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Showing papers on "Doppler broadening published in 1993"


Journal ArticleDOI
C. Colón, G. Hatem, E. Verdugo, P. Ruiz, J. Campos 
TL;DR: In this paper, the Stark broadening parameters of Al(II) have been measured in a plasma produced by ablation with a Nd:YAG laser of an aluminum target.
Abstract: The Stark broadening parameters of the 1990.53, 2631.55, 2669.17, 2816.18, 3900.68, and 5593.23 A lines of Al(II) have been measured in a plasma produced by ablation with a Nd:YAG laser of an aluminum target. In order to obtain suitable experimental conditions for the homogeneity and stability of the plasma a study of the spatial and temporal plasma evolution in helium, argon, and nitrogen at different pressures was made. The broadening parameters were obtained with the aluminum target placed in molecular nitrogen at 1000 mbar, which provides appropriate measurements conditions. The Al(II) 4663.05 A line was used to determine the electron density in all cases. For this line the Stark shift parameter has been measured. Contributions to broadening arising from mechanism different than Stark broadening were estimated for every studied line.

132 citations


Journal ArticleDOI
TL;DR: A diagnostic has been developed to measure velocity and translational temperature in the plume of a 1-kW-class arcjet thruster operating on hydrogen and shows that although Doppler broadening is the only significant broadening mechanism, the fine structure of the transition must be taken into account.
Abstract: A diagnostic has been developed to measure velocity and translational temperature in the plume of a 1-kW-class arcjet thruster operating on hydrogen. Laser-induced fluorescence with a narrow-band cw laser is used to probe the Balmer α transition of excited atomic hydrogen. The velocity is determined from the Doppler shift of the fluorescence excitation spectrum, whereas the temperature is inferred from the lineshape. Analysis shows that although Doppler broadening is the only significant broadening mechanism, the fine structure of the transition must be taken into account. Near the exit plane, axial velocities vary from 4 to 14 km/s, radial velocities vary from 0 to 4 km/s, and swirl velocities are shown to be relatively small. Temperatures from 1000 to 5000 K indicate high dissociation fractions.

82 citations


Journal ArticleDOI
TL;DR: In this paper, the authors compare angular and temporal broadening for 10 pulsars and conclude that there is a uniform distribution of scattering material in the interstellar plasma with localized, strong scattering near young supernova remnants.
Abstract: Comparison of angular and temporal broadening for 10 pulsars suggests a uniform distribution of scattering material in the interstellar plasma with localized, strong scattering near young supernova remnants. Angular broadening and temporal broadening both measure the integrated strength of scattering along the line of sight, but with different weighting functions. Comparison of the two thus yields information on the distribution of scattering material along the line of sight. We report new measurements of angular diameter for the scattering disks of eight pulsars, and discuss two measurements from the literature. We compare these results with published measurements of temporal broadening

81 citations


Journal ArticleDOI
TL;DR: The spectral and spatial profiles of atomic hydrogen emission (the Balmer lines Hα and Hβ) from a low-pressure rf (13.56 MHz) discharge in H2+Ar mixtures have been studied as discussed by the authors.
Abstract: The spectral and spatial profiles of atomic hydrogen emission (the Balmer lines Hα and Hβ) from a low‐pressure rf (13.56 MHz) discharge in H2+Ar mixtures have been studied. The plasma emission was observed in a direction normal to the applied electric field. The Hα profiles exhibit central narrow components and wide components which are due to Doppler broadening. Comparisons of the Hα profiles in a pure hydrogen plasma with those in H2+Ar mixtures show that collisions of molecular hydrogen ions and hydrogen atoms with argon atoms play a significant role in the production of the Hα profile shapes.

