Dissertationen: „Ion physics“

1

Hughes, Ian G. „Electron ion and ion-ion collisions“. Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335410.

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2

Kelly, Gregory J. „Negative ion production from positive ions incident in a metal vapour“. Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/22416.

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3

Fisher, Zachary (Zachary Kenneth). „Shuttling of ions for characterization of a microfabricated ion trap“. Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78510.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 65-67).
In this thesis, I present experimental results demonstrating the characterization of a planar Paul trap. I discuss the theory of ion trapping and analyze the voltages required for shuttling. Next, the characteristics of a digital-to-analog converter (DAC) are calibrated, and this instrument is integrated into trapping experiments to test the viability of the analytic model. Combining theory with the capabilities of the DAC, I calculate that the new experimental system is capable of 3 nm-precision control of the ion. Taking advantage of this ion control, I present initial results for a lock-in micromotion detection method which minimizes stray fields around an ⁸⁸Sr+ ion using Fourier analysis on the ion fluorescence to detect resonance at the secular frequencies. This method drives the ion oscillator across resonance using a superimposed radiofrequency electric field, which allows for off-axis field measurements as well as trap characterization. With this method, the secular frequencies of the trap are measured and are observed to fall within 3.50[sigma] of the analytic prediction.
by Zachary Fisher.
S.B.

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4

Holden, Nicola Kathleen. „Atmospheric ion measurements using novel high resolution ion mobility spectrometers“. Thesis, University of the West of England, Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288184.

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5

Kellerbauer, Alban. „Production of a cooled ion beam by manipulation of 60-keV ions into a radio-frequency quadrupole ion guide“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0025/MQ50804.pdf.

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6

Labaziewicz, Jarosław. „High fidelity quantum gates with ions in cryogenic microfabricated ion traps“. Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45167.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 135-146).
While quantum information processing offers a tantalizing possibility of a significant speedup in execution of certain algorithms, as well as enabling previously unmanageable simulations of large quantum systems, it remains extremely difficult to realize experimentally. Recently, fundamental building blocks of a quantum computer, including one and two qubit gates, teleportation and error correction, were demonstrated using trapped atomic ions. Scaling to a larger number of qubits requires miniaturization of the ion traps, currently limited by the sharply increasing motional state decoherence at sub-100 [mu]m ion-electrode distances. This thesis explores the source and suppression of this decoherence at cryogenic temperatures, and demonstrates fundamental logic gates in a surface electrode ion trap. Construction of the apparatus requires the development of a number of experimental techniques. Design, numerical simulation and implementation of a surface electrode ion trap is presented. Cryogenic cooling of the trap to near 4 K is accomplished by contact with a bath cryostat. Ions are loaded by ablation or photoionization, both of which are characterized in terms of generated stray fields and heat load. The bulk of new experimental results deals with measurements of electric field noise at the ion's position. Upon cooling to 6 K, the measured rates are suppressed by up to 7 orders of magnitude, more than two orders of magnitude below previously published data for similarly sized traps operated at room temperature. The observed noise depends strongly on fabrication process, which suggests further improvements are possible. The measured dependence of the electric field noise on temperature is inconsistent with published models, and can be explained using a continuous spectrum of activated fluctuators. The fabricated surface electrode traps are used to demonstrate coherent operations and the classical control required for trapped ion quantum computation. The necessary spectral properties of coherent light sources are achieved with a novel design using optical feedback to a triangular, medium finesse, cavity, followed by electronic feedback to an ultra-high finesse reference cavity.
(cont.) Single and two qubit operations on a single ion are demonstrated with classical fidelity in excess of 95%. Magnetic field gradient coils built into the trap allow for individual addressing of ions, a prerequisite to scaling to multiple qubits.
by Jarosław Labaziewicz.
Ph.D.

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7

Segal, Matthew. „Development of an ion transport system for singly charged ion injection into an electron string ion source (ESIS) charge-breeder“. Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33024.

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A 1+ ion delivery system was designed and constructed for the purpose of ion injection into the Electron String Ion Source (ESIS) charge-breeder at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The transport system was initially developed at iThemba LABS in Cape Town. This system includes a Liquid Metal Ion Source (LMIS) and an ion extraction and focusing system. The ion delivery system is used to produce Ga+ and Au+ ions which are transported through a beam-line system consisting of charged particle optics such as focusing einzel-lenses, an electrical quadrupole switchyard for 90◦ beam bending, and subsequent correction and focusing lenses before the entry port into the ESIS. A replica of the full system was created and used to study injection and ion transport efficiency before implementation with the ESIS. A multi-wire harp beam profilometer was used to study ion beam profiles and to obtain geometric parameters of Ga+ beams. Ga+ injection into the KRION 6T ESIS was performed successfully using the ion injection system. The extraction of multiply charged gallium was successful after 1+ injection into the KRION 6T ESIS, with a maximum charge-state of 23+. Although 1+ to n+ injection has been performed with similar Electron Beam Ion Source (EBIS) devices, this work is the first case of 1+ to n+ injection using the ESIS. This research was conducted within the frame-work of the South Africa/JINR collaboration and has been funded by the National Research Foundation (NRF).

