Light Hadron Physics

2009 ◽  
Vol 24 (supp01) ◽  
pp. 169-172
Author(s):  
Jian-Ming Bian ◽  
Vladimir Bytev ◽  
Ying Chen ◽  
Hong-Ying Jin ◽  
Shan Jin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Wave Length ◽  
Microscopic Structure ◽  
Experimental Measurements ◽  
Length Scales ◽  
Hadron Physics ◽  
Light Hadron ◽  
Structure Of Matter

Our knowledge about the structure of matter and the nature of the interactions between its constituent components follows a hierarchy that closely tracks the evolution of experimental measurements from low to higher and higher energies. For example, with an electron beam of a given energy, one can access the microscopic structure of matter at length scales corresponding to the de-Brogie wave length of the electrons that are being used: λ = 2π × 197.3 Mev · fm /Eγ, were Eγ is the energy of the photon that is exchanged in the experimentally observed process. As the energy of the beams that are available get higher and higher, the sizes of objects that can be probed get smaller and smaller…

Mechanism of Silicon Plate Decay in Aluminum Matrix under Electron Beam Effect

2020 ◽  
Vol 839 ◽  
pp. 32-36
Author(s):  
Vladimir Sarychev ◽  
Sergey Nevskii ◽  
Sergey Konovalov ◽  
Alexander Semin ◽  
Elena Martusevich ◽  
...  
Keyword(s):  
Electron Beam ◽  
Wave Length ◽  
Aluminum Matrix ◽  
Mechanical Stresses ◽  
High Current Electron Beam ◽  
Initial Stage ◽  
The Matrix ◽  
Current Electron ◽  
Rayleigh Taylor Instability ◽  
Expansion Coefficients

The decay mechanism of silicon particles in silumin in the thermal effect zone of low-energy high-current electron beam is proposed. Its essence consists in the fact that under the effect of the mechanical stresses the interface of silicon inclusion with aluminum matrix becomes instable resulting in the decay of silicon particle. It was supposed that the instability was the analog of Rayleigh-Taylor instability. The mechanical stresses arising due to the discrepancy of the elastic moduli and the linear expansion coefficients of the inclusion and the matrix are the analogs of gravity force. The analysis of the initial stage of instability within the frameworks of the visco-potential approximation has shown that the dependence of the rate of perturbations’ growth has only one maximum which falls on the wave length of the order ≈ 500 nm that is 5-fold higher than that of the experimental data. Such a discrepancy may be explained by the fact that when developing the model the temperature of the silicon inclusion and the aluminum matrix was considered to be constant, similar and being equal to the eutectic temperature of silumin. In fact, the temperatures of the inclusion and the matrix are different. To take into account the influence of these facts on the instability of the interface the new investigations are necessary.

Determination of microvascular oxyhemoglobin saturations using cryospectrophotometry

1990 ◽  
Vol 259 (6) ◽  
pp. H1912-H1920 ◽  
Author(s):  
B. M. Fenton ◽  
T. E. Gayeski
Keyword(s):  
Optical Density ◽  
Incident Light ◽  
Wave Length ◽  
Empirical Relationship ◽  
Complex Function ◽  
Vessel Diameter ◽  
Experimental Measurements ◽  
Independent Calibration ◽  
Hb Concentration

Although a four-wavelength method for cryospectrophotometric measurement of intravascular oxyhemoglobin (HbO2) saturations has previously been described, the relationship between experimental measurements and theory has not been clearly detailed. The current work utilizes an empirical relationship between HbO2 saturation measurements and reflected light oximetry, which is consistent with the two-flux theory of Kubelka and Munk (Z. Tech. Phys. 11a: 593-603, 1931). To obtain linear, concentration-independent calibration curves, the theoretical results require that 1) the complex function relating optical density, scattering, and absorption can be linearly approximated over the range of scattering and absorption coefficients used; and 2) the scattering coefficient is independent of wavelength. Incident light cannot easily be measured using reflection spectroscopy, which precludes the determination of isosbestic points. Therefore, equibestic wave-length pairs were used at which optical density differences were invariant with saturation. This allows numerous wavelength sets over the range 540-600 nm to be selected, rather than the limited choices of isosbestic wavelengths. Finally, the effects of freeze rate, freeze depth, Hb concentration, and vessel diameter are each discussed in terms of their influence on experimental measurements.

Some experimental measurements of the inner potentials of various crystals

1951 ◽  
Vol 206 (1085) ◽  
pp. 219-232 ◽  
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Oxide Layer ◽  
Experimental Measurements ◽  
Surface Layers ◽  
Fast Electrons ◽  
The Past ◽  
Materials Used ◽  
Made In

Although a large number of measurements of inner potential have been made in the past, the results have, on the whole, been far from consistent. These measurements were made by electron diffraction methods, and one possible reason for the lack of consistency is that, owing to the very limited penetration of the electron beam, the nature of the surface layers of the specimen will play an important part in the results obtained. In particular, if the specimen is a single crystal, there arises the possibility that different results will be obtained if the measurements are made using crystallographically different surfaces of the crystal. This possibility was examined experimentally and, for the materials used, no difference was found in the results obtained from different surfaces of the same crystal. Measurements were also made, using fast electrons (60 kV), of the inner potentials of metal crystals, and it was found that consistent results could be obtained in all cases if suitable experimental precautions were observed. It was also found that the presence of a thin contaminating layer on the surface (e. g. an oxide layer) did not affect the results provided the electron beam was able to penetrate the first few atomic layers of the specimen itself.

Experimental validation of a predictive model for numerical simulation of thermo-metallurgical phenomena during electron beam welding

2004 ◽  
Vol 120 ◽  
pp. 599-606
Author(s):  
M. Carin ◽  
Ph. Rogeon ◽  
D. Carron ◽  
Ph. Lemasson ◽  
D. Couedel ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Electron Beam ◽  
Heat Affected Zone ◽  
Experimental Validation ◽  
Electron Beam Welding ◽  
Welding Process ◽  
Experimental Measurements ◽  
Finite Element Code ◽  
Thermal Cycles

In the present work, thermal cycles measured with thermocouples embedded in specimens are employed to validate a numerical thermometallurgical model of an Electron Beam welding process. The implemented instrumentation techniques aim at reducing the perturbations induced by the sensors in place. A comparison between simulations performed on finite element code SYSWELD and the experimental measurements carried out on 16MnNiMo5 steel in the case of a partial penetration is achieved. This comparison is based on thermal cycles and also on microstructural evolutions, shapes of fusion zone (FZ) and heat affected zone (HAZ).

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