Category Archives: LHC Exhibition

The Art of Boiling Beer: 60 years of the Bubble Chamber

Ahead of November’s opening of the Collider exhibition, Content Developer Rupert Cole explains how beer was used for cutting-edge particle physics research. 

Late one night in 1953, Donald Glaser smuggled a case of beer into his University lab. He wanted to test out the limitations of his revolutionary invention: the bubble chamber.

Previously, Glaser had only tried exotic chemical liquids in his device. But now his sense of experimental adventure had been galvanised by a recent victory over the great and famously infallible physicist Enrico Fermi.

Donald Glaser and his bubble chamber, 1953. Credit: Science Museum / Science and Society Picture Library

Donald Glaser and his bubble chamber, 1953. Credit: Science Museum / Science and Society Picture Library

Fermi, who had invited Glaser to Chicago to find out more about his invention, had already seemingly proved that a bubble chamber could not work. But when Glaser found a mistake in Fermi’s authoritative textbook, he dedicated himself to redoing the calculations.

Glaser found that, if he was correct, that the bubble chamber should work with water. To make absolutely certain he “wasn’t being stupid”, Glaser conducted this curious nocturnal experiment at his Michigan laboratory. He also discovered that the bubble chamber worked just as well when using lager as it had with other chemicals.

There was one practical issue however, the beer caused the whole physics department to smell like a brewery. “And this was a problem for two reasons,” Glaser recalled. “One is that it was illegal to have any alcoholic beverage within 500 yards of the university. The other problem was that the chairman was a very devout teetotaler, and he was furious. He almost fired me on the spot”.

On 1st August 1953, 60 years ago this Thursday, Glaser published his famous paper on the bubble chamber – strangely failing to mention the beer experiment.

Glaser’s device provided a very effective way to detect and visualise particles. It consisted of a tank of pressurised liquid, which was then superheated by reducing the pressure. Charged particles passing through the tank stripped electrons from atoms in the liquid and caused the liquid to boil. Bubbles created from the boiling liquid revealed the particle’s path through the liquid.

Particle tracks produced by Gargamelle indicating the discovery of the neutral currents, 1973. Credit: CERN

Particle tracks produced by Gargamelle indicating the discovery of the neutral currents, 1973. Credit: CERN

One of Glaser’s motivations for his invention was to avoid having to work with large groups of scientists at big particle accelerators. Instead, he hoped his device would enable him to study cosmic rays using cloud chambers in the traditional fashion; up a mountain, ski in the day, “and work in sort of splendid, beautiful surroundings. A very pleasant way of life – intellectual, aesthetic, and athletic”

Ironically, as the bubble chamber only worked with controlled sources of particles, it was inherently suited to accelerator research, not cosmic rays. Soon the large accelerator facilities built their own, massive bubble chambers.

Design drawings for CERN’s Gargamelle bubble chamber. Credit: CERN

Design drawings for CERN’s Gargamelle bubble chamber. Credit: CERN

Between 1965-1970 CERN built Gargamelle – a bubble chamber of such proportions that it was named after a giantess from the novels of Francois Rabelais (not the Smurfs’ villain). Gargamelle proved a huge success, enabling the discovery of neutral currents – a crucial step in understanding how some of the basic forces of nature were once unified.

This November you’ll have the chance to see up close the original design drawings for Gargamelle, and much more in the Collider exhibition.

Standard Model Stands Firm

Dr. Harry Cliff, a Physicist working on the LHCb experiment and the first Science Museum Fellow of Modern Science, writes about a recent discovery at CERN. A new Collider exhibition opens in November 2013, taking a behind-the-scenes look at the famous particle physics laboratory. 

On Friday afternoon, at the EPS conference in Stockholm, two colleagues of mine from CERN stood up to announce that the search for one of the rarest processes in fundamental physics is over. The result is a stunning success for the Standard Model, our current best theory of particles and forces, and yet another blow for those hoping for signs of new physics from CERN’s Large Hadron Collider (LHC).

The Compact Muon Spectrometer, an experiment at CERN. Image credit: CERN.

The Compact Muon Spectrometer, an experiment at CERN. Image credit: CERN.

The LHCb and CMS experiments at the LHC have made the first definitive observation of a particle called a Bs meson decaying into two muons, confirming a tentative sighting at LHCb (my experiment) last autumn. The discovery has far-reaching implications for the search for new particles and forces of nature.

Beyond the Standard Model

There are a lot of reasons to suspect that the current Standard Model isn’t the end of the story when it comes to the building blocks of our Universe. Despite agreeing with almost every experimental measurement to date, it has several gaping holes. It completely leaves out the force of gravity and has no explanation for the enigmatic dark matter and dark energy that are thought to make up 95% of the Universe. The theory also requires a large amount of “fine-tuning” to match experimental observations, leaving it looking suspiciously like the laws of physics have been tinkered with in a very unnatural way to produce the Universe we live in.

