Fully upgraded $\beta$-NMR setup at ISOLDE for high-precision high-field studies

TL;DR

This paper reports significant upgrades to the $eta$-NMR setup at CERN's ISOLDE, including a high-field superconducting magnet and digital data acquisition, enabling more precise measurements of short-lived nuclei and biological samples.

Contribution

The paper introduces a fully upgraded $eta$-NMR system with a 4.7 T superconducting magnet, improved detector array, and digital data system, enhancing measurement precision and expanding research capabilities.

Findings

Achieved sub-ppm magnetic field homogeneity and stability.

Recorded narrower linewidths and higher resolution in $eta$-NMR resonances.

Enabled more accurate bio-$eta$-NMR and studies of nuclear magnetization distribution.

Abstract

$\beta$-NMR is an advancing technique that enables measurements relevant to various fields of research, ranging from physics to chemistry and biology. Among the recent achievements of the $\beta$-NMR setup located at the ISOLDE facility at CERN is the determination of the magnetic moment of a shortlived nucleus with a part-per-million accuracy. Presented here are major upgrades and extensions of that $\beta$-NMR setup. The most important advancement is the installation of a 4.7 T superconducting solenoidal magnet, leading to sub-ppm spatial homogeneity and temporal stability of the magnetic field. A detector array optimised for such magnetic field has also been implemented and a more powerful, time-resolved, fully-digital data acquisition system has been deployed. To commission the upgraded beamline, $\beta$-NMR resonances of short-lived 26Na were recorded in solid and liquid samples. These showed 3-fold narrower linewidths and 15-fold higher resolving power than using the previous setup. Hence, the improvements achieved here permit more accurate bio-$\beta$-NMR studies, investigating, e.g., the interaction of metal ions with biomolecules, such as DNA. They also pave the way for the first studies of the distribution of the magnetisation inside short-lived nuclei.