Search

The composition, structure and mechanical properties of Ti–Al–Ta–N coatings obtained by high-power impulse magnetron sputtering and direct current magnetron sputtering have been studied using energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and nanoindentation. It has been established that for high-power impulse sputtering, the current and power of the magnetron discharge increase exponentially during the pulse and reach peak values that are an order of magnitude higher than similar characteristics for magnetron sputtering at direct current. A high level of ionization of the sputtered particles caused a significant increase in the number of ions in the particle flux deposited on the substrate. The suppression of the growth of columnar grains and the formation of a denser and more homogeneous microstructure were ensured by an increase in the intensity of ion bombardment of the growing coating. This made it possible to improve its mechanical characteristics. [ABSTRACT FROM AUTHOR]

Axions with an energy of 8.4 keV emitted in the М1 transition in 169Tm nuclei in the Sun are sought in the → 169Tm* → (8.4 keV) reaction of resonant absorption by 169Tm nuclei on the Earth using a thulium garnet crystal as a bolometric detector. The flux of monochromatic 8.4‑keV axions has been calculated. New constraints on the axion–nucleon coupling constants have been obtained and, as a result, new upper bounds on the axion mass eV and eV have been obtained at 90% C.L. in the KSVZ and DFSZ models, respectively. [ABSTRACT FROM AUTHOR]

The search for neutrino events in correlation with gravitational wave (GW) events for three observing runs (O1, O2 and O3) from 09/2015 to 03/2020 has been performed using the Borexino data-set of the same period. We have searched for signals of neutrino-electron scattering and inverse beta-decay (IBD) within a time window of ± 1000 s centered at the detection moment of a particular GW event. The search was done with three visible energy thresholds of 0.25, 0.8 and 3.0 MeV. Two types of incoming neutrino spectra were considered: the mono-energetic line and the supernova-like spectrum. GW candidates originated by merging binaries of black holes (BHBH), neutron stars (NSNS) and neutron star and black hole (NSBH) were analyzed separately. Additionally, the subset of most intensive BHBH mergers at closer distances and with larger radiative mass than the rest was considered. In total, follow-ups of 74 out of 93 gravitational waves reported in the GWTC-3 catalog were analyzed and no statistically significant excess over the background was observed. As a result, the strongest upper limits on GW-associated neutrino and antineutrino fluences for all flavors ( ν e , ν μ , ν τ ) at the level 10 9 - 10 15 cm - 2 GW - 1 have been obtained in the 0.5–5 MeV neutrino energy range. [ABSTRACT FROM AUTHOR]

Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a Ce– Pr source with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the Pr (0 ) Nd (1 ) allowed beta transition. [ABSTRACT FROM AUTHOR]

Operation of a model of a compact neutron source that can be used to calibrate dark-matter and electron-antineutrino detectors and to determine their response functions is demonstrated. The calibration neutron source in question is a combination of the Cf radionuclide, which undergoes spontaneous fission, producing neutrons, and an original silicon semiconductor detector. The latter provides a time reference for the neutron-emission instant by recording signals from fission fragments. [ABSTRACT FROM AUTHOR]

The resonant excitation of the 83Kr first excited nuclear level (E = 9.4 keV) by solar axions whose fluxes depend on the axion–electron coupling constant gAe 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 mA ≤ 320 eV and mA ≤ 4.6 eV in the KSVZ and DFSZ axion models, respectively. [ABSTRACT FROM AUTHOR]

DOI 10.1007/ s11182- 024- 03218- wRussian Physics Journal, Vol. 67, No. 7, July, 2024 25. docx CORRECTION 1082 To the article “ Microstructure and Mechanical Properties of Ti– Al– Ta– N Coatings Obtained by High- Power Impulse Magnetron Sputtering” by E. D. Kuzminov, A. Y. Derbin, and A. R. Shugurov, Vol. 67, No. 6, pp. 784– 790, June, 2024. Designations a and b in Fig. 4 should read b and a. Designations a and b in Fig. 5 should read b and a. 1064- 8887/ 24/ 6707- 1082 © 2024 Springer Nature Switzerland AG [Extracted from the article]

