Cern News

NA64 uses the high-energy SPS muon beam to search for dark matter

The NA64 experiment started operations at CERN’s SPS North Area in 2016. Its aim is to search for unknown particles from a hypothetical “dark sector”. For these searches, NA64 directs an electron beam onto a fixed target. Researchers then look for unknown dark sector particles produced by collisions between the beam’s electrons and the target’s atomic nuclei.

Recently, the NA64 team started using a muon beam from the SPS to search for new particles that interact predominantly with muons – heavier versions of the electron – and could explain simultaneously the long-standing puzzle of the muon’s anomalous magnetic moment and the dark-matter (DM) problem. Their first results were accepted in the journal Physical Review Letters on 8 April.

In this paper, the NA64 collaboration sets new limits on the available parameter space – the window where the researchers could find a hypothetical dark boson Z’ coupling only to muons and tauons for given values of its mass and coupling strength. In the so-called vanilla model, the Z’ can only decay back into neutrinos and could provide an explanation of the muon’s anomalous magnetic moment puzzle. However, in extended models, it can also decay into DM candidates. This would solve the DM problem by predicting the observed relic density of DM particles created in the early universe. With these results, the NA64 collaboration demonstrates the great potential of muon beams in dark matter searches and in future new physics scenarios preferably coupled to muons.

“Muons scattering off the nuclei in the target could produce a hypothetical dark boson Z’, followed by its invisible decay into either a pair of neutrinos or a pair of dark-matter candidates, depending on the underlying model,” explains the deputy Technical Coordinator Laura Molina Bueno. “The signature of this production would be missing energy and momentum in our detectors.”

To search for this, a 160 GeV tertiary muon beam derived from the primary SPS proton beam is fired onto an electromagnetic calorimeter acting as an active target. The experimentalists then search for events in which one final-state muon has a momentum lower than 80 GeV with no detectable activity in the downstream calorimeters.

As no event matching these conditions was observed in the expected signal region, the researchers were able to exclude this region and conclude that, for the first model, the only possible mass window for a dark boson Z’ to explain the g-2 muon anomaly is from 6 MeV up to 40 MeV. Their results also indicate that light thermal dark matter coupled to the standard model via a (Lmu-Ltau) Z’ cannot be heavier than 40 MeV.

NA64 is among the first experiments searching for dark sectors weakly coupled to muons. The experimentalists are confident that they will cover the available parameter space in the future by using higher beam intensities. “Using a muon beam opens a new window to explore other well-motivated new physics scenarios, such as benchmark dark-photon models, scalar portals, millicharged particles or lepton-flavour violating processes,” concludes NA64 co-Spokesperson Paolo Crivelli.

anschaef Sat, 05/18/2024 - 08:34 Byline Kristiane Bernhard-Novotny Publication Date Sat, 05/18/2024 - 08:29

Accelerator Report: Already a fifth of the way there

The whole CERN accelerator complex and its associated experimental facilities have been fully operational for some time now, so the time is ripe to review the first part of this year’s run and look forward to what is still to come.

At the LHC, first collisions with just a few bunches occurred on 6 April. Meaningful physics data taking can only begin when collisions take place with at least 1200 bunches per beam, and this milestone was reached on 14 April. It means that, out of the 147 days allocated to proton-proton collisions this year, 32 have already been completed, representing just over 20% of the 2024 proton run.

During these initial 32 days, the LHC machine was available 67.2% of the time with stable beams in collision 45.2% of the time. The goal is to achieve a stable beam time ratio of at least 50%. Such figures are quite normal in the early stages of an annual run, a period during which various teething problems and challenges are identified and addressed, as discussed in my last report.

Luminosity production is also progressing according to schedule, as can be seen in the graph below. So far, the integrated luminosity collected has reached 17.5 fb-1, which is nearly 20% of the 2024 target of 90 fb-1. To reach this target, we need an average of about 0.8 fb-1 per day. Recently we have seen a record production of 1.23 fb-1 in just 24 hours, which demonstrates the LHC’s impressive potential to meet and possibly even exceed our target.

The predicted and achieved luminosity curves for ATLAS and CMS. The blue areas indicate the machine development (MD) periods, the red area the Van de Meer run, and the green one the technical stop. (Image: CERN)

Today, the LHC is performing the Van de Meer run, a crucial process used to calibrate the luminosity measurements in the four main LHC experiments (ALICE, ATLAS, CMS, LHCb).

This follows the first block of machine development (MD) sessions that took place on 13-15 May, during which experts conducted various tests and studies, including further investigation into the collimator hierarchy breaking that occurred in April.

On 18 May, the LHC will resume its primary task of producing luminosity. This production period will continue until the second MD block that is scheduled to start on 5 June and will be followed by a 5-day technical stop to carry out essential preventive and corrective maintenance before the summer holiday season. During the summer, the LHC will continue its luminosity production.

An overview of the beam availability of the different injectors and experimental facilities. The availability of each machine takes into account the non-availability of the upstream machines. (Image: CERN)

Not only is the LHC performing well, but the injector complex is also achieving a high level of beam availability for its experimental users. Physics in the injector complex kicked off on 22 March in the PS East Area. With the run scheduled to end on 2 December, the East Area has already completed over 20% of its 2024 run. Meanwhile the antimatter factory, which was the last facility in the injector complex to start beam operation, began delivering antiprotons to its experiments on 22 April, so just over 10% of its scheduled physics time for 2024 has now elapsed.

Linac4, the first link in the proton injector chain, has posted an average availability of 97.3% since its start after Long Shutdown 2 (LS2). It has posted availability of 95.7% so far in 2024, about 1.6% less than usual. This can mainly be attributed to a series of faults that led to the replacement of a klystron in March.

The injectors will continue their routine beam delivery to the experimental facilities until 12 June, when they too will interrupt beam production for a 4-day technical stop. Afterwards, it will be business as usual once more and the experiments can look forward to good beam delivery over the summer.

As we continue through the year, the achievements so far set a promising pace for the remaining months.

anschaef Thu, 05/16/2024 - 11:56 Byline Rende Steerenberg Publication Date Wed, 05/15/2024 - 11:52

CERN 70th anniversary exhibition at Geneva Airport

To honour its 70 years of contributions to scientific knowledge, technological innovation and international collaboration, CERN has put together a rich and diverse programme, at CERN and across its Member States, Associate Member States and beyond. This programme includes exhibitions, the first of which can now be visited at Geneva Airport as part of a collaboration between the two organisations. Inaugurated on 2 May, the exhibition’s three components will occupy the wall leading to the security check before entering the departure lounge, the “Panorama” terrace and the international terminal until autumn 2024.

