Overview: high-energy computing production How do the raw signals become analyzable data? How do we “fake” the LHC (turn theoretical models into mock detector output)? How do these analyzable events get to my workstation “so quickly?” How are they archived? How do I extract parameters from event records? How do I condense petabytes of data into a picture? operations analysis

Analysis with ROOT How do I extract parameters from event records? How do I condense petabytes of data into a picture? analysis

Data is stored in many formats… trigger bytestream convert RDO (raw) fast pattern recognition event sorting esd D3PD reconstruction MERGE& derive aod note: you’ll see these acronyms often… aod pattern recognition more sorting tag

Simulation: treated the same way! MONTE CARLO PRODUCTION CHAIN RDO (raw) esd D3PD RECO MERGE & derive aod aod tag

The event format: tracks calorimeter clusters electron muon metadata

The event format in software Organized by event (quadrillions witnessed in 2012!) event-wide information Examples: metadata; sum of measured transverse energy physics object lists: muons, electrons, taus… tracks of charged particles “truth” particles… object properties: e.g. “hits” on tracks µ track jet tau track hit 2-tuple (a,b) n-tuple (a1,a2,…aN) TTree (evt, (el.px,el.py,el.pz)[el_n],UnitVector, …)

Condensing the information how can we make that “jungle” look more like a Higgs boson?

Histograms! “Hello World” for HEP computing: making a histogram TH1F(“name”, “title; x title; y title”, nBins, firstBinValue, LastBinValue) Pseudocode: histo = makeHisto(nbins=50, firstbin=0*GeV, lastbin=200*GeV) for thisEvent in allEvents: if HasZ( thisEvent ): m = recoZMass( thisEvent ) histo.FillWith( m ) TH1F::Fill(value,weight)

getting to the fun part: Are you into installing/basic histogramming? Are you ready for processing/understanding ATLAS data? ROOT installation The DUKE ROOT tutorial: exercises by Al Goshaw help from Neil, others… The ATLAS ROOT tutorial: also a nice way to try out your new ATLAS computing account! TTrees, tree loops, TSelectors, python tree access Common homework: the Duke D3PD Dictionary