Mainz 2012 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 33: Fundamentale Symmetrien
HK 33.1: Gruppenbericht
Mittwoch, 21. März 2012, 16:30–17:00, P 1
Progress report on the nEDM project at the Paul Scherrer Institut, Switzerland — •Martin Fertl — Paul Scherrer Institut, Villigen, Switzerland
The Standard Model (SM) of Particle Physics predicts a permanent electric dipole moment for the neutron (nEDM), breaking time reversal and parity symmetry. The electroweak prediction is several orders of magnitude below the current best experimental limit dn < 2.9 × 10−26 ecm (90 % CL, ILL-RAL-Sussex). Many SM extensions predict a nEDM in the range of current experimental sensitivity. Improving the upper experimental limit restricts the allowed parameter space of these models. In a first step the nEDM collaboration has installed the upgraded ILL-RAL-Sussex instrument at the new ultra-cold neutron (UCN) source at the Paul Scherrer Institut (PSI), Switzerland. The collaboration aims at increasing the experimental sensitivity by a factor of five due to the expected higher UCN density and improved control of systematic effects. In parallel a new apparatus is developed for a next measurement phase aiming at another order of magnitude improvement. The experiment employs the Ramsey method of separated oscillatory fields to detect a shift of the Larmor precession frequency of UCN in a parallel and an anti-parallel configuration of very homogeneous magnetic and electric fields. In 2010/2011, the nEDM apparatus has been characterized in detail. The polarized UCN infrastructure was studied and significant progress in the homogeneity of the magnetic field was achieved. Preliminary results of dedicated measurements related to the major systematic false effects will be presented.