Summer has arrived and may bring with it another heatwave at a time when, unfortunately, COVID-19 is still with us.
The World Meteorological Organization (WMO) recently published a warning about the health risks posed by the double challenge of a heatwave and the pandemic, especially for vulnerable people. Some of the measures usually recommended during a heatwave, such as the use of air conditioning, contradict those in place to combat the novel coronavirus.
Here are a few tips to help you stay safe during this time, without increasing the risk of spreading the virus:
In the event of a medical emergency, call 74444!(Image: CERN)
If you need support on a specific issue, the following services are available to you:
After ten years as the High-Luminosity LHC (HL-LHC) project leader, Lucio Rossi, who will leave CERN this autumn, is passing the baton to Oliver Brüning, who has been his deputy since the project was launched in 2010.
Oliver Brüning began his career in particle physics at the DESY laboratory in Hamburg, Germany. Having completed a PhD on particle dynamics in the HERA storage ring, he took part in the commissioning of the accelerator. He joined the SPS-LEP accelerator physics group at CERN as a fellow in 1995, and later became a staff member. He became the leader of the AB-ABP-LOC (Accelerators and Beam Physics – LHC Operation and Commissioning) section in 2003 and then, two years later, of the BE-ABP group. From 2008 onwards, he was in charge of the accelerator systems side of the work towards a possible large hadron–electron collider (LHeC). From 2009 to 2010, he was deputy head of the BE department. And from 2015 to 2019, he led the LHC Full Energy Exploitation study, which set out the preparatory and consolidation work required for the LHC to run at an energy of 14 TeV in Run 3 and, beyond that, for the HL-LHC.
The HL-LHC is now entering the crucial installation phase: as civil engineering work progresses, the first components have been inserted into the accelerator (see here and here). “Over the last few months, the HL-LHC project has passed some significant milestones,” says Oliver Brüning. “The underground structures of the High-Luminosity LHC were connected to the LHC tunnel at Point 1 in December 2019 and at Point 5 in June 2020. Recently, a superconducting electrical transmission line developed for the HL-LHC set a new record.” The next major step for the project will be the installation, this winter, of an 11 tesla dipole magnet that uses the superconductor niobium–tin (Nb3Sn).On 30 June 2020, Fabiola Gianotti, CERN Director-General, Frédérick Bordry, Director for Accelerators and Technology, Lucio Rossi, former HL-LHC project leader, and Oliver Brüning, new HL-LHC project leader, marked the connection of the LHC tunnel with the HL-LHC at Point 5 (Image: CERN)
Lucio Rossi will leave CERN at the end of September, having devoted more than 19 years to the LHC and its successor. After taking over the leadership of CERN’s Superconducting Magnets and Cryostats group in 2001, he put all his energy and enthusiasm into guiding the team responsible for developing, building, constructing, assembling and installing the thousands of superconducting magnets that make up the LHC. He is one of the main supporters of and driving forces behind the High-Luminosity LHC project, which he has led since the very beginning. As of October, the multi-award-winning physicist will be a professor at the University of Milan and an associate of INFN-LASA, his home institute. He plans to devote himself to teaching and to medical applications.
The LHCb collaboration has observed a type of four-quark particle never seen before. The discovery, presented at a recent seminar at CERN and described in a paper posted today on the arXiv preprint server, is likely to be the first of a previously undiscovered class of particles.
The finding will help physicists better understand the complex ways in which quarks bind themselves together into composite particles such as the ubiquitous protons and neutrons that are found inside atomic nuclei.
Quarks typically combine together in groups of twos and threes to form particles called hadrons. For decades, however, theorists have predicted the existence of four-quark and five-quark hadrons, which are sometimes described as tetraquarks and pentaquarks, and in recent years experiments including the LHCb have confirmed the existence of several of these exotic hadrons. These particles made of unusual combinations of quarks are an ideal “laboratory” for studying one of the four known fundamental forces of nature, the strong interaction that binds protons, neutrons and the atomic nuclei that make up matter. Detailed knowledge of the strong interaction is also essential for determining whether new, unexpected processes are a sign of new physics or just standard physics.
“Particles made up of four quarks are already exotic, and the one we have just discovered is the first to be made up of four heavy quarks of the same type, specifically two charm quarks and two charm antiquarks,” says the outgoing spokesperson of the LHCb collaboration, Giovanni Passaleva. “Up until now, the LHCb and other experiments had only observed tetraquarks with two heavy quarks at most and none with more than two quarks of the same type.”
“These exotic heavy particles provide extreme and yet theoretically fairly simple cases with which to test models that can then be used to explain the nature of ordinary matter particles, like protons or neutrons. It is therefore very exciting to see them appear in collisions at the LHC for the first time,” explains the incoming LHCb spokesperson, Chris Parkes.
The LHCb team found the new tetraquark using the particle-hunting technique of looking for an excess of collision events, known as a “bump”, over a smooth background of events. Sifting through the full LHCb datasets from the first and second runs of the Large Hadron Collider, which took place from 2009 to 2013 and from 2015 to 2018 respectively, the researchers detected a bump in the mass distribution of a pair of J/ψ particles, which consist of a charm quark and a charm antiquark. The bump has a statistical significance of more than five standard deviations, the usual threshold for claiming the discovery of a new particle, and it corresponds to a mass at which particles composed of four charm quarks are predicted to exist.
As with previous tetraquark discoveries, it is not completely clear whether the new particle is a “true tetraquark”, that is, a system of four quarks tightly bound together, or a pair of two-quark particles weakly bound in a molecule-like structure. Either way, the new tetraquark will help theorists test models of quantum chromodynamics, the theory of the strong interaction.
Read more on the LHCb website.
