The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source - Design and Performance

TL;DR

The paper details the design and performance evaluation of the Cold Neutron Chopper Spectrometer at ORNL, demonstrating its capabilities in cold and thermal neutron scattering with high accuracy and potential as a key instrument for neutron research.

Contribution

It introduces a new spectrometer at ORNL with comparable performance to existing instruments and validates its performance through measurements and simulations.

Findings

Neutron flux and energy resolution match simulations within 20%.

The spectrometer performs excellently in cold and thermal neutron ranges.

It is suitable for quasielastic and inelastic neutron scattering experiments.

Abstract

The design and performance of the new Cold Neutron Chopper Spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct geometry inelastic time-of-flight spectrometer, designed to cover essentially the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM2, AMATERAS at J-PARC, PHAROS at LANSCE and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.