Find out more on the “CERN and its neighbours” website.

anschaef Wed, 05/15/2024 - 12:09 Byline Zoe Nikolaidou Publication Date Wed, 05/15/2024 - 12:07

Computer Security: WhiteHat & Zebra trainings are back

Vulnerabilities and weaknesses lurk all over the digital place: unprotected file uploads, generous SQL queries, unfiltered input fields, disclosed passwords… They are the entry point for cross-site scripting, remote code execution or root privilege escalation, and the first step towards fostering the patient-zero-like compromise of a server, a service or the whole of CERN; the first step towards losing protected, restricted or confidential information; the first step that can result in mild to serious reputational damage for the Lab.

A plethora of means exists to protect against that. On the one hand, the Computer Security team is scanning for vulnerabilities and weaknesses in the hope of detecting them early and mitigating them fast. On the other, hand-in-hand with the Computer Security team, you, as an excellent software developer and experienced programmer, have followed the right courses to put in place a secure software programming and code development life-cycle, including sound system architecture and choice of components, apply best practices for managing and building your software in a secure fashion, and are aware of (and can avoid!) potential supply chain traps.

The CERN WhiteHat Challenge
While external students continue hacking into CERN and finding “juicy” stuff, we are glad to announce that the WhiteHatChallenge is back at CERN after a two-year hiatus. Designed as two half-days of training on ethics and integrity, focusing on penetration testing and vulnerability scanning, it should bring you up to speed on detecting suboptimal configurations and weaknesses in your web services and websites. While penetration testing is a marathon that requires lots of training and practice, this WhiteHat training should at least get you up and walking. It will cover the concepts for breaking into and abusing web applications, the use of the appropriate tools, and a Capture the Flag (CTF) tournament as a homework exercise to sharpen your skills. Hopefully it will give you a taste for becoming ─ after lots more fun training ─ an experienced penetration tester, hacker and participant in worldwide CTF tournaments! So, join us! All details for afternoon 1 and afternoon 2 can be found on Indico ─ no registration necessary.

Zebra Alliance Incident Response Exercise
And if you want to experience the pressure when the going really gets tough, see how incident response is conducted in reality. The Zebra Alliance has been hacked yet again (after previous attacks in 2022 and 2023)! And once again, it’s up to you and your peers in the room to figure out what happened. How did the attacker get in? What was their technique and intrusion vector? What’s their name (so the police can apprehend them)? No prior knowledge of security, incident response or even IT is needed. All you need is a laptop, the curiosity to dig and the eagerness to learn and tackle the challenge. As seats are limited, however, we kindly request that you register on Indico.

Have fun at both of these events! We hope to see you soon!

______

Do you want to learn more about computer security incidents and issues at CERN? Follow our Monthly Report. For further information, questions or help, check our website or contact us at Computer.Security@cern.ch.

anschaef Wed, 05/15/2024 - 11:33 Byline Computer Security team Publication Date Wed, 05/15/2024 - 11:29

Unveiling the science of tomorrow: FCC Study takes centre stage at La Roche-sur-Foron exhibition

The Future Circular Collider (FCC) study took centre stage at the International Fair of Haute-Savoie/Mont Blanc in La Roche-sur-Foron from 27 April to 6 May. An information booth, overflowing with interactive exhibits, captivating presentations and branded goodies, showcased the proposed research infrastructure’s scientific potential, alongside the applications of particle physics research in everyday contexts.

The FCC study envisages a next generation particle collider that could succeed the LHC at CERN, currently the most powerful collider in the world. The FCC aspires to offer the broadest possible exploration of the Universe's mysteries via high-precision and high-energy studies of the elementary constituents of matter and the forces governing their interactions.

The information booth at the International Fair of Haute-Savoie/Mont Blanc provided a unique opportunity for residents and visitors to articulate their views on the project and engage in constructive dialogue with the FCC team. Acknowledging the importance of transparency and community involvement, the project team is committed to openly addressing the hurdles inherent in such a monumental scientific endeavour. CERN’s participation in the International Fair of Haute-Savoie/Mont Blanc, enhanced by the valuable help of volunteers from the FCC team, resulted in meaningful discussions with more than 2000 members of the local community on topics ranging from the required technological advancements to sustainability measures.

More information about the FCC study:

https://fcc.web.cern.ch

https://fcc-faisabilite.eu

 

ndinmore Wed, 05/15/2024 - 10:27 Publication Date Wed, 05/15/2024 - 10:18

Hunting for millicharged particles at the LHC

The LHC family of experiments continues to grow. Alongside the four main experiments, a new generation of smaller experiments is contributing to the search for particles predicted by theories beyond the Standard Model, our current theory of particle physics. Recently, the FORMOSA demonstrator, which hunts for millicharged particles, has been installed in the cavern containing the FASER detector, 480 meters downstream from the ATLAS interaction point. It will now collect its first data.

Some theories predict the existence of millicharged elementary particles that would have a charge much smaller than the electron charge. If they exist, they would give clues to a theory beyond the Standard Model and could be considered as candidates for dark matter.

The FORMOSA demonstrator aims to prove the feasibility of the full experiment, which is intended to be installed in a proposed underground hall located about 620 metres away from the ATLAS interaction point. This experimental area – the Forward Physics Facility – is under study within the Physics Beyond Colliders initiative and is expected to host several experiments that will search for long-lived particles predicted by theories beyond the Standard Model. These particles would be produced by collisions at the centre of the ATLAS detector and would interact feebly with Standard Model particles. If approved, the experiments, among them the the proposed FASERν 2 and FLArE experiments, could start taking data when the High-Luminosity LHC is switched on in 2029.

The FORMOSA demonstrator comprises scintillators. When interacting with a charged particle, the scintillators emit photons that are subsequently converted into an electrical signal. While cosmic muons or those from ATLAS collisions may also strike the scintillators, millicharged particles typically deposit much less energy into each layer, distinguishing them from muons that traverse the detector.

“Initial studies with so-called no-beam data and source tests look already promising. This marks an important step towards achieving the goal to run the demonstrator this year and a great demonstration of the collaborative spirit of the projects within the Forward Physics Facility,” says project leader Matthew Citron from University of California, Davis.

Millicharged particles have become a particular focus of research in recent years. The MilliQan detector, located 33 meters away from the CMS interaction point, as well as MoEDAL-MAPP close to LHCb, started data taking during LHC Run 3. In 2020, a study carried out with a smaller demonstrator, MilliQan had ruled out the existence of millicharged particles for a range of masses and charges. Thanks to a higher volume of detection and its location in the far forward region of the LHC collisions, the FORMOSA experiment hopes to extend this search.

cmenard Tue, 05/14/2024 - 08:59 Byline Kristiane Bernhard-Novotny Publication Date Tue, 05/14/2024 - 16:20

Managing energy responsibly: CERN passes ISO 50001 audit The CERN Meyrin site. Continual improvement of energy management is one of the key pillars of the Organization’s strategy to minimise its impact on the environment. (Image: CERN)

All members of the CERN community are ambassadors for CERN’s commitment to environmentally responsible research. We therefore need to understand the implications and audits of the ISO 50001 certification – the international standard used to continually monitor and improve energy management.

