Tag Archives: Collider

LHC: Lip Hair Champions

Content Developer Rupert Cole explores some famous moustaches in particle physics ahead of the opening of our new Collider exhibition on 13th November. 

It’s that time again: Movember – the eminently charitable moustache-growing month raising awareness for men’s health. But what, you might reasonably wonder, has facial hair got to do with particle physics? Well, I have a theory; one backed by hard pictorial and anecdotal evidence…

The Cavendish lab’s moustachioed students, 1897. Credit: Cavendish Laboratory

The Cavendish lab’s moustachioed students, 1897. Credit: Cavendish Laboratory

Consider the glory days of Cambridge’s Cavendish Laboratory, during which the first subatomic particle was identified, a revolutionary particle detector invented, and the atomic nucleus split by one of the first particle accelerators. Significantly, the great Cavendish leaders and pioneers of this period cannot be accurately described as clean shaven.

Joseph John Thomson

JJ Thomson has a “rather straggling moustache,” wrote a talented student called Ernest Rutherford in 1896, “but a very clever-looking face and a fine forehead”. In another letter to his fiancé, Rutherford made the additional comment that Thomson “shaves very badly”.

We may detect a hint of jealousy in Rutherford’s description of Professor “JJ”. As, according to one chronicler of the lab’s history, the young student Rutherford possessed only “a thinly sprouting moustache”.

JJ Thomson. Credit: Cavendish Laboratory

JJ Thomson. Credit: Cavendish Laboratory

Nevertheless, concealed in Thomson’s supposedly wayward bristles was a creative and audacious genius. At the time, the Cavendish’s director had been performing his groundbreaking experiments on cathode rays. The next year he shocked the scientific world when he announced the existence of a particle smaller than the smallest atom – later dubbed the “electron”.

Ernest Rutherford

Once the rambunctious New Zealander’s lip-hair had acquired its full bushy substance, he was well on the way to scientific stardom.

His first momentous contribution to physics came in 1902 at McGill University, Canada. Rutherford and his colleague Frederick Soddy explained what radioactivity actually is – the process of atomic decay.

Soddy described his co-discoverer simply as an “exuberant natural, young man with a moustache”. Biographers would later characterise Rutherford’s ever-growing asset as reminiscent of a “walrus”.

By the time he succeeded his old moustachioed mentor, JJ Thomson, as Professor of the Cavendish, Rutherford had already discovered the atomic nucleus (1911) and managed to split nitrogen atoms in half, causing them to transmute into two oxygen atoms (1917-19).

But it was at the Cavendish that he ushered in the era of accelerator physics. Contemporaries recall a particular accessory: a pipe, containing the world’s driest and instantly-flammable tobacco.

Ernest “The Walrus” Rutherford. Credit: Science Museum / SSPL

Ernest “The Walrus” Rutherford. Credit: Science Museum / SSPL

On one Spring day in 1932, Rutherford entered the lab in a famously foul mood. His pipe “went off like a volcano” – having pre-dried his tobacco on a radiator. Impatient at the progress his young researchers John Cockcroft and Ernest Walton had made with their 800,000-volt proton accelerator, he instructed them to “stop messing about… and arrange that these protons were put to good use”.

At Rutherford’s suggestion, they immediately installed a zinc-sulphide scintillation screen – a device which causes charged particles to sparkle when they hit – into their wooden observation hut. A few days later, Walton saw on this screen evidence that their machine was splitting the nucleus of lithium atoms!

Had the authority of the tache and pipe not intervened, the Cavendish men may have been pipped to the discovery by the clean-shaven American teams, who boasted the biggest and best of accelerators.

Charles Thomson Rees Wilson

CTR Wilson, one of Rutherford’s fellow students at the Cavendish, was a
“modest” personality with a similarly unassuming moustache. He spent 16 years assembling cloud chambers – a device he initially invented to study meteorological phenomena.

