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Mitigating the environmental impact of CERN procurement

Every year, CERN spends some 500 MCHF on goods and services to build, maintain and operate its infrastructure to fulfil its scientific objectives. These purchases not only come at a financial cost, but also have an impact on the environment through the indirect emissions arising from their procurement. In 2023, CERN reported its procurement-related indirect emissions in the CERN Environment Report for the first time. These amounted to 98 030 tCO2e and 104 974 tCO2e in 2021 and 2022 respectively. To put this in context, this represents more than 90% of CERN’s total indirect emissions, the rest being attributed to personnel mobility, duty travel and catering, and just over 30% of CERN’s total emissions.

CERN strives to be a model for environmentally responsible research by taking action on its most impactful domains, including energy and water consumption and emissions, and setting objectives to minimise its environmental footprint. Adopting measures to positively influence procurement-related emissions is a priority for which a comprehensive strategy has been set out that will commit CERN, its suppliers and each and every one of us to making conscious decisions when purchasing goods or services.

Underpinning this strategy, the Environmentally Responsible Procurement Policy was approved by the Enlarged Directorate in June 2023. Anchored in the principle of embedding environmental responsibility where appropriate throughout all phases of the procurement process, the Policy commits the Organization to environmentally responsible procurement and to achieving sustainable results both internally and throughout its supply chains, integrating relevant best practices in its processes, measuring their impact, and communicating with and raising the awareness of all stakeholders.

In December 2023, the Enlarged Directorate approved the implementation of the Policy, effective from 1 January 2024. This entails a one-year kick-off phase to identify suitable areas for policy implementation, including a comprehensive awareness-raising programme with tailored training for technical officers and workshops for the departments focusing on their purchasing activities.

Additionally, pilot projects will help evaluate the integration of environmental criteria into market surveys and invitations to tender. Procurement officers will have access to a supplier sustainability due diligence tool and guidelines outlining best practices. These resources will equip them with the knowledge they need to assess suppliers based on their sustainability efforts.

Furthermore, a supplier engagement programme will be launched in order to foster discussions on sustainability within our supply chains, aiming to collaborate with and encourage suppliers to adopt sustainable practices.

Overall, this comprehensive implementation plan is designed to ensure a smooth transition towards policy compliance and create a sustainable framework for all stakeholders involved. Successful implementation will depend on all actors in CERN’s supply chains challenging our choices and decisions, from CERN’s IPT department, to CERN personnel involved in purchasing, to the suppliers themselves spanning our 23 Member and 11 Associate Member States, while continuing to strive for balanced returns.

According to Chris Hartley, Head of the IPT Department: “It is of great importance that we have established an Environmentally Responsible Procurement Policy for CERN. All CERN stakeholders want to see CERN continue to minimise its environmental impact. This Policy, underpinned by our progressive commitment to responsible sourcing, waste reduction and supplier engagement, will contribute to a more sustainable future.”

ndinmore Mon, 04/15/2024 - 16:39 Byline IPT department Publication Date Mon, 04/15/2024 - 16:35

Nature Physics, Published online: 15 April 2024; doi:10.1038/s41567-024-02473-5

When photons impinge on a material, free electrons can be created by the photoelectric effect. The emitted electron current usually fluctuates with Poisson statistics, but if squeezed quantum light is applied, the electrons bunch up.

ProtoDUNE’s argon filling underway

CERN’s Neutrino Platform houses a prototype of the Deep Underground Neutrino Experiment (DUNE) known as ProtoDUNE, which is designed to test and validate the technologies that will be applied to the construction of the DUNE experiment in the United States.

Recently, ProtoDUNE has entered a pivotal stage: the filling of one of its two particle detectors with liquid argon. Filling such a detector takes almost two months, as the chamber is gigantic – almost the size of a three-storey building. ProtoDUNE’s second detector will be filled in the autumn.

ProtoDUNE will use the proton beam from the Super Proton Synchrotron to test the detecting of charged particles. This argon-filled detector will be crucial to test the detector response for the next era of neutrino research. Liquid argon is used in DUNE due to its inert nature, which provides a clean environment for precise measurements. When a neutrino interacts with argon, it produces charged particles that ionise the atoms, allowing scientists to detect and study neutrino interactions. Additionally, liquid argon's density and high scintillation light yield enhance the detection of these interactions, making it an ideal medium for neutrino experiments.

