[Hps-analysis] FEE Track Matched Clusters

[Nelson, Timothy Knight]

So the GBL track isn’t used for this collection? (I though GBL “healed” the v2 momentum scales).

T
 
> On Oct 7, 2015, at 9:18 AM, Sho Uemura <meeg at slac.stanford.edu> wrote:
> 
> SeedTracks in v2 geometry have big momentum shifts like what you're seeing. GBLTracks have better momentum in v2 than in v1.
> 
> We think this is because v1 has systematic misalignments across the detector (e.g. L1-3 vs. L4-6), and v2's misalignments are due to measurement error and are less correlated from sensor to sensor. SeedTracks are very sensitive to alignment of the first layers of the SVT, so the momentum measurement is worse in v2. GBLTrack momentum is in a sense "averaged" over the length of the track, so the momentum measurement is better in v2.
> 
> SeedTracks are very sensitive to misalignment in
> 
> On Wed, 7 Oct 2015, Nelson, Timothy Knight wrote:
> 
>> Hi Holly,
>> 
>> It turns out the v2 (survey) alignment used in pass 2 is no better (and possibly worse) than the v1 (as designed) alignment (the assembly error appears to have been as small as or smaller than the survey error, where 50 microns is a big effect).  Nonetheless, you shouldn?t be seeing those effects with either one, so something is obviously wrong.    I?m not sure which track collection is used for the FP Particle collection, but our best fits for FEE should have errors at the 1% level, not the 10% level, in both top and bottom.
>> 
>> Sho?  Omar? Pelle?
>> 
>> Tim
>> 
>>> On Oct 7, 2015, at 8:20 AM, Graf, Norman A. <ngraf at slac.stanford.edu> wrote:
>>> 
>>> Good Morning Holly,
>>> I?m sure the experts will also chime in, but I?d like to point you to the presentations at
>>> yesterday?s SVT meeting where there was quite a bit of discussion of alignment.
>>> https://confluence.slac.stanford.edu/display/hpsg/10.6.2015+Weekly
>>> Omar had also shown some slides (not yet posted) from his analysis of the v3
>>> detector, which I assume he will be showing either tomorrow or Friday.
>>> Norman
>>> 
>>> From: Hps-analysis [mailto:hps-analysis-bounces at jlab.org] On Behalf Of Holly Vance
>>> Sent: Wednesday, October 07, 2015 7:24 AM
>>> To: hps-analysis at jlab.org
>>> Subject: [Hps-analysis] FEE Track Matched Clusters
>>> 
>>> Hi,
>>> 
>>> I analyzed the skimmed FEE events from pass 2 studying track matched clusters at the Ecal. I made a very short summary in the attached pdf, and I was wondering if anyone from tracking can comment on why the momentum for these tracks is 10% high/low.
>>> 
>>> How well do we know the SVT planes positions? I assume the survey cannot tell us this precisely.
>>> 
>>> -Holly
>>> 
>>> 
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>> 
>> 
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