62 citations


Journal ArticleDOI
TL;DR: The gamma ray induced Doppler broadening (GRID) technique as mentioned in this paper was proposed for the study of interatomic potential in solids, which can be used to probe the repulsive interatomic power potential in very low energies.
Abstract: The gamma ray induced Doppler broadening (GRID)-technique is reviewed. This experimental method, relying on ultra-high resolution gamma ray spectroscopy, involves the direct measurement of the Doppler broadening of gamma rays emitted when nuclei decay in-flight following recoil induced by preceding gamma rays. The technique permits the deduction of absolute transition rates in atomic nuclei formed after neutron capture and can therefore contribute to obtaining crucial information for sensitive tests of nuclear models. The method can be used for the study of lifetimes below a few picoseconds, but also, inversely, allows the investigation of interatomic collisions at very low energies. Thus one can probe the repulsive interatomic potential in solids. The characteristic features of the GRID technique are discussed and illustrated by some selected examples. Different approaches to model the slowing-down process at low energies are presented.

56 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used a difference-frequency laser spectrometer to measure N 2, O 2, H 2, Ar- and He-broadening coefficients and pressure shifts for Q - and R -branch transitions in the ν 1 fundamental band of ammonia.
Abstract: N 2 -, O 2 -, H 2 -, Ar- and He-broadening coefficients and pressure shifts have been measured for Q - and R -branch transitions in the ν 1 fundamental band of ammonia using a difference-frequency laser spectrometer. The J - K dependence of the broadening coefficients is much smaller than previously observed for self broadening of NH 3 . Semiclassical line broadening calculations for N 2 broadening are in reasonable quantitative agreement with the data, but they also exaggerate the J - K dependence. Dicke narrowing is observed as strong deviations from Voigt profiles at intermediate pressures and provides estimates for optical diffusion constants which correlate well with the mass diffusion constants for NH 3 in the various buffer gases.

56 citations


Journal ArticleDOI
TL;DR: The results showed that, in a long straight tube, the mean velocity can be estimated to within about 5% from the time-averaged maximum Doppler shift at various flow rates and pulsatilities, and the error due to geometrical spectral broadening, especially for large beam-vessel angles, can be corrected.
Abstract: It has been suggested that mean velocity of flow could be estimated by the time-averaged maximum frequency over an integral number of cardiac cycles (Gill 1985). The present study verified this theory experimentally with a computer-controlled flow phantom. The effects of some parameters on the relationship between mean velocity and time-averaged maximum frequency were also studied. Parameters investigated included beam-vessel angle, diameter of tubing, pulsatility, flow rate and stenosis. The velocities measured by the Doppler system were compared with the actual velocities. A simple theoretical model was also developed to compare with the experimental results. The results showed that, in a long straight tube, the mean velocity can be estimated to within about 5% from the time-averaged maximum Doppler shift at various flow rates and pulsatilities. The error due to geometrical spectral broadening, especially for large beam-vessel angles, can be estimated to within 3% and therefore corrected.

54 citations


Journal Article
TL;DR: Recent advances in both conceptual and numerical models of the Doppler ultrasound process are reviewed, and these advances to practical aspects such as spectral broadening, velocity estimation error, and data analysis error are related.
Abstract: Analysis of the signals, spectra and error bounds for Doppler ultrasound signals is challenging and involves numerous concepts in signal analysis, probability, acoustics, and fluid mechanics. Nonetheless, the results of this analysis must be accessible to both engineers and clinicians who work with ultrasound technology. The engineer who designs, builds, or maintains equipment must know whether specific artifacts are fundamental or can be eliminated. The clinician must be able to interpret whether specific signal features accurately represent the flow field or result from limitations of Doppler ultrasound. This article reviews recent advances in both conceptual and numerical models of the Doppler ultrasound process, and relates these advances to practical aspects such as spectral broadening, velocity estimation error, and data analysis error. It then reviews recent innovations in system implementation and signal analysis which are indicative of the future potential of Doppler ultrasound instrumentation.

