Parity violation in Ytterbium

Atomic parity violation (APV) experiments offer the opportunity to study the weak interactions at low-energy scales, providing valuable information about the Standard Model and nuclear physics. Owing to its high atomic mass, the strong mixing by the weak interaction of two opposite parity eigenstates, as well as the availability of many stable isotopes, ytterbium is a particularly good candidate for investigating APV effects. This brings within reach the possibility to detect the nuclear anapole moment of the Yb nucleus as well as to probe the variation of neutron skin among the different isotopes of this element.

Our group has recently succeeded in observing a large APV effect on Yb, in an experiment that concluded in 2009 at Berkeley with a measurement of the effect at the 10% level.  With a new apparatus recently constructed in Mainz, we have improved our statistical  sensitivity to a level that will allow us to perform measurements with a 0.1% accuracy, enough to probe the Yb anapole moment and neutron distributions.