Startup of the High-Intensity Ultracold Neutron Source at the Paul Scherrer Institute

Ultracold neutrons (UCN) can be stored in suitable bottles and observed for several hundreds of seconds. Therefore UCN can be used to study in detail the fundamental properties of the neutron. A new user facility providing ultracold neutrons for fundamental physics research has been constructed at the Paul Scherrer Institute, the PSI UCN source. Assembly of the facility finished in December 2010 with the first production of ultracold neutrons. Operation approval was received in June 2011. We give an overview of the source and the status at startup.Comment: Proceedings of the International Conference on Exotic Atoms and Related Topics - EXA2011 September 5-9, 2011 Austrian Academy of Sciences, Theatersaal, Sonnenfelsgasse 19, 1010 Wien, Austria 6 pages, 3 figure

Experimental study of 199Hg spin anti-relaxation coatings

We report on a comparison of spin relaxation rates in a $^{199}$Hg magnetometer using different wall coatings. A compact mercury magnetometer was built for this purpose. Glass cells coated with fluorinated materials show longer spin coherence times than if coated with their hydrogenated homologues. The longest spin relaxation time of the mercury vapor was measured with a fluorinated paraffin wall coating.Comment: 9 pages, 6 figures, submitted to JINS

Oscillating ultra-cold neutron spectrometer

The energy spectrum of ultra-cold neutrons (UCN) is very often a key point to determine the systematic effects in precision measurements utilizing UCN. The proposed novel method allows the in-situ measurements of the UCN velocity distribution and its time evolution. In addition, the proposed UCN spectrometer can be a handy diagnostic tool for monitoring the UCN spectrum in critical places in the transport system connecting an UCN source with experiments. In this paper, we present the preliminary results from measurements and simulations using the oscillating UCN spectrometer at the PSI UCN source

X-ray emission during the muonic cascade in hydrogen

We report our investigations of X rays emitted during the muonic cascade in hydrogen employing charge coupled devices as X-ray detectors. The density dependence of the relative X-ray yields for the muonic hydrogen lines (K_alpha, K_beta, K_gamma) has been measured at densities between 0.00115 and 0.97 of liquid hydrogen density. In this density region collisional processes dominate the cascade down to low energy levels. A comparison with recent calculations is given in order to demonstrate the influence of Coulomb deexcitation.Comment: 5 pages, Tex, 4 figures, submitted to Physical Review Letter