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CLEAR study paves the way for novel electron-based cancer therapy

Thu, 10/06/2021 - 11:30
CLEAR study paves the way for novel electron-based cancer therapy Thomas Hortala thortala Thu, 06/10/2021 - 10:30

There are some cancer tumours that not even surgery, chemotherapy or traditional radiation therapy can cure. These resistant tumours contribute to making the disease one of the main causes of mortality worldwide, but the scientific community is teeming with ideas to make cancer fatalities a thing of the past. Among the latest medical and technological innovations, progress in particle therapy – the process of irradiating tumours using highly energetic particle beams generated by a particle accelerator – allows the treatment of tumours that would otherwise have been fatal.

More than 10 000 small electron linear accelerators (linacs) are currently used for cancer treatment worldwide. Most of these machines rely on photon beams generated by electrons to irradiate their target. Some, however, use the electron beam itself for direct low-energy electron irradiation, although this can only reach superficial tumours. These methods differ from hadron therapy, a technique based on irradiation with protons or heavy ion beams.

A possible complement to hadron and low-energy electron therapy is the use of high-energy electron beams within the 50-200 MeV range, which can penetrate deep into tissues. However, this technique is rarely used due to the higher cost and larger size of the accelerator needed to produce them compared to photon facilities. In addition, their depth profile is less well defined than that achieved with hadron beams. Recent developments in high-gradient acceleration for compact linear accelerators, mainly driven by the CLIC study at CERN, have started to change the story.

A recent finding might constitute a further step towards the use of high-energy electron beams. Two studies involving the universities of Strathclyde and Manchester were carried out at CERN’s linear electron accelerator for research (CLEAR), a test facility that serves research and development efforts on accelerator technology. Researchers tested a new irradiation technique involving very high-energy electron (VHEE) beams focused on a small, dense spot. By focusing a VHEE beam with a large aperture electromagnetic lens, they established that the particles could travel several centimetres deep into a water phantom (a large bucket of water used for studies on radiation) without significant scattering – that is, while remaining focused on a well-defined, targeted volume. Such a beam could thus theoretically be used to treat deep-seated cancerous cells with limited harm to the surrounding tissues.

This is promising news for the medical technology community for a variety of reasons: VHEE beams produced by compact linacs in clinical settings would not only offer a more cost-effective alternative to other particle beam therapies but would also provide doctors with a highly reliable medium, as their scattering in inhomogeneous tissue is limited. These factors could drastically expand the pool of patients eligible for electron therapy. Additionally, VHEE beams would be compatible with FLASH radiotherapy, a technique for delivering highly energetic particles to tissues almost instantaneously (in less than a second). CERN and the Lausanne University Hospital (CHUV) recently joined forces with the aim of building a high-energy clinical facility for FLASH therapy, with preliminary tests to be conducted at the CLEAR facility.

The ultra-focused VHEE beam is the direct fruit of advances in linear acceleration technology achieved by the CLIC study at CERN. It attests to the relevance of this field of research not only for particle physics but for society as a whole. Although VHEE beams require more research before practical applications in a clinical setting are found, the CLEAR results contribute to widening the field of possibilities for cancer treatment.

CERN’s Year of Environmental Awareness

Wed, 09/06/2021 - 11:11
CERN’s Year of Environmental Awareness thortala Wed, 06/09/2021 - 10:11

On 5 June, the world celebrated World Environment Day, a day established by the United Nations to raise awareness and encourage action towards the protection of the environment worldwide. To mark this day, CERN is launching a series of articles, entitled “CERN’s Year of Environmental Awareness”, presenting the environmental challenges facing the Organization and its efforts to tackle them. The articles on environmental protection and sustainability will be complemented by infographics providing data on CERN’s environmental initiatives, as well as tips and suggestions that each and every one of us can follow to improve CERN’s environmental footprint. Throughout the Year of Environmental Awareness, activities will be proposed to encourage the CERN community to contribute to environmental protection.

The topics covered in this series of articles stem from the CERN Environment Report 2017-2018, published last year, and its upcoming update covering 2019 and 2020. The report is aligned with the internationally recognised Global Reporting Initiative Standards. In accordance with these standards, CERN identified and prioritised environmental topics of significance to the Organization (following a methodology based on the principle of materiality). The identification of topics and the prioritisation process began with focus group meetings with internal stakeholders representing various technical, administrative and managerial functions at CERN, ranging from users to staff representatives to Council members. They were asked to express their views about important environmental topics and to prioritise them. Based on the insights from these meetings, CERN identified and interviewed external stakeholders, such as Host State representatives, to establish the relative importance of the identified topics.

This process revealed various perspectives and highlighted a range of environmental concerns and opportunities for CERN. A list of topics deemed to be of material importance in the CERN context was then drawn up. This list included energy, emissions, ionising radiation, waste, water and effluents, noise and biodiversity. Environmental compliance in relation to these topics was also included in the CERN Environment Report 2017-2018. In addition, CERN’s knowledge and technology transfer work was identified as an activity that could have a positive impact on the environment.

CERN’s Year of Environmental Awareness will be officially launched by the Director-General at an online event on 24 June. The event, involving representatives from the Host States, will feature presentations on environmental subjects and a round-table discussion. You are also invited to discuss and share your ideas on environmental topics at CERN via a dedicated Mattermost channel.


This article is a part of the series “CERN’s Year of Environmental Awareness”.

Sparking breakthroughs in radiation protection for spacecraft, aviation and accelerators

Tue, 08/06/2021 - 17:43
Sparking breakthroughs in radiation protection for spacecraft, aviation and accelerators Thomas Hortala thortala Tue, 06/08/2021 - 16:43 Electronics on spacecraft, aircraft, accelerators and ground transportation were targeted by the EU-funded project (Image: RADSAGA)

With the proliferation of space missions around the globe and technological leaps allowing the development of ever more sophisticated components, there is good reason to be excited about humanity’s next steps into the unknown. However, many systems relying on complex and fragile electronics – be they in space or underground, like CERN’s accelerators – have to contend with a very specific Achilles heel: radiation damage. Damage from high-energy radiation is, notably, one of the main engineering challenges encountered when developing equipment for the High-Luminosity LHC. That’s why CERN and the European Union teamed up for the RADSAGA project (RADiation and Reliability Challenges for Electronics used in Space, Aviation, Ground and Accelerators), which has brought laboratories, radiation test facilities, universities and industry together around the issue of radiation protection for electronics. As the project reaches its end after more than four fruitful years, the time has come to take stock.

