Parity nonconservation in 207Pb

Two experiments are currently underway to measure the single‐particle weak mixing matrix element for the 1064 KeV transition in 207Pb. One experiment measures the circular polarization of the 1064 KeV gamma ray emitted from an unpolarized source, while the other experiment measures the forward‐backward asymmetry of gamma rays emitted from a polarized source. Analysis of the first set of polarized source data yields an upper limit of 46 eV for the single‐particle weak mixing matrix element.