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The Giant Pairing Vibration (GPV) is a correlated two-nucleon excitation mode in atomic nuclei predicted long time ago. It is expected to be excited in two-nucleon transfer reactions, similarly to the pairing vibrations feeding the ground states of even-even nuclei near shell-closure. Recent experiments have provided evidence for this mode in 14 C and 15 C nuclei populated via 12 C, 13 C( 18 O, 16 O) 14 C, 15 C two-neutron transfer reactions at 84 MeV beam energy. In the present paper, new data show the persistence of the same structures in the energy spectra of 14 C and 15 C populated by the same reactions at a higher bombarding energy of 275 MeV. The extracted centroid, width, spin-parity and transition probability fully agree with the previous observation thus giving a robust confirmation that the GPV mode is populated in such transfer reactions. [ABSTRACT FROM AUTHOR]

In this work we will present an overview of our global studies on continuum excitations induced by protons, for the weakly bound nuclei 6 Li , 7 Li and 9 Be , presenting strong clustering modes. Measurements are made in inverse kinematics and extensive simulations have been developed, to corroborate the analysis and interpretation of the results. The focus of the measurements is on the breakup reaction, but simultaneously this research is complemented by the study of all involved reaction channels, including elastic scattering. In this respect our theoretical interpretation in a Continuum Discretized Coupled Channel approach can be fully validated. Between our sound conclusions we can underline the following: the non reciprocity between the strengths of the breakup probability and the coupling to continuum; the experimental validation of a continuum discretization for three body Continuum Discretized Coupled Channel theories; and last but not least the unique possibility for deducing continuum decay rates of borromean nuclei in proton induced studies, by considering the kinematics of the target recoil. Other specific conclusions for each system will be discussed. [ABSTRACT FROM AUTHOR]

Gamma-ray and neutron spectra from the 18 O + 76 Se reaction at 15.3 MeV/u were measured with the EDEN array of liquid scintillators at the LNS. The results were compared to GEANT Hadrontherapy physics list simulations in order to assess the reliability of this model for the development of the NUMEN project. A good agreement with the shape of the experimental gamma-ray spectra and a reasonable agreement with the total count rates were obtained. The gamma spectra originated from the nuclear reactions were selected by time coincidence with the Superconducting Cyclotron radio-frequency reference signal. The random coincidence background rate was appropriately described only when the Faraday Cup, the material and geometry of the experimental hall and its contents were included in the simulation with sufficient detail. The information on the radiation spectra is important for the adequate development of the project of the detector arrays and electronic equipment for the advanced phase of NUMEN. Since orders of magnitude larger beam intensities are planned for this phase, the random coincidence rate is also of significant importance, particularly for the performance of the G-NUMEN gamma calorimeter array. [ABSTRACT FROM AUTHOR]

The Gamow–Teller strength distributions of 116 Sb and 122 Sb were measured with the 116 , 122 Sn (3 He , t) 116 , 122 Sb charge-exchange reactions at 140 MeV/u . The measurements were carried out at the Research Center for Nuclear Physics (RCNP) at Osaka University in Osaka, Japan using the Grand Raiden spectrometer. The data were analysed by Multipole-Decomposition Analysis (MDA). The Gamow–Teller strengths summed up to 28 MeV are (38 ± 7) % and (48 ± 6) % of the Ikeda sum rule for 116 Sb and 122 Sb , respectively, if the quasi-free scattering (QFS) contribution is not subtracted. These percentages are (29 ± 7) % and (35 ± 5) % , respectively, if the QFS contribution is maximally subtracted. These results were compared to those from previous measurements of the same isotopes, to recent measurements of 150 Pm , and to a Quasi-particle Random-Phase Approximation (QRPA) calculation with Quasi-Particle Vibration Coupling (QPVC). The data suggest that the true QFS contribution is small for 116 Sb , but are inconclusive about whether the QFS contribution is small or significant for 122 Sb . Therefore, these data may provide an interesting test for the general quenching phenomenon of the Gamow–Teller Resonance (GTR). However, more research to reveal the nature of the QFS contribution is still needed on both the experimental and the theoretical side. [ABSTRACT FROM AUTHOR]

Signatures of the population of the Giant Pairing Vibration (GPV), a correlated two-nucleon excitation across major shell expected to be populated in two-nucleon transfer reactions, have been observed for the first time in carbon isotopes. In the present paper, a review of the experimental methods and of the analysis leading to that observation is reported. A new case, with new experimental data, regarding the possible population of the GPV in another light nucleus, 11Be , by the same reaction, is introduced and discussed. [ABSTRACT FROM AUTHOR]

