I was fascinated by the research field of one of my professors, Guy Demortier. He was working on the characterization of antique jewelry. He had found a way to differentiate by PIXE (Proton Induced X-ray Emission) analysis between antique and modern brazes that contained Cadmium, the presence of this element in antique jewelry being controversial at the time. He was interested in ancient soldering methods in general, and the granulation technique in particular. He studied them at the Laboratoire d'Analyses par Réaction Nucléaires (LARN). Brazing is an assembly operation involving the fusion of a filler metal (e.g. copper- or silver-based) without melting the base metal. This phenomenon allows a liquid metal to penetrate first by capillary action and then by diffusion at the interface of the metals to be joined, making the junction permanent after solidification. Among the jewels of antiquity, we find brazes made with incredible precision, the ancient techniques are fascinating.

In fact, this was one of Namur's fields of research at the time: heritage sciences. Professor Demortier was conducting studies on a variety of jewels, but those made by the Etruscans using the so-called granulation technique, which first appeared in Eturia in the 8th century BC, are particularly incredible. It consists of depositing hundreds of tiny gold granules, up to two-tenths of a millimeter in diameter, on the surface to be decorated, and then soldering them onto the jewel without altering its fineness. So I also trained in brazing techniques and physical metallurgy.

I applied for a position as a physicist at CERN in the field of vacuum and thin films, but was invited for the position of head of the vacuum brazing department. This department is very important for CERN as it studies methods for assembling particularly delicate and precise parts for accelerators. It also manufactures prototypes and often one-off parts. Broadly speaking, vacuum brazing is the same technique as the one we study at Namur, except that it is carried out in a vacuum chamber. This means no oxidation, perfect wetting of the brazing alloys on the parts to be assembled, and very precise temperature control to obtain very precise assemblies (we're talking microns!). I'd never heard of vacuum brazing, but my experience of Etruscan brazing, metallurgy and my background in applied physics as taught at Namur were of particular interest to the selection committee. They hired me right away!

CERN is primarily known for hosting particle accelerators, including the famous LHC (Large Hadron Collider), a 27 km circumference accelerator buried some 100 m underground, which accelerates particles to 99.9999991% of the speed of light! CERN's research focuses on technology and innovation in many fields: nuclear physics, cosmic rays and cloud formation, antimatter research, the search for rare phenomena (such as the Higgs boson) and a contribution to neutrino research. It is also the birthplace of the World Wide Web (WWW). There are also projects in healthcare, medicine and partnerships with industry.

For my part, in addition to developing vacuum brazing methods, a field in which I've worked for over 20 years, I've worked a lot in parallel for the CLOUD experiment. For over 10 years, and until recently, I was its Technical Coordinator. CLOUD is a small but fascinating experiment at CERN which studies cloud formation and uses a particle beam to reproduce atomic bombardment in the laboratory in the manner of galactic radiation in our atmosphere. Using an ultra-clean 26 m³ cloud chamber, precise gas injection systems, electric fields, UV light systems and multiple detectors, we reproduce and study the Earth's atmosphere to understand whether galactic rays can indeed influence climate. This experiment calls on various fields of applied physics, and my background at UNamur has helped me once again.

I was also responsible for CERN's MACHINA project -Movable Accelerator for Cultural Heritage In situ Non-destructive Analysis - carried out in collaboration with the Istituto Nazionale di Fisica Nucleare (INFN), Florence section - Italy. Together, we have created the first portable proton accelerator for in-situ, non-destructive analysis in heritage science. MACHINA is soon to be used at the OPD (Opificio delle Pietre Dure), one of the oldest and most prestigious art restoration centers, also in Florence. The accelerator is also destined to travel to other museums or restoration centers.

ELISA uses the same accelerator cavity as MACHINA. The public can observe a proton beam extracted just a few centimetres from their eyes. Demonstrations are organized to show various physical phenomena, such as light production in gases or beam deflection with dipoles or quadrupoles, for example. The PIXE analysis method is also presented. ELISA is also a high-performance accelerator that we use for research projects in the field of heritage and others such as thin films, which are used extensively at CERN. The special feature is that the scientists who come to work with us do so in front of the public!

I remember that in 1989, I finished typing my report for my IRSIA fellowship in the middle of the night, the day before the deadline. It had to be in by midnight the next day. There were very few computers back then, so I typed my report at the last minute on one of the secretaries' Macs. One false move and pow! all my data was gone - big panic! The next day, the secretary helped me restore my file, we printed out the document and I dropped it straight into the mailbox in Brussels, where I arrived after 11pm, in extremis, because at midnight, someone had come to close the mailbox. Fortunately, technology has come a long way since then...

The proximity between teaching and research inspires and questions. This enables graduate students to move into multiple areas of working life.

Come and study in Namur!

