Talk at Sustainable HEP 2026.

Designing the next generation of materials for rare-event searches: high-strength, ultra-pure copper alloys

More information can be found here.

Description

The quest to directly detect dark matter and unravel the nature of neutrinos has driven the development of experimental techniques with unprecedented sensitivity, placing extreme demands on detector-material-induced backgrounds. As a result, the choice of construction materials, particularly those in direct contact with the target medium, has become a critical limiting factor. Electroformed copper, thanks to its exceptional radiopurity, is the material of choice for low-background experiments. However, its limited mechanical strength and ductility restrict its application for large-scale, high-pressure, or load-bearing components.

To overcome these limitations, a materials design approach is proposed. The combination of electrodeposition techniques with CALPHAD-based modelling enables rapid predictive design of alloy compositions and thermal processing, allowing the navigation of the complex parameter space of radiopurity, mechanical strength, and manufacturability. The recent advances in the synthesis and design optimisation of high-strength, radiopure copper-based alloys will be presented and the physics impact will be illustrated through case studies.

Energy savings and efficient use of materials are at the centre of this project; for example, the proposed materials design approach accelerates the R&D phase and reduces the required direct experimentation cycles. This results in less energy and materials usage during development. The obtained optimised thermal processing parameters result in reduced thermal treatment temperatures and duration, leading to materials with the desired properties at lower energy and material cost. Furthermore, mechanically enhanced materials lead to reduced required thickness of specific structures. These developments, initially motivated by fundamental research, could also prove important to other applications, such as electronics, transport, metal purification for upcycling and clean energy technologies.

References

[1] NEWS-G Collaboration “Copper electroplating for background suppression in the NEWS-G experiment”, Nucl. Instrum. Meth. A, 988 (2021): 164844

[2] NEWS-G Collaboration “Exploring light dark matter with the DarkSPHERE spherical proportional counter electroformed underground at the Boulby Underground Laboratory”, Phys. Rev. D 108, (2023): 112006

[3] Vitale A. et al. “A preliminary investigation into the electrodeposition and synthesis of radiopure Copper–Chromium alloys for rare-event physics detector systems”, Nucl. Instrum. Meth. A, 1003 (2021): 165291

[4] Spathara, D., “Design of high-strength, radiopure copper–chromium alloys for rare-event searches assisted by computational thermodynamics”, Nuclear Inst. and Methods in Physics Research, A, 1082 (2026): 170970

[5] Spathara, D., et al. “Materials design for the synthesis of high strength radiopure copper alloys for rare event detection”, Commun Phys 8 (2025): 464