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The PAX (antiProtonic Atom X-ray spectroscopy) experiment is the first to use TELMAX, the new antiproton test beamline at CERN’s antimatter factory. It aims to test the theory describing the interactions between light and charged particles, known as quantum electrodynamics (QED), under conditions of intense electric fields. But why these conditions? “Although QED is well understood for light systems such as hydrogen atoms, it hasn’t yet been explored in detail for highly charged atoms in the presence of strong electric fields," explains the experiment’s spokesperson, Nancy Paul. “This is due to experimental challenges and uncertainties linked to unknown nuclear properties. In fact, the effects of QED are magnified by intense electric fields, and this gives us a better chance of measuring them.”
Adiabatic Demagnetisation Refrigerator (ADR) cryostat for the PAX prototype TES detector, open on the bottom, where one can see the 80 mK cold plate connected to the readout electronics. Insert: The PAX prototype TES detector (2 x 2 x 4 cm), consisting of 64 pixels and integrated microwave multiplexed readout electronics. For the experiment, this detector is mounted on the end of the cold-finger in the ADR cryostat. (Image: PAX/NIST Quantum Sensors Division).The PAX experiment is being conducted by a team from France’s Centre national de la recherche scientifique (CNRS) and is funded by the European Research Council (ERC). It is employing a novel approach, namely very high-precision spectroscopy of the X-rays emitted by antiprotonic atoms, i.e. atoms that contain an antiproton orbiting around the nucleus. By studying the transitions between the various states of these atoms, the team will obtain more accurate results than through other approaches. Two novel technologies are being harnessed in tandem to achieve this: the low-intensity antiproton beams delivered by TELMAX and a quantum-sensing X-ray detector.
To create antiprotonic atoms – atoms in which an electron is replaced by an antiproton – TELMAX's antiproton beam is directed at a solid target (made of zirconium, silicon or gold) or a gas target (neon, argon, krypton or xenon), depending on the case. “These antiprotonic atoms generate Coulomb fields that are much more powerful than those generated by 'conventional' atoms; this is what magnifies the effects of QED,” Nancy Paul explains. By studying QED under these special conditions, the collaboration hopes to detect minuscule deviations from the predictions, which could point to unknown phenomena. “The Standard Model of particle physics is incomplete, and precision measurements in quantum systems are crucial to deepening our knowledge of QED and possibly discovering new physics”, notes Nancy Paul.
The brand new quantum-sensing X-ray detector used by PAX also improves sensitivity beyond what was previously available with traditional approaches. “For our experiment, we are using a new microcalorimeter X-ray detector based on Transition Edge Sensors (TES). This kind of detector offers energy precision that is 50 to 100 times better than semi-conductor detectors – with attainable accuracies of 1 eV on 100 keV X-rays”, she adds. The detector was built by a team from the Quantum Sensors Division of the US National Institute of Standards and Technology (NIST). The same types of detectors are used in areas such as X-ray astronomy on satellites, in the ATHENA project, for example. PAX is the first application of this novel technology for antimatter.
anschaef Thu, 06/05/2025 - 13:44 Byline Anaïs Schaeffer Publication Date Fri, 06/06/2025 - 08:34Alasdair Smith passed away in March at the age of 82. After receiving a PhD in physics from the University of Glasgow in 1970, Alasdair began a long career at CERN, working on experiments at the ISR, then on OPAL at LEP and, finally, on LHCb at the LHC.
At the ISR, Alasdair worked on three experiments: R103, R105 and R108, contributing to the construction and set-up of the detectors and associated electronics. In particular, he took part in the design and construction of the cylindrical drift chambers located inside the superconducting solenoidal magnet of the R108 detector.
After the closure of the ISR, Alasdair moved on to LEP, where he was the OPAL liaison officer in the CERN Experimental Support group. Alasdair played an instrumental role in the OPAL experiment throughout its existence. As OPAL’s Technical Coordinator, he piloted the technical project from before any hardware existed right through to when the last piece left LEP Point 6 for disposal. In many ways, he pioneered the concept of what the technical coordinator of a large experiment should do.
Alasdair was competent, efficient, always available to give advice and seemingly never nervous, constantly reassuring and minimising stress for everyone. He remained on top of all the details while still creating an atmosphere of mutual trust: delegating responsibility to team members and supporting all the subsystem technical communities, as well as those involved in detector operations.