In the last few decades a number of theories have been put forward that attempt to solve some of the Standard Model’s problems. One particularly popular idea is supersymmetry (SUSY for short), which proposes a slew of new fundamental particles, each one a mirror image of the particles of the Standard Model.

The Large Hadron Collider beauty (LHCb) experiment at CERN. Image credit: CERN.

The Large Hadron Collider beauty (LHCb) experiment at CERN. Image credit: CERN.

SUSY has many attractive features: it provides a neat explanation for dark matter and unifies the strengths of the three forces of the Standard Model (this suggests that they could all be aspects of one unified force, which should definitely be referred to as The Force, if it turns out to exist someday). It would also keep my colleagues in work for decades to come, thanks to a whole new load of super-particles (or sparticles) to discover and study.

However, physicists were first attracted to it because the theory is aesthetically pleasing. Unlike the Standard Model, SUSY doesn’t require any awkward fine-tuning to produce laws of physics that match our experience. This is not a very scientific argument, more a desire amongst physicists for theories to be elegant, but historically it has often been the case that the most beautiful theory turns out to be right one.

On the hunt

The decay observed at LHCb and CMS is predicted to be extremely rare in the Standard Model, with a Bs meson only decaying into two muons about 3 times in every billion. However, if ideas like SUSY are correct than the chances of the decay can be significantly boosted.

Finding particle decays this rare makes hunting for a needle in a haystack seem like a doddle. Hundreds of millions of collisions take place every second at the LHC, each one producing hundreds of new particles that leave electrical signals in the giant detectors. Physicists from LHCb and CMS trawled through two years worth of data, searching untold trillions of collisions for signs of two muons coming from a Bs meson. The pressure to be the first to find evidence of this rare process was intense, as Dr. Marc-Olivier Bettler, a colleague of mine from Cambridge and member of the LHCb team told me.

“It is a very strange type of race. To avoid bias, we don’t allow ourselves to look at the data until the last minute. So it’s a bit like running blindfolded – you can’t see the landscape around you or your competitors, even though you know that they’re there, so you have no idea if you are doing well or not! You only find out after you cross the finish line.”

However, ultimately the race ended in a draw. Neither LHCb nor CMS alone had enough data to announce a formal discovery, each turning up just a handful of likely candidates. But when their results are formally combined next week it is expected that the number of observed decays will pass the all-important “five sigma” level, above which a discovery can be declared.

Standard Model Stands Firm

In a blow for supporters of SUSY, LHCb and CMS observed the decay occurring at exactly the rate predicted by the Standard Model – approximately 3 times in a billion. This is yet another triumph for the Standard Model and kills off a number of the most popular SUSY theories.

Professor Val Gibson, leader of the Cambridge particle physics group and member of the LHCb experiment explained that, Measurements of this very rare decay significantly squeeze the places new physics can hide. We are now looking forward to the LHC returning at even higher energy and to an upgrade of the experiment so that we can investigate why new physics is so shy.”

This result is certainly not the end of the road for ideas like supersymmetry, which has many different versions. However, combined with the recent discovery of the Higgs boson (whose mass is larger than predicted by many SUSY theories) this new result may only leave us with versions of SUSY that are somewhat inelegant, meaning that the original motivation – a natural description of nature – is lost.

This new result from CERN is yet another demonstration of the fantastic (and somewhat annoying) accuracy of the Standard Model. Incredible precision is now being achieved by experiments at the LHC, allowing physicists to uncover ever-rarer particles and phenomena. If ideas like supersymmetry are to survive the onslaught of high precision tests made by the LHC experiments, we may have to accept that we live in a spookily fine-tuned Universe.

CERN: 60 years of not destroying the world

Ahead of November’s opening of the Collider exhibition, Content Developer Rupert Cole celebrates six decades of research at CERN, the European Organization for Nuclear Research. 

Just before the Large Hadron Collider first turned on in September 2008, there was (in some quarters) a panic that it would destroy the world.

Doomsday was all over the media. “Are we all going to die next Wednesday?” asked one headline. Even when CERN submitted a peer-reviewed safety report in an attempt to allay fears, it didn’t altogether quash the dark mutterings and comic hysteria: “Collider will not turn world to goo, promise scientists.” 

This cartoon is pinned on the wall of the theory common room at CERN. Image credit: Mike Moreau

This cartoon is pinned on the wall of the theory common room at CERN. Image credit: Mike Moreu

In case you were wondering, the LHC has subsequently proved to be completely safe, and has even found the Higgs Boson to boot.

