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A recent experiment on 12C + 24Mg sub-barrier fusion was performed. Standard coupled-channels calculations clearly over-estimated the low energy cross sections and there was indication of a maximum of the astrophysical S factor vs energy. In the present work further measurements have been performed on the same system, and we extended the excitation function to lower energies down to σ ≃ 4 ÎĽ b, confirming the existence of the hindrance phenomenon. Additional energy points near the barrier were added as well. In agreement with the result of previous experiment, the hindrance energy threshold is observed to correspond to a remarkably large cross section. The present new data allow to better define the S -factor maximum, that is well fitted using two parametrizations of either the hindrance or the adiabatic model. We also performed coupled-channels calculations using a Woodsâ€"Saxon potential. Far below the barrier we observe that the coupling strengths decrease and tend to vanish, indeed one-dimensional tunnelling calculations well reproduce the excitation function. Further precise cross section measurements at slightly lower energies are needed to discriminate between the adiabatic and hindrance models. This would give a reliable guidance for the extrapolation to the systems of astrophysical interest, like 12C + 12C and 16O + 16O. [ABSTRACT FROM AUTHOR]

7Example of different TKEL conditions for 92 Mo using the shortest target-to-degrader distance. a Doppler-corrected spectrum without a TKEL condition. b Condition on the low part of the TKEL. c More restrictive condition on the low part of the TKEL. d Condition on the high part of the TKEL. 10Simulated Doppler corrected -ray spectra using the velocity from PRISMA (after the degrader) for 50 Ca showing the DSAM and RDDS techniques. The original article can be found online at https://doi.org/10.1140/epja/s10050-023-01027-2. [Extracted from the article]

The γ decay of the elusive narrow, near-threshold proton resonance in 11B was investigated at Laboratori Nazionali di Legnaro (INFN) in a particle- γ coincidence experiment, using the 6Li(6Li,p γ) fusion-evaporation reaction and the GALILEO-GALTRACE setup. No clear signature was found for a possible E1 decay to the 1/2 1 − , first-excited state of 11B, predicted by the Shell Model Embedded in the Continuum (SMEC) with a branching of 0.98 − 69 + 167 × 10 − 3 with respect to the dominant particle-decaying modes. The statistical analysis of the γ -ray spectrum provided an average upper limit of 2.37 × 10 − 3 for this γ -ray branching, with a global significance of 5 σ. On the other hand, by imposing a global confidence level of 3 σ , a significant excess of counts was observed for E = γ 9300 (20) keV, corresponding to a resonance energy of 11429(20) keV (namely 200(20) keV above the proton separation energy of 11B) and a γ -ray branching of 1.12 (35) × 10 − 3. This result is compatible with the SMEC calculations, potentially supporting the existence of a near-threshold proton resonance in 11B. [ABSTRACT FROM AUTHOR]

The magnetic dipole moments (μ) of 209Tl g (N = 128) and 207Tl m (N = 126) have been measured for the first time using the in-source laser resonance-ionization spectroscopy technique with the Laser Ion Source and Trap (LIST) at ISOLDE (CERN). The application of the LIST suppresses the usually overwhelming background of the isobaric francium isotopes and allows access to heavy thallium isotopes with A ⩾ 207. The self-consistent theory of finite Fermi systems based on the energy density functional by Fayans et al. well describes the N dependence of μ for 1 / 2 + thallium ground states, as well as μ for the 11 / 2 − isomeric states in europium, gold and thallium isotopes. The inclusion of particle-vibration coupling leads to a better agreement between the theory and experiment for μ (Tl g , I π = 1 / 2 +). It is shown that beyond mean-field contributions to μ cannot be neglected at least for thallium isotopes with I π = 1 / 2 +. [ABSTRACT FROM AUTHOR]