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8

McGuinness, Philip. „Electron-ion elastic collisions“. Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268236.

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9

Boudreault, Ghislain. „Accurate ion beam analysis“. Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/844001/.

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This thesis primarily deals with accuracy obtainable when using IBA (Ion Beam Analysis) techniques to characterize materials. RBS (Rutherford Backscattering Spectrometry) is the main technique used, together with EBS (Elastic Backscattering Spectrometry), ERDA (Elastic Recoil Detection Analysis) and NRA (Nuclear Reaction Analysis). An exhaustive literature review on these analytical methods is made in connection with accuracy issues such as stopping powers and multiple scattering. The experimental set-ups and procedures are described, with emphasis laid on critical aspects of work where the highest accuracy is required. The instrumentation for dosimetry on ion implanters is first estabhshed at the 1% level for high-dose heavy implants in silicon. A new parameterisation of He stopping power in Si is used, and this latter material, via the surface yield, is used as a calibration standard. A precision (standard uncertainty) in the determination of implantation doses by RBS is conclusively demonstrated at 1.5%. The IBA DataFurnace code is validated for such accurate analysis, which can now be made routinely and rapidly. The certified Sb sample IRMM-302/BAM-L001, which has a certification of 0.6% traceable to the international standard of weight in Paris, is measured, and more importantly this measurement demonstrates the reliability of the stopping power parameterisation at 1.4%. Using conventional ERDA, the H dose of an amorphised Si wafer, implanted with 6-keV H+ ions, is found to be 57.8(1.0)x1015 at/cm2, which is a 1.8% standard uncertainty. The estimated combined uncertainty of this measurement is ~6%, and this mainly comes from the determination of the ERDA solid angle by using standard Kapton. The Kapton composition is carefully determined using RBS. The RBS solid angle is obtained using the amorphised silicon surface yield as a calibration standard as in the dosimetry analysis mentioned above. The ERDA H absolute dose obtained is compared with the results from other participants from all over the world in a Round Robin exercise, which includes measurements by using both He-ERDA and HI-ERDA (Heavy Ion-ERDA) together using various detectors. The results from each participant are given and compared. The overall absolute dose obtained of the implant is 57.0(1.2)x1015 H/cm2, and this represents an inter-lab reproducibility of 2.2% (standard uncertainty). Unstable surface hydrogen contamination was observed, and this surface peak was resolved by some of the methods. This implant can now be used as a standard for quantitative analysis of hydrogen. Low-fluorine content SiO2:F films are analysed by RBS for absolute fluorine concentration determination. Prior to the RBS analysis, the uniformity of the films and stability of F under beam irradiation is investigated. Because the RBS is not very sensitive to F and the F signal has a large matrix background, an internally consistent method of data handling, which enables the relative collected charge to be determined very precisely for the spectra from different samples, is developed. This method has as a parameter the F content, which is then extracted iteratively. A F concentration of 10 at% is determined with an estimated uncertainty of 10% (one percentage point, i.e. 10 +/- 1%). The O stopping powers are found to be the main factor governing the accuracy of the absolute determination of the F content. All the other uncertainties add up to only ~1%. The elemental composition of residual deposits from an ion implanter is thoroughly investigated using several complementary analytical methods, namely, RBS, BBS and NRA. Preliminary SEM/EDAX results are used as a guide. Depth profiles of such non-homogeneous, non-fiat and brittle samples are obtained, which give an indication of the concentration of each element present. From this complete IBA elemental study, some unprecedented light is brought on both the history of the implanter and the way in which these deposits are formed. Such an investigation is essential for a better understanding and the development/miniaturisation of semiconductors as it impressively pushes the boundaries of accuracy obtainable in IBA material characterisation.

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10

Sterling, Robin C. „Ytterbium ion trapping and microfabrication of ion trap arrays“. Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/39684/.

