Understanding Neutrino Spin: Exploring Measurement Possibilities Beyond Decay

In summary, neutrinos do not interact strongly with other particles, so it is possible to measure their spin by looking at the way they interact with other particles.
  • #1
kilokhan
5
0
If a neutrino is unaffected by EM and strong forces, and only interacts weakly, how is it possible to measure its spin? I don't mean measurement in a practical sense, as in looking at pion decay.. but how it could be measured in principle. I guess what I mean is are there any physical phenomena where it is a factor (apart from decays).
 
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  • #2
Why do you rule out decays? That is how most particle spins are determined in practice and in principle.
 
  • #3
what about the usual thought experiment used to explain spin, with magnetic fields? do we expect neutrinos to be deflected?
 
  • #4
Without thinking too much about it, I think they would not be deflected because they don't have magnetic moment (because they don't have charge...). The magnetic moment of neutrino is less than [tex]0.74 \times 10^{-10} \mu_{B}[/tex] (upper known limit in terms of the Bohr magneton, which is the natural unit)

Now maybe a higher order process I have not thought of right now could indeed deflect this neutrino...

Apart from that, it is possible to deduce the spin of the neutrino from more general principles, without actually measuring it.
 
  • #5
kilokhan said:
what about the usual thought experiment used to explain spin, with magnetic fields? do we expect neutrinos to be deflected?


Well you said in your first post that they don't interact via the EM-force so have answered that one yourself :-)
 
  • #6
We detect neutrinos by looking at how they interact with other particles. A good choice is electrons. Of course neutrinos don't leave a track but electrons do.

The target electrons all have spin 1/2 but they are oriented randomly. We can look at the characteristics of the electrons that are hit to learn stuff about the spin and orientation of the neutrinos.

For example, if the neutrinos had no spin, then the interaction would follow the symmetry of a spin-0 + spin-1/2 system. Since the spin-1/2 systems aren't polarized, the resulting collisions aren't polarized either.

Instead, the neutrinos turn out to have spin-1/2 and they ARE polarized, with their spin aligned in the direction of travel (or antiparallel). You should be able to detect this in the characteristics of the ejected electron.
 
  • #7
kilokhan said:
If a neutrino is unaffected by EM and strong forces, and only interacts weakly, how is it possible to measure its spin? I don't mean measurement in a practical sense, as in looking at pion decay.. but how it could be measured in principle. I guess what I mean is are there any physical phenomena where it is a factor (apart from decays).

I would say it can be measured like for every other particle.
Indeed differencial cross-section depends of the spin of incoming and outgoing particles. So looking at the differencial cross-section of well chosen observable (like an angle) will answer your question.
 

FAQ: Understanding Neutrino Spin: Exploring Measurement Possibilities Beyond Decay

What are neutrinos and why is their spin important?

Neutrinos are subatomic particles with a very small mass and no electrical charge. They are one of the fundamental particles that make up the universe. The spin of a particle refers to its intrinsic angular momentum, which is a fundamental property that determines how it behaves in the presence of magnetic fields. Understanding the spin of neutrinos is important because it can provide insight into their interactions and properties.

How is neutrino spin currently measured?

Currently, the most common method for measuring neutrino spin is through the observation of their decay products. This involves detecting the particles produced when a neutrino interacts with matter or antimatter, and analyzing their properties to determine the spin of the original neutrino. However, this method has limitations and can only provide limited information about the spin.

What are the limitations of measuring neutrino spin through decay?

One of the main limitations of measuring neutrino spin through decay is that it only provides information about the spin component along the direction of motion. This means that the full picture of the neutrino's spin cannot be obtained. Additionally, this method is only applicable to certain types of neutrinos, limiting its use in studying other types of neutrinos.

What are some potential measurement possibilities beyond decay for understanding neutrino spin?

There are several proposed methods for measuring neutrino spin beyond decay. These include using accelerator experiments to study neutrino interactions, using neutrino oscillations to probe spin, and developing new detection techniques such as measuring the polarization of photons produced in neutrino interactions. These methods could provide a more comprehensive understanding of neutrino spin.

How can a better understanding of neutrino spin benefit scientific research?

A better understanding of neutrino spin can have many benefits for scientific research. Neutrinos play a crucial role in many astrophysical processes, and understanding their spin could provide insight into these processes. Additionally, a more complete understanding of neutrino spin could also have implications for particle physics and our understanding of the fundamental laws of the universe.

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