A keen mountaineer – an activity that always complements well-trimmed bristles – Wilson derived inspiration to build cloud chambers when he was atop Ben Nevis, observing beautiful optical effects.

His third and final chamber, completed in 1911, was later described by Rutherford as “the most original and wonderful instrument in scientific history”. Incredibly, it could capture with photographs the tracks of particles. Wilson had invented the first detector that could visualise and record the subatomic world.

CTR Wilson, 1927. Credit: AB Lagrelius and Westphal

CTR Wilson, 1927. Credit: AB Lagrelius and Westphal

It seems remarkable that the humble moustache may have had such a crucial role in the foundation particle physics. Never again would the Cavendish be led by lip-hair champions; and considering the lab’s unprecedented success in this golden period, we can reliably infer the cost of this absence.

I leave you with the words of Arthur Eddington: “An atom which has lost an electron is like a friend who has shaved-off his moustache.”

Next week you can see Thomson’s cathode-ray tube, Rutherford’s atomic models, the Cockcroft-Walton accelerator, CTR Wilson’s cloud chamber, and much more at the Science Museum’s new Collider exhibition. 

For more famous physics moustaches click here.

LHC: Lifting Heavy Contraptions

Curator Ali Boyle on how the Collider team are installing some of the larger objects in our new exhibition. 

It’s just three weeks to go until Collider opens with a flurry of exciting events. Which means that we’re getting to the best part of exhibition work – after all the planning, the objects are finally starting to make their way onto gallery.

That’s sometimes easier said than done when your objects come from CERN. A few are so large that we’ve had to install them on gallery early and build the rest of the exhibition around them. First up was the object we call The Beast, a 2-tonne section of one of the giant dipole magnets that keep the LHC’s particle beams on course.

Thankfully it was only a section – a whole LHC magnet weighs in at 35 tonnes and is 15 metres long. And our basement gallery is a lot easier to get to than a tunnel 175 metres below ground, the challenge faced by CERN as they upgrade the LHC’s magnet system.

dipole_lifting

Conservator Richard (in white) supervises The Beast being lowered onto its trolley. (Credit: Alison Boyle)

Another 2-tonne behemoth, delivered from CERN that morning, followed – an accelerating cavity from LEP, the Large Electron Positron collider, which previously occupied the tunnel that now houses the LHC. The copper cavity, used in the first phase of LEP operations, looks like something Jules Verne might have imagined.

The LEP cavity's storage sphere is carefully lowered into place. (Credit: Alison Boyle)

The LEP cavity’s storage sphere is carefully lowered into place. (Credit: Alison Boyle)

Of course, being the Science Museum, we’re used to big bits of kit. The LHC objects, although hefty, were a piece of cake compared with getting the planes in. Or handling the 4-tonne Rosse Mirror, which we moved into its current position in Cosmos & Culture in 2009.

Made of speculum, a mixture of copper and tin, the Rosse Mirror is six feet in diameter. It is one of the few surviving original pieces of the largest scientific instrument of its day, the enormous telescope built by the Earl of Rosse at Birr Castle in the Irish midlands and known as the  ‘Leviathan of Parsonstown’. The mirror was donated to us in 1914 – here it is being delivered.

Easy does it … moving the Rosse Mirror into the Western Galleries, 1914. (Credit: Science Museum)

There’s a clear distinction between ‘doers’ and ‘watchers’ in this photograph. On Collider this week I was definitely the latter. As those keen observers of the museum world, the Ministry of Curiosity, point out, curators rarely do the actual muscle work.

So, rather than take my word for it, why not ask someone who really knows about moving big bits of particle accelerator around? Lyn Evans (or ‘Evans the Atom’ as he’s dubbed in the press) was Project Leader for the LHC build. Next Wednesday 30 October, thanks to our friends at the London Science Festival, you can hear him talk about the LHC’s engineering challenges at Science Museum Lates. He’ll be joined by Collider‘s very own Harry Cliff, who’ll give a sneak preview of how we’re bringing CERN to South Kensington. Not all of it obviously, as that would be a bit too heavy…

Discover more about the Higgs boson and the world’s largest science experiment in our new exhibition, Collider, opening on 13th November 2013.

