Introduction

• Joseph O'Neill (University of Birmingham)

Neutron measurements for the characterisation of NILE, a facility based on compact neutron generators

• Carlo Cazzaniga (STFC)

Two table-top neutron generators producing 14 MeV and 2.5 MeV neutrons have been installed at the Neutron Irradiation Laboratory for Electronics (NILE) of the Rutherford Appleton Laboratory. The neutron fields are generated through deuterium–tritium (DT) and deuterium–deuterium (DD) fusion reactions, respectively. Monte Carlo simulations supported the design and optimisation of the facility. This work presents the characterisation and dosimetry of the radiation fields using a range of complementary measurement techniques. Activation foils provide standard passive measurements of neutron fluence, while active detectors, including fission chambers, are primarily used for online beam monitoring. Diamond detectors are used for high-resolution neutron spectroscopy, and scintillation detectors provide both neutron monitoring and spectrometric measurements, with the additional capability of neutron–gamma discrimination. SRAM based detectors are deployed as a reference for the irradiation of electronics applications.

High-Flux Accelerator Driven Neutron Facility (HF-ADNeF)

• Jack Bishop (University of Birmingham)

The High-Flux Accelerator Driven Neutron Facility (HF-ADNeF) is a user facility located at the University of Birmingham providing ~$10^{11}$ n/s/cm$^{2}$ via the $^{7}$Li$(p,n)$ reaction, giving neutrons up to an energy of 0.9 MeV. Due to the thick target approach, this energy spectrum is broad energy. The current capabilities of the facility and some use cases will be highlighted as well as a brief discussion of future development plans. These include moving to a deuteron beam which will boost the maximum neutron energy up to $\approx$ 18 MeV to bring the neutron energies into the DT fusion regime. Details available at: https://www.birmingham.ac.uk/about/college-of-engineering-and-physical-sciences/physics-and-astronomy/facilities/high-flux-accelerator-driven-neutron-facility

First Underground Characterisation of a Deuterated Liquid Scintillator for Low-Energy Neutron Measurements in Nuclear Astrophysics.

• Rhys Bonnell

Direct measurements of astrophysical nuclear reactions require the detection of extremely low event rates and therefore benefit greatly from the ultra-low-background conditions available in deep underground laboratories. For neutron-producing reactions, sensitivity can be further limited by the lack of neutron-energy information provided by many conventional high-efficiency detectors, complicating the discrimination of signal neutrons from environmental or target-induced backgrounds. In the study of the 10B(a,n)13N using irradiation-resistant 10B enriched boron carbide (10B4C) targets, 13C within the target material introduces a competing, 13C(α,n)16O neutron source. Because traditional high-efficiency detectors such as 3He counters lack energy resolution [1], they cannot distinguish neutrons originating from a primary reaction from those produced by target contaminants or environmental backgrounds. This limitation necessitates the use of scintillator detectors with spectroscopic capabilities, which allow for the determination of neutron energies to confidently isolate the reaction of interest. As part of the ERC NUCLEAR programme [2], we are investigating the 10B(a,n)13N reaction. Using EJ-301D deuterated liquid scintillators [3]. Unlike conventional proton-based scintillators, which yield a featureless recoil continuum, deuterated scintillators produce a characteristic, peaked pulse-height response due to neutron-deuteron scattering [4]. This distinct structure allows the incident neutron energy spectrum to be reliably reconstructed through spectrum unfolding, utilizing the detector response matrix and the Maximum Likelihood Error Minimization (MLEM) [5] approach. Crucially, this capability eliminates the need for Time-of-Flight (ToF) techniques, offering a significant advantage for continuous-beam experiments or compact laboratory setups where long flight paths are unfeasible. This talk will present the first characterization of these deuterated scintillators in an underground setting. I will report on preliminary measurements conducted at the Laboratori Nazionali del Gran Sasso (LNGS) within the Laboratory for Underground Nuclear Astrophysics (LUNA) facility [6]. Finally, I will demonstrate the strategic advantages of using EJ-301D detectors to measure the 10B(a,n)13N reaction in the presence of events from natural/ambient background and/or target contaminants. [1] Csedreki, L., Ciani, G. F., Balibrea-Correa, J., et al. (2021). Characterization of the LUNA neutron detector array for the measurement of the 13C(α, n)16O reaction. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 994, 165081. https://doi.org/10.1016/j.nima.2021.165081 [2] https://www.erc-nuclear.uk [3] Becchetti, F. D., Raymond, R. S., Torres-Isea, R. O., Di Fulvio, A., Clarke, S. D., Pozzi, S. A., & Febbraro, M. (2016). Deuterated-xylene (xylene-d10; EJ301D): A new, improved deuterated liquid scintillator for neutron energy measurements without time-of-flight. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 820, 112–120. https://doi.org/10.1016/j.nima.2016.02.058 [4] Febbraro, M., Lawrence, C. C., Zhu, H., Pierson, B., Torres-Isea, R. O., Becchetti, F. D., Kolata, J. J., & Riggins, J. (2015). Deuterated scintillators and their application to neutron spectroscopy. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 784, 184–188. https://doi.org/10.1016/j.nima.2014.10.072 [5] Pehlivanovic, B., Avdic, S., Marinkovic, P., Pozzi, S. A., & Flaska, M. (2013). Comparison of unfolding approaches for monoenergetic and continuous fast-neutron energy spectra. Radiation Measurements, 49, 109–114. https://doi.org/10.1016/j.radmeas.2012.12.008 [6] https://luna.lngs.infn.it/index.php/new-about-us

