Polar Detector Spots Neutrinos 54
C. Mattix writes "It looks as though they finally got some - MSNBC has a story on the polar station that detected neutrinos. " It's got a good explanation of the AMANDA station and what they're doing - not the heaviest scientific article, but good to read.
Woohoo!! (Score:3)
You mean they have finally discovered ill-suited laws that Congress tries to pass? Wow.
Maybe they should have set up camp in Washington DC.
DanH
Cav Pilot's Reference Page [cavalrypilot.com]
The matter's body thetans... (Score:1)
Re:Woohoo!! (Score:2)
And they went one mile below the surface of the south pole just to find it.
Maybe they should have set up camp in Washington DC.
No, the device is sensitive to Muons, not Morons.
"Everything you know is wrong. (And stupid.)"
six for six (Score:2)
Good history (although the translation from French is kind of amusing) here [in2p3.fr]
and this background info is a little better (also, there is more yellow on the page
http://www.ps.uci.edu/~superk/neutrino.html [uci.edu]
Detectors (Score:1)
Re:Neutrinos?! (Score:1)
The fact that the neutrino's themselves are undetectable doesn't matter. Have you ever heard of theoretical physics? The (indirect, by detecting the behaviour of the resulting part after a collision) detection just confirms what was already suspected. Please do not make bold statements like this without being actually informed about the subject.
BTW, a nice little fact about neutrino's, just to imagine how small they are. Statistically, you need about a light year of lead to stop one.
Neutrinos are detected all the time. (Score:1)
Why neutrino telescopes matter (Score:5)
Now, this low interaction probability is also good. Ordinary telescopes detect electromagnetic radiation (light, radio waves etc), however photons do scatter of the interstellar medium and even off the background radiation (for high enough energies of the radiation). This means that for long distances the vision of such telescopes is blurred. Neutrinos on the other hand don't scatter (with any significant probability) on the interstellar medium etc so it makes for "sharper images" of the universe if you can build a telescope that can see neutrinos.
What you can study is sources that emit neutrinos (of course). Points of interest could be e.g. active galactic nuclei. Also, it has been hypothethized that supersymmetric particles could account for a significant portion of dark matter. The lightest susy particle (the neutralino) has to be stable and would accumulate in the center of heavy objects (such as the Earth or the Sun) because of gravity. There the concentration would be high enough that they could annihilate with their antiparticles, and produce neutrinos.
This entirely off the top of my head. I used to share office with Amanda people a couple of years back.
Hats off for Amanda. It's just a lovely piece of engineering (and interesting science)!
FYI (Score:1)
Re:Neutrinos are detected all the time. (Score:1)
AMANDA Home Page (Score:4)
For those who may be interested in some additional technical details, please check out the AMANDA home page at: http://amanda.berkeley.edu/amanda/amanda.html [berkeley.edu].
It provides info on the history of the project (AMANDA-A, -B, and -II) as well as lots of links to many other resources and references.
Re:Detectors (Score:3)
Just have a look at this image from the construction of the Superkamiokande Neutrino Detector [u-tokyo.ac.jp]. The photomultiplier tubes ("mushrooms") used there are very much similar to those used for the AMANDA detector. You can see two of the AMANDA sensors here [berkeley.edu], together with the glass pressure globes they're put in before deployment.
I know this - have been working for the AMANDA group once, when we were calibrating the first PMT's for AMANDA back in 1995. It's done at Desy Zeuthen [www-zeuthen.desy.de] near Berlin. And we were using Linux boxes in the lab for data aquisition purposes ;-)
The nifty thing about AMANDA aren't the PMT tubes but the pressure globes they are put in (1500m of solid ice do exert some force ...). I've got one of the predecessors (used for the BAIKAL experiment) at home, it's cool telling people at a party that the salad bowl has once been at 1500m depth in Lake Baikal.
By the way, did someone notice that the AMANDA logo is a Penguin [berkeley.edu] ?
Re:Woohoo!! (Score:1)
(Super) Kamiokande and the Home Salt mine detectors have been picking up solar and cosmological neutrinos for years now.
But being at the south pole they get a slightly different view, due to the different position in space, as neutrinos pretty much ignore matter, like the Earth.
Re:Neutrinos - AMANDA is more than "detection" (Score:1)
The new thing about AMANDA is that it's direction-sensitive. That means instead of "oops - there's been one of the ghost particles" AMANDA will find out about "oops - one of the ghost particles came from ...". No other experiment has been able to get this information so far.
Think of the difference between a conventional neutrino detector and AMANDA as that between a Geiger Counter and the Chandra Gamma-Ray Observatory [harvard.edu]. It's an entire new field of science you can do if you're imaging the sky instead of just counting particles.