CERN was awarded the ISO 50001 certification on 2 February 2023 for a period of three years, covering the entire perimeter of the Organization: all sites, activities and energies. CERN’s unique array of accelerators, detectors and infrastructure is primarily powered by electricity, accounting for about 95% of CERN’s total energy use. In addition, the Laboratory uses natural gas for heating, fuel for its fleet of vehicles, diesel for emergency generators and commercial liquid nitrogen for cooling. The ISO 50001 standard provides guidance and tools to improve energy performance and integrate energy management into our overall efforts to improve quality and environmental management.

In this context, mandatory annual surveillance audits are carried out by the French Association for Standardization, AFNOR. The first surveillance audit for CERN took place from 28 February to 1 March. It required weeks of preparation, including an internal pre-audit with EDF in January. The process included technical assessments of the Laboratory’s largest energy consumers. Focused interviews were held with Management, technical teams including cryogenics, electricity, cooling and ventilation, and support teams such as HR, procurement and HSE. Training and awareness raising of the entire CERN community is an important facet of the certification; a dedicated communications plan was therefore also assessed during the audit.

Conclusions were positive and identified no non-conformities. The auditor produced an official report at the end of April recommending that CERN maintain the certification without reserve: “Although recently deployed, the energy management system demonstrates a good level of maturity and is based on a well-structured organisation. Changes have been implemented since last year, both in the provision of resources and in the organisation of new steering bodies in conjunction with the energy team.”

“The conclusion of the audit highlights how well the requirements of the standard have been implemented across the Organization, from top management to technical teams,” notes CERN’s energy coordinator, Nicolas Bellegarde. “The auditor was particularly impressed with the energy improvement actions carried out by CERN’s services and official bodies in 2023, including the experiments, demonstrating that the overall energy performance has improved and remains a top priority for the Organization.” The next audit will be carried out in February 2025.

Share your feedback about energy saving and find out more about CERN’s approach to energy management and the ISO 50001 certification here: https://hse.cern/content/energy-management

The official AFNOR ISO 50001 certification logo. (Image: AFNOR)

 

ndinmore Wed, 05/08/2024 - 10:23 Byline HSE unit Publication Date Tue, 05/14/2024 - 10:17

Accelerator Report: Keeping cool and adapting to challenges

On 29 April, the LHC team received the green light for the final step in the intensity ramp-up and added the last 141 bunches to obtain a full machine with 2352 bunches in each beam.

The 2024 beam commissioning and subsequent intensity ramp-up to about 1900 bunches per beam went very smoothly and, as mentioned in my last report, we were well ahead of schedule. Today, we are still on schedule, but some of the margin has been consumed by two main challenges that were encountered in the last two weeks, which have led to some changes to the filling scheme.

The first challenge occurred on 17 April, when the machine was filled with 1791 bunches per beam. Abnormal beam losses were observed in the collimation region (Point 7) during the final stage of the “squeeze process”, where the beam size in the experiments is reduced to increase the number of collisions.

The collimation system is designed to absorb particles that stray from their trajectory and could hit sensitive components of the accelerator, such as the superconducting magnets, and interfere with their operation. To avoid this happening, Point 7 is equipped with primary and secondary collimators.

The primary collimators, which are situated close to the beam, intercept the deviating beam particles (also called the primary particles), absorb part of their energy and redirect them to the secondary collimators. The secondary collimators, which are further away from the beam, then absorb these particles.

On 17 April, a breaking of the collimation hierarchy was observed: a secondary collimator started playing the role of a primary collimator for certain particles. This can damage the secondary collimator, as it is not designed to intercept the primary particles. Many studies are ongoing to understand the issue, especially as this effect is not observed when the machine is filled with only a few bunches, which is the case during the beam commissioning, when the LHC team validates the collimation hierarchy. In the meantime, the “squeeze” has been limited, sacrificing a few percentage points of luminosity, but avoiding potential damage to the machine parts.

The second challenge arose on 22 April, when the 1.9-Kelvin refrigeration unit A (QUARC A) at Point 8 stopped working due to a faulty cold compressor. Consequently, the cryogenics team switched to the spare unit B (QUARC B), which was in cold standby. Unfortunately, the QUARC B is less efficient, resulting in a loss of cooling capacity. A good cooling capacity is needed in sector 7-8 to extract the heat load induced by the electron cloud. Therefore, the number of bunches per beam was reduced from 1983 to 1215 the day after. On 24 April, the cryogenics team was ready to switch back to QUARC A and the cooling capacity was recovered by 25 April. A first fill with 1419 bunches was put in collision, successfully followed by a 1959-bunch fill during the night.

However, to reduce the heat load and leave the possibility open to further increase the total number of bunches, the injectors switched from bunch trains containing three batches of 48 bunches each to bunch trains with three batches of 36 bunches each. With this bunch pattern, the number of gaps in the bunch trains increases and the electron cloud production in the LHC decreases, hence the heat load to the cryogenics system.

LHC Page 1 on 30 April, with two successful fills with 2352 bunches per beam each. On the left, we see beams 1 and 2 in blue and red respectively. On the right, the luminosity of the four main LHC experiments. (Image: CERN)

On 26 April, the next intensity step was made, increasing the number of bunches from 1959 to 2211 bunches per beam. Over the following weekend, these 2211 bunches per beam, together with an excellent machine availability of 70% and beams in collision close to 58% of the time, resulted in an accumulation of 2.5 fb-1, which corresponds to a very encouraging 0.83 fb-1 per 24 hours.

On 29 April, after careful analysis, the cryogenics team concluded that there was indeed margin in the cryogenic cooling system to perform the final intensity step and increase to 2352 bunches per beam, still using the three batches of 36 bunches from the SPS.

Collisions with 2352 bunches per beam and a limited “squeeze” of the beam will be the default running mode for the time being, until the collimation hierarchy issue is understood and resolved. Despite this, the luminosity production is very good and looks promising for the remainder of the year.

anschaef Fri, 05/03/2024 - 10:41 Byline Rende Steerenberg Publication Date Fri, 05/03/2024 - 10:37

CERN and ENEA plan to develop liquid-metal technologies for particle accelerators

CERN has established a partnership with ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development, to develop new beam-intercepting devices using liquid-lead technologies.

