A short history of gamma ray investigations is given. Particular reference is made to the use of beta-ray spectrometers in these investigations, and a detailed description is given of the thin-lens beta-ray spectrometer and its auxiliary apparatus. The energies of the gamma rays of radium and of its equilibrium disintegration products are determined by measuring the momentum of the photoelectrons ejected by these gamma rays from a lead radiator. These energies agree well with the values reported by Ellis and Mann, and also agree with most of the previously unconfirmed values reported by Latyshev. Evidence is given for the existence of a gamma ray (804 Kev.) previously unreported. The energy calculations are based on a calibration using the F line of thorium B (Hϱ = 1385.6 gauss-cm.) / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The thin-lens beta-ray spectrometer is described, together with its associated equipment. The energies of gamma-rays, emitted by Radium in equilibrium with its disintegration products have been determined by measuring, in such a spectrometer, the energies of photoelectrons ejected from lead. These energies agree reasonably well with those reported by Ellis and Skinner, although several values reported by Alichanov and Latyshev have not been found. The energy calculations were based on a calibration using the F line of Thorium B; (H ϱ = 1385.6 gauss-cm.). An indication was found of a gamma energy not previously reported. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Zugl.: München, Techn. Univ., Diss., 2006

Abstract This thesis discusses 226Ra distribution in the seawater of the East China Sea and the sea off northeastern Taiwan. Six profiles and fifteen surface water samples were measured. Water samples were collected during cruises 493 and 523 in July, 1997 and July, 1998, respectively. 226Ra measurements were performed by the regenerated 222Rn method that had been widely used for seawater samples. The surface water 226Ra activities vary between 8.7 and 15.9 dpm/100kg in the East China Sea. There is an increase in surface water 226Ra northward toward the estuary of the Changjiang. This variation is somewhat similar to that observed in the East China Sea by Nozaki et al. (1976). The surface water 226Ra activities vary between 9.1 and 10.8 dpm/100kg in the area off northeastern Taiwan. There values are higher than KEEP-MASS cruise of July, 1992. The Kuroshio Current not easy to enter shelf, so the dilution effect of Kuroshio is smaller. Otherwise, There are 226Ra in profiles were measured from six stations on Cruise 493 (13 and 15) in Kuroshio area and Cruise 523 (5, 7, 13 and 15) in shelf. The deep water profile on Cruise 493 (st.13) displays a phenomenon 226Ra increase from about 9.7 dpm/100kg at 5m to about 14.3 dpm/100kg at 500m, station 15 from Cruise 493 displays a phenomenon 226Ra increase from about 9.8 dpm/100kg at 5m to about 17.7 dpm/100kg at 800m. 226Ra profile at station 7 showed that the gradient from 600m to 750m is large, and 226Ra concentration does not increase below this depth. 226Ra maybe associated with nepheloid layer due to lateral or horizontal transport of the water mass. Each 226Ra profile shows a downward increase from less than 10 dpm/100kg at the surface, and shows the underlying sediments as the main source. Based on the radioactive disequilibrium observed between 210Pb and 226Ra, all the ratios of Pb-210/Ra-226 in Station 13 are greater than 1, except at 400m. The 210Pb concentration is high and the ratio of Pb-210/Ra-226 is greater than 1 at 800m.

Thesis (M.S.)--University of Wisconsin--Madison, 1937. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Radium contamination in the lakes near uranium mines and its intake by fish and other aquatic species are of great concern in environmental radiation protection. As an alternative technique to Liquid Scintillation Counting, we present a gamma-ray spectrometric method for low level 226Ra analysis, particularly in live fish. The HyperPure Ge and a 4π NaI(Tl) array were employed as gamma-ray spectrometers. The 226Ra spectra for each spectrometer were collected in order to compare their analytical performance. From the HPGe 226Ra spectra, a detection limit of 6.81 Bq with 99% confidence was determined for an hour counting with the three strongest peaks combined. For the 4π NaI(Tl) 226Ra spectra, in order to optimize the spectral analysis, a method applied to nine different energy regions was attempted and it turned out that the detection limit is best when the total integral count subtracted by the corresponding background is used. The detection limit of the 4π NaI(Tl) was 0.99 Bq with 99% confidence for one hour counting. A benchmark simulation for point source position dependence on relative peak efficiency showed a good agreement with the experimental data. To extend 226Ra analysis to volumetric aqueous samples, MCNP Monte Carlo simulations showed that for three cylindrical volume sources, as the simulated volume source size increased from 60 ml to 125 ml to 250 ml, the full-energy peak efficiency in the energy range of interest for 226Ra decreased by approximately 3% for each size increase, due to attenuation in the source volume. A method has been proposed in order to demonstrate this technique for a live fish, whereby a fish injected with 226Ra would be kept in its own special aquarium and its gamma-ray spectrum collected. / Thesis / Master of Science (MSc)

No description available.

