|
|
|
|
|
|
|
|
|
 Posted: Tue May 02, 2006 4:19 pm
So I understand the neutrino is most similar to the electron with the exception of the fact that it has no charge. And I undertstand that it can move through objects without being detected, and that it acts only under the influence of the weak and the gravitational force. But... what is its purpose? What does it do?
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Tue May 02, 2006 4:42 pm
Gah, elementary particles do not do things, they exist, that is what they do. XD
If you insist, neutrinos were predicted by Pauli to explain "missing energy". They carry away information and are a pest in collider experiments. >_>
The neutrino is little like the electron really. While each of the charged leptons has an associated neutrino partner, neutrinos are far more "interesting" and mysterious than the charged leptons. It is because the neutrino interacts so weakly with other particles that it can move through the universe without being detected, to detect it you have to have it interact with something! Which is why SNO and Super-K are such massive beasts: the low interaction cross sections [the cross section is crudely the likelihood of occurance] is combated with a large area.
There is a lot of work at the moment into neutrino physics. The nature of neutrino oscillations [MINOS, K2K, etc.] is one hot topic, as neutrinoless double beta-decay [0νββ] which would be strong evidence that the neutrino is its own antiparticle [NEMO-III].
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Tue May 02, 2006 9:39 pm
Just to elaborate... A Lost Iguana The neutrino is little like the electron really. While each of the charged leptons has an associated neutrino partner, neutrinos are far more "interesting" and mysterious than the charged leptons. Somewhat, but the neutrino differs from the electron in one rather exotic way--it can only have negative helicity. Electrons, of course, can be either left-handed or right-handed. A Lost Iguana There is a lot of work at the moment into neutrino physics. The nature of neutrino oscillations [MINOS, K2K, etc.] is one hot topic, as neutrinoless double beta-decay [0νββ] which would be strong evidence that the neutrino is its own antiparticle [NEMO-III]. Eh. There even fringe proposals to the effect the neutrino has negative mass-squared, i.e., is tachyonic. Time will tell.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Wed May 03, 2006 2:32 pm
Hmm. Beta-decay. The electron was supposed to be the only particle emitted and you would get discrete energy spectra [conservation of energy, you know the energies of the particles beforehand], only observations revealved that the spectra were continuous.
Pauli, in his famous letter, posited the neutrino in order to explain why a continuous range of energies was allowed, the neutrino was carrying away a "random" percentage of the energy.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Wed May 03, 2006 2:51 pm
Alrighty, so a neutrino has negative helicity, ( looked it up xd ) what's this 'missing energy' thing? What did Pauli ned to explain?
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Sat May 06, 2006 1:53 pm
A Lost Iguana Hmm. Beta-decay. The electron was supposed to be the only particle emitted and you would get discrete energy spectra [conservation of energy, you know the energies of the particles beforehand], only observations revealved that the spectra were continuous. Pauli, in his famous letter, posited the neutrino in order to explain why a continuous range of energies was allowed, the neutrino was carrying away a "random" percentage of the energy. so weird eek so the neutrino is the reason things are quantized?
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Sat May 06, 2006 2:36 pm
poweroutage so weird eek so the neutrino is the reason things are quantized? Why do you think that? The neutrino was hiding the true kinematics of the system, giving the impression that the resulting particle could have a range of energies. If there was only one particle then it should only have one energy. If there is another particle being emitted then you lose the information about it and it looks like you have lost energy.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Mon May 08, 2006 8:57 am
A Lost Iguana poweroutage so weird eek so the neutrino is the reason things are quantized? Why do you think that? The neutrino was hiding the true kinematics of the system, giving the impression that the resulting particle could have a range of energies. If there was only one particle then it should only have one energy. If there is another particle being emitted then you lose the information about it and it looks like you have lost energy. because I've come to accept the quantized nature of things, and now you're telling me "hey... actually, things are not quantized it was the neutrino. yah, sorry, we had to pull on one you."
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Mon May 08, 2006 6:37 pm
Quantization is not something absolute. A free particle, for example, can have any energy level. Quantum mechanics is more analogous to "given such-and-such system", e.g., particle in a potential field, then its energy states are quantized in such-and-such manner. By changing the potential field, one can have any preditermined energy level as one of the possibilities. See, for example, the standard textbook treatment of particle-in-a-box, and observe how the energy levels are relative to the box size. One can question this, of course--there is some evidence that spacetime itself is discrete (this is contested), but there is no working theory to adequately handle such a thing even if it turns out to be the case.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Posted: Wed Mar 07, 2007 6:19 am
poweroutage A Lost Iguana Hmm. Beta-decay. The electron was supposed to be the only particle emitted and you would get discrete energy spectra [conservation of energy, you know the energies of the particles beforehand], only observations revealved that the spectra were continuous. Pauli, in his famous letter, posited the neutrino in order to explain why a continuous range of energies was allowed, the neutrino was carrying away a "random" percentage of the energy. so weird eek so the neutrino is the reason things are quantized? No no. And hehe... This is what my current project is about. Radioactive decay of, for example, Strontium 90 is a quantum process. It should yield discrete values. The nucleus loses a discrete amount of energy that's carried away by a beta particle (an elecron). So when we detect these electrons, we would expect they have that discrete amount of energy. But they didn't. They had a wide range of energies, always lower than the the expected value. So this meant that (a) Some energy was missing and (b) We were getting a continuous range of energies when we should be getting a discrete value. It turns out that when a nucleus decays, it emits both an electron *and* a neutrino. The neutrino is responsible for hiding the missing energy, and when you add up the energy of the neutrino and its corresponding Beta Particle, the total is what you'd expect. In short, the total process is still discrete and dictated by the boundary conditions of the atom. It's just that the energy is distributed between the electron and the neutrino.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Reply
