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Scintillation
About: Scintillation is a research topic. Over the lifetime, 14022 publications have been published within this topic receiving 187694 citations.
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TL;DR: In this paper, a power law spectrum with index α = 3 was assumed for the turbulence or refractive index spectrum, and the intensity spectra were found to duplicate the Born approximation for weak scattering and the high frequency approximation for strong scattering.
Abstract: Spectra of intensity fluctuations resulting from the propagation of a plane wave through a thin but arbitrarily strong layer of refractive index variations are computed using the theory in a companion paper [Rumsey, 1975]. A power law spectrum with index α = 3 was assumed for the turbulence or refractive index spectrum. The intensity spectra were found to duplicate the Born approximation for weak scattering and the high frequency approximation for strong scattering. The scintillation index, or the rms intensity fluctuation, saturates at unity for a plane wave. The scintillation index has been computed for sources of various sizes. The results of the computation are in remarkable agreement with the results of radio star scintillation measurements.
72 citations
TL;DR: The spectra and decay times of the 4.3- and 3.7-eV luminescence bands associated with the self-trapped excitons in CsI have been observed in a wide temperature range by using two-photon spectroscopy.
Abstract: The spectra and decay times of the 4.3- and 3.7-eV luminescence bands associated with the self-trapped excitons (STE's) in CsI have been observed in a wide temperature range (4.5--300 K) by using two-photon spectroscopy. The results reveal that the 4.1-eV luminescence in pure CsI, which is well known as the room-temperature scintillation, appears mainly from the 4.3-eV STE state: the 4.3-eV STE luminescence is dominant below 6 K and is quenched above 6 K, but appears again at 4.1 eV at room temperature by thermal activation of STE's from the 3.7-eV STE state to the 4.3-eV STE state.
72 citations
TL;DR: In this paper, the light yield of Y2O3 ceramics was evaluated in about 1.13 times higher than that of Bi4Ge3O12(BGO):Ce single crystals and was estimated in 9300 photon/MeV.
Abstract: Various fundamental characteristics of Y2O3 ceramics, such as optical transmittance, reflectivity, absorption coefficient, refractive index, and dielectric constant, were investigated. Furthermore, in order to evaluate the possible application of this material as γ-ray scintillator, other radiation responses, like the α-ray excited emission spectrum, the γ-ray excited pulse height spectrum, the light yield, the nonproportionality, the energy resolution, and the γ-ray excited scintillation decay curves were obtained. The light yield of Y2O3 ceramics was evaluated in about 1.13 times higher than that of Bi4Ge3O12(BGO):Ce single crystals and was estimated in 9300 photon/MeV. The nonproportionality measurements showed a good proportionality. The scintillation decay curve could be fitted by an exponential function characterized by a fast component of about 34 ns.
72 citations
TL;DR: In this article, the authors report measurements of up to 8 minutes in the centimeter wavelength variability patterns of the intra-hour scintillating quasar PKS 1257-326 as observed between the VLA and the ATCA on three separate epochs.
Abstract: We report measurements of time delays of up to 8 minutes in the centimeter wavelength variability patterns of the intra-hour scintillating quasar PKS 1257-326 as observed between the VLA and the ATCA on three separate epochs. These time delays confirm interstellar scintillation as the mechanism responsible for the rapid variability, at the same time effectively ruling out the coexistence of intrinsic intra-hour variability in this source. The time delays are combined with measurements of the annual variation in variability timescale exhibited by this source to determine the characteristic length scale and anisotropy of the quasar's intensity scintillation pattern, as well as attempting to fit for the bulk velocity of the scattering plasma responsible for the scintillation. We find evidence for anisotropic scattering and highly elongated scintillation patterns at both 4.9 and 8.5 GHz, with an axial ratio > 10:1, extended in a northwest direction on the sky. The characteristic scale of the scintillation pattern along its minor axis is well determined, but the high anisotropy leads to degenerate solutions for the scintillation velocity. The decorrelation of the pattern over the baseline gives an estimate of the major axis length scale of the scintillation pattern. We derive an upper limit on the distance to the scattering plasma of no more than 10 pc.
72 citations
TL;DR: In this paper, the statistical properties of the beacon signals together with their correlation with the concurrent radiometric signal suggest that both scintillation and a variable attenuation mechanism act to produce the field fluctuations.
Abstract: Selected events of enhanced field amplitude fluctuations recorded on the Orbital Test Satellite (OTS) path have been analyzed. The statistical properties of the beacon signals together with their correlation with the concurrent radiometric signal suggest that both scintillation and a variable attenuation mechanism act to produce the field fluctuations. Analysis of the coherence between the beacon and the radiometric signals gives an indication of the fluctuation frequency range over which each effect prevails. The comparison between scintillation data collected by a large (17 m) and a small (3 m) antenna indicates that the turbulence of the refractive index was particularly high during the course of the considered events. >
72 citations