The MINERvA Analysis Toolkit (MAT) is a toolkit for at looping root tuples, filling histograms, and calculating/propagating systematics. It's the foundation for dozens of MINERvA publications and counting.

Paper here: Arxiv 2103.08677.

In this repo I show here how it can work on Mu2e. runEventLoop.C loops over TrkAna tree entries, makes cuts, and plots a branch: the number of hits in a track. Run it with (and see instructions below):

root -l -b -q load.C+ runEventLoop.C+

Replace MakeClass: At minimum, MAT's ChainWrapper can immediately replace ROOTs MakeClass for looping entries and accessing branches: it's faster and has an easier branch access interface:

chain->GetDouble("my_branch");
chain->GetVectorInt("my_int_vector_branch");

No messy header loading all branches. Each branch is loaded as needed and is cached for subsequent loops.

Systematics The MAT makes it easy to start doing systematics analysis immediately. It uses "many universe" approach to systematics: For a single event, a histogram's bin counts are re-calculated in each user-defined universe, subject to cuts or event weights. Resulting systematics and histogram algebra/manipulation are handled and propagated. CVUniverse.h defines how variables are calculated in the central value. And in Systematics.h, user defines how those variables should behave differently in each universe.

# standard mu2e setup
cd /your/working/directory
mu2einit
setup mu2e
muse setup TrkAna v05_00_00

# the MAT
git clone https://github.com/MinervaExpt/MAT.git
mkdir -p opt/build && cd opt/build
cmake ../../MAT -DCMAKE_INSTALL_PREFIX=`pwd`/.. -DCMAKE_BUILD_TYPE=Release
make install #-j 4
source setup_MAT.sh 
cd ../..

# get some tutorial trkana files
mkdir filelists
setup dhtools
samListLocations -d --defname=nts.mu2e.CeEndpointMix1BBSignal.Tutorial_2024_03.tka > filelists/nts.mu2e.CeEndpointMix1BBSignal.Tutorial_2024_03.list

# download this repo and run the loop
git clone https://github.com/bamesserly/mu2e-mat.git
cd mu2e-mat/
root -l -q -b load.C+ runEventLoop.C+