Serge Mathot (May 2025) - Interview by Karin Derochette

• The CERN accelerators complex
• The Science Portal, CERN's public education and communication center
• Newsroom - June 2025 | The Departement of physics hosts a delegation from CERN
• Newsroom and Omalius Alumni article - September 2022 | François Briard

In the photo: Édouard Lecanuet, production assistant at Histovery, Minister Valérie Lescrenier in charge of Tourism and Heritage, Marc de Villenfagne, managing director of the Citadelle of Dinant, and Axel Tixhon, professor in the History Department at UNamur, inaugurate the HistoPad, a 3D reconstruction tool of the history of the Citadelle of Dinant. A project scientifically validated by Axel Tixhon.

Thanks to an interactive tablet christened HistoPad, the public can explore the site like never before. At various points along the route, visitors discover historical scenes recreated in 3D, supported by rigorous documentation and faithful reproductions of period settings, costumes and objects.

Three key periods have been selected for this immersion:

• 1821, Dutch period and construction of the fort
• 1832, Belgian period during which the Citadelle becomes a military prison
• 1914, during the First World War, the site is the scene of confrontations

Professor Tixhon was involved in all stages of the project, as a member of the scientific committee. Initially, he highlighted historically interesting events and traces still visible today, such as artillery pieces, an old kitchen or a bakery. It also provided Histovery with relevant and reliable documentation.

His expertise has made it possible to assess the historical accuracy of the reconstructions.

Some locations have also been virtually recreated from ancient iconographic sources, such as an ingenious wooden mechanism that once carried water from the Meuse to the fortress.

Histovery, already known for its achievements at the Château de Chambord, the Palais de papes in Avignon and Fort Alamo in the USA, here signs a Walloon first, blending heritage, innovation and scientific rigor. A success that demonstrates, once again, the relevance of dialogue between experts at the University of Namur and socio-economic and cultural players.

In the picture, from left to right: (top) Pierre Louette, Director of the Physics Department; François Briard, Head of the Science Portal Group (CERN); Julien Colaux, IBA specialist, physics researcher; Boris Hespeels, biology researcher; Alexandre Mayer, physics researcher; Anne-Catherine Heuskin, physics and biophysics researcher. (bottom) André Füzfa, astrophysicist and mathematics researcher; Serge Mathot, Applied Physicist (CERN) and Michaël Lobet, physics researcher.

The love affair between CERN and UNamur goes back a long way. CERN's accelerator complex and experimental program are very different and much larger than those of UNamur's Physics Department, but the fields in which the two institutions work have much in common.

In addition, both guests have a personal history with UNamur. The Physics Department was pleased to welcome Serge Mathot, Referent Applied Physicist (CERN) and alumni of the UNamur Physics Department (1992), as well as François Briard, Group Leader Science Portal (CERN), and alumni of the UNamur Faculty of Computer Science (1994).

The activities began with a meeting between the guests, Rector Annick Castiaux, Vice-Rector for Research Carine Michiels, Physics Department Director Pierre Louette and several other members of the Physics and Biology Department. After a general presentation of the University, the participants pointed out the missions shared by both institutions: research and the transfer of technology and knowledge, service to society, scientific popularization and education and training.

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Physics lunch - CERN presentation

The physics lunch is the monthly meeting between students and members of the physics department and a professional, alumni or not, coming to explain his or her background and what he or she does on a daily basis as a physicist.

During this meeting, attended by around 80 people, François Briard and Serge Mathot presented CERN, the world's largest laboratory for particle physics. CERN's mission is to understand the most elementary particles and the laws of our universe.

At the end of the seminar, the students came away with stars in their eyes. Indeed, opportunities for internships or even first jobs at CERN are possible for physicists but also in many other fields.

Some internship programs at CERN are particularly well suited to the needs of young Belgian students.

The vast majority of physicists working with CERN (over 13,000) are in fact sent to CERN for varying periods of time by their employing national research institutes. CERN offers an exceptional opportunity to develop international experience under excellent conditions, in an environment that is unique in the world! What an inspiration for our young students!

The projet d'Action Recherche Concertée (ARC) PHOENIX aims to renew our understanding of medieval parchments and ancient coins. Artificial intelligence will be exploited to analyze the data generated by material characterization.

This joint study between the Department of Physics and the Namur Institute of Structured Matter (NISM) and the Department of History and the Institut Patrimoines, Transmissions, Héritages (PaTHs) will address questions relating to the production chain and use of these objects and materials in past societies.

At the same time, Serge Mathot presented a seminar in heritage science attended by some 50 people. In particular, he presented his research and the brand-new ELISA accelerator: a miniaturized gas pedal capable of delivering a 2 MeV proton beam used to perform real measurements at the Science Portal.

Having the opportunity to exchange views with François Briard, Group Leader of the CERN Science Portal is a rare opportunity. Comparing outreach activities has opened up new avenues, discovering and sharing approaches, assessing what works and what doesn't, depending on the target audience. A highly satisfying enrichment for the members present from Confluent des Savoirs (CDS), the University of Namur's research outreach and dissemination service.

