[en] The first search ever for the α-decay of "1"4"6Nd into the first excited state of "1"4"2Ce has been performed by using an ultra-low background High Purity Germanium (HPGe) detector and a Nd-sample with 97.20(1)% abundance of "1"4"6Nd. No significant signal could be observed with a measuring time of 144 h. A lower limit on the half-life of this decay mode has been determined to be T_1_/_2 > 1.6 × 10"1"8 years at 90% CL. (author)

[en] We lack significant nuclear physics input to understand the rapid-neutron capture (r-)process fully. The r-process is the source of half the elements heavier than iron and the only way to produce the long-lived actinides we find on earth. This process’s key nuclear physics inputs are nuclear masses, cross-sections of (n,γ) and (γ,n), and decay half-lives and branching ratios of neutron-rich isotopes. However, there is currently no method to directly measure neutron-induced reaction rates on short-lived nuclides, so there is no experimental data for the primary nuclear reaction that drives the r-process. We show here a conceptual design of a novel approach to access this information experimentally. The idea is to form a target of short-lived isotopes by confining them as ions in a radio-frequency (RF) trap. Next, they are irradiated with an intense neutron flux, and the reaction products are identified by mass spectrometry. The chosen method is a two-stage process in the presence of high neutron fluxes. The first process is neutron-induced fission in a thin actinide foil to create fission fragments. These fragments are slowed down in a cryogenic stopping cell before being filtered through a radio frequency quadrupole (RFQ) system. The RFQ system selects fission fragments of a specific atomic mass number A and confines them to a small volume in an RF trap, where they are irradiated for a second time in a controlled manner. The resultant A+1 isotopes are mass-selectively transported to a multiple-reflection time-of-flight mass spectrometer, where the reaction products are identified and counted.

[en] The GERmanium Detector Array (GERDA) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of ⁷⁶Ge. Germanium detectors made of material with an enriched ⁷⁶Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of the experiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new ⁷⁶Ge enriched detectors of broad energy germanium (BEGe)- type were produced. A subgroup of these detectors has already been deployed in GERDA during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the ⁷⁶Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of GERDA Phase II. (orig.)

[en] 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 0νββ 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. (orig.)

[en] A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 10²³ yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with ⁷⁶Ge. A new result for the half-life of the neutrino-accompanied ββ decay of ⁷⁶Ge with significantly reduced uncertainties is also given, resulting in T_1/2^2ν = (1.926 ± 0.094) @ x 10²¹ yr. (orig.)

[en] Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of "3"6Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of "3"6Ar was established: T_1_/_2 > 3.6 x 10"2"1 years at 90% CI. (orig.)