[Frost] New findings for FROST momentum problems

[Sungkyun Park]

Hi Brian,

Your result is very impressive so I want to check the vertex time in my code.

1.  What is the vertex time you used?
     I have also used the concept the vertex time in my code.
     I get the information of st_time and st_len from GPID bank.

       The vertex_time = st_time - st_len/(beta*30) 
 
         * st_time : ST calibrated time fro this track [ns]
         * st_len : track length from origin to ST [cm]
         * 30 : the velocity of the light [cm/ns]

2. In page 4, what does "p p init", "p pi+ init", and "p pi- init" mean? 
    I guess "p pi+ init" is made in gamma p -> p pi+ (pi-)
    and the histograms are momentum of p and pi+ in butanol and ch2 target, right?
   I do not understand what the red and black lines are.

Sung
Florida State University



----- Original Message -----
From: Brian Vernarsky <soulish at gmail.com>
Date: Wednesday, November 17, 2010 2:35 pm
Subject: [Frost] New findings for FROST momentum problems
To: FROST <frost at jlab.org>

> Greetings all,
> 
> I have been continuing to work on finding the source of the momentum
> discrepancies we see between the butanol and CH2 targets.  I tried to
> look into the tracking code, but could not find any problems there.
> So I started to look at some other reactions than the gamma p -> p pi+
> pi- () reaction, and when I looked at the single track reactions I
> found what might be the source of our problem, the start counters.  I
> have written up all of my findings in a presentation you can find at:
> 
> http://www.andrew.cmu.edu/user/bvernars/FROST_update_2010-11-17.pdf
> 
> It is a somewhat large file, around 10 Mb.  Please let me know if you
> have any questions or ideas.  Thanks
> 
> Brian
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