This development could enhance the performance and reliability of particle accelerators worldwide and is essential for proposed future projects at CERN, such as the Future Circular Collider (FCC) and Muon Collider. FCC-ee collisions of intense electron and positron beams would produce a high-energy photon beam carrying up to 500 kW of power on each side of the interaction regions; liquid lead is an excellent and compact candidate to safely absorb this photon beam. The Muon Collider would need proton beams to interact with a target to supply muons. If the target was solid graphite, proton beams would be limited to 2 MW of power; a liquid-lead target, however, would be able to withstand more powerful proton beams and hence produce more muons. Looking at the intensity frontier, liquid-lead targets could also be applied to the production of neutrons and feebly interacting particles.

“By pooling our resources and expertise, we are confident that we can accelerate the development of liquid-metal-based beam-intercepting devices”, explains Marco Calviani, Head of the Target, Collimators and Dumps section at CERN. “This collaboration will unlock an enabling technology for new possibilities in fundamental research, applied science and applications for the benefit of society.”

“Together with CERN, we are well positioned to use our know-how of liquid-lead-based technology to push the boundaries of innovation and pave the way for transformative advancements in accelerator technology,” continues Mariano Tarantino, Head of the Nuclear Energy Systems Division at ENEA.

anschaef Tue, 04/30/2024 - 13:17 Byline Kate Kahle Publication Date Tue, 04/30/2024 - 13:14

Enhancing safety: improving seismic risk assessments

CERN is located in a particularly complex geological setting, which also happens to be prone to earthquakes. Seismic events of a certain magnitude have the potential to inflict substantial damage or lead to equipment failure, which naturally poses a risk to both personnel and assets.

Complex research infrastructures like CERN often boast unique technologies and equipment hidden deep underground. This presents a unique set of challenges, since there are currently no regulations covering either the structural systems or the subterranean infrastructure, resulting in a lack of established procedures for conducting seismic risk assessments. Regarding radiation shielding in particular, the prevailing approach frequently involves using high-density blocks to achieve the required level of shielding, an exceptional solution that is not regulated by European or Swiss norms.

Examples of concrete block configurations at CERN: beam line shielding in the Neutrino Platform trenches (left) and Proton Synchrotron East Area facility (right). (Image: CERN)

To bridge this gap and identify feasible solutions, CERN’s HSE unit and SCE and BE departments have been carrying out dedicated research for the last three years, in collaboration with the Swiss Federal Institute of Technology Lausanne (EPFL), the California Institute of Technology (Caltech), the University of Montpellier and the European Centre for Training and Research in Earthquake Engineering (EUCENTRE). Together, they have performed full-scale seismic tests on a large shaking table at EUCENTRE to observe the dynamic behaviour of stacked concrete blocks. The numerical models were calibrated using the test data, enabling the simulation of the seismic behaviour of real block configurations at CERN. This research provides the basis for a novel methodology for the seismic risk assessment of this kind of structure, which is currently applied as a routine activity in areas such as the PS, SPS and LHC complex. Furthermore, the research has resulted in a clear procedure for calibrating the numerical models, as well as a methodology and risk assessment process that will be applied to future block configurations in new experiments and facilities to be built at CERN.

Shaking table tests were carried out at EUCENTRE in Pavia, Italy. The left image shows geometrical details, with dimensions in mm, of the specimen (middle image). The right image shows the tested accelerograms, which are compatible with the seismic design requirements for several ordinary buildings in Switzerland. (Image: CERN)

The collaboration was recently awarded the “Best Paper Award 2023” by the Engineering Structures journal for the paper entitled “Shaking table tests for seismic stability of stacked concrete blocks used for radiation shielding”.  According to Marco Andreini, senior structural engineer in the HSE-OHS group, “this award recognises the significance and impact of our work, not only for CERN but also for other similar complex infrastructures around the world.”

Looking ahead, it is hoped that this novel approach can be used by other large research infrastructures and beyond.

anschaef Tue, 04/30/2024 - 11:41 Byline HSE unit SCE department Publication Date Thu, 05/02/2024 - 10:00

MADMAX at the forefront of the search for axions

Imagine a set of classic Matryoshka dolls, each containing a smaller doll inside it. MADMAX – not the movie, but an experiment hosted in CERN’s largest experimental area, the SPS North Area – employs a similar technique to search for axions, a leading candidate for dark matter.

MADMAX (Magnetized Disk and Mirror Axion experiment) consists of multiple dielectric disks and a focusing mirror called the booster. Like the smaller dolls nestled within the larger ones, the booster is surrounded by an inner and outer vessel. There is a vacuum between these vessels to allow physics data taking at very low temperatures. Finally, the giant Morpurgo magnet serves as the outermost doll, providing the magnetic field essential for the experiment's operation. The Morpurgo magnet is the largest warm bore dipole in the world, with a 1.6-tesla magnetic field, and is mainly used to test subdetectors of the ATLAS experiment.

In February and March this year, the two new prototypes of MADMAX have come into action to collect physics data at room temperature and, for the first time, at close to liquid helium temperature.

“We used Closed Booster 200, our new 200-mm-disk prototype, to collect physics data at room temperature, and Closed Booster 100, our 100-mm-disk prototype, to collect data close to the temperature of liquid helium, at around 10 K (about -263 °C). At this temperature, the background thermal noise is lower than at room temperature, significantly increasing the sensitivity to axions,” explains Pascal Pralavorio, a physicist from the MADMAX collaboration.

The collected data was discussed in the MADMAX collaboration meeting held at CERN in March this year. The data is currently being analysed and the collaboration looks forward to sharing its physics results in the future.

In the last decade, physicists have explored several experimental approaches, such as the CERN Axion Solar Telescope, to search for axions. To date, no experiment has succeeded in finding them. If axions are discovered, it would have profound implications for our understanding of both particle physics and cosmology. Firstly, it would validate the existence of a new particle predicted by theorists more than 40 years ago, confirming our understanding of fundamental forces in the Universe. Secondly, since axions are considered a leading candidate for dark matter, their discovery could provide a direct explanation for this elusive substance that makes up a significant portion of the Universe.

MADMAX is a relatively young collaboration that started in 2017. Since 2020, CERN has provided the Morpurgo magnet to the experiment during technical stops, when the SPS beam is shut down. MADMAX benefits from a strong participation from across CERN for cryogenics, magnets, electrical power convertors, and safety and operations. It is one of the few experiments at CERN that are well suited for tests independent of beam time, as it does not require a particle beam from an accelerator.

