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Dissertations / Theses on the topic 'Caesium'

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Published: 4 June 2021

Last updated: 31 January 2023

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1

Slaughter, Daniel Stephen, and d. slaughter@aip org au. "Superelastic Electron Scattering from Caesium." Flinders University. Chemistry Physics and Earth Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20071009.100421.

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This thesis describes an experimental study of superelastic electron scattering from the 6^2P_3/2 state of caesium. The present status of electron-atom collision studies is initially reviewed and the motivation behind the current work is then presented. A description of the theoretical framework is subsequently provided in the context of the present experimental study, followed by an overview of the several theoretical approaches for describing electron-atom interactions which are currently available. The apparatus and experimental setup used throughout the project are also described in detail. Technical specifications and data are provided, including diagrams (where appropriate) for a laser frequency locking system, electron gun and spectrometer, atomic beam source and data acquisition system. The experimental procedures are explained and discussed, including a detailed analysis of the optical pumping process required to excite the atomic target. A substantial component of this project was to address several potential sources of systematic error and to reduce these wherever possible. All of the errors and uncertainties relevant to the experiment are discussed in chapter 5. In chapter 6 the results of the present superelastic electron scattering experiments are reported for incident electron energies of 5.5eV, 8.5eV and 13.5eV, corresponding to superelastic electron energies of 7eV, 10eV and 15eV. These results are presented as three reduced Stokes parameters, P1, P2, P3 and a coherence parameter, P+ . For comparison, predictions from a number of currently available theories are presented alongside the experimental results. Finally, conclusions are drawn on this work in the context of the current status of electron-atom scattering from alkali-metals.

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2

Butcher, Louise Sara. "Laser spectroscopy of caesium dimers." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:dfd00a20-7f46-4828-8123-4f720980fb07.

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We have obtained spectra of 10 vibrational bands of the Cs₂ (2)³∏_u ← ϰ³∑⁺₉ system. The molecules were formed in a supersonic free jet expansion, and were excited by light from a single mode CW dye laser. The total laser induced fluorescence was measured at 90° to the incident light and molecular beam, using a photomultiplier. Using a slit system to image a selected part of the interaction region, we have reduced the Doppler width to about 350MHz. We have been able to resolve the discrepancy between the different vibrational band positions given in two previous papers. Our vibrational bands show broad rotational contours, but we have not been able to resolve individual rotational lines. We have also obtained rotationally resolved spectra of the bandhead region of 22 vibrational bands of the Β¹∏₉ ← X¹∑⁺_u system. We found that the frequencies of the bandheads agreed with the bandhead positions deduced from the Dunham coefficients of a previous work. We have developed a theoretical model of the rotational structure and intensity distribution, taking into account optical pumping and the small solid angle subtended by the detector. By fitting this model to the experimental spectrum of the v' = 3,u∿ = 0 band using least squares optimization, we were able to extract rotational constants and line positions. We found that these line positions were in good agreement with those from the previous work. We have discussed how such spectroscopic data may be used in a determination of the s-wave scattering length of caesium, and we have reviewed the validity of the scattering length and other pararneterisations of low energy Cs-Cs interactions.

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3

Kennedy, P. A. "Chemistry of sodium-caesium solutions." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355439.

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4

Martin, Jocelyn L. "Magnetic trapping and cooling in caesium." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361996.

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5

Webb, Claire. "Experiments with a caesium atom interferometer." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301650.

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6

Perkins, Joy. "Caesium toxicity accumulation in terrestrial microorganisms." Thesis, University of Dundee, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284497.

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7

Phoonthong, P. "State-insensitive traps for caesium atoms." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1344076/.

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State-insensitive traps are an important tool for precision spectroscopy. In these traps both the ground and excited state of the relevant atomic transition are shifted by the same amount. To obtain state-insensitive trapping, a specific trapping wavelength - called the "magic wavelength" - must be used. This thesis describes state-insensitive trapping of caesium atoms, as realised by using a trapping laser beam at the magic wavelength of 935.6 nm. Two different experimental setups were realised and characterised. The first set of experiments provided the characterisation of a singlewell state-insensitive trap, produced by using the laser beam from a Tisapphire laser. The trap lifetime was determined as a function of the trap depth, with the largest lifetime of 203 ms measured for a trap depth of 2.4 mK. Further improvement in the trap lifetime was obtained by applying a depumper laser beam, which prepared the atoms in the lower ground state. This suppresses hyperfine changing collisions, and the lifetime was increased to 3.6 s as a result. Ultimately, the lifetime was limited by the pointing instability of the dipole trap beam and the background gas collisions. A second experimental setup was then realised, to reduce the background gas collisions, which is the limitation of lifetime in the first setup. Furthermore, the imaging system was upgraded to reduce the background noise, and a MOPA system was used to produce the state-insensitive trap. In a second set of experiments, a single-well trap and a 1D optical lattice were compared to evaluate the suppression of two-body collisions in the 1D lattice case.

