Paving the way for next-generation high magnetic field sample environments in neutron scattering

An in-depth technical partnership between the company HTS-110 (New Zealand) and the ILL resulted in the delivery of the world's first high-critical-temperature superconducting magnet for neutron scattering: a 12 tesla system delivered to the CEA for neutron science at the ILL (see image). The system is now installed on the two-axis diffractometer D23, as well as on several three-axis spectrometers and other diffractometers at the ILL.

Mirroring this successful collaboration model, HTS-110 has now been selected by the European Spallation Source (ESS) to design and manufacture a 14 tesla high-field magnet for neutron spectroscopy. As in the previous project, HTS-110 will be responsible for manufacturing the magnet system, while the Variable Temperature Insert (VTI) will be designed by the ILL team. This continuity allows the ESS to benefit from a proven interface between magnet and sample environment, leveraging HTS-110’s manufacturing capabilities alongside ILL’s 50 years of expertise in cryogenic systems.

The new system will be deployed on the CSPEC (Cold Chopper Spectrometer) and TREX (Bispectral Chopper Spectrometer) instruments at the ESS in Lund, Sweden, offering researchers a symmetric vertical field of up to 14 tesla combined with a variable temperature insert which will support normal operation from 1.5 K to 325 K, and allow the insertion and cooling of a dilution refrigerator and/or a ³He ultra-low temperature insert.

The chosen solution leverages the inherent thermal stability of High-Temperature Superconductors when compared to their conventional low-temperature counterparts. They provide superior current-carrying capacity in high magnetic fields, enhanced thermal stability, and a much lower risk of quench, making them ideal for demanding neutron scattering environments. Ensuring maximal detector coverage and low background interference, the 14 tesla system is designed to optimise data quality and detector efficiency in neutron science.

Moreover, the detector for CSPEC is being manufactured at the ILL, following an agreement signed in 2024. Similar to those of the ILL instruments IN5 and PANTHER but slightly bigger, this helium-3 detector will be made up of 12 multitube modules, plus a spare module, each comprising 32 tubes with a length of 3.5 m. Each module will be tested and manufactured at the ILL, delivered to the ESS by the end of 2027, and then filled with the detection gas before installation on the instrument. The agreement also includes the training of ESS staff.

As for the magnetic system, the design phase will start immediately, with final delivery of the system scheduled for 2027. This magnet will serve as a key component in unlocking discoveries in quantum materials, superconductivity, and functional materials at the atomic level.