Hi Rich and Jan,
Thanks for pointing out the sign problem. The reason I included the
LCIO document is that its treatment of the meaning of the reference
point is more pedagodical. I have updated the wiki page.
Rob
Jan Strube wrote:
> Hi Rich,
>
> well spotted. As Nick has pointed out a long time ago, the LCIO document
> is inconsistent and the d0 sign is wrong.
> At least in eq. 3 if that's what you mean. That's one reason why I have
> linked the L3 note in our javadoc and not the LCIO doc, yet. If there's
> an updated version, we should link that, of course.
> I have written up the track parameters in org.lcsim, which are also what
> I think the real LCIO parameters are, in
> contrib/JanStrube/vertexing/vertexing.pdf.
> This is just a draft, but very detailed, and it underlies the
> conventions that are used in HelixSwimmer and everything else I am
> working on.
>
> Cheers,
> Jan
>
>
> On Nov 27, 2007, at 6:36 PM, Richard Partridge wrote:
>
>> 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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