MINERvA Analysis Toolkit

work
Particle physics analysis toolkit

GitHub | arxiv

The MAT is an error analysis software toolkit for particle physics data analysis that I designed and built as a member of the MINERvA Experiment.

The MAT is a flexible and powerful set of software tools to centralize, calculate, and visualize systematic uncertainties in particle physics analyses.

Data Visualization

hist -> DrawErrorSummary(); // [left]
errMatrix = hist -> GetCorrelationMatrix();
errMatrix.Draw(); // [ right ]

Some of the data visualization tools provided by the MAT: error budget and total covariance matrix (above) and the source code (below).


The MnvHnD, a powerful histogram container class

The MnvHnD container holds and manages universe information. Universes are propagated through histogram manipulations.


Uncertainties processed in a single event record loop

double PassesCuts(const ExampleUniverse& univ) {
  return univ.GetLeptonEnergy() < 20;
}

MnvH1D energyHistogram(systematics);

for(const auto& event: eventRecord) {
  for(const ExampleUniverse& univ: systematics) {
    if(PassesCuts(univ)) {
      const double energy = univ.GetLeptonEnergy();
      const double weight = univ.GetWeight();
      energyHistogram.FillUniverse(univ, energy, weight);
    }
  }
}

The central value and all systematics are processed in a single loop. Different universes may modify weights or impact the result of the cuts.


Systematic Universe classes modularly implement many-universe error analysis

class ExampleUniverse: public BaseUniverse
{
  public:
    //Constructor and destructor details...
    
    virtual double GetLeptonEnergy() const {
      return m_tree->Get("lepton_energy");
    }
    
    virtual double GetWeight() const {
      return 1;
    }
    
  private:
    TreeWrapper* m_tree;
};

template <class UNIVERSE>
class CalibrationLeptonEnergyUniverse: public UNIVERSE
{
  public:
    //Constructors to match UNIVERSE

    double GetLeptonEnergy() const override {
      return UNIVERSE::GetLeptonEnergy() + 50; //MeV
    }
};

In the MAT namespace, experiments set experiment-wide constants, interfaces and systematics. Users and groups implement analysis-specific systematics and calculators. Here, the calibration process impacts the lepton energy, moving events in and out of the cuts when that universe is processed in the event loop.

Motivation

Uncertainty evaluation in HEP is complex and extremely important, but there are no community-standard tools.

Experiments are getting bigger, and flexible analysis systems are increasingly important for maximizing physics output.

The MAT lowers the software barrier to entry for analyzers allowing users to spend less time writing code and more time thinking about physics.


Acknowledgments

I designed and built the Universe system, upgraded the MnvHnD object to use Universes (I am not the original author of the MnvHnD), and was a principal developer of the toolkit as a whole (including most of its other unlisted bells and whistles), all on behalf of the MINERvA collaboration. I worked with several awesome MINERvA colleagues along the way, and now the toolkit is mostly maintained internally by MINERvAns. ```

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