A time-of-flight neutron spin echo spectrometer

Abstract

At present a new high-resolution neutron spin echo spectrometer, IN15, installed at the horizontal Cold Source of the HFR reactor at the Institut Laue-Langevin (ILL) in Grenoble, is tested with neutrons, being in its static mode. For a time-of-flight (TOF) operation of the spectrometer the velocity selector for the static mode will be replaced by an arrangement of four choppers, producing neutron pulses of variable time width [1]. Neutron tests for the TOF mode will start early in 1991. As can be seen from eq. (1), even for a relatively small wavelength band, )tmax/Ami n between 2 and 3, a large dynamic range is covered. Another aspect of this TOF mode is generally to gain experience for pulsed neutron sources. A broad time width ~of the pulses in the TOF mode corresponds to the broad incident wavelength band AA/A in static spin echo spectroscopy, which can be used because of the decoupling to energy resolution. This means a higher echo signal.