Chris Parkes of the University of Manchester in the UK has been appointed as the new spokesperson of the LHCb experiment collaboration. Parkes, who was previously the deputy spokesperson of the collaboration, will represent more than 1400 people from 85 institutions in 19 countries for a period of three years, beginning 1 July 2020.
Parkes takes over the LHCb leadership from Giovanni Passaleva of the National Institute for Nuclear Physics in Florence, Italy, who has served as LHCb spokesperson since 1 July 2017.
“It’s an exciting time to take the reins of LHCb,” say Parkes. “We are preparing many exciting physics results from analyses of the full data taken during the first decade of LHC operations. We’re currently constructing and installing our new detector apparatus, the LHCb Upgrade I. It will allow us to collect larger data sets and relies on a new paradigm of real-time analysis, free of the restrictions that come with a traditional hardware trigger. The construction activities have been heavily disrupted by the COVID-19 pandemic, but we are working together across the international collaboration to complete the experiment. For the further future, we are planning an Upgrade II of the detector that will allow the full exploitation of the High-Luminosity LHC. LHCb is a growing global community that celebrates our diversity and spirit of open collaboration. It will be a pleasure and honour to lead the collaboration in the next stage of its journey.”
“It has been a great pleasure serving the collaboration these last three years,” says Passaleva. “During this term Chris and I have led a major renewal and improvement of the experiment for the upcoming LHC Run 3. And we had the fortune to witness historical discoveries! It was really great to work with Chris and I have no doubt he will lead LHCb to new heights.”
Parkes is a professor at the University of Manchester, UK. He has been deputy spokesperson of LHCb for the past three years and has been a member of the collaboration for more than twenty years. Parkes was one of the instigators of both the LHCb Upgrade I and II, and led the UK’s construction activities for the LHCb Upgrade I. He has worked extensively on physics studies involving the charm quark and on the LHCb Vertex Locator (VELO) detector, serving as the detector’s Project Leader during the first LHC physics period (2010–2012). Prior to LHCb, he worked on W-boson physics with the DELPHI experiment at the previous CERN collider, LEP.
White Rabbit (WR) is a technology developed at CERN to provide sub-nanosecond accuracy and picosecond precision of synchronisation for the LHC accelerator chain. First used in 2012, the technology has since then expanded its applications outside the field of particle physics and is now deployed in numerous scientific infrastructures worldwide. It has shown its innovative potential by being commercialised and introduced into different industries, including telecommunications, financial markets, smart grids, space industry and quantum computing.
CERN developed White Rabbit (WR) as an open-source hardware, with primary adoption by other research infrastructures with similar challenges in highly accurate synchronization of distributed electronic devices. The R&D process and all knowledge gained throughout the development has been made available through CERN's Open Hardware Repository. This gives other organisations and companies the freedom to use and modify existing information. Through proactive engagement of CERN's Knowledge Transfer and Beam Controls groups, a larger group of companies and organisations connected to the development of hardware, software, and gateware for WR switches and nodes. The WR ecosystem quickly grew to include several organisations, developing open hardware for widespread benefit. This collaborative approach brought improvements to the original concept, allowing CERN to also benefit from the new developments.
On 16 June, the WR technology was recognised as a worldwide industry-standard, called Precision Time Protocol (PTP), governed by the IEEE, the world's largest technical professional organisation dedicated to advancing technology for the benefit of humanity. The WR addition to the PTP standard, referred to as High Accuracy, allow to increase PTP's synchronisation performance by a few orders of magnitude, from sub-microseconds to sub-nanoseconds.
“PTP is the first IEEE standard to incorporate a CERN-born technology. This is a major step for White Rabbit. It is already widely used in large scientific facilities and its adoption in industry is gaining momentum. Its incorporation into the PTP standard will allow hardware vendors world-wide to produce WR equipment compliant with the PTP standard and consequently accelerate its dissemination on a larger scale," says Maciej Lipinski, Electronics Engineer at CERN, who led the WR standardisation effort.
Intensity is rising at CERN. In the superconducting equipment testing hall, an innovative transmission line has set a new record for the transport of electricity. The link, which is 60 metres long, has transported a total of 54 000 amperes (54 kA, or 27 kA in either direction). “It is the most powerful electrical transmission line built and operated to date!” says Amalia Ballarino, the designer and project leader.
The line has been developed for the High-Luminosity LHC (HL-LHC), the accelerator that will succeed the Large Hadron Collider (LHC) and is scheduled to start up at the end of 2027. Links like this one will connect the HL-LHC’s magnets to the power converters that supply them.Interview with Amalia Ballarino, the superconducting link project leader, during the insertion of the line into its cryostat in February 2020 (Video: CERN)The secret to the new line’s power can be summarised in one word: superconductivity.
The line is composed of cables made of magnesium diboride (MgB2), which is a superconductor and therefore presents no resistance to the flow of the current and can transmit much higher intensities than traditional non-superconducting cables. On this occasion, the line transmitted an intensity 25 times greater than could have been achieved with copper cables of a similar diameter. Magnesium diboride has the added benefit that it can be used at 25 kelvins (-248 °C), a higher temperature than is needed for conventional superconductors. This superconductor is more stable and requires less cryogenic power. The superconducting cables that make up the innovative line are inserted into a flexible cryostat, in which helium gas circulates.
The strands of magnesium diboride of which the cables are made were developed by industry, under CERN’s supervision. The cable manufacturing process was designed at CERN, before industrial production began. As the strands of magnesium diboride are fragile, manufacturing the cables requires considerable expertise. The current is transmitted from the power supply at room temperature to the flexible link by ReBCO high-temperature superconducting (HTS) cables.A team member connects the superconducting link cables before the electrical transmission tests begin (Image: CERN)
Last year, an initial prototype transmitted a 40 kA intensity over a distance of 60 metres. The link that is currently being tested is the forerunner of the final version that will be installed in the accelerator. It is composed of 19 cables that supply the various magnet circuits and could transmit intensities of up to 120 kA! “We started the power tests by connecting just four cables, two at 20 kA and two at 7 kA,” explains Amalia Ballarino. New records are therefore expected to be set in the coming months.
