Virtual depth by active background suppression: Revisiting the cosmic muon induced background of GERDA Phase II

In-situ production of long-lived isotopes by cosmic muon interactions may generate a non-negligible background for deep underground rare event searches. Previous Monte Carlo studies for the GERDA experiment at LNGS identified the delayed decays of $^{77}$Ge and its metastable state $^{77m}$Ge as dominant cosmogenic background in the search for neutrinoless double beta decay of $^{76}$Ge. This might limit the sensitivity of next generation experiments aiming for increased $^{76}$Ge mass at background-free conditions and thereby define a minimum depth requirement. A re-evaluation of the $^{77(m)}$Ge background for the GERDA experiment has been carried out by a set of Monte Carlo simulations. The obtained $^{77(m)}$Ge production rate is (0.21$\pm$0.01) nuclei/(kg$\cdot$yr). After application of state-of-the-art active background suppression techniques and simple delayed coincidence cuts this corresponds to a background contribution of (2.7$\pm$0.3)$\cdot10^{-6}$ cts/(keV$\cdot$kg$\cdot$yr). The suppression achieved by this strategy equals an effective muon flux reduction of more than one order of magnitude. This virtual depth increase opens the way for next generation rare event searches.Comment: 9 pages, 5 figure

Cryocautery and Aqueous Humor Dynamics

A method of cyclocryocautery, using the Kelman Cryostylet, is described. On rabbit eyes this brings about a statistically significant lowering of intraocular pressure and reduction of aqueous flow over an observation period of three months. The effects upon the facility of outflow are variable. Side effects are minimal. The intraocular temperature was measured at various points during and after cryocautery. An applicator temperature of about -40° C was found sufficient for the desired result with minimal side effects. Angiocryocautery of one or both long posterior ciliary vessels resulted only in a temporary reduction of intraocular pressure, as permanent obliteration of these vessels was not possible by this method. In a small series of eight patients with primary and secondary glaucomas, the procedure described was effective in six cases. Possible indications in other forms of glaucoma are discussed

Unilateral Aphakia and Contact Lenses

The binocular functions of a group of 60 patients with unilateral aphakia were tested after fitting with a contact lens. Results showed a high degree of extramacular fusion in the group. However, only 50% of these patients obtained satisfactory stereoacuity levels. There was no relation between the time elapsed from cataract extraction to contact lens fitting and the amount of ultimate stereoacuity obtained. Some factors presenting common obstacles to successful fitting of aphakic contact lenses are discussed

Sympathetic Cooling of a Single Individually-Trapped Proton in a Cryogenic Penning Trap

A method to prepare arbitrary stored ions with low energy in the mK range would improve many high-precision Penning trap experiments and is essential for high-precision measurements of the antiproton and proton g-factors. In this thesis, we investigate sympathetic cooling of a single individually-trapped proton by laser-cooled 9Be+ ions stored in a separate trap. Both ions are coupled by image currents induced in a common electrode and the coupling is enhanced by a connected cryogenic superconducting radio-frequency RLC oscillator. The image-current based coupling makes the technique applicable to arbitrary ions. We describe the new experimental setup, based on a significant modification of the previous proton g-factor experiment, and the installation and optimization of new image-current detectors. We further describe the development and characterization of a single-photon sensitive fluorescence detection system based on silicon photomultipliers integrated into the cryogenic Penning trap. We demonstrate laser-cooling of the 9Be+ ions and measure their temperature to 1.1(2) mK using fluorescence detection. The simultaneous detection of fluorescence photons and image currents of laser-cooled 9Be+ ions enables a measurement of the laser-induced damping. We further demonstrate sympathetic cooling of the axial mode of a single proton to 2.6(2.5) K, limited by the applied temperature measurement method. With a newly developed temperature measurement trap, we improve this value to 160(30) mK, almost two orders of magnitude below the environment temperature. Finally, we argue that the technique can be optimized to reach temperatures in the low double-digit mK range, which would enable a future generation of antiproton and proton g-factor measurements with an order of magnitude improved precision. For other high-precision Penning trap experiments, the method will be an attractive tool to prepare arbitrary ions for measurement

The Effect of Electrical Curren on the Crystalline Lens

In summary, the cataractogenic properties of electric current were studies. Previous observations dealing with this subject utilized a multiple shock technique--something which is unlikely to occur in any accidental exposure. This study focused on the production of lens changes in rabbit eyes following single exposures of measured electric current