1. Mark Sikora, Dan Watts, Derek Glazier
Recoil Polarimetry
Mark Sikora, Dan Watts, Derek Glazier
Outline:
Motivation
Technique
Experimental setup
Previous data
Initial data from current run
Future work

2. Motivation
Nucleon substructure – accessed by measuring resonance spectrum
Constituent quark models, lattice QCD, holographic dual QCD predict different resonances, more constraints needed
Meson photoproduction off the nucleon is essential
Recoil polarization is necessary for a complete measurement

3. Motivation
16 polarization observables: dσ/dΩ, 3 single pol. observables, 12 double pol. observables

4. Technique

5. Experimental Setup p γ2 γ1 2.5 cm thick graphite cylinder
Reconstruct π0 from γ’s γ1

6. Event Selection Look for events with 3 hits
Missing mass cut for pion and proton
Look for coincidence between PID hits and reconstructed proton φ angle

7. Results from test beamtimes (2x3 day runs)
D(1232) resonance
D(1232) resonance
second resonance
region
seco resonance
region
γ+p→p+π0

8. Initial proton asymmetry

9. Comparison to MAID Cx
Ebeam

10. Current beam time (VERY preliminary)

11. Initial proton asymmetry

12. Work to be done Model analyzing power
Kinematic fitting of vertex position?
η channel
Neutron polarimetry