We report experiments on the production of ultracold neutrons (UCN) in a converter of superfluid helium coated with fluorinated grease (fomblin). We employed our special technique of window-free extraction of accumulated UCN from the superfluid helium, in which they were produced by downscattering neutrons of a cold beam from the Munich research reactor. The fomblin-coating reduced the time constant for UCN passage through the extraction hole by a factor three compared to our previous experiment employing an uncoated stainless steel vessel. A time-of-flight measurement of the cold neutron spectrum incident on the converter, combined with a gold foil activation, allowed us to determine both the single-phonon and multi-phonon contributions to the UCN production. The UCN production rate is in reasonable agreement with the theoretical expectation. © 2010 The Author(s).
CITATION STYLE
Zimmer, O., Schmidt-Wellenburg, P., Fertl, M., Wirth, H. F., Assmann, M., Klenke, J., & van den Brandt, B. (2010). Ultracold neutrons extracted from a superfluid-helium converter coated with fluorinated grease. European Physical Journal C, 67(3), 589–599. https://doi.org/10.1140/epjc/s10052-010-1327-1
Mendeley helps you to discover research relevant for your work.