Perhaps, we can resolve this by running unpol deuterium for false
asymmetry. Keep in mind that Pz from quasi-elastic channel also appears
to be large.
Vitaliy
Chi Zhang wrote:
>Hi, all
>
>I checked the data after reading Genya's email when I got back from
>the fire work show.
>
>Here is my fitted values for Pzz, and the atatched figure shows the fitted
>theory curve with the data.
>
>Take target spin angle at 32 degrees. I have:
>from Parallel kinematics data only: 52.3+-2.5%
>from Perpendicular Kinematics only: 61.4+-1.5%
>from difference from the two kinematics: 56.9+-1/4%
>
>Consider that Genya uses a model that predicts smaller T20, I think my
>number is "consistant" with 61.4*1.2=67.2% on his side.
>
>Note that the difference in Pzz fitted from the two kinematics can be
>canceled out by playing with spin angle, while the fit from the
>"difference" is very INSENSITIVE to spin angle. So 56.9 would be the
>number I report.
>
>I am not sure if 57% is still TOO high to be true. But I am much more
>willing to believe it than 85%. It would be a very good news if it is in
>fact 57%.
>
>However, if you look at the plot, you will see that at Q2>=0.25(Gev/c)^2,
>(the 3rd point in all three figures) data point is biased toward VERY
>LARGE asymetry which I believe is NOT real. Also please just ignore the
>4th point which contains all events passing my cuts with Q2>0.35. In one
>of the figure, the 4th point has no error bar which means 0 count is found
>in at least one of the spin states.
>
>If Pzz if fitted by integrating all data into ONE bin, we will get a very
>large Pzz due to the weird behavior in the 3rd bin. I think this shows the
>limitation of the 1-bin method to determine Pzz.
>
>I think the problem of weird Q2 evolution is likely to be in
>detector/software. I would like to use this as an opportunity to remind
>every body that our resolutions are still at 30MeV, 1deg, 2.5cm level. I
>do not think we will be able to move further with "PHYSICS" before we pay
>the price to make the dectectors work as we expected.
>
>In the end, I would like to give a short report on Wed analysis meeting,
>if there is one, about a program of wire chamber time to distance
>calibration I have been prototyping since the beginning of the summer.
>
>Chi
>
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