Celebrate the Nobel Prize at the Science Museum

Roger Highfield, Director of External Affairs at the Science Museum, celebrates the 2013 Nobel Prize for Physics ahead of the opening of our Collider exhibition next month.      

Congratulations to Briton Peter Higgs and Belgian François Englert, winners of the 2013 Nobel Prize for Physics “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.”

A few minutes ago, after an unusual delay, the Royal Swedish Academy of Sciences announced the winners of the physics prize in Stockholm, ending this chapter of the quest for new elementary particles, the greatest intellectual adventure to date.

Ian Blatchford, Director of the Science Museum, comments: “That it has taken decades to validate the existence of the Higgs Boson illustrates the remarkable vision of the theoretical work that Higgs, Francois Englert and others did with pen and paper half a century ago, one that launched an effort by  thousands of scientists and inspired a staggering feat of engineering in the guise of the Large Hadron Collider.

What is the Higgs? Here’s all you need to know, in just 90 seconds, from Harry Cliff, a Cambridge University physicist working on the LHCb experiment and the first Science Museum Fellow of Modern Science

Although the identity of the winners has been a closely-guarded secret, many have speculated that those who played a central role in discovery of the long-sought Higgs, notably the emeritus Edinburgh professor himself, were leading contenders for a place in history.

The Science Museum has been so confident that the Large Hadron Collider would change our view of nature that we have invested more than £1 million, and worked closely with the European Organization for Nuclear Research, CERN, to celebrate this epic undertaking with its new exhibition, Collider: step inside the world’s greatest experiment, which opens to the public on 13 November. 

Here Higgs explains how the Large Hadron Collider works during a visit to what is now Cotham School, Bristol, where he was once a pupil.

In July 2012, two separate research teams at CERN’s £5 billion Large Hadron Collider reported evidence of a new particle thought to be the Higgs boson, technically a ripple in an invisible energy field that gives most particles their mass.

This discovery represented 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.

Nima Arkani-Hamed, a leading theoretical physicist at the Institute for Advanced Study in Princeton who will attend the launch of Collider, bet a year’s salary the Higgs will be found at the LHC.

Another speaker at the Collider launch, the world’s most famous scientist, Prof Stephen Hawking, lost a $100 bet he made against the discovery (though he is adamant that Higgs deserves the Nobel Prize).

Higgs, who refuses to gamble, told me just before the LHC powered up that he would have been puzzled and surprised if the LHC had failed in its particle quest. “If I’m wrong, I’ll be rather sad. If it is not found, I no longer understand what I think I understand.”

When Higgs was in the CERN auditorium last year to hear scientists tell the world about the discovery, he was caught reaching for a handkerchief and dabbing his eyes.  On the flight home, he celebrated this extraordinary achievement with a can of London Pride beer.

The Science Museum hoped to have the can, now deemed a piece of history Alas, Higgs had dumped it in the rubbish before we could collect it. However, the museum does possess the champagne bottle that Higgs emptied with his friends the night before the big announcement.

The champagne bottle Peter Higgs drank from, the night before the Higgs boson discovery was announced to the world. Credit: Science Museum

The champagne bottle Peter Higgs drank from, the night before the Higgs boson discovery was announced to the world. Credit: Science Museum

The modest 84-year-old  is now synonymous with the quest: the proposed particle was named the Higgs boson in 1972.

But there have been demands that the particle be renamed to acknowledge the work of others. Deciding who should share this Nobel has been further complicated because a maximum of three people only can be honoured (prompting many to question the criteria used by the Nobel committee).

The LHC, the world’s most powerful particle accelerator, is the cumulative endeavour of around ten thousand men and women from across the globe. In recognition of this the Collider exhibition will tell the behind-the-scenes story of the Higgs discovery from the viewpoint of a young PhD student given the awesome task of announcing the discovery to her colleagues (though fictional, the character is based on Mingming Yang of MIT who is attending the launch).

