Scintillation Method Research Articles

姶良Ｔｎ火山灰（ＡＴ）の｀１４´Ｃ年代

The ages of peaty mud samples including the Aira-Tn ashes (AT) that were identified from refractive indices and chemical compositions were determined precisely with radiocarbon dating using the benzene-liquid scintillation method. The eruption age of AT was found to be 24, 720±290y.B.P.

Attempt to determine the environmental 36Cl concentration in water by liquid scintillation counting

A low-background liquid scintillation spectrometer (ALOKA SL-1) located in the IAEA Isotope Hydrology Laboratory in Vienna was used for 36Cl activity measurement in water samples. The procedure of sample preparation consists of synthesizing of silicon tetrachloride or sodium chloride followed by purification. In both cases the limiting factor in the analysis appeared to be the pure reproducibility of the sample preparation procedure. The conclusion from these experiments is that the liquid scintillation method could be feasible only for the identification of the “bomb chlorine” but is far from being suitable for the accurate determination of 36Cl in groundwater for dating purposes.

Tritium Production Measurements by the Lithium-Glass Scintillator Method

As a part of the Phase I of JAERI/USDOE collaborative program on fusion blanket neutronics, the effect of constituents of the fusion blanket on tritium production rate distribution was examined experimentally by the Lithium-glass scintillator method. The self-shielding factor of the Lithium-glass scintillator was estimated by an experiment as well as a calculational method. The Li-glass method has shown excellent performance and reliability in the parametric measurement of the tritium production rate distribution.

Diffusion of Tritiated Water and Chloride in Basalt-Bentonite Mixtures

Effective diffusion coefficients of tritiated water and chloride (36Cl) were measured in mixtures of crushed basalt and bentonite as functions of temperature (20 to 90°C) and mixture bulk density (1.5 to 1.9 Mg/m3). A quick-freeze technique was used to halt the diffusion process so the tracer distributions could be determined by slicing the core and analyzing slices by liquid scintillation methods. Linear and multiplelinear regression analyses were performed on both data sets. The regression equations were then used to predict diffusion coefficient values outside the range of densities used in these experiments. The predicted values agree very well with published data. Correlation of diffusion coefficients with temperature was highly significant for both elements. Dependence of chloride diffusion on clay density was much larger than for tritium.

Kinetics of reparative DNA replication induced in CBA and C57BL/6 mouse spleen cells by urethane and influenza virus

The authors investigated the reparative replication of DNA, induced by urethane and influenza virus in C57BL/6 and CBA mice which have marked differences in tumor formation. Reparative DNA replication, induced by urethane and influenza virus was investigated by a liquid scintillation method based on measuring incorporation of /sup 3/H-thymidine into the total mass of mouse spleen cells, when replicative DNA synthesis was inhibited by hydroxyurea. The intensity of reparative DNA replication was judged from the value of the stimulation index which is the ratio of the radioactivity in the spleen cells of the experimental animals to the corresponding parameters in cells of intact animals. The phenomenon of the stimulating and inhibitory effects of influenza virus on reparative DNA replication in cells depending on their genotype and sensitivity to virus is established.

(n,2n) cross sections of2H and239Pu

Abstract The large liquid scintillator method has been used to measure the 239Pu(n,2n) cross section between threshold and 13 MeV, and the 2H(n,2n) cross section between 7.5 and 15 MeV. The 239Pu excitation function has been calculated using a statistical preequilibrium model.

Assay of polyamines by thin-layer chromatography and a combination of double-isotope dilution and scintillation methods

Assay of polyamines by thin-layer chromatography and a combination of double-isotope dilution and scintillation methods

Observations of low-luminosity radio galaxies at 102 MHz

This paper presents results given of the observations of 38 low-luminosity radio galaxies at 102 MHz by the method of interplanetary scintillation. The authors give a detailed analysis of the observational data for the objects. Low-luminosity radio galaxies with upper limits of the flux densities at 102 MHz are shown.

