Papst, Oliver (2024)
Exploration of Nuclear-Structure Effects on Averaged Decay Quantities in the Quasicontinuum.
Technische Universität
doi: 10.26083/tuprints-00011437
Ph.D. Thesis, Primary publication, Publisher's Version
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Exploration of Nuclear-Structure Effects on Averaged Decay Quantities in the Quasicontinuum | ||||
Language: | English | ||||
Referees: | Pietralla, Prof. Dr. Norbert ; Isaak, Dr. Johann | ||||
Date: | 29 July 2024 | ||||
Place of Publication: | Darmstadt | ||||
Collation: | xx, 176 Seiten | ||||
Date of oral examination: | 15 July 2024 | ||||
DOI: | 10.26083/tuprints-00011437 | ||||
Abstract: | In this work, the decay behavior of dipole strength of ⁹⁶Mo and ¹⁵⁰Nd after excitation with high-energy photons was investigated. For this purpose, multiple experiments at the γ³ setup and clover array setup at the High-Intensity γ-ray Source (HIγS) at Duke University and at the Darmstadt High-Intensity Photon Setup (DHIPS) of the superconducting Darmstadt electron linear accelerator (S-DALINAC) at Technische Universität Darmstadt were performed. For the ¹⁵⁰Nd experiment at HIγS, the laser-Compton backscattering photon beam was operated in a new high-resolution mode, with an energy resolution of ΔE/E ≈ 2 %. The high energy resolution allowed, for the first time, the spectral separation of different decay components into the ground state band for a heavy deformed nucleus. Between 4 MeV and 7 MeV, an almost constant average branching ratio of 0.481(71) between the decay to the 2⁺₁ state and the ground state was observed. By introducing an internal fluctuation ratio s, the statistical distribution of partial transition widths was deduced. The observations are consistent with χ²-distributed transition widths with degree of freedom ν = 1.82(10), and inconsistent with the Porter-Thomas distribution ν = 1. Additionally, in combination with the DHIPS experiment, properties of individual states and the photon-scattering cross section were determined. For the ⁹⁶Mo experiment, utilizing γγ-coincidence measurements in combination with a linearly polarized quasi-monochromatic photon beam, the photon strength functions (PSFs) were determined that are built on top of excited 2⁺ states, which were then combined into a single downward PSF. The general shape and slope of the determined PSF agree very well with experiments using complementary probes, however, it is much smoother and exhibits fewer fluctuations in comparison to the literature values. This deviation indicates a possible violation of the Brink-Axel hypothesis for the studied energy range. |
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Uncontrolled Keywords: | physics, nuclear physics, nuclear photonics, photon strength function, angular distributions, nuclear resonance fluorescence, γγ coincidences, γ spectroscopy, photo response, pygmy dipole resonance, Brink-Axel hypothesis, Mo-96, Nd-150, cross sections, branching ratios, average branching ratios, level energies, angular momentum quantum numbers, parity quantum numbers, data acquisition system, statistical model, Porter-Thomas distribution, energy-integrated cross sections, elastic cross sections | ||||
Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-114379 | ||||
Classification DDC: | 500 Science and mathematics > 530 Physics | ||||
Divisions: | 05 Department of Physics > Institute of Nuclear Physics > Experimentelle Kernphysik > Experimentelle Kernstruktur und S-DALINAC | ||||
TU-Projects: | DFG|SFB1245|B02 Neumann-Cosel SF DFG|GRK2128|TP Pietralla |
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Date Deposited: | 29 Jul 2024 12:13 | ||||
Last Modified: | 30 Jul 2024 13:31 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/11437 | ||||
PPN: | 520201647 | ||||
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