Condensation of uranium hexafluoride in supersonic Laval nozzle flow

6 carried in a mixture of argon and methane was studied experimentally in a continuously operating supersonic Laval nozzle. The onset of condensation was detected by Rayleigh light scattering. Measurements of static pressure in the nozzle, together with the equations of isentropic flow, permitted the determination of the relation between the pressure of UF₆, P_k, and the temperature, T_c, at the observed onset of condensation. The experiments addressed conditions of condensation onset in the range 80<T_c<160 K and 0.1<P_k<3.0 Torr. We found that there was no influence of the pressure of the carrier gas argon, which ranged from 3.5 to 68 Torr at onset points, on the onset of condensation. The dependence of the supersaturation ratio on temperature at the onset could be expressed by a straight line as deduced by P.P. Wegener and B.J.C. Wu from the classical theory of homogeneous nucleation [Adv. Colloid Interface Sci. 7, 325 (1977)]. These results indicate that supersonic expansion in the nozzle formed single-component droplets of UF₆ in a mixture of UF₆, CH₄, and Ar under the experimental conditions studied herein. Received: 23 December 1997 / Revised version: 7 April 1998     

Metastable plasma of hydrated ions

The conditions are considered under which a plasma of ions with shell of water molecules can exist for an anomalously long time in a state which is supercooled as regards its degree of ionization.General Physics Institute, Russian Academy of Sciences, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 3–10, April, 1995.     

Reactor laser using a mixture of xenon with uranium hexafluoride

The possibility is considered of developing a reactor laser based on a mixture of xenon, uranium hexafluoride, and a buffer gas. The kinetic scheme of populating the xenon monofluoride exciplex is analyzed. The conditions for the possibility of less stringent requirements on the nuclear pumping intensity are investigated. The conditions that ensure the necessary heat dissipation under various reactor-laser operating conditions are considered. It is shown that in principle supersonic flow of the working gas can ensure energy output in the form of laser radiation.Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 120, pp. 43–50, 1980.     

The operation of high-speed emergency protection based on uranium hexafluoride

The dynamic properties of a gas-liquid one-time direct emergency protection device used in nuclear power plants are studied using computer experiments within a model suggested. In the case of reactivity emergency, an absorbent is introduced into the reactor core automatically without human intervention and any external control.     

Analysis of the optical band positions for manganese (IV) ions in trigonal barium titanium hexafluoride and barium silicon hexafluoride crystals

The optical band positions (or crystal field energy levels) of manganese (IV) ions in trigonal barium titanium hexafluoride and barium silicon hexafluoride crystals are computed from the full diagonalization (of energy matrix) method founded on the two-spin–orbit-parameter model which consists of the effects from both the spin–orbit parameters of dⁿ ion and ligand ions. The computed results are in rational agreement with the experimental values. It is found that the large difference of first excited state splitting ΔE (²E) between the manganese (IV)-doped barium titanium hexafluoride and barium silicon hexafluoride crystals is owing mainly to the great difference of trigonal distortion between the fluorine octahedral clusters in the two host crystals.     

Formation of the distribution function of the aerosol-particle radii for the hydrolysis products of uranium hexafluoride in industrial premises

We consider UO₂F₂ and HF aerosol particles that formed in the air of industrial premises at a factory of the nuclear industry. The distribution function g ₁ of the aerosol-particle radii at a given space-time point is analyzed. Some of the lognormal distribution functions that are related to a gas-dispersed environment of the working premise are considered. The deviation of g ₁ from lognormal distribution functions is estimated. The related problems of calculating the average transmission coefficients of atoms of toxic substances (uranium or fluorine) in the human body during inhalation are discussed.     

Luminescence of uranium ions in sodium fluoride crystals

The luminescence spectra of bulk and fiber sodium fluoride crystals activated with uranium ions have been analyzed. Luminescence of uranium centers at temperatures of 8.5 and 300 K is considered and the features of the luminescence spectra of these centers in crystals of different dimension are analyzed. The luminescence spectra are simulated with allowance for the spectral-line profiles. Possible models of uranium centers are considered.     

Estimation of the permissible time for human presence in the zone of an emergency release of uranium hexafluoride with inhalation

This paper describes a complex model that allows one to calculate the mass of harmful substances that enter the human body in the conditions of an emergency release of uranium hexafluoride (UF₆) in a work space. It covers all parts of the process, from the pollution of the work environment by gaseous UF₆, before the penetration of toxic substances in the body. The model is built based on the available data in the literature about the research on this subject. On the basis of numerical calculations carried out within the framework of the constructed model it is concluded that the predominant harmful role belongs to inhalation. It shows the relationship between the residence time in an emergency and the amount of fluorine taken into the body, which is the most toxic to humans. The allowable residence time of a person in an emergency release zone is estimated.     

