Search for tri-nucleon decays of ^{76}Ge in GERDA

We search for tri-nucleon decays of 76Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to 73Cu, 73Zn, and 73Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of 73Ga to 73Ge (stable). We search for the 73Ga decay exploiting the fact that it dominantly populates the 66.7 keV 73mGa state with half-life of 0.5 s. The nnn-decays of 76Ge that proceed via 73mGe are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2×1026 yr  (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude

Liquid argon light collection and veto modeling in GERDA Phase II

The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of 76 Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the Gerda liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition

Descending the sanitation ladder in urban Uganda: evidence from Kampala Slums

BACKGROUND: While the sanitation ladder is useful in analysing progressive improvements in sanitation, studies in Uganda have not indicated the sanitation barriers faced by the urban poor. There are various challenges in shared latrine use, cleaning and maintenance. Results from Kampala city indicate that, failure to clean and maintain sanitation infrastructure can lead to a reversal of the potential benefits that come with various sanitation facilities. METHODS: A cross sectional qualitative study was conducted between March and May 2013. Data were collected through 18 focus group discussions (FGDs) held separately; one with women, men and youth respectively. We also used pictorial methods; in addition, 16 key informant interviews were conducted. Data were analysed using content thematic approach. Relevant quotations per thematic area were identified and have been used in the presentation of the results. RESULTS: Whether a shared sanitation facility was improved or not, it was abandoned once it was not properly used and cleaned. The problem of using shared latrines began with the lack of proper latrine training when people do not know how to squat on the latrine hole. The constrained access and security concerns, obscure paths that were filthy especially at night, lack of light in the latrine cubicle, raised latrines sometimes up to two metres above the ground, coupled with lack of cleaning and emptying the shared facilities only made a bad situation worse. In this way, open defecation gradually substituted use of the available sanitation facilities. This paper argues that, filthy latrines have the same net effect as crude open defection. CONCLUSION: Whereas most sanitation campaigns are geared towards provision of improved sanitation infrastructure, these findings show that mere provision of infrastructure (improved or not) without adequate emphasis on proper use, cleaning and maintenance triggers an involuntary descent off the sanitation ladder. Understanding this reversal movement is critical in sustainable sanitation services and should be a concern for all actors