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Tens of kilometres above Earth’s surface, high-energy particles from outer space constantly strike the atmosphere, creating showers of energetic secondary particles that rain down from the sky. Approximately one of these particles passes through your head every second, but the “cosmic rays” that produce them are still not fully understood. In a recent paper, the ATLAS Collaboration describes how its first measurement of proton–oxygen collisions at the LHC could help us learn more about them.
Cosmic rays were discovered over a century ago by physicist Victor Hess in experiments conducted aboard hot-air balloons. Today, astrophysicists use detectors on the ground to image cosmic-ray showers and computer simulations of the showers to understand that data.
However, these simulations depend on properties of the strong force – one of the fundamental forces of the Universe – which is difficult to accurately model. Current simulations disagree with one another, making it difficult for astrophysicists to interpret their measurements of cosmic rays.
In part to help improve these simulations, the LHC was configured to collide protons with oxygen ions for the first time in July 2025. This meant physicists could study ‘recreated’ cosmic-ray collisions in more detail. The beam of protons acted as a cosmic ray, while the beam of oxygen ions played the role of Earth’s atmosphere, which is composed primarily of nitrogen and oxygen.
The new paper describes how ATLAS physicists analysed these collisions by measuring the tracks left in the experiment from electrically charged particles. They measured key properties of the collision, including how often the particles were created, how many were created, and the energies and angles at which they flew out.
They then compared the measured distributions of charged particles with the numbers predicted by various simulations typically used to interpret data from cosmic-ray observatories. These simulations, which are tuned to reproduce data from previous collisions of protons with heavier nuclei, disagree with one another.
The new ATLAS measurements achieve a precision level of a few percent, significantly improving knowledge of proton–oxygen collisions. Theorists can now use this input to refine their models and help shed more light on the mysterious high-energy particles arriving from our cosmos.
Read more on the ATLAS website.
ehatters Mon, 04/20/2026 - 17:33 Byline ATLAS collaboration Publication Date Tue, 04/21/2026 - 10:29According to our current understanding of the Universe, quarks are fundamental, point-like particles: basic building blocks that are not made up of smaller particles. A recent paper from the CMS Collaboration describes how it probed quarks to the scale of 10-20 metres to test this premise.
At this scale, no evidence of constituent particles was identified, but history shows that structures once considered fundamental can reveal deeper layers: matter was found to consist of molecules, which were then found to be made of atoms, which were in turn found to consist of a dense nucleus surrounded by a cloud of electrons.
Rutherford discovered the nucleus by sending a beam of helium nuclei onto a gold-foil target. These nuclei scattered off the gold atoms of the foil at various angles, which Rutherford then measured. By studying the distribution of the scattering angles, he was able to prove that atoms contained a point-like nucleus at the centre. This was possible because the helium beam in the experimental set-up had enough energy to probe the inside of the atoms.
The nucleus was then shown to be made of protons and neutrons, which were themselves later found to consist of quarks. LHC experiments including CMS are now continuing this quest, colliding particles at extremely high energies to probe the potential inner structure of quarks.
When two beams of protons collide within CMS, they break apart into their constituent quarks. These outgoing quarks become two jets – sprays of particles – that can be measured and used to reconstruct the scattering angle between the quarks.
The distribution of the scattering angle between the two jets can be compared to the distribution that would be expected if the quark was indeed a point-like particle. The recent results from the CMS Collaboration, which were based on data from the second run of the LHC, showed no significant disagreement with the scattering distribution of a point-like quark. This means that quarks are not likely to be larger than 10-20 metres if they are composite structures.
This size estimate is derived from the constraints on the energy scale at which quark ‘compositeness’ reveals itself. For the benchmark model of the recent CMS paper, which assumed that quarks were composite, the recent results set the most stringent limit to date at 37 TeV.
Similarly to how Rutherford was able to identify the components of the atom only because his beam of particles had enough energy, studying particle collisions with higher energies could help us to identify smaller potential structures within quarks. Data from the third run of the LHC and the upcoming High-Luminosity LHC could help to reduce the uncertainties on the measurement of the scattering angle, allowing us to identify even smaller structures and continue the search for the smallest building blocks of matter.
A collision event recorded by the CMS detector with two outgoing jets. (Image: CMS) ehatters Thu, 04/16/2026 - 14:57 Byline CMS collaboration Publication Date Thu, 04/16/2026 - 14:46One of the four missions of CERN is to “train new generations of physicists, engineers and technicians” in a broad area of subjects, topics and themes directly and indirectly linked to their interests, profession and duties. Any good training should make you grow intellectually and grow your skills, should allow you to advance in your career and pimp up your CV for any future professional direction you might strive for. “Food for your brain” is therefore the greatest nutrition for your intellect besides a good morning coffee and an Italian-native Hawaiian pizza. Here is the menu provided by the Computer Security Office.
Starting with the obvious: the all-you-can-eat offerings of the “SecureFlag” online training, whose training platform provides hands-on courses, exercises and virtual environments for improving your skills in secure software development in any programming language(s); for securely configuring your systems, VMs and containers; and for securely operating your web and computing services (demo video). These courses come in many levels of easiness, starting with general beginner sessions and delving deeper for the more experienced and advanced software developers, system administrators and service managers. The Computer Security Office has identified a list of must-do and recommended courses that will assist you in reviewing and/or developing your secure coding practices further. However, “all-you-can-eat” rightly offers you many more courses in the vast “SecureFlag” portfolio for a flat annual fee of less than 500 CHF so you can nurture your brain again and again until next year. Remember that these courses are mandatory for all relevant people as per these two OC5 Subsidiary Rules, so please check out the CERN Learning Hub for full details and to sign up! Enjoy your feast!
This all-you-can-eat buffet is complemented by the very delicious WhiteHat training, which is aimed at webmasters, web application developers and anyone else regularly or irregularly setting up, configuring, managing, publishing or posting dynamic contents on CERN-hosted web servers (and beyond). This two-session training course, the first for the basics and the introduction of homework challenges, and the second to resolve and discuss that homework, is supposed to bring your mind closer to all the traps and pitfalls that make a website insecure, vulnerable and eventually broken – and teach you how to avoid them. New sessions are supposed to come soon, so keep an eye on this Indico agenda or follow our Monthly Report to avoid missing the announcement.
