Speaker
Mr.
Giovanni Benato
(University of Zurich)
Description
The search for neutrinoless double beta decay ($0\nu\beta\beta$) is playing since two decades a major role in astroparticle physics.
The discovery of this process would demonstrate the violation of lepton number conservation
and the presence of a Majorana term in the neutrino mass.
The GERmanium Detector Array ({\sc{gerda}}) experiment, located at the Gran Sasso underground laboratory in Italy,
is one of the leading experiments for the search of $0\nu\beta\beta$ decay in $^{76}$Ge.
The first data taking (Phase I) took place between November 2011 and June 2013.
With a $\approx 21~\rm kg \cdot yr$ exposure and a background index (BI) at {{$\text{Q}_{\beta\beta}$}}~of $1.1\cdot10^{-2}$~{{$\rm cts/(kg \cdot yr \cdot keV)$}} after pulse shape discrimination,
{\sc{gerda}}~Phase I set a limit on the $0\nu\beta\beta$ decay half life of $T_{1/2}^{0\nu} > 10^{25}~\rm yr~(90\%\mathrm{C.L.})$.
The setup is now being upgraded for the Phase II of the experiment. A final sensitivity on $0\nu\beta\beta$ decay half life
up to $2\cdot10^{26}$~yr can be obtained with an exposure of $100~\rm kg \cdot yr$ and a BI of $10^{-3}$~{{$\rm cts/(kg \cdot yr \cdot keV)$}}.
The main strategies for reaching this are the use of the newly developed Broad Energy Germanium detectors (BEGe),
with enhanced energy resolution and pulse shape discrimination capabilities,
and the installation of an active veto in the liquid argon surrounding the germanium crystals
for the recognition of external background events.
In this talk, a review of the {\sc{gerda}}~Phase I results will be given, followed by a report on the ongoing operations for the preparation of Phase II.
Primary author
Mr.
Giovanni Benato
(University of Zurich)
