Beta plus decay is a type of radioactive decay where a proton inside the nucleus of an atom transforms into a neutron, and the nucleus emits a positron (the antimatter counterpart of an electron) and a neutrino.
Understanding Beta Plus Decay
In essence, beta plus decay weakens the "proton-richness" of a nucleus, bringing it closer to stability. Here's a breakdown of the process:
- Initial State: A nucleus with too many protons relative to neutrons.
- Process: One proton within the nucleus converts into a neutron. This conversion also results in the emission of:
- Positron (e+): A positively charged particle with the same mass as an electron.
- Neutrino (νe): A nearly massless, neutral elementary particle.
- Final State: A nucleus with one less proton and one more neutron. The atomic number decreases by one, but the mass number remains the same. The emitted positron and neutrino carry away energy.
Key Characteristics
- Proton to Neutron Conversion: The defining feature of beta plus decay is the transformation of a proton into a neutron within the nucleus.
- Positron Emission: The emitted positron interacts with an electron in a process called annihilation, producing two gamma-ray photons.
- Neutrino Emission: The neutrino interacts very weakly with matter, making it difficult to detect.
- Atomic Number Change: The atomic number of the nucleus decreases by one, meaning a different element is formed.
- Mass Number Invariance: The mass number of the nucleus remains unchanged.
Example
Imagine a radioactive isotope of Carbon-11 (11C). It undergoes beta plus decay:
11C → 11B + e+ + νe
Carbon-11 (11C) decays into Boron-11 (11B), a positron (e+), and a neutrino (νe).
Why Does Beta Plus Decay Occur?
Beta plus decay occurs when the nucleus has too many protons relative to neutrons for stability. The process reduces the positive charge in the nucleus, moving it closer to a more stable configuration. The parent nucleus has an excitation energy exceeding the mass energy of the daughter nucleus.