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8

Turner, Graham M. "Solution and surface reactions of liquid caesium." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329884.

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9

Jacobi, David Louis. "Sorption studies of caesium by complex hexacyanoferrates." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46841.

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10

Godun, Rachel M. "Beam splitting mechanisms for a caesium atom interferometer." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343474.

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11

Payne, Katharine. "Natural genetic variation in caesium accumulation by plants." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415498.

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12

Hobbs, Jeffrey W. "The chemistry of caesium tellurite, CSâ†2TeOâ†3." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359928.

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13

Broadley, Martin Roger. "A comparison of caesium uptake by higher plants." Thesis, University of the West of England, Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264624.

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14

Freytag, Ruben. "Simultaneous magneto-optical trapping of ytterbium and caesium." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/26874.

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This thesis presents progress toward the production of ultracold CsYb molecules. To this end, an apparatus capable of producing magneto optical traps of Yb and Cs was designed, built and tested. Both atoms are produced in a dual species oven and both slowed to low speeds by a single Zeeman slower. From the Zeeman slower atoms are captured in a dual-species magneto-optical trap. To cool caesium the 852 nm D₂ transition is addressed by two lasers for cooling and repump. For ytterbium the 399 nm ¹S₀ → ¹P₁ transition is addressed for the Zeeman slower and the 556 nm ¹S₀ → ³P₁ transition is addressed for the magneto-optical trap. The 399 nm light is produced by two homebuilt diode lasers in an injection-seeding setup, which can produce up to 100 mW. The 556 nm light is produced from a commercial frequency doubled fiber laser, which can produce up to 260 mW. The Zeeman slower is characterised experimentally for both Cs and Yb, and the results compared to those of a numerical simulation of the slower for Yb. The velocity distribution exiting the slower is very sensitive to the exact magnetic field profile, the laser power and detuning of the laser light. The number of atoms loaded into the magneto-optical trap was investigated as a function of the magnetic field gradient, the laser power and the laser detuning. The capture velocity of the Yb MOT is small because the linewidth of the MOT transition is narrow, and so we investigated the influence of broadening the laser linewidth by adding multiple finely-spaced sidebands to the laser light. After optimisation the caesium MOT trapped 5.5 x 10⁸ atoms at 125 ± 4 μK. The ytterbium MOT trapped 4.7 x 10⁹ atoms at 81 ± 2 μK. Lastly we demonstrate that both MOTs can be produced in the same vacuum chamber simultaneously.

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15

Bertram, Uwe Christoph. "Theoretical studies of Cs impurities in semiconductors." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319587.

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16

MacDonald, Cole. "Measurement of Radioactive Caesium Isotopes by Accelerator Mass Spectrometry." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31828.

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The first measurements of the radioactive 135Cs and 134Cs isotopes were made on an accelerator mass spectrometer. The natural Ba interference was suppressed using an isobar separator for anions (ISA) in order to measure the less abundant isobaric 134Cs and 135Cs isotopes. It was found that the Ba interference could be suppressed by a factor of 2 × 10^5 while 25% of Cs was transmitted. Furthermore, through comparing the known natural abundance of Ba isotopes to the measured concentration in a sample it was shown that the ISA does not introduce significant mass dependant fractionation at the level of 0.8%. A slow sequential injection analysis technique was developed to measure 135Cs using 134Cs as a reference isotope. This technique also permitted the monitoring of Ba interference. The ionization efficiency of Cs when analyzed in the molecular anion form, CsF2^- , was on the order of 10^−7 while the total measurement efficiency was 1.7×10^−9. The abundance sensitivity of this system was found to be 135Cs/ 133Cs = (1.3 ± 1.7) × 10^−10 , corresponding to a 3σ detection limit of 132.5 pg of analyte per target. Lastly, using the developed AMS techniques, beta spectroscopy, gamma spectroscopy, and isotope production, a measurement of the half life of 135Cs was made. The two measurements of the half life of 135Cs were 0.72 ± 0.32 Ma and 0.99 ± 0.42 Ma.

