Stephen Hawking during a visit to the Large Hadron Collider (LHC) tunnel in March 2013, prior to the Inaugural Fundamental Physics Prize Ceremony in Geneva. (Image: Laurent Egli/CERN)
Theoretical physicist, Stephen Hawking has died today, 14 March, aged 76.
“Hawking’s results have a great impact on theoretical research done at CERN”, states Gian Giudice, Head of Theoretical Physics at CERN.
“For me, the highlights of Hawking’s work are in black hole physics and the origin of the universe: Hawking radiation and thermodynamics of black holes, area theorem on black-hole horizon surface and the Hartle-Hawking state of the primordial universe,” explains Giudice.
“Stephen Hawking was one of the giants, and stars, of physics of the past century. He has inspired a whole generation with his ability to present complex science in a popular way,” continues Eckhard Elsen, CERN Director for Research and Computing. “He spurred interest in black holes and the physics related to it, including future gravitational wave experiments.”
Stephen Hawking during his tour of the ATLAS cavern in 2006 with (left to right) theorist Thomas Hertog, ATLAS spokesperson Peter Jenni and ATLAS deputy spokesperson, and now CERN Director-General, Fabiola Gianotti. (Image: Maximilien Brice and Claudia Marcelloni/CERN)
“Each time Stephen Hawking visited CERN, we were impressed by his great enthusiasm, vitality and passion for knowledge. He was a brilliant example on how to face disease with courage. He was a warrior.” – Fabiola Gianotti, CERN Director-General.
“A giant of our field has left us, but his immortal contributions will remain forever.” – Gian Giudice, Head of Theoretical Physics at CERN.
Today, 9 March, marks the end of CERN’s annual winter shut down. The Laboratory’s massive accelerator complex will soon begin to lumber out of its winter hibernation and resume accelerating and colliding particles.
But while the Large Hadron Collider (LHC) has not been filled with protons since the Year-End Technical Stop (YETS) began on 4 December 2017, its tunnels and experimental caverns have been packed with people performing maintenance and repairs as well as testing components for future accelerators.
Watch this short overview of activities from around the LHC ring during the YETS (Video: CERN)
Today, CERN’s Engineering department hands the accelerator complex back to the Beams department, who will commence hardware commissioning for 2018. This commissioning will culminate in the restart of the LHC, planned for early April.
Antimatter’s journey between the ELENA and ISOLDE facilities (Image: CERN)
Antimatter vanishes instantly when it meets matter. But researchers have developed ways to trap it and increase its lifespan in order to use it to study matter. A new project called PUMA (antiProton Unstable Matter Annihilation) aims to trap a record one billion antiprotons at CERN’s GBAR experiment at the ELENA facility and keep them for several weeks. Such a long storage time would allow the trapped antiprotons to be loaded into a van and transported to the neighbouring ISOLDE ion-beam facility located a few hundred metres away. At ISOLDE, the antiprotons would then be collided with radioactive ions so that exotic nuclear phenomena could be studied.
To trap the antiprotons for long enough for them to be transported and used at ISOLDE, PUMA plans to use a 70-cm-long “double-zone” trap inside a one-tonne superconducting solenoid magnet and keep it under an extremely high vacuum (10-17 mbar) and at cryogenic temperature (4 K). The so-called storage zone of the trap will confine the antiprotons, while the second zone will host collisions between the antiprotons and radioactive nuclei that are produced at ISOLDE but decay too rapidly to be transported and studied elsewhere.
The project hopes to study the properties of radioactive nuclei by measuring the pion particles emitted in the collisions between the nuclei and the antiprotons. Such measurements would help determine how often the antiprotons annihilate with the nuclei’s protons or neutrons, and, therefore, their relative densities at the surface of the nucleus. The relative densities would then indicate whether the nuclei have exotic properties, such as thick neutron skins, which correspond to a significantly higher density of neutrons than protons at the nuclear surface, and extended halos of protons or neutrons around the nuclear core.
Today, CERN is the only place in the world where low-energy antiprotons are produced, but “this project might lead to the democratisation of the use of antimatter”, says Alexandre Obertelli, a physicist from the Darmstadt technical university (TU Darmstadt) who is leading the project. He plans to build and develop the solenoid, trap and detector in the coming two years, with the aim of producing the first collisions at CERN in 2022.
