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Metal poles around the bend
Nature Physics, Published online: 26 February 2024; doi:10.1038/s41567-024-02402-6
Electric dipoles are common in insulators, but extremely rare in metals. This situation may be about to change, thanks to flexoelectricity.Quantized topological pumping in Floquet synthetic dimensions with a driven dissipative photonic molecule
Nature Physics, Published online: 26 February 2024; doi:10.1038/s41567-024-02413-3
Although dissipation is often detrimental to the observation of topological effects, a photonic molecule driven at several incommensurate frequencies is shown to be a candidate system for quantized topological transport in synthetic dimensions.A new data centre at CERN
On 23 February 2024, a brand-new data centre was inaugurated on CERN’s Prévessin site (France), marking the completion of a major project for the Organization’s computing strategy. Spanning more than 6000 square metres and including six rooms for IT equipment with a cooling capacity of 2 MW each, the centre will host CPU (central processing unit) servers for physics data processing as well as a small amount of CPU servers and storage capacity for business continuity and disaster recovery (for example, when data is corrupted). CERN’s main data centre on the Meyrin site (Switzerland) will continue to house the majority of the Organization’s data storage capacity.
The rate of data production of the experiments at the Large Hadron Collider (LHC) continues to grow, already reaching some 45 petabytes per week, and this is expected to double in the era of the High-Luminosity LHC, the major upgrade of CERN’s current flagship accelerator, the LHC. The data from these experiments is fed into the Worldwide LHC Computing Grid (WLCG), a collaboration of around 170 data centres distributed across more than 40 countries, with a storage capacity of about 3 exabytes and one million CPU cores distributed across the network. While the Meyrin data centre has so far performed the Tier 0 role, that is, the core for the LHC Computing Grid, the Prévessin centre will provide vital additional computing capacity to CERN.
The new building was built in a record time of less than two years. It complies with strict technical requirements to ensure its environmental sustainability, and is equipped with an efficient heat-recovery system that will contribute to heating buildings on the Prévessin site.
The backbones of our interconnected world, data centres are energy-intensive infrastructures. According to a recent report, their energy consumption accounts for about 1.5% of the European Union’s total electricity consumption. Two parameters characterise the environmental sustainability of a data centre: the power usage effectiveness (PUE) – the ratio of total data centre input power to IT load power – and the water usage effectiveness (WUE) – the ratio between the use of water in data centre systems and the energy consumption of the IT equipment.
The new Prévessin centre has a PUE target of 1.1, lower than the worldwide average of 1.6, and close to 1.0, which would be the value for a perfectly efficient data centre, where all the power is delivered to the IT equipment.
It has a WUE target of 0.379 litres per kWh thanks to an innovative water recycling system. The cooling system will be automatically triggered when the outside temperature reaches 20 degrees Celsius. Five huge fan-walls installed in each room will ensure that the overall temperature does not exceed 32 degrees Celsius.
The new centre was designed, built and will be operated in the framework of a FIDIC (International Federation of Consulting Engineers) Gold Book contract, which also ensures its financial sustainability. The building’s IT rooms will gradually be equipped with up to 78 racks each. Starting from the top-floor rooms, they are expected to be fully equipped over the next ten years.
ndinmore Fri, 02/23/2024 - 15:12 Byline Antonella Del Rosso Publication Date Fri, 02/23/2024 - 15:10Artificial intelligence needs a scientific method-driven reset
Nature Physics, Published online: 23 February 2024; doi:10.1038/s41567-024-02403-5
AI needs to develop more solid assumptions, falsifiable hypotheses, and rigorous experimentation.Attosecond metrology of the two-dimensional charge distribution in molecules
Nature Physics, Published online: 23 February 2024; doi:10.1038/s41567-024-02406-2
Attosecond interferometry measurements of photoionization delays in planar carbon-based molecules can provide information on the dimension and shape of the two-dimensional hole generated in the process.Non-classical microwave–optical photon pair generation with a chip-scale transducer
Nature Physics, Published online: 23 February 2024; doi:10.1038/s41567-024-02409-z
A transducer that generates microwave–optical photon pairs is demonstrated. This could provide an interface between optical communication networks and superconducting quantum devices that operate at microwave frequencies.From particle physics to medicine
Did you know that particle accelerators are also used to treat cancer? That medical imaging has taken great leaps forwards thanks to the crystals and chips developed for particle physics? And that CERN is home to a facility that develops isotopes for medical research?