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Over the past 15 years ion traps have demonstrated all the building blocks required of a quantum computer. Despite this success, trapping ions remains a challenging task, with the requirement for extensive laser systems and vacuum systems to perform operations on only a handful of qubits. To scale these proof of principle experiments into something that can outperform a classical computer requires an advancement in the trap technologies that will allow multiple trapping zones, junctions and utilize scalable fabrication technologies. I will discuss the construction of an ion trapping experiment, focussing on my work towards the laser stabilization and ion trap design but also covering the experimental setup as a whole. The vacuum system that I designed allows the mounting and testing of a variety of ion trap chips, with versatile optical access and a fast turn around time. I will also present the design and fabrication of a microfabricated Y junction and a 2- dimensional ion trap lattice. I achieve a suppression of barrier height and small variation of secular frequency through the Y junction, aiding to the junctions applicability to adiabatic shuttling operations. I also report the design and fabrication of a 2-D ion trap lattice. Such structures have been proposed as a means to implement quantum simulators and to my knowledge is the first microfabricated lattice trap. Electrical testing of the trap structures was undertaken to investigate the breakdown voltage of microfabricated structures with both static and radio frequency voltages. The results from these tests negate the concern over reduced rf voltage breakdown and in fact demonstrates breakdown voltages significantly above that typically required for ion trapping. This may allow ion traps to be designed to operate with higher voltages and greater ion-electrode separations, reducing anomalous heating. Lastly I present my work towards the implementation of magnetic fields gradients and microwaves on chip. This may allow coupling of the ions internal state to its motion using microwaves, thus reducing the requirements for the use of laser systems.

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11

Li, Ming. „Quantum Theory of Ion-Atom Interactions“. University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404667900.

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12

Papadopoulos, S. „Atomic and cluster ion emission from liquid metal ion sources“. Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375310.

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13

Franklin, A. M. „Computational applications and ion behaviour in ion trap mass spectrometer“. Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294313.

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14

Glass, John T. „Relativistic ion-atom collision processes“. Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282153.

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15

O'Rouke, Sheelagh Francesca Camille. „Theory of ion-atom collisions“. Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334486.

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16

Bolouri, H. „Secondary ion emission“. Thesis, University of Salford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353964.

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17

Antohi, Paul Bogdan. „Cryogenic surface electrode ion traps with integrated superconducting microwave resonators for polar molecular ion spectroscopy“. Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68866.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 129-144).
Trapped cold molecules open the possibility of studying ultracold chemistry and astrophysical processes in laboratory settings. Their rich internal structure also makes them suitable for quantum information manipulation or for tests of fundamental laws of nature. These experiments require precise control over the molecular internal degrees of freedom. There are few present proposals for trapping and cooling molecules. One proposal is based on confining neutral polar molecules in DC Stark shift traps, but this approach presents some issues. An attractive alternative is to confine polar molecular ions in RF Paul ion traps, which is the focus of this thesis. The objectives here are to develop the theoretical models and to devise the experimental components and methods to investigate the coupling of polar molecular ions' rotational states to the microwave radiation. The new approach presented here is based on co-trapping Sr+ atomic ions together with SrCl+ molecular ions in a cryogenic surface electrode RF ion trap and on using the coupling of the molecular ion's rotational states to an integrated superconducting microwave line or cavity either as a cooling method or for precise rotational spectroscopy. The first part of the thesis describes two theoretical methods for observing the coupling of the microwave radiation to the rotational levels of a molecule. The first method proposed is based on the enhancement of the molecular rotational transition rates by the co-trapped molecular-atomic ions Coulomb collisions. The second method is based on microwave cavity assisted heating or cooling of the molecular ions. The second part of the thesis presents the development of a cryogenic surface electrode RF ion trap with an integrated microwave transmission line/resonator. The ion trap is operated in a 4.2 K closed cycle cryostat.
by Paul Bogdan Antohi.
Ph.D.

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18

Sprague, Robert Wendell. „Optical absorption and anisotropy of refractory oxides fabricated by ion-assisted deposition and ion plating“. Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185285.

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The thickness and refractive index of thin films determines their performance. Thickness variation due to the deposition process is well understood and correctable. Variation in the refractive index due to the deposition process is a considerably more complex problem. In this work two important members of the class of high index refractory materials: Tantalum pentoxide and Titania are investigated. These materials are known to produce very high quality films. Ion plating of tantalum results in the extremely high quality films, but ion plating of titania results in films with absorption that is too high and the process is now no longer used. Ion assisted deposition of titania, however, results in high quality films. The variation in refractive index due to the columnar microstructure of these materials has been eliminated but the subtler aspects of the thin films behavior is more difficult to improve. It is this aspect that I have investigated. In particular what improvements can be made by post deposition annealing of ion plated and ion assisted deposition of Tantalum pentoxide, and can the ion bombardment of Titania result in films with increased birefringence. If this anisotropy can be increased a number of interesting polarizing elements can be produced. These investigations were performed in distinct methods. The absorption of these films required the design and construction of a specialized highly sensitive waveguide apparatus. The investigation of anisotropy involved examining the evolution of form birefringence in situ by polarimetry. A further parameter of interest, although not as yet widely studied in thin films as the effects are small and difficult to observe is material nonlinearity. In the future the design of dynamic filters or coatings for powerful laser systems will require a good means of determining this kind of behavior in thin films. To this end we have designed our absorption instrument to be able to determine changes in refractive index due to a strong external pump beam. These effects are described in chapter three as an indication of future trends in this area.

