We are deeply saddened to learn of the death of Stefano Mazzoni. Stefano left an indelible mark at CERN, where he worked within the Beam Instrumentation group. From his arrival on 1 September 2012, as a physicist specialising in optics and lasers, Stefano quickly distinguished himself through his exceptional expertise and dedication.
Over the years, he became much more than just a colleague. Stefano was a leader, an inspiring personality and one of the pillars of the group’s research programme. His contributions to the High-Luminosity LHC and AWAKE plasma acceleration projects, as well as the CLIC and FCC studies on future electron and positron colliders, are testament to his deep commitment and excellence.
Stefano specialised in developing innovative systems to measure the ultra-small, down to micron-scale beam sizes. As early as 2012, freshly arrived at CERN, he invested himself in an experiment programme that was starting up at Cornell University’s electron and positron storage ring, on the shores of Cayuga Lake in New York State. This was the starting point for a body of research that continues to this day, work that has spanned oceans, from the United States to Japan, via accelerators in Spain, in the United Kingdom and at CERN.
His journey and work remind us that the path of research is a long voyage, filled with excitement and frustration, breakthroughs and setbacks. A voyage sustained by the dedication and relentless efforts of individuals like Stefano, who are both humble and brilliant.
Beyond his scientific skills, Stefano was above all an exceptional human being: warm, kind and empathetic. He had the ability to recognise when people were facing difficulties or going through tough times, and he approached these situations constructively and with understanding. His radiant personality and collaborative spirit allowed him to forge deep and sincere bonds with colleagues from around the world. His international renown was the result of not only his work, but also the positive and lasting impact he had on those around him. We think here of the students, PhD students and postdocs, researchers and colleagues who had the chance to work closely with Stefano. All the messages we have received are filled with sadness and support, but also with conviction and unwavering hope.
In his daily life, Stefano was full of enthusiasm and energy. He loved music and sports with a passion. We will always remember his smile when he reached the top of a mountain. We will remember the tracks he left behind in the powder snow. We will remember his elegant and swift stride that traversed the world on his travels. Every year, he participated enthusiastically in the famous CERN relay race with his team, “the Bellissimi”. Stefano also knew how to appreciate the simple pleasures in life. We remember the plate of sushi shared in San Francisco last June, and the last pizza enjoyed with colleagues a few weeks ago at Luigia, after our weekly group meeting.
Above all, Stefano cherished his family, his wife and children, of whom he was immensely proud.
Stefano’s absence leaves a vast void for his family, friends, colleagues at CERN and far beyond. He will forever remain in our hearts and memories, and his legacy will continue to inspire us and, through us, future generations.
Thank you, Stefano, goodbye dear friend. It was a pleasure and a privilege to share these moments with you.
His friends and colleagues
We deeply regret to announce the death of Stefano Mazzoni on 13 April 2025.
Mr Stefano Mazzoni, born on 30 May 1978, worked in the SY department and had been at CERN since 1 September 2012.
The Director-General has sent a message of condolence to his family on behalf of the CERN staff.
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