Status of the GERDA experiment

The study of neutrinoless double beta (0nbb) decay is the only one presently known approach to the fundamental question if the neutrino is a Majorana particle, i.e. its own anti-particle. The observation of 0nbb decay would prove that lepton number is not conserved, establish that neutrino has a Majorana component and, assuming that light neutrino is the dominating process, provide a method for the determination of its effective mass. GERDA is a new 0nbb decay experiment which is currently taking data at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. It implements a new shielding concept by operating bare diodes made from Ge with enriched 76Ge in high purity liquid argon supplemented by a water shield. The aim of GERDA is to verify or refute the recent claim of discovery, and, in a second phase, to achieve a two orders of magnitude lower background index than past experiments, to increase the sensitive mass and to collect an exposure of 100 kg yr. The paper will discuss design, physics reach, and status of data taking of GERDA.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in 76Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10% at the Q value for 0 neutrino double beta decay in 76Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.JRC.D.4 - Standards for Nuclear Safety, Security and Safeguard

Pulse shape discrimination performance of inverted coaxial Ge detectors

We report on the characterization of two inverted coaxial Ge detectors in the context of being employed in future 76Ge neutrinoless double beta (0) decay experiments. It is an advantage that such detectors can be produced with bigger Ge mass as compared to the planar Broad Energy Ge (BEGe) or p-type Point Contact (PPC) detectors that are currently used in the Gerda and Majorana Demonstrator 0 decay experiments respectively. This will result in a lower background for the search of 0 decay due to a reduction of detector surface to volume ratio, cables, electronics and holders which are dominating nearby radioactive sources. The measured resolution near the 76Ge Q-value at 2039 keV is 2.3 keV FWHM and their pulse-shape discrimination of background events are similar to BEGe and PPC detectors. It is concluded that this type of Ge-detector is suitable for usage in 76Ge 0 decay experiments.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

Gamma Production Cross Section Measurements for 76Ge via (n,n'gamma) at GELINA

This report describes the inelastic scattering data delivered to the Institute for Nuclear and Particle Physics of TU-Dresden. The GAINS setup was used for measurements of gamma production cross sections associated with the 69th excited state of 76Ge, using the (n, n'gamma) technique. The experimental work was performed at the GELINA facility at a 200 m flight path with eight high purity germanium detectors, using highly enriched 76Ge samples. A brief description of the experimental details and the results are presented.JRC.D.5-Nuclear physic

New nuclear structure and decay results in the 76Ge-76As system

The process of neutrinoless double beta decay plays a key role in modern neutrino physics. The experiments on the 76Ge neutrinoless double beta decay using germanium-semiconductors are at the forefront in this field. Due to the extremely low count rates expected for this rare decay, any kind of background event in the detector, especially at energies close to Q = 2039 keV has to be avoided. Therefore a careful investigation on the neutron-induced background was carried out. In this scope experiments investigating the inelastic-neutron-excitation of 76Ge and the de-exitation of its 69th level have been performed. The 70Ge(n,jn)68Ge crossection was measured with quasi-monoenergetic neutrons. In order to calculate the Matrixelement for the transition between the 76Ge-76As groundstates the Electron Capture at 76As has been measured for the first time.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Neutron inelastic scattering measurements for Na, Mo, Zr, Ge, and U

Studies for advanced reactor systems such as sodium-cooled fast reactors designed for recycling of high level waste, accelerator driven systems for transmutation, and systems envisioning the use of the Th/U fuel cycle impose tight requirements on nuclear data for accurate predictions of their operation and safety characteristics. Among the identied needs established by sensitivity studies, neutron inelastic scattering on the main structural materials and actinides and some (n,xn) cross sections for actinides feature prominently. Prompt-gamma spectroscopy and time-of-flight techniques were used to measure (n,xn) cross-sections of interest. Experiments were performed at the GELINA neutron time-of-flight facility of IRMM. Results and progress concerning 235;238U, are presented and discussed for 23Na, 76Ge, Zr and Mo.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard