August 2006

To sum up...

Final entry (until I resume work!). Let's put everything that's been done this summer together...

We'll have to start by creating an area for our project. If our version of CMSSW is, say, 0_8_0, then we'll have to write:

scramv1 project CMSSW CMSSW_0_8_0;

To checkout code from the repository:

cd CMSSW_0_8_0/src;
cmscvsroot CMSSW; cvs login;
cvs co -r CMSSW_0_8_0 IOMC;

Inside the IOMC/GeneratorInterface/test we can find some examples of event generation. Before doing anything like this though, we'll have to do:

cd IOMC/GeneratorInterface/test;
eval `scramv1 runtime -sh`; Needed after logon to run a project.
cmsRun mcinput.cfg; Generate events.

To study a certain process you need to change the parameters that are being sent to Pythia. For the example code, these are located in IOMC/GeneratorInterface/data inside the .cfi files. Setting MSEL=0 allows you to define your own processes. Then, you'll have to use MSUB to choose processes and, if desired, MDME values to turn on or off decay channels. More information about these can of course be found in the Pythia manual.

Now, after generating some events you'll want to process them I suppose. There are two ways to do this:

• Using ROOT and FWLight
• Using the Full Framework

For FWLight, you'll have to load all the necessary tools after starting ROOT:

gSystem->Load("libFWCoreFWLite.so");
AutoLibraryLoader::enable();

The full framework gives you full control (and probably less frustration!). You'll have to create a directory for your analysis and create an empty analyzer project which you'll use as a template to do all the real work:

After logging in your account then you can do:

cd CMSSW_0_8_0/src
eval `scramv1 runtime -sh`
mkdir Analysis
mkedanlzr Analyzer

Now you can change the Analyzer.cc in the Analysis/Analyzer/src directory to do whatever you want to do. I have put online my code (not final version). After Aug. 15th I'll put online the "final" versions as well as a reference. A useful "recipe" from Sasha Nikitenko can be found here. Other useful pages can be found in the sidebar (-->) .All the presentations I've put in the files section could be useful. Also, in previous postings there are information about how to iterate over SuperClusters or other parts of the resulting root files and how to extract information from them.

Now a good part of this summer was (well) spent on trying to deduce a good electron-finding technique. The following cuts seem to work nicely:

• Min SC energy cut = 5.0 GeV
• Max SC energy cut = 300.0 GeV
• ΔR between SCs & Jets >= 0.5
• E ratio between SCs & Jets >= 0.3
• ΔR between Tracks & SCs = 0.5
• E/Pt between Tracks & SCs >= 0.7

Also, the current version of CMSSW seems to have some issues with the EndCap SuperClusters (look at previous post and the August 1st presentation).

You may also find my final presentation interesting (tba).