Obertelli was awarded an ERC Consolidator Grant from the European Research Council and the five-year PUMA project was launched in January this year. Along with researchers from RIKEN in Japan and CEA Saclay and IPN Orsay in France, he has submitted a letter of intent to CERN’s experiment committee to pave the way towards PUMA becoming a CERN-recognised experiment.
CERN director for accelerators and technology, Frédérick Bordry, highlighted procurement opportunities for the High Luminosity LHC upgrade project. (Image credit: Morten Nørulf/BSBF)
Big science equals big business, whether it is manufacturing giant superconducting magnets for particle colliders or perfecting mirror coatings for space telescopes. Last week, the Big Science Business Forum (BSBF), in Copenhagen, Denmark, saw more than 1000 delegates from more than 500 companies and organisations spanning 30 countries discuss opportunities in the current big-science landscape.
Nine of the world’s largest research facilities – CERN, EMBL, ESA, ESO, ESRF, ESS, European XFEL, F4E and ILL – offered insights into procurement opportunities and orders worth billions of euros for European companies in the coming years. These range from advisory engineering work and architectural tasks, to advanced technical equipment, construction projects and radiation-resistant materials. A further nine organisations also joined the conference programme: ALBA, DESY, ELI-NP, ENEA, FAIR, MAX IV, SCK•CEN – MYRRHA, PSI and SKA, gathering 18 of the world’s most advanced big-science organisations under one roof.
CERN participants presented 19 of the 120 talks, covering not only the business and knowledge transfer opportunities in general, but also the specifics of the CERN environment. Many focussed on the upcoming contracts for the Large Hadron Collider (LHC) upgrade: the High Luminosity LHC project. As well as material, power and electrical engineering and the manufacturing of components, talks looked at the needs for vacuum technology, radio-frequency systems, beam instrumentation, industrial controls, computing and safety.
The big-science market is currently fragmented by various different quality standards and procurement procedures of the different laboratories. BSBF provided a space to discuss the entry challenges for businesses and suppliers – including small- and medium-sized enterprises – that can be valuable business partners for big science projects.
"The vision behind BSBF is to provide an important stepping stone towards establishing a stronger, more transparent and efficient big-science market in Europe and we hope that this will be the first of a series of BSBF in different European cities," said Agnete Gersing of the Danish ministry for higher education and science during the opening address.
The event, which ran from 26 to 28 February, featured around 800 one-to-one business meetings. Parallel sessions covered 16 topics concerning big science as a business area, addressing topics such as the investment potential and best practices of Europe’s big-science market.
“Much of the most advanced research takes place at big-science facilities, and their need for high-tech solutions provides great innovation and growth opportunities for private companies,” said Danish minister for higher education and science, Søren Pind.
Find out more about doing business with CERN and about the industrial opportunities of the new High Luminosity LHC project via CERN’s procurement website.
The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator (Image: Maximilien Brice/Julien Ordan/CERN)
This is the last chance to go to the LHC tunnel before the CERN accelerators complex restarts soon. Our scientists will be answering your questions as well as explaining how CERN’s accelerators work and why they stop in winter, and what physicists are up to when there’s no beams and no collisions.
Watch the live on Facebook or below, from 4pm.
Linac4 is CERN’s newest accelerator. It was inaugurated in May 2017. (Image: Maximilien Brice/CERN)
CERN’s newest accelerator, Linac4, is on its way to join the LHC injection chain. It was inaugurated in May 2017, after two decades of design and construction.
For the past 40 years, CERN’s accelerator complex has been served by Linac2, which is still injecting protons into the PS and SPS from where they end up in the Large Hadron Collider (LHC).
Although the construction of this workhorse of the CERN accelerator chain was an important step forward for CERN, and contributed to major physics discoveries, including the W, Z and Higgs bosons, Linac2’s relatively low energy and intensity are not compatible with the demanding requirements of the LHC luminosity upgrade (HL-LHC). For this reason, in 2007, it was decided to replace Linac2 with a more suitable injector for the LHC’s future.
A decade later, in spring 2017, the 160 MeV Linac4 was fully commissioned and entered a stand-alone operation run to assess and improve its reliability, prior to being connected to the CERN accelerator complex. The machine’s overall availability during this initial run reached 91 per cent – an amazing value for an accelerator whose beam commissioning was completed only a few months earlier. The Linac4 reliability run will continue well into 2018, sending the beam round-the-clock to a dump located at the end of the accelerating section under the supervision of the CERN Control Centre (CCC) operation team.
