Neutron Decay and the Structure of Weak Interaction

Neutron beta decay is an excellent system to study the charged weak interaction experimentally. The decay is precisely described by theory and unencumbered by nuclear structure effects. Observables are numerous correlation coefficients, spectra and the neutron lifetime. Most importantly, precision measurements in neutron beta decay are used to investigate the structure of the weak interaction and to derive the CKM matrix element Vud.

In this talk I will present recent results of the PERKEO III spectrometer on the beta asymmetry and introduce the new instrument PERC, which is currently under construction at the FRM II by an international collaboration. PERC is
designed to perform improved measurements of several correlation coefficients by an order of magnitude.
The concept of the instrument as well as its current status will be presented.