Eliptic vs rectangular matching cut
Area difference between these two cuts is:
- Rectangular cut: (2*D_phi)*(2*D_theta) = 4*D_theta*D_phi
- Eliptic cut: pi * D_theta * D_phi
- Difference = 22%
Conversion / Signal from PLUTO simulation
I have compared the 1D distribution for (theta_rich - theta_RK) (in phi it
looks similar) for electrons comming from conversion and the electrons
comming from all other sources. the conversion signal I have chosen according
to the following condition: "pid.genInfo1==7001 || pid.genInfo1==17001 ||
pid.genInfo1==52001", the "real" signal is negation of the previous
condition. the determination of the mean and sigma of the distribution was
done with the "standard" 2-gaussian fit for momentum bins (0,150>; (150,350>
and (350,1000>
in the picture "compareSim.png" you can see mean and sigma of the delta_theta
distributions for the 3 momenta bins. the upper two pictures are done for
electrons and positrons separately (red color "real" signal, blue conversion
signal). in the lowest picture the comparision between electrons and
positrons for the "real" signal is done.
as one can see, the differences in the simulation are only minor. the yields
for signal and conversion are comparable (almost 1:1) for momenta (0,150>, it
drops to 2:1 for momenta (350,1000> (see thetaNeg.jpg)
The sigma of the delta_theta distributions for negative tracks is:
- Signal: 0.96, 0.74, 0.54
- Conversion: 1.01, 0.81, 0.62
The sigma of the delta_theta distributions for positive tracks is:
- Signal: 1.18, 0.79, 0.60
- Conversion: 1.12, 0.88, 0.60
==================================================
in phi are the distributions much more narrower:
The sigma of the delta_phi distributions for negative tracks is:
- Signal: 0.55, 0.47, 0.47
- Conversion: 0.40, 0.53, 0.56
The sigma of the delta_phi distributions for positive tracks is:
- Signal: 0.57, 0.49, 0.50
- Conversion: 0.46, 0.51, 0.40
At this point i have to add, that i set following limits for the fit
parameters:
for signal is sigma in the range (0.4; 2.0) and for the background (2.0;
infinity), which you can see in the fits not very well describing the
distributions. in the most cases, the background had sigma of 2.0 in few
cases just a touch higher than 2.0! (not a very good model :-(...), since for
experimental data this limits worked very well, i decided not to introduce
new limits for the fits.
I hope, the selection of the conversion was done properly (according to the
documentation i hope i have not overseen something...)
--
MartinJurkovic - 29 May 2007
- Comparision delta theta (RICH - MDC) distribution of signal and conversion leptons:
- Phi correlation for positive leptons (signal left, conversion right):
- Theta correlation for positive leptons (signal left, conversion right):