_ With 20/20 wisdom, it seems surprising that the CC counter have such
large effect on the dilution factor. They are of course expected to
help at large angles but there we have a large error bar anyways so that
should not affect the result for the tgt dilution factor.
_ I attached 3 files for the 180 deg data set (the CC were always on en):
asym180_nocuts (read: no further cuts other than pm, vertex, coplanarity,
trigger type) should be compared to asym180_gcuts and asym180_cc were
the graphical banana cut and the CC are added.
As you can see from the fit results a la VZ, the dilution factor does not
change at all. Note that the optimal dil.fact. here is calculated by
comparing the chi2 in steps of 0.01. Onyl the uncertainty changes a little.
_ I think the validity of nocut/CC/gcuts should be further determined by
comparing yields to MC, which of course is not so immediate since that
depends on 4 relative efficiencies (that is our big problem relative
to nikhef were we had only one CC, good or bad that it was).
_ I don't think we can skip cross sections and understand efficiencies,
with an eye to optimal data S/N at larger angles,q2. but hopefully that
will come. On the other hand means we certainly should expect to have found
good events up to theta ca 40 deg.
Regards,
-- tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Wed, 10 Sep 2003, vitaliy ziskin wrote:
> Wang,
> You are right. I just checked and my assumption that over such a long
> period (12hours) the total charge in each helicity state will be the
> same. However, I have to say that it's not the case. Still I'm
> suprized that it make such a big difference. My result is right=0.12
> and left=0.11 (down from 0.18 and 0.15). I have to say that the reason
> I added cerenkov in the cut is to get rid of this painful left/right
> asymmetry, which I think still does the job. However, the "inhancement"
> in the asymmetry came as extra, erroneously, as it seems now. This means
> that the result for 0 degrees agrees with result for 180 degrees (13
> both sides). So there was no deteriation in the target cell over a
> period of two weeks. Whether the af effects the asymmetry or not is
> still not clear. The plot that you showed for that is not helpfull
> since you can not look at the asymmetry for one run (or fill) due to
> very low statistics. You need to add statistics over a day and compare
> af for that day.
>
> Cheers, Vitaliy
>
> Wang Xu wrote:
>
> >Dear Vitaliy,
> > The meaning of "Cerekov cuts was not valid" is:
> > when you analyze run 2306-2343 with Cerekov
> >Cuts:"ncl>-1"or"ncr>-1"(root -l show_ep_asym2.C 2306-2343),
> > charge is correct, but events after Cerekov cuts are zero.( I
> >believe Cerekov detector did not working well for some reason.)
> > Therefore, if you run show_ep_asym2.C all, charge summed over all
> >runs. But Yield summed all except run 2306-2343. So you can not get
> >correct asy.
> > You can try it. for example (root -l show_ep_asym2.C 2306). You
> >will fully understand what I mean.
> > Best regards,
> > Wang
> >
> >
> >2306-2343,
> >
> >On Wed, 10 Sep 2003, vitaliy ziskin wrote:
> >
> >
> >
> >>I beg to differ.
> >>First of all what do you mean "not valid". Secondly what is this cut
> >>(I>75), if it is a beam current than I don't think you are doing
> >>yourself a favor in making this cut. Also, if the cuts are invalid than
> >>the result should bear this out. As of now you are cutting out about a
> >>quarter of all events but excluding those runs. I still state that
> >>cerenkov do improve the result imensely (dil. of about 0.17), until
> >>proven otherwise.
> >>
> >> Cheers, Vitaliy
> >>
> >>Wang Xu wrote:
> >>
> >>
> >>
> >>>In Ben's previous email, He gave a summary of asy results with respect to
> >>>different cuts.
> >>>The conclusion we drawn from the results is that Cerekov cuts reduced a
> >>>large amount of background. However after I checked asy. run by run. I
> >>>realized the Cerekov cuts was not valid during run 2306-2343.The new
> >>>results (excluded run 2306-2343) are:
> >>>with Cerekov Cuts(I>75) left right
> >>>dilution(Pb*Pt):(asymwccut2.ps) 0.10 0.12
> >>>without Cerekov Cuts(I>75) left right
> >>>dilution(Pb*Pt):(asymwccut2.ps) 0.12 0.10.
> >>>Therefore the Cerekov cuts did not change Asy significantly. Overall Pb*Pt
> >>>is about 0.11.
> >>> Best regards,
> >>> Wang
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
>
>
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