Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 21: Instrumentation und Anwendungen

HK 21.3: Talk

Monday, March 7, 2005, 14:45–15:00, TU MA042

Diamond-like carbon coatings for ultra-cold neutron reflectors — •St. Heule¹, T. Brys¹, M. Daum¹, P. Fierlinger¹, A. Foelske¹, M. Gupta¹, R. Henneck¹, M. Kasprzak¹, K. Kirch¹, T. Lippert¹, C.-F. Meyer², F. Nolting¹, A. Pichlmaier¹, B. Schultrich², P. Siemroth², and U. Straumann³ — ¹Paul Scherrer Institut, 5232 Villigen, Switzerland — ²Fraunhofer Institut fuer Werkstoff- und Strahltechnik, Winterbergstrasse 28, 01277 Dresden, Germany — ³Physik-Institut der Universitaet Zuerich, Winterthurerstrasse 190, 8057 Zuerich, Switzerland

At PSI we are presently setting up a new, high-intensity source for ultracold neutrons (UCN). For the storage (and transport) of UCN so far one has widely used Beryllium-coatings which are toxic and therefore difficult to handle. As an alternative to Be we investigate diamond-like carbon (DLC), for which loss factors close to that of Be have been obtained in a recent experiment at ILL. We produce DLC-coatings by Pulsed Laser Deposition (PLD), a process which results in a very low hydrogen content of the films. This is crucial for our applications as UCNs are up-scattered on hydrogen atoms and therefore immediately lost. The deposition process will be optimized to obtain maximum density in order to get maximum limiting velocity. We are in the process of optimizizing the coating process with small-size test samples and - in parallel - building up a facility for coating real guide tubes. We report first results on the characterization of these samples as well as of additional calibration samples by Raman spectroscopy, x-ray spectroscopy (XPS,NEXAFS), neutron reflectometry and laser-acoustic methods.