Or perhaps this one (Score:1)
Or perhaps this one [founderscamp.com] that you carry as your top story [founderscamp.com].
Ha!Ha!
Re:six for six (Score:2)
A pedant writes (Score:1)
I wonder how well the reporter understood this? (Score:3)
Pretty good article, but I got the impression that the person writing it didn't quite understand what was going on. He said this was the first time that neutrinos were detected, and then immediately quoted one of the AMANDA researchers as saying it was the first time a new, higher energy neutrino had been detected.
Interesting to here that they plan to construct a larger particle detector.
Yet another fine example of science reporting... (Score:1)
2) they've had neutrino observatories since the mid-70's
3) there are currently at least four full-time neutrino/high energy observatories in operation
Maury
Re:Neutrinos?! - George Bush reaction ! (Score:1)
Basic research seems to have a hard time ahead with this US administration.
Neutrinos are... (Score:1)
Re:Why bother ? Should have given money education! (Score:1)
I'm ashamed to be in the same species as you!
Re:Neutrinos?! (Score:2)
Neutrinos rarely interact with normal matter, and that makes them very hard to detect. However, if you're prepared to throw a whole array of sensors around a huge vat of water (not just water) in a location where _other_ nuclear interactions are minimal (e.g. away from the surface of the earth), and you're prepared to wait for enough time, you will occasionally see what are predicted to be the results of neutrino interactions. You don't actually detect the neutrinos, but they have a 'fingerprint' that is easy to recognise, and no other interaction causes that fingerprint.
Don't flame - inform instead.
THL
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Re:Neutrinos - AMANDA is more than "detection" (Score:2)
Re:six for six (Score:5)
Leptons are the 'light particles'. they have less mass than most other commonly seen particles. There are six types. The electron, the muon, the tauon, and the neutrino. Now that looks like only four because their are three types of neutrino, the elctron neutrino, the muon neutrino and the tauon neutrino.There are three types so that the 'families' are preserved.
Now the nuetrino was introduced in order to preserve a quantity known as spin. All the leptons have spin 1/2, and are fermions. Fermions are particles that follow the Pauli exclusion principle, so no two fermions are in the same quantum state. Now when a neutron decays into a proton and an electron, charge is preserved, whoever spin isn't, because the neutron has spin +-1/2, the proton has spin +-1/2, and so does the electron. In order to get the spins balancing, you need a neutral extra spin 1/2 particle.
Now about those 'familys' I mentioned earlier? Well, only the electron is stable among the non-neutrino leptons. The others decay into an electron and a bunch of neutrinos. However the number of particles in each family remains constant. So when a muon decays (1 muon), it decays into an electron (1 electron), a muon netrino (1 muon) and an electron _anti_neutrino (-1 electron)
So there are six leptons, tauons and muons decay into electrons, but leave behind neutrinos of the same family.However, the universe would not be at all interesting with only leptons. There are quarks as well.
There are also six flavours of quarks. This may or may not be coincidence. Last I checked physicists were unsure if there was a link between quarks and leptons. The six quarks are Up and Down, which form protons, and other stuff that decays into protons (and various leptons). There is strange and charmed, and top and bottom, which make up weird particles that tend to be heavier.
Quarks are never seen alone. They bind together in groups of three or two, and have a charge of +2/3 or -1/3. Now a group of three quarks (called a baryon or heavy particle), such as a proton would have two quarks with a charge of +2/3 and one with a charge of -1/3. I think a proton is uud. Now a neutron(ddu) turns into a proton when one of it's down quarks turns into an up quark, an electron, and two neutrinos. It does this using the weak force, which I'll get to later. Quarks also come in groups of two, which are a quark and an antiquark. These are mesons. They tend to be things like !ud or !du.
So you now have leptons, that help balance things and quarks, that stick together. But what forces act on them? Four. Gravity, Electromagnetism, Weak and Strong nuclear forces.
The strong force is what groups quarks together. All quarks have a color, red, green, or blue. Now in a baryon or meson, the overall color must be white. So a baryon is made up of a red quark, a green quark, and a blue quark. A meson usually has a blue colored quark and an antiblue colored antiquark. Or red/antired, or green/antigreen. As long as no red green or blue shows, the universe is happy. All this is kept in check by the strong force and it's messenger particle, the gluon. Gluons carry color between quarks. If a red quark changes to a green quark, a red/antigreen gluon is emmited, and when it hits a green quark, the antigreen and green colors cancel, and the previously green quark becomes red.
Then there is the weak force. The weak force changes things. It is responsible for the changes in a neutron that cause it to decay. There are three carrier particles for the weak force W+,W- and Z. they carry electrical charges of +1,-1, and 0 respectivly. Now when the d quark in a neutron decays, it emits a W-. the charge is conserved by the W- taking away -1 from the -1/3 to give a +2/3 charge. Now we have a u quark and a W-. the W- then decays into an electron and an electron antineutrino.
