A. Trifirò - Academia.edu (original) (raw)

Papers by A. Trifirò

Journal of Physics: Conference Series, May 1, 2018

International Conference on Recent Trends in Nuclear Physics-2012, 2013

ABSTRACT The de-excitation of medium mass nuclei 118,134Ba produced in fusion process of 78,86Kr ... more ABSTRACT The de-excitation of medium mass nuclei 118,134Ba produced in fusion process of 78,86Kr on 40,48Ca targets at 10 AMeV is studied, in order to investigate the isospin dependence of the decay modes; the neutron enrichment of the compound nuclei is in fact expected to play an important role on the emission mechanisms, providing crucial information on fundamental nuclear quantities such as level density, fission barrier, viscosity and symmetry energy. The experiment was performed at INFN-LNS with the 4π multidetector for charged particles CHIMERA, used for the first time in this low energy regime, thanks to a suitable Pulse Shape Discrimination method for charge identification applied to the silicon detectors. Preliminary results show a different isotopic composition and relative enrichment for the same Z in the two systems. The yields of the Intermediate Mass Fragments (IMF, 3&lt;Z&lt;12) exhibits a strong even-odd staggering, more pronounced for the n-poor system. The IMF energy spectra show some differences according to the entrance channel and to the charge and mass of the fragment.

The reactions 78 Kr + 40 Ca and 86 Kr + 48 Ca realized at 10 AMeV, have been studied in Catania a... more The reactions 78 Kr + 40 Ca and 86 Kr + 48 Ca realized at 10 AMeV, have been studied in Catania at LNS with the 4π multidetector CHIMERA. For these systems, we have already studied the fusion-evaporation and fission-like processes. Now we will present a study of the break-up of the Projectile-Like Fragment (PLF) into two fragments, following more violent deep-inelastic collision. A selection method has been developed, in order to discriminate PLF break-up from events due to other mechanisms, fusion-fission-like processes, which populate the same region of the phase-space. A preference for PLF aligned break-up, along the direction of the PLF-TLF separation axis with the light fragment emitted in the backward part, has been evidenced, suggesting dynamical-nonequilibrium effects. The isospin is expected to play a crucial role in the onset of this process; a comparison between the neutron-rich 86 Kr + 48 Ca system and neutron-poor 78 Kr + 40 Ca one will be presented.

arXiv: Instrumentation and Detectors, 2020

The Extreme Energy Events (EEE) experiment, dedicated to the study of secondary cosmic rays, is a... more The Extreme Energy Events (EEE) experiment, dedicated to the study of secondary cosmic rays, is arguably the largest detector system in the world implemented by Multigap Resistive Plate Chambers. The EEE network consists of 60 telescopes distributed over all the Italian territory; each telescope is made of three MRPCs and allows to reconstruct the trajectory of cosmic muons with high efficiency and optimal angular resolution. A distinctive feature of the EEE network is that almost all telescopes are housed in High Schools and managed by groups of students and teachers, who previously took care of their construction at CERN. This peculiarity is a big plus for the experiment, which combines the scientific relevance of its objectives with effective outreach activities. The unconventional location of the detectors, mainly in standard classrooms of school buildings, with heterogeneous maintenance conditions and without controlled temperature and dedicated power lines, is a unique test fi...

The European Physical Journal C, 2021

This paper describes the simulation framework of the extreme energy events (EEE) experiment. EEE ... more This paper describes the simulation framework of the extreme energy events (EEE) experiment. EEE is a network of cosmic muon trackers, each made of three multi-gap resistive plate chambers (MRPC), able to precisely measure the absolute muon crossing time and the muon integrated angular flux at the ground level. The response of a single MRPC and the combination of three chambers have been implemented in a GEANT4-based framework (GEMC) to study the telescope response. The detector geometry, as well as details about the surrounding materials and the location of the telescopes have been included in the simulations in order to realistically reproduce the experimental set-up of each telescope. A model based on the latest parametrization of the cosmic muon flux has been used to generate single muon events. After validating the framework by comparing simulations to selected EEE telescope data, it has been used to determine detector parameters not accessible by analysing experimental data on...

