[Clas_hadron] Abstract for contributed QNP 2012 talk (April, 2012)

[Barry Ritchie]

Thanks for pointing me to that section of the thesis (5.5, p. 82) and providing a copy, which refreshes my memory on the analysis. 

At least some aspects of the analysis presented in the thesis have likely been voided by work on the polarization estimates since the thesis was put together. Please look at Mike's presentation at http://wwwold.jlab.org/Hall-B/secure/g8b/ASU/Overlap.pdf to get a flavor of just how serious these problems are.  At the very least, the new systematics and consistency studies will need to be addressed if the SDME results are to become more than preliminary.
 
The thesis says: "The current systematic errors on the mean polarization are ∼5%  for the ECP=2.1 GeV data and ∼10% for ECP =1.9 GeV data." I'll defer to Mike, Volker, and Ken as to what the best estimates of the uncertainties are, but I do believe the consensus is that the systematic errors at 2.1 GeV are considerably larger than 5%. I also noted in the thesis that the same polarization was assumed for perp and para. That's probably not correct either.  

---BGR


Professor  Barry G. Ritchie 
Department of Physics 
Arizona State University 
Tempe, AZ  85287-1504 
  
Telephone: (480) 965-4707 
Fax: (480) 965-7954 

-----Original Message-----
From: Philip L. Cole [mailto:cole at jlab.org] 
Sent: Saturday, January 07, 2012 12:08 PM
To: Barry Ritchie
Cc: clas_hadron at jlab.org; jjuliansb at yahoo.com
Subject: Re: [Clas_hadron] Abstract for contributed QNP 2012 talk (April, 2012)

Barry,

Thanks for your comments.  The bottom line is that our statistics are such
that the statistical errors are greater than those from the systematic
uncertainties.  We extracted 8200 phis over these two energy settings, and
when binned in cos_theta, there are just not that many phis per bin.
Please see
<http://wwwold.jlab.org/Hall-B/general/thesis/salamanca_thesis.pdf>.  The
thesis served as the CLAS analysis note.  And the analysis was approved in
this past November.  The issue of systematics and jitter of the coherent
edge is addressed in 5.5 Summary of SDMEs on p. 87.  Also, please look at
Fig. 6.2 on page 92 to see the quality of the fits to the data (with
statistical errors).

Regards,
Phil

> Phil, Mike Dugger has reminded me that it's actually the 2.1 edge setting
> that is really bad, not the 1.9 GeV edge setting. The others have more
> reasonable systematic problems (that is, no where near as severe as the
> 2.1 GeV data set) But all edges required systematic corrections.
>
> ---BGR
>
> Professor  Barry G. Ritchie
> Department of Physics
> Arizona State University
> Tempe, AZ  85287-1504
>
> Telephone: (480) 965-4707
> Fax: (480) 965-7954
>
> -----Original Message-----
> From: clas_hadron-bounces at jlab.org [mailto:clas_hadron-bounces at jlab.org]
> On Behalf Of Barry Ritchie
> Sent: Friday, January 06, 2012 9:56 PM
> To: cole at physics.isu.edu; burkert
> Cc: clas_hadron at jlab.org
> Subject: Re: [Clas_hadron] Abstract for contributed QNP 2012 talk (April,
> 2012)
>
> Phil, out of curiosity, does the (perhaps substantial) uncertainty in the
> photon beam linear polarization have any significant effect on the SDME
> results you intend to present (particularly considering the really big
> problems with the 1.9 GeV coherent edge)? Or are you using the systematic
> corrections for the polarization as suggested by Volker and Mike to get
> your results?
>
> ---BGR
>
> Professor  Barry G. Ritchie
> Department of Physics
> Arizona State University
> Tempe, AZ  85287-1504
>
> Telephone: (480) 965-4707
> Fax: (480) 965-7954
>
> -----Original Message-----
> From: clas_hadron-bounces at jlab.org [mailto:clas_hadron-bounces at jlab.org]
> On Behalf Of Philip L. Cole
> Sent: Friday, January 06, 2012 9:31 PM
> To: burkert
> Cc: clas_hadron at jlab.org
> Subject: Re: [Clas_hadron] Abstract for contributed QNP 2012 talk (April,
> 2012)
>
> Colleagues,
>
> Please find attached the improved version of the abstract for the QNP 2012
> contributed talk.
>
> Phil
>
>> Hi Phil,
>>
>> you need some introduction as to what the measurement was supposed to
>> accomplish.
>> Also, you should state that the experiment was done with the CLAS
>> detector and carried
>> out by the CLAS collaboration.
>>
>> Cheers,
>> Volker
>>
>>    On 1/6/12 4:15 PM, Philip L. Cole wrote:
>>> Colleagues,
>>>
>>> Please find attached my proposed abstract to be presented as a
>>> contributed
>>> talk at the QNP 2012 conference, which will convene April 16-20, 2012.
>>>
>>> Regards,
>>> Phil
>>>
>>>
>>>
>>> This body part will be downloaded on demand.
>>
>> _______________________________________________
>> Clas_hadron mailing list
>> Clas_hadron at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/clas_hadron
>
>
> --
>    Philip L. Cole
>    Associate Professor
>    Idaho State University
>    Department of Physics
>    Pocatello, Idaho 83209
>    (208) 282-5799  office
>             -4649  fax
>     cole at athena.physics.isu.edu
>     http://www.physics.isu.edu/staff/cole.html
>
>
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-- 
   Philip L. Cole
   Associate Professor
   Idaho State University
   Department of Physics
   Pocatello, Idaho 83209
   (208) 282-5799  office
            -4649  fax
    cole at athena.physics.isu.edu
    http://www.physics.isu.edu/staff/cole.html