In fact, this isn’t the first time CERN has provoked fears of world destruction. In the lead-up to the signing of CERN’s founding Convention – 60 years ago this month – the proposed organisation was greatly hindered and influenced by apocalypse anxiety.

Only, back then, it had nothing to do with micro black holes swallowing the earth or strangelet particles messing with matter. No such exotic phenomena were needed. Just the mention of the words nuclear and atomic was enough to provoke serious paranoia in the Cold-War climate.

In 1949 Denis de Rougement, a Swiss writer and influential advocate for a federal Europe, attended the European Cultural Conference — one of the early conferences in which a “European Centre for Atomic Research” was discussed. “To speak of atomic research at that time,” de Rougement reflected, “was immediately to evoke, if not the possibility of blowing up the whole world, then at least preparations for a third world war.”

The press undoubtedly subscribed to the more extreme school of thought. On the second day of the conference, all the scientists present had to be locked in a chamber for protection as they had been pestered so severely by journalists on the previous day.

In some of the initial discussions, a nuclear reactor as well as an accelerator was proposed for the European research centre. It was carefully stressed that no commercial applications would be developed and all military work scrupulously excluded.

The French, who led these early proposals, removed the director of the French Atomic Energy Commission, the communist-leaning Frederic Joliot-Curie, after J. Robert Oppenheimer (of Manhattan Project fame) stated the Americans wouldn’t support a project that included a senior figure with Soviet sympathies.

Left to right: J. Robert Oppenheimer, Isidor I. Rabi, Morton C. Mott-Smith, and Wolfgang Pauli in a boat on Lake Zurich in August 1927. Image credit: CERN

Left to right: J. Robert Oppenheimer, Isidor I. Rabi, Morton C. Mott-Smith, and Wolfgang Pauli in a boat on Lake Zurich in August 1927. Image credit: CERN

The nuclear reactor was dropped when Hungarian-American physicist Isidor I. Rabi, the so-called “father” of CERN,  stepped on the scene. Rabi, who co-founded the American research centre Brookhaven National Laboratory, put a resolution to the annual conference of UNESCO in Florence, June 1950 for a (“western”) European physics laboratory.

The fact Rabi omitted to mention a nuclear reactor was likely a political move on the part of the US, who were not keen on Soviet bits of Europe developing nuclear weapons. After much to-ing and fro-ing in the next two years, a provisional agreement was signed on 14 February 1952 by ten European states.

The next day, the signed agreement was telegrammed to Rabi, informing him of the “birth of the project you fathered in Florence”. The convention was signed on the 1st July, 1953 and CERN became an official organisation just over a year later.

Telegram sent to Isidor Rabi on 15 February, 1952 – marking the birth of CERN. Image credit: CERN.

Telegram sent to Isidor Rabi on 15 February, 1952 – marking the birth of CERN. Image credit: CERN.

For sixty years, CERN has been successfully exploring the unknown regions of the quantum world, while leaving the world we live in very much intact.

See a copy of the telegram and more in Collider: step inside the world’s greatest experiment, opening this November. Click here for further reading on the history of CERN

Happy birthday, Z boson

Alice Lighton, content developer for our Collider exhibition, writes about the history of quantum physics. Collider: step inside the world’s greatest experiment opens in November 2013 with a behind-the-scenes look at the famous CERN particle physics laboratory. 

The air brimmed with excitement on this momentous day. The discovery of the particle confirmed a theory that had taken years to devise, and justified the toil of hundreds of scientists.

You might think I’m referring to the Higgs boson – the particle that explains mass, discovered at the LHC last year. But thirty years ago this month, another event shaped modern physics – the discovery of the Z boson.

In the 1960s, physicists predicted the Z and W bosons, as a way to link the electromagnetic and weak forces. There was plenty of evidence the theory was correct, but the lynchpin would be the discovery of the Z boson.

A section of the 4.3 mile-round Super Proton Synchrotron, at CERN near Geneva. Image: CERN

To make a Z boson, two particles are smashed together. The energy of the crash creates new, heavy particles. If a Z boson is produced, it sticks around for only a fraction of a second before it decays into other particles. To claim the prize of discovering the Z boson, physicists would need to be able to forensically reconstruct what happens in a collision, never seeing the Z directly.

Europe and America built machines to discover the Z, including the Super Proton Synchrotron (SPS) at CERN. “The idea of creating this massive object (the Z) and letting it decay…was a riveting idea (well at least for me in the late 1970s),” said Crispin Williams, a physicist who now works on the ALICE experiment at the LHC.