The MADMAX collaboration is currently discussing with the SPS Committee the possibility of using the Morpurgo magnet for another programme of data taking during the Long Shutdown 3 of CERN’s accelerator complex, which will take place from 2026 to 2028.

ckrishna Tue, 04/30/2024 - 09:43 Byline Chetna Krishna Publication Date Tue, 04/30/2024 - 09:30

Probing matter–antimatter asymmetry with AI The open CMS detector during the second long shutdown of CERN’s accelerator complex. (Image: CERN)

When we look at ourselves in a mirror, we see a virtual twin, identical in every detail except with left and right inverted. In particle physics, a transformation in which charge–parity (CP) symmetry is respected swaps a particle with the mirror image of its antimatter particle, which has opposite properties such as electric charge.

The physical laws that govern nature don’t respect CP symmetry, however. If they did, the Universe would contain equal amounts of matter and antimatter, as it is believed to have done just after the Big Bang. To explain the large imbalance between matter and antimatter seen in the present-day Universe, CP symmetry has to be violated to a great extent. The Standard Model of particle physics can account for some CP violation, but it is not sufficient to explain the present-day matter–antimatter imbalance, prompting researchers to explore CP violation in all its known and unknown manifestations.

One way CP violation can manifest itself is in the “mixing” of electrically neutral mesons such as the strange beauty meson, which is composed of a strange quark and a bottom antiquark. These mesons can travel macroscopic distances in the Large Hadron Collider (LHC) detectors before decaying into lighter particles, and during this journey they can turn into their corresponding antimesons and back.

This phenomenon, called meson mixing, could be different for a meson turning into an antimeson versus an antimeson turning into a meson, generating CP violation. To see if that’s the case, researchers need to count how many mesons or antimesons survive a certain duration before decaying, and then repeat the measurement for a given range of durations. To do so, they have to separate mesons from antimesons, a task called flavour tagging. This task is crucial to pinning down CP violation in meson mixing and in the interference between meson mixing and decay.

At a seminar held recently at CERN, the CMS collaboration at the LHC reported the first evidence of CP violation in the decay of the strange beauty meson into a pair of muons and a pair of electrically charged kaons.

By deploying a new flavour-tagging algorithm on a sample of about 500 000 decays of the strange beauty meson into a pair of muons and a pair of charged kaons, collected during Run 2 of the LHC, the CMS collaboration measured with improved precision the parameter that determines CP violation in the interference between this meson’s mixing and decay. If this parameter is zero, CP symmetry is respected. The new flavour-tagging algorithm is based on a cutting-edge artificial intelligence (AI) technique called a graph neural network, which performs accurate flavour tagging by gathering information from the particles surrounding the strange beauty meson and those being produced alongside it.

The collaboration then combined the result with its previous measurement of the parameter based on data from Run 1 of the LHC. The combined result is different from zero and is consistent with the Standard Model prediction and with previous measurements from CMS and the ATLAS and LHCb experiments.

Notably, the combined result is comparable in precision to the world’s most precise measurement of the parameter, obtained by LHCb, a detector specifically designed to perform measurements of this kind. Moreover, the result has a statistical significance that crosses the conventional “3 sigma” threshold, providing the first evidence of CP violation in the decay of the strange beauty meson into a pair of muons and a pair of charged kaons.

The result marks a milestone in CMS’s studies of CP violation. Thanks to AI, CMS has pushed the boundary of what its detector can achieve in the exploration of this fundamental matter–antimatter asymmetry.

Find out more on the CMS website.

abelchio Tue, 04/30/2024 - 08:54 Byline CMS collaboration Publication Date Tue, 04/30/2024 - 08:53

Alice Bucknell wins the second edition of the Collide Copenhagen residency award

Following an international open call launched in collaboration with Copenhagen Contemporary in January, Arts at CERN announced today that the artist Alice Bucknell is the recipient of the second Collide Copenhagen residency award.

Established in 2012, Collide is Arts at CERN’s international residency award, where the residency is a unique opportunity for artists working in the crossovers between art, science and technology to immerse themselves in the vibrant environment of the Laboratory and engage in dialogue with CERN's scientific community.

Collide Copenhagen is a three-year collaboration framework between CERN and Copenhagen Contemporary. It supports artistic research into art, science and technology, with a residency taking place annually from 2023 to 2025. For this edition, Collide received 718 entries from 91 different countries.

Bucknell will embark on a two-month residency, split between CERN and Copenhagen Contemporary, to develop their proposal “Small Void”. Drawing inspiration from CERN’s particle physics research and the intricate ecosystems of Earth, the project seeks to explore the relationships between life and intelligence at the micro-scale through game worlds.

At CERN, Bucknell will work alongside scientists to explore artistically microscopic black holes – hypothetical entities with the potential to unlock new questions about physics and extra dimensions. Delving into how researchers envision the “micro” through scientific imaging, the artist will seek to imagine and transform these hypothetical objects within the game and incorporate visualisations inspired by CERN experiments.

In Copenhagen, the focus will shift to Earth-bound life forms. Inspired by the Assistens Cemetery’s lichen, Bucknell will explore these resilient ecosystems that exist outside a binary perception of life and aliveness. By integrating both elements as narrative agents, the game will aim to spark a dialogue about microcosmic intelligence and life.

With the support of the curatorial teams of Arts at CERN and Copenhagen Contemporary, a phase of designing and producing a new artwork will follow the residency. Together with the 2023 awardee, Dutch artist Joan Heemskerk, and the winner of next year’s edition, the three awardees of Collide Copenhagen will become part of an exhibition at Copenhagen Contemporary in 2025.

“I am thrilled to witness Collide’s continued success in attracting artists who brilliantly merge physics with key aspects of our contemporary culture. Alice Bucknell’s bold approach to science will undoubtedly inspire CERN scientists to delve into questions about the limits of knowledge and our understanding of the world. It’s also exciting to see how Collide strengthens the partnership between CERN and Copenhagen Contemporary as we enter the second year of our collaboration, fostering innovative art projects within our communities in Geneva and Copenhagen,” said Mónica Bello, Head of Arts at CERN.

“With a highly original perspective on the deep interweaving of technology and nature in contemporary culture, Alice Bucknell invites us to be insiders in a gameplay where nature, ecology and the environment are reimagined. At Copenhagen Contemporary we are beyond excited to take a deep dive through Bucknell’s speculative ecological lens and to continue our flourishing collaboration with Arts at CERN in this second edition of Collide Copenhagen,” said Marie Laurberg, Director of Copenhagen Contemporary.

About Arts at CERN  

About Copenhagen Contemporary 

About Alice Bucknell

Alice Bucknell is an artist with a particular interest in game engines and speculative fiction. Their recent work has focused on creating cinematic universes within game worlds, exploring the affective dimensions of video games as interfaces for understanding complex systems, relations and forms of knowledge.