Ever since X-rays were discovered by Wilhelm Röntgen in 1895, physics and medicine have been closely intertwined. Medical imaging and cancer treatments have benefited from developments in particle physics over the years, and the innovations continue today, including in collaboration with CERN.
As part of CERN’s 70th anniversary celebrations, doctors, biologists and physicists will walk you through how the collaboration between fundamental physics and medicine is leading to innovative treatment methods and diagnostic techniques. One special patient – a researcher, writer and populariser of science – will share with us his experience of being treated for cancer in one of the four European centres for hadron therapy.
Entrance to the event is free, but registration is mandator. Click here to register.
This is the second in a series of events being organised to mark CERN’s 70th anniversary.
From the big questions in physics today to the machines of the future and the human adventure of scientific collaboration without borders, CERN invites you to discover the many facets and benefits of its research through lectures, debates and artistic performances.
Have your diaries at the ready. Consult the full programme of events on the CERN at 70 webpage.
cmenard Thu, 02/22/2024 - 16:55 Publication Date Thu, 02/22/2024 - 16:45
CERN’s accelerators gear up for action after the winter maintenance break
As winter bids farewell, the recommissioning of CERN’s accelerator complex gathers pace, with the scientific community eagerly awaiting particle beams in their experiments. Following the traditional winter break (called the “year-end technical stop” (YETS)), the Linear accelerator 4 (Linac4) is the first machine to resume beam operation, followed by the downstream machines: the Proton Synchrotron Booster (PSB), Proton Synchrotron (PS), Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC).
Beam entered Linac4 on 5 February, and the PS Booster a few days later. This week, the first beam was injected into the PS, which is now preparing the first beam for the SPS beam commissioning, scheduled to start on 1 March. The first particle beams will reach the LHC on 11 March.
The expectations for 2024 are high. In the LHC, the focus is on luminosity production with proton–proton collisions. The luminosity is an important indicator of the performance of an accelerator: it is proportional to the number of collisions that occur in the experiments in a given amount of time. The higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.
The 2024 LHC run will conclude with lead–lead ion collisions; the first lead ions will be injected into the LHC on 6 October. The 2024 run is scheduled to end on 28 October.
The resumption of operation of the accelerator complex heralds a new year of physics, surely leading to important physics results. As the countdown to 11 March continues, the operations and other expert teams are working diligently to prepare the machines and the beams for another successful physics run.
anschaef Wed, 02/21/2024 - 11:32 Byline Rende Steerenberg Publication Date Thu, 02/22/2024 - 09:31CERN’s accelerators gear up for action after the winter maintenance break
As winter bids farewell, the recommissioning of CERN’s accelerator complex gathers pace, with the scientific community eagerly awaiting particle beams in their experiments. Following the traditional winter break (called the “year-end technical stop” (YETS)), the Linear accelerator 4 (Linac4) is the first machine to resume beam operation, followed by the downstream machines: the Proton Synchrotron Booster (PSB), Proton Synchrotron (PS), Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC).
Beam entered Linac4 on 5 February, and the PS Booster a few days later. This week, the first beam was injected into the PS, which is now preparing the first beam for the SPS beam commissioning, scheduled to start on 1 March. The first particle beams will reach the LHC on 11 March.
The expectations for 2024 are high. In the LHC, the focus is on luminosity production with proton–proton collisions. The luminosity is an important indicator of the performance of an accelerator: it is proportional to the number of collisions that occur in the experiments in a given amount of time. The higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.
The 2024 LHC run will conclude with lead–lead ion collisions; the first lead ions will be injected into the LHC on 6 October. The 2024 run is scheduled to end on 28 October.
