Operators: chris2 kohlm ----
During this ice-coating shift I did some analysis instead of going home as I have become somewhat used to my recent day-night rythm.
I inherited and extended the script show_ep_asym2.C which has been in use for online asymmetry analysis so far.
The new script is named "show_ep_asym_thetae.C" and another one named "show_ep_asym_q2.C". Both scripts show the counts and the charge-normalized yields for both helicity states, and the resulting asymmetries for both the left and right sector. The first one as a function of the electron scattering angle, the second one as a function of the four-momentum transfer squared.
I analyzed all runs with polarized hydrogen at longitudinal holding field since Friday, viz.
2201-2206 2208-2210 2212 2215-2216 2218-2221 2223-2224 2226-2227 2230-2239 2244-2249 2269 2253-2256 2258-2267 2273-2278 2283-2286 2288-2295 2297-2302 2306-2313 2315-2320 2322 2324-2328
Charge in (beam-target) polarization states:
( h, P) charge
-------- -----------
( +1, +1) 5639.0737
( -1, +1) 5505.0469
Plotted results of show_ep_asym_thetae.C and show_epasym_q2.C are attached
(see elog if not attached with the BLAST_SHIFTS-email).
>From the number of counts it is clear that only the first three bins in the asymmetry versus thetae and q2 are meaningful.
It seems like the asymmetry on the right sector is somewhat more diluted.
The yields on the right sector are generally somewhat higher, possibly indicating some extra dilution due to (unpolarized) background contamination.
Interesting to note that the yield at Q2=0.1 is much smaller than for Q2=0.2, which is supposedly an acceptance effect (though the [Mott] cross section is highest for Q2=0.1, already some of the protons at backward angle may get lost (also perhaps because of their low energy) . Would be nice to compare this with an MC.
It should also be further investigated how sensitive these results are to variations of the cut definitions.
Regards,
Michael
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