The foilhyphen;induced dissociation of molecular ions can provide a direct image of the stereochemical structures of small molecules. Such experiments require highhyphen;resolution measurements of the relative momenta of all dissociation fragments. In order to improve and extend previous studies of this type to a larger variety of molecules and clusters, we have developed a new type of lowhyphen;pressure multiwire proportional counter. The novel feature of this largehyphen;area (25times;50 cm2) multiparticle detector is that all the signals are recorded from a single twohyphen;level printed circuit board which serves as the anode. This segmented anode consists of three families of nonintersecting lsquo;lsquo;wiresrsquo;rsquo; which are interwoven on the rear surface of the board. By redundantly determining positions and arrival times, the new segmented anode multiparticle detector provides good time resolution (100ndash;200 ps) and high spatial resolution (0.2 mm) for detecting as many as six simultaneous particles.
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