Image caption No small undertaking: the experiments occupy huge subterranean caverns
- Every time fundamental research hits the headlines you can be sure that someone – maybe lots of people – will question whether it's worth it.
- And so it is with the restart of this mother of all physics experiments, ready after its two-year upgrade to explore uncharted corners of the sub-atomic realm.
- This vast machine ranks as one of the world's biggest experiments, with incredibly sophisticated machinery filling a 27km circular tunnel, and the bill so far has come to a little under £4 billion.
- Back in 2008, when the vast device was first brought to life, one senior British scientist grumbled to me that “the particle physicists seem to get all the money they want”.
Sound and fury?
His view was that humanity faces a long list of severe and immediate threats which are more deserving of the kind of massive scientific investment devoted to the research at Cern.
Top of his list was clean energy. If we could start with a blank sheet of paper, he said, would we really choose to devote all those billions to particle physics?
- I heard a similar complaint on the day that the Rosetta spacecraft achieved its historic rendezvous with a comet far beyond Mars.
- As the mission controllers erupted around me, one of my tweets attracted a sternly-worded demand to know how anyone would benefit from this venture to a distant and icy rock.
- “What good,” I was asked, “might any knowledge that it might obtain do for mankind?”
Image caption Why do we need a 27km tunnel for smashing particles together at almost the speed of light?
- One answer might be pragmatic: if a comet ever headed our way, it would be good to know what they are made of and how they might be deflected.
- Another could be that it would surely satisfy our curiosity to know if comets were the source of our water or even of life itself.
- But a response that feels more compelling is that previous generations have only been able to gaze at comets in awe or fear while ours might be the first to understand them.
- The same kind of argument applies to the Large Hadron Collider.
- When it discovered the famous Higgs boson, and confirmed its position in the Standard Model of physics, that was an extraordinary achievement in its own right.
- It proved the existence of an invisible process that performs the fundamentally important role of giving all other particles their mass or substance.
Big stuff, but did it change anything practical in our everyday lives? Of course not.
But it is a huge step on a journey towards understanding how the universe works, and there is much more to come.
Image copyright Jonathan Webb – BBC Image caption The massive engineering challenge posed by the collider has already produced spin-offs
- The next collisions of protons may reveal something about the majority of matter that exists but has yet to be seen – the stuff known as dark matter.
- They may uncover evidence for the weird notion that there are extra dimensions, or hordes of previously unseen particles that form pairs with the ones we know about.
- Any of this would open our eyes to a new way of perceiving the fabric of everything we see and touch – how it is made and what holds it together.
- Astounding though these discoveries may be, they would not by themselves alter anything tangible about how we get up the next day, to face our lives and our work.
But that is how science functions. A new insight can open a door and it's then up to other researchers to choose whether to venture through it, sometimes decades later, to develop practical applications.
For example, the fact that we live in an age of electronics did not come down to a single discovery overnight.
Its roots can be traced to the brilliant theorisers and experimenters who did fundamental work back in the 19th century – Michael Faraday, James Clerk Maxwell and J.J. Thomson to name but a few.
Image copyright CERN / SPL Image caption The cost of the LHC so far comes to just under £4bn
- So who knows if the Higgs boson or dark matter particles or extra dimensions may eventually lead to some similarly huge leap in the next 50-100 years?
- The Cern case is that we will never know unless the basic job of exploration is done now.
- Back in the 1960s, when Nasa was under pressure to justify the cost of the Apollo moon landings, it resorted to highlighting spin-offs.
- The lunar missions, it argued, had given technology a unique boost and produced such wonders as miniaturised electronics and the non-stick frying-pan.
- And that kind of spin-off is another key part of Cern's case.
- It can claim credit for inventing a system for sharing data around the globe: the World Wide Web.
- Born of fundamental research which at the time might have felt irrelevant, it enables you to read this article now.
Return of the LHC – season 2 continues
The LHC has introduced beam for the first time since the year-end technical stop began in December 2015
Applause in the LHC control room as the first particles began circulating in the LHC (image: Maximillien Brice/CERN)
On Friday 25 March, the Large Hadron Collider (LHC) opened its doors to allow particles to travel around the ring for the first time since the year-end technical stop (YETS) began in December 2015. At 10.30 am, a first bunch was circulating and by midday the beam was circulating in both directions.
