A Neutrino Buzz in the Air

Today is a special day for those who have been working in the area of neutrino oscillations.

We were still celebrating the recent awarding of the Nobel Prize to Drs Art McDonald and Takaaki Kajita, who are leaders of the SNO and Super-K experiments respectively—it is a fantastic feeling to know that colleagues in the area of physics we study have been recognised in one of the most visible ways possible.

But a different award was announced today—or rather on the evening of Sunday 8th November in California where a flashy presentation ceremony was held, with Seth Macfarlane as the host—the 2016 Breakthrough Prize in Fundamental Physics.

From the official announcement page:

The 2016 Breakthrough Prize in Fundamental Physics to be Awarded to Seven Leaders and 1370 Members of Five Experiments Investigating Neutrino Oscillation: Daya Bay (China); KamLAND (Japan); K2K / T2K (Japan); Sudbury Neutrino Observatory (Canada); and Super-Kamiokande (Japan)"

The Nobel Prize is famously awarded to up to only three individuals per prize, and there is always much discussion before and after as to who ought to receive the prize, and, inevitably, who missed out unfairly. There is usually no controversy about whether the actual recipients deserved their prizes, but there are cases where many of us feel that it would have been fairer to relax the three-winner requirement a little, a constraint that was only officially introduced in the late 1960s.

One of the many differences between the Nobel Prize and the Breakthrough Prize is that the latter not only allows more than three people to win the prize, but that it acknowledges the important role that collaborative work plays in modern science. Therefore, the $3M prize goes not just to the top few leaders of an experiment (although such leaders are also recognised explicitly; with seven physicists in this year's case being honoured his way), but is shared by all those who worked together to produce the seminal journal papers in which these experiments reported their findings.

At Imperial, we are delighted that many past and present HEP group members are laureates for the T2K experiment, and as it happens I also receive the prize for my work with KamLAND when at Stanford University.

In our field, collaborations can be all-consuming parts of our lives; in the early days of T2K, I vividly remember my colleagues working day and night, week after week, to help design the detectors we would be building, and long hours spent in the lab, testing and assembling detector components; we would discuss and argue over and over again about how best to do things, and toiled to make sure that the fruits of our work in 2005 would still be worthwhile in 2015 (and now, we are hoping they will continue to be useful in 2025).

Collaborations can continue working together for many years, with individuals receiving their PhDs, becoming postdocs and obtaining academic positions, and generally growing old together, all while pursuing the same common goal—to make their experiment successful. Of course many people will move on to different things, be they jobs in industry or work at other experiments (and in new collaborations), but I think the bond between people who have worked on these experiments together during the most intense times is quite unique and long-lasting.

Today I received an email that was sent out to the roughly 100 prize recipients of the KamLAND Collaboration who worked on the papers from early 2000s where we demonstrated that neutrinos actually oscillate, rather than disappearing in other ways. The list of names on its own brings back memories to me of stressful, but also exhilarating, days and nights spent deep in a mine—in fact all of the experiments which received the prize today involve some kind of underground part to their set-ups—trying to get the experiment to perform as well as it needed to, and arguing over how to analyse the data. Yes, we do spend a lot of time arguing with each other!

Super-K and SNO, whose leaders received the Nobel Prize, showed definitively how neutrinos change identity as the travel; but one needs to put together the discoveries made by all five experiments which won the Breakthrough Prize to form the current picture that we have of neutrino oscillations, and it is an interesting distinction that has been made by the respective prize committees.

All the buzz that surrounds our field is made even more exciting by the fact that the discoveries we have made point to more possible progress in the next several years, and here at Imperial we are working on the future Hyper-K and LBNF/DUNE experiments as well as other neutrino projects, all as part of international collaborations. As proof of this, this month we are hiring three postdoctoral researchers (we are currently going through the selection process) to join the T2K and Hyper-K effort, and we hope that some of the new cohort of PhD students that have just arrived at Imperial will also join us (but that is up to them!).

So while these prizes do help us look back to savour the amazing physics discoveries that we have made in this field over the last couple of decades, it is the future that really excites us—not only in neutrinos, but in all the other areas in which we are building experiments that have the ability to make breakthrough discoveries that tell us more about the universe we live in.

New Discovery from the T2K Experiment (7.5 sigma for Electron Neutrino Appearance)!

It has been pointed out to me that this has become more of a historical record than a blog....