54 citations


Journal ArticleDOI
Abstract: Cloud droplets may take a variety of paths to reach some location in a cloud and therefore may encounter varying growth conditions. This paper examines the effect of these variations on broadening of the droplet size distribution in cumuli. Diffusional growth of a collection of droplets is studied in detail using measurements obtained during the Cooperative Convective Precipitation Experiment (CCOPE) from the University of Wyoming's King Air research aircraft. A technique is described by which these measurements may be converted to the frame of reference of a moving droplet. Entrainment processes that are associated with variations in vertical velocity appear to have the effect of intensifying fluctuations in integral radius, which in turn produce variations in the supersaturation encountered by the droplets and thus opportunities for variations in growth. Contributions to spectral broadening arise from turbulent structures in the cloud, producing variations in integral radius as well as in the c...

52 citations


Journal ArticleDOI
TL;DR: In this article, the influence of Doppler broadening on the Rayleigh-backscattered signal is evaluated, and a correction method for this effect is presented, which requires an accurate estimate of the molecular and particle backscatter contributions, which is hardly achievable by usual lidar inversion techniques.
Abstract: The method of measuring atmospheric temperature profiles with differential absorption lidar (DIAL), based on the temperature dependence of oxygen absorption lines in the near infrared, is investigated in some detail. Particularly the influence of Doppler broadening on the Rayleigh-backscattered signal is evaluated, and a correction method for this effect is presented. This correction, however, requires an accurate estimate of the molecular- and particle backscatter contributions, which is hardly achievable by usual lidar inversion techniques. Under realistic conditions, resulting errors may be as high as 10 K. First range-resolved measurements using this technique are presented, using a slightly modified DIAL system originally constructed for water vapor measurements. Temperature profiles in the planetary boundary layer are obtained with a resolution of 82 m vertical and 30 min in time, showing an absolute accuracy of 4 K and an error in the temperature gradient of 0.5 K (100 m)−1. While much bet...

45 citations


Journal ArticleDOI
TL;DR: The observation of electromagnetically induced phase matching in collisionally broadened Pb vapor at a critical intensity at which the Rabi frequency of a dressing 1064-nm laser overcomes the Doppler broadening of the vapor.
Abstract: We report the observation of electromagnetically induced phase matching in collisionally broadened Pb vapor. At a critical intensity at which the Rabi frequency of a dressing 1064-nm laser overcomes the Doppler broadening of the vapor, the generated four-frequency-mixing signal at 283 nm increases in a steplike manner by a factor of 59.

Journal ArticleDOI
TL;DR: In this paper, a new method is described for forming films consisting of weakly interacting microcrystals by deposition of the solute in an argon matrix followed by complete evaporation of the argon.
Abstract: Infrared and Raman spectroscopy are used to examine effects of solid structure on vibrational line shapes in thin solid films of CO2 and N2O prepared by vapor deposition. A new method is described for forming films consisting of weakly‐interacting microcrystals by deposition of the solute in an argon matrix followed by complete evaporation of the argon. The infrared absorption bands of these films exhibit inhomogeneous spectral broadening in the range between the transverse and longitudinal frequencies of the bulk crystal. The origin of this broadening is shown to be the dependence of vibrational frequencies on size and shape of the microcrystals due to long‐range dipole interactions. In contrast, the spectra of polycrystalline films formed by direct vapor deposition are the same as for single crystals because the long‐range dipole interactions effectively couple vibrational motions across the grain boundaries. An analysis shows that inhomogenously broadened spectra are obtained whenever the separation be...

Journal ArticleDOI
TL;DR: In this paper, the effects of self-phase modulation, stimulated Raman scattering, and parametric four-photon interaction in an 8-μm core fibre of 4 m length with the effect of selective spectral attenuation in a ruby rod resulted in a rather smooth spectra extending from 685 nm to 830 nm (spectral width ≈ 2300 cm-1).
Abstract: Picosecond light pulses of a passively mode-locked ruby laser (pulse duration Δt L≈35 ps) are spectrally broadened in optical fibres of core diameters from 4 μm to 600 μm. Combining the effects of self-phase modulation, stimulated Raman scattering, and parametric four-photon interaction in an 8-μm core fibre of 4 m length with the effect of selective spectral attenuation in a ruby rod resulted in rather smooth spectra extending from 685 nm to 830 nm (spectral width ≈2300 cm-1).