Finally, in October 2001, Alasdair joined the LHCb experiment, where he remained until his retirement in December 2007. He joined the collaboration’s management as Resource Coordinator, taking over from Hans-Jurgen Hilke, who had been both Resource Coordinator and Technical Coordinator simultaneously. Alasdair joined at a very timely moment for LHCb, as the experiment entered a phase where the work of Technical Coordinator was rapidly increasing. Alasdair was a fantastic Resource Coordinator, keeping everybody in the collaboration on their toes while not being bureaucratic. He also ensured good relations with the funding agencies, which trusted him. Given the size of the LHCb collaboration at that time – comparable to that of a LEP experiment – his approach was a perfect match.
Alasdair also took advantage of opportunities to relax, bringing his Scottish traditions to CERN. For example, he and two fellow bagpipers symbolically piped the OPAL detector into the LEP Point 6 cavern.
Alasdair will be sorely missed by those who worked with him, as well as by those who had only occasional contact with him. Much sympathy goes to his wife, Christiane, and to all of his relatives.
His colleagues and friends
ndinmore Wed, 04/30/2025 - 10:20 Publication Date Wed, 04/30/2025 - 10:19
Did you know that the camera sensor in your smartphone could help unlock the secrets of antimatter? The AEgIS collaboration, led by Professor Christoph Hugenschmidt’s team from the research neutron source FRM II at the Technical University of Munich (TUM), has developed a detector using modified mobile camera sensors to image in real time the points where antimatter annihilates with matter. This new device, described in a paper just published in Science Advances, can pinpoint antiproton annihilations with a resolution of about 0.6 micrometres, a 35-fold improvement over previous real-time methods.
AEgIS and other experiments at CERN’s Antimatter Factory, such as ALPHA and GBAR, are on a mission to measure the free-fall of antihydrogen within Earth’s gravitational field with high precision, each using a different technique. AEgIS’s approach involves producing a horizontal beam of antihydrogen and measuring its vertical displacement using a device called a moiré deflectometer that reveals tiny deviations in motion and a detector that records the antihydrogen annihilation points.
“For AEgIS to work, we need a detector with incredibly high spatial resolution, and mobile camera sensors have pixels smaller than 1 micrometre,” says Francesco Guatieri, the principal investigator on the paper. “We’ve integrated 60 camera sensors into our detector, enabling it to achieve a resolution of 3840 mega pixels – the highest pixel count of any imaging detector to date.”
Previously, photographic plates were the only option, but they lacked real-time capabilities,” added Guatieri. “Our solution, demonstrated for antiprotons and directly applicable to antihydrogen, combines photographic-plate-level resolution, real-time diagnostics, self-calibration and a good particle collection surface, all in one device.”
The researchers used commercial optical image sensors that had previously been shown to be capable of imaging low-energy positrons in real time with unprecedented resolution. “We had to strip away the first layers of the sensors, which are made to deal with the advanced integrated electronics of mobile phones,” says Guatieri. “This required high-level electronic design and micro-engineering.”
A key factor in achieving the record resolution was an unexpected element: crowdsourcing. “We found that human intuition currently outperforms automated methods,” says Guatieri. The AEgIS team asked their colleagues to manually determine the position of the antiproton annihilation points in each of the more than 2500 detector images, a procedure that turned out to be far more accurate and precise than any algorithm. The only downside: it took up to 10 hours for each colleague to plough through every annihilation event.
“The extraordinary resolution also enables us to distinguish between different annihilation fragments,” says AEgIS spokesperson Ruggero Caravita. By measuring the width of tracks of different annihilation products, the researchers can investigate whether the tracks are produced by protons or pions.
“The new detector paves the way for new research on low-energy antiparticle annihilation, and is a game-changing technology for the observation of the tiny shifts in antihydrogen caused by gravity,” says Caravita.
Read more:
Paper: Real-time antiproton annihilation vertexing with sub-micron resolution
anschaef Wed, 04/02/2025 - 13:23 Byline Alex Epshtein Publication Date Wed, 04/02/2025 - 16:22Congratulations to the winners of the 2024 ATLAS thesis awards. Every year, these awards celebrate the outstanding achievements made by PhD students working with the collaboration, recognising the significant impact of their research on physics analyses, detector advancements and software development.
“The ATLAS Thesis Awards not only recognise the dedication and excellence of our early-career researchers but also underscore the critical role they play in advancing the experiment’s scientific mission,” said Jean-François Arguin, Chair of the 2024 Thesis Awards Committee. “This year’s submissions were of an exceptional standard, reflecting the depth and breadth of research within ATLAS.”