New data are presented for the Li(d, p)Li stripping reaction which, together with previously reported elastic scattering data taken in the same experiment, provide a coherent set. These data, plus existing measurements of the elastic scattering and stripping at 6MeV/u were analysed within the same coupled reaction channels scheme. Good descriptions of the stripping data to the 0.0MeV $ 2^+$ and 0.98MeV $ 1^+$ states of Li were obtained using a set of $ \langle $ ^8Li| ^7Li + n〉 overlaps taken from the literature, provided that the elastic scattering was also well described. Multi-step reaction paths made significant contributions to the description of the larger angle data. The asymptotic normalisation coefficients are compared with previous determinations. [ABSTRACT FROM AUTHOR]

A study of the continuum of C populated by the C(O, O)C reaction at 84 MeV incident energy has been performed. The ejectiles have been momentum analyzed at forward angles by the MAGNEX magnetic spectrometer. The energy spectra were obtained up to about 20 MeV excitation energy. The scattering of two neutrons independently removed from the projectile as it passes the target nucleus has been described by means of an optical potential with a semi-classical approximation for the relative motion. The calculations describe a significant part of the continuum observed in the energy spectra. In particular, a resonance of the residual nucleus dominates the region near the two-neutron emission threshold. [ABSTRACT FROM AUTHOR]

The focal plane detector of the MAGNEX large acceptance magnetic spectrometer is presented. It is based on a large low-pressure gas-filled tracker followed by a wall of silicon detectors to stop the particles. It has been designed for the stringent requirements from the ion optics and the foreseen use with heavy ions. The performances of the device are demonstrated using 4MeV/ u oxygen beams. The results of the tests are described and discussed in view of the application of the particle identification and trajectory reconstruction techniques to recover the kinematic properties of the reaction products. They demonstrate the suitability of such detector in a wide range of experiments where low-energy thresholds, large-accepted solid angle, precise momentum measurement and good particle identification are needed. [ABSTRACT FROM AUTHOR]

A general algorithm to extract the center of gravity of charge distributions generated in a patterned electrode is presented. The results obtained analyzing the data produced by the gas focal plane detector of the MAGNEX spectrometer are discussed. The algorithm is characterized by an unprecedented efficiency and accuracy when dealing with data with small signal-to-noise ratio. A clear recovery of the smooth position distribution from the quantized one obtained with standard algorithms is observed. The optimized algorithm is also able to naturally mitigate the cross-talk phenomena that are quite strong in this kind of compact detectors. [ABSTRACT FROM AUTHOR]

Experimental signatures of the dynamical correlations of a core with a single-particle neutron have been found in light neutron-rich nuclei investigated via the ( 7Li, 7Be) charge-exchange reactions at around 8MeV/u. Of particular astrophysical relevance are low-lying narrow resonances ( Γ ∼ 200keV FWHM) BSEC (Bound States Embedded in the Continuum). Because of their long lifetime BSEC states are likely to effect the capture rates in any scenario for nucleosynthesis in neutron-rich environment. They have been observed in the continuum of 11Be and 15C nuclei. A microscopic nuclear structure model based on QRPA theory, which takes into account Dynamical Core Polarisation (DCP) correlations, gives a suitable description of these resonances as well as single-particle states of the studied systems. In this context, high-energy narrow structures populated in nuclei having an integer number of α-particles plus three neutrons are good BSEC candidates and can be systematically investigated. [ABSTRACT FROM AUTHOR]

The Sn(p,t)Sn reaction was investigated at 35 MeV incident energy. The Sn excitation energy spectrum was reconstructed up to about 16 MeV. Preliminary results show the presence of a broad resonance at high excitation energy, compatible with the predicted population of the Giant Pairing Vibration (GPV). [ABSTRACT FROM AUTHOR]

The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the 40Ca(18O,18Ne)40Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article. [ABSTRACT FROM AUTHOR]

A study about the C(O, O)C two-neutron transfer reaction was performed at the Catania INFN-LNS laboratory at 84 MeV incident energy. The O ejectiles produced in the reactions were momentum analyzed and identified by the MAGNEX spectrometer. The Q-value spectrum of C shows several known bound and resonant states, in particular states with 2 p-4 h configuration respect to the O core. The integrated cross sections show an enhanced yield for the two-neutron transfer compared to the one-neutron transfer. These results are some experimental evidences that the (O, O) reaction proceeds mainly by the direct transfer of the neutron pair, instead of a second order process. [ABSTRACT FROM AUTHOR]