This new type of electrical transmission line has applications far beyond the realm of fundamental research. Links like these, which can transfer vast amounts of current within a small diameter, could be used to deliver electricity in big cities, for example, or to connect renewable energy sources to populated areas.
On 12 June, the new schedule for the activities of Long Shutdown 2 (LS2) was unveiled. The first test beams will circulate in the LHC at the end of September 2021, four months after the date planned before the COVID-19 crisis.
The rest of CERN’s accelerator complex will restart gradually from December 2020 onwards. The various ISOLDE experiments and the experiments at the PS-SPS complex will therefore be able to start data taking as of summer 2021.
The COVID-19 lockdown phase, which resulted in a shutdown of activities on the CERN site and the closure of many partner institutes, is now being followed by a gradual restart, all of which has naturally had an impact on the LS2 schedule. For example, it is now impossible for several activities to take place simultaneously in the same location, which is causing delays to the schedule. The main LHC experiments, which are international collaborations, are facing particular difficulties, since they are waiting for equipment and collaborators to arrive from all over the world.Restart of the activities of the DISMAC (Diode Insulation and Superconducting Magnets Consolidation) project in the LHC tunnel (Image: CERN)
To allow them to complete their upgrade programmes, Run 3 of the LHC will therefore start in March 2022, provided that the current plan, which includes the installation of the second small wheel of ATLAS, is confirmed. If this is not the case, physics running will instead be brought forward to November 2021. “Initially, ATLAS had planned to install its second small wheel during the 2021-2022 year-end technical stop (YETS),” recalls José Miguel Jiménez, head of CERN’s Technology department. “But, under the new schedule, it might be possible – if the assembly process proceeds without any issues – to install it during LS2.” The schedule will be confirmed by the ATLAS collaboration in November.
In order to keep to the schedule, around 500 additional people – mainly those involved in LS2 – have been returning to their activities on the CERN site every week since the start of Phase I of the restart plan on 18 May. “We have been able to plan the restart precisely and optimally thanks to the excellent documentation work done by all the teams before the machines were put into safe mode in March,” emphasises Jiménez. This has made it possible to resume activities rapidly since May, although often in a different order: “It hasn’t always been possible to simply pick up where we left off,” he adds. “Many institutes are still closed, not to mention the fact that many of our collaborators and contractors are unable to come to CERN.”Copper coating of the interior of a cylinder for the COLDEX (COLD bore Experiment) installed in the SPS (Image: CERN)
No changes have been made to the schedule beyond 2022. Provided that ATLAS completes its upgrades during LS2, the 2023/2024 YETS will be a normal shutdown. LS3 will start at the beginning of 2025.
Closure of accelerators – current schedule:
The commissioning of the accelerators will begin this summer, starting with gradual hardware commissioning. The first beams from Linac 4 are expected in December this year.
Between now and the end of 2020, seven of the LHC’s eight sectors will be cooled down. Electrical quality tests, powering tests and a long campaign of quench training for the magnets will follow.
A week of tests with low intensity beams will take place at the LHC at the end of September 2021.
Restart of physics runs – current schedule:
According to the new schedule, all of the LHC experiment halls will be closed on 1 February 2022.
Special COVID-19 occupational health and safety measures
Special health and safety measures have been put in place at CERN to help in the fight against COVID-19 (see full details on the HSE unit website).
In particular, we remind you that:
We invite you to consult all the special COVID-19 occupational health and safety measures on the HSE unit website.
These exceptional measures must be followed in addition to the usual safety and radiation protection rules, which remain in force come what may.
The CERN against COVID-19 task force, and the dozens of members of the CERN community involved in the initiatives launched since lockdown began, are continuing their work. Find out the latest news on the task force website:
CERN and Paragraf - a technology company borne out of the department of materials science at the University of Cambridge – are set to detail final results of tests conducted on a novel graphene-based local magnetic measurement sensor. The collaboration has proved that such a sensor eliminates some of the systematic errors and inaccuracies found in the state-of-the-art sensors used at CERN.
The Hall probe is an important tool for local magnetic field mapping – an essential task in particle accelerators, which depend on high-precision magnetic fields. The probe transduces the magnetic field into a proportional voltage. However, errors frequently arise due to elements of the sensor not being perfectly aligned and sensitive to in-plane field components (planar effect), as well as non-linear response.
Theoretically, graphene solves this issue. This carbon allotrope, first discovered at the University of Manchester in 2004, has been hailed as the new wonder material, as its extreme thinness, lightness, conductivity and resistance could revolutionize a variety of technologies. In the case of the Hall probe, the development of a two-dimensional graphene sensor clears the issue of planar effects and makes for precise detections, including at liquid-helium temperatures.
Find out more in the CERN Courier
On 11 June, LHCb announced the winners of the 2020 PhD Thesis and Early Career Scientist Awards.
The LHCb Thesis Awards recognize excellent PhD theses and additional work that have made an exceptional contribution to LHCb. In parallel, the Early Career Scientist prizes are awarded to recognize outstanding achievements of early career scientists to the benefit of LHCb.
This year’s winners of the Thesis prize are Philippe D'Argent (Heidelberg University) and Laurent Dufour (Nikhef/Groningen University. Carlos Abellan Beteta (Zurich), Claudia Bertella (CERN), Daniel Campora (Nikhef), Nadim Conti (INFN, Milan), Edgar Lemos Cid (Santiago de Compostela), Olli Lupton (Warwick), Mark Smith (Imperial College), Dorothea vom Bruch (LPNHE, Paris) were awarded the Early Career prize.
