Hi John and all
here are some ed elastic cross section plots.
counts in a large number runs (40cm, 60cm alll together) are plotted vs.
Z, theta_e and Q2. linear and log scale are provided.
red is electron into right, blue is electron into left, back is Monte
Carlo. Magentta is background electron into right, Cyan is background
electron into left, backgounds are presented by filled areas, MC is in
solid line, data are ofcourse in data points with error bars.
In log scale, one can see some messy up and downs at high Q2. In linear
scale, one can see red data is lower than blue data, indicating missing
events when electrons go into right sector.
All plots have "background" overlaid only that only in the log scales
they are visible.
One word about the "cell wall background". It is extracted from about 79kC
of empty target and H2 target runs. H2 runs produce the little hump at low
Q2 end.
Another word about the "background". I believe this does not reflect the
contamination from deuteron e'p channel. The reason is that even though H2
runs are used, ep elastic and ed elastic are two distinct narrow peaks in
kinematics. With the smearing due to resolution, the leak of ep elastic
into ed cuts is very little. However, deuteron e'p is much more spread out
in kinematics, therefore is more likely to appear within ed elastic cuts.
Please excuse me to say again that better resolution will help suppressing
"e'p background".
Finally, there is a macro cross_sec.C, use: root cross_sec.C will produce
the plots along with two others. You can zoom in or change scales then to
see the background and details.
Chi
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