[Hps-analysis] py/pz reconstruction

[Sebouh Paul]

I am unable to access the svt cluster-size information using the DST.  I am
guessing it is somewhere in the LCIO?  Rafo, could you send me the code you
used to create the similar graphs using LCIO yesterday, so I can try
changing it to only include tracks with more than one strip in the 1st or
2nd layer?

On Fri, Apr 1, 2016 at 12:49 AM, Nelson, Timothy Knight <
tknelson at slac.stanford.edu> wrote:

> Hi Sebouh,
>
> Pretty cool. I count 19 peaks in ~0.113 units of tanLambda, so each peak
> is ~0.113/19 = 0.000595 in tanLambda (which is dy/dz between the two hits
> in L1 and L2, assuming that this is the track state at the vertex).  For
> layers separated by dz=100 mm (e.g. layers 1 and 2), that means the peaks
> represent a difference in rise of 100mm*0.000595 = 60 microns.  That is the
> strip pitch.  For this pattern to appear, some things need to be true:
>
> - a significant fraction of clusters have only one strip: true.
> - angular alignment around the z-axis between L1 and L2 must be so good
> (shockingly good, actually) that the positions of strips are coherent
> independent of the position of the hits along the strips: apparently true
> in the top but not in the bottom.
>
> So… here’s a test: make the same plots but require that tracks have more
> than one strip in the cluster (in either layer).  I believe that should
> kill this pattern.
>
> Tim
>
> > On Mar 31, 2016, at 8:04 PM, Sebouh Paul <sebouh.paul at gmail.com> wrote:
> >
> > Here are the plots using tanLambda, for GBL tracks.
> >
> > On Thu, Mar 31, 2016 at 7:27 PM, Nelson, Timothy Knight <
> tknelson at slac.stanford.edu> wrote:
> > Hi Sebouh,
> >
> > Can you please provide the tanLambda plot with appropriately fine
> binning?
> >
> > Tim
> >
> > > On Mar 31, 2016, at 3:17 PM, Sebouh Paul <sebouh.paul at gmail.com>
> wrote:
> > >
> > > when using very fine binning, (less than 10 mrad) I see in the
> spectrum of py/pz (which is equivalent to tan_lambda/cos(phi0) )  a sort of
> regular ondulation, but only when looking at electrons in the top half of
> the detector from GBL tracks.
> > > The attached screenshots are from v0 skim of run 5772 in pass6.
> > >
> > > One of the attached screenshots is with the seed tracks (no
> ondulation), the second one is with gbl tracks (which has ondulations only
> in electrons on the top half of the detector), and the third one is a
> finer-binned zoom in of the second graph to highlight the ondulation.
> > >
> > > Do any of you all have any idea what might be causing this?  This
> happens in both the DST and the LCIO, so it's probably not caused by the
> DST-maker
> > >
> > > Note:  I also found that if I drop the cos(phi0) from the formula that
> I am plotting, I still see the ondulation, so this might just be something
> to do with tanLambda, and not necessarily the combined formula
> tanLambda/cos(theta)
> > >
> > > <Screen Shot 2016-03-31 at 5.50.34 PM.png><Screen Shot 2016-03-31 at
> 5.56.34 PM.png><Screen Shot 2016-03-31 at 6.02.06
> PM.png>_______________________________________________
> > > Hps-analysis mailing list
> > > Hps-analysis at jlab.org
> > > https://mailman.jlab.org/mailman/listinfo/hps-analysis
> >
> >
> > <Screen Shot 2016-03-31 at 10.53.55 PM.png><Screen Shot 2016-03-31 at
> 10.57.40 PM.png><Screen Shot 2016-03-31 at 11.00.25 PM.png>
>
>
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