In this paper the technological aspects of the FAZIA array will be explored. After a productive commissioning phase, FAZIA blocks started to measure and give very useful data to explore the physics ...of Fermi energy heavy-ion reactions. This was possible thanks to many technical measures and innovations developed in the commissioning phase and tuned during the first experimental campaigns. This paper gives a detailed description of the present status of the FAZIA setup from the electronic and mechanical point of view, trying also to trace a path for new improvements and refinements of the apparatus.
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.
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).
Proton energy calibration and identification efficiency of few Thallium activated Cesium Iodide (CsI(Tl)) crystals of the FAZIA detection system, have been studied in the range 59-180 MeV by using ...the proton beam delivered by the cyclotron of the CCB (Cyclotron Center Bronowice) facility. We observe that the light output versus energy is linear in the lower investigated energy range while showing a deviation from linearity above 140 MeV. The effects of proton induced nuclear reactions and multiple scattering causing incomplete energy deposition (IED) events have been identified and estimated via Pulse Shape Analysis in CsI(Tl) crystals. The measured experimental efficiency for proton identification in the examined energy range is then compared with GEANT4 simulations. For a centered collimated irradiation on the crystal, and at the highest measured energy, the resulting experimental efficiency value is about 70%.
A STUDY ON 4 REACTIONS FORMING 46Ti Cicerchia, M.; Marchi, T.; Gramegna, F. ...
Journal of physics. Conference series,
02/2018, Letnik:
966, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The NUCL-EX collaboration is carrying out an extensive research program on preequilibrium emission of light charged particles from hot nuclei. The ultimate goal is to study how cluster structures ...affect nuclear reactions 1,2,3,4. Indeed, a strong correlation between nuclear structure and reaction dynamics emerges when some nucleons or clusters of nucleons are emitted or captured 5. At this purpose, the four reactions 16O+30Si, 16O+30Si, 18O+28Si and 19F +27Al have been measured at about 120 MeV projectile energy. Experimental data were collected at Legnaro National Laboratories, using the GARFIELD+RCo array, fully equipped with digital electronics 6. Following an initial identification of particles and the energy calibration procedures, the complete analysis is being performed on an event-by-event basis. Experimental data are then compared to the theoretical predictions where events are generated by numerical codes based on pre-equilibrium and statistical models and then filtered through a software replica of the setup. Differences between the experimental data and the predicted data put into evidence effects related to the entrance channel and to the cluster nature of the colliding ions. After a general introduction on the experimental campaign, this contribution will focus on the preliminary results obtained so far.
In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei 1, 2. In the currently experimental campaign, the NUCL-EX collaboration has measured ...the12C+12C and14N+10B reactions at 95 MeV and 80 MeV respectively. The experimental data corresponding to complete fusion of target and projectile into an excited24Mg nucleus was compared to the results of a pure statistical model 3, 4. In addition, data from12C+12C have been analyzed to investigate the decay of the Hoyle state of12C* 12 obtained as an intermediate step in the 6α decay channel of the24Mg* formed in central events.
Clustering structural properties in medium-mass systems have been investigated studying the competition between the evaporation and pre-equilibrium particle emission in central collisions. At ...variance with light nuclei, in the case of heavier nuclei there are no experimental evidences of such structure effects, since the determination of pre-formed clusters within nuclear matter is less obvious. The two systems 16O + 65Cu and 19F + 62Ni, leading to the same compound system 81Rb*, have been studied at the same beam velocity (16 AMeV). The experiments have been performed using the GARFIELD + RCo multi-detection system at the Legnaro National Laboratories. Recent results of the data analysis and of the comparison of the experimental data with different statistical and dynamical model calculations are reported in this contribution.
The study of nuclear states built on clusters bound by valence neutrons in their molecular configurations is a field of large interest, which is being renewed by the availability of exotic beams: ...clustering is, in fact, predicted to become very important at the drip-line, where weakly bound systems will prevail. Although for light nuclei at an excitation energy close to the particle separation value there are experimental evidences of such structure effects, this is still not the case for heavier nuclear systems. Many attempts have been done using preformation alpha clustering models, but there is still a lack of experimental data capable to give a direct feedback. In particular, searching for alpha clustering effects in medium mass systems is still a challenge, which can give new hints in this subject. In the past we have studied the reactions 250, 192 and 130 MeV 16O + 116Sn, observing a significant increase in the fast emitted α-particle yield. This effect was ascribed to the presence of preformed a-clusters in the 16O projectile nucleus. In order to investigate these aspects, in a model independent way, a new experimental campaign has been performed with the GARFIELD + RCo set up, to compare results from two different reactions: a double magic a-cluster (16O) and a non-magic α-cluster projectile (19F) at the same beam velocity (16AMeV) have been chosen, impinging respectively on 65Cu and 62Ni targets, thus leading to the same 81Rb* compound nucleus. The angular distributions and the light charged particles emission spectra in coincidence with evaporation residues have been measured and analyzed. The preliminary results of the data analysis and the main features of the theoretical model used for their interpretation are presented.
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