Spacecraft and accelerators share a common denominator: the harsh radiation environment to which their hardware is exposed, featuring either cosmic rays or secondary particles released from collisions. But fragile electronics on Earth can also suffer from the radiation that abounds on its surface. Consequently, RADSAGA’s young early-stage researchers focused on improving the radiation hardness of spacecraft, aviation and accelerator components, and of communication and transportation equipment on Earth. Their research was guided by the need to conduct systematic radiation hardness tests on commercially available, off-the-shelf components that are increasingly used in the space industry, as well as the need to adopt a new testing approach, focusing on systems and sub-systems instead of individual components. To achieve their goal, the RADSAGA teams made the most of the many radiation facilities scattered across Europe, including CERN’s.  

The essential first step in this endeavour was to carry out a thorough review and characterisation of the particle beams used to qualify commercially available electronic components. Indeed, a deep understanding of the relevant parameters (particle flux, energy spectra, beam size, etc.) of the beams offered by the test facilities allows industry to make informed decisions about which facility to use to test a specific component. In parallel, the RADSAGA experts pursued the development of state-of-the-art electronic components of strategic importance and with a tolerance to radiation that is orders of magnitude higher than what can be found on the market. This was successfully achieved with, for instance, the CMOS sensor, an image sensor that serves as the “electronic eye” of many devices.

Equally crucial were studies conducted of the system tests that are used to gauge the radiation hardness of whole devices as opposed to individual component characterisations, which are the current norm despite being more costly. Shifting test practices in industry from component-level qualifications to system tests could result in economies of scale and greater time efficiency. Finally, the RADSAGA experts developed guidelines for radiation testing and verification of radiation-tolerant space equipment and small satellites based on commercial electronics. The guidelines, which are intended to serve as a basis for a new European radiation testing standard for systems, are already a key reference for engineers across Europe.

The RADSAGA project’s many findings on the issue of radiation effects on electronics have equipped the European industry and laboratories like CERN with a solid base upon which to build their own radiation protection strategies. But the story doesn’t end there: the success of RADSAGA has sparked the creation of two more EU-financed projects: RADMEP (the European Joint Master in Radiation and its Effects on Microelectronics and Photonics Technologies) and RADNEXT (a project offering transnational access to a large network of radiation facilities).

While RADMEP and RADNEXT are still in the kick-off phase, you are warmly invited to browse the many scientific papers published by RADSAGA.

Greening gaseous detectors

Tue, 08/06/2021 - 16:16
Greening gaseous detectors Mark Rayner thortala Tue, 06/08/2021 - 15:16

When charged high-energy particles crash past noble-gas molecules, they leave a trail of ionisation in their wake. These tiny signals can be amplified using electric fields, and read out by electronics, revealing particle tracks with beautiful precision. This is the time-honoured concept behind the LHC’s gaseous detectors – an indispensable concept, thanks to its ability to instrument large volumes of a detector in an affordable way.

Unfortunately, environmentally harmful chlorofluorocarbons known as freons also play an essential role, dampening runaway effects to make sure that the amplified signals aren’t swallowed up by electronics noise. Physicists at the LHC are working on consolidating strategies for eliminating the current risks, and are studying novel “eco-gases” for the next generation of detectors. These were the topics of the workshop recently hosted online by CERN. To read more, check out the full report in the CERN Courier magazine.

The High-Luminosity LHC project takes shape at Point 1

Tue, 08/06/2021 - 15:21
The High-Luminosity LHC project takes shape at Point 1 Thomas Hortala thortala Tue, 06/08/2021 - 14:21

With the pure whiteness of its walls, its impeccable cleanliness and its alternating white and blue lights, the new High-Luminosity LHC (HL-LHC) cavern, situated at Point 1 near the ATLAS detector at around 80 metres below ground, could easily pass for a medical facility. However, “it won’t stay that way for long,” smiles Oliver Brüning, HL-LHC project leader: the empty cavern and 300-metre-long service tunnel will soon experience the clutter and bustle of the installation of its technical infrastructure and, further in the future, of the equipment fitting out the upgraded LHC.

Along with a similar underground complex at Point 5 (close to CMS), which is still under construction, this cavern and gallery are the keystone upon which much of the HL-LHC strategy rests. Indeed, the structure presents a comprehensive solution to the challenges posed by the future accelerator – namely, increased radiation damage to components due to the higher number of collisions, greater losses in magnet refrigeration and storage issues in the tight LHC tunnel, which cannot house all of the cutting-edge equipment needed to improve its performance. These pieces include superconducting links, cold compressors for the triplet quadrupole magnets, a variety of cooling magnet protection systems and the power generation for the new crab cavity SRF system. They will be moved to the new cavern, alongside all of the new and old power converters of the LHC, during Long Shutdown 3.

Ever since the decision to build the caverns was made in 2015, the teams responsible for the civil engineering works (primarily the Civil Engineering group within SCE, although the project involves groups from all across the Organization) haven’t lost a second: concerned by the disturbances that the heavy drilling works could cause in the LHC beam during operation, the HL-LHC leadership advanced the start of the works to 2018 and LS2, with the aim of finalising the civil engineering works before Run 3. Designers settled for a double-decker solution, with the new gallery resting parallel to the LHC tunnel, six metres above it, and connected to the old tunnel at four different points. “This elegant double-decker design allows us to bore the connections through the roof of the LHC tunnel, so as to not lose a single square metre of ground floor in the already jam-packed tunnel,” explains Oliver Brüning.

Laurent Tavian, work package leader for the construction of the underground structure, cannot hide his satisfaction with the unfolding of the civil engineering works: “Our main concern was water, as the flooding of the caverns had complicated the digging of different caverns in the past. But this never crystallised into a real issue here, as we were lucky enough to dig during two exceptionally dry years. What we did not expect, however, were the hydrocarbons.” Despite the minor inconvenience of finding small pockets of natural gas and oil and the few weeks lost because of the 2020 lockdown, civil engineering is now finishing smoothly and on schedule, thanks in part to the trusting relationship built with the main contractor company, The Joint Venture Marti Meyrin. The construction of surface buildings – for cooling systems and other services – is well under way and should be completed by autumn 2022.

“The purpose of the HL-LHC upgrade is not limited to maxing out the luminosity of the accelerator, but also to make the machine more reliable. We want it working like a Swiss clock,” states Oliver Brüning. With the new equipment stored separately from the accelerator tunnel in the new underground structures, interventions will be carried out while the machine is still operating, ensuring continuous data collection – unlike in previous runs, when the machine required frequent breaks for technicians to access the equipment. Though the road to the HL-LHC is still long, the idea of a more luminous, sturdier and more reliable accelerator is now one step closer to completion thanks to the new underground structures.

