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           Beamline Design

The preliminary beamline design consists of the "right" size beamline in each region and then for regions upstream of QTOR, the maximum sheilding with a single thickness of lead in that region. Figure 1 shows the entire beamline as it is currently defined. The regions are:

          sewer pipe
          GEM
          Minitorus
          Region II
          QTOR
          downstream of QTOR

For now we have adopted the two plug solution as our favorite. We believe that it is desireable to have at least one plug to try to keep the entire region upstream of QTOR from being irradiated, but two plugs allow us to have the desired angular range for the downstream luminosity monitors. The plugs are embedded in the upstream and downstream cleanup collimators (See Figures 3 and 4).

Figure 1 - Picture of the entire beamline.	Figure 2 - Zoom in on region with the tungsten plugs.
Figure 3 - Upstream tungsten plug, embedded in the upstream cleanup collimator.	Figure 4 - Downstream tungsten plug, partially embedded in the downstream cleanup collimator.

There are obvious flaws in this design, because there are actually openings for particles with p_z < 0 to get out of the beampipe (See Figure 1 or 2). That and other issues will eventually have to be addressed. However, there were several problems with the geometry definition, and now I am very carefully checking to make sure that the geometry and materials are defined correctly.

The elements and their lengths and inner and outer radii are listed in Table 1 below. Maybe Greg or someone could double-check the aluminum beampipe thicknesses and lengths.

When I am satisfied that the materials and geometry definitions are correct, I will calculate a baseline for the photon rates. I will then try to add and remove shielding to see if the photon rates (specifically at Region II, but also at GEM and cerenkov bar locations) can be improved. Finally, a full photon rate study will be performed to get the total rates at the 3 locations with the new collimators and beamline and sheilding in place.

Region	Component	Material	R_i (cm)	R_o (cm)	Length (cm)
target	sewer pipe	Aluminum	29.5275	30.48	49.09
upstream cleanup	Plug 1	Tungsten	1.246	4.0	7.0
GEM	BEA1	Aluminum	2.80543	3.0163	44.41
GEM	BES1	Lead	3.0163	5.2388	44.41
minitorus	BEA2	Aluminum	5.50418	5.715	171.281
minitorus	BES2	Lead	5.715	7.62	171.281
Region II	BEA3	Aluminum	10.26668	10.4775	102.1
Region II	BES3	Lead	10.4775	18.0975	102.1
dowmstream cleanup	Plug 2	Tungsten	5.95	14.55	7.0
QTOR	BEA4	Aluminum	13.0175	13.97	436.619
QTOR	BES4	Lead	13.97	wedges?	436.619
downstream of QTOR	BEA5	Aluminum	29.5275	30.48	515
downstream of QTOR	BES5	Lead	30.48	34.29	515

Table 1 - List of components and volume information.

           Drift Chamber Update

The machine shop is 90% finished with the frames for the next Region II chamber.

Norm and Juliette have begun stretching the cathode planes and the gas windows. Figure 5 shows one of them reflecting a Virginia Tech Qweak poster.

We plan to start stringing the sense planes within the next couple of weeks. Figure 6 shows a sense plane frame with the wire scanner and camera/monitor setup that we will use to measure the wire positions. The wires will be positioned in the corners of the grooves that are magnified in the monitors view. A drawing of the card layout is taped to the frame - you can see it on the right side of the monitor view.

Figure 5 - One of the cathode planes reflecting a Qweak poster.	Figure 6 - The wire scanner setup with a sense plane.