Commissioning of Neutron Scattering Instrumentation

Monday Jul 7, 2025, 3:30 PM → 6:00 PM Europe/Stockholm

This symposium focuses on the techniques, tools and approaches to pass a neutron scattering instrument from construction to the usage state. With the ESS shortly having several instruments in commissioning, the SNS just having put instruments through this process and planning its second target station here we aim to collect the knowledge associated with that process.

During operation the characterisation of the scattered neutrons in an neutron instrument depends on a number of parameters which first have to be reliably established at startup, among those the relation between timestamping and wavelength profile, absolute incoming intensity, spatial setup of the detector and background.

Here we will adress each of those issues in a section of the mini symposium:

• Measurements of Incident Beam
• Round Robin and Standard Samples
• Background and Detectors
• Comparison between Simulation and Experiment

 

In this symposium we target to collect expertise and nurture discussion about 

• the current methods and approach
• issues and challenges with those
• and hopefully a way forward

 

Interested participants are therefore cordially invited to join the mini symposium and join the discussion about methods, challenges and approaches during commissioning of a neutron scattering instrument for scientific use.

Measurements of Incident Beam

1 Methods used for neutron beam characterization at ISIS

Speaker: Robert Bewley (STFC UKRI)

Round Robin and Standard Samples

2 Reproducibility and Reliability - the role of reference samples

The aim of a neutron measurement on a sample is usually to obtain information about some material
object that can be used to understand structure or properties. The end-information about a sample
needs to be reliable. Differences in measured data can arise from instrumental effects such as finite
resolution, and the range of wavelengths exploited, the momentum and energy transfer that are
accessible. As a scientific tool, it is important to understand these differences. Commissioning of a
new instrument will require an evaluation of these effects rather than just a verification that raw
data are similar. In this respect, samples that test different aspects are important: these will verify
calibration of intensity and momentum transfer but also need to test resolution, stability, and
background from the sample and the instrument. The talk will illustrate this largely with examples drawn from small-angle scattering.

Speaker: Adrian Rennie (Uppsala University)

Background and Detectors

3 Instrument backgrounds – Why does it matter? : Most brightest – not most blinded.

In the development of neutron scattering instruments, the primary focus is often on maximizing signal intensity, while managing instrument background tends to receive comparatively less attention. This imbalance is not necessarily due to a lack of awareness of the importance of background reduction but rather reflects the historical reality that mitigating instrument noise has been more of an art than a science. While substantial tribal knowledge exists in this area, there is no standardized methodology or formula for optimizing instrument backgrounds.
In this presentation, we will share several illustrative examples from the Lujan Center at the Los Alamos Neutron Science Center (LANSCE), Los Alamos National Laboratory. These examples will highlight both signal-to-noise challenges and strategies. Additionally, results from beamline source term verification experiments will be presented to further explore the complexities of background characterization and control.

Speaker: Günter Muhrer (European Spallation Source ERIC)

4 Recent progress and applications of high resolution MCP neutron counting detectors with Timepix readouts

Detectors using neutron-sensitive Microchannel Plates (MCPs) with Timepix readouts have found niche applications in pulsed neutron sources, where the arrival position of each neutron and its energy are reconstructed with high accuracy. These detectors can localize each neutron with approximately 10 µm spatial resolution and very high timing precision—around 500 ns for thermal neutrons and 10 ns for epithermal neutrons. The detection efficiency of these devices for thermal and cold neutrons is approximately 50%.
In these detectors, neutrons are directly converted into a charge of approximately 10⁵ electrons, all confined within a ~10 µm pore, with no afterpulsing or readout noise. The Timepix readout ASIC is positioned directly beneath the MCP in vacuum, enabling pixelated detection of numerous simultaneous events, thereby significantly increasing the count rate capability to GHz levels.
This talk will review the current state of this detection technology, which is primarily used for energy-resolved neutron imaging at this time, and will present experimental results across various applications, including residual strain mapping, texture analysis, in-situ crystal growth optimization, annealing, and time-resolved imaging of dynamic processes. Additionally, we will discuss upcoming advancements enabled by the latest generation of Timepix4 readouts, highlighting how MCP/Timepix detectors offer a compelling solution for applications requiring neutron counting with high spatial and temporal resolution.

Speaker: Anton Tremsin (University of California at Berkeley)

Comparison between Simulation and Measurement

5 From McStas instrument design to commissioning tool: Preparing for operating the ESS instruments

The McStas instrument simulation tool has been widely used for designing and optimising the ESS instrument suite. This contribution will outline how the ESS DMSC makes use of McStas for preparation of the data pipeline and transitioning from “as designed” to “as built” models. We will further outline lesser-known features in McStas and related projects to aid beamline staff in the commissioning process.

Speaker: Peter Willendrup (DTU Physics)