A flight through the upgraded infrastructure at Point 1  (Video: CERN)


LHCb measures tiny mass difference between particles

Tue, 08/06/2021 - 09:57
LHCb measures tiny mass difference between particles Ana Lopes abelchio Tue, 06/08/2021 - 08:57

The LHCb collaboration has measured a difference in mass between two particles of 0.00000000000000000000000000000000000001 grams – or, in scientific notation, 10-38 g. The result, reported in a paper just submitted for publication in the journal Physical Review Letters and presented today at a CERN seminar, marks a milestone in the study of how a particle known as a D0 meson changes from matter into antimatter and back.

The D0 meson is one of only four particles in the Standard Model of particle physics that can turn, or “oscillate”, into their antimatter particles, which are identical to their matter counterparts in most ways. The other three are the K0 meson and two types of B mesons.

Mesons are part of the large class of particles made up of fundamental particles called quarks, and contain one quark and one antimatter quark. The D0 meson consists of a charm quark and an up antiquark, while its antiparticle, the anti-D0, consists of a charm antiquark and an up quark.

In the strange world of quantum physics, just as Schrödinger's notorious cat can be dead and alive at the same time, the D0 particle can be itself and its antiparticle at once. This quantum “superposition” results in two particles, each with their own mass – a lighter and a heavier D meson (known technically as D1 and D2). It is this superposition that allows the D0 to oscillate into its antiparticle and back.

The D0 particles are produced in proton–proton collisions at the Large Hadron Collider (LHC), and they travel on average only a few millimetres before transforming, or “decaying”, into other particles. By comparing the D0 particles that decay after travelling a short distance with those that travel a little further, the LHCb collaboration has measured the key quantity that controls the speed of the D0 oscillation into anti-D0 – the difference in mass between the heavier and lighter D particles.

The result, 10-38 g, crosses the “five sigma” level of statistical significance that is required to claim an observation in particle physics.

“To put this incredibly small mass difference in context, it is still a small number even when compared with the mass of the D0 particle – the same as the mass of a snowball compared to the mass of the entire Mont Blanc, the highest peak in Europe, standing at over 4800 metres,” says LHCb spokesperson Chris Parkes. “And it’s a big step in the study of the oscillatory behaviour of the D0 particles.”

With the tiny mass difference now observed, a new phase of particle exploration can begin. Researchers can make further measurements of the D0 decays to obtain a more precise mass difference and look for the effect on the D0 oscillation of unknown particles not predicted by the Standard Model.

Such new particles could increase the average speed of the oscillation or the difference between the speed of the matter-to-antimatter oscillation and that of the antimatter-to-matter oscillation. If observed, such a difference could shed light on why the universe is made up entirely of matter, even though matter and antimatter should have been created in equal amounts during the Big Bang.

LHCb spokesperson Chris Parkes explains the new result. (Video: CERN)


Read more on the LHCb website.

Computer Security: Block the bad, grant the good access

Mon, 07/06/2021 - 11:57
Computer Security: Block the bad, grant the good access Computer Security Team anschaef Mon, 06/07/2021 - 10:57

Since Santa Claus delivered CERN’s next-generation outer perimeter firewall right before Christmas, the IT department’s network team has finalised its installation and commissioning and the first packets should flow soon through it. With it come new, advanced protection capabilities (hence “next-generation firewall”). Time, then, to start benefitting from these new protective features!

First, some background: CERN’s outer perimeter firewall is the first line of defence for the Organization’s computer security. As a “stateful” firewall, it keeps track of the full state of every single network connection, i.e. the destination IT service being connected to, the network protocol employed (i.e. ICMP, TCP or UDP), the port number used (e.g. “ports 20000-25000/tcp”) and the application-layer protocol (e.g. “HTTPS”), as well as whether the traffic originated from within CERN (“outgoing”) or is destined to be served by CERN (“incoming”).

The firewall automatically analyses in depth any incoming or outgoing traffic and autonomously judges whether to permit or deny its onward journey into or out of CERN. The decision to grant or block traffic is based on network protocol standards, firewall-opening requests made by CERN IT service managers, dedicated threat intelligence provided by the firewall’s security researchers, and the decisions of CERN’s Computer Security Officer, who is mandated to protect the Organization against all types of cyberthreats.

Adhering to network protocol standards, any outgoing traffic initiated from the so-called “lower ports”, i.e. ports 0-1023* or using so-called “private” or “non-routable” IP addresses will be blocked.

Any incoming traffic is blocked by default unless there is an explicit opening towards a particular IT service. Administrators of such IT services can submit corresponding firewall-opening requests, which are subsequently assessed and approved or rejected by the Computer Security team.

In general and as in the past, correctly secured services in production are authorised and opened. Requests in respect of systems that fail to follow basic security paradigms are rejected, and the corresponding systems have to improve their security posture before being reassessed.

Complementing CERN’s intrusion detection system (see our Bulletin article on “Scaling out intrusion detection”), the new firewall comes with sophisticated threat intelligence on malicious actors and threats, allowing the Computer Security team to block any malicious or abnormal incoming or outgoing traffic.

In addition, the firewall will block outgoing traffic to a number of external destinations considered to pose security risks to CERN (and to your devices), like websites:

  • serving malware or being abused for commanding or controlling malware
  • hosting phishing sites
  • offering “grayware” for downloads (i.e. unwanted applications or files that are not classified as malware but can worsen the performance of computers and cause security risks)
  • as well as newly registered domains and private – and hence non-routable – IP addresses.

Furthermore, the firewall will block sites known to contain content the accessing of which constitutes a violation of CERN’s Computing Rules (OC5), like those:

  • dedicated to illegally offering videos, movies or other media for download
  • infringing copyrights (peer-to-peer communication will not be affected as it is also used nowadays for many legitimate reasons).

For these blocked categories, measures have been put in place to understand the collateral damage with regard to false positives, i.e. websites that are harmless. So, if you identify a website that you strongly believe is wrongly blocked, contact us at

Other categories of websites may or may not be blocked by the firewall, depending on the settings that CERN chooses. However, it goes without saying that just because a website is not blocked does not mean that accessing it is necessarily OK and permitted under CERN’s Computer Rules. Accessing content that is inappropriate or offensive or that violates applicable laws is in breach of these Rules and will be followed up by the Computer Security team as usual, regardless of such content’s status in the firewall’s filters.

