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Beta particles are high-energy Electron s or Positron s emitted by certain types of Radioactive Nuclei such as Potassium -40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed Beta Decay . They are designated by the Greek Letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the Electron and the Positron . &BETA;<SUP>&MINUS;</SUP> DECAY (ELECTRON) Unstable atomic nuclei with an excess of neutrons may undergo β− decay, where a Neutron is converted into a Proton , an electron and an electron-type antineutrino (the Antiparticle of the Neutrino ): A W minus Boson is emitted from the nucleus which then decays into an electron and an antineutrino. It does this by converting one of the two up quarks in the proton into a down quark, leaving two down quarks and one up quark (a Neutron) to convert an up quark into a down quark a -1 charge is carried away to observe charge conservation (the W- boson, then the electron, as an up quark carries a charge of +2/3 and the down quark has a charge of -1/3; this quark is said to have undergone a flavor change) &BETA;<SUP>+</SUP> DECAY (POSITRON) Unstable nuclei that are deficient in neutrons may undergo β+ decay, where a proton is converted into a neutron. The proton consists of two up quarks and a down quark, one of the proton up quarks decays to a down quark, doing so, it will emit a W particle, which is unstable and decays further into a positron and an electron neutrino: The positron and the neutrino are emitted from the nucleus. THE NEUTRINO AND CONSERVATION OF ENERGY Due to the presence of the neutrino, the atom and the beta particle do not usually Recoil in opposite directions. This observation led Wolfgang Pauli to postulate the existence of neutrinos in order to prevent violation of conservation of Energy and Momentum laws. Beta decay is mediated by the Weak Nuclear Force . Beta particles may be stopped by a few millimeters of Aluminium . A beta particle's flight is ten times farther than an alpha particle, as it ionizes a tenth less than an alpha particle. The beta particle can produce gamma rays when passing through lead, so lighter materials are preferred as shielding. USES Beta particles can be used to treat health conditions such as eye and bone cancer. As well as being used as tracers. The main element for these jobs is Strontium-90. 'Strontium- 90' Strontium-90 is used as a radioactive tracer in medical and agricultural studies. The heat generated by strontium-90's radioactive decay can be converted to electricity for long-lived, light-weight power supplies (see Radioisotope Thermoelectric Generator ). These are often used in remote locations, such as in navigational beacons, weather stations, and space vehicles. Strontium-90 is also used in electron tubes, as a radiation source in industrial thickness gauges, and for the treatment of eye diseases. Controlled amounts of strontium-90 have been used as a treatment for bone cancer. 'Technetium-99' Technetium-99 is also used as a tracer in medicine as a gamma-free source of beta particles. The half-life of Technetium-99 is relatively low, meaning that the damage to the body is limited. REFERENCES http://www.epa.gov/radiation/radionuclides/strontium.htm SEE ALSO
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