Applications of radioactivity

Despite its sinister reputation, radioactivity has a great many positive applications, from medicine to space exploration. Each one exploits a specific property of a well-chosen isotope: its energy, its mean life, the type of radiation it emits.

• Medicine: PET imaging with ${}^{18}$F, thyroid therapy with ${}^{131}$I, tumour radiotherapy with ${}^{60}$Co, brachytherapy with implanted sources.
• Dating: ${}^{14}$C for archaeology ($0$–$50$ ka), ${}^{40}$K/${}^{40}$Ar for rocks of $10^6$–$10^9$ years, U/Pb for rocks of $10^7$–$4{,}5\cdot 10^9$ years — this is how the age of the Earth was measured.
• Energy: fission reactors (about $10\%$ of the world’s electricity) and experimental fusion plants on the horizon.
• Safety: household smoke detectors use ${}^{241}$Am, whose $\alpha$ radiation ionises the air; smoke reduces the ionic current and triggers the alarm.
• Space exploration: radioisotope thermoelectric generators (RTGs, with ${}^{238}$Pu) power probes too far from the Sun to use solar panels (Voyager 1 and 2, New Horizons).

The common thread is that the same physics — unstable nuclei transforming while releasing energy and radiation — can cure a tumour, date a rock, or power a probe at the edge of the solar system. The difference lies in the use chosen for it.

Collegamenti

Argomenti: Fisica nucleare Concetti: Decadimento radioattivo · Fissione nucleare

Esercizi collegati: Esercizio svolto — decadimento del radon in cantina · Dalla legge fenomenologica all’esponenziale · Vita media di un campione misto