Linac4 will be connected to the next accelerator in the chain, the PSB, in 2019 at the beginning of the LHC Long Shutdown 2. Test beams will be made available to the PSB as soon as 2020, and from 2021 all protons at CERN will come from the new Linac4, marking the end of a 20 year-long journey of design and construction that has raised many challenges and inspired innovative solutions.
It’s expected that Linac4 will have a long life – at least as long as Linac2 – and play a vital role at the high-luminosity LHC and beyond.
Learn more about Linac4 in this CERN Courier article.
A virtual tour of linac4. (Video: Audiovisual Production Service/CERN)
Georges Charpak’s 'multiwire proportional chamber' particle detector consisted of many parallel wires, each connected to individual amplifiers. Linked to a computer, it could achieve a counting rate a thousand times better than existing detection techniqu
Fifty years ago today, Georges Charpak revolutionised particle detection while working at CERN when his paper detailing the invention of a new particle detection system, was published. The new detector technique could record millions of particle tracks each second, instead of the one or two tracks captured by earlier methods. The first multiwire proportional chamber was born.
Until 1968, most detection in particle physics meant examining thousands of photographs from bubble or spark chambers, flash tubes or scintillation counters, to look for interesting tracks left behind from the debris of particle collisions. Discovering new particles or phenomenon often meant searching for rare one-in-a-billion interactions. These early photographic methods were not able to quickly choose that one, making the discovery of new particles and new phenomenon time-consuming, painstaking work.
Then came a revolution in transistor amplifiers. While a camera can detect a spark, a detector wire connected to an amplifier can detect a much smaller effect. Georges Charpak realised that with modern electronics, and by connecting the detector directly to a computer, you could dramatically increase data collection. On 23 February 1968, he and colleagues published a paper entitled “the use of multiwire proportional counters to select and localize charged particles”.
The multiwire proportional chamber used a much older piece of equipment – the proportional counter, such as a Geiger Müller tube – in a new way.
In a proportional counter, an electrical voltage is applied to a gas-filled tube with a wire running through its centre. The voltage ionises the gas, as negatively-charged electrons are liberated from the gas atoms and move towards the wire in the centre. Here the high electrical field means these negative ions move faster, ionising more of the gas, freeing more electrons to be accelerated, and so on. This avalanche of ions creates an electrical signal on the wire, which shows the position of the first ionisation.
Charpak proposed, instead of a tube and a single wire, to use a gas-filled box with a large number of parallel detector wires running through it. Each wire was connected to individual amplifiers, so acted as an independent proportional counter. When linked to a computer, this could achieve a counting rate a thousand times better than any existing detectors.
The invention revolutionised particle detection, pushing it into the electronic era.
In 1992 Charpak won the Physics Nobel Prize for his “breakthrough in the technique for exploring the innermost parts of matter”, and today many experiments in particle physics routinely use some type of track detector based on the principle of Charpak’s multiwire proportional chamber. It has contributed to important discoveries in particle physics including the charm quark, the W and Z bosons, and the gluon, and it has had several other applications in medicine and biology.Find out more in the CERN Courier:
Installation of a collimator in the LHC. Collimators protect the sensitive equipment from escaping particles. (Image: Maximilien Brice, Julien Ordan/CERN)
The performance of the LHC relies on accelerating and colliding beams made of tiny particles with unprecedented intensities. If even a small fraction of the circulating particles deviates from the precisely set trajectory, it can quench a super-conducting LHC magnet or even destroy parts of the accelerator. The energy in the two LHC beams is sufficient to melt almost one tonne of copper.
This is why the LHC shows its teeth every time particles misbehave. These “teeth” are part of special devices around the LHC, called collimators. Their jaws – moveable blocks of robust materials – close around the beam to clean it of stray particles before they come close to the collision regions. The materials the jaws are made of can withstand extreme conditions of temperature and pressure, as well as high levels of radiation.
More than a hundred of these bodyguards are placed around the LHC. They are also installed on each side of the LHC experiments to absorb the stray particles before they come close to the collision regions.
With the expected increase in the number of particle collisions in the High-Luminosity LHC, the beam intensity will be much higher. New collimators are being developed by CERN’s Engineering department to meet the beam-cleaning requirements of the future project. Some of the recent innovations in the LHC collimation system include a wire and a crystal collimator. You can learn more about them in this article.
