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We studied multinucleon transfer reactions in the 197Au+130Te system at Elab=1.07 GeV by employing the PRISMA magnetic spectrometer coupled to a coincident detector. For each light fragment we constructed, in coincidence, the distribution in mass of the heavy partner of the reaction. With a Monte Carlo method, starting from the binary character of the reaction, we simulated the de-excitation process of the produced heavy fragments to be able to understand their final mass distribution. The total cross sections for pure neutron transfer channels have also been extracted and compared with calculations performed with the grazing code. [ABSTRACT FROM AUTHOR]

Measurements of fusion excitation functions of 58Ni + 124Sn and 64Ni + 124Sn are extended towards lower energy to cross sections of 1 fib and are compared to detailed coupled-channels calculations. The calculations clearly show the importance of including transfer reactions in a coupled-channels treatment for such heavy systems. This result is different from the conclusion made in a previous article which claimed that the influence of transfer on fusion is not important for fusion reactions of Ni + Sn. In the energy region studied in this experiment no indication of fusion hindrance has been observed, which is consistent with a systematic study of this behavior. [ABSTRACT FROM AUTHOR]

Excited states in the Z = 19, N = 29 neutron-rich 48K isotope have been studied using deep-inelastic transfer reactions with a thick target at Gammasphere and with a thin target at the PRISMA-CLARA spectrometer. The lowest excited states were located; they involve a proton hole in the s1/2 or d3/2 orbital coupled to a p3/2 neutron. A new 7.1(5)-ns, 5+ isomer, the analog of the 7/2- isomer in 47K. was identified. Based on the observed y-decay pattern of the isomer a revised spin-parity assignment of 1- is proposed for the ground state of 48 K. [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]

The measurement of one-neutron stripping cross sections for the 89Y(6Li,5Li)90Y* reaction at 22 MeV and 34 MeV is reported, using both in-beam and off-beam γ-ray spectroscopy methods. Characteristic γ lines of 90Y are clearly identified by both the γ-γ and proton-γ coincidence methods. The obtained cross section of one-neutron stripping at 34 MeV is found to be much smaller than that at 22 MeV. The one-neutron stripping cross sections measured for this system have the same order of magnitude as the one measured for the same reaction for the 6Li+96Zr system at energies around the Coulomb barrier. Parameter-free coupled reaction channel calculations agree quite well with the experimental data. Theoretical study of the effect of the one-neutron transfer on the elastic total fusion cross section is performed. [ABSTRACT FROM AUTHOR]

Background: Near- and sub-barrier fusion of various Ca + Zr isotopic combinations have been widely investigated. A recent analysis of 40Ca+96Zr data has highlighted the importance of couplings to multiphonon excitations and to both neutron and proton transfer channels. Analogous studies of 40Ca+90Zr tend to exclude any role of transfer couplings. However, the lowest measured cross section for this system is rather high (840μb). A rather complete data set is available for 40Ca+94Zr, while no measurement of 40Ca+92Zr fusion has been performed in the past. Purpose: Our aim is to measure the full excitation function of 40Ca+92Zr near the barrier and to extend downward the existing data on 40Ca+90Zr, in order to estimate the transfer couplings that should be used in coupled-channels calculations of the fusion of these two systems and of 40Ca+94Zr. Methods: 40Ca beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used, bombarding thin metallic 90Zr (50μg/cm2) and 92ZrO2 targets (same thickness) enriched to 99.36% and 98.06% in masses 90 and 92, respectively. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ER) at very forward angles, and angular distributions of ER were measured. Results: The excitation function of 40Ca+92Zr has been measured down to the level of ~60μb. Coupled-channels (CC) calculations using a standard Woods-Saxon (WS) potential and following the line of a previous analysis of 40Ca+96Zr fusion data give a good account of the new data, as well as of the existing data for 40Ca+94Zr. The previous excitation function of 40Ca+90Zr has been extended down to 40μb. Conclusions: Transfer couplings play an important role in explaining the fusion data for 40Ca+92Zr and 40Ca+94Zr. The strength of the pair-transfer coupling is deduced by applying a simple recipe based on the value obtained for 40Ca+96Zr. The logarithmic slopes and the S factors for fusion are reproduced fairly well for all three systems by the CC calculations, and there are no indications of a fusion hindrance at the lowest energies. In contrast, the new data for 40Ca+90Zr indicate the onset of a fusion hindrance at the lowest energies. [ABSTRACT FROM AUTHOR]

The excited states of unstable ^{20}O were investigated via γ-ray spectroscopy following the ^{19}O(d,p)^{20}O reaction at 8  AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2_{2}^{+} and 3_{1}^{+} states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+} and 3_{1}^{+} states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.