Any other outgoing traffic, e.g. you browsing the internet, remains unrestricted and the internet is freely “visible” to your devices, laptops and smartphones. Websites with “innocent” content, used either for professional business or for personal leisure, will continue to be accessible from within CERN’s office network, e.g. business and economy, educational institutions, financial services, government, health and medicine, internet communications and telephony, internet portals, job searches, legal, news, online storage and backup, personal sites and blogs, reference and research, search engines, shopping, social networking, training and tools, translation, travel, web-based email, etc.

Please note that, even though CERN provides unrestricted internet access, browsing for personal leisure should be aligned with the “Rules for Personal Use” of the CERN Computing Rules.

Overall, this new configuration is regarded as sound and reasonable. It reflects best practice in terms of modern blocking capabilities and procedures, and protects our open academic environment while taking seriously our need for robust cybersecurity protection.


* VPN and IPsec tunnels will be kept open.

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

First ATLAS New Small Wheel nears completion

Mon, 07/06/2021 - 10:32
First ATLAS New Small Wheel nears completion Katarina Anthony thortala Mon, 06/07/2021 - 09:32

These now-iconic detectors are critical to a new era of exploration for the ATLAS experiment. In the coming years, a major upgrade to the LHC – known as the High-Luminosity LHC – aims to crank up the collider's luminosity by a factor of ten beyond its design value. This will generate even more collisions, allowing ATLAS physicists to probe phenomena that are even rarer in nature.

A massive upgrade of the ATLAS experiment is underway to prepare for this increased luminosity. The first major system to be upgraded is the muon spectrometer, with the New Small Wheels set to be installed on either end of the experiment in summer and autumn 2021. The wheels use novel small-strip Thin Gap Chambers (sTGC) and Micromegas detectors. These new technologies will give ATLAS much more stringent selection criteria for muons, and better handle high background and pile-up rates – the two main requirements for the High-Luminosity LHC.

The New Small Wheels were built in ATLAS institutes around the world and mounted on the wheels at CERN over the course of several years. Following the installation of the last "wedge" of detectors, the first New Small Wheel is now complete, with just final testing and commissioning pending.

The photos below showcase the logistical complexity behind this milestone. Look forward to watching the installation of this “small” behemoth, set to be broadcast live on CERN and ATLAS channels this summer.

To find out more and view more photos, visit the ATLAS website

Apply now to the 2021 CERN Entrepreneurship Student Programme

Thu, 03/06/2021 - 16:26
Apply now to the 2021 CERN Entrepreneurship Student Programme Priyanka Dasgupta katebrad Thu, 06/03/2021 - 15:26 The CERN Entrepreneurship Student Programme invites you on a 5-week journey into the world of entrepreneurship, just like these CESP participants from 2018. (Image: CERN)

Merging technology with entrepreneurship helps to drive innovative solutions to existing challenges. With this in mind, the CERN Entrepreneurship Student Programme (CESP) returns for its fourth edition, training the next generation of entrepreneurs.

This five-week programme will give master’s-level students the opportunity to develop entrepreneurial skills, in collaboration with external mentors, technical experts from CERN and supporters of the CERN entrepreneurship programme. Students studying science, technology, engineering and maths (STEM) subjects from across the world can apply for the chance to spend five weeks learning the venture creation process, with guidance from technology and business experts.

Last year, due to the challenges of the pandemic, CERN adapted the CESP programme to a virtual format that took place in October and November. This year’s virtual edition, however, returns to its original July and August timeframe, to make best use of the students’ summer break.

A great deal was learned from last year’s virtual programme. While the challenges of missing live interaction were clear, the resilience of participants was impressive, adapting and excelling despite the unprecedented situation. The virtual format also improved accessibility, with participants able to connect with a wider range of mentors and potential customers than before.

For this year’s virtual edition, CERN is looking for master’s-level students working on interesting problems. Submit a proposal on why your problem is important, for whom it is a problem and why you are the right team/person to solve this. If you are successful, the CESP project team will connect you to experts at CERN and network mentors. Moreover, CESP will bring you in contact with start-up accelerators, seed funds and venture funds to help you navigate your start-up journey after the completion of the CESP programme.

Applications are open from now until 1 July 2021 and the programme will be held from 26 July to 27 August. CESP is managed by the CERN Knowledge Transfer group and enabled by the CERN & Society Foundation. The 2021 edition is made possible by the Arconic Foundation.

For more details, including how to apply, see the CESP page.

Celebrating four years of the CERN alumni network with a virtual event

Thu, 03/06/2021 - 11:47
Celebrating four years of the CERN alumni network with a virtual event cagrigor Thu, 06/03/2021 - 10:47


Nearing the end of a professional CERN contract can be exciting but is not always easy, especially for those who are at an early stage of their career. However, leaving CERN doesn’t mean that you have to part ways with the Organization and its collaborative community. Since its launch in 2017, the High-Energy Network of CERN alumni has been fostering links between CERN and its outgoing personnel across all categories, including students, users, fellows, associates and staff members.

The network has been growing steadily, with a current membership of over 6800 people worldwide. It includes groups of people with common interests, scientific collaboration groups and student groups, as well as ten regional groups, which will be joined by others soon. To celebrate its fourth anniversary, a special virtual event will be held on LinkedIn on 8 June, focusing on how CERN can be a career springboard and on the incredible career trajectories of CERN alumni and their impact on society.

An exciting programme will showcase how CERN alumni have gone on to work on initiatives and drive innovation for the benefit of society in fields ranging from medical applications to the environment.

We’ll be joined by Charlotte Warakaulle, CERN’s Director for International Relations, who will highlight the strategic importance of the alumni network for CERN, and by three CERN alumni: Mario Michan, Director and CEO of Daphne Technology, whose aim is to decarbonise the maritime industry, Christina Vallgren, Co-founder and CEO of TERAPET SA, which is improving proton therapy for cancer treatment, and her latest recruit, Michael Betz.

We’ve also been crafting a new module that will allow you to benefit even more from being part of the network. Stay tuned to learn all about it during the event!

Whether you move on to a new employer or a new field or launch your own start-up, being a member of the alumni network isn’t just about having fast-track access to job opportunities, events, talks and other resources. It’s a way to stay connected to CERN, its community and your colleagues. If you want to be part of a unique, supportive network comprising like-minded individuals, spread across the globe and united by a passion for science, CERN and its scientific mission, why not join the network?

