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Background: In our recent experiment, $^9$Be+p at 5.67A MeV, the breakup decay rates to the 3 configurations, $\alpha$+$\alpha$+n, $^8$Be$^*$+n and $^5$He+$^4$He of $^9$Be, were observed and quantified, in a full kinematics approach. Unfolding step by step the accessibility to the above configurations, it will require similar studies at lower and higher energies as well as the interpretation of the data in a theoretical framework. Purpose: Investigate the breakup decay rate of $^9$Be+p at 2.72A MeV, where the $\alpha$+$\alpha$+n configuration is mainly accessible. Compare and interpret data at 2.72A MeV and 5.67A MeV into a 4-body CDCC formalism; Point out and discuss couplings to continuum. Methods: Our experimental method includes an exclusive breakup measurement in a full kinematic approach of $^9$Be incident on a proton target at 2.72A MeV, together with elastic scattering and other reaction channels measurements under the same experimental conditions. The interpretation of the data at 2.72A MeV and 5.67A MeV is considered in a 4-body CDCC approach, using the Transformed Harmonic Oscillator method for the 3-body projectile. Results: An elastic scattering angular distribution at 2.72A MeV is measured, which compares very well with CDCC calculations, indicating a strong coupling to continuum. At the same energy, the measured breakup and total reaction cross sections present good agreement with the calculated values. Further on, the elastic scattering and breakup cross section data at 5.67A MeV are found in very good agreement with the CDCC calculations. The present results support further our 3-body model for the structure of $^9$Be, validating relevant radiative reaction rates obtained previously., Comment: 10 pages, 11 figures

In this work we investigate whether it is feasible with proton inelastic scattering in inverse kinematics to quantify breakup decay rates, by observing the proton recoil in a full kinematics approach. Taking as example the 2.43 MeV excited state of 9Be, we perform an exclusive breakup measurement of 9Be incident on a proton target at an energy of 51 MeV. Two of the three cluster constituents (α and α) as well as the proton target recoil are recorded in a triple coincidence mode. As in other methods we have determined relative α−α and α−n, Q-value and 9Be excitation spectra, energy spectra for all fragments observed and non observed, reconstructed in a full kinematics approach. Additionally to that, we have obtained and concentrated on energy spectra of the proton recoil. The signature of the 9Be configurations were identified in bi-dimensional ΔE−E spectra (proton contour) and decay rates were determined for all three configurations He5+α, Be8+n and α+α+n. Finally a breakup cross section was deduced as σbreak=(142±20)mb. We conclude that proton inelastic excitation to continuum of Borromean light nuclei in inverse kinematics, may provide the mean for probing in the proton recoil spectra the decay rates through all cluster configurations. This involves extensive simulations with the implementation of the experimental conditions and of calculations describing the physics in continuum. © 2021 Elsevier B.V.

The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical $r$-process in producing nuclei heavier than $A\sim190$. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in $^{207}$Hg have been probed using the neutron-adding ($d$,$p$) reaction in inverse kinematics. The radioactive beam of $^{206}$Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of $^{207}$Hg marks a first step in improving our understanding of the relevant structural properties of nuclei involved in a key part of the path of the $r$-process., Comment: 6 pages, 5 figures

The exclusive breakup of the Borromean nucleus Be9 incident on a proton target at 5.67 MeV/nucleon was studied with a triple coincidence requirement between the two breakup α fragments and the recoiling proton. The analysis was performed using an event-by-event code in a full kinematics approach, and Q-value spectra, relative spectra, and energy spectra of all reaction products were determined. Clear signatures of the three breakup modes: α+α+n, Be8+n, and He5+He4 were observed in the recoiling proton spectra and the rates of these modes were quantified. © 2020 American Physical Society.

The breakup of Be-9 is studied via an inelastic scattering experiment on a proton target at 5.6 A MeV in inverse kinematics. Two of the three cluster constituents (alpha and alpha) as well as the proton target recoil were recorded in a triple coincidence mode allowing a full kinematics approach analysis. In this respect relative alpha - alpha and alpha - n, Q-value and Be-9 excitation spectra, energy spectra for all fragments as well as the energy spectrum of the recoil proton were reconstructed. A clear signature of the two breakup sequential modes (He-5 + He-4 and Be-8 + n) was identified via the recoiling proton reconstructed spectra together with the direct breakup decay. A strong He-5+He-4 mode was observed compatible with previous beta decay experiments.

The beta decay of 31Ar, produced by fragmentation of a 36Ar beam at 880 MeV/nucleon, was investigated. Identified ions of 31Ar were stopped in a gaseous time projection chamber with optical readout allowing to record decay events with emission of protons. In addition to \b{eta}-delayed emission of one and two protons we have clearly observed the beta-delayed three-proton branch. The branching ratio for this channel in 31Ar is found to be 0.07(2)%., 5 pages, 3 figures, submitted to Physical Rev. C

The inclusive breakup for the 11Li+208Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of 9Li following the 11Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the 11Li continuum at low excitation energy.

Recent results on the reaction dynamics induced by light radioactive ion beams at Coulomb barrier energies are reviewed. As a general feature, the exotic structure and the weak binding energy of most of these projectiles enhance the reaction probability rather than the fusion cross section, as originally expected. The quest has now moved toward understanding which direct reaction mechanism originates the enhancement. Experimental data showed that n-halo and p-halo nuclei are characterized by a different behavior. Transfer processes enhance the reaction probability for n-halo nuclei, such as 6;8He, while for p-halo nuclei, such as 8B, the breakup channel seems to be mainly responsible for the enhancement.

