Measurement of muonic X-ray intensities and Coulomb capture ratios in chlorides

Muonic X-ray spectra of 32 chlorides have been measured with Ge detectors. Coulomb capture ratios and Lyman X-ray intensities were determined, and correlations to target data established. The experimental capture ratios agree well with the values from a recently proposed formula.     

Dynamics of muonic atom cascade in hydrogen-helium mixtures

The deexcitation of excited muonic protium and deuterium in the mixture of hydrogen and helium isotopes is considered. Methods of experimental determination of the probability of direct atomic muon capture by hydrogen and muon transfer rates from excited muonic hydrogen to helium are proposed. Theoretical results for the population of the muonic atoms in the ground state, , are compared with the existing experimental data. Results obtained for mixtures are of interest for investigation of nuclear fusion in muonic molecules. Received: 6 August 1998 / Revised: 1st October 1998 / Accepted: 2 October 1998     

Coulomb deexcitation of muonic hydrogen within the quantum close-coupling method

The Coulomb deexcitation of muonic hydrogen in collisions with the hydrogen atom has been studied in the framework of the fully quantum-mechanical close-coupling method for the first time. The calculations of the l-averaged cross sections of the Coulomb deexcitation are performed for (μp)_n and (μd)_n atoms in the initial states with the principal quantum number n = 3–9 and at relative energies E = 0.1–100 eV. The obtained results for the n and E dependences of the Coulomb deexcitation cross sections drastically differ from the semiclassical results. An important contribution of the transitions with Δn > 1 to the total Coulomb deexcitation cross sections (up to ～37%) is predicted.     

Charge exchange and Coulomb de-excitation of muonic atoms in low energy collisions

The muon transfer and Coulomb de-excitation rates at the collisions of (pμ) _n , (dμ) _n and (tμ) _n muonic atoms in excited states n = 3, 4, 5 with hydrogen isotopes p, d, t are calculated for all possible combinations of hydrogen isotopes. The advanced adiabatic approach (AAA) [1–3] is adapted and used to the specific case of muonic atom collisions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Time-evolution of cascade processes of muonic atoms in hydrogen-helium mixtures

The time-dependence of the population of muonic hydrogen states in hydrogen-helium mixtures is calculated for principal quantum number n. The number of muons transferred to helium nuclei is also determined. The dependence of the population of the ground state of muonic hydrogen on time and target density and the helium concentration is also considered. The results are in agreement with recent experimental data. The comparison of the calculated yield of K lines of X-ray in pure hydrogen and deuterium with experimental data indicates the essential role of the Coulomb deexcitation process. Possible Stark mixing is also analysed. Received 17 February 1999 and Received in final form 9 June 1999     

On the molecular limit of Coulomb gases

We give a partially new analysis of the molecular nature of matter. A key feature is a property of the Coulomb potential as ³ is decomposed into simplices. A further application thereof is given in an appendix.     

Coulomb capture of muons and atomic radius

An earlier theoretical treatment of the Coulomb capture of muons has been extended to take the radius of the (electronic) atom into account. Smaller radii are shown to favor the capture, in agreement with earlier experimental findings.     

The muonic X-ray cascade in fluorine following the μ-transfer from hydrogen

The X-ray cascade following theμ-transfer reactionμp + F →p + μF is interpreted in terms of a pseudolevel crossing model which predicts the angular momentum distribution of then=6 level essentially populated by the transfer. The resulting cascade agrees with recent experimental results.     

Coulomb deexcitation and nonresonant charge exchange of muonic hydrogen in mixtures of hydrogen isotopes

The process of inelastic collisions of excited muonic hydrogen has been considered in the framework of the asymptotic theory of nonadiabatic transitions. The Coulomb deexcitation and chargetransfer rates are calculated in the energy range 0.001–100 eV taking into account the electron-screening effect for excited states in the range n = 3–10 for various isotopic configurations. The text was submitted by the authors in English.     

Experimental investigation of the concentration dependence of the permittivity in ternary disordered systems

The concentration dependence of the complex permittivity in a model insulator-semiconductor-conductor ternary system is studied. A maximum in the real part of the permittivity is found, and a qualitative explanation of this finding is suggested.     

