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Active Target

The role of the active target is to monitor the lateral stopping distributions. The active target consists of 69 plastic scintillator fibers surrounded by 8 guard-ring elements of the same material. The entire active target is a cylinder of diameter and long as shown in figure gif. However, each of the 69 fibers has a square cross section of and is covered with an acrylic cladding of thick for optical isolation. The fibers are then glued together with epoxy to make the active target.

Figure: The active target used during the test run of 1994 to measure the horizontal and vertical beam profiles. It contains 69 plastic scintillator fibers with 8 guard-ring elements of the same material around them. Each fiber is isolated by an acrylic cladding and they are held together with epoxy.

Each fiber is connected to a one-inch photomultiplier tube via a fiber optic light guide.

The stopping distributions are needed for an accurate Monte Carlo simulation of the experiment and acceptance corrections for pion beta and decays.

Bernward Krause
Mon Jan 15 14:57:06 MET 1996