Two CERN physicists, effusive Italian Carlo Rubbia and Dutchman Simon Van der Meer, realised that to beat the firepower of the newly-opened Tevatron in Chicago, the SPS had to take risks. The pair devised an audacious plan; rather than fire beams onto a fixed object, they would collide two opposing beams, each only a hair’s width across and both travelling at almost the speed of light.

What’s more, one of the beams would be made of antimatter, which destroys ordinary matter. Creating and manipulating a beam of antimatter was a revolutionary concept.

Williams remembers when Rubbia and Van der Meer announced their plan to collide two beams. “This was to a packed auditorium at CERN and I suspect that most people thought he was out of his mind,” said Williams.

Rubbia and Van der Meer celebrate receiving a Nobel prize for their efforts. Image: CERN

Despite the technical challenge, the new collider worked. One visitor to CERN in 1982 described the intense excitement the new development created. “I went to the CERN cafeteria for a coffee and there I saw something that I had not noticed before. There was a monitor on the wall and people were watching the screen with great interest. The monitor was showing the rate of proton–antiproton collisions in CERN’s latest challenge – a bold venture designed to produce the intermediate bosons, W and Z.”

In January 1983, the risk-takers received their reward, when the W boson was discovered.  On 1st June 1983, scientists at CERN announced they had seen five Z bosons in their detectors.

The tracks left by the decay of the Z boson in a detector. Image: UA1/CERN

The route to the discovery had revolutionised particle physics, with more intricate detectors and the ability to manipulate antimatter. For Williams, the discovery of the Higgs boson was much less elegant. “In comparison the Higgs at the LHC is just brute force,” he said.  “Maybe I am just getting old and cynical: and I look back at the Z discovery through rose tinted glasses.”

LHC. Camera. Action! (Part 2)

Dr. Harry Cliff, a Physicist working on the LHCb experiment and the first Science Museum Fellow of Modern Science, writes about his recent filming trip to CERN for Collider, a new Science Museum exhibition opening in November 2013. The first part can be read here

Day 2, Thursday

On the first day of the Collider exhibition team’s visit to CERN we had explored the architecture and interiors of the town-sized laboratory. Now it was time to enter its beating heart: the gigantic experiments probing the fundamental laws of the universe, and the people who make them a reality.

Our team now divided. Pippa, Finn and crew set off to the far side of the 27km LHC ring to Point 5, home of the enormous Compact Muon Solenoid (CMS) experiment. 100 metres underground, 25 metres long, 15 metres high, weighing in at 12,500 tonnes and containing enough iron to build two Eiffel Towers, CMS is one of the four huge detectors that record the particle collisions produced by the Large Hadron Collider. It is also a remarkable sight, beautiful even, its concentric layers giving it the appearance of a gigantic cybernetic eye. One member of the team said it was the most incredible thing he had ever seen, with only the Pantheon in Rome coming close to matching it.

The enormous Compact Muon Solenoid (CMS) experiment. Credit: CERN.

The enormous Compact Muon Solenoid (CMS) experiment. Credit: CERN.

CMS was photographed from every angle so that it can be recreated in a 360 immersive projection for the Collider exhibition. The CMS team were incredibly accommodating in allowing us to get our cameras as close to CMS as possible, all while they carried out vital work on the detector. We owe particular thanks to the boundlessly energetic Michael Hoch who looked after us for the day and made it all possible.

Meanwhile, 13km around the ring, in a less spectacular CERN office, our radio producer and I carried out audio interviews of LHC physicists and engineers. Each of them sharing what makes them tick as scientists and inventors. One even surprised us by dismissing the discovery of the Higgs boson as “boring”; what drives him as a scientist is seeking answers to new questions. For him the Higgs threatens to be a dead-end on the journey of discovery, rather than opening up new avenues of inquiry. Over the course of the day we interviewed five members of CERN’s international community, drawn from across Europe, representing a diverse cross section of CERN’s most important asset, its people.

Day 3, Friday

The last day might have been the most challenging. The team assembled at CERN’s custom-built TV studio to film interviews with LHC engineers against a green screen. These are the people who build and operate CERN’s experiments and they will appear as full-body projections in the exhibition, as if museum visitors have wandered into the LHC tunnel to be met by a friendly member of staff. Over dinner the night before we had shared anxieties as to how it might go. Video, unlike audio, can’t be edited to remove fumbled words or long pauses – our interviewees would have to deliver near-perfect speeches, and none of them had ever done anything like this before. In fact, neither had any of us.

Our concerns were unfounded. The engineers were naturals and by the end of the day we had recorded some brilliant interviews that should really help bring CERN to life for the visitors to the exhibition.

