Elastic Resonance Research Articles

Harmonic response of cylindrical and toroidal shells to an internal acoustic field. Part II: Results

General systems of cylindrical and toroidal shells enclosing an acoustic medium are studied by their response to acoustic excitation by a plane wave with harmonic time dependence. Noteworthy features are: (i) at frequencies low compared to the fundamental the torus’ cross section deforms as an ogive due to meridional curvature, (ii) coupled elastic resonances lag resonances of the empty system, (iii) additional circumferential harmonics appear besides 0 and 1 when the exciting frequency is closest to resonances of the shell’s cross section, (iv) longitudinal acoustic resonances lag resonances of the system with rigid walls, and (v) nonresonant response peaks occur at coincidence. The present analysis demonstrates the inadequacy of beam theory to model the response of short and thin shell configurations at frequencies above the fundamental elastic resonance.

Tunnelling spectroscopy of Cd xHg 1− xTe detectors

The p-n junctions, in epitaxial graded-band-gap Cd x Hg 1 - x Te layers, with slowly varying band parameters and with molar composition x from 0.20 to 0.26, were produced by Hg diffusion. The analysis of current-voltage ( I - U) and log 10 I versus U plots indicates the backward-type behaviour of the junctions. Also, d 2 U/d I 2 versus U and d 2 I/d U 2 versus U dependencies show several singularities, which support the suggested occurrence of (1) tunnel-resonance electron transitions through localized states within the energy band gap (elastic resonance scattering) and (2) interaction between tunnelling electrons and longitudinal phonons and localized states (non-elastic resonance scattering). Analysis of R 0 A versus T plots leads to the conclusion that the trap-to-trap tunnel current dominates at lower temperatures and either the generation-recombination current or surface-leakage current limit the junction operation at higher temperatures. The energy of the HgTe-mode LO phonon is found to be equal ≅ 18 meV and the energy of the shallow acceptor state equal to 15–25 meV above the valence band.

Effect of inelastic transitions on the line shape of surface resonances

We show that the inelastic resonant processes discussed by Cantini and Tatarek affect the line shape of elastic resonances. This effect is not included in the Debye-Waller correction to the repulsive matrix elements, as used by Hutchison and others, and may explain the discrepancy between the line strengths predicted by Hutchison's formulae and those observed by Cantini et al.

Decay Properties of Highly Excited Mesons in a Duality Scheme with the Quark-Model Hadron Spectrum

The duality property of hadron scattering amplitudes has been now recognized as fundamental, but its concrete representation has not been established yet. The finite-energy sum rule is not symmetric in treating two dual channels. The Veneziano-type models have, at present, no unique way to specify their pole structures. Further, there is the difficulty of appearance of negative-norm states about them. As to their applications to the meson-meson scattering, a promising amplitude has been presented by Frampton,!) who has impo~ed a restraint on (an infinite number of) satellite terms using a symmetric group. The 7[7[-47[7[ Frampton amplitude (A 4(1) in his work) does not involve odd daughters, and it is presumably free from the difficulty of appearance of ghosts. Applications of the Veneziano-type models to the baryonmeson scattering have, however, faced more difficulties. In this respect, Hoyer and Uschersohn) have propo~ed a new method of imposing duality constraints recently. The scheme given by them is composed of an infinite number of localized duality relations which involve only observed resonances. According to the supposition that the dynamics of hadrons is governed essentially by the quark-orbital Regge trajectory, presented by Bando et al.) and Nakkagawa et al.) who studied the hadron dynamics and the hadron spectrum in the quark model, it is considered to be worth while to generalize the Hoyer-Uschersohn relation assuming the harmonic-oscillator spectrum of SU(6)@O(3)L multiplets for the idealized hadron spectrum. Such a generalization has been done by the author recently:) In fact, the obtained relation has been found to be successful for both of the baryon-meson and meson-meson scattering. About low-lying resonances, it has been shown to be consistent with experiments.) In this paper, we discuss the elastic resonance widths of highly excited mesons in the above scheme with the quark-model hadron spectrum. Our purpose is to examine whether or not the scheme is hopeful to the absence of negative· norm states. Let us consider the 0-0-4 0-0processes where the u-channel is exotic. The present scheme for the process under discussion is

Elastic Resonance of a Liquid-Crystal Blue Phase

The blue phase of cholesteryl oleate is shown to exhibit the macroscopic shear elasticity expected for a three-dimensionally ordered structure. The first measurements of blue-phase elastic constants are presented.