“The number of brilliant winners of the Early Career Scientist prize and the extraordinary level of the PhD theses evaluated, show how crucial the contribution of younger colleagues to the experiment activities truly is”, point out Francesca Dordei and Stephanie Hansmann-Menzemer, Chairs of the Prize Committees. “It was really hard for the Committees to select only a few names among the many early career scientists and PhD students that not only contribute but often lead cutting edge developments in LHCb physics, detector and software developments”. Almost 350 PhD students study in the collaboration on diverse areas of LHCb physics, ranging from physics analysis to advanced detector and software developments.
Last week, in the context of the 5-Yearly Review (5YR), the CERN Management presented to the CERN Council its proposal identifying the financial and social conditions to be reviewed for staff members, fellows and associated members of the personnel. This proposal is the result of several months of concertation with the Staff Association during many CCP (Comité de Concertation Permanent) meetings, and discussed subsequently at TREF (the Tripartite Employment Conditions Forum) with representatives of the Member States. Contrary to the previous 5YR in which a number of ‘optional elements’ were included in the process, this exercise will focus primarily on the mandatory elements. Nevertheless, in a continuing effort to follow societal developments and improve diversity across the CERN population, in particular in respect of gender, as well as of under-represented Member and Associate Member States, and to foster retention post-recruitment, the Management proposed to carry out a benchmarking exercise with other organisations to ensure CERN remains at the leading edge in terms of employment conditions.
In preparation for this key milestone in the 5YR’s lifecycle, intensive efforts have been underway since 01 January 2020 to collect, review and analyse a huge amount of data to produce the main reports. So what happens next? The work will continue in earnest to collect the relevant data from local and international markets for the Staff salary comparative analysis, and with ESA, ESO, EMBL, the EC and DESY for the Fellows stipends comparative analysis. The findings will then be reported and discussed at CCP, followed by presentations to TREF in October 2020, March 2021 and May 2021. The projected completion date of the 5-Yearly Review is the Council meeting in December 2021.
Further details of the 5-Yearly Review 2021, content, timescales and updates can be found on https://hr-dep.web.cern.ch/content/5yr-2021.
There is strong evidence that dark matter exists and permeates the cosmos, yet all searches for the hypothetical particles that may make up this invisible form of matter have drawn a blank so far. In light of these null results, researchers have started to spread a wider net in their searches, exploring as many types of particle as possible, new regions in which the particles may lie hidden and new ways to probe them. The NA64 experiment collaboration has now widened the scope of its searches with a search for axions and axion-like particles – hypothetical particles that could mediate an interaction between dark matter and visible matter or comprise dark matter itself, depending on their exact properties.
The NA64 team targeted an unexplored area for axions and axion-like particles, a gap in the two-dimensional area of possible values of their mass and interaction strength with a pair of photons. This gap doesn’t include the regions where axions and axion-like particles could make up dark matter, but it includes an area where axions could explain the long-puzzling symmetry properties of the strong force, for which axions were originally proposed, as well as an area where axion-like particles could mediate an interaction between dark matter and visible matter.
To explore this gap, the NA64 team used an electron beam of 100 GeV energy from the Super Proton Synchrotron and directed it onto a fixed target. They then searched for axions and axion-like particles that would be produced in interactions between high-energy photons generated by the 100 GeV electrons in the target and virtual photons from the target’s atomic nuclei. The researchers looked for the particles both through their transformation, or “decay”, into a pair or photons in a detector placed right after the target or through the “missing energy” that the particles would carry away if they decayed downstream of the detector.
The NA64 team analysed data that was collected over the course of three years, between 2016 and 2018. Together, these data corresponded to some three hundred billion electrons hitting the target. The NA64 researchers found no sign of axions and axion-like particles in this dataset, but the null result allowed them to set limits on the allowed values of the interaction strength of axions and axion-like particles with two photons for particle masses below 55 MeV.
“We’re very excited to have added NA64 to the list of experiments that are hunting for axions as well as axion-like particles, which are a popular candidate for a mediator of a new force between visible and dark matter”, says NA64 collaboration spokesperson Sergei Gninenko. “Little by little, and together, these experiments are narrowing down the regions of where to look for, and perhaps find, these particles.”
Plastic scintillators are one of the most used active materials in high-energy physics. Their properties make it possible to track and distinguish between particle topologies. Among other things, scintillators are used in the detectors of neutrino oscillation experiments, where they reconstruct the final state of the neutrino interaction. Measurements of oscillation phenomena are carried out through comparison of observations of neutrinos in near detectors (close to the target) and far detectors (up to several hundred kilometres away).
CERN is strongly involved in the T2K experiment, the current world-leading neutrino oscillation experiment, in Japan, which recently released promising results. A future upgrade of the experiment’s near detector will pave the way for more precise results. The novel detector will comprise a two-tonne polystyrene-based plastic scintillator detector segmented into 1 x 1 x 1 cm3 cubes, leading to a total of around two million sensitive elements: the smaller the cubes, the more precise the results. This technology could be adopted for other projects, such as the DUNE near detector. However, more precise measurements would require finer granularity, making the detector assembly harder.
This is where the CERN EP-Neutrino group – led by Albert De Roeck – steps in, developing a new plastic scintillator production technique that involves additive manufacturing. The R&D is carried out in collaboration with the Institute for Scintillation Materials (ISMA) of the National Academy of Science of Ukraine, which has strong expertise in the development of scintillator materials, and the Haute École d’Ingénierie et Gestion du Canton de Vaud (HEIG-VD), which is expert in additive manufacturing. The final goal is to 3D-print a “super-cube”, that is, a single massive block of scintillator containing many optically independent cubes. 3D-printing would solve the issue of assembling the individual cubes, which could thus be produced in any size, including smaller than 1 cm3, and relatively quickly (volumes bigger than 20 x 20 x 20 cm3 can be produced in about a day).