Stars are fuelled by the fusion of hydrogen into helium via two processes: the "pp chain" and the "CNO cycle." Neutrinos emitted in the core of the Sun are the only direct probe for the investigation of such processes. The Borexino experiment has performed a complete spectroscopy of the neutrinos from the "pp chain," and has recently reported the first experimental evidence of neutrinos from the CNO cycle, never observed before, being this process subdominant in the Sun (about 1% of the solar energy). This experimental evidence of the CNO neutrinos was obtained using the highly radiopure large-volume liquid-scintillator detector of Borexino. Advances in the thermal stabilization of the detector over the last five years enabled us to exploit a method to constrain the rate of Bi-210 contaminating the scintillator, the main background for such a measurement. Since the CNO cycle is dominant in massive starts, this result proves the evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe. [ABSTRACT FROM AUTHOR]

The search for neutrino events in correlation with 42 most intense fast radio bursts (FRBs) has been performed using the Borexino dataset from 05/2007 to 06/2021. We have searched for signals with visible energies above 250 keV within a time window of ± 1000 s corresponding to detection time of a particular FRB. We also applied an alternative approach based on searching for specific shapes of neutrino-electron scattering spectra in the full exposure data of the Borexino detector. In particular, two incoming neutrino spectra were considered: the monoenergetic line and the spectrum expected from supernovae. The same spectra were considered for electron antineutrinos detected through inverse beta-decay reaction. No statistically significant excess over the background was observed. As a result, the strongest upper limits on FRB-associated neutrino fluences of all flavors have been obtained in the 0.5–50 MeV neutrino energy range. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022390011 [ABSTRACT FROM AUTHOR]

Cosmogenic radio-nuclei are an important source of background for low-energy neutrino experiments. In Borexino, cosmogenic 11 C decays outnumber solar pep and CNO neutrino events by about ten to one. In order to extract the flux of these two neutrino species, a highly efficient identification of this background is mandatory. We present here the details of the most consolidated strategy, used throughout Borexino solar neutrino measurements. It hinges upon finding the space-time correlations between 11 C decays, the preceding parent muons and the accompanying neutrons. This article describes the working principles and evaluates the performance of this Three-Fold Coincidence (TFC) technique in its two current implementations: a hard-cut and a likelihood-based approach. Both show stable performances throughout Borexino Phases II (2012–2016) and III (2016–2020) data sets, with a 11 C tagging efficiency of ∼ 90 % and ∼ 63–66 % of the exposure surviving the tagging. We present also a novel technique that targets specifically 11 C produced in high-multiplicity during major spallation events. Such 11 C appear as a burst of events, whose space-time correlation can be exploited. Burst identification can be combined with the TFC to obtain about the same tagging efficiency of ∼ 90 % but with a higher fraction of the exposure surviving, in the range of ∼ 66–68 %. [ABSTRACT FROM AUTHOR]

A 4π β spectrometer consists of two Si(Li) detectors with a sensitive region that is more than 8-mm thick. Using this total-absorption spectrometer it is possible to make a direct measurement of β spectra without correcting the response function for the electron backscattering from the crystal surface. The β spectra of transitions to the excited states of daughter nuclei have been measured using an additional 3'' BGO detector of γ rays, which is connected in coincidence with the pair of Si(Li) detectors. [ABSTRACT FROM AUTHOR]

The cosmic silence of the underground Gran Sasso laboratory together with the exceptional radio purity of the liquid scintillator, has allowed Borexino to investigate the radiogenic heating of the Earth's interior and to contribute to various fields of experimental neutrino astronomy. This contribution is aimed to summarize the results obtained by Borexino on geo-neutrinos and on possible extra-terrestrial sources of antineutrinos such as supernovae explosions and solar flares. [ABSTRACT FROM AUTHOR]

