Understanding Tritium and Radioactive Decay

Tritium is a naturally occurring radioactive isotope of hydrogen. It is denoted as $^{3}\text{H}$ or sometimes as T. Unlike the common hydrogen isotope ($^{1}\text{H}$) and deuterium ($^{2}\text{H}$), Tritium has two neutrons and one proton in its nucleus, making it unstable. Radioactive isotopes undergo radioactive decay, which is the process by which an unstable atomic nucleus loses energy by emitting radiation, such as alpha particles, beta particles, gamma rays, or positrons.

Tritium Decay Process

The stability of an atomic nucleus depends on the balance between protons and neutrons. Isotopes that have an excess of neutrons relative to protons tend to undergo beta decay. Tritium has 1 proton and 2 neutrons, while the stable isotope of Helium, $^{3}\text{He}$, has 2 protons and 1 neutron. This suggests that Tritium is neutron-rich and is likely to convert a neutron into a proton.

Beta decay ($\beta$-emission) is a type of radioactive decay in which a beta particle (either an electron or a positron) is emitted from an atomic nucleus. There are two types of beta decay:

• Beta-minus decay ($\beta^-$): A neutron in the nucleus is converted into a proton, an electron (the beta particle), and an electron antineutrino. This process increases the atomic number by one while keeping the mass number the same.
• Beta-plus decay ($\beta^+$) or Positron Emission: A proton in the nucleus is converted into a neutron, a positron (the beta particle), and an electron neutrino. This process decreases the atomic number by one while keeping the mass number the same.

Gamma decay ($\gamma$-emission) involves the emission of a high-energy photon from an excited nucleus, usually following another type of decay. Alpha decay ($\alpha$-emission) involves the emission of an alpha particle (a helium nucleus, $^{4}\text{He}$) and typically occurs in very heavy nuclei.

Analyzing Tritium Decay Mechanism

Since Tritium ($^{3}\text{H}$) has 1 proton and 2 neutrons, it is neutron-rich compared to the stable $^{3}\text{He}$ (2 protons, 1 neutron). Therefore, Tritium undergoes beta-minus decay, where a neutron is transformed into a proton, an electron, and an electron antineutrino. The decay equation for Tritium is:

\( _{1}^{3}\text{H} \rightarrow _{2}^{3}\text{He} + e^{-} + \bar{\nu}_e \)

Here:

• \(_{1}^{3}\text{H}\) is the Tritium nucleus (1 proton, 2 neutrons).
• \(_{2}^{3}\text{He}\) is the resulting Helium-3 nucleus (2 protons, 1 neutron).
• \(e^{-}\) is the emitted electron (beta particle).
• \(\bar{\nu}_e\) is the emitted electron antineutrino.

This equation shows that Tritium decays by emitting an electron, which is a beta particle. This confirms that Tritium decays via beta-emission.

Conclusion on Tritium Decay

Based on its nuclear composition and the nature of radioactive decay processes, Tritium decays through the emission of a beta particle. This is specifically beta-minus decay.

Therefore, Tritium decays by $\beta$-emission.