Upgrade of the facility EXOTIC for the in-flight production of light Radioactive Ion Beams

The facility EXOTIC for the in-flight production of light weakly-bound Radioactive Ion Beams (RIBs) has been operating at INFN-LNL since 2004. RIBs are produced via two-body reactions induced by high intensity heavy-ion beams impinging on light gas targets and selected by means of a 30 -dipole bending magnet and a 1-m long Wien filter. The facility has been recently upgraded (i) by developing a cryogenic gas target, (ii) by replacing the power supplies of the middle lenses of the two quadrupole triplets, (iii) by installing two y-steerers and (iv) by placing two Parallel Plate Avalanche Counters upstream the secondary target to provide an event-by-event reconstruction of the position hit on the target. So far, RIBs of 7Be, 8B and 17F in the energy range 3-5 MeV/u have been produced with intensities about 3 7 105, 1.6 7 103 and 105 pps, respectively. Possible light RIBs (up to Z = 10) deliverable by the facility EXOTIC are also reviewed.\ua9 2013 Elsevier B.V. All rights reserved

States in 10Be populated in 6,7Li( 7Li,3,4He)10Be* reactions at 30 and 52 MeV

In this contribution, an analysis of an experiment with the 30 and 52 MeV 7Li beam and the 7LiF and 6LiF targets is given, emphasizing population of cluster states by triton transfer to 7Li. Results concerning both reactions are given and discussed. Aside from the dominant α + d structure in 6Li, a rather large overlap with 3He+t cluster configuration populates cluster states in 10Be by triton pick-up. A comparision with t pick-up from 7Li, resulting with detected α instead of 3He, with a considerably higher Q-value is given. A special attention was paid to analysing and compensating non-uniformity of thicknes of standard 50 μm thin silicon detectors used in the measurement. Rather than measuring their thickness independantly, a method was derived to calculate and compensate the thickness variation directly from the measured data

Li-alpha CLUSTER STATES IN B-12 USING Li-8 + He-4 INVERSE KINEMATICS ELASTIC SCATTERING

The Li-8 elastic scattering on a He-4 gas target was studied by means of the Inverse Kinematic Thick Target scattering method (TTIK) in order to investigate cluster configurations in excited states of B-12. A Li-8 beam, at E-c.m. = 10.2 MeV, was provided by the EXCYT radioactive beam facility at Catania. The beam, while passing through the helium thick target decreases its energy, thus exploring the Li-8-alpha center-of-mass energy range 2.7 MeV <= E-CM <= 9.6 MeV. Four Delta E-E silicon detector telescopes were used to detect the recoiling alpha particles. The time interval between the Li-8 passing through a on plate foil, placed at the entrance of the chamber, and the detection of the alpha particles by the Delta E detectors was also measured. The time measurement allows to disentangle elastic from reactions events, otherwise impossible from energy measurements. This can be considered as an improvement of the TTIK method. In this paper the used experimental technique and the obtained preliminary results will be presented

Fusion of 40Ca + 96Zr revisited: Transfer couplings and hindrance far below the barrier

The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections 432.4 \u3bcb, i.e. two orders of magnitude smaller than obtained in a previous experiment, where the subbarrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested relying on coupled-channels calculations. The purpose of this work has been to investigate the behavior of 40Ca + 96Zr fusion far below the barrier, thereby disentangling the elusive interplay of effects due to inelastic couplings, transfer couplings and, possibly, the appearance of the fusion hindrance. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrance shows up, and a comparison with 40Ca + 96 is illuminating in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q > 0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few \u3bcb. Locating the hindrance threshold, if any, in 40Ca + 96 would require challenging measurements of cross sections in the sub-\u3bcb range

Fusion hindrance and quadrupole collectivity in collisions of A 3c 50 nuclei: The case of 48Ti + 58Fe

