Accelerator Report: The accelerator complex is gradually waking up from the winter shutdown

The 2026 Chamonix Workshop took place last week and brought together the accelerator and experimental communities to review the recent operational performance of the accelerator complex and discuss challenges ahead. The programme included a look back at the 2025 operation as well as an overview of this year’s final stretch of Run 3 and of the post-LS3 (Long Shutdown 3) operation. With LS3 approaching, discussions centred on the upcoming HL-LHC upgrades, as well as consolidation activities in the North Area and ISOLDE, and on the construction of the HiECN3 facility. The workshop concluded with an outlook on CERN’s longer-term future, including progress on the Future Circular Collider (FCC) project and the implications of the European Strategy for Particle Physics.

As for the current status of the accelerator complex, the transition into the 2026 run – the last year of Run 3 – is particularly rapid. Responsibility was transferred from the year-end technical stop (YETS) coordination team to the Operations Group (BE-OP) to perform the Departmental Safety Officer (DSO) tests, followed by equipment and control checks, machine checkout and, finally, beam commissioning.

The commissioning of Linac4 and the PS Booster (PSB) has progressed smoothly and according to plan. Owing to the very short YETS, little or no work was carried out on the equipment, which allowed the reuse of the 2025 machine settings. This approach proved successful and is a strong indication of the maturity and stability of the systems.

Thanks to the extensive preparation by the equipment groups and an efficient hardware commissioning phase, the PS hardware commissioning was completed in only four days. As a consequence, the PS received its first beam on 24 January, three days ahead of schedule. Most of the PS beams were recommissioned rapidly, allowing the first beam to be delivered to the first physics users of 2026: n_TOF on 2 February and the East Area on 4 February.

The H- beam has returned to ELENA on schedule, marking another important milestone in the restart of the low-energy antiproton programme. In the Antiproton Decelerator (AD), the DSO tests in the target area and the ring have just been completed. The first proton beam on the AD target is planned for 13 February, with the start of physics scheduled for 27 February.

In the SPS, DSO tests are under way to validate the machine and its safety systems, while the hardware tests across the accelerator are nearing completion. Provided that these final tests conclude as planned, the start of beam commissioning is expected for 13 February.

The LHC key passes from the Accelerator Coordination and Engineering Group in the Engineering Department (EN-ACE), on the left, to the Operations Group in the Beams Department (BE-OP), after completion of the DSO tests – always a symbolic moment at the end of a YETS. (Image: CERN)

Meanwhile, on the LHC side, DSO tests were successfully carried out on 6 February, marking the shift of responsibility from the YETS coordination team to the operators for the last machine of the complex. Over the coming two weeks, more than 1600 superconducting circuits will be progressively tested up to their nominal currents, corresponding to operation at 6.8 TeV.

Once this extensive powering campaign is completed, only the machine checkout phase will remain between the end of the YETS and the arrival of beam. During machine checkout, all accelerator systems are tested together to verify the overall readiness of the technical infrastructure, before beam injection and circulation can begin (planned for 21 March).

With the injector chain performing strongly and the LHC restart advancing according to plan, the accelerator complex is steadily waking up from the YETS and moving towards the start of the 2026 physics programme. The coming weeks will be decisive as commissioning activities continue across the complex.

anschaef Wed, 02/11/2026 - 11:07 Byline Matteo Solfaroli, Deputy Leader of the Operations Group (BE-OP) Publication Date Thu, 02/12/2026 - 08:03

Celebrating Women in Science Day 2026 at CERN

Every year, on 11 February, CERN celebrates the International Day of Women and Girls in Science. In an effort to amplify diverse voices in STEM, six women scientists from CERN open up about their careers and the lessons they hope to pass on to the next generation.

Francesca is an Italian biomedical engineer pursuing her PhD at CERN, working in the robotics team of the Beams Department. She’s currently working on the MARCHESE project, in affiliation with Campus Bio-Medico University of Rome, focusing on contactless monitoring of physiological parameters. Despite choosing a scientific career and often volunteering in scientific outreach initiatives, Francesca continues to nurture her passion for the humanities and arts. “I firmly believe that collaboration and inclusion are the right paths to improve the world together. I’m driven by a strong curiosity about everything around me.”