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17

Dalgleish, Heather Y. "Caesium-137 distribution and uptake in the agricultural environment." Thesis, Coventry University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240684.

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18

Chowdhury, M. A. M. "Laser cooling of caesium atoms applied to time standards." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359421.

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19

Harris, Magaret L. "Realisation of a cold mixture of rubidium and caesium." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2300/.

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This thesis describes a new apparatus designed to study cold, ultracold, and quantum degenerate mixtures of rubidium and caesium atoms. The Rb- Cs mixture is prepared using a double magneto-optical trap (MOT) system in which a two-species pyramid MOT acts as a source of cold atoms for a 'science' MOT. The first results of experiments on the magneto-optically trapped mixture are presented, including measurements of trap loss rates due to single-species and interspecies inelastic collisions. A technique for reducing interspecies loss by spatially separating the MOTs during loading is described. This technique allows 50-50 mixtures of Rb and Cs atoms to be loaded into a magnetic trap at close to their respective maximum single- species atom numbers. Alternatively, one species can be loaded with arbitrarily small amounts of the other. The displaced MOT technique is thus аn excellent starting point for investigations of interspecies Feshbach resonances and sympathetic cooling of Rb-Cs mixtures in magnetic and optical traps. In addition, a model of polarisation spectroscopy based on numerical integration of population rate equations is described. Theoretical polarisation spectra generated by the model are shown to agree with experimental spectra for the F = I + 1/2 → F' transitions in Rb and Cs. An investigation of the sub-Doppler dichroic atomic vapour laser locking (DAVLL) technique demonstrates how locking signals can be optimised for the Rb D2 transitions. The role of polarisation purity in generating the spectra is discussed, and impurities are modeled using a Jones matrix approach. Comparisons with polarisation spectroscopy and DAVLL are used to enhance understanding of atom-light interactions in spectroscopic systems, and indicate methods for optimising locking signals for use in cold atom experiments.

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20

Hird, Adine B. "The chemistry of radioactive caesium in upland peat soils." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480592.

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21

Higgitt, David L. "The use of caesium-137 measurements in erosion investigations." Thesis, University of Exeter, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279722.

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22

Godfrey, K. W. "An optical echo study of caesium-noble gas collisions." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235322.

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23

Michelberger, Patrick Steffen. "Room temperature caesium quantum memory for quantum information applications." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:19c9421d-0276-4c6d-a641-7640d2981da3.

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Quantum memories are key components in photonics-based quantum information processing networks. Their ability to store and retrieve information on demand makes repeat-until-success strategies scalable. Warm alkali-metal vapours are interesting candidates for the implementation of such memories, thanks to their very long storage times as well as their experimental simplicity and versatility. Operation with the Raman memory protocol enables high time-bandwidth products, which denote the number of possible storage trials within the memory lifetime. Since large time-bandwidth products enable multiple synchronisation trials of probabilistically operating quantum gates via memory-based temporal multiplexing, the Raman memory is a promising tool for such tasks. Particularly, the broad spectral bandwidth allows for direct and technologically simple interfacing with other photonic primitives, such as heralded single photon sources. Here, this kind of light-matter interface is implemented using a warm caesium vapour Raman memory. Firstly, we study the storage of polarisation-encoded quantum information, a common standard in quantum information processing. High quality polarisation preservation for bright coherent state input signals can be achieved, when operating the Raman memory in a dual-rail configuration inside a polarisation interferometer. Secondly, heralded single photons are stored in the memory. To this end, the memory is operated on-demand by feed-forward of source heralding events, which constitutes a key technological capability for applications in temporal multiplexing. Prior to storage, single photons are produced in a waveguide-based spontaneous parametric down conversion source, whose bespoke design spectrally tailors the heralded photons to the memory acceptance bandwidth. The faithful retrieval of stored single photons is found to be currently limited by noise in the memory, with a signal-to-noise ratio of approximately 0.3 in the memory output. Nevertheless, a clear influence of the quantum nature of an input photon is observed in the retrieved light by measuring the read-out signal's photon statistics via the g⁽²⁾-autocorrelation function. Here, we find a drop in g⁽²⁾ by more than three standard deviations, from g⁽²⁾ ~ 1.69 to g⁽²⁾ ~ 1.59 upon changing the input signal from coherent states to heralded single photons. Finally, the memory noise processes and their scalings with the experimental parameters are examined in detail. Four-wave-mixing noise is determined as the sole important noise source for the Raman memory. These experimental results and their theoretical description point towards practical solutions for noise-free operation.