Then there is the electromagnetic force, which has as its messenger the photon. Now when two electrons pass by each other and deflect, a pair of photons is exchanged. These photons, like all the other messenger particles are virtual. They only exist for a fleeting second, and don't do much apart from tell the particles what to do. Electromagnetism only talks with particles with electric charge.
Finally there's gravity. Physicists havent yet got Quantum gravity, so they don't yet know how to fit it in with everything else. It's carrier is called the graviton, but nobody has yet caught a live one. Mostly because the energy needed to turn a virtual graviton into a real one is huge.
One last thing. The messenger particles are all bosons, so the can be acting cohesivly in a group. This gives things like lasers their intensity. Fermions can't do this, so you'll never see a easer.
The reason neutrinos are so hard to spot is because the have no mass, they don't interact gravitationally, they are electrically neutral, so they don't talk electromagnetism, and they aren't a quark, so they don't talk colors with the strong force. They can only be detected by their interaction with other particles through the weak force. This is what makes spotting them big physics.
BTW, remember that I may be wrong. IANAPhysicist.
It sure is a versatile tool! (Score:1)
Chris
Re:six for six (Score:1)
Why not? You sound as if you've got basic particle physics down pretty well. That's gotta be the most concise, while correct, explanation of those ideas I've ever seen. Maybe you should just get a job at a high school and improve the quality of instruction there.
Article seems more precise than our criticism (Score:2)
This article clearly states these were the first neutrinos seen by AMANDA:
In the next paragraph it correctly characterizes the novelty as having to do with the level of energy in the neutrinos observed:It skimmed the surface, granted, but the article doesn't make the errors we're accusing it of. What gives?
You can't expect much better of MSNBC; after all, they have all the science headlines under "Technology," their industry-conquering "boy we sure are innovative" section.
Widely used acronym (Score:1)
Re:six for six (Score:2)
Re:Article seems more precise than our criticism (Score:1)
It is harder to see a dim light than a bright light. You need a better, more sensitive detector (Hubble) to see a _dim_ light than to see a bright light (naked eye).
What am I missing? Maybe the high energy ones pass to fast to have the TIME to detect them? Then the dector is not more _sensitive_, but only _faster_.
I guess the bottom line is they can detect _more_ particles.
Re:six for six (Score:1)
The calculus, (and there's a lot of it) gets hidden in the algebraic notation of quantum physics. It looks simple, but it's not for the faint of heart.
BTW my high school Newtonian physics had it's fair share of calculus (especially useful for acceleration). Your milage may vary.
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Re:Why neutrino telescopes matter (Score:1)
Re:six for six (Score:1)
Crap (Score:2)
Re:Article seems more precise than our criticism (Score:1)
Do you get it now?
Re:six for six (Score:1)
Good job, just a few nitpicks:
They're pretty sure. It shows up in grand unified theories, and I think there are more mundane reasons to believe it as well. Actually it's just one virtual photon (to lowest order). Current thinking is that quantum gravity won't turn out to be like an ordinary quantum field theory on a background spacetime, so it probably won't be describable in terms of an exchange particle (graviton). However, current thinking is that it also ought to look like an ordinary QFT at sufficiently large scales / low energies, so in those regimes it ought to look like there's a graviton, though if you were to look closer you'd probably find out that it's not really a particle. The Super-K results suggest that at least some of them do have mass. Everything interacts gravitationally, even massless particles, because everything has energy and energy gravitates. After all, photons are massless yet light is deflected gravitationally.The problem is just that gravity is so weak, we can't hope to detect neutrinos (or any other individual particles) just from their gravitational effects alone.
More practical stuff (Score:1)
Re:six for six (Score:2)
Bravo! Most of my particle physics colleagues couldn't give a better brief explanation. In less than a page, you've succeeded in summarizing the last fifty years or so of high energy physics brilliantly!
I did want to mention one thing. You said:Last I checked physicists were unsure if there was a link between quarks and leptons.
In fact, we are pretty darn sure that there IS a link. We don't know exactly why there are three families (or generations) of fermions (although there are many ideas out there), but we DO have a good understanding of why there are as many leptons as there are quarks. In fact, the reason we believed for many years that there was a top quark and a tau neutrino is that they HAD to be there.
The reason is a tad technical, and has to do with something called gauge anomaly cancellation. If the number of leptons and quarks was NOT the same, then some of the symmetries of the theory that we actually see in nature would be destroyed by certain "one loop Feynman graphs" that connect three gauge bosons (the triangle graphs). But, with the same number of quarks and leptons, the gauge anomalies of the standard model cancel, and all is right with the current theory of the universe. In fact, gauge anomaly cancellation is nearly a requirement for any model to be taken seriously, and is one of the first things people ask about when someone presents a new model.