For the more security gourmets among you, the Computer Security Office also provides the “the best technical training that I have ever received at CERN _by far_. I want to warmly thank the teachers/experts very much, _excellent_ work.” – according to one senior staff who participated in the second Forensics & Incident Response training. And the next one is already scheduled: for sysadmins and security professionals managing CERN IT services, involved in the experiments’ IT administration or in WLCG computing, we are offering another hands-on training in Linux digital forensics. Participants will learn techniques for identifying, collecting and analysing digital evidence using open source tools. Through practical exercises and interactive table-top scenarios, attendees will gain confidence in handling security incidents, from initial detection to effective containment and recovery. This two-day event on 11 and 12 June offers an opportunity to explore realistic security incidents and develop the skills for effective response. A few spots are still available...
And, finally, for dessert: the “Zebra Alliance” incident response table-top with an interesting and challenging computer security breach scenario to be solved. This scenario is based on a real incident and will introduce you to the real technical and social challenges when handling large-scale computer security incidents worldwide. The next one is scheduled for Friday, 22 May. Seats are limited, so reserve soon here on Indico. Bon appétit!
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Do you want to learn more about computer security incidents and issues at CERN? Follow our Monthly Report. For further information, questions or help, check our website or contact us at Computer.Security@cern.ch.
anschaef Wed, 04/15/2026 - 11:45 Byline Computer Security Office Publication Date Wed, 04/15/2026 - 11:43
Beyond 25 by ’25
Following the successful conclusion of “25 by ’25” at the end of 2025, the Diversity & Inclusion (“D&I”) Programme is now building on this momentum by launching a new D&I initiative for CERN: “Inclusion Matters.”
With “25 by ’25”, CERN committed to strengthening gender and nationality diversity through a first-time aspirational target. “Inclusion Matters.” will continue to strengthen and retain this diversity while fostering a strong sense of belonging across the CERN community.
A call to contribute
Inspired by the Director-General’s vision for CERN as “a beacon of inclusivity in science, where diversity in all its forms can thrive”, the new initiative invites members of the CERN community to propose practical solutions for an even more inclusive workplace by 2030.
50 actions. 5 years. One shared commitment.
“Inclusion Matters.” contains an Organization-wide goal to deliver 50 visible and tangible inclusion actions over the 2026–2030 mandate, with 10 actions committed to each year, at a rhythm of roughly one per month, collectively referred to as “50 Inc.”. Each action, however small, is intended to make a meaningful difference to at least one community or individual, with the cumulative effect strengthening inclusion across CERN.
What do “inclusion actions” look like?
Inclusion-orientated actions for the first months of 2026 include:
How can I contribute?
Members of the CERN community will be invited to submit 50 Inc. action proposals via an online ticketing form as of mid-May.
In reviewing proposals, the newly established Diversity & Inclusion Strategic Oversight Board (D&I Board) will assess the diversity of actions, of beneficiary communities and of implementing services, as well as considering feasibility, benchmarking and strategic alignment. The D&I Board will also take into account perspectives from the departmental D&I Officers, diversity networks and D&I contact points within the experiment collaborations. This input will be coordinated, consolidated and presented to the D&I Board by the D&I Programme Advisers.
Progress on actions toward 50 Inc. will be tracked through an online dashboard.
Colleagues are encouraged to gather practical ideas that could further inclusion in everyday working life at CERN.
Click here to contribute your 50 Inc. action proposal: Inclusion Matters. I Diversity & Inclusion Programme
anschaef Wed, 04/15/2026 - 11:31 Byline Daniela Antonio Publication Date Wed, 04/15/2026 - 11:31The LHC has successfully reached its nominal Run 3 performance, marking an important milestone in the 2026 physics programme. The intensity ramp-up phase was completed at the end of March, with the machine routinely operating at 1.8×10¹¹ protons per bunch in each beam. Following this achievement, the LHC entered a period of stable physics production for about a week, during which the machine delivered performance that significantly exceeded expectations (see figure).
Luminosity delivered to ATLAS and CMS. (Image: CERN)
After this initial high-performance period, the LHC has now entered a dedicated three-week run with reduced pile-up conditions, which means a lower average number of collisions per bunch crossing (the so-called low-μ run). This special mode of operation is an integral part of the 2026 proton–proton physics programme and has been requested by the ATLAS and CMS collaborations to allow them to perform high-precision measurements under optimised experimental conditions.
In standard LHC operation, each bunch crossing typically results in around 64 simultaneous proton–proton interactions. By contrast, the number of interactions per crossing is significantly reduced during the low-μ run. These conditions provide a much cleaner experimental environment, allowing improved control of detector effects and a significant reduction of background noise. Owing to the reduced collision rate, this mode of operation involves particularly long fills lasting up to 50 consecutive hours.
This dedicated data-taking period is primarily motivated by the goal of high-precision measurement of the W boson mass. Achieving the target level of precision requires excellent control of the collision reconstruction, in particular for the hadronic recoil and the missing transverse energy, both of which are significantly improved in low-pile-up conditions. More broadly, the low-μ dataset will also enable a wide range of precision measurements, including studies of electroweak, heavy-flavour and diffractive physics.
A dedicated Van der Meer (VdM) run to provide data for absolute luminosity calibration was initially scheduled to take place during this period. The VdM method consists of transversely sweeping the two beams across each other while measuring the collision rate as a function of their relative displacement. This allows a precise determination of the absolute luminosity scale, ensuring that all subsequent measurements can be normalised with high accuracy.
Such calibration runs require specially prepared beams, with well-defined transverse profiles and controlled intensities. Producing these beams involves a dedicated scheme across the entire injector chain. In the PS Booster, this includes techniques such as controlled tune settings, multiple scattering on the stripping foil and adjustments of the injection trajectory. The beam is then transferred to the PS, where injection oscillations must be carefully minimised. Finally, in the SPS, a dedicated manipulation known as “shaving” is applied to shape the beam distribution before injection into the LHC. These preparatory steps typically require several days of dedicated beam time ahead of the calibration run itself.
However, an unforeseen issue in the LHC cryogenic infrastructure has required a short interruption of operations. One of the warm screw compressors in the station at Point 18, which had already shown elevated vibration levels in recent weeks, exhibited signs of rapidly evolving bearing degradation. In the last few days, the vibration levels increased further and became less stable, indicating a growing risk of significant damage.
