The Nobel Prize in Physics 2015: Takaaki Kajita And Arthur B. McDonald

http://in.reuters.com/article/2015/10/06/nobel-prize-physics-idINKCN0S00ZZ20151006

by sasvari • 11 years ago

161 29 11 years ago

in.reuters.com

bobmichael• 11 years ago

Technical document explaining the scientific background here: http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

Maro• 11 years ago

https://en.wikipedia.org/wiki/Neutrino_oscillation

Neutrino oscillation is a quantum mechanical phenomenon whereby a neutrino created with a specific lepton flavor (electron, muon or tau) can later be measured to have a different flavor. The probability of measuring a particular flavor for a neutrino varies periodically as it propagates through space.

First predicted by Bruno Pontecorvo in 1957,[2] neutrino oscillation has since been observed by a multitude of experiments in several different contexts. Also, it turned out to be the resolution to the long-standing solar neutrino problem.

Neutrino oscillation is of great theoretical and experimental interest, since observation of the phenomenon implies that the neutrino has a non-zero mass, which was not included as part of the original Standard Model of particle physics.

sidcool• 11 years ago

I would love someone to do an ELI5 of their research.

pkrumins2• 11 years ago

They do it themselves as part of receiving the Nobel prize. It's called the Nobel Lecture. I just wrote a comment about it in this thread.

dagw• 11 years ago

Here's the official ELI5 (or ELI12, which is probably what you really want):

http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

edit: and here is the official ELIAPhysicsGradStudent: http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

hugh4• 11 years ago

Feynman was asked by a journalist if he could please explain what he got his Nobel for in terms the average person could understand. He said no, if he could so that it wouldn't be worth a Nobel Prize.

In this case, they got it for discovering neutrino oscillations, which prove that neutrinos have mass. Want to understand why neutrino oscillations imply that neutrinos have mass? Bad luck.

sanxiyn2• 11 years ago

This seems to be awards for two neutrino observatories, Super-Kamiokande and SNO(Sudbury Neutrino Observatory). Note that the Nobel Prize in Physics 2002 was also awarded to neutrino observations.

redmaverick• 11 years ago

Is it fair to give the Nobel prize to a single/two persons in 2015? Usually it is a team of people all working together collectively to solve a common problem.

sanxiyn2• 11 years ago

No, it isn't. This is a big problem with the Nobel Prize.

TimFogarty• 11 years ago

Interesting discussion about this issue with relation to the 2013 Nobel Prize for Physics here:

https://www.youtube.com/watch?v=uNTativ_vDU

jeffwass• 11 years ago

I was actually involved with the experimental setup at SNO, however tiny in the grand scheme.

Btw, my contribution was in the front end particle detectors, when I was an undergraduate student. This was 20 yrs ago so a bit fuzzy on he details. But basically, people on my team (University of Pennsylvania high energy physics dept) designed analog ASIC's that effectively connected directly to the SNO photomultiplier tube outputs to process the tiny electrical signals, IIRC often from only a few hundred or thousand electrons. There were two chips they designed. An integrator (SNOINT) which was like a preamp and identified how strong the signal was, and a discriminator (SNOD) which identified accurate timing information of the pulses.

We required IIRC about 10,000 of these chips, and the fabrication process had a very low yield (about 30% had all functionality working). So my job entailed setting up an automated test station, simulating all functionality of the photomultiplier inputs, and interfacing with a computer to run the suite of tests and identify good/bad in about 30-60s. We had a good process and hired a bunch of part-time workers who would run through the tests to identify the good chips.

I was quite jealous of some of my colleagues who worked with the actual production circuit boards, and got to travel to SNO itself and go down into the mine to set them up in production.

Fun times though. We also built Fermilab and CERN detector electronics, and even for the cancelled superconducting supercollider. That job basically taught me electronics and data acquisition, and led to my next job as a joint hardware/software engineer.

exmadscientist• 11 years ago

No, absolutely not. Science is much different in 2015 than it was in 1915. The remaining problems are much harder and require the efforts of many, many more people to attack, but the archaic structure of the Prize means 99% of them can never be rewarded.

I used to work on an extremely similar experiment to SNO and Super-K. I played a small but key role in getting the thing to work at all. (I like to think things went a lot smoother with me helping out than they would have with someone else doing my job, but you never can tell, can you?)

Did this year's Prize recipients contribute more to science than the people at the bottom of the ladder? I don't know, I didn't work on those experiments. I also know that you should not under-value leadership. On the experiment I worked on (and now you see why I'm not naming it), one of the top people -- one of the candidates for any major awards or prizes -- was a total and complete fool and roadblock, in the classic style of legendarily terrible senior managers. Yet he has received a lion's share of the credit for this mismanagement. (To be fair, there were plenty of other top people who were good at their jobs.)

My direct supervisor on this project seemed to deal with this by wanting his fingers in as many pies as possible. I can only explain his behavior by speculating that he really, really wanted a Nobel Prize. But he will almost certainly never win one. To get a Prize in experimental particle physics these days, you must be a senior member of an experiment, and you must be very, very lucky that your experiment turns out to be Prize-worthy. This guy seemed to want to be involved in as many experiments as he could so that one of them would work out. But that meant he had little attention for each project, could not rise to the top levels of any of them, and generally never made as much total impact as if he'd concentrated on just getting one thing right. If our hunches were correct, and his life goal really is a Nobel Prize, it's kind of sad to think this talented scientist is on a life course that will only distract him with mirages, never bringing him towards his real goal.