Interestingly, the interior of the partially filled detector now appears green instead of its usual golden colour. This is because when the regular LED light is reflected inside the metal cryostat, the light travels through the liquid argon and the wavelength of the photons is shifted, producing a visible green effect.

The DUNE far detector, which will be roughly 20 times bigger than protoDUNE, is being built in the United States. DUNE will send a beam of neutrinos from Fermi National Accelerator Laboratory (Fermilab) near Chicago, Illinois, over a distance of more than 1300 kilometres through the Earth to neutrino detectors located 1.5 km underground at the Sanford Underground Research Facility (SURF) in Sanford, South Dakota.

Watch a short time-lapse video of protoDUNE being filled with liquid argon:

ckrishna Fri, 04/12/2024 - 10:15 Byline Chetna Krishna Publication Date Fri, 04/12/2024 - 10:30

Nature Physics, Published online: 12 April 2024; doi:10.1038/s41567-024-02456-6

As amorphous solids, glasses and gels are similar, but the origins of their different elastic properties are unclear. Simulations now suggest differing free-energy-minimizing pathways: structural ordering for glasses and interface reduction for gels.

The next-generation triggers for CERN detectors

The experiments at the Large Hadron Collider (LHC) require high-performance event-selection systems – known as “triggers” in particle physics – to filter the flow of data to manageable levels. The triggers pick events with distinguishing characteristics, such as interactions or collisions of particles recorded in particle detectors, and make them available for physics analyses. In just a few seconds, the complex system can determine whether the information about a given collision event is worth keeping or not. 

The ATLAS and CMS experiments use triggers on two levels. The first trigger runs in sync with the rate of particle bunches colliding in the detectors, deciding in less than 10 microseconds which data to keep. Events that pass the first-level trigger move on to the second high-level trigger for further selection. The selected events are then sent to the CERN Data Centre, where the data is copied, stored and eventually made available to scientists around the world for data analysis.  

In preparation for the High-Luminosity LHC (HL-LHC), the ATLAS and CMS detectors are being upgraded with finer spatial and timing granularity, which will result in more data for each collision. The principle is the same as taking a picture with a camera with more pixels: the resulting file will be bigger because the image contains more detail, and the picture will be of higher quality. To prepare for the data deluge expected when the LHC enters the high-luminosity era, scientists need to develop new strategies for more sophisticated event processing and selection.

The key objective of the five-year Next-Generation Triggers (NextGen) project is to get more physics information out of the HL-LHC data. The hope is to uncover as-yet-unseen phenomena by more efficiently selecting interesting physics events while rejecting background noise. Scientists will make use of neural network optimisation, quantum-inspired algorithms, high-performance computing and field-programmable gate array (FPGA) techniques to improve the theoretical modelling and optimise their tools in the search for ultra-rare events.

The foundations of the NextGen project were laid in 2022 when a group of private donors, including former Google CEO Eric Schmidt, visited CERN. This first inspiring visit eventually evolved into an agreement with the Eric and Wendy Schmidt Fund for Strategic Innovation, approved by the CERN Council in October 2023, to fund a project that would pave the way for the future trigger systems at the HL-LHC and beyond: NextGen was born.

NextGen will collaborate with experts in academia and industry. The work builds on the open-science and knowledge-sharing principles embedded in CERN's institutional governance and modus operandi. The project includes a work package dedicated to education and outreach, a unique multi-disciplinary training programme for NextGen researchers and targeted events and conferences for the wider community of scientists interested in the field. The intellectual property generated as part of the NextGen Triggers project, owned by CERN, will be released and shared under open licences in compliance with the CERN Open Science Policy.

The NextGen Triggers project will mark a new chapter in in high-energy physics, leveraging upgraded event-selection systems and data-processing techniques to unlock a realm of discoveries.  

ckrishna Thu, 04/11/2024 - 11:45 Byline Antonella Del Rosso Publication Date Thu, 04/11/2024 - 12:00

Searching for new asymmetry between matter and antimatter The LHCb detector seen in 2018 during its opening (Image: CERN)

Once a particle of matter, always a particle of matter. Or not. Thanks to a quirk of quantum physics, four known particles made up of two different quarks – such as the electrically neutral D meson composed of a charm quark and an up antiquark – can spontaneously oscillate into their antimatter partners and vice versa.

