2020 Medal Winners | francais

The 2020 CAP Medal for Lifetime Achievement in Physics

is awarded to

Eric Hessels

"I am very honoured to receive this award. I would like to acknowledge the hard work and intelligence of my students and collaborators, as the work being honoured here would not have been possible without them." winner citation

The Canadian Association of Physicists (CAP) is pleased to announce that the 2020 CAP Medal for Lifetime Achievement in Physics is awarded to Eric Hessels, York University, for his world leadership in advancing the state of the art for high precision atomic physics measurements, and their significance as tests of fundamental physics. announcement

Eric Hessels has been a leader in the field of precision measurement in physics for over 30 years. His specialty has been ultrahigh-precision measurements of transition energies in atoms and molecules, with a goal to understanding fundamental physics. Most recently, his group made the most precise measurement ever of a fine structure energy interval of helium, which will help to enable a more accurate determination of a fundamental constant of nature that governs the strength of electromagnetic interactions and correspondingly test the physics present in this two-electron atom. His group recently made the most precise measurement of a subtle shift in an energy level of hydrogen caused by the interaction of the electron with the proton. This enabled a measurement of the radius of the proton, helping to resolve a long-standing controversy known as the Proton Radius Puzzle and consequently verifying standard physics. Dr. Hessels has completed many other ultrahigh-precision measurements of simple atoms over the past three decades. Additionally, he has been a pioneer in research into antimatter, and was a key member of the ATRAP collaboration that successfully produced and trapped atoms of anti-hydrogen.

One of Dr. Hessels' strengths is the development of innovative methodologies, such as a dual charge exchange methods used for producing anti-hydrogen, and the frequency-offset separated-oscillatory-fields (FOSOF) technique that led to the proton radius measurement. He is an expert on the modelling of systematic errors affecting precision measurements.

Recently, Dr. Hessels has been leading an effort to measure the distribution of charge in the electron. The measurement has the potential to test physics at higher energies than are accessible at current or planned particle colliders, essentially on a table top. This measurement will be pivotal to understanding why there is such a huge imbalance between matter and antimatter in our universe. nominator citation

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