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James Doherty | Open University | United Kingdom

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If you can’t stand the heat, get into the Synchrotron!

Friday, May 16th, 2014

I attended the Australian Accelerator School in January of this year.  Better late than never, I recount some of my experiences below.

It’s Day 1 of the Australian Accelerator School and Melbourne is the hottest city on Earth with temperatures soaring above 40°C – which is a bit much when one has just arrived from a soggy UK winter. Fortunately, the Australian Synchrotron is housed in a beautifully air-conditioned building located in the suburbs of Melbourne, just next door to Monash University.

The Australian Synchrotron, which opened in 2007, is the largest stand-alone piece of scientific infrastructure in the southern hemisphere and provides a source of highly intense light which is used for a wide range of research purposes. It is situated on a modern site with the circular synchrotron at its focus, surrounded by several other buildings.

Beampipe: getting acquainted with the Australian  Synchrotron.

Beampipe: getting acquainted with the Australian Synchrotron.

The School has gathered 23 students, mainly from Australia and New Zealand, and an impressive panel of experts. Phil Burrows of Oxford University is the keynote lecturer and will provide a step-by-step guide on the physics and maths underpinning particle accelerators. Ralph Steinhagen of CERN is armed with over 700 slides on the technical aspects of accelerator operation. Toshi Mitsuhashi of KEK, aka the “Master”, will share his vast experience on the optics of accelerators, while Jeff Corbett of SLAC will lead laboratory exercises. And not forgetting Roger Rassool of Melbourne University, who will be present to add his irrepressible energy and enthusiasm to proceedings.

Mornings are to be spent in lectures and afternoons in the lab. In labs we will have the chance to develop practical skills, such as soldering, using oscilloscopes, programming Arduino chips, and modelling electronic circuits and particle accelerators. There are also various international conferences running through the fortnight, some sessions of which we will be attending. The programme will conclude with a group project, to be presented to the experts on the final day of the school. And there’s the odd social event to attend too.

In true Aussie fashion we are welcomed with a barbecue – although we all feel feel more cooked than sausages after a few minutes outdoors. And we’ll be kept sweating over the next 12 days…

Stay tuned for wine + DIY particle physics…


Day 1 labs: getting familiar with oscilloscopes.


Citizen Science – a power for change that’s here to stay

Monday, March 17th, 2014

I previously blogged about how CERN is embracing the power of citizen science to assist with it’s research (see here). LHC@home also allows non-scientists to get involved with particle physics at CERN. To learn a bit more about citizen science, I recently attended the third Citizen Cyberscience Summit in London, and was asked by online publication ‘International Science Grid This Week’ to write an article on the event. The article was published here on 12 March 2014, and I replicate it below.

February saw London host the Third Citizen Cyberscience Summit, a three-day event dedicated to the expanding field of citizen science. More than 300 delegates from around the world assembled to network, share ideas, and get creative. The event provided fascinating insight into how computers, mobile phones, and other devices are helping to mobilize the citizen science community. Attendees were left with the distinct impression that citizen science is no passing fad but a movement on the forefront of a fundamental shift in how we approach science and education.

Citizen Science?

For the uninitiated, citizen science is scientific research conducted in whole or part by amateur or non-professional scientists. There is a spectrum of different kinds of citizen science from ‘crowdsourcing’, in which citizens analyze data, to ‘extreme citizen science’, where scientists collaborate with citizens in problem definition, data collection and analysis.

One of the youngest delegates gets the chance to hack a drone. Image courtesy James Doherty.

One of the youngest delegates gets the chance to hack a drone. Image courtesy James Doherty.

Citizen science stars

On day one of the summit, keynote speeches from the heavyweights of citizen science left delegates with no doubt that citizen science is a big deal. The crown jewel of citizen science remains the Zooniverse, a top-down crowdsourcing platform where citizens analyze large sets of data, such as pictures of galaxies that need to be classified as elliptical or spiral. The Zooniverse has reached the significant milestone of one million contributors and plans to use human input to program computers for data analysis.

Other leaders in the field include Eyewire, an addictive game in which participants help scientists map neural connections in the brain. Erinma Ochu delivered a heart-warming account of her sunflower project, in which participants grow and help to analyze sunflowers, and Daniel Lombraña González reported on how CrowdCrafting has helped interest groups in the US monitor fracking activities.

World Community Grid, which uses spare capacity on computers and mobile devices to power scientific research on health, poverty and sustainability, was also featured at the summit. Sophia Tu and Juan Hindo of IBM, which sponsors and supports World Community Grid, announced a major scientific breakthrough in childhood cancer. Donated computing capacity has enabled researchers of childhood cancer to discover seven drug candidates that are highly effective at destroying tumors without any apparent side effects. This may also have applications for adult cancers, including breast and lung cancer.