Display of a candidate event for a W boson decaying into one muon and one neutrino from proton-proton collisions recorded by ATLAS with LHC stable beams at a collision energy of 7 TeV (Image: CERN)
In a paper published today in the European Physical Journal C, the ATLAS Collaboration reports the first high-precision measurement at the Large Hadron Collider (LHC) of the mass of the W boson. This is one of two elementary particles that mediate the weak interaction – one of the forces that govern the behaviour of matter in our universe. The reported result gives a value of 80370±19 MeV for the W mass, which is consistent with the expectation from the Standard Model of Particle Physics, the theory that describes known particles and their interactions.
The measurement is based on around 14 million W bosons recorded in a single year (2011), when the LHC was running at the energy of 7 TeV. It matches previous measurements obtained at LEP, the ancestor of the LHC at CERN, and at the Tevatron, a former accelerator at Fermilab in the United States, whose data made it possible to continuously refine this measurement over the last 20 years.
The W boson is one of the heaviest known particles in the universe. Its discovery in 1983 crowned the success of CERN’s Super proton-antiproton Synchrotron, leading to the Nobel Prize in physics in 1984. Although the properties of the W boson have been studied for more than 30 years, measuring its mass to high precision remains a major challenge.
“Achieving such a precise measurement despite the demanding conditions present in a hadron collider such as the LHC is a great challenge,” said the physics coordinator of the ATLAS Collaboration, Tancredi Carli. “Reaching similar precision, as previously obtained at other colliders, with only one year of Run 1 data is remarkable. It is an extremely promising indication of our ability to improve our knowledge of the Standard Model and look for signs of new physics through highly accurate measurements.”
The Standard Model is very powerful in predicting the behaviour and certain characteristics of the elementary particles and makes it possible to deduce certain parameters from other well-known quantities. The masses of the W boson, the top quark and the Higgs boson for example, are linked by quantum physics relations. It is therefore very important to improve the precision of the W boson mass measurements to better understand the Higgs boson, refine the Standard Model and test its overall consistency.
Remarkably, the mass of the W boson can be predicted today with a precision exceeding that of direct measurements. This is why it is a key ingredient in the search for new physics, as any deviation of the measured mass from the prediction could reveal new phenomena conflicting with the Standard Model.
The measurement relies on a thorough calibration of the detector and of the theoretical modelling of the W boson production. These were achieved through the study of Z boson events and several other ancillary measurements. The complexity of the analysis meant it took almost five years for the ATLAS team to achieve this new result. Further analysis with the huge sample of now-available LHC data, will allow even greater accuracy in the near future.
The TOTEM experiment studies protons that stay intact after collisions in the LHC. (Image: Maximilien Brice/CERN)
Protons are known to contain quarks and gluons. But are gluons behaving as expected?
Scientists from the TOTEM (Total, elastic and diffractive cross-section measurement) collaboration may have found indirect evidence of a subatomic gluon-compound in proton-proton collisions. First theorised in the 1970s, such a state, then dubbed “Odderon”, consists of an odd number of gluons. This state is unusual, as gluons are normally observed in pairs.
Usually, the protons that collide in the LHC shatter and create new particles. Sometimes though, in about 25 percent of the time, they survive the encounter intact. Instead of breaking in pieces, they only change their direction and emerge from the detector at very small angles to the beampipe – their deviation at a 200-metre distance is in the order of one millimetre. This kind of interaction is called “elastic scattering” and it is the specialty of TOTEM, CERN’s longest experiment. To be able to detect the survived protons, its detectors are spread across almost half a kilometre around the CMS interaction point.
The quarks in the proton are bound by gluons, the carriers of the strong force. Physicists have successfully explained low-momentum elastic scattering at high energies with the exchange of a “Pomeron”, which in modern language is a state of two teamed-up gluons.
TOTEM precisely measured the elastic-scattering process at 13 TeV to extract the total probability for proton-proton collisions as well as the so-called rho parameter that helps to explain the difference in proton-proton and antiproton-proton scattering.
Combining these two measurements, TOTEM finds better agreement with theoretical models that indicate the exchange of three aggregated gluons. Although this exchange has been predicted by the Quantum Chromodynamics (QCD) theory back in the 1980s, no experimental evidence had been presented to date.
The measurements also hint towards a slow-down of the total probability of scattering with energy. While somewhat expected at the very highest energy, there has been no indication of such an effect in previous data.
