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Accelerator Report: Protons or Easter eggs? Let’s hope for both

Τετ, 27/03/2024 - 16:59
Accelerator Report: Protons or Easter eggs? Let’s hope for both

Beam commissioning is progressing well across the entire accelerator complex, with initial completion achieved in the first machines of the chain. Last week, the first physics experiments started in the East Area, behind the PS, and others will follow suit shortly.

A Cell-Coupled-Drift-Tube-Linac (CCDTL) ready to be tested in SM18. (Image: CERN)

However, despite the overall positive momentum of beam commissioning, challenges have arisen along the way, highlighting the complexities involved. Last week, some of the components of one of the Linac4 accelerating structures, specifically the Cell-Coupled-Drift-Tube-Linacs (CCDTLs) 3 and 4, presented some issues. Both CCDTLs rely on a single klystron*, a high-power microwave amplifier crucial for providing accelerating power to the structures, which, in turn, transfer the power to the protons, which are then accelerated.

The high-voltage and high-frequency amplifier chain, including the klystron, experienced frequent voltage breakdowns, resulting in a significant drop in accelerating voltage within the two CCDTLs. This disruption severely perturbed the beam, rendering it unusable for the PS Booster. Experts intervened multiple times, initially focusing on fine-tuning the parameters of the amplifier chain and later on cleaning and replacing various components suspected to be causing the breakdowns.

By 22 March, a set of parameters was established to allow the acceleration of beams with a low proton intensity, enabling commissioning activities to continue in the downstream machines, including the LHC. However, these parameters did not meet the requirements for generating the full-blown physics beams that will be required in the coming weeks. On 24 March, a collaborative effort with experts from various groups convened in the CERN Control Centre (CCC) to conduct a final assessment. This evaluation aimed to determine whether the klystron needed replacing.

After re-establishing the parameters suitable for high-intensity beam acceleration, the beam was switched back on. Unfortunately, within the first hour, at least two high-voltage breakdowns occurred – the team thus concluded that the klystron replacement was necessary.

To maintain commissioning activities in the downstream machines, parameters allowing low-intensity beam acceleration were reinstated. This allowed operations to continue until Monday morning, when the klystron replacement process started. Such an intervention typically requires two to three days before beam operations can be restored.

The new klystron is in place, ready to feed the CCDTLs 3 and 4. (Image: CERN)

Meanwhile, commissioning activities in the downstream machines have been suspended and the start of physics at the n_TOF facility, behind the PS, has been postponed (it was originally scheduled to start on 25 March). Commissioning of the North Area's secondary beams began on 22 March instead of 25 March. Thanks to this head start, the incident in Linac4 does not impact the overall schedule for the North Area, where physics is still scheduled to start on 10 April.

In Linac4, the old klystron has been removed, and the new one had been installed and tested by 26 March. Beam was sent to the PS Booster at 5 p.m. that day and, at 9 p.m., the LHC beam commissioning activities resumed. Since then, they have been progressing well.

On 27 March, beams entered into “test” collisions at the target energy of 6.8 TeV in the LHC. These were not yet stable beams, which meant that the experiments did not take data. Collisions for physics at 6.8 TeV are expected to take place on 8 April.

______

* A klystron is a high-power microwave amplifier used to generate high-power radiofrequency (RF) signals at a specific frequency. It operates on the principle of velocity modulation, where bunches of electrons are alternately accelerated and decelerated within a resonant cavity structure. This modulation process results in the amplification of the RF signal.

anschaef Wed, 03/27/2024 - 15:59 Byline Rende Steerenberg Publication Date Thu, 03/28/2024 - 10:49

CERN and STFC support environmentally sustainable physics

Τετ, 27/03/2024 - 11:29
CERN and STFC support environmentally sustainable physics CERN Director-General, Fabiola Gianotti, and STFC Executive Chair, Mark Thomson, sign a new agreement to support the development of more sustainable particle accelerators (Image: CERN)

On 22 March, CERN and the UK’s Science and Technology Facility Council (STFC) signed a new agreement to collaborate on the research and development of advanced new technologies to make future particle accelerators significantly more sustainable.

Minimising the environmental impact of particle physics activities, ensuring their sustainability and energy efficiency is one of the key recommendations of the last update of the European Strategy for Particle Physics, published in 2020.

“CERN is fully committed to fostering sustainability across its existing and forthcoming projects, actively engaging in a variety of initiatives,” explains Mike Lamont, CERN Director of Accelerators and Technology. “These include sourcing renewable energy, implementing heat recovery schemes, and forging collaborations with industry to explore innovative applications of sustainable technology, such as high-power electricity distribution in various contexts. Our philosophy in this regard aligns well with that of the STFC and we look forward for exploiting the potential of this collaboration – together we are stronger.”

The agreement will act as a framework to better direct CERN and STFC’s funding, expertise and technological investment to minimise environmental impact. It provides guidance and recommendations that consider the entire lifecycle of accelerator facilities from design and construction to operation and decommissioning.

The agreement also outlines a proposal for STFC to establish a new Centre of Excellence in Sustainable Accelerators (CESA) at the Daresbury Laboratory in the UK. CESA would conduct original research in sustainable accelerator technologies and train accelerator scientists, technicians and engineers in the skills required to develop new accelerators with sustainability at the heart of the design.

For more details, see the UKRI website.

katebrad Wed, 03/27/2024 - 10:29 Publication Date Wed, 03/27/2024 - 10:28

Spring at CERN, your photos

Τετ, 27/03/2024 - 11:03
Spring at CERN, your photos Ice-white blossom in front of ISOLDE (Image: Sanje Fenkart) (Image: CERN)

Blossom, blue sky and buildings proved the winning combination for our “spring at CERN” photo competition. Congratulations to Sanje Fenkart from the IR department, who wins not just one CAGI Chocopass, but two, allowing her and a friend to spend a day exploring Geneva and tasting from a range of chocolate shops.

