Positronenzerfall

Positronenzerfall, also known as beta-plus decay or β+ decay, is a type of radioactive decay where an atomic nucleus emits a positron. A positron is the antiparticle of an electron, possessing the same mass but a positive electric charge. This process occurs in proton-rich nuclei, where an excess of protons destabilizes the atom. During positronenzerfall, a proton within the nucleus transforms into a neutron, an electron neutrino, and a positron. The positron is then ejected from the nucleus.

The general equation for positronenzerfall is p + → n + e+ + νe, where 'p' represents a proton, 'n' a neutron, 'e+' a positron, and 'νe' an electron neutrino. This transformation results in a decrease in the atomic number of the nucleus by one, while its mass number remains unchanged. For example, Carbon-11 decays via positronenzerfall into Boron-11.

Positronenzerfall is a fundamental process in nuclear physics and has important applications in medical imaging, particularly in Positron Emission Tomography (PET) scans. In PET, radioactive isotopes that undergo positronenzerfall are introduced into the body, and the emitted positrons annihilate with electrons, producing gamma rays that are detected by the scanner. This allows for the visualization of metabolic processes within the body. The energy of the emitted positron is typically quite low, and it quickly encounters an electron in the surrounding matter, leading to annihilation.