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T: Fachverband Teilchenphysik
T 102: Niederenergie-Neutrinophysik III
T 102.5: Vortrag
Donnerstag, 3. März 2016, 17:50–18:05, VMP9 SR 07
Correlated background induced by radioimpurities in Double Chooz — •Michael Franke for the Double Chooz collaboration — Physik Department E15, Technische Universität München
The Double Chooz reactor antineutrino experiment, located at the Chooz nuclear power plant in France, provides a precise measurement of the θ13 parameter. After data taking with the far detector since April 2011, the near detector was finished in October 2014 and data taking started within this year. Although this enables a significant reduction of both reactor and detector related systematics uncertainties, several sources of background have to be taken into account to allow a measurement of the neutrino mixing angle θ13 with the desired precision. The talk will focus on the background induced by radioactivity in the near detector. Events coming from the decay of 214Bi and 212Bi followed by the α-decay of 214Po and 212Po, referred to as BiPo coincidences, provide a fast coincidence signal between β− and α signal, which is also spatially correlated. It can be easily distinguished from other background. Therefore it provides tagging of the number of decays within the U decay chain and the Th decay chain. This provides a tool to prove the radiopurity of the Double Chooz Detector. It 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. However, these events cannot be neglected for a measurement of θ13 and have to be addressed in further ongoing studies.
This work has been supported by the DFG (GO 1729/1-1).