Heavy-ion Transfer Reactions Research Articles

Population of heavy neutron-rich nuclei in multinucleon transfer reactions

Selected results recently obtained in studies of heavy ion transfer reactions at energies close to the Coulomb barrier are presented. In particular, the production of neutron-rich heavy nuclei via multinucleon transfer processes in 206Pb+118Sn, 197Au+130Te, and 94Rb+208Pb is discussed.

Nucleon-nucleon correlation studies in heavy-ion transfer reactions

We present some of the recent experimental results in heavy-ion transfer reactions obtained with the large solid angle magnetic spectrometer PRISMA at energies close to the Coulomb barrier. We focus on a series of experiments that have been carried out to study the nucleon-nucleon correlations for closed shell and superfluid systems. They are discussed together with the newest results concerning the proton transfer channels above and below the Coulomb barrier. The second set of the experiments was performed to study the production mechanism of heavy neutron-rich nuclei and the related effects of secondary processes.

Recent studies of heavy ion transfer reactions using large solid angle spectrometers

We present selected results recently obtained in the study of heavy ion transfer reactions at energies close to the Coulomb barrier by employing the large solid angle magnetic spectrometer PRISMA. We discuss the production of neutron-rich heavy nuclei via multinucleon transfer processes and the related effects of secondary processes, in particular nucleon evaporation, studied in a high resolution kinematic coincidence experiment. We also present the recent results in the studies of neutron-neutron correlations for closed shell and superfluid systems.

Fusion and the Discovery of Isotopes

Heavy-ion fusion-evaporation has been the most productive method to form and identify new isotopes. Of the presently known over 3200 isotopes, almost 25% were discovered with heavy-ion induced reactions. Since the development of the first heavy-ion beam at Berkeley in 1950 most of the nuclides on the neutron-deficient side of the line of stability and all isotopes of the superheavy elements were discovered utilizing fusion reactions. In addition, some isotopes were first produced in heavy-ion transfer, charge-exchange, incomplete fusion or deep inelastic reactions. The discovery of isotopes relies on new advances in accelerator and detector technology. The continuous development of pioneering and innovative separation and detection techniques have pushed the limit towards ‒ and in many cases beyond ‒ the proton-dripline. A review of the discovery of neutron-deficient and super-heavy nuclides in heavy-ion induced reactions as well as an outlook for the discovery potential in the future is presented.

Nuclear Data Sheets for A = 41

Available information pertaining to the nuclear structure of all nuclei with mass numbers A=41 ranging from Al (Z=13) to Ti (Z=22) are presented. The experimental reaction and decay data are evaluated and any inconsistencies or discrepancies are noted. The adopted values for various level properties (such as the spin, parity and and halflife) and gamma properties (energy, intensity and multipole character) are given.Since the prior evaluation several new measurements have expanded our knowledge of A=41 nuclides. The half-life of the ground state of 41Si has been determined and a single excited state identified. Excited levels in 41P have been observed for the first time. In 41Cl, seven new excited states have been identified in deep inelastic and heavy ion transfer reactions. Half-lifes for four states in 41Ar have been updated and additional levels with gammas have been included from a new measurement using the multiple ion transfer reaction. In 41Ca via charge-exchange reaction measurements, several new excited states were observed. A number of new resonances in 41K have been identified via the (p,γ) reaction.There remains a significant discrepancy in the half-life of the first excited state (980 keV) in 41K, with measurements differing by more than an order of magnitude. Transfer reactions suggest that this M1 transition should be l-forbidden, however, several measurements yield a lifetime which suggests a sizable M1 strength. Further measurements to resolve the current conflicts would be beneficial.

Probing nucleon-nucleon correlations in heavy-ion transfer reactions

The γ-particle coincident measurements, performed by coupling of the PRISMA spectrometer to the large γ arrays (CLARA and AGATA), demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynamics. By using the unique PRISMA performance in terms of both resolution and efficiency, measurements at very low bombarding energies have been performed. Via transfer of nucleon pairs, valuable information on the component responsible for particle correlations has been derived.

Probing nucleon-nucleon correlations in heavy-ion transfer reactions

The γ -particle coincident measurements, performed by coupling of the PRISMA spectrometer to the large γ arrays (CLARA and AGATA), demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynamics. By using the unique PRISMA performance in terms of both resolution and efficiency, measurements at very low bombarding energies have been performed. Via transfer of nucleon pairs, valuable information on the component responsible for particle correlations has been derived.

