Showing posts with label nobel prize. Show all posts
Showing posts with label nobel prize. Show all posts

09 November 2015

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.









09 October 2008

Elephant in the room for the Nobel Prize in Physics!


On Tuesday it was announced that Makoto Kobayashi and Toshihide Maskawa have been awarded the Nobel Prize in Physics for 2008. The award is "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature." They share the prize with Yoichiro Nambu for his work on spontaneous symmetry breaking, a process vital to the derivation of the Higgs mechanism which gives particles mass in the standard model and which, as has been well publicised, is major part of the physics to be investigated with the LHC.

The work of Kobayashi and Maskawa concerns a slightly more obscure asymmetry in nature, so called CP violation. Essentially CP asymmetry reveals a subtle difference between the weak nuclear decays of some particles and their corresponding anti-particles and forms a cornerstone in the investigation of why the universe is made of matter and not anti-matter. It was first observed experimentally in the 1960s and at the time posed a theoretical conundrum. Kobayashi and Maskawa showed in the early 1970s that this effect could be incorporated into the standard model if there are at least 3 generations of quarks. This effectively predicted the yet to be discovered top and bottom quarks. Their work built on the flavour mixing formalism developed by the Italian Nicola Cabibbo and resulted in the so called CKM (Cabibbo-Kobayashi-Maskawa) matrix.


The ultimate test of the CKM matrix came this decade with the operation of the B Factories; BELLE in Japan and BaBar in the USA. These experiments produce pairs of B mesons (particle and anti-particle) and study their decays looking for the effects of CP violation predicted by Kobayashi and Maskawa. In 2001 both collaborations reported the first experimental observations of CP violation from B meson decays, completely in agreement with the CKM matrix formalism. They have since made scores of similar measurements all consistent with the model. Imperial College has been heavily involved with the BaBar experiment (named after the eponymous cartoon elephant who is also the experiment mascot) for the duration of it's running, which was completed earlier this year. We continue to work as part of the collaboration who are now analysing the final data set. Currently the Imperial group are looking at the effects of radiative penguin decays which can further constrain the elements of the CKM matrix.

It is the success of the CKM mechanism under intense experimental scrutiny which has made Kobayashi and Maskawa deserving winners of the 2008 Nobel Prize in physics.