Comments on: Project Help

By: edgar

edgar — Fri, 26 Feb 2010 17:07:23 +0000

the idea is that once you start looping over the events, you check if that event passed a given trigger condition, if it did, you can go ahead and start calculating the invariant mass of the “hard” di-muon system for the event and fill the histo so you can then plot it. Calculating the invariant mass first and then checking for the trigger bit (like in the above comment) is also fine, but it is not optimal because you can save some computing time by not going through the calculation of the invariant mass if that event did not pass the trigger.

By: edgar

edgar — Fri, 26 Feb 2010 15:54:39 +0000

You can load the trg branches just like you load the mu_* branches, and then, after you calculate the inv mass, use the C++ if statement to just fill the histograms for those events that satisfy that particular trg, something like:

if (trg_blah == 1) hinv->Fill(invm);

this would be equivalent to doing

h1->Draw(“invariantmass”,”trg_blah==1″)

from the command line if you had the invariantmass variable in there.

Additional hint: use the double muon trigger.

By: chelsea

chelsea — Fri, 26 Feb 2010 12:12:50 +0000

Oops, sorry for some reason about half of my post was deleted. The command that I used (which came from the “mytree->Draw” command we discussed earlier) was h1->Draw(“invariantmass”,”invariantmass<200&&trg_L1MuOpen==1"), where h1 is the name of the histogram and I have set the branch address for invariant mass.
The error I receive is "unknown branch: Can't call TH1F::Draw".