Hi Eugene,
thank you for sending this out.
I assume in P.ps the electron offsets are plotted vs. p_e (not p_p) and in
TH.ps the electron offsets are plotted vs. th_e (not th_p)?
A have a few remarks:
Since here we talk about Eloss, the corrections are really only functions
of the momentum, and the angle dependence only comes through the
momentum-angle correlation for elastic scattering.
For the "residual" kinematic offsets, they may depend both on angle and
momentum, however elastic scattering can determine these offsets only as a
function of one coordinate (e.g. momentum) because the other coordinate
(angle) is again correlated with the first one.
If we believe that the origin of the residual offsets is a
property of the detector, then my feeling says it may be better to express
them as a function of the angle rather than the momentum. Reason is that
the corrections expressed as function of angle may be applicable to other
channels as well (such as pion production) which cover significantly
different momentum regions for the same angle.
Ideally, one would wish to express the corrections of reconstructed
variables as a function of a detector-specific coordinate (such as
position along the wire chamber plane).
Regards,
Michael
On Fri, 10 Mar 2006, Eugene J. Geis wrote:
> Proton's momentum loss can be parameterized over
> momentum or over theta. The high polar angle and
> low momentum occupy the same phase space so use only
> one. The parameterizations were done by comparing
> reconstructed MonteCarlo with Eloss on and Eloss off,
> MASCARAD was off for both MonteCarlo runs and thus
> plays no part in this parameterization. Electrons
> proved to not need any parameterization as should
> be expected.
>
> The following polynomials should be added to the
> reconstructed momentum in order to "bump up" the
> proton's momentum to the proper momentum.
>
> Root's 4th degree polynomial fit over
> energy lost vs. momentum gives the following:
>
>
> p0 3.05683e-02
> p1 -1.64857e-01
> p2 3.34062e-01
> p3 -2.99825e-01
> p4 1.00794e-01
>
>
> Root's 4th degree polynomial fit over
> energy lost vs. theta gives the following:
>
>
> p0 5.97905e-02
> p1 -5.29057e-03
> p2 1.73551e-04
> p3 -2.49832e-06
> p4 1.33493e-08
>
>
> Attached graphs can be interpreted as the titles
> given for each plot.
>
> Note: For P.ps and TH.ps, the two plots on the left
> side are for ELOSS ON, and the two plots on the
> right side are for ELOSS OFF!
>
> PARAM.ps is a plot of the profiles subtracted from
> each other. Cuts for good ep-elastic data are
>
> TCut Cutst_L("(qwl==-1&&qwr==1&&
> abs(sqrt((0.85-pwl+0.938272)**2 -
> 0.85*(0.85-2.*pwl*cos(twl*0.01745))-pwl**2)-0.938)<0.04 && abs(fwl-fwr+180.)<3.0)");
>
> TCut Cutst_R("(qwl==1&&qwr==-1&&
> abs(sqrt((0.85-pwr+0.938272)**2 -
> 0.85*(0.85-2.*pwr*cos(twr*0.01745))-pwr**2)-0.938)<0.04 && abs(fwl-fwr+180.)<3.0)");
>
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