[Frost] Official Target/Beam Pol. Table

[Michael Dugger]

Hi,

I agree with Liam that there should be a single FROST approved table.

-Michael

On Wed, 23 Feb 2011, lcasey at jlab.org wrote:

> Um, sorry.  There are two tables on that page (
> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Checking_Target_Polarisation
> ), one of them agrees with Steffen's table for run group 5 and the other
> does not.  So probably group 5 is not an issue after all and that's just a
> table transcription error.  I would still like to see an official table
> reflecting those differences for the first 3 run groups though.  Thanks.
>
> Peace,
>
> Liam
>
>> Hi all,
>>
>> I know we've been through this a thousand times, but I can't really let it
>> drop until we have some official table of consistent polarization
>> direction values that works not just for E, but also for recoil double
>> polarization observables that depend only on the target or beam
>> polarization direction.
>>
>> Jo has already gone over the target polarization directions a second time.
>> I don't think that needs to be done again, but we need to make sure the
>> meaning of the helicity bit in terms of photon circular polarization is
>> consistent with both Jo's target polarization direction and the overall
>> sign of E.  In this spirit, I've edited the table I had initially put in
>> when we were all trying to work out the helicity assigment to reflect what
>> I think the table should look like. Note that for the first three run
>> groups I have removed the negative sign from the electron beam
>> polarization and changed the sign of the target polarization to agree with
>> Jo's table.  It stands to reason that if the target direction is incorrect
>> here and the E sign is correct, then the odd change in the meaning of the
>> helicity bit between 1.6 and 2.4 GeV data must also be incorrect.
>>
>> That's the simple part, I think.  There's one more thorny issue, which I
>> signify with question marks.  It was never suggested that the electron
>> polarization direction was negative for group 5. Nonetheless, the signs
>> from Jo's table (+/-) and Steffen's table (-/-) are different here.  In
>> this case perhaps the electron beam polarization should be changed to
>> negative.  At any rate, I'd like to talk about it and making an official
>> table tomorrow.
>>
>> Peace,
>>
>> Liam
>>
>>
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