In any case, the hundreds of us working on the experiment knew that we would never receive any high-level acknowledgements of our work, no matter how important our contributions were to the project. And that, I think, was a small but meaningful contributor to why I left science for engineering. (More importantly, I found while working on the project that I preferred engineering and am personally more fulfilled, as well as better paid, this way, but observations like that aren't going to improve modern science.)

johansch• 11 years ago

If physics research is anything similar to e.g. software development/design/creation, I think it is. Any project I have seen with that has been successful has one or a few visionary/whole picture kinda type leaders, and then a number of competent foot soldiers.

The key is to combine the vision part with the ability to manage and motivate the team.

pkrumins2• 11 years ago

I can't wait to see laureates' Nobel Lectures. Each year laureates give a down to earth lecture about their findings - how they started, how they found the results, what motivated them to work on these problems, etc. Very interesting to see laureates explain this themselves.

Click on the laureate names, then choose "Nobel Lecture" to watch the videos.

For example,

http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

For Higg's lecture a few years ago, etc.

singold• 11 years ago

OT: In spanish Kajita sounds like Cajita (little box), so there's a joke about this being a PR campaing of McDonalds.

Also Kajita should be happy because of this achievement :P

kragen• 11 years ago

Well, it looks like it should sound like "cajita", as in "cajita feliz" ("happy meal"), but actually his name is pronounced [kadʒita], not [kaxita]; think "callita", like a small digging stick, but pronounced with a Rioplatense accent. Japanese transliteration is misleading in Spanish!

(You could kind of make the same complaint about pronouncing "tomato" as [tə'meɪɾoʊ], since the second vowel in the Nahuatl word is very clearly [a], but I think you can make a reasonable case that "tomato" is an English word with several centuries of history whose pronunciation has simply changed, while Kajita is not a Spanish word, but rather the name of a Japanese guy who's in fact not even dead yet. So if you pronounce it [kaxita], you're just mispronouncing it, that's all.)

adekok2• 11 years ago

I worked on SNO for my masters, helping to build the water purification systems. The goal was one atom of impurity per cubic metre of water. It made distilled water look filthy. :)

Everyone knew that if we got it to work, Arthur would win the Nobel Prize. He worked very hard on it, and was a good leader.

Congratulations to him.

dgemm• 11 years ago

I was a summer student at SNO circa 2006 and Art McDonald was always the nicest and most patient person you could imagine. Congratulations to him and the whole team that worked on this for many years.

apetresc2• 11 years ago

Maybe I'm confused, but it seems like he won the prize for completely unrelated work. Does the prize committee award it for the full lifetime work and simply pick one nominal project to credit, or has Arthur McDonald simply done two Nobel-worthy projects in his lifetime?

adekok2• 11 years ago

http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

"for the discovery of neutrino oscillations, which shows that neutrinos have mass”

Which indicates that he won it for work resulting from the SNO experiment.

powertower• 11 years ago

http://physics.carleton.ca/sno/about-sno-project/sno-water-s...

Can't seem to find any info on the actual process of achieving this level of purification.

bmm6o• 11 years ago

Is there an easy explanation for why the oscillation implies mass?

mzs• 11 years ago

If a = b = 0 then a - b = 0, but it was shown that a - b > 0 and a and b are neutrino masses.

zakk• 11 years ago

You need to know two facts:

1) A massless object will travel at the speed of light. A massive object, on the other hand, as long as it may accelerate, will always travel at smaller speeds.

2) When you are travelling at the speed of light you don't experience time, it is completely frozen. If you could ride a photon time would freeze. This is the notion of proper time, in physicists' terms. Think of the twins paradox, it's similar, albeit not identical...

So if a neutrino were massless, as predicted by the Standard Model, it wouldn't experience time and it wouldn't oscillate. Oscillating requires time.

It follows that, as oscillations are observed, the neutrino must experience time, and have a mass.

This mass is quite tiny, we don't know its value, we just know upper bounds.

marcosdumay• 11 years ago

Time does not pass for a massless particle, thus it can not change by itself.

JTon• 11 years ago

Quote from the embedded video:

In order to do this we had to build a detector the size of a 10 story building, 2 kilometers underground. In a mine, Creighton Mine, near Sudbury, Ontario... and we had the advantage of a thousand tonnes [of heavy water] on loan from Canada's reserves of heavy water. The value of which was on the order of 300 million dollars. We used that for about 10 years, measuring neutrinos roughly 1 [per] hour. By having this very sensitive detector we were able to make measurements that others could not. But it took [a] team... on the order of 150 people to accomplish this scientific measurement.

Pretty astounding work, if you ask me. The dedication of these people should be applauded.

dang• 11 years ago

We changed the URL from http://www.nobelprize.org/nobel_prizes/physics/laureates/201... to one that gives some background.

ycitera• 11 years ago

I probably will get down-voted for my ignorance, but is this as meaning-less as the Nobel Peace Prize?

The Nobel Prize in Physics 2015: Takaaki Kajita And Arthur B. McDonald

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