The atomic force microscope hacked by Lego2nano students. Image courtesy James Doherty.

The atomic force microscope hacked by Lego2nano students. Image courtesy James Doherty.

Tu and Hindo also talked at the summit about their experience launching an Android mobile app in partnership with BOINC of the University of California, Berkley, US, last July, becoming one of the first volunteer computing initiatives to go mobile. They found that many citizen scientists are more comfortable downloading a mobile app than installing software on their computer: signups jumped ten times the week of launch and the app quickly reached ‘Top 5 Trending’ status in the Google Play store.

Citizen science’s expanding influence was evidenced by a series of talks on policy and engagement. Jacquie McGlade’s video presentation highlighted the importance of inclusiveness and keeping the gates of citizen science open to all. A recurring theme emerged that citizens are enjoying more autonomy in defining the projects to which they contribute. And Kaitlin Thaney of the Mozilla Science lab argued that the wider researcher community should draw inspiration from citizen science and the web’s open-source revolution to itself become more open and collaborative.

Engaging and empowering citizens

On the second day, the summit moved to less formal surroundings in University College London (UCL), UK, for workshops, panel discussions, and short presentations. A panel debate with five female citizen scientists highlighted the commitment of people engaged with citizen science and the empowerment they experience from contributing to projects.

At a series of talks on DIY citizen science, Francois Grey, coordinator of the Citizen Cyberscience Centre, described how the Lego2nano summer school program mobilized a group of students to construct an atomic force microscope for a fraction of the price of those found in modern labs. Grey argued that because so much can be learned from making and programming technology, young people should be encouraged to become makers, engineers, and programmers.

In the evening, the Citizen Science Cafe also afforded those not attending the conference the opportunity to pop-in after work to mingle with others passionate about citizen science.

What can you do for your community?

By day three of the summit, delegates were chomping at the bit to start doing some citizen science themselves. Saturday’s ‘hackdaychallenge’ provided an opportunity for collaboration on a number of different projects, including: constructing an application that enables citizens to analyze photographs from the International Space Stationmaking the most of solar panels installed in Ghanian schools; and an application developed by child psychologist Caspar Addyman for analyzing baby laughter. The winning project was the Pulse Sensor Textile Challenge, which aims to measure the impact of textiles on emotions.

The closing keynote presentation was delivered by journalist-turned-academic Jeff Howe, who first coined the term ‘crowdsourcing’. In this entertaining and insightful talk, Howe noted that the most successful crowdsourcing projects are often a gift from an individual to the community, and providediStockphoto.com as an illustrative example. He argued that the cardinal rule of crowdsourcing is that one should ask ‘what can you do for your community, not what your community can do for you’. Like Grey, Howe suggested that citizen science has the potential to bring about a fundamental change in how young people are educated.

Hackday team discusses how photographs taken on mobile phones may be used in disaster response. Image courtesy James Doherty.

Hackday team discusses how photographs taken on mobile phones may be used in disaster response. Image courtesy James Doherty.

More than a passing fad

A recent article in Nature hinted at a certain decline in citizen science, but little evidence of this trend was on display at the summit, which was saturated with energy, enthusiasm and love for citizen science. Grey described the event not as a “thin broth with just one intellectual ingredient but a rich stew of ideas with spices from far-away fields”. This is, indeed, reflective of the pervasive nature of citizen science: there is a vibrant community across the globe analyzing data, playing games, growing sunflowers, posting pictures, monitoring pollution, and more.

So, citizen science seems to be much more than a passing fad that is now in decline. Rather, it is a movement that empowers its participants. That demands openness, collaboration and accessibility. That has the potential to bring about change. And most importantly that recognizes, as Howe puts it, that “everyone has something to offer”.


Accelerating Down Under

Tuesday, January 14th, 2014

Believe it not, there are particle accelerators to be found beyond the outer-Geneva area – even in such far flung locations as Melbourne, Australia. You may recall from a previous blog post that I befriended some Aussie particle physicists at CERN during the summer who kindly invited me to a two-week accelerator school at the Australian Synchrotron in Melbourne. And here I am!

The Australian Synchrotron opened in 2007 and is the largest stand-alone piece of scientific infrastructure in the southern hemisphere. It is a source of highly intense light which is used for a wide range of research purposes.

The Australian Synchrotron.

The Australian Synchrotron.

Synchrotrons are circular machines which accelerate electrons to extremely high energies, producing electron beams which travel at almost the speed of light. As the beam of electrons takes a circular path around the machine, the electrons emit intense radiation known as synchrotron light. This light is really useful for imaging, analysis and in a wide range of scientific experiments.

