Study of Li-10 via the Li-9(H-2, p) reaction at REX-ISOLDE

The Click to view the MathML source reaction has been investigated at 2.36 MeV/u at the REX-ISOLDE facility. In this Letter we focus on the Click to view the MathML source channel which potentially holds spectroscopic information on the unbound nucleus 10Li. The experimental excitation energy spectrum and angular distribution are compared with CCBA calculations. These calculations clearly support the existence of a low-lying (s) virtual state, with a (negative) scattering length of the order asnot, vert, similar1324 fm and a p1/2 resonance with an energy of Ersimilar, equals0.38 MeV and a width of Γsimilar, equals0.2 MeV

Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics

By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress. \ua9 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence

Transfer reactions in inverse kinematics at REX-ISOLDE

Research on the structure of exotic nuclei is one of the most intriguing topics in present day nuclear physics. With the use of facilities for isotope separation on-line, such as ISOLDE at CERN, short-lived isotopes can be studied experimentally. Since 2002, the REX-ISOLDE facility enables radioactive ions produced by ISOLDE to be post-accelerated, increasing the energy of the ions enough to do nuclear transfer reactions in inverse kinematics. In this thesis, transfer reactions are used to study the structure of neutron-rich lithium isotopes through a series of experiments at REX-ISOLDE. The first experiment used a 9Li beam at 2.36 MeV/u impinging on a deuterated polyethylene target to study 10Li, 9Li and 8Li. For the (d,p)-channel the resonance ground state and a first excited state are observed and the results agree with theoretical calculations. The elastic channel agrees with Optical Model, OM, calculations. For the (d,t)-channel the shape of the angular distribution agrees with Distorted Wave Born Approximation, DWBA, calculations but the absolute scale is not reproduced. Therefore, a benchmark experiment with an 8Li beam at 3.15 MeV/u on the same target was made to test the validity of the method. Using OM calculations with the same potentials as for the 9Li experiment, the data from the elastic channel and OM agree on an absolute scale. The (d,p)-channel is well described for small scattering angles using DWBA calculations; the agreement extends to even larger angles if coupled-channels are taken into account. The conclusion is that transfer reactions remain a viable tool for investigating nuclear structure. Beyond the need to improve experimental obstacles such as increasing the beam energy, the analysis highlights the need of careful modelling of the reaction mechanism to be able to describe the data. The obtained results give confidence to investigate even more exotic nuclei and also to search for resonance states in unbound nuclei. The general analysis and simulation programs developed will be applicable for future experiments

Transfer reactions in inverse kinematics at REX-ISOLDE

Research on the structure of exotic nuclei is one of the most intriguing topics in present day nuclear physics. With the use of facilities for isotope separation on-line, such as ISOLDE at CERN, short-lived isotopes can be studied experimentally. Since 2002, the REX-ISOLDE facility enables radioactive ions produced by ISOLDE to be post-accelerated, increasing the energy of the ions enough to do nuclear transfer reactions in inverse kinematics. In this thesis, transfer reactions are used to study the structure of neutron-rich lithium isotopes through a series of experiments at REX-ISOLDE. The first experiment used a 9Li beam at 2.36 MeV/u impinging on a deuterated polyethylene target to study 10Li, 9Li and 8Li. For the (d,p)-channel the resonance ground state and a first excited state are observed and the results agree with theoretical calculations. The elastic channel agrees with Optical Model, OM, calculations. For the (d,t)-channel the shape of the angular distribution agrees with Distorted Wave Born Approximation, DWBA, calculations but the absolute scale is not reproduced. Therefore, a benchmark experiment with an 8Li beam at 3.15 MeV/u on the same target was made to test the validity of the method. Using OM calculations with the same potentials as for the 9Li experiment, the data from the elastic channel and OM agree on an absolute scale. The (d,p)-channel is well described for small scattering angles using DWBA calculations; the agreement extends to even larger angles if coupled-channels are taken into account.The conclusion is that transfer reactions remain a viable tool for investigating nuclear structure. Beyond the need to improve experimental obstacles such as increasing the beam energy, the analysis highlights the need of careful modelling of the reaction mechanism to be able to describe the data. The obtained results give confidence to investigate even more exotic nuclei and also to search for resonance states in unbound nuclei. The general analysis and simulation programs developed will be applicable for future experiments

