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Spectroscopy along Decay Chains of Element 114, Flerovium

Såmark-Roth, Anton LU (2021)
Abstract
This thesis focusses on a nuclear spectroscopy experiment conducted to study α-decay chains stemming from isotopes of flerovium (element Z = 114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions 48Ca + 242Pu and 48Ca + 244Pu provided a total of 29 flerovium decay chains. The measurement of two new types of even-even flerovium decay chains, starting from 286Fl and 288Fl, respectively, marked the discoveries of (i) an excited state in 282Cn and (ii) the isotope 280Ds. The observations gave further insights into the location of the coveted Island of Stability. With fifteen new decay chains starting... (More)
This thesis focusses on a nuclear spectroscopy experiment conducted to study α-decay chains stemming from isotopes of flerovium (element Z = 114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions 48Ca + 242Pu and 48Ca + 244Pu provided a total of 29 flerovium decay chains. The measurement of two new types of even-even flerovium decay chains, starting from 286Fl and 288Fl, respectively, marked the discoveries of (i) an excited state in 282Cn and (ii) the isotope 280Ds. The observations gave further insights into the location of the coveted Island of Stability. With fifteen new decay chains starting from 289Fl, the global data set was doubled for this isotope. Measured decay properties of these chains could provide new evidence of α-decay fine structure of odd-A superheavy nuclei, as predicted by theoretical calculations.

The papers included in this thesis cover various aspects of the flerovium experiment. The chapters complement the publications with background information and further details. They include an introduction to the research field of superheavy nuclei, detector development efforts, a description of the experimental setup as well as information on the data analysis and the simulations performed. The chapters also provide a summary of the main results and overarching outlook perspectives.

In Paper I, the processing of digitised silicon preamplifier signals were applied to short-lived α-decaying nuclei North-East of Pb. Further preparatory aspects of the experiment as well as applied spectroscopic tools, are covered in Paper III. The TASISpec decay station was upgraded with novel Compex germanium detectors, and their characterisation is given in Paper II. Paper V presents detailed information on the data analysis and statistical assessments applied to the flerovium decay chains. Highlights from the even-even Fl-decay chains are presented in Paper IV and as a press release in Paper VII. Finally, the main findings of the odd-A, 289Fl, decay chains form Paper VI. (Less)
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author
supervisor
opponent
  • Professor van Duppen, Piet, Department of Physics and Astronomy, KU Leuven, Belgium
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Superheavy elements, Flerovium, Nuclear Structure, Spectroscopy, Alpha decay, Electromagnetic decay, Spontaneous fission, Germanium detectors, Fysicumarkivet A:2021:Såmark-Roth
pages
227 pages
publisher
Lund University
defense location
Rydbergsalen, Fysikum, Lunds universitet Join via zoom: https://lu-se.zoom.us/j/67696180840?pwd=U3ZZUWFxTlYybElPU1lLYVdqMmtBZz09 passcode 2020
defense date
2021-06-18 13:15:00
ISBN
978-91-7895-835-1
978-91-7895-836-8
project
Spectroscopy along Decay Chains of Element 114, Flerovium
language
English
LU publication?
yes
id
ba14ef1a-87ba-462e-8026-1947b71dbef7
date added to LUP
2021-05-04 19:06:49
date last changed
2021-11-26 08:46:27
@phdthesis{ba14ef1a-87ba-462e-8026-1947b71dbef7,
  abstract     = {{This thesis focusses on a nuclear spectroscopy experiment conducted to study α-decay chains stemming from isotopes of flerovium (element Z = 114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions 48Ca + 242Pu and 48Ca + 244Pu provided a total of 29 flerovium decay chains. The measurement of two new types of even-even flerovium decay chains, starting from 286Fl and 288Fl, respectively, marked the discoveries of (i) an excited state in 282Cn and (ii) the isotope 280Ds. The observations gave further insights into the location of the coveted Island of Stability. With fifteen new decay chains starting from 289Fl, the global data set was doubled for this isotope. Measured decay properties of these chains could provide new evidence of α-decay fine structure of odd-A superheavy nuclei, as predicted by theoretical calculations.<br/><br/>The papers included in this thesis cover various aspects of the flerovium experiment. The chapters complement the publications with background information and further details. They include an introduction to the research field of superheavy nuclei, detector development efforts, a description of the experimental setup as well as information on the data analysis and the simulations performed. The chapters also provide a summary of the main results and overarching outlook perspectives.<br/><br/>In Paper I, the processing of digitised silicon preamplifier signals were applied to short-lived α-decaying nuclei North-East of Pb. Further preparatory aspects of the experiment as well as applied spectroscopic tools, are covered in Paper III. The TASISpec decay station was upgraded with novel Compex germanium detectors, and their characterisation is given in Paper II. Paper V presents detailed information on the data analysis and statistical assessments applied to the flerovium decay chains. Highlights from the even-even Fl-decay chains are presented in Paper IV and as a press release in Paper VII. Finally, the main findings of the odd-A, 289Fl, decay chains form Paper VI.}},
  author       = {{Såmark-Roth, Anton}},
  isbn         = {{978-91-7895-835-1}},
  keywords     = {{Superheavy elements; Flerovium; Nuclear Structure; Spectroscopy; Alpha decay; Electromagnetic decay; Spontaneous fission; Germanium detectors; Fysicumarkivet A:2021:Såmark-Roth}},
  language     = {{eng}},
  publisher    = {{Lund University}},
  school       = {{Lund University}},
  title        = {{Spectroscopy along Decay Chains of Element 114, Flerovium}},
  url          = {{https://lup.lub.lu.se/search/files/98045410/ASamarkRoth_PhDThesis.pdf}},
  year         = {{2021}},
}