In some accelerators, operators attempt to minimize the emission of synchrotron radiation so that particles retain maximum energy for high-energy collisions. For example, in the Large Hadron Collider (LHC), protons are accelerated as they have a much larger mass than electrons and so suffer less from loss of synchrotron radiation. Also, the larger the circumference of the circular path which the particles take, the weaker the synchrotron radiation emission – that’s why the LHC was built with a huge 27 km circumference. Linear accelerators, such as the Stanford Linear Accelerator Center (SLAC) in the US, avoid the emission of synchrotron radiation altogether as particles travel in a straight line.

So a synchrotron’s key output – synchrotron light – is the very same thing which operators of other accelerators voraciously try to minimize.

The Australian Synchrotron’s accelerator school is an intensive two-week course on particle physics and accelerators. It attracts student physicists from across Australia (and occasionally the UK!), as well as lecturers and tutors from leading institutions from across the world.

Stay tuned over the next few weeks to hear about my adventures at the Australian Synchrotron.


Summer on the Higgs Farm

Friday, November 8th, 2013

The Open University asked me to write an article on my time at CERN over the summer. I replicate the article below which was published by the OU on 5 November 2013 here. The article pulls together my experiences on the CERN Summer Programme and provides links to particular blog entries on this site should you wish to learn more. Enjoy!

I got lucky – very lucky. For I spent this summer at CERN in Switzerland at the world’s greatest laboratory and the birthplace of the Nobel-winning Higgs boson. I am studying physical sciences with the OU and in this article I recount an incredible, challenging and unforgettable summer. I also include links to my blog which you can click to learn more about life at CERN.

What is CERN?

CERN, or the European Organization for Nuclear Research, is an international organisation which operates the world’s largest particle physics laboratory. At CERN scientists use complex scientific instruments to probe the fundamental structure of the universe and basic constituents of matter – fundamental particles.

CERN is the home of the world’s largest machine, the Large Hadron Collider (LHC): a 27km circular particle accelerator that collides particles which are travelling at close to the speed of light. The LHC was used to observe the Higgs boson, a particle which is the by-product of a mechanism by which other fundamental particles acquire mass. This observation led to Peter Higgs and Francois Englert being announced as winners of a Nobel Prize for Physics in October 2013.

Learn more about the Higgs Nobel here, here and here.

The Student Summer Programme

Each year CERN invites around 300 physics, engineering and computer science students from across the globe to participate in its Summer Student Programme. The programme affords students the opportunity to attend a six week lecture series on particle physics and related topics, and also to carry out a research project.

Learn more about the CERN Summer Student Programme here.


This year’s crop of summer students pose outside CERN’s showcase visitor’s centre, Globe.

First impressions

CERN is plonked in the midst of beautiful agricultural estates which nestle between the Alps and Jura mountain ranges, with several sites on either side of the Swiss-French border. Smaller experiments are based on the main Meyrin site on the outskirts of Geneva, while larger accelerators, such as the LHC, extend into France.

On arrival one is rather taken aback by how plain, industrial and, dare I say, ugly CERN is. Buildings are haphazardly distributed and typical of 1960 university campus architecture. But there is more to CERN than first meets the eye.

More first impressions here.

CERN's Meyrin site.

CERN’s Meyrin site.

What are the people like?

There are approximately 10,000 people on the CERN site each day who hail from all corners of the Earth. One need only walk into the main restaurant at lunchtime to sense the excitement in the air at CERN. People know they’re involved with something special and they want to be there. The diverse, multicultural and enthusiastic workforce creates a fantastic atmosphere.

The lectures

The lecture series was intense, technical and extremely interesting. Topics ranged from theoretical and mathematical subjects, such as the Standard Model and Supersymmetry (theoretical models which explain how fundamental particles interact), to more applied and technical topics, such as the operation of particle accelerators and detectors. Lectures were delivered by leaders in the field and daily Q&A sessions provided an excellent opportunity to interrogate them.

More on the lecture series here.

My research

I worked in the Beam Instrumentation Group to develop a new type of beam position monitor (BPM) for the LHC. This is a gizmo which measures the position of the beams of particles which circulate around the LHC so that they can be kept on target. The project was very hands-on and involved playing with lasers and crystals. This new type of BPM might someday be installed in the LHC so it was exciting to be involved with its development.

Find our more about my research here and here.


My laboratory set-up incorporating lasers and birefringent crystals,

The social life

Bringing together 300 students inevitably leads to an active social scene. There was lots going on including parties on site, trekking in the mountains, trips to nearby Swiss towns, dance classes, and music festivals. Geneva also provided enough entertainment, cheese and wine to keep most amused, satiated and merry. My favourite activity was having a swim in Lake Geneva.

