This chapter of Astrophysics in a Nutshell covered the proton-proton chain and how that reaction powers the Sun and other stars. One consequence of the p-p chain that I thought was interesting was the release of neutrinos. This occurs in the first, rate-limiting step of the p-p chain:
\[p+p\rightarrow d+e^++\nu_e.\]The \(\nu_e\) is the neutrino.
Neutrinos are interesting for a lot of reasons. In basic terms, they're very similar to electrons, except they are uncharged (although there are two other types of neutrinos that are more closely related to two other subatomic particles). This means that they're critically different from electrons in that they are not affected by the electromagnetic forces. Because of this, they can travel for vast distances before interacting with any other particles--the mean free path of a neutrino is on the order of 1018 cm! While this property makes them useful for carrying information from astronomical events vast distances away, it also makes neutrinos very difficult to detect.
One way of detecting neutrinos is by observing its effects on the few particles that it does hit. If a neutrino collides with an atom with high enough energy, the atom will be burst into its constituent protons and neutrons. These particles can be detected by machines such as the Large Hadron Collider. Neutrino collisions with quarks can yield different particles which can also be detected. Regardless of the huge flux of neutrinos from the Sun, we've still detected very few neutrinos, so improvements in our technology will greatly benefit this field.
Sources
Astrophysics in a Nutshell, Dan Moaz
http://www.ps.uci.edu/~superk/neutrino.html
https://icecube.wisc.edu/info/neutrinos
http://profmattstrassler.com/2011/09/25/how-to-detect-neutrinos/
Nice focused post
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