We returned to London that evening, exhausted but carrying a huge amount of material, covering almost every aspect of the Large Hadron Collider. For the first time I really have a sense of what this Collider exhibition will become; it’s going to be quite something to see it take shape over the next five months. If you can’t make it to Geneva to see the LHC in person, you’ll find a healthy slice of the world’s greatest experiment at South Kensington this November. 

LHC. Camera. Action! (part 1)

Dr. Harry Cliff, a Physicist working on the LHCb experiment and the first Science Museum Fellow of Modern Science, writes about his work on Collider, a new Science Museum exhibition opening in November 2013.

In the past year, I’ve become a regular passenger on the evening flight from Gatwick to Geneva, home of CERN and the mighty Large Hadron Collider.  I think I could recite Easyjet’s pre-recorded safety announcement pretty much word-for-word if pushed. But this was a rather special trip, as I was visiting CERN perhaps for the last time on museum business.

I was accompanied by a team with a dazzling array of skills. Creative mastermind Pippa Nissen had marshalled exhibition designersgraphic designers, a sound artist, an animator, a camera technician and a radio producer. Not to mention our video designer, Finn Ross, fresh from his win at the Olivier Awards, and the inevitable after-party hangover. And me, a quantum superposition of particle physicist, curator and travel rep.

Our mission was to capture the essence of CERN so that it can be (almost literally) recreated in the Science Museum’s upcoming exhibition, Collider. All this material was to be gathered in just three days, using only cameras, microphones and the minds of our design team.

Day 1, Wednesday

One does not simply walk into CERN. Its gates are guarded by unfailingly helpful, though rather formidable, security personnel and to gain access you must produce a CERN ID card or a visitor pass.

CERN security gate.

CERN security gate. Image credit: Science Museum

We had rather brilliantly chosen the 1st of May as our day to arrive, a national holiday in Switzerland, meaning the reception where we would normally collect our passes was closed. I had arranged for them to be left with the security guard at the main gate, but conveying this to him proved a challenge in my halting GCSE French. Finally, with a bit of gesticulating and some help from our more linguistically capable graphic designer, we located the passes and stepped across the threshold into the world’s largest physics laboratory.

CERN is the size of a medium-sized town, spread across several sites, the largest of which straddles the border between the Swiss suburb of Meyrin and the French village of St-Genis-Pouilly. The lab grew up organically from its beginnings in the 1950s and is a peculiar hodgepodge of office buildings, warehouses and laboratories. CERN’s rather shabby above ground stands in stark contrast to the shining machines that inhabit its subterranean spaces. As far as is possible, the money goes underground, spent on CERN’s reason for being: exploring the unknown regions of the quantum world.

Our job on day one, however, was to explore CERN’s above ground world. The first few hours were spent photographing the exteriors of buildings to act as backdrops in the exhibition. There was a particular warehouse door, in varying shades of rust and faded blue, that really caught the team’s attention. It will take me a while to forget the image of the design team gathered around it while Finn took high-res shots with his £20k camera. That’s designers for you I suppose.

The long beige corridors of CERN's Building 2. Image credit: Science Museum

The long beige corridors of CERN’s Building 2. Image credit: Science Museum

Then we ventured into the star of the show, the enigmatic Building 2, a 1970s block that houses a large number of institute offices. Along its long beige corridors you find offices of universities from all over the world, including the room where Tim Berners-Lee invented the World Wide Web and my own home-away-from-home, the Cambridge LHCb office. We spent a happy afternoon photographing the office doors, each with their own personal details that do more than any museum text panel could in getting across just how international a place CERN is. We owe a particular debt of thanks to a PhD student from Bristol, in on a holiday to work on her thesis, who obligingly allowed us barge into her office to take photographs.

Meanwhile our sound designer was busily recording the soundscape of CERN from the clanging of doors and the echo of footsteps on lino to the hum of electrical equipment. Once we had recorded enough material to rebuild Building 2 in its entirety should any calamity befall it, we made a brisk trip around nearby parts of the lab, taking in the main auditorium where the discovery of the Higgs boson was announced to the world, and a series of labs and warehouses including the LEIR accelerator ring, the machine responsible producing beams of lead ions for our muse, the Large Hadron Collider.

But after all that, we had only scratched the surface of the sprawling laboratory. The next day it would be time to go underground…

A hundred years of the quantum atom

Alice Lighton, content developer for our Collider exhibition, writes about the history of quantum physics. Colider: step inside the world’s greatest experiment opens in November 2013 with a behind-the-scenes look at the famous CERN particle physics laboratory. 

A few years ago, a friend asked a question that took me somewhat by surprise. “Alice,” he said, “is quantum physics right, or is it just a theory?”

At the time I was in the midst of a physics degree, so my initial response was “I hope so!” Quantum physics matches up to experiment extraordinarily well – it is often called the most accurate theory ever. But the question, and subsequent conversation, made me realise how little many people know about the subject, despite its profound impact on modern life and the way we think about the universe.

