Peter Butler is an experimental nuclear physicist who studies the phenomenon of reflection asymmetry in atomic nuclei and the structure of the heaviest elements. He presented compelling evidence that some nuclei have permanent octupole deformation (‘pear-shape’) from measurements of their rotational behaviour and electric charge distribution.
He conceived and led the development of instruments, sited at the Jyväskylä accelerator laboratory, to measure quantum transitions in heavy nuclei: the GREAT spectrometer that labels transitions in rare nuclei, and SACRED that measures atomic conversion electrons emitted by high-Z nuclei.
More recently he has been spokesperson of several CERN experiments to successfully characterise nuclear shapes using beams of radioactive nuclei, such as the pear-shaped radium-224. During his tenure as CERN-ISOLDE group leader he initiated the HIE-ISOLDE project for accelerating radionuclides. He was spokesperson and chair of the ISOLDE collaboration and chaired committees giving advice on experimental programmes at Jyväskylä, Oak Ridge and CERN, and GANIL’s future programme. In 2012, he was awarded the Rutherford Medal of the Institute of Physics for his contributions to experimental nuclear physics.
Professor of Physics, Department of Physics, University of Liverpool