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Liam Casey Catholic University of America Adviser: Dr. Franz Klein. FROST: Status of g p -> K + L analysis. Particle Identification. Protons, pions, and kaons are identified by beta and momentum cuts. Kaon region may overlap with misidentified protons and pions.
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Liam Casey Catholic University of America Adviser: Dr. Franz Klein FROST: Status of gp -> K+L analysis
Particle Identification • Protons, pions, and kaons are identified by beta and momentum cuts. • Kaon region may overlap with misidentified protons and pions. • Bad timing information may also give false kaon identification at low momentum.
Momentum plotted against Missing Mass (1) • In the lower energy regions, a L signal is visible when missing mass is plotted. • There is additionally a peculiar sloping line passing through the signal region, which most likely indicates misidentified kaons.
Momentum plotted against Missing Mass (2) • The L signal fades for higher photon energies, while the sloping line remains.
Polarization Observable E: Comparison to Model Predictions (2.478 GeV Beam) • Appears to show some level of agreement with SAID data. • Higher cos q bins are more suspect due to high background contamination. • For full asymmetry, Ptarg ~ 0.8, Pel ~ 0.85 are taken as averages.
Polarization Observable E: More Energy ranges (2.478 GeV Beam)
Conclusions and Further Work • All results are extremely preliminary, but first measurements of E indicate some qualitative agreement with SAID PWA in more trustworthy regions (those not dominated by heavy background). • Energy loss corrections need to be added without losing all the lambdas. • Background subtraction • Measurements of other polarization observables