Boron (5B) naturally occurs as isotopes 10Boron and 11Boron, the latter of which makes up about 80% of natural boron. There are 13 radioisotopes that have been discovered, with mass numbers from 7 to 21, all with short half-lives, the longest being that of 8Boron, with a half-life of only 771.9 ms and 12Boron with a half-life of 20.2 ms. All other isotopes have half-lives shorter than 17.35 ms. Those isotopes with mass below 10 decay into helium (via short-lived isotopes of beryllium for 7Boron and 9Boron) while those with mass above 11 mostly become carbon.

List of isotopes

Boron-8

Boron-8 is an isotope of boron that undergoes β+ decay to beryllium-8 with a half-life of 771.9 ms. It is the strongest candidate for a halo nucleus with a loosely-bound proton, in contrast to neutron halo nuclei such as lithium-11. Although neutrinos from boron-8 beta decays within the Sun make up only about 80 ppm of the total solar neutrino flux, they have a higher energy centered around 10 MeV, and are an important background to dark matter direct detection experiments. They are the first component of the neutrino floor that dark matter direct detection experiments are expected to eventually encounter.

Applications

Boron-10

Boron-10 is used in boron neutron capture therapy as an experimental treatment of some brain cancers.