Atmospheric Neutrino: Pion Decay to Muon & Muon Neutrino

  • Thread starter Kolahal Bhattacharya
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In summary, atmospheric neutrinos are a type of neutrino particle created in the Earth's atmosphere through the decay of pions produced by high-energy cosmic rays. They are difficult to study directly but can provide important information about high-energy cosmic rays and the properties of neutrinos. These particles are detected using large underground detectors and play a crucial role in particle physics research, providing a unique source of high-energy neutrinos for studying fundamental properties and understanding the origins and behavior of high-energy cosmic rays.
  • #1
Why does pions(coming through atmosphere) decays into a muon and a muon neutrino, not directly into electron and lelectron neutrino?I know it's because splin angular momentum conservation...but I need to be more clear about it.
 
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  • #2
Actually some of the pions do decay directly into electron and anti-neutrino (or positron and neutrino). But the branching ratio for this process is very small- only about 1%.

To explain this, please read:http://hyperphysics.phy-astr.gsu.edu/hbase/particles/hadron.html" [Broken]

And Griffiths' book on particle physics also has a very good discussion.

Cheers.
 
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  • #3


The decay of pions (coming through the atmosphere) into a muon and a muon neutrino, rather than directly into an electron and an electron neutrino, is due to the conservation of spin angular momentum. This concept is based on the principle of conservation of angular momentum, which states that the total angular momentum of a system remains constant unless acted upon by an external torque.

In the case of pion decay, the initial state of the pion is a spin-0 particle, while the final state is a spin-1/2 particle (muon) and a spin-1/2 particle (muon neutrino). According to the law of conservation of spin, the total spin angular momentum of the system must remain the same before and after the decay.

If the pion were to directly decay into an electron and an electron neutrino, the total spin angular momentum of the system would not be conserved. This is because the electron has a spin of 1/2, while the electron neutrino has a spin of 1/2 as well, resulting in a total spin angular momentum of 1. However, the initial pion only has a spin of 0, which means that the total spin angular momentum would not be conserved.

In order to conserve spin angular momentum, the pion must decay into a spin-1/2 particle (muon) and a spin-1/2 particle (muon neutrino) with opposite spins, resulting in a total spin angular momentum of 0. This is in accordance with the law of conservation of spin and explains why pions decay into a muon and a muon neutrino rather than directly into an electron and an electron neutrino.

In summary, the conservation of spin angular momentum is the reason why pions decay into a muon and a muon neutrino, not directly into an electron and an electron neutrino. This principle plays a crucial role in understanding the behavior of subatomic particles and their interactions.
 

1. What is an atmospheric neutrino?

An atmospheric neutrino is a type of neutrino particle that is created in the Earth's atmosphere through the decay of pions, which are produced by high-energy cosmic rays interacting with the air molecules. These neutrinos have a wide range of energies and can travel great distances before interacting with other particles.

2. How are atmospheric neutrinos created?

Atmospheric neutrinos are created through the decay of pions, which are produced when high-energy cosmic rays, such as protons or nuclei, collide with air molecules in the Earth's atmosphere. These pions then quickly decay into muons and muon neutrinos, which can be detected by scientists.

3. What is the significance of studying atmospheric neutrinos?

Studying atmospheric neutrinos can provide important information about the composition and behavior of high-energy cosmic rays, which are difficult to study directly. It can also help us understand the properties and interactions of neutrinos, which are one of the most abundant particles in the universe but are difficult to detect due to their weak interactions with matter.

4. How are atmospheric neutrinos detected?

Atmospheric neutrinos are detected using large underground detectors, such as the Super-Kamiokande detector in Japan. These detectors are filled with a transparent medium, such as water or ice, and surrounded by sensitive photodetectors. When a neutrino interacts with the medium, it produces a faint flash of light that can be detected by the photodetectors.

5. What is the role of atmospheric neutrinos in particle physics research?

Atmospheric neutrinos play a crucial role in particle physics research as they provide a unique source of high-energy neutrinos, which can be used to study the fundamental properties of these particles. They can also help us understand the origins and behavior of high-energy cosmic rays, which are important for understanding the structure and evolution of our universe.

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