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19

Coath, Christopher D. „A study of ion-optics for microbeam secondary-ion mass spectrometry“. Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335723.

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20

Epstein, Charles S. „Development of a polarized Helium-3 ion source for RHIC using the electron beam ion source“. Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84388.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 39-40).
This thesis presents my work on the design and development of a source of polarized Helium-3 ions for the Relativistic Heavy Ion Collider at Brookhaven National Lab, Upton, NY. The 3He atoms will be polarized using the technique of metastability exchange optical pumping (MEOP), and will then be flowed into the newly commissioned Electron Beam Ion Source (EBIS). Fully stripped 3He++ ions will be extracted and their polarizations measured at low energies before acceleration in the RHIC complex.
by Charles Samuel Epstein.
S.B.

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21

Mazeliauskas, Aleksas. „Fluctuations in Ultra-Relativistic Heavy Ion Collisions“. Thesis, State University of New York at Stony Brook, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10256734.

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Fluctuations are one of the main probes of the physics of the new state of hot and dense nuclear matter called the Quark Gluon Plasma (QGP) which is created in the ultra-relativistic heavy ion collisions. In this dissertation we extend and improve upon the existing descriptions of heavy ion collisions in three different directions: we study the new signatures of initial state fluctuations, the propagation of perturbations in the early stages of the collision, and the effect of thermal fluctuations on the hydrodynamic expansion of the QGP.

First, in Chapter 3 we study initial state fluctuations by examining the complete statistical information contained in the two-particle correlation measurements in hydrodynamic simulations of Pb+Pb collisions at the CERN Large Hadron Collider (√s_NN = 2.76 TeV). We use Principal Component Analysis (PCA) to decompose the spectrum of harmonic flow, v_n(p_T) for n = 0–5, into dominant components. The leading component is identified with the standard event plane v_n(p_T), while the subleading component describes additional fluctuations in the two-particle correlation function. We find good geometric predictors for the orientation and the magnitude of the leading and the subleading flows. The subleading v₀, v₁, and v₃ flow harmonics are shown to be a response to the radial excitation of the corresponding eccentricity ϵ_n. In contrast, for v₂ the subleading flow in peripheral collisions is dominated by the nonlinear mixing between the leading elliptic flow and radial flow fluctuations. Nonlinear mixing also plays a significant role in generating subleading v₄ and v₅ harmonics. The PCA gives a systematic way of studying the full information of the two-particle correlation matrix and identifying the subleading flows, which we show are responsible for factorization breaking in hydrodynamics.

Second, in Chapter 4 we study the thermalization and hydrodynamization of fluctuations at the early stages of heavy ion collisions. We use leading order effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations. For the short evolution we can use a linear response theory to construct the pre-equilibrium Green functions. Then the energy-momentum tensor at a time when hydrodynamics becomes applicable can be expressed as a linear convolution of response functions with the initial perturbations. We propose combining effective kinetic theory with weak coupling initial state models, such as IP-Glasma, to model the complete pre-thermal evolution from saturated nuclei to hydrodynamics in a weak coupling framework.

Last, in Chapter 5 we consider out-of-equilibrium hydrodynamic fluctuations in the expanding QGP. We develop a set of kinetic equations for a correlator of thermal fluctuations which are equivalent to nonlinear hydrodynamics with noise. We first show that the kinetic response precisely reproduces the one-loop renormalization of the shear viscosity for a static fluid. We then use the hydro-kinetic equations to analyze thermal fluctuations for a Bjorken expansion. The steady state solution to the kinetic equations determine the coefficient of the first fractional power of the gradient expansion (∞ 1/(τ T)^3/2), which was computed here for the first time. The formalism of hydro-kinetic equations can be applied to more general background flows and coupled to existing viscous hydrodynamic codes to incorporate the physics of hydrodynamic fluctuations.

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22

Varfalvy, Peter. „Precision ion optics of axisymmetric electric systems“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23430.

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A comprehensive computer package for the calculation and simulation of charged-particle dynamics in electromagnetic fields has been developed and tested. The program provides a user-friendly and flexible interface for visualizing particle dynamics using phase space diagrams, which are essential for complete understanding of a beam optics system. The program performs an accurate finite difference computation of a user-defined boundary value problem (in the form of a grid) followed by a high-order Runge-Kutta numerical integration of the equations of motion to evaluate the particle dynamics within the field. The program is unique in its combination of these flexible finite calculation techniques with the parallel processing of particle ensembles in order to display phase space diagrams.
After extensive testing, the program has been used to design a low emittance ion source and an ion beam deceleration system for high-efficiency ion collection. The program has also been used to analyze a radiofrequency quadrupole collisional focusing system using ion mobility concepts.

