[Olympus] momentum spectrum

[Belostotski, Stanislav]

Dear Brian and colleagues,
Thanks a lot for your plot.  In view of our Monday discussion, the =

result is as expected.
The broad Kirill's distribution is due to reconstruction done without =

GEMs with MWPC only. The MWPC spatial resolution is about 0.5mm while =

the total deflection of the lepton in the magnetic field  is 2. to =

2.5mm, i.e. momentum resolution (without GEMs) must be very poor.
This has also been demonstrated by Yuri in his MC studies.
I included Brian's plot in a the attached file where various variants =

(with or without GEMs reconstruction) are presented.
A good cross check is made.
With best regards, StanB

On 13.05.2014 14:43, Brian S. Henderson wrote:
> Hello again,
>
> I have attached a set of plots that looks at the various reconstruction
> parameters for MWPC only tracking for two combined electron runs (7909
> and 7910) and two combined positron runs (7950 and 7951) with the
> corresponding MC data sets.  The only thing like a cut applied was to
> accept only the single best fit track per event (with very loose cuts on
> the max chi^2 and number of iterations).
>
> As you can see, the momentum distributions from the MC look similar to
> what you showed yesterday.  It looks like something has definitely
> changed in the MC since I last used MWPC only tracking, so I apologize
> for questioning your momentum distributions yesterday.  Oddly, the data
> looks more like what I would expect than the MC (at least for the first
> 10 plots which are left arm), especially the missing energy distribution
> which peaks at around 250 MeV for the MC.  This makes me think that
> there could be an issue in the way the MWPC digitization was changed to
> correspond with the GDML changes made to fix the coordinate system
> issues. It also could be that the estimate of the MWPC resolution
> currently used in the digitization is not a good model.  I will take a
> look at this right away this morning to see if I can figure anything out.
>
> Brian
>
> On 05/12/2014 12:59 PM, Suvorov, Kirill wrote:
>> Hi Brian,
>>
>> Could you please send pictures of reconstructed momentum distribution
>> for radiative generator (without GEM digitization) and tell what cuts
>> did you use?
>>
>> best regards, Kirill
>>
>> p.s. We trying to understand why my pictures of momentum distribution
>> are worse.
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