Thank you to all of you who sent in your photos. They are beautiful and are now available in a CC-BY photo collection, shown as a slideshow here:

We’d like to thank the International Geneva Welcome Centre (CAGI) for their sweet (pun intended) gesture of offering these prizes. The CAGI cultural kiosk is located in CERN’s main building and is open from Monday to Friday from 8:30 a.m. to 11:00 a.m. and from 11:30 a.m. to 2:30 p.m. It offers numerous discounts for local activities and events both in Switzerland and in France. Find out more here: https://www.cagi.ch/en/cultural-kiosk-agenda/

katebrad Wed, 03/27/2024 - 10:03 Byline Internal Communication Publication Date Wed, 03/27/2024 - 16:46

The delicate balance of lepton flavours

Τρί, 26/03/2024 - 11:33
The delicate balance of lepton flavours

In a talk at the ongoing Rencontres de Moriond conference, the ATLAS collaboration presented the result of its latest test of a key principle of the Standard Model of particle physics known as lepton flavour universality. The precision of the result is the best yet achieved by a single experiment in decays of the W boson and surpasses that of the current experimental average.

Most elementary particles can be classed into groups or families with similar properties. For example, the lepton family includes the electron, which forms the negatively charged cloud of particles surrounding the nucleus in every atom, the muon, a heavier particle found in cosmic rays, and the tau-lepton, an even heavier short-lived particle only seen in high-energy particle interactions.

As far as physicists know, the only difference between these particles is their mass, as generated through their different strengths of interaction with the fundamental field associated with the Higgs boson. In particular, a remarkable feature of the Standard Model is that each lepton type, or “flavour”, is equally likely to interact with a W boson, the electrically charged carrier of the weak force that is one of the four fundamental forces of nature. This principle is known as lepton flavour universality.

High-precision tests of lepton flavour universality, as obtained by comparing the rates of decay of the W boson into an electron and an electron neutrino, into a muon and a muon neutrino or into a tau-lepton and a tau neutrino, are therefore sensitive probes of physics beyond the Standard Model. Indeed, if lepton flavour universality holds, these decay rates should be equal (within negligible mass-dependent corrections).

This can be tested by measuring the ratios of the W boson’s rates of decay into the different lepton flavours. One of the challenges associated with such measurements at the Large Hadron Collider (LHC) is the collection of a pure (“unbiased”) sample of W bosons. In a paper released by Nature Physics in 2021, ATLAS reported the world’s most precise measurement of the ratio of the W boson’s rate of decay into a tau-lepton versus its rate of decay into a muon, demonstrating that collision events in which a pair of top quarks is produced provide an abundant and clean sample of W bosons.

In a recent paper, ATLAS released a new measurement, this time addressing the ratio of the W boson’s rate of decay into a muon versus its rate of decay into an electron. While the combination of all previous measurements showed that this ratio is within about 0.6% of unity, corresponding to equal decay rates, there was still room for improvement.

The new ATLAS result is based on a study of its full dataset from the second run of the LHC, collected between 2015 and 2018. The analysis looked at over 100 million top-quark-pair collision events. The top quark decays promptly into a W boson and a bottom quark, so this sample provides 100 million pairs of W bosons. By counting the number of these events with two electrons (and no muon) or two muons (and no electron), physicists can test whether the W boson decays more often into an electron or a muon.

However, it's not that simple. The Z boson, the electrically neutral carrier of the weak force, can also decay into a pair of electrons or muons, leaving a similar experimental signature to that of a top-quark pair. Since the combined mass of the leptons in Z-boson events clusters around the Z-boson mass of 91 GeV, this background process can be estimated and subtracted.

Moreover, as a result of measurements conducted in the 1990s at CERN’s Large Electron–Positron (LEP) collider, the LHC’s predecessor, and at the Stanford Linear Collider (SLC), the ratio of the Z boson’s rate of decay into two muons versus its rate of decay into two electrons is known to be equal to unity within 0.3%. Thus, in this ATLAS analysis, the Z boson’s decay rate ratio was determined as a reference measurement, allowing researchers to reduce uncertainties coming from the reconstruction of electrons and muons. Additionally, as many measurement uncertainties are similar in the events with two electrons and those with two muons, they were found to have only a minor effect on the measured decay rate ratio.

The final result from this new ATLAS analysis is a ratio of 0.9995, with an uncertainty of 0.0045, perfectly compatible with unity. With an uncertainty of only 0.45%, the result is more precise than all previous measurements combined (see figure below). For now, lepton flavour universality survives intact.

Measurements of the ratio of the W boson’s rate of decay into a muon versus its rate of decay into an electron. The new ATLAS result is shown in the last row as an open blue circle. Previous measurements are shown above using solid symbols, and the Particle Data Group average of all previous results is shown using a black diamond. (Image: ATLAS/CERN) abelchio Tue, 03/26/2024 - 10:33 Byline ATLAS collaboration Publication Date Tue, 03/26/2024 - 10:17

Computer Security: Day of the open firewall

Τρί, 26/03/2024 - 00:22
Computer Security: Day of the open firewall

With ongoing vulnerability scans of CERN’s internet presence performed by an external specialised company, the Computer Security team’s plans to perform penetration testing against selected targets visible to the internet, and the possibility of CERN joining a so-called Bug Bounty programme (a Bulletin article on this will come soon), we are preparing for an increasingly thorough assessment of the weaknesses, misconfigurations and vulnerabilities inside CERN – on the campus network, the technical network and the networks dedicated to the different experiments.

Given that the CERN networks are many, vast and interconnected in a complex manner, with tens of thousands of registered devices, thousands of them regularly or permanently connected, a large proportion of unmanaged “bring-your-own” devices or unpatchable and inherently vulnerable devices of the Internet of Things, a very large number of heterogenous virtual machines and containers running arbitrary applications, and about ten thousand websites leading to millions of webpages, vulnerability scanning and penetration testing of such an environment is complex, complicated and tedious. That’s why we have decided to lower CERN’s outer perimeter firewall protections for 24 hours on the first Monday of next month so that any external third party interested in poking/hacking/breaking into CERN can do so. The open firewall, allowing any incoming traffic, will facilitate not only the work of the aforementioned external company, but also that of the students affiliated with our WhiteHat programme, Bug Bounty hunters hoping for an entry on our Kudos page and any other benign or malicious attacker.

As usual, any ethical party probing CERN during those 24 hours is supposed to stop their activity before any damage or destruction is done and to report all their findings immediately to us so that they can be addressed, controlled, mitigated and fixed. For those cases where the scans and tests are performed by malicious actors, our network-based intrusion detection system connected to the outer perimeter firewall will stay alert and monitor all activities in the hope of identifying their ill-doing well in time, as we managed to in the past. The Computer Security team will, exceptionally, cover its duties 24/7. Of course, we cannot guarantee that no damage will be done by any malicious attacker, but we are counting on the robustness, resilience and up-to-dateness of your systems, devices, virtual machines/containers and websites. This risk is also the reason why we will open the firewall for just 24 hours: this tight time window should keep any collateral damage low.