So far, the collaboration has been fruitful. A preliminary test gave the first proof of concept: the scintillation light yield of a polystyrene-based scintillator 3D-printed with fused deposition modelling (see fig. 2) has been found to be comparable to that of a traditional scintillator. But the road towards a ready-to-use super-cube is still long. Further optimisation of the scintillator parameters and tuning of the 3D-printer configuration, followed by a full characterisation of the 3D-printed scintillator, will need to be achieved before the light reflector material for optically isolating the cubes can be developed.
This new technique could also open up new possibilities for the field of particle detection. A successful 3D-printed plastic scintillator detector could pave the way for a broader use of this technology in detector building, which could shake up the field of high-energy physics, as well as that of medicine, where particle detectors are used, for instance, in cancer therapy. Moreover, the greatly cost-effective 3D-printer could be replicated quite easily and used in a vast number of settings. Umut Kose, from the EP-neutrino group and Neutrino Platform at CERN, explains: “Our dream goes beyond the super-cube. We like to think that, in a few years, 3D-printing will allow high-school students to make their own radiation detection systems. The outreach potential of this technology is mind-blowing”.
Davide Sgalaberna, now at ETH Zurich, cannot hide his enthusiasm for this adventure: “This is the first time that 3D-printing could be used for real particle detectors. We are transforming our personal will into a project, and we are hopeful that this could lead to a breakthrough. That is thrilling”. A thrill shared by Davide’s colleagues, who are more than ready to resume work on the 3D-printed detector once the easing of lockdown allows everyone to return to CERN.
Read the full story in the EP newsletter
Following almost two years of discussion and deliberation, the CERN Council today announced that it has updated the strategy that will guide the future of particle physics in Europe within the global particle-physics landscape. Presented during the open part of the Council’s meeting, held remotely due to the ongoing COVID-19 pandemic, the recommendations highlight the scientific impact of particle physics, as well as its technological, societal and human capital.
By probing ever-higher energy and thus smaller distance scales, particle physics has made discoveries that have transformed the scientific understanding of the world. Nevertheless, many of the mysteries about the universe, such as the nature of dark matter, and the preponderance of matter over antimatter, are still to be explored. The 2020 update of the European Strategy for Particle Physics proposes a vision for both the near- and the long-term future of the field, which maintains Europe's leading role in addressing the outstanding questions in particle physics and in the innovative technologies being developed within the field.
The highest scientific priorities identified in this update are the study of the Higgs boson - a unique particle that raises scientific profound questions about the fundamental laws of nature - and the exploration of the high-energy frontier. These are two crucial and complementary ways to address the open questions in particle physics.
“The Strategy is above all driven by science and thus presents the scientific priorities for the field,” says Ursula Bassler, President of the CERN Council. “The European Strategy Group (ESG) – a special body set up by the Council – successfully led a strategic reflection to which several hundred European physicists contributed.” The scientific vision outlined in the Strategy should serve as a guideline to CERN and facilitate a coherent science policy across Europe.
The successful completion of the High-Luminosity LHC in the coming decade, for which upgrade work is currently in progress at CERN, should remain the focal point of European particle physics. The strategy emphasises the importance of ramping up research and development (R&D) for advanced accelerator, detector and computing technologies, as a necessary prerequisite for all future projects. Delivering the near and long-term future research programme envisaged in this Strategy update requires both focused and transformational R&D, which also has many potential benefits to society.
The document also highlights the need to pursue an electron-positron collider acting as a “Higgs factory” as the highest-priority facility after the Large Hadron Collider (LHC). The Higgs boson was discovered at CERN in 2012 by scientists working on the LHC, and is expected to be a powerful tool to look for physics beyond the Standard Model. Such a machine would produce copious amounts of Higgs bosons in a very clean environment, would make dramatic progress in mapping the diverse interactions of the Higgs boson with other particles and would form an essential part of a rich research programme, allowing measurements of extremely high precision. Construction of this future collider at CERN could begin within a timescale of less than 10 years after the full exploitation of the High-Luminosity LHC, which is expected to complete operations in 2038.
The exploration of significantly higher energies than the LHC will allow new discoveries to be made and the answers to existing mysteries, such as the nature of dark matter, to potentially be found. In acknowledgement of the fact that the particle physics community is ready to prepare for the next step towards even higher energies and smaller scales, another significant recommendation of the Strategy is that Europe, in collaboration with the worldwide community, should undertake a technical and financial feasibility study for a next-generation hadron collider at the highest achievable energy, with a view to the longer term.
It is further recommended that Europe continue to support neutrino projects in Japan and the US. Cooperation with neighbouring fields is also important, such as astroparticle and nuclear physics, as well as continued collaboration with non-European countries.
“This is a very ambitious strategy, which outlines a bright future for Europe and for CERN with a prudent, step-wise approach. We will continue to invest in strong cooperative programmes between CERN and other research institutes in CERN’s Member States and beyond,” declares CERN Director-General Fabiola Gianotti. “These collaborations are key to sustained scientific and technological progress and bring many societal benefits.”
“The natural next step is to explore the feasibility of the high-priority recommendations, while continuing to pursue a diverse programme of high-impact projects,” explains ESG chair Halina Abramowicz. “Europe should keep the door open to participating in other headline projects that will serve the field as a whole, such as the proposed International Linear Collider project.”