Explore the winning theses:
This year’s award ceremony took place on 20 February in CERN’s Main Auditorium. More details can be found on the ATLAS collaboration website.
ndinmore Mon, 03/10/2025 - 16:22 Byline ATLAS collaboration Publication Date Tue, 03/11/2025 - 16:18
The ATLAS collaboration welcomes its new management team, who began their mandate in March 2025. Succeeding Andreas Hoecker as ATLAS Spokesperson is Stéphane Willocq (University of Massachusetts Amherst). A long-standing ATLAS member since 2004, he brings extensive leadership experience to the role, having previously served as Deputy Spokesperson, ATLAS Physics Coordinator and Chair of the Publications Committee. Joining him in the new management team are Deputy Spokespersons Anna Sfyrla (University of Geneva) and Guillaume Unal (CERN), alongside returning members Technical Coordinator Martin Aleksa (CERN), Resources Coordinator David Francis (CERN) and Upgrade Coordinator Benedetto Gorini (CERN).
The new team, who have been elected for a two-year term, will steer ATLAS through the final phase of LHC Run 3 and navigate the transition into the High-Luminosity LHC (HL-LHC) era. This is a pivotal moment for ATLAS as the collaboration prepares for extensive upgrades to the experiment.
“I want to express my deep gratitude to Andreas for his leadership and dedication to ATLAS,” says Willocq. “During his two terms as Spokesperson and two preceding terms as Deputy Spokesperson, he played a key role in advancing our scientific programme and strengthening our collaboration. We are building on a solid foundation thanks to his efforts. I also want to extend my appreciation to Manuella Vincter for her six years as Deputy Spokesperson. Her commitment to ATLAS and its members has been invaluable.”
“The strength of ATLAS lies in its people,” Willocq continues. “Our collaboration spans the globe, bringing together individuals from diverse backgrounds and areas of expertise to tackle some of the most profound questions in nature. As we set course for the HL-LHC era, we can do so with confidence, knowing that our collective efforts have consistently driven major scientific advances.”
For more information, including detailed biographies, visit the ATLAS website.
ndinmore Mon, 03/10/2025 - 16:18 Byline ATLAS collaboration Publication Date Tue, 03/11/2025 - 16:10It is with a heavy heart that we share the news of the passing of Senamile Masango, a member of the CERN Alumni Network. A pioneering South African nuclear scientist, entrepreneur and advocate for the UN Sustainable Development Goals, she dedicated her life to advancing science and empowering women in STEM. As the founder of the Senamile Masango Foundation, she worked to build a brighter future for Africa, ensuring that no one was left behind in the pursuit of knowledge and opportunity.
Hailing from a Zulu royal lineage, Senamile began university at the age of 16. During her master’s studies at the University of the Western Cape (UWC) in South Africa, she came to CERN in 2017 as the only female member of an African-led team that conducted an experiment at ISOLDE to investigate the isotope selenium 70. She graduated with a master’s degree cum laude in nuclear physics from UWC, based on work done at TRIUMF, the Canadian National Facility for Nuclear and Particle Physics.
She was named one of the 50 Global Inspirational Women of 2020, was a Women in Tech Global Awards finalist in 2021 and was a recipient of the International Women in Science Award in 2022.
Senamile was a strong supporter of the CERN Alumni Network, recognising the importance of global scientific collaboration and mentorship. She was a keynote speaker at CERN Alumni Third Collisions in 2024, with an inspiring talk entitled “Changing the World Through Science by Taking Science to the Community,” which deeply resonated with the audience, reflecting her passion for making science accessible to all.
Our thoughts go out to Senamile’s family, friends and colleagues.
The CERN Alumni Relations Team
katebrad Mon, 02/24/2025 - 12:14 Publication Date Thu, 02/27/2025 - 12:14We received news of the passing of Paul Kuijer with great sorrow. Paul was a senior experimental physicist at Nikhef and played an important role in the ALICE experiment at CERN. During the last years of his career, Paul had turned his attention mostly towards the ET Pathfinder project within the Gravitational Waves group at Nikhef and the University of Maastricht. While he officially retired in 2024, he still came to Nikhef weekly and continued to contribute to several projects.
Paul worked on his PhD at the University of Amsterdam with the MARK-J experiment at the PETRA accelerator in DESY, Hamburg, where he performed a search for the top quark and measured the strong coupling constant using electron–positron collisions. In 1987, he joined Utrecht University as an assistant professor and worked on various experiments at the Institute for Nuclear Physics. In 1994, he became a member of the ALICE experiment at CERN and worked on the proposal and technical design report for the Silicon Strip Detectors (SSD), a joint project realised with laboratories in Finland, France, Italy, The Netherlands, Russia and Ukraine. In 2008, he became the first ALICE run-coordinator and, in 2009, he was selected as deputy spokesperson of the ALICE collaboration.
When his role as deputy spokesperson came to an end, he again worked on silicon detectors at Nikhef, overseeing the maintenance of the SSD, and, until 2019, was the project leader for the upgrade of the new ALICE Inner Tracking System.
