Time-resolved neutron imaging at ANTARES cold neutron beamline

TL;DR

This paper demonstrates the use of time-resolved neutron imaging at the ANTARES beamline to study dynamic processes with high temporal and spatial resolution, enabling detailed analysis of water distribution in a model steam engine.

Contribution

The study showcases the capabilities of time-resolved neutron radiography using a fast detector and TOF technique at ANTARES, enabling dynamic imaging of processes like water flow in engines.

Findings

Successful imaging of water distribution within a steam engine at 10 Hz.

Achieved sub-mm spatial resolution with less than 10 minutes of integration.

Measured neutron spectrum and transmission spectra with high energy resolution.

Abstract

In non-destructive evaluation with X-rays light elements embedded in dense, heavy (or high-Z) matrices show little contrast and their structural details can hardly be revealed. Neutron radiography, on the other hand, provides a solution for those cases, in particular for hydrogenous materials, owing to the large neutron scattering cross section of hydrogen and uncorrelated dependency of neutron cross section on the atomic number. The majority of neutron imaging experiments at the present time is conducted with static objects mainly due to the limited flux intensity of neutron beamline facilities and sometimes due to the limitations of the detectors. However, some applications require the studies of dynamic phenomena and can now be conducted at several high intensity beamlines such as the recently rebuilt ANTARES beam line at the FRM-II reactor. In this paper we demonstrate the capabilities of time resolved imaging for repetitive processes, where different phases of the process can be imaged simultaneously and integrated over multiple cycles. A fast MCP/Timepix neutron counting detector was used to image the water distribution within a model steam engine operating at 10 Hz frequency. Within <10 minutes integration the amount of water was measured as a function of cycle time with a sub-mm spatial resolution, thereby demonstrating the capabilities of time-resolved neutron radiography for the future applications. The neutron spectrum of the ANTARES beamline as well as transmission spectra of a Fe sample were also measured with the Time Of Flight (TOF) technique in combination with a high resolution beam chopper. The energy resolution of our setup was found to be ~0.8% at 5 meV and ~1.7% at 25 meV.