Göttingen 2012 – scientific programme
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T: Fachverband Teilchenphysik
T 106: Niederenergie-Neutrinophysik/Suche nach Dunkler Materie 1
T 106.3: Talk
Monday, February 27, 2012, 17:20–17:35, ZHG 102
Correlated and Accidential Background induced by Radioimpurities in DoubleChooz — •Martin Hofmann, Franz von Feilitzsch, Michael Franke, Marianne Göger-Neff, Lothar Oberauer, Patrick Pfahler, Walter Potzel, Stefan Schönert, and Vincenz Zimmer — Lehrstuhl E15, Technische Universität München
Since spring 2011, Double Chooz is successfully taking data. The precise determination of the νe flux and its spectral shape will allow for a measurement of the neutrino mixing angle ϑ13. In order to achieve the desired precision, several sources of background have to be taken into account and investigated. In this talk, the focus will be on the background induced by radioactivity in the Double Chooz detector, which are mainly accidential νe-like events and (α,n) reactions on 13C as part of the correlated background. The selection cuts applied to the raw data to extract the events of interest will be presented, as well as the BiPo coincidences search to determine the concentration of radioisotopes from the U and Th decay chain in the different detector parts. The latter method shows that the radiopurity in Double Chooz is well within the specifications of less than 10−13 g/g of U and Th in all parts of the inner detector. The rate of accidential coincidences is far below the design goal of 1 event per day, too. However, these events cannot be neglected for an accurate measurement of ϑ13, just as the (α,n) background, and have to be addressed in further ongoing studies. This work has been supported by founds of the DFG (TR 27: Neutrinos and beyond), the Excellence Cluster Universe and the Maier-Leibnitz-Laboratorium Garching.