Boron (5B) naturally occurs as isotopes and , 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 , with a half-life of only and with a half-life of . All other isotopes have half-lives shorter than . Those isotopes with mass below 10 decay into helium via short-lived isotopes of beryllium while those with mass above 11 mostly become carbon.
List of isotopes
|-id=Boron-7 | | style="text-align:center" | 5 | style="text-align:center" | 2 | | style="text-align:center" | 1967 | [] | p | Subsequently decays by double proton emission to for a net reaction of → + 3 | (3/2−)
| Has 1 halo protonIntermediate product of a branch of proton–proton chain in stellar nucleosynthesis as part of the process converting hydrogen to helium | style="text-align:center" | 5 | style="text-align:center" | 3 | | style="text-align:center" | 1950 | | β+ | Immediately decays into two α particles, for a net reaction of → 2 + | 2+
|-id=Boron-9 | | style="text-align:center" | 5 | style="text-align:center" | 4 | | style="text-align:center" | 1940 | | p | | Immediately decays into two α particles, for a net reaction of → 2 + | 3/2−
| One of the few stable odd-odd nuclei | style="text-align:center" | 5 | style="text-align:center" | 5 | | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 3+ | colspan=2 align=center|[, ] |-id=Boron-11 | | style="text-align:center" | 5 | style="text-align:center" | 6 | | style="text-align:center" | 1920 | colspan=3 align=center|Stable | 3/2− | colspan=2 align=center|[, ]
|-id=Boron-12 | rowspan=2| | rowspan=2 style="text-align:center" | 5 | rowspan=2 style="text-align:center" | 7 | rowspan=2| | rowspan=2 style="text-align:center" | 1935 | rowspan=2| | β− () | | rowspan=2|1+ | rowspan=2| | rowspan=2| |- | β−α () | Immediately decays into two α particles, for a net reaction of → 3 + |-id=Boron-13 | rowspan=2| | rowspan=2 style="text-align:center" | 5 | rowspan=2 style="text-align:center" | 8 | rowspan=2| | rowspan=2 style="text-align:center" | 1956 | rowspan=2| | β− () | | rowspan=2|3/2− | rowspan=2| | rowspan=2| |- | β−n () | |-id=Boron-14 | rowspan=3| | rowspan=3 style="text-align:center" | 5 | rowspan=3 style="text-align:center" | 9 | rowspan=3| | rowspan=3 style="text-align:center" | 1966 | rowspan=3| | β− () | | rowspan=3|2− | rowspan=3| | rowspan=3| |- | β−n ()
| β−2n ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
|-id=Boron-15 | rowspan=3| | rowspan=3 style="text-align:center" | 5 | rowspan=3 style="text-align:center" | 10 | rowspan=3| | rowspan=3 style="text-align:center" | 1966 | rowspan=3| | β−n () | | rowspan=3|3/2− | rowspan=3| | rowspan=3| |- | β− (< )
| β−2n (< ) | |-id=Boron-16 | | style=text-align:center | 5 | style=text-align:center | 11 | | style=text-align:center | 2000 | > | n ? | | 0−
|-id=Boron-17 | rowspan=5|Has 2 halo neutrons | rowspan=5 style=text-align:center | 5 | rowspan=5 style=text-align:center | 12 | rowspan=5| | rowspan=5 style="text-align:center" | 1973 | rowspan=5| | β−n () | | rowspan=5|(3/2−) | rowspan=5| | rowspan=5| |- | β− ()
| β−2n ()
| β−3n ()
| β−4n () | |-id=Boron-18 | | style=text-align:center | 5 | style=text-align:center | 13 | | style=text-align:center | 2010 | < | n | | (2−)
|-id=Boron-19 | rowspan=4|Has 4 halo neutrons | rowspan=4 style=text-align:center | 5 | rowspan=4 style=text-align:center | 14 | rowspan=4| | rowspan=4 style="text-align:center" | 1984 | rowspan=4| | β−n () | | rowspan=4|(3/2−) | rowspan=4| | rowspan=4| |- | β−2n ()
| β−3n (< )
| β− (> ) | |-id=Boron-20 | | style=text-align:center | 5 | style=text-align:center | 15 | | style=text-align:center | 2018 | > | n | | (1−, 2−)
|-id=Boron-21 | | style=text-align:center | 5 | style=text-align:center | 16 | | style=text-align:center | 2018 | > | 2n | | (3/2−)
Boron-8
Boron-8 is an isotope of boron that undergoes β+ decay to beryllium-8 with a half-life of . 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 boron-8 beta decay neutrinos from 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.
See also Daughter products other than boron Isotopes of carbon Isotopes of beryllium Isotopes of helium
References