Showing papers on "Scintillation published in 1974"
TL;DR: In this paper, a simple, physically based elaboration of the first-order perturbation theory of optical scintillations is presented and compared with observations, and it reproduces in detail the observed saturation curve and the observed spatial covariance.
Abstract: The diffraction theory of optical scintillations has so far failed to describe the propagation of light over paths where the integrated amount of refractive-index turbulence is sufficient to cause saturation of the scintillations. We present a simple, physically based elaboration of the first-order perturbation theory and compare it with observations. Our theory reproduces in detail the observed saturation curve and the observed spatial covariance of the scintillations. In particular, we show why the fine-scale structure of scintillations persists deep into the saturation regime.
208 citations
Book•
01 Jan 1974
TL;DR: In this paper, a book to wait for in this month is given, and even if you have wanted for long time for releasing this book applications of liquid scintillation counting; you may not be able to get in some stress.
Abstract: That's it, a book to wait for in this month. Even you have wanted for long time for releasing this book applications of liquid scintillation counting; you may not be able to get in some stress. Should you go around and seek fro the book until you really get it? Are you sure? Are you that free? This condition will force you to always end up to get a book. But now, we are coming to give you excellent solution.
200 citations
TL;DR: In this paper, correlation measurements of the scintillation of single and double stars are described and interpreted in terms of discrete turbulent layers, and an approximate altitude is determined and the index and temperature structure constants integrated over the layer thickness are estimated.
Abstract: Correlation measurements of the scintillation of single and double stars are described and interpreted in terms of discrete turbulent layers. For each observed layer, an approximate altitude is determined and the index and temperature structure constants integrated over the layer thickness are estimated. Results are in good agreement with in situ measurements performed elsewhere.
135 citations
TL;DR: In this article, several ionospheric irregularity models with different power spectra are compared with the observed results and both magnitude and frequency dependence of the scintillation index are investigated.
74 citations
TL;DR: Horrocks as mentioned in this paper applied liquid scintillation counting to the application of counting. But this work focused on counting the number of points in a set of points instead of counting the entire set.
Abstract: Applications of Liquid Scintillation Counting. By D. L. Horrocks. Pp. xiii+346. (Academic Press: New York and London, June 1974.) $29.50; £14.15.
73 citations
TL;DR: The diffraction theory of interplanetary scintillations, which allows a connection to be established between the spatial spectrum of electron-density fluctuations in the irregular medium and the power spectrum of intensity scintillation observed on the ground, is reviewed and applied to the case of the ionosphere.
60 citations
TL;DR: In this paper, the authors show that the observed scintillation scale (∼1 km) is much smaller than the outer-scale dimension of the irregularities, since Fresnel filtering attenuates irregularity structure larger than (πλz)1/2, about 1 km.
Abstract: Recent in situ measurements and scintillation spectra suggest a power law irregularity spectrum in the F region ionosphere with a large outer-scale dimension (∼100 km). This result is consistent with the ‘near-field’ scintillation approximation, since Fresnel filtering attenuates irregularity structure larger than (πλz)1/2, about 1 km. Consequently, the observed scintillation scale (∼1 km) is much smaller than the outer-scale dimension of the irregularities. Theoretical calculations show that Gaussian irregularities cannot explain these differences in scale. The wavelength dependence based on small scintillation levels has most often been reported as approximately λ¹ and λ² for interplanetary and ionospheric scintillation, respectively. Differences between these measurements and the theoretical dependence are discussed.
51 citations
TL;DR: A gamma-ray spectrometer has been flown on the Apollo 15 and 16 spacecraft to determine the lunar-surface composition and measure the cosmic gamma-rays flux as discussed by the authors, and the data were transmitted on an event-by-event basis.
49 citations
01 Mar 1974
41 citations
TL;DR: In this article, the association between corotating sectors of enhanced scintillation and compression regions located at the interface between fast and slow solar wind streams was found to be strongly correlated.
TL;DR: The literature dealing with communication theory and ionospheric physics contains numerous analyses of the effect of fading on communications signals, so the literature of each field can be applied to the other.
Abstract: The literature dealing with communication theory contains numerous analyses of the effect of fading on communications signals, while the literature dealing with ionospheric physics contains numerous models and measurements of ionosphericinduced scintillation. This correspondence relates the two; thus, the literature of each field can be applied to the other.