Challenges in the Calibration, Operation, Quality Control and Reliability of a Processing Facility Active Neutron Generator Assay System for Intermediate Level Waste

• James Doherty (Nuclear Restoration Services)

Nuclear Restoration Services (NRS) operates the Dounreay site in the north of Scotland, which was built in 1955 as the centre of fast reactor research in the United Kingdom. Today, our challenge is to decommission and remediate the site, including our research reactor, our two fast reactors, our fuel cycle area, and our legacy underground waste stores which are no longer suitable for that purpose. Our Remote-Handled Intermediate Level Waste (RHILW) processing facility uses a Passive/Active Neutron Interrogation System to determine the total mass of Plutonium and Uranium in variously sized cans. The system dates back to the 1980s; our lifetime plan and waste management strategies have identified the need for this measurement capability for several decades to come. The neutron interrogation source for the RHILW Active Assay system was upgraded from a Californium Shuffler to a SODERN MEN 16NG Neutron Generator in 2021. Neutrons are detected using coincidence counting by an array of 16 He3 detector tubes which surround the measurement chamber. During refurbishment a design study was carried out by the upgrade manufacturer using MCNP modelling techniques to optimise the design of cans, waste matrices and to produce Active and Passive calibrations for each type of waste matrix. For both Passive and Active assay, 4 calibrations were developed using MCNP dependent on the Hydrogen density of the waste matrix. Passive calibrations have performed well throughout the working life of the system since November 2022, however, a downward drift was observed in year-on-year calibration check measurements and in the daily active QC measurement. To prevent the system failing its active QC check and allow the site to continue to process RHILW, in May 2025 the Radiometrics Team at Dounreay developed new Active calibration curves based on empirical measurements made using four new certified Uranium standards, which we produced for the task using existing material, with U235eff mass ranging between 1g and 20g. In the event the calibration continues to drift due to deterioration of neutron generator output, NRS Dounreay has gained the internal ability to use these standards for system recalibration without the need for MCNP modelling. In 2026, NRS Dounreay engaged a supply chain partner to undertake a technical and strategic review into the issues faced with the current configuration of the system and make recommendations for the future. On that basis, we are now considering a new configuration for fast neutron detection using Am-Li interrogation sources and a fast neutron collar of scintillator detectors. We have approximately 5 years to reach sufficient technical and operational readiness for this transformation, due to the lifetime of the neutron generator in the current configuration.

