A Novel "Deflection-Bunching" System at the Karlsruhe Isochronous Cyclotron Used with a Neutron Tmie-of-Flight-Spectrometer

A system consisting of two coupled electrostatic deflectors and the associated electronics is described. The principle of the system is shown in fig. 1: One deflector which is located near the center of the machine is used for a two-fold purpose a) to eliminate two out of three microstructure pulses by deflection to a beam stop and b) to form ion bunches of 4,5 usec duration each consisting of fifty microstructure pulses. A second pair of deflector plates is located at a mean radius of 39 inches and serves to simultaneously deflect the set of microstructure pulses to a target positioned above the median plane of the cyclotron. At the time of deflection, the bunch is distributed over 4 inches in radius. Using this method neutron pulses of 1 ± 0,3 nsec duration with a repetition rate of 20 kc/sec can be produced. A neutron time-of-flight spectrometer has been put in operation using this "deflection-bunching" system.