Check out some of our previous events:

CERN Alumni First Collisions
Moving out of Academia to Industrial engineering
Moving out of Academia to Entrepreneurship
Moving out of Academia to the Environmental Industry

Accelerators meet gravitational waves

Thu, 03/06/2021 - 10:49
Accelerators meet gravitational waves cagrigor Thu, 06/03/2021 - 09:49


In particle accelerators like the Large Hadron Collider (LHC), charged particles bob and weave in magnetic and electric fields, following tightly corralled trajectories. Their paths are computed assuming a flat Euclidean space-time, but gravitational waves ­– first observed by the LIGO and Virgo detectors in 2015 – crease and stretch this underlying geometry as they ripple out across the universe. For the past 50 years, there has been intermittent interest in the possibility of detecting observable resonant effects as a result of this extra curvature of the fabric of space-time, as the particles whizz around the accelerators repeatedly at close to the speed of light.

Advances in accelerator technology could now usher in an era of gravitational-wave astronomy in which particle accelerators play a major role. To explore this tantalising possibility, over 100 accelerator experts, particle physicists and members of the gravitational physics community participated in a virtual workshop entitled “Storage Rings and Gravitational Waves” (SRGW2021), organised as part of the European Union’s Horizon 2020 ARIES project. During this meeting, they explored the role that particle accelerators could play in the detection of cosmological backgrounds of gravitational waves. This would provide us with a picture of the early universe and give us hints about high-energy phenomena, such as high-temperature phase transitions, the nature of inflation and new heavy particles that cannot be directly produced in the laboratory.

Lively discussions at the SRGW2021 workshop – the first, apart from an informal discussion at CERN in the 1990s, to link accelerators and gravitational waves and bring together the scientific communities involved – attest to the prospective role that accelerators could play in detecting or even generating gravitational waves. The great excitement and interest prompted by this meeting, and the exciting preliminary findings from this workshop, call for further, more thorough investigations into harnessing future storage rings and accelerator technologies for gravitational-wave physics.

This text was extracted from the full meeting report in CERN Courier, where you can learn more about gravitational-wave research using particle accelerators.

FASER catches first candidate collider neutrinos

Wed, 02/06/2021 - 16:24
FASER catches first candidate collider neutrinos Ana Lopes abelchio Wed, 06/02/2021 - 15:24

It’s a first at the Large Hadron Collider (LHC), or indeed at any particle collider: the FASER collaboration has detected the first candidate particle interactions for neutrinos produced in LHC collisions. The result, described in a paper posted online, paves the way for studies of high-energy neutrinos at current and future colliders.

Neutrinos are the most abundant fundamental particles that have mass in the universe, and they have been detected from many sources. Yet, no neutrino produced at a particle collider has ever been directly detected, even though colliders produce them in abundance. Studying such collider neutrinos could shed new light on the still enigmatic nature of these fundamental particles, not least because collider neutrinos are produced at high energies, at which their weak interactions with matter have been little studied.

The FASER experiment’s FASERν detector and the newly approved SND@LHC detector have both been designed to catch and study collider neutrinos, and they are expected to be installed at the LHC over the course of 2021 and to begin taking data when the collider starts up again in 2022. However, the FASER collaboration was in for an early treat when it took four weeks’ worth of proton–proton collision data with a smaller pilot version of FASERν shortly before the LHC was shut down for maintenance and upgrades at the end of 2018.

After analysing the pilot detector data and estimating a background of particle events that could mimic the signal from neutrino interactions, the FASER team found several candidate events for collider neutrinos. The result has a statistical significance of 2.7 standard deviations, a little below the 3 standard deviations required to claim evidence of a particle or process in particle physics.

“The goal of the pilot detector was to demonstrate the feasibility of neutrino measurements in the experimental environment of the LHC,” says FASER co-spokesperson Jamie Boyd. “So we are very excited that this small detector, which is only about 1% of the final detector, allowed us to see the first candidate events for neutrino interactions at a collider.”

The team expects to observe about 20 000 collider neutrino interactions with the full-fledged FASERν detector in the next LHC run, from 2022 to 2024.

Two candidate events for neutrinos produced in LHC collisions and interacting in the FASERν pilot detector. The neutrinos enter the detector from the left, and interact with the detector material to produce a number of charged particles. The different lines in each event show tracks from these charged particles, originating from the neutrino interaction point. (Image: FASER/CERN)

CERN switched off its lights for the second edition of "La nuit est belle!"

Mon, 31/05/2021 - 10:17
CERN switched off its lights for the second edition of "La nuit est belle!" thortala Mon, 05/31/2021 - 09:17

On Friday, 21 May, CERN took part in the general switch-off of public lighting for the event La nuit est belle!

La nuit est belle! aims to raise public awareness about the impact of light pollution caused by artificial lighting. This second edition was dedicated to the protection of nocturnal biodiversity.

Despite the cancellation of some of the activities due to the rain, 178 municipalities in Greater Geneva actively participated in the event by not turning on their streetlights. Shops, companies and private individuals also joined the movement, as well as more than 100 municipalities beyond Greater Geneva.

Discover the time-lapse of the Globe of Science and Innovation recorded on this occasion.

Time-lapse video of the Globe during "La nuit est Belle" 2021 (Video: CERN)

For more information, visit:


CERN’s COVID scale and measures

Thu, 27/05/2021 - 12:10
CERN’s COVID scale and measures thortala Thu, 05/27/2021 - 11:10

On 1 June, a new unified system governing teleworking, site access and other aspects of life at CERN will be introduced. It has been developed over recent weeks by a Lab-wide working group and is based on the incidence rate in the local area, along with a qualitative assessment taking into account the number of confirmed cases at CERN, vaccination, the stratified testing campaign and the local presence of new variants of the virus. The level in force at any given time may move up or down the scale and may change at short notice. Normally, the level to be applied will be communicated with 10 days’ notice via the weekly COVID-19 email, while the level in force will be displayed on the information panels at the entrances to the CERN sites, on the HSE website and in the main CERN directory. In the event of sudden degradation, any level change will be promptly notified through the COVID-19 email.

CERN’s COVID scale has four levels, with level four (red) being the strictest and level one (green) being the most open. In between come level three (orange) and level two (yellow). Level four is applied when the virus is circulating in the local area at a rate of over 100 cases per 100 000 people per week, while level one applies when circulation is negligible. The transition between levels may lead to the relaxation or strengthening of measures, as the prevailing situation demands, and the levels of service offered on the CERN sites will be adapted accordingly.