So, stay tuned for next Monday, 1 April, 00:00 to 23:59, the day when we shall learn more about the security of CERN’s internal networks, and subsequently further improve all the systems connected to it.  

________

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 Mon, 03/25/2024 - 23:22 Byline Computer Security team Publication Date Mon, 03/25/2024 - 23:22

First observation of photons-to-taus in proton–proton collisions by CMS

Δευ, 25/03/2024 - 17:27
First observation of photons-to-taus in proton–proton collisions by CMS

In March 2024, the CMS collaboration announced the observation of two photons creating two tau leptons in proton–proton collisions. It is the first time that this process has been seen in proton–proton collisions, which was made possible by using the precise tracking capabilities of the CMS detector. It is also the most precise measurement of the tau’s anomalous magnetic moment and offers a new way to constrain the existence of new physics.

The tau, sometimes called tauon, is a peculiar particle in the family of leptons. In general, leptons, together with quarks, make up the “matter” content of the Standard Model (SM). The tau was only discovered in the late 1980s at SLAC, and its associated neutrino – the tau neutrino – completed the tangible matter part upon its discovery in 2000 by the DONUT collaboration at Fermilab. Precise research for the tau is rather tricky though, as its lifetime is very short: it remains stable for only 290·10-15 s (a hundred quadrillionth of a second).

The two other charged leptons, the electron and the muon, are rather well studied. A lot is also known about their magnetic moments and their associated anomalous magnetic moments. The former can be understood as the strength and orientation of an imaginary bar magnet inside a particle. This measurable quantity, however, needs corrections at the quantum level arising from virtual particles tugging at the magnetic moment, deviating it from the predicted value. The quantum correction, referred to as anomalous magnetic moment, is of the order of 0.1%. If the theoretical and experimental results disagree, then this anomalous magnetic moment, al , opens doors to physics beyond the SM.

The anomalous magnetic moment of the electron is one of the most precisely known quantities in particle physics and agrees perfectly with the SM. Its muonic counterpart, on the other hand, is one of the most investigated ones, into which research is ongoing. Although theory and experiments have mostly agreed so far, recent results give rise to a tension that requires further investigation.

For the tau, however, the race is still going. It is especially hard to measure its anomalous magnetic moment, aτ, due to the tau’s short lifetime. The first attempts to measure aτ after the tau’s discovery came with an uncertainty that was 30 times higher than the size of the quantum corrections. Experimental efforts at CERN with the LEP and LHC detectors improved the constraints, reducing the uncertainties to 20 times the size of the quantum corrections.

In collisions, researchers look for a special process: two photons interacting to produce two tau leptons, also called a di-tau pair, which then decay into muons, electrons, or charged pions, and neutrinos. So far both ATLAS and CMS have observed this in ultra-peripheral lead–lead collisions. Now, CMS reports on the first observation of the same process during proton–proton collisions. These collisions offer a higher sensitivity to physics beyond the SM as new physics effects increase with the collision energy. With the outstanding tracking capabilities of the CMS detector, the collaboration was able to isolate this specific process from others, by selecting events where the taus are produced without any other track within distances as small as 1 mm. “This remarkable achievement of detecting ultra-peripheral proton–proton collisions sets the stage for many groundbreaking measurements of this kind with the CMS experiment,” said Michael Pitt, from the CMS analysis team.

This new method offers a new way to constrain the tau anomalous magnetic moment, which the CMS collaboration tried out immediately. While the significance will be improved with future run data, their new measurement places the tightest constraints so far, with higher precision than ever before. It reduces the uncertainty from the predictions down to only three times the size of the quantum corrections. “It is truly exciting that we can finally narrow down some of the basic properties of the elusive tau lepton,” said Izaak Neutelings, from the CMS analysis team. “This analysis introduces a novel approach to probe tau g-2 and revitalises measurements that have remained stagnant for more than two decades,” added Xuelong Qin, another member of the analysis team.

Further material: 3D interactive version of the event display with all tracks here.

sandrika Mon, 03/25/2024 - 16:27 Publication Date Mon, 03/25/2024 - 17:00

World Wide Web at 35

Δευ, 25/03/2024 - 16:36
World Wide Web at 35 Tim Berners-Lee invented and developed the World Wide Web as an essential tool for high energy physics at CERN from 1989 to 1994. Together with a small team he conceived HTML, http, URLs, and put up the first server and the first 'what you see is what you get' browser and html editor. (Image: CERN)

Thirty-five years ago, a young computer expert working at CERN wrote a proposal that combined accessing information with a desire for broad connectivity and openness. This proposal went on to become the World Wide Web (WWW), whose impact on society has been profound.  

Sir Tim Berners-Lee’s first proposal in March 1989 was for an internet-based hypertext system to link and access information across different computers. In November 1990, this “web of information nodes in which the user can browse at will” was formalised as a proposal, “WorldWideWeb: Proposal for a HyperText Project”, by Berners-Lee, together with a CERN colleague, Robert Cailliau. By Christmas that year, Berners-Lee had implemented key components, namely html, http and URL, and created the first Web server, browser and editor (WorldWideWeb). This server is now exhibited in the Laboratory’s new visitor centre, CERN Science Gateway.

CERN released the WWW software into the public domain on 30 April 1993, making it freely available for anyone to use and improve. This decision encouraged the use of the Web, and society to benefit from it.

Now, thirty-five years since his original proposal, Sir Tim Berners-Lee reflects on the web’s trajectory in an open letter and states how we, as engaged citizens, can "re-shape a digital future that prioritises human well-being, equity, and autonomy".

katebrad Mon, 03/25/2024 - 15:36 Publication Date Wed, 03/27/2024 - 16:24

Brazil becomes Associate Member State of CERN

Παρ, 22/03/2024 - 10:06
Brazil becomes Associate Member State of CERN

Brazil has become the first Associate Member State of CERN in the Americas, following official notification that the country has completed its internal approval procedures in respect of the agreement signed in March 2022 granting it that status and of the Protocol on Privileges and Immunities of the Organization. The starting date of Brazil’s status as an Associate Member State is 13 March 2024.