Re:More practical stuff (Score:1)
As for the snow there, it's probably more icy, from being compressed by the weight of all the snow above.
. . .
Re:More practical stuff (Score:3)
(I am a former member of the AMANDA collaboration, BTW...)
Re:AMANDA backups (Score:1)
Re:Woohoo!! (Score:1)
Re:Neutrinos?! (Score:1)
No, There is land below the ice at the SP. You are thinking of the North Pole, which doesn't have land below the ice.
There is an inaccurate statement in the article that has mislead you:
Neutrinos travel through Earth all the time without being detected.
This should read: Most Neutrinos travel through Earth all the time without being detected.
There is a nice introduction into the discovery of the neutrino at [in2p3.fr]
http://wwwlapp.in2p3.fr/neutrinos/aneut.html
Re:I wonder how well the reporter understood this? (Score:1)
No. He said neutrinos were detected the for first time with the AMANDA detector. Or in other words, the AMANDA detector hasn't detected any neutrinos until recently.
Horta Eggs (Score:1)
newspaper description of project [rapidcityjournal.com]
Re:What the heck do they do?! (Score:2)
Why would detecting nutrinos matter at all? The article said something about knowing the path that the nutrino came from...uhm so what? It is most likely so far out in space we have no idea where it originated. And knowing where it came from matters how? Didn't they say things like stars give them off? Pick a star, there you go, theres an origin for nutrinos. Can we detect how old they are, if they contain life or anything like that, from what I understand - no. Then why are we spending all this money to look at things that ar invisible (and yet that makes sense) instead of putting it in something worthwhile?
Oh well. If something does not have immediately apparent practical use, it's not worth anything to study? I guess we'd still be in the middle of dark ages if this guideline would have been strictly adhered to. Everything does NOT have immediately apparent practical applications.
Careful (Score:1)
Re:Neutrinos?! (Score:1)
>Neutrinos travel through Earth all the time without being detected.
>This should read: Most Neutrinos travel through Earth all the time without being detected.
To be truly pedantic MOST Neutrinos don't travel through the earth at all, the earth being so small in relation to the size of the universe.
Re:six for six (Score:2)
Part of this may be due to inefficiency in our detectors, errors in our theories of stellar behaviour or errors in our theories of fundamental particles.
The problem is almost certainly (i.e. hundreds of physicists have bet their careers on it) in our theory of fundamental particles. The discrepancy is absolutely not due to detector inefficiency (the same types of experiments obtain the expected neutrino flux from nearby experiments); the detection efficiency for neutrinos is very low, but if you build a big enough detector, it doesn't kill you. Furthermore, many different experiments using very different techniques obtain results that (roughly) agree on the disagreement. And while there are problems with the stellar models, the same calculation that tells you how many neutrinos come out also tell you how many photons come out and what the surface temperature of the sun should be, and the photon flux and temperature measurements are dead on. Further, the stellar models make predictions about things like "sun-quakes" (the spectrum of solar acoustic surface waves) that are, I believe, also dead on. So, while there is room for improvement in both the experiments and the stellar models, they are not reallly suspect in the solar neutrino problem.
Further evidence that it is the fundamental particle physics that is wrong is that there is a measurable azimuthally dependent flux (angle above versus below the horizon) of atmospherically produced muon neutrinos; the Standard Model predicts no such behavior.
In fact, the best (educated) guess at this point is that neutrinos are able to "oscillate" between the different types, and that the neutrinos from the sun change from electron type to some other type during the time it takes to get from the sun to the earth. Thus, when they get here, some of them are no longer in a form that can be detected by the experiments to date.
Now, I don't think that AMANDA can tell us anything about the solar neutrinos (it looks at very high energy muon type neutrinos, not the low energy electron type), but there are experiments such as SNO in Canada that should be able to access the low energy neutrinos and give us some more information about the solar neutrino problem.
Re:six for six (Score:1)
As for my science classes, the first ones just repeated the same material over and over, adding a tiny bit more detail each year. Once I got to a class specifically focused on physics, it was just another incremental increase in the amount of detail and homework. The really sad part is that almost no mathematical background was expected on the part of the students. Screw calculus, that class was taught without the benefit of anything past first year algebra. The result was a bunch of students trying to remember dozens of formulas, not realizing that most of them were just permutations or combinations of others. I remember spending significantly more time helping my classmates than doing work. The rest of my time in that class was spend reading books about much more interesting physics and/or designing simple nuclear weapons. Now that I'm in 400-level physics courses, I sometimes long for the days before integrals. Then I remember how much high school sucked, and go back to the problem.
Re:Woohoo!! (Score:1)
Whoa! (Score:1)
Re:Neutrinos (Score:1)