McCauley, T. (2014). Dimuon event information derived from the Run2010B public Mu dataset. CERN Open Data Portal. DOI: 10.7483/OPENDATA.CMS.CB8H.MFFA.
Welcome to JupyROOT 6.07/07
First of all we convert the csv file into ROOT format, i.e. filling up a TTree data structure. But first of all we uncompress it if it's not.
inputFileName = 'MuRun2010B.csv' import os if not os.path.exists(inputFileName): import urllib2 response = urllib2.urlopen('https://raw.githubusercontent.com/dpiparo/swanExamples/master/notebooks/MuRun2010B.csv') filecontent = response.read() with open(inputFileName,"w") as f_out: f_out.write(filecontent)
dimuons = ROOT.TTree("MuonPairs","MuonPairs") dimuons.ReadFile(inputFileName)
Now we create an histogram to hold the invariant mass values. In order to loop on the TTree rows, we use the TTree::Draw method: this is the most straightforward way in which you can loop on a N-tuple in ROOT.
invMass = ROOT.TH1F("invMass","CMS Opendata: #mu#mu mass;#mu#mu mass [GeV];Events",512, 2, 110) invMassFormula = "sqrt((E1 + E2)^2 - ((px1 + px2)^2 + (py1 + py2)^2 + (pz1 + pz2)^2))" cut = "Q1*Q2==-1" c = ROOT.TCanvas() dimuons.Draw(invMassFormula + " >> invMass",cut,"hist") c.SetLogx() c.SetLogy() c.Draw()
That might have been too fast. We now make the analysis above more explicit producing a plot also for the J/Psi particle.
from math import sqrt invMass = ROOT.TH1F("Spectrum","Subset of CMS Run 2010B;#mu#mu mass [GeV];Events",1024, 2, 110) jpsiLow = 2.95 jspiHigh = 3.25 jpsi = ROOT.TH1F("jpsi","Subset of CMS Run 2010B: J/#psi window;#mu#mu mass [GeV];Events",128, jpsiLow, jspiHigh) for e in dimuons: # a loop on the events if e.Q1 * e.Q2 != -1: continue m2 = (e.E1 + e.E2)**2 - ((e.px1 + e.px2)**2 + (e.py1 + e.py2)**2 + (e.pz1 + e.pz2)**2) m = sqrt(m2) invMass.Fill(m) if m < jspiHigh and m > jpsiLow: jpsi.Fill(m)
Now time to draw our plot: this time we will inline an image in the notebook. We will plot on the same canvas the full spectrum and the zoom in the J/psi particle.
dualCanvas = ROOT.TCanvas("DualCanvas","DualCanvas",800,512) dualCanvas.Divide(2,1) leftPad = dualCanvas.cd(1) leftPad.SetLogx() leftPad.SetLogy() invMass.Draw("Hist") dualCanvas.cd(2) jpsi.Draw("HistP") dualCanvas.Draw()