Journal ArticleDOI
TL;DR: In this paper, the effect of the excitation wavelength on energy hopping among chromophores in well-defined positions was investigated in a [beta]-cyclodextrin bearing seven 2-naphthoyloxy chromophore.
Abstract: A [beta]-cyclodextrin bearing seven 2-naphthoyloxy chromophores is a good model for the study of the effect of the excitation wavelength on energy hopping among chromophores in well-defined positions, as in photosynthetic antennae. Absorption spectra, emission spectra, and excitation polarization spectra were recorded in a propylene glycol-dioxane glass at 200 K. Comparison is made with a bis(naphthoate) bichromophoric molecule. The parallelism between the increase of emission spectrum displacement and fluorescence anisotropy observed for the red edge of most vibronic bands, and especially for the 0-0 one, is established for the first time. It can be interpreted in terms of inhomogeneous spectral broadening due to solvation heterogeneity. The decrease of energy transfer that is observed upon red-edge excitation is evidence that energy hopping is not chaotic but directed toward lower-energy chromophores. 43 refs., 7 figs.

Journal ArticleDOI
TL;DR: In this paper, a joint nonequilibrium ionization analysis of spectral data from the Einstein Observatory of the SNR N132D in the LMC is presented on the basis of data from Focal Plane Crystal Spectrometer (FPCS) and the Solid State Spectrometers (SSS), and lower spectral resolution data from IPC and the Monitor Proportional Counter (MPC).
Abstract: A joint nonequilibrium ionization analysis of spectral data from the Einstein Observatory of the SNR N132D in the LMC is presented on the basis of data from the Focal Plane Crystal Spectrometer (FPCS) and the Solid State Spectrometer (SSS), and lower spectral resolution data from the IPC and the Monitor Proportional Counter (MPC). The FPCS detected individual emission lines of O VII, O VIII, Ne IX, Ne X, Fe XVII, and possibly Fe XX. Measured line widths for the oxygen lines suggest Doppler broadening that is roughly consistent with optically measured expansion velocities of 2250 km/s. At the SSS/IPC temperature, FPCS flux ratios constrain the O/Fe abundance to be at least 1.9 times its solar value and the O/Ne abundance to be 0.2-1.0 times its solar value. Models for remnants with progenitor masses of 20 and 25 solar masses are completely consistent with the data, while remnants with progenitor masses of 13 and 15 solar masses can be made consistent if the progenitors are required to eject a large fraction of their iron cores.

Journal ArticleDOI
TL;DR: In this paper, the authors test three different prescriptions for plasma experimentalists to avoid saturation broadening while maintaining a strong signal, and identify the prescription that is the easiest to use and the least sensitive to the spatial profile of the laser beam.
Abstract: Saturation broadening is an obstacle in using laser‐induced fluorescence as a plasma diagnostic. The Doppler‐broadened line shape ideally yields the ion velocity distribution function, but at high laser power, saturation of the optical transition leads to additional undesirable line broadening. We test three different prescriptions for plasma experimentalists to avoid saturation broadening while maintaining a strong signal. Based on experiments in an argon plasma, and a semiclassical atomic physics simulation, we have identified the prescription that is the easiest to use and the least sensitive to the spatial profile of the laser beam. This procedure is to measure the laser intensity that leads to saturation on the peak of the spectral line, and then to reduce the intensity to 20% of the saturation level.

