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!