Overview
UKAEA’s Tritium Fuel Cycle division has applied its specialist tritium expertise to a new field: cosmology. In a commercial contract with Laboratori Nazionali del Gran Sasso, (LNGS) in Italy, UKAEA collaborated with research teams from Sapienza University of Rome, Roma Tre University and LNGS. The aim was to assess the feasibility of preparing graphene targets loaded with tritium atoms to detect cosmic neutrino background – relic particles from the big bang.
The project identified the UKAEA-Eni H3AT Tritium Loop Facility as the ideal host site. It examined the technical and regulatory challenges of integrating the PTOLEMY (Pontecorvo Observatory for Light-universe, Massive-neutrino Yield) experiment’s design and explored how to safely transport samples to Italy. The work demonstrates how UKAEA’s fusion-driven tritium capabilities can support cutting-edge fundamental physics research beyond energy applications.
Key highlights
- UKAEA’s tritium expertise, developed for fusion energy, was successfully applied to a new field. Supporting efforts to detect cosmic neutrino background, demonstrating the wider value of UKAEA’s capabilities.
- The project identified the UKAEA-Eni H3AT Tritium Loop Facility as the most suitable host site for the PTOLEMY experiment. This was a concrete, practical outcome of the feasibility study.
- The project addressed complex technical and regulatory challenges. These included tritium compatibility and the safe transport of samples under vacuum from the UK to Italy, showcasing UKAEA’s specialist knowledge.
- The results were well received and UKAEA’s feedback will shape the next iteration of the PTOLEMY design. In addinsights gained have informed UKAEA’s own exploitation plan for the facility.
Background
The PTOLEMY collaboration aims to detect cosmic neutrino background, using tritiated graphene samples. The particles have existed since around one second after the big bang and generate a detectable electric current when they interact with the graphene target. Relic neutrinos are extremely faint and difficult to detect but doing so gives a unique snapshot of the early universe.
Handling tritium safely requires specialist facilities and expertise that the PTOLEMY team does not have in-house. UKAEA’s Tritium Fuel Cycle division was a natural partner to explore whether its facilities, including the UKAEA-Eni H3AT Tritium Loop Facility, could support the project.
The challenge
The project needed to identify a suitable host facility and a study of UKAEA’s sites was undertaken. The site needed to accommodate the PTOLEMY design and integrate an external experimental system into an existing tritium facility. This included analysing the tritium-loading concept design, central to producing PTOLEMY’s graphene target, which needed to be stable and hold tritium at a precise atomic scale.
The team also had to ensure tritium compatibility for individual components and the system as a whole. Mechanical, process and vacuum design considerations were assessed, since adapting an experiment originally designed for hydrogen into a tritium environment involves significant engineering changes. Navigating the regulatory landscape, particularly around transporting tritium samples under vacuum from the UK to Italy, added further complexity. Lastly, there was the need to bridge the knowledge gap between PTOLEMY researchers and UKAEA’s facility team.
The solution
UKAEA addressed these challenges through a structured feasibility study beginning with an optioneering assessment of their facilities. This identified the UKAEA-Eni H3AT Tritium Loop Facility as the most suitable host site, followed by analysis of the tritium-loading concept to assess how the PTOLEMY design could be integrated.
The team investigated tritium compatibility and evaluated the feasibility of the mechanical, process and vacuum design required to adapt a hydrogen-based experiment for use in a tritium environment. This engineering work underpins the highly specialised physics equipment PTOLEMY relies on elsewhere in the experiment, from ultra-sensitive electron detectors to precision voltage systems all of which depend on a safe and stable tritium environment.
Alongside this, the team reviewed regulatory requirements for transporting samples under vacuum from the UK to Italy. Technical discussions with PTOLEMY researchers clarified the design changes needed when porting a hydrogen experiment into a tritium facility. The discussions led to insights that were shared with UKAEA’s facility team to support a wider exploitation plan.
Applications and impact
The most direct application of this work is in fundamental physics research, supporting PTOLEMY’s goal of detecting cosmic neutrino background using tritiated graphene samples. The project also demonstrates broader applications for UKAEA’s tritium expertise, opening potential new markets and partnerships for UKAEA’s tritium facilities.
Outcomes
The study identified the UKAEA–Eni H3AT facility as the most suitable host site. It produced findings on tritium compatibility, mechanical, process and vacuum design feasibility, and regulatory considerations for transporting samples under vacuum. It also generated valuable insight into the requirements of prospective tritium users. The results were well received by PTOLEMY researchers, and UKAEA’s feedback will directly inform the next iteration of the design.
Looking ahead
UKAEA’s feedback will shape the next iteration of the PTOLEMY design, with further refinement expected. Insights gained about prospective tritium users have been incorporated into an exploitation plan for the facility team. This supports UKAEA’s ambition to attract and assist similar external users of its tritium facilities in the future.
Find out more about the PTOLEMY project.
UKAEA’s tritium facilities and expertise are available to support researchers and industry partners. We are open to exploring new applications for tritium, from fusion energy to fundamental physics and beyond. If your organisation is considering how tritium technology could support your research, get in touch with UKAEA’s Tritium Fuel Cycle division to discuss how we can help.