36 research outputs found
Isospin diffusion measurement from the direct detection of a quasiprojectile remnant
No full textThe neutron-proton (n-p) equilibration process in Ca48+Ca40 at 35 MeV/nucleon bombarding energy is experimentally estimated by means of the isospin transport ratio. Experimental data are collected with a subset of the FAZIA telescope array, which permits us to determine the Z and N of detected fragments. For the first time, the quasiprojectile (QP) evaporative channel is compared with the QP breakup one in a homogeneous and consistent way, pointing to comparable n-p equilibration, which suggests a close interaction time between projectile and target independently of the exit channel. Moreover, in the QP evaporative channel n-p equilibration is compared with the prediction of the antisymmetrized molecular dynamics model coupled with the Gemini statistical model as an afterburner, showing a higher probability of proton and neutron transfers in the simulation with respect to the experimental data
FAZIA: A new performing detector for charged particles
No full textThe FAZIA apparatus is a new detector designed for the Fermi energy domain for charged particles based on three stages telescopes: Silicon detector (300 μm thick), Silicon detector (500 μm thick) and CsI(Tl) (10 cm). Using the ΔE-E technique and the Pulse Shape Analysis (PSA) it permits the charge and mass discrimination up to more than Z=20. In the following, some details about the FAZIA detectors and electronics, their performance and the frst experimental campaigns already performed will be discussed
FAZIA : a new performing detector for charged particles
No full textThe FAZIA apparatus is a new detector designed for the Fermi energy domain for charged particles based on three stages telescopes: Silicon detector (300 μm thick), Silicon detector (500 μm thick) and CsI(Tl) (10 cm). Using the ΔE-E technique and the Pulse Shape Analysis (PSA) it permits the charge and mass discrimination up to more than Z=20. In the following, some details about the FAZIA detectors and electronics, their performance and the frst experimental campaigns already performed will be discussed
Isospin diffusion measurement from the direct detection of a quasiprojectile remnant
No full textInternational audienceThe neutron-proton (n-p) equilibration process in Ca48+Ca40 at 35 MeV/nucleon bombarding energy is experimentally estimated by means of the isospin transport ratio. Experimental data are collected with a subset of the FAZIA telescope array, which permits us to determine the Z and N of detected fragments. For the first time, the quasiprojectile (QP) evaporative channel is compared with the QP breakup one in a homogeneous and consistent way, pointing to comparable n-p equilibration, which suggests a close interaction time between projectile and target independently of the exit channel. Moreover, in the QP evaporative channel n-p equilibration is compared with the prediction of the antisymmetrized molecular dynamics model coupled with the Gemini statistical model as an afterburner, showing a higher probability of proton and neutron transfers in the simulation with respect to the experimental data
Isospin effects studied with the chimera detector at 35 MeV/nucleon
No full textThe yield of light charged particles and intermediate mass fragments is studied for the neutron-rich, Sn-124 +Ni-64, and neutron-poor, Sn-112+Ni-58, reactions at 35 MeV/nucleon as a function of the impact parameter. Our 3 main observations are: (i) The yields of H-1, He-3 and He-4 particles in the neutron-poor system are enhanced with respect to the neutron-rich system and the yield of H-3 is suppressed at all impact parameters, (ii) The ratio of H-3 to He-3 yield is three times larger for neutron poor system, (iii) The N/Z ratio of the emitted intermediate-mass fragments shows dependence on the isospin of the system, (iv) The neutron richness of detected intermediate mass fragments depends strongly on their rapidity. The gross features of the experimental data are reproduced by quantum molecular dynamics model calculations
Isospin transport in 84Kr+112,124Sn reactions at Fermi energies
No full textIsospin transport phenomena in dissipative heavy ion collisions have been investigated at Fermi energies with a beam of 84Kr at 35AMeV. A comparison of the 〈N〉/Z of light and medium products forward-emitted in the centre of mass frame when the beam impinges on two different targets, the n-poor 112Sn and the n-rich 124Sn, is presented. Data were collected by means of a three-layer telescope with very good performances in terms of mass identification (full isotopic resolution up to Z ~ 20 for ions punching through the first detector layer) built by the FAZIA Collaboration and located just beyond the grazing angle for both reactions. The 〈N〉/Z of the products detected when the n-rich target is used is always higher than that associated to the n-poor one; since the detector was able to measure only fragments coming from the QuasiProjectile decay and/or neck emission, the observed behaviour can be ascribed to the isospin diffusion process, driven by the isospin gradient between QuasiProjectile and QuasiTarget. Moreover, for light fragments the 〈N〉/Z as a function of the lab velocity of the fragment is observed to increase when we move from the QuasiProjectile velocity to the centre of mass (neck zone). This effect can be interpreted as an evidence of isospin drift driven by the density gradient between the QuasiProjectile zone (at normal density) and the more diluted neck zone
Examination of cluster production in excited light systems at Fermi energies from new experimental data and comparison with transport model calculations
No full textFour different reactions, S32+C12 and Ne20+C12 at 25 and 50 MeV/nucleon, have been measured with the FAZIA detector capable of full isotopic identification of most forward emitted reaction products. Fragment multiplicities, angular distributions and energy spectra have been measured and compared with Monte Carlo simulations, i.e., the antisymmetrized molecular dynamics (AMD) and the heavy-ion phase space exploration (HIPSE) models. These models are combined with two different afterburner codes (HFl and SIMON) to describe the decay of the excited primary fragments. In the case of AMD, the effect of including the clustering and interclustering processes to form bound particles and fragments is discussed. A clear confirmation of the role of the cluster aggregation in the reaction dynamics and particle production for these light systems, for which the importance of the clustering process increases with bombarding energy, is obtained
Study of the in medium cross-section and of the clustering process by means of the Bayesian technique applied to a nuclear reaction at Fermi energy
No full textA Bayesian analysis aimed at tuning two parameters of the AMD model, one of them related to the in medium nucleon nucleon cross-section and the other to the clustering, has been performed. Experimental data collected with four blocks of the FAZIA setup have been compared with simulated data built with different values of the investigated parameters
