Timepix background studies for double beta decay experiments

The double beta decay (ββ) is very challenging subject of today's physics. It can be used as a powerful tool to test neutrino properties (e.g. Dirac or Majorana type of neutrino) and lepton number conservation. However, these experiments demand very high sensitivity and very strong background reduction. We have been performing intensive R and D towards the use of pixel detector Timepix in the ββ decay experiments. The Timepix device, operated in Time Over Threshold (TOT) mode, provides spectroscopic capabilities in each individual pixel. The main advantage of such detector is its ability to identify and reject background signals (e.g. tracks made by electrons, alpha particles, muons). It would efficiently recognize the signal of ββ decay processes. Two pixel detectors, Si (pixel size 55 × 55 μm2) and CdTe (pixel size 110 × 110 μm2), were tested in the surface laboratory as well as in the underground laboratories, from the point of view of intrinsic background and the results are presented. Low background materials for construction of the setup were also identified. The first prototype of Silicon Pixel Telescope (SPT) has been tested and future improvements are also presented.