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23

Lo, Monaco L. „Nucleon transfer in heavy ion reactions“. Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371555.

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24

Montgomerie, Christine Ann. „Spectroscopy of the hydrogen molecular ion“. Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257936.

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25

Georgiacodis, D. N. „Low temperature ion-irradiation effects in silicon studied by ion-channelling techniques“. Thesis, University of Sussex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304345.

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26

BARBERET, Philippe. „Développement d'une ligne d'irradiation microfaisceau en mode ion par ion pour la radiobiologie expérimentale à l'échelle cellulaire“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2003. http://tel.archives-ouvertes.fr/tel-00004084.

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Un dispositif micro-irradiation par ions isolés a été développé au CENBG pour des applications en radiobiologie à l'échelle cellulaire. Cette installation consiste en un aménagement de la ligne microfaisceau préexistante qui permet déjà d'obtenir un faisceau de protons ou de particules alpha entre 1 et 3 MeV, de faible intensité, et d'une résolution spatiale sous vide inférieure au micromètre. La majeure partie de ce travail a consisté à développer un étage d'irradiation adaptable sur la microsonde et permettant de délivrer les ions à l'air avec une précision absolue de quelques micromètres. Un programme permettant le contrôle de la totalité des instruments ainsi que des phases d'étalonnage et d'irradiation automatiques a également été mis au point. Des outils de simulation Monte Carlo, nécessaires à la caractérisation et à l'optimisation du dispositif et notamment en terme de résolution spatiale, ont été validés à l'échelle du micromètre par comparaison à des résultats expérimentaux. Les performances du dispositif, notamment en terme de contrôle du nombre d'ions, de résolution spatiale et de précision d'irradiation ont été testées sous faisceau. Les résultats obtenus permettent d'envisager les premières applications dans des études de radiobiologie. Dans un futur proche cet outil va permettre l'étude des réponses cellulaires aux faibles doses, allant jusqu'au cas extrême d'un ion pour une cellule. Il devrait permettre par ailleurs d'aborder des mécanismes cellulaires fondamentaux tels la signalisation, la communication intercellulaire ou encore la mort cellulaire programmée (apoptose).

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27

O'Neill, Raymond W. „Electron-ion excitation studies“. Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333828.

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28

Sharples, Graham Robert. „Low energy ion implantation“. Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327921.

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29

Ghalambor, Dezfuli Abdol Mohammad. „Characteristics of a laser desorption ion source“. Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60065.

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The characteristics of a pulsed laser ion source have been studied. A pulse from a heating laser (Nd: YAG laser) desorbs the neutral atoms from the surface of a metal target and then a second pulse or pulses from excimer or dye lasers selectively ionize the desorbed neutrals using the Resonance Ionization Spectroscopy technique. Time-of-flight and electrostatic energy analyzer measurements have been used to study different characteristics of this ion source such as spatial, velocity, and energy distributions. These measurements reveal that although the energy spread of the basic source is relatively high, (FWHM $ sim$ 37 eV) the use of a pulsed acceleration system can reduce this spread by a factor of 5 (to about 7 eV), making the source suitable for collinear laser spectroscopy.

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30

Ashman, A. S. „Laser spectroscopy of molecular ions in an Ion Cyclotron Resonance apparatus“. Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234408.

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31

May, Paul W. „The energies of ions, electrons and neutral in reactive ion etching plasmas“. Thesis, University of Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303946.

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32

Shen, Kuan-Hsuan. „Modeling ion conduction through salt-doped polymers: Morphology, ion solvation, and ion correlations“. The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595422569403378.

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33

McCartney, Mark. „Ionization processes in multielectron ion-atom collisions“. Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359106.

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34

Grogan, Daniel Francis. „Ion beam polishing of diamond films“. Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185199.

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Emerging deposition technologies now permit the nucleation and growth of diamond films on a variety of substrates, bestowing on them the extraordinary mechanical, chemical, thermal, and electrical properties of diamond. However, the diamond films invariably suffer from great surface roughness and attendant optical scatter which preclude their use in most optical applications. To be useful optically, these films must be polished. In this work, diamond films deposited by microwave-assisted chemical vapor deposition on silicon substrates have been polished by a beam of 500 eV oxygen ions with the use of spin-coated planarizing overcoat. The overcoat was developed to have the same ion-beam etch rate as the diamond films at the planarizing angle. The films' surface roughness was reduced from in excess of 1 μm (rms) and 6 μm (peak-to-valley), to 35 nm (rms) and 217 nm (peak-to valley). The polished films retained their diamond character and surface contamination was not detected. This polishing process makes optical applications in the near-infrared realizable for these diamond films.