Neutron detection work in the Applied Radiation Technology group at UKAEA

• Gemma Wilson (UKAEA)

The Applied Radiation Technology group at UKAEA specialises in neutron and gamma measurements, benchmark experiments in for materials undergoing neutron irradiation and in neutronics simulations and analysis for current and future fusion facilities. This talk will discuss the current research in the group relating to neutrons, and work towards the upcoming LIthium BReeding Tritium Innovation (LIBRTI) facility. The specific needs for neutron detectors within a fusion environment and for fusion-related research will also be discussed.

Development of a Complete Neutron Diagnostics System for the Lithium Breeding Tritium Innovation (LIBRTI) Programme

• Gee Bartram (UKAEA)

For the upcoming Lithium Breeding Tritium Innovation (LIBRTI) facility at UKAEA, a D-T neutron generator will be utilised. This source will be surrounded by breeder blanket material to produce tritium, where one of the aims is to determine the tritium breeding ratio (TBR). Monitoring the neutron flux and neutron energies provided by the source is essential for measuring the tritium consumed. To prepare for the operation of the LIBRTI facility in the coming years, a neutron diagnostics system capable of measuring the both the neutron flux and neutron energies emitted by the D-T generator is currently being designed. In this presentation, the proposed design is discussed. The D-T source is cooled using water, which is then transported outside the target through pipework. By measuring the activation products within the source cooling water, a measurement of neutron flux can be achieved that is not impeded by the presence of the breeder blanket. The proposed method is to measure gamma rays following the beta decay of 16N and beta-delayed neutron emission from 17N using scintillators. By selecting a scintillator with strong pulse shape discrimination (PSD) capabilities for the desired energies, signals from gamma rays and neutrons can be separated, with both signals providing a value of neutron flux. This is the first use of PSD for this application in the fusion sector. Furthermore, traditional neutron monitoring techniques such as the use of fission chambers and activation foils around the source will be utilised and discussed.

MultiGrid detectors for T-REX at ESS

• Ken Livingston (University of Glasgow)

MultiGrid (MG) technology has been developed as alternative to 3He for neutron detection - partly due to the increasing cost and availability of Helium, and partly to access the high rates anticipated at new facilities like ESS (European Spallation Source). MG was first developed over 10 years ago, and has been used in several tests, but the T-REX bispectral chopper spectrometer will be the first large scale detector to be fully instrumented with MultiGrid. The T-REX MG detector is currently being constructed in Lund, Sweden, and will be installed ready for initial beam tests at ESS on 2027. This talk presents the design, development and construction of the MultiGrid detector.

Towards establishing a high-energy d-Li neutron production capability at HF-ADNeF

• John Murphy (University of Birmingham)

The University of Birmingham’s High-Flux Accelerator-Driven Neutron Facility (HF-ADNeF) currently operates using the *p*−7Li reaction to produce intense, fast neutron beams for experimental studies. However, the accelerator could accelerate deuterons onto the lithium target instead, enabling neutron production up to energies of 17 MeV, covering the D-T fusion neutron spectrum peak at 14.1 MeV. Such a high-flux neutron field would be of considerable interest for detector benchmarking, neutron damage assessment, high-energy reaction studies and cross-section data validation. The aim of the project is to realise a well-defined, high-energy neutron beam, enabling a range of future experimental nuclear science investigations at HF-ADNeF. This contribution will present the motivation, strategy, and current progress towards establishing the *d*−Li operating mode, with a focus on the modelling of the neutron spectrum and experimental validation approaches.

