Serial Delay-Line Readout for Position Sensitive Neutron Beam Monitor

Abstract

The intensity of neutron beams is measured by neutron beam monitor detector at research reactors, in order to allow normalization of neutron scattering data. A two dimensional position sensitive neutron beam monitor has been developed, able to measure the distribution of beam intensity in its cross-section. The neutron adsorption efficiency of these monitor detectors are low enough to minimize the intensity loss, but high enough to provide low statistical error. Since the number of detected events is not too high, the dead time is not crucial for these detectors. A novel readout method has been developed that slightly increases the dead time but eventuates a robust, simple and flexible system. This new method relies on the serial connection of the delay-lines, minimizing the number of analogue signals. Two or three analogue signal outputs are enough to reconstruct the two-dimensional intensity matrix. Combining this new method with a comprehensive acquisition on the primary signals, the quality parameters of the detectors are also improved. Design and measurement results at the Budapest Research Reactor are presented.