Teleworking measures vary according to the level in force. When level four or three applies, for example, those who can telework should telework, though one day per week on site is possible under level four, and two days per week under level three. Site access conditions under levels four and three stipulate that members of the personnel may come on site for professional reasons only, and in consultation with their supervisors, while retirees may come on site to access bank safety deposit boxes, the Pension Fund or the CHIS office, only if strictly necessary. Family members are still, in levels four and three, not permitted on site. These conditions are relaxed under levels two and one. Hygiene measures will continue to apply whatever the level.

These are the main features of the system, but there is much more detail concerning activities and services on site. Club activities, shop and exhibition opening and on-site visits, for example, are all covered.

As is already the case today, the measures defined in the new system will be complemented by rules regarding isolation and quarantine for COVID-19 cases, close contacts and persons arriving from high-risk countries and areas. These rules will continue to reflect Host State regulations and recommendations and CERN’s need to define a unique set of measures on its sites.

A summary of the system is available on the poster above, and full details may be found here. Once the system is in force, a banner at the top of the CERN home page indicating the level currently in force will click through to the full description of the conditions under that level of the scale.

CERN opportunities for STEM* students with disabilities

Wed, 26/05/2021 - 11:52
CERN opportunities for STEM* students with disabilities Anna Cook anschaef Wed, 05/26/2021 - 10:52

Every year, CERN welcomes hundreds of students to embark on a unique journey of growth and discovery, guided and coached by supervisors eager to impart the richness of working here. This gives the students the opportunity to build skills, demonstrate those skills to employers and gain work experience in what is a great start to their future career. CERN’s administrative, technical and doctoral student programmes, alongside the short-term internships and flagship summer-student opportunities, make up the vast landscape that demonstrates CERN’s commitment to educating the next generation of scientists. And in recent years, this offering has taken on a new dimension.

Accessibility and reasonable accommodations for people with disabilities is a key facet of the CERN Diversity & Inclusion (D&I) policy. In 2017, CERN was awarded a grant from the European Physical Society for a disability-specific internship programme proposed by the Diversity & Inclusion team at the time. The programme aimed to contribute to the academic and professional development of undergraduate and graduate students with visible and non-visible disabilities while helping the high-energy physics community to increase the diversity of its talent pool. The Organization would also benefit by improving its inclusiveness practices. And the momentum has built: since 2018, six interns have joined CERN thanks to this initiative, through either the short-term internship or technical student programmes, and more are set to join in the near future.

The impact of the initiative is best illustrated in the participants’ own words. “The CERN programme for students with disabilities was a unique opportunity to demonstrate my abilities, to gain confidence. Thanks to my supervisor, I was able to spread my wings, prove my skills, go beyond my disability,” says Mathias, a student in IT. His supervisor, Pawel, notes: “I truly believe that we should be more open towards people with disabilities. The opportunity created a change in Mathias’ life as well as in our lives and in CERN as an Organization. Working together with people with disabilities on common goals requires us to ‘look at the world from a new perspective’, which I consider beneficial.” Axel, another supervisor who guided a student over the course of several months, underlined that “he integrated so well that people took him as what he was: a productive, smart intern. But for me personally, what I'm most proud of is not that ‘we made it’, nor that our student credibly conveyed that he really appreciated his time with us, nor that CERN and the diversity office succeeded with this pilot: it's that the team seems to continuously sense team members’ needs and reacts appropriately and in a welcoming, inclusive and inspiring way.”

The short-term internship programme coordinator, Laetitia Bréavoine, is in direct contact with supervisors and students alike in this context: “I was deeply touched to see how enthusiastic our supervisors were about participating in this programme. The most rewarding thing for me is to witness the joy of students when they find out they have a chance to come to CERN, and I am proud to have helped make it happen.”

The programme was recently recognised by the OECD in its benchmark study of diversity and inclusion, which compared CERN with seven other international organisations. As it goes from strength to strength, Axel sums it up well: “More of that, please: let's start to actively increase diversity!”


If you are interested in taking part as a supervisor in the studentships for people with disabilities, contact

To find out more about the D&I framework for people with disabilities, along with other D&I aspects, visit the D&I website.

*STEM: science, technology, engineering and mathematics

An upgraded Inner Tracking System joins the ALICE detector

Wed, 26/05/2021 - 10:29
An upgraded Inner Tracking System joins the ALICE detector thortala Wed, 05/26/2021 - 09:29

After two nerve-wracking months dedicated to the installation of the ALICE detector’s new Inner Tracking System (ITS), Corrado Gargiulo’s mechanical engineering team, in charge of the installation, can relax: the delicate procedure has been successfully completed and ALICE’s innermost subdetector is poised to collect its first data in the coming weeks.

With its 10 m2 of active silicon area and nearly 13 billion pixels, the new ITS is the largest pixel detector ever built. The detector lies sandwiched between the beam pipe and the Time Projection Chamber, which was installed in 2020, deep in the ALICE detector. By reconstructing primary and secondary particle vertices and improving the momentum and angle resolution for particles reconstructed by the Time Projection Chamber, the ITS is instrumental in identifying the particles born out of the powerful lead–lead collisions in the core of the ALICE detector.

The upgrade of the ITS will significantly increase the resolution of the vertex reconstruction, making the subdetector fit for future runs with higher luminosity, as part of a comprehensive overhaul of ALICE’s subdetectors striving for this very objective. The current upgrade relies on new pixel sensors called ALPIDE, which also make up the new Muon Forward Tracker (MFT), installed a few months ago. Each of those chips contains more than half a million pixels in an area of 15 × 30 mm2 and features an impressive resolution of about 5 μm in both directions – the secret to the subdetector’s improved performances. They are organised in seven layers, the innermost three forming the inner barrel, while the outermost four make up the outer barrel. The collected data is then transmitted with a bit rate of up to 1.2 Gb/s to a system of about 200 readout boards located 7 m away from the detector. The data is then aggregated and eventually sent to ALICE’s computing farm, where it is sequenced and processed.

The insertion of the heart of the ALICE detector around its beam pipe required surgical-like precision. The installation unfolded in two stages, as the two barrels making up the ITS had to be lowered separately, two months apart. The outer barrel got the ball rolling: it was loaded onto a truck in March and transported from Meyrin to Point 2, where the mating of its two halves and its insertion in the detector were carried out smoothly.

