Re: Better MonteCarlo comparisons and conclusions.

From: Michael Kohl (kohlm@mit.edu)
Date: Fri Feb 24 2006 - 14:56:37 EST


Hi Eugene,

1) Can you make plots for BeamEnergy, Electrons and Protons where
    "with MASCARAD" and "no MASCARAD" are overlayed (with different colors
    or symbols)?
2) If possible, also real reconstructed data should be plotted overlayed,
    too.

3) Repeat 1) and 2) with energy loss turned off in comparison with real
data.

I'm still not convinced that internal radiation (MASCARAD) in combination
with finite momentum resolution does not move average values.

I discussed your latest plots with Vitaliy. We (or I) have some
questions and remarks:
a) What exact W-cut are you using for the profile histograms?
b) Did you use the same W-cut for the real data in New_BeamEnergy.pdf?
c) How does the W spectrum for real data compare with W.ps?
d) Comparison between MASCARAD on and off is impossible if results are
    plotted in different panels with different scales.
d) Electrons*.ps: Without MASCARAD, electron angle in the left sector
    seems shifted by 0.5s degrees but not in the right sector?! With
    MASCARAD, also electron angle in right sector gets a shift.
e) Are the wiggles in the angular distributions also present in the data?
f) BeamEnergy*.ps: Could the falloff of the reconstructed beam energy from
    proton coordinates at angles 60-65 degrees be due to the increasing
    energy loss (these are the slowest protons?
g) Electrons_Masc.ps: when you subtract theta_e(p_e) from theta_e_crunch,
    what p_e are you using to calculate theta_e? Radiated or unradiated? If
    the radiated momentum is used, theta_e_calc will be off. You should
    rather construct theta_e_crunched - theta_e_tossed.

Please save and send canvases also as *.root, this allows one to
zoom in interactively.

Thanks and best regards,

    Michael

  On Wed, 22 Feb 2006, Eugene J. Geis wrote:

> I've included 7 plots here.
>
> Energy Loss is ON in both: MASCARAD on, and MASC off.
> Strict W Cut is now included in ALL histograms except
> W.ps
>
>
>
> W.ps - is invariant mass plotted on top of one another.
> SLIGHT SHIFT... but very small. ~5 MeV.
>
> BeamEnergy_*.ps - Reconstructed Beam Energy from electron
> and proton, a strict W Cut is included
> for both MASC on and off. Beam Energy
> drops ~5 MeV when MASC is on.
>
> Electrons_*.ps - Typical kinematic relations of ep-elastic
> Looks bad for lowest Q^2 electrons.
> Everything else is relatively flat. MC
> would suggest to me to reject electrons
> below 26 degrees.
>
> Protons_*.ps - Same Typical kinematic relations of ep-elas
> for proton. Not good at all below 36
> degrees and above 68 degrees. Also not good
> below 320 MeV and above 900 MeV. MonteCarlo
> would suggest to me that we should neglect
> any events within those ranges, UNLESS elec
> kinematics provide the proton information.
>
> New_BeamEnergy.pdf - For the heck of it, the actual data's
> reconstruction of the beam energy. Same
> color coding as the MC BeamEnergy postscript
>
>
>
> I believe I should now generate some Hydrogen Monte Carlo
> with NO energy loss to be sure of the results. Dependency
> on the discrepancies observed in proton theta will tell us
> whether energy loss should be included in
> reconstruction (both p and theta dependent), or should be
> inserted after (p-dependent discrepancies only).
>
> I think:
> If the former situation is the case, energy loss should be
> put into Reconstruction and then kinematic corrections
> should use the |MASCARAD on/E-Loss off| reconstructed Beam
> Energy for the benchmark. If the latter is
> true (p-dependent only), then kinematic corrections should
> use the |MASCARAD on/E-Loss on| reconstructed Beam Energy
> for the benchmark. Energy loss would be implicit in the
> kinematic corrections and wouldn't even need implementation.
>
> Replies are expected and more than welcome.
>
> -eugene
>
>
>
>
>
>
> ----------------------------------------------------------
> Eugene Geis
> PhD Student, Physics Department, ASU
> Research Affiliate, MIT-Bates Laboratory of Nuclear Science
> eugene.geis@asu.edu
> ----------------------------------------------------------
>

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