The GERmanium Detector Array
The Physics of GERDA

The Physics of GERDA


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The Search for Neutrinoless Double Beta Decay

Neutrino oscillations have established that neutrinos are massive. However, neutrino oscillations are only sensitive to the mass squared differences of the neutrino mass eigenstates. Neutrinoless double beta decay, in contrast, can yield information on the absolute neutrino mass scale. This decay also violates lepton number conservation which is possible only if neutrinos are their own anti-particles (so-called Majorana particles). The experimental observation of such fundamental particle – anti-particle symmetry would corroborate theoretical models which explain the smallness of neutrino masses and would shed light on the mechanism generating the present matter dominance of the Universe.

The GERmanium Detector Array (GERDA), searching for the neutrinoles double beta decay of 76Ge, is located at the Laboratori Nazionali del Gran Sasso, INFN, Italy. The setup implements a new shielding concept by operating bare Ge diodes - enriched in 76Ge in high purity liquid argon supplemented by a water shield. The aim of GERDA is in a first phase to verify or refute a claim of discovery of neutrinoless double beta decay by the Heidelberg-Moscow experiment, and, in a second phase, to achieve a background of 1 × 10-3 cts/(keV kg yr) at Qββ which is two orders of magnitude below the current state-of-the-art. After an exposure of 100 kg years and the said background index, half-lifes up to 2 × 1026 years can be probed at 90% confidence level corresponding to a range of the effective neutrino mass of <0.09-0.29 eV. The GERDA experimental setup allows also to develop and test the experimental techniques for a possible future one ton experiment with sensitivity in the 10 meV mass range.

An explanation of the components of the GERDA installation is shown in the figure below.

Figure: A labeled view of the GERDA installation at the Laboratori Nazionali del Gran Sasso, Italy.

Further information on Gerda:

English (pdf, 3.7 MB)
Deutsch (pdf, 3.7 MB)
Italiano (pdf, 3.7 MB)

mov (140 MB)

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Last modified: 04.11.2010 go to top