TL;DR: In this article, the scintillation pulse height and PSD properties of anthracene have been investigated as a function of proton direction using recoil protons released within the crystals by monoenergetic incident neutrons.
TL;DR: A two-compartment vial is described in which suspensions of bacteria, cells, or tissues may be cultured and their growth and metabolism measured radiometrically by using a liquid scintillation counter.
Abstract: A two-compartment vial is described in which suspensions of bacteria, cells, or tissues may be cultured and their growth and metabolism measured radiometrically by using a liquid scintillation counter. The device consists of a scintillation vial lined with a cylinder of scintillating paper into which is placed a sterilized inner culture vial containing a carbon-14 substrate. The assembled device can be carried by the sample transport systems of conventional liquid scintillation counters. Evolved 14CO2 is collected and measured cumulatively and continuously. The device can be constructed simply and economically from readily available reagents and glassware. Data are given on relative sensitivity and on the effect of the color and transparency of the inner vial. A pilot experiment with bacteria (Escherichia coli) is described.
Patent•
15 Oct 1974TL;DR: An improved projection screen which substantially reduces scintillation includes a first transparent element having an initial light refracting surface of closely spaced micro-optical elements that redirect a substantial portion of the light rays simultaneously entering a retina-resolvable area of the screen along different non-parallel paths of travel within the screen as discussed by the authors.
Abstract: An improved projection screen which substantially reduces scintillation includes a first transparent element having an initial light refracting surface of closely spaced micro-optical elements that redirect a substantial portion of the light rays simultaneously entering a retina-resolvable area of the screen along different non-parallel paths of travel within the screen. Transparent spacing means are located adjacent the screen element containing the initial refracting surface and provide for intra-screen amplification of the initially created differences in the paths of ray travel to an extent that the intra-screen paths of travel of such rays differ by more than the coherence length of the image projecting light source.
TL;DR: In this article, the optical scintillation theory has been adapted to the ionospheric geometry in order to study the ionosphere scintillant phenomenon in the presence of multiple scattering under a frequency above about 20 MHz.
Abstract: Recent development in the optical scintillation theory has been adapted to the ionospheric geometry in order to study the ionospheric scintillation phenomenon in the presence of multiple scattering Under approximations well satisfied in typical ionospheres for a frequency above about 20 MHz, the first through fourth moment equations have been derived and some analytic solutions given The fourth moment equation has also been solved numerically The numerical results show clearly the occurrence of focusing and saturation phenomena The new multiple-scatter effects are emphasized
TL;DR: In this paper, a transparent parallel plate gas scintillation proportional counter has been designed which provides improved resolution, more efficient use of counter volume, and better counting geometry than center wire or spherical anode counters.
TL;DR: In this article, the number of scintillation photons at any given energy and the efficiency of the photodiode were determined by using a known electron/photon efficiency for a given scintillator.
TL;DR: In this article, the morphology of artificial spread-F irregularities was studied by measuring the scintillation of VHF and UHF signals transmitted through the disturbed region from geostationary and orbital satellites.
Abstract: Experiments are described to study the morphology of artificial spread-F (ASF) irregularities by measuring the scintillation of VHF and UHF signals transmitted through the disturbed region from geostationary and orbital satellites. The ASF irregularities are found to be approximately field aligned with correlation distances of about 100 m transverse to the field direction; a smaller structure less than 10 m is also seen. The fluctuations seem to be distributed through the entire F layer, and are less than one percent of the ambient electron density at most times.
TL;DR: In this paper, measurements of the angular sizes of radio source components in the range 0.1″-1.0″, using the technique of interplanetary scintillation, reveal an absence of small-diameter sources at the largest redshifts.
Abstract: Measurements of the angular sizes of radio source components in the range 0.1″–1.0″, using the technique of interplanetary scintillation, reveal an absence of small–diameter sources at the largest redshifts. The cosmological implications of this result are discussed.
Patent•
27 Nov 1974TL;DR: In this paper, a scintillation camera is provided with electrical components which expand the intrinsic maximum rate of acceptance for processing of pulses emanating from detected radioactive events, and buffer storage is provided to accommodate temporary increases in the level of radioactivity.
Abstract: A scintillation camera is provided with electrical components which expand the intrinsic maximum rate of acceptance for processing of pulses emanating from detected radioactive events. Buffer storage is provided to accommodate temporary increases in the level of radioactivity. An early provisional determination of acceptability of pulses allows many unacceptable pulses to be discarded at an early stage.