Selective observation of elastic body resonances by using long pulses to excite a ringing response in the body

An elastic body submerged in water will ring when insonified by sound whose frequency is the same as one of the resonances of that body. Correspondence has been established between these normal mode resonances of the body and the individual circumferential waves predicted by creeping wave theory. Insonifying the target with a relatively long sinusoidal pulse results in a series of superimposed responses consisting of the specular reflection and a series of creeping waves arriving after successive circumnavigations of the body. Echoes, both analytically and experimentally obtained, from spherical targets will be used to identify the properties of the resonance ringing and associate the superimposed echoes with the resonance poles that can be predicted theoretically.

Zero-angular-momentum resonances in atom-atom collisions

In elastic atom-atom collisions resonances can be formed even for zero angular momentum, provided that the potential has a barrier. It is shown that their contribution in the cross section is much larger than expected from their energy width. This is due to an unusually large broadening effect in the angular momentum variable which only occurs for zero-angular-momentum resonances. The broadening effect in the partial waves is analyzed, and it is shown how such resonances affect the cross sections.

Magnetostatic surface wave devices for UHF and L band applications

Magnetostatic wave (MSW) delay lines and filters made with gallium-substituted garnet films (Ga:La-YIG) are described. These devices were tuned over the 0.3 - 2 GHz frequency range by varying the dc bias field in the range 10-500 Oe depending on the saturation magnetization of the garnet film, therefore complementing already demonstrated MSW devices covering the 2-15 GHz frequency range. Techniques for reducing the amplitude and delay ripples and for minimizing the coupling to elastic resonances are described. The agreement between theoretical predictions, measured amplitude and group delay responses was fairly good. Typically, for a delay line at 500 MHz, the insertion loss is l0 dB; the amplitude ripples are less than 0.5 dB peak-to-peak and the group delay ripples are less than 10 nsec peak-to-peak. Linearly dispersive delay lines show a dispersion of about 1 nsec/MHz over more than 120 MHz bandwidth, while bandpass filters exhibit 25 MHz bandwidth with less than 0.3 dB amplitude ripples.

RST analysis of monostatic and bistatic acoustic echoes from an elastic sphere

We readdress the basic problem of the scattering of acoustic waves by an elastic sphere, now under the dissecting knife of the Resonance Scattering Theory (RST), with the purpose of illustrating the power of the method, and the versatile options and information it offers. These options include ease of understanding, novel physical interpretation of the phenomenon, and striking calculational simplicity. The principal findings presented here include: (a) the actual modal resonances, quantitatively separated from the corresponding modal backgrounds in the frequency (the ‘‘acoustic spectrogram’’—already a target-identification tool) domain, and in the combined frequency and mode-order domain (the ‘‘response surface’’). (b) The bistatic plots of the scattering cross section, to illustrate the point that if the cross section is redetermined at certain selected observation angles, the resonance contributions from each individual mode can actually be isolated from those of all other modes. (c) A study of the nulls or dips present in the partial waves (i.e., modes), and in the summed cross section. We show the cause and physical meanings of these dips analytically and computationally, in both instances. (d) A derivation of the analytic conditions predicting the nulls and also the influence of the elastic resonance (SEM) poles in the scattered echoes. These conditions, which emerge from our scattering approach, are shown to be in agreement with early results of Love [A Treatise on the Mathematical Theory of Elasticty (Dover, New York, 1944)], obtained on a purely vibrational basis. A tungsten carbide sphere is used in all the examples, since this is a favorite target for experimental calibrations. Our future work will underline the intimate connection between his direct approach, and that (leading to the solution) of the inverse scattering problem for sonar target identification.

A three-body scattering problem in the molecular mass limit

A three-body problem is studied that involves the scattering of a heavy particle from a bound state of a heavy and a light particle. For fairly large mass ratios we find many partial waves involved in the scattering with both elastic and inelastic resonances present. It is also found that virtually all of the breakup inelasticity is in the odd partial waves, if the heavy particles are identical bosons. The same problem is solved in the Born-Oppenheimer approximation and it is found that the effective potential between the heavy particles develops an imaginary part in the odd partial waves and thus gives a quantitative account of the three-body results including the inelasticity. The linear combination of nuclear orbitais method is applied to the same problem and is found to be inadequate.

