Hi Rob,
It looks to me like the note on the helix parameter convention differs from
my understanding of what we have previously agreed on. Namely, I believe
the sign of d0 is opposite to the "L3 convention". There is a link to the
note describing this in the getTrackParameters method for the track
interface javadocs:
"getTrackParameter(int i)
Get an individual track parameter The track parameters for LCD are
defined as follows IndexMeaning 0 d0 = XY impact parameter 1 phi0 2 omega =
1/curv.radius (negative for negative tracks) 3 z0 = z of track origin (z
impact parameter) 4 s = tan lambda Parameters according to the L3
conventions"
There is a link to
http://www.lcsim.org/software/lcsim/apidocs/org/lcsim/util/swim/doc-files/L3
_helix.pdf in the text L3 conventions.
I don't particularly care what convention we use as long as we are
consistent. So far, I think we follow the L3 convention, and not the LCIO
doc you found.
Rich
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]] On Behalf Of Robert Kutschke
Sent: Tuesday, November 27, 2007 6:20 PM
To: [log in to unmask]
Subject: Revised notes now on the wiki
Hi All,
I have revised the notes that I sent around earlier. They are now on the
wiki:
https://confluence.slac.stanford.edu/display/ilc/FastMC+Track+Discussion
The main changes are:
1) Added Caroline's comments.
2) Added a link to the official LCIO document that defines the track
parameters
and the reference point.
3) Added a link to the definition of what is in the persistent
representation.
4) Changed point 2 and 3 to better represent what we said.
Rob
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