[Frost] About Beam polarization

[Steffen Strauch]

Dear Sung,

You are right.  Whenever the status of the half-wave plate changes the helicity of the beam in the hall flips sign.  At

http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Helicity_assignment_for_g9a

different analyzes are summarized.  For the single-pion observable E, I get consistent results per run throughout g9a.  That does only mean, however, that the product of target polarization, helicity-bit status, half-wave plate status, and beam polarization is correct.   Whether or not "helicitybit = 1" means helicity plus or minus in the hall depends on many factors.  If you need to find out for sure what the half-wave-plate status is for each period I suggest you search the electronic log book.  I briefly did that and many run summaries contain this information.  It would be good to post these results (including the reference links to the log book) at the frost wiki page.

All the best,
Steffen



On May 24, 2011, at 12:10 PM, Sungkyun Park wrote:

> Hi Eugene and Steffen
> 
> I have a question about helicity signal.
> In Table 5 of Steffen's CLAS-ANALYSIS 2004-118,
> the helicity signal from TGBI-bank latch1 is changed by the half-wave-plate positions.
> In our data, we also have half wave plate IN or OUT.
> 
> In CL data,  
>  Period 1 (55521-55536) : half wave plate IN.
>  Period 2 (55537-55555) : half wave plate OUT.
>  Period 3 (55556-55595) : half wave plate IN.
>  Period 4 (55604-55625) : no idea  
>  Period 5 (55630-55678) : no idea
>  Period 6 (56164-56193) : no idea  
>  Period 7 (56196-56233) : no idea
> 
> Q1) In period1, 1(latch1) means beam-helicity is minus and in period2, 1(latch1) means beam-helicity is plus.
>       That is, period 1 and period 2 has the different beam-helicity when they have the same value in latch1
>       Is this right?
> Q2) What are half-wave-plate from period 4 to period 7?
> 
> Eugene) Who is our next chef of g9b? Natalie?
>             I will start the another job for DC-Calibration.
> 
> Sung
> Florida State University
> 
> 
> 
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> 
> 
> <sp06k.vcf>