More on the social scene at CERN here and here.

What did I learn?

I learned a lot at CERN. One of the most striking features of modern physics is that we are still largely in the dark – literally. The matter which everything we can see, including ourselves, is composed of makes up a mere 4% of the universe. The rest is dark matter and dark energy. Supersymmetry holds some promise for a deeper understanding of dark matter but as far as dark energy – which accounts for 73% of the universe – is concerned, we haven’t got the foggiest. It is this kind of mystery which I think makes science so alluring.

I also learned that there are exciting times ahead for physics. CERN is mostly closed for business at the moment as its accelerators are being upgraded but when the LHC is switched back on in 2015, it is going to reach incredible collision energies approaching 7 TeV. Higher energies means different kinds of stuff might fly out of the particle collisions. So the observation of the Higgs boson may be just the tip of the iceberg of a whole new generation of fundamental particles and physics.

The gargantuan detector, CMS.

The gargantuan detector, CMS. This 12,500 tonne beast is located 80 metres underground at a point where particles collide in the LHC. It may be instrumental in discovering new physics.

Will I go back?

I had a fantastic time at CERN and would love to return one day… if they’ll have me.


The Humble Scientist

Tuesday, October 22nd, 2013
Peter Higgs at a press conference at Edinburgh University on 11 October 2013.

Peter Higgs at a press conference at Edinburgh University on 11 October 2013.

As the dust settles following the announcement of the winners of the 2013 Nobel prize for physics, it is worth pausing for a moment to contemplate the man who – reluctantly – gave his name to a boson.

On 8 October 2013, at around 10am GMT, the Nobel committee concluded its deliberations, identified this year’s laureates, and made a few phone calls. In an apartment in Edinburgh a telephone rang, and rang…

Peter Higgs was in a little pub in Leith, a beautiful area to the north of Edinburgh, enjoying a nice bowl of soup, some fish and a pint. It was only when he returned to Edinburgh that an old neighbour congratulated him on the ‘good news’. He replied, “oh, what news?”. On being informed that he had been awarded science’s highest honour, the 84 year-old Emeritus professor resignedly trudged back to his apartment – and its ringing telephone.

Higgs was born in Newcastle in 1925, the son of an Englishman and Scotswoman. He was home-schooled in his early years then, when his family relocated to Bristol, he attended Cotham Grammar School where he was a prize-winning pupil – but not in physics. It was only when he read the works of Paul Dirac, an old boy of his school, that physics really captured his imagination. Higgs went on to be awarded first class honours in undergraduate physics at Kings College London before completing a Masters and PhD in molecular physics. In 1960 he took up a permanent lecture post in Edinburgh.

The Highland air clearly agreed with Higgs, for it was during his walks in Scotland’s rugged mountain ranges that he is said to have conceived a theory of how certain fundamental particles acquire mass. In October 1964 he submitted two papers to the journal Physics Letters, the second of which related to this theory and what is now known as the Higgs field. The first paper was published but the second was rejected and stated to have “no obvious relevance to physics”. On reviewing the paper, Yoichiro Nambu, a respected physicist of the time, suggested Higgs may like to explain the physical implications of his theory. So Higgs inserted a paragraph explaining that the excitation of the Higgs field would yield a particle, which would come to be known as the Higgs boson. Higgs resubmitted the amended paper to rival journal Physical Review Letters, which published it later in 1964.

Around the same time other theorists were working on similar ideas. Belgium’s Robert Brout and Francois Englert published a paper prior to Higgs in 1964 and, although their paper didn’t explicitly refer to the boson, it was the first to propose the mechanism now known as the Brout-Englert-Higgs mechanism.  Another trio of scientists, Kibble, Guralnik and Hagen, also helped to refine the theory behind this mechanism, which is now a keystone of the Standard Model.

Higgs went on to enjoy a successful career in physics, be appointed to various distinguished posts, and win many awards. It was however his work on the Brout-Englert-Higgs mechanism which remains his most notable contribution to the field.

On attending a conference in Sicily in early July 2012, Higgs was tipped off by CERN veteran John Ellis that the observation of the Higgs boson may be announced at a seminar planned for the 4th July at CERN, Geneva. Once he and his travel companion, Alan Walker, were satisfied they had sufficient clean underpants between them to extend their trip, they changed their flights. The observation of the Higgs boson was indeed announced and both Higgs and Englert, who had never previously met, were present. Higgs shed a tear of joy following the announcement and on being asked why he was so moved, he stated that it was people’s reaction to the news and how much it meant to them that so profoundly affected him. On the plane back to Edinburgh he celebrated with a bottle of London pride – a working-man’s ale.

