[Eg6_analysis] rtpc vertex/angle study

[Nathan Baltzell]

Hi Raphaël,

It was there before: when I rechecked 1 GeV after noticing this
I used an old skim I still have from epass1v11.  The effect is
small at elastic kinematics, so unlikely our previous calibrations
were affected.

I agree it looks like a reconstruction issue.
I'll see what I can find out.

Yes, CLAS-RTPC vertex peak is ~40% narrower now.

-Nathan



On Wed, 07 Aug 2013 11:58:02 -0500, Dupré Raphaël  
<raphael.dupre at gmail.com> wrote:

> Hello Nathan,
>
> Did you check if this problem was there before the last cooking?
>
> To me it looks like a reconstruction problem, we might want to check
> in the GEM package how exactly the variable is produced. It would be
> good to get the correction at this level don't you think so?
>
> Anyway it is very interesting, we will obtain a much better vertex
> after correction!
>
> Best,
>
> On Wed, Aug 7, 2013 at 6:30 PM, Nathan Baltzell <baltzell at anl.gov> wrote:
>> Hello EG6ers,
>>
>> I noticed an effect in the RTPC in pass1v1 data: an error on the  
>> z-vertex
>> that depends on theta.  It might originate from an error on theta.  If  
>> so,
>> there could be a significant correction for tracks far from 90deg.
>> Here's a little study:
>>
>> https://clasweb.jlab.org/rungroups/lowq/wiki/index.php/RTPC_Vertex_and_Angle_(Aug_7,_2013)
>>
>> Regards,
>> Nathan
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>
>