The aluminum ring with an outer diameter of 45.0 in and wall thickness 2.0 in is necessary for a sturdy support structure and to permit machining of the outside surface to accommodate the flanges for fixed and sliding seals mounted on opposite sides of the ring that vacuum connect the chamber to each HRS. The height of the aluminum ring shown in figure 2.3.1.5 is 36.0 in, which is designed to accommodate the mounting flanges. The stainless steel base ring shown in figure 2.3.1.6 is 11.50 in in height with one pump-out 6 in diameter port and with seven 4 in viewing and electrical feed-through ports. The base ring will also contain support mechanisms for the solid target ladder assembly, a rotisserie for collimating slits, radiators, and magnetic fingers for removing the solid target vacuum-lock can. The total height of the top ring, middle ring, and base ring is 93.81 in. This length is partly determined by our desire to include with the cryogenic extended target a solid target vertical ladder secured in an inverted hat through a hole in the base of the chamber.
The base ring includes an end plate through which the inverted hat will be adapted to fit into the large vertical pipe serving as the pivot post for the Hall A spectrometers as shown in figure 2.3.1.6.
The stainless steel cylindrical top hat shown in Figure 2.3.1.7 has 40.0 in inner diameter, and is 0.375 in thick and 46.31 in high , which is necessary to permit the cryotarget to be withdrawn and to make space available to expose the solid targets to the electron beam.
The 200 A electron beam, presumably focussed to a mm spot and rastered 5 mm horizontally or vertically on the target, enters through a oval hole in the middle ring which is 2.06 in wide and exits through a 1.81 in hole connected to the exit pipe.