"These measurements explore for the first time the behaviour of protons in elastic interactions at the highest energy of 13 TeV. These results obtained with a record precision were made possible by the excellent performance of the TOTEM detectors and the exceptional capabilities of the Large Hadron Collider,” observed Simone Giani, the TOTEM spokesperson.
If three gluons really were to form a compound, it should appear in other scattering experiments. Physicists are hence looking forward to dedicated experiments to establish whether such a compound is actually being formed. In order to further explore and confirm the theoretical interpretations, a special LHC proton run at an energy of 900 GeV is planned to take place in 2018 to collect more data and it will involve also other LHC experiments.
Evangelia Gousiou (right): “Nothing beats the rush you get when something that you designed works for the first time.” (Image: Jacques Fichet/CERN)
With 11 February marking the International Day of Women and Girls in Science, female physicists, engineers and computer scientists from CERN and from Fermilab share their experiences of building a career in science.Evangelia Gousiou: “Nothing beats the rush you get when something that you designed works for the first time.”
Electronics engineer, Evangelia Gousiou, talks about what led her to a career in engineering. (Video: Jacques Fichet/CERN)
Electronics engineer, Evangelia Gousiou, began her career studying IT and Electronics in Athens, Greece, before beginning an internship at a manufacturing plant in Thailand. She came to CERN for a one-year position, and now, ten years later is still at CERN enjoying a job that is never boring.
“Work is never repetitive, which makes it very rewarding. I usually follow a project through all its stages from conception of the architecture, to the coding and the delivery to the users of a product that I have built to be useful for them. So I see the full picture and that keeps me engaged.” - Evangelia Gousiou
For Evangelia, to be a good electronics engineer means knowing a range of disciplines, from software to mechanics. There is also the human aspect, as she works daily with people from many different cultures.
At school, her favourite subjects were maths and physics, as she enjoyed finding out how things worked, yet Evangelia never dreamt of being an engineer when she grew up. When the time came to choose what to study, she felt that engineering would be something interesting to study and future-proof, and then she got hooked and now can’t imagine doing anything else. “I would recommend engineering professions for their intellectual challenge and the empowerment that they bring,” she beams.
A CLIC X-band prototype structure built by PSI using Swiss FEL technology. (Image credit: M Volpi)
What if accelerators could be more compact and more cost-effective? It would make their use in research, industry and medicine more affordable and more accessible. This is where the CompactLight project steps in. This new European project, which kicked off on 25 January at CERN, aims to use advanced linear-accelerator (linac) technology, developed at CERN and elsewhere, to develop a new generation of compact X-ray free-electron lasers (XFELs).
XFELs work by accelerating electrons at almost the speed of light before sending them through “undulators”, which are an array of magnets producing alternating magnetic fields. These fields deflect the electrons back and forth to produce high-intensity X-ray beams of unprecedented brilliance and quality. These X-ray beams provide novel ways to probe matter and allows researchers to make “movies” of ultrafast biological processes. The demand for such high-quality X-rays is large, as the field still has great and largely unexplored potential for science and innovation – potential that can be unlocked if the linacs that drive the X-ray generation can be made smaller and cheaper.
By using a technology known as “X-band”, linacs can accelerate electrons with higher accelerating-gradients, resulting in shorter accelerating cavities and hence a more compact machine. X-band technology is the result of years of intense research and development at SLAC in the US, KEK in Japan and at CERN in the context of the Compact Linear Collider (CLIC) project.
The latest developments in high-quality beam sources, as well as innovative undulators are also part of the recipe for achieving a significant reduction in facility cost. Compared with existing XFELs, the proposed facility can have a lower electron-beam energy (due to the enhanced undulator performance), so can be more compact (with both lower energy and a higher accelerating-gradient) and have lower electrical power demand.
Success for CompactLight will have a much wider impact: not just establishing X-band technology as a new option for accelerator-based facilities, but integrating advanced undulators to the next generation of compact photon sources. This can help the wider spread of a new generation of compact X-band-based accelerators and light sources, with a large range of applications including medical use, and enable the development of compact cost-effective X-ray facilities at national or even university level across and beyond Europe.
The three-year CompactLight project, funded by the European Commission’s Horizon 2020 programme, brings together a consortium of 21 leading European institutions, including Elettra, CERN, PSI, KIT and INFN, in addition to seven universities and two industry partners (Kyma and VDL). The CompactLight kick off took place during the 2018 CLIC workshop, held at CERN.
This article is based on a recent CERN Courier article.
