Done several simulations to study whether adding the shielding in front of the Cerenkov
bar can reduce the inelastic electron background with Neven's unsculpted collimator.

1. Firstly, check the electron envelop of elastic (red) and inelastic (blue) electrons
at Z=330, 380, and 430 cm (without the shielding) to determine the shape and
position of the opening of the shielding. The electrons shown in the figure
also hit the Bar (302< x <320 cm, -105< y <105 cm) at Z=530 cm. There is an
energy cut (energy > 1000 MeV) for elastic electrons.





2. Side view of the Qweak spectrometer with the shielding. The shielding is a 70 cm
thick concrete wall located at Z = 330-400 cm, with a conical tube shape opening.





3. Upstream view of the Qweak spectrometer with the shielding





4. Table of inelastic/elastic ratio w/o shielding. It seems adding the shielding can
not reduce the inelastic electron background, as some inelastic electrons may
hit the inner surfaces of the window of the shielding wall, then scatter
to the bar.



Shielding	Elastic Rate (MHz)	Inelastic Rate (MHz)	Inelastic/Elastic (%)	Q2_mean (GeV^2)	FOM (FOM=R*Q^4)
No	777	0.54	0.069	0.02375	0.438
Yes	779	1.36	0.175	0.02371	0.438