Berare is a Turkish experimental physicist who worked with the ATLAS experiment during her MSc and PhD on searches for physics beyond the Standard Model. During her PhD, she became a Support Scientist for the Beamline for Schools (BL4S) competition, which marked the beginning of her journey combining research with science communication. She now works for both BL4S and ELISA, the mini proton accelerator at CERN’s Science Gateway. She fondly remembers the moment when the BL4S 2022 winners arrived at the experimental zone: “I felt incredibly lucky to share my passion with young, curious and really passionate people. We spent two weeks of beam time together watching their ideas turn into reality. All the intricate details of running an experiment, we accomplished them as a team.”

Mia is a Canadian research fellow in the Accelerator Systems Department, working on beam developments for fundamental physics with radioactive molecules. Mia pursued a bachelor’s degree in mechanical engineering before moving to Vancouver for a master’s degree in engineering physics. Her interest in radioactive ion beam production brought her to CERN, where she studied actinide beams for three years as a PhD student in the Marie Curie European Training network “LISA” (Laser Ionisation and Spectroscopy of Actinides) at ISOLDE – a facility at CERN where scientists study the properties of atomic nuclei, with further applications in fundamental studies, astrophysics, and material and life sciences.

Laura is a German mechanical engineer at CERN working on research and development to produce cavities for future accelerators. She studied mechanical and aerospace engineering at the Technical University of Munich. She joined CERN four years ago as a technical student for her master’s thesis and continued as a fellow working on collimators. Laura says that “as a child, I took part in girls’ day initiatives, which sparked my fascination for astrophysics and engineering. Later, it felt natural for me to give something back by organising workshops for young students to make STEM seem less intimidating and more accessible.” She particularly enjoys being close to the CERN Main Workshop and understanding how design ideas become real components.

Paraskevi is a Greek physicist working at CERN’s HiRadMat (High-Radiation to Materials) facility, designed to deliver high-intensity beams to an irradiation area where material samples, as well as accelerator component assemblies, can be tested. She studied physics at NKUA, specialising in nuclear and particle physics, and is now pursuing her PhD at HiRadMat in collaboration with the University of Liverpool, studying novel materials for high-intensity beam diagnostics. “Continuous learning is one of my biggest motivators, and I am looking forward to exploring the limits of our knowledge on beam-material interactions,” says Paraskevi.

Silvia is a Spanish physicist and deputy project manager for the Muon Drift Tube of the CMS detector, a general-purpose detector at the Large Hadron Collider (LHC). She started her career at CERN more than 20 years ago as a technical student, working on prototypes of the first dipoles for the LHC. “My first motivation came in high school, from my teacher,” says Silvia about what made her pursue a career in STEM. “My favourite part about my job is learning. You can learn something new every day.”

In parallel to this initiative, like every year since 2017, from 2 to 6 February 66 women scientists and engineers visited schools in Geneva, Switzerland, and in the Haute-Savoie and Ain regions of France to meet with students. Organised in collaboration with CERN, the University of Geneva, EPFL, LAPP and LAPTh, this event allowed more than 4200 students between 6 and 17 years old to meet a woman scientist, discuss their profession and career path, ask questions and participate in classroom activities.

anschaef Tue, 02/10/2026 - 12:48 Byline Bianca Moisa Publication Date Wed, 02/11/2026 - 08:46

Computer Security: A final spurt for improved networking

The past two years have brought a lot of new computer-security deployments at CERN. Spurred on by the 2023 cybersecurity audit, a lot has already been achieved and 2026 should see the successful implementation of all remaining work packages. We already discussed mandatory requirements for IT service managers and upcoming changes to password policies and improvements to two-factor authentication in the last two issues of the Bulletin. Finally, let’s focus on networking in this one.