Enabling Better Science: Recent Scintillator and Micro-Pattern Gas Detector Developments at ISIS

• Giacomo Mauri (STFC - ISIS)

ISIS is the UK neutron and muon spallation source with a suite of over thirty specialised instruments. It is a world-leading facility for research in a vast range of scientific fields, from physics and chemistry to biology and engineering. All neutron instruments employ either scintillator-based or gaseous-based detectors. These have been under development at ISIS for more than three decades. Continuous research and development aim to improve detector capabilities, achieve better performance and meet the increasingly demanding requirements set by neutron scattering instruments. At ISIS, there is a portfolio of instrument projects aimed at transforming its scientific capabilities: The Endeavour Programme. This includes four cutting-edge instruments and five major upgrades over the next decade, ensuring that ISIS remains a global leader in neutron science. Key challenges in detector development include achieving large area coverage, optimizing spatial resolution, and ensuring high counting rate capability. This work presents a general overview of the latest development of scintillator-based and micro-pattern gas neutron detectors performed at ISIS. Novel designs of ZnS:Ag/6LiF coupled to wavelength shifting fibre (WLSF) and lithiated glass detectors will be described. The performance and results, using these detectors, will be shown for various neutron scattering applications. Improvements in detection efficiency, position resolution and count rate capability will be presented. Moreover, future development routes will be highlighted. µRWELL is one of the latest Micro-Pattern Gaseous Detector (MPGD) technologies developed at CERN. At ISIS, we are investigating the use of these detectors in combination with a 3He-based gas mixture as a potential solution for future upgrades of spectroscopy, SANS, and neutron imaging instruments. The latest achievements with µRWELLs will be presented here. Enhancements in performance, together with continued research on these detector technologies, will further extend the capabilities of the science programme, paving the way for future instrument upgrades at ISIS.

Neutron Detection R&D for Nuclear Threat Reduction

• Matthew Taggart
• Kerri Loughney

TBC

NPL Activities in Neutron-Induced Cross Section Measurements

• Giuseppe Lorusso

TBC

Prompt-gamma dosimetry for BNCT at HF-ADNeF

• Max Conroy (University of Birmingham)

Boron neutron capture therapy (BNCT) is a promising form of cancer treatment whereby a boron-loaded pharmaceutical is administered to a patient and, upon irradiation with a neutron beam, the products from the resulting neutron-induced reaction damage and destroy the cancer. One particular area of BNCT that requires development is dosimetry. In this work, a scintillator-based gamma detection system has been designed and simulated using OpenMC, to be placed inside the HF-ADNeF target room. By detecting prompt-gamma rays emitted when neutrons interact with a phantom, dosimetry and even imaging can be performed. This is not a simple task, due to the significant neutron and gamma flux present in the room, which this work focusses on overcoming.

Simulation and confirmation of an ²⁴¹Am-⁹Be neutron source with Geant4 and flux measurements using CLLBC

• Filippo Falezza (The University of Birmingham)

Among commercially available neutron sources, the ²⁴¹Am-⁹Be proves to be useful in both industrial, education and research environments because of its constant neutron flux and longer working life compared to other alternatives. An accurate simulation tool of this source would allow a better understanding of the neutron energy spectrum and flux. The ⁹Be(α,n)¹²C reaction of interest is not isotropic. However, Geant4 nuclear libraries can only handle isotropic reactions, and for this reason a new source term has been developed. This talk will focus on accurately reproducing the emerging neutron and γ spectra. The simulation will be experimentally verified against commonly accepted results; it is then employed in a cylindrical water bath to analyse neutron moderation and flux in water and eventually dose from emerging particles is investigated.

The NeuAMS proposal for combined accelerator mass spectrometry & neutronics

• Stewart Freeman (University of Glasgow)

TBC

Neutron detection and imaging for security applications

• David Sharp

Radiation detection is an established component of nuclear-security systems used at borders, ports, critical infrastructure and major public events. Passive radiation portal monitors screen vehicles, cargo and people while portable monitors, backpack systems, personal radiation detectors and handheld radionuclide identification devices support searches, alarm investigation and secondary inspection. In typical security applications, neutron detection complements gamma-ray measurement because it provides an important indication of the possible presence of special nuclear material. Scintillators remain the detector technology of choice within the security industry for radiation detection owing to their versatility, robustness and cost. This presentation will review current and emerging scintillator technology in the context of neutron detection for security applications. This will include established pulse processing techniques that enable NaI(Tl) detectors already deployed in radionuclide identification devices to detect fast neutrons and thermal neutrons. Novel polyurethane-based organic scintillators will also be presented. These offer simultaneous fast-neutron and gamma-ray detection, pulse-shape discrimination, fast response and direct coupling with silicon photomultipliers that could enable use in future radionuclide detection products. Beyond passive detection, neutrons could also provide complementary imaging information to established x-ray-based techniques where dense or highly attenuating cargo limits X-ray penetration, or where improved sensitivity to organic and hydrogen-rich materials is required. This talk will highlight areas of interest for neutron imaging were this technique able to make the jump from facility-based measurements to deployable real-world systems.

