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Tag archives: neutrinos

How to win a Nobel prize

By Hamish Johnston

Takaaki Kajita

Eureka moment: Takaaki Kajita’s Nobel journey began when he was improving software. (Courtesy: Takaaki Kajita)

This morning I had the pleasure of speaking with Takaaki Kajita, who shared this year’s Nobel Prize for Physics. He won for discovering that some of the muon neutrinos produced by cosmic-ray collisions in the atmosphere change flavour as they travel to Earth. This phenomenon, called neutrino oscillation, tells us that neutrinos have mass – something that was not initially included in the Standard Model of particle physics.

From his office at the University of Tokyo, Kajita told me that the story began in 1986 when he was working on a proton-decay experiment at the Kamioka underground lab in Japan. He was trying to improve some software that was designed to discriminate between electrons and muons created within the detector. He noticed that there were fewer events associated with muon neutrinos than expected. Muon neutrinos are created in the atmosphere when cosmic rays collide with air molecules and a possible explanation for the deficit was that some of the muon neutrinos were oscillating into electron neutrinos on their journey to the detector. Looking back, however, Kajita told me that his initial reaction to the deficit was that he must have made a mistake in his analysis.


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Juggling Newton’s cradles, physics poetry, the birth of exoplanetary research and more


By Tushna Commissariat

We get many exciting, interesting and sometimes strange e-mails in our Physics World inbox on a weekly basis. But we were pleasantly surprised to receive one from Jay Gilligan – a professor of juggling at the University of Dance and Circus in Stockholm, Sweden. Together with one of his former students, Erik Åberg, he has perfected the art of juggling with giant Newton’s cradles. While juggling undoubtedly involves a lot of physics – everything from air resistance, speed, velocity and of course gravity comes into play – this takes it to an even more physical, if you will excuse the pun, level. Do watch the video above to see all of the amazing tricks that the duo can do, and try them for yourself if you are dexterous enough.


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Weighing up the options for neutrino mass


By Tushna Commissariat

As I am sure all of you know, the 2015 Nobel Prize for Physics was awarded yesterday to Arthur McDonald and Takaaki Kajita “for the discovery of neutrino oscillations, which shows that neutrinos have mass”. Following on from yesterday’s neutrino-flavoured excitement, here’s an explanation of why it’s so important that we better understand neutrino mass.

Our current observations and theories of neutrino oscillations suggest that at least two of the currently known three flavours of neutrinos have non-zero mass. While we know the mass differences between the different neutrino flavours accurately, their actual masses have not been measured. It’s not for lack of trying, it has simply proven very difficult to make the measurements.


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Busting dust deep underground in SNOLAB

SNOLAB's Nigel Smith (left), Ian Lawson (centre) and Chris Jillings

Squeaky clean: SNOLAB’s Nigel Smith (left), Ian Lawson (centre) and Chris Jillings.

By Hamish Johnston at the CAP Congress in Edmonton, Alberta

I’m a bit of a DIY enthusiast and one thing that I know about drilling into a masonry wall is that you should hold a vacuum-cleaner hose to the hole or you will end up with dust all over the wall and the floor below. Believe it or not, that is exactly what workers at SNOLAB in Canada do in order to keep background levels of radiation from affecting their dark-matter and neutrino detectors.


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Space-station toilet tour, the Louvre’s particle accelerator and more


By Tushna Commissariat

I’m sure that many of us, while watching videos of astronauts on board the International Space Station (ISS), floating around with their halo-like hair, have given much thought to how they shower, wash their hair, brush their teeth and, indeed, poop and pee! Well, you can stop stretching your imagination and take a look for yourself – we spotted this story on the Slate website, where you can see the latest videos from the European Space agency, where Italian astronaut Samantha Cristoforetti, who is currently on the ISS, gives us a tour of both the toilet (above) and the “shower” area (below). She even demonstrates exactly how to wash your hair in space – it looks rather fuss-free if you ask me!


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Sweet-talking physics

By Louise Mayor

We’re always up for trying new formats and approaches to journalism here at Physics World. You’ve probably seen our documentary-type films, podcasts and 100 Second Science video series, but the latest addition to our repertoire is a short monthly video in which one of our editorial team highlights something in the upcoming or current issue as a kind of taster.