On the statistical mechanics of classical Coulomb and dipole gases

A detailed, rigorous study of the statistical mechanics-screening- and critical properties, phase diagrams, etc., of classical Coulomb monopole and dipole gases in two or more dimensions is presented. The statistical mechanics of the two-dimensionalXY and Villain models is reconsidered and related to the one of two-dimensional lattice Coulomb gases. At low temperatures and moderate densities those gases behave like dipole gases. The Kosterlitz-Thouless transition is analyzed in that perspective and characterized by an order parameter. Techniques useful for a proof of existence of such a transition in a two-dimensional hard-core Coulomb gas are developed and applied to the study of dipole gases.A Sloan Fellow, and supported in part by NSF grant No. DMR 7904355.     

Explanation of the pressure and concentration dependence of the EFG in noncubic metals and alloys

The pressure and concentration dependence of the electric field gradient (EFG) in noncubic metals and alloys is calculated within a pseudopotential approach. The results agree well with experiment. Far-reaching consequences about the Debye-Waller-factor and about the origin of the EFG are discussed.     

On the models of Coulomb capture of negative particles

Various models of atomic capture of negative mesonic particles are tested against 321 experimental Coulomb-capture ratios, measured on binary systems: gas mixtures, alloys and simple compounds. The comparison has shown that the general agreement between theory and experiment is not satisfactory. We tried to improve on the models by introducing adjustable parameters to be estimated by fitting the experimental data. The predictions of the model proposed by Schneuwly, Pokrovsky and Ponomarev (SPP) are closest to the atomic capture ratios for alloys and compounds while the data measured in gas mixtures are better approximated by the empirical formula of Vasilyev et al. The theoretical formula of Daniel fails in describing the capture in the light elements.     

基于声压-振速测量的平面近场声全息实验研究

常规的近场声全息均是采用全息面声压或质点振速作为输入量求解,由于采用单一输入量无法分离来自全息面背向声波的干扰,因此要求所有声源均位于全息面的同一侧,即测量声场为自由声场,这种要求大大限制了近场声全息的实际应用.基于声压-速度测量的近场声全息以全息面上声压和质点振速同时作为输入量,通过建立和求解两侧声源在全息面上的声压和质点振速耦合关系,可以实现全息面两侧声波的分离,从而解决上述问题.文中在前期对声场分离技术研究的基础上,基于欧拉公式和有限差分近似,推导了新的基于声压-速度测量的平面近场声全息理论公式.随后通过实验检验了该方法在有背景源干扰情况下实现声场分离和重建的有效性.     

Theory of the Coulomb capture of negative mesonic particles

The Coulomb capture of negative mesonic particles is semiclassically calculated in closed form. Expressions are given for energy loss and angular momentum loss, capture ratios, and spectral flux densities of the slow particles in matter. The effect of a centrifugal barrier on the capture ratio and the spectral flux density is shown. Numerical results are given for gaseous Ar and a hypothetical solid of Z = 18 with an assumed atomic radius corresponding to average condensed matter. There is a great difference between the results for the two cases.     

Mineral-derived Li4SiO4-based adsorbent for post-combustion CO2 capture: An experimental and kinetic investigation

Li₄SiO₄-based adsorbent is considered as a promising choice for the CO₂ removal from power plants’ flue gases. However, the relatively high raw materials cost still limits its industrial applications. In this work, aiming to reduce the cost of Si-source, three novel natural occurring minerals including the pumicestone, the montmorillonite and the attapulgite were employed as Si-sources for the production of Li₄SiO₄-based adsorbents. The phase composition, surface morphology as well as the cyclic CO₂ ad-desorption performance of obtained adsorbents were experimentally and kinetically investigated. It is found that the Si content of minerals directly determines the adsorption capacity of adsorbents, resulting in a relatively high and stable capacity of nearly 0.1 g/g within 22 cycles for the pumicestone derived adsorbent compared with other adsorbents obtained from minerals. Moreover, the excess Ca inside the minerals is found forming CaO, which is harmful to the desorption performance of adsorbent owing to the occurrence of Li–Ca–CO₂ interactions. As a consequence, Si-source with high Ca content was proven inadaptable for the synthesis of Li₄SiO₄-based adsorbent, which provides guidance for the future selection of mineral Si-sources in this field.