E852 used a 12 inch long liquid hydrogen target with a diameter of 2.5 inch. The hydrogen was contained in a vessel constructed of a 0.0075 inch thick mylar cylinder with domed ends of 0.005 inch thick mylar. The vessel was wrapped in 40 layers of mylar superinsulation (of 0.010 inch total thickness) on the domes and 60 layers of mylar superinsulation on the cylinder (of 0.015 inch total thickness) all enclosed in a vacuum container made of aluminum. This container had cylindrical walls 0.083 inch thick, and outer diameter 4.5 inch and had domed downstream end of 0.025 inch aluminum. On the upstream far away from the target vessel (~13 ft) the vacuum container was sealed by a 0.0075 inch thick mylar window.
(The beam therefore was traversing in sequence the .0075 in. mylar window, the upstream superinsulation 0.010 in. mylar, the 0.005 in. upstream mylar hydrogen vessel dome, the 12 in. liquid hydrogen (3% interaction length), the 0.005 in. downstream mylar dome of the hydrogen vessel, the downstream superinsulation 0.010 in. mylar, and the 0.025 in. aluminum downstream vacuum container dome.)
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