Russina, M.; Mezei, F.: First implementation of Repetition Rate Multiplication in neutron spectroscopy. Nuclear Instruments & Methods in Physics Research A 604 (2009), p. 624-631
10.1016/j.nima.2009.03.010
Abstract:
The conventional way in time-of-flight (TOF) neutron spectroscopy is to use neutron pulses of one monochromatic wavelength. Repetition Rate Multiplication implies using a set of several monochromatic wavelengths coming from one source pulse, instead of a single one. This makes possible to overcome a major efficiency draw back of practical pulsed neutrons sources, the too low pulse repetition rate for TOF spectroscopy and allow us to freely choose the pulse repetition rate at the sample. Here we present the first experimental realization of this novel technique using the flexible disc chopper system of the TOF spectrometer NEAT at BENSC and report about the first real life data collection by Repetition Rate Multiplication. The first choppers of the instrument emulated a pulsed source with 20 – 40 Hz repetition rate with the sample at 13.5 m, and the secondary spectrometer was operated with about 160 Hz chopper pulse frequency. The spectra have been detected by 3He counters placed at 2.5 meter from the sample. Several RRM frames with different incoming wavelengths have been recorded coming from each “source” chopper pulse. The results show that information from different RRM frames can be efficiently combined and evaluated. This offers more efficient use of the pulsed source by cutting the data collection dead time, and allows for faster and enhanced quality data collection by using several monochromatic wavelengths in parallel.