About the jury

The jury consisted of Mónica Bello, Curator and Head of Arts at CERN; Marie Laurberg, Director of Copenhagen Contemporary; Ana Prendes, Assistant Curator of Arts at CERN; and Hannah Redler-Hawes, independent curator.

 

ldragu Mon, 04/29/2024 - 13:49 Publication Date Mon, 04/29/2024 - 14:00

Adding CERN to the shopping list A CERN guide takes the phrase “hands-on activity” literally at the International Geneva exhibition in Balexert shopping centre (Image: CERN)

Busy shoppers put trolleys to one side to visit the CERN stand at the “Genève internationale” exhibition at Balexert, the largest shopping centre in Geneva, from 16 to 20 April.

Through practical activities and chats, CERN guides helped visitors to discover more about CERN’s research, while highlighting what our new visitor centre, CERN Science Gateway, has to offer.

“Thank you to all the CERN guides who joined the stand over the five days of the exhibition,” says François Briard, head of visitor and event operations. “Your enthusiasm was fantastic and contagious.”

Interested in becoming a CERN guide? Find out more here.

See more photos in the slideshow below:

katebrad Fri, 04/26/2024 - 12:35 Byline Kate Kahle Publication Date Thu, 05/02/2024 - 14:21

MoEDAL zeroes in on magnetic monopoles The MoEDAL detector (Image: CERN)

The late physicist Joseph Polchinski once said the existence of magnetic monopoles is “one of the safest bets that one can make about physics not yet seen”. In its quest for these particles, which have a magnetic charge and are predicted by several theories that extend the Standard Model, the MoEDAL collaboration at the Large Hadron Collider (LHC) has not yet proven Polchinski right, but its latest findings mark a significant stride forward. The results, reported in two papers posted on the arXiv preprint server, considerably narrow the search window for these hypothetical particles.

At the LHC, pairs of magnetic monopoles could be produced in interactions between protons or heavy ions. In collisions between protons, they could be formed from a single virtual photon (the Drell–Yan mechanism) or the fusion of two virtual photons (the photon-fusion mechanism). Pairs of magnetic monopoles could also be produced from the vacuum in the enormous magnetic fields created in near-miss heavy-ion collisions, through a process called the Schwinger mechanism.

Since it started taking data in 2012, MoEDAL has achieved several firsts, including conducting the first searches at the LHC for magnetic monopoles produced via the photon-fusion mechanism and through the Schwinger mechanism. In the first of its latest studies, the MoEDAL collaboration sought monopoles and high-electric-charge objects (HECOs) produced via the Drell–Yan and photon-fusion mechanisms. The search was based on proton–proton collision data collected during Run 2 of the LHC, using the full MoEDAL detector for the first time.

The full detector comprises two main systems sensitive to magnetic monopoles, HECOs and other highly ionising hypothetical particles. The first can permanently register the tracks of magnetic monopoles and HECOs, with no background signals from Standard Model particles. These tracks are measured using optical scanning microscopes at INFN Bologna. The second system consists of roughly a tonne of trapping volumes designed to capture magnetic monopoles. These trapping volumes – which make MoEDAL the only collider experiment in the world that can definitively and directly identify the magnetic charge of magnetic monopoles – are scanned at ETH Zurich using a special type of magnetometer called a SQUID to look for any trapped monopoles they may contain.

In their latest scanning of the trapping volumes, the MoEDAL team found no magnetic monopoles or HECOs, but it set bounds on the mass and production rate of these particles for different values of particle spin, an intrinsic form of angular momentum. For magnetic monopoles, the mass bounds were set for magnetic charges from 1 to 10 times the fundamental unit of magnetic charge, the Dirac charge (gD), and the existence of monopoles with masses as high as about 3.9 trillion electronvolts (TeV) was excluded. For HECOs, the mass limits were established for electric charges from 5e to 350e, where e is the electron charge, and the existence of HECOs with masses ranging up to 3.4 TeV was ruled out.

“MoEDAL’s search reach for both monopoles and HECOs allows the collaboration to survey a huge swathe of the theoretical ‘discovery space’ for these hypothetical particles,” says MoEDAL spokesperson James Pinfold.

In its second latest study, the MoEDAL team concentrated on the search for monopoles produced via the Schwinger mechanism in heavy-ion collision data taken during Run 1 of the LHC. In a unique endeavour, it scanned a decommissioned section of the CMS experiment beam pipe, instead of the MoEDAL detector’s trapping volumes, in search of trapped monopoles. Once again, the team found no monopoles, but it set the strongest-to-date mass limits on Schwinger monopoles with a charge between 2gD and 45gD, ruling out the existence of monopoles with masses of up to 80 GeV.

“The vital importance of the Schwinger mechanism is that the production of composite monopoles is not suppressed compared to that of elementary ones, as is the case with the Drell–Yan and photon-fusion processes,” explains Pinfold. “Thus, if monopoles are composite particles, this and our previous Schwinger-monopole search may have been the first-ever chances to observe them.”

The MoEDAL detector will soon be joined by the MoEDAL Apparatus for Penetrating Particles, MAPP for short, which will allow the experiment to cast an even broader net in the search for new particles.

abelchio Fri, 04/26/2024 - 10:45 Byline Ana Lopes Publication Date Fri, 04/26/2024 - 10:24

Capturing CERN’s diverse community Showcasing the diversity of jobs, nationalities and cultures within the CERN community, the photo includes representatives from ATS, BE, EN, EP, HSE, HR, IPT, IR, IT, PF, SY, TE and TH. (Image credit: Yann Arthus-Bertrand)

Members of the CERN community are now part of the project Les Français et Ceux qui vivent en France (The French and those who live in France) by renowned French photographer Yann Arthus-Bertrand.

Known for his book Earth from Above and his films Home and Human, Arthus-Bertrand has also been photographing the people of France for more than 30 years for his project The French and those who live in France. During a discussion with French demographer and historian Hervé Le Bras in 2023, he was prompted to enrich and complete this project. Throughout 2024, he is touring France to capture the diversity of the French population.

Arthus-Bertrand expressed an interest in photographing members of the CERN community residing in the Pays de Gex area of France, and the photoshoot took place on 8 March, during the Festival des Confrontations Photo 2024.

An internal call to the community resulted in more than 40 registrations in the first five minutes and 180 in total before registrations were closed. Participants were selected from among the first people to respond from each department.

“Yann was very kind”, says Zoe Nikolaidou who coordinated the collaboration. “He liked that we were wearing work clothes, including hardhats and hi-vis jackets, but he wasn’t so keen on us wearing our CERN access passes,” she laughs. “He didn’t find them very photogenic!”

