i am already dividing by the charge (i.e. multiplying by the inverse of
the charge).
and i don't know the beam helicity; the asymmetries in the plots are still
multiplied by the helicity (whatever it is) as well as the vector
polarization (whatever it is). all i assume is that the helicity has the
same magnitude in both the + and - helicity runs.
aaron
On Mon, 11 Aug 2003, vitaliy ziskin wrote:
> Aaron,
> This is exactly the picture I was getting when I did not do the
> normalization by charge correctly. You need to normalize by the inverse
> of what you are normalizing by now. Also, how do you know the helicity
> of the beam in each run? I had to do my analysis by hand just because
> of the fact that we had a problem with ADC channel in charge of the beam
> helicity.
>
>
> Cheers, Vitaliy
>
> Aaron Joseph Maschinot wrote:
>
> >i have performed a separate analysis on the polarized hydrogen data taken
> >in the past day (i.e. runs 1846-1848, 1850-1852, 1854, 1855, 1860-1863).
> >due to the miscabling error discovered yesterday, i believe that only
> >this data is reliable. i cannot find the theoretical pictures that
> >vitaliy claimed to have found. the data is these plots had charge and
> >coplanarity cuts imposed on them.
> >
> >i don't believe my results. i do not know what the theory says, but this
> >picture looks too high, considering that both the helicity and the vector
> >polarization are still included in these plots. maybe there's an error in
> >the macro. or else blast has problems.
> >
> >to do this analysis, i wrote a new macro called "show_ep_asym2.C"
> >("show_ep_asym.C" is a pre-existing but currently non-working macro.) the
> >macro is fairly easy to adapt. it is also well documented.
> >
> >i am leaving for a while later on in this week. thus, someone else should
> >probably take over the hydrogen asymmetry analysis, as it will surely go
> >on for a while longer.
> >
> >if you care (or are forced) to pick up where i am leaving off, you need to
> >know the following:
> >
> >1) for each run, you need to go to the pro2003/analysis/CRUNCH/v3/
> > directory and run the "lrn" macro, then you need to go to the
> > pro2003/analysis/utils/ directory and run the "flrn.C" macro, and then
> > you need to go to the pro2003/analysis/macros/ directory and run the
> > "charge.C" macro. do NOT run the "charge_t20.C" macro (as we have been
> > doing for the past two months or so).
> >
> >2) the next step is to go to the pro2003/analysis/utils/ directory and
> > look at the "strings.C" file. make sure that it is set up for proton
> > scattering off of a hydrogen target!!!! (this is extremely simple to\
> > do if you just read the documentation at the beginning of the
> > "strings.C" file.)
> >
> >3) you can then run the "show_ep_asym2.C" macro. for example, to
> > calculate the asymmetry in runs 1846-1848, 1850-1852, 1854, 1855, and
> > 1860-1863, type the following:
> >
> > root -l show_ep_asym2.C 1846-1848 1850-1852 1854 1855 1860-1863
> >
> >4) i'm not very experienced with hydrogen analysis. the "show_ep_asym2.C"
> > macro assumes that the H(e,e'p) cross section is given by the
> > following:
> >
> > S( h, P) = S0*(1 + h*P*A_{eN})
> >
> > thus:
> >
> > h*P*A_{eN} = [S( h, P) - S(-h, P)] / [[S( h, P) + S(-h, P)]
> >
> > if this assumption is wrong, the macro is straightforward to modify.
> >
> >5) a VERY GOOD check to run on your hydrogen data is to run the
> > "show_ep_asym2.C" macro only for runs of ONE DEFINITE POLARIZATION
> > STATE (i.e. (h = +1, P = +1) or (h = -1, P = +1)). the first few lines
> > that the macro prints out tell how much charge was collected in each
> > polarization state. the next few lines tell how many hits were
> > collected in each each polarization state. check that charge and hits
> > were collected in only the polarization state pertinent to the runs.
> > this may sound like a funny check, but this error has appeared numerous
> > times in the last couple of months (it even occurred this morning).
> >
> >good luck.
> >
> >aaron
> >
> >
> >
> >
>
>
>
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