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24

Fuller, Adam James. "Caesium and strontium sorption to sediment and clay minerals." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7481/.

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Radioactive caesium (137Cs) and strontium (90Sr) are two of the most important contaminant radionuclides present in many terrestrial environments, as a result of accidental and approved releases from anthropogenic nuclear activity. This thesis investigates the sorption of Cs and Sr onto the surfaces of common terrestrial minerals and a mixed phase sediment. The key findings of the work were with regard to the effect of solution pH and ionic strength on changing the mechanism of Cs and Sr interaction with reactive mineral surfaces. Caesium was found to sorb to multiple sorption sites within the mixed phase sediment. The first of these was a Cs selective site at the edge of the illite interlayer, known as the frayed edge site. It was determined from electron microscopy and x-ray absorption spectroscopy that Cs was selectively incorporated and retained in the interlayer structure in inner-sphere complexes. Cs was also found to sorb to two other main sorption sites in competition with other cations. Therefore the concentrations of Cs sorbing to the mineral surfaces were greatly reduced in low pH or high ionic strength conditions. Solution pH and ionic strength also played a major role in Sr sorption. At intermediate pH Sr sorbed to the surface of illite, chlorite and goethite in outer-sphere complexes. Therefore the presence of competing ions in solution significantly reduced total Sr sorption. However, at very high pH, Sr was specifically adsorbed into inner-sphere surface complexes. This allowed significant concentrations of Sr to sorb to the mineral surface even in high ionic strength solutions. The findings of this thesis mark a significant advance in understanding the fundamental processes governing the behaviour of 137Cs and 90Sr in the environment. Particularly it shows the importance of groundwater chemistry in governing sorption behaviour.

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25

Osborne, Boyd Neil. "Caesium and strontium exchange at specific clay mineral sites." Thesis, University of Central Lancashire, 1999. http://clok.uclan.ac.uk/19273/.

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The sorption of caesium and strontium onto clay minerals by exchange with other, charge compensating cations was studied by batch experiments. It was demonstrated that, for clay minerals with a net negative charge arising from isomorphous substitution within the crystal lattice, caesium and strontium sorption is predominantly a cation exchange process. Strontium exchange with charge compensating sodium ions on clay minerals, in the absence of competing cations, results in high strontium R3 values until exchange with sodium is virtually completed. Strontium exchange for calcium ions markedly reduces the strontium R4 under similar conditions. This is consistent with calculations to determine the selectivity coefficient for the exchange reaction. For the exchange of divalent strontium for monovalent sodium ions, theory predicts that the selectivity of the clay to the divalent cation increases with its loading. This is not the case for the homo-, divalent exchange of strontium for calcium and the marginal difference in hydration energies of the two cations further depresses strontium-selectivity of clays. Clay minerals are selective to caesium ions because of their low hydration energy and the Rd for caesium exchange with sodium is higher than for potassium exchange with sodium under similar conditions. Caesium sorption can cause 2: 1 swelling clay minerals to physically alter their structure as caesium loading increases. For this reason, caesium exchange on smectites does not fit Langmuir nor Freundlich plots. Also, the selectivity coefficient was found to vary widely with loading, compared with potassium exchange on smectites or caesium exchange on non-swelling minerals. Complete caesium exchange on Los Trancos montmorillonite causes the interlayer to collapse. Desorption of caesium ions from planar surface and edge sites can be achieved but the majority of caesium in the interlayer region is resistant to desorption and strong acid attack.

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26

Burslem, Rosemary Helen. "The pervaporative dewatering of alcohol using caesium polyacrylate membranes." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321842.

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27

Rangel, Elizabeth Vega. "Analysis of caesium and strontium in biological and environmental materials." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/843384/.

