Measurements in nuclear beta decay provide the most precise information available on the unitarity of the CKM matrix, a key test for the possible existence of physics beyond the Standard Model.

Extremely pure isotopic samples are produced from the MARS recoil spectrometer (in the case of ²²Mg the beam was >99.9% pure). The fast tape-transport system is then used to move the collected samples to a shielded counting position where beta-decay half-lives and gamma-ray intensities are measured with uniquely high precision.