2015 saw the start of Run 2 for the LHC, the largest accelerator in the world where the LHC reached a proton-proton collision energy of 13 TeV — the highest ever reached by a particle accelerator.
Beam intensity also increased and, by the end of 2015, 2240 protons bunches per beam were being collided. This year, the aim is to increase the number of bunches even further to the target of 2748.
Beams are made of “trains” of proton bunches moving at almost the speed of light around the 27 kilometre ring of the LHC. By sending more bunches around the ring the LHC will be able to generate more collisions, meaning more physics data for the experiments.
Powering tests finished on 18 March 2016, and in the following week the LHC has been undergoing the final phase of preparation before beam.
This phase is known as machine checkout, during which all the systems of the LHC, such as the magnetic circuits and collimators, are put through their paces without beam. This includes ramping all hardware up to their high-energy values and testing the “squeeze” process.
By adjusting magnet strengths either side of a given experiment, the squeeze reduces the beam size at the interaction point thereby increasing the collision rate.
“Following the machine checkout, the LHC team works with low intensity beam for about 3 to 4 weeks to re-commission all systems and to check out all aspects of beam-based operation to make sure that the LHC is fully safe before stable beams is declared,” Mike Lamont of the Operations team explains. Stable beams are the signal that the experiments can start taking data.
In 2016 the LHC will continue to open the path for new discoveries by providing up to 1 billion collisions per second to its experiments as it continues Run 2. The goal this year is to reach an integrated luminosity of around 25 fb-1, up from the 4 fb-1 it reached by the end of last year.
Luminosity is an essential indicator of the performance of an accelerator, measuring the potential number of collisions that can occur in a given amount of time. Integrated luminosity is the accumulated number of potential collisions.
The inverse femtobarn (fb-1) is the unit used by physicists to measure the integrated luminosity; 1 fb-1 corresponds to around 80 million million collisions.
More information on the first beams seen by the ATLAS and CMS experiments available on their websites.
A time-lapse video of some of the important milestones preceding proton beam injection this year and the activities over the last few days in the CERN Control Centre (CCC), the place where the CERN accelerator chain is operated and controlled. (Video: CERN)
Rice insight gives Large Hadron Collider better eyesight
Mike Williams – April 1, 2020Posted in: News Releases
National Science Foundation backs physicists, engineers as they upgrade sensors for deeper discoveries
HOUSTON – (April 1, 2020) – Rice University will receive $3 million for its direct work on the next round of upgrades to the Large Hadron Collider (LHC), but it will be responsible for much more.
Rice physicist Karl Ecklund will oversee roughly half of the $77 million in National Science Foundation funding to U.S. institutions that will help make the particle accelerator, which is best known for finding the Higgs boson, better able to discover even deeper truths about elemental matter.
Rice University physicists and engineers have received National Science Foundation support to design, build and manage the installation of next-generation sensors in the Compact Muon Solenoid at the Large Hadron Collider. Courtesy of CERN
Ecklund and his Rice colleagues have long been involved in the Compact Muon Solenoid (CMS), one of two major experiments attached to the LHC, a 17-mile ring buried beneath land that borders France and Switzerland.
CMS detects the speed and paths of particles that spew from colliding protons and survive for fractions of a second. The detectors record and transmit the data that scientists later parse for evidence of unique or unknown particles that could provide new knowledge about the universe.
CMS is only compact compared to the collider itself; the sensor-laden array of concentric tubes weighs 13,000 tons and disassembling it for upgrades is an arduous task. That’s why the LHC periodically shuts down for a few years at a time.
The PPRC hails the return of circulating beams in the Large Hadron Collider
Members of the QMUL Particle Physics Research Centre (PPRC) involved in the ATLAS experiment and the GridPP computing network are ready for the new operational phase of the LHC, as CERN announces the first successful circulation of proton beams after a two years maintenance stop.
On Easter day, April 5th 2015, the Beams Division at CERN has successfully circulated protons around the Large Hadron Collider (LHC) 27-kilometer underground ring, for the first time since the end of 2012 reaching a crucial milestone in the re-commissioning of the machine ahead of its Run 2 phase. The LHC Run 2, due to start in mid 2015, foresees proton-proton collisions with a total energy of 13 and 14 TeV, nearly twice that of the previous phase that led to the discovery of the Higgs boson. Members of the PPRC participate in the ATLAS experiment and in the past two years have been working to improve the tracking and triggering capabilities of the detector, owing to their involvement in the construction, operation and upgrades of the ATLAS Semiconductor Tracker and the calorimeter first-level Trigger electronics.
