In a nuclear reaction n-> p + e- electric charge and energy can be conserved but spin angular momentum is definitely violated. This is because left hand side has a half integral spin whereas in the right hand side, summing spins yield integral values. Thus it needs to be a three body decay where the third fermion has somehow escaped detection. Also from the energy spectrum (plot of number of events vs energy of the emitted electron) of emitted beta particle one sees that the spectrum is a continuous smooth curve with a characteristic shape. See the figure below.

Using these two facts, Pauli postulated (1930) the existence of a missing spin half particle which is also being emitted in this reaction and which should be there to conserve energy and angular momentum. The name neutrino was given by Fermi in 1932. Because the three body process n -> p + e- + antineutrino is just the well known beta decay process, it can surely change atomic structure of the substance from which it is emitted.

Further reading: http://www.astro.wisc.edu/~larson/Webpage/neutrinos.html

"Using there two facts, Pauli postulated (1930) the existence of a missing spin half particle which is also being emitted in this reaction and which should be there to conserve energy and angular momentum."

Although this is something I've known for serveral years this additional idea has popped to me: the neutrinos embody the half spin h/2 ,  they are pure angular momentum which is action, since they have no charge.. It is fascinating to know that our Sun emits pure Action.

"And mass-energy, so it's not pure action."

the mass of neutrinos is not a Crystal clear topic.

Nuclear reactors do it too, 4.5% of power from a reactor is lost as neutrinos.

...yes like geo neutrinos from earth core. 4.5% is very much though.

@ Remi Cornwall

I give a little thought to the Neutrinos.  In my theory, tt seems that you can go from one type of Neutrino to another by electron capture, instead of oscillation.  Is there a proof that there is an actual oscillation? That is, did someone measure the neutrino composition along a distance and saw the oscillation, measured the wavelength of that oscillation

Neutrino beams are produced in particle accelerators. They offer a great control over type of neutrino that is being studied. Such neutrinos are in GeV energy range and they are studied over a few hundred kilometers of baseline. MINOS, K2K and SuperK experiments have observed muon neutrino disappearance over such baselines.

In 2010, in a laboratory 732 km away from Geneva, tau particle was first detected in a muon neutrino beam by OPERA detector.

ref:

@Biswajoy Brahmachari

The disappearance of Muon neutrino doesn't eliminate the possibility of transforming into another neutrino for electron-loss in this case.  

My question has to do if these muon neutrinos that disappeared at a given range, appeared back if you look further down.  That would be a proof of an oscillation.  Disappearance is a proof of decay 

Using atmospheric decay events it is difficult to distinguish between decay scenario and oscillation scenario. In Long baseline experiments they can be distinguished, by studying dependence of probability "P" of appearance (or not-appearing "1-P")  as a function of L/E. For decay models dependence is exponential and for oscillation models it is sinusoidal.

"In a nuclear reaction n-> p + e- electric charge and energy can be conserved but spin angular momentum is definitely violated. This is because left hand side has a half integral spin whereas in the right hand side, summing spins yield integral values. Thus it needs to be a three body decay where the third fermion has somehow escaped detection."

I repeat: it is clear that the Neutrino existence comes from the conservation of the angular momentum and angular momentum is "pure action" = h/2.

What is left or radiated has to have a dimension of a pure action nothing else...I do not see what is wrong with this statement....this would explain why the neutrino is also so elusive....