The scintillator-filled etch-pit method for neutron dosimetry: Part I — Thermal neutrons, with (n,α) converters

The scintillation method of Harvey and Weeks (1982) has been extended to the counting of etched tracks in CR-39 made by thermal and fast neutrons. In Part I, we report our work on thermal neutron detection. Here, CR-39 detectors, palced in contact with both Li 2 B 4 O 7 and BNl converter screens, have been exposed to neutrons from portable sources, with suitable moderation. The chemically etched (n,α) pits are filled with scintillator material, and the light pulses caused by a strong readout α-source are detected by a photomultiplier. The linearity of response with this method has been tested for tracks made by α-particles of different energies (1 - 5.5 MeV). The response remains linear so long as serious overlapping of etch pits does not occur. The method promises to offer a quick and automatic technique for neutron dosimetry.

The scintillator-filled etch-pit method for neutron dosimetry: Part II — Fast neutrons, using intrinsic tracks

The scintillation method of Harvey and Weeks (1982) has been extended, in Part II, to the counting of “intrinsic tracks” made in the CR-39 detector by fast neutrons from either portable sources or accelerators, without moderation. The pits of the chemically etched intrinsic tracks are filled with a scintillator material and counted as in Part I. An optical photodensitometer has also been used to measure the scintillator-filled etch pits. The effect on the detector response of varying the incident neutron energy has been studied, as have various combinations of pre- and post-ECE chemical etching in order to optimize the response. A linear response of count rate vs neutron fluence has been obtained on the log-log scale up to a certain fluence value, which is eventually limited by the overlapping of the etch-pit openings.

Measurements of atmospheric turbulence strength by coherent optical scintillation

The strength of the atmospheric turbulence is measured by an optical scintillation method. The obtained quantity is the structure constant at optical frequencies. As all turbulence parameters, this quantity is strongly affected by meteorological and local conditions, therefore it is of interest to measure it in different conditions and locations. The present measurements were made to characterize the turbulence at Florence.

Remote sensing of rainfall parameters by laser scintillation correlation method — Numerical simulation of the retrieving

This paper is a continuation of an earlier paper[1]. In this paper, we investigate the stability and the representativeness of the rainfall rateh determined by theB 2*-h relationship in the scintillation method of remote sensing of rain parameters, develop an adequate scheme for retrieving rainfall rate and raindrop size distribution (DSD), and finally characterize the technique by numerical simulations. The results show that theB 2*-h relationship is quite stable for all the raindrop size distributions used in present simulations; the measured rainfall rate is not severely affected by the distribution of the path-weighting function ofB 2*. The retrieving of DSDs is successful even if the observation errors are assumed in simulations. The rainfall rates derived from the ratrieving of DSD is more accurate than these determined byB 2*-h relationship. This method is superior in heavier rains.

Effect of the degree of evaporation of an ensemble of particles with different sizes on the parameters of the calibration curve in the scintillation method of spectral analysis

Effect of the degree of evaporation of an ensemble of particles with different sizes on the parameters of the calibration curve in the scintillation method of spectral analysis

On the fiftieth anniversary of major discoveries at the Cavendish Laboratory

This paper begins with some recollections of the Cavendish Laboratory of the University of Cambridge in the years 1928–30, which just preceded the discovery of the neutron and other major discoveries there in 1932–33. It then goes on to describe new developments in experimental techniques for accelerating, detecting, and counting charged particles such as protons and α particles in the Cavendish Laboratory which made possible the major discoveries by Chadwick, Blackett, and Cockcroft and Walton in 1932–33. The scintillation method was superseded by the linear amplifier and scale-of-two counter. Other experimental techniques described here include the original proportional counter, the cloud chamber triggered by coincident pulses in two Geiger–Müller counters for the detection of cosmic rays, and a 700-kV voltage multiplier for the first transmutations by artificially accelerated hydrogen ions. Pioneer measurements on pair production of γ rays and annihilation radiation are discussed in terms of Dirac’s relativistic theory of the electron.