2026 will also bring improved and more granular network filtering to the Technical Network (TN) and, later, between the Campus and data centre networks, introducing a pair of redundant firewalls for each. Today’s filtering between the Campus network, the Meyrin and Prévessin data centres and the TN is based on tuples of IP addresses and, in some rare cases, network service (“port numbers”). This “TRUSTED/EXPOSED” mechanism dates back to before 2006, when no filtering between those network domains was deployed at all. Today, that filtering is deemed too coarse as it either broadly “trusts” particular enumerated devices on the Campus or in the data centres and makes those visible to the whole TN, or exposes certain enumerated devices from the TN to all the other networks. With the upcoming TN firewall, such cross-traffic from the TN to the data centres and the Campus network will be identified and controlled in a more fine-grained manner: Which IT services need to be visible to the TN? Using which network ports? In which direction (incoming or outgoing)? Using which transport protocol (TCP? UDP?)? And who are its clients on the TN? The same holds true for devices connected to the TN: Where do they need to expose their data to and how? With the TN firewall hardware deployed before Long Shutdown 3 (LS3), the major task will be to answer those questions and migrate from the current “TRUSTED/EXPOSED” mechanism to the more fine-grained firewall protection rules during LS3. And once we are done with that, an identical firewall will be deployed between the Campus network and the data centres.

In parallel, and linked to more “domestic” matters, all IT services hosted in the Meyrin or Prévessin data centres will consider deploying Openstack’s “Security Groups” once this feature is available. “Security Groups” will allow the service to separate their internal back-end servers from the user-facing front-ends and to better protect those from any other data centre services. At the time of writing, all virtual machines in the “m4” family are eligible, with other types expected to join in 2026–2027. And remember, in the Prévessin data centre this functionality is already in place and ready to be put to good use. Similarly, certain control systems, like those for building automation, will be subjected to better network protection (VLANs) as we have done for the CCTV cameras and general access control systems and printers in 2025.

More generally, 2026 should usher in an encrypted Wi-Fi network using industry-standard WPA protection. While this does not provide end-to-end encryption of your traffic, it secures your traffic from network snooping and protects the CERN network from connections by unauthorised devices. WPA roll-out is planned for early 2026, with a long transition from the old network (“CERN” SSID) to the new one (“CERN-Campus”) such that no device is left behind.

So, thanks a lot helping secure CERN if you are involved with the TN and Campus firewalls or “Security Groups”. The TN admins and Computer Security Office, respectively, will surely reach out to you. And for the upcoming WPA3 Wi-Fi deployment: Just. Try. It. Out. It’s an easy step towards obtaining the best privacy for your communication while further protecting the Organization.

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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 Tue, 02/10/2026 - 12:29 Byline Computer Security Office Publication Date Tue, 02/10/2026 - 12:28

Groundbreaking CMS calorimeter for the High-Luminosity LHC Scientists from all over the world are contributing to the first complete prototype of a wedge-shaped slice of the new CMS endcap calorimeter. This slice, known as a “cassette”, is being constructed in a clean room at the CMS experiment site in Cessy, France. (Image: N. Stathaki, CERN)

In beehives on the CERN site, a buzzing team of bees collaborates to build hexagon after hexagon of honeycomb – a shape that allows the most honey for a given amount of beeswax to be stored. Working nearby, a team of similarly committed scientists has recently pieced together some more high-tech hexagons to form the first prototype “cassette” for the new CMS endcap calorimeters.

These cassettes are the wedge-shaped building blocks of the CMS High-Granularity Calorimeters (HGCALs) which, when complete, will be the largest silicon-based detectors ever built. The two endcaps will be placed on either side of CMS to replace the experiment’s existing endcaps ready for the High-Luminosity LHC (HL-LHC), which is due to start operating in 2030.

As HGCAL physicist Dimitra Tsionou from National Taiwan University explains, the new calorimeter represents a significant advancement in detection technology. “HGCAL is effectively a 5D calorimeter: it performs 3D spatial reconstruction, energy reconstruction, and has very high timing resolution”.

This technology will allow HGCAL to handle the dramatic increase in the number of particles that the HL-LHC will deliver. As well as helping physicists to observe more rare processes, the higher luminosity provided by the HL-LHC will result in 4 to 5 times more simultaneous particle collisions than occur with the existing LHC. 40 million times each second, 140–200 collisions are expected to occur simultaneously, far more than the existing CMS endcaps are capable of measuring.

In addition, the endcaps will need to withstand the higher levels of radiation to which they will be subjected due to the increased number of collisions. HGCAL will not only handle these much harsher conditions but will also match the energy resolution, improve the particle identification and enhance the triggering performance of the existing endcaps.

