[Frost] Official Target/Beam Pol. Table

[lcasey at jlab.org]

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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