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Atmospheric testing of nuclear weapons and nuclear reactor accidents has resulted in widespread distribution of radioactive fission products into the environment. Determination of these radionuclides in biological and environmental samples presents serious difficulties because of interferences (90Sr with a continuous beta spectrum needs separation from other radionuclides, such as 90Y) and the poor limits of detection established by currently available counting equipment. In this project an ion exchange chromatography procedure for the separation of Cs, Sr and Y was developed. Since these radionuclides are hazardous, the method was developed using stable isotopes and inductively coupled plasma mass spectrometry (ICP-MS) as an elemental detector. In the first instance, the optimum operating conditions of the instrument for the analysis of Cs, Sr and Y were determined. These values were found to be 1.1 kW incident power and 1 1 min-1 nebuliser flow rate. The accuracy of the ICP-MS measurments was then assessed through the use of international reference materials NIST:SRM 1572 Citrus Leaves and NIST:SRM 1573 Tomato Leaves. In general a good agreement was observed for most of the elements between certified values and the results obtained in this study. The developed separation technique consisted of three stages. In the first stage ammonium molybdophosphate (AMP) and BioRad AG 50W-X8 resins were used. Caesium was separated from the other two isotopes using 2 M NH4OH. In the second stage Sr and Y were eluted from the above mentioned column using 4 M HNO3. The solution was then loaded onto a Sr-SpecRTM column where Sr is retained. In the third stage Sr was eluted from the column using deionised water. This setup provided excellent recoveries for the three stages namely: 85 % for Cs, 93 % for Y and 95 % for Sr. The analysis of Cs, Sr, and Y in foodstuffs, namely beans and milk was carried out after using the aforementioned separation procedure. Different growth media (commercial white silica sand, Lightwater garden soil, commercial garden soil, Rose Batch compost, and commercial compost) were used to assess the effect of organic content on the uptake of Cs and Sr by bean plants. These experiments involved the addition of different doses of added elemental concentration (100 to 1000 ?g ml-1) to the substrate and also various solution pH's (4 to 9). It was observed that the higher uptake of Cs and Sr by bean plants was at solution pH 7 and also for growth media with high organic content, i.e. Rose Batch compost and commercial compost. The distribution of Cs and Sr into the bean plant tissue resulting through absorption from commercial compost, showed that Cs is absorbed mostly in the stem (95 %) and with minimal levels in root and leaves (5 %). On the other hand, Sr was readily absorbed to the aboveground parts of the bean plants (36 % stem, 63 % in leaves) in contrast to other parts; 0.3 % root and 0.05 % beans. A study was undertaken to assess the uptake of Cs and Sr by bean plants in the presence of K and Ca at various solution pH's. It was found that in general, for all solution pH's, potassium inhibits the uptake of Cs. On the other hand, there appears to be a competition between Sr and Ca at high pH (7 to 9) which resulted in a rapid reduction of the Sr uptake. The addition of Ca to the substrate decreased the uptake of Sr by stems/leaves and increased the uptake of Sr by beans. As an application, solutions with different pH and radionuclide 137Cs and 90Sr) levels were added to mature bean plants. The developed ion exchange chromatography procedure was then adopted to separate 137Cs and 90Sr from these plants. In this study a Ge(Li) gamma ray spectrometer (ND 66) was used as a detector for 137Cs whilst a liquid scintillation counter was used for measuring 90Sr. Prior to the 137Cs measurements, the detection limits, resolution, absolute full energy peak and calibration of the instrument were evaluated. In general the values obtained in this work were in good agreement with the certified values.

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28

Khan, Abdul Waheed. "Modelling the structure, properties and phase transformations of caesium phosphomolybdate." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539696.

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29

Chen, Tzu-Yu. "Immobilisation of caesium from crystalline silicotitanate by hot isostatic pressing." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3712/.

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The main aim of this project was to develop a durable ceramic wasteform by HIPing Cs-exchanged crystalline silicotitanate (CST) used for nuclear waste clean-up. The sodium form (Na-CST) and niobium substituted sodium form (Na-Nb/CST) CST were hydrothermally synthesised and characterised. The synthesised CSTs and a commercial CST containing material, IONSIV®, were subjected to ion exchange studies and then the crystal phases present after HIPing were investigated. Cs-IONSIV® was thermally decomposed and converted to two major Cs-containing phases, Cs2TiNb6O18 and Cs2ZrSi6O15, and a series of other phases. Additionally the effect of metal addition on phase formation under HIP conditions was explored. The microstructure and phase assemblage of HIPed Cs-IONSIV® samples as a function of Cs content were examined using XRD, XRF, SEM and TEM/EDX. To understand the Cs bonding environment in these Cs-containing phases, structural characterisation was undertaken using Rietveld analysis of synchrotron X-ray powder diffraction data and neutron diffraction data. The potential of these phases for hosting Cs+ and its decay product Ba2+ was also studied. This thesis is also concerned with determining the aqueous durability of these HIPed samples by carrying out MCC-1 and PCT-B leach tests. These show very low Cs leach rates and the promise of safe long-term immobilisation of Cs from CSTs as well as suggesting these phases are more leach resistant than hollandite - the material targeted for Cs sequestration in Synroc.