So this month, I decided to take the plunge and get in front of the camera myself to present the third edition of what we have started jokingly referring to in the office as our “fireside chats”. (Here are the July and August versions.)


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Pointless or profound?

By Matin Durrani

Cover of Physics World September 2014 issueThe cover feature of the September 2014 issue of Physics World, which is out now in print and digital formats, concerns “sterile neutrinos” – a hypothesized fourth kind of neutrino in addition to the familiar electron, muon and tau neutrinos. Sterile neutrinos are controversial – they have never been detected and we are not even sure if they exist at all. But if they do, sterile neutrinos could potentially solve a raft of unsolved problems in physics, including why neutrinos themselves have mass, what makes up dark matter and why there is so much more matter than antimater in the universe.

In the article, you can find out more about the mysteries these hypothetical particles could solve. But since they might not exist, why – you may wonder – would anyone bother looking for them? In other words, is the search for sterile neutrinos pointless or profound? Check out the September issue to find out more.


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Winning rock-paper-scissors, meeting a future Nobel laureate, hot new batteries and more

By Hamish Johnston

Donald Sadoway wants us to think differently about batteries

Donald Sadoway wants us to think differently about batteries. (Courtesy: MIT/M Scott Brauer)

When I was a PhD student, there was a group of retired professors that shared a tiny office in the physics department. It was whispered that one of them was extremely wealthy thanks to a successful commercial spin-out and we marvelled at the fact that he came in to work every day rather than enjoying the fruits of his labours. However, it wasn’t the wealthy professor who was destined for international fame. In 1994 his officemate Bertram Brockhouse shared the Nobel Prize for Physics, and Brockhouse’s quiet life changed dramatically. Indeed, he got his own office!

I was reminded of this little group when I read ZapperZ’s blog entry about his encounter with Ray Davis before Davis bagged the 2002 Nobel for his work on neutrinos. Sitting next to Davis on a two-hour flight, ZapperZ had an inkling that he was beside an interesting character after their brief chat about physics. But it wasn’t until the Nobel was announced several years later that he realized the opportunity he had missed.


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Are ‘sterile neutrinos’ dark-matter particles after all?

Graph showing recent constrains on sterile neutrino production

Could sterile neutrinos constitute dark matter? (Courtesy: Bubul et al./ arXiv:1402.2301)


By Tushna Commissariat

It is always interesting to us at Physics World when a particular topic suddenly attracts the attentions of the physics community, especially when it’s a rather hotly debated subject. The past couple of days, for example, have seen a lot of talk about “sterile neutrinos”, based on two papers – published in quick succession on the arXiv preprint server – that suggest the tentative detection of these hypothetical paricles.

Both papers are based on an unidentified emission line seen in the X-ray spectrum of some galaxy clusters obtained by the European Space Agency’s XMM-Newton observatory. Intriguingly, sterile neutrinos are also considered to be possible dark-matter candidates, meaning that – if discovered – they would be the first fundamental particles to lie beyond the bounds of the Standard Model of particle physics.


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Particle art lights up Victorian ice well

By James Dacey

Photograph of art installation Covariance

Covariance includes 28,000 glass beads and 36,000 diamantés. (Courtesy: Richard Davies)

“The finished work is everything I had hoped for and more – it takes my breath away!”

That was the reaction of artist Lyndall Phelps upon seeing her physics-inspired installation in London, which will open to the public this Saturday. Entitled Covariance, the work was inspired by the SuperKamiokande neutrino observatory in Japan – reflecting the machinery of particle detectors and the way in which particle physicists visualize their data. The kaleidoscopic artwork is housed in a Victorian ice well beneath the London Canal Museum, in reference to the subterranean location of many large particle-physics experiments.

Phelps is an artist who often creates works inspired by science, where she looks in particular for the personal and emotive themes that can exist within academia. For this latest project, she worked in collaboration with Ben Still, a particle physicist from Queen Mary, University of London. The pair was commissioned to work on the project by the Institute of Physics (IOP) as the first in a programme of artists-in-residence called Superposition.


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