[d2n-analysis-talk] BPM Calibration Discrepancy: BigBite vs LHRS

[Diana Parno]

Thanks, Vince. I think this is it -- the BB and LHRS values agree to  
within a couple hundred microns, which is also the level at which any  
individual point on the bull's-eye scan agrees with the corresponding  
Epics variable.

Diana

On Apr 8, 2010, at 3:47 PM, Vincent Sulkosky wrote:

>
> Dear Diana,
>
> My first guess is that the BPM pedestals between the left HRS and BB  
> arms are different.  This can definitely be the case, since we are  
> using two separate sets of electronics.  We typically do a BPM  
> pedestal run at some point early in the runb.  If it exists you  
> should find it and analyze the data to get the BPM pedestals for the  
> BB database.  On the other hand, Bodo's web page says it is not  
> necessary and the pedestals can be taken out in the fits.
>
> I suspect this is what has caused the difference.  The important  
> question is do the beam positions from BB and the Left HRS agree  
> after calibration?
>
> Best Regards,
> Vince
>
> --
>
> Vincent A. Sulkosky, MIT Postdoctoral Associate
>
> CEBAF Center F358
> Jefferson Lab	            Phone: (757) 269-5487
> 12000 Jefferson Avenue      Pager: (757) 584-5487
> Suite #4, MS 12		    email: vasulk at jlab.org
> Newport News, VA 23606	    Fax:   (757) 269-5703
>
>
>