Neutrinos emitted in the carbon, nitrogen, oxygen (CNO) fusion cycle in the Sun are a sub-dominant, yet crucial component of solar neutrinos whose flux has not been measured yet. The Borexino experiment at the Laboratori Nazionali del Gran Sasso (Italy) has a unique opportunity to detect them directly thanks to the detector's radiopurity and the precise understanding of the detector backgrounds. We discuss the sensitivity of Borexino to CNO neutrinos, which is based on the strategies we adopted to constrain the rates of the two most relevant background sources, pep neutrinos from the solar pp-chain and 210 Bi beta decays originating in the intrinsic contamination of the liquid scintillator with 210 Pb. Assuming the CNO flux predicted by the high-metallicity Standard Solar Model and an exposure of 1000 days × 71.3 t, Borexino has a median sensitivity to CNO neutrino higher than 3 σ . With the same hypothesis the expected experimental uncertainty on the CNO neutrino flux is 23%, provided the uncertainty on the independent estimate of the 210 Bi interaction rate is 1.5 cpd / 100 ton . Finally, we evaluated the expected uncertainty of the C and N abundances and the expected discrimination significance between the high and low metallicity Standard Solar Models (HZ and LZ) with future more precise measurement of the CNO solar neutrino flux. [ABSTRACT FROM AUTHOR]

A search for resonant absorption of solar axions by 169 Tm nuclei was carried out. A newly developed approach involving low-background cryogenic bolometer based on Tm 3 Al 5 O 12 crystal was used that allowed for significant improvement of sensitivity in comparison with previous 169 Tm based experiments. The measurements performed with 8.18 g crystal during 6.6 days exposure yielded the following limits on axion couplings: | g A γ (g AN 0 + g AN 3) ≤ 1.44 × 10 - 14 GeV - 1 and | g Ae (g AN 0 + g AN 3) ≤ 2.81 × 10 - 16 . [ABSTRACT FROM AUTHOR]

A spectrometer based on a Si(Li) detector has been tested by exposure to α particles with the aim of determining changes in the detector characteristics versus the fluence. As a result of 60-day measurements with a total fluence of 6.2 × 109 α particles, it has been established that the dependence of the deterioration in the energy resolution of α-particle peaks on the fluence is described by a linear function with a slope of Δσ/ΔФ = (8.4 ± 0.4) × 10–10 keV/α. The measured amplitude of the α-particle momentum decreases linearly with increasing fluence with a slope of (–4.8 ± 0.6) × 10–9 keV/α. These effects do not prevent reliable discrimination between the signals from α particles and fission fragments until the fluence reaches a value of 1010 α particles when the Si(Li) detector is a part of a neutron source for detecting fission fragments. [ABSTRACT FROM AUTHOR]

Spectra of electrons from beta decays of 144Ce-144Pr nuclei have been measured and analyzed in order to find a contribution from a heavy neutrino. For the neutrino with the mass mνH in the interval of 150-350 keV, a new upper bound |UeH|2 ≤ (2−5) × 10−3 at 90% C.L. has been found for the mixing parameter. [ABSTRACT FROM AUTHOR]

Resonance excitation of the 83Kr 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:|gAγ × mA| ≤ 6.3 × 10 -17 In the framework of the hadronic-axion model, this corresponds to a new axion-mass constraint of mA ≤ 12.7 eV at 95% C.L. [ABSTRACT FROM AUTHOR]

The characteristics of a beta spectrometer that consists of a total-absorption Si(Li) detector and a drift Si detector are presented. Using this spectrometer, it is possible to efficiently separate β radiation of nuclei from concomitant X and γ rays. The method is based on coincidences between signals from the thick and thin detectors. The spectrometer can be used to precisely measure the shape of the β spectra of various radioactive nuclei, in particular, of the 144Pr nucleus, which is the most promising antineutrino source for searching for neutrino oscillations into a sterile state. [ABSTRACT FROM AUTHOR]

The aim of the SOX-Borexino project is to verify or falsify the existence of eV-scale sterile neutrinos. The existence of sterile neutrinos is suspected because of several anomalies, which were observed in previous experiments. A ~3.7 PBq electron antineutrino source made of Ce will be installed below the Borexino detector at LNGS, Italy, to search for short-baseline oscillations of active-to-sterile neutrinos within the detector volume. Source delivery and beginning of data acquisition is planned for end of 2016, preliminary results are expected already in 2017. [ABSTRACT FROM AUTHOR]

