Neutrino physics entered a new era in the last decade. With the discovery of a non-vanishing
neutrino rest mass in oscillation experiments a variety of new questions showed up in the
context of nuclear and particle physics. One of the crucial questions is the determination of
the absolute neutrino mass, which cannot be measured in oscillation experiments. One option
is neutrino-less double beta decay, the simultaneous conversion of two neutrons into two
protons emitting two electrons. This total lepton number violating process requires that
neutrinos are their own antiparticles and is considered to be gold plated. Furthermore, the
measured half-life is directly linked with the neutrino mass. Currently, half-life measurements
beyond 1025 years are discussed. This requires a large amount of the isotope of interest and a
reduction of disturbing background to the smallest possible level. Indeed it is a search for the
needle in a haystack.
After a general introduction into double beta decay and the physics of the COBRA
experiment based on CdZnTe semiconductors the current status and results will be presented.
This will be followed by an outlook for a large scale experiment