To mitigate this risk and protect the integrity of the compressor station, it was decided to bring forward the replacement of the unit, which had originally been planned for the technical stop in May. This intervention was performed early this week, resulting in a three-day stop of the LHC.
Meanwhile, in the injector chain, the availability of the PS was impacted by a major fault affecting the main power supply (POPS). The issue, involving communication and controller failures, required significant intervention by the power converters team. Operation was restored after component replacement and diagnostics. While the root cause is still under investigation, the event highlights the ageing of critical components and the importance of the planned POPS+ upgrade during LS3.
Despite these interruptions, the overall performance of the accelerator complex remains excellent. With nominal intensity reached and dedicated physics runs under way, the 2026 LHC programme is now fully in motion, with further key milestones expected in the coming weeks.
anschaef Wed, 04/15/2026 - 10:59 Byline Matteo Solfaroli, Deputy Leader of the Operations Group (BE-OP) Publication Date Wed, 04/15/2026 - 10:56
For its 2026 edition, Beamline for Schools (BL4S) has received 712 submissions, involving 4051 students from 89 countries, the highest number of applications since its creation in 2014. This represents a 40% increase compared to the 2025 edition and the highest ever number of countries participating. Since the launch of the competition, more than 28 000 students have submitted research proposals. The selection process is ongoing, and the winning teams will be announced in May, so stay tuned!
Beamline for Schools is an education and outreach project, funded by the CERN & Society Foundation, that started in 2014 in the context of CERN’s 60th anniversary. Multiple teams of high-school students propose an experiment to be performed on a beamline at CERN, DESY or ELSA (University of Bonn) – an experience designed to inspire the scientists of tomorrow to pursue careers in STEM (science, technology, engineering and mathematics). The winning teams have the opportunity to run their experiment like true physicists, immersed in a cutting-edge physics environment in one of the three laboratories.
“High-school students are very creative, and the proposed experiments grow each year in complexity, creativity and technicality”, says Jorge Villa, school and students programmes manager at CERN. Previous winners have explored a wide range of scientific topics, from the development of two-dimensional detectors and three-dimensional muon detectors using scintillator encoding, to the use of Silicon Photomultiplier (SiPM)-on-tile muon calorimeters for high-altitude applications and multi-wire proportional chambers. Some teams have worked on beam diagnostics in CERN’s East Area, leading to remarkable results. Experiments related to particle beam interactions and radiation studies like spallation and? transition radiation in multi-layered dielectric–metallic targets have also been carried out. “We regularly review and update the pool of detectors available to the students, to give them the best tools for their experiments. Right now, we are working on integrating MicroMegas and Timepix detectors into our experimental setup”, says Markus Joos, BL4S technical coordinator at CERN. The competition has led to scientific publications, educational publications and contributions in international conferences and workshops (see here).
This competition is only possible thanks to the many volunteers at CERN, DESY and ELSA. A huge thanks to all of them!
Join the BL4S team!
Marteen van Dijk (BE Department) gives a lecture on Cherenkov detectors at CERN during the 2025 edition of BL4S. (Image: CERN)Members of the CERN community are more than welcome to join the Beamline for Schools team.
BL4S exists thanks to the many volunteers who help throughout the year in many ways, such as reviewing the proposals to select the winning teams (in March 2026, 40 volunteers contributed to the review of 712 proposals), taking part in online events to present their research and experiments to the students, helping with data analysis when the winning teams are at CERN or acting as regional contacts for students of the same native language.
For the 2026 edition, additional support will be required in August for data analysis activities and after the summer for online events and national contact activities.
Go to cern.ch/bl4s to find out more. For more information about volunteering, subscribe to bl4s-volunteers-pool. You can also send an email to beamline.4.schools@cern.ch, and we will be happy to get back to you to discuss the different volunteering options.
With the increasing number of proposals, we will need more volunteers, in particular to evaluate the proposed experiments and select the winning teams. Come and join us – be part of an amazing initiative that has a worldwide impact on the education of high-school students.
anschaef Wed, 04/15/2026 - 10:39 Byline Jorge Villa Publication Date Mon, 04/20/2026 - 10:36At 00:35 CEST today, the Artemis II mission successfully launched, marking the first human journey to the Moon since 1972. During their ten-day journey aboard the Orion spacecraft, the four astronauts are expected to receive tens of millisieverts of radiation, more than ten times what most people experience in an entire year on Earth. Understanding and managing this exposure is essential if humans are to continue to explore space safely.
This is precisely the role of the six Timepix chips on board Artemis II. Developed at CERN, they have been deployed through a collaboration with ADVACAM, a CERN partner specialising in photon-counting imaging technologies. The chips form part of NASA’s Hybrid Electronic Radiation Assessor (HERA) system, which is designed to monitor the radiation environment inside the Orion spacecraft. The system will measure the composition, intensity and energy of incoming particles in real time, helping scientists to assess the radiation exposure of both crew members and onboard electronics.
Unlike low Earth orbit missions, such as those to the International Space Station, Artemis II will travel beyond the protection of Earth’s geomagnetic field. During the journey, astronauts will pass through the Van Allen radiation belts, regions of trapped charged particles that increase their overall radiation exposure significantly. They will also face higher levels of galactic cosmic rays and solar particle events, highly energetic radiation that can affect both human health and sensitive electronic systems. In such environments, real-time radiation monitoring and characterisation and real-time response are essential, particularly in the case of sudden radiation events, such as coronal mass ejections, which can rapidly increase exposure.
Timepix detectors were developed by the CERN-hosted Medipix2 Collaboration, which designs hybrid pixel detector technologies for imaging and radiation measurement. Based on hybrid pixel detectors, a technology originally created for particle physics experiments, the Timepix detectors are closely related to the detectors used in the Large Hadron Collider to track particles produced in high-energy collisions. Over time, the technology has been adapted for space applications through contributions from multiple partners. For Artemis II, Timepix-based systems have been implemented in collaboration with ADVACAM and will contribute to radiation measurements during the mission.
The Timepix chip, developed for the needs of the LHC experiments, is now being used in space missions (Image: CERN)At the core of the Timepix technology, each chip consists of a matrix of pixels capable of detecting individual particles and measuring the energy they deposit. Combined with the characteristic shapes of the tracks left in the sensor, this allows different types of radiation to be identified. Despite their small size, the detectors provide detailed spatial and energy information, making them well-suited to the mixed-field radiation environment of space.