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35

Pearson, Christopher Elliott. „Theory and application of planar ion traps“. Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36398.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 101-106).
In this thesis, we investigate a new geometry of Paul trap with electrodes in a plane. These planar ion traps are compatible with modern silicon microfabrication, and can be scaled up to large arrays with multiple trapping zones. We implement these designs on printed circuit boards with macroscopic ions, allowing us to study the traps while avoiding the experimental challenges of atomic ion traps. We discuss the dynamics of ions in the traps using both numerical and analytical means. Scalable traps are of interest to the quantum computing community as a potential implementation of a large scale quantum computer. However, there are concerns about the low trap depth relative to a conventional trap of the same size. We address this in three ways, first by introducing a conductive plane above the trap to increase its depth, then by using a deeper trap with a three dimensional electrode geometry to load the trap, and finally by loading the trap directly while using a buffer gas to slow down energetic ions so that the trap can capture them. Also of concern is the ability of the trap to move ions through arms and intersections.
(cont.) We demonstrate these movement operations, and study properties of the linear trap including the secular frequency and geometric factors between planar and four rod traps. The precision of atomic ion trap experiments makes them sensitive to background gas pressure at levels that are undetectable to conventional gauges. The capacity for integrating circuitry and optical elements with the trap could anticipate complete ion trap experiments performed by a single chip, and a new technology for an integrated pressure gauge would be immensely useful if the pressure detection can shown to be feasible and repeatable. In a point planar trap, we observe ion motion to determine background gas pressure, demonstrating an application that could bring planar ion traps into much wider use.
by Christopher Elliott Pearson.
S.M.

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36

Boyce, Kevin Robert. „Improved single ion cyclotron resonance mass spectroscopy“. Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/42551.

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37

George, Elizabeth Marie. „Fiber optic integration in planar ion traps“. Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44459.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.
Includes bibliographical references (leaves 69-70).
Atomic ion traps are are excellent tools in atomic physics for studying single ions. Accurate measurement of the ion's electronic state in these ion traps is required by both atomic clocks and quantum computation. Quantum computation with trapped ions can only scale to larger numbers of qubits if the ion traps and their laser delivery and measurement infrastructure can be scaled to smaller sizes. Fiber optics are a promising method of measurement because they collect a large fraction of light scattered by the trapped ions, and many optical fibers can be placed in a small area, allowing more ions to be measured in a small region. The question I address in this thesis is, "How can optical fibers be integrated onto planar ion traps?" This thesis presents a process I designed and implemented for integrating optical fibers onto planar ion traps as well as a system for integrating optical fibers into a cryogenic system. While the fiber integration was successful, we were unable to trap any ions in our fiber-integrated ion trap. We were able to show that the integrated fiber could collect light scattered from the surface of ion trap, and hypothesize that the large amount of dielectric present on the surface of the trap may have distorted the trapping potential and prevented us from trapping any ions. We also determined that scatter spots on the surface of the trap are a much bigger problem for fiber optic light collection systems than for traditional bulk optics systems. Finally, we propose a method of integration that could reduce the amount of exposed dielectric in the vicinity of the trap, as well as solve the problem of sensitivity to scatter spots.
by Elizabeth Marie George.
S.B.

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38

Cornell, Eric Allin. „Mass spectroscopy using single ion cyclotron resonance“. Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13562.

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39

Vogt, Markus O. „Toward coherent ion-cavity coupling“. Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/68376/.

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Entanglement is an established resource in quantum information processing, and there is a clear imperative to study many-body systems both in quantum technology applications and for probing fundamental physical laws. Ion trap cavity quantum electrodynamics is a highly promising platform for research. Prerequisites are the controlled coupling of many ions to the cavity field along with the ability to initialize the quantum states and drive coherent transitions between them. A coaxial ion trap and high finesse cavity system has been shown to couple strings of up to five ions to the cavity mode with nearly optimal coupling strength thanks to precise control over their positions in the standing wave and their mutual Coulomb interaction. The predictive power of the theoretical model demonstrates that the scheme can be extended to more ions or to higher coupling regimes. In a separate experiment it has been demonstrated that a quantum state can be initialized, before coherently transferring the population to a qubit state through the cavity interaction. The emission of polarized photons in the cavity mode has been measured, taking the system closer to the generation of cluster states for quantum information research and fundamental studies in many-body entanglement. Building on the aforementioned work, an infrastructure has been put in place for the direct observation of vacuum Rabi oscillations between a single ion and the cavity. In this scheme, the contribution to the dynamics from the dominant incoherent channel is minimized through post-selection of the data. As a quantum system coupled to a reservoir with memory, it will provide experimental constraints on theoretical work in the field of non-Markovian dynamics.

