Hello Jason,
Thanks for the quick analysis results. I looked at the results
closely and like to say that they are very encouraging!
The target polarization could be low due to the fact that we ran
with a warm cell. However, one can still see by ``eye averaging'' that A1
and A2 seem to have opposite signs and A3 and A4 also, which is what one
would expect. Therefore, I think the result is encouraging!
Question: what is the percentage of the total polarized data used
in your analysis?
Thanks,
Haiyan
========================================================================
Haiyan Gao URL: http://www.tunl.duke.edu/~mep
Triangle Universities Nuclear Laboratory
Department of Physics, Duke University
Office: 426 TUNL Office Phone: (919)-660-2622
Email: gao@tunl.duke.edu Fax: (919)-660-2634
Mailing address: 426 TUNL Building
Science Drive
Box 90308
Duke University
Durham, NC 27708
=========================================================================
On Wed, 14 May 2003, Jason Seely wrote:
> hi everyone,
>
> sorry i missed the analysis meeting today - i meant to show the
> following, but here it is.
>
> i have put a new macro in /macros/ called 'show_ep_asym.C'. this script
> just produces asymmetries and super ratios for each sector, and for both
> beam and target asymmetries separately. to run it, just do
>
> root -l show_ep_asym.C run#
>
> i have included a plot as an example. this plot is for runs 303-306
> 308-309 311-317 323-328, which were supposedly polarized ep runs where
> the target was flipped automatically and the waveplate was taken in and
> out at each fill. there are four combinations of polarization states:
> ++, +-, -+, -- where, for example, +- means (beam is +)(target is -).
> from these, we can form four separate asymmetries:
>
> A1 = (++ - +-)/(++ + +-)
> A2 = (-+ - --)/(-+ + --)
> A3 = (++ - -+)/(++ + -+)
> A4 = (+- - --)/(+- + --)
>
> so A1 and A2 are the asymmetries for constant beam helicity, but
> flipping the target, and A3 and A4 are the asymmetries for a constant
> target polarization, but flipping the beam helicity. note that if
> everything is normalized properly A1 = -A2, A3 = -A4, A1 = A3, A2 = A4.
>
> by comparing these asymmetries to each other, we should be able to get a
> handle on the false asymmetries, and also spot any measured asymmetry
> since, for example A1 and A2 will differ by a minus sign.
>
> anyway, please see the plot. as it stands, i don't think we are seeing
> any asymmetry yet. to produce the plot, the only cuts i made were to
> ask for a + particle on one side and a - particle on the other, that
> their vertex was within z = +/- 10 cm (to try to find particles closer
> to the center of the target where the polarization should have been
> higher) and an adc cut ("(atl>5000&&atr<5000)||(atr>5000&&atl<5000)").
> there is more to be done here, but i just wanted to send the plot out
> and let people know it's there so as the polarized data rolls in, we can
> use this script to find asymmetries.
>
> thanks,
>
> jason
>
> --------------------------------------------------------------------
> jason seely
> 26.650.b
> massachusetts institute of technology
> 77 massachusetts avenue
> cambridge, ma 02139-4307
>
> email: seely@mit.edu
> phone: 617.253.4772/6734
> html: web.mit.edu/seely/www
> --------------------------------------------------------------------
>
>
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