350 research outputs found
Results of wavelet processing of the 2K-capture Kr-78 experiment statistics
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
Comparative analysis of spectra of the background of the proportional counter filled with Kr, enriched in Kr-78, and with Kr of natural content
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 Kr
(8400 hr) and with natural Kr (3039 hr) is given. A new limit on the half-life
of Kr with regard to 2K-capture, T 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
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 -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
Results of a search for daily and annual variations of the Po-214 half-life at the two year observation period
The brief description of installation TAU-2 intended for long-term monitoring
of the half-life value () of the Po is presented.
The methods of measurement and processing of collected data are reported. The
results of analysis of time series values with different time step are
presented. Total of measurement time was equal to 590 days. Averaged value of
the Po half-life was obtained s. The annual
variation with an amplitude , solar-daily variation
with an amplitude , lunar-daily variation with
an amplitude and sidereal-daily variation with an
amplitude were found in a series of
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
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
Search for 2K(2\nu)-capture of Xe-124
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 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
The background simulation of experiment for searching of capture in Xe-124
We describe the Monte Carlo (MC) simulation package of the `2K-CAPTURE' setup
and discuss the agreement of its output with data. The `2K-CAPTURE' MC
simulates the energy loss of particles in detector and components of the
passive shield and generates the resulting response in working volume large
proportional counter (LPC). The simulation accounts for absorption, reemission,
and scattering of both photons and neutrons and tracks them until they either
are absorbed. The algorithm proceeds with a detailed simulation of the
electronics chain. The MC is tuned using data collected with radioactive
calibration source deployed in the internal channel of the installation. The
simulation reproduces the energy response of the detector corresponding to
distribution of the generated pointwise clusters of a charge of primary
ionization in LPC.Comment: 6 pages, 5 figures, 1 table, presented at IV international conference
on particle physics and astrophysic
Results of measurements of an environment neutron background at BNO INR RAS objects with the helium proportional counter
A method of measurements of the environmental neutron background at the
Baksan Neutrino Observatory of the INR RAS are described. Measurements were
done by using of a proportional counter filled with mixture of Ar(2
at)+He(4 at). The results obtained at the surface and the underground
laboratory of the BNO INR RAS are presented. It is shown that a neutron
background in the underground laboratory at the 4900 m w.e. depth is decreased
by times without any special shield in a comparison with the Earth
surface. A neutron flux density in the 5-1323.5~cm air height region is
constant within the determination error and equal to
scm.Comment: 5 pages, 4 figures, 2 table
Characteristics of a thermal neutrons scintillation detector with the [ZnS(Ag)+LiF] at different conditions of measurements
A construction of a thermal neutron testing detector with a thin
[ZnS(Ag)+LiF] scintillator is described. Results of an investigation of
sources of the detector pulse origin and the pulse features in a ground and
underground conditions are presented. Measurements of the scintillator own
background, registration efficiency and a neutron flux at different objects of
the BNO INR RAS were performed. The results are compared with the ones measured
by the He proportional counter.Comment: 6 pages, 6 figures, 1 table
First result of the experimental search for the 9.4 keV solar axion reactions with Kr-83 in the copper proportional counter
The experimental search for solar hadronic axions is started at the Baksan
Neutrino Observatory of the Institute for Nuclear Researches Russian Academy of
Science. It is assumed that axions are created in the Sun during M1-transition
between the first thermally excited level at 9.4 keV and the ground state in
Kr-83. The experiment is based on axion detection via resonant absorption
process by the same nucleus in the detector. The big copper proportional
counter filled with krypton is used to detect signals from axions. The
experimental setup is situated in the deep underground low background
laboratory. No evidence of axion detection were found after the 26.5 days data
collection. Resulting new upper limit on axion mass is m_{A} < 130 eV at 95%
C.L.Comment: Talk at the International Workshop on Prospects of Particle Physics:
"Neutrino Physics and Astrophysics" Jan 26 - Ferb 2, 2014, Valday, Russia, 10
pages, 5 figure
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