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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Low-velocity matter wave source for atom interferometry produced by Zeeman-tuned laser cooling and magneto-optic trapping

Mayer, Shannon K. 22 January 1997 (has links)
A continuous, low-velocity, nearly monochromatic atomic beam is created using laser cooling and two-dimensional magneto-optic trapping. Rubidium atoms from an effusive oven are slowed and cooled using Zeeman-tuned slowing. The scattering force from a counter-propagating, frequency-stabilized diode laser beam is used to decelerate the thermal beam of atoms to a velocity of ~ 20 m/s. A spatially varying magnetic field is used to Zeeman shift the resonance frequency of the atom to compensate for the changing Doppler shift, thereby keeping the slowing atoms resonant with the fixed frequency laser. This slowing process also cools the beam of atoms to a temperature of a few Kelvin. The slow beam of atoms is loaded into a two-dimensional magneto-optic trap or atomic funnel. The atoms are trapped along the axis of the funnel and experience a molassestype damping force in all three spatial dimensions. By frequency shifting the laser beams used to make the trap, the atoms are ejected at a controllable velocity. The continuous matter-wave source has a controllable beam velocity in the range of 2 to 15 m/s, longitudinal and transverse temperatures of approximately 500 ��K, and a flux of 3.4 x10��� atoms/s. At 10 m/s, the de Broglie wavelength of the beam is 0.5 nm. The spatial profile of the atomic beam was characterized 30 cm from the exit of the atomic funnel using a surface ionization detector. The low-velocity atomic beam is an ideal source for atom interferometry and a variety of applications in the field of atom optics. / Graduation date: 1997
2

Laser pulse amplification through a laser-cooled active plasma

Ghneim, Said Nimr, 1953- January 1988 (has links)
Recent advances in experimental laser cooling have shown the possibility of stopping an atomic beam using the light pressure force of a counter-propagating laser wave. As an application to laser cooling, it is proposed to build a single frequency cesium laser that has a narrow linewidth. Laser cooling techniques are used to cool an atomic beam of cesium to an average velocity of 5 m/s, corresponding to a temperature of 0.2°K. Expressions of the basic forces that a laser wave exerts on atoms are derived according to a semi-classical approach. The experimental problems and methods of avoiding these problems are treated in detail. A computer Monte-Carlo simulation is used to discuss the feasibility of building the proposed laser. This simulation was done for an ensemble of 10,000 atoms of cesium, and it included the effects of the gravitational force and the related experimental variables. The possibility of building single frequency lasers that use a cooled medium of noble gases, and many other applications of laser cooling are briefly discussed at the end of this work.
3

A rubidium atomic funnel

Swanson, Thomas B. 11 July 1995 (has links)
A low velocity, low temperature beam of atoms is produced from a two-dimensional magneto-optic trap known as an atomic funnel. The funnel provides simultaneous spatial and velocity compression of atoms and will provide a source for a three-grating atomic interferometer. Rubidium atoms from an oven are slowed by chirped cooling and loaded into the trap. Atoms are ejected from the trap using frequency offsets in optical molasses. The resultant beam has a controllable velocity in the range of 3 to 10 m/s with temperatures of order 500 ��K. / Graduation date: 1996
4

Some investigations in atomic structure using the method of atomic beam resonance

Tinker, M. H. January 1967 (has links)
No description available.
5

Atomic beam polarized 3He+ ion source

Vyse, Robert Norman January 1970 (has links)
A beam of polarized ³He⁺ ions has been produced using atomic beam method techniques. This method has the attraction of being capable of producing an ion beam with polarizations up to 100%. The polarization of ³He beams presently produced by optical pumping techniques is of the order of 5%. The apparatus is composed of three main sections, the atomic beam source consisting of a supersonic nozzle cooled to liquid helium temperatures to produce a low velocity atomic beam, the tapered hexapole magnet to spatially separate the particles in the two magnetic spin substates, and the electron bombardment ionizer to produce ³He⁺ ions from the neutral ³He atomic beam. The low velocity beam is required because the nuclear magnetic moment of ³He is of the order of 1000 times smaller than the electronic magnetic moment used to separate beams in conventional Stern-Gerlach magnets and to achieve a high ionization efficiency. The measured intensity of the beam produced by the atomic beam source cooled to liquid helium temperature was 1 x 10¹⁸ atoms/sr-sec, the most probable velocity was 310 m/sec, and the velocity full width at half maximum was 50 m/sec. The beam flux through the ionizer increases by a factor of 1.3 when the hexapole field is turned on, in good agreement with the theoretically expected increase. This increase corresponds to a polarization of 65% of the atomic beam. A 12nA³He⁺ ion beam was obtained corresponding to an ionization efficiency of approximately 0.15%. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
6

Experimental and theoretical studies of the behaviour of an H-ion beam during injection and acceleration in the TRIUMF central region model cyclotron

Root, Laurence Wilbur January 1974 (has links)
A comparison is made between the experimental and theoretical behaviour of the H" beam in the TRIUMF central region cyclotron. The axial injection process and the first six accelerated turns are studied in detail. In order to optimize the cyclotron performance the phase space emittance of the beam at the injection line exit must be matched to the central region acceptances. To this end,a theoretical study was made of the ion optical properties of the injection elements: the magnet bore, the spiral electrostatic inflector, the electrostatic deflector and the first radio-frequency accelerating gap. In many cases these results were confirmed by experimental observations. It was also shown theoretically that by a suitable choice of the accelerating gap, under optimum conditions, 10% of the injected beam can be directed within the radial acceptance and 30% within the vertical acceptances. The effects of a chopper and buncher in the injection line were also measured. A minimum pulse length of approximately 2.5 nsec was obtained with a bunching factor of 3-0. To accelerate a beam to full radius, vertical steering had at first to be provided by means of asymmetrically-powered trim coils and electrostatic deflection plates for each turn. The steering required is known to be consistent with the effects of magnetic field asymmetries and dee misalignments measured later. The size and shape of the vertical beam envelopes were found to be consistent with theory. The vertical tune vz was estimated to be 0.17 ± 0.03 for 20 deg phase ions. This agreed with the predicted value of 0.17- The transition phase which separates the vertically-focused and defocused phases was estimated to be -3 ± 3 deg, while the predicted value was 0 deg. The radial beam diagnostic techniques used for determining proper centring and isochronous operating conditions are discussed. With these techniques it was possible to centre a 30 deg phase interval to within 0.15 in., which was the approximate uncertainty in our measurements. A simplified treatment of radia 1 - longitudinal coupling is given and used to explain qualitatively the behaviour of a small emittance beam. The effects of space charge on the first six accelerated turns are calculated. For a beam occupying a phase width of 30 deg, these effects are predicted to be negligible for average accelerated currents below 100 uA. The experimental observations made on high-current beams are described.; prior to the shutdown of the cyclotron beams of up to 1^0 uA average current were accelerated. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
7

Electron-enhanced etching of SI(100) by atomic and molecular hydrogen

Clemons, John L. 05 1900 (has links)
No description available.
8

Atomic beam studies hyperfine-structure separations in potassium-42, rubidium-84, and cesium-129 ; magnetic moment and hyperfine structure anomaly in potassium-42 /

Khan, Jhan M. January 1961 (has links)
Thesis (Ph.D.)--University of California, Berkeley, 1961. / "UC-34 Physics Distributions" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 85-87).
9

Investigation of atomic structure using the method of atomic beams

Bellany, Ian January 1966 (has links)
No description available.
10

Investigation of hyperfine structure using the method of atomic beams

Martin, N. J. January 1965 (has links)
No description available.

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