The QMUL personnel are also involved with GridPP, the UK part of the Worldwide LHC Computing Grid which is spread over 174 facilities in 40 countries and which processes about 10 gigabytes of data every second. The PPRC hosts one of the largest GridPP computing clusters, part of the London Tier-2 with approximately 420 machines with 3600 CPU cores and 1.7 PB of disk space.
With today's announcement, the ATLAS group at QMUL is looking forward to the upcoming high-luminosity proton-proton collisions of the LHC Run 2 later in the year.
The PPRC staff are preparing to study in minute details the emerging of top-quarks, W/Z bosons with associated heavy and light-flavour jets, B mesons and Higgs bosons, in the hope of discovering new particles, such as candidate particles of Dark Matter, or the indication of new fundamental forces or even a new space-time structure.
The present low-intensity commissioning of the full operational cycle of the LHC is expected to last about 2 months. Run 2 itself is expected to last three years.
Beams in the Large Hadron Collider came to a stop today, closing out four years of record-breaking operation for the ATLAS experiment. Run 2 saw the extraordinary exploration of the high-energy frontier, as the ATLAS experiment brought new understanding of particle physics.
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Geneva, 23 May 2017. A new season of record-breaking kicked off today, as the ATLAS experiment began recording first data for physics of 2017. This will be the LHC’s third year colliding beams at an energy of 13 tera electron volts (TeV), allowing the ATLAS Experiment to continue to push the limits of physics.
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With the year’s first proton beams now circulating in the Large Hadron Collider, physicists have today recorded “beam splashes” in the ATLAS experiment
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Friday morning, 29 April 2016: what was expected to be a productive shift turned out to be very different.
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This morning the Large Hadron Collider (LHC) circulated the first proton-proton beams of 2016 around its 27 kilometre circumference. The beams were met with great enthusiasm in the ATLAS Control Centre as they passed through the ATLAS experiment.
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Faster and Faster! This is how it gets as soon as LS1 ends and the first collisions of LHC Run 2 approaches. As you might have noticed, at particle physics experiments we LOVE acronyms! LS1 stands for the first Long Shutdown of the Large Hadron Collider.
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As final preparations were made for the start of the Large Hadron Collider's (LHC) Run 2, the ATLAS Control Room was the centre of activity. Here are images from the three days that were landmark events…
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After a shutdown of more than two years, Run 2 of the Large Hadron Collider (LHC) is restarting at a centre-of-mass energy of 13 TeV for proton–proton collisions and increased luminosity. This new phase will allow the LHC experiments to explore nature and probe the physical laws governing it at scales never reached before.
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Today ATLAS and other particle physics experiments at CERN's Large Hadron Collider (LHC) began recording physics data from 13 TeV proton collisions, which allow for precision studies of the Higgs boson and other Standard Model particles, as well as the search for new particles with higher masses. The new data will bring a deeper understanding of nature.
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Goodbye, for a while, to the Large Hadron Collider
The lord of the particle accelerator, CERN’s Large Hadron Collider (LHC), went out of particle collision business for almost two years as of late last week. For particle physicists, Valentine’s Day 2013 will be remembered for the successful completion of phase 1 of the LHC’s operations.
But the two-year shutdown won’t involve much relaxing for the tens of thousands of scientists, engineers and technicians involved in one of world’s largest scientific projects. During this period – known as the Long Shutdown 1 (LS1) – the LHC will undergo a significant upgrade and consolidation.
CERN’s LHC live update page shows the end of the physics run as of February 14. CERN
It will be an exciting and intense period. One part of the CERN team will be preparing the LHC to be operational again after its planned upgrade by 2015, while others will be finalising their results on the vast amount of data that has been accumulated in the last three years.
Under the hood
The collider is housed in a 27km ring-shaped tunnel that is approximately 100m underground between the Swiss-French border at the CERN laboratory. It contains a large assembly of different kinds of superconducting magnets, including dipoles, quadrupoles and sextupoles.