Journal ArticleDOI
TL;DR: In this article, a treatment due to Kaulakys was used to estimate broadening and shift of 17 spectral lines of argon involving intermediate Rydberg states in the framework of impact theory.
Abstract: Results of experiments on low pressure broadening and shift of 17 spectral lines of argon involving intermediate Rydberg states are interpreted in the framework of the impact theory. Using a treatment due to Kaulakys it is shown that in pure argon and in the Ar-He mixture the experimental data are in satisfactory agreement with those calculated on the basis of the Fermi pseudopotential and polarization interaction. On the other hand, for the Ar-Ne mixture the theoretical broadening and shift values computed from this treatment are in poor agreement with experiment. The role of Maxwellian averaging as well as the scattering length in the analysis of the broadening cross-sections are also discussed.

Journal ArticleDOI
TL;DR: In this article, the absolute intensities and foreign gas broadening coefficients of the 18 0,18 ←18 1,18 and 11 1,10 ←11 2,10 transitions in the v 7 band of C 2 H 4 near 948 cm -1 have been measured at a spectral resolution of ∽5 × 10 -4 cm −1 using tunable diode laser spectrometry.
Abstract: Absolute intensities and foreign gas broadening coefficients of the 18 0,18 ←18 1,18 and 11 1,10 ←11 2,10 transitions in the v 7 band of C 2 H 4 near 948 cm -1 have been measured at a spectral resolution of ∽5 × 10 -4 cm -1 using tunable diode laser spectrometry. Ar, He, N 2 , and O 2 were used as the broadening gases. In order to determine the temperature dependence of the broadening coefficient, data were obtained at temperatures ranging from 150 to 296 K. The absolute intensity of the 5 0,5 ←5 1,5 transition was also found at 296 K. A band strength of 339 ± 10 cm -2 atm -1 was obtained from weighted averages of the individual line intensities and a rigid asymmetric top calculation.

Journal ArticleDOI
TL;DR: Equations that describe the steady-state dependence of the coherent-coupling properties of photorefractively induced refractive-index gratings on high-speed periodic biphase, sinusoidal, and triangular phase modulation impressed on one of the input optical beams are found and solved for both depleted and undepleted pump conditions.
Abstract: Equations that describe the steady-state dependence of the coherent-coupling properties of photorefractively induced refractive-index gratings on high-speed periodic biphase, sinusoidal, and triangular phase modulation impressed on one of the input optical beams are found and solved for both depleted and undepleted pump conditions. The period of the phase modulation wave form was kept short compared with the grating-formation time but did not cause significant spectral broadening. The results obtained were verified with data obtained from measurements of two-wave mixing in the photorefractive material, InP:Fe.

Journal ArticleDOI
TL;DR: The spectral superbroadening behavior of forward coherent radiation from a 10-cm-long liquid-filled cell is investigated by using an ultrashort and intense laser pulse as the pump source and the dominant contributions from stimulated Rayleigh-Kerr and Raman-K Kerr scattering are proposed.
Abstract: The spectral superbroadening behavior of forward coherent radiation from a 10-cm-long liquid-filled cell is investigated by using an ultrashort (∼0.5 ps) and intense (∼10 GW/cm2) laser pulse as the pump source. Five different transparent liquids (heavy water, water, carbon tetrachloride, benzene, and carbon disulfide) have been studied with a special experimental design that can distinguish the predominant contributions from the various possible mechanisms. Under the same pump condition, a very wide and symmetrical superbroadening (continuum) is observed on both the Stokes and the anti-Stokes side of the pump line for non-Kerr-type liquids such as heavy water and water, whereas only a red-shifted spectral broadening can be observed on the Stokes side for Kerr-type liquids such as carbon disulfide and benzene. For an explanation of the latter behavior, the dominant contributions from stimulated Rayleigh–Kerr and Raman–Kerr scattering are proposed.