At a seminar held recently at CERN, the LHCb collaboration at the Large Hadron Collider (LHC) presented the results of its latest search for matter–antimatter asymmetry in the oscillation of the neutral D meson, which, if found, could help shed light on the mysterious matter–antimatter imbalance in the Universe.

The weak force of the Standard Model of particle physics induces an asymmetry between matter and antimatter, known as CP violation, in particles containing quarks. However, these sources of CP violation are difficult to study and are insufficient to explain the matter–antimatter imbalance in the Universe, leading physicists to both search for new sources and to study the known ones better than ever before.

In their latest endeavour, the LHCb researchers have rolled up their sleeves to measure with unprecedented precision a set of parameters that determine the matter–antimatter oscillation of the neutral D meson and enable the search for the hitherto unobserved but predicted CP violation in the oscillation.

The collaboration had previously measured the same set of parameters, which are linked to the decay of the neutral D meson into a positively charged kaon and a negatively charged pion, using its full data set from Run 1 of the LHC and a partial data set from Run 2. This time around, the team analysed the full Run-2 data set and, by combining the result with that of its previous analysis, excluding the partial Run-2 data set, it obtained the most precise measurements of the parameters to date – the overall measurement uncertainty is 1.6 times smaller than the smallest uncertainty achieved before by LHCb.

The results are consistent with previous studies, confirming the matter–antimatter oscillation of the neutral D meson and showing no evidence of CP violation in the oscillation. The findings call for future analyses of this and other decays of the neutral D meson using data from the third run of the LHC and its planned upgrade, the High-Luminosity LHC.

Other neutral D meson decays of interest include the decay into a pair of two kaons or two pions, in which LHCb researchers observed CP violation in particles containing charm quarks for the first time, and the decay into a neutral kaon and a pair of pions, with which LHCb clocked the speed of the particle’s matter–antimatter oscillation. No avenue should be left unexplored in the search for clues to the matter–antimatter imbalance in the Universe and other cosmic mysteries.

Find out more on the LHCb website.

abelchio Thu, 04/11/2024 - 11:41 Byline Ana Lopes Publication Date Thu, 04/11/2024 - 17:00

Nature Physics, Published online: 11 April 2024; doi:10.1038/s41567-024-02500-5

Author Correction: Cooperative pattern formation in multi-component bacterial systems through reciprocal motility regulation

Nature Physics, Published online: 11 April 2024; doi:10.1038/s41567-024-02448-6

Questioning the validity of axioms can teach us about physics beyond the standard model. A recent search for the violation of charge conservation and the Pauli exclusion principle yields limits on these scenarios.

Nature Physics, Published online: 11 April 2024; doi:10.1038/s41567-024-02474-4

Controlling phase transitions in solids is crucial for many applications. Ultrafast laser pulses have now been shown to enable the energy-efficient generation of structural fluctuations in VO2 by harnessing the correlated disorder in the material.

Nature Physics, Published online: 11 April 2024; doi:10.1038/s41567-024-02451-x

Linear topological systems can be characterized using invariants such as the Chern number. This concept can be extended to the nonlinear regime, giving rise to nonlinearity-induced topological phase transitions.

Nature Physics, Published online: 11 April 2024; doi:10.1038/s41567-024-02437-9

The Majorana Demonstrator experiment reports searches for the violation of the Pauli exclusion principle and of charge conservation. In the absence of a signal, exclusion limits for these processes are reported.

ATLAS provides first measurement of the W-boson width at the LHC View of an ATLAS collision event in which a candidate W boson decays into a muon and a neutrino. The reconstructed tracks of the charged particles in the inner part of the ATLAS detector are shown as orange lines. The energy deposits in the detector’s calorimeters are shown as yellow boxes. The identified muon is shown as a red line. The missing transverse momentum associated with the neutrino is shown as a green dashed line. (Image: ATLAS/CERN)

The discovery of the Higgs boson in 2012 slotted in the final missing piece of the Standard Model puzzle. Yet, it left lingering questions. What lies beyond this framework? Where are the new phenomena that would solve the Universe's remaining mysteries, such as the nature of dark matter and the origin of matter–antimatter asymmetry?