This is not the first time that Timepix has gone into space. Timepix technology has been used in space for over a decade. First deployed on the International Space Station in 2012, it has since supported radiation studies in orbit and is now integrated into instruments such as HERA for exploration-class missions.
As humanity makes its return to the Moon and prepares to travel further into deep space, understanding radiation exposure becomes increasingly important. Data collected by the Timepix chips during the Artemis II mission will provide new insights into the radiation environment beyond Earth’s orbit and its impact on both spacecraft systems and the health of the crew. These measurements will help to refine radiation models, evaluate shielding strategies and improve risk assessment for future missions.
mearnold Wed, 04/01/2026 - 16:59 Byline Feza Tankut Publication Date Thu, 04/02/2026 - 10:55Following on from the robotic mice, CERN engineers have now developed a super-charged kart to enable workers to race through the Large Hadron Collider (LHC) underground tunnel during the upcoming major works, starting this summer.
The karts promise a power boost to activities during this period, known as Long Shutdown 3 (LS3), which will see the LHC transformed into the High-Luminosity LHC. These vehicles will replace the bicycles that were used until now to travel through the 27-km underground tunnel, enabling engineers and technicians to speed to areas where improvements to the accelerator are required.
During CERN’s major works, starting this summer, karts and equipment will reach underground areas via giant green pipes. (Image: CERN)
“Each kart is turbo-boosted by 64 superconducting engines,” explains project leader Mario Idraulico. “When the engines are cooled to below their critical temperatures, the Meissner effect levitates the karts, allowing them to zip through the tunnels at high speeds and, mamma mia, they’re super!”
Early tests have been promising, and the next steps involve testing different kart designs in an underground race. Safety coordinator Luigi Fratello has ensured that each driver will be issued with Safety and Health Equipment for Long and Limited Stays (SHELLS), although his response to drivers wanting bananas in the tunnel was “Oh no!”
These karts, although developed to support CERN’s fundamental research programme, show clear applications for society. CERN’s Knowledge Transfer Group has begun discussions with European startup company Quantum Mushroom to explore aerospace applications and powering for next-generation anti-gravity vehicles.
Surprisingly, the kart project began from a collaboration between CERN engineers and onsite nursery school children – one example of CERN’s commitment to inspiring future generations. “We’re thrilled that the children’s kart designs were the inspiration for the engineered karts,” exclaimed schoolteacher Yoshi Kyouryuu, mid-way through painting spots on eggs for an Easter egg hunt.
“As educators, we promote curiosity from a young age, which is why we paint question marks all over our yellow school walls,” explained school director, Rosalina Pfirsich, looking up from her storybook. “With all the contributions the children have made to the upcoming High-Luminosity LHC project, we’ve taken to calling them Luma!”
katebrad Wed, 04/01/2026 - 08:17 Publication Date Wed, 04/01/2026 - 08:56Effective 2 April 2026, Chile has become an Associate Member State of CERN. Its status entered into force following Chile’s ratification of the Associate Member State Agreement of May 2025 and its accession to the Protocol on CERN’s Privileges and Immunities.
Chile is henceforth entitled to be represented at the CERN Council, Finance Committee and Scientific Policy Committee.
CERN’s partnership with Chile dates back to 1991, when the first international cooperation agreement was signed. Since then, Chilean universities and research institutions have made valuable contributions to a wide range of projects and currently participate in the ATLAS, CMS and LHCb experiments, the SND@LHC, NA64 and SHiP collaborations and the activities of the ISOLDE facility.
Chile’s status as an Associate Member State marks a significant deepening of CERN’s relations in the Americas and will open a new era of collaboration with Chilean institutions. It will also provide opportunities for Chilean nationals, who are now eligible to apply for limited-duration staff positions and to participate in CERN’s graduate programmes, as well as for Chilean firms, which are now entitled to bid for CERN contracts, strengthening both CERN’s supplier base and Chile’s national industry and technology sectors.
rodrigug Tue, 03/31/2026 - 14:55 Publication Date Thu, 04/02/2026 - 13:00After the major upgrades carried out during Long Shutdown 2 (LS2, 2019–2020), the LHC injector complex entered a new phase of operation. The LHC Injectors Upgrade (LIU) project consolidated and enhanced the accelerator chain to meet the demanding beam requirements of the High-Luminosity LHC (HiLumi LHC), scheduled to come into operation after Long Shutdown 3 (LS3, 2026–2030).
The LIU objective was clear: significantly increase the beam brightness and almost double the beam intensity delivered to the LHC. Each of the two LHC beams consists of more than 2000 tightly packed proton bunches that are spaced by just 25 nanoseconds, structured by the 40-MHz LHC radiofrequency system. After LS3, denser bunches will produce a substantially higher number of particle collisions in the LHC, opening the door to more precise measurements of the Higgs boson and rare processes and potentially revealing signs of new physics.
In the period between LS2 and LS3, efforts in the injector complex have focused on demonstrating that the upgraded machines could achieve the demanding LIU beam parameters. With this milestone now reached, attention has shifted towards ensuring reliable, stable and sustainable delivery of high-quality beams. This is a crucial step to guarantee that the HiLumi LHC can operate at peak performance from the very start of physics running, planned for 2030.
To this end, dedicated HiLumi LHC beam reliability runs have been introduced in the injector schedule. During selected weeks in 2026, short periods of beam time – typically around 30 minutes following each LHC fill – are reserved to simulate HiLumi LHC-type filling schemes with the new beam parameters. These runs are designed to test not only performance but also the robustness and reproducibility of operation and technical systems.
HiLumi LHC beam reliability runs already took place successfully in parallel operation last year in the machines of the Proton Synchrotron complex (Linac4, PSB and PS), and the first such reliability run in the Super Proton Synchrotron (SPS) was successfully carried out last week. Operating mainly during daytime on weekdays, and carefully scheduled around LHC operation and machine development periods, the SPS performed eight injection attempts, six of which reached flat-top energy. Typically, during these runs, 15 to 20 injections were accumulated, all meeting the beam quality criteria required for transfer to the LHC.
As expected for such high-intensity beams, stability posed some initial challenges. Special beam adjustments were required at the start of each run to maintain stable conditions. Continuous optimisation of the SPS cycle – including improved energy matching, orbit corrections, fine-tuning of local bumps and commissioning of the beam scraper – resulted in a clear improvement in performance over the course of the week, as illustrated inthe figure below. Throughout the run, vacuum conditions remained comfortably within operational limits. Thus, by the end of the run, reaching flat top had become significantly more routine.
