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Re: Reconstruction macro crash [message #11861 is a reply to message #11857] Mon, 23 May 2011 15:57 Go to previous messageGo to previous message
Gianluigi Boca is currently offline  Gianluigi Boca
Messages: 177
Registered: March 2004
first-grade participant
From: *gsi.de
Lia Lavezzi wrote on Mon, 23 May 2011 13:36

Hi Stefano,
actually there is a test to decide whether the track can reach the GEM plane or not with a simple and quick helix extrapolation to the first plane (no GEANE, just math).
In my thoughts that should have been enough to throw away also these pz = 0 tracks, but clearly there is something which goes wrong.

...I was wondering (looking in the log) how is it possible that a track with:

first mom = (0.077671,-0.047670,0.000000)
first pos = (16.552964,0.397360,0.000000)
last mom = (-0.085107,-0.032588,0.000000)

has last pos = (14.075058,-26.674008,-4.163533)...
Gianluigi, this comes from your PR, do you have any idea?
Ciao,
Lia.



In principle no physics prevents from having a track with Pz=0, and the Pattern Recognition in fact can find a track with Pz =0.

Pz =0 when one of the parameter I use to parametrize the Helix is very large.
Also, Pz=0 for a track is not in contraddiction, from the Pattern Recognition algorithm point of view, with having
the Z position of the last point NOT EXACTLY 0; certainly it must be CLOSE to zero [as in the this example, where
last pos = (14.075058,-26.674008,-4.163533) ].

Anyway, I am investigating possible bugs in the code right now

Gianluigi




 
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