Ohio University Qweak Status Report: 08/26/2004

Done several simulations for primary collimator study (no collimator shift, shift collimator up 1 cm, shift it up 2 cm, open it 2 cm wider along radial direction). In each simulation, 100k elastic electrons were triggered, and the second collimator was taken out, the phi range =+/-11 degree which is determined by the primary collimator. Only primary eleastic electrons were tracked. The event rate is for events hitting the Cerenkov bar at Z=530 cm, and centering at X=310 cm. The size of the Cerenkov bar is 200 x 16 cm. The results are listed in the table.



Primary collimator	Rate (MHz)	Q2_mean (GeV^2)	Theta_mean (degree)	FOM (FOM=R*Q^4)
no shift	626.1	0.0268	8.044	0.4497
up 1 cm	538.6	0.0295	8.450	0.4687
up 2 cm	443.7	0.0325	8.874	0.4687
2 cm wider	694.2	0.0284	8.262	0.5599



1. Q^2 profile at Z= 530 cm for current primary collimator (no shift)



2. Theta profile at Z= -280 cm for current primary collimator (no shift)



3. Q^2 profile at Z= 530 cm for primary collimator (up 1 cm)



4. Theta profile at Z= -280 cm for primary collimator (up 1 cm)



5. Q^2 profile at Z= 530 cm for primary collimator (up 2 cm)



6. Theta profile at Z= -280 cm for primary collimator (up 2 cm)



7. Q^2 profile at Z= 530 cm for primary collimator (2 cm wider)



8. Theta profile at Z= -280 cm for primary collimator (2 cm wider)