Working characteristics of the New Low-Background Laboratory (DULB-4900) Gavriljuk, Ju.M.; Gangapshev, A.M.; Gezhaev, A.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2013, Letnik:
729
Journal Article
Recenzirano
The Baksan Neutrino Observatory of the Institute for Nuclear Research of the Russian Academy of Science is one of the first and biggest underground laboratories in the world specially constructed to ...carry out different types of experiments in the field of nuclear physics, particle and astroparticle physics. Main technical characteristics of the new low-background laboratory DULB-4900 of the BNO are presented. The laboratory is located at a distance of 3700m from the main entrance of the observatory tunnel in the hall with dimensions ~6×6×40m3. Thickness of the mountain rock over DULB corresponds to 4900m w.e. and this deep location provides the cosmic ray flux reduction with the factor of about 107. The methods and results of the background level measurements both in the hall and operating facilities are given. Contamination of the radioactive 222Rn gas has been also measured in the air by using direct detection of γ-radiation of its daughter 214Bi distributed inside the volume of the low-background chamber. The results of the data analysis are presented and discussed.
•Main technical characteristics of the new unique Deep Underground Low Background laboratory of the Baksan Neutrino Observatory are presented.•The rock overburden of 4900m w.e. reduces the cosmic muon flux down to about (3.0±0.15)×109muonscm−2s−1.•The methods and results of the background level measurements both in the hall and operating facilities are given.
The resonant excitation of the
83
Kr first excited nuclear level (
E
= 9.4 keV) by solar axions whose fluxes depend on the axion–electron coupling constant
g
Ae
is sought. The γ- and X-ray photons ...and the conversion and Auger electrons from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences). As a result, a new constraint
≤ 1.50 × 10
–17
(90% C.L.) has been obtained for the axion–electron and axion–nucleon coupling constants, which corresponds to new constraints on the axion mass
m
A
≤ 320 eV and
m
A
≤ 4.6 eV in the KSVZ and DFSZ axion models, respectively.
Resonance excitation of the
83
Kr first nuclear level (
E
= 9.4 keV) by solar axions formed via the Primakoff mechanism is sought. The γ- and X-ray photons and the conversion and Auger electrons ...arising from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory. The following experimental constraint is obtained for the product of the axion–photon coupling constant and the axion mass:|
g
A
γ
×
m
A
| ≤ 6.3 × 10
-17
In the framework of the hadronic-axion model, this corresponds to a new axion-mass constraint of
m
A
≤ 12.7 eV at 95% C.L.
It is necessary to take into account the neutron background in almost all low-background research. In this paper an estimated neutron flux in the underground laboratory DULB-4900 of BNO INR RAS is ...presented. The estimation is based on results of measurements of radionuclide content in surrounding rock (granite).
Introduction. Monocyte chemoattractant protein type 1 (MCP-1) and plasminogen activator inhibitor type 1 (PAI-1) play a key role in inflammation, fibrosis and progression of renal dysfunction. ...Sulodexide advantages in vascular pathology treatment were proved by clinical trials, however, its efficiency in diabetic nephropathy (DN) was investigated insufficiently.
The aim of the present work – to study the influence of sulodexide on clinical and laboratory parametres, MCP-1 and PAI-1 levels in blood plasma of patients with DN.
Materials and methods. 76 type 2 diabetic patients with different stages of DN were observed. 44 patients received basic therapy with anti-diabetic drugs and ACE- inhibitors, 32 patients in addition to basic therapy were treated with sulodexide in a daily dose 600 LU. Concentrations of MCP-1 and PAI-1 in blood plasma were determined using immunoassay kits.
Results. In patients with DN when compared with healthy controls MCP-1 and RAI-1 levels in blood plasma significantly increased already at initial stages of the disease. Such changes may promote a development of inflammatory and fibrotic processes in kidneys. Progression of the disease was accompanied by more essential growth of MCP-1 and RAI-1 in DN patients with expressed clinical manifestations of kidney injury. Sulodexide treatment in patients with DN resulted in essential decrease of inflammatory and fibrotic markers and had positive effect on urinary protein excretion.
Conclusions. Glicosaminoglycans, in particular, sulodexide, is effective in complex treatment of patients with DN.
We report on the study of thermal neutron flux using monitors based on mixture of ZnS(Ag) and LiF enriched with a lithium-6 isotope at the deep underground laboratory DULB-4900 at the Baksan Neutrino ...Observatory. An annual modulation of thermal neutron flux in DULB-4900 is observed. Experimental evidences were obtained of correlation between the long-term thermal neutron flux variations and the absolute humidity of the air in laboratory. The amplitude of the modulation exceed 5% of total neutron flux.
Axions with an energy of 9.4 keV emitted in the
M
1 transition of
83
Kr nuclei in the Sun have been sought in the resonance absorption reaction
A
+
83
Kr →
83
Kr* →
83
Kr + γ,
e
(9.4 keV). A ...proportional gas chamber filled with krypton and placed in a low-background setup at the underground laboratory of the Baksan neutrino observatory was used to detect γ-ray photons and electrons appearing after the decay of a nuclear level. As a result, a new constraint has been determined on the isoscalar and isovector coupling constants of the axion with nucleons: |
g
AN
3
–
g
AN
0
| ≤ 1.29 × 10
–6
. This constraint results in the following new bound on the mass of the axion in the hadronic axion model:
m
A
≤ 100 eV (95% C.L.).
High-efficiency acceleration of charged particle beams at high gradients of energy gain per unit length is necessary to achieve an affordable and compact high-energy collider. The plasma wakefield ...accelerator is one concept being developed for this purpose. In plasma wakefield acceleration, a charge-density wake with high accelerating fields is driven by the passage of an ultra-relativistic bunch of charged particles (the drive bunch) through a plasma. If a second bunch of relativistic electrons (the trailing bunch) with sufficient charge follows in the wake of the drive bunch at an appropriate distance, it can be efficiently accelerated to high energy. Previous experiments using just a single 42-gigaelectronvolt drive bunch have accelerated electrons with a continuous energy spectrum and a maximum energy of up to 85 gigaelectronvolts from the tail of the same bunch in less than a metre of plasma. However, the total charge of these accelerated electrons was insufficient to extract a substantial amount of energy from the wake. Here we report high-efficiency acceleration of a discrete trailing bunch of electrons that contains sufficient charge to extract a substantial amount of energy from the high-gradient, nonlinear plasma wakefield accelerator. Specifically, we show the acceleration of about 74 picocoulombs of charge contained in the core of the trailing bunch in an accelerating gradient of about 4.4 gigavolts per metre. These core particles gain about 1.6 gigaelectronvolts of energy per particle, with a final energy spread as low as 0.7 per cent (2.0 per cent on average), and an energy-transfer efficiency from the wake to the bunch that can exceed 30 per cent (17.7 per cent on average). This acceleration of a distinct bunch of electrons containing a substantial charge and having a small energy spread with both a high accelerating gradient and a high energy-transfer efficiency represents a milestone in the development of plasma wakefield acceleration into a compact and affordable accelerator technology.
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