Beryllium-10

Beryllium-10 Full table
General
Name, symbol	Beryllium-10,^10Be
Neutrons	6
Protons	4
Nuclide data
Natural abundance	trace
Half-life	1.387*10^6 12 y [1]
Spin	0+
Binding energy	6497.6318 keV
Decay mode	Decay energy
β^−	0.5560[1] MeV

Beryllium-10 (¹⁰Be) is a radioactive isotope of beryllium. It is formed mainly by the cosmic ray spallation of oxygen. Beryllium-10 has a half-life of 1.39 × 10⁶ years,^[2] and decays by beta decay to stable boron-10 with a maximum energy of 556.2 keV. It decays through the reaction ¹⁰Be->¹⁰B+e. Light elements in the atmosphere react with high energy galactic cosmic ray particles. The spallation of the reaction products is the source of ¹⁰Be (t, u particles like n or p):

¹⁴N(t,5u)¹⁰Be; Example: ¹⁴N(n,p α)¹⁰Be

¹⁶O(t,7u)¹⁰Be

Plot showing variations in solar activity, including variation in ¹⁰Be concentration which varies inversely with solar activity. (Note that the beryllium scale is inverted, so increases on this scale indicate lower beryllium-10 levels).

Because beryllium tends to exist in solutions below about pH 5.5 (and rainwater above many industrialized areas can have a pH less than 5), it will dissolve and be transported to the Earth's surface via rainwater. As the precipitation quickly becomes more alkaline, beryllium drops out of solution. Cosmogenic ¹⁰Be thereby accumulates at the soil surface, where its relatively long half-life (1.387 million years) permits a long residence time before decaying to ¹⁰B.

¹⁰Be and its daughter product have been used to examine soil erosion, soil formation from regolith, the development of lateritic soils and the age of ice cores.^[2] It is also formed in nuclear explosions by a reaction of fast neutrons with ¹³C in the carbon dioxide in air, and is one of the historical indicators of past activity at nuclear test sites.

References

1. National Nuclear Data Center, Brookhaven National Laboratory, Chart of Nuclides: ¹⁰Be information, Accessed 16-Oct-2013.
2. Balco, Greg; Shuster, David L. (2009). "²⁶Al-¹⁰Be–²¹Ne burial dating" (PDF). Earth and Planetary Science Letters 286: 570–575. Bibcode:2009E&PSL.286..570B. doi:10.1016/j.epsl.2009.07.025.