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40

Eccles, Adrian John. „The design, construction and characterisation of a microfocused ion/atom gun for use in secondary ion mass spectrometry (SIMS)“. Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334868.

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41

Allcock, David Thomas Charles. „Surface-electrode ion traps for scalable quantum computing“. Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559722.

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The major challenges in trapped-ion quantum computation are to scale up few-ion experiments to many qubits and to improve control techniques so that quantum logic gates can be carried out with higher fidelities. This thesis re- ports experimental progress in both of these areas. In the early part of the the- sis we describe the fabrication of a surface-electrode ion trap, the development of the apparatus and techniques required to operate it and the successful trap- ping of ⁴⁰Ca⁺ ions. Notably we developed methods to control the orientation of the principal axes and to minimise ion micromotion. We propose a repumping scheme that simplifies heating rate measurements for ions with low-lying D levels, and use it to characterise the electric field noise in the trap. Surface-electrode traps are important because they offer a route to dense integration of electronic and optical control elements using existing microfabrication technology. We explore this scaling route by testing a series of three traps that were microfabricated at Sandia National Laboratories. Investigations of micromotion and charging of the surface by laser beams were carried out and improvements to future traps are suggested. Using one of these traps we also investigated anomalous electrical noise from the electrode surfaces and discovered that it can be reduced by cleaning with a pulsed laser. A factor of two de- crease was observed; this represents the first in situ removal of this noise source, an important step towards higher gate fidelities. In the second half of the thesis we describe the design and construction of an experiment for the purpose of replacing laser-driven multi-qubit quantum logic gates with microwave-driven ones. We investigate magnetic-field-independent hyperfine qubits in ⁴⁰Ca⁺ as suitable qubits for this scheme. We make a design study of how best to integrate an ion trap with the microwave conductors required to implement the gate and propose a novel integrated resonant structure. The trap was fabricated and ions were successfully loaded. Single-qubit experiments show that the microwave fields above the trap are in excellent agreement with software simulations. There are good prospects for demonstrating a multi-qubit gate in the near future. We conclude by discussing the possibilities for larger-scale quantum computation by combining microfabricated traps and microwave control.

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42

Wang, Yicheng. „Slow collisions of hydride ion and deuteride ion with sodium, potassium and cesium“. W&M ScholarWorks, 1987. https://scholarworks.wm.edu/etd/1539623770.

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The cross sections of charge transfer and electron detachment in collisions of H$\sp{-}$ and D$\sp{-}$ with Na, K and Cs have been measured for collision energies ranging from 3 to 300 eV. Both charge transfer and electron detachment are significant electron-loss mechanisms for H$\sp{-}$(D$\sp{-}$); both processes exhibit velocity-dependent isotope effects for H$\sp{-}$ and D$\sp{-}$. $\sigma\sb{\rm cg}$(E) displays high energetic thresholds for Na and K (about 20 eV for H$\sp{-}$ + Na and 40 eV for H$\sp{-}$ + K) yet no obvious one for Cs. $\sigma\sb{\rm e}$(E) does not depend on the target as much as $\sigma\sb{\rm ct}$(E) and displays near zero-energy thresholds. The relative importance of charge transfer as an electron-loss mechanism decreases as the mass of the alkali-metal increases.

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43

McMahon, Matthew M. „Modeling Ion Acceleration Using LSP“. The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440426562.

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44

Mouncey, Simon Patrick. „Low energy ion-surface interactions“. Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333823.

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45

Gallagher, Richard Thomas. „Kinetics and equilibria of ion-molecule association reactions : studied using temperature variable high pressure ion sources“. Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/4160/.

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Interest in termolecular association reactions of the type shown below, stems from their importance in the chemistry of planetary atmospheres, gas-cooled nuclear reactors and gas-phase cluster ions. This study is concerned with evaluating the rate constants of such X+ + X + M ------> X2+ + M k3 (1) reactions as both a function of temperature and of the third body M. The values of the third order rate constant k3 are expressed conventionally in terms of k3 = CT-m where T is the temperature and C and m are constants characteristic of the reaction which depend also on the nature of M. Literature now shows a general measure of agreement on values of C and m in several studies for which X=M, however, inconsistent values have been reported on the M=He system. This thesis describes an investigation of the two systems X=N2, CO and M= the reactant or a rare gas. Experiments were conducted in a conventional high pressure ion source and a pulsed drift ion source fitted to an updated Kratos MS9 mass spectrometer. Results obtained for the one component studies show good agreement with other literature values for the temperature dependence, m. In general, for both N2 and CO systems, He was found to have the same efficiency as the parent molecule as a third body at 300K, but the temperature dependence of k3 is markedly lower. Ar was found to behave very similarly to the parent molecule in both systems. For the CO system, although good agreement is found for the temperature dependence result with literature, there is still an uncertainty of about a factor of 2 in the room temperature values of k3.

