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You searched for subject:(Relativistic AND QED effects). Showing records 1 – 2 of 2 total matches.

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Universidade Nova

1. Machado, Jorge Felizardo Dias Cunha. High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions.

Degree: 2018, Universidade Nova

This work aims to provide insight on Bound-State Quantum-Electrodynamics (BSQED) by experimental fundamentals high-precision tests in exotic states of matter. Although BSQED and the relativistic many-body problem have been undergoing important progress, there are still some issues that require the increase of the number and accuracy of experimental fundamental tests. The first part of this work was done within the framework of the recent experiment in muonic helium ions ( 4He+ and 3He+) by the CREMA collaboration. This experiment, aims to provide new accurate values for the root-mean-square (rms) charge radii of the helium isotopes nuclei that are extracted from the measurement of the Lamb Shift, i.e., the measurement of the energy difference between the 2S 2P states. With the goal of measuring the transition energies with an accuracy of at least 50 ppm, the rms charge radii of the helium isotopes will be determined with an uncertainty of 0.03%, a factor of ten more precise than previous results obtained from electron scattering. The second part of this work aims the high-precision measurement of x-ray transitions in Highly-Charged Ions (HCI) using a Double-Crystal Spectrometer (DCS). These ions were produced in the plasma of an Electron-Cyclotron Resonance Ion Source (ECRIS). This kind of spectrometer is able not only to provide high-precision measurements but also reference-free measurements, without reference to any theoretical or experimental energy. Four transitions energies from n = 2!n = 1 have been measured in an argon plasma in three different charge states, He-, Be- and Li-like, with an accuracy of better than 3 ppm. Besides the energies, the natural width of each transition has also been experimentally obtained. The obtained results are in excellent agreement with the most recent theoretical calculations. Advisors/Committee Members: Santos, José, Indelicato, Paul.

Subjects/Keywords: Muonic atoms (ions); Lamb shift; Laser spectroscopy; Relativistic and QED effects; ECRIS; HCI; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

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

APA (6th Edition):

Machado, J. F. D. C. (2018). High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions. (Thesis). Universidade Nova. Retrieved from https://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/33710

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):

Machado, Jorge Felizardo Dias Cunha. “High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions.” 2018. Thesis, Universidade Nova. Accessed November 28, 2020. https://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/33710.

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

MLA Handbook (7th Edition):

Machado, Jorge Felizardo Dias Cunha. “High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions.” 2018. Web. 28 Nov 2020.

Vancouver:

Machado JFDC. High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions. [Internet] [Thesis]. Universidade Nova; 2018. [cited 2020 Nov 28]. Available from: https://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/33710.

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

Council of Science Editors:

Machado JFDC. High precision tests of QED Measurement of the alpha-particle and helion rms charge radius and the transition energies in highly-charged ions. [Thesis]. Universidade Nova; 2018. Available from: https://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/33710

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

2. Ghomeshi, Ramin Ghorbani. Pair Production and the Light-Front Vacuum.

Degree: Physics, 2013, Umeå University

Dominated by Heisenberg's uncertainty principle, vacuum is not quantum mechanically an empty void, i.e. virtual pairs of particles appear and disappear persistently. This nonlinearity subsequently provokes a number of phenomena which can only be practically observed by going to a high-intensity regime. Pair production beyond the so-called Sauter-Schwinger limit, which is roughly the field intensity threshold for pairs to show up copiously, is such a nonlinear vacuum phenomenon. From the viewpoint of Dirac's front form of Hamiltonian dynamics, however, vacuum turns out to be trivial. This triviality would suggest that Schwinger pair production is not possible. Of course, this is only up to zero modes. While the instant form of relativistic dynamics has already been at least theoretically well-played out, the way is still open for investigating the front form. The aim of this thesis is to explore the properties of such a contradictory aspect of quantum vacuum in two different forms of relativistic dynamics and hence to investigate the possibility of finding a way to resolve this ambiguity. This exercise is largely based on the application of field quantization to light-front dynamics. In this regard, some concepts within strong field theory and light-front quantization which are fundamental to our survey have been introduced, the order of magnitude of a few important quantum electrodynamical quantities have been fixed and the basic information on a small number of nonlinear vacuum phenomena has been identified. Light-front quantization of simple bosonic and fermionic systems, in particular, the light-front quantization of a fermion in a background electromagnetic field in (1+1) dimensions is given. The light-front vacuum appears to be trivial also in this particular case. Amongst all suggested methods to resolve the aforementioned ambiguity, the discrete light-cone quantization (DLCQ) method is applied to the Dirac equation in (1+1) dimensions. Furthermore, the Tomaras-Tsamis-Woodard (TTW) solution, which expresses a method to resolve the zero-mode issue, is also revisited. Finally, the path integral formulation of quantum mechanics is discussed and, as an alternative to TTW solution, it is proposed that the worldline approach in the light-front framework may shed light on different aspects of the TTW solution and give a clearer picture of the light-front vacuum and the pair production phenomenon on the light-front.

Subjects/Keywords: Strong-Field QED; Quantum Vacuum; Schwinger Pair Production Mechanism; Dirac Forms of Relativistic Dynamics; Light-front Quantization; Zero-mode Issue; DLCQ; Worldline Approach

…Strong-Field QED effects directly. 2 Introductory light-front field theory ith the… …Preface ince the invention of quantum electrodynamics (QED) as an effort to… …properties to investigate. QED has been extremely successful in explaining the physical phenomena… …relativity through QED and are included among the most well-verified predictions in physics (… …intensity regime so far, a few interesting ones in the low-energy high intensity regime of QED… 

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

APA (6th Edition):

Ghomeshi, R. G. (2013). Pair Production and the Light-Front Vacuum. (Thesis). Umeå University. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444

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):

Ghomeshi, Ramin Ghorbani. “Pair Production and the Light-Front Vacuum.” 2013. Thesis, Umeå University. Accessed November 28, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444.

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

MLA Handbook (7th Edition):

Ghomeshi, Ramin Ghorbani. “Pair Production and the Light-Front Vacuum.” 2013. Web. 28 Nov 2020.

Vancouver:

Ghomeshi RG. Pair Production and the Light-Front Vacuum. [Internet] [Thesis]. Umeå University; 2013. [cited 2020 Nov 28]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444.

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

Council of Science Editors:

Ghomeshi RG. Pair Production and the Light-Front Vacuum. [Thesis]. Umeå University; 2013. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444

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

.