzyEquals(sqrtS()/GeV, 200, 1E-3)) {
        _hist_nch        = bookHisto1D(1, 1, 1);
        _hist_nch_eta05  = bookHisto1D(3, 1, 1);
        _hist_nch_eta15  = bookHisto1D(4, 1, 1);
        _hist_nch_eta30  = bookHisto1D(5, 1, 1);
        _hist_nch_eta50  = bookHisto1D(6, 1, 1);
        _hist_mean_nch   = bookHisto1D(11, 1, 1);
      } else if (fuzzyEquals(sqrtS()/GeV, 900, 1E-3)) {
        _hist_nch        = bookHisto1D(2, 1, 1);
        _hist_nch_eta05  = bookHisto1D(7, 1, 1);
        _hist_nch_eta15  = bookHisto1D(8, 1, 1);
        _hist_nch_eta30  = bookHisto1D(9, 1, 1);
        _hist_nch_eta50  = bookHisto1D(10, 1, 1);
        _hist_mean_nch   = bookHisto1D(12, 1, 1);
      }

      /// @todo Moments of distributions
    }


    /// Do the analysis
    void analyze(const Event& event) {
      // Trigger
      const TriggerUA5& trigger = apply<TriggerUA5>(event, "Trigger");
      if (!trigger.nsdDecision()) vetoEvent;

      const double weight = event.weight();
      _sumWPassed += weight;

      // Count final state particles in several eta regions
      const int numP05 = apply<ChargedFinalState>(event, "CFS05").size();
      const int numP15 = apply<ChargedFinalState>(event, "CFS15").size();
      const int numP30 = apply<ChargedFinalState>(event, "CFS30").size();
      const int numP50 = apply<ChargedFinalState>(event, "CFS50").size();

      // Fill histograms
      _hist_nch->fill(numP50, weight);
      _hist_nch_eta05->fill(numP05, weight);
      _hist_nch_eta15->fill(numP15, weight);
      _hist_nch_eta30->fill(numP30, weight);
      _hist_nch_eta50->fill(numP50, weight);
      _hist_mean_nch->fill(_hist_mean_nch->bin(0).xMid(), numP50*weight);
    }


    void finalize() {
      scale(_hist_nch, 1.0/_sumWPassed);
      scale(_hist_nch_eta05, 1.0/_sumWPassed);
      scale(_hist_nch_eta15, 1.0/_sumWPassed);
      scale(_hist_nch_eta30, 1.0/_sumWPassed);
      scale(_hist_nch_eta50, 1.0/_sumWPassed);
      scale(_hist_mean_nch, 1.0/_sumWPassed);
    }

    //@}


  private:

    /// @name Counters
    //@{
    double _sumWPassed;
    //@}

    /// @name Histograms
    //@{
    Histo1DPtr _hist_nch;
    Histo1DPtr _hist_nch_eta05;
    Histo1DPtr _hist_nch_eta15;
    Histo1DPtr _hist_nch_eta30;
    Histo1DPtr _hist_nch_eta50;
    Histo1DPtr _hist_mean_nch;
    //@}

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(UA5_1989_S1926373);

}