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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