The resumption of operation of the accelerator complex heralds a new year of physics, surely leading to important physics results. As the countdown to 11 March continues, the operations and other expert teams are working diligently to prepare the machines and the beams for another successful physics run.
anschaef Wed, 02/21/2024 - 11:32 Byline Rende Steerenberg Publication Date Thu, 02/22/2024 - 09:31CMS collaboration explores how AI can be used to search for partner particles to the Higgs boson
As part of their quest to understand the building blocks of matter, physicists search for evidence of new particles that could confirm the existence of physics beyond the Standard Model (SM). Many of these beyond-SM theories postulate the need for additional partner particles to the Higgs boson. These partners would behave similarly to the SM Higgs boson, for example in terms of their “spin”, but would have a different mass.
To search for Higgs partner particles, scientists at the CMS collaboration look for the signatures of these particles in the data collected by the detector. One such signature is when the particles decay from a heavy Higgs partner (X) particle to two lighter partner particles (φ), which in turn each decay into collimated pairs of photons. Photon signatures are ideal to search for particles with unknown masses as they provide a clean, well-understood signature. However, if the φ is very light, the two photons will significantly overlap with each other and the tools usually applied for the photon identification fall apart.
This is where artificial intelligence (AI) comes in. It is well known that machine learning computer vision techniques can differentiate between many faces, and now such AI methodologies are becoming useful tools in particle physics.
The CMS experiment searched for the X and φ partners of the Higgs boson using the hypothetical process X→φφ, with both φ decaying to collimated photon pairs. To do this, they trained two AI algorithms to distinguish the overlapping pairs of photons from noise, as well as to precisely determine the mass of the particle from which they originated. A wide range of masses was explored. No evidence for such new particles was seen, enabling them to set upper limits on the production rate of this process. The result is the most sensitive search yet performed for such Higgs-like particles in this final state.
How can the scientists test the AI’s effectiveness? It is not as easy as verifying AI facial differentiation, where you can simply check by looking. Thankfully, the SM has well-understood processes, which CMS physicists used to validate and control the AI techniques. For example, the η meson, which also decays to two photons, provided an ideal test bench. Scientists at CMS were able to cleanly identify and reconstruct the η meson when searching for its decay into photons when they applied these AI techniques.
This analysis clearly shows that AI algorithms can be used to cleanly identify two-photon signatures from the noise and to search for new massive particles. These machine learning techniques are continuously improving and will continue to be used in unique analyses of LHC data, extending CMS searches to even more challenging cases.
ndinmore Tue, 02/20/2024 - 13:21 Byline CMS collaboration Publication Date Wed, 02/21/2024 - 09:30
CMS collaboration explores how AI can be used to search for partner particles to the Higgs boson
As part of their quest to understand the building blocks of matter, physicists search for evidence of new particles that could confirm the existence of physics beyond the Standard Model (SM). Many of these beyond-SM theories postulate the need for additional partner particles to the Higgs boson. These partners would behave similarly to the SM Higgs boson, for example in terms of their “spin”, but would have a different mass.
To search for Higgs partner particles, scientists at the CMS collaboration look for the signatures of these particles in the data collected by the detector. One such signature is when the particles decay from a heavy Higgs partner (X) particle to two lighter partner particles (φ), which in turn each decay into collimated pairs of photons. Photon signatures are ideal to search for particles with unknown masses as they provide a clean, well-understood signature. However, if the φ is very light, the two photons will significantly overlap with each other and the tools usually applied for the photon identification fall apart.
This is where artificial intelligence (AI) comes in. It is well known that machine learning computer vision techniques can differentiate between many faces, and now such AI methodologies are becoming useful tools in particle physics.
The CMS experiment searched for the X and φ partners of the Higgs boson using the hypothetical process X→φφ, with both φ decaying to collimated photon pairs. To do this, they trained two AI algorithms to distinguish the overlapping pairs of photons from noise, as well as to precisely determine the mass of the particle from which they originated. A wide range of masses was explored. No evidence for such new particles was seen, enabling them to set upper limits on the production rate of this process. The result is the most sensitive search yet performed for such Higgs-like particles in this final state.
How can the scientists test the AI’s effectiveness? It is not as easy as verifying AI facial differentiation, where you can simply check by looking. Thankfully, the SM has well-understood processes, which CMS physicists used to validate and control the AI techniques. For example, the η meson, which also decays to two photons, provided an ideal test bench. Scientists at CMS were able to cleanly identify and reconstruct the η meson when searching for its decay into photons when they applied these AI techniques.
