Mainz 2012 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 50: Poster – Fundamentale Symmetrien

HK 50.2: Poster

Donnerstag, 22. März 2012, 14:00–16:00, P Foyer

A Kelvin Probe set-up to measure the work function for aSPECT — •Christian Schmidt — Institut für Physik, Johannes Gutenberg-Universität Mainz

aSPECT is a high precision experiment testing and looking for physics beyond the standard model. It utilizes a retardation spectrometer of MAC-E type to measure the proton recoil spectrum in free neutron decay in order to determine the electron antineutrino angular correlation coefficient a. Currently a is determined with a precision of Δ a/a ≈ 5%, whereas aSPECT aims for a precision of Δ a/a ≈ 0.3%. For aSPECT the potential difference between the decay volume and the retardation electrode has to be known better than 10 mV. The same limit have to be fulfilled for the spatial fluctuations of the potential. The electrode system used for aSPECT is made of gold-coated copper. The work function of gold surfaces exhibits fluctuations at a level of 100-200 mV. These fluctuations must be quantified, understood and minimised. Therefore we have set up a Scanning Kelvin Probe System. This Kelvin Probe set-up will also be used to measure the work function of other precision experiments like KATRIN. This poster will present the first measurements and results.