Engineering topics

Kuzminov, V. V.

Publications and source records attributed to Kuzminov, V. V..

At least 19 records

DOE OSTI2022

Search for electron-neutrino transitions to sterile states in the BEST experiment

The Baksan Experiment on Sterile Transitions (BEST) probes the gallium anomaly and its possible connections to oscillations between active and sterile neutrinos. Based on the Gallium-Germanium Neutrino Telescope (GGNT) technology of the SAGE experiment, BEST employs two zones of liquid Ga target to explore neutrino oscillations on the meter scale. Oscillations on this short scale could produce deficits in the 71 Ge production rates within the two zones, as well as a possible rate difference between the zones. From July 5th to October 13th 2019, the two-zone target was exposed to a primarily monoenergetic, 3.4-MCi 51 Cr neutrino source 10 times for a total of 20 independent 71 Ge extractions from the two Ga targets. The 71 Ge production rates from the neutrino source were measured from July 2019 to March 2020. At the end of these measurements, the counters were filled with 71 Ge doped gas and calibrated during November 2020. In this paper, results from the BEST sterile neutrino oscillation experiment are presented in details. The ratio of the measured 71 Ge production rates to the predicted rates for the inner and the outer target volumes are calculated from the known neutrino capture cross section. Comparable deficits in the measured ratios relative to predicted values are found for both zones, with the 4⁢𝜎 deviations from unity consistent with the previously reported gallium anomaly. Finally, if interpreted in the context of neutrino oscillations, the deficits give best-fit oscillation parameters of Δ⁢𝑚 2 = 3.3$^{+∞}{−2.3}$ eV 2 and sin 2 ⁡2⁢𝜃 = 0.42$^{+0.15}{−0.17}$, consistent with 𝜈 𝑒 →𝜈 𝑠 oscillations governed by a surprisingly large mixing angle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Results from the Baksan Experiment on Sterile Transitions (BEST)

The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos 𝜈𝑒 observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred to as the “gallium anomaly,” which could be interpreted as evidence for oscillations between 𝜈𝑒 and sterile neutrino (𝜈 𝑠 ) states. A 3.414-MCi 51 Cr 𝜈 𝑒 source was placed at the center of two nested Ga volumes and measurements were made of the production of 71 Ge through the charged current reaction, 71 Ga ⁢(𝜈 𝑒 ,𝑒 − ) ⁢71 Ge, at two average distances. The measured production rates for the inner and the outer targets, respectively, are [54.9$^{+2.5}_{−2.4}$⁢(stat) ± 1.4⁢(syst)] and [55.6$^{+2.7}_{−2.6}$⁢(stat) ± 1.4⁢(syst)] atoms of 71 Ge/𝑑. The ratio (𝑅) of the measured rate of 71 Ge production at each distance to the expected rate from the known cross section and experimental efficiencies are 𝑅 in = 0.79 ± 0.05 and 𝑅 out = 0.77 ± 0.05. The ratio of the outer to the inner result is 0.97 ± 0.07, which is consistent with unity within uncertainty. The rates at each distance were found to be similar, but 20%–24% lower than expected, thus reaffirming the anomaly. Furthermore, these results are consistent with 𝜈 𝑒 → 𝜈 𝑠 oscillations with a relatively large Δ⁢𝑚 2 (>0.5 eV 2 ) and mixing sin 2 ⁡2⁢𝜃 (≈ 0.4).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Low-Background Method of Isotope Markers for Measuring the Efficiency of Intercalation of Graphite by Potassium Atoms

The result of low-background measurements of the gamma activity of graphite-potassium intercalated sample is presented. A germanium gamma spectrometer, used for measurements, was located in the low-background chamber of Baksan Neutrino Observatory. For 384 hours of exposure, 768 decays of K-40 isotope nuclei were registered. This activity corresponds to 85 μg/cm{sup 2} potassium atoms embedded in to graphite lattice. A computer simulation of the intercalation process and the gamma-ray spectrum set is also presented. The accuracy of the potassium concentration determination can be brought to 10{sup –}11–10{sup –}12 g/g for mixture enriched with K-40 isotope.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Search for Variations of {sup 213}Po Half-Life

