BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:ASP Online Seminars: Africa’s Window to the Extreme Universe: Th e H.E.S.S. Telescopes and the Mystery of Cosmic Rays DTSTART:20260616T130000Z DTEND:20260616T143000Z DTSTAMP:20261009T105200Z UID:indico-event-1673697@indico.cern.ch CONTACT:ASP-IOC@cern.ch\;denauroi@in2p3.fr\;mounia.laassiri@cern.com\;moun ia.laassiri@gmail.com DESCRIPTION:Speakers: Mathieu JACOBE DE NAUROIS (Laboratoire Leprince Ring uet IN2P3/CNRS - Ecole Polytechnique)\n\nAbstract:\nThe Earth is constant ly bombarded by extremely high-energy particles from the far reaches of th e cosmos\, known as cosmic rays. Discovered in 1912 by Victor Hess\, these particles—which can be electrons\, protons\, atomic nuclei\, or even an tiparticles—may carry energy as high as that of a bullet\, all concentra ted in a single particle. Their impact on our daily lives is often overloo ked: they contribute to irradiation during air travel\, random mutations i n our DNA\, the production of Carbon-14 in the atmosphere\, and even disru ptions in electromagnetic communications.\nMany cosmic phenomena appear ca pable of accelerating these particles\, both within our Galaxy and in the distant Universe. These phenomena are linked to some of the most violent e vents in the cosmos: the collapse and explosion of massive stars (supernov ae)\, the disappearance of matter into supermassive black holes\, and myst erious objects such as “pulsars”\, “magnetars”\, “microquasars ”\, or “blazars”.\nThe H.E.S.S. (High Energy Stereoscopic System) te lescope array\, operating in Namibia since 2003\, hunts these cosmic accel erators by detecting the very high-energy gamma rays they emit. These tele scopes work in a unique way: they capture the extremely brief and faint li ght produced in the upper atmosphere when a gamma photon interacts with ox ygen or nitrogen\, triggering a cascade of secondary particles. In this pr ocess\, the telescopes record thousands of images per second.\nIn this sem inar\, I will introduce the cosmic ray puzzle\, explain how the H.E.S.S. t elescopes operate\, and recount 20 years of tracking down the astrophysica l sources of cosmic rays. I will conclude by presenting the projects plann ed for the coming decades.\nBio of the speaker:\nProf. Mathieu de Naurois is a CNRS Senior Research Director and Professor at École Polytechnique\, specializing in very high-energy gamma-ray astronomy. This cutting-edge f ield uses large\, ultra-fast telescopes to detect the faint and fleeting C herenkov light emitted in the atmosphere by particle cascades—triggered when a very high-energy gamma ray interacts with an atmospheric nucleus.\n His work has focused on the launch and operation of the H.E.S.S. array of Atmospheric Cherenkov Telescopes in Namibia\, a project run by an internat ional collaboration of nearly 200 researchers. He has contributed to the d iscovery and interpretation of gamma-ray emissions from various celestial objects\, including binary star systems\, starburst galaxies\, and superno va remnants. From 2016 to 2019\, he led the H.E.S.S. collaboration and cur rently serves as its Deputy Director. He is also a member of the Cherenkov Telescope Array Observatory (CTAO)\, the next-generation gamma-ray observ atory under construction\, set to succeed H.E.S.S. in 2028. He currently h olds the position of Vice-Chair of the CTAO Council\, the observatory’s primary governing body.\nIn 2017\, Mathieu de Naurois was awarded the CNRS Silver Medal for his outstanding contributions to gamma-ray astronomy.\n\ nhttps://indico.cern.ch/event/1673697/ URL:https://indico.cern.ch/event/1673697/ END:VEVENT END:VCALENDAR