Back to 2013, and Higgs must endure the media storm which inevitably follows a Nobel laureate to be. He will patiently give interviews and press conferences but one strongly suspects that he would prefer to be back in Leith having a pint. What I so admire about Higgs, other than his obvious scientific brilliance, is what an understated and humble man he is. Where some seem to ravenously crave a Nobel, one suspects Higgs would prefer not to have to bother with the accompanying kerfuffle. Indeed Higgs rejected a knighthood as he did not want “that sort of title”. He has been at pains to emphasise the contributions of the five other original authors of the Brout-Englert-Higgs mechanism, and the thousands of other scientists at CERN and beyond involved with the observation of the Higgs boson. He belittles his contribution to science as compared to the likes of Einstein as it only took “two or three weeks in 1964” to concoct. And to top it all he is just about the only person who refers to the Higgs boson as the ‘scalar boson’. In today’s highly competitive, often cut-throat, social media driven society, his dignified, gentle and modest character is wonderfully refreshing.

Higgs plans to retire from his busy lecture schedule when he hits the ripe age of 85. He leaves behind a world of science full of uncertainty. The Higgs boson looks awfully like the Standard Model Higgs boson but is it a supersymmetrical Higgs boson? Are there other types of Higgs boson waiting to be discovered when the Large Hadron Collider is switched back on in 2015? And what about dark matter and dark energy – what on Earth are they all about?

One thing is certain however – they don’t make ’em like Peter Higgs anymore.


The Patient Laureates

Tuesday, October 8th, 2013
Professors Englert (right) and Higgs - 2013 Physics Nobel Laureates.

Professors Englert (left) and Higgs – 2013 Physics Nobel Laureates.

This morning Professors Peter Higgs and Francois Englert were awarded the Nobel Prize for Physics for their predictions, made in 1964, of a mechanism which explains how certain fundamental particles such as quarks and electrons acquire mass. The mechanism is a key constituent of the Standard Model, our best model for explaining the interaction of fundamental particles. The award crowns a pair of remarkable careers and concludes a gloriously romantic story.

Francois Englert spoke directly to the press following the announcement and declared that he was “extraordinarily happy to have the recognition of this extraordinary award”. He intends to congratulate Peter Higgs on the “very important and excellent work” which he completed during the 1960s.

Here are some of the key milestones on the long and remarkable journey of these two Nobel laureates.

A fortunate rejection

In August 1964, Robert Brout and Francois Englert of the Free University of Brussels published a landmark paper which detailed the mechanism by which elementary particles such as quarks and electrons acquire mass. At around the same time, Peter Higgs of Edinburgh University submitted two papers on what is now known as the Higgs field to the journal Physics Letters. The second of those papers was rejected – and a good thing it was too. Respected physicist, Yoichiro Nambu, who reviewed Higgs’ paper suggested that he may wish to elaborate on his theory’s physical implications. In response, Higgs added a paragraph which said that an excitation of the Higgs field would yield a new particle. This particle came to be known as the Higgs boson.

Higgs resubmitted the paper to an opposition journal, Physical Review Letters, which published it later in October 1964.

A rather youthful Peter Higgs in 1954.

A rather youthful Peter Higgs in 1954.

Accurate predictions but no cigar

In the mid 1990’s the Higgs was back in the public eye. Although it had not yet been observed, it had enabled the Standard Model to make a number of successful predictions, including the discovery of the top quark at 176 GeV made by Fermilab’s Tevatron.

Experiments at Fermilab’s Tevatron and CERN’s Large Electron Positron (LEP) Collider had concluded that the Higgs must exist above 117 GeV, but neither was sensitive enough to probe at these energy levels. Enter the mammoth Large Hadron Collider (LHC) into the fray in 2008.  This beastly circular accelerator, with a circumference of 27 km and phenomenally powerful electromagnets, promised collision energies approaching 14 TeV. So the observation of the Higgs boson was considered, surely, imminent – until the LHC blew up after nine days of operation and was closed down for more than a year of repairs.

Patience Professors, patience…

Hello Higgsy

On 4 July 2012 science’s worst kept secret was publicly announced at CERN, Geneva. Spokespersons of the ATLAS and CMS detectors announced that they had observed a ‘Higgs-like particle’ at 126 GeV and CERN’s Director General, Rolfe-Dieter Heur, declared – “I think we have it”. Peter Higgs sat in the room and shed a tear of joy. He also met a chap called Francois Englert for the first time that day.