The project will result in the publication of one or more books and a touring exhibition across France.

katebrad Thu, 04/25/2024 - 12:00 Byline Kate Kahle Publication Date Fri, 04/26/2024 - 17:19

Computer Security: Pay per vulnerability

Remember CERN’s WhiteHat Challenge, in which we gave people outside CERN permission to hack into the Organization as long as they abided by a short set of rules and in which CERN trained its own staff and users in penetration testing and vulnerability scanning? While our “Day of the open firewall” to ease the life of penetration testes was of course only an April Fool’s hoax, we are still and seriously aiming to bring vulnerability scanning and penetration testing to the next (professional) level…

Actually, vulnerabilities lurk everywhere. In the operating system of your desktop PC, laptop or smartphone; in the software programs you run; in the applications and code you develop; in the web pages, web frameworks and web servers you use. Critical for assessing the risk of each vulnerability is the exploitability: can an attacker gain direct benefit from that vulnerability for their evil deed? Which hurdles need to be overcome beforehand? In that sense, computing services directly connected or visible to the internet are the most risky, as each potential vulnerability can be directly exploited by attackers (who are legion on the internet). Hence, it is essential that this attack sphere – all servers with openings in CERN’s outer perimeter firewall towards the internet – is as protected as possible and all known vulnerabilities are eradicated. That’s why CERN created the WhiteHat Challenge giving computer science and IT security students as well as interested CERN staff and users the chance to hack into CERN.

Now, in order to be even more thorough and delve even deeper, in order to find more (sophisticated) vulnerabilities, and just in time for the 2024 spring clean, the Computer Security team decided to tap into a larger pool of professionals and engage with ethical hackers and launched a three (and a half) staged approach towards improving the security of CERN’s Internet presence and beyond. Subject to ground rules, code of ethics, and scoping, the hackers are permitted to penetrate into CERN’s infrastructure (as outlined in the contractual scope and ethically without causing any damage) in order to identify vulnerabilities and weaknesses:

1. In this first stage, we aim at a broad vulnerability scanning by external professionals of the whole Internet presence of CERN (and by an eager internal student in parallel) in order to identify the “low hanging fruits” (if any) and get them fixed;
2. Afterwards, during the second stage, an in-depth penetration testing of key and core services performed by ethical hackers shall verify that our protective means are solid and robust, and that more complex attack vectors yield into nothing;
3. Once stages 1 and 2 are terminated, and all findings are mitigated, the Computer Security Team will team up with a larger group of ethical hackers through a so-called “Bug Bounty Program”, like HackerOne or BugBountySwitzerland.

While the costs for the first two stages are free of charge and covered by a flat budget provided by CERN’s Computer Security Team, the third one shall be “paid per vulnerability found” ─ the so-called “Bug Bounty” as outlined in the contract ─ by the owner of the corresponding vulnerable system. It is this Bounty which creates an incentive for an ethical hacker reporting first a finding as each finding supports their living: For example 100 CHF for identifying an easy cross-site scripting problem; 500 CHF for obtaining root access to a server; 1000 CHF for finding credentials that allow them to move laterally towards other internal services; 5000 CHF for compromising a service that allows them to configure other services (like Puppet, Git, LDAP or Active Directory).

However, that Bounty also creates an incentive for you! Like the shared responsibility for computer security at CERN, the Bug Bounty costs will also be shared, and shall be born by your (group’s or departmental) budget if you own, manage or run a computing resource, service, system, device or website that is found by an ethical Bug Bounty hacker to be vulnerable or weak, and if that finding is linked to negligence of general security standards (bad programming practices, unpatched systems, suboptimal handling of secrets and passwords, nit using CERN’s Single Sign-On etc.), … Time for incentive to get it right from the beginning! It’s up to you whether you are ready to pay any incurring costs of vulnerable resources found by an ethical hacker, or to invest a bit more in getting your system and service, your devices and websites up to general standards. The CERN Computer Security Team is happy to help you with this.

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Do you want to learn more about computer security incidents and issues at CERN? Follow our Monthly Report. For further information, questions or help, check our website or contact us at Computer.Security@cern.ch.

anschaef Wed, 04/24/2024 - 12:15 Byline Computer Security team Publication Date Wed, 04/24/2024 - 12:11

CERN's edge AI data analysis techniques used to detect marine plastic pollution

Earth Observation (EO) and particle physics research have more in common than you might think. In both environments, whether capturing fleeting particle collisions or detecting transient traces of ocean plastics, rapid and accurate data analysis is paramount.

On this Earth Day, as we reflect on our responsibility to reduce plastics for the benefit of our society and all life on our planet, we are excited to present a new EU project, Edge SpAIce. It applies CERN’s cutting-edge AI technology to monitor the Earth’s ecosystems from space in order to detect and track plastic pollution in our oceans.

“In particle physics, the trigger system plays a critical role by swiftly determining which data from the particle detector should be retained, given that only a small fraction of the 40 million collision snapshots taken each second can be recorded. As the data influx at the Large Hadron Collider (LHC) has grown significantly over the years, physicists and computer scientists are continually innovating to upgrade this process - and this is where AI technology comes in,” says Sioni Summers, a CERN physicist working on the CMS experiment at the LHC, who is supervising this work.

Edge SpAIce is a collaborative endeavour involving CERN, EnduroSat (BG) and NTU Athens (GR) and coordinated by AGENIUM Space. Its aim is to develop a specially designed on-board system for satellites that will make it possible to acquire and process high-resolution pictures using a DNN (Deep Neural Network). The system will use the “edge AI” approach, in which data is processed in near real-time directly on the satellite, mirroring the efficient filtering of LHC data in particle detectors at CERN. This means that it is not necessary to transmit all of the captured data back to Earth but only the relevant information - in this case, the presence of marine plastic litter. The system will also be deployed on FPGA hardware developed in Europe, which will improve competitiveness. This could open the door for a whole new market for EO services and applications.

As modern life increasingly relies on technology, the solution that the project offers adeptly addresses the growing demand for data processing and the rapid expansion of EO satellites. By eliminating the need for heavy processing in Earth-based data centres, it not only reduces the carbon footprint but also helps to relieve the burden on these facilities. The innovative approach holds potential for broader applications in domains such as agriculture, urban planning, disaster relief and climate change. Additionally, this technology will provide environmental scientists and policymakers with invaluable data for targeted clean-up operations. It will advance our understanding of plastic pollution patterns, thereby enhancing our capacity to address environmental challenges effectively.

“AGENIUM Space is thrilled to have found synergies with CERN in developing innovative solutions for our planet’s future,” said Dr Andis Dembovskis, a business development executive with AGENIUM Space.

