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You searched for +publisher:"University of North Texas" +contributor:("Shiner, David C."). Showing records 1 – 3 of 3 total matches.

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University of North Texas

1. Hassan Rezaeian, Nima. A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium.

Degree: 2015, University of North Texas

We perform high precision measurements of an isotope shift between the two stable isotopes of helium. We use laser excitation of the 23 S1-23 P0 transition at 1083 nm in a metastable beam of 3He and 4He atoms. A newly developed tunable laser frequency selector along with our previous electro-optic frequency modulation technique provides extremely reliable, adaptable, and precise frequency and intensity control. The intensity control contributes negligibly to overall experimental uncertainty by stabilizing the intensity of the required sideband and eliminating the unwanted frequencies generated during the modulation of 1083 nm laser carrier frequency. The selection technique uses a MEMS based fiber switch and several temperature stabilized narrow band (~3 GHz) fiber gratings. A fiber based optical circulator and an inline fiber amplifier provide the desired isolation and the net gain for the selected frequency. Also rapid (~2 sec.) alternating measurements of the 23 S1-23 P0 interval for both species of helium is achieved with a custom fiber laser for simultaneous optical pumping. A servo-controlled retro-reflected laser beam eliminates residual Doppler effects during the isotope shift measurement. An improved detection design and software control makes negligible subtle potential biases in the data collection. With these advances, combined with new internal and external consistency checks, we are able to obtain results consistent with the best previous measurements, but with substantially improved precision. Our measurement of the 23 S1-23 P0 isotope shift between 3He and 4He is 31 097 535.2 (5) kHz. The most recent theoretic calculation combined with this measurement yields a new determination for nuclear size differences between 3He and 4He: ∆rc=0.292 6 (1)exp (8)th (52)exp fm, with a precision of less than a part in 〖10〗4 coming from the experimental uncertainty (first parenthesis), and a part in 〖10〗3 coming from theory. This value is consistent with electron scattering measurement, but a factor of 10 more precise. It is inconsistent (4 sigma) with a recent isotope shift measurement on another helium transition (21 S0-23 S1). Comparisons with ongoing muonic helium measurements may provide clues to the origin of what is currently called the proton puzzle: electronic and muonic measurements of the proton size do not agree. In the future, the experimental improvements described here can be used for higher precision tests of atomic theory and quantum electrodynamics, as well as an important atomic physics source of the fine structure constant. Advisors/Committee Members: Shiner, David C., Mueller, Dennis, Krokhin, Arkadii, Rostovtsev, Yuri.

Subjects/Keywords: isotope shift; nucleus charge radius; helium spectroscopy; fine/hyperfine measurements; precision measurements; Helium  – Isotopes.; Isotope shift.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hassan Rezaeian, N. (2015). A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc804828/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hassan Rezaeian, Nima. “A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium.” 2015. Thesis, University of North Texas. Accessed October 13, 2019. https://digital.library.unt.edu/ark:/67531/metadc804828/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hassan Rezaeian, Nima. “A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium.” 2015. Web. 13 Oct 2019.

Vancouver:

Hassan Rezaeian N. A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium. [Internet] [Thesis]. University of North Texas; 2015. [cited 2019 Oct 13]. Available from: https://digital.library.unt.edu/ark:/67531/metadc804828/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hassan Rezaeian N. A Precise Few-nucleon Size Difference by Isotope Shift Measurements of Helium. [Thesis]. University of North Texas; 2015. Available from: https://digital.library.unt.edu/ark:/67531/metadc804828/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of North Texas

2. Smiciklas, Marc. A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure.

Degree: 2010, University of North Texas

Spectroscopic measurements of the helium atom are performed to high precision using an atomic beam apparatus and electro-optic laser techniques. These measurements, in addition to serving as a test of helium theory, also provide a new determination of the fine structure constant α. An apparatus was designed and built to overcome limitations encountered in a previous experiment. Not only did this allow an improved level of precision but also enabled new consistency checks, including an extremely useful measurement in 3He. I discuss the details of the experimental setup along with the major changes and improvements. A new value for the J = 0 to 2 fine structure interval in the 23P state of 4He is measured to be 31 908 131.25(30) kHz. The 300 Hz precision of this result represents an improvement over previous results by more than a factor of three. Combined with the latest theoretical calculations, this yields a new determination of α with better than 5 ppb uncertainty, α-1 = 137.035 999 55(64). Advisors/Committee Members: Shiner, David C., Weathers, Duncan L., Mueller, Dennis W., Perez, Jose.

Subjects/Keywords: Helium.; precision measurements; fine structure; spectroscopy; Fine-structure constant.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Smiciklas, M. (2010). A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc31547/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Smiciklas, Marc. “A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure.” 2010. Thesis, University of North Texas. Accessed October 13, 2019. https://digital.library.unt.edu/ark:/67531/metadc31547/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Smiciklas, Marc. “A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure.” 2010. Web. 13 Oct 2019.

Vancouver:

Smiciklas M. A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure. [Internet] [Thesis]. University of North Texas; 2010. [cited 2019 Oct 13]. Available from: https://digital.library.unt.edu/ark:/67531/metadc31547/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Smiciklas M. A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure. [Thesis]. University of North Texas; 2010. Available from: https://digital.library.unt.edu/ark:/67531/metadc31547/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of North Texas

3. Correa, Jose Ricardo. Studies of Charged Particle Dynamics for Antihydrogen Synthesis.

Degree: 2014, University of North Texas

Synthesis and capture of antihydrogen in controlled laboratory conditions will enable precise studies of neutral antimatter. The work presented deals with some of the physics pertinent to manipulating charged antiparticles in order to create neutral antimatter, and may be applicable to other scenarios of plasma confinement and charged particle interaction. The topics covered include the electrostatic confinement of a reflecting ion beam and the transverse confinement of an ion beam in a purely electrostatic configuration; the charge sign effect on the Coulomb logarithm for a two component (e.g., antihydrogen) plasma in a Penning trap as well as the collisional scattering for binary Coulomb interactions that are cut off at a distance different than the Debye length; and the formation of magnetobound positronium and protonium. Advisors/Committee Members: Ordonez, Carlos A., Deering, William D., Shiner, David C., Weathers, Duncan L., Wurtele, Jonathan.

Subjects/Keywords: Charge particle; dynamics; antihydrogen; Coulomb; antimatter; positron; magnetic; CERN; Particles (Nuclear physics); Antimatter.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Correa, J. R. (2014). Studies of Charged Particle Dynamics for Antihydrogen Synthesis. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc699934/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Correa, Jose Ricardo. “Studies of Charged Particle Dynamics for Antihydrogen Synthesis.” 2014. Thesis, University of North Texas. Accessed October 13, 2019. https://digital.library.unt.edu/ark:/67531/metadc699934/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Correa, Jose Ricardo. “Studies of Charged Particle Dynamics for Antihydrogen Synthesis.” 2014. Web. 13 Oct 2019.

Vancouver:

Correa JR. Studies of Charged Particle Dynamics for Antihydrogen Synthesis. [Internet] [Thesis]. University of North Texas; 2014. [cited 2019 Oct 13]. Available from: https://digital.library.unt.edu/ark:/67531/metadc699934/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Correa JR. Studies of Charged Particle Dynamics for Antihydrogen Synthesis. [Thesis]. University of North Texas; 2014. Available from: https://digital.library.unt.edu/ark:/67531/metadc699934/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.