In the beta-ray decay, there are 3 types of decay processes in the beta rays, namely, (i) the core decay due to electron emission, denoted as β ^ -, (ii) the core decay due to emission of positrons, denoted as the β ^ +, and the last (iii) Arrest core by core electrons, called electron capture. All three types of processes are included in the beta decay process is often called Isobars change because all these processes do not make changes in the mass number A, ie, changes in mass numbers equal to zero. But it always happens the event causing the change in nuclear charge. Because a nucleus is always composed of neutrons and protons, then the conservation of electricity needed changes can be taken from the emission process β ^ -, a neutron in the nucleus that is converted into a proton. When the beta decay of radioactive nuclei, then the child has the same number of nuclei with nucleon as a core before.
Once again, note that the number of nucleons and the total charge are both conserved in the same state. However, as we shall see later, this process is not explained entirely by such expression. Note that in beta decay, a neutron turns into a proton, and it is also important to show that the electrons or positrons in the decay did not exist before in the core but by the time of exit decay, so that there is residual energy will be lost at the core. Now consider the energy of the system before and after the decay. As with the alpha decay, we assume that energy is conserved and that the heavy recoiling daughter nuclei carry negligible kinetic energy. In experiments, it was found that the beta particles of one type of nucleus that is emitted, with a continuous range of kinetic energies up to some maximum value, Kmax.
Beta particle is a subatomic particle is thrown from an unstable atomic nucleus - beta. Particle is equivalent to an electron and a single negative electric charge-e (-1.6 x 10-19 C) and has a mass of very small (0.00055 atomic mass units) or only about 1 / 2000 of the mass of a neutron or a proton. The difference is that the beta particles originating from the nucleus while the electrons originating from outside the core. The speed of the beta particles is varied depending on the energy possessed by every - every particle. Because of considerations - theoretical considerations do not permit an independent existence and of intra-nuclear electrons, it is postulated that the particles formed at the time of transmission by the transformation of a neutron into a proton and an electron according to the equation
01n-10e + 11H -------->
Transformation shows that the decrease in beta occur between isotopes - an isotope which has the excess number of neutrons. So that the excess neutrons are transformed into protons and electrons as described above, protons resulting from the transformation will remain at the core, while the electrons produced will be thrown with high energy. This process will result in the number of neutrons from an atom is reduced by one while the number of protons increases by one. Because the number of protons of an atom determines the element, then the transformation of neutrons into protons will change these radionuclides into another element. As an example the transformation of radioactive phosphorus to sulfur stabilized in accordance with the equation:
--------> 16 15 32P 32s + -1 0e + 1.71 MeV
Can be noted that - as already mentioned, during the beta transformation, there is one negative charge is lost, and because the mass of the beta particles are much smaller than 1 amu (atomic mass units), then the seedling will have a core of atomic number greater than the number 1 amu parent atoms, whereas the mass number will remain 32 amu. Energy transformation in this example at 1.71 MeV is the energy equivalent to the difference in mass between nuclei 32P and 32s plus the number of nuclei Beta particles. This energy appears as kinetic energy of beta particles.
Of beta decay experiments revealed that the beta particles emitted by a continuous distribution ranging from zero to the value expected theoretically based on a consideration - the consideration of energy - mass to specific beta transitions, rather than mono-energitik as well as alpha particles. Another anomaly is the fact that the nuclear recoil is not in the opposite direction to the electron momentum. In 1930, Pauli proposed a hypothesis about the existence of a particle called neutrinos that accompany the beta particles whose energy is equal to the difference between the kinetic energy of beta particles accompanying the maximum of the distribution and energy spectrum, neutrino - such as those postulated to be uncharged and have a mass an infinitely small, so with these characteristics then these particles will be very difficult to detect. However, proving the existence of these particles is then achieved experimentally in 1950. So the equation must be modified to become a beta transformation
--------> 01n-10e + 11H + ν
with ν is the neutrino
Phosphorus-32, like other beta transmitters which include H-3, C-14, Y-90, does not emit gamma rays (called a pure beta emitter). Opponents of the transmitter is a pure beta-emitting beta - gamma (beta particles (immediately) followed by emission of gamma rays) in this case the core of puppies after beta-ray emission is left in the activated state, and keumdian activation energy is released through pemacaran gamma rays. One example of beta-gamma emitting isotopes is Hg-203
Penetrating power of beta particles to penetrate the network depends on the particle's energy, so the beta particle radiation is also an external radiation hazard if it has an energy above 200 keV so that the level of hazard must be evaluated for each case. Ray - beta rays with energy less than 200 keV are not considered as an external radiation hazard because it has a very limited penetrating power as well as S-35 and C-14. But to note is that the rays - will trigger the beta rays X-ray bremsstrahlung of the high penetrating power if it is stopped through the shielding is not designed properly and measures - appropriate preventive measures are not taken.
Direct irradiation of the beta particles is karane harmful emissions from a strong beta emitter can be heated or even burn the skin.
However, beta-emitting entry through the inhalation of air becomes a serious concern for beta particles are emitted directly into the living tissue that can cause harm at the molecular level that can disrupt cell function. Because beta particles are so small and has a charge smaller than alpha particles beta particles in general it will penetrate into the tissue, resulting in more severe cell damage.
Kinetic energy after the decay of the same system with a decrease in the mass-energy of the system of core values, Q. However, since all the core holding of certain types have the same initial mass of the equation is valid for a magnetic beta-ray spectrometer of all kinds. After many experimental and theoretical studies, Pauli in 1930 suggested that a third particle must be present to transport energy and momentum lost. Fermi later named this particle, the neutrino (little neutral one) because it must be neutral and has a mass a little longer. Although able to escape the various forms of detection for years, neutrinos (denoted by v) finally detected experimentally in 1956. It has the following properties
- Weak Electric Charge
- Rest mass is much smaller than the electron. Recent research suggests that the neutrino mass is not 0 but less than 2.8 eV.
- Very weak interaction with matter, which makes it very difficult to detect.
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