This work aims at presenting an alternative approach to the long standing problem of the B(E2) values in Sn isotopes in the vicinity of the N=Z double-magic nucleus 100Sn, until now predominantly measured with relativistic and intermediate-energy Coulomb excitation reactions. The direct measurement of the lifetime of low-lying excited states in odd-even Sn isotopes provides a new and precise guidance for the theoretical description of the nuclear structure in this region. Lifetime measurements have been performed in 105Sn for the first time with the coincidence Recoil Distance Doppler Shift technique. The lifetime results for the 7 / 2 1 + first excited state and the 11 / 2 1 + state, 2 + ( 104 Sn) ⊗ ν 1 g 7 / 2 multiplet member, are discussed in comparison with state-of-the-art shell model and mean field calculations, highlighting the crucial contribution of proton excitation across the core of 100Sn. The reduced transition probability B(E2) of the 11 / 2 1 + core-coupled state points out an enhanced staggering with respect to the B(E2; 2 1 + → 0 1 +) in the even-mass 104Sn and 106Sn isotopes. [ABSTRACT FROM AUTHOR]

The structure of 74Se at low energy was investigated via spectroscopy of internal conversion electrons at the INFN Legnaro National Laboratories (LNL). A set of internal K-conversion coefficients and monopole transition strengths was measured. A large ρ 2 (E 0 ; 2 2 + → 2 1 +) ⋅ 10 3 = 210 (130) value was deduced. This result, in addition to a low upper limit for the 0 3 + → 0 2 + electron transition, casts in doubt a simple interpretation of the 74Se low-lying structure, in particular the recently proposed spherical, vibrational character. New microscopic beyond-mean-field calculations generally agree with the experimental results and are capable of producing a large ρ 2 (E 0 ; 2 2 + → 2 1 +) value, even if still a factor ≈7 smaller than the experiment. Triaxiality and a complex shape-coexistence and mixing scenario seem responsible for this unexpected experimental result. [ABSTRACT FROM AUTHOR]

Background: 58Ni+64Ni is the first case where the influence of positive Q-value transfer channels on subbarrier fusion was evinced, in a very well known experiment by Beckerman et al. [Phys. Rev. Lett. 45, 1472 (1980)], by comparing with the two systems 58Ni+58Ni and 64Ni+64Ni. Subsequent measurements on 64Ni+64Ni showed that fusion hindrance is clearly present in this case. On the other hand, no indication of hindrance can be observed for 58Ni+64Ni down to the measured level of 0.1 mb. Purpose: Measuring deep subbarrier fusion cross sections for 58Ni+64Ni, where the influence of positive Q-value transfer channels on near-barrier fusion was evidenced previously, in order to investigate whether hindrance shows up. Methods: 167-200 MeV 58Ni beams from the XTU Tandem Accelerator of INFN-Laboratori Nazionali di Legnaro were used, bombarding thin metallic 64Ni(50 μg/cm²) enriched to 99.6% in mass 64. An electrostatic beam deflector allowed fusion evaporation residues to be detected at very forward angles in a detector telescope. Results: The excitation function has been extended by two orders of magnitude downward. The cross sections for 58Ni+64Ni continue decreasing very smoothly below the barrier, down to ≃1μb. The logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S factor is observed. Coupled-channel (CC) calculations using a Woods-Saxon potential and including inelastic excitations only underestimate the subbarrier cross sections by a large amount. Good agreement is found by adding two-nucleon transfer couplings to a schematical level. This behavior is quite different from what already observed for 64Ni+64Ni (no positive Q-value transfer channels available), where a clear low-energy maximum of the S factor appears, and whose excitation function is overestimated by a standard Woods-Saxon CC calculation. Conclusions: No hindrance effect is observed in 58Ni+64Ni in the measured energy range. This trend at deep subbarrier energies reinforces the recent suggestion that the availability of several states following transfer with Q>0 effectively counterbalances the Pauli repulsion that, in general, is predicted to reduce tunneling probability inside the Coulomb barrier. [ABSTRACT FROM AUTHOR]