Probing nucleon-nucleon correlations via heavy ion transfer reactions

The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers, coupled to large arrays. The recent results of -particle coincident measurements demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynam- ics. Via transfer of pairs, valuable information on the component responsible for particle correlations has been derived.

Probing nucleon-nucleon correlations via heavy ion transfer reactions

Probing nucleon-nucleon correlations via heavy ion transfer reactions

Structure of chlorine isotopes populated by heavy ion transfer reactions

Neutron-rich chlorine isotopes were populated in the Ar-40 + Pb-208 multiple transfer reaction via the -1p channels in a fragment-gamma coincident measurement employing the Prisma-Clara setup. New gamma transitions have been identified and, together with already available data, level schemes have been revised and compared with the results of large-scale sd-pf shell-model calculations. The evolution of the energy splitting between the s(1/2) and d(3/2) orbitals and the increased mixing of different proton configurations in the populated Cl isotopic chain have been deduced by inspecting the shell-model wave functions.

Gamma spectroscopy as a tool to search for particle–phonon coupled states: status and perspectives

The coupling mechanism between a particle and a phonon is a basic phenomenon in fermonic many-body interacting systems, which is here experimentally investigated in neutron-rich nuclei by in-beam γ-spectroscopy. In particular, nuclei around doubly magic 48Ca are studied by the heavy-ion transfer reaction 48Ca on 64Ni at 282 MeV, with the PRISMA-CLARA setup at Legnaro Laboratory of INFN. Angular distributions, polarizations and lifetimes analyses are used to probe spin and parities of several excited states, shading lights on their configuration. In the one-neutron transfer channels (49Ca and 47Ca), states arising from coupling of a single particle to the 3− phonon of 48Ca are identified, showing the robustness of nuclear collectivity in rather light systems. Preliminary results on 65Cu are also discussed with regard to the coupling of the p3/2 unpaired proton to the 3− phonon of 64Ni. Experimental results are interpreted using a phenomenological weak-coupling model, which is also used to provide predictions on exotic systems around the doubly magic 132Sn core.

Heavy-ion transfer reactions studied at large internuclear distances with the PRISMA magnetic spectrometer

We performed a study of the behaviour of the main transfer channels in the 116Sn+60Ni system at different bombarding energies from above to well below the Coulomb barrier. The experiment has been done in inverse kinematics, detecting the lighter target-like ions with the magnetic spectrometer PRISMA at very forward angles. Good mass, nuclear charge and kinetic energy resolutions have been achieved. Sufficient statistics has been accumulated to extract angular distributions for different bombarding energies, requiring a study of the response function of the spectrometer. The comparison between the data and microscopic calculations for the present case and for the previously measured 96Zr+40Ca system, namely superfluid and near closed shells nuclei, should significantly improve our understanding of nucleon-nucleon correlation properties in multinucleon transfer processes.

Heavy ion transfer reactions: ongoing and future experiments performed with large acceptance magnetic spectrometers

The advent of the last generation large solid angle magnetic spectrometers, coupled to large gamma arrays, allowed to perform gamma-particle coincidences for nuclei moderately far from stability, especially in the neutron-rich region. Via transfer of multiple pairs valuable information on nucleon-nucleon correlations can also be derived, especially from measurements performed below the Coulomb barrier. There is growing interest in the study of the properties of the heavy binary partner, in the Pb and in the actinides regions, crucial also for astrophysics.

Heavy-ion transfer reactions at large internuclear distances using the PRISMA magnetic spectrometer

We measured excitation functions for the main transfer channels in the 116Sn+60Ni reaction at different bombarding energies from above to well below the Coulomb barrier. The experiment has been performed in inverse kinematics, detecting the lighter (target-like) ions with the magnetic spectrometer PRISMA at very forward angles. Good mass, nuclear charge and kinetic energy resolutions have been achieved. The comparison between the data and microscopic calculations for the present case and for the previously measured 96Zr+40Ca system, namely superfluid and near closed shells nuclei, should significantly improve our understanding of nucleon-nucleon correlation properties in multinucleon transfer processes.

