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, 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