Isaak, J. ; Savran, D. ; Löher, B. ; Beck, T. ; Friman-Gayer, U. ; Krishichayan, ; Pietralla, N. ; Ponomarev, V. Yu. ; Scheck, M. ; Tornow, W. ; Werner, V. ; Zilges, A. ; Zweidinger, M. (2021)
Dipole response in Te-128,130 below the neutron threshold.
In: Physical Review C, 103 (4)
doi: 10.1103/PhysRevC.103.044317
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Background: Numerous studies of the ground-state decay of the pygmy dipole resonance (PDR) have been carried out in the past. However, data on the decay of the PDR to low-lying excited states is still very scarce due to limitations of the sensitivity to weak branching transitions of experimental setups.
Purpose: We present a detailed examination of the low-energy dipole response of 128Te and 130Te below their neutron separation thresholds of 8.8 and 8.5 MeV, respectively.
Methods: Photonuclear reactions with the subsequent γ-ray spectroscopy of the decay channel with continuous-energy bremsstrahlung at varying endpoint energies and linearly polarized quasimonochromatic γ-ray beams with energies ranging from 2.7 to 8.9 MeV in steps of roughly 250 keV were used for probing the decay behavior of the low-energy dipole response in 128Te and 130Te. In addition, (→γ,γ′γ'') reactions were used to study the population of low-lying states of 128Te.
Results: Spin-parity quantum numbers and reduced transition probabilities are determined for individual photo-excited states. The analysis of average decay properties for nuclear levels in narrow excitation-energy bins enable the extraction of photoabsorption cross sections, average branching ratios to the 2+1 state, and the distinction between E1 and M1 transitions to the ground state and to the 2+1 state accounting for resolved and unresolved transitions.
Conclusions: Above 5 MeV, the experimental data are in reasonable agreement to calculations within the quasiparticle phonon model. The major fraction of the ground-state decay channel is due to E1 transitions, while less than 5–10% stem from M1 transitions. Furthermore, first direct experimental evidence is provided that the population of the 2+1 state of 128Te via primary γ-ray transitions from excited states in the PDR region from 5 to 9 MeV is dominated by E1 transitions of 1− states.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2021 |
| Autor(en): | Isaak, J. ; Savran, D. ; Löher, B. ; Beck, T. ; Friman-Gayer, U. ; Krishichayan, ; Pietralla, N. ; Ponomarev, V. Yu. ; Scheck, M. ; Tornow, W. ; Werner, V. ; Zilges, A. ; Zweidinger, M. |
| Art des Eintrags: | Bibliographie |
| Titel: | Dipole response in Te-128,130 below the neutron threshold |
| Sprache: | Englisch |
| Publikationsjahr: | 22 April 2021 |
| Verlag: | APS |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Physical Review C |
| Jahrgang/Volume einer Zeitschrift: | 103 |
| (Heft-)Nummer: | 4 |
| DOI: | 10.1103/PhysRevC.103.044317 |
| Kurzbeschreibung (Abstract): | Background: Numerous studies of the ground-state decay of the pygmy dipole resonance (PDR) have been carried out in the past. However, data on the decay of the PDR to low-lying excited states is still very scarce due to limitations of the sensitivity to weak branching transitions of experimental setups. Purpose: We present a detailed examination of the low-energy dipole response of 128Te and 130Te below their neutron separation thresholds of 8.8 and 8.5 MeV, respectively. Methods: Photonuclear reactions with the subsequent γ-ray spectroscopy of the decay channel with continuous-energy bremsstrahlung at varying endpoint energies and linearly polarized quasimonochromatic γ-ray beams with energies ranging from 2.7 to 8.9 MeV in steps of roughly 250 keV were used for probing the decay behavior of the low-energy dipole response in 128Te and 130Te. In addition, (→γ,γ′γ'') reactions were used to study the population of low-lying states of 128Te. Results: Spin-parity quantum numbers and reduced transition probabilities are determined for individual photo-excited states. The analysis of average decay properties for nuclear levels in narrow excitation-energy bins enable the extraction of photoabsorption cross sections, average branching ratios to the 2+1 state, and the distinction between E1 and M1 transitions to the ground state and to the 2+1 state accounting for resolved and unresolved transitions. Conclusions: Above 5 MeV, the experimental data are in reasonable agreement to calculations within the quasiparticle phonon model. The major fraction of the ground-state decay channel is due to E1 transitions, while less than 5–10% stem from M1 transitions. Furthermore, first direct experimental evidence is provided that the population of the 2+1 state of 128Te via primary γ-ray transitions from excited states in the PDR region from 5 to 9 MeV is dominated by E1 transitions of 1− states. |
| Freie Schlagworte: | Deutsche Forschungsgemeinschaft, DFG, German Research Foundation, SFB 1245, Project-ID 279384907 LOEWE-Schwerpunkt "Nukleare Photonik" BMBF (Grant No. 05P18RDEN9) |
| Fachbereich(e)/-gebiet(e): | DFG-Sonderforschungsbereiche (inkl. Transregio) DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche > SFB 1245: Atomkerne von fundamentalen Wechselwirkungen zu Struktur und Sternen 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Kernphysik 05 Fachbereich Physik > Institut für Kernphysik > Experimentelle Kernphysik 05 Fachbereich Physik > Institut für Kernphysik > Experimentelle Kernphysik > Experimentelle Kernstruktur und S-DALINAC |
| Hinterlegungsdatum: | 15 Nov 2023 08:43 |
| Letzte Änderung: | 11 Jan 2024 07:42 |
| PPN: | 514614862 |
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