| 1. |
- Såmark-Roth, Anton, et al.
(författare)
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Flerovium spectroscopy – benchmarking nuclear theory at proton number Z = 114
- 2020. - 2
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the wake of the discovery of superheavy elements, nuclear spectroscopy experiments aim at providing anchor points at the uppermost end of the nuclear chart for nuclear structure theory, which otherwise had to solely rely on extrapolations. In two runs in 2019 and 2020, such a nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z = 114). One incentive to study flerovium isotopes is that many, but not all, nuclear structure models or model parametrizations favour Z = 114 as the next magic proton number beyond lead, Z = 82.
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| 2. |
- Såmark-Roth, Anton
(författare)
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Spectroscopy along Decay Chains of Element 114, Flerovium
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.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.
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| 3. |
- Såmark-Roth, Anton, et al.
(författare)
-
Spectroscopy along flerovium decay chains: Discovery of 280Ds and an excited state in 282Cn
- 2021
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Ingår i: Physical Review Letters. - 1079-7114. ; 126:3
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Tidskriftsartikel (refereegranskat)abstract
- A nuclear spectroscopy experiment was 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 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to 286Fl and 288Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α-particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely 282Cn. Spectroscopy of 288Fl decay chains fixed Qα=10.06(1) MeV. In one case, a Qα=9.46(1)-MeV decay from 284Cn into 280Ds was observed, with 280Ds fissioning after only 518 μs. The impact of these findings, aggregated with existing data on decay chains of 286,288Fl, on the size of an anticipated shell gap at proton number Z=114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.
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