Journal ArticleDOI
TL;DR: In this article, defects in separation-by-implanted-oxygen wafers with monoenergetic positron beams were studied with a Doppler broadening profile of the positron annihilation radiation and lifetimes of positrons.
Abstract: Defects in separation-by-implanted-oxygen wafers were studied with monoenergetic positron beams. Doppler broadening profiles of the positron annihilation radiation and lifetimes of positrons were measured as a function of incident positron energy for 200-keV O+-ion implanted Si specimens. For as-implanted specimens, the dominant defect species at a depth of ~20 nm was identified as vacancy-clusters and that in the region between ~200 nm and ~600 nm as vacancy-oxygen complexes. After annealing treatment, the formation of an oxide layer was observed in the region where a great number of vacancy-oxygen complexes formed. It was also found that interstitial Si atoms accumulated at the Si/SiO2 interface.

Journal ArticleDOI
TL;DR: In this article, a large spectral bandwidth stimulated Rayleighwing scattering (SRWS) induced by a picosecond laser pulse has been investigated in bulk liquid CS2 and the spectral broadening range of SRWS can reach up to 200 cm−1 on Stokes side.
Abstract: Large spectral bandwidth stimulated Rayleigh‐wing scattering (SRWS) induced by picosecond laser pulse has been investigated in bulk liquid CS2. The spectral broadening range of SRWS can reach up to 200 cm−1 on Stokes side. Many features of this scattering, such as the shift of the spectral maximum from excitation line and the temperature dependence, are presented. In order to explain the spectral broadening phenomenon, a possible mechanism based on collision‐induced light scattering is also discussed.

Journal ArticleDOI
TL;DR: In this paper, a momentum analysis of the hfs and the line-profile, and of the convolved curve is performed, and scaling laws for hfs splitting and its influence on spectral lines are given.
Abstract: Hyperfine structure is common in spectral lines. Hfs splits lines due to nuclear moments and shifts lines of different isotopes (IS). Both effects, even if they are small compared with the line- and instrumental-width, broaden and shift the lines and alter their shape and may lead to erroneous interpretations of spectra of astrophysical interest. The IS permits in principle the observation of isotope abundances (e.g. for H-D) but - if unresolved - shifts lines particularly if intensities are strongly affected by absorption (a fake Doppler shift, especially of interstellar lines). The hfs-splitting and its influence on spectral-lines is investigated with a momentum analysis of the hfs and the line-profile, and of the convolved curve. It is found that the hfs can be misinterpretated as Doppler broadening. In optically dense media (e.g. in stellar interior) hfs and IS may decrease the average transparency. Scaling laws for hfs and IS are given.

Journal ArticleDOI
TL;DR: It is shown that the relative bandwidth is both independent of the flow velocity and blood hematocrit and the relative Doppler bandwidth invariance theorem was experimentally verified with an in vitro steady laminar blood flow model.
Abstract: Intrinsic and nonstationary Doppler spectral broadening, and the skewness of the spectral representation, were evaluated experimentally using porcine red cell suspensions as ultrasonic scatterers. Theoretically, the relative Doppler bandwidth, defined as the intrinsic bandwidth divided by the mean Doppler frequency shift, should be velocity independent. The relative Doppler bandwidth invariance theorem was experimentally verified with an in vitro steady laminar blood flow model. It is shown that the relative bandwidth is both independent of the flow velocity and blood hematocrit. Using a pulsatile laminar flow model, the authors demonstrated that the relative Doppler bandwidth invariance theorem did not hold during flow acceleration and deceleration. In addition, a positive skewness of the Doppler spectra was observed during acceleration while a negative skewness was measured during the deceleration of blood. The effect of the window duration used in the Fourier spectral computation, on nonstationary broadening, is characterized. >

Journal ArticleDOI
TL;DR: The sensitivity of Doppler spectral indices to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity.
Abstract: The sensitivity of Doppler spectral indices (mean frequency, maximum frequency, spectral broadening index and turbulence intensity) to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity. The bias of spectral estimate has a more important effect on these indices than its variance. A too low order, in the case of autoregressive modelling and minimum variance methods, and excessive smoothing, in the case of the FFT method, result in increased errors of Doppler spectral indices. There is a trade-off between the errors resulting from a short data window and those due to insufficient temporal resolution.