By the conclusion of last week’s run, the SPS was routinely delivering beams at full HiLumi LHC nominal parameters: bunch intensities of 2.3×10¹¹ protons, transverse emittances of 2.1 micrometres and bunch lengths of 1.65 nanoseconds.
Following a short interruption this week to give priority to HiRadMat operations, the reliability programme will resume with a three-week period of more intensive running. This next phase will extend operation into nights and weekends, further testing the endurance of the injector complex under realistic conditions. The goal is clear: to build on the strong performance achieved so far and establish the level of reliability required for the HiLumi LHC era.
Evolution of the time required to reach the HL-LHC beam parameters during last week’s reliability run, demonstrating a clear improvement over the course of the week. (Image: CERN)ehatters Thu, 03/26/2026 - 17:36 Byline Bettina Mikulec, Leader of the Operations Group (BE-OP) Publication Date Thu, 03/26/2026 - 17:30
As the weather gets warmer and Easter approaches, we are celebrating once more with the relaunch of our photography competition for the CERN community. Please send us your best photos of “spring at CERN” for the chance to win a Chocopass, kindly offered by the CAGI cultural kiosk at CERN and Geneva Tourism. This Chocopass lets you spend a day exploring Geneva and tasting chocolate from a range of shops across the city.
To enter:
A big thank you to the International Geneva Welcome Centre (CAGI) and Geneva Tourism for offering a Chocopass to the winner! The CAGI cultural kiosk is located in CERN’s main building and is open from Monday to Friday from 8:30 a.m. to 1:30 p.m. It offers numerous discounts for local activities and events both in Switzerland and in France.
Find out more about CAGI on their website.
ehatters Thu, 03/26/2026 - 13:50 Byline Internal Communication Publication Date Thu, 03/26/2026 - 13:38On Thursday 12 March, Sławosz Uznański-Wiśniewski came to CERN to give an insider’s view of his time on the International Space Station (ISS) from 26 June to 14 July 2025.
Sławosz discussed the Ignis mission to the ISS, a Polish-led scientific and technical programme carried out in collaboration with the European Space Agency (ESA). One of the flagship investigations of the mission was developed at CERN and Sławosz personally installed and operated it on the ISS.
During the talk, Sławosz talked about this particular experiment and shared details of his experience in space.
The recording of Sławosz’s talk is now available online.
roryalex Thu, 03/26/2026 - 11:53 Publication Date Thu, 03/26/2026 - 11:52Following the successful conclusion of the 2023 cybersecurity audit, 2026 will see another series of vulnerability assessments, penetration tests (“pentests”) and cybersecurity reviews. While some are mandatory and conducted regularly, like those initiated when CERN buys new IT equipment, new software, or new hardware with an IT component, when CERN launches new projects encompassing information technology or when critical CERN computing services undergo a transition or migration to a newer major version, others are rather ad hoc and triggered at the initiative of the Computer Security Office. Here’s a short summary of what’s coming up next.
While the 2023 cybersecurity audit was formally and officially concluded by the CERN audit team at the end of 2025, some of its recommendations could only be scheduled for implementation in 2026 as either sophisticated preparations were needed or their deployment would heavily impact accelerator and experiment operations and therefore had to wait for LS3. Hence, this year will also see the technical conclusion of those remaining audit points, e.g. the change towards using 15-character passwords, the roll-out of 2-factor authentication to virtual machines used for accelerator software development, the newly encrypted CERN Wi-Fi (based on WPA3), the technical enforcement of CERN’s Computing Rules and the deployment of dedicated firewall protections for CERN’s Technical Network and, in 2027, the Campus network. So there is still some heavy lifting ahead.
Status of the 95 work tasks to fulfil the 2023 cyber-security audit. (Image: CERN)And there is more to come: at the end of 2025, the Computer Security Office contracted a penetration test of CERN’s Active Directory (AD) by an external company. Working like real attackers would, their experts were supposed to identify potential weaknesses and vulnerabilities in CERN’s AD which might allow an attacker to take over CERN’s computing infrastructure. And it comes as no surprise that they found a series of areas for improvement, so 2026 will see some modifications to CERN’s AD set-up and its LDAP configuration (like the extension of the usage of secure protocols like LDAPS, introduction of SMB signing, hardening of UNC paths, removal of insecure (encryption) protocols, and the change of some internal passwords). While many of these changes will happen behind the scenes, others might have some impact on CERN in general. However, as usual, the corresponding interventions will be announced well in advance.
In addition, in order to learn more about password hygiene at CERN and to complement the ongoing change from 8-character passwords with a certain complexity of symbols, numbers and upper/lowercase letters towards 15-character passwords (minimum), the Computer Security Office has invited a specialised company to come on site and try to brute-force and crack the passwords of CERN centrally managed primary, secondary and service accounts in a privacy-preserving manner. Owners of accounts with weak passwords will be informed and asked to improve their choice.
Also on the cards is a full-fledged vulnerability scan of thousands of internet-facing, public websites hosted at CERN (and not protected by the CERN Single Sign-On) as well as hundreds of servers opened towards the internet in order to identify weaknesses, misconfigurations and vulnerabilities. The corresponding tender is currently out, and the work is expected to be conducted during summer 2026 (and the findings fixed right afterwards). Once more, owners of websites or servers found to need improvement will be contacted directly. Already, here, a thank you for quickly addressing any issues!
And, finally, on 1 April, the Computer Security Office will invite all interested parties to conduct a series of pen-, pan- and panttesting offered in CERN’s Restaurant 2... Feel free to join!
Do you want to learn more about computer security incidents and issues at CERN? Follow our Monthly Report. For further information, questions or help, check our website or contact us at Computer.Security@cern.ch.
ehatters Wed, 03/25/2026 - 19:07 Byline Stefan Lueders Publication Date Wed, 03/25/2026 - 19:01In 2026, CERN has received funding for 13 new projects from the European Union’s R&D programme Horizon Europe, following applications to Research Infrastructures calls in 2025. All these projects will kick off this year and CERN will lead the coordination of five of them: ATTRACT EXPAND, EPITA, iRIS, PRISMAP+ and RADNEXT 2030.