Beyond the immediate scientific return, major research infrastructures such as CERN have broad societal impact, thanks to their technological, economic and human capital. Advances in accelerators, detectors and computing have a significant impact on areas like medical and biomedical technologies, aerospace applications, cultural heritage, artificial intelligence, energy, big data and robotics. Partnerships with large research infrastructures help drive innovation in industry. In terms of human capital, the training of early-career scientists, engineers, technicians and professionals provides a talent pool for industry and other fields of society.
The Strategy also highlights two other essential aspects: the environment and the importance of Open Science. “The environmental impact of particle physics activities should continue to be carefully studied and minimised. A detailed plan for the minimisation of environmental impact and for the saving and reuse of energy should be part of the approval process for any major project,” says the report. The technologies developed in particle physics to minimise the environmental impact of future facilities may also find more general applications in environmental protection.
The update of the European Strategy for Particle Physics announced today got under way in September 2018, when the CERN Council, comprising representatives from CERN’s Member and Associate Member States, established a European Strategy Group (ESG) to coordinate the process. The ESG worked in close consultation with the scientific community. Nearly two hundred submissions were discussed during an Open Symposium in Granada in May 2019 and distilled into the Physics Briefing Book, a scientific summary of the community’s input, prepared by the Physics Preparatory Group. The ESG converged on the final recommendations during a week-long drafting session held in Germany in January 2020. The group’s findings were presented to the CERN Council in March and were scheduled to be announced on 25 May, in Budapest. This was delayed due to the global Covid-19 situation but they have now been made publicly available.
For more information, consult the documents of the Update of the European Strategy for Particle Physics:
Michel Spiro, renowned physicist, President of the International Union of Pure and Applied Physics (IUPAP) and former President of CERN Council (2010-2012), is the new Chair of the CERN & Society Foundation Board. He replaces Anne Richards, who completed her second and final term as founding Board member of the Foundation. The physicist Fido Dittus is taking the role of Board Member designated by CERN. He is replacing Peter Jenni, whose term also ended.
Since 2014, the CERN & Society Foundation disseminates the organization’s knowledge and savoir-faire to the benefit of society, through education and outreach activities. Under Anne and Peter’s leadership, the foundation has significantly extended its impact on society through partnerships with more than 80 organizations and education programmes that engaged more than 9500 high-school students with STEM disciplines.
To find out more, read the Foundation’s annual review whose 2019 edition has just been published.
The COVID-19 pandemic has seen CERN shine in its response to the crisis, with creative, collaborative, inventive solutions highlighted in the framework of the CERN against Covid-19 taskforce, which has channelled many initiatives from our community to harness CERN’s technologies, expertise and know-how for the benefit of society.
While encouraging us all to take well-deserved leave to take care of ourselves and return to work refreshed, the Director-General has appealed to our collective sense of solidarity and generosity by encouraging CERN employees to donate some of their leave days. Their monetary equivalent will be used to contribute to the work of the CERN against COVID-19 taskforce and to cover other COVID-19-related expenses the Laboratory has to face.
The response to this appeal has been remarkable: since 26 May more than 750 leave days have been donated with each donation ranging between 1 and 10 days maximum.
Leave can be donated up to 13 September on: http://cern.ch/leave-donation.
Donations are anonymous. Full details of the scheme, open to Staff and Fellows can be found on: https://admin-eguide.web.cern.ch/en/procedure/covid-19-leave-donation.
Computing equipment donated to Fayoum University has left CERN on 16 June for Egypt.
117 servers from the CERN computing centre and six network switches were donated to Fayoum University. The donation included more than three thousands processor cores for the compute, and more than 1000 terabytes for the storage.
Fayoum University is part of the Egyptian Network for High Energy Physics (ENHEP) and became a CMS member in 2010. The equipment donated will be instrumental in the creation of a facility supporting scientific analyses, providing storage data space for scientific experiments and for performing Monte Carlo simulations. The created centre will ultimately join the Worldwide LHC Computing Grid (WLCG).
Since 2012, CERN has regularly donated computing equipment that no longer meets its highly specific requirements on efficiency but is still more than adequate for less exacting environments. To date, a total of 2252 servers and 129 network switches have been donated by CERN to countries and international organisations, namely Algeria, Bulgaria, Ecuador, Egypt, Ghana, Mexico, Morocco, Nepal, Palestine, Pakistan, the Philippines, Senegal, Serbia, and the SESAME laboratory in Jordan.
Geneva and Hamburg, 15 June 2020. Two teams of high-school students, one from the International School of Geneva, Campus des Nations, Switzerland, and one from the Werner-von-Siemens-Gymnasium in Berlin, Germany, have won the 2020 Beamline for Schools competition (BL4S). Later this year, the winning teams will be invited to the DESY research centre in Hamburg, Germany, for the opportunity to carry out their proposed experiments together with scientists from CERN and DESY.
Beamline for Schools, an international competition open to high-school students from across the world, invites submission of proposals for an experiment that uses a beamline. Beamlines deliver a stream of subatomic particles to any given set-up, making it possible to study a broad variety of properties and processes in various scientific disciplines. They are operated at laboratories such as CERN and DESY. Due to the second Long Shutdown of CERN’s accelerators for maintenance and upgrade, there is currently no beam at CERN, which has opened up opportunities for partnerships with laboratories such as DESY during this period.
"DESY is very pleased to welcome the BL4S competition for the second time," says Helmut Dosch, Chairman of the DESY Board of Directors. "The preparations must have been even more challenging for the students this year, but the high number of participants proves how popular this competition is. We are looking forward to meeting the next generation of scientists in autumn.”
