LHC as detector of relict neutrinos?

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Kasuha
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LHC as detector of relict neutrinos?

Post by Kasuha » Wed Feb 03, 2010 4:11 pm

I was reading an article about neutrinos and their detection recently and when it discussed relict neutrinos and problems with their detection due to their extremely low energy I got an idea if LHC couldn't be used as a kind of such a detector - sure these neutrinos have too small energy to interact with any non-relativistic matter but protons in LHC are quite relativistic to make such collisions possible ... maybe?

I understand there is very little "detector matter" circulating in LHC but eventual collision of such kind could be possibly detected as a collision which occurred e.g. in time or place where beams are in the LHC but don't collide.

Now I'm no scientist so I'd like to ask if somebody knows if something like this is at all possible and if it was taken into account...

Anitusar
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Re: LHC as detector of relict neutrinos?

Post by Anitusar » Sun Feb 07, 2010 9:02 pm

No, this will not be possible for several reasons:

1) The problem with Neutrinos is not their low energy, but their very, very, very, very low interaction rate. If you would want to make sure, that a neutrino had an interaction with a material, you would need several lightyears(!) of a gold volume for example. They really do not like to interact.

2) If there would be an interaction with a proton of the beam, it would most likely occur in the parts of the ring, where the protons are accellarated. No detectors there.

CERN is however involved in the neutrino field via the CERN Neutrinos to Gran Sasso experiment, where they study neutrino oscillations.

A good neutrino detector has to be really big due to the low interaction rate. One experiment i find really cool is the IceCube Neutrino Observatory

Kasuha
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Re: LHC as detector of relict neutrinos?

Post by Kasuha » Mon Feb 08, 2010 11:36 am

In my opinion, an interaction of beam proton with a neutrino can happen anywhere along the beam trajectory. I don't see why it should have higher chance in RF.

Problem of existing neutrino detectors including Ice Cube or Gran Sasso is the fact that they only detect neutrinos of high enough energy. Vast majority of neutrinos does not have so high energy. And relict neutrinos are even less energetic, but the less energy they have, the more of them could be around now.
The theory is, if we give detector mass enough energy, it is more likely to interact with low energy neutrinos. And given the abundance of low-energy neutrinos compared to high-energy ones we are detecting now, it might require less detector mass.

But well, there is really very little "detector mass" in LHC probably, even less really monitored space and also chances of proton interaction with a neutrino are unknown to me (might get better with lead ions?). And also the energy to which beam is accelerated might also be not enough for such collisions... but that's why I have asked if somebody really considered this option.

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tswsl1989
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Re: LHC as detector of relict neutrinos?

Post by tswsl1989 » Mon Feb 08, 2010 12:25 pm

The fact that neutrinos have such low energy means you need huge amounts of observed matter to have a reasonable chance of observing the desired interaction.

The amount of matter in the LHC is comparatively small, so the chances of the neutrino interacting anywhere is low. Couple that with the high energy of the beam and chances of noticing any interactions are so small as to be negligible.

I imagine that any neutrino events detected by the experiments with no beam present would be discarded as noise.

If you want to detect neutrinos, then Ice cube style experiments are the best way to do it.

Kasuha
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Re: LHC as detector of relict neutrinos?

Post by Kasuha » Mon Feb 08, 2010 4:30 pm

The problem with Ice Cube is, it only detects neutrinos with energy of 50 GeV or higher. I don't think it is going to detect a single relict neutrino over its lifetime. It's like we'd try to detect relict radiation using a gamma ray detector.

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