München 2019 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 52: Instrumentation XI, Accelerators and Applications
HK 52.7: Vortrag
Donnerstag, 21. März 2019, 15:45–16:00, HS 11
Investigation of non-depolarizing neutron guide coatings for neutron beta decay studies with PERC — •Alexander Hollering1, Thorsten Lauer3, Bastian Märkisch1, and Ulrich Schmidt2 — 1TUM — 2Universität Heidelberg — 3Movatec GmbH
Neutron beta decay is a sensitive tool to search for non-V-A couplings beyond the Standard model in the charged weak interaction. The PERC instrument, which is currently under construction at the MLZ, Garching, aims to measure correlation parameters in neutron beta decay with an accuracy improved by one order of magnitude to a level of 10−4. This also requires control of the neutron polarization on the same level. Inside the PERC instrument an 8 m long neutron guide is used as decay volume in a magnetic field of 1.5 Tesla and is fed by a highly polarized cold neutron beam. Supermirror neutron guides are usually made of hundreds of nanometer thin layers from nickel and titanium on a glass substrate. But the nickel is magnetized by the magnetic field which leads to depolarization of the neutron beam even for layers made of nickel alloy with vanadium added. In order to ensure a depolarization of the neutron beam on the level of 10−4 per bounce, completely non-magnetic coatings preferably made of diamagnetic materials are required. We present results on mirrors made from copper and titanium layers with excellent reflectivity. Despite copper is well known for its high mobility, which lead to degradation of the reflectivity caused by interdiffusion, our supermirrors are highly resistant to baking-out. We present an element analysis of the supermirrors via elastic recoil detection and reflectivity measurements.