Editing Beta particle (section)

== Interaction with other matter ==

[[File:TrigaReactorCore.jpeg|thumb|250px|Blue [[Cherenkov radiation]] light being emitted from a [[TRIGA]] reactor pool is due to high-speed beta particles traveling faster than the speed of light ([[phase velocity]]) in water (which is 75% of the speed of light in vacuum).]]Of the three common types of radiation given off by radioactive materials, [[Alpha particle|alpha]], beta and [[Gamma ray|gamma]], beta has the medium penetrating power and the medium ionising power. Although the beta particles given off by different radioactive materials vary in energy, most beta particles can be stopped by a few millimeters of [[aluminium]]. However, this does not mean that beta-emitting isotopes can be completely shielded by such thin shields: as they decelerate in matter, beta electrons emit secondary gamma rays, which are more penetrating than betas per se. Shielding composed of materials with lower atomic weight generates gammas with lower energy, making such shields somewhat more effective per unit mass than ones made of larger atoms such as lead.

Being composed of charged particles, beta radiation is more strongly ionizing than gamma radiation. When passing through matter, a beta particle is decelerated by electromagnetic interactions and may give off [[bremsstrahlung]] [[X-ray]]s.

In water, beta radiation from many [[nuclear fission product]]s typically exceeds the speed of light in that material (which is about 75% that of light in vacuum),<ref>The macroscopic speed of light in water is 75% of the speed of light in vacuum (called ''c''). The beta particle is moving faster than 0.75 c, but not faster than c.</ref> and thus generates blue [[Cherenkov radiation]] when it passes through water. The intense beta radiation from the fuel rods of [[swimming pool reactor]]s can thus be visualized through the transparent water that covers and shields the reactor (see illustration at right).

=== Detection and measurement ===
[[File:Beta radiation in a cloud chamber.jpg|thumb|300px|Beta radiation detected in an isopropanol [[cloud chamber]] (after insertion of an artificial source [[strontium-90]])]]
The ionizing or excitation effects of beta particles on matter are the fundamental processes by which radiometric detection instruments detect and measure beta radiation. The ionization of gas is used in [[ionization chamber|ion chambers]] and [[Geiger counter|Geiger–Müller counters]], and the excitation of [[scintillator]]s is used in [[scintillation counter]]s.
The following table shows radiation quantities in SI and non-SI units:
{{Radiation related quantities}}

* The [[gray (unit)|gray]] (Gy)  is the SI unit of [[absorbed dose]], which is the amount of radiation energy deposited in the irradiated material. For beta radiation this is numerically equal to the [[equivalent dose]] measured by the [[sievert]], which indicates the stochastic biological effect of low levels of radiation on human tissue. The radiation weighting conversion factor from absorbed dose to equivalent dose is 1 for beta, whereas alpha particles have a factor of 20, reflecting their greater ionising effect on tissue.
* The [[rad (unit)|rad]] is the deprecated [[CGS]] unit for absorbed dose and the [[Röntgen equivalent man|rem]] is the deprecated [[CGS]] unit of equivalent dose, used mainly in the USA.

=== Beta spectroscopy ===
The energy contained within individual beta particles is measured via ''beta spectrometry''; the study of the obtained distribution of energies as a [[spectrum]] is ''beta spectroscopy''. Determination of this energy is done by measuring the amount of deflection of the electron's path under a magnetic field.<ref>{{cite web |last1=Boeglin |first1=Werner |title=4. Beta Spectroscopy — Modern Lab Experiments documentation |url=https://wanda.fiu.edu/boeglinw/courses/Modern_lab_manual3/beta_spectroscopy.html |website=wanda.fiu.edu}}</ref>