One parameter that may hold clues about new physics phenomena is the “width” of the W boson, the electrically charged carrier of the weak force. A particle’s width is directly related to its lifetime and describes how it decays to other particles. If the W boson decays in unexpected ways, such as into yet-to-be-discovered new particles, these would influence the measured width. As its value is precisely predicted by the Standard Model based on the strength of the charged weak force and the mass of the W boson (along with smaller quantum effects), any significant deviation from the prediction would indicate the presence of unaccounted phenomena.

In a new study, the ATLAS collaboration measured the W-boson width at the Large Hadron Collider (LHC) for the first time. The W-boson width had previously been measured at CERN’s Large Electron–Positron (LEP) collider and Fermilab’s Tevatron collider, yielding an average value of 2085 ± 42 million electronvolts (MeV), consistent with the Standard-Model prediction of 2088 ± 1 MeV. Using proton–proton collision data at an energy of 7 TeV collected during Run 1 of the LHC, ATLAS measured the W-boson width as 2202 ± 47 MeV. This is the most precise measurement to date made by a single experiment, and — while a bit larger — it is consistent with the Standard-Model prediction to within 2.5 standard deviations (see figure below).

This remarkable result was achieved by performing a detailed particle-momentum analysis of decays of the W boson into an electron or a muon and their corresponding neutrino, which goes undetected but leaves a signature of missing energy in the collision event (see image above). This required physicists to precisely calibrate the ATLAS detector’s response to these particles in terms of efficiency, energy and momentum, taking contributions from background processes into account.

However, achieving such high precision also requires the confluence of several high-precision results. For instance, an accurate understanding of W-boson production in proton–proton collisions was essential, and researchers relied on a combination of theoretical predictions validated by various measurements of W and Z boson properties. Also crucial to this measurement is the knowledge of the inner structure of the proton, which is described in parton distribution functions. ATLAS physicists incorporated and tested parton distribution functions derived by global research groups from fits to data from a wide range of particle physics experiments.

The ATLAS collaboration measured the W-boson width simultaneously with the W-boson mass using a statistical method that allowed part of the parameters quantifying uncertainties to be directly constrained from the measured data, thus improving the measurement’s precision. The updated measurement of the W-boson mass is 80367 ± 16 MeV, which improves on and supersedes the previous ATLAS measurement using the same dataset. The measured values of both the mass and the width are consistent with the Standard-Model predictions.

Future measurements of the W-boson width and mass using larger ATLAS datasets are expected to reduce the statistical and experimental uncertainties. Concurrently, advancements in theoretical predictions and a more refined understanding of parton distribution functions will help to reduce the theoretical uncertainties. As their measurements become ever more precise, physicists will be able to conduct yet more stringent tests of the Standard Model and probe for new particles and forces.

Comparison of the measured W-boson width with the Standard-Model prediction and with measurements from the LEP and Tevatron colliders. The vertical grey band illustrates the Standard-Model prediction, while the black dots and the associated horizontal bands represent the published experimental results. (Image: ATLAS/CERN) abelchio Wed, 04/10/2024 - 12:03 Byline ATLAS collaboration Publication Date Wed, 04/10/2024 - 11:57

Nature Physics, Published online: 10 April 2024; doi:10.1038/s41567-024-02464-6

Between pattern and chaos

CMS releases Higgs boson discovery data to the public CMS event display of a candidate Higgs boson decaying into two photons, one of the two decay channels that were key to the discovery of the particle. (Image: CERN)

As part of its continued commitment to making its science fully open, the CMS collaboration has just publicly released, in electronic format, the combination of CMS measurements that contributed to establishing the discovery of the Higgs boson in 2012. This release coincides with the publication of the Combine software – the statistical analysis tool that CMS developed during the first run of the Large Hadron Collider (LHC) to search for the unique particle, which has since been adopted throughout the collaboration.