However, although one suggestion is to allow the two research teams who discovered the Higgs boson to share the accolade, the Nobel committee traditionally awards science prizes to individuals and not organizations (unlike the Nobel Peace Prize).

Instead, the Nobel committee honoured the theoreticians who first anticipated the existence of the Higgs.

Six scientists published the relevant papers in 1964 though, as Belgium’s Robert Brout died in 2011, there were five contenders (the Nobel Prize cannot be given posthumously).

In August 1964, François Englert from the Free University of Brussels with Brout, published their theory of particle masses. A month later, while working at Edinburgh University, Higgs published a separate paper on the topic, followed by another in October that was – crucially – the first to explicitly state the Standard Model required the existence of a new particle. In November 1964, American physicists Dick Hagen and Gerry Guralnik and British physicist Tom Kibble added to the discussion by publishing their own research on the topic.

Last week, Prof Brian Cox of Manchester University, who works at CERN, said it would be ‘odd and perverse’ not to give the Nobel to Peter Higgs, and also singled out Lyn ‘the atom’ Evans, the Welshman in charge of building the collider, as a candidate.

And the two likeliest winners were named as Peter Higgs – after whom the particle was named – and François Englert, according to a citation analysis by Thomson Reuters.

Today’s announcement marks the formal recognition of a profound advance in human understanding, the discovery of one of the keystones of what we now understand as the fundamental building blocks of nature.

Discover more about the Higgs boson and the world’s largest science experiment in our new exhibition, Collider, opening 13th November 2013.

Unboxing CERN

Content Developer Rupert Cole on unboxing objects from CERN for Collider, a new Science Museum exhibition opening in November 2013.

There are not many things that would persuade me to wait for a van in the rain at 7am; but this was not to be missed. For on this particular cold, wet and early morning at the Science Museum, our hotly-anticipated Collider objects were due to arrive from CERN.

8am. An hour on and the van was here. Evidently, good objects come to those who wait.

Unveiling the LHC crates. Credit: Harry Cliff

Unveiling the LHC crates. Credit: Harry Cliff

Maybe it was the fact we had been working with only object dimensions and tiny pictures, but the first sight of even just the crates, in their various sizes and shapes, suddenly made the exhibition feel all the more real and tangible.

Broadly there were two concerns. Was everything there? And how to shift a two-tonne superconducting dipole magnet, aka “the Beast”? Luckily, on hand to help with the latter was a forklift truck – naturally, delivered by a bigger truck.

One forklift truck. Credit: Harry Cliff

One forklift truck. Credit: Harry Cliff

Once the two-tonne Beast had been fork-lifted over to the Goods Lift (conveniently situated up a slope) there was the small matter of getting it in. At this stage, ascertaining whether everything had come relied on the skilful art of imagining which object might fit in which crate. Given the variety of objects, ranging from a 22-cm delicate crystal detector piece to a whopping 2-metre-long iron magnet, guessing according to the logic of packing was relatively straight forward.

Later, came the Christmas-esque joy of cracking open the crates and seeing the LHC treasures in the flesh. Looking at the cross-section cut of the dipole magnet, it was nice to see that even “the Beast” had a friendly face.

Dipole magnet cross section. Credit: Harry Cliff

Dipole magnet cross section. Credit: Harry Cliff

After the museum conservators have polished various nooks and crannies, and the workshop team have made some mounts, the objects will be installed into this empty gallery – and soon after that, the gallery will make its dramatic transformation into the world’s greatest scientific experiment.

Exhibition space ready for the Collider exhibition. Credit: Ali Boyle

Exhibition space ready for the Collider exhibition. Credit: Ali Boyle

Come and experience the sights and sounds of CERN at Collider, a new immersive exhibition opening this November at the Science Museum. Book tickets here

Beaming with Joy: LHC celebrates five years of not destroying the world

Content Developer Rupert Cole, and Science Museum Fellow of Modern Science Dr. Harry Cliff, celebrate the LHC’s 5th birthday for Collider, a new Science Museum exhibition opening in November 2013.