The South China Sea (SCS) is a large semi-enclosed marginal sea to the west of the tropical Pacific, and connected to the western Pacific through the Luzon Strait. The surface water circulation and hydrography in the SCS are strongly influenced by the East Asian monsoon system. The seasonal changes of the monsoon system induce changes in the mixed layer thickness, upwelling, primary production, and associated biogeochemistry. In order to understand the characteristics of the Kuroshio intrusion and the source strength of radium isotopes from the coastal zone, we carried out surface water and water column samplings for Ra-228 and Ra-226 measurements in the northern SCS and the Luzon Strait areas. The Ra isotopes were much higher in the SCS surface waters than in the open ocean surface waters because the SCS was enclosed mostly by landmasses which are known as sources of these nuclides. Higher surface water activities are seen in the northern (shelf and slope) area; lower values are observed in the southern (deep basin) area; the lowest values appear in the eastern (Luzon Strait) area. Large temporal and spatial variations were also observed probably due to the source strength of radium isotopes from the coastal zone and intrusion of the Kuroshio Current. The vertical 228Ra profiles are remarkably similar, showing high values in the surface layer and fairly uniform below about 500m depth but with an increase toward the bottom due to input from the underlying sediments. The shallow water profile on the shelf shows higher 228Ra values due to both vertical and horizontal mixing of the shelf water and additional source from the shore zone. The 226Ra profiles in the northern SCS are quite similar to those in the northwest Pacific both in pattern and magnitude, showing lowest values at the surface and an increase with depth although more scattered. 226Ra activities in the shallow water (less than 1000m depth) are higher in the northern SCS than in the northernwest Pacific Ocean, but they are quite comparable below this depth. The Ra-228/Ra-226 activity ratios of the surface water decrease from the coastal zone and estuaries toward the basin and the Luzon Strait (from 4.11 to 1.03), indicating the former as a main source area for Ra-228. The vertical 228Ra/226Ra activity ratios decrease rapidly from the surface at 2.3 to a depth of 1500m at 0.5 below which the values are less than 0.5. This pattern is similar to that of the open ocean but these values are much higher than those in the open oceans where the surface water values are 0.5 or less and the deep water values are less than 0.1. This suggests a strong input of Ra-228 relative to Ra-226 from the bottom sediments into the deep water of the semi-enclosed SCS.

Naturally occurring radioactive material (NORM) exists in connate waters and, under the right conditions during oil drilling, can plate out on the interior surfaces of oil and gas industry equipment. Once deposited, this material is commonly referred to as ??scale.?? This thesis is concerned with the presence of 226Ra in scale deposited on the inner surfaces of oil drilling pipes and the internal dose consequences of inhalation of that scale once released. In the process of normal operation, barium sulfate scale with a radium component adheres to the inside of downhole tubulars in oil fields. When crude flow is diminished below acceptable operational requirements, the pipe is sent to a descaling operation to be cleaned, most likely by a method known as rattling. The rattling process generates dust. This research investigated the chemical composition of that aerosol and measured the solubility of pipe scale from three oilfield formations. Using standard in-vitro dissolution experimental equipment and methods, pipe scale is introduced into simulated lung fluid over a two-week period. These samples are analyzed using quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS), known for very low detection limits. Analysis reveals virtually no 226Ra present in the lung fluid exposed to pipe scale. Sample measurements were compared against background measurements using Student??s t test, which revealed that nearly all the samples were statistically insignificant in comparison to the lung fluid blanks. This statistical test proves within a 95% confidence interval that there is no 226Ra present in the lung fluid samples. These results indicate that inhaled NORM pipe scale should be classified as Class S and serve to further confirm the extreme insolubility of petroleum pipe scale. For dose calculations, the S classification means that the lung is the main organ of concern. Radium-226 from petroleum pipe scale does not solubilize in the interstitial lung fluid, and does not, therefore, enter the bloodstream via respiratory pathways. Since there is no removal by dissolution, the 500 day biological half-life implied by the S classification is based solely on the mechanical transport of 226Ra out of the lungs by phagocytosis or the mucociliary escalator.

Thesis (Ph.D.)--University of Chicago, Department of Chemistry, 1917. / "Private edition, distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Journal of the American Chemical Society, vol. XLIII. no. 3. March, 1921." Includes bibliographical references. Also available on the Internet.