Big Bang nucleosynthesis amounts of the hydrogen isotope deuterium (H or D), the helium isotope helium-3 (He), and a very small amount of the lithium isotope lithium-7 (Li). In addition to these stable nuclei, two unstable or radioactive isotopes were also produced: the heavy hydrogen isotope tritium (H or T); and the beryllium isotope beryllium-7 (Be); but these unstable isotopes later decayed into He and Li, as above. Essentially all of the elements that are heavier than lithium were created much later, by stellar nucleosynthesis in evolving and exploding stars. There are several important characteristics of Big Bang nucleosynthesis (BBN): The key parameter
Tritium radioluminescence for night use and small lights (which need to be more reliable than battery powered lights yet not interfere with night vision or be bright enough to easily give away one's location) used mostly by military personnel fall under the latter application. Tritium lighting is made using glass tubes with a phosphor layer in them and tritium gas inside the tube. Such a tube is known as a "gaseous tritium light source" (GTLS), or "beta light" (since the tritium undergoes beta decay). The tritium in a gaseous tritium light source undergoes beta decay, releasing electrons that cause the phosphor layer