The ATTRACT EXPAND project will build on the previous ATTRACT projects set up in 2018 to help turn world-class scientific research in Europe into commercial innovation. CERN’s innovation space, IdeaSquare, will play a key role in the project, coordinating it and acting as a hub within the ATTRACT Academy for many of the science-to-industry collaborations involving young European innovators. The new project aims to support 30 new high-potential technologies through an open call for funding.
EPITA aims to drive sustainable innovation in particle accelerator science by developing a portfolio of innovative technologies for a new generation of accelerators. This will be achieved through co-creation with industry in an open environment, maximising the technologies’ impact.
iRIS aims to develop and pilot AI-powered solutions to enhance the sustainability of research infrastructures. The project’s goal is to improve the energy efficiency of particle accelerators and technical infrastructures, develop strategies for the reuse of construction and demolition materials and accelerate soil restoration.
PRISMAP+ builds on the work of its predecessor project, PRISMAP, and aims to provide coordinated access to radionuclides for biomedical research in Europe through the medical-radionuclides.eu platform. It is conceived as a new phase of the European medical radionuclide programme, based on the production and delivery of high-purity-grade radionuclides.
RADNEXT 2030 builds on the success of the RADNEXT project to establish a sustainable, transnational and interdisciplinary radiation testing and research infrastructure that will support both scientific excellence and industrial competitiveness in Europe. Radiation effects induced by energetic particles in electronic and photonic components and systems are a critical concern for space science, avionics, high-energy physics, nuclear energy, IT infrastructure and many other mission-critical applications. This means that access to testing facilities is increasingly important. The project also supports activities at CERN, with RADNEXT 2030 enabling scientific access to the CHARM and HEARTS@CERN facilities.
If you wish to apply to a call from the European Union and need support or advice, get in touch with CERN’s EU Projects Office. Its mission is to oversee the participation of CERN in the EU programmes for scientific and technological cooperation and to provide support in the preparation and implementation of EU projects carried out at CERN.
ehatters Wed, 03/25/2026 - 18:50 Publication Date Wed, 03/25/2026 - 18:45
In an important step for open science, CERN has been selected to host a new phase of Open Research Europe (ORE), an initiative supported by the European Commission and a new funding consortium of European national funding agencies and research organisations. Aligned with the Action Plan for Diamond Open Access (2022)[1], the initiative is a community-led alternative to traditional academic publishing. When the new ORE platform is launched later this year, authorship eligibility will be expanded to include researchers affiliated with institutions in the countries that participate in the consortium. Publishing will remain completely free for both European Commission-funded researchers and authors from participating countries. The aim is to promote equity, diversity and transparency in scholarly communication while maintaining high standards of quality and integrity.
The ORE funding consortium currently comprises members from Austria, France, Germany, Italy, the Netherlands, Norway, Portugal, Slovenia, Spain, Sweden and Switzerland[2]. The European Commission participates as a permanent observer in the governance body and provides dedicated financial support. CERN will provide the technical and operational infrastructure for the platform, built on the open source software Open Journal Systems (OJS), while governance and editorial oversight will remain the responsibility of the ORE consortium.
ORE follows the innovative publish–review–curate model, which promotes rigour and transparency in the publishing of research. Articles are first checked for integrity and compliance, then published and peer-reviewed openly. Peer-review reports are made public, and articles that successfully pass review are curated into subject-specific collections. This approach combines quality assurance with openness, while also enabling post-publication review.
Launched by the European Commission in 2021 to provide beneficiaries of EU research programmes with a no-fee open access publishing platform[3], ORE was designed to make publicly funded research more transparent, accessible and sustainable through an innovative publishing model. In the five years since its launch, the platform has seen steady growth and uptake across the research community, with more than 1,200 articles published and over 6,300 authors from more than 3,000 institutions worldwide taking part.
CERN’s role in operating ORE builds on its long-standing experience in developing and maintaining open science infrastructures and community-governed services for the global research community. By hosting ORE, CERN will provide a neutral, reliable and sustainable environment, drawing on expertise gained through flagship open science initiatives such as Zenodo, Invenio and SCOAP3.
“For CERN, hosting Open Research Europe is a natural extension of our commitment to an open, community-led scientific infrastructure,” said Mar Capeáns, CERN Director for Site Operations. “The platform supports the rapid sharing of research, while reinforcing Europe’s ability to shape the future of scholarly communication.”
“Open Research Europe is a strong example of a shared commitment to fostering the free flow of knowledge across the European Research Area and beyond”, stated Marc Lemaître, Director-General for Research and Innovation (DG RTD), European Commission. “By ensuring open access to high-quality research, ORE facilitates the circulation of the latest research findings and amplifies public trust in science. Today, as European research funders and research organisations join forces to support ORE, we open a new chapter, one that strengthens open access scholarly publishing and improves research practices across Europe”.
Beyond the technical infrastructure, the initiative is expected to deepen collaboration between CERN, the European Commission, national representatives and research organisations. Working in partnership with the OPERAS Research Infrastructure, outreach and engagement activities will be expanded across Europe to attract eligible authors to the platform. ORE is expected to support a growing number of research outputs each year, making publicly funded science more accessible and transparent while setting a benchmark for equitable publishing initiatives in Europe and beyond.
More information on the future platform at: https://ore.eu
[1] https://scienceeurope.org/our-resources/action-plan-for-diamond-open-access/
[2] Austrian Science Fund (FWF), European Organization for Nuclear Research (CERN), French National Research Agency (ANR), French National Centre for Scientific Research (CNRS), German Federal Ministry for Research, Technology and Space (BMFTR), Italian Ministry of Universities and Research (MUR), Dutch Research Council (NWO), Research Council of Norway (RCN), Foundation for Science and Technology, Portugal (FCT), Slovenian Research and Innovation Agency (ARIS), Swedish research funders (Forte, Formas and the Swedish Research Council), Spanish Foundation for Science and Technology (FECYT), Spanish National Research Council (CSIC), Swiss National Science Foundation (SNSF)
[3] Current platform (operational till fall 2026): https://open-research-europe.ec.europa.eu
rodrigug Wed, 03/25/2026 - 17:22 Publication Date Thu, 03/26/2026 - 15:17
Open Research Europe (ORE), a non-profit, open access scientific publishing platform, will be hosted at CERN as of autumn 2026. Initiated by the European Commission in 2021 and supported by a consortium of national research funders from eleven CERN Member States, ORE is designed to facilitate the rapid and transparent dissemination of publicly funded research.