Formal cooperation between CERN and Brazil started in 1990 with the signature of an International Cooperation Agreement, allowing Brazilian researchers to participate in the DELPHI experiment at the Large Electron–Positron Collider (LEP). Over the past decade, Brazil’s experimental particle-physics community has doubled in size. At the four main Large Hadron Collider (LHC) experiments alone, about 200 Brazilian scientists, engineers and students collaborate in fields ranging from hardware and data processing to physics analysis.

Today, Brazilian institutes participate in all the main experiments at the LHC – ALICE, ATLAS, CMS and LHCb and their ongoing and planned upgrades – as well as in ALPHA at the anti-proton decelerator. They are also involved in experiments at ISOLDE, ProtoDUNE at the Neutrino Platform and instrumentation projects such as Medipix. Following on from their participation in the RD51 collaboration, Brazilian teams are also contributing to setting up the DRD1 and DRD3 R&D collaborations for future detectors. Brazilian nationals also participate very actively in CERN training and outreach programmes.

Beyond particle physics, CERN and Brazil’s National Centre for Research in Energy and Materials (CNPEM) have also been formally cooperating since December 2020 on accelerator technology R&D and its applications.

As an Associate Member State, Brazil is entitled to appoint representatives to attend meetings of the CERN Council and the Finance Committee. Its nationals are eligible to apply for limited-duration staff positions and CERN’s graduate programmes, and its industry is entitled to bid for CERN contracts, increasing opportunities for industrial collaboration in advanced technologies.

angerard Fri, 03/22/2024 - 09:06 Publication Date Fri, 03/22/2024 - 17:00

CERN rewarded for its contributions to cloud computing

Πέμ, 21/03/2024 - 17:12
CERN rewarded for its contributions to cloud computing

On 21 March, CERN received the “Top End User” special award by the Cloud Native Computing Foundation (CNCF) for its “forward-looking approach to leveraging cloud native technologies to address future scientific and operational challenges”. Prior recipients of the “Top End User” CNCF award have included Mercedes-Benz, Spotify and Apple.  

Cloud native technologies are software solutions that exploit the basic features of cloud computing – e.g., scalability, flexibility, data resiliency – and allow system engineers to effectively manage complex computing environments with minimal effort. CERN has been a member of the CNCF community since 2020 and is considered an “end user” because it develops cloud native technologies internally but does not sell cloud service externally.

CERN contributes to community-driven cloud computing ecosystems, such as the CNCF, but also runs its own private cloud, which is configured and integrated into the CERN network and authentication services. The organization’s cloud ecosystem is heterogeneous and complex, as Taylor Dolezal, head of ecosystem at CNCF confirmed: “CERN's innovative use of cloud native technologies is a shining example of how open source and collaboration can drive cutting-edge research.”

For more details see the CNCF announcement and the IT README.

katebrad Thu, 03/21/2024 - 16:12 Publication Date Thu, 03/21/2024 - 15:39

Scientists use n_TOF to investigate how cerium is produced in the Universe

Πέμ, 21/03/2024 - 12:42
Scientists use n_TOF to investigate how cerium is produced in the Universe The experimental setup. (Image: n_TOF collaboration)

Cerium is a rare Earth metal that has numerous technological applications, for example in some types of lightbulbs and flat-screen TVs. While the element is rare in Earth’s crust, it is slightly more abundant in the Universe. However, much is unknown about how it is synthesised in stars. Now, in a new study published in Physical Review Letters, the n_TOF collaboration at CERN investigates how cerium is produced in stars. The results differ from what was expected from theory, indicating a need to review the mechanisms believed to be responsible for the production of cerium – and other heavier elements – in the Universe.

“The measurement we carried out enabled us to identify nuclear resonances never observed before in the energy range involved in the production of cerium in stars,” explains Simone Amaducci, of INFN’s Southern National Laboratories and first author of the study. “This is thanks to the very-high-energy resolution of the experimental apparatus at CERN and the availability of a very pure sample of cerium 140.”

The abundance of elements heavier than iron observed in stars (such as tin, silver, gold and lead) can be reproduced mathematically by hypothesising the existence of two neutron capture processes: the slow (s) process and the rapid (r) process. The s process corresponds to a neutron flux of 10 million neutrons per cubic centimetre while the r process has a flux of more than one million billion billion neutrons per cubic centimetre. The s process is theorised to produce about half of the elements heavier than iron in the Universe, including cerium.

CERN’s Neutron Time-of-Flight facility (n_TOF) is designed to study neutron interactions, such as those that occur in stars. In this study, the scientists used the facility to measure the nuclear reaction of the cerium 140 isotope with a neutron to produce isotope 141. According to sophisticated theoretical models, this particular reaction plays a crucial role in the synthesis of heavy elements in stars. Specifically, the scientists looked at the reaction’s cross section: the physical quantity that expresses the probability that a reaction occurs. The scientists measured the cross section at a wide range of energies with an accuracy 5% higher than previous measurements.

The results open up new questions about the chemical composition of the Universe. “What intrigued us at the beginning was a discrepancy between theoretical star models and observational data of cerium in the stars of the M22 globular cluster in the Sagittarius constellation,” explains Sergio Cristallo of INAF’s Abruzzo Astronomical Observatory, who proposed the experiment. “The new nuclear data differs significantly, up to 40%, from the data present in the nuclear databases currently used, definitely beyond the estimated uncertainty.”

These results have notable astrophysical implications, suggesting a 20% reduction in the contribution of the s process to the abundance of cerium in the Universe. This means a paradigm shift is required in the theory of cerium nucleosynthesis: other physical processes that are not currently included would need to be considered in calculations of stellar evolution. Furthermore, the new data has a significant impact on scientists’ understanding of the chemical evolution of galaxies, which also affects the production of heavier elements in the Universe.

ndinmore Thu, 03/21/2024 - 11:42 Publication Date Thu, 03/21/2024 - 17:06

CERN launches the White Rabbit Collaboration

Πέμ, 21/03/2024 - 11:12
CERN launches the White Rabbit Collaboration The White Rabbit community gathers to celebrate the launch of the White Rabbit Collaboration. (Image: CERN)

White Rabbit (WR) is a technology developed at CERN, in collaboration with institutes and companies, to synchronise devices in the accelerators down to sub-nanoseconds and solve the challenge of establishing a common notion of time across a network. Indeed, at a scale of billionths of a second, the time light takes to travel through a fibre-optic cable and the time the electronics take to process the signal are no longer negligible. To avoid potential delays, the co-inventors of White Rabbit designed a new ethernet switch.