03 Jan 1974
TL;DR: In this paper, the characterization of ionospheric scintillations in terms of scintillation index is discussed, and the relationship of SCI to system design parameters, cumulative amplitude distributions, and fade levels are shown.
Abstract: : The characterization of ionospheric scintillations in terms of scintillation index is discussed. Scintillation index cannot be directly applied to the design of systems that use transionospheric propagation. The relationships of scintillation index to system design parameters, cumulative amplitude distributions, and fade levels, are shown. The determination of a spectral index is explained and its use for extrapolating the results of ionospheric scintillation measurements to a desired frequency is shown.
TL;DR: Nonylphenoxypolythoxyethoxyethanol-NT-シンチレーター (NT-SHINチレームター) as mentioned in this paper
Abstract: Nonylphenoxypolyethoxyethanol-トルエンシチレーター (NT-シンチレーター) は, 3Hあるいは14Cを測定するのにすぐれた特性を有することが判明した。水溶性の試料に対するNT-シンチレーターの測定の性質を詳細に検討した。1NNaOHで試料を溶解させ, NT-シンチレーターと混合し, さらに2NHClを加え再び混合後しんとうすることによって種々の試料が多量に保持できた。このエマルジョンは長期間安定であり, しかも一定の計数効率で計測することができた。また, 今回の方法は, 3Hと14Cの二重標識化合物の放射能の分別測定の補正計算において, あまりわずらわされず適応できることが明らかになった。
Patent•
16 Aug 1974
TL;DR: In this article, means for obtaining such a response with crystal pieces, such means comprising the combination of crystal pieces and liquid or solid organic scintillator matrices having a cyclic molecular structure favorable to fluorescence, are provided.
Abstract: A scintillation counter consists of a scintillation detector, usually a crystal scintillator optically coupled to a photomultiplier tube which converts photons to electrical pulses. The photomultiplier pulses are measured to provide information on impinging radiation. In inorganic crystal scintillation detectors to achieve maximum density, optical transparency and uniform activation, it has been necessary heretofore to prepare the scintillator as a single crystal. Crystal pieces fail to give a single composite response. Means are provided herein for obtaining such a response with crystal pieces, such means comprising the combination of crystal pieces and liquid or solid organic scintillator matrices having a cyclic molecular structure favorable to fluorescence.
TL;DR: In this paper, a Monte Carlo program for the evaluation of the response functions and detection efficiencies of organic scintillators for neutrons up to 15 MeV is described.
Patent•
06 Sep 1974TL;DR: In this paper, a planar scintillating crystal is used to produce light events whose spatial distribution corresponds to the spatial distribution of the radiation stimuli causing such events, and computing circuitry coupled to the photomultipliers computes the projection of a light event in the crystal on a reference axis.
Abstract: A scintillation camera has a planar scintillating crystal that produces light events whose spatial distribution corresponds to the spatial distribution of the radiation stimuli causing such events, and a plurality of photomultipliers having photocathodes for receiving light from the crystal through a planar face thereof. Computing circuitry coupled to the photomultipliers computes the projection of a light event in the crystal on a reference axis by forming an analytical function of the outputs of the photomultipliers according to the spatial location of the light event in the crystal.
Patent•
02 Oct 1974TL;DR: A scintillation camera system for use in positron imaging in which radiation scattered in an object under study is screened and Compton events, as well as primary radiation, are imaged as discussed by the authors.
Abstract: A scintillation camera system for use in positron imaging in which radiation scattered in an object under study is screened and Compton events, as well as primary radiation, are imaged.
01 Dec 1974
TL;DR: In this paper, various geometrical configurations for gas scintillation proportional counters have been investigated in order to determine which configuration is best for use in a large volume, high efficiency counter for measuring low energy gamma and x-rays.
Abstract: Various geometrical configurations for gas scintillation proportional counters have been investigated in order to determine which is best for use in a large volume, high efficiency counter for measuring low energy gamma and x-rays. A xenon filled counter having a rod anode inside a cylindrical cathode appears to provide the best configuration for providing a uniform field and the best resolution over the total volume of the counter. The details of construction and operating characteristics of various shaped counters are described.
TL;DR: In this paper, calculations have been carried out to determine the response of a large all-liquid scintillation spectrometer to incident protons and charged pions in the low-GeV energy range.