If I were to blame it partly on a former student who has been promising to write an extensive article about his finishing his PhD on T2K and then going on to work on the LUX dark matter experiment in the States, that would be very poor form indeed, so I would not do such a thing!

Anyway, today is a big day for us on the T2K experiment (the photo above is the T2K Imperial group from a couple of years ago), and in particle physics as a whole. The early T2K observation from a couple of years back that muon neutrinos actually oscillate into electron neutrinos has become a fully-significant discovery (and is being presented to the European Physical Society meeting in Stockholm today by our friend and colleague Mike Wilking):

Imperial College Press Release on the new discovery by T2K

While the most obvious change is that the number of electron-neutrino candidate events has gone from 6 to 28, which is because of the longer period of time T2K has been running, and the higher intensity of the beam (plus of course the size of the underlying physics which causes the process), it is just as important that a lot of work has gone into understanding of the beam and the detectors and the ways neutrinos interact, to increase our certainty on the inputs that go into the physics statement that we can make.

That is to say that the likelihood that random fluctuations (which is to say just bad luck) could make us see what we see is less than one in a trillion. We are certain at that level that what we are seeing is the appearance of electron neutrinos in a muon neutrino beam, once they have travelled the 295 km from J-PARC to the Super-K detector! In the plot above, the green shows the electron neutrino candidates we'd expect to see if this new physics didn't happen. So much work goes into working out the size of the green histogram, so that we know that the actual electron neutrino candidates we see (in the black dots with uncertainties shown in the vertical bars) must mostly be caused by new physics, shown in pink.

We will still be able to make this measurement better, providing a high-precision value of the parameters that describe this in our current model of neutrino oscillations. This, combined with measurements made by other experiments of related but different processes, and other measurements by T2K itself, will continue to help us learn if our models do indeed describe the universe well, and what their implications are. That could be the topic of a future blog post—are there any finishing PhD students' who'd like to contribute an extensive article on this?

PS. This is the work of many many people, and here I quote the bit in our press release today that describes this:

The T2K experiment was constructed and is operated by an international collaboration. The current T2K collaboration consists of over 400 physicists from 59 institutions in 11 countries [Canada, France, Germany, Italy, Japan, Poland, Russia, Switzerland, Spain, UK and US]. The experiment is primarily supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). Additional support is provided by the following funding agencies from participating countries: NSERC, NRC and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; Ministry of Science and Higher Education, Poland; RAS, RFBR and the Ministry of Education and Science of the Russian Federation; MICINN and CPAN, Spain; SNSF and SER, Switzerland; STFC, U.K.; DOE, U.S.A.

NEUTRINO2012 in Kyoto

For the last week or so the Higgs has been hitting the headlines, but it's also been an amazing year in the world of neutrinos, and last month, a group of us from Imperial attended the Neutrino 2012 conference in Kyoto, which is where the whole community comes together to report and discuss our work, and think about the future.

This was the 25th in the Neutrino series of conferences, which are held every other year and are the biggest and most prestigious in the field of neutrinos. In 2014 it will be held jointly by Boston University, Harvard, MIT and Tufts, and in 2016 it will be those of us here at Imperial College London who will be hosting*. We have already started making plans for 2016, so this year at Kyoto, my colleagues and I were thinking not just about the physics, but also the logistics of the conference, the good things we encountered, and any issues that we might be able to improve when it is our turn:

Anyway, this year, over 600 physicists participated, making it the best attended Neutrino conference ever, and the physics results from the past two years that were reported are really reshaping our view of the Universe and also how we should perform experiments in the future to learn even more. Here are some pictures of Kyoto as found in slides shown by some of the speakers during the conference:

And finally, one of the most beautiful slides of all:

Well, one last photo that is not quite as pretty:

Overall, it was a fabulous conference, with all sorts of ideas sprouting forward from the community on the sorts of things we can do next to take the next steps forward—many of these will result in new experiments, and many will result in new interpretations for previous and current experiments, including these ones we are working on here at Imperial.
The big question with the Higgs and the LHC is “are we seeing something beyond the Standard Model”, but in neutrinos we've been looking well beyond the Standard Model, and now that we actually know all three mixing angles, it may not be long before we uncover a few more fundamental mysteries of the Universe....
*which is to say the Neutrino conferences from now till then are following me round the world!

Imperial High Energy Physics Group Open Day

Happy New Year!

We will be holding a Group Visit day on the 19th of January, for anyone who is considering joining our group as a PhD student. If you would like to come and talk to us, please email my colleague, Dr David Colling!