First used in 2012, the application of this fully open-source technology has quickly expanded outside the field of particle physics. In 2020, it was included in the worldwide industry standard known as Precision Time Protocol (PTP), governed by the Institute of Electrical and Electronics Engineers (IEEE).

What’s more, CERN recently launched the White Rabbit Collaboration, a membership-based global community whose objective is to maintain a high-performance open-source technology that meets the needs of users and to facilitate its uptake by industry. The WR Collaboration will provide dedicated support and training, facilitate R&D projects between entities with common interests and complementary expertise and establish a testing ecosystem fostering trust in products that incorporate the open-source technology. At CERN, the WR Collaboration Bureau – a dedicated team composed of senior White Rabbit engineers and a community coordinator – will facilitate the day-to-day running of the Collaboration’s activities and support its members.

“A key distinctive feature of White Rabbit, as opposed to other technologies that have been developed since, is that it is open source and based on standards”, says Javier Serrano, Chair of the White Rabbit Collaboration Board and co-inventor of the technology. Companies and institutes can therefore adapt it to their needs and incorporate it in their products and systems, while the technology, in turn, benefits from a large community of developers. “The first step to foster industry uptake was to include WR concepts in the IEEE standard. Through this endeavour, we established many links with industry,” says Maciej Lipinski, Chair of the White Rabbit Collaboration Council and senior White Rabbit engineer at CERN.

White Rabbit is used in the finance sector as well as in many research infrastructures, and it is currently being evaluated for application in the future quantum internet. The technology could also play a key role in the future landscape of global time dissemination technologies, which currently rely heavily on satellites. The infrastructure for the dissemination of time is essential to the economy and underpins most critical national infrastructure. Governments and industry across the globe are therefore striving to find alternatives to distribute a reference time, such as the one WR could offer via optical fibre, with telecom and power grid companies starting to test WR in their networks.

The WR Collaboration comes at a moment when many sectors are undergoing a profound transformation with regards to their timing technology. “The WR Collaboration will provide a neutral gathering point around this open-source technology and define a long-term common vision, establishing a solid ground from which innovation can thrive,” continues Amanda Diez Fernandez from CERN’s Knowledge Transfer group and the White Rabbit Community Coordinator.

To learn more about how to join the White Rabbit Collaboration, go to: www.white-rabbit.tech

_______

From 21–22 March, the White Rabbit community met at CERN to celebrate the launch of the WR Collaboration. To find out more, listen to the recorded talks of the event.

ndinmore Thu, 03/21/2024 - 10:12 Publication Date Fri, 03/22/2024 - 14:10

Observing accelerator resonances in 4D

Τρί, 19/03/2024 - 13:09
Observing accelerator resonances in 4D CERN’s Super Proton Synchrotron in 2022. (Image: CERN)

Whether in listening to music or pushing a swing in the playground, we are all familiar with resonances and how they amplify an effect – a sound or a movement, for example. However, in high-intensity circular particle accelerators, resonances can be an inconvenience, causing particles to fly off their course and resulting in beam loss. Predicting how resonances and non-linear phenomena affect particle beams requires some very complex dynamics to be disentangled.

For the first time, scientists at the Super Proton Synchrotron (SPS), in collaboration with scientists at GSI in Darmstadt, have been able to experimentally prove the existence of a particular resonance structure. While it had previously been theorised and appeared in simulations, this structure is very difficult to study experimentally as it affects particles in a four dimensional space*. These latest results, published in Nature Physics, will help to improve the beam quality for low-energy and high-brightness beams for the LHC injectors at CERN and the SIS18/SIS100 facility at GSI, as well as for high-energy beams with large luminosity, such as the LHC and future high-energy colliders.

“With these resonances, what happens is that particles don’t follow exactly the path we want and then fly away and get lost,” says Giuliano Franchetti, a scientist at GSI and one of the paper’s authors. “This causes beam degradation and makes it difficult to reach the required beam parameters.”

The idea to look for the cause of this emerged in 2002, when scientists at GSI and CERN realised that particle losses increased as accelerators pushed for higher beam intensity. “The collaboration came from the need to understand what was limiting these machines so that we could deliver the beam performance and intensity needed for the future,” says Hannes Bartosik, a scientist at CERN and another of the paper’s authors.

Over many years, theories and simulations were developed to understand how resonances affected particle motion in high-intensity beams. “It required an enormous simulation effort by large accelerator teams to understand the effect of the resonances on beam stability,” says Frank Schmidt at CERN, also one of the paper’s authors. The simulations showed that resonance structures induced by coupling in two degrees of freedom are one of the main causes of beam degradation.

It took a long time to devise how to look for these resonance structures experimentally. This is because they are four dimensional* and require the beam to be measured in both the horizontal and the vertical planes to see if they exist. “In accelerator physics, the thinking is often in only one plane,” adds Franchetti.

Figure 1: Conceptually visualising 4D resonance structures is much more complicated than one-dimensional resonances. This image shows the 4D resonance structure measured in the SPS. (Image: H. Bartosik, G. Franchetti and F. Schmidt, Nature Physics)

To measure how resonances affect particle motion, the scientists used beam position monitors around the SPS. Over approximately 3000 beam passages, the monitors measured whether the particles in the beam were centred or more to one side, in both the horizontal and vertical planes. The resonance structure that was found is shown in Figure 1.

“What makes our recent finding so special is that it shows how individual particles behave in
a coupled resonance,” continues Bartosik. “We can demonstrate that the experimental findings agree with what had been predicted based on theory and simulation.”

While the existence of the coupled resonance structures has now been observed experimentally, much more remains to be done to reduce their detrimental effect. “We’re developing a theory to describe how particles move in the presence of these resonances,” continues Franchetti. “With this study, coupled with all the previous ones, we hope we will get clues on how to avoid or minimise the effects of these resonances for current and future accelerators.”

*Space refers to “phase space” – the space in which all possible states of a system are represented

Read the paper here

ndinmore Tue, 03/19/2024 - 12:09 Byline Naomi Dinmore Publication Date Wed, 03/20/2024 - 11:15

CERN publishes knowledge transfer highlights from 2023

Τρί, 19/03/2024 - 12:53
CERN publishes knowledge transfer highlights from 2023 CERN’s 2023 knowledge transfer highlights are available for the first time in digital format, in line with CERN’s commitment to reduce unnecessary printing. (Image: CERN)

CERN’s new digital report “Accelerating Innovation Through Partnerships” highlights knowledge transfer activities from 2023. It showcases concrete applications of CERN technologies and know-how, with diverse examples in the healthcare, environment, aerospace, digital and quantum fields.