These special types of magnets can conduct larger electric currents than ordinary wire and are required to create intense magnetic fields – 8.4 Tesla at the LHC is more than 100,000 times more powerful than Earth’s magnetic field – to focus and accelerate the particles to high energies.
CERN’s Accelerator Complex. CERN
The magnetic fields are connected electronically to a carrying current between different magnets. During the course of the overhaul of the LHC, more than 10,000 of these high current splices will be consolidated.
In the coming days and weeks, the engineers and scientific teams at the LHC will open up 1,695 interconnections of the main magnets’ cryostats (the devices used to maintain the LHC temperature at -271.3°C degrees Celsius – colder than the temperature of outer space, at -270.5°C).
The LHC’s tunnel ventilation system will also be replaced. It is worth noting that, before entering into the LHC, protons (or lead ions) undergo several acceleration steps with the combination of linear and other small circular accelerators.
CERN’s Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS) are small accelerators compared to the LHC, and use the technique of accelerating the particles through time-dependant magnetic fields.
During the LS1, renovation work for the accelerator magnetic chains in both of these accelerators has also been planned.
The LHC consolidation work planned during the two year shutdown. CERN
In addition to above, other facilities at the LHC such as the ventilation system at the PS tunnel (629m in circumference) will also be replaced. At the SPS, the instrumentation and control systems cables (approximately 100km in length) will be either removed or replaced.
The particles in the LHC are made to collide at the four different locations and at each of the locations the outcome of the collisions is recorded by the detectors (essentially the giant cameras are taking pictures millions of times a second).
Four locations constitute four different experiments at the LHC, with the strength of the scientific teams ranging from 500 to 3,500 for different experiments.
Two experiments – namely ATLAS and CMS – are general-purpose discovery experiments. The other two – ALICE and LHCb – are for more specific physics studies. These experiments will also undergo maintenance and upgrade to meet the machine’s new environment in 2015.
Australia is part of the ATLAS Collaboration (with around 3,500 scientists from 178 institutes, it’s one of the largest collaborations among all LHC experiments) and play a leading role in the experiment. Australian physicists are very busy in preparing the results with the LHC data in addition to making a core contribution in the planned ATLAS upgrade work during the LS1.
Until December last year, the LHC operated at the energy 8 Trillion electron Volt (TeV). In 2015, when the LHC springs back to life, it will operate at the energy 13 TeV at the start, approximately by a factor of 1.6 higher compared to last proton-proton collisions and then will ramp up to 14 TeV to reach the physics goals.
Major physics breakthroughs
The LHC is a discovery machine and has been designed to shed light on the unanswered questions in science. It is now best known for the discovery of a particle last July, the properties of which are quite similar to a long-sought Higgs boson particle.
With about a 2.5-times-larger data-set compared to last year, researchers are currently trying to pin down the property of this particle.
The shutdown and consolidation of the LHC explained.
In addition to this, a tremendous amount of effort is being made to study every possible physics theory emerging from the LHC data.
Next-generation LHC: CERN lays out plans for €21-billion supercollider
Artistic impression of the Future Circular Collider.Credit: CERN
CERN has unveiled its bold dream of building a new accelerator nearly 4 times as long as its 27-kilometre Large Hadron Collider (LHC) — currently the world’s largest collider — and up to 6 times more powerful.
CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, outlined the plan in a technical report released on 15 January.
The document offers several preliminary designs for a Future Circular Collider (FCC) — which would be the most powerful particle smasher ever built — with different types of collider ranging in cost from around €9 billion (US$10.
2 billion) to €21 billion.
It is the lab’s opening bid in a priority-setting process called the European Strategy for Particle Physics Update, which will take place over the next two years and will affect the field’s future well into the second half of the century.
The Large Hadron Collider Returns in the Hunt for New Physics
In 2012, researchers at the world's largest particle accelerator announced they had discovered a particle that resembled a key missing piece in our fundamental understanding of physics: the Higgs boson.
It was a Nobel Prize-worthy moment. But what comes next could be even more exciting.
The Large Hadron Collider is back for its second run at almost twice the energy it had then. This time, it's hoped it could shed light on physics beyond the Standard Model, the decades-old theory that describes the fundamental particles and forces that make up our universe.
“By moving up in energy, we open this window on producing these heavier, more exciting particles that we've never seen before,” Chris Young, who works on the ATLAS experiment, explained when we visited the site.
