Reactions induced by 11Be beam at Rex-Isolde

The collision induced by the three Beryllium isotopes, 9,10,11Be, on a 64Zn target were investigated at Ec.m. ≈ 1.4 the Coulomb barrier. The experiments with the radioactive 10,11Be beams were performed at the Rex-Isolde facility at CERN. In the case of 9,10Be, elastic scattering angular distributions were measured whereas, in the 11Be case, the quasielastic scattering angular distribution was obtained. A strong damping of the quasielastic cross-section was observed in the 11Be case, in the angular range around the Coulomb-nuclear interference peak. In this latter case a large total-reaction cross-section is found. Such a cross-section is more than a factor of two larger than the ones extracted in the reactions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the 11Be case could be attributed to transfer and/or break-up event

Elastic scattering of Beryllium isotopes near the Coulomb barrier

In this contribution, results of experiments performed with the three Beryllium isotopes 9,10,11Be on a medium mass 64Zn target, at a center of mass energy of≈1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the 9,10Be reactions. In the 11Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulombnuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the 11Be case could be attributed to transfer and/or break-up events

Pulse shape discrimination of charged particles with a silicon strip detector

Abstract A simple and effective pulse shape discrimination technique is applied to a silicon strip detector array. Excellent charge identification from H up to the Ni projectile has been obtained and isotope separation up to N has also been observed. The method we systematically studied is essentially based on a suitable setting of the constant fraction discriminators, and its main advantage is that no additional electronic modules are needed compared to the ones used in the standard TOF technique

Ground-state proton decay of 69Br and implications for the rp-process 68Se waiting-point

The first direct measurement of the proton separation energy, Sp, for the proton-unbound nucleus 69Br is reported. Of interest is the exponential dependence of the 2p-capture rate on Sp which can bypass the 68Se waiting-point in the astrophysical rp process. An analysis of the observed proton decay spectrum is given in terms of the 69Se mirror nucleus and the influence of Sp is explored within the context of a single-zone X-ray burst model.Comment: 6 pages, 6 figures, INPC 2010 conference proceeding

Three-α particle correlations in quasi-projectile decay in 12C + 24Mg collisions at 35AMeV

Two and multi particle correlations have been studied in peripheral 12C+24Mg collisions at 35AMeV with CHIMERA 4π multi detector, in order to explore resonances produced in light nuclei. Correlations techniques have become a tool to explore nuclear structure properties but also to evaluate the competition between simultaneous and sequential channels in decay of light isotopes. The exploration of features such as branching ratios with respect to different decay channels (sequential vs. simultaneous) could provide information on in-medium effects on nuclear structure properties, an important perspective for research on the nuclear interaction. The performed experiment is preliminary to further studies to be performed by coupling of CHIMERA to FARCOS (Femtoscope ARray for COrrelations and Spectroscopy, FARCOS TDR available at https://drive.google.com/file/d/0B5CgGWz8LpOOc3pGTWdOcDBoWFE) array devoted to measurements of two and multi particle correlations with high energy and angular resolutions

Freeze-out configuration properties in the 197Au + 197Au reaction at 23 AMeV

Data from the experiment on the 197Au + 197Au reaction at 23 AMeV are analyzed with an aim to find signatures of exotic nuclear configurations such as toroid-shaped objects. The experimental data are compared with predictions of the ETNA code dedicated to look for such configurations and with the QMD model. A novel criterion of selecting events possibly resulting from the formation of exotic freeze-out configurations, "the efficiency factor", is tested. Comparison between experimental data and model predictions may indicate for the formation of flat/toroidal nuclear systems

Experimental study of the collision 11Be + 64Zn around the Coulomb barrier

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, 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 coupled-channel 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.INFN y Ministerio de Ciencia e Innovación (España) FPA2009-07653 FPA2009-07387 FPA2010-17142Comisión Europea 50606

Correlations between isospin dynamics and Intermediate Mass Fragments emission time scales: a probe for the symmetry energy in asymmetric nuclear matter

We show new data from the $^{64}$Ni+$^{124}$Sn and $^{58}$Ni+$^{112}$Sn reactions studied in direct kinematics with the CHIMERA detector at INFN-LNS and compared with the reverse kinematics reactions at the same incident beam energy (35 A MeV). Analyzing the data with the method of relative velocity correlations, fragments coming from statistical decay of an excited projectile-like (PLF) or target-like (TLF) fragments are discriminated from the ones coming from dynamical emission in the early stages of the reaction. By comparing data of the reverse kinematics experiment with a stochastic mean field (SMF) + GEMINI calculations our results show that observables from neck fragmentation mechanism add valuable constraints on the density dependence of symmetry energy. An indication is found for a moderately stiff symmetry energy potential term of EOS.Comment: Talk given by E. De Filippo at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Elastic Scattering for the 11Be+64Zn System Close to the Coulomb Barrier

The quasi-elastic scattering angular distribution of the collision 11Be + 64Zn was measured and compared with the elastic scattering angular distribution for its core, the 10Be nucleus on the same target. Optical model and continuum-discretized coupled-channel calculations of the 11Be+64Zn reaction were performed in order to interpret the effect of coupling with the break-up channels on the measured cross-sections

Decrease in n-acetylaspartate following concussion may be coupled to decrease in creatine

Objectives: To assess the time course changes in brain N-acetylaspartate (NAA) and creatine (Cr) in athletes who suffered a sport-related concussion. Participants: Eleven non-consecutive concussed athletes and 11 sex and age-matched control volunteers. Main outcome measures: At 3, 15, 30 and 45 days post-injury, athletes were examined by proton Magnetic Resonance Spectroscopy (1H-MRS) for the determination of NAA,(Cr) and choline (Cho). 1H-MRS data recorded in the control group were used for comparison. Results: Compared to controls (2.18 ± 0.19), athletes showed an NAA/Cr increase at 3 (2.71 ± 0.16; p < 0.01) and 15 days (2.54 ± 0.21; p < 0.01), followed by a decrease and subsequent normalization at 30 (1.95 ± 0.16, p < 0.05) and 45 days(2.17 ± 0.20; p <0.05) post-concussion. NAA/Cho decreased at 3, 15 and 30 days post-injury (p < 0.01 compared to controls), with no differences from controls at 45 days post-concussion. Significant increase in the Cho/Cr after 3 (+33%, p < 0.01) and 15 (+31.5%, p < 0.01) days post-injury was observed, whilst no differences compared to controls were recorded at 30 and 45 days post-impact. Conclusions: This cohort of athletes indicates that concussion may cause concomitant decrease in cerebral NAA and Cr. This occurrence provokes longer time of metabolism normalization, as well as longer resolution time of concussion-associated clinical symptoms