72 research outputs found

    Radiative Strength Functions for Dipole Transitions in Zr-90

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    Partial cross sections for the (p,gamma) reaction on the Y-89 nucleus that were measured previously at proton energies between 2.17 and 5.00 MeV and which were averaged over resonances were used to determine the absolute values and the energy distribution of the strength of dipole transitions from compound-nucleus states to low-lying levels of the Zr-90 nucleus. The data obtained in this way were compared with the predictions of various models.Comment: 10 pages, 5 figure

    Results of wavelet processing of the 2K-capture Kr-78 experiment statistics

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    Results of a search for Kr-78 double K-capture with the large low-background proportional counter (2005-2008 years) at the Baksan Neutrino Observatory are presented. An experimental method and characteristics of detectors are described. Basic features of the digitized pulses processing using wavelet transform are considered. With due account taken of the analysis of individual noise characteristic it has been shown that the appropriate choice of both wavelet characteristics and sequence of processing algorithms allows one to decrease the background in the energy region of useful events with a unique set of characteristics by ~2000 times. New limit on the half-life of Kr-78 with regard to 2K-capture has been found: T_{1/2} >= 2.4E21 yrs (90% C.L.).Comment: 12 pages, 9 figure

    Characteristics of proportional counter filled with CF4_4 and Xe additions

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    In this article the measurement results of proportional counter working characteristics filled with CF4_4 and Xe (0÷50\div5% Xe) additions at different pressures (0.8÷14.80.8\div14.8 atat) are presented. We have found that a bit of Xe addition reduces working voltage necessary to get the same gas amplification by two times against pure CF4_4, it improves as well the resolution of the counter and increases limit gas amplification by more than ten times.Comment: 7 pages, 8 figure

    Results of a search for daily and annual variations of the Po-214 half-life at the two year observation period

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    The brief description of installation TAU-2 intended for long-term monitoring of the half-life value τ\tau (τ1/2\tau_{1/2}) of the 214^{214}Po is presented. The methods of measurement and processing of collected data are reported. The results of analysis of time series values τ\tau with different time step are presented. Total of measurement time was equal to 590 days. Averaged value of the 214^{214}Po half-life was obtained τ=163.46±0.04\tau=163.46\pm0.04 μ\mus. The annual variation with an amplitude A=(8.9±2.3)104A=(8.9\pm2.3)\cdot10^{-4}, solar-daily variation with an amplitude ASo=(7.5±1.2)104A_{So}=(7.5\pm1.2)\cdot10^{-4}, lunar-daily variation with an amplitude AL=(6.9±2.0)104A_L=(6.9\pm2.0)\cdot10^{-4} and sidereal-daily variation with an amplitude AS=(7.2±1.2)104A_S=(7.2\pm1.2)\cdot10^{-4} were found in a series of τ\tau values. The maximal values of amplitude are observed at the moments when the projections of the installation Earth location velocity vectors toward the source of possible variation achieve its maximal magnitudes.Comment: Talk at The International Workshop on Prospects of Particle Physics: "Neutrino Physics and Astrophysics" February 1 - Ferbuary 8, 2015, Valday,Russia, 7 pages, 12 figure (to be published in PEPAN

    The origin of the background radioactive isotope Xe-127 in the sample of Xe enriched in Xe-124

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    The results of investigation of Xe-127 radioactive isotope production in the xenon sample enriched in Xe-124, Xe-126, Xe-128 are presented. The isotope is supposed to be the source of the background events in the low-background experiment on search for 2K-capture of Xe-124. In this work we consider two channels of Xe-127 production: the neutron knock-out from Xe-128 nucleus by cosmogenic muons and the neutron capture by Xe-126 nucleus. For the first channel the upper limit of the cross section of Xe-127 production was found to be sigma >= 0.007 barn at 95\% C.L. For the second channel the value obtained for the cross section was found to be equal to sigma =(2.74+-0.4) barn, which coincides well, within the statistical error, with reference value.Comment: Talk at The International Workshop on Prospects of Particle Physics: "Neutrino Physics and Astrophysics" Ferbuary 1 - 8, 2015, Valday,Russia, 4 pages, 5 figures, 1 tabel (to be published in PEPAN

