The aSPECT Experiment – an Overview and Latest Results

The aSPECT retardation spectrometer measures the beta−neutrino angular correlation coefficient a in free neutron-decay. This measurement can be used to determine the ratio g_A/g_V of the weak coupling constants, as well as to search for physics beyond the Standard Model, e.g. for a test of the unitarity of the CKM matrix. In 2013 aSPECT had a successful beam time at the Institut Laue-Langevin. The goal of this beam time is to improve the current uncertainty of a from Delta a/a = about 5% to about 1%. The data analysis is being finalized and the quantitative determination of the uncertainties is ongoing. This is includes systematic tests and measurements of the coefficient a using different experimental settings during the beam time, additional offline measurements, e.g. of the work-function fluctuations of the electrodes, and field and tracking simulations. In this talk the status of the analysis and the systematic uncertainties is presented. In addition, an overview of present neutron physics activities at the TRIGA research reactor Mainz will be given (UCN-source, neutron lifetime experiment).