• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.773-782
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• 2016

The performance of the CT-TDLAS (computed tomography-tunable diode laser absorption spectroscopy) is strongly dependent upon the line broadening functions. The line of the laser beam used in the TDLAS is scattered by the natural broadening, the collisional broadening and the doppler broadening. The influence of the natural broadening to the experimental spectra obtained in the TDLAS is negligible. The influences of the collisional broadening and the doppler broadening to the experimental spectra are relatively large, in high pressure gas flows and in high temperature low pressure gas flows, respectively. In this study, optimal coefficients are proposed for the doppler broadening function by using the experimental data obtained in a flat burner test. The optimal coefficients were ${\gamma}_j=0.16$ and n=0.37. Using these coefficients, the temperature and concentration distributions at the engine exhaust gas pipe have been calculated showing their validities.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.138-138
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• 2006

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1471-1481
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• 2022

This paper aims to present a new method for obtaining an analytical solution for the Kaniadakis Doppler broadening (KDB) function. Also, in this work, we report the computational efficiencies of this solution compared with the numerical one. The solution of the differential equation achieved in this paper is free of approximations and is, consequently, a more robust methodology for obtaining an analytical representation of ψ_k. Moreover, the results show an improvement in efficiency using the analytical approximation, indicating that it may be helpful in different applications that require the calculation of the deformed Doppler broadening function.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.365-369
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• 2014

We present accurate analytical solutions of the lineshapes of birefringence (rotation) and dichroism (absorption) spectroscopy for a circular anisotropic medium composed of atoms of the transition $J_g=0{\rightarrow}J_e=1$. The susceptibility of a weak probe beam was analytically calculated and was averaged over a Maxwell-Boltzmann velocity distribution. The lineshapes of the two spectroscopies were then presented in analytical forms at arbitrary values of the linewidths of the inhomogeneous (Doppler) broadening and the homogeneous (natural) broadening of the atoms.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.367-373
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• 2011

It is described that the proton beam induces micro defects and electronic deep levels in Cz single crystal silicon. Enhance signal-to-noise ratio, Coincidence Doppler Broadening Positron Annihilation Spectroscopy has been applied to study of characteristics of p type and n type silicon samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The samples were exposed by 4.0 MeV proton beams ranging from 0 to ${\sim}10^{14}$ ptls. The S-parameter values were increased as increasing the irradiated proton beam, that indicated the defects generate more.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.47-54
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• 1999

The Doppler in neurosonologic examination could be applied to blood flow to determine its movement, the direction of its movement, and how fast it is. Indicies of the Doppler study denoted velocity, direction, and amount of RBC in the examined vessel. Systolic. diastolic, and mean blood flow velocities represent velocity of RBCs in a sample volume. Blood flow direction to the probe means direction of RBC to the probe. Size of amplitude displays toe amount of the RBCs passing the sample volume. Spectral broadening means presence of turbelence. The RBC movements and hemodynamics at the examined vessels can be estimated by analysis of Doppler indicies The formation and meaning of each of neurosonologic Doppler study is described in the present review.

• Korean Journal of Materials Research
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• v.15 no.6
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• pp.370-374
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• 2005

Doppler broadening spectrometer for positron annihilation experiment(DBPAS) has been used to characterize nano size defect structures in materials. DBPAS measures the concentration, spatial distribution, and size of open volume defects in the rare-earth intensifying screen materials. The screens were exposed by X-ray varying the exposed doses from 3, 6, 9, and 12 Gy with 6 W and 15 MV respectively and also irradiated by 37 MeV proton beams ranging from 0 to $10^{12}ptls$. The S parameter values increased as the exposed time and the energies increased, which indicated the defects were generated more. The S parameters of the samples with X-rays varied from 0.5098 to 0.5108, on the other hand, as proton beams varied from 0.4804 to 0.4821.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1895-1898
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• 2018

The mechanical properties of Al, Ti, Fe, and Cu metals p-type Si, and n-type Si were investigated by using coincidence Doppler broadening (CDB) positron annihilation spectroscopy. The samples in this experiment were irradiated by using X-rays at generating powers for up to 9 kW. The data taken after the irradiation showed all the characteristic features predicted from defects with vacancies. The S parameter values of the metals were generally less than those of semiconductors such as p-type Si and n-type Si. The relationship between n-type Si and p-type Si were more affected when n-type Si rather than p-type Si was irradiated with X-rays.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.642-649
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• 2016

Important safety parameters such as the fuel temperature coefficient (FTC) and the power coefficient of reactivity (PCR) of the CANada Deuterium Uranium (CANDU-6) reactor have been evaluated using the Monte Carlo method. For accurate analysis of the parameters, the Doppler broadening rejection correction scheme was implemented in the MCNPX code to account for the thermal motion of the heavy uranium-238 nucleus in the neutron-U scattering reactions. In this work, a standard fuel lattice has been modeled and the fuel is depleted using MCNPX. The FTC value is evaluated for several burnup points including the mid-burnup representing a near-equilibrium core. The Doppler effect has been evaluated using several cross-section libraries such as ENDF/B-VI.8, ENDF/B-VII.0, JEFF-3.1.1, and JENDL-4.0. The PCR value is also evaluated at mid-burnup conditions to characterize the safety features of an equilibrium CANDU-6 reactor. To improve the reliability of the Monte Carlo calculations, we considered a huge number of neutron histories in this work and the standard deviation of the k-infinity values is only 0.5-1 pcm.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.113-124
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• 2009

The line shape functions for the Doppler-broadened gamma ray spectrum are considered in the $^{10}B(n,{\alpha}{\gamma})^7Li$ reaction occurring in a surrounding medium where the excited $^7Li$ nucleus is slowed down and stopped before decay. The phenomenological form of the stopping power was used for the broadening effect. Convolution with the detailed response of a germanium detector is taken into consideration for the simplest case of solely electronic stopping. A numerical study for the analysis of $^{10}B$ by thermal neutron capture is conducted by performing a parametric search and fitting the measured spectrum in a least-squares approach. In comparison with the previous numerical approach using the same analysis, the computational speed is increased and reliable information concerning the stopping power of the medium is obtained while estimating the uncertainty. Implementation of the routine analysis of $^{10}B$ is facilitated on a recent version of the gamma ray spectrum analysis package HyperGam.