A device with the parent {sup 229}Th source was constructed to search for variations of the daughter {sup 213}Po half-life (T{sub 1/2} = 4.2 μs). A solar-daily variation with amplitude A{sub So} = (5.3 ± 1.1) × 10{sup –4}, a lunar-daily variation with amplitude A{sub L} = (4.8 ± 2.1) × 10{sup –4}, and a sidereal-daily variation with amplitude A{sub S} = (4.2 ± 1.7) × 10{sup –4} were found upon proceeding the data series over a 622-day interval (from July 2015 to March 2017). The {sup 213}Po half-life mean value is found to be T{sub 1/2} = 3.705 ± 0.001 μs. The reference value is corrected by 12%.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2018

Results of In-Depth Analysis of Data Obtained in the Experimental Search for 2K(2ν)-Capture in {sup 78}Kr

A brief description of the results of joint analysis of data obtained in long-term measurements of krypton samples differing in {sup 78}Kr content is presented. Low-background high-pressure proportional gas counters were used as detectors. The comparative analysis of experimental data on single and double K -capture provided the first estimate of the probability of production of a double K -shell vacancy in the process of K -shell electron capture in {sup 81}Kr: P{sub KK}=[5.7±0.8 (stat.)±0.4 (syst.)]×10{sup −5}. A new result for the half-life of {sup 78}Kr with respect to the 2K(2ν)-mode was also obtained: T{sub 1/2}=[1.9{sub −0.7}{sup +1.3} (stat.)±0.3 (syst.)]×10{sup 22} years (90% CL).

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2018

2K-Capture in {sup 124}Хе: Results of Data Processing for an Exposure of 37.7 kg day

The results of the experimental search for two-neutrino 2K-capture in {sup 124}Xe with a large copper proportional counter obtained by processing the data for an exposure of 37.7 kg day are presented. The experimental setup is located at the Underground Low-Background: Laboratory of the Baksan Neutrino Observatory at a depth of 4900 m.w.e. The combination of methods of selection of useful signals with a unique set of characteristics and the event topology taken into account allowed us to suppress the background in the energy region of interest. A new half-life limit for 2K(2ν)-capture in {sup 124}Xe was determined: T{sub 1/2} ≥ 7.7 × 10{sup 21} years (90% CL).

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2018

Search for two-neutrino 2K capture in {sup 124}Xe: the method and preliminary results

The technique used in the experiment in the search for the process of 2K2ν-capture in {sup 124}Xe using large high-pressure proportional counters is briefly described. The measurements with a xenon sample enriched to 21% (or ~57 g) of the {sup 124}Xe isotope carried out for 3340 hours yielded a zero signal. The resultant upper limit on the {sup 124}Xe half-life with respect to the 2ν-mode of the nuclear capture of two K-shell electrons amounts to T{sub 1/2}>4.6 10{sup 21} yr at the 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Search for resonant absorption of solar axions emitted in M1-transitions in {sup 83}Kr nuclei: Second stage of the experiment

Axions with energies of 9.4 keV putatively produced in the Sun via an M1-transition in the {sup 83}Kr nucleus are searched for using the reaction of resonant absorption: A +{sup 83}Kr →{sup 83}Kr* →{sup 83}Kr + γ, e (9.4 keV). The γ-quanta and electrons are detected with a proportional counter filled with krypton and placed in a low-background setup. A new upper limit on the axion–nucleon coupling constant is imposed: |g{sup 3}{sub AN} g{sup 0}{sub AN}|≤1.02 10{sup 6}. For the hadronic axion, this implies a new upper limit on the axion mass: m{sub A }≤ 79eV at the 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2017

Observation of daily and annular variations in the {sup 214}Po half-life

Results: of the analysis of a time series of values of the half-life (τ) of the {sup 214}Po nucleus with a different time step obtained from the TAU-1 (354 days) and TAU-2 (973 days) installations are presented. The annual variation with an amplitude of (9.8 ± 0.6) × 10{sup −4} and daily variations in the solar, lunar, and sidereal times with amplitudes of (5.3 ± 0.3) × 10{sup −4}, (6.9 ± 2.0) × 10{sup −4}, and (7.2 ± 1.2) × 10{sup −4}, respectively, are found in the series of τ values. It is shown that variations in microclimatic parameters cannot be a cause of τ variations.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2017

Search for 2K(2ν)-capture of {sup 124}Xe

The results of a search for two neutrino mode of double K-capture of {sup 124}Xe using a large copper low-background proportional counter are presented. Data collected during 3220 hours of measurements with 58.6 g of {sup 124}Xe provides us to a new limit on the half-life of {sup 124}Xe regarding 2K-capture at the level: T{sub 1/2} ≥ 2.0 × 10{sup 21} years at a 90% confidence level.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2017