Candidate superdeformed band in28Si

Recent antisymmetrized molecular dynamics (AMD) calculations for ${}^{28}$Si suggest the presence of a superdeformed (SD) band with a dominant ${}^{24}\mathrm{Mg}+\ensuremath{\alpha}$ clustering for its configuration, with firm predictions for its location and associated moment of inertia. This motivates a review of the experimental results reported in the literature with a particular focus on ${}^{24}$Mg($\ensuremath{\alpha}$,$\ensuremath{\gamma}$) studies, as well as on $\ensuremath{\alpha}$-like heavy-ion transfer reactions such as ${}^{12}$C(${}^{20}$Ne,$\ensuremath{\alpha}$)${}^{28}$Si. Combining this information for the first time leads to a set of candidate SD states whose properties point to their $\ensuremath{\alpha}$-cluster structure and strong associated deformation. Analysis of data from Gammasphere allows the electromagnetic decay of these candidate states to be probed and reveals further supporting evidence for such a structure. This paper appraises this body of information and finds the evidence for an SD band is strong.

Complete γ-spectroscopy of n-rich nuclei around 48Ca with Multi-Nucleon Transfer reactions

The gamma decay of neutron-rich nuclei around 48Ca was measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using the multi-nucleon transfer reaction 48Ca on 64Ni at 282 MeV. Evidence is found for a large spin alignment which allows to use angular distributions and polarizations of gamma rays to firmly establish, for the first time, spin and parities of several excited states. In the one neutron transfer channels, 49Ca and 47Ca, states arising by coupling a single particle to the 3− phonon of 48Ca are observed, showing the robustness of nuclear collectivity in rather light systems. The work demonstrates the feasibility of complete in-beam γ-spectroscopy with heavy-ion transfer reactions and provides a method that can be further exploited in the future with heavy targets and radioactive beams.

Complete γ-spectroscopy of neutron-rich nuclei around 48Ca by Heavy-Ion Transfer reactions

The gamma decay of neutron-rich nuclei around 48Ca was measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using the heavy-ion transfer reaction 48Ca on 64Ni at ~6MeV/A. The analysis shows the feasibility to perform complete in-beam γ-spectroscopy with heavy-ion transfer reactions (in terms of angular distributions, polarizations of the γ rays and lifetimes of the nuclear states), providing a method that can be further exploited in the future with heavy targets and radioactive beams. In the one neutron transfer channels, 49Ca and 47Ca, states arising by coupling a single particle to the 3 phonon of 48Ca are observed, showing the robustness of nuclear collectivity in rather light systems.

γspectroscopy of calcium nuclei around doubly magic48Ca using heavy-ion transfer reactions

The γ decays of neutron-rich Ca isotopes around 48Ca were measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using the heavy-ion transfer reactions 48Ca on 64Ni and 48Ca on 208Pb at ≈6 MeV/A. The work shows the feasibility to perform full in-beam γ spectroscopy with heavy-ion transfer reactions (in terms of angular distributions, polarizations, and lifetimes analysis), providing a method that can be further exploited in the future with heavy targets and radioactive beams. For the one-neutron transfer channels, 49Ca and 47Ca, shell-model and particle-vibration coupling calculations are used to understand the nature of the states. In particular, in both nuclei evidence is found for particle-vibration coupled states based on the 3− phonon of 48Ca. In the two-neutron transfer channels, 46Ca and 50Ca, the experimental data are in global agreement with predictions based on full fp shell-model calculations.20 MoreReceived 9 December 2011DOI:https://doi.org/10.1103/PhysRevC.85.044301©2012 American Physical Society

Probing the nature of particle–core couplings in 49Ca with γ spectroscopy and heavy-ion transfer reactions

Neutron rich nuclei around 48Ca have been measured with the CLARA–PRISMA setup, making use of 48Ca on 64Ni binary reactions, at 5.9 MeV/A. Angular distributions of γ rays give evidence, in several transfer channels, for a large spin alignment (≈70%) perpendicular to the reaction plane, making it possible to firmly establish spin and parities of the excited states. In the case of 49Ca, states arising from different types of particle–core couplings are, for the first time, unambiguously identified on basis of angular distribution, polarization and lifetime measurements. Shell model and particle–vibration coupling calculations are used to pin down the nature of the states. Evidence is found for the presence, in the same excitation energy region, of two types of coupled states, i.e. single particle coupled to either 48Ca or 50Ca simple configurations, and particle–vibration coupled states based on the 3− phonon of 48Ca.

Heavy ion transfer reactions: Status and perspectives

With the large solid angle magnetic spectrometer (PRISMA) coupled to the γ-array (CLARA), extensive investigations of nuclear structure and reaction dynamics have been carried out. In the present paper aspects of these studies will be presented, focussing more closely on the reaction mechanism, in particular on the properties of quasielastic and deep inelastic processes and on measurements at energies far below the Coulomb barrier.