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The main goal of the GERDA experiment was to search for the neutrinoless double-beta decay of Ge. Beside this, many other GERDA results of searching for various processes beyond the Standard Model were obtained. Among them, a possible manifestation of the inclusive, mode independent decays of a single neutron and proton and some specific modes of tri-nucleon decays in Ge were investigated, as well as a possible decay of an electron via channel . A search for full energy depositions from bosonic keV-scale dark matter candidates has been performed too.

In modern technological processes, a large role is played by measurements of technical parameters. The total number of industrial enterprises is constantly monitored by regulatory authorities for the use of water resources. Mostly it was not possible to measure most of the existing pressure-free flows recently, but with the advent of equipment on the metrology market that could measure the speed and level at the same time, the situation changed radically. It makes sense to consider in detail two measurement methods that are currently used in more than 90 % of cases - the acoustic (non-contact) method and the two-channel Doppler method which metrological standards of these methods were compared.

Classical fiber optic physical sensors have intra-fiber structures that change the back-reflection response as environmental conditions change. These structures are often a modification of the fiber core glass. But, there are sensors that are the incorporation of a gas or liquid cell into the fiber core. Such a structure works as a Fabry–Pérot interferometer, it can also work as a threshold sensor when the aggregate state of the cell changes. This paper deals with the structure in the fiber created by the fuse effect. The cells of this structure contain oxygen at pressures from 4 atm. These cells work as a threshold sensor that can indicate the presence of cryogenic liquid. The purpose of the present study is to determine the dependence of the change in back reflection on temperature.

The progress in the development of the GERDA (GErmanium Detector Array) experiment is presented. The goal of the experiment is the search for neutrinoless double beta decay of 76Ge with considerable reduction of background in comparison with predecessor experiments. GERDA will operate bare germanium semiconductor detectors (enriched in 76Ge) submerged in high purity liquid argon supplemented by a water shield. The experimental set up is currently under construction in the underground facility of LNGS, Italy. The results of various R&D efforts and the main steps of the GERDA set up design and installation are given as well as several novel methods for background reduction are described.

The article studies nonlinear oscillations of a double mathematical pendulum which axes of the cylindrical joints are not collinear to each other and constitute an acute angle between themselves. Nonlinear oscillation modes of the system are constructed and analyzed in the first approximation using asymptotic methods. A quantitative verification of the obtained results is carried out by considering particular cases of a plane and orthogonal double pendulum and monitoring the energy integral in the appropriate approximation. The constructed analytical solutions are accompanied by graphic illustrations that clarify the essence of the solution.

Exploring the pharmacologically important pyrazolo[1,5-a][1,3,5]triazin-7(6H)-one scaffold for the construction of new bioactive compounds, we developed a synthesis of 4-phenethylthio-2-phenylpyrazolo[1,5-a][1,3,5]triazin-7(6H)-one (4) via S-alkylation of 2-phenyl-4-thioxopyrazolo[1,5-a][1,3,5]triazine-7(6H)-one (3), prepared by the double ring closure of pyrazole and triazine rings upon the treatment of 1-cyanoacetyl-4-benzoylthiosemicarbazide (2) with alkali. The antiproliferative activity of 4 against human lung cancer (A549) and human breast cancer (MDA-MB231) cell lines was investigated. Compound 4 was found to be more active against lung cancer cells than breast cancer cells.

LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m3, 1.4tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 103 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of the order 10−2 cts/(keV-kg-y), which is at the level of the GERDA phase I design goal. As a consequence of these results, the development of an active liquid argon veto in GERDA is pursued.

This study is a continuation of the article “Optimization of oscillation damping modes of a spatial double pendulum: 1. Formulation of the problem,” in which the problem of the optimal oscillation damping of a double pendulum with hinged noncollinear axes was formulated. Passive damping (viscous friction) is considered separately, and the possibility of additional account of active impacts (collinear control) is also explored. Two optimization criteria are introduced that characterize the efficiency of the damping of system motion: first, the degree of stability is maximized, and then the integral energy-time criterion is minimized. The optimal values of the parameters of the damping variants under consideration are determined by applying both criteria in finding the exact solution of the problem in a linear model. The results obtained are presented as visual graphic illustrations which enable determination of their main qualitative and quantitative features. The conclusions made can be useful in studying the motions of manipulators and various robotic structures.

Low background experiments place stringent constraints on amount of radioactive impurities in the materials used for their assembly. Often these are in conflict with the constraints placed on the materials by their roles in the experiment. This is especially true for certain electronic components. A high value, high voltage capacitor for use in low background experiments has been developed from specially selected radiopure materials. Electroformed copper foils are separated by polyethylene napthalate (PEN) foils and supported within a PTFE teflon spiral coil tube. The electrical performance as well as radiopurity are scrutinized here. With some minor modifications to tune the performance for the application, this capacitor can be well suited for a variety of applications in low background experiments. Here the use of the capacitor for high voltage (HV) decoupling in the operation of high purity germanium (HPGe) detectors is demonstrated.

A discovery that neutrinos are Majorana fermions would have profound implications for particle physics and cosmology. The Majorana character of neutrinos would make possible the neutrinoless double-β (0νββ) decay, a matter-creating process without the balancing emission of antimatter. The GERDA Collaboration searches for the 0νββ decay of 76Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg·year, we observe no signal and derive a lower half-life limit of T 1/2 > 0.9 × 1026 years (90% C.L.). Our T 1/2 sensitivity, assuming no signal, is 1.1 × 1026 years. Combining the latter with those from other 0νββ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 to 0.16 electron volts.