At 27km in circumference, the LHC spans the border of France and Switzerland near Geneva. After two years of maintenance, it was recently rebooted with proton beams primed to collide at an energy of 13 TeV (teraelectronvolts). The last run, when the Higgs was discovered, got to a maximum of 8 TeV.
The increased energy means there's scope to find particles we haven't seen before, and some physicists have their eyes open for evidence of one particular extension to the Standard Model: supersymmetry.
Known fondly by proponents as SUSY, this set of theories suggests that every Standard Model particle has a supersymmetric partner; each particle is partnered with a “sparticle.”
Supersymmetry is a compelling idea. It could conveniently fill in some of the remaining gaps in the Standard Model, such as the mass of the Higgs boson. “Supersymmetry would be one way of avoiding the future collapse of the universe,” theoretical physicist John Ellis, a major proponent of SUSY, told us.
- And it could delve further into the mysteries of our universe: One of the theorised supersymmetric particles, the neutralino, is a candidate for dark matter.
- But as attractive as it all sounds, there's a caveat: We haven't yet found any supersymmetric particles.
- With the LHC's new, higher energies, it's the best chance yet to detect something supersymmetric and add experimental backing to a theory that some theoretical physicists have dedicated their life's work to.
Just as the LHC was booting up for its new run, we visited CERN to check up on one of the largest experimental science facilities ever built. We spoke to the people running this huge machine and gathering data from the unprecedented particle collisions, as well as the theoretical physicists waiting for experimental data to settle their rivalries once and for all.
“This year is the hundred-year anniversary of Einstein's theory of general relativity, which revolutionised our ideas about space and time and gravity,” Ellis said. “I think the discovery of supersymmetry would be as big as that—something beyond what Einstein could ever dream of.”
The Quantum Frontier
“What Lincoln does brilliantly is dispel the popular myth that the LHC was built solely to discover the Higgs boson, or 'God particle'. This is a project with a far wider reach… His fresh analogies and insights make this book very readable.”
(Valerie Jamieson New Scientist)
“The book is written in a very readable and entertaining style, and I can warmly recommend it to anyone with more than a passing interest in science.”
(John L. Hutchison infocus)
“A Fermilab scientist conveys the excitement surrounding the LHC.”
“This small book conveys the excitement and the importance of science's biggest ever experiment.”
“I deeply enjoyed Lincolnâ€™s very accessible discussions of antimatter and Cerenkov radiation. And the in-depth explanations of what the different calorimeters and solenoids do inside the LHCâ€™s vast underground accelerator are fascinating.”
(Sally Adee IEEE Spectrum Magazine)
“It is to the authorâ€™s credit that he succeeds in explaining all the major ideas at a level that should be comprehensible to a very wide readership, using little or no mathematicallanguage…
The style of writing is extremely pleasant, and any reader who has an interest in particle physics, including those without any previous knowledge of the subject, should find this material accessible and interesting.”
“Don Lincoln's book should be in the hands of everyone interested in physicsâ€•even if only vaguely. It conveys the excitement particle physicists feelâ€•and everyone else should feelâ€•about the start of the Large Hadron Collider.”
(Gabor Domokos, The Johns Hopkins University)
“The Quantum Frontier… prepares readers with what they can anticipate when the LHC becomes operational.”
(John S. Rigden and Roger H. Stuewer Physics in Perspective)
“Should be in every physics library: it offers an exciting assessment of the Large Haldron Collider, which runs between France and Switzerland, and surveys just why its opening is so significant. You needn't be a physicist to appreciate its importance, and the clear explorations in layman's terms imparts excitement. Perfect for any general lending library strong in science.”
(Midwest Book Review)
“Don Lincoln's playful, energetic style took me from the fundamentals of contemporary physics through to the extremely complex and sophisticated guts of the LHC experiments, touching on everything from the Earth's 'inevitable' destruction by black holes to speculated future physics experiements in a post-LHC era. Cracking it open for the first time, I was worried that a book taking under 200 pages to cover such an ambitious topic would be riddled with sterile facts listed on after the other. But the contrary is what I found.”
(Jordan Juras CERN Courier)
Don Lincoln is a scientist with the Fermi National Accelerator Laboratory. He is the author of Understanding the Universe: From Quarks to the Cosmos.