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satcorr1
Saturation correction procedure 03/14/06
The hee'p runs and hydrogen production runs were analyzed and plots of
xptar vs missing mass were made.
Hee'p setting Ebeam=4021 (electron in the sos, psos=-1.59 GeV)
H(e,e'pi) production data, electron in the sos, setting 1alh2,
psos=-1.73 GeV
kumac
Plots from other heep and production settings can be found here.
Given a plot above, define mm(xptar) as the fitted (green) line.
This function was converted to a change in delta using the derivative
at the central kinematics. The derivative was assumed to be
independent of xptar.
ddelta(xptar) = [ d(delta)/d(mm)]_central * mm(xptar)
Next the function ddelta(xptar) was fit by a parameterization. We
also need to consider the plots from the other central momentum
settings, and so the function ddelta(xptar) was generalized to include
pcentral, ie. ddelta(xptar,pcentral). The work on the
parameterization of this function is shown here:
SOS
HMS - current parameterization (Tanja's 2000 fit) looks good
Description of ps file:
- First
column is the central sos momentum. All central momentum settings
are written end-to-end down the page. Different settings can be
seen by a change in spcentral.
- The second
column is ssxptar. At a given spcentral setting, a plot of
ssxptar vs. ddelta (third column) has the 'banana' shape.
- The third
column is the correction required to fix the 'banana' shape, ie make
the missing mass plots above have a straight, vertical line at
zero. The
correction is a change in delta, while the plots above are ssxptar vs.
missing mass. The change in missing mass was converted to a
change in delta using the derivative.
- The fourth
column, "avg" is the average of ddelta at each setting.
- The fifth
is column three - column four, which is what we need to fit. The
reason that ddelta is not fit instead is that "avg" is a zeroth order
offset that will shift the spectrometer central momentum. This
zeroth order correction is not fit for the same reason the optics
matrix elements do not contain the zeroth order matrix elements.
- The next few columns are the free parameters in the fit, and
column 10 is the fit to column 5.
- Each
spcentral setting has a plot showing (ddelta-avg) vs. ssxptar (data is
the blue points, the magenta is the parameterization). The
spcentral for each plot can be found by looking at the first
column. Whenever the spcentral changes in the first column, there
is a new plot.