A Pulsed Neutron Source for Thermal Reactor Physics

A compact 200 kV Cockcraft type pulsed neutron source was designed and constructed as a versatile tool for various pulsed neutron experiments in thermal reactor physics. Special care was taken to obtain the maximum peak intensity of pulsed neutrons against the average background neutrons induced from accelerator operation. To this end, two particular design features have been adopted. One is pulsing of the R-F ion source probe voltage combined with pulsing of the deflector voltage of the post accelerated D⁺ ion beam. The other feature is the use of a beam analyzing magnet to the accelerated beam. With these devices, a peak to background ratio of 10⁵ was obtained.

Pulsed neutrons of 14 MeV can be generated at pulse widths from 0.13 μs 500 ms, with a neutron yield of 3.7×10⁴–2×10⁹ n/pulse. The repetition rate of the pulses can be changed independently of the pulse width. An arrangement for long focusing beam adjustment provides for selection of the target position in a wide range.