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30

Oughton, Deborah H. "The environmental chemistry of radiocaesium and other nuclides." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277617.

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31

Banis, Y. Norouzi. "Data provision and parameter evaluation for erosion modelling." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242445.

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32

Klier, Jurgen. "Liquid helium on weak binding substrates." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337745.

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33

Ishak, Abdul Kadir. "Suspended sediment dynamics and flux in the macrotidal Taf estuary, South Wales." Thesis, Bangor University, 1997. https://research.bangor.ac.uk/portal/en/theses/suspended-sediment-dynamics-and-flux-in-the-macrotidal-taf-estuary-south-wales(2a686e53-be86-4731-ac19-aa998d5400ba).html.

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34

Ghamari, Langroudi Masoud. "Analysis of caesium sensitive membrane conductances in neurones of supraoptic nucleus." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37893.

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The release of vasopressin and oxytocin from the nerve terminals of magnocellular neurosecretory cells (MNCs) is optimised by increases in firing frequency and the adoption of a phasic pattern of firing in the soma. The temporal summation of post-spike depolarising afterpotentials (DAPs) of consecutive action potentials has been proposed to contribute to the generation of phasic firing. There has not been, however, any experimental evidence to support this hypothesis. In this study, a direct blocker of the DAP is introduced as being Cs +. Using this blocker, it is shown that the DAP plays an important role in the generation of phasic firing. Furthermore, these experiments reveal that external Cs+ causes depolarisation of MNCs when the membrane potential is held between action potential threshold and near -80 mV. External Cs+, however, is also known as a classical blocker of the hyperpolarisation activated inward current (IH). If I H is present in rat MNCs, the blockade of the IH by external Cs+ should lead to hyperpolarisation rather than the observed depolarisation. Using a recently introduced blocker of IH, ZD 7288, I show that IH is indeed expressed in rat MNCs, and that it also plays an important role in excitability and phasic firing of these cells. Finally, the ionic basis for the depolarising effects of external Cs + in rat MNCs is investigated. It is concluded in that extracellular Cs+ blocks both IH and a leakage K+ current that contributes significantly to the resting potential.

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35

Bance, Peter. "Evaporative cooling of caesium in a TOP trap : prospects for BEC." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244564.

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36

Karow, H. U. [Verfasser]. "Untersuchungen an Caesium-Plasmadioden mit Einstrahlung von Fremdlicht / H. U. Karow." Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1196578524/34.

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37

Absalom, J. P. "Radio-caesium lability and fixation in upland soils : measurement and modelling." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294725.

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38

Richards, Martyn W. "Chemical reactions of caesium, tellurium and oxygen with transition metal alloys." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276201.

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39

Owens, Philip Neil. "Towards improved interpretation of caesium-137 measurements in soil erosion studies." Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384997.

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40

Dove, William Thomason. "A three pulse optical echo study of depolarising collisions in caesium." Thesis, Open University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293719.

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41

Ruse, Mark. "An investigation of Caesium-137 at reference locations in Hong Kong." Thesis, Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21779326.

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42

Thomas, Angharad Mair. "Ultra-cold collisions and evaporative cooling of caesium in a magnetic trap." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403426.

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43

Day, George. "The immobilisation of Caesium and Strontium from nuclear waste captured by IONSIV." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8206/.

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A previous study revealed Cs_2TiNb_6O_1_8 to be the major Cs-containing phase after hot isostatic pressing Cs-loaded IONSIV (a commercial exchanger) which demonstrated excellent wasteform properties. Both experimental and theoretical studies have been carried out in order to assess if Cs_2TiNb_6O_1_8 is able to retain ^1^3^7Ba^2^+, the transmutation product of ^1^3^7Cs^+. A series of samples with different charge compensation mechanisms have been synthesised including Cs_2_-_xBa_xTi^(^4^+^)_1_+_xNb^(^5^+^)_6_-_xO_1_8, Cs_2_-_xBa_xTi^(^3^+^)_xTi^(^4^+^)_1_-_xNb_6O_1_8 and Cs_2_-_xBa_xTiNb^(^4^+^)_xNb^(^5^+^)_6_-_xO_1_8. Analysis suggested that Ba incorporation was not successful because of the identification of Ba impurities in the X-ray diffraction patterns. A series of atomistic simulations have also been performed to support the experimental work, using the General Utility Lattice Program code which suggested that Ba incorporation is not energetically favourable. Sr-loaded IOSNIV has also been thermally converted via calcination (in air) and hot isostatic pressing. The removal and immobilisation of Sr is an important process on account of ^9^0Sr being one of the more problematic radionuclides produced from the fission process. Both thermal conversion methods produced crystalline phase assembles which were analysed by X-ray diffraction, X-ray fluorescence and microscopy studies. The HIPed materials performed well in aqueous durability tests, suggesting these wasteforms will be suitable for final disposal in a geological disposal facility.

