Yes you are right. However I was referring to the integrated charge
from the scalers. Even then, you can cut inside a fill. It only
applies to weekend data. Beam helicity is a whole topic on his own.
Good that vz started it.
-- t
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Thu, 14 Nov 2002, Chris Crawford wrote:
> from tancredi's message, Re: [BLAST_SHIFTS] runplan 11/12, the integrated current
> may not be very accurate.
> >Yesterday data was inhibited during ramp/stacking but not the charge,
> >so they may be useless in terms of false elicity asymmetries.
>
> instead of putting the epics stuff in init.C, could ntuple.C just write out the
> integrated current for each helicity for each run?
>
> --chris
>
>
> Vitaliy Ziskin wrote:
>
> > I have attempted to look at the beam helicity asymmetry in run 2814 taken last
> >
> > night with 500k events in it. I used the epics information about the lamda half
> >
> > plate in/out at the source. The situation for this run is following:
> >
> > Integrated current for positive helicity: 166.604 Coulombs
> > Integrated current for negative helicity: 194.006 Coulombs
> >
> > So, we took slightly more data with negative helicity, where I define negative
> >
> > helicity as half wave plate in. I added a ntuple variable to the eep ntuple
> >
> > call "hel" ( the same entry is made into the epics ntuple). When I plotted
> >
> > the raw paddle hits (normalized to the Intergrated current) from the eep ntuple
> >
> > the difference between pos and negative helicity was sizable, which makes sence
> >
> > since we know that the noise is not linear with the current. When I plotted
> >
> > paddle hits for protons using "plnn" and "prnn" cuts the situation improves.
> >
> > I include a plot that generated with macro show_hel.C (residing in the development
> >
> > directory). What is ploted is the number of proton hits in the paddles integrated
> >
> > over all paddles on the other sides with the appropriate cuts from cuts.C (note that
> >
> > "plnn[6]" does not exist and thus shows more events) for negative helicity (red)
> >
> > and positive helicity (black). Top left shows protons on the left and top right
> >
> > shows protons on the right. Underneath them is the plot for Left side and Right
> >
> > side asymmetry takes as \frac{N_{-} - N_{+}}{N_{-}+N_{+}}.
> >
> > More statistics is needed, but I can't include more runs since current init.C
> >
> > does not load different epics ntuple needed to calculate Integrated current for
> >
> > each asymmetry.
> >
> > Let me know what you think.
> >
> > Cheers, Vitaliy
> >
> > =====================================================================
> > Vitaliy Ziskin Tel: (617)253-9209
> > MIT 26-547 http://www.lns.mit.edu/people/vziskin/
> > 77 Massachusetts Ave
> > Cambridge, Ma
> > 02139
> > ======================================================================
> > "For long you live and high you fly
> > And smiles you'll give and tears you'll cry
> > And all you touch and all you see
> > Is all your life will ever be"--Pink Floyd
> >
> > ------------------------------------------------------------------------
> > Name: hel_asymm.ps
> > hel_asymm.ps Type: Postscript Document (application/postscript)
> > Encoding: 7bit
> > Download Status: Not downloaded with message
>
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