ROOT Data Analysis Framework Overview

ROOT Tutorials

In general, my lesson plan was as follows:

• Show you how to run PROOF (emphasizing the code needed)
  • TChain files together
  • Make template header, code, and PROOF starting files for specific .root data files
  • Troubleshooting PROOF run errors (whether it's your code or the cluster's errors)

• Basic analysis code
  • Explain online & offline triggers
  • Analysis cut (lots to discuss)
  • Ways to display data (and interpret it)
  • Calculating invariant mass, delta phi, etc.
  • Calculating Accidental Scaling Factor
  • Tag weighting (accidental subtraction)
  • Two calculations for Sideband Subtraction
  • Fitting histograms
  • Cross section (differential and total)

• Provide sample code and tricks
  • Setup an array (using a for loop or with direct input, depending on the occasion)
  • Reorder things from high to low mass (how to deal with multiple combinations at once)
  • TLorentzVectors
  • Create new .root files
  • Create marcos to print, make GIF's, fit data, etc.
  • TGraphs & TSplines

• Final Summary
  • Walk you through my analysis for determining the Eta meson cross section
  • Big picture stuff that puts everything all together and hopefully makes it all make sense

Lesson #1

Lesson #1 Video

• C++ code examples used in lesson #1
  

Lesson #2

Lesson #2 Video

Lesson #3

Lesson #3

• C++ code examples used in lesson #3
  

• Additional C++ code examples added to the file used in lesson #1
  

Lesson #4

Lesson #4

Lesson #5

Lesson #5

Additional Resource Files

This file can be uploaded in to a personal annex directory on gluey and manipulated with ROOT to plot the TH1D's and TH2D's contained within.

• ROOT file with TTree h1
  

If inside the folder containing the .root file, use the command:

root -l TwoG_jul_16_2021Analysis.root

If you know the path to the file then use:

root -l

TFile *_file0 = TFile::Open("/nfs/direct/annex/mcintyre/AnalysisXII/TwoG/inv_mass/TwoG_jul_16_2021Analysis.root")

or

root -l /nfs/direct/annex/mcintyre/AnalysisXII/TwoG/inv_mass/TwoG_jul_16_2021Analysis.root

These files are the three files needed to run a PROOF session. These files, written in C++, contain basic clean-up cuts for Radphi data analysis as discussed during the tutorial videos. Running a PROOF session on files such as these are how the .root file (listed above) was created.

• C++ code used to TChain data files and setup PROOF service.
  
• Header file used to perform data analysis.
  
• TSelector used to perform data analysis.
  

A GitHub page containing ROOT training material and tutorials given to CERN Summer Students. There is a link to the ROOT introductory course part of the CERN Training Catalogue.

• GitHub page containing ROOT training material from CERN
  

• Images of histograms contained within the TTree of TwoG_jul_16_2021Analysis.root. These are three examples of the type of histograms you can produce using the ROOT framework.
• 

  Figure 1: A TH2D histogram plotting polar angle of a photon in the LGD versus its energy. This plot was generated with all clean-up cuts except the beamhole cut.

• 

  Figure 2: A TH2D histogram plotting polar angle of a photon in the LGD versus its energy. This plot was generated with all clean-up cuts including the beamhole cut.

Figure 3: A TH1D histogram of the Mandelstam variable t for the two gamma final state sample.