The Yale Enge Splitpole Spectrograph Focal Plane Detector

Specifications

Description

The detector is a hybrid gas detector, backed by a plastic scintillator. The gas detector measures both the initial ionization and has regions run in the proportional mode. The position along the focal plane is determined in two planes by detecting the proportional cascade around two 50 micrometer wires, placed 10 cm apart, which run the length of the detector. These wires are surrounded by a segmented cathode whose segments are coupled to a delay line which runs the length of the wire. The proportional cascade induces an image charge on the segmented cathode, and by measuring the relative delay of the signal at both ends of the delay line we determine the track position. The delay line is made up of discrete delay line chips with a tap to tap delay of 5 ns. Particle identification is done by measuring the correlation between, the ionization signal in the gas detector verses plastic scintillator pulse height, the ionization signal verses position, and the plastic scintillator pulse height verses position.

Visit software for information on kinematics and detector simulation programs.

Incarnations of the Front Wire Assembly

Ken Swartz designed the Mark I, whose primary innovation over the previous assembly was its use of etched circuit board rather than copper rings for signal pickup. The aging problem was soundly defeated by the Mark I, but resolution was still not quite the optimal predicted. This was hypothesized to be due to the smaller surface area available for image charge pickup. Alan Chen, in consultation with Ken, then redesigned so that there were 2 circuit boards to pick up the charge, oriented along the sides of the wire rather than the top. We have dubbed this design Mark II. It was installed in the front wire position and an experiment performed [¹²C(¹⁶O,⁶He)²²Mg]. This new design has, in fact, given us the resolution we desire. A lengthened version of the Mark II for the rear wire position has been built and will be used in future runs.

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