A method for calibrating the energy scale of a scintillation detector using γ rays has been proposed and implemented. The technique is based on Compton scattering in the scintillation detector, followed by photoelectric absorption of a scattered γ-ray photon in a Ge detector. The novelty of the method consists in placing the γ-ray source and the scintillation and Ge detectors tightly to each other. The method is efficient for detectors with a low-Z material for which the ratio of the cross sections for Compton scattering and photoeffect is great in value and the attenuation length of the γ-ray flux is comparable to the detector dimensions. The described technique can be used to precisely investigate the dependence of the light yield in a scintillator on the electron energy. [ABSTRACT FROM AUTHOR]

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Purpose: Precipitation of weakly basic drugs in intestinal fluids can affect oral drug absorption. In this study, the implications of self-association of brivanib alaninate in acidic aqueous solution, leading to supersaturation at basic pH condition, on its solubility and oral absorption were investigated. Methods: Self-association of brivanib alaninate was investigated by proton NMR spectroscopy, surface tension measurement, dynamic light scattering, isothermal titration calorimetry, and molecular modeling. Drug solubility was determined in various pH media, and its tendency to supersaturate upon pH shift was investigated in buffered and biorelevant aqueous solutions. Pharmacokinetic modeling of human oral drug absorption was utilized for parameter sensitivity analyses of input variables. Results: Brivanib alaninate exhibited continuous, and pH- and concentration-dependent self-association. This phenomenon resulted in positive deviation of drug solubility at acidic pH and the formation of a stable supersaturated drug solution in pH-shift assays. Consistent with the supersaturation phenomenon observed in vitro, oral absorption simulations necessitated invoking long precipitation time in the intestine to successfully predict in vivo data. Conclusions: Self-association of a weakly basic drug in acidic aqueous solution can increase its oral absorption by supersaturation and precipitation resistance at the intestinal pH. This consideration is important to the selection of parameters for oral absorption simulation. [ABSTRACT FROM AUTHOR]

Axions with an energy of 9.4 keV emitted in the M1 transition of Kr nuclei in the Sun have been sought in the resonance absorption reaction A + Kr → Kr* → 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- g| ≤ 1.29 × 10. This constraint results in the following new bound on the mass of the axion in the hadronic axion model: m ≤ 100 eV (95% C.L.). [ABSTRACT FROM AUTHOR]

The very low radioactive background of the Borexino detector, its large size, and the well proved capability to detect both low energy electron neutrinos and antineutrinos make an ideal case for the study of short distance neutrino oscillations with artificial sources at Gran Sasso. This paper describes the possible layouts of 51Cr ( νe) and 144Ce- 144Pr $$ \left( {{{\overline{\nu}}_e}} \right) $$ source experiments in Borexino and shows the expected sensitivity to eV mass sterile neutrinos for three possible different phases of the experiment. Expected results on neutrino magnetic moment, electroweak mixing angle, and couplings to axial and vector currents are shown too. [ABSTRACT FROM AUTHOR]

A search for axioelectric absorption of solar axions produced in the $p + d \rightarrow{^{3}\rm{He}}+\gamma~(5.5~\rm{MeV})$ reactions has been performed with a BGO detector placed in a low-background setup. A model-independent limit on an axion-nucleon and axion-electron coupling constant has been obtained: $| g_{Ae}\times g_{AN}^{3}|< 2.9\times 10^{-9}$ for 90 % confidence level. The constrains of the axion-electron coupling have been obtained for hadronic axion with masses in (0.1-1) MeV range: | g|≤(1.4-9.7)×10. [ABSTRACT FROM AUTHOR]

We have studied the α-decays of Po into Pb and of Po into Pb tagged by the coincidence with the preceding β-decays from Bi and Bi, respectively. The Rn, Th, and Rn sources used were sealed inside quartz vials and inserted in the Counting Test Facility at the underground Gran Sasso National Laboratory in Italy. We find that the mean lifetime of Po is (236.00 ± 0.42(stat) ± 0.15(syst)) μs and that of Po is (425.1 ± 0.9(stat) ± 1.2(syst)) ns. Our results, obtained from data with signal-to-background ratio larger than 1000, reduce the overall uncertainties and are compatible with previous measurements. [ABSTRACT FROM AUTHOR]

