Cherwell-Simon Memorial Lecture: The XENON Project: at the forefront of Dark Matter Direct Detection

What is the Dark Matter which makes 85% of the matter in the Universe? We have been asking this question for many decades and used a variety of experimental approaches to address it, with detectors on Earth and in space. Yet, the nature of Dark Matter remains a mystery. An answer to this fundamental question will likely come from ongoing and future searches with accelerators, indirect and direct detection. Detection of a Dark Matter signal in an ultra-low background terrestrial detector will provide the most direct evidence of its existence and will represent a ground-breaking discovery in physics and cosmology. Among the variety of dark matter detectors, liquid xenon time projection chambers have shown to be the most sensitive, thanks to a combination of very large target mass, ultra-low background and excellent signal-to-noise discrimination. Experiments based on this technology have led the field for the past decade. I will focus on the XENON project and its prospects to continue to be at the forefront of dark matter direct detection in the coming decade. Professor Elena Aprile is Professor of Physics at Columbia University in New York City. After obtaining her undergraduate degree in Physics in Naples, Italy, she earned her PhD at the University of Geneva, Switzerland. She started her research on noble liquid imaging detectors under the mentorship of Professor Carlo Rubbia, first as a student at CERN and later as postdoc at Harvard University. At Columbia, she pioneered the development of a Compton telescope for gamma-ray astrophysics based on a liquid xenon time projection chamber. She later turned her attention to the dark matter question proposing the XENON project for its direct detection using liquid xenon as target and detector medium. She founded the XENON Dark Matter Collaboration in 2002 and has served as its scientific spokesperson ever since; her international team includes more than 170 scientists and students representing 24 nationalities and 22 institutions. Aprile has been principal investigator on more than 20 research grants worth nearly $30 million over the last three decades and holds a patent for a vacuum ultraviolet light source. She has served on numerous panels and committees, for NASA, NSF, DOE, Fermilab, CNRS, ERC, etc. She is a Fellow of the American Physical Society since 2000. In 2017, she received an honorary degree from the University of Stockholm. She is the recipient of the 2019 AAS Lancelot Berkeley Prize.