HGCAL physicist Dimitra Tsionou placing a hexagonal module on a large copper cooling plate, using a vacuum support tool to avoid physical damage. Each module consists of a hexagonal silicon sensor sandwiched between a high-density copper-tungsten alloy baseplate and a printed circuit board. These modules come from six different module assembly centres: IHEP in Beijing, NTU in Taipei, TIFR in Mumbai, UCSB in Santa Barbara, CMU in Pittsburgh and TTU in Texas. (Image: CERN)

When particles collide, other particles are produced, many of which will enter the endcaps to be detected by HGCAL. Although the collisions will be simultaneous, they will occur up to 10 cm away from each other, so the particles they produce will reach the endcaps about ten trillionths of a second apart. HGCAL will measure the timing of each particle – the difference between when it arrives in the detector and the moment of the collision – with the exceptional corresponding level of precision.

For the calorimeter to trace the paths of these particles back to the collision they came from, HGCAL needs to have a high density of sensors, the ‘high granularity’ from which its name derives. Each cassette is covered with sensors that will record the energy, position and timing of the particles passing through the 47 layers of the detector.

CERN will construct the 26 layers closest to the collision point, which will form the electromagnetic section and detect electrons and photons. In parallel, Fermilab will construct the 21 layers furthest from the collision point to form the hadronic section that will measure particles like protons and neutrons. A full endcap will have a total active sensor area of about 500 square metres – almost the size of two tennis courts – and will contain more than 3 million detector channels.

The first 26 layers of each endcap will form the electromagnetic section, made entirely from silicon modules assembled into double-sided cassettes. 6 cassettes are required to form two layers of a complete circle, and all 156 cassettes needed for the full section will be assembled and tested at CERN. These cassettes will then be covered with a steel-clad lead “absorber”, which will produce showers of secondary particles when hit by particles originating in the initial collisions. (Video: Karol Rapacz, CMS) 

“It’s very ambitious”, explained HGCAL physicist and logistics manager Ludivine Ceard from National Taiwan University. “It's the first time that a detector using this technology will be built on this scale and have to operate in such tough conditions.”

When Fermilab has constructed and tested the hadronic cassettes, they will be shipped to CERN and inserted into steel structures, the first of which was produced in Pakistan and is currently being re-assembled at CERN. An electromagnetic section will then be joined to a hadronic section to form a full HGCAL endcap.

Once both HGCAL sections are complete, the electromagnetic section will be placed on top of the hadronic section to form a full calorimeter. (Video: Karol Rapacz, CMS)

“There’s so many challenging aspects”, emphasised Ceard, but she added that these challenges are definitely worth it as far as the team is concerned. “HGCAL is really special, the first of its kind”.

(Video: CMS, CERN)

 

ehatters Thu, 01/29/2026 - 11:15 Byline Emma Hattersley Publication Date Thu, 01/29/2026 - 10:48

Accelerator Report: Run 3 operations counting down to LS3

With accelerator operations for 2025 having ended on 8 December and the Linac4 source restarting already on 5 January, this year’s transition felt particularly short. While there was formally a year-end technical stop (YETS), accelerator activity resumed almost immediately, leaving little sense of a real pause. Nevertheless, many teams made effective use of the short stop, carrying out essential maintenance and selected improvement activities, as outlined in the previous report.

As every year, the CERN accelerator complex is restarting in a carefully sequenced manner, from the Linac4 source through the accelerator complex all the way up to the LHC, together with the attached experimental facilities. Once responsibility is handed over from shutdown coordination to the operations teams, each accelerator follows its established restart sequence: DSO (Departmental Safety Officer) tests to verify the integrity of the safety systems, equipment and control checks, machine checkout, and finally beam commissioning to prepare the beams required for the downstream machines and users.

As can be seen in figure 1, Linac4 and the PS Booster have already completed their standalone beam commissioning successfully and have handed over the baton to the PS. The East Area and the SPS are following closely behind. According to the current schedule, the 2026 physics programme will begin on 5 February with n_TOF, followed by the East Area on 11 February.

Figure 1: Restart sequence of the LHC injector chain. Red bars correspond to hardware commissioning periods, whereas yellow marks beam commissioning periods. The blue background indicates the start of the operational period, with the first physics user coming online. (Image: CERN)

For the LHC (see figure 2), DSO tests are scheduled for the end of next week, followed by around two weeks of hardware recommissioning and machine checkout. This year, the restart falls during the February holiday period, rather than the “notorious” Easter timeframe of previous years, illustrating the squeezed schedule.

