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You searched for subject:(nucleus charge radius). Showing records 1 – 3 of 3 total matches.

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Johannes Gutenberg Universität Mainz

1. Zakova, Monika. Nuclear charge radii of light isotopes based on frequency comb measurements.

Degree: 2010, Johannes Gutenberg Universität Mainz

Optical frequency comb technology has been used in this work for the first time to investigate the nuclear structure of light radioactive isotopes. Therefore, three laser systems were stabilized with different techniques to accurately known optical frequencies and used in two specialized experiments. Absolute transition frequency measurements of lithium and beryllium isotopes were performed with accuracy on the order of 10^(−10). Such a high accuracy is required for the light elements since the nuclear volume effect has only a 10^(−9) contribution to the total transition frequency. For beryllium, the isotope shift was determined with an accuracy that is sufficient to extract information about the proton distribution inside the nucleus. A Doppler-free two-photon spectroscopy on the stable lithium isotopes (6,7)^Li was performed in order to determine the absolute frequency of the 2S → 3S transition. The achieved relative accuracy of 2×10^(−10) is improved by one order of magnitude compared to previous measurements. The results provide an opportunity to determine the nuclear charge radius of the stable and short-lived isotopes in a pure optical way but this requires an improvement of the theoretical calculations by two orders of magnitude. The second experiment presented here was performed at ISOLDE/CERN, where the absolute transition frequencies of the D1 and D2 lines in beryllium ions for the isotopes (7,9,10,11)^Be were measured with an accuracy of about 1 MHz. Therefore, an advanced collinear laser spectroscopy technique involving two counter-propagating frequency-stabilized laser beams with a known absolute frequency was developed. The extracted isotope shifts were combined with recent accurate mass shift calculations and the root-mean square nuclear charge radii of (7,10)^Be and the one-neutron halo nucleus 11^Be were determined. Obtained charge radii are decreasing from 7^Be to 10^Be and increasing again for 11^Be. While the monotone decrease can be explained by a nucleon clustering inside the nucleus, the pronounced increase between 10^Be and 11^Be can be interpreted as a combination of two contributions: the center-of-mass motion of the 10^Be core and a change of intrinsic structure of the core. To disentangle these two contributions, the results from nuclear reaction measurements were used and indicate that the center-of-mass motion is the dominant effect. Additionally, the splitting isotope shift, i.e. the difference in the isotope shifts between the D1 and D2 fine structure transitions, was determined. This shows a good consistency with the theoretical calculations and provides a valuable check of the beryllium experiment.

In dieser Arbeit wurde die optische Frequenzkamm-Technologie erstmals für Kernstrukturuntersuchungen von leichten radioaktiven Isotopen genutzt. Dafür wurden ingesamt drei Lasersysteme mit verschiedenen Methoden auf genau bekannte Frequenzen stabilisiert und diese dann bei zwei verschiedenen Experimenten eingesetzt. Messungen der absoluten Übergangsfrequenz in Lithium- und…

Subjects/Keywords: Halo-Kerne; Kernladungsradius; Laserspektroskopie; Frequenzkamm; halo-nucleus; nuclear charge radius; laser spectroscopy; Frequency comb; Physics

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

APA (6th Edition):

Zakova, M. (2010). Nuclear charge radii of light isotopes based on frequency comb measurements. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2010/2197/

Chicago Manual of Style (16th Edition):

Zakova, Monika. “Nuclear charge radii of light isotopes based on frequency comb measurements.” 2010. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed October 22, 2019. http://ubm.opus.hbz-nrw.de/volltexte/2010/2197/.

MLA Handbook (7th Edition):

Zakova, Monika. “Nuclear charge radii of light isotopes based on frequency comb measurements.” 2010. Web. 22 Oct 2019.

Vancouver:

Zakova M. Nuclear charge radii of light isotopes based on frequency comb measurements. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2010. [cited 2019 Oct 22]. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2010/2197/.