This year is the centenary of the publication of one of the theories that laid the foundation for our understanding of matter in terms of quanta – packets of energy. According to quantum mechanics, light is not a wave, but lump of energy called photons. Max Planck came up with the idea at the end of the 19th Century, though he considered his light ‘quanta’ a useful model, rather than reality.

Niels Bohr

Niels Bohr, one of the founders of modern physics.

One hundred years ago, in 1913, the young Danish researcher Niels Bohr sent a paper to the Philosophical Magazine in London that used these quanta to solve a serious problem with theories about the atom. At the time, scientists thought the atom was like a solar systems; electrons orbit a nucleus of protons and neutrons. But anything that moves in a circle gradually slowly radiates energy, and so moves closer to the centre of orbit. Eventually, electrons should fall into the nucleus of the atom.

But they blatantly don’t, otherwise everything in the Universe would collapse, and we wouldn’t exist. Bohr proposed that electrons could only sit in discrete orbits or distances from the nucleus – and therefore when electrons change orbit transitions between orbits emit only emit energy in discrete packets (quanta), not gradually. The electrons therefore stay put in their orbits, and don’t fall into the nucleus of the atom.

A hydrogen atom is made from one electron orbiting a proton. Photo credit: flickr/Ludie Cochrane

Bohr was the first to show that packets of energy could successfully explain and predict the behaviour of atoms, the stuff that makes up you and me. His results were only approximately correct, but a big improvement of previous theories.

Generations of scientists have built on Bohr’s insight to understand and create the modern world. When my friend asked whether quantum physics worked, I pointed at his laptop. Computers, nanotechnology, and the Large Hadron Collider owe their existence to the physics that began with Bohr’s generation.

The CMS experiment at the Large Hadron Collider tries to work out the rules governing the sub-atomic world. Photo credit: CERN

Bohr’s original papers are clear and comprehensible, a beautiful read for physicists. The mathematics involves nothing more difficult than multiplication and division, yet the philosophical implications are immense. Max Planck never fully accepted quantum physics; neither did Albert Einstein, despite winning a Nobel Prize for his work on the subject.

Bohr also won a Nobel Prize for his quantum theory, but his work did not stop. He founded the Niels Bohr Institute, a centre of theoretical physics in Copenhagen, worked on the Manhattan Project developing the atomic bomb, and continued to make contributions to quantum mechanics.

And he has a lovely link to the exhibition I’m currently working on, about the Large Hadron Collider. Bohr was influential in the founding of CERN, the Geneva laboratory that is home to the LHC. If he had his way, the LHC would be in Denmark, but other scientists objected – Northern Europe was too cloudy, and had too few ski resorts, for Italian tastes.

An artists impression of the immersive collision experience in the Collider exhibition. Image credit: Science Museum / Nissen Richards Studio

Science Museum visitors to step into the greatest experiment on Earth

By Roger Highfield, Director of External Affairs at the Science Museum Group

Plans are unveiled today for the biggest-ever exhibition in the UK to focus on the Large Hadron Collider (LHC), the world’s greatest scientific experiment, where a 10,000 strong international army of scientists and engineers is exploring the fundamental building blocks of the universe, from the discovery of the Higgs particle to the nature of antimatter.

The King’s College theoretician John Ellis has suggested that the LHC, the most compelling scientific endeavour so far of the 21st century, could inspire a generation in the same way that the Apollo adventure did in the 1960s. That is precisely why the Science Museum is bringing the LHC to the public in its new Collider exhibition, opening in November 2013. Visitors will be transported right into the heart of the 27 km circumference machine – that straddles the border between Switzerland and France – with the help of an award-winning creative team including Nissen Richards Studio, playwright Michael Wynne and video artist Finn Ross.

An artists impression of the immersive collision experience in the Collider exhibition. Image credit: Science Museum / Nissen Richards Studio

An artists impression of the immersive collision experience in the Collider exhibition. Image credit: Science Museum / Nissen Richards Studio

The immersive exhibition, the result of a unique collaboration with CERN, the European Organization for Nuclear Research, will blend theatre, video and sound art, taking visitors to the site of the LHC where they can explore the Control Room and a huge underground detector cavern, meet ‘virtual’ scientists and engineers and examine objects up-close. “I particularly like the fresh, theatrical approach the Museum is taking to bringing the drama and excitement of cutting-edge science to the public,” said CERN Director General, Rolf Heuer.

