Undetected Electron Backscattering in PERKEO III

The beta asymmetry in neutron beta decay is used to determine the ratio of axial-vector coupling to vector coupling most precisely. In electron spectroscopy, backscattering of electrons from detectors can be a major source of systematic error. We present the determination of the correction for undetected backscattering for electron detection with the instrument PERKEO III. For the electron asymmetry, undetected backscattering leads to a fractional correction of $5\times 10^{-4}$, i.e. a change by 40% of the total systematic uncertainty.Comment: Proceedings of the International Workshop on Particle Physics at Neutron Sources PPNS 2018, Grenoble, France, May 24-26, 201

Experiments with Gravitationally-bound Ultracold Neutrons at the European Spallation Source ESS

AbstractExperiments with gravitationally-bound ultracold neutrons have made substantial progress in the last decade. They have been contributing to answer scientific questions ranging from gravity tests at micron distances, the direct search for dark matter particles as axions, and dark energy realizations. Comparing the present accuracy of around 10-14 eV - achieved with a gravity resonance spectroscopy technique - with the by many orders of magnitude expected smaller size of inevitable systematic errors, one may conclude that the present experiments are heavily restricted by the limited strength of today's ultracold neutron (UCN) sources.We propose to build a dedicated UCN source at the European Spallation Source in order to perform experiments with gravitationally-bound UCN

Gravity Resonance Spectroscopy and Einstein-Cartan Gravity

The qBounce experiment offers a new way of looking at gravitation based on quantum interference. An ultracold neutron is reflected in well-defined quantum states in the gravity potential of the Earth by a mirror, which allows to apply the concept of gravity resonance spectroscopy (GRS). This experiment with neutrons gives access to all gravity parameters as the dependences on distance, mass, curvature, energy-momentum as well as on torsion. Here, we concentrate on torsion.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs, Zaragoza, June 22 to 26, 2015, 6 pages, 4 figure

Quantum states of neutrons in the gravitational field and limits for non-Newtonian interaction in the range between 1 micron and 10 microns

Quantum states in the Earth's gravitational field can be observed, when ultra-cold neutrons fall under gravity. In an experiment at the Institut Laue-Langevin in Grenoble, neutrons are reflected and trapped in a gravitational cavity above a horizontal mirror. The population of the ground state and the lowest states follows, step by step, the quantum mechanical prediction. An efficient neutron absorber removes the higher, unwanted states. The quantum states probe Newtonian gravity on the micrometer scale and we place limits for gravity-like forces in the range between 1 micron and 10 microns.Comment: Aspects of Quantum Gravity, ed. by C. Laemmerzahl, Springer, Berlin, Heidelberg 2003, (Lecture notes in physics