Journal of Physics: Conference Series, 2018

View the article online for updates and enhancements. Content from this work may be used under th... more View the article online for updates and enhancements. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

EPJ Web of Conferences, 2016

The study of the decay modes competition of the compound systems produced in the collisions 78 Kr... more The study of the decay modes competition of the compound systems produced in the collisions 78 Kr+ 40 Ca and 86 Kr+ 48 Ca at 10AMeV is presented. In particular, the N/Z entrance channel influence on the decay paths of the compound systems, directly connected to the isospin influence, is investigated. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS) in Catania by using the 4π multi-detector CHIMERA. Charge, mass, angular distributions and kinematical features of the reaction products were studied. The analysis shows some differences in the contribution arising from the various reaction mechanisms for the neutron poor and neutron rich systems. Comparison with theoretical statistical and dynamical models are presented for the two systems. Besides a study of the influence of the energy on the entrance channel is performed for the 78 Kr+ 40 Ca reaction, by comparing the results of this experiment to those obtained for the same system at 5.5 AMeV with the INDRA device at GANIL.

Physical Review C, 2016

Directed and elliptic flows of neutrons and light charged particles were measured for the reactio... more Directed and elliptic flows of neutrons and light charged particles were measured for the reaction 197 Au+ 197 Au at 400 MeV/nucleon incident energy within the ASY-EOS experimental campaign at the GSI laboratory. The detection system consisted of the Large Area Neutron Detector LAND, combined with parts of the CHIMERA multidetector, of the ALADIN Time-of-flight Wall, and of the Washington-University Microball detector. The latter three arrays were used for the event characterization and reaction-plane reconstruction. In addition, an array of triple telescopes, KRATTA, was used for complementary measurements of the isotopic composition and flows of light charged particles. From the comparison of the elliptic flow ratio of neutrons with respect to charged particles with UrQMD predictions, a value γ = 0.72 ± 0.19 is obtained for the power-law coefficient describing the density dependence of the potential part in the parametrization of the symmetry energy. It represents a new and more stringent constraint for the regime of supra-saturation density and confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence deduced from the earlier FOPI-LAND data. The densities probed are shown to reach beyond twice saturation.

Journal of Physics: Conference Series, 2015

Future space experiments dedicated to the observation of high-energy gamma and cosmic rays will i... more Future space experiments dedicated to the observation of high-energy gamma and cosmic rays will increasingly rely on a highly performing calorimetry apparatus, and their physics performance will be primarily determined by the geometrical dimensions and the energy resolution of the calorimeter deployed. Thus it is extremely important to optimize its geometrical acceptance, the granularity, and its absorption depth for the measurement of the particle energy with respect to the total mass of the apparatus which is the most important constraint for a space launch. The proposed design tries to satisfy these criteria while staying within a total mass budget of about 1.6 tons. Calocube is a homogeneous calorimeter instrumented with Cesium iodide (CsI) crystals, whose geometry is cubic and isotropic, so as to detect particles

EPJ Web of Conferences, 2014

A study of hot Giant Dipole Resonance (GDR) in nuclei of mass A=120130 in an excitation energy r... more A study of hot Giant Dipole Resonance (GDR) in nuclei of mass A=120130 in an excitation energy range from 150 to 330 MeV, where the GDR quenching is expected to arise, has been undertaken using the MEDEA multi-detector system. Hot nuclei were populated using complete and incomplete fusion reactions. The characterization of hot system was performed through the study of residue time of flight combined with the analysis of light charged energy spectra detected in coincidence. Gamma-ray energy spectra show an evolution of the GDR main features both in terms of width and multiplicity. Evidences of a saturation of gamma multiplicity appear at high excitation energy at variance with predictions of statistical model calculations. Gammaray energy spectra can been reproduced in a phenomenological way introducing in the statistical model a sharp suppression of the gamma-ray emission above E* = 240 MeV. A comparison of experimental data to models describing the GDR disappearance will be presented.

ABSTRACT The existence of the dynamical dipole mode in the 192Pb composite system was investigate... more ABSTRACT The existence of the dynamical dipole mode in the 192Pb composite system was investigated, through the study of its prompt γ decay, employing the 40Ca+152Sm and 48Ca+144Sm reactions at Elab=11 and 10.1 MeV/nucleon, respectively. The γ-rays and light charged particles were detected in coincidence with evaporation residues and fission fragments. First results of this experiment show that the dynamical dipole mode survives in collisions involving heavier mass reaction partners than those studied previously. As a fast cooling mechanism on the fusion path, the prompt dipole γ radiation could be of interest for the synthesis of super-heavy elements through "hot" fusion reactions. Furthermore, by using radioactive beams and the prompt γ radiation as a probe we could get information on the symmetry energy at sub-saturation densities.