Radioisotope investigations on the stratigraphic distribution of poly/methyl methacrylate/grafted onto leather

Investigations on the stratigraphic distribution of poly/methyl methacrylate/ in leather follow our earlier experiments on radiation grafting of vinyl monomers in situ . Polymer distribution was determined for pigskins and cattlehides tanned with basic sulphates of chromium /III/. 14C-labelled methyl methacrylate was used in present experiments. Precision slicing technique was employed to cut consecutive slices parallel to the grain surface of the radiation modified leather. Quantitative analysis of polymer distribution in leather was based on radioactivity measurements. Each layer was burned in Oxymat apparatus and resulting 14CO 2 was analysed by liquid scintillation method. On the basis of radioactivity measurements and visual observations with light microscope conclusion on desirable distribution of polymer was reached. In the midcorium part of leather polymer is evenly distributed and its content is much higher than for outer layers next to surface and flesh. Mechanism of relevant processes as well as formation and role played by peroxide compounds is discussed.

Absorption and excretion of tablet disintegrating β-cyclodextrin polymer in rats

Absorption and excretion of a new tablet disintegrating agent, a crosslinked β-cyclodextrin polymer was investigated following per os administration in the rat. The polymer, which is insoluble but swells in water, was prepared from β-cyclodextrin by reacting with [2- 14C]epichlorohydrin in an alkaline medium. Radioactivity of blood, urine, faeces, exhaled carbon dioxide and the gastrointestinal tract was determined by a liquid scintillation method. No radioactivity could be detected in the blood up to 24 h after the administration of the polymer. Radioactivity of urine and exhaled carbon dioxide together did not exceed 0·11% of the total administered radioactivity, 98% of which was found in the large intestine and the faeces. Therefore, it is assumed that β-cyclodextrin polymer could not be absorbed from the gastrointestinal tract.

Fano factor in gaseous argon measured by the proportional scintillation method

It is found that the apparent Fano factor in argon obtained by using 5.90 keV X-rays with the proportional scintillation method depends on the gas pressure and that the true Fano factor can be obtained by extrapolating the linear relation between the apparent Fano factor and the reciprocal of the gas pressure. The Fano factor thus obtained gives good agreement, within experimental errors, with the value recently obtained by using a gridded ionization chamber.

Sub Arc Second Components in Nearby Bright Galaxies at Metre-Wavelengths

150 nearby bright galaxies have been observed for compact components at 327 MHz by the method of Interplanetary Scintillation (IPS) using the Ooty radio telescope; scintillation was detected in 28 of these galaxies indicating compact components with size < 30 mas to 300 mas having flux density > 100 mJy. Comparison of our data with other results at high frequencies indicates that these compact components are associated with the central regions of the galaxies.

Geological Survey of Japan Radiocarbon Dates I

This radiocarbon laboratory began operation in 1980 using the benzene scintillation method. The benzene synthesizer is essentially identical with that of Ikeda (1976). A liquid scintillation counter is Aloca LSC-LB1. Samples dated are wood, charcoal, shell, and coral.Pretreatment of wood and charcoal is a standard acid-alkali procedure, using 2% HCl and 2% NaOH at elevated temperatures. Charcoal is further heated in concentrated HNO3 for one hour, diluted in water, stands one night, and is washed and dried. Pretreated wood and charcoal are carbonized before combustion. The combustion products are passed over CuO, and are collected in an ammonium hydroxide bubbler system, and precipitated with calcium chloride.

The determination of technetium-99 in urine

A method has been developed for the routine radiochemical analysis of technetium-99 in human urine. The excreted technetium is coprecipitated from a 200 mL urine sample with CuS. Valence state adjustments are performed with K2S2O8. The precipitate is dissolved in ammoniacal peroxide and, after the Cu(II) is removed by ion exchange, the Tc-99 is extracted with 2-butanone (MEK). Subsequent evaporation of the organic solvent gives an essentially weightless source that if counted with a gas proportional counter will give a better limit of detection than liquid scintillation methods. The recovery of Tc-99 using this procedure is 80% (σ = 4%) and the limit of detection is 20 mBq (0.6 pCi) at the 95% confidence level for a routine sample – counting time 20 minutes, counting efficiency 24%, ambient background 1.3 counts per minute (cpm).