The axio-electric effect in silicon atoms is sought for solar axions appearing owing to bremsstrahlung and the Compton process. Axions are detected using a Si(Li) detector placed in a low-background setup. As a result, a model-independent constraint on the axion-electron coupling constant | g| ≤ 2.2 × 10 has been obtained, which leads to the bounds m ≤ 7.9 eV and m ≤ 1.4 eV (at 90% C.L.) for the mass of the axion in the DFSZ and KSVZ models, respectively. [ABSTRACT FROM AUTHOR]

xions of energy 14.4 keV that originated from the M1 transition in Fe nuclei in the Sun were sought by using the resonance-absorption reaction A+Fe → Fe* → Fe+ γ (14.4 keV). Asectioned Si(Li) detector arranged in a low-background facility was used to record photons from this reaction. This resulted in setting a new limit on the axion couplings to nucleons, |−1.19 g + g| ≤ 3.0×10. Within the hadronic-axion model, the respective constraint on the axion mass is m ≤ 145 eV (at a 95% C.L.). [ABSTRACT FROM AUTHOR]

The Pauli exclusion principle was tested for nucleons in the C nucleus by using data from the Borexino detector. The approach used consisted in seeking photons, neutrons, and protons, as well as electrons and positrons, emitted in the Pauli-forbidden transitions of nucleons from the 1 P shell to the filled 1 S shell. Owing to a uniquely low background level in the Borexino detector and its large mass, the currently most stringent experimental limits were obtained for the probabilities and relative intensities of Pauli-forbidden transitions for the electromagnetic, strong, and weak channels. [ABSTRACT FROM AUTHOR]

Data of the Borexino experiment on the detection of the reaction involving elastic solar-neutrino scattering on an electron are presented. The fraction of electron neutrinos in the fluxes of Be and B neutrinos is in agreement with the LMA MSW oscillation solution. The uniquely low level of the Borexino detector background made it possible to set new limits on the effective magnetic moment of the neutrino, on the possible violation of the Pauli exclusion principle, and on some other rare processes. [ABSTRACT FROM AUTHOR]

A search for the axioelectric absorption of 5.5-MeV solar axions produced in the p + d → 3He + γ (5.5 MeV) reaction was performed with two BGO detectors placed inside a low-background setup. Constraints on the axion-electron coupling constant were obtained for axions with masses in the (0.1–1.0)-MeV range: g Ae ≤ (1.8–9.0) × 10−7. The solar positron flux from A → e− + e+ decay was determined for axions with masses m A > 2 me. Using the existing experimental data on the interplanetary positron flux, a new constraint on the axion-electron coupling constant for axions with masses in the (1.2–5.4)-MeV range was obtained: g Ae ≤ (1–5) × 10−17. [ABSTRACT FROM AUTHOR]

We searched for resonant excitation of the first excited state of the 169Tm nucleus by axions formed inside the Sun by the Primakoff effect, A + 169Tm → 169Tm* → 169Tm + γ (8.41keV). Gamma quanta with an energy of 8.41keV were registered by a sectionalized Si(Li) detector installed in a low-background setup. As a result, we set a new upper limit for the photon to axion coupling constant, g Aγ(GeV−1) m A(eV) ≤ 1.06 × 10−5, which for a hadronic axion model corresponds to a mass limit of m A ≤ 169 eV at a 90% confidence level. [ABSTRACT FROM AUTHOR]

A search for resonant absorption of 14.4 keV solar axions by a 57Fe target was performed. The Si(Li) detector placed inside the low-background setup was used to detect the γ-quanta appearing in the deexcitation of the 14.4 keV nuclear level: A+57Fe→57Fe*→57Fe+ γ. The new upper limit for the hadronic axion mass has been obtained of m A≤159 eV (95% c.l.) ( S=0.5, z=0.56). [ABSTRACT FROM AUTHOR]

Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions emitted in the M1-transitions of 7Li*. The Compton conversion of axion to a photon A+e→e+γ, axioelectric effect A+e+Z→e+Z, decay of axion in two photons A→2γ and Primakoff conversion on nuclei A+Z→γ+Z are considered. The upper limit on constants of interaction of axion with electrons, photons and nucleons – gAegAN≤(1.0–2.4)×10-10 at mA≤450 keV and gAγgAN≤5×10-9 GeV-1 at mA≤10 keV are obtained (90%c.l.). For heavy axions with mass at 100A<400 keV the limits gAe<(0.7–2.0)×10-8 and gAγ<10-9–10-8 are obtained in assumption that gAN depends on mA as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor and artificial radioactive sources. [ABSTRACT FROM AUTHOR]