My summer project at Imperial

After spending my last 3 months with this department over the summer, I wanted to share my experience with you via this blog. Either that or I was strongly encouraged by my supervisor Yoshi! I am a 3^rd year undergraduate here at Imperial and I worked in HEP over last summer as part of a UROP (http://www3.imperial.ac.uk/urop) scheme.

Although not as extravagant as other blog entries on this site, with students travelling to Japan and Switzerland, my placement in the Blackett lab was just as enjoyable and rewarding. I was working with Yoshi and Ajit on the COMET experiment. In particular I was using computer simulations to optimise both a collimator and the fantastically named lagger-tagger, a name that Yoshi is still trying hard to get adopted by the particle physics community (hopefully not in vain).

I spent most of my time working with Ajit, who was very helpful, giving me lots of his time and expertise. His crash course in particle physics allowed me, who had not studied the subject yet, to understand enough of what was going on to do my project. I started by getting familiar with some of the tools of the high-energy physicist. First on the list was the hilariously steep learning curve required to use ROOT, and its 20 years worth of quirky workarounds, providing endless fun for the data analyst (I also wonder if the Windows version of ROOT is called Administrator). Second was G4beamline, a brilliant piece of software, with documentation so in depth and confusing that presumably only the person who wrote it can use all of its myriad features with any degree of confidence. Joking aside these are impressive programs, testament to group collaboration over years, and they allowed me to complete my project without much hassle at all.

The next part of my work was at the Daresbury Laboratory, working as part of the team building the detectors for T2K. This was useful as I could see another stage of an experiment, its actual construction, rather than its design. When I received the email telling me that the detector I had worked on had been shipped out to Japan it gave me the feeling that I had provided something real to an huge multinational experiment.

Another enjoyable part of my work over the summer was the opportunity to be a part of a research group, thankfully the High Energy physics group was welcoming and I got on well with all that I met, meeting for lunches and the occasional night out. The experience has convinced me to do a similar project next summer and to apply for a PhD place after my degree.

All in all I had a great time doing my UROP placement here, it was hard work, but very rewarding. Looking around this blog, I have only one regret, that I didn’t take more photos of myself smiling, standing in front of physics equipment.

Thanks to Yoshi and Ajit for their time.

Dave

Super-K Sonic Boooom!

(photograph by Nick Ballon)
Well done Tom indeed, but we on T2K are also mixing it up with non-physicists (and artists), in our case in an artist's rendition of Super-Kamiokande, built under London Bridge Station, complete with accompanying sonic booooums....

Super K Sonic Booooum
Nelly Ben Hayoun, sound by Tim Olden
Wed 4 to Sat 14 8pm
Come on a fantastic voyage on a dingy that floats on 50 000 tonnes of extremely pure water where neutrinos interact with electrons in a massive Sonic Boom…Take part on this risky experiment with unique insights from scientists from Imperial College London and Queen Mary University who works with the Neutrino Observatory Super K and T2K in Japan, as SNO in Canada.

www.nellyben.com

This is in the amazing Shunt Lounge, and will be on Friday 6th and Saturday 7th and again from Wednesday 11th till Saturday 14th.

Everyone is welcome, but you need to be there at 8pm for the full experience!

And not only this, but as you can see from the advert:

Scientific Talks at the Sonic Boooum
Nelly Ben Hayoun
Wed 4 to Sat 14
Nov. 4th Dave Wark
Nov. 5th Ryan Terri
Nov. 6th Yoshi Uchida/Melissa George
Nov. 7th Yoshi Uchida/Melissa George

Nov. 11th Matthew Malek
Nov. 12th Ben Still
Nov. 13th Dave Wark
Nov. 14th Francesca De Lodovico

there's a chill-out zone where you can enter the trance-like state that can envelop you when you experience a... physics seminar. Hmmmm....

Photos forthcoming.

A Happy New Year from Imperial T2K....

A seriously-belated Happy New Year to all avid followers of this blog from around the world!

2009 will be a very big year for many of us at Imperial High Energy Physics, most certainly including me and my colleagues who are working on the T2K Experiment.

I am writing this as the names of some towns such as Petrozavodsk have finally started appearing on the in-flight map after several hours of unmarked Arctic coastline. Being on a certain cash-strapped flag-carrying airline has meant that there was no functional personal entertainment system to distract me from map-gazing and some slightly more fun duties such as marking student reports.