A PET scan of the human brain showing energy consumption. The brain consumes seven times less power than a typical laptop but is capable of far more complex tasks. (Image credit: Jens Maus, Wikimedia Commons)
Understanding the fundamental constituents of the universe is tough. Making sense of the brain is another challenge entirely. Each cubic millimetre of human brain contains around 4 km of neuronal “wires” carrying millivolt-level signals, connecting innumerable cells that define everything we are and do. The ancient Egyptians already knew that different parts of the brain govern different physical functions, and a couple of centuries have passed since physicians entertained crowds by passing currents through corpses to make them seem alive. But only in recent decades have neuroscientists been able to delve deep into the brain’s circuitry.
On 25 January, speaking to a packed audience in CERN’s theory department, Vijay Balasubramanian of the University of Pennsylvania described a physicist's approach to solving the brain. Balasubramanian did his PhD in theoretical particle physics at Princeton University and also worked on the UA1 experiment at CERN’s Super Proton Synchrotron in the 1980s. Today his research ranges from string theory to theoretical biophysics, where he applies methodologies common in physics to model the neural topography of information processing in the brain.
“We are using, as far as we can, hard mathematics to make real, quantitative, testable predictions, which is unusual in biology.” - Vijay Balasubramanian
The brain's basic architecture is reasonably well understood. Highly complex sensory and cognitive tasks are carried out by the cooperative action of many specialised neurons and circuits, each of which has a surprisingly simple function. Balasubramanian used examples including our sense of smell, which allows humans and other animals to distinguish vast arrays of odour mixtures using very limited neural resources, and our “sense of place" (how we mentally represent our physical location) to demonstrate that brains have evolved neural circuits that exploit sophisticated principles of mathematics – some of which are only now being discovered.
Remarkably, predictions made by fairly crude models are turning out to describe the brain’s circuits rather well, often challenging traditional thinking. In general, Balasubramanian’s calculations suggest that animals have evolved to get the biggest cognitive bang for the least possible number of neurons. “Neurons are expensive!” he says, pointing out that the brain makes up just two per cent of our bodyweight but represents 20 per cent of our metabolic load. The brain consumes just 12W of power, seven times less than a typical laptop computer, yet boasts significantly more computational power harnessed to perform subtler functions. “The brain can make us fall in love, whereas the computer hardly recognizes a face,” he says.
Still, Balasubramanian thinks humans overestimate their cognitive abilities: we are not quite as special as we think we are. He argues that the majority of our brain’s behaviour stems from primal wiring that is common to most vertebrates. While a quantitative understanding of higher concepts such as “thoughts” or “consciousness” is still far off, clearly there is fertile ground for physicists to explore in the fast changing world of neuroscience.
Watch the recording of Balasubramanian's CERN talk here.
CERN Director-General, Fabiola Gianotti, (second from right) joins her fellow co-chairs at the World Economic Forum press conference earlier today. (Image: WEF)
This week, CERN's Director-General, Fabiola Gianotti, is attending the annual meeting of the World Economic Forum in Davos as co-chair.
Among the discussions and exchanges, she will be taking part in a panel discussion today at 6pm CET entitled "Creating a shared future in a fractured world" alongside fellow co-chairs: Chetna Sinha, Erna Solberg, Christine Lagarde, Sharan Burrow, Ginni Rometty and Isabelle Kocher. Watch it live here.
On Thursday 25 January, she will take part in a panel discussion at 11.50am CET "Creating a shared future through education and empowerment" alongside Justin Trudeau, Orit Gadiesh and Malala Yousafzai. Watch it live here.
"It is a great honour to have been chosen for this role and I hope to show the importance of scientific input in global discussions," says Fabiola Gianotti.
"I will take this great opportunity to highlight the role of fundamental science in the progress of knowledge, as a driver of innovation to the benefit of society and as a way to foster peaceful collaboration among people from all over the world. I will also emphasise the importance of education in science, technology, engineering and mathematics and of open access to scientific results and developments for all."
Read more about how she believes that science is universal and unifying.
An overhead crane moves the new 6.3m by 2.3m module into its vertical position. (Image: Maximilien Brice/CERN)
These detectors are prototypes for the US-based Deep Underground Neutrino Experiment (DUNE), which will study the differences between neutrinos and anti-neutrinos to help understand how the Universe came to be made up of matter.
ProtoDUNE at CERN consists of two large neutrino detectors, each filled with liquid argon.