Search for resonant absorption of solar axions by 57Fe and 169Tm nuclei, leading to the excitation of the first nuclear level: 57Fe: A + 57Fe → 57Fe* → 57Fe + γ and A + 169Tm → 169Tm* → 169Tm + γ, has been performed. To this end, the energy spectra of the Si(Li) detector with 57Fe and 169Tm targets have been measured. The detector and targets were located in a low-background setup equipped with passive and active shields. A new upper limit on the axion mass: m A ≤ 330 eV (90% confidence level) has been established from the spectrum of 57Fe (30 days). Measurements with a 169Tm target during 8 days gave a new upper limit on the product of the axion-photon coupling constant and the axion mass: g Aγ (GeV−1) × m A (eV) ≤ 2.9 × 10−4 (90% confidence level). [ABSTRACT FROM AUTHOR]

The resonant absorption of solar axions by 57Fe nuclei, which is accompanied by the excitation of the first excited nuclear level: A + 57Fe → 57Fe* → 57Fe + γ(14.4 keV), is sought. To seek 14.4-keV photons, a Si(Li) detector and an enriched 57Fe target are used. The detector and target are placed in a low-background setup equipped with passive and active shieldings. As a result, a new upper limit m A ≤ 360 eV (at 90% C.L.) has been determined for the axion mass. [ABSTRACT FROM AUTHOR]

Electron antineutrino interactions above the inverse beta decay energy of protons (Eν̄e>1.8 MeV) were looked for with the Borexino counting test facility (CTF). One candidate event survived after rejection of background, which included muon-induced neutrons and random coincidences. An upper limit on the solar ν̄e flux, assumed having the 8B solar neutrino energy spectrum, of 1.1×105 cm-2 s-1 (90% C.L.) was set with a 7.8 ton × year exposure. This upper limit corresponds to a solar neutrino transition probability, νe→ν̄e, of 0.02 (90% C.L.). Predictions for antineutrino detection with Borexino, including geoneutrinos, are discussed on the basis of background measurements performed with the CTF. [ABSTRACT FROM AUTHOR]

The resonance absorption of solar axions by 7Li nuclei, which is accompanied by the excitation of the first nuclear level of lithium a + 7Li→7Li*→7Li + γ, is sought. To this end, the energy spectrum has been measured by an HPGe detector that is surrounded by a LiOH layer. A new upper limit ma≤16 keV (at 90% C.L.) has been determined for the mass of the hadron axion. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

It is shown that a large-volume liquid organic scintillator detector with an energy resolution of 10 keV at 200 keV (1σ) will be sensitive to solar pp neutrinos, if operated at the target radiopurity levels for the Borexino detector or the solar neutrino project of KamLAND.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The Pauli exclusion principle (PEP) has been tested for nucleons (n,p) inandnuclei, using the results of background measurements with the prototype of the Borexino detector, the Counting Test Facility (CTF). The approach consisted of a search for,n,pand/or’s emitted in a non-Paulian transition of 1P- shell nucleons to the filled 1S1/2 shell in nuclei. Similarly, the Pauli-forbiddendecay processes were searched for. Due to the extremely low background and the large mass (4.2 tons) of the CTF detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established:,,,,and, all atC.L. [ABSTRACT FROM AUTHOR]