Professor Anne-Catherine Heuskin and Dr. Boris Hespeels are currently working on the BEBLOB project, a Belspo project with ESA support, as part of the UNIVERSEH (European Space University for Earth and Humanity) alliance. They are particularly interested in its astonishing ability to withstand high doses of radiation.

Anne-Catherine Heuskin also works in radiobiology. Particles are used to irradiate cancerous cells in order to destroy their genetic material and prevent them from proliferating: this is the basis of radiotherapy and proton therapy.

The meeting confirmed the willingness of FaSEF and UNamur to get involved in coordinating the Belgian National Teacher Programme in French-speaking Belgium, which CERN intends to relaunch in 2026. Consideration was also given to other avenues for teacher training, such as CERN's forthcoming involvement in the "Salle des Pros", the training venue for the various players involved in teacher training at UNamur.

The TRAKK is Namur's creative hub supported by 3 complementary partners in the field: BEP, KIKK, and UNamur. In addition to the venue, François Briard was able to visit the ProtoLab , which bridges the gap between ideas and industry by being a decentralized research and development hub accessible to SMEs and project leaders by offering advanced support in prototyping products or services.

Graduating in law and information technology management (DGTIC) in 1994 after his bachelor's and master's degrees in computer science in 1993, François Briard works at CERN, the European Organization for Nuclear Research in Geneva, the world's largest particle physics laboratory.

During his school career, which was 100% at UNamur, he was vice-president of the Régionale namuroise and student delegate during his years as a candidate in economic and social sciences, computer science option.

Thanks to the multidisciplinary training provided at UNamur, he was able to seize several opportunities to redirect his career at CERN, where he was an information systems engineer from 1994 and then, from 2014, redirected his career until he became Group Leader of the Science Portal, which is CERN's general public communications center.

Serge Mathot obtained his doctorate in applied sciences from UNamur in 1992, following his bachelor's degree in physical sciences in 1985.

He then carried out a post-doctorate at the Joint Research Center (EU science hub) in Geel, which aims to bring together multidisciplinary skills to develop new measurement methods and tools such as reference materials.

He perfected his expertise in physical metallurgy before joining CERN in 1995 as a Referent Applied Physicist. He has worked on numerous research projects (CLOUD, MACHINA, ELISA...) and developed numerous parts for the manufacture of CERN's gas pedals.

CERN, the European Organization for Nuclear Research, is one of the world's largest and most prestigious scientific laboratories. Its vocation is fundamental physics, the discovery of the constituents and laws of the Universe. It uses highly complex scientific instruments to probe the ultimate constituents of matter: the fundamental particles. By studying what happens when these particles collide, physicists understand the laws of Nature.

The instruments used at CERN are particle gas pedals and detectors. Gas pedals carry beams of particles at high energies to collide with other beams or fixed targets. Detectors observe and record the results of these collisions.

Founded in 1954, CERN is located on either side of the French-Swiss border, near Geneva. It was one of the first organizations on a European scale and today has 25 member states, including Belgium.

Whether it concerns linguistics, economics, politics, sustainable development, law, history, educational sciences, literature or translation, research in the humanities and social sciences is as eclectic as it is rich and essential for tackling society's challenges. Of UNamur's eleven research institutes, seven are directly involved in SHS research. While there is a high degree of complementarity in these areas of research, better pooling of resources, sharing and easier access to certain services, resources and support will help to sustain and strengthen the excellence of SHS research at UNamur. It is with this in mind that the SHS impulse platform has just been created.

• Axis 1 - Support for the acquisition of databases, documentary resources and software
• Axis 2 - Subsidy for cutting-edge training in the use of specialized methods
• Axis 3 - Funding access to the SMCS "Support en Méthodologie et Calcul Statistique" platform at UCLouvain, thanks to an inter-university partnership.
• Axis 4 - Setting up an SHS space, containing a laboratory for running experiments and shared work tools promoting exchanges between researchers.

This initiative, launched in January 2025, addresses the specific challenges faced by SHS researchers. The long-term aim is to sustain and expand the services. "We will also hire a researcher expert in methodological analysis in SHS who will be able to inform innovative methodologies and frame the methodological design of research projects," emphasizes Sandrine Biémar, vice-dean of UNamur's Faculty of Education and Training Sciences, a member of the IRDENA institute and the SHS Impulse management committee. "The wish is also to support networking between SHS researchers at UNamur and to be a lever for setting up interdisciplinary projects," adds Sandrine Biémar.

The platform's management team is made up of representatives of the university's various SHS institutes, and ensures efficient management of resources. The platform's impact will be assessed during its initial phase (2025-2027), enabling strategies for its sustainability and development to be defined.