Figure 2: LHC restart sequence. Hardware commissioning is due to start on 7 February, and first collisions with 1200 bunches are expected for 16 March, following beam commissioning and intensity ramp-up. (Image: CERN)

Operations in 2026 will bring the Run 3 period to its conclusion, ahead of the upcoming Long Shutdown 3 (LS3). While LS2 focused primarily on the LHC Injector Upgrade (LIU) programme, LS3 will be dedicated to the High-Luminosity LHC (HL-LHC) upgrade, alongside several major projects such as the North Area consolidation, ISOLDE improvements and preparations for AWAKE Run 2c.

Although the official Run 3 target for the LHC of 500 fb⁻¹ of integrated luminosity was already reached by the end of last year, the LHC physics programme continues until 29 June 2026, with ongoing efforts to maximise physics output until the very end of the run. The injector chain will continue delivering proton and ion beams until the injectors’ own shutdowns for LS3, which will start on 31 August 2026.

Next week, the annual Chamonix workshop will take place from Monday to Thursday. Discussions will focus on the end of Run 3, preparations for LS3, the staged restart of Run 4 and a broader outlook on CERN’s future projects.

Challenging months lie ahead as Run 3 draws to a close and preparations for the next phase intensify – stay tuned!

anschaef Wed, 01/28/2026 - 12:38 Byline Bettina Mikulec, Leader of the Operations Group (BE-OP) Publication Date Thu, 01/29/2026 - 09:33

Presidential visits to CERN Gitanas Nausėda, President of the Republic of Lithuania (left), and Diana Nausėdienė, First Lady of the Republic of Lithuania (right), visiting the LHC tunnel with CERN Director-General Mark Thomson (centre). (Image: CERN)

On 19 January, CERN welcomed Gitanas Nausėda, President of the Republic of Lithuania. The President was received at Point 5 of the LHC (CMS experiment), in Cessy (France), by the Representative of the French Republic, Joël Bourgeot, as well as CERN’s Director-General, Mark Thomson, the Director for Accelerators and Technology, Oliver Brüning, the Director for Research and Computing, Gautier Hamel de Monchenault, the Director for Stakeholder Relations, Ursula Bassler, the Director for Finance and Human Resources, Jan-Paul Brouwer, the Director for Site Operations, Mar Capeáns, the Chief Information Officer, Enrica Porcari, and the Adviser for Relations with Associate Member States, Christoph Schäfer.

Following a general introduction to CERN’s activities, Lithuania’s President visited the CMS experimental cavern as well as the LHC tunnel. After the visit, the delegation travelled to CERN Science Gateway, where President Nausėda met members of the Lithuanian community working at CERN.

In the afternoon, a CERN–Lithuania Science and Innovation event took place, where CERN and several Lithuanian companies signed a Research and Development Agreement related to the Future Circular Collider Feasibility Study.

Vahagn Khachaturyan, President of the Republic of Armenia (centre), in the ATLAS experimental cavern with ATLAS Collaboration Spokesperson Stéphane Willocq (left) and CERN Director-General Mark Thomson (right). (Image: CERN)

Later that day, CERN also welcomed Vahagn Khachaturyan, President of the Republic of Armenia. The President and his delegation were received at Point 1 of the LHC (ATLAS experiment) by CERN’s Director-General, Mark Thomson, the Director for Research and Computing, Gautier Hamel de Monchenault, the Director for Stakeholder Relations, Ursula Bassler, the Adviser for Relations with Non-Member States, Salvatore Mele, and the Adviser for Relations with Associate Member States, Christoph Schäfer.

Following a general presentation of CERN’s activities, Armenia’s President visited the ATLAS control room and experimental cavern. He was also introduced to members of the Armenian community at CERN and met Armenian teachers participating in the Armenian Teacher Programme at CERN.

anschaef Wed, 01/28/2026 - 11:30 Byline Anaïs Schaeffer Publication Date Wed, 01/28/2026 - 11:26

Computer Security: A final dash to protect your account

The past two years have brought a lot of new computer-security deployments at CERN. Spurred on by the 2023 cybersecurity audit, a lot has already been achieved and 2026 should see the successful implementation of all remaining work packages. We already discussed mandatory requirements for IT service managers in a past issue of the Bulletin. This time we present upcoming changes to passwords and improvements to two-factor authentication, while the focus will be on networking in a future article.