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44

Pendleton, Stephen J. "The migration of radioactive caesium and strontium through a bentonite-like clay." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14963.

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A number of leaks of radioactive liquors to ground are known to have occurred from several plant buildings, vaults and disposal trenches within and around the Separation area at the Sellafield nuclear site over the past 50 years1. The most significant of these leaks have occurred from the Magnox Silo, the Caesium Extraction Plant, the Magnox Reprocessing Pump House, the Sludge Storage Tanks, the Burial Pits and the Medium Active Evaporation and Thermal Denitration Plant. The radioactive contamination will be accompanied by other components of spent fuel reprocessing, including inorganic salts from neutralised acids, solvents and other organic compounds along with the typical contaminants commonly associated with large industrial activity such as heavy metals, fuel, oils, degreasing agents etc. The research in this thesis describes the effects of common industrial contaminants on the behaviour of Cs and Sr sorption to bentonite and montmorillonite clay minerals. Batch sorption experiments of Cs and Sr uptake onto bentonite and montmorillonite in a number of complex systems were investigated as follows: 1. Initial batch sorption experiments investigating the normal behaviour of the clay minerals. 2. Introduction of anthropogenic organic ligands EDTA, NTA and picolinic acid into the system and their influence on Sr and Cs uptake. 3. Time dependent studies investigating the effect that residence time of the anthropogenic organic ligands has on the sorption properties of montmorillonite and bentonite. 4. Quaternary systems where simulant Magnox sludge equilibrated water, at a number of concentrations, was introduced to ternary systems containing anthropogenic organic ligands. 5. Time dependent studies investigating the effect of hydrocarbons TCE, toluene and naphthalene on the uptake of Cs and Sr to bentonite and montmorillonite. The batch sorption experiments show that the presence of anthropogenic organic ligands reduces the uptake of Cs and Sr by both montmorillonite and bentonite. It is also shown that the presence of simulant Magnox sludge in quaternary systems can also reduce the uptake of Cs and Sr, with significant reductions in sorption observed for Sr sorption in EDTA quaternary systems. Further, the uptake of Cs and Sr to bentonite and montmorillonite appears to decrease with increasing anthropogenic organic ligand residence time. This suggests that the ligands are altering the surface of the clay minerals reducing the number of available binding sites. The influence of hydrocarbons shows a significant decrease in sorption after 3 months for Cs and Sr sorption to montmorillonite. There were no further significant changes for all other hydrocarbon systems investigated.

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45

Parkinson, Benjamin Graves. "Influence of Composition on Structure and Caesium Volatilisation from Glasses for HLW Confinement." Thesis, University of Warwick, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487979.

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The problem of high-temperature volatilisation of material from alkali borosilicate glasses, commonly used for the long-term storage of high-level nuclear waste, has been investigated using four mixed-alkali borosilicate glass systems. Each system is based on the mixed alkali borosilicate base-glass (MW) used in the UK and USA, initially being doped with one of three simulated waste oxides in varying quantities; aluminium oxide (0.95 mol%), lanthanum oxide (1.68 mol%) or magnesium oxide (2.55 or 10.2 mol%), before increasing quantities of caesium o~de were added (0-9.66 mol%) [1]. A number of experimental techniques have been employed in this study, including various thermal analysis measurements, nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. From boron-ll and silicon-29 MAS NMR measurements, the fraction of tetrahedral boron (N4) and silicon Q3 and Q4 units (with respective three- and four-bridging oxygen) were resolved and compared against theory [2] and previous experimental measurements [3-6]. Silicon Q3 fractions resolved from NMR measurements [1] were compared against values obtained from quantitative Raman spectroscopy [7]. This approach is shown to be successful in resolving silicon Q3 units and therefore would be particularly useful in studies where the presence of large (> 1 mol%) quantities of paramagnetic species in glasses makes NMR difficult. Further detail resolved in the lIB MAS NMR spectra of these glasses also enabled the fraction of reedmergnerite and danburite medium~~~' order structures to be calculated [8]. The volatilisation of alkali borate and alkali silicate material, identified using EDX measurements, is shown not only to increase as a function of the fraction of Q3 units but is also affected by the presence of these medium-range order structures, where increasing quantities of danburite units leads to a greater degree of volatility [4,8]. Finally, a number of 170-enriched mixed-oxide alkali borosilicate systems have been manufactured, using an 17O-enriched silicon oxide precursor obtained through an established hydrolysis reaction of 20% oxygen-I7 enriched water with silicon tetrachloride [9]. Subsequent thermal analysis and NMR measurements have shown the oxygen-I7 environments of these borosilicate systems to vary significantly based on the presence of caesium, aluminium or lanthanum in quantities realistic to the modified mixed-alkali borosilicate glasses in the remainder of this study.