This analysis clearly shows that AI algorithms can be used to cleanly identify two-photon signatures from the noise and to search for new massive particles. These machine learning techniques are continuously improving and will continue to be used in unique analyses of LHC data, extending CMS searches to even more challenging cases.
ndinmore Tue, 02/20/2024 - 13:21 Byline CMS collaboration Publication Date Wed, 02/21/2024 - 09:30
Quantum transport response of topological hinge modes
Nature Physics, Published online: 20 February 2024; doi:10.1038/s41567-024-02388-1
Topologically protected hinge modes could be important for developing quantum devices, but electronic transport through those states has not been demonstrated. Now quantum transport has been shown in gapless topological hinge states.Sound interactions across multiple modes
Nature Physics, Published online: 19 February 2024; doi:10.1038/s41567-024-02425-z
Some quantum acoustic resonators possess a large number of phonon modes at different frequencies. Direct interactions between modes similar to those available for photonic devices have now been demonstrated. This enables manipulation of multimode states.Time in a glass
Nature Physics, Published online: 19 February 2024; doi:10.1038/s41567-024-02419-x
Ageing is a non-linear, irreversible process that defines many properties of glassy materials. Now, it is shown that the so-called material-time formalism can describe ageing in terms of equilibrium-like properties.Organic molecules pumped to resonance
Nature Physics, Published online: 19 February 2024; doi:10.1038/s41567-024-02410-6
Interacting emitters are the fundamental building blocks of quantum optics and quantum information devices. Pairs of organic molecules embedded in a crystal can become permanently strongly interacting when they are pumped with intense laser light.Superradiant and subradiant states in lifetime-limited organic molecules through laser-induced tuning
Nature Physics, Published online: 19 February 2024; doi:10.1038/s41567-024-02404-4
Laser-induced tuning of pairs of lifetime-limited organic emitters allows the controlled creation of superradiant and subradiant entangled states.AEgIS experiment paves the way for new set of antimatter studies by laser-cooling positronium
AEgIS is one of several experiments at CERN’s Antimatter Factory producing and studying antihydrogen atoms with the goal of testing with high precision whether antimatter and matter fall to Earth in the same way. In a paper published today in Physical Review Letters, the AEgIS collaboration reports an experimental feat that will not only help it achieve this goal but also pave the way for a whole new set of antimatter studies, including the prospect to produce a gamma-ray laser that would allow researchers to look inside the atomic nucleus and have applications beyond physics.
To create antihydrogen (a positron orbiting an antiproton), AEgIS directs a beam of positronium (an electron orbiting a positron) into a cloud of antiprotons produced and slowed down in the Antimatter Factory. When an antiproton and a positronium meet in the antiproton cloud, the positronium gives up its positron to the antiproton, forming antihydrogen.
Producing antihydrogen in this way means that AEgIS can also study positronium, an antimatter system in its own right that is being investigated by experiments worldwide.
Positronium has a very short lifetime, annihilating into gamma rays in 142 billionths of a second. However, because it comprises just two point-like particles, the electron and its antimatter counterpart, “it’s a perfect system to do experiments with”, says AEgIS spokesperson Ruggero Caravita, “provided that, among other experimental challenges, a sample of positronium can be cooled enough to measure it with high precision”.
This is the feat accomplished by the AEgIS team. By applying the technique of laser cooling to a sample of positronium, the collaboration has already managed to more than halve the temperature of the sample, from 380 to 170 degrees kelvin. In follow-up experiments the team aims to break the barrier of 10 degrees kelvin.
AEgIS’ laser cooling of positronium opens up new possibilities for antimatter research. These include high-precision measurements of the properties and gravitational behaviour of this exotic but simple matter–antimatter system, which could reveal new physics. It also allows the production of a positronium Bose–Einstein condensate, in which all constituents occupy the same quantum state. Such a condensate has been proposed as a candidate to produce coherent gamma-ray light via the matter-antimatter annihilation of its constituents – laser-like light made up of monochromatic waves that have a constant phase difference between them.