Ionization scheme development at the ISOLDE RILIS

The resonance ionization laser ion source (RILIS) of the ISOLDE on-line isotope separation facility is based on the method of laser step-wise resonance ionization of atoms in a hot metal cavity. The atomic selectivity of the RILIS complements the mass selection process of the ISOLDE separator magnets to provide beams of a chosen isotope with greatly reduced isobaric contamination. Using a system of dye lasers pumped by copper vapour lasers, ion beams of 24 elements have been generated at ISOLDE with ionization efficiencies in the range of 0.5-15%. As part of the ongoing RILIS development off-line resonance ionization spectroscopy studies carried out in 2003 and 2004 have determined the optimal three-step ionization schemes for scandium, antimony, dysprosium and yttrium

Recent developments in production of radioactive ion beams with the selective laser ion source at the on-line isotope separator ISOLDE

The production of radioactive ionization laser ion source (RILIS) of ISOLDE on-line isotope separation facility was investigated. The RILIS setup included three dye lasers and ionization schemes which employ three resonant transitions were also used. The RILIS efficiency could be reduced by nuclear effects such as hyperfine splitting and isotope shifts. The off-line resonance ionization spectroscopy determined optimal three-step ionization schemes for yttrium, scandium and antimony and antimony. The results show that best ionization schemes of Y provided gain factor of 15 with respect to surface ionization. (Edited abstract) 8 Refs

Kinematic identification of the t branch in the decay of 11Li

The -delayed 8 Li + t branch of the 11Li decay was identified via kinematical analysis of the charged particles observed in coincidence. The back-to-back events observed in a narrow angular acceptance were compared to a Monte Carlo simulation. The 8 Li + t sum energy spectrum was fitted assuming that the decay occurs through an intermediate state in 11Be . The resulting energy centroid and full-width half maximum for the intermediate state are 18.35(30)MeV and 1.5(4)MeV, respectively. The -delayed 8 Li + t branching ratio obtained from the coincidence spectrum, BR t = 0.93(8) 710-4 , is in agreement with previous measurements but more precise

The 8Li + 2H reaction studied in inverse kinematics at 3.15 MeV/nucleon using the REX-ISOLDE post-accelerator

The reaction 8Li + 2H has been studied in inverse kinematics at the incident energy of 3.15 MeV/nucleon, using the REX-ISOLDE post-accelerator. The reaction channels corresponding to (d,p), (d,d), and (d,t) reactions populating ground states and low-lying excited states in 7–9Li have been identified and the related angular distributions extracted and compared with coupled-channels, distorted-wave Born approximation (DWBA), and coupled-reaction-channels calculations. For the inelastic and (d,t) channels we find that higher order effects are very important and hence one needs to go beyond the simple DWBA to extract reliable structure information from these processes

The ⁸Li + ²H reaction studied in inverse kinematics at 3.15 MeV/nucleon using the REX-ISOLDE post-accelerator

The reaction 8Li + 2H has been studied in inverse kinematics at the incident energy of 3.15 MeV/nucleon, using the REX-ISOLDE post-accelerator. The reaction channels corresponding to (d,p), (d,d), and (d,t) reactions populating ground states and low-lying excited states in 7–9Li have been identified and the related angular distributions extracted and compared with coupled-channels, distorted-wave Born approximation (DWBA), and coupled-reaction-channels calculations. For the inelastic and (d,t) channels we find that higher order effects are very important and hence one needs to go beyond the simple DWBA to extract reliable structure information from these processes