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46

Hashim, Hasnita. „Heavy ion transfer reactions“. Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306004.

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47

Bieber, David Justin. „Emission spectroscopy in the VUV and visible from highly charged ions in an electron beam ion trap“. Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267952.

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48

Windham, Gordon. „Spin dependence in heavy ion induced nuclear reactions“. Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/843452/.

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The interest of this work is to explore the spin dependent effects of projectile structure in nuclear heavy ion induced reactions. The projectiles are considered to consist of two clusters which remain inert, the intercluster wavefunctions are obtained by the use of the orthogonality condition model. Excitation to the low lying projectile states is included by the use of coupled channels calculations. The projectile excited states are included by allowing excitation in the inter cluster wavefunctions. Coupling to the excited states is performed by multipole terms arising from a single folding model, which is used consistently throughout the work. The effects of projectile excitation are considered in two areas, elastic and inelastic scattering, and transfer reactions. It is found that the inclusion of the projectile excited states has a very strong effect on the spin dependent elastic observables, in particular the vector analysing powers. In contrast to earlier analysis it is found that projectile excitation plays a dominant role in reproducing the experimentally observed vector analysing powers for the elastic scattering of 6Li from 16O and 28Si at 22.8 MeV. Projectile excitation is also seen to produce strong spin dependent effects in the elastic scattering of Li from 120Sn at 44 MeV and of 19Ffrom 28Si at 60 MeV. The inclusion of projectile excitation via CCBA calculations produces changes in the transfer cross section for the 28Si (19F, 16O)31P(1/2+ ,g.s.) reaction. The observed changes can be understood in terms of the effects of spin dependence in the reaction path. The inclusion of projectile excitation however does not significantly improve the quality of the agreement with experimental data.

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49

Forster, Christine. „Aspects of charge exchange in ion-atom collisions“. Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6189/.

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The straight line semi-classical Impact Parameter method has been modified for use with classical trajectories. Ion-atom collisions have been modelled using wavefunctions expanded in terms of atomic basis states which were centred on either the target or projectile ions. Total and differential charge exchange cross-sections are presented for (^4)He(^++) and (^4)He(^+) collisions within the centre of mass energy range 0.21 kev < E(_em) < 2.5 keV. Results using curved and straight line paths are compared with data from other authors. Significant trajectory effects were found at the lower energies in the range. The curved trajectory results were lower than those from the straight line model and also lower than previous calculations carried out. At higher energies in the range there was good agreement between straight line and curved trajectory models and previous work. Differential cross-sections were found to be sensitive to the trajectories employed, and comparisons have been made with previous work. Total, state specific and differential cross- sections for charge exchange are presented for Be(^++) and H collisions using a five state basis, within the centre of mass energy range 0.111 keV < E(_em) < 0.4444 keV. There was reasonable agreement between the straight line results and previous work. There were significant trajectory effects for all the final charge transfer states. Results are presented for low-energy collisions between positively charged muons and atomic hydrogen. An eight state basis has been used. Direct excitation cross sections for n = 2 atomic states and charge transfer cross sections to Is and n = 2 have been calculated. The effect on the cross sections of using different internuclear potentials has been examined. Trajectory effects were small for charge transfer to Is but were more pronounced in the direct excitation and charge exchange cross- sections to n = 2. These results have been compared to those obtained for curved trajectory H(^+) and H collisions at the same relative velocity, to assess the validity of velocity scaling. It was found that velocity scaling was reliable for charge transfer to Is and for total electron capture cross-sections. However, it was progressively inaccurate for direct excitation and for electron capture into excited states for µ(^+) impact energies of less than 300 eV. These results are discussed and suggestions for further work are made.

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50

Valerio, Peter Michael 1968. „Heavy quark production in heavy-ion collisions“. Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/288922.

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The results of the full next-to-leading-order calculation of open charm production cross section, via hard parton scattering, for both hadronic and heavy-ion collisions at RHIC and LHC energies are presented. In addition to the total cross section, the transverse momentum and rapidity distributions are included. An effective K-factor which encapsulates the next-to-leading-order corrections and the nuclear effects is presented. The open charm yield will be measured through the correlated dileptons produced when the charm decays. An important background comes from the decay of bottom quarks. Therefore, the open bottom yield from hard parton scatterings is presented. The first next-to-leading-order calculation of the thermal heavy quark production is presented, as well as the dimuon spectrum from both the thermal and the initial fusion charm and bottom production at RHIC energies.

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