Five years ago, at breakfast time, the world waited anxiously for news from CERN, the European Organization for Nuclear Research. The first nervy bunch of protons were due to be fired around the European lab’s latest and biggest particle accelerator, the Large Hadron Collider (LHC), as it kicked into action.

Some “mercifully deluded people” – as Jeremy Paxman put it – feared the LHC would do no end of mischief. There was talk of planet-swallowing black holes, the transformation of the Earth into a new state of “strange” matter, and even the prospect of the obliteration of the entire universe. But for those of more sensible dispositions, the LHC’s first beam was an occasion for great excitement.

As the protons sped all the way round the 27km tunnel under the countryside between Lake Geneva and the Jura Mountains, thousands of physicists and engineers celebrated decades of hard work, incredible ingenuity and sheer ambition. Together they had created the largest-ever scientific experiment.

After the LHC was switched on, project leader Lyn Evans said, “We can now look forward to a new era of understanding about the origins and evolution of the universe.”

Operating a massive particle accelerator requires much more than flicking a switch – thousands of individual elements have to all come together, synchronised in time to less than a billionth of a second.

University College London’s physicist Jon Butterworth recalls a “particularly bizarre memory” from that day. Relaxing in a Westminster pub after an exhausting LHC event in London, Butterworth found he could follow live updates from his own ATLAS experiment on the pub’s TV.

Time for a rest. Credit: CERN

Particle physics continued to make news. The following fortnight’s joy turned to dismay as an accident involving six tonnes of liquid helium erupting violently in the tunnel – euphemistically referred to as “the incident” – damaged around half a mile of the collider, closing the LHC for a year.

Since then, besides the brief setback that was “baguette-gate”, a bizarre episode when the collider was sabotaged by a baguette-wielding bird, the LHC has been producing great work. Hundreds of scientific papers have been published by the CERN experiments, on topics as diverse as searches for dark matter candidates, the production of the primordial state of matter (known as quark-gluon plasma) and precision measurements of matter-antimatter asymmetries.

However, it was on July 4 last year, that the LHC snared its first major catch with the discovery of the Higgs boson – as one of the most significant scientific finds of the century. The Higgs boson was one of the longest-sought prizes in science – it was almost fifty years ago in 1964 that three groups of theorists laid the ground-work for what would become the final piece of the theory known as the Standard Model of Particle Physics. They proposed an energy field, filling the entire Universe that gives mass to fundamental particles.

This “Higgs mechanism” neatly explained why the weak nuclear force was so weak and why light is able to travel over infinite reaches of space. It also laid the groundwork for the unification of the weak and electromagnetic forces into a single “electroweak” force, in a coup similar to James Clerk-Maxwell’s unification of electricity and magnetism in the 19th century.

Peter Higgs at CERN’s public announcement of the Higgs Boson, 4 July 2012. Credit: CERN

However, like air, the Higgs field itself is invisible; the only way to know if it is there is to create a disturbance in it, like a breeze or a sound. It was Peter Higgs who first suggested that if the field existed, it would be possible to create such a disturbance, which would show up as a new particle. Hence, the boson was named after him, much to the irritation of some of the other five theorists responsible for the theory.

The LHC’s discovery of the Higgs closed a chapter in the development of fundamental physics, placing the keystone into the great arch of the Standard Model. The LHC is currently being upgraded so that in 2015 it will reopen at almost double its previous energy. What every scientist is now aching for is a sign of something new, physics beyond the Standard Model, and most probably beyond our wildest aspirations.

This article was originally published at The Conversation (original article).

Through the past, present and future, follow the compelling drama, the amazing achievements and the inspirational hopes of the LHC at Collider, a new exhibition opening this November at the Science Museum.

The Conversation

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.