Large straw-tube tracking chambers for AGS experiment E864

We have built two very large planar straw tube detectors with 4 mm diameter tubes for AGS experiment E864. This is a Au+Pb collision experiment at 11.5 AGeV/c, designed to search for strangelets and other novel forms of matter. A central collision trigger requires tracking chambers to operate in a high multiplicity environment, with as many as 200 hits per event in the first data run, which represented an occupancy of 20%. Each detector consists of three planes of tubes, a vertical X plane as well as stereo U and V planes. Each plane has two close-packed layers of tubes. One detector is 40 cmx200 cm and contains 3x960 tubes, and the other is 80 cmx400 cm and has 3x1920 tubes. The function of the detector is to achieve high mass resolution in tracking charged particles, and it has been successfully used during three data runs at the AGS