And the winner is…



So it took almost 50 years, a $10 billion machine and the input of thousands upon thousands of scientists, engineers and mathematicians, but technology caught up with theory and proved Francois Englert and Peter Higgs right. There may be some grumblings that the observation of the Higgs boson also deserved the recognition of the Nobel Committee, but I think no one would begrudge these two extraordinary men science’s ultimate accolade. It has certainly been a long time coming.

Well done chaps – you thoroughly deserve it!


Nobel Rivals

Monday, October 7th, 2013

In less than 24 hours the 2013 Nobel Prize for Physics will be announced and there seems to be one word on everyone’s lips… Higgs. The scientific community appears to hope en masse that Peter Higgs and Francois Englert collect a Nobel for their prediction of the Brout-Englert-Higgs mechanism, the mechanism by which elementary particles such as quarks and electrons acquire mass. There is however competition. Here are some of the other front-runners:

Iron-based superconductors - Hideo Hosono

Superconducting materials have zero electrical resistance when cooled below a critical temperature – a very useful property as it allows for the highly efficient transfer of electrical signals. Today’s most efficient superconductors incorporate a layer of superconducting copper oxide which must be cooled to very low temperatures to operate. For example, in the Large Hadron Collider (LHC) the operating temperature of the superconducting electromagnets, which are used to steer the beam of particles around the accelerator, is retained at around -271°C. The highest temperature at which today’s superconductors can operate is around -140°C, which is still fairly chilly.

A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. (Image by Mai-Linh Doan.)

A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. (Image by Mai-Linh Doan.)

The possibility of an iron-based superconductor, which could in theory have a much higher critical temperature, had previously been dismissed as it was assumed that the large magnetic moment of iron prevented the emergence of pairs of electrons known as ‘Cooper pairs’, which are required for superconductivity in conventional superconductors. However, in 2008 Hideo Hoson of the Tokyo Institute of Technology accidentally stumbled across the first iron-based layered superconductor. Iron-based devices may hold the key to the holy grail of superconductivity – room temperature superconductors – which would certainly make running the LHC at bit cheaper!

Discovery of extrasolar planets - Geoffrey Marcy, Michel Mayor and Didier Queloz 

In 1995 Michael Mayor and Didier Queloz of the University of Geneva announced the discovery of a massive exoplanet in orbit around the star 51 Pegasi, and they used a sneaky technique know as the radial velocity method to find it. The gravitational field of the orbiting planet causes 51 Pegasi to ‘wobble’ in its own small orbit. Using the Doppler effect, Mayor and Queloz were able to measure the variations in the radial velocity of 51 Pegasi, that is the speed at which the star was moving towards and away from Earth in its orbit, to infer the existence of a massive exoplanet. Clever!

Geoffrey Marcy of the University of California has discovered more exoplanets than anybody else, including 70 out of the first 100 identified. Indeed he was the first to verify the existence of Mayor and Queloz’s exoplanet around 51 Pegasi. He has also discovered the first transiting planet around another star, the first extrasolar planet beyond 5 AU, the first Neptune-sized exoplanets, and the first multiple planet system around a star similar to the Sun. He is the quintessential planet-hunter.

An artist's impression of an exoplanet.

An artist’s impression of an exoplanet.

And the winner is…

So tomorrow’s announcement is not a foregone conclusion. Profs Englert and Higgs, and any others hoping to be awarded a Higgs-related Nobel prize, have some stiff competition. Exoplanets have provided some of the buzziest science headlines in recent years, while iron-based superconductors could have hugely significant practical applications, including in particle physics.

However, one senses that it is perhaps the right time for science’s ultimate accolade to be awarded for the prediction and/or observation of the Higgs, which has undoubtedly been one of the most significant discoveries in science in the past century. And with Profs Englert and Higgs in their 80s and Nobels not awarded posthumously (which is why Robert Brout, who collaborated with Englert and died in 2011, cannot be awarded the prize), one suspects that the Nobel committee is somewhat feeling the pressure.

Stay tuned to Quantum Diaries tomorrow where we’ll be blogging live to keep you informed of the latest developments in the run-up to and following the prize announcements. I will also be doing a bit of tweeting @JimmyDocco. And there is already an excellent blog post up in anticipation of the big announcement here.


A summer at CERN in pictures

Tuesday, September 17th, 2013

They say a picture says a thousand words – so here is my story of a summer at CERN in 12,000 words.


Welcome to CERN baby! – this year’s crop of summer students gather in front of the Globe for a group photo (first to spot me gets a postcard!)


It was beautiful summer which, with CERN located in the midst of agricultural estates, afforded itself to some very colourful walks.

The sun was shining and the weather sweet – the summer held much promise. And with CERN located in the midst of agricultural estates, there were a few nice strolls to be enjoyed too.