Physics measurements based on data from the LHC are usually reported as a central value and its corresponding uncertainty. For instance, soon after observing the Higgs boson in LHC proton–proton collision data, CMS measured its mass as 125.3 plus or minus 0.6 GeV (the proton mass being about 1 GeV). But this figure is just a brief summary of the measurement outcome, a bit like the title of a book.

In a measurement, the full information extracted from the data is encoded in a mathematical function, known as the likelihood function, that includes the measured value of a quantity as well as its dependence on external factors. In the case of a CMS measurement, these factors encompass the calibration of the CMS detector, the accuracy of the CMS detector simulation used to facilitate the measurement and other systematic effects.

A likelihood function of a measurement based on LHC data can be complex, as many aspects need to be pinned down to fully understand the messy collisions that take place at the LHC. For example, the likelihood function of the combination of CMS Higgs boson discovery measurements, which CMS just released in electronic format, has nearly 700 parameters for a fixed value of the Higgs boson mass. Among these, only one – the number of Higgs bosons found in the data – is the physics parameter of interest, while the rest model systematic uncertainties.

Each of these parameters corresponds to a dimension of a multi-dimensional abstract space, in which the likelihood function can be drawn. It is hard for humans to visualise a space with more than a few dimensions, let alone one with many. The new release of the likelihood function of the CMS Higgs boson discovery measurements – the first likelihood function to be made publicly available by the collaboration – allows researchers to get around this problem. With a publicly accessible likelihood function, physicists outside the CMS collaboration can now precisely factor in the CMS Higgs boson discovery measurements in their studies.

The release of this likelihood function, as well as that of the Combine software, which is used to model the likelihood and fit the data, marks a new milestone in CMS’s decade-long commitment to fully open science. It joins hundreds of open-access publications, the release of almost five petabytes of CMS data on the CERN open-data portal and the publication of its entire software framework on GitHub.

Find out more on the CMS website.

abelchio Tue, 04/09/2024 - 14:29 Byline CMS collaboration Publication Date Tue, 04/16/2024 - 10:50

Computer Security: Swipes vs PINs vs passwords vs you

What kind of person are you? An artist, like a painter? A credit card fanatic or just “in numbers”? Cerebral, a memoriser or even a genius? An influencer, like a peacock, or just prettily self-confident? A security buff or sufficiently security aware? Or just ignorant about security and your privacy? Let’s assume for a moment that the way you unlock your smartphone tells us which.

There are many different ways to unlock your smartphone: swiping patterns, PIN numbers, passwords, biometric fingerprints or face recognition. Some are more secure, some less so. But all are better than nothing. So, let’s look at some of them.

Swiping patterns: The obvious choice on Android phones. Your favourite pattern on a 3x3 matrix. But as it should be a continuous swipe, the number of actual possibilities are quite limited, boiling down to about 20 most-used swipes. If yours is listed there, it may be time to move to another, more secure swipe. In any case, your swiping can be spied on and then tried once your smartphone is stolen.

Worse ─ although it’s probably still academic ─ a small basic sonar system combining a local loudspeaker to emit acoustic signals inaudible to humans and a microphone to record them coming back again allowed researchers to use “the echo signal […] to profile user interaction with the device”, i.e. the way your finger swipes over and interacts with the screen. They’ve shown how this sonar can be employed to help identify the swipe pattern to unlock an Android phone – reducing the number of trials to be performed by an attacker by 70%. And that’s only their proof of concept… Maybe PINs and passwords are better?

PINs vs passwords: A common paradigm of computer security is linked to password complexity. Four-digit PIN numbers are no longer state of the art. And even six digits are not necessarily sufficient. While guessing and brute-forcing is difficult, as your smartphone should have a lock-out procedure only allowing a small number of tries before introducing timeouts or even wiping your phone completely(!), PINs can be easily spied on and replayed once your smartphone has been stolen*. Or do you shield your screen as you type your smartphone PIN as you do for your credit card at an ATM? Of course, a better choice is a long and complex password or even passphrase (unless you use one of the top 10 most-used passwords). Admittedly, typing such long and complex passwords can be tedious. Enter: biometrics.