Very early 2026 should bring an evolution of CERN’s password policy. The audit deemed that eight characters, even if a combination of lower-case and capital letters, symbols and numbers, are too few. Following best practice, like that of the NIST 800-63b standard, the CERN Computing Rules require a minimum length of 15 characters, making passwords “passphrases”. That is a lot to memorise. But it is also a lot more secure and harder to crack. And since the need for letter/number/symbol complexity has been dropped, any kind of sentence – the passphrase − would do. Gone are the days of “B055man69”, “Joshua”, “SamFox99” or “a^2+b**2=sqr(c)”. “Last Christmas”, “Strangers in the night” or “Boom Boom Pow” are the new way to go.

At the same time, and still linked to “accounts”, the Computer Security Office will conclude a penetration test conducted by an external company against CERN’s Active Directory (AD) – the holy grail of all computer knowledge at CERN and the usual and obvious target for any ransomware attack. With the AD lost, CERN’s IT systems would be considered to be fully, deeply and entirely compromised. With tremendous cost. Thus, it is imperative to review the current AD’s settings, poke for any possible weaknesses, identify potential vulnerabilities and get them subsequently and swiftly fixed before they can be exploited.

The first quarter of 2026 should also see the termination of the roll-out of two-factor authentication (2FA) to the Organization. While 2FA was deployed to the CERN Single Sign-On in 2023 and 2024, it was activated on the CERN Windows Terminal Services and LXPLUS interactive Linux service for remote desktop (RDP) and SSH access only last September. While this process went generally smoothly, the non-persistence of RDP and SSH connections, i.e. the loss of the RDP/SSH session once the Wi-Fi connection is lost or the laptop is put in sleep mode, is still an issue requiring further improvement. But for that we need your feedback. On our side, however, the game changer should arrive before Easter 2026 with the establishment of a new VPN service. Terminated in 2007 because CERN’s brilliant internet connectivity then also channelled all private/home traffic through CERN, posing a risk to the end users’ privacy and CERN’s reputation, CERN’s VPN service will be resurrected with better functionality* and, this time, a split tunnel configuration so that only traffic towards CERN can get through.

Stay tuned for these changes, hopefully to your benefit and making your (remote) life easier. And check out the next article on sprinting to the networking finish line.

 

*Linux, MacOS and Windows clients are supported, as is the “WireGuard UDP” protocol. Android and iOS users should also be able to connect, but due to the cacophony of possible clients, they cannot be supported centrally.

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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 Tue, 01/27/2026 - 12:29 Byline Computer Security Office Publication Date Tue, 01/27/2026 - 12:24

European labs get aligned at CERN

Uncertainty is inherent to the scientific process. The measurements that scientists make are only as good as the tools they use to make them. Taking uncertainty into account is part of everyday life for all scientists at CERN, but it is especially important when measuring the dimensions of accelerator and detector components. However, in the world of metrology, the science of measurement, not all laboratories agree on how uncertain they should be.

This is why, over the past few months, eleven laboratories from across Europe have come to CERN to make extremely precise measurements of the same sample object, a silicon carbide girder. By comparing their results, they will be able to come to an agreement on how to determine the uncertainty in their measurements. Many factors influence measurement uncertainty, including the measurement method used, the skills of the operators and the environment in which the measurement is taken.

Precision measurements are extremely important for accelerator laboratories, and CERN is no exception. The Large Hadron Collider (LHC) uses magnets to accelerate beams of protons and direct them onto a collision course. Extreme precision is needed to make this possible given that the components must be aligned with a tolerance of 150 microns over 200 metres. That is a margin of error equivalent to the thickness of a single sheet of paper. The concept of alignment precision is often interpreted inconsistently, and this can lead to unrealistic tolerances that can potentially have a significant negative impact on accelerator performance.

With the High-Luminosity LHC (HL-LHC) and potentially the FCC on the horizon, there are increasing demands for even higher precision. Many other accelerator laboratories are experiencing similar increases in precision requirements.