An evolutionary model for the Southwest Norwegian Caledonides

<h3>Abstract</h3> Dyslexia is a common neurodevelopmental disorder with a strong genetic component. Independent genetic association studies have implicated the <i>KIAA0319</i> gene in dyslexia, however its function is still unknown. We developed a cellular knockout model for KIAA0319 in RPE1 cells via CRISPR-Cas9n to investigate its role in processes suggested but not confirmed in previous studies, including cilia formation and cell migration. We found that KIAA0319 knockout increased cilia length and accelerated cell migration. Using Elastic Resonator Interference Stress Microscopy (ERISM), we detected an increase in cellular force for the knockout cells that was restored by a rescue experiment. Combining ERISM and immunostaining showed that KIAA0319 depletion reduced the number of podosomes formed by the cells. Our results suggest an involvement of KIAA0319 in mechanosensing and force regulation and shows for the first time that podosomes exert highly dynamic, piconewton vertical forces in epithelial cells.

Theory ofK-shell ionization during nuclear resonance scattering

Recently the measured proton-induced C K-shell ionization probability was found to vary significantly near the 0.461-MeV j = 1/2+ elastic resonance in /sup 12/C. Since the resonance was so wide that time-delay effects on K-shell ionization should be very small, it was hypothesized that this effect was due to the exchange of angular momentum between the projectile motion and electron. Assuming a potential description of the nuclear scattering, we make a completely quantum-mechanical calculation of the ionization probability in the distorted-wave Born approximation and show that angular momentum effects do not account for these results. We also show how the amplitude for monopole excitation is augmented by the ''shake-off'' or ''sticking'' term found in the semiclassical theory of Ciocchetti and Molinari, and display the formal correspondence between the semiclassical and quantum-mechanical theories. Numerical calculations of the ionization probability show only a slight dip at the minimum in the p-C elastic cross section, opposite in sign and of much smaller magnitude than the reported variation.

Magnetoelastic properties of amorphous alloys

A phenomenological description of the first and second order magnetoelastic effects is developed for amorphous ferromagnetic alloys: magnetostriction, Δ E effect and magnetoelastic contributions to the sound velocities are discussed in detail. A brief description is given of the main experimental methods used to study these effects. A general review of the available data is given for thermal expansion, spontaneous and forced magnetostriction, static elastic properties, acoustic resonance and sound waves propagation under a magnetic field.

Nearfield acoustic radiation from spherical shells

In this study, the acoustic nearfield of excited spherical shells is investigated. The interaction of the acoustic medium with the vibration response of an elastic spherical shell due to an excitation by a point force or an acoustic point source is investigated analytically and experimentally. Thus, only axisymmetric, nontorsional motion of the spherical shell is considered, with a thin shell theory that includes extensional and bending deformation. The elastic spherical shell resonances were computed when in vacuo and when submerged in light (air) and heavy (water) acoustic medium. These were verified experimentally by testing two duralumin shells, a = 8 in. in radius and wall thicknesses h = 0.0514 and 0.1069 in. The measured resonance frequencies were within 5% of those predicted in air and in water for identified mode numbers up to 34. The measured mean‐line driving point admittance also agreed well with the predicted ones to within 3 dB. [Work supported by NAVSEA.]

Sonic method and apparatus for activating a fluid in treating material or polishing parts employing coupling resonator member

One or more elongated members, such as bars or tubes of an elastic material are sonically vibrated, by means of a mechanical oscillator coupled thereto, at a frequency such as to set up resonant elastic standing wave vibration in the elastic resonators. A conduit or chamber is provided in which material to be treated or parts to be polished along with an appropriate fluid treatment material are placed, the parts and material either being flowed through the conduit or retained therein for a predetermined treatment time. Sonic energy is coupled from the resonator member or members to the treatment conduit at selected positions along the standing waves generated in the resonators, this coupling being made adjacent the node and anti-node of such vibration in one embodiment; at two anti-nodes in a second embodiment, and a single anti-node in a third embodiment, to obtain various types of vibratory motion in the treatment conduit or chamber for various effects on the parts or other material being treated.