Since Beamline for Schools was launched in 2014, more than 11,000 students from 91 countries have participated. This year, 198 teams from 49 countries worldwide submitted a proposal for the competition’s seventh edition. From the entries received, 23 teams from 17 different countries (Argentina, Australia, Bulgaria, Canada, Chile, China, Germany, Japan, Netherlands, Philippines, Poland, Portugal, Spain, Switzerland, Turkey, United Kingdom, United Sates) were shortlisted. Each shortlisted team will receive BL4S t-shirts and a Cosmic Pi detector. Ten teams from Australia, Brazil, India, Italy, Japan, Mexico, Russia, Turkey, United States, were selected for Special Mention and will also receive BL4S t-shirts.
“We look forward to welcoming this year’s winners to DESY. With the difficult situation worldwide, we are particularly grateful for and overwhelmed by the record number of entries. Students across the globe organised themselves via videoconferences and teamed up even across countries – an undoubtedly extraordinary and experience-rich situation for everyone,” said Sarah Aretz, BL4S project manager.
The two winning teams of 2020 have proposed two very different experiments. This illustrates the wide spectrum of research questions that are possible within the boundary conditions of BL4S. The team Nations' Flying Foxes from Switzerland wants to detect a particle known as Δ+ Baryon. When high energy electrons interact with protons, these protons can be converted into the Δ+ particle. As the particle has a very short lifetime, the team will have to look for indirect signatures pretty much in the same way as short-lived particles are detected in the large experiments at CERN and DESY.
“From the first brainstorming session for ideas two years ago, to finally going to DESY in a few months – this has been an amazing journey. What an incredible moment! This will truly shape our academic careers well into the future,” said Mikhail Slepovskiy from the Nations’ Flying Foxes team.
The team ChDR Cheese from Germany wants to use a physics effect known as Cherenkov Diffraction Radiation (ChDR) as the basis of an innovative technology for the diagnosis of particle beams in accelerators. When particles move along certain materials such as fused silica, photons can be created while the particle beam itself is not disturbed. The properties of these photons, however, provide information about the beam that is valuable for the accelerator control system.
“Hearing that we had won baffled all of us. It was like a dream come true. We are tremendously grateful to DESY and CERN for giving us this incredible opportunity and cheering us up in such trying times,” said Tobias Baumgartner from the ChDR Cheese team.
Beamline for Schools is an Education and Outreach project funded by the CERN & Society Foundation and supported by individual donors, foundations and companies. For 2020, the competition is partly supported by the Wilhelm and Else Heraeus Foundation with additional contributions from the Arconic Foundation as well as from the Ernest Solvay Fund, managed by the King Baudouin Foundation.
BL4S website: http://beamline-for-schools.web.cern.ch
2020 edition: https://beamlineforschools.cern/editions/2020-edition
Shortlisted and special mention teams 2020: https://beamlineforschools.cern/bl4s-shortlisted-and-special-mention-teams-2020
Previous winners: https://beamlineforschools.cern/bl4s-competition/winners
CERN, the European Organization for Nuclear Research, is one of the world's leading laboratories for particle physics. The Organization is located on the French-Swiss border, with its headquarters in Geneva. Its Member States are: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Cyprus and Slovenia are Associate Member States in the pre-stage to Membership. Croatia, India, Lithuania, Pakistan, Turkey and Ukraine are Associate Member States. The European Union, Japan, JINR, the Russian Federation, UNESCO and the United States of America currently have Observer status.
About the CERN & Society Foundation:
The CERN & Society Foundation is a charitable foundation established by CERN to fund a programme of projects. These projects, in the areas of education and outreach, innovation and knowledge exchange, and culture and creativity, are inspired or enabled by CERN, but lie outside of its specific research mandate. The Foundation seeks the support of individuals, trusts, international organizations and commercial entities to help make these projects happen, and spread the CERN spirit of scientific curiosity for the inspiration and benefit of society.
DESY is one of the world’s leading particle accelerator centres. Researchers use the large‐scale facilities at DESY to explore the microcosm in all its variety – ranging from the interaction of tiny elementary particles to the behaviour of innovative nanomaterials, the vital processes that take place between biomolecules and the great mysteries of the universe. The accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. DESY is a member of the Helmholtz Association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent).
This media update is part of a series related to the 2020 Large Hadron Collider Physics conference, which took place from 25 to 30 May 2020. Originally planned to take place in Paris, the conference was held entirely online due to the COVID-19 pandemic.
At the LHCP conference this year, the ATLAS and CMS collaborations presented new results relating to a physics process called vector boson scattering. CMS also reported the first observation of the so-called “massive triboson production. Studying these processes to test the Standard Model is important as it could shed light on new physics. The results were presented online at the virtual LHCP conference, originally due to be held in Paris.
During proton collisions at the LHC, many particles, including the carriers of the electroweak force – photons and W and Z bosons – are produced. These bosons are often referred to simply as vector bosons, in the Standard Model, and one of the processes that leads to their pair production is called vector boson scattering.
Vector boson processes are an excellent probe to seek deviation from theoretical predictions. Two rare processes that are of particular interest as they probe the self-interactions of four vector bosons are diboson production via vector boson scattering and triboson production”. The observation and measurement of these processes are important as they test the electroweak symmetry breaking mechanism, whereby the unified electroweak force separates into electromagnetic and weak forces in the Standard Model, and are complementary to the measurements of Higgs boson production and decay.
In a vector boson scattering process, a vector boson is radiated from a quark in each proton and these vector bosons scatter off one another to produce a diboson final state. Triboson production refers instead to the production of three massive vector bosons.
At the LHCP conference, physicists from the ATLAS and CMS collaborations presented new searches for the production of a pair of Z bosons via electroweak production including the vector boson scattering mechanism. ATLAS observed this process at 5.5 sigma and CMS reported strong evidence. CMS also reported the first observation of a W boson produced in association with a photon through the vector boson scattering process, as well as more precise measurements of the same-sign WW production, and an observation of the vector boson scattering production of a W and a Z boson, complementing earlier ATLAS observations.