New facility for Neutron Metrology at NPL

• Michael Bunce (National Physical Laboratory)

Michael Bunce1, David Thomas1, Graeme Taylor1, Neil Roberts1, Andrew Bennett1, Sarb Cheema1, Kimberly Ward1, Daniel Smith1, Nicola Horwood1 and Ed O’Sullivan1 1Nuclear Metrology Group, National Physical Laboratory, UK By definition a neutron detector will detect neutrons. However, the amount of information that can be derived from a detected event depends on what is known about the characteristics of the instrument. Information on the number of neutrons detected depends on knowledge of the efficiency of the device and this requires standard fields for calibration. For spectrometers monoenergetic fields provide facilities for deriving detector response functions. Radiation protection devices require dose standards. The National Physical Laboratory has provided industry and academia with fluence, energy, and dose standard neutron fields for characterising neutron detecting instruments since the 1960’s. Sectors such as civil nuclear power, defence, radiation-protection and fusion generation rely on NPLs facilities to innovate, operate safely and ensure traceability back to an internationally recognised UK primary standard. A central part of the capability was the 3.5 MV Van de Graaff accelerator which has been retired after over 60 years of operation. A new 2 MV Tandetron has been installed, which will use light ions to generates monoenergetic fields of neutrons ranging from a few keV to 20 MeV and intense thermal fields. This presentation will outline the neutron capabilities of the Nuclear Metrology Group at NPL and the details of the new accelerator.

Developments in Portable Neutron Measurement and Radiometric Analysis Capabilities at Sellafield

• Henry Watkinson (Sellafield Ltd)

Characterisation of fissile material inventories in legacy nuclear facilities remains a significant challenge for successful decommissioning. To do so effectively requires portable neutron techniques, which face several difficulties – constrained access, complex geometries, elevated dose rates that interfere with neutron measurements, and often a need for rapid operational decision-making. Over the past year, several neutron detection developments have been undertaken at Sellafield to address these obstacles and improve the capability of portable neutron assay in active plant environments. Central to this work has been the production of a localisation and quantification method of fissile material based on an array of in-situ measurements with Arktis S670 fast neutron detectors called FINDER. The data are combined with computational optimisation approaches to infer source position and strength from the measured distributions. The solution is obtained using detector response matrices generated in the Monte Carlo N-Particle (MCNP) package, followed by a novel adaptive clustering method that groups similarly detectable source terms. This acts as a dimensionality reduction step, producing a stable and physically plausible initialisation for the Maximum Likelihood Expectation Maximisation (MLEM) solve. The methodology enables localisation in complex geometries while simultaneously providing estimates of fissile material inventory and has been designed to deliver robust, physically realistic solutions in challenging measurement environments. The effectiveness of the approach has been evaluated using representative deployment scenarios and is currently undergoing benchmarking prior to use in nuclear facilities. Alongside this development, a Kromek TN-15 deployment package has been engineered with the supply chain to facilitate operation in high-dose environments, enabling thermal neutron measurements within channels beneath legacy storage tanks. This package is an alternative neutron measurement technique for carrying out material localisation and quantification activities and has been deployed successfully. In parallel, an Arktis total neutron counting system is being developed to coarsely quantify fissile material in waste packages for clearance against acceptance criteria, facilitating appropriate disposal. This presentation will describe the technologies, benchmarking, methods, deployment challenges, and applications that have been explored over the past two years. It is expected that these capabilities will shortly transition from development to deployment to support hazard reduction and waste management across Sellafield.