The origin of the background radioactive isotope {sup 127}Xe in the sample of Xe enriched in {sup 124}Xe

The results of investigation of {sup 127}Xe radioactive isotope production in the xenon sample enriched in {sup 124}Xe, {sup 126}Xe, {sup 128}Xe 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 {sup 124}Xe. In this work we consider two channels of {sup 127}Xe production: the neutron knock-out from {sup 128}Xe nucleus by cosmogenic muons and the neutron capture by {sup 126}Xe nucleus. For the first channel the upper limit of the cross section of {sup 127}Xe production was found to be σ ≤ 0.007 × 10{sup −24} cm{sup 2} at 95% C.L. For the second channel the value obtained for the cross section was found to be equal to σ = (2.74 ± 0.4) × 10{sup −24} cm{sup 2}, which coincides well, within the statistical error, with reference value.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2016

Limit on the radiative neutrinoless double electron capture of 36 Ar from GERDA Phase I

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. Here, a search for neutrinoless double electron capture of 36 Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of 36 Ar was established: T 1/2 > 3.6 × 10 21 years at 90% CI.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2016

Results of a search for daily and annual variations of the {sup 214}Po 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 τ(T{sub 1/2}) of the {sup 214}Po is presented. The methods of measurement and processing of collected data are reported. The results of analysis of time series values of τ with different time step are presented. Total measurement time was equal to 590 days. Averaged value of the {sup 214}Po half-life was obtained τ = 163.46 ± 0.04 μs. The annual variation with an amplitude A = (8.9 ± 2.3) × 10{sup −4}, solar-daily variation with an amplitude A{sub So} = (7.5 ± 1.2) × 10{sup −4}, lunar-daily variation with an amplitude A{sub L} = (6.9 ± 2.0) × 10{sup −4} sidereal-daily variation with an amplitude A{sub S} = (7.2 ± 1.2) × 10{sup −4} were found in a series of τ 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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

A technique for searching for the 2K capture in {sup 124}Xe with a copper proportional counter

An experimental technique for searching for the 2K capture in {sup 124}Xe with a large low-background copper proportional counter is described. Such an experiment is conducted at the Baksan Neutrino Observatory of the Institute for Nuclear Research of the Russian Academy of Sciences. The experimental setup is located in the Low-Background Deep-Level Laboratory at a depth of 4900 m.w.e., where the flux of muons of cosmic rays is suppressed by a factor of 10{sup 7} relative to that at the Earth’s surface. The setup incorporates a proportional counter and low-background shielding (18 cm of copper, 15 cm of lead, and 8 cm of borated polyethylene). The results of processing the data obtained in 5 months of live measurement time are presented. A new limit on the half-life of {sup 124}Xe with respect to the 2K capture is set at the level of 2.5 × 10{sup 21} years.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2015

Results on $\beta \beta $ decay with emission of two neutrinos or Majorons in $^{76}$ Ge from GERDA Phase I: GERDA Collaboration

A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1,2,3,7 were searched for. No signals were found and lower limits of the order of 10 23 yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76 Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76Ge with significantly reduced uncertainties is also given, resulting in T 2ν 1/2 = (1.926 ± 0.094) × 10 21 yr.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2015

Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in $^{76}$Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10% at the $Q$ value for $0\nu \beta \beta $0νββ decay in $^{76}$Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

First result of the experimental search for the 2K-capture of {sup 124}Xe with the copper proportional counter

First result of experiment for searching of 2K-capture of {sup 124}Xe with the large-volume copper proportional counter (LPC) is given. The 12 liters sample with 63.3% (44 g) of {sup 124}Xe was used in measurements. The limit on the half-life of {sup 124}Xe with regard to 2K(2ν)-capture for the ground state of {sup 124}Te (0{sup +} → 0{sup +}, g.s.) has been found: T{sub 1/2} ≥ 4.67 × 10{sup 20} yr (90% C.L.). A sample with volume 52 liters comprising of {sup 124}Xe (10.6L - 58.6 g) and {sup 126}Xe (14.1L - 79.3 g) will used at the next step of the experiment to increase a sensitivity of 2K-caption of {sup 124}Xe registration. In this case sensitivity to the investigated process will be at the level of S = 1.46 × 10{sup 21} yr (90% C.L.) for 1 year measurement.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2015

Production, characterization and operation of $^{76}$Ge enriched BEGe detectors in GERDA

The GERmanium Detector Array (Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of 76 Ge. Germanium detectors made of material with an enriched 76 Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new 76 Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present article reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the 76 Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. Lastly, the detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