speed up with binary search

[u/mrichter/AliRoot.git] / MUON / READMEevaluation.txt

// $Id$

/*! 

\page README_evaluation Evaluation
 

\section  evaluation_s1 How to process invariant mass spectra for J/psi or Upsilon

The macro MUONmassPlot_ESD.C reads back the MUON ESD informations and compute 
the invariant mass spectra and corresponding uncorelated background. 
Moreover gives the number of event in the resonance peak and the number of triggers.
<pre>
Usage:
root [0] .L $ALICE_ROOT/MUON/MUONmassPlot_ESD.C+
root [1] MUONmassPlot_ESD(ExtrapToVertex, 
			geoFilenam, filename
                        FirstEvent, LastEvent, 
	                esdFileName,
			ResType, Chi2Cut,
			PtCutMin, PtCutMax,
        		massMin, massMax)

with:
ExtrapToVertex (default -1)
      <0: no extrapolation;
      =0: extrapolation to (0,0,0);
      >0: extrapolation to ESDVertex if available, else to (0,0,0)
geoFilename (default "geometry.root") geometry file name needed to extrap to vertex
filename    (default "galice.root") galice root file name
FirstEvent  (default 0)
LastEvent   (default 10000)
esdFileName (default "AliESDs.root") esd root file name
ResType     (default 553):   553 for Upsilon, anything else for J/Psi
Chi2Cut     (default 100):   keep only tracks with chi2 per d.o.f. < Chi2Cut
PtCutMin    (default 1):     keep only tracks with transverse momentum > PtCutMin
PtCutMax    (default 10000): keep only tracks with transverse momentum < PtCutMax
massMin     (default 9.17 for Upsilon) keep only invariant masses with 
massMax     (default 9.77 for Upsilon) massMin < mass < massMax
</pre>

\section evaluation_s2 How to run MUONRecoCheck macro

To check the muon reconstruction by comparing the reconstructed tracks
with the reference tracks made of "AliTrackReference" for the hits in chamber (0..9)
and kinematic informations (TreeK) for the vertex.
This macro can be used to check the track reconstruction e.g. efficiency,
momentum resolution ... but also to make physics analysis whenever
track identification is needed.   

To compile MUONRecoCheck.C
<pre>
.includepath $ALICE_ROOT/STEER
.includepath $ALICE_ROOT/MUON
.L $ALICE_ROOT/MUON/MUONRecoCheck.C+
</pre>

To run MUONRecoCheck
<pre>
MUONRecoCheck(nEvent,"geometry.root", "galice.root"); // nEvent = nb of events
</pre>


\section evaluation_s3 Macros for MC studies

For MC studies the classes AliMUONTrackLight and AliMUONPairLight can be 
used in order to fill not only the single muon / dimuon's kinematics (charge, 
pT, rapidity, etc) at the generation AND reconstruction level, but also for 
"decoding" the Pythia output and for the storing of the single muon's history. 
This allows to tag if two muons of a given event come from a certain, well-defined 
process, such as J/psi, Upsilons, correlated open charm or open beauty or the 
low masses or if they are of uncorrelated origin. For open beauty/charm it also 
tags the creation process (pair creation, flavour excitation or gluon splitting). 
The classes also allow to tag feed-down or neutral B meson oscillation and 
has a method that checks whether the reconstructed track is a muon or not.

The macros ReadRecoCocktail.C, DecodeRecoCocktail.C and MergeMuonLight.C 
are examples how to use these two classes. DecodeRecoCocktail.C opens the 
generated files, loops over the events and fills an AliMUONTrackLight object 
for every reconstructed track for which the reference to its generated particle 
could be established, using the AliMUONRecoCheck class. 
It then takes the AliMUONTrackLight objects and forms - event by event - 
AliMUONPairLight objects, on a combinatorial basis. For a given event these 
objects are stored in respective TClonesArrays which are then stored in a tree. 
By default, the produced output file is called "MuonLight.root". 
This root file can then be taken by the macro "ReadRecoCocktail.C" that shows, 
on the example of the reconstructed mass and pT of the AliMUONPairLight object,
how to access the available information. For large statistics, in which many 
individual MuonLight.root files are produced, MergeMuonLight.C can be used 
to merge the files and produce one common output root file.

To read a generation/reconstrution from PDC06 preproduction, and write a file 
with a tree of AliMUONTrackLight / AliMUONPairLight :
go to the directory containing the generation/reconstruction. From there run
aliroot

<pre>
.L DecodeRecoCocktail.C+
DecodeRecoCocktail();
.q
</pre>

To read the file previously generated:
<pre>
aliroot
.L ReadRecoCocktail.C+
ReadRecoCocktail();
.q
</pre>

This chapter is defined in the READMEevaluation.txt file.

*/