[Eg6_analysis] rtpc alignment

[Stepan Stepanyan]

Nathan,

Thanks a lot for the quick turnaround. I agree misalignment seems
cannot explain discrepancy. But still we need to understand why L/R
momenta are so different, 10-20%. Are track lengths similar, I assume
we have the same pad geometry in both sides.

Regards, Stepan

On 8/30/12 11:02 PM, Nathan Baltzell wrote:
> Dear All,
>
> Continuing the discussion from today's meeting regarding
> the possible effect of misalignment on momentum, I looked
> into the reconstruction code and made some estimates from
> the magnetic field map.
>
> For details:
> http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Alignment
>
> To summarize:
> The effect should be a few-percent error on momenterm per cm
> of misalignment due to picking the incorrect magnetic field
>   from the map.  It's dependent on polar angle, but at elastic
> kinematics we would need much greater than 1cm of misalignment
> for this effect to wholly account for the L/R momentum
> discrepancy we see in the data.
>
> -Nathan
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