The A=96 system in ββ decay

Properties of the single and double beta decays of ⁹⁶Zr are discussed. It is argued that the single beta decay can provide important information to the neutrinoless variant of β β decay, as it provides a test of theories aimed at calculating the nuclear matrix elements (NME) for both decays. An experimental extraction of the NME for the single β decay requires a measurement of the decay Q-value and half-life. It is shown that the present Q-value of the ⁹⁶Zr single β decay is insufficiently well known and requires a re-measurement, preferentially using high-precision ion traps. We also describe the geochemical method to determine the total half-life of ⁹⁶Zr, from which to set a limit on the single β -decay half-life at a level of ≈15 × 10¹⁹yr. Further, the geochemical analysis will allow setting a limit on a rather exotic quadruple β decay of ⁹⁶Zr.