High-intensity and versatile chopper spectrometer project for J-PARC

Abstract

We have proposed a versatile inelastic neutron spectrometer (VINS) for the spallation neutron source at the Materials and Life Science Facility, Japan Proton Accelerator Research Complex. This is a direct- geometry Fermi chopper spectrometer, aimed at realizing a very high neutron flux with reasonable energy and Q resolutions. A wide energy-transfer range of 0.5 < E < 1000 meV will be covered with two energy-resolution modes, ΔE/E_i ∼ 5 and 2.5%. Q range will also be considerably large as up to 40 Å⁻¹ at E_i = 1000 meV, enabled by an array of detectors covering −30 < 2θ < 130° (2.8 Sr). Preliminary Monte Carlo simulation predicts the maximum flux of 10⁶ neutrons/cm²/s at the sample position for E_i = 10 meV (assuming that the neutron source is running at 1 MW). With the remarkably high neutron flux, VINS will be a unique tool for various types of condensed matter research, in particular, those which have never been explored by inelastic neutron scattering due to sample size restriction.