Re: [Brahms-dev-l] RICH image plane offset

Hi Flemming,

> The physical detector has certainly not been moved, and is accurate to
> better than 1mm.
> The imageplane you talk about is constructed in the code from ideal
> assumption
> on positioning and properties of the mirror.
> Are the numbers different from the previous years ? if yes by how much?

Ok, now I remember. Default values for the offset were set in 2002 reco
(or, actually in brat): SetImagePlaneOffset(Float_t x=0.185, Float_t y=-0.083)

> Is this done with the final T5 geometry ?

I guess you're right - the larger offset comes from the non-optimal T5
geometry. If the correct geometry is in the database now, we'll probably
have much better alignment of the ring centers and reconstructed rings in
the next reco round...

Cheers,

Claus


On Wed, 26 May 2004, flemming videbaek wrote:

> a) I doubt since it is not yet in DB awaiting a few more checks on auau zero
> field runs,
> and DC calibrations for auau.
>
> I recomend one change the offset in analysis, and not in DB, but as
> indicated these are likely not
> final.
> Another note on RICH is that I think the index of refraction should be in DB
> having values store
> at the level of one per 1 to 2 weeks.
>
> flemming
>
>
> ----------------------------------------------------------------
> Flemming Videbaek
> Physics Department
> Brookhaven National Laboratory
>
> e-mail: videbaek@bnl.gov
> phone: 631-344-4106
> ----- Original Message -----
> From: "Claus O. E. Jorgensen" <ekman@nbi.dk>
> To: "brahms-dev" <brahms-dev-l@lists.bnl.gov>
> Sent: Wednesday, May 26, 2004 11:08 AM
> Subject: [Brahms-dev-l] RICH image plane offset
>
>
> >
> > Hi,
> >
> > I just checked the alignment of the RICH image plane - this is done using
> > the CheckGeometry option in the rich pid module (which gives the radial
> > distance from the single hits to the reconstructed ring as function of
> > phi).
> >
> > It looks as is the image plane is off by ~0.35 cm. This can be fixed by
> > moving the image plane position in the software
> >
> > richPidModule->SetImagePlaneOffset(-0.204,-0.407);
> >
> > or by changing the RICH geometry (rotation) on the bfs platform. How
> > well do we know the RICH position? Was it moved before this run? Should we
> > change the RICH geometry in the db or shift the default image plane
> > position in the reco scripts?
> >
> > Cheers,
> >
> > Claus
> >
> > _______________________________________________
> > Brahms-dev-l mailing list
> > Brahms-dev-l@lists.bnl.gov
> > http://lists.bnl.gov/mailman/listinfo/brahms-dev-l
> >
>
>

_______________________________________________
Brahms-dev-l mailing list
Brahms-dev-l@lists.bnl.gov
http://lists.bnl.gov/mailman/listinfo/brahms-dev-l