Date: Mon, 07 Jul 2003 16:44:48 -0500
From: Terry Tope 

Doug - Attached is a drawing of the expansion volume BTeV plans to use for the test beam. Their actual vessel is 2200 ft^2, so they plan to have 10 of these on it. Basically its just 4 ft. diameter ventilation hose that expands and contracts guided by four rods. The hose end is glued to thin metal sheet. The hose was a problem because it was stitched around the metal support wire so a grad student was lucky enough to fill all the holes. But they have not tried it on an actual system. - Terry pdf version of the following image.