A cross section of the LHC.

We got acquainted with the stars of CERN – a cross section of the Large Hadron Collider (LHC). Notice the two beam pipes through which particles circulate around the 27 km circular accelerator in different directions.


The gargantuan detector, CMS.

And its giants – the gargantuan particle detector, CMS. This 12,500 tonne beasty is located 80 metres underground at a point where the beams of the LHC cross and particles collide.



The weekends afforded a fine opportunity to soak up some Swiss culture – here a group of Swiss horn players in Gruyère.


CERN's old rubbish - on a quite Saturday morning stroll around the Meyrin site I stubbled across this - an old decommissioned detector.

Or to take a quiet Saturday morning stroll around CERN, where you never know what you’ll find – I stubbled across this old decommissioned detector.


The final project

Now there was of course some work to be done – my experiment coupling a laser into optical fibres and through a birefringent crystal.


While most of came to learn about the laws of Physics, some wanted to defy them - Filip levitating.

And while most of us came to learn about the laws of Physics, some sought to defy them – Filip levitating.


The Antimatter Decelerator - which is used to make and store antimatter at CERN - is described my Michael "Antimatter" Doser himself.

But we did learn about the stranger goings-on at CERN – Michael “Antimatter” Doser himself explains the workings of the Antimatter Decelerator, which is used in the production of antimatter.


A reveller caught in the spotlight at the outdoor film.

There was plenty of time for a few nights at the movies – a reveller caught in the spotlight at the outdoor film at Perle du Lac, Geneva.


Cian and Donal of the Emigrants jamming in Charly O'Neils.

And a few more down the pub – Cian and Donal of the Emigrants jamming in Charly O’Neills.


We had arrived to work at...

All in all, it was a rather memorable summer at…


Three months in a dark room – only for the LHC

Sunday, September 8th, 2013

I have spent much of the past three months in a dark room as my research at CERN has involved using lasers to develop a new type of beam position monitor (BPM) for the Large Hadron Collider (LHC). From a technological perspective, this is seriously cool.

What is a beam position monitor?

To thread a beam of particles through a narrow accelerator beam pipe and around various obstacles you need to control and steer the beam using magnets. This is important for two key reasons: firstly, you want your beam to accurately hit its intended target; and, secondly, if you loose beam aperture in high energy accelerators, stray particles will damage your machine – and you don’t want to damage a $10 billion machine such as the LHC.

You can only control what you can measure and so BPMs are of fundamental importance in the operation of particle accelerators.

The current generation of BPMs are mostly electromagnetic in their operation. They use metal strips, known as striplines,  which line the inside of the beam pipe, to measure beam position. A beam of charged particles has an electric field which causes the striplines to become charged – so the striplines essentially act as electrodes. The closer the beam gets to a particular stripline, the larger the charge build-up on that stripline. So by measuring the voltage which builds up across the striplines, one can calculate the position of the beam.

Grand – so we’re sorted for BPMs then? Not quite…

Intra-bunch head-tail instabilities

Yikes, what are those?

Beams are made up of many discrete bunches of particles. Those bunches have beginnings and ends, known as heads and tails. Sometimes the heads and tails vibrate, resonate or even swap position. Such so-called ‘head-tail instabilities’ lead to beam instability and hence accelerator operators need to monitor such phenomena very carefully.


Plots of intra-bunch head-tail instabilities in the PS in 1974 as recorded on an oscilloscope (courtesy of J. Gareyte, “Head-Tail Type Instabilities in the PS and Booster”, CERN, 1974).

The plots above show such intra-bunch head-tail instabilities observed in CERN’s Proton Synchrotron (PS) in 1974. Note that the time period over which each plot is recorded is 200 nanoseconds (ns), meaning the bunches were approximately 120 ns in length. The problem is that today bunches are hundreds to thousands times shorter than that – so accelerator operators require BPMs of much wider bandwidth to monitor these kind of instabilities.

A new type of BPM…?

I’ve been working on a new type of BPM which uses birefringent crystals to monitor beam position and that, in theory, should have wide enough bandwidth to observe intra-bunch head-tail instabilities in the LHC. To understand how it works we need to understand birefringence…

When light enters a birefringent crystal it is polarised in two different planes – lets say horizontal and vertical. Now each of those planes has a different refractive index due to the structure of the crystal. So the light in the horizontal plane travels at a different speed to the light in vertical plane. This causes light to rotate or twist as it travels through the crystal. The refractive indexes in the crystal change in the presence of an electric field, and this is known as Pockels effect.