The APAs are large rectangular steel frames covered with approximately 4000 wires and will be used to read the signal from particle tracks generated inside the liquid-argon detector.
Many more components for the detector are being built around the world and some, such as this APA, are arriving at CERN to be installed in protoDUNE.
The CMS experiment is looking for exotic long-lived particles that could get trapped in its detector layers (Image: Michael Hoch, Maximilien Brice/CERN)
New particles produced in the LHC’s high-energy proton-proton collisions don’t hang around for long. A Higgs boson exists for less than a thousandth of a billionth of a billionth of a second before decaying into lighter particles, which can then be tracked or stopped in our detectors. Nothing rules out the existence of much longer-lived particles though, and certain theoretical scenarios predict that such extraordinary objects could get trapped in the LHC detectors, sitting there quietly for days.
The CMS collaboration has reported new results in its search for heavy long-lived particles (LLPs), which could lose their kinetic energy and come to a standstill in the LHC detectors. Provided that the particles live for longer than a few tens of nanoseconds, their decay would be visible during periods when no LHC collisions are taking place, producing a stream of ordinary matter seemingly out of nowhere.
The CMS team looked for these types of non-collision events in the densest detector materials of the experiment, where the long-lived particles are most likely to be stopped, based on LHC collisions in 2015 and 2016. Despite scouring data from a period of more than 700 hours, nothing strange was spotted. The results set the tightest cross-section and mass limits for hadronically-decaying long-lived particles that stop in the detector to date, and the first limits on stopped long-lived particles produced in proton-proton collisions at an energy of 13 TeV.
The Standard Model, the theoretical framework that describes all the elementary particles, was vindicated in 2012 with the discovery of the Higgs boson. But some of the universe’s biggest mysteries remain unexplained, such as why matter prevailed over antimatter in the early universe or what exactly dark matter is. Long-lived particles are among numerous exotic species that would help address these mysteries and their discovery would constitute a clear sign of physics beyond the Standard Model. In particular, the decays searched for in CMS concerned long-lived gluinos arising in a model called “split” supersymmetry (SUSY) and exotic particles called “MCHAMPs”.
While the search for long-lived particles at the LHC is making rapid progress at both CMS and ATLAS, the construction of a dedicated LLP detector has been proposed for the high-luminosity era of the LHC. MATHUSLA (Massive Timing Hodoscope for Ultra Stable Neutral Particles) is planned to be a surface detector placed 100 metres above either ATLAS or CMS. It would be an enormous (200 × 200 × 20 m) box, mostly empty except for the very sensitive equipment used to detect LLPs produced in LHC collisions.
Since LLPs interact weakly with ordinary matter, they will experience no trouble travelling through the rocks between the underground experiment and MATHUSLA. This process is similar to how weakly interacting cosmic rays travel through the atmosphere and pass through the Earth to reach our underground detectors, only in reverse. If constructed, the experiment will explore many more scenarios and bring us closer to discovering new physics.
CERN Director General, Fabiola Gianotti, the Minister of Foreign Affairs of the Republic of Lithuania, Linas Linkevičius, and the President of the Republic of Lithuania, Dalia Grybauskaitė at the signing of the agreement (Image: Julie Haffner/ CERN)
Today, the Republic of Lithuania became an Associate Member State of CERN. This follows official notification to CERN that the Republic of Lithuania has completed its internal approval procedures, as required for the entry into force of the Agreement, signed in June 2017, granting that status to the country.
Lithuania’s relationship with CERN dates back to 2004, when an International Cooperation Agreement was signed between the Organization and the government of the Republic of Lithuania setting priorities for the further development of scientific and technical cooperation between CERN and Lithuania in high-energy physics. One year later, in 2005, a Protocol to this Agreement was signed, paving the way for the participation of Lithuanian universities and scientific institutions in high-energy particle physics experiments at CERN.
Lithuania has contributed to the CMS experiment since 2007 when a Memorandum of Understanding (MoU) was signed marking the beginning of Lithuanian scientists’ involvement in the CMS collaboration. Lithuania has also played an important role in database development at CERN for CMS data mining and data quality analysis. Lithuania actively promoted the BalticGrid in 2005.
In addition to its involvement in the CMS experiment, Lithuania is part of two collaborations that aim to develop detector technologies to address the challenging upgrades needed for the High-Luminosity LHC.
