What is beta decay 1

Beta decay

One of the three forms of radioactivity besides alpha and gamma decay. In the case of radioactivity, certain atomic nuclei (technical term: Radionuclides) certain matter particles (electrons, positrons, helium atomic nuclei, also neutrons) or high-energy, electromagnetic radiation. Radioactivity is dangerous to life due to its strong ionizing effect! In some cases, radioactivity can be shielded and thus 'defused' with simple means.

What exactly is β-decay?

  • At the β--Decay A (bound) neutron in the atomic nucleus decays into a proton, an electron and an anti-electron neutrino (note conservation of the lepton number!). Here the electrons are identified with the beta radiation.
  • At the β+-Decay a (bound!) Proton in the atomic nucleus decays into a neutron, a positron (the antiparticle of the electron) and an electron neutrino.

The β radiation has a longer range than the alpha radiation, but can already be shielded by a thin sheet of aluminum. However, like all forms of radioactivity, this radiation is dangerous!

Weak, but great!

Only through the quantum theory or quantum field theory of weak interaction was this form of radioactivity calculable and explainable. In the case of the weak force, messenger particles (Calibration bosons) exchanged. In both forms of β-decay they change the internal structure of the neutron or proton. As a reminder: protons and neutrons are the particles that are in the atomic nucleus. Hence they are called nucleons. To be precise, there is a positively and a negatively charged W-particle that convey the weak force. If they are exchanged, they change the quark content of the nucleons according to the conservation laws of electrical charge etc. In the theory of weak interaction, the W-particles are also called charged currents (W.+ and W.-). In addition, there is the neutral current (Z-particle Z0), its decay experimental the number of three generations of leptons reveals.

Neutronization of stars

The β-decay can also take place in the opposite direction of the reaction. This inverse β-decay is particularly important at extremely high central densities inside stars, from around 1.14 × 109 g cm-3. In practice, this is only relevant for compact objects, because 'normal' main sequence stars or protostars do not reach this density domain. In particular, the inverse β-decay takes place inside white dwarfs and especially neutron stars.