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Re: GEM tracking [message #8350 is a reply to message #8336] Thu, 30 April 2009 11:55 Go to previous messageGo to previous message
Radoslaw Karabowicz is currently offline  Radoslaw Karabowicz
Messages: 108
Registered: June 2004
Location: GSI
continuous participant
From: *gsi.de
Problem continues...

It seems that my yesterday enthusiastic mail was a bit preliminary.
I have been looking at several tracks at it looked rather ok, however when I look systematicly into the results I have realised that the fitting is still producing not optimal results.
As you may remember, I was giving to the Kalman fitter a Monte Carlo momentum increased by 100Mev/c as a starting value. What I have realized is that the fitter smears the momentum with some sigma, but the reconstructed mean momentum value of many tracks still differs from the MC momenta by a value of 100MeV/c.

I have therefore made two runs of my reconstruction, once with having the start momenta given to Kalman decreased by .5 GeV/c as compared to MC truth, and in the second run I set start momenta as MC truth plus .5 GeV/c. Plots below summarize the results:

Momenta decreased:
StartMom.SetMagThetaPhi(beforeMom.Mag()-0.5,
beforeMom.Theta(),
beforeMom.Phi());

index.php?t=getfile&id=5303&private=0

Momenta increased:
StartMom.SetMagThetaPhi(beforeMom.Mag()+0.5,
beforeMom.Theta(),
beforeMom.Phi());

index.php?t=getfile&id=5304&private=0

Please take a look at the mean value of the distribution, the reco momenta is just smeard, it doesn't come back to MC truth:((.
The next thing I am planing to do is to use the tracks with high p_t. But that will come probably the next week.

yours,
radek
 
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