Installation of the Outer Barrel of the new silicon Inner Tracking System of ALICE inside the solenoidal magnet. (Image: CERN)

But the outer barrel was the easy part, at least compared to its inner counterpart whose insertion was complicated by its position right by the beam pipe. Luckily, weeks of rehearsals and careful alignment studies using metrological surveys proved their worth, and after an intense week of insertion and mating of the component’s two halves, which involved a few late-evening sessions for the experts, the delicate manoeuvre was completed in the late evening of 12 May. Preliminary tests showed no damage occurred during the installation, proving that the teams’ hard work paid off.

The ITS is now fully ready for stand-alone tests with cosmic rays, in view of joining the MFT for a common commissioning phase. The final steps before taking data at the LHC are the installation scheduled for next month of the Fast Interaction Trigger, the last of the ALICE subdetectors that has yet to join this formidable machine, and an overarching commissioning phase starting in July. With the milestone of the ITS installation now behind them, the ALICE collaboration is looking ahead to Run 3 with growing confidence and excitement.

RADES joins the hunt for dark matter

Tue, 25/05/2021 - 12:18
RADES joins the hunt for dark matter Ana Lopes abelchio Tue, 05/25/2021 - 11:18

Long-hypothesised particles called axions could solve two problems in one strike: they could explain the puzzling symmetry properties of the strong force and they could make up the mysterious dark matter that permeates the cosmos. One of the newest detectors of the CAST experiment at CERN, RADES, has now joined the worldwide hunt for axions, searching for axions from the Milky Way’s “halo” of dark matter and setting a limit on the strength of their interaction with photons. The results are described in a paper submitted for publication in the Journal of High Energy Physics.

One way of searching for axions from the Milky Way’s dark-matter halo is to look for their conversion into photons in a “resonating cavity”. If such axions surround and enter a resonating cavity that is placed in a strong magnetic field and resonates at a frequency corresponding to their mass, the chances of detecting them through their conversion into photons are increased.

Many experiments have used this search method and set limits on the interaction strength of axions with two photons in the case of small axion masses, mainly below 25 µeV (for comparison, the proton mass is 1 GeV). Searching for larger axion masses using this approach requires a smaller cavity resonating at a higher frequency, but the smaller volume of a smaller cavity decreases the chances of spotting the particles.

A workaround involves dividing the cavity into smaller cavities that resonate at a higher frequency and collectively don’t result in a loss of cavity volume. This is exactly the concept behind the RADES detector, which was installed inside one of CAST’s dipole magnet bores in 2018 and can search for axions from the Milky Way’s dark-matter halo that have a mass of around 34.67 µeV.

Researchers are developing complementary approaches to searching for axions, and some have searched for larger-mass axions using new cavity designs and placed limits on their interaction strength with two photons. But the best limit so far for an axion mass of 34.67 µeV was placed by CAST’s previous searches for axions from the Sun.

In its latest paper, the CAST team describes the results of the first RADES search for axions. Sifting through data taken for more than 100 hours within a period of 20 days in 2018, the team saw no signs of axions. However, the data places a limit on the interaction strength of axions with two photons in the case of axions with a mass of or close to 34.67 µeV – a limit that is more than 100 times more stringent than CAST’s previous best limit for this mass.

“This result is a significant first step in the direct search for axions using dipole magnets,” says RADES scientist Sergio Arguedas Cuendis. “And as far as axion searches go, it’s one of the most stringent limits ever set for axions with masses above 25 µeV.”

Recognise the signs of a mental health problem

Fri, 21/05/2021 - 11:09
Recognise the signs of a mental health problem Medical Service anschaef Fri, 05/21/2021 - 10:09

According to the World Health Organization (WHO), mental disorders affect one in four people in the world. Our mental health evolves throughout our lifetime and is influenced by many factors, both internal and external. The COVID-19 pandemic is a good example of an external factor that puts our mental health under strain.

We can feel mentally well while suffering from a mental disorder. We can also feel under mental strain without having a mental disorder, for instance when we experience an unsettling event, such as separation or losing a loved one.

So, when should you take action? The signs and symptoms to look out for fall into several categories:

  • Emotional: sadness, fear, anxiety, irritability, low self-esteem.
  • Behavioural: mood swings, aggression, lack of interest in activities and difficulty performing daily tasks, substance abuse.
  • Cognitive: significant difficulties concentrating or reasoning normally, memory problems.
  • Physical: headaches, intense fatigue, sleep problems, loss of appetite, rapid heart rate.
  • Sensory: visual or auditory perception problems.

The time to take action is when the symptoms do not subside and they stop you going about your daily life.

Some of the symptoms of feeling depressed or “down” and being clinically depressed are the same – fatigue, lack of concentration, sleep problems and feeling sad. But people who are just feeling down have milder symptoms that disappear by themselves with time and social interaction. Feeling down is temporary and is a normal part of life, such as when facing a difficulty; it can sometimes just depend on the time of year or there may even be no apparent reason.

Depression, on the other hand, is an illness. Its symptoms are more intense and are experienced all day long, almost every day, lasting anything from two weeks to several months, and do not depend on the circumstances. The symptoms can interfere with your daily life, making it difficult to communicate, concentrate and retain information, and can therefore have an impact on your social relationships and work. Other possible symptoms are weight gain or loss, somatic problems (e.g. stomach or back pain), despair and dark thoughts.

Depression can be treated, but proper care and monitoring are essential.

If you feel that you would benefit from talking professional or personal matters through with a professional, don’t hesitate to contact us. The Medical Service offers all members of the personnel (MPE and MPA) first-line psychological counselling. Appointments with our psychologists, Katia Schenkel and Sébastien Tubau, are free of charge and strictly confidential:

Let’s not forget that our mental health is crucial to our overall health.


For more information:


The next article in this series will look at ways of looking after our mental health.

Change at the helm of the CERN & Society Foundation

Thu, 20/05/2021 - 18:11
Change at the helm of the CERN & Society Foundation thortala Thu, 05/20/2021 - 17:11

After eight successful years as the Head of the Partnerships and Fundraising Section at CERN, it is with deep gratitude and a bittersweet heart that we announce that Matteo Castoldi is stepping down from his position. 

During his tenure, Matteo has overseen the creation and consolidation of fundraising from private donors at CERN through the CERN & Society Foundation. He was instrumental in the development and implementation of CERN’s first strategy for fundraising, and has spearheaded the fundraising campaigns to  successfully launch projects such as the Beamline for Schools Competition, the CERN Entrepreneurship Student Programme, the High School Student Internship Programme, Sparks!, and more. In the last two years, Matteo has also supported the capital fundraising campaign of the CERN Science Gateway which has successfully almost reached its fundraising goals within this very short time span.