View of the LHC tunnel. Image credit: CERN

View of the LHC tunnel. Image credit: CERN

For the first time, visitors can get up close with exclusive access to part of the large 15-metre magnets that steer the particle beam, and elements from each of the LHC’s ‘eyes’, four giant detectors housed in caverns around the machine, notably CMS and ATLAS, where collisions take place. They will also be able to follow the story of sub-atomic exploration through the Museum’s collections – on display will be J.J. Thomson’s apparatus which led him to the discovery of the electron in 1897, and the accelerator used by John Cockcroft and Ernest Walton to split the atom in 1932.

JJ Thomson (1856-1940) at work. Image credit: Science Museum / Science & Society Picture Library

JJ Thomson (1856-1940) at work. Image credit: Science Museum / Science & Society Picture Library

When in operation, trillions of protons race around the LHC accelerator ring 11,245 times a second, travelling at 99.9999991% the speed of light. Evidence for a Higgs-like particle was found in the aftermath of the resulting collisions between protons.

Named after the British physicist Peter Higgs who postulated its existence more than half a century ago, and who will help launch the new exhibition with other leading figures, the particle is the final piece of the Standard Model, a framework of theory developed in the late 20th century that describes the interactions of all known subatomic particles and forces, with the exception of gravity.

The highlight of the exhibition, according to Alison Boyle, the Science Museum’s curator of modern physics, will be a 360-degree projection taking in both extremes of the scale of the LHC. ‘We are going to take our visitors from an enormous experiment cavern to the very heart of a proton collision.

Artist's impression of the immersive detector experience. Image credit: Science Museum / Nissen Richards Studio

Artist’s impression of the immersive detector experience. Image credit: Science Museum / Nissen Richards Studio

Key figures from CERN, such as Professor Heuer, attended a gala ceremony held last month by the Fundamental Physics Prize Foundation at the Geneva International Conference Centre, hosted by Hollywood actor and science enthusiast Morgan Freeman with performances by singer Sarah Brightman and Russian pianist Denis Matsuev. Freeman mused that it was “a bit like the Oscars” and made the best joke of the night when referring to complaints about physicists ‘playing god’: “I have done it twice and I don’t see the problem.’

Yuri Milner, the Russian theoretical physicist turned internet entrepreneur who backs the prizes through his Milner Foundation, said it “celebrates what is possible in humanity’s quest to understand the deepest questions of the universe.”

The evening celebrated two Special Fundamental Physics Prizes of $3,000,000, one for Prof Stephen Hawking, who himself has been the subject of a special exhibition here at the Science Museum, for his discovery of Hawking radiation from black holes, and his deep contributions to quantum gravity and quantum features of the early universe, based on his efforts to combine theories of the very big (general relativity) with the very small (quantum theory). In his acceptance speech, Hawking thanked Milner for recognising key work in theory with what is now the most lucrative academic prize on the planet.

The second special prize was shared by the leaders of the LHC project, CMS and ATLAS experiments from the time the LHC was approved by the CERN Council in 1994: Peter Jenni, Fabiola Gianotti (ATLAS), Michel Della Negra, Tejinder Singh Virdee, Guido Tonelli, Joe Incandela (CMS) and Lyn Evans (LHC), for their role in the epic endeavour that led to the discovery of the new Higgs-like particle.

After they all took the stage Mr Matsuev performed Edvard Grieg’s “The Hall of the Mountain King”, presumably a reference to the great caverns in which the Higgs-like particle was first spotted. The award-winning biographer Graham Farmelo, who has advised on the development and launch of Collider, said it was ‘the most impressive gathering of great physicists for almost ninety years – since Einstein and most of the other discoveries of relativity and quantum theory met at the famous Solvay Conference in 1926’.

The Museum’s £1m Collider exhibition is part-funded by the Science and Technology Facilities Council, Winton Capital Management, the Embassy of Switzerland in the United Kingdom, and is supported by a number of individuals.

Collider will open in November 2013 and run for six months. Visits to Collider will be timed and, to avoid disappointment, please visit sciencemuseum.org.uk/collider to book tickets.

View of the LHCb cavern

X-citing news from CERN

Dr. Harry Cliff, a Physicist working on the LHCb experiment and the first Science Museum Fellow of Modern Science, writes about a new discovery at CERN for our blog. A new Science Museum exhibition about the Large Hadron Collider will open in November 2013, showcasing particle detectors and the stories of scientific discoveries.

In 2003 physicists at the Belle experiment in Japan reported they had discovered a brand new particle.

Adding a new entry to the big book of particle physics is certainly satisfying, but not usually cause for much excitement. The discovery of the Higgs-like boson last year was an exception. After all, hundreds of particles have shown up in experiments over the last century. So many in fact, that they were often referred to, rather derisively, as a “zoo”.

The Large Hadron Collider at CERN. Image Credit: CERN

But the particle found at Belle was different.

