A high resolution, fast neutron, time-of-flight spectrometer used for neutron energies between about several hundred kiloelectron volts and 30 .MeV is described. A 1 nsec neutron pulse occurring with a repetition rate of 20 kc is obtained with a novel "bunching deflection" system operating on the internal beam of the fixed energy Karlsruhe isochronous cyclotron. By the timing of the neutrons over a 57 m f1ight path aresolution of 0.025 nsec/ni at optimum was obtained. Detector counts are accumulated in a 2X8000 channel time analyzer system with 1 nsec channel width. A planned f1ight path of 180 m and an increase of the repetition rate from 20 kc at present to 200 kc is expected to provide further improvements of the spectrometer.

Measurements of the intensity distribution of microstructure beam pulses from an isochronous cycIotron are described. Typical intensity distributions resuIt in an increase ofthe chance coincidence rate of coincidence experiments by a factor of 2 over the ideal case of equally sized bursts. Among other factors stray frequencies in the rf may contribute to these intensity fluctuations. 151For a normalized intensity distribution h(l) the chance coincidences are given byh(l) = (j (I-I o ), N chO = clczI~.

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