The fusion excitation function of 48Ti + 58Fe has been measured in a wide energy range around the Coulomb barrier, covering 6 orders of magnitude of the cross sections. We present here the preliminary results of this experiment, and a full comparison with the near-by system 58Ni + 54Fe where evidence of fusion hindrance shows up at relatively high cross sections. The sub-barrier cross sections of 48Ti + 58Fe are much larger than those of 58Ni + 54Fe. Significant differences are also observed in the logarithmic derivatives, astro-physical S-factors and fusion barrier distributions. The influence of low-energy nuclear structure on all these trends is pointed out and commented. Coupled-channels calculations using a Woods-Saxon potential are able to reproduce the experimental results for 48Ti + 58Fe. The logarithmic derivative of the excitation function is very nicely fit, and no evidence of hindrance is observed down to around 1 \u3bcb. The fusion barrier distribution is rather wide, flat and structureless. It is only in qualitative agreement with the calculated distribution

Osmium Catalyst for the Borrowing Hydrogen Methodology: α-Alkylation of Arylacetonitriles and Methyl Ketones

Complex [Os(η6-p-cymene)(OH)(IPr)]OTf is an efficient catalyst precursor for the α-alkylation of arylacetonitriles and methyl ketones with alcohols, which works with turnover frequencies between 675 and 176 h–1 for nitriles and between 194 and 28 h–1 for ketones.Financial support from the Spanish MINECO [Projects CTQ2007-65218/BQU, CTQ2011-23459, CTQ2011-24165, and Consolider Ingenio 2010 (CSD2007-00006)], the DGA (E35), Generalitat Valenciana (PROMETEO/2009/039 and FEDER), and the European Social Fund (FSE) is acknowledged

Elastic scattering measurement for the system 17O + 58Ni at Coulomb barrier energies with silicon strip detectors exploiting ASIC electronics

The quasi elastic scattering of a 17O projectile from a 58Ni target has been studied at beam energies ranging from 42.5 to 55.0 MeV in 2.5 MeV steps. The total reaction cross sections were derived from the measured angular distributions by using an optical model fit within the coupled-channel code FRESCO. These cross sections are very similar to those measured for 17F (loosely bound by 0.6 MeV), mirror nucleus of 17O (tightly bound by 4.14 MeV). This outcome points out that, in this energy range, the small binding energy of the 17F valence proton has negligible influence onto the reactivity of such a loosely bound projectile, contrary to simple expectations, and to what observed for other loosely bound nuclei. The reaction dynamics seems to be influenced mainly by the Coulomb interaction which is similar for both mirror projectiles

Elastic scattering measurements for the system 7Be + 28Si at 17.2 MeV

Elastic scattering of 7Be+28Si was studied at several near barrier energies for probing the energy dependence of the optical potential. Our analysis at 17.2 MeV will be presented in this article and discussed, in terms of Continuum Coupled Channel Calculations (CDCC). This research is part of a long term plan concerning the energy dependence of the optical potential for weakly bound projectiles, at near barrier energies and for probing the potential threshold anomaly. The experiment took place at the EXOTIC facility - Laboratori Nationali di Legnaro (LNL), and refers to an angular distribution measurement, using the detector array EXPADES (Exotic Particle Detection System). Results at 9 MeV (Rutherford region) were also analyzed and were used for estimating the solid angle. Our analysis for other energies is under process

Study of the ⁶Li + p → \rightarrow ³He + ⁴He reaction in inverse kinematics

Angular distribution measurements were performed for the 6Li + p$\rightarrow$3He + 4He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8MeV/u. The detection of both recoils ( 3He and 4He over the laboratory angle range $\theta_{lab}=16^{\circ}$ to $34^{\circ}$ allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame ( $\theta_{c.m.}\sim 40^{\circ}$ to $140^{\circ}$. The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations

Scattering process for the system 7Be + 58Ni at 23.2 MeV beam energy

We measured for the first time the scattering process of 7Be nuclei from a 58Ni target at 23.2 MeV beam energy. The experiment was performed at the Laboratori Nazionali di Legnaro (LNL, Italy), where the 7Be Radioactive Ion Beam was in-flight produced with the facility EXOTIC. Charged reaction products were detected by means of the detector array DINEX, arranged in a cylindrical configuration around the target to ensure a polar angle coverage in the ranges \u3b8cm = 40\ub0-80\ub0 and 110\ub0-150\ub0. The scattering differential cross section was analyzed within the optical model formalism with the coupled-channel code FRESCO to extract the total reaction cross section. The result was compared with those obtained at lower beam energies in an earlier experiment performed at the University of Notre Dame (USA). At the present stage of our analysis, the two data sets were found to be not fully consistent each other