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46

Mercer, Lee Jonathan. "Radio-caesium uptake and flux in wheat as influenced by external potassium concentration." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369102.

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47

Webster, Stephen. "Prospects for Bose-Einstein condensation in caesium : cold collisions and dipole-force trapping." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325563.

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48

Haworth, Richard C. "Neutron scattering studies of vitreous iron phosphates and vitreous and crystalline caesium borates." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501343.

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Introductory chapters within this thesis cover the basics of glass science, magnetic behaviour in materials, nuclear and magnetic neutron scattering theory, and instrumentation and data reduction techniques. The sample chapters present experimental techniques, results and discussions, and conclusions concerning the study of the nuclear and magnetic structure and dynamics of vitreous iron phosphates; the structure and dynamics of vitreous caesium borates; and a structural characterisation of the phases of caesium enneaborate. All of the glasses have the common attribute of being candidates for nuclear waste immobilisation through vitrification, although the prime motivation for this work has been to further the current understanding of the nuclear structure (and magnetic and larger scale structure in the case of the iron phosphates) of these glass systems through novel dynamical studies.

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49

De, Silva K. M. N. "Kinetic investigation of atomic rubidium and caesium by time-resolved laser-induced fluorescence." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598454.

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This dissertation is concerned with characterising the collisional behaviour of the heavier alkali elements, rubidium and caesium atoms, in their ²S_1/2 electronic ground states at elevated temperatures by time-resolved laser-induced fluorescence (LIF). This thesis is comprised of six chapters. Chapter one provides a general introduction of the gas phase kinetic study of alkali atoms in their ²S/_1/2 ground states, particularly in the time-resolved mode. Chapter two gives an account of the detailed description of the apparatus used for the present investigation for studying the atomic reactions of Rb and Cs at elevated temperatures by time-resolved LIF following pulsed irradiation. Chapter three describes the determination of absolute second-order rate constants for the collisional removal of Rb(5²S_1/2) with a wide range of alkyl chlorides (CH₃Cl, C₂H₅Cl, C₃H₇Cl, C₄H₉Cl, C₅H₁₁Cl, C₆H₁₃Cl and C₇H₁₅Cl), fluoralkyl chlorides (CF₃Cl, CF₂Cl₂ and CFCl₃) and other simple chlorine-containing molecules (CH₂Cl₂, CHCl₃ and CCl₄). Chapter four describes the collisional behaviour of Rb(5²S_1/2) with a series of alkyl bromides (CH₃Br, C₂H₅Br, C₃H₇Br, C₄H₉Br, C₅H₁₁Br, and C₆H₁₃Br), and other simple bromine and iodine-containing-molecules (CF₃Br, CH₂Br₂, C₂H₄Br₂, CH₃I and CH₂I₂) at elevated temperature. Chapter five includes the detailed investigation of the oxidation reaction between Rb(5²S_1/2) and N₂O as a function of temperature over a limited range accessible with this system. This chapter also describes the reactions of Rb(5²S_1/2) with CH₃Cl, CH₃Br and CF₃Cl as a function of temperature. Despite the limitations with this system, these are the first temperature dependent studies of the Rb + CH₃Cl, CH₃Cl, CH₃Br and CF₃Cl systems investigated by time-resolved LIF. Chapter six describes the determination of absolute second-order rate constants for the collisional removal of Cs(6²S_1/2) with a series of alkyl chlorides (CH₃Cl, C₃H₇Cl, C₄H₉Cl, C₅H₁₁Cl, C₆H₁₃Cl and C₇H₁₅Cl) and alkyl bromides (C₃H₇Br, C₄H₉Br, C₅H₁₁Br, C₆H₁₃Br and C₇H₁₅Br) investigated by time-resolved laser-induced fluorescence at elevated temperatures.

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50

Kennard, David R. "The chemistry of the corrosion of transition metals by caesium, tellurium and oxygen." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357966.

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