Beryllium-8

Beryllium-8 (Be-8) is an isotope of beryllium, a chemical element with the atomic number 4. It consists of 4 protons and 4 neutrons in its nucleus. Beryllium-8 is unstable and has a very short half-life of about 7.6 x 10^-17 seconds, which means it decays rapidly into other particles.