Binary collisions of either stable or radioactive heavy ions at Fermi energies allow to study the nuclear reaction mechanisms under dynamical conditions of non-equilibrium and the formation of ...transient pieces of nuclear matter of very short mean life times at sub-normal density. An important role in the evolutionary phase of the collision is played by the gradient of the nuclear density affecting the isospin asymmetry of the reaction products by typical transport phenomena such as the isospin diffusion and drift. Experimental determination of the value of the nuclear matter density in the early phase of the collision is a crucial step towards understanding the underlying mechanism responsible for the production of clusters. In this paper a method for evaluating the nuclear density in semi-peripheral collisions in the reaction
124
S
n
+
64
N
i
at 35 MeV/nucleon as studied with the CHIMERA multi-particle detector is described.
The emission probability of Intermediate Mass Fragments (IMFs) in non-central reactions has been investigated in collisions of heavy
124
Xe
projectiles with the two different medium-mass targets of
...64
Ni
and
64
Zn
at the laboratory energy of 35
A
MeV. The two colliding systems differ only for the target atomic number Z and, consequently, for the isospin
N
/
Z
ratio. The probability of IMFs emission from the projectile-like fragment has been measured, showing an enhancement of the IMFs emission for the neutron rich
64
Ni
target. Most of the observed projectile break-up yield is associated with the production of only one IMF, that is, a quasi-binary splitting of projectile in two fragments in a broad range of charge asymmetry. For the events with one IMF, the relative contributions of the dynamical and statistical emissions have been evaluated. We find an enhancement of dynamical break-up probability for the neutron rich target with respect to the neutron poor one. The analysis suggests influence of the target isospin in inducing the dynamical break-up of projectile-like fragments. The new data have been also compared with previous published results of
112
,
124
Sn
+
58
,
64
Ni
systems, in order to disentangle between isospin effects against system-size effects on the emission probability. The comparisons between previous and new data suggest that the dynamical break-up is determined by the
N
/
Z
content of both projectile and target; for the cases here investigated, the influence of the system size on the dynamical emission probability can be excluded.
The experimental investigation of Heavy Ion reactions at Fermi energies requires an accurate measurement of observables, such as linear momentum and energy of the detected particles. In order to ...address this problem, dedicated and flexible correlator arrays are useful tools to be coupled with 4π detectors. One of these arrays is FARCOS, presently under construction at the INFN Sezione di Catania and Laboratori Nazionali del Sud (LNS).
Abstract
After its successful campaign of measurements beyond the Polar Arctic Circle, the PolarquEEEst experiment measured the cosmic charged particle rate at sea level in a latitude interval ...between 35
$$^{\circ }$$
∘
N and 82
$$^{\circ }$$
∘
N. In this paper, these measurements are described and the corresponding results are discussed.
The eruption of the Hunga-Tonga volcano in the South Pacific Ocean on January 15, 2022, at about 4:15 UTC, generated a violent explosion, which created atmospheric pressure disturbances in the form ...of Rayleigh-Lamb waves detected all over the globe. Here we discuss the observation of the Hunga-Tonga shock-wave performed at the Ny-Ålesund Research Station on the Spitsbergen island, by the detectors of the PolarquEEEst experiment and their ancillary sensors. Online pressure data as well as the results of dedicated offline analysis are presented and discussed in details. Results include wave arrival times, wave amplitude measurements and wave velocity calculation. We observed five passages of the shock wave with a significance larger than 3 Formula: see text and an amplitude up to 1 hPa. The average propagation velocity resulted to be (308 ± 0.6) m/s. Possible effects of the atmospheric pressure variation associated with the shock-wave multiple passages on the cosmic-ray rate at ground level are also investigated. We did not find any significant evidence of this effect.
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 only, such as detection efficiency, angular and spatial resolution.
The goal of the PolarquEEEst experiment was to measure the cosmic charged particle rate at latitudes greater than 66
∘
N, where no systematic and accurate measurements at sea level have ever been ...performed. A latitude range well above the Arctic Circle was explored on board of a sailboat, up to the unprecedented northernmost value of
82
∘
07
′
N. In this paper a description of the experimental set-up is reported, then the procedures for calibration and data analysis are described in detail. The results show that the rate measured in this latitude range stays constant within a novel accuracy of
±
1
%.
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.
In the last decades Silicon Carbide (SiC) received special attentions, in particular as semiconductor material, because is considered as alternative to Silicon for the future high-power, low ...consumption, radiation-hard microelectronics devices. This ambitious goal is particularly interesting also for the physics of the detectors. In this work are discussed some of the recent results obtained by SiCILIA collaboration, a joint research activity between INFN and IMM institutions to increase the level of technological development in the field of SiC detectors.
The study of heavy-ion collisions in the Fermi energy domain (20 MeV/nucleon < E/A < 100 MeV/nucleon) is a fundamental research topic in modern nuclear physics. In the case of semi-peripheral ...collisions, the Fermi energy regime is characterized by the formation of a transient, neck-like structure that connects a projectile-like fragment (PLF) with a target-like fragment (TLF). The neck structure represents a precursor of the fireball which is a typical overlap of participating nucleons at relativistic energies (E/A> 200 MeV/nucleon). It undergoes an expansion phase in a short time scale of the order of 100 fm/c with the formation of a low-density region of nuclear matter, therefore favoring the clusterization of intermediate mass fragments (IMFs) of atomic number Z (typically) less than 20. Particular emphasis is given to some relevant results obtained by the CHIMERA collaboration in the last decade, regarding the time scale of the production mechanisms of the intermediate mass fragments in neck fragmentation and their neutron enrichment.
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