STAR QA Board

[Geary Eppley <eppley@rice.edu>]

Hi Gene:

Thanks. The offset matches L4 which does VPD-TPC gets -2. The RMS is  
also about the same as L4 and about the same as Run 17.

If I understand the earlier emails, you use fast offline with modified  
parameters to get this data.

Do you have a Vx vs Vy plot for this data?

-Geary

Quoting "Van Buren, Gene" <gene@bnl.gov>:

> Hi, Geary
>
> On Dec 27, 2021, at 1:02 PM, Geary Eppley  
> <eppley@rice.edu<mailto:eppley@rice.edu>> wrote:
> The central Vx vs Vy central distribution shown Friday has a radius  
> of order 1mm. The L4 distribution has a radius of order 1 cm. Do you  
> know what causes that difference?
>
> I do not know exactly what L4 is doing, but my best guess is that  
> they are using no BeamLine constraint at all.
>
>
> We are interested in VPD-TPC Vz offset to see if any adjustments  
> need to be made. L4 consistently shows and offset of -2 cm or less.  
> The RMS is just slightly worse than Run 17, which is not bad  
> considering the current problems with the active splitter.
>
> What offset do you see in your analysis?
>
>
> I'm attaching a histogram of (Vtx_z,tpc - Vtpx_z,vpd) from the data  
> I used to determine the BeamLine last Tuesday. Hope that's useful.
>
> -Gene
>
> [cid:5FA1EB5A-4C18-43E5-B139-E2BF69938FDB@attlocal.net]