A precision measurement of the longitudinal polarization of 83 210 Bi(RaE)?-particles at 900 keV

Abstract

The longitudinal polarization of electrons from the fl-decay of 21~ has been measured near the endpoint energy using MMler-scattering. The value PL = (-0.718 + 0.0244) v/c obtained from this experiment has much smaller uncertainty than previous data and allows a moreaccurate redetermination of the nuclear R In addition, an improved determination of the parameters X and Ydefined by Fujita under the assumption of the validity of the CVC theory has been performed. The results are compared with various shell-model predictions.

Beta shapefactor determinations by the cutoff energy yield method

“…However, according to Behrens and Szybisz [33], reliable nuclear wave functions can only be derived accurately from experiment. An irrefutable test of the accuracy of the Cherenkov counting analysis in the determination of the configuration of j 210 Bi; 1 À i ground state is the agreement between computed and experimental longitudinal electron polarization curves [34]. Since the Cherenkov counting predictions for this observable [7] are in much better agreement than previous attempts [35,36], we can state that the shapefactor function measured by Cherenkov counting has a high degree of accuracy.…”