“A Bose-Einstein condensate of antimatter would be an incredible tool for both fundamental and applied research, especially if it allowed the production of coherent gamma-ray light with which researchers could peer into the atomic nucleus.” says Caravita.
Laser cooling, which was applied to antimatter atoms for the first time about three years ago, works by slowing down atoms bit by bit with laser photons over the course of many cycles of photon absorption and emission. This is normally done using a narrowband laser, which emits light with a small frequency range. By contrast, the AEgIS team uses a broadband laser in their study.
“A broadband laser cools not just a small but a large fraction of the positronium sample,” explains Caravita. “What’s more, we carried out the experiment without applying any external electric or magnetic field, simplifying the experimental set-up and extending the positronium lifetime.”
The AEgIS collaboration shares its achievement of positronium laser cooling with an independent team, which used a different technique and posted their result on the arXiv preprint server on the same day as AEgIS.
Further material:
Video collection
Photo collection 1
Photo collection 2
About AEgIS:
The AEgIS collaboration is composed of several research groups from CERN, Istituto Nazionale di Fisica Nucleare (units of Milano, Pavia and the Trento Institute for Fundamental Physics and Applications), the University of Oslo, the Universite Paris-Saclay and the Centre National de la Recherche Scientifique, the University of Liverpool, the Warsaw University of Technology, the University of Trento, the Jagiellonian University of Krakow, the Raman Research Institute of Bangalore, the University of Innsbruck, the University and the Politecnico of Milan, the University of Brescia, the Nicolaus Copernicus University in Torun, the University of Latvia, the Institute of Physics of the Polish Academy of Sciences and the Czech Technical University of Prague.
AEgIS experiment paves the way for new set of antimatter studies by laser-cooling positronium
AEgIS is one of several experiments at CERN’s Antimatter Factory producing and studying antihydrogen atoms with the goal of testing with high precision whether antimatter and matter fall to Earth in the same way. In a paper published today in Physical Review Letters, the AEgIS collaboration reports an experimental feat that will not only help it achieve this goal but also pave the way for a whole new set of antimatter studies, including the prospect to produce a gamma-ray laser that would allow researchers to look inside the atomic nucleus and have applications beyond physics.
To create antihydrogen (a positron orbiting an antiproton), AEgIS directs a beam of positronium (an electron orbiting a positron) into a cloud of antiprotons produced and slowed down in the Antimatter Factory. When an antiproton and a positronium meet in the antiproton cloud, the positronium gives up its positron to the antiproton, forming antihydrogen.
Producing antihydrogen in this way means that AEgIS can also study positronium, an antimatter system in its own right that is being investigated by experiments worldwide.
Positronium has a very short lifetime, annihilating into gamma rays in 142 billionths of a second. However, because it comprises just two point-like particles, the electron and its antimatter counterpart, “it’s a perfect system to do experiments with”, says AEgIS spokesperson Ruggero Caravita, “provided that, among other experimental challenges, a sample of positronium can be cooled enough to measure it with high precision”.
This is the feat accomplished by the AEgIS team. By applying the technique of laser cooling to a sample of positronium, the collaboration has already managed to more than halve the temperature of the sample, from 380 to 170 degrees kelvin. In follow-up experiments the team aims to break the barrier of 10 degrees kelvin.
AEgIS’ laser cooling of positronium opens up new possibilities for antimatter research. These include high-precision measurements of the properties and gravitational behaviour of this exotic but simple matter–antimatter system, which could reveal new physics. It also allows the production of a positronium Bose–Einstein condensate, in which all constituents occupy the same quantum state. Such a condensate has been proposed as a candidate to produce coherent gamma-ray light via the matter-antimatter annihilation of its constituents – laser-like light made up of monochromatic waves that have a constant phase difference between them.
“A Bose-Einstein condensate of antimatter would be an incredible tool for both fundamental and applied research, especially if it allowed the production of coherent gamma-ray light with which researchers could peer into the atomic nucleus.” says Caravita.
Laser cooling, which was applied to antimatter atoms for the first time about three years ago, works by slowing down atoms bit by bit with laser photons over the course of many cycles of photon absorption and emission. This is normally done using a narrowband laser, which emits light with a small frequency range. By contrast, the AEgIS team uses a broadband laser in their study.
