Search

Investigation of double beta decay processes (β+EC, EC/EC) of 74Se was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.) using ultra low-background HPGe detector Obelix with sensitive volume of 600 cm³ and a sample of natural selenium with a mass of 1.6 kg, containing ∼0.89% (∼14.24 g) of 74Se. New experimental limits (at 90 % CL) on double beta decay transitions of 74Se to the ground and exited states of 74Ge were obtained from the preliminary calculation of experimental data accumulated in 135 days. [ABSTRACT FROM AUTHOR]

Investigation of double beta decay processes (β+EC, EC/EC) of 58Ni was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.) using ultra low-background HPGe detector Obelix with sensitive volume of 600 cm3 and a sample of natural nickel, containing ∼68% of 58Ni with a mass of ∼21.7 kg. New experimental limits on 2νβ+EC decay of 58Ni to the ground 0+ and 2+1 , 811 keV excited state of 58Fe, and 2νEC/EC decay of 58Ni to 2+1 , 811 keV and 2+2 , 1 675 keV excited states of 58Fe were obtained from the preliminary calculation of experimental data accumulated in ∼88d. They are - T1/2(β+EC, 0+ → 0+) > 1.4 ×1021 y; T1/2 (β+EC, 0+ → 2+1 ) > 1.7 ×1022 y, T1/2 (EC/EC, 0+ → 2+1 ) > 2.4 ×1022 y, T1/2 (EC/EC,0+ → 2+2 ) > 2.1 × 1022 y. For resonant neutrino-less radiative EC/EC decay with energy of 1 918.3 keV a new experimental limit of T1/2 (0νEC/EC − res, 1918keV) > 4.7 ×1022 y was also obtained. All limits are at 90 % CL. [ABSTRACT FROM AUTHOR]

A new experimental run of searching for EC/EC decay of 106Cd was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and ~23.2 g 106Cd with enrichment of 99.57%. The limit on 2νEC/EC decay of 106Cd - T1/2(2νEC/EC) > 3.1×1020 y, at 90% C.L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of 106Cd were obtained from the measurement of ~23.2 g of 106Cd with the low-background HPGe spectrometer OBELIX lasted 395 h - T1/2(KL, 2741 keV) > 0.9×1020 y and T1/2(KK, 2718 keV) > 1.4×1020 y at 90% C.L. [ABSTRACT FROM AUTHOR]

Investigations of double beta decay processes to excited states of daughter nuclei were performed at the Modane underground laboratory (LSM, France, 4800 m w.e.) using the high sensitivity spectrometer OBELIX [1], which is a common activity of JINR Dubna, IEAP CTU in Prague and LSM. The spectrometer is based on the HPGe detector with the sensitive volume of 600 cm³ and relative efficiency of 160%. Investigation of resonant neutrino-less double electron capture of 106Cd was performed with ~23.2 g of 106Cd (enrichment of 99.57%) during ~17 days. The experiment with natural Ni (~21.7 kg of mass) was also carried out during ~47 days. The preliminary experimental limits for 0νEC/EC resonant decay to the excited states of 106Pd and different modes of β β decay 58Ni are presented. [ABSTRACT FROM AUTHOR]

An ultra-low background coaxial HPGe detector for gamma-ray spectrometry with a relative efficiency of 160%, corresponding to a 600cm³ Ge crystal, was installed at the Laboratoire Souterrain de Modane, France (4800 m.w.e). To reduce the instrinsic detector background, all parts involved in the detector cryostat were selected for their low radioactivity contamination. A shielding, composed of an inner layer of roman lead and an external layer of regular lead was installed, together with a system to reduce the Rn level inside the sample chamber. The shielding was designed to allow the measurement of Marinelli-shaped samples. We present the constructional details which lead to a remarkable low detector background of 73 cts/kg·d in [40, 3000] keV. Measured samples showed that sensitivities about 100 μBq/kg in 226Ra and 228Th are reached for samples of some kg and 30 days of lifetime. [ABSTRACT FROM AUTHOR]

Double beta decay (ββ) experiments are challenging frontiers in contemporary physics. These experiments have the potential to investigate more about neutrinos (eg. nature and mass). The main challenge for these experiments is the reduction of background. The group at IEAP, CTU in Prague is investigating a new approach using pixel detectors Timepix. Pixel detector offer background reduction capabilities with its ability to identify the particle interaction (from the 2D signature it generates). However, use of pixel detectors has some challenges such as the presence of readout electronics near the sensing medium and heat dissipation. Different aspects of pixel setup (identification of radio-impurities, selection of radio-pure materials) and proposed experimental setup are presented. Also, results of preliminary background measurements (performed on the surface and in the underground laboratories) using the prototype setups are presented. [ABSTRACT FROM AUTHOR]

The collaboration TGV has finished measurement of 2νEC/EC decay of 106Cd with 10 g (Phase I) and 13.6 g (Phase II) samples (with enrichment of 75%), respectively. The times of measurements were 8687h (Phase I) and 12900h (Phase II). The half-life limits (at 90% CL) were obtained for 2νEC/EC decay of 106Cd to the ground state of 106Pd as T1/2>3.0×1020 y (Phase I) and T1/2>4.2×1020 y (Phase II). The collaboration decided to continue with the study of 2νEC/EC decay of 106Cd using 23 g of an isotope enriched to 98.4%. We plan to use the TGV II spectrometer for this measurement and also Si pixel detectors for further study of double beta decay (ββ) processes. [ABSTRACT FROM AUTHOR]

A low background high sensitive HPGe spectrometer OBELIX was installed at the Modane Underground Laboratory (LSM, France, 4800 m w.e.). The detector was designed to measure a contamination of enriched isotopes and radioimpurities in construction materials, to investigate rare nuclear processes such as resonance neutrinoless double electron capture and two-neutrino double beta decay to excited states of daughter nuclei. Spectrometer sensitivity, contamination of NEMO-3 sources and results of 2? 2ß - decay of 100Mo to the 0+ (1130 keV) and 2+ (540 keV) excited states as well as future plans for OBELIX detector are given. [ABSTRACT FROM AUTHOR]

The article presents an author index for the August 8, 2013 issue of the journal "AIP Conference Proceedings" by the American Institute of Physics (AIP), including A. Ortiz de Solórzano, Frédéric Perrot, and Helmut Schuhmacher.