The FAZIA apparatus exploits Pulse Shape Analysis (PSA) to identify nuclear fragments stopped in the first layer of a Silicon-Silicon-CsI(Tl) detector telescope. In this work, for the first time, we ...show that the isotopes of fragments having atomic number as high as Z∼20 can be identified. Such a remarkable result has been obtained thanks to a careful construction of the Si detectors and to the use of low noise and high performance digitizing electronics. Moreover, optimized PSA algorithms are needed. This work deals with the choice of the best algorithm for PSA of current signals. A smoothing spline algorithm is demonstrated to give optimal results without requiring too much computational resources.
Abstract
The onset of Multifragmentation phenomenon is investigated at low excitation energies. A detailed study on the origin of Intermediate Mass Fragment (IMF, Z>=3) produced in central collisions ...in the
58
Ni+
40
Ca reaction at 25 AMeV is presented. The experimental campaign was performed with CHIMERA multi-detector at INFN Laboratori Nazionali del Sud in Catania (Italy). The multiple identification techniques of the 4p apparatus, together with low detection thresholds, enable the performance of a careful selection of Fusion-evaporation residues, Multifragmentation sources and their decay products. Comparisons with dynamical approach based on Boltzmann-Langevin-One-Body (BLOB) model predictions coupled with sequential emission code, were used as useful tools to depict and understand the characteristics of fragments emitted from an equilibrated compound nucleus or formed simultaneously in the multifragmenting source. A comparison with the preliminary results obtained for fragment production in central collisions of the same system,
58
Ni+
40
Ca, at higher incident energies E
beam
=35AMeV, allows to study and characterize the evolution of multifragmentation phenomenon at the lower end of Fermi energies.
An experimental campaign has been performed by the Nuclex-Hector collaboration at the Laboratori Nazionali di Legnaro in order to study different reaction channels by detecting, in coincidence, ...Evaporation Residue (ER), Charged Particles and high energy γ-rays from Giant Dipole Resonance (GDR). The studied system was 48Ti+40Ca at 300, 450 and 600 MeV, using a modular apparatus formed by triplephoswich detectors for ER and particles at the forward angles, the GARFIELD ΔE-E forward drift chamber for the charged particles between 30° and 85° and the HECTOR apparatus at the backward angles for γ-rays.
Abstract
The recently coupled INDRA-FAZIA apparatus offers unique opportunities to investigate heavy ion collisions at Fermi energies by combining the optimal identification capabilities of FAZIA and ...the large angular coverage of INDRA. We present a selection of the results of the analysis of the first experimental campaign performed with INDRA-FAZIA, in which the four reactions
58,64
Ni+
58,64
Ni have been studied at two different beam energies (32 and 52 MeV/nucleon) in the intermediate energy regime. The present work is focused on the isospin diffusion effects in semiperipheral and peripheral collisions. A stronger isospin equilibration is found at 32 MeV/nucleon than at 52 MeV/nucleon, as expected due to a shorter projectile-target interaction time in the latter case.
The response of silicon–silicon–CsI(Tl) and silicon–CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. ...The capabilities of two methods are compared: (a) the standard
Δ
E
–
E
technique and (b) the digital Pulse Shape Analysis technique (for identification of nuclear fragments stopped in a single Si-layer). In a test setup, nuclear fragments covering a large range in nuclear charge, mass and energy were detected. They were produced in nuclear reactions induced by a 35A MeV beam of
129Xe impinging on various targets. It was found that the
Δ
E
–
E
correlations allow the identification of all isotopes up to
Z
∼
25
. With the digital Pulse Shape Analysis it is possible to fully distinguish the charge of stopped nuclei up to the maximum available
Z (slightly over that of the beam,
Z=54).
An atomic clock based on x-ray fluorescence yields has been used to estimate the mean characteristic time for fusion followed by fission in reactions 238U + 64Ni at 6.6 MeV/A. Inner shell vacancies ...are created during the collisions in the electronic structure of the possibly formed Z=120 compound nuclei. The filling of these vacancies accompanied by a x-ray emission with energies characteristic of Z=120 can take place only if the atomic transitions occur before nuclear fission. Therefore, the x-ray yield characteristic of the united atom with 120 protons is strongly related to the fission time and to the vacancy lifetimes. K x rays from the element with Z=120 have been unambiguously identified from a coupled analysis of the involved nuclear reaction mechanisms and of the measured photon spectra. A minimum mean fission time τ(f)=2.5×10(-18) s has been deduced for Z=120 from the measured x-ray multiplicity.
The 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential ...cross-section data at various angles to benchmark and constrain theoretical models is made challenging by the presence of competitive reactions on target contaminants. In this paper we report on a recent measurement using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope combined with a suitable target to control possible contaminants, allowed to unambiguously disentangle the contribution of various states in 33Cl, in particular the 2.352 MeV state lying just few tens of keV above the proton separation energy.
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