FROST: Status of  p -> K +  analysis Liam Casey Catholic University of America Adviser: Dr. Franz Klein

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.

Missing Mass Plots: Finding 

Missing Mass Plots: Finding  (cont)

Momentum plotted against Missing Mass (1) ● In the lower energy regions, a  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  signal fades for higher photon energies, while the sloping line remains.

Misidentified Kaon: Plot particle identified as Kaon with Proton Mass

Misidentified Kaon: Plot particle identified as Kaon with Pion mass

Polarization Observable E: Comparison to Model Predictions (2.478 GeV Beam) ● Appears to show some level of agreement with SAID data. ● Higher cos  bins are more suspect due to high background contamination. ● For full asymmetry, P targ ~ 0.8, P el ~ 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