In this paper details of the experimental procedure and data analysis of the collision of 11Be+64Zn around the Coulomb barrier are described and discussed in the framework of different theoretical approaches. In a previous work [A. Di Pietro et al., Phys. Rev. Lett. 105, 022701 (2010).], the elastic scattering angular distribution of the collisions 9,10Be+64Zn as well as the angular distribution for the quasielastic scattering and transfer/breakup cross sections for the 11Be+64Zn reaction were briefly reported. The suppression of the quasielastic angular distribution in the Coulomb-nuclear interference angular region observed in the collision of the 11Be halo nucleus with respect to the other two beryllium isotopes was interpreted as being caused by a long-range absorption owing to the long decay length of the 11Be wave function. In this paper, new continuum-discretized coupledchannel calculations of the 11Be+64Zn reaction are reported in the attempt to interpret the effect of coupling with the breakup channels on the measured cross sections. The calculations show that the observed suppression of the Coulomb-nuclear interference peak is caused by a combined effect of Coulomb and nuclear couplings to the breakup channels. ispartof: Physical Review C, Nuclear Physics vol:85 issue:1 status: published

A powerful method of investigating proton-unbound nuclear states by tracking their decay products in flight is discussed in detail. To verify the method, four known levels in 15 F , 16 Ne , and 19 Na were investigated by measuring the angular correlations between protons and the respective heavy-ion fragments stemming from the precursor decays in flight. The parent nuclei of interest were produced in nuclear reactions of one-neutron removal from 17 Ne and 20 Mg projectiles at energies of 410–450 A MeV. The trajectories of the respective decay products, 14 O + p + p and 18 Ne + p + p, were measured by applying a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of the fragments, which provided information on energies and widths of the parent states. In addition for reproducing properties of known states, evidence for hitherto unknown excited states in 15 F and 16 Ne was found. This tracking technique has an advantage in studies of exotic nuclei beyond the proton drip line measuring the resonance energies and widths with a high precision although by using low-intensity beams and very thick targets.

A powerful method of investigating proton-unbound nuclear states by tracking their decay products in flight is discussed in detail. To verify the method, four known levels in 15F, 16Ne, and 19Na were investigated by measuring the angular correlations between protons and the respective heavy-ion fragments stemming from the precursor decays in flight. The parent nuclei of interest were produced in nuclear reactions of one-neutron removal from 17Ne and 20Mg projectiles at energies of 410–450 A MeV. The trajectories of the respective decay products, 14O + p + p and 18Ne + p + p, were measured by applying a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of the fragments, which provided information on energies and widths of the parent states. In addition for reproducing properties of known states, evidence for hitherto unknown excited states in 15F and 16Ne was found. This tracking technique has an advantage in studies of exotic nuclei beyond the proton drip line measuring the resonance energies and widths with a high precision although by using low-intensity beams and very thick targets.

Proton-proton correlations were observed for the two-proton decays of the ground states of $^{19}$Mg and $^{16}$Ne. The trajectories of the respective decay products, $^{17}$Ne+p+p and $^{14}$O+p+p, were measured by using a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of fragments projected on planes transverse to the precursor momenta. The measured three-particle correlations reflect a genuine three-body decay mechanism and allowed us to obtain spectroscopic information on the precursors with valence protons in the $sd$ shell., Comment: 5 pages 6 figures

4 pages, 2 figures, 1 table.-- El pdf del artículo es la versión post-print., Dipole polarizability refers to the effect of the excitation to negative parity states through the electric dipole interaction. In nuclear reactions induced by stable beams, dipole polarizability does not play a major role. For nuclei close to the drip lines where the separation energies of neutrons or protons are small, a substantial part of the dipole strength function occurs at low excitation energies. We propose to investigate this effect by measuring elastic scattering and break-up of Li-11 at energies below the Coulomb barrier.

International audience; The proton-rich, unbound nucleus 11N has been studied using the technique of elastic resonance scattering in inverse geometry. The spins and parities of the three lowest resonance levels have been determined as 1/2+, 1/2− and 5/2+, resulting from the orbitals 1s1/2, 0p1/2 and 0d5/2, respectively. This level ordering is the same as the one found in the mirror nucleus of 11N, namely the one-neutron halo nucleus 11Be. Especially, the in 11Be well known level inversion, where the ground state is a 1/2+ intruder state below the from a naive shell model expected ground state 1/2−, is also found in 11N.

The breakup of 9Be is studied via an inelastic scattering experiment on a proton target at 5.6 A MeV in inverse kinematics. Two of the three cluster constituents (α and α) as well as the proton target recoil were recorded in a triple coincidence mode allowing a full kinematics approach analysis. In this respect relative α - α and α - n, Q-value and 9Be excitation spectra, energy spectra for all fragments as well as the energy spectrum of the recoil proton were reconstructed. A clear signature of the two breakup sequential modes (5He + 4He and 8Be + n) was identified via the recoiling proton reconstructed spectra together with the direct breakup decay. A strong 5He + 4He mode was observed compatible with previous beta decay experiments.