DANSSino: a pilot version of the DANSS neutrino detector

DANSSino is a reduced pilot version of a solid-state detector of reactor antineutrinos (to be created within the DANSS project and installed under the industrial 3 GW(th) reactor of the Kalinin Nuclear Power Plant -- KNPP). Numerous tests performed at a distance of 11 m from the reactor core demonstrate operability of the chosen design and reveal the main sources of the background. In spite of its small size (20x20x100 ccm), the pilot detector turned out to be quite sensitive to reactor antineutrinos, detecting about 70 IBD events per day with the signal-to-background ratio about unity.Comment: 16 pages, 11 figures, 3 tables. arXiv admin note: substantial text overlap with arXiv:1304.369

Search interactive regional game as a metod of developing general competencies

The article presents the possibility of using regional interactive quest game as the pedagogical technology aimed to formation of the general competences of studentsВ статье рассматривается возможность использования краеведческой интерактивной игры-квеста, как педагогической технологии, направленной на формирование общих компетенций обучающихс

Search for sterile neutrinos at the DANSS experiment

DANSS is a highly segmented 1~m${}^3$ plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1~$\mathrm{GW_{th}}$ reactor of the Kalinin Nuclear Power Plant 350~km NW from Moscow. The distance to the core is varied on-line from 10.7~m to 12.7~m. The reactor building provides about 50~m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 $\widetilde\nu_e$ per day at the closest position with the cosmic background less than 3$\%$. The inverse beta decay process is used to detect $\widetilde\nu_e$. Sterile neutrinos are searched for assuming the $4\nu$ model (3 active and 1 sterile $\nu$). The exclusion area in the $\Delta m_{14}^2,\sin^22\theta_{14}$ plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor $\widetilde\nu_e$ spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at 3 distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to $\sin^22\theta_{14}<0.01$ in the most sensitive region.Comment: 10 pages, 13 figures, version accepted for publicatio

FEATURES OF THE OIL AND GAS POLICY OF THE UNITED STATES OF AMERICA

The scientific article is devoted to the study of the features of the oil and gas policy of the United States of America. The authors considered the organizational and economic structure of the oil and gas industry, state policy and taxation in the oil and gas complex, problems and prospects for its development

Background free search for neutrinoless double beta decay with GERDA Phase II

The Standard Model of particle physics cannot explain the dominance of matter over anti-matter in our Universe. In many model extensions this is a very natural consequence of neutrinos being their own anti-particles (Majorana particles) which implies that a lepton number violating radioactive decay named neutrinoless double beta ($0\nu\beta\beta$) decay should exist. The detection of this extremely rare hypothetical process requires utmost suppression of any kind of backgrounds. The GERDA collaboration searches for $0\nu\beta\beta$ decay of $^{76}$Ge (^{76}\rm{Ge} \rightarrow\,^{76}\rm{Se} + 2e^-) by operating bare detectors made from germanium with enriched $^{76}$Ge fraction in liquid argon. Here, we report on first data of GERDA Phase II. A background level of $\approx10^{-3}$ cts/(keV$\cdot$kg$\cdot$yr) has been achieved which is the world-best if weighted by the narrow energy-signal region of germanium detectors. Combining Phase I and II data we find no signal and deduce a new lower limit for the half-life of $5.3\cdot10^{25}$ yr at 90 % C.L. Our sensitivity of $4.0\cdot10^{25}$ yr is competitive with the one of experiments with significantly larger isotope mass. GERDA is the first $0\nu\beta\beta$ experiment that will be background-free up to its design exposure. This progress relies on a novel active veto system, the superior germanium detector energy resolution and the improved background recognition of our new detectors. The unique discovery potential of an essentially background-free search for $0\nu\beta\beta$ decay motivates a larger germanium experiment with higher sensitivity.Comment: 14 pages, 9 figures, 1 table; ; data, figures and images available at http://www.mpi-hd.mpg/gerda/publi

Characterization of 30 76^{76}Ge enriched Broad Energy Ge detectors for GERDA Phase II

The GERmanium Detector Array (GERDA) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double beta decay of $^{76}$Ge into $^{76}$Se+2e$^-$. GERDA has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the HADES underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for GERDA Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the strength of pulse shape simulation codes.Comment: 29 pages, 18 figure

The first search for bosonic super-WIMPs with masses up to 1 MeV/c2^2 with GERDA

We present the first search for bosonic super-WIMPs as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1 MeV/c$^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most stringent direct limits on the dimensionless couplings of axion-like particles and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and ${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval, respectively, were obtained.Comment: 6 pages, 3 figures, submitted to Physical Review Letters, added list of authors, updated ref. [21

Bone mineral density in patients with early axial spondyloarthritis

Objective: to study bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN) in patients with early axial spondyloarthritis (SpA) and to reveal its association with inflammatory disease activity.Subjects and methods. Seventy-three patients aged 18–45 years with inflammatory back pain lasting at least 3 months and not more than 5 years were examined. Axial SpA was diagnosed according to the 2009 ASAS criteria. BASDAI and ASDAS C-reactive protein (CRP) values were used to estimate disease activity; BASFI was employed to evaluate functional status. The examination encompassed determination of HLA-B27, X-ray of the pelvis and LS, magnetic resonance imaging (MRI) of sacroiliac joints, LS, and hip joints (in the presence of clinical signs of their injuries), densitometry of LS (LI-IV) and FN. By taking into account the young age of patients, the Z-score was applied to measure BMD. The latter is considered lower if the Z-score is 1–2 standard deviations (SD) in at least one of the segments under study.Results. The median Z-score was -0.7 (-1.3; -0.3) SD for FN and 0.9 (-1.6; -0.5) SD for LS. Reduced BMD in at least one of the segments under study was detected in 13 (17.8%) patients: that in LS and FN in 11 (15.1%) and 5 (6.8%) patients, respectively. Lower BMD was observed in two segments in 3 (4.1%) patients. No association was found between lower BMD and age, gender, disease activity (BASDAI, ASDAS), and laboratory inflammatory markers (erythrocyte sedimentation rate (ESR) and CRP). A relationship was established between inflammatory changes according to the data of MRI of LS (MRI spondylitis) and reduced BMD in the same segment. MRI spondylitis was detected in 8 patients. Five and 3 patients with spondylitis of LS were found to have lower and normal BMD in this segment, respectively. Six out of 65 patients without MRI spondylitis in LS had its reduced BMD and the remaining (n=59) patients had its normal BMD (p=0.0014).Conclusion. There was an association between the active inflammatory changes as evidenced by LS MRI and the reduced BMD in this segment of the axial skeleton. Our data validate the hypothesis that in early axial SpA, bone is lost in the vertebral bodies due to local inflammation