    Comparative analysis of spectra of the background of the proportional counter filled with Kr, enriched in Kr-78, and with Kr of natural content

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    The results of the experiment searching for 2K-capture with large low-background proportional counter are presented. The comparison of spectra of the background of the proportional counter filled with Kr enriched in 78^{78}Kr (8400 hr) and with natural Kr (3039 hr) is given. A new limit on the half-life of 78^{78}Kr with regard to 2K-capture, T1/22.01021_{1/2}\geq2.0\cdot10^{21} yrs (95% C.L.) has been obtained.Comment: 4 pages, 7 postscript figures, talk at the XIV-th Int. School "Particles and Cosmology

    Sources of the systematic errors in measurements of Po-214 decay half-life time variations at the Baksan deep underground experiments

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    The design changes of the Baksan low-background TAU-1 and TAU-2 set-ups allowed to improve a sensitivity of Po-214 half-life (\tau) measurements up to the 2.5 x 10^{-4} are described. Different possible sources of systematic errors influencing on the τ\tau-value are studed. An annual variation of Po-214 half-life time measurements with an amplitude of A=(6.9 \pm 3) x 10^{-4} and a phase of (\phi=93 \pm 10) days was found in a sequence of the week-collected \tau-values obtained from the TAU-2 data sample with total duration of 480 days. 24 hours' variation of the \tau-value measurements with an amplitude of A=(10.0 \pm 2.6) x 10^{-4} and phase of (\phi=1 \pm 0.5) hours was found in a solar day 1 hour step \tau-value sequence formed from the same data sample. It was found that the Po-214 half-life averaged at 480 days is equal to (163.45 \pm 0.04) mks.Comment: 17 pages, 6 figures, accepted for publication in Journal of Physics of Elementary Particles and Atomic Nucle

    Search for 2K(2\nu)-capture of Xe-124

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    The results of a search for two neutrino mode of double K-capture of Xe-124 using a large copper low-background proportional counter are presented. Data collected during 3220 hours of measurements with 58.6 g of 124^{124}Xe provides us to a new limit on the half-life of Xe-124 regarding 2K-capture at the level: T_{1/2} >= 2.0*10^{21} years at a 90\% confidence level.Comment: 9 pages, 4 figures, Talk at The International Workshop on Prospects of Particle Physics: "Neutrino Physics and Astrophysics" February 01 - Ferbuary 08, 2015, Valday, Russi

    Radiative Strength Functions for Dipole Transitions in 57, 59Co

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    Average-resonance data on the (p,gamma) reaction on 56,58Fe that were taken at proton energies of Ep=1.5-3.0 MeV are used to determine the absolute values of the radiative strength functions for energies below 10 MeV. The results obtained in this way are compared with the results of the calculations that rely on the statistical approach and which take into account the temperature of the nucleus and its shell structure. Good agreement with experimental data is achieved without any variation of parameters.Comment: 6 pages, 6 figure

    Force and magnetic field sensor based on measurement of tunneling conductance between ends of coaxial carbon nanotubes

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    The interaction and tunneling conductance between oppositely located ends of coaxial carbon nanotubes are studied by the example of two (11,11) nanotubes with open ends terminated by hydrogen atoms. The Green function formalism is applied to determine the tunneling current through the nanotube ends as a function of the distance between the ends, relative orientation of the nanotubes and voltage applied. The energy favorable configuration of the coaxial nanotubes is obtained by the analysis of their interaction energy at different distances between the nanotube ends and angles of their relative rotation. Using these calculations, a general scheme of the force sensor based on the interaction between ends of coaxial nanotubes is proposed and the relation between the tunneling conductance and measured force is established for the considered nanotubes. The operational characteristics of this device as a magnetic field sensor based on measurements of the magnetic force acting on the coaxial nanotubes filled with magnetic endofullerenes are estimated.Comment: 9 pages, 8 figure
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