65 research outputs found
The production of metal artefacts in Southern Etruria (Central Italy): case studies from copper to Iron Age
An analytical study is presented, aimed to determine the elemental composition of copper-based artefacts dated back from Copper Age to Early Iron Age (mid-fourth millennium to the VIIIth century B.C.), found on the Tyrrhenian side of the peninsula, corresponding to the Lazio region. The objects belong to different archaeological contexts and had various functions. They were analysed by the X-ray fluorescence technique. The results highlight the experimental character of Copper Age metallurgy, which will later evolve in the established use of copper-tin alloys. Regarding the Bronze Age, despite the typological and functional heterogeneity of the artefacts and the wide chronological range, the alloys are relatively homogeneous in composition, with regular changes that appear related to chronology, according to what is already known for the Italian peninsula. Such changes are supposedly due to variations in the availability of tin, which was not locally mined. Early Iron Age metallurgy is represented by the Selvicciola Hoard solely, which restricts the possibility of generalizing the conclusions. A striking feature of the alloys is the great compositional difference between the complete and the fragmented artefacts. The formers are made of tin bronze, whereas in the latter tin is replaced by antimony and/or lead. The use of such unusual alloys is unlikely due to lack of metallurgical knowledge. Considering the urbanized communities that arose in the Middle-Tyrrhenian area during the Early Iron Age, we suppose that such variability in a single context might be related to a production system capable of using alloys of different quality and value to satisfy a diversified demand
Comparing active and passive Bonner Sphere Spectrometers in the 2.5 MeV quasi mono-energetic neutron field of the ENEA Frascati Neutron Generator (FNG)
Bonner Sphere Spectrometer (BSS) equipped with passive detectors are used to replace active BSS in radiation environment characterized by high fluence rate, large photon background and pulsed time structure as those encountered near particle accelerators. In this work a newly developed passive Bonner Sphere Spectrometer, using Dysprosium activation foils as central detectors (Dy-BSS), was tested through comparison with a well-established active BSS. As a suitable neutron field, where both systems can correctly operate, the 2.5 MeV quasi mono-energetic beam of the ENEA Frascati Neutron Generator (FNG) was chosen. The two spectrometers are based on substantially different operation principles, therefore their response matrix are very different. In addition, the BSS are independently calibrated in different reference neutron fields. The exercise took place at 90 ďż˝ and at a fixed distance from the neutron emitting deuterated target. As reference data, the results obtained by unfolding the active BSS data were used. The FRUIT unfolding code, ver. 5 was used. The results of the Dy-BSS are fully comparable with those of the active BSS, in terms of both total fluence and shape of the neutron spectra. For the energy range studied in this exercise, the expected level of accuracy of the Dy-BSS and its suitability for operational neutron monitoring are fully confirmed
Measurement of the neutron fields produced by a 62 MeV proton beam on a PMMA phantom using extended range Bonner sphere spectrometers
The experimental characterization of the neutron fields produced as parasitic effect in medical accelerators is assuming an increased importance for either the patient protection or the facility design aspects. Medical accelerators are diverse in terms of particle type (electrons or hadrons) and energy, but the radiation fields around them have in common (provided that a given threshold energy is reached) the presence of neutrons with energy span over several orders of magnitude. Due to the large variability of neutron energy, field or dosimetry measurements in these workplaces are very complex, and in general, cannot be performed with ready-to-use commercial instruments. In spite of its poor energy resolution, the Bonner Sphere Spectrometer (BSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. The energy range of this instrument is limited to Eo 20 MeV if only polyethylene spheres are used, but can be extended to hundreds of MeV by including metal-loaded spheres (extended range BSS, indicated with ERBSS). With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, an ERBSS experiment was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN—LNS (Laboratori Nazionali del Sud), where a proton beam routinely used for ophthalmic cancer treatments is available. The 62 MeV beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points wer
Design and validation of a photon insensitive multidetector neutron spectrometer based on Dysprosium activation foils
Abstract This communication describes a photon insensitive passive neutron spectrometer consisting of Dysprosium (Dy) activation foils located along three perpendicular axes within a single moderating polyethylene sphere. The Monte Carlo code MCNPX 2.6 was used to optimize the spatial arrangement of the detectors and to derive the spectrometer response matrix. Nearly isotropic response in terms of neutron fluence for energies up to 20 MeV was obtained by combining the readings of the detectors located at the same radius value. The spectrometer was calibrated using a previously characterized 14 MeV neutron beam produced in the ENEA Frascati Neutron Generator (FNG). The overall uncertainty of the spectrometer response matrix at 14 MeV, assessed on the basis of this experiment, was ±3%
