2021 Ernest Rutherford Medal and Prize

Professor Michael A Bentley for distinguished contribution to the understanding of fundamental symmetries in atomic nuclei and their relation to the underlying interaction between nucleons. 

Professor Michael A Bentley IOP Ernest Rutherford Medal and Prize winner 2021

Professor Michael A Bentley has made outstanding and sustained contributions to our understanding of fundamental symmetries in atomic nuclei and their relation to the underlying interactions between nucleons.

The atomic nucleus is a complicated many-body quantum object whose behaviour is governed by the interactions between individual nucleons. Despite this complexity, nuclei often exhibit collective behaviour and fundamental symmetries. Bentley has made seminal contributions to our understanding of both these paradigms of nuclear structure.

Early in his career, Bentley’s work established that nuclei are superdeformed (2:1 axis ratio) at high angular momentum through his lifetime measurements of excited states in 152Dy. This ground-breaking research had an enormous impact on many international research programmes and provided an important motivation for the development of large gamma-ray spectrometer arrays for nuclear structure experiments.

Bentley’s research has since focused on understanding the symmetries arising from the strong force that binds nucleons together. The theoretical foundation of nuclear physics incorporates the central tenet of a charge-symmetric nuclear force.

Charge symmetry should result in identical patterns of excited states in mirror nuclei – nuclei of the same mass where the number of neutrons and protons are exchanged. Investigations of these exotic nuclei, at the limit of nuclear existence, are challenging and require specialist techniques for their synthesis and measurement.

Bentley has made pioneering experimental investigations, in laboratories worldwide, of charge-symmetry breaking in nuclei through precise measurements of energy differences between excited states in mirror nuclei.

Bentley’s measurements have imposed crucial constraints on contemporary theoretical nuclear models such as large-scale shell-model calculations, indicating the presence of important charge-symmetry breaking effects. His work has refined the theories of very exotic nuclei, the study of which is the principal aim of radioactive beam facilities. Bentley is now the world-leading authority on charge-symmetry breaking.

Bentley’s research has been underpinned by his leadership in state-of-the-art technological developments. For over 30 years, Bentley has made significant contributions to developing detector technologies and has devised novel experimental techniques for next-generation radioactive beam facilities.

He leads the UK’s Science and Technology Facilities Council’s £5.3m contribution to the multinational Advanced GAmma Tracking Array (AGATA), and is the UK lead for the Lund-York-Cologne-CAlorimeter (LYCCA) spectrometer, a particle-tracking device to be used at the Facility for Antiproton and Ion Research, Germany. He recently coupled AGATA and LYCCA in order to study an exotic isobaric triplet, demonstrating the technical excellence needed to make scientific breakthroughs.