Proceedings ArticleDOI
02 Jun 1993
TL;DR: In this article, a measurement of the temperature and linear density of Hg/sup +/ ions held in a linear ion trap (LIT) was performed by analyzing the sidebands on the 40.5 GHz resonance line.
Abstract: The authors describe a spectroscopic measurement of the temperature and linear density of Hg/sup +/ ions held in a linear ion trap (LIT). The inferred temperature and number result from analysis of sidebands on the 40.5 GHz resonance line. The temperature of the ion cloud is determined by the Doppler-broadened line when microwave radiation is propagated along the axis of the LIT. When propagation is perpendicular to the trap axis, the microwave sidebands are displaced from the trap secular frequency by an amount dependent on the ion cloud size and temperature. A Monte Carlo simulation of the ion trajectories inside the cloud is used to model the position of these sidebands for a given cloud temperature, and a comparison with measured sideband position is used to determine ion number. In clock operation with 7 /spl times/ 10/sup -14/ /spl tau//sup -1/2/ stability, the method described here was used to measure a -8.8 /spl times/ 10/sup -13/ frequency offset due to second order Doppler shift at 650 K and a linear ion density of 2.5 /spl times/ 10/sup 6//75 mm. >

Journal ArticleDOI
TL;DR: A direct fit of a modeled profile to the data is found to produce more consistent results and is less sensitive to noise than the method of least-squares fitting to low-order Fourier-transform coefficients derived from the data.
Abstract: Two techniques for recovery of the Doppler temperature from Fabry–Perot spectrometer observations of multiple-line profiles are tested. A direct fit of a modeled profile to the data is found to produce more consistent results and is less sensitive to noise than the method of least-squares fitting to low-order Fourier-transform coefficients derived from the data. This result is unexpected since the Fourier-transform method permits the reduction of noise by truncating the series of coefficients used to determine the temperature.

Journal ArticleDOI
TL;DR: In this paper, a direct knowledge of α-sticking probability in μCF of high density D-T mixture with high T concentration has been obtained by measuring a characteristic muonic X-ray from the (αμ) atoms (central energy of 8.2 keV with a correct Doppler broadening).
Abstract: Among a series of X-ray experiments on the muon catalyzed fusion (μCF) carried out by using pulsed muons at UTMSL/KEK, a direct knowledge of α-sticking probability (ωs) in μCF of high density D-T mixture with high T concentration has been obtained by measuring a characteristic muonic X-ray from the (αμ) atoms (central energy of 8.2 keV with a correct Doppler broadening). Combining with the recent X-ray measurements in (dμ) to3He and4He impurities, new insight is now obtained for the detailed background structure in the X-ray spectrum, suggesting the future direction for the X-ray measurements.

Journal ArticleDOI
01 Mar 1993-Vacuum
TL;DR: In this paper, the application of proton-induced narrow resonances in nuclear reactions as probes for depth profiling near-surface regions of solids has been investigated at projectile energies below 400 keV.

Journal ArticleDOI
TL;DR: In this paper, the temperature dependences of the annihilation parameters in GaS and GaSe were analyzed in terms of the thermal expansion coefficient of the lattice and a volume coefficient of annihilation parameter.
Abstract: Positron lifetime and Doppler broadening measurements have been performed on the layered semiconductors GaS, GaSe and GaTe in the temperature range 8-320 K. The temperature dependences of the annihilation parameters in GaS and GaSe are analysed in terms of the thermal expansion coefficient of the lattice and a volume coefficient of the annihilation parameter. The results reveal a noticeable volume effect on the positron annihilation characteristics in the bulk of GaS and GaSe; no evidence for positron trapping at grown-in defects was found in these samples.