Another way to probe four-boson interaction is to study the very rare production of three massive bosons or tribosons. This April, the CMS experiment released a 5.7 sigma result of the triboson phenomenon, establishing it as a firm observation, following the first evidence of this process seen by the ATLAS experiment last year.
Most physics processes of fundamental particles involve two or more individual particles that interact with each other via an intermediary particle that is emitted or absorbed in the process.
“The more bosons produced, the rarer the event. This new observation of tribosons was very difficult because it is a much rarer process than the one that led to the Higgs boson discovery, and very interesting because it may reveal signs of new particles and anomalous interactions,” says Roberto Carlin, CMS spokesperson.
In the triboson and vector boson scattering processes, W and Z can interact with themselves to create more W and Z particles, producing two or three bosons. W and Z being highly unstable particles, they quickly decay into leptons (electrons, muons, taus and their corresponding neutrinos) or quarks. But such processes are extremely rare and the diboson and triboson events that physicists look for are mimicked by background processes, making them even more difficult for physicists to analyse.
“To separate signal from background, physicists have to be ingenious and employ advanced machine learning algorithms. This is a challenging task for such rare processes, and requires meticulous and thorough studies,” says Karl Jakobs, ATLAS spokesperson.
The measurements of vector boson scattering and triboson production presented at LHCP 2020 are consistent with the predictions made by the Standard Model, which remains our best understanding of fundamental particles and their interactions. The above observations also provide physicists with tools to probe quartic self-interaction between massive electroweak bosons. The current measurements place constraints on the strength at which these quartic interactions take place and increased precision from the use of new datasets could open up horizons for new physics at higher energy scales in the LHC and lead to possible discoveries of new particles.
Last week, the LHC Experiments Committee formally accepted a proposal for a new first stage of the high-level trigger (HLT) for LHCb. LHCb is one of the four main experiments on the Large Hadron Collider (LHC). It is exploring what happened after the Big Bang that allowed matter to survive and build the Universe we see today.
Like the other experiments on the LHC, LHCb uses a ‘trigger’ system to filter the huge amount of data produced by particle-collision events within its detectors. About 1 in 500 collision events are selected for further analysis. This trigger system is split into two levels: HLT 1, which reduces the data rate from around 40Tbit/s to 1–2 Tbit/s, and HLT 2, which reduces this further to 80 Gbit/s. This is then sent to storage and analysed using the Worldwide LHC Computing Grid (WLCG).
Until now, both HLT 1 and HLT 2 have been carried out using a farm of traditional computer chips called CPUs, which stands for ‘central processing unit’. The new system – set to go into production in 2021 – will see HLT 1 run instead on graphical processing units (GPUs). The highly parallelised structure of GPUs can make them more efficient than general-purpose CPUs for running algorithms that process large blocks of data in parallel.
Researchers at LHCb have been exploring the potential of GPUs for their trigger systems since around 2013. Building on that foundational work, this new system is the specific result of intense investigations carried out over the last two years, through an initiative called Allen, which is named after the pioneering computer scientist Frances Elizabeth Allen. The three lead developers for the Allen team are, Dorothea vom Bruch, a postdoctoral researcher from the French Laboratory of Nuclear and High-Energy Physics (LPNHE); Daniel Cámpora, a postdoctoral researcher from the University of Maastricht and the Dutch National Institute for Subatomic Physics (Nikhef), who was a PhD student during most of Allen’s development, co-supervised between CERN and the University of Sevilla in Spain; and Roel Aaij, a software engineer at Nikhef, who also played a major role in the development and commissioning of LHCb’s Run 1 and 2 HLT systems.The lead developers of the Allen initiative (Image: CERN)
The Allen team’s new system can process 40 Tbit/s, using around 500 NVIDIA Tensor Core GPUs. It matches – from a physics point of view – the reconstruction performance for charged particles achieved on traditional CPUs. It has also been shown that the Allen system will not be limited in terms of memory capacity or bandwidth. Plus, not only can it be used to perform reconstruction, but it can also take decisions about whether to keep or reject collision events.
A diverse range of algorithms has been implemented efficiently on Allen. This demonstrates the potential for GPUs not only to be used as computational accelerators in high-energy physics, but also as complete and standalone data-processing solutions. Other LHC experiments are also investigating the potential of GPUs; the ALICE experiment already used them in production for their HLT in Run 2.
“We knew that this was an interesting avenue to explore, but we were surprised it worked out so quickly,” says Vladimir Gligorov of LPNHE, who leads LHCb’s Real Time Analysis project. “Over the last two years, the LHCb HLT team made the CPU HLT almost ten times faster, so it could work as planned, which is itself a huge achievement, and then this blue-skies project paid off as well. Now we can have the best of both worlds.”
The Allen initiative has received support through a CERN openlab project with the Italian company E4 Computer Engineering, which deploys hardware from NVIDIA. This project provides a testbed for GPU-accelerated applications, with several use cases spread across various LHC experiments.
“Through the CERN openlab project, the team was able to capitalise on E4 Computer Engineering’s expertise and strong links with NVIDIA,” explains Maria Girone, CERN openlab CTO. “This helped ensure the team was supplied with GPUs on which to run tests, and meant there was a good link with the NVIDIA engineers, who provided advice for helping to make the code run as efficiently as possible on the GPUs. This kind of interaction with industry plays an important role in accelerating innovation and helps us to solve the computing challenges posed by the LHC’s ambitious upgrade programme.”
“CERN openlab has played an important role in bringing together various teams across the laboratory and the experiments who are exploring the potential of GPUs,” explains Gligorov. “Seeing that others were exploring this technology too helped give us the confidence to push forward with these investigations. We’re certainly glad we did, as they’ve really paid off.”