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Re: GEM tracking [message #8350 is a reply to message #8336] |
Thu, 30 April 2009 11:55 |
Radoslaw Karabowicz
Messages: 108 Registered: June 2004 Location: GSI
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continuous participant |
From: *gsi.de
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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());
Momenta increased:
StartMom.SetMagThetaPhi(beforeMom.Mag()+0.5,
beforeMom.Theta(),
beforeMom.Phi());
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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