Neutrinos and nuclear reactions

[jlefevre76]

This isn't really my area (I'm a mechanical engineering graduate), but I thought maybe somebody on the forum could give me feedback or help redirect my thinking if this is not right.

So, neutrinos are famous for not really doing anything, just kind of being there (by this I mean being the product of decay or stellar reactions, or both, anyway...). So, like many a scientist before, I am asking a favorite question:

What can we point a neutrino beam at that will actually do something? Since spatially, the interactions between nuclei and neutrinos are rare because nuclei are small relative due to the different forces at work in the nucleus, and the electrons holding elements/molecules together at distances orders of magnitude greater than the nuclei. So, I was thinking, besides testing elements to see which ones react with neutrinos (which it's my understanding that basically none of them do), maybe we could do a more dynamic kind of experiment. Maybe, one could point a particle accelerator beam at a target, and have a nuclear reaction (maybe low level) going on the other side. So, the neutrinos would fly through the space occupied by the nuclear reaction in progress. It might not do anything, but maybe it would. Perhaps, the presence of neutrinos would slow down the rate of reaction, or speed up the rate or reaction, or have some other interesting kind of effect (though I honestly don't know what would be more interesting than being able to control a nuclear reaction with a neutrino beam).

Any comments? I can't say I'm confident this is a novel or interesting idea, but I thought I'd see what people who know this kind of stuff think about something along these lines.

 

[Borg]

Neutrinos are extremely difficult to detect. Take a look at the detection section of the Wiki article on neutrinos and you'll see that they can't be detected directly. Plus 'boosting' the number of them doesn't do much because there are already about 65 billion of them from the sun passing through every square centimeter of your body (perpendicular to the sun) every second.

 

[mfb]

You cannot hit "a nuclear reaction in progress" for two reasons:
- It is hard enough to hit a nucleus that just sits there for months, waiting for neutrinos. Hitting it exactly in the extremely short time of a nuclear reaction (shorter than 10^-20 seconds) does not work. Does not work as in: you will not get a single interaction of this kind even if you run your experiment for a billion years with incredible rates for both neutrino flux and nuclear reaction rate.
- With reasonable neutrino beams, you hit individual nucleons (protons and neutrons) instead of the whole nucleus. The collision won't care about the rest of the nucleus.

Neutrinos interact with all types of nuclei and also with electrons, those interactions are just extremely rare for all types.

 

[jlefevre76]

Ok, good to know. I already knew that reactions with neutrinos are so rare, they basically don't happen, like the neutrinos passing through the Earth go in one side and out the other (or so I've been told). Anyway, just a thought I had. It's great to get an answer so quickly and a few facts to remind me of stuff I had forgotten (I think I had heard the number of neutrinos from the sun was ridiculously high once before, but I guess I had forgotten, not being something I deal with on a regular basis, I forget that kind of information).

 

[e.bar.goum]

My favourite way to describe how non-interacting neutrinos are is this:

The mean free path of neutrinos in lead is a light year.

That is, if you put a beam of neutrinos through a lead block, that lead block would have to be a light year long before half of the neutrinos have interacted.

 

[mfb]

they basically don't happen

Well, neutrino detectors rely on the tiny deviation from this approximation and they do care about the interaction rates.

The mean free path length depends on the energy. At 1000 TeV the Earth is a significant obstacle and most neutrinos above this energy won't reach the other side.

 

[Matterwave]

Well, neutrino detectors rely on the tiny deviation from this approximation and they do care about the interaction rates.

The mean free path length depends on the energy. At 1000 TeV the Earth is a significant obstacle and most neutrinos above this energy won't reach the other side.

Are these the energies of the neutrinos produces at CERN or OPERA or w/e? I can't think of any astrophysical sources for neutrinos with this much energy...

 

[mfb]

CERN and all other accelerator-based beams are limited to tens of GeV (well you could get more energy if you would use the LHC beam, but that is not done for practical reasons, and it would still be at most ~TeV).

There are astrophysical sources for PeV-neutrinos, IceCube found three events so far, called "Ernie", "Bert" and "Big Bird". Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data