So here we are flying back from a week of meetings at KEK, the Japanese national laboratory for particle physics, where each day was filled with over 12 lovely hours of non-stop sessions of presentations and discussion.

After several years of work, this year our experiment will finally see data from actual neutrinos flying 200 miles across Japan from the village of Tokai on the eastern coast, to Kamioka in the hills in the north-west of the country. Our physicist colleagues at the new accelerator complex of J-PARC are working hard to make sure that we get lots of neutrinos making this journey, because by the very nature of neutrinos, we will only be able to observe a tiny fraction of them in our detectors.

The neutrinos will be made by slamming an extremely intense beam of protons into a long rod of graphite, where "strong" interactions (in the particle physics sense) will produce a huge shower of light particles, which produce neutrinos as by-products as they undergo "weak" interactions while flying down a 100m-long tube. Everything from the source of the protons, to the initial straight accelerator which gets them moving as a beam, the smallish synchrotron ring that raises their energy to 3 GeV, and the mile-long 50 GeV Main Ring which follows, is all brand-new, and over the last year or so, each component has been commissioned and tested, and the protons have gradually crept closer to the dedicated neutrino beam line for T2K.

The picture at the top is the place where the graphite target goes, as of a week or two ago.

The energy of the protons is tiny compared to those in the LHC (a GeV is one-7000th of the LHC energy of 7 TeV), which will also be turning on this year, but the power of the beam is what matters most for us, and will be the highest ever for an accelerator like this, fingers crossed!

With the recent successful commissioning of the Main Ring at 30 GeV, the neutrino beamline is all that is left now, and almost all the components are in place for the superconducting magnets and array of beam monitors to be switched on in a couple of months' time, and protons fired into the graphite target. Eventually, the accelerator complex will try and put as much power into the beam as possible, to make as many neutrinos as we can, but initially it will only be configured to produce a little beam, so that things can be checked out and everyone is certain they are happy that we can start cranking the power up later this year.

The beam is of course not the only critical part of T2K, and many things have to come together for the experiment to work: a host of detectors which make sure the neutrino beam is how we want it to be and is pointing in exactly the right direction; the ND280 "near detectors", 280m away from the target, which we are working on in the UK, and which will look at the neutrino interactions in unprecedented detail so that we can understand the beam properly and correctly interpret what the neutrinos are telling us; Super-Kamiokande, the underground tank with 50,000 tonnes of water that will detect the neutrinos after their trip across the country. There is even an experiment at CERN, called NA61, which putting in time to measure exactly what happens when you fire a proton beam at the T2K graphite target. This is actually very subtle physics that no one is able to calculate with any confidence, and hence measuring this will be a big contribution to T2K.

Each of these parts of the experiment is making very rapid progress, which we confirmed over the course of the past week, and we talked things over to make sure that everything will work well when it all comes together over the next year or so.

For ND280, we are now running tests at Rutherford Lab in Oxfordshire, to make sure that the detectors we are building, called electromagnetic calorimeters, work properly, and also the electronics and data acquisition systems that are UK responsibilities too. These will need to operate reliably with many of the other detector systems being built by our T2K friends around the world, so we have to make sure everything works before it is sent to Japan to be put underground in the ND280 detector cavern.

Of course we don't just build an experiment and switch it on and then wait to see what happens -- it takes a lot of work to figure out how best to use information we see in the detectors, and we need to make sure we know what to do with it beforehand. Much of my work is centred on ensuring that once the experiment is turned on, we know that it is working properly, that we can extract from the data everything we need, and that we can analyse that information and turn it into physics measurements that we can publish. This involves a lot of software work and physics analysis studies, which is the most exciting bit for me. Our 2nd year students gave presentations to the entire collaboration on their work, and personally I thought they did rather well.

On top of all this physics to discuss, there is a host of logistical issues that we also have to sort out, such as when and how we send our detectors, and who with, and how many people we need at J-PARC and when, how many physicists will fit into a cheap flat in Tokai etc....

This meeting at KEK was a target for a lot of the work we have been doing over the last several months, but it wasn't the first set of hardcore meetings this year. In November, I suggested that we have a T2KUK Physics and Software meeting before the start of term in January. Somehow, this idea proved surprisingly popular, and the meeting grew to a full UK collaboration meeting, which our friends at Liverpool kindly hosted.