An electro-optical (EO) BPM

We can use the birefringent nature of the crystals, combined with the Pockels effect, to monitor the position of a particle beam. As we know, the beam is made up of charged particles and therefore has an electric field. So if you put a birefringent crystal next to the beam, and the beam then changes position, the refractive index of the crystal changes. If we can measure this change of refractive index then we can calculate the position of the beam.

To do this you fire a laser  through the crystal and use a light sensor to detect the intensity of the laser after it exits the crystal. By cleverly placing and orientating a polariser before the crystal (to linearly polarise the light entering the crystal) and then another polariser (known as an analyser) after the crystal, you can block all the light leaving the crystal – so the detector reads zero. This is analogous to rotating a pair of 3D glasses as shown below.


Two pairs of 3D glasses with linearly polarised lenses. When the planes of polarisation are parallel, linearly polarised light emerges from the lenses.


The same 3D glasses but now with the planes of polarisation perpendicular to each other. The first lens polarises light in the horizontal plane and the second polarises light in the vertical plane.  The result – light is extinguished.

So when the beam is in its optimal position, you ideally wish to be getting a zero reading on your light detector.

Then, when the beam strays from the optimal position, the refractive index of the birefringent crystal changes, causing the light passing through the crystal to rotate to a different degree.  The analyser (which is calibrated to extinguish light emerging from the crystal when the beam is in its optimal position) no longer blocks all of the laser – so you get a reading on your light detector which you can use to calculate the beam position. Easy-peasy!

The advantages of the EO BPM

Birefringent crystals are really sensitive to changes in electric field. So if we can measure changes to the refractive index we can very accurately calculate the position of the beam. Moreover, the laser in the BPM will be coupled into optical fibres and so the signal will not suffer the same levels of attenuation as those carried through the electrical cables of electromagnetic BPMs. We can therefore monitor the position of the beam at much higher bandwidths, as required.

Due to the efficiency of optical fibres in transmitting signals, the crystal may be placed hundreds of meters underground in the accelerator tunnel, while more complicated equipment (including the light detector) can be placed on the surface – where operators may calibrate and control the BPM – without any significant loss of signal bandwidth. The crystals are also tiny so may fit where other BPMs can’t reach.


My experimental set-up in the lab – the laser is coupled into the optical fibre using mirrors. It then travels through the optical fibre, is polarised by the system of paddles in the foreground, before emerging from the fibre. The laser beam then passes through the analyser before hitting the light detector.

When will it be in operation?

The EO BPM is still under R&D but we hope to have a prototype ready to test in the Super Proton Synchrotron at the end of Long Shutdown 1 (LS1) in mid-2014. So, the EO BPM is in the pipeline, or at least it will be soon…

The EO BPM is the brainchild of Ralph Steinhagen.


Girls, at CERN – loads of ’em!

Sunday, August 25th, 2013

My pal got chatting to a drunk fella in a bar in Oxford a few weeks before he started a new job at CERN. When he mentioned the identity of his future employer, the drunk fella guffawed with a “well you’re not going to find a girlfriend over there!”.

Now, either this intoxicated chap was implying that my pal is inherently unattractive to particle physicists (which seems unlikely as he’s a very handsome man) or he was insinuating that there aren’t too many ladies at CERN. I think it was more likely the latter and to that my response would be – not so!

I’m not sure of the exact figures but from a cursory glance around the lecture theatre there seems to be a roughly equal number of girls and boys on the CERN Student Summer Programme this year. Moreover, a significant proportion of our lecturers are female, with Daniela Bortoletto, Tara Shears and Magdalena Kowalska proving to be fantastic communicators as well as scientists.

Females are prominent and very visible at CERN. For example, the observation of the Higgs, one of the most important discoveries in modern science, was partly announced by Fabiola Gianotti as spokesperson of the ATLAS detector.

Fabiola Gianotti appears on the cover of Time magazine.

Fabiola Gianotti appears in Time magazine.

Now, that’s not to ignore the reality that the ratio of sexes at CERN more generally is still tipped in favour of males but, nevertheless, particle physics isn’t solely a man’s world. A CERN website specifically states that:

“CERN hopes to… send a clear message to all young women interested in particle physics and high technology that they are welcome in the field as physicists, engineers and computer scientists… Particle physics is a field where women play an active role at the forefront of experimental research.”

CERN even has an official and very active Women’s Club to provide an additional support network for females working at CERN. 

So, if you are female and hoping to break into particle physics, the opportunities, support structures and role models are there for you to get your foot in the door and progress to the pinnacle of your field.  So no excuses – get the application in…


Contrary to the predictions of an inebriated man in an Oxford drinking establishment, my pal is now dating a very lovely female particle physicist. So ha!