It didn’t fit neatly into the picture painted by theory and there was no clear explanation for its origin. It was a bit of an enigma, and earned a suitably enigmatic name: the X particle.

Professor Val Gibson from the University of Cambridge told me that she and her colleagues “have been mesmerized” about the identify this mysterious particle for the last ten years.

The Particle Zoo

The vast majority of the particles that make up the particle zoo are not fundamental; in other words they are made up of smaller things and these things are fundamental particles called quarks. Six different types of quark have been discovered and they can form a large number of different combinations, explaining the particle zoo.

However, quarks only bind together in very specific ways. Two ways in fact. One option is a ménage à trois known as a baryon. Baryons include the proton and the neutron, the building blocks of the atomic nucleus. The other option is where a quark and an antiquark couple up to form a meson.

The X didn’t fit easily into either of these pictures. This generated a lot of excitement and there was speculation as to whether it could be an ordinary meson, or some new exotic combination involving four quarks, a tetraquark, or a “molecule” of two mesons stuck together.

If this were true it would be the first time such an exotic state had been definitively seen in nature.

The only way to tell would be to measure the quantum numbers of the X, three properties that give a clue to its internal structure. This hadn’t been possible, until now.

Exciting, Exotic X

Amid the hundreds of trillions of collisions generated by the Large Hadron Collider over the past three years physicists at the LHCb experiment (the experiment I work on) managed to pick out about 300 X particles.

View of the LHCb cavern

View of the LHCb cavern. Image credit: CERN

This week, they presented the first full measurement of the quantum numbers of the X, at a conference at La Thuile in Italy. The result was emphatic – the X is not a meson, it is something altogether more exotic.

LHCb physicist Dr Matt Needham told me that “this measurement is a great step forward in understanding this mysterious X” and a “very exciting result”. However, there is still work to be done.

“The real nature (of the X) is still unclear”. Whether it’s a tetraquark, meson molecule or something else entirely must now be determined.

His colleagues at LHCb will now search for signs of the X decaying in new ways to try to separate out the various different options. Although the Large Hadron Collider has now shut down for two years physicists at LHCb will have no shortage of data to work with. An unprecedented sample was collected during 2012, corresponding to 180 trillion collisions, each one producing hundreds of particles.

The true nature of this enigmatic particle may soon be known. Whatever the result, we have now had our first glimpse of an altogether new state of matter. Finding out exactly what the X is will bring us deeper understanding of nature’s fundamental building blocks and the forces that bind them together.

Visitors to the Science Museum will have a chance to get up close and personal with the LHC at a new exhibition opening in November 2013. The exhibition will showcase real pieces of the LHC, including an intricate particle detector from the heart of the LHCb experiment.

LHC home screen Jan 3rd

The LHC’s Christmas Holiday

Over the past three weeks, deep under the Jura Mountains on the Swiss-French border, a monster has been sleeping. Over Christmas, the Large Hadron Collider, the world’s largest experiment, takes a break from colliding protons together in an underground tunnel. The machine normally runs for 24 hour-a-day, seven days a week, but for four weeks in January and December, it is switched off.

LHC home screen Jan 3rd

So long, and thanks for all the fish! The LHC operators look forward to their Christmas holiday.

There are several reasons for the extended break. The physicists, engineers and support staff who operate the machine and experiments are human. Yes, they are devoted to the search for the fundamental laws that govern the Universe, but they also like to indulge on Christmas pudding and see their families.

That explains why the LHC doesn’t run on Christmas day, but why does it shut down for three weeks?

Because it’s cold outside.

The cold doesn’t affect how the LHC works – far from it, as the machine is cooled to -271ºC. But it does affect the power supply.

One of the most intriguing facts I’ve learned over the course of working on the Science Museum’s upcoming LHC exhibition is that even though the LHC does an extremely specialised and power-consuming task – accelerating protons so they have the energy of a high speed train and are travelling at nearly the speed of light – the machine takes its power from the French grid. The same nuclear, coal and hydro-electricity plants that provide the energy to light the Mona Lisa and charge your mobile on holiday also power the LHC.

When it’s cold outside French electricity consumption spikes. In December, France uses about 50 percent more electricity than it does in August, heating, cooking and lighting dark days. When all systems are go, CERN can use as much as a third of Geneva’s power, or the same as a large town. So during darkest depths of winter, when the French grid is being stretched the most, the LHC powers down.

The time off isn’t wasted. Repairs and upgrades are always needed, so engineers have been busy tweaking to ensure the LHC is in tip-top condition for its run in 2013. From next week LHC will fire protons into lead nuclei for a month. After that short run, the machine shuts for two years for a serious upgrade.