Since 2004, CERN and Lithuania have also successfully collaborated on many educational activities aimed at strengthening the Lithuanian particle physics community. Lithuania has been participating in the CERN Summer Student programme and 53 Lithuanian teachers have taken part in CERN’s high-school teachers programme.
The associate membership of Lithuania strengthens the long-term partnership between CERN and the Lithuanian scientific community. Associate Membership allows Lithuania to take part in meetings of the CERN Council and its committees (Finance Committee and Scientific Policy Committee). It also makes Lithuanian scientists eligible for staff appointments. Finally, Lithuanian industry is henceforth entitled to bid for CERN contracts, thus opening up opportunities for industrial collaboration in areas of advanced technology.
(Video: Daniel Dominguez/CERN)
CERN wishes you Happy New Year 2018.
In 2017, CERN pushed the limits of knowledge with many new developments. Its flagship machine, the Large Hadron Collider (LHC), collected a staggering amount of data, accumulating 5 million billion proton-proton collisions.
In 2018, the LHC begins its final year of data-taking before the second long technical stop. This technical stop, set to last from late 2018 to early 2021, will allow CERN’s technicians, engineers and physicists to renovate and improve the accelerator complex, as well as the experiment collaborations to prepare their detectors to fully exploit the future higher luminosity of the machine.
Whether with the LHC or with the many other research facilities, the year looks set to promise many scientific and technological advances to enrich our understanding of particle physics and to benefit society as a whole.
(Video: Noemi Caraban/CERN)
This year has been rich with new facilities for research and applications, physics results that enrich human knowledge and international collaborations that bring together more countries, as well as programmes to train and educate thousands of students and teachers. This video showcases the highlights of 2017 at CERN.
Find out more details about these events on the “updates” page.
See you next year for new adventures to the limits of knowledge and technology.
On a peaceful afternoon in early summer 1977, the laboratory of CERN radiobiologist Marilena Bianchi was visited by a physicist with a pretty unusual request. He asked for her help in his quest to create a first image of a mouse using a PET (positron-emission tomography) camera.
The physicist, David Townsend, had been helping Alan Jeavons, also a physicist at CERN. Jeavons had developed a new detector, based on a high-density avalanche chamber, to take PET images. Townsend had developed the software to reconstruct the data from the detector and to turn them into an image.
Once they were ready, Townsend asked Bianchi, who was developing medical applications of CERN technologies, to inject a mouse with a small amount of short-lived radioisotope, which was absorbed into the skeleton of the animal.
The first PET image taken at CERN, in 1977, showing the skeleton of a mouse. Unlike a modern-day image, this one is truly digital – it is composed of numbers. Each number indicates how much of the isotope has been emitted at each point. (Image: CERN)
The isotope she injected emitted positrons, the antimatter twins of electrons. These positrons bumped into nearby electrons and in the collision a pair of photons was created. The photons shot out in exactly opposite directions. By placing two detectors around the mouse, Jeavons and Townsend picked up these pairs of photons, pinpointing where the positron annihilations occurred. “A few days later, David Townsend came back with this beautiful picture. The first mouse scan taken with a PET camera,” remembers Streit-Bianchi. “The findings were then presented at a conference in October 1977.”
PET was not invented at CERN, but the work carried out by Jeavons and Townsend made a major contribution to its development, thanks to the type of detector and computer programme developed for image-taking analysis. After the initial success, Jeavons and Townsend devoted their careers to improving medical imaging. Later, Townsend and co-workers in the US suggested to combine PET-CT (computed tomography) to see both metabolic and anatomic information. This was a major breakthrough for cancer diagnosis and treatment follow up.
“I am very proud. The inventiveness of these two physicists and their desire to develop a special PET camera resulted in the further development of a perfectly safe method to inquire what is happening in the body.” - Streit-Bianchi
Forty years on, PET technology is even more advanced thanks to the work carried out at CERN and other research laboratories around the world. The technologies and scientific advances behind high-energy physics – through developments in accelerators, detectors and computing – have helped to contribute to the field of medical imaging.
Twenty years ago, with Marilena Streit-Bianchi’s help, CERN established a dedicated policy and structure for knowledge and technology transfer. The CERN group of the Crystal Clear Collaboration is now developing new fast detector prototypes for use in both high-energy physics experiments and medical imaging, with particular emphasis on the PET technology. Read more about Streit-Bianchi’s 41-year career at CERN in the September 2014 CERN Courier.
Find out more about PET at CERN in the June 2005 CERN Courier.