Find out more about CERN’s ongoing partnerships with industry, academia, research institutions and hospitals in its Member and Associate Member States. See how entrepreneurs are supported by the recently launched CERN Venture Connect programme. Discover how these activities not only drive innovation but also have a positive impact on society.

Save the date of 18 April 2024 for the public event “The virtuous circle of knowledge and innovation” taking place in CERN Science Gateway as part of the series of events for CERN’s 70th birthday.

For more information about CERN’s ongoing knowledge transfer activities, visit kt.cern.

This video summarises the new digital report “Accelerating Innovation Through Partnerships”. (Video: CERN) katebrad Tue, 03/19/2024 - 11:53 Byline CERN Knowledge Transfer group Publication Date Wed, 03/20/2024 - 14:01

Accelerator Report: Beams are circulating in the LHC

Πέμ, 14/03/2024 - 11:43
Accelerator Report: Beams are circulating in the LHC The LHC fixed display, just after both beams entered into circulation. The blue and red lines represent the number of protons in beams 1 and 2, respectively. The black line represents the energy of the beams. It is flat because the beams had not yet been accelerated at this point. (Image: CERN)

On 8 March, three days ahead of schedule, the first proton beam was injected into the LHC; 20 minutes later, the second beam was injected, circulating in the opposite direction.

Since the last Accelerator Report, the hardware tests and subsequent cold check-out were successfully completed, both ahead of schedule. Once the usual remaining wrinkles were ironed out, everything was ready to start the 2024 LHC beam commissioning. The single bunch low intensity probe beam, meticulously prepared in the injector chain in the past weeks, came knocking at the LHC's door.

Many of the LHC engineers in charge and system experts gathered in the CERN Control Centre (CCC) on 8 March, alongside members of the Management, to witness the process, eagerly waiting for the first beams to circulate again in the LHC.

The LHC Operations team started the injection and threading process for beam 2 (circulating counter clockwise): they injected the beam at LHC Point 8, just in front of the LHCb experiment, and let it circulate up to Point 7, where a set of collimators was fully closed to intercept it. The measurements performed by the beam position monitors indicated that the beam trajectory could be improved. This was quickly done using an automated beam steering tool that powers corrector magnets to smoothen the trajectories of the particles.

Confident in this correction, the Operations team opened up the collimators at Point 7 and closed the ones further along the ring at Point 6, before injecting the beam again. This process was repeated until the last collimators, at Point 1 (ATLAS experiment), were opened, leaving the way clear for the beam to make a second, third, fourth… and millionth turn.

Another small correction to adjust the orbit of the circulating particles was made before attention switched to beam 1, which ended up circulating in the machine less than 20 minutes after beam 2 and was welcomed by many happy faces in the CCC. The next step – accelerating both beams up to 6.8 TeV – was also accomplished during the weekend. Witnessing both beams in circulation is something of a relief for everyone involved, although the real beam commissioning work starts at that point.

For the 2024 run, it was decided to modify the optics of the accelerator and to replace them by reverse polarity optics (RP-optics). The objective is to mitigate the radiation suffered by some of the magnets of the inner triplet region on both sides of the ATLAS experiment. The inner triplet is a set of quadrupole magnets that focus the beam to very small dimensions at the centre of the experiments.

Some of the collision debris – particles produced by the collisions and travelling  parallel to the beams, outside the experiment – is intercepted by the magnets in the inner triplet regions, inducing radiation damage to their insulation. With different optics, the debris is deposited in other places in these magnets, so that the burden of the radiation damage is distributed more widely. This helps to extend the magnets' lifetimes, even with an increased number of collisions.

The commissioning and validation of the RP-optics are among the many beam commissioning steps that have to be taken in the coming weeks before beams enter into collision at 6.8 TeV, hopefully on 8 April. Depending on how work progresses, this milestone may shift forwards or backwards by a few days.

anschaef Thu, 03/14/2024 - 10:43 Byline Rende Steerenberg Publication Date Thu, 03/14/2024 - 10:39

Accelerator Report: Beams are circulating in the LHC

Πέμ, 14/03/2024 - 11:43
Accelerator Report: Beams are circulating in the LHC The LHC fixed display, just after both beams entered into circulation. The blue and red lines represent the number of protons in beams 1 and 2, respectively. The black line represents the energy of the beams. It is flat because the beams had not yet been accelerated at this point. (Image: CERN)

On 8 March, three days ahead of schedule, the first proton beam was injected into the LHC; 20 minutes later, the second beam was injected, circulating in the opposite direction.

Since the last Accelerator Report, the hardware tests and subsequent cold check-out were successfully completed, both ahead of schedule. Once the usual remaining wrinkles were ironed out, everything was ready to start the 2024 LHC beam commissioning. The single bunch low intensity probe beam, meticulously prepared in the injector chain in the past weeks, came knocking at the LHC's door.

Many of the LHC engineers in charge and system experts gathered in the CERN Control Centre (CCC) on 8 March, alongside members of the Management, to witness the process, eagerly waiting for the first beams to circulate again in the LHC.

The LHC Operations team started the injection and threading process for beam 2 (circulating counter clockwise): they injected the beam at LHC Point 8, just in front of the LHCb experiment, and let it circulate up to Point 7, where a set of collimators was fully closed to intercept it. The measurements performed by the beam position monitors indicated that the beam trajectory could be improved. This was quickly done using an automated beam steering tool that powers corrector magnets to smoothen the trajectories of the particles.

Confident in this correction, the Operations team opened up the collimators at Point 7 and closed the ones further along the ring at Point 6, before injecting the beam again. This process was repeated until the last collimators, at Point 1 (ATLAS experiment), were opened, leaving the way clear for the beam to make a second, third, fourth… and millionth turn.

Another small correction to adjust the orbit of the circulating particles was made before attention switched to beam 1, which ended up circulating in the machine less than 20 minutes after beam 2 and was welcomed by many happy faces in the CCC. The next step – accelerating both beams up to 6.8 TeV – was also accomplished during the weekend. Witnessing both beams in circulation is something of a relief for everyone involved, although the real beam commissioning work starts at that point.

