| 1. |
- Stryjczyk, M., et al.
(author)
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Decay studies of the long-lived states in Tl 186
- 2020
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In: Physical Review C. - 2469-9985. ; 102:2
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Journal article (peer-reviewed)abstract
- Decay spectroscopy of the long-lived states in Tl186 has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The α decay from the low-spin (2-) state in Tl186 was observed for the first time and a half-life of 3.4-0.4+0.5 s was determined. Based on the α-decay energy, the relative positions of the long-lived states were fixed, with the (2-) state as the ground state, the 7(+) state at 77(56) keV, and the 10(-) state at 451(56) keV. The level scheme of the internal decay of the Tl186(10(-)) state [T1/2=3.40(9) s], which was known to decay solely through emission of 374-keV γ-ray transition, was extended and a lower limit for the β-decay branching bβ>5.9(3)% was determined. The extracted retardation factors for the γ decay of the 10(-) state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the πd3/2 shell in the isomeric decay and significant structure differences between Tl184 and Tl186.
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| 2. |
- Kirsebom, O. S., et al.
(author)
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Measurement of the 2+→0+ ground-state transition in the β decay of F 20
- 2019
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In: Physical Review C. - 2469-9985. ; 100:6
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Journal article (peer-reviewed)abstract
- We report the first detection of the second-forbidden, nonunique, 2+→0+, ground-state transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities.
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| 3. |
- Távora, V.G., et al.
(author)
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Strong coupling effects on near-barrier 15C + 208Pb elastic scattering
- 2024
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In: Physics Letters B. - 0370-2693. ; 855
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Journal article (peer-reviewed)abstract
- The presence of a neutron halo in 15C has been demonstrated in several reaction experiments at intermediate energies. In the present study, the dynamical effects of this structure are observed for the first time at Coulomb barrier energies in the 15C + 208Pb quasi-elastic scattering at MeV, measured at the HIE-ISOLDE facility, CERN using the high-granularity detector array GLORIA. A combined continuum discretised coupled channels and coupled reaction channels calculation describes the data well and significant coupling effects due both to breakup and single-neutron stripping are identified.
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| 4. |
- Ovejas, J. D., et al.
(author)
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Halo effects in the low-energy scattering of 15 C with heavy targets
- 2020
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In: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 51:3, s. 731-736
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Journal article (peer-reviewed)abstract
- The neutron-rich carbon isotope 15C was postulated to be a halo nucleus (Sn = 1215 keV, S2n = 9395 keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a "pure" s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-Z 208Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations.
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| 5. |
- Ovejas, J. D., et al.
(author)
-
Study of the scattering of 15C at energies around the Coulomb barrier
- 2020
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1643:1
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Conference paper (peer-reviewed)abstract
- The neutron rich carbon isotope 15C is the only known case of an almost "pure"2s1/2 single-neutron halo ground state configuration. At collision energies around the Coulomb barrier the reaction dynamics is expected to be dominated by single neutron transfer and breakup. To investigate these effects, we have measured the scattering of 15C with a 208Pb target at 65 MeV at the HIE-ISOLDE facility in CERN (Geneva, Switzerland). The preliminary data demonstrates the presence of a strong long-range absorption pattern in the angular distribution of the elastic cross section. The results are discussed in the framework of Optical Model calculations.
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| 6. |
- Spartà, R., et al.
(author)
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8B reaction dynamics researched at HIE-ISOLDE
- 2024
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In: Nuovo Cimento della Societa Italiana di Fisica C. - 2037-4909 .- 1826-9885. ; 47:2
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Journal article (peer-reviewed)abstract
- For the first time a measurement of 8B + 64Zn reaction has been performed at HIE-ISOLDE at CERN at energies around the Coulomb barrier, to understand how the debated halo structure of the light nucleus can affect reaction dynamics.
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| 7. |
- Spartà, R., et al.
(author)
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Probing proton halo effects in the 8 B+ 64 Zn collision around the Coulomb barrier
- 2021
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 820
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Journal article (peer-reviewed)abstract
- Proton halo effects in the 8B+64Zn reaction at an energy around 1.5 times the Coulomb barrier have been studied at HIE-ISOLDE CERN using, for the first time, the only existing postaccelerated 8B beam. This, together with the use of a high granularity and large solid angle detection system, allowed for a careful mapping of the elastic angular distribution, especially in the Coulomb-nuclear interference region. Contrary to what is observed for the one-neutron halo nucleus 11Be on the same target in a similar energy range, the analysis of the elastic scattering angular distribution shows only a modest suppression of the Coulomb-nuclear interference peak, with no remarkable enhancement of the total reaction cross-section. Inclusive angular and energy distributions of 7Be produced in direct reaction processes have also been measured. The comparison of these data with the results of theoretical calculations for the elastic and non-elastic breakup contributions indicate that both processes are important. Overall, the experimental data suggest a 8B collision dynamics at the barrier very different from the one of neutron halo nuclei, showing only modest effects of coupling to continuum. This behaviour can be interpreted as due to the presence of the additional Coulomb interactions halo-core and halo-target together with the presence of the centrifugal barrier felt by the valence proton of 8B.
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| 8. |
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| 9. |
- Kundalia, K., et al.
(author)
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Study of elastic and inelastic scattering of 7Be + 12C at 35 MeV
- 2022
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In: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 833, s. 137294-137294
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Journal article (peer-reviewed)abstract
- The elastic and inelastic scattering of 7Be from 12C have been measured at an incident energy of 35 MeV. The inelastic scattering leading to the 4.439 MeV excited state of 12C has been measured for the first time. The experimental data cover an angular range of θcm = 15∘-120∘. Optical model analyses were carried out with Woods-Saxon and double-folding potential using the density dependent M3Y (DDM3Y) effective interaction. The microscopic analysis of the elastic data indicates breakup channel coupling effect. A coupled-channel analysis of the inelastic scattering, based on collective form factors, shows that mutual excitation of both 7Be and 12C is significantly smaller than the single excitation of 12C. The larger deformation length obtained from the DWBA analysis could be explained by including the excitation of 7Be in a coupled-channel analysis. The breakup cross section of 7Be is estimated to be less than 10% of the reaction cross section. The intrinsic deformation length obtained for the 12C⁎ (4.439 MeV) state is δ2 = 1.37 fm. The total reaction cross section deduced from the analysis agrees very well with Wong's calculations for similar weakly bound light nuclei on 12C target.
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| 10. |
- Ali, Sk M., et al.
(author)
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Study of the 7Be(d,3He)6Li* reaction at 5 MeV/u
- 2024
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In: Physics Letters B. - 0370-2693. ; 853
-
Journal article (peer-reviewed)abstract
- The measurement of the 7Be(d,3He)6Li* transfer cross section at 5 MeV/u is carried out. The population of the 2.186 MeV excited state of 6Li in this reaction channel is observed for the first time. The experimental angular distributions have been analyzed in the finite range DWBA and coupled-channel frameworks. The effect of the 7Be(d,3He)6Li reaction on both the 6Li and 7Li abundances are investigated at the relevant big-bang nucleosynthesis energies. The excitation function is calculated by TALYS and normalized to the experimental data. The S factor of the (d,3He) channel from the present work is about 50% lower than existing data at nearby energies. At big-bang energies, the S factor is about three orders of magnitude smaller than that of the (d,p) channel. The (d,3He) reaction rate is found to have a less than 0.1% effect on the 6,7Li abundances.
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