“A broadband laser cools not just a small but a large fraction of the positronium sample,” explains Caravita. “What’s more, we carried out the experiment without applying any external electric or magnetic field, simplifying the experimental set-up and extending the positronium lifetime.”
The AEgIS collaboration shares its achievement of positronium laser cooling with an independent team, which used a different technique and posted their result on the arXiv preprint server on the same day as AEgIS.
Further material:
Video collection
Photo collection 1
Photo collection 2
About AEgIS:
The AEgIS collaboration is composed of several research groups from CERN, Istituto Nazionale di Fisica Nucleare (units of Milano, Pavia and the Trento Institute for Fundamental Physics and Applications), the University of Oslo, the Universite Paris-Saclay and the Centre National de la Recherche Scientifique, the University of Liverpool, the Warsaw University of Technology, the University of Trento, the Jagiellonian University of Krakow, the Raman Research Institute of Bangalore, the University of Innsbruck, the University and the Politecnico of Milan, the University of Brescia, the Nicolaus Copernicus University in Torun, the University of Latvia, the Institute of Physics of the Polish Academy of Sciences and the Czech Technical University of Prague.
Accelerator Report: The accelerator complex gears up for action after the yearly winter maintenance break
The symbolic key to resume LHC operations will be handed over from the ACE (Accelerator Coordination and Engineering) group in the Engineering department to the Operations group on Friday, 16 February, kicking off the 2024 “particle season”.
As winter bids farewell, the recommissioning of the accelerator complex gathers pace, with the scientific community eagerly awaiting particle beams in their experiments. Following the year-end technical stop (YETS), Linac4 is the first machine to resume beam operation, followed by the downstream machines: the PS Booster, PS, SPS and LHC.
Beam entered Linac4 on 5 February, two days ahead of schedule – extra time welcomed by the Linac team. During the YETS, work was done on the chain of accelerating cavities, requiring a re-phasing – a challenging and often time-consuming task. To do so, the acceleration of the particle beam is optimised as the beam goes down the Linac: the voltage waves in the cavities are timed correctly as the beam passes by, ensuring optimum acceleration in each of the cavities and bringing the energy to 160 MeV at the end of the Linac.
This week, the beam was then sent to the PS Booster. The operations team has one week to prepare for the first beam to be injected into the PS on 21 February. The PS will then have to prepare the first beam for the SPS beam commissioning, scheduled to start on 1 March. The first particle beams will reach the LHC on 11 March, initially with one to a few bunches at most.
Before injecting particle beams, the hardware recommissioning coordinators of each machine and the many equipment experts have the task of meticulously recommissioning and validating all the subsystems. They run the machine “as if” particle beams were being accelerated, but without particles. They go through checklists, validating and ticking off thousands of tests, to give the green light for beam commissioning.
The expectations for 2024 are high. Firstly, in the LHC, the focus is on luminosity production with proton–proton collisions, aiming at an unprecedented accumulation of luminosity of up to 90 fb-1. This, together with the accumulation of luminosity forecast for the 2025 run, should provide a sizeable analysis data set to keep physicists busy during Long Shutdown 3. The 2024 LHC run will conclude with lead–lead collisions; the first lead ions will be injected into the LHC on 6 October. The 2024 run is scheduled to end on 28 October.
The injector chain has an ambitious year ahead as well: the injectors have a busy fixed-target programme and will provide beams to all the experimental facilities. The first fixed-target physics will start in the PS East Area on 22 March, followed by the PS n_TOF facility on 25 March. Physics in ISOLDE, downstream of the PS Booster, will start on 8 April, followed by the SPS North Area on 10 April. The antimatter factory is set to start delivering antiprotons to its experiments on 22 April. The AWAKE facility, behind the SPS, will run for ten weeks in total (in blocks of two or three weeks) until the middle of September, when the dismantling of the no-longer-used CERN Neutrinos to Gran Sasso (CNGS) target facility will start, to allow for a future extension of the AWAKE facility. The SPS HiRadMat facility will see four 1-week runs.