Mixed n–γ fields dosimetry at low doses by means of different solid state dosimeters
Abstract A Mock-up of the inboard shield of the ITER International nuclear fusion reactor was realized at the Frascati Neutron Generator (FNG) at ENEA Frascati with the scope to measure the nuclear heating (total dose) in the superconducting coils. High sensitivity MCP-6 and MCP-7 dosimeters were used to measure the low
PHOTONEUTRON SOURCE BY HIGH ENERGY ELECTRONS ON HIGH Z TARGET: COMPARISON BETWEEN MONTE CARLO CODES AND EXPERIMENTAL DATA
ne, in the National Laboratory of Frascati, near Rome (Italy). Neutrons are produced sending high energy electrons to impinge on an optimized Tungsten target. This source could be suitably used for calibration of neutron detectors as well as for material and nuclear science investigations. Moreover photoneutron processes are encountered in many physics domains: from accelerator to reactor physics, mainly related to neutron shielding issues in high Z materials, used for gamma shielding.This work presents the Monte Carlo simulations performed with different codes (FLUKA and MCNPX) to estimate the neutron rate and energy spectrum, obtained when 510 MeV electrons are sent against the designed target. Finally, the comparison of the Monte Carlo predictions of neutron and photon fluences around the target with the experimental values is discussed
Compact thermal neutron sensors for moderator-based neutron spectrometers
In the framework of the NESCOFI@BTF project of the Italian Institute of Nuclear Physics, different types of active thermal neutron sensors were studied by coupling semiconductor devices with a suitable radiator. The objective was to develop a detector of small dimensions with a proper sensitivity to use at different positions in a novel moderating assembly for neutron spectrometry. This work discusses the experimental activity carried out in the framework of the ERINDA program (PAC 3/9 2012) to characterise the performance of a thermal neutron pulse detector based on (6)Li
Linear Accelerator Test Facility at LNF Conceptual Design Report
Test beam and irradiation facilities are the key enabling infrastructures for
research in high energy physics (HEP) and astro-particles. In the last 11 years
the Beam-Test Facility (BTF) of the DA{\Phi}NE accelerator complex in the
Frascati laboratory has gained an important role in the European
infrastructures devoted to the development and testing of particle detectors.
At the same time the BTF operation has been largely shadowed, in terms of
resources, by the running of the DA{\Phi}NE electron-positron collider. The
present proposal is aimed at improving the present performance of the facility
from two different points of view: extending the range of application for the
LINAC beam extracted to the BTF lines, in particular in the (in some sense
opposite) directions of hosting fundamental physics and providing electron
irradiation also for industrial users; extending the life of the LINAC beyond
or independently from its use as injector of the DA{\Phi}NE collider, as it is
also a key element of the electron/positron beam facility. The main lines of
these two developments can be identified as: consolidation of the LINAC
infrastructure, in order to guarantee a stable operation in the longer term;
upgrade of the LINAC energy, in order to increase the facility capability
(especially for the almost unique extracted positron beam); doubling of the BTF
beam-lines, in order to cope with the signicant increase of users due to the
much wider range of applications.Comment: 71 page
Optimisation Study of the Fabry-PĂ©rot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source
We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam
A cross-sectional study evaluating hospitalization rates for chronic limb-threatening ischemia during the COVID-19 outbreak in Campania, Italy
The expansion of coronavirus disease 2019 (COVID-19) prompted measures of disease containment by the Italian government with a national lockdown on March 9, 2020. The purpose of this study is to evaluate the rate of hospitalization and mode of in-hospital treatment of patients with chronic limb-threatening ischemia (CLTI) before and during lockdown in the Campania region of Italy. The study population includes all patients with CLTI hospitalized in Campania over a 10-week period: 5 weeks before and 5 weeks during lockdown (n = 453). Patients were treated medically and/or underwent urgent revascularization and/or major amputation of the lower extremities. Mean age was 69.2 +/- 10.6 years and 27.6% of the patients were women. During hospitalization, 21.9% of patients were treated medically, 78.1% underwent revascularization, and 17.4% required amputations. In the weeks during the lockdown, a reduced rate of hospitalization for CLTI was observed compared with the weeks before lockdown (25 vs 74/100,000 inhabitants/year; incidence rate ratio: 0.34, 95% CI 0.32-0.37). This effect persisted to the end of the study period. An increased amputation rate in the weeks during lockdown was observed (29.3% vs 13.4%; p < 0.001). This study reports a reduced rate of CLTI-related hospitalization and an increased in-hospital amputation rate during lockdown in Campania. Ensuring appropriate treatment for patients with CLTI should be prioritized, even during disease containment measures due to the COVID-19 pandemic or other similar conditions
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