Re: [BLAST_ANAWARE] vector asymmetry at NIKHEF

From: John Calarco (jrc@einstein.unh.edu)
Date: Sun May 02 2004 - 17:53:42 EDT


Hi Vitaliy,

   I am not familiar with the NIKHEF Gen experiment except by skimming
through the thesis. However, if it is correct that they simply took
(N1-N2)/(N1+N2) as in hydrogen (I missed that during my skimming) then
it is certainly incorrect when the tensor analyzing power is not zero.
The other possibility is that a correction factor was applied for the
tensor analyzing power, but then that would be an additional systematic
error contribution.

   In any case, god job in spotting this. My recommendation is that you
analyze your data in such a way as to correctly cancel the tensor
contribution. Then it is not an issue.

                                                                 John

On Sun, 2 May 2004, vitaliy ziskin wrote:

> This question is to people who have the experience with GeN experiment
> at NIKHEF. I'm pouring over Igor's thesis and notice that nowhere did
> he mention that along with a vector asymmetry then have a tensor
> asymmetry since Pzz = 1-3n0. In buiding his asymmetry he used formalism
> similar to a hydrogen vector asymmetry, disregarding tensor piece (see
> John C. message a while ago). Of course, the tensor piece in a
> quasi-elastic channel will only contribute at large missing momentum (it
> is identicaly zero at zero missing momentum). But at heigher missing
> momentum its contribution can be upto 15% of the asymmetry. This this
> accounted for.
>
>
> Cheers, Vitaliy
>
>

-- 
John R. Calarco
Dept. of Physics
Univ. of New Hampshire
Durham, NH 03824
phone: (603)862-2088
FAX:   (603)862-2998
email: calarco@unh.edu



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