[Hps-analysis] FEE Track Matched Clusters

[Omar Moreno]

Final state particles are made out of both GBL and seed tracks.  The type
of the particle (ReconstructedParticle of HpsParticle) is set to the type
of the track so you should be able to select whichever tracks you want to
use.  The momentum of the FS particle is equal to the momentum of the track
associated with it.

A word of caution, though; when extrapolating GBL tracks to the Ecal, the
GBL track parameters at the target are used.  This is incorrect and, as a
result, FS particles using GBL tracks may be mismatched to a cluster. What
we really want to do is extrapolate the track using the GBL track
parameters at the last layer with a hit in the SVT.  This requires some
additional code which, I believe, Tim is working on.  Furthermore, we still
haven't checked the agreement between the GBL tracks in Java and those
obtained using the C++ refit.  Matt said the GBL tracks look fine so I'm
assuming they are OK, but we should do a thorough comparison.

--Omar Moreno

On Wed, Oct 7, 2015 at 11:01 AM, Sho Uemura <meeg at slac.stanford.edu> wrote:

> You could try making the plots with seed tracks and with GBL tracks. The
> GBL tracks should show better top-bottom agreement on momentum scale, and
> they should also show better resolution (tighter E/p distribution). If you
> see neither of those differences, there might be something wrong with the
> track type code.
>
> Yes, the new pass3 detector should make seed tracks and GBL tracks agree
> better. But bad things will continue to happen if somehow your analysis is
> using seed tracks instead of GBL, or a mixture of both.
>
> On Wed, 7 Oct 2015, Holly Vance wrote:
>
> So I re-ran my code checking that the track type is GBL, and the plots look
>> the same. It seems that these effects will be specifically addressed in
>> this upcoming pass.
>>
>> On Wed, Oct 7, 2015 at 12:25 PM, Nelson, Timothy Knight <
>> tknelson at slac.stanford.edu> wrote:
>>
>> 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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