Biometrics: Still our favourite – using your fingerprint sensor or a capture of your face to unlock your phone. Your smartphone (and laptop) manufacturers went to extreme lengths to ensure that your biometric signature cannot be tampered with by your fingerprint on a piece of tape, your face in a photo or your sleeping self. And they also ensured that your biometric information is properly and securely stored using a special-purpose hardware chip (TPM: “trusted platform module”). Still, fingerprint authentication in particular has been broken into in the past for Android and Windows devices, making face recognition our favourite choice to protect access to your smartphone and all the personal (and professional!) data you store and access with it.

 

*Actually, Apple’s latest security patch also fixed some issues 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 Tue, 04/09/2024 - 14:03 Byline Computer Security team Publication Date Tue, 04/09/2024 - 14:01

Nature Physics, Published online: 09 April 2024; doi:10.1038/s41567-024-02462-8

The time has come to consider appropriate guardrails to ensure quantum technology benefits humanity and the planet. With quantum development still in flux, the science community shares a responsibility in defining principles and practices.

Nature Physics, Published online: 09 April 2024; doi:10.1038/s41567-024-02459-3

Quantum systems exhibit vastly different properties depending on their dimensionality. An experimental study with ultracold bosons now tracks quantum correlation properties during the crossover from two dimensions to one dimension.

Nature Physics, Published online: 09 April 2024; doi:10.1038/s41567-024-02454-8

Although topological photonics has been an active field of research for some time, most studies still focus on the linear optical regime. This Perspective summarizes recent investigations into the nonlinear properties of discrete topological photonic systems.

Nature Physics, Published online: 09 April 2024; doi:10.1038/s41567-024-02472-6

Photoemission experiments demonstrate that the photon number statistics of the exciting light can be imprinted on the emitted electrons, allowing the controlled generation of classical or non-classical electron number statistics of free electrons.

Large Hadron Collider reaches its first stable beams in 2024 LHC Page 1 showing the first stable beams of 2024 (Image: CERN)

On Friday 5 April, at 6.25 p.m., the LHC Engineer-in-Charge at the CERN Control Centre (CCC) announced that stable beams were back in the Large Hadron Collider, marking the official start of the 2024 physics data-taking season. The third year of LHC Run 3 promises six months of 13.6 TeV proton collisions at an even higher luminosity than before, meaning more collisions for the experiments to take data from. This will be followed by a period of lead ion collisions in October.

Before the LHC could restart, each accelerator in the CERN complex had to be prepared for another year of physics data taking. Beginning with Linac4, which welcomed its first beam two months ago, each accelerator has gone through a phase of beam commissioning in which it is gradually set up and optimised to be able to control all aspects of the beam, from its energy and intensity to its size and stability. During this phase researchers also test the accelerator’s performance and address any issues before it is used for physics. Following Linac4, which contains the source of protons for the beam, each accelerator was commissioned in turn: the Proton Synchrotron Booster, the Proton Synchrotron, the Super Proton Synchrotron, and finally the LHC from 8 March until 5 April. The whole complex is now ready for data taking.

Back to the CCC. While stable beams are the goal, the CCC engineers must first take several steps to achieve them. First, they must inject the beams into the LHC from the previous accelerators in the chain. Then begins the ramp-up process, which involves increasing the beam energy up to the nominal energy of 6.8 TeV. The next step – shown as “flat top” on LHC Page 1 – is where the energy in the beams is consistent, but they’re not quite ready yet. In order to achieve stable beams, the circulating beams must then be “squeezed” and adjusted using the LHC magnets. This involves making the beams narrower and more centred on their paths, and therefore more likely to produce a high number of collisions in the detectors. Only after the squeezing and adjustment has been completed can stable beams be declared and the experiments around the LHC begin their data taking.

Watch a video explaining the process from first injection to stable beams:

Delphine Jacquet and Georges Trad, both engineers in charge of the LHC, explain how the LHC beams work from the injections of protons to stable beams.  (Video: CERN)

Did you know?

Although the solar eclipse on 8 April will not affect the beams in the LHC, the gravitational pull of the moon, like the tides, changes the shape of the LHC because the machine is so big. Read more here.

ndinmore Fri, 04/05/2024 - 10:28 Byline Naomi Dinmore Publication Date Fri, 04/05/2024 - 18:30