Beyond this busy physics programme, many machine development studies and tests are planned in all the machines. One of these tests will take place between mid-March and early June to configure the Linac3 source to produce magnesium ions, which will be accelerated in Linac3, injected into LEIR, and possibly even into the PS. This test will help assess the feasibility and performance of magnesium beams in the accelerator complex, for potential future applications in the LHC and the SPS North Area.
The resumption of operation of the accelerator complex heralds a new year of physics, surely leading to important physics results. As the countdown to 11 March continues, the operations and expert teams are working diligently to prepare the machines and the beams for another successful physics run.
anschaef Thu, 02/15/2024 - 10:11 Byline Rende Steerenberg Publication Date Thu, 02/15/2024 - 10:08Accelerator Report: The accelerator complex gears up for action after the yearly winter maintenance break
The symbolic key to resume LHC operations will be handed over from the ACE (Accelerator Coordination and Engineering) group in the Engineering department to the Operations group on Friday, 16 February, kicking off the 2024 “particle season”.
As winter bids farewell, the recommissioning of the accelerator complex gathers pace, with the scientific community eagerly awaiting particle beams in their experiments. Following the year-end technical stop (YETS), Linac4 is the first machine to resume beam operation, followed by the downstream machines: the PS Booster, PS, SPS and LHC.
Beam entered Linac4 on 5 February, two days ahead of schedule – extra time welcomed by the Linac team. During the YETS, work was done on the chain of accelerating cavities, requiring a re-phasing – a challenging and often time-consuming task. To do so, the acceleration of the particle beam is optimised as the beam goes down the Linac: the voltage waves in the cavities are timed correctly as the beam passes by, ensuring optimum acceleration in each of the cavities and bringing the energy to 160 MeV at the end of the Linac.
This week, the beam was then sent to the PS Booster. The operations team has one week to prepare for the first beam to be injected into the PS on 21 February. The PS will then have to prepare the first beam for the SPS beam commissioning, scheduled to start on 1 March. The first particle beams will reach the LHC on 11 March, initially with one to a few bunches at most.
Before injecting particle beams, the hardware recommissioning coordinators of each machine and the many equipment experts have the task of meticulously recommissioning and validating all the subsystems. They run the machine “as if” particle beams were being accelerated, but without particles. They go through checklists, validating and ticking off thousands of tests, to give the green light for beam commissioning.
The expectations for 2024 are high. Firstly, in the LHC, the focus is on luminosity production with proton–proton collisions, aiming at an unprecedented accumulation of luminosity of up to 90 fb-1. This, together with the accumulation of luminosity forecast for the 2025 run, should provide a sizeable analysis data set to keep physicists busy during Long Shutdown 3. The 2024 LHC run will conclude with lead–lead collisions; the first lead ions will be injected into the LHC on 6 October. The 2024 run is scheduled to end on 28 October.
The injector chain has an ambitious year ahead as well: the injectors have a busy fixed-target programme and will provide beams to all the experimental facilities. The first fixed-target physics will start in the PS East Area on 22 March, followed by the PS n_TOF facility on 25 March. Physics in ISOLDE, downstream of the PS Booster, will start on 8 April, followed by the SPS North Area on 10 April. The antimatter factory is set to start delivering antiprotons to its experiments on 22 April. The AWAKE facility, behind the SPS, will run for ten weeks in total (in blocks of two or three weeks) until the middle of September, when the dismantling of the no-longer-used CERN Neutrinos to Gran Sasso (CNGS) target facility will start, to allow for a future extension of the AWAKE facility. The SPS HiRadMat facility will see four 1-week runs.
Beyond this busy physics programme, many machine development studies and tests are planned in all the machines. One of these tests will take place between mid-March and early June to configure the Linac3 source to produce magnesium ions, which will be accelerated in Linac3, injected into LEIR, and possibly even into the PS. This test will help assess the feasibility and performance of magnesium beams in the accelerator complex, for potential future applications in the LHC and the SPS North Area.
The resumption of operation of the accelerator complex heralds a new year of physics, surely leading to important physics results. As the countdown to 11 March continues, the operations and expert teams are working diligently to prepare the machines and the beams for another successful physics run.
anschaef Thu, 02/15/2024 - 10:11 Byline Rende Steerenberg Publication Date Thu, 02/15/2024 - 10:08Σελίδες