Originally created as a platform exclusively for research funded by Horizon 2020 and Horizon Europe, ORE will now additionally serve as a free publishing venue for any author whose national funding agency participates in the funding consortium. Following approval by the CERN Council in December 2025, CERN will provide the technical and operational infrastructure for ORE over a five-year pilot phase, while governance matters will remain with the ORE consortium.
ORE follows the publish–review–curate model, which allows research outputs to be made openly accessible after initial checks for integrity, policy compliance and eligibility, followed by transparent peer review. Reviewer reports and identities are publicly available and articles that successfully pass peer review are curated into discipline-specific collections.
CERN’s involvement builds on the Organization’s long-standing leadership in open science infrastructure. As the host, CERN will provide ORE with a neutral, reliable and sustainable operational environment, drawing on its experience in developing and operating a range of open science initiatives including Zenodo, Invenio and SCOAP³.
For the CERN community, ORE will offer an additional open access publishing option particularly suited to interdisciplinary and collaborative research that does not naturally align with established journals. Intended to be complementary to existing publishing platforms, ORE does not replace SCOAP³, which remains the primary open access route for high-energy physics publications. ORE will instead broaden the range of transparent, non-commercial publishing choices available to researchers while maintaining high standards of scientific quality and integrity.
Hosting ORE will deepen the collaboration between CERN, the European Commission and national research organisations and strengthen CERN’s strategic role in academic communication. As a trusted steward of open, community-oriented scientific infrastructure, CERN is committed to supporting open access to publicly funded research.
ehatters Wed, 03/25/2026 - 17:11 Publication Date Wed, 03/25/2026 - 17:08The top quark, the heaviest and most short-lived elementary particle known, has long been thought to decay too quickly to form bound states. However, a new result from the CMS Collaboration, presented this week at the Rencontres de Moriond conference, strengthens last year's observation that top quarks may, in fact, briefly pair up with their antimatter counterparts. This fleeting bound state – known as toponium – would be the most massive composite particle ever observed, completing the family of quark–antiquark states bound by the strong nuclear force.
Most matter around us is made of atoms, in which electrons cling to protons through the electromagnetic force. But protons themselves are not elementary. They belong to a broad family of composite particles called hadrons, in which quarks are held together by the strong nuclear force. Among them, the simplest are pairings of a quark with its own antiquark, which provide an especially clean window on the workings of the strong force. For decades, such states have been known for every type of quark but the most elusive: the top.
First discovered more than 30 years ago at the Tevatron accelerator near Chicago, the top quark has been extensively studied ever since, with experiments at the LHC going so far as to measure quantum entanglement between top quarks and antiquarks. Even when produced alongside its antiquark, the top typically decays before any bound state can form. Yet the hundreds of millions of top quark–antiquark pairs produced at the LHC, effectively making it a top-quark factory, provide such an enormous dataset that the rarest phenomena can leave a detectable trace.
The first hints of toponium appeared in searches for heavy Higgs-boson-like particles that could decay into a top quark–antiquark pair. An unexpected excess of collision events was observed at a mass close to twice the mass of the top quark, which is more characteristic of a bound state rather than a new fundamental particle. Detailed studies by the CMS and ATLAS experiments confirmed this excess using events in which both top quarks decay into leptons (electrons or muons).
The new CMS study approaches the problem from a different angle, examining events in which one top quark decays into a bottom quark, a charged lepton and a neutrino while the other decays into quarks that produce sprays, or “jets”, of particles. “Isolating the signal in this decay channel was challenging,” says Otto Hindrichs, a researcher at the University of Rochester who developed a new AI-assisted technique to reconstruct these collision events.
“Instead of reconstructing the mass of the top quark–antiquark pair directly, we focused on the relative velocity of the top quark and antiquark,” explains Yu-Heng Yu, a graduate student involved in the analysis. “If they form a bound state, their relative velocity should be much smaller than when they are produced independently,”
These new techniques proved highly effective. They resulted in the observation of an excess with a statistical significance of more than five standard deviations – the gold standard for a discovery in high-energy physics. The result provides a new, statistically independent confirmation of toponium production.
“Toponium is heavier than the heaviest known atomic nucleus, oganesson, making it the most massive bound state ever observed,” says Regina Demina, leader of the CMS group at the University of Rochester. “Its discovery deepens our understanding of the strong nuclear force and its ability to bind the fundamental constituents of matter.”
Find out more on the CMS website.
roryalex Tue, 03/24/2026 - 11:35 Byline CMS collaboration Publication Date Wed, 03/25/2026 - 11:31According to the theory of supersymmetry, there is a mirror world of hypothetical particles that could help resolve several physics puzzles, such as the surprisingly small mass of the Higgs boson and the nature of dark matter. The ATLAS Collaboration at the Large Hadron Collider (LHC) has conducted new searches for these so-called supersymmetric (SUSY) particles using machine-learning techniques. The results of these searches, presented this week at the Moriond conference, have placed some of the strongest bounds yet on the properties of SUSY particles.
Supersymmetry proposes that each particle in the Standard Model has a “superpartner”. The higgsino is the SUSY counterpart of the Higgs boson and is the subject of many SUSY searches. But detecting the higgsino, if it exists, is far from simple. The higgsino would not appear on its own but as a mixture of other SUSY particles, creating states known as neutralinos and charginos. Theorists predict that the lightest neutralino could be stable and, therefore, a strong candidate for dark matter. The other, heavier neutralinos and charginos would decay into this stable SUSY particle. However, these decays are expected to produce very little energy and the resulting low-energy particles would be extremely difficult to detect.
By deploying machine-learning techniques, the ATLAS Collaboration has been able to significantly improve the experiment’s sensitivity to low-energy particles. ATLAS now reports the results of two new searches for signs of SUSY particles in analyses of data from the LHC’s second run, which was collected between 2015 and 2018.
One of these searches involved hunting for signs of a disappearing track left by a chargino decaying into a stable neutralino, which is invisible to the detectors, and a low-energy pion. The pion follows a highly curved trajectory that is extremely difficult to identify in a busy proton–proton collision, causing the chargino’s track to “disappear”. The ATLAS Collaboration additionally searched for signs of heavier neutralinos decaying into the lightest and only stable neutralino and two low-momentum leptons, such as electrons. The researchers deployed neural networks to search deep into the low-momentum region of pions and leptons to find signs of them being produced through the decay of SUSY particles.
