6 ms·

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

161 points by sasvari 11y ago

bobmichael 11y ago
Technical document explaining the scientific background here: http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/advanced-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201...
Maro 11y ago
https://en.wikipedia.org/wiki/Neutrino_oscillation 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 11y ago
I would love someone to do an ELI5 of their research.
- pkrumins 11y 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 11y ago
  Here's the official ELI5 (or ELI12, which is probably what you really want): http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/popular-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201... edit: and here is the official ELIAPhysicsGradStudent: http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/advanced-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201...
- hugh4 11y 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.
sanxiyn 11y 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 11y 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.
- sanxiyn 11y ago
  No, it isn't. This is a big problem with the Nobel Prize.
- TimFogarty 11y ago
  Interesting discussion about this issue with relation to the 2013 Nobel Prize for Physics here: https://www.youtube.com/watch?v=uNTativ_vDU https://www.youtube.com/watch?v=uNTativ_vDU
- jeffwass 11y 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.
pkrumins 11y 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/2013/higgs-lecture.html http://www.nobelprize.org/nobel_prizes/physics/laureates/201... For Higg's lecture a few years ago, etc.
singold 11y 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 11y 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.)
adekok 11y 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 11y 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.
- apetresc 11y 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?
  - adekok 11y ago
    http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/press.html 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.
    - apetresc 11y ago
      Wait, so the water purification project led to the discovery that neutrinos have mass? EDIT: Oh okay, I get it now. The project wasn't about building water purification systems, they just needed really really pure water to run particle-related experiments. Got it!
- powertower 11y ago
  http://physics.carleton.ca/sno/about-sno-project/sno-water-system 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 11y ago
Is there an easy explanation for why the oscillation implies mass?
- mzs 11y 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 11y 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 11y ago
  Time does not pass for a massless particle, thus it can not change by itself.
souljaswag 11y ago
Takaaki Kajita is one suave motherfucker. Dude is popular with the ladies. Ain't gonna lie. I saw him at the club one time and dude knows how to get it on.
JTon 11y 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 11y ago
We changed the URL from http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/index.html http://www.nobelprize.org/nobel_prizes/physics/laureates/201... to one that gives some background.
ycitera 11y ago
I probably will get down-voted for my ignorance, but is this as meaning-less as the Nobel Peace Prize?

161 points by sasvari 11y ago

Technical document explaining the scientific background here: http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/advanced-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201...

Maro 11y ago

https://en.wikipedia.org/wiki/Neutrino_oscillation 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 11y ago

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

pkrumins 11y 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 11y ago
Here's the official ELI5 (or ELI12, which is probably what you really want): http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/popular-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201... edit: and here is the official ELIAPhysicsGradStudent: http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/advanced-physicsprize2015.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/201...
hugh4 11y 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.

sanxiyn 11y 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 11y 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.

sanxiyn 11y ago
No, it isn't. This is a big problem with the Nobel Prize.
TimFogarty 11y ago
Interesting discussion about this issue with relation to the 2013 Nobel Prize for Physics here: https://www.youtube.com/watch?v=uNTativ_vDU https://www.youtube.com/watch?v=uNTativ_vDU
jeffwass 11y 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.

pkrumins 11y 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/2013/higgs-lecture.html http://www.nobelprize.org/nobel_prizes/physics/laureates/201... For Higg's lecture a few years ago, etc.

singold 11y 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 11y 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.)

adekok 11y 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 11y 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.
apetresc 11y 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?
- adekok 11y ago
  http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/press.html 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.
  - apetresc 11y ago
    Wait, so the water purification project led to the discovery that neutrinos have mass? EDIT: Oh okay, I get it now. The project wasn't about building water purification systems, they just needed really really pure water to run particle-related experiments. Got it!
powertower 11y ago
http://physics.carleton.ca/sno/about-sno-project/sno-water-system 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 11y ago

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

mzs 11y 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 11y 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 11y ago
Time does not pass for a massless particle, thus it can not change by itself.

souljaswag 11y ago

Takaaki Kajita is one suave motherfucker. Dude is popular with the ladies. Ain't gonna lie. I saw him at the club one time and dude knows how to get it on.

JTon 11y 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 11y ago

We changed the URL from http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/index.html http://www.nobelprize.org/nobel_prizes/physics/laureates/201... to one that gives some background.

ycitera 11y ago

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