On the mass spectrum of SQCD

We present a detailed study of the mass spectrum of SQCD in the vector, axial vector, Goldstone and flavour-singlet channels in the caseN _c =M _F by means of SVZ sum rules in their finite energy version. Our analysis constrains the relative strength of the two independent scalar condensates, φ⁺φ> and \(\left\langle {\tilde \phi \phi } \right\rangle \) .     

Low mass glueballs in the meson spectrum

The spectrum of bound states of gluons is discussed within the MIT bag model. We argue that (1) contrary to previous analysis there is no light exotic 1^?+ state in the two gluon sector, (2) experiments on the three gluon sector can clearly differentiate the bag model from other models, (3) the state seen in J/ψ radiative decays at 1.4 GeV is most likely a pseudoscalar glueball, and (4) there should be a second 2⁺⁺ state underneath the f(1270) resonance.     

Verification of a mathematical model that describes the action of uranium hexafluoride on the human body in facilities of the atomic industry

A complex mathematical model that describes the action on the human body of uranium hexafluoride that enters the air of the work space in facilities of the atomic industry is considered. Partial models that describe the pollution of the work space and percutaneous and inhalation entries of toxic substances to the body are discussed. Initial equations are presented and basic experimental premises are considered. The choice of several important parameters of the complex model is discussed. The predictions of the model are compared with known experimental results.     

Absence of discrete spectrum in highly negative ions

LetH _N be the Hamiltonian for the Coulomb system consisting ofN particles of like charge in the field of a fixed point chargeZ. We show that if the particles are bosons, thenH _N has no discrete spectrum whenNN ₀=cZ ² for some constantc. If the particles are fermions, thenH _N is bounded below uniformly inN. These results can be extended to molecules and to other power law potentials.Research supported by the National Science Foundation, MCS78 -20455 USAOn leave from Department of Mathematics, University of Lowell, Lowell, MA O1854 USA     

Absence of discrete spectrum in highly negative ions

We extend the results of [1] to fermions, i.e., we show that ifH _N is the Hamiltonian forN electrons in the field of a fixed point chargeZ, then there is a constantc such thatH _N has no discrete spectrum forN≧N ₀=cZ ^6/5.     

Mixed-valence induced during the intercalation of lithium ions into uranium fluorides

The mixed-valence in uranium fluorides LiU₄F₁₆ and UF₄ can be induced (or eliminated) by the intercalation (deintercalation) of lithium ions into these compounds. These processes can be electrochemically performed both with LiU₄F₁₆ (or LiTh₄F₁₆) and with monoclinic UF₄ as starting materials using a liquid electrolyte composed of propylene carbonate as solvent and LiClO₄ as salt. In the cases of UF₄ and LiU₄F₁₆, the electrochemical intercalation of Li⁺ into the host matrix is reversible and a maximum of three Li⁺ ions per U₄F₁₆ unit can be reversibly intercalated. Additional experimental evidences of the mixed-valence in these fluorides are presented such as the Electron Paramagnetic Resonance characterization of the starting materials and of those electrochemically modified.     

On the mass spectrum of elementary particles

A simple theory of the elementary particle mass spectrum is proposed. It originates from the Dirac idea of the free electron motion and from the transformed Klein-Gordon equation. The theory is based on an equation that includes the squared mass operator having an infinite sequence of orthogonal eigenfunctions and a discrete spectrum of eigenvalues. A discrete mass formula is derived. It yields values of mass that are in agreement with present-day empiric data for elementary particles.     

激光质谱法的质量数定标研究

介绍了激光质谱法的基本原理,利用已知苯和甲苯质荷比与飞行时间的关系,对质谱信号进行了精确定标.利用该方法对丙酮的多光子电离质谱进行了验证,得到了理想的实验结果.     

SUSY spectrum and the Higgs mass in the BLMSSM

The predictions for the mass of the light CP-even Higgs are investigated in the context of a simple extension of the Minimal Supersymmetric Standard Model where the baryon and lepton numbers are local gauge symmetries. This theory predicts the existence of light charged and neutral leptons which give extra contributions to the Higgs mass at the one-loop level. We show the possibility to satisfy the LEP2 bound and achieve a Higgs mass around 125 GeV in a supersymmetric spectrum with light sfermions and small left–right mixing in the stop sector. We make a brief discussion of the unique leptonic signals at the Large Hadron Collider. This theory predicts baryon number violation at the low scale and one could avoid the current LHC bounds on the supersymmetric mass spectrum.     

Vibronic excitation spectrum of alkali aluminometaphosphate glasses containing uranium

The absorption, excitation and emission spectra of metaphosphate glasses MPO₃.Al(PO₃)₃ (M = Li, Na, K) doped with 1 or 2 w.% of uranium oxide have been measured at room temperature. The spectra were compared with those of solid uranyl nitrate and its water solution. The excitation band of glasses peaking at about 420 nm shows a great deal of structure like that of the solution. The diffuse structure would be due to the electron vibronic transitions in the uranium centre of a molecular form (probably uranyl (UO₂)²⁺).