The Checker Board Counter: A Semiconductor dE/dx Detector with Position Indication

As part of an extensive design study for a cyclotron project containing a few hundred semiconductor detectors of different types, we have developed a new version of the (dE/dx) detector as used in (dE/dx × E) telescopes. This checker board counter delivers, besides the ¿E signal, also information about the position of the incident particles. With this detector the angular distributions of charged reaction products can be measured with high angular accuracy in a large solid angle, while slit scattering is eliminated. The checker board counter is essentially a dE/dx detector, which is subdivided in a large number of sensitive fields. These are obtained by placing counter electrodes in the form of parallel strips on each side of the detector in such a way that the back and front side patterns are perpendicular to each other, together forming a rectangular coordinate system. In our case a checker board counter with 88 sensitive fields of 1.37 × 1.37 mm2 maintaining an angular accuracy of 1 degree with an 88-fold increase in solid angle was chosen. Some aspects of the electronic read-out system of the detector are given.