If heavy neutrinos with mass m[sub ν[sub H]] ≥ 2m[sub e] are emitted in the decays of [sup 8]B in the Sun, then ν[sub H] → ν[sub L] + e[sup +] + e[sup –] decays should be observed. In the present work, the results of background measurements with the Borexino Counting Test Facility have been used to obtain bounds on the number of these decays. As a result, new limits on the coupling |U[sub eH]|[sup 2] of a massive neutrino in the range of 1.1 MeV to 12 MeV have been derived (|U[sub eH]|[sup 2] ≤ 10[sup –3]–10[sup –5]). The obtained limits on the mixing parameter are stronger than obtained in previous experiments using nuclear reactors and accelerators. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The possibility of using ultrapure liquid organic scintillator as a low-energy solar neutrino detector is discussed. The detector with an active volume of 10 t and 4π coverage will count 1.8 pp neutrinos and 5.4[SUP7] Be neutrinos per day with an energy threshold of 170 keV for the recoil electrons. The evaluation of the detector sensitivity and backgrounds is based on the results obtained by the Borexino collaboration with the Counting Test Facility (CTF). The detector can be build at the LNGS underground laboratory as an upgrade of the CTF detector using already developed technologies. [ABSTRACT FROM AUTHOR]

Results of background measurements with a prototype of the Borexino detector were used to obtain bounds on the lifetime of radiative neutrino decay ν[sub H] → ν[sub L] + γ. The new lower limit for the lifetime of pp and [sup 7]Be neutrinos is τ[sub c.m.](ν[sub H] → ν[sub L] + γ)/m[sub ν] ≥ 4.2 × 10[sup 3] s eV[sup –1] (α = 0). It is more than an order of magnitude stronger than the value obtained in previous experiments using nuclear reactors and accelerators. © 2002 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Searches for invisible axions emitted in the electromagnetic transitions of isomeric nuclei are continued. It is found experimentally that the probability of axion emission in an M1 transition in [sup 125m]Te is less than 8.5 × 10[sup –6] (90% C.L.).© 2002 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The [sup 45]Ca β spectrum has been measured with a Si(Li) detector. New limits on the mixing parameter (U[sub eH² ≤ 0.005) for a neutrino with mass in the interval 75-100 keV are obtained. The possibility of a monochromatic peak appearing at the end of the β spectrum is analyzed. [ABSTRACT FROM AUTHOR]

A method of searching for the invisible axion emitted in M transitions of isomeric nuclei is proposed. It is determined experimentally that the probability of emission of an axion in the M1 transition in [sup 125m]Te is ≤1.3·10[sup -5] (90% confidence level). © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Mechanically dissociated brain cells of 14 and 18-day-old mouse embryos and of mouse neonates were cultured for 3 weeks. Neurons, oligodendrocytes and astrocytes were identified at the 7th, 14th and 21st day in vitro by staining the cultures using the indirect immunoperoxidase technique with antisera directed against neuron specific enolase, galactocerebroside, myelin basic protein and glial fibrillary acidic protein. The number of neurons and oligodendrocytes was higher in embryonic cultures than in neonate cultures. The expression of some antigens was also different in the two types of culture. Our results indicate that the development of brain cells in mechanically dissociated brain cell cultures depends on the age of the animal at the time of plating. [ABSTRACT FROM AUTHOR]

The polysaccharides were studied in an electroreceptor organ, the tuberous organ of Gnathonemus petersii (Mormyridae). Histochemical methods (P.A.S., alcian blue, toluidine blue and iron colloidal reactions) allowed us to demonstrate the existence of glycogen in the sensory cytoplasm, and P.A.S. positive polysaccharides in the sensory cavity. The polysaccharides were shown to be amylase proof; they display an acidity due to the existence of sulphated radicals. The histochemical study was completed by a cytochemical analysis: a treatment with thiocarbohydrazide (TCH) according to the Thiery's method. This method allowed us to estimate the glycogen concentration, its localization, and relationship with cellular organites within the sensory cytoplasm, as well as to differentiate the highly glycogenous type II cells of the platform from the other accessory cells (Derbin and Szabo, 1968). After a treatment for 20 hours with TCH, silver stained grains were visible on the polysaccharide filaments of the sensory chamber, between the microvilli and the vacuoles of the epidermal cells lining to the sensory cavity. Silver grains coated the outed surface of the microvilli. Such polysaccharides were not identical to the filamentous polysaccharides of the cavity. In order to determine the cytochemical localization of the polysaccharide acid groups, sections were stained with iron salts. The colloidal iron constitutes a deposit opaque to electrons and located both on the filamentous polysaccharides of the sensory cavity and in the vacuoles of the epidermal cells, indicating that only these filamentous polysaccharides display acid radicals. [ABSTRACT FROM AUTHOR]