Radiation Effects and Defects in Solids, 2004

Ultra-high-molecular-weight-polyethylene (UHMWPE) is irradiated with 5 MeV electrons in vacuum at... more Ultra-high-molecular-weight-polyethylene (UHMWPE) is irradiated with 5 MeV electrons in vacuum at different doses. The radiation effects induced by the electron irradiation are investigated by using different physical analyses such as mechanical tensile stress measurement, hardness measurements, specific heat measurements, infrared molecular absorption, surface wetting, polymer darkness and morphological scanning electron microscopy. The results indicate that the effects induced by high

Journal of Applied Polymer Science, 2006

Poly(ethylene oxide) (PEO) hydrogels were prepared by crosslinking of aqueous PEO 35,000 solution... more Poly(ethylene oxide) (PEO) hydrogels were prepared by crosslinking of aqueous PEO 35,000 solutions at a 30% concentration by using electron irradiation. Measurements were performed at different dose rates and irradiation doses. The swelling properties of each sample have been investigated and the network properties of the PEO hydrogels calculated. In particular, the effect of dose rate and dose irradiation on the crosslinking density were investigated. Finally, the experimental results illustrating the effects of the beam parameters on the network properties for a pulsed irradiation are compared to those of a continuum beam.

Journal of Physics: Conference Series, 2016

During the last four years, several measurements have been carried out where the capabilities of ... more During the last four years, several measurements have been carried out where the capabilities of FARCOS array were tested. In some of this occasions, FARCOS was coupled to the 4π array CHIMERA, permanently placed at INFN-Laboratori Nazionali del Sud, Catania in order to be tested in real experimental measurements. At the present situation, the FARCOS demonstrator is formed by 4 telescopes out of the originally 20 that will constitute the final array. Here are presented some preliminary results obtained with the new array, probing its qualities and showing the effectiveness of FARCOS telescopes. The initial encouraging results support the construction of the complete array.

EPJ Web of Conferences, 2015

International Journal of Modern Physics E-Nuclear Physics, 2006

Using the 4π CHIMERA detector system we have observed a dynamical, non-equilibrated fission of pr... more Using the 4π CHIMERA detector system we have observed a dynamical, non-equilibrated fission of projectile-like fragments as well as an equilibrated fission component in collisions 124Sn + 64Ni and 112Sn + 58Ni at 35A MeV. The velocity and angular distributions of projectile-like fission fragments were analyzed. The contribution of the &amp;amp;amp;amp;amp;quot;dynamical fission&amp;amp;amp;amp;amp;quot; component is larger in the neutron rich 124Sn + 64Ni system than in the neutron poor 112Sn + 58Ni one.

Nuovo Cimento C Geophysics Space Physics C, Nov 1, 2018

Since January 2003, the 4 π charged-particle detector array CHIMERA in its full configuration has... more Since January 2003, the 4 π charged-particle detector array CHIMERA in its full configuration has successfully been operated at the Cata nia L boratori Nazionali del Sud (LNS) accelerator facility. Physics e xp riments studying heavy-ion reactions at Fermi bombarding energies have used a variety of beams delivered by the LNS Superconducting Cyclotron. A brief discussion of the status of some of these experiments is presented, alo ng with an outline of recent technical developments aimed at improving the CHIME RA response. Future experiments in the field of isospin physics in this ener gy domain, planned at LNS for both primary and less intense secondary partic le beams, could benefit significantly from improved experimental (A-Z) par ticle identification. Successful tests of specific pulse shape discrimi nation methods for CHIMERA silicon elements suggest that a corresponding upgrade of this detector array is feasible.

The study of the decay modes competition of the compound systems produced in the collisions 78Kr+... more The study of the decay modes competition of the compound systems produced in the collisions 78Kr+40Ca and 86Kr+48Ca at 10 MeV/A is presented. In particular, the N/Z entrance channel influence on the decay paths of the compound systems, directly connected to the isospin influence, is investigated. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS) in Catania by using the 4π multi-detector CHIMERA. Charge, mass, angular distributions and kinematical features of the reaction products were studied. The analysis shows some differences in the contribution arising from the various reaction mechanisms for the neutron-poor and neutron-rich systems.