Sometimes we complain about how we get overloaded by meeting after meeting, but I think these big occasions when we get a large number of people together in the same room, are impossible to do without. It is not just the slide presentations and formal discussions, but the informal chats over coffee that can really help brings ideas together and new things get started.

Once we get back from a meeting like this, it is back to the rather more laborious daily routine of getting things to work, fixing them if they don't, coming up with new things to try, and in general trying to meet deadlines, half of them self-imposed. I hasten to add that a large fraction of the actual contributions come from our students, which is always very rewarding for us as well as the students themselves (I think).

Other things that happened while we were away in Japan include: a lovely sunny afternoon when the weather on my balcony reached 24C; about 7 different types of ramen noodles; a mysterious "frying thing of fish" for lunch at the KEK canteen; lots of "Rilakkumas"; snow at KEK; the party on the Friday night followed by the traditional karaoke which Dave finally came along to; my team losing 4 - 3 in the Cup....

Well, we are over Krakow now, and I think I should take a little nap before we land. Now that everyone who reads this blog is probably all T2K'd out, I'll refrain from writing about our experiment till our next major development -- which may not be too far off!

T2K is Coming Along....

It has been a few years since our group started working on T2K, and as with any experiment, initially there was lots of talking and designing and re-designing, but without very much to show for it all, at least in a form that can be appreciated outside of physics meetings.

But with less than a year to go till we start taking data (which is a scary thought), we now have some photos and videos to prove that T2K construction is right on track!
The picture on the right is something I generated a while ago from the representation of the T2K near detector in the computer simulations that we have been using to design and study it.
The movie shows the magnet coil a week ago, being put inside the red magnet, which has already been placed 20 metres underground in the brand-new detector cavern. All 900 tonnes of the magnet were shipped all the way from CERN just a few months ago. Note the uncanny similarity between the picture and the movie.... The movie is sped up by the way -- the workmen don't actually whizz about like that.
It is a proper experimental hall now, but on the right is how the "cavern" looked when we visited J-PARC 9 months ago in September 2007--barely a scratch on the surface!
The near detector is being built in the ground about 280m from the origin of the neutrino beam that is also undergoing construction, so that we will be able to measure the beam and understand the interaction properties of neutrinos well enough to be able to measure it again at Super-Kamiokande, 295 km away, which is the point of T2K.
The cage-like object rendered in brown in the picture at the top is what we call the "Basket". It sits in the middle of the magnet, and holds up the P0D, FGD, and TPC detectors inside. This was one of the UK responsibilities, and in this picture you can see our colleagues from up North inspecting it when it was finished. Since it goes inside a big magnet, the Basket, and everything else too, needs to be made of non-magnetic materials, and that was one of the things they checked.
I hope it goes without saying that the Basket is not the only thing we are building for T2K in the UK! The Electromagnetic Calorimeter, or ECAL, which the UK is responsible for, is also coming along nicely, as is the neutrino beamline itself. I think I'll save those for another post though....

International Collaborations, Elections, and the Subtleties of Language

An election was just held to decide who would work alongside Koichiro Nishikawa of Kyoto University as the first International Co-Spokesperson for the collaboration of a couple of hundred physicists working on the T2K Experiment.

When Dave Wark, my colleague at Imperial, was nominated as a candidate, I offered him a bit of advice to help him advance his international credentials -- through the words "yoroshiku onegai shimasu" which is what Japanese politicians spew after every other sentence during election campaigns. It roughly translates to, well, er, ...according to one web page:

"I suppose every language has a number of expressions that defy translation into another language. One of the Japanese phrases that belong to this category would be 'Yoroshiku onegai shimasu.'", then going on to say:

"Thus, if I were to be forced to translate the phrase 'Yoroshiku onegai shimasu.' into English, I would say, 'I hope you will take care of ( someone / something ) in a way that is convenient for both you and me. (I count on your cooperation.)'"

Which sounds utterly shameless in this context....

My personal translation, which is what I gave Dave, was that it expresses a desire for "the concept of pursuing goodness, correctness". Beautiful.

I think he might have used the phrase at a meeting or two, though whether anyone actually understood him is unknown.

He didn't listen to my other suggestion that he ought to become the first physicist to launch a spokesperson election campaign on YouTube, however.



But now, the speculation is over. I can sense the tension in the imperialhep.blogspot.com readership.

The results were announced earlier today, and despite not having a YouTube election campaign, it turns out that Dave has been elected by a majority of the vote.

Whether our new International Co-Spokesman will ever visit us on this blog remains to be seen. Dave?