In addition to working on hardware, Paul had a strong passion for physics, supervising many PhD students throughout his career. Everyone who worked with him remembers him fondly and with respect. He was an excellent scientist and a gentle, reliable person who would always make time to discuss physics and help with the daily practical problems encountered by technicians, PhD students or staff members. Paul was known for his hands-on approach; he often had a small project on the go, and he never shied away from new challenges. He was very approachable and always made time to discuss physics or simply chat with students and staff alike.
We will greatly miss his friendly and warm personality. Paul leaves a great void in our community. Our thoughts are with the family, friends and close colleagues that Paul leaves behind.
His friends in the ALICE collaboration
katebrad Mon, 02/24/2025 - 11:54 Publication Date Thu, 02/27/2025 - 11:53The Standard Model of particle physics is based on the idea that if you simultaneously swap a matter particle for its antimatter version (changing the sign of its charge), flip its spatial coordinates as if viewed through a mirror (parity) and reverse the direction of time, then there should be no difference in the behaviour of the two particles. Due to the central role of fundamental symmetry in quantum field theory, discovering even a small violation of this principle, known as charge-parity-time (CPT) symmetry, would suggest that our understanding is incomplete and could point to new physics beyond the Standard Model.
Experiments at CERN’s Antimatter Factory test fundamental principles such as CPT symmetry by studying the properties and behaviour of antimatter and comparing them with normal matter. The ALPHA experiment performs such tests through spectroscopy of antihydrogen – that is, by measuring the frequencies of transitions in the anti-atom using laser light or microwaves. If the results match those of normal hydrogen, the measurement is consistent with CPT symmetry. These frequencies, measured in units of Hz, equivalent to one per second, correspond to the energy level intervals in atoms and the spectral lines that arise when they make quantum transitions between levels. To accurately compare matter and antimatter, the frequencies must be determined incredibly precisely, requiring ultra-precise clocks. That’s why a caesium fountain clock was recently installed in ALPHA and a new optical fibre link between the experiment and the French National Metrological Institute in Paris is now online. Both the clock and the optical link will help improve the precision of ALPHA’s antihydrogen measurements by orders of magnitude.
“For our previous measurement of the transition between the ground state and the first excited state of antihydrogen, we used a simpler clock made out of a quartz oscillator referenced via GPS satellite as a frequency reference, and we reached a precision on the transition frequency of two parts per trillion (2×10-12),” says physicist Janko Nauta from the ALPHA collaboration. “However, the equivalent measurement on hydrogen, performed a few years before our antihydrogen measurement, has an even higher precision, of four parts per quadrillion (4×10-15), calling for a better clock to look for potential differences between matter and antimatter.”
The SI second is defined as the duration of 9 192 631 770 oscillations between two levels of the ground state of the caesium-133 atom. The caesium fountain clock that the ALPHA researchers received and installed in 2022 tells them exactly how long one second lasts. (Image: CERN)“For ALPHA, both the optical fibre link and the caesium fountain clock play important roles in making antihydrogen measurements with a precision that matches that of the hydrogen measurements,” continues Nauta. “While we rely on the clock, the link helps us to reduce noise in the measurement and to better evaluate the clock in the long term, to verify that it stays accurate. In addition, the link will make it possible to use signals from optical quantum clocks in the future, surpassing the stability of clocks that currently realise the SI second.”
The link is part of the REFIMEVE+ network, a project that distributes an ultra-stable optical frequency reference to research laboratories across France and beyond via existing optical cables on the French internet network. It is a pilot implementation of a new project that aims to connect multiple experiments at CERN to REFIMEVE+. This has the potential to improve the precision of clocks across CERN and could provide a new way for the Laboratory to access Coordinated Universal Time (UTC) – the global standard for timekeeping. The optical signal from the link can synchronise with UTC more precisely than via GPS satellite, which is currently used across CERN.
“The CERN Quantum Technology Initiative envisages having more precise frequency signals delivered to CERN from other national metrology institutes and distributing them to all the interested experiments at the Laboratory,” says Edoardo Martelli from CERN’s IT department. “Having more sources allows a more precise synchronisation of the local clocks and increases the robustness of the service.”
ALPHA’s most recent precise measurement of the transition between the ground state and the first excited state of antihydrogen has placed tighter constraints on violations of CPT symmetry than its previous measurement. With the new optical link, the collaboration hopes to put CPT symmetry to even more stringent tests.
ndinmore Fri, 02/21/2025 - 09:36 Byline Naomi Dinmore Publication Date Fri, 02/21/2025 - 09:27
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