No signs of these SUSY particles were observed in either of these searches. However, these results have now set some of the most stringent limits yet on the masses and lifetimes of charginos and neutralinos, superseding the longstanding limits set by the Large Electron–Positron Collider, the LHC’s predecessor.
These limits help guide future searches for SUSY particles at the LHC and the High-Luminosity LHC. The search continues for the mirror world of SUSY.
roryalex Thu, 03/19/2026 - 09:25 Byline Rory Harris Publication Date Thu, 03/19/2026 - 11:23The LHCb experiment at CERN’s Large Hadron Collider (LHC) has discovered a new particle consisting of two charm quarks and one down quark, a similar structure to the familiar proton, but with two heavy charm quarks replacing the two up quarks of the proton, thus quadrupling its mass. The discovery, presented at the ongoing Moriond conference, will help physicists better understand how the strong force binds protons, neutrons and other composite particles together.
Quarks are fundamental building blocks of matter and come in six flavours: up, down, charm, strange, top and bottom. They usually combine in groups of twos and threes to form mesons and baryons, respectively. Unlike the stable proton, however, most of these mesons and baryons, which are collectively known as hadrons, are unstable and short-lived, making them a challenge to observe. Producing them requires smashing together high-energy particles in a machine such as the Large Hadron Collider (LHC). These unstable hadrons will quickly decay, but the more stable particles that are produced as a result of this decay can be detected and the properties of the original particle can therefore be deduced.
Researchers have used this approach many times to find new hadrons, and the new particle just announced by the LHCb Collaboration brings the total number of hadrons discovered by LHC experiments up to 80.
“This is the first new particle identified after the upgrades to the LHCb detector that were completed in 2023, and only the second time a baryon with two heavy quarks has been observed, the first having being observed by LHCb almost 10 years ago,” says LHCb Spokesperson Vincenzo Vagnoni. “The result will help theorists test models of quantum chromodynamics, the theory of the strong force that binds quarks into not only conventional baryons and mesons but also more exotic hadrons such as tetraquarks and pentaquarks.”
In 2017, LHCb reported the discovery of a very similar particle, which consists of two charm quarks and one up quark. This up quark is the only difference between this particle and the new one, which has a down quark in its place. Despite the similarity, the new particle has a predicted lifetime that is up to six times shorter than its counterpart, due to complex quantum effects. This makes it even more challenging to observe.
By analysing data from proton–proton collisions recorded by the LHCb detector during the third run of the LHC, the LHCb Collaboration observed the new baryon with a statistical significance of 7 sigma, well above the threshold of 5 sigma required to claim a discovery.
“This major result is a fantastic example of how LHCb’s unique capabilities play a vital role in the success of the LHC,” says Mark Thomson, CERN Director-General. “It highlights how experimental upgrades at CERN directly lead to new discoveries, setting the stage for the transformative science we expect from the High-Luminosity LHC. These achievements are only possible thanks to the exceptional performance of CERN’s accelerator complex and the teams who make it all work and to the commitment of the scientists on the LHCb experiment.”
Further information:
LHCb presentation at Moriond is available here.
LHCb news article.
“If you place a large rock in a flowing stream, you can shelter objects located just downstream. It’s much the same with crystals and a beam of particles,” explains Francesco Velotti, applied physicist in the Accelerator Systems (SY) Department. This “crystal shadowing” technique has been successfully used in the Super Proton Synchrotron (SPS) since 2021 and is now entering a new phase, with the recent installation of a refined system made of three crystals ready for testing in the SPS.
As the last injector for the Large Hadron Collider (LHC), the SPS also supplies proton beams for the North Area fixed-target experiments. Proton beams are extracted from the SPS using a process known as slow extraction. As its name suggests, slow extraction delivers the beam over long time intervals, producing extended particle pulses. This allows the beam to be spread out in space and time, a key requirement for fixed-target experiments that rely on stable and uniform particle fluxes.
But slow extraction comes with a significant challenge. Compared with fast extraction, it leads to higher beam losses, which in turn result in increased damage to accelerator components. One of the most exposed elements is the electrostatic septum, a critical device that shaves off the circulating beam from the extracted beam. Beam losses in this region are particularly problematic, as they limit accessibility for maintenance and place constraints on long-term operation.
To address this issue, a team of experts from the SY Department (SY-ABT, SY-BI and SY-STI), with contributions from the Beams (BE) Department (BE-CEM), developed and installed a crystal-based system to avoid beam losses. When inserted into the beam, the bent silicon crystals act as a protective shield for the septum through a so-called shadowing effect. The position of the crystals can be remotely adjusted according to beam conditions. This development was carried out in the framework of the DECRYCE project (DEvelopment of CRYstals for Collimation and beam Extraction), a project created in 2022 to address the full research and development cycle for crystal systems at CERN, from design and engineering of crystal benders to silicon strips, assembly of crystal systems and experimental validation.
“The principle of crystal shadowing is rooted in the precise alignment of a thin, bent crystal so that a portion of the halo particles is deflected away from sensitive components,” explains Luigi Esposito, applied physicist in the SY Department. “Detailed beam dynamics simulations have been used to design and optimise these crystal systems, and they are carefully compared with real beam measurements to validate performance and assess potential operational gains.”
“We installed the first prototype – a system made of a single silicon crystal – in the SPS in 2021. It showed a 50% beam loss reduction, both in dedicated measurement campaigns and in operational conditions, where an AI-based control system was key to ensuring reliable performance, confirming the simulations,” adds Velotti.
The full system, consisting of several aligned bent silicon crystals, was installed in the SPS in January and is now entering its operational validation phase, as the SPS just finished its beam commissioning phase.
Reducing beam losses is a critical enabler for the next generation of fixed-target experiments. With the planned increase in proton intensity required for SHiP and the High-Intensity ECN3 (HI-ECN3) project, protecting components – and thus ensuring safe, reliable long-term operation of the SPS infrastructure – will be essential.
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To learn more, read the scientific article: Demonstration of non-local crystal shadowing at the CERN SPS.
anschaef Wed, 03/11/2026 - 13:23 Byline Anaïs Schaeffer Publication Date Thu, 03/12/2026 - 08:21
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