Multi-Grid Detector for Neutron Spectroscopy: Results Obtained on Time-of-Flight Spectrometer CNCS

Abstract

The Multi-Grid detector technology has evolved from the proof-of-principle and characterisation stages. Here we report on the performance of the Multi-Grid detector, the MG.CNCS prototype, which has been installed and tested at the Cold Neutron Chopper Spectrometer, CNCS at SNS. This has allowed a side-by-side comparison to the performance of ${}^3$He detectors on an operational instrument. The demonstrator has an active area of 0.2 m${}^2$. It is specifically tailored to the specifications of CNCS. The detector was installed in June 2016 and has operated since then, collecting neutron scattering data in parallel to the He-3 detectors of CNCS. In this paper, we present a comprehensive analysis of this data, in particular on instrument energy resolution, rate capability, background and relative efficiency. Stability, gamma-ray and fast neutron sensitivity have also been investigated. The effect of scattering in the detector components has been measured and provides input to comparison for Monte Carlo simulations. All data is presented in comparison to that measured by the ${}^3$He detectors simultaneously, showing that all features recorded by one detector are also recorded by the other. The energy resolution matches closely. We find that the Multi-Grid is able to match the data collected by ${}^3$He, and see an indication of a considerable advantage in the count rate capability. Based on these results, we are confident that the Multi-Grid detector will be capable of producing high quality scientific data on chopper spectrometers utilising the unprecedented neutron flux of the ESS.

submitted to JINST

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• Simulation Tools for Detector and Instrument Design
• Performance tests of boron-coated straw detectors with thermal and cold neutron beams
• Software-based data acquisition and processing for neutron detectors at European Spallation Source - early experience from four detector designs
• Detector rates for the Small Angle Neutron Scattering instruments at the European Spallation Source
• Evidence of fast neutron sensitivity for 3He detectors and comparison with Boron-10 based neutron detectors
• Verification of He-3 proportional counters fast neutron sensitivity through a comparison with He-4 detectors
• Performance evaluation of the Boron Coated Straws detector with Geant4
• CSPEC: The cold chopper spectrometer of the European Spallation Source, a detailed overview prior to commissioning
• Suppression of intrinsic neutron background in the Multi-Grid detector
• Performance study of the Jalousie detector baseline design for the ESS thermal powder diffractometer HEIMDAL through GEANT4 simulations
• Time- and energy-resolved effects in the boron-10 based Multi-Grid and helium-3 based thermal neutron detectors
• Investigation of neutron scattering in the Multi-Blade detector with Geant4 simulations