Neutrinos-Antineutrinos in the universe

[omiros]

Hello everybody, I am a first year physics student and I have a question about neutrinos and antineutrinos.

In a beta minus decay we will get an antineutrino, so I assume that Earth 'produces' more antineutrinos. Does it?

However from a beta plus we get neutrinos and positrons. So does that mean that we had more protons in the beginning that started becoming neutrons? Do the neutrinos that we find now, were mostly created after the big bang?

Do neutrino detectors detect antineutrinos too?

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Does that mean that the number of the electrons in stars etc is getting smaller, cause of positrons? (random)

 

[Bill_K]

Do the neutrinos that we find now, were mostly created after the big bang?

Most of the neutrinos we detect are solar neutrinos coming from p + P → d + e⁺ + ν. Neutrinos from the big bang are known as relic neutrinos and are too low energy to be detectable.

 

[mfb]

A few neutrinos from supernovae and other cosmic events can be detected, together with atmospheric neutrinos (produced by cosmic rays hitting our atmosphere) and nuclear reactor antineutrinos (beta- decays, so just antineutrinos).

Similar to the cosmic microwave background, primordial neutrinos (= from the big bang) lost energy during the expansion of space, so current detectors are not sensitive enough to see them.

 

[IsometricPion]

In a beta minus decay we will get an antineutrino, so I assume that Earth 'produces' more antineutrinos. Does it?

The Earth does produce antineutrinos; they are from the decay of radioactive nuclei (http://www.physicstoday.org/resource/1/phtoad/v64/i9/p14_s1). I am sure the Earth produces neutrinos as well, but I am not aware of a similar measurement for them.

Do neutrino detectors detect antineutrinos too?

It depends on the method they are using for detection (Wikipedia- Neutrino detector).

 

[Buzz Bloom]

Hi Bill:

Most of the neutrinos we detect are solar neutrinos coming from p + P → d + e+ + ν.

Is the "P" here a typo where "p" was intended? If not, whar does "P" mean?

 

[ChrisVer]

Do neutrino detectors detect antineutrinos too?

It depends on what and how you want to measure in neutrino detectors and what detectors you are using.

 

[mfb]

Is the "P" here a typo where "p" was intended? If not, whar does "P" mean?

It was a two year old typo (and as the thread is very old, I'll close it, feel free to discuss in other threads or open a new one).

Actually, it was not correct either because neutrinos from that particular reaction are very low-energetic and hard to detect, that was achieved for the first time in 2014.