The retardation spectrometer aSPECT was built to measure the shape of the proton spectrum in free neutron decay with high precision. This allows us to determine the antineutrino electron angular correlation coefficient a. We aim for a precision more than one order of magnitude better than the present best value, which is Delta_a /a = 5%. In a recent beam time performed at the Institut Laue-Langevin during April / May 2008 we reached a statistical accuracy of about 2% per 24 hours measurement time. Several systematic effects were investigated experimentally. We expect the total relative uncertainty to be well below 5%.
@article{arxiv.0811.3851,
title = {Measuring the proton spectrum in neutron decay - latest results with aSPECT},
author = {M. Simson and F. Ayala Guardia and S. Baeßler and M. Borg and F. Glück and W. Heil and I. Konorov and G. Konrad and R. Muñoz Horta and K. K. H. Leung and Yu. Sobolev and T. Soldner and H. -F. Wirth and O. Zimmer},
journal= {arXiv preprint arXiv:0811.3851},
year = {2015}
}
Comments
Accepted for publication in the Conference Proceedings of the International Workshop on Particle Physics with Slow Neutrons 2008 held at the ILL, France. To be published in Nuclear Instruments and Methods in Physics Research, Section A