The Edge SpAIce project exemplifies how creative thinking by partners across diverse fields can lead to a collaborative knowledge transfer project that tackles major societal challenges. To discover how other CERN knowledge transfer and innovation projects are making a positive impact on the environment, please visit: https://kt.cern/environment

ptraczyk Mon, 04/22/2024 - 16:28 Byline Marzena Lapka Publication Date Mon, 04/22/2024 - 16:23

SHiP sets sail to explore the hidden sector

The SHiP (Search for Hidden Particles) collaboration was in high spirits at its annual meeting this week. Its project to develop a large detector and target to be installed in one of the underground caverns of the accelerator complex has been accepted by the CERN Research Board. Thus, SHiP plans to sail to explore the hidden sector in 2031. Scientists hope to capture particles that interact very feebly with ordinary matter – so feebly, in fact, that they have not yet been detected.

This group of hypothetical particles includes dark photons, axions and axion-like particles, heavy neutral leptons and others. These particles, which could be among the dark matter, particles, are predicted by several theoretical models that extend beyond the Standard Model, the current theory describing elementary particles and the forces that unite them.

Although very solid, the Standard Model does not explain certain phenomena. The particles predicted by the Model – in other words, the ordinary matter that we know – account for just 5% of the Universe. The rest is thought to be unknown matter and energy, which scientists refer to as dark matter and dark energy. Their effects can be observed in the Universe, but their nature is a mystery that a growing number of experiments are trying to uncover.

This is where SHiP comes in. The idea is simple: the more particles that are produced, the greater the chances of finding feebly interacting particles. A high-intensity proton beam from the Super Proton Synchrotron (SPS) accelerator will be repeatedly sent to a target, a large metal block, producing a vast number of particles. Among them, scientists hope to find particles from the hidden sector. Thanks to the very high beam intensity, SHiP will be more sensitive than the existing experiments.

Another special feature of SHiP is that its detectors will be placed several tens of metres away from the target in order to detect relatively long-lived particles and eliminate “background noise”, in other words, particles such as muons that could interfere with the detection of long-lived particles. The experiment is equipped with a magnet system to divert the flow of muons and a large 50 m-long chamber in which the particles of interest can decay into known particles.

The experiment therefore complements the large LHC experiments, whose detectors surround the collision point and are unable to study the feebly interacting particles that travel several tens of metres before transforming. Theoretical models predict that the lower their mass and the weaker their coupling (the intensity of the interaction), the longer the lifetime of these particles. SHiP will therefore be sensitive to particles with relatively low masses.

In their journey through the detector, these particles could either disintegrate into known particles or collide with an atom of ordinary matter, which would also produce particles. The SHiP detectors have been designed to detect their signals.

Beyond the hypothetical dark-matter particles, SHiP will also study neutrinos which, despite being known particles of the Standard Model, are difficult to intercept and still hold many mysteries.

The target and the experiment will be installed in an existing underground cavern at CERN and supplied by a beam line from the SPS, CERN’s second largest accelerator, which supplies several experiments and pre-accelerates particles for the LHC.

The target is a complex device that is more like a beam dump than a conventional fixed target. Under study for several years, it is a 1.5-metre-thick block made of several different metals in order to produce the specific particles required by SHiP and fitted with a cooling and shielding system.

Part of the SHiP collaboration during its annual meeting, which was held at CERN this week. (Image: Marina Cavazza/CERN)

 

cmenard Thu, 04/18/2024 - 16:35 Byline Corinne Pralavorio Publication Date Fri, 04/19/2024 - 14:05

ALICE gets the green light for new subdetectors

Two detector upgrades of ALICE, the dedicated heavy-ion physics experiment at the Large Hadron Collider (LHC), have recently been approved for installation during the next long shutdown of the LHC, which will take place from 2026 to 2028. The first one is an upgrade of the innermost three layers of the Inner Tracking System (ITS3), and the second is a new forward calorimeter (FoCal), optimised for photon detection in the forward direction of the ALICE detector.

High-energy collisions of heavy ions like lead nuclei at the LHC recreate quark–gluon plasma: the hottest and densest fluid ever studied in a laboratory. Besides studying the properties of quark–gluon plasma, the ALICE programme covers a broad array of topics involving strong interaction, such as determining the structure of nuclei and the interactions between unstable particles, as presented in "A journey through the quark-gluon plasma and beyond".

Inner Tracking System (ITS3)

ALICE’s current Inner Tracking System, installed for the ongoing LHC run, is the world’s largest pixel detector to date, with 10 m2 of active silicon area and nearly 13 billion pixels. The new Inner Tracking System, ITS3, builds on the successful use of monolithic active pixel sensors and takes this concept to the next level.

“ALICE is like a high-resolution camera, capturing intricate details of particle interactions. ITS3 is all set to boost the pointing resolution of the tracks by a factor of 2 compared to the current ITS detector,” said Alex Kluge and Magnus Mager, the project leaders of ITS3. “This will strongly enhance the measurements of thermal radiation emitted by the quark–gluon plasma and provide insights into the interactions of charm and beauty quarks when they propagate through the plasma.”

The ITS3 sensors are 50 µm thick and as large as 26×10 cm2. To achieve this, a novel stitching technology was used to connect individual sensors together into a large structure. These sensors can now be bent around the beampipe in a truly cylindrical shape. The first layer will be placed only 2 mm from the beampipe and 19 mm from the interaction point. It can now be cooled by air instead of water and has a much lighter support structure, significantly reducing the materials and their effect on the particle trajectories seen in the detector.

 

Forward Calorimeter (FoCal)

The FoCal detector consists of an electromagnetic calorimeter (FoCal-E) and a hadronic calorimeter (FoCal-H). FoCal-E is a highly granular calorimeter composed of 18 layers of silicon pad sensors, each as small as 1×1 cm2, and two additional special layers with pixels of 30×30 μm2. FoCal-H is made of copper capillar tubes and scintillating fibres.

“By measuring inclusive photons and their correlations with neutral mesons, and the production of jets and charmonia, FoCal offers a unique possibility for a systematic exploration of QCD at small Bjorken-x. FoCal extends the scope of ALICE by adding new capabilities to explore the small-x parton structure of nucleons and nuclei,” said Constantin Loizides, project leader of FoCal at the ALICE collaboration.

The newly built FoCal prototypes have recently been tested with beams in the CERN accelerator complex, at the Proton Synchrotron and Super Proton Synchrotron, demonstrating their performance in line with expectations from detector simulations.

The ITS3 and FoCal projects have reached the important milestone of completing their Technical Design Reports, which were endorsed by the CERN review committees in March 2024. The construction phase of ITS3 and FoCal starts now, with the detectors due to be installed in early 2028 in order to be ready for data taking in 2029.

ckrishna Thu, 04/18/2024 - 14:52 Byline ALICE collaboration Publication Date Thu, 04/25/2024 - 10:00