For the 2024 run, it was decided to modify the optics of the accelerator and to replace them by reverse polarity optics (RP-optics). The objective is to mitigate the radiation suffered by some of the magnets of the inner triplet region on both sides of the ATLAS experiment. The inner triplet is a set of quadrupole magnets that focus the beam to very small dimensions at the centre of the experiments.

Some of the collision debris – particles produced by the collisions and travelling  parallel to the beams, outside the experiment – is intercepted by the magnets in the inner triplet regions, inducing radiation damage to their insulation. With different optics, the debris is deposited in other places in these magnets, so that the burden of the radiation damage is distributed more widely. This helps to extend the magnets' lifetimes, even with an increased number of collisions.

The commissioning and validation of the RP-optics are among the many beam commissioning steps that have to be taken in the coming weeks before beams enter into collision at 6.8 TeV, hopefully on 8 April. Depending on how work progresses, this milestone may shift forwards or backwards by a few days.

anschaef Thu, 03/14/2024 - 10:43 Byline Rende Steerenberg Publication Date Thu, 03/14/2024 - 10:39

Reducing emissions related to duty travel: everybody’s contribution counts

Τετ, 13/03/2024 - 15:46
Reducing emissions related to duty travel: everybody’s contribution counts

In an era where the consequences of climate change loom ever larger, reducing carbon emissions is imperative. Among the various contributors to carbon emissions, duty travel – comprising conferences and other professional engagements – is an often-overlooked source.

Travel is embedded in CERN’s DNA, with worldwide collaborations that rely on exchanges between people from all around the globe. International exchange is a pillar of scientific progress at CERN and beyond, and is particularly important for early-career researchers and those from underrepresented geographic regions.

At the same time, CERN strives to be a role model for environmentally responsible research and, in this context, to minimise its carbon emissions wherever possible. Extensive professional travel, particularly by air, has an environmental impact. CERN’s third Environment Report shows that emissions arising from travel by personnel on the CERN payroll amounted to 151 tCO2e and 827 tCO2e in 2021 and 2022 respectively, a marked reduction compared with the 3330 tCO2e reported in 2019, before the COVID-19 pandemic. Most emissions result from air travel, mainly from long-distance flights. Although they represent just a small fraction of CERN’s total emissions, acting on them is important as, whatever the scale, all actions contribute to minimising CERN’s environmental impact.

A dedicated working group was set up in 2022 to make recommendations on reducing duty-travel emissions without having a detrimental impact on CERN. The recommendations, approved by the Enlarged Directorate on 23 January 2024, recognise and integrate the crucial importance of international collaboration for the advancement of CERN’s mission and research, while encouraging everyone to collectively set an example by reducing duty-travel-related carbon emissions. The recommendations are now available in the Admin e-guide duty travel pages.

Two overarching principles apply:

  1. 1. Reducing (air) travel by considering whether virtual participation, if available, provides similar value. This will help reduce the number of trips undertaken and contribute to reducing overall emissions. In particular, single-day trips requiring air travel should be avoided if virtual participation is possible.
  2. 2. Encouraging the use of ground transportation (particularly the train) for distances up to 700 km and as transport options allow, taking into account time- and cost-efficiency.

The recommendations are accompanied by a simple decision tree to help travellers reflect before they book their trips. In addition, the new online booking tool Egencia offers several different features, including a CO2 calculator for flights. Finally, the recommendations also cover event guidelines to encourage organisers and participants to make mindful, environmentally conscious choices. These take into account the importance of in-person interactions for building and maintaining collaborations and networks, particularly for early-career professionals. They aim to ensure that effective virtual participation is possible in all events hosted by the Organization and to minimise the amount of travel required without compromising collaboration, operations, goals and opportunities for personnel.

ndinmore Wed, 03/13/2024 - 14:46 Byline HSE unit Publication Date Wed, 03/13/2024 - 14:38

Reducing emissions related to duty travel: everybody’s contribution counts

Τετ, 13/03/2024 - 15:46
Reducing emissions related to duty travel: everybody’s contribution counts

In an era where the consequences of climate change loom ever larger, reducing carbon emissions is imperative. Among the various contributors to carbon emissions, duty travel – comprising conferences and other professional engagements – is an often-overlooked source.

Travel is embedded in CERN’s DNA, with worldwide collaborations that rely on exchanges between people from all around the globe. International exchange is a pillar of scientific progress at CERN and beyond, and is particularly important for early-career researchers and those from underrepresented geographic regions.

At the same time, CERN strives to be a role model for environmentally responsible research and, in this context, to minimise its carbon emissions wherever possible. Extensive professional travel, particularly by air, has an environmental impact. CERN’s third Environment Report shows that emissions arising from travel by personnel on the CERN payroll amounted to 151 tCO2e and 827 tCO2e in 2021 and 2022 respectively, a marked reduction compared with the 3330 tCO2e reported in 2019, before the COVID-19 pandemic. Most emissions result from air travel, mainly from long-distance flights. Although they represent just a small fraction of CERN’s total emissions, acting on them is important as, whatever the scale, all actions contribute to minimising CERN’s environmental impact.

A dedicated working group was set up in 2022 to make recommendations on reducing duty-travel emissions without having a detrimental impact on CERN. The recommendations, approved by the Enlarged Directorate on 23 January 2024, recognise and integrate the crucial importance of international collaboration for the advancement of CERN’s mission and research, while encouraging everyone to collectively set an example by reducing duty-travel-related carbon emissions. The recommendations are now available in the Admin e-guide duty travel pages.

Two overarching principles apply:

  1. 1. Reducing (air) travel by considering whether virtual participation, if available, provides similar value. This will help reduce the number of trips undertaken and contribute to reducing overall emissions. In particular, single-day trips requiring air travel should be avoided if virtual participation is possible.
  2. 2. Encouraging the use of ground transportation (particularly the train) for distances up to 700 km and as transport options allow, taking into account time- and cost-efficiency.

