Mainz 2012 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 42: Instrumentation
HK 42.9: Talk
Thursday, March 22, 2012, 18:45–19:00, P 3
Investigations of the Patch Effect with a Scanning Kelvin Probe and their Applications to Neutron Decay Experiments — •Gertrud Konrad1,2, Stefan Baessler3, Iain Baikie4, Henry Bonner3, Werner Heil2, Rachel Hodges3, Thorsten Lauer2, Sean McGovern3, and Xuying Tong3 — 1Atominstitut, TU Wien, Austria — 2Universität Mainz, Germany — 3University of Virginia, Charlottesville, USA — 4KP Technology Ltd., Wick, UK
Precision measurements of neutron decay observables address important open questions of particle physics and are generally complementary to direct searches for BSM physics in high-energy physics.
The analysis of the decay protons is based on a precise energy measurement, by means of an electrostatic filter or by TOF measurement. Then the electric potential between the decay and filter regions has to be known with an accuracy of better than 10 mV. Possible inhomogeneities of the work function (WF) at the electrode surface vary the electric field distribution. On the inside of a cylindrical electrode, a spatial variation of order of 100 meV over a distance of several cm was found. A scanning Kelvin probe (SKP) has been used to map the WF. To minimize the WF variations, different surface materials, treatments, and coatings are being investigated. A platinized surface yielded a RMS WF of better than 10 meV. Coating adhesion and surface roughness have a significant influence on the measured WF values.
The physics motivation, the SKP technique, the status of the investigation as well as the impact on neutron decay correlations from the knowledge of the WF will be presented in this talk.