Observations of elastic and quasi-elastic nuclear gamma resonance absorption in hemoglobin crystals

Mössbauer spectra of carbonmonoxy-liganded human hemoglobin crystals, selectively enriched with 57Fe in the α-chains, were measured at 260 K and at 101 K a quadrupole doublet of lorentzians with the usual, narrow line width was observed, while at 260 K a superposition was observed of one doublet with a narrow and a second one with a broadened line width. The narrow doublet is attributed to elastic absorption processes and the broadened doublet to quasi-elastic ones. The spectrum at 260 K indicates that fluctuational processes between conformational substates of the quarternary “R” structure do exist.

Ion-ion recombination in (X++Y-+Z) systems at low gas densities. II. Elastic ion-neutral collisions

For pt.I see ibid., vol.13, no.18, p.3649 (1980). The study of Bates and Flannery (1968) of recombination in (X++Y-+Z) systems is expanded so as to provide recombination coefficients at low gas densities for all systems of physical interest. An expression for the collisional rate coefficient for all elastic and inelastic events via ion-pair-neutral collisions is derived. Comparison between elastic and symmetrical resonance charge transfer ion-neutral collisions for promoting energy changes in the ion pair is presented. An equilibrium-deactivation model is proposed and considered together with Thomson's approach (1924) within a detailed treatment of the rate for collisional transitions. The role in recombination of the various types of collisional transitions is thoroughly examined.

Application of a band-crossing model for resonances inO16+O16scattering

A band-crossing model that has been proposed as a possible mechanism for resonances in heavy ion reactions is applied to energy dependent structure in the $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ system. The recently observed intermediate-width structure in the 6.13 MeV gamma-radiation yield can be well understood in terms of the band-crossing model, assuming the crossing of the elastic potential resonance band and an aligned rotational band in which the intrinsic spin ($3\ensuremath{\hbar}$) and the relative angular momenta are coupled to their maximum value. Numerical calculations based on this model reproduce all of the observed energy dependent structure of the cross section in the $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ interaction, i.e., the gamma-radiation yield from the ${3}_{1}^{\ensuremath{-}}$ state of $^{16}\mathrm{O}$, as well as the total fusion and elastic scattering data. Each oscillation in the fusion excitation function is interpreted as reflecting a shape resonance of each new grazing partial wave in the entrance channel as it becomes active with increasing energy. The observed anticorrelation of the total fusion and the 90\ifmmode^\circ\else\textdegree\fi{} excitation function of elastic scattering data is reproduced naturally by the model. It is concluded that these data support the existence of nuclear molecular resonances in the $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ system.NUCLEAR REACTIONS $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ scattering, $10&lt;~{E}_{\mathrm{c}.\mathrm{m}.}&lt;~41$ MeV; calculated elastic scattering excitation functions, fusion cross sections, and ${3}_{1}^{\ensuremath{-}}$ inelastic cross sections. Resonance mechanism for heavy ion reactions.

Studies in nuclear spectroscopy using the (γ, γ') and the (γ, n) reactions

The technique of using elastic and inelastic resonance scattering of monochromatic protons for studying the spectroscopic properties of energy levels in various nuclei is discussed. The photons are produced by thermal neutron capture in some metallic elements. The resonance levels are photoexcited by a random overlap between one of the incident γ-lines and one nuclear level of the scattering isotope. It is shown that such (γ, γ') reactions may be used for measuring the excitation energies, the spins, parities and radiative widths of the resonance levels. Also the excitation energies and spins of the low lying levels, the absolute strengths of E1, M1, E2, M2 transitions from the resonance level can be obtained. For unbound levels, the study of the (γ, n) reaction can provide information on the spin, parity, neutron width of the resonance level, interference between various multipolarities, and spectroscopic information on the energy level of the A − 1 isotope. The advantages of using stronger γ-sources from hugh flux reactors is discussed.

Differential and total cross sections inHe2+-He collisions

The authors obtain differential cross sections for ${\mathrm{He}}^{2+}$ impact on $\mathrm{He}(1{s}^{2})$ using a molecular treatment of the collision and the impact-parameter eikonal approximation. Small angles and low energies for which elastic and two-electron resonance transfer reactions occur are considered. The results are compared with the experimental data of Chen et al. Total cross sections are also given and compared with other theoretical and experimental results.