“We are all looking to become more and more precise and accurate and we are all hitting our limits,” said Patrick Bestmann, a surveying engineer at CERN. “The main issue is that, if somebody asks you how precisely you can do something, a multitude of answers are all correct, depending on the definition.”

For this reason, engineers at a number of European laboratories have organised what is officially called an interlaboratory comparison (ILC), a process recognised by the International Organization for Standardization to help laboratories to ensure measurement consistency and identify potential errors or biases. For this particular ILC, the laboratories all measured a silicon carbide girder, which was built as a prototype for CERN’s proposed Compact Linear Collider.

Now that all the laboratories have completed their measurements of the girder, they will submit them along with their uncertainties. The data will then be compared statistically to identify any outliers.

“It’s not about assigning blame or criticism, but about awareness. If someone regularly overestimates their uncertainty, they need to know, and the same is true if they underestimate it”, said Bestmann.

The laboratories hope to publish the results and present their findings in 2026 in a peer-reviewed paper. Going forward, all the participating laboratories can be sure that, when it comes to uncertainties, they will all be aligned, just like their accelerators.

roryalex Mon, 01/26/2026 - 15:16 Byline Rory Harris Publication Date Mon, 01/26/2026 - 15:15

Heating homes with the world’s largest particle accelerator The 27-km LHC has eight surface points. Point 8, home of the LHCb experiment, is located close to the French town of Ferney-Voltaire. (Image: CERN)

What if the world’s largest particle accelerator could also heat homes? CERN’s Large Hadron Collider (LHC) is doing just that, thanks to a new heat exchange system. Since mid-January, heat recovered from the LHC has been supplying a heating network for a new residential and commercial area in the nearby French town of Ferney-Voltaire. This network, inaugurated on 12 December, is expected to supply the equivalent of several thousand homes. By avoiding traditional energy sources, such as gas, the network prevents the emission of thousands of tonnes of CO2.

This building houses the connection between CERN's heat exchange system and the heating system for the new commercial and residential area of Ferney-Voltaire. (Image: Nicolas Gascard/Pays de Gex Agglo)

The 27-km LHC has eight surface points and Point 8 is located close to Ferney-Voltaire. The installations at Point 8, particularly the cryogenics, need to be cooled with water. As water circulates through the equipment, the equipment cools and the water heats up. “Typically, hot water would then pass through a cooling tower, releasing heat into the atmosphere so that the cooled water could be reinjected into the equipment,” explains CERN’s energy coordinator, Nicolas Bellegarde. “In the new set-up, hot water initially passes through two 5-MW heat exchangers, which transfer thermal energy to the new heating network in Ferney-Voltaire.”

As one of the new network’s heat sources, CERN provides heat whenever possible, as long as it does not impact its activities. At present, Ferney-Voltaire is only using up to 5 MW from CERN but, with two heat exchangers in the system, this could theoretically be doubled, especially when CERN’s accelerators are fully operational. In summer 2026, CERN will stop the LHC for several years of maintenance and upgrades, known as Long Shutdown 3 (LS3), to prepare for the upcoming High-Luminosity LHC. Some Point 8 installations will continue to be cooled, enabling CERN to supply between 1 and 5 MW to the network during LS3, with the exception of a total of five months spread over this multi-year period.

One of the two 5-MW heat exchangers at LHC Point 8 (Image: CERN)

Driven by a commitment to environmentally responsible research, CERN has implemented many initiatives to help reduce the impact of its activities on the environment. Energy recovery is a key part of CERN’s energy management strategy, in line with ISO 50001 requirements, alongside keeping energy consumption to a minimum and improving energy efficiency. Other projects include CERN’s Prévessin Data Centre, inaugurated in 2024, which is equipped with a heat-recovery system set to warm most site buildings from winter 2026/2027, and the future recovery of heat from LHC Point 1 cooling towers to supply buildings on CERN’s Meyrin site. Together, these initiatives will save 25–30 GWh per year as of 2027, marking significant progress in CERN’s responsible energy management.

katebrad Mon, 01/26/2026 - 09:48 Byline Kate Kahle Anna Cook Publication Date Wed, 01/28/2026 - 15:23