Argon Trap Trace Analysis, or short ArTTA, is a technique to reliably measure the extremely rare 39Ar isotope. 39Ar is a radioisotope of argon constantly created in the outer atmosphere due to neutron spallation of the main isotope 40Ar (mainly 40Ar(n,2n)39Ar). In combination with its half life of 269 years an atmospheric equilibrium of 39Ar/40Ar = 8.1x10-16 is created. To measure such small concentrations, quantum physical techniques from the field of atom physics are necessary, capturing and thus detecting individual atoms in a magneto-optical trap, granting isotopic selectivity due to resonant multi-photon scattering. In the frame of this colloquium, I will introduce the method of ArTTA and summarise our work of the past years. Highlights will be given on our extensive work on Lake Kivu in Rwanda and the Democratic Republic of the Congo.
39Ar ArTTA – Dating of Hydrological Systems with Quantum Physics