“It has been a privilege for me to have had the mandate to set up and run CERN’s fundraising activities for so many years. I would like to thank the former and the present CERN management for giving me this opportunity. I would also like to give my gratitude to the team of amazing colleagues at CERN, the wonderful donors, and of course all the past and present members of the Partnerships & Fundraising team, who helped me greatly in order to succeed in this endeavour.”

Matteo Castoldi (Image: CERN)

Matteo has been quintessential to the fact that more than 9,500 high-school students have been engaged with STEM disciplines, more than 190 graduates have been trained and partnerships with more than 80 organisations have been established since the CERN & Society Foundation was born in 2014. We wish Matteo the very best for his next professional adventure.

Filling his shoes is Pascale Goy who has so far spent her career in leadership and human resources management in various international organizations, namely the World Trade Organization and the International Trade Centre, before joining CERN. Pascale took charge of the Learning and Development Group at CERN from its creation, in 2012. She was instrumental in transforming training at CERN into six wide-ranging learning portfolios, from leadership to highly technical fields, with over 500 courses delivered every year to 6000 physicists, engineers, technicians and administrative staff. Her enthusiasm and energy contributed to developing effective and productive partnerships with all departments at CERN over the course of her tenure. Her human touch and strong belief in people’s development and growth potential will definitely stand her in good stead as she embraces this new role.

“Helping to spread the CERN spirit of scientific curiosity is a great cause I believe in. I am honoured to take up this challenge at this moment in my career. It is a remarkable new professional trajectory that inspires me to give everything I have and then some, and to make a difference. CERN is unique indeed, and I look forward to the thrilling experience of driving the Partnerships and Fundraising mission. I cannot wait to get started! I would like to give my thanks to Matteo for the very warm welcome.”

The CERN Director for International Relations Charlotte Warakaulle thanked Matteo for his achievements and welcomed Pascale to the team:

We are grateful to Matteo for his essential role in the launch and consolidation of fundraising activities at CERN. With vision and dedication, he has built strong and lasting partnerships in support of science, and helped to enhance our impact on society. Matteo’s work provides a firm foundation on which Pascale will build, bringing with her wide-ranging expertise and great passion for inclusive partnerships, learning and education. I look forward to the next exciting chapter for CERN & Society!

If you wish to know more about the CERN & Society Foundation, the latest Annual Report is now available here.

Why the LHC magnets are blue - and other colourful accelerator questions answered

Wed, 19/05/2021 - 18:39
Why the LHC magnets are blue - and other colourful accelerator questions answered Thomas Hortala thortala Wed, 05/19/2021 - 17:39

Springtime has arrived in Geneva, where CERN is located, bringing with it colourful blossoms and the whir and buzz of nature awakening. A few dozen metres beneath the fertile soil, another equally buzzing ecosystem is springing back to life: CERN’s accelerator system, whose rings are gradually entering their recommissioning phase. Whether the beauty of our metal machines resembles that of mother nature is open to debate, but one thing is certain: when it comes to colourfulness, our accelerators can compete with most blossoming meadows.

Magnets are systematically painted to protect them from rust, except in the case of superconducting magnets (like those of the LHC), where the vacuum vessels containing the equipment are painted instead. Besides the blue of the LHC dipole magnets, which bend particle beams to preserve the particles’ circular trajectory, CERN’s accelerators are painted in colours ranging from red to green, purple, orange and various shades of silver. How are these colours chosen and why? The short answer is that CERN’s top physicists and engineers decide which ones they like the best. Indeed, unlike other pieces of equipment whose colour code is strictly regulated for safety reasons, the teams developing the magnets have free reign over the colour of their creations.

Certain unwritten rules do influence their decision-making, however, as Vittorio Parma, formerly in charge of the LHC cryostats, explains: “Working in accelerator tunnels can be quite gloomy as the lighting is poor. To offset this, we tend to go for the brighter, more luminous colours that make working around the magnets easier.” This swayed Vittorio’s team towards the choice of a gleaming white for the vacuum vessels containing the LHC’s quadrupole magnets, which focus the particles in tighter bunches, when they designed the LHC superconducting magnets in the 1990s. The white alternates with the more familiar blue of the dipoles and the deep red of the triplet quadrupole magnets, which further focus the beam around the collision points. They will be joined in a few years’ time by the dark blue of the future High-Luminosity LHC’s 11 Tesla magnets, which are currently undergoing tests. The darker shade is intended to reflect the magnet’s stronger magnetic field than that of the regular LHC dipoles, which are lighter in colour.

The LHC with its blue dipole magnets and white quadrupole magnets (top left), a red LHC triplet quadrupole magnet before installation (top right) and a prototype of the dark blue 11 Tesla HL-LHC dipole magnet (bottom) (Image: CERN)

This gaudy picture is completed by the magnets of CERN’s other accelerators (LINAC 4, the Proton Synchrotron and its Booster, the Super Proton Synchrotron and the antimatter decelerating rings, to name but a few). “Each machine was built at a different point in time, by different people with different mindsets. Each team chose the hues of their magnets without following any strict code and, as a result, each machine is a unique, colourful artwork. This showcases the diversity and the creativity of the work done here at CERN”, explains Davide Tommasini, who led the development of the superconducting magnets for the LHC.

Consequently, a bending dipole magnet in the PS Booster is green, while its SPS counterpart is red, and a blue magnet may be a dipole in the LHC or a quadrupole in the SPS or LEIR. This somewhat messy patchwork contributes to the strong visual identity of CERN’s accelerators, from the green and orange of the PS Booster to the red and dark blue of the SPS - not to mention the magnets of the transfer lines, which boast their own specific colours, such as the mint and lavender of the superb dipole magnets we see below.

The PS Booster very nearly took a different path, recalls Giorgio Brianti, Division Leader at the time the machine was built. “I thought it would be nice to hold a competition for a colour scheme.” Coming at the tail end of the flower-power era, though, this was maybe not such a good idea. “The winning entry was kind of psychedelic, with lots of bands of colour all over the place. I didn’t like the result at all, so I presented the prize of a few bottles of champagne to the winner, but I chose the colours myself.”

The PS Booster with its orange quadrupole and green dipole magnets, (top left), dipole magnets used in the PS Booster transfer lines (top right, bottom left), and the Super Proton Synchrotron with its red dipole and blue quadrupole magnets (bottom right) (Image: CERN)

So, which is your favourite?