Council of Science Editors:

Zakova M. Nuclear charge radii of light isotopes based on frequency comb measurements. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2010. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2010/2197/


University of North Texas

2. 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 22, 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. 22 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 22]. 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


Johannes Gutenberg Universität Mainz

3. Sánchez Alarcón, Rodolfo Marcelo. Nuclear charge radius of the halo nucleus lithium-11.

Degree: 2006, Johannes Gutenberg Universität Mainz

Nuclear charge radii of short-lived isotopes can be probed in a nuclear-model independent way via isotope shift measurements. For this purpose a novel technique was developed at GSI, Darmstadt. It combines two-photon laser spectroscopy in the 2s-3s electronic transition of lithium, resonance ionization, and detection via quadrupole mass spectrometry. In this way an accuracy of 5e-5 which is necessary for the extraction of nuclear charge radii, and an overall detection efficiency of 1e-4 is reached. This allowed an isotope shift measurement of Li-11 for the first time at the TRIUMF facility in Vancouver. Additionally, uncertainties in the isotope shift for all other lithium isotopes were reduced by about a factor of four compared to previous measurements at GSI. Results were combined with recent theoretical mass shift calculations in three-electron systems and root-mean-square nuclear charge radii of all lithium isotopes, particulary of the two-neutron halo nucleus Li-11, were determined. Obtained charge radii decrease continuously from Li-6 to Li-9, while a strong increase between Li-9 and Li-11 is observed. This is compared to predictions of various nuclear models and it is found that a multicluster model gives the best overall agreement. Within this model, the increase in charge radius between Li-9 and Li-11is to a large extend caused by intrinsic excitation of the Li-9-like core while the neutron-halo correlation contributes only to a small extend.

Kernladungsradien kurzlebiger Isotope können nur durch die Messung der Isotopieverschiebung kernmodellunabhängig bestimmt werden. Dazu wurde an der Gesellschaft für Schwerionenforschung (GSI), Darmstadt eine neuartige Technik entwickelt. Diese kombiniert Zweiphotonen-Spektroskopie des 2s-3s-Übergangs mit Resonanz-Ionization und einem Nachweis durch Quadrupol-Massenspektrometrie. Auf diese Weise wird sowohl für eine Bestimmung der Kernladungsradien die notwendige Genauigkeit von 5e-5 als auch eine Effizienz von 1e-4 erreicht. Im Rahmen dieser Arbeit ist es mit der Methode gelungen am TRIUMF Institut (Vancouver) erstmals die Isotopieverschiebung des Isotops Li-11 zu messen. Darüberhinaus konnte die Genauigkeit für die anderen Lithiumisotope gegenüber früheren Messungen an der GSI um etwa einen Faktor vier verbessert werden. Die Resultate wurden mit den neuesten Berechnungen des Masseneffekts in Drei-Elektronen-Systemen kombiniert, um die mittleren quadratischen Ladungsradien aller Lithium-Isotope, insbesondere des Zwei-Neutronen-Halokerns Li-11, zu bestimmen. Die erhaltenen Radien nehmen von Li-6 bis Li-9 kontinuierlich ab, während der Radius von Li-9 zu Li-11 stark ansteigt. Dies wird mit verschiedenen Kernmodellen verglichen, von denen ein Multicluster-Modell die beste Übereinstimmung zeigt. In diesem Modell wird der Anstieg des Kernladungsradius zwischen Li-9 und Li-11 hauptsächlich durch intrinsische Anregungen des Li-9-Rumpfes verursacht, während die Korrelation der Halo Neutronen nur eine untergeordnete Rolle spielt.

Subjects/Keywords: Kernladungsradius, Laser Spektroskopie, Isotopieverschiebung, Halokern, Lithium; nuclear charge radius, laser spectroscopy, isotope shift, halo nucleus, lithium; Physics

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

APA (6th Edition):

Sánchez Alarcón, R. M. (2006). Nuclear charge radius of the halo nucleus lithium-11. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2006/1007/

Chicago Manual of Style (16th Edition):

Sánchez Alarcón, Rodolfo Marcelo. “Nuclear charge radius of the halo nucleus lithium-11.” 2006. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed October 22, 2019. http://ubm.opus.hbz-nrw.de/volltexte/2006/1007/.

MLA Handbook (7th Edition):

Sánchez Alarcón, Rodolfo Marcelo. “Nuclear charge radius of the halo nucleus lithium-11.” 2006. Web. 22 Oct 2019.

Vancouver:

Sánchez Alarcón RM. Nuclear charge radius of the halo nucleus lithium-11. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2006. [cited 2019 Oct 22]. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2006/1007/.

Council of Science Editors:

Sánchez Alarcón RM. Nuclear charge radius of the halo nucleus lithium-11. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2006. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2006/1007/

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