Low Energy Neutrinos: Questions & Answers

In summary: Which means that the energy of the weak interactions is orders of magnitude smaller than the energy of the electromagnetic interactions.
  • #1
Wallace
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Hi guys, I have a basic question about neutrinos. Since it is now supposed from both cosmological and particle physics observations that neutrinos have a small rest mass, what are the lowest energy (and hence lowest speed) neutrinos we can/have observed?

Since they are so weakly interacting (and hence do not readily 'lose' energy) and most that we observe come from the Sun (nearby), I'm assuming that we only observe relativistic neutrinos.

Would it be possible (or make any sense) to study non-relativistic neutrinos? Or is the rest mass so small that even if a neutrino could someone be slowed to rest, the slightest force on them would cause them to be accelerated back to relativistic speeds.

Do my questions even make sense in this context?
 
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  • #2
The cross section for neutrinos decrases with decreasing energy.
I do not remember what the lowest detected neutrinos is for the moment.

The neutrinos only interact weakly (gravity is neglectable).

http://www.isv.uu.se/~cph/kurs/reading.php
good reading material, download the pdf's before the course page shouts down :)
 
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  • #3
Interesting, I was wondering about cross-section vs energy. I should know this, but I've clearly forgotten, but why does this decrease for neutrinos but for say X-rays the cross-section increases as energy is decreased? Is this a massive particle vs photon difference or is it not so simple? (I suspect the later)
 
  • #4
It has to do with the fact that neutrinos only interact trough the weak force, but photons via the electromagnetic (with is also much stronger than weak force). So you have two totaly different forces and therefore different interaction behaviors and cross sections.
 
  • #5
:redface: Ah yes of course
 
  • #6
Or, to make it clearer. The coupling constant of the weak force is infact as large as 0.58 times the coupling constant of the EM force, but the RANGE of the weak interatcions is incredible small! About 1/1000 of the radius of a proton!
 

1. What are low energy neutrinos and why are they important?

Low energy neutrinos are subatomic particles with very little mass and no charge. They are important because they play a crucial role in understanding the fundamental nature of the universe and its processes, such as nuclear reactions in stars and supernovae explosions.

2. How are low energy neutrinos produced?

Low energy neutrinos are produced through various processes, including radioactive decay, nuclear reactions, and cosmic ray interactions. They can also be produced artificially in particle accelerators.

3. How do we detect low energy neutrinos?

Low energy neutrinos are notoriously difficult to detect because they interact very weakly with matter. However, scientists have developed specialized detectors, such as giant underground tanks of water or ice, that can detect the faint signals produced when a neutrino collides with an atomic nucleus.

4. Can low energy neutrinos be used for anything practical?

While low energy neutrinos do not have any practical applications yet, scientists are actively researching ways to harness their unique properties for various purposes, such as communication and energy production.

5. Are there different types of low energy neutrinos?

Yes, there are three known types of low energy neutrinos: electron neutrinos, muon neutrinos, and tau neutrinos. Each type is associated with a corresponding charged particle and has distinct properties, such as mass and interaction strengths.

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