The recommendations are accompanied by a simple decision tree to help travellers reflect before they book their trips. In addition, the new online booking tool Egencia offers several different features, including a CO2 calculator for flights. Finally, the recommendations also cover event guidelines to encourage organisers and participants to make mindful, environmentally conscious choices. These take into account the importance of in-person interactions for building and maintaining collaborations and networks, particularly for early-career professionals. They aim to ensure that effective virtual participation is possible in all events hosted by the Organization and to minimise the amount of travel required without compromising collaboration, operations, goals and opportunities for personnel.

ndinmore Wed, 03/13/2024 - 14:46 Byline HSE unit Publication Date Wed, 03/13/2024 - 14:38

CERN community: celebrate spring at CERN with us

Τετ, 13/03/2024 - 12:06
CERN community: celebrate spring at CERN with us

Blossom on the trees, longer days and a strange craving for egg-shaped chocolates tells us that spring is in the air.

To celebrate, we’re launching a photography competition for the CERN community. Send us your best photos of “spring at CERN”. Our favourite photo will win a CAGI Chocopass, kindly offered by the CAGI cultural kiosk at CERN. This Chocopass lets you spend a day exploring Geneva and tasting from a range of chocolate shops.

How to enter:

  • You must have a CERN email address to take part in this competition.
  • Send your photo to bulletin-editors@cern.ch by Sunday 24 March at 11:59 p.m. CET.
  • You can send a maximum of three photos per person.
  • By sending your photo, you agree to it being added to a CC-BY photo collection in the CERN Document Server, where you will be credited.
  • The photos may be used by CERN online for this competition and in the future.
  • The winner will be announced in the next CERN Bulletin.

We are grateful to the International Geneva Welcome Centre (CAGI) for offering a Chocopass for the winning prize. The CAGI cultural kiosk is located in CERN’s main building and is open from Monday to Friday from 8:30 a.m. to 11:00 a.m. and from 11:30 a.m. to 2:30 p.m. It offers numerous discounts for local activities and events both in Switzerland and in France. Find out more here: https://www.cagi.ch/en/cultural-kiosk-agenda/

katebrad Wed, 03/13/2024 - 11:06 Byline Internal Communication Publication Date Wed, 03/13/2024 - 11:24

CERN community: celebrate spring at CERN with us

Τετ, 13/03/2024 - 12:06
CERN community: celebrate spring at CERN with us

Blossom on the trees, longer days and a strange craving for egg-shaped chocolates tells us that spring is in the air.

To celebrate, we’re launching a photography competition for the CERN community. Send us your best photos of “spring at CERN”. Our favourite photo will win a CAGI Chocopass, kindly offered by the CAGI cultural kiosk at CERN. This Chocopass lets you spend a day exploring Geneva and tasting from a range of chocolate shops.

How to enter:

  • You must have a CERN email address to take part in this competition.
  • Send your photo to bulletin-editors@cern.ch by Sunday 24 March at 11:59 p.m. CET.
  • You can send a maximum of three photos per person.
  • By sending your photo, you agree to it being added to a CC-BY photo collection in the CERN Document Server, where you will be credited.
  • The photos may be used by CERN online for this competition and in the future.
  • The winner will be announced in the next CERN Bulletin.

We are grateful to the International Geneva Welcome Centre (CAGI) for offering a Chocopass for the winning prize. The CAGI cultural kiosk is located in CERN’s main building and is open from Monday to Friday from 8:30 a.m. to 11:00 a.m. and from 11:30 a.m. to 2:30 p.m. It offers numerous discounts for local activities and events both in Switzerland and in France. Find out more here: https://www.cagi.ch/en/cultural-kiosk-agenda/

katebrad Wed, 03/13/2024 - 11:06 Byline Internal Communication Publication Date Wed, 03/13/2024 - 11:24

You see an empty field? We see an “Open Sky Laboratory”!

Τρί, 12/03/2024 - 12:33
You see an empty field? We see an “Open Sky Laboratory”!

The Future Circular Collider (FCC) Feasibility Study is developing a concept for a new research infrastructure to host the next generation of higher-performance particle colliders with the aim of extending the research currently being conducted at the LHC, once the HL-LHC reaches its conclusion, beyond 2040.

In 2021–2022, the EU-funded FCC Innovation Study* launched an international challenge-based competition called “Mining the Future”, which invited scientists and companies to propose innovative yet technically feasible solutions to turn the material excavated during the construction of FCC underground structures into a usable resource. The reuse potential of the excavation material is one of the factors that will contribute to the acceptability and cost efficiency of the FCC project.

The proposed solutions are now being integrated into a unique design and evaluated in the field, and will reach maturity by 2030. The objectives of the evaluations are twofold. Firstly, to establish how to conduct the online identification, sorting and pre-treatment of the materials during the excavation process. Secondly, to prepare different reuse pathways to sort and pre-treat materials, including transforming sterile rock – a soft and heterogeneous sedimentary rock called molasse – into fertile soil for agriculture, forestry and renaturation applications, in line with the principles of a circular economy. The quality-assured creation of fertile soil is a lengthy process spanning several years and has been chosen as the first large-scale experiment with field tests at an “Open Sky Laboratory”.

The plot of land located near LHC Point 5 (CMS, Cessy, France) destined for the Open Sky Laboratory. (Image: CERN)

The Open Sky Laboratory, a plot of about 10 000 m2 located near LHC Point 5 (CMS, Cessy, France – see image), has been made available and will be prepared in collaboration with CERN’s SCE and EN departments. Molasse extracted during the HL-LHC excavations will be transported to this field to be used in the tests. Initial laboratory analyses will be performed off site to identify the most suitable mix of molasse and other materials. These will be followed by field tests in the Open Sky Laboratory’s controlled environment (monitoring of the field, weather and plant growth conditions), using scientific protocols developed by a collaboration of universities working in this domain.

In keeping with CERN’s long-standing tradition, this project relies on an open collaboration with academia and industry. Currently, the collaboration includes university and research experts in agronomy, pedogenesis and geology and industrial partners in soil engineering and phytoremediation, soil treatment techniques and monitoring and supervisory control systems.

A socioeconomic assessment of reuse cases for the transformed soil will be performed in order to evaluate the potential economic benefits for FCC construction and the potential advantages for the entire construction sector in Europe.

*Grant agreement 951754

anschaef Tue, 03/12/2024 - 11:33 Byline Luisa Ulrici Publication Date Thu, 03/14/2024 - 09:30

Σελίδες

Πανεπιστήμιο Κρήτης - Τμήμα Φυσικής - Πανεπιστημιούπολη Βουτών - TK 70013 Βασιλικά Βουτών, Ελλάδα
τηλ: +30 2810 394300 - email: chair@physics.uoc.gr