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125 result(s) for "Rapisarda, Giuseppe"
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Radiation Damage by Heavy Ions in Silicon and Silicon Carbide Detectors
While silicon has been a steadfast semiconductor material for the past 50 years, it is now facing competition from other materials, especially for detector design. In that respect, due to its high resistance to radiation damage, silicon carbide is one of the most promising materials. In this work, we discuss the radiation damage studies of a new, large area, p-n junction silicon carbide device developed by the SiCILIA collaboration. We have studied the general performances of several devices, as a function of fluence, irradiated in different experimental conditions with different beams. A standard p-n junction silicon detector was also irradiated for comparison. The new detectors manifest excellent performance in terms of stability of the main parameters, linearity, defect distribution, charge collection efficiency, energy resolution, leakage current, etc. Experimental results evidence a radiation resistance of SiC devices more than two order of magnitude higher than Si devices. The new construction technology applied to silicon carbide material has made it possible to create very robust devices with excellent performance. These devices will soon be available for all those scientific projects where a high resistance to radiation damage is required.
Defense and protection mechanisms in lung exposed to asbestiform fiber: the role of macrophage migration inhibitory factor and heme oxygenase-1
Fluoro-edenite (FE), an asbestiform fiber, is responsible for many respiratory pathologies: chronic obstructive diseases, pleural plaques, fibrosis, and malignant mesothelioma. Macrophage migration inhibitory factor (MIF) is one of the first cytokines produced in response to lung tissue damage. Heme oxygenase-1 (HO-1) is a protein with protective effects against oxidative stress. It is up regulated by several stimuli including pro-inflammatory cytokines and factors that promote oxidative stress. In this research, the in vivo model of sheep lungs naturally exposed to FE was studied in order to shed light on the pathophysiological events sustaining exposure to fibers, by determining immunohistochemical lung expression of MIF and HO-1. Protein levels expression of HO-1 and MIF were also evaluated in human primary lung fibroblasts after exposure to FE fibers in vitro. In exposed sheep lungs, MIF and HO-1 immunoexpression were spread involving the intraparenchymal stroma around bronchioles, interstitium between alveoli, alveolar epithelium and macrophages. High MIF immunoexpression prevails in macrophages. Similar results were obtained in vitro, but significantly higher values were only detected for HO-1 at concentrations of 50 and 100 μg/mL of FE fibers. MIF and HO-1 expressions seem to play a role in lung self-protection against uncontrolled chronic inflammation, thus counteracting the strong link with cancer development, induced by exposure to FE. Further studies will be conducted in order to add more information about the role of MIF and HO-1 in the toxicity FE-induced.
The 19F(p, α1,2) reaction studied via Trojan Horse Method in astrophysical range of interest
The complex reaction network connected to the 19F stellar abundance is very sensitive to the physical condition in stars. To overcome difficulties present in the direct measurements, mainly the very low cross section in the astrophysical energy range due to the Coulomb repulsion, an indirect measurement of the 19F(p, α) reaction, with the Trojan Horse Method (THM), was performed at INFN-LNS. While the method had been successfully used to study α0 channel, in the present analysis focus was given to the α1,2 channels, where better knowledge of the reaction rates at low energies is required, obtainable by employing the THM method.
Direct and Indirect Measurements of the 19F(p,α)16O Reaction at Astrophysical Energies Using the LHASA Detector and the Trojan Horse Method
Fluorine is one of the most interesting elements in nuclear astrophysics. Its abundance can provide important hints to constrain the stellar models since fluorine production and destruction are strictly connected to the physical conditions inside the stars. The F19(p,α)16O reaction is one of the fluorine burning processes and the correction evaluation of its reaction rate is of pivotal importance to evaluate the fluorine abundance. Moreover, the F19(p,α)16O reaction rate can have an impact for the production of calcium in the first-generation of Population III stars. Here, we present the AsFiN collaboration efforts to the study of the F19(p,α)16O reaction by means of direct and indirect measurements. On the direct measurements side, an experimental campaign aimed to the measurement of the F19(p,α0,π)16O reaction is ongoing, taking advantage of the new versatile arrays of silicon strip detectors, LHASA and ELISSA. Moreover, the Trojan Horse Method (THM) was used to determine the F19(p,α0)16O reaction S(E)-factor in the energy range of astrophysical interest (Ecm≈ 0–1 MeV), showing, for the first time, the presence of resonant structures within the astrophysical energy range. THM has been also applied for the study of the F19(p,απ)16O reaction; data analysis is ongoing.
Recent THM investigations on neutron induced reactions at astrophysical energies
Neutron induced reactions on stable and unstable nuclei play a significant role in the nucleosynthesis of the elements in the cosmos. In the last years, several efforts have been made to investigate the possibility of applying the Trojan Horse Method (THM) to neutron induced reactions mostly by using deuteron as “TH-nucleus”. Here, the main advantages of using THM will be given together with a more focused discussion on the recent 7 Be(n, α ) 4 He and the 14 N(n,p) 14 C reactions.
Direct and Indirect Measurements of the sup.19Fsup.16O Reaction at Astrophysical Energies Using the LHASA Detector and the Trojan Horse Method
Fluorine is one of the most interesting elements in nuclear astrophysics. Its abundance can provide important hints to constrain the stellar models since fluorine production and destruction are strictly connected to the physical conditions inside the stars. The F19(p,α)[sup.16] O reaction is one of the fluorine burning processes and the correction evaluation of its reaction rate is of pivotal importance to evaluate the fluorine abundance. Moreover, the F19(p,α)[sup.16] O reaction rate can have an impact for the production of calcium in the first-generation of Population III stars. Here, we present the AsFiN collaboration efforts to the study of the F19(p,α)[sup.16] O reaction by means of direct and indirect measurements. On the direct measurements side, an experimental campaign aimed to the measurement of the F19(p,α[sub.0,π] )[sup.16] O reaction is ongoing, taking advantage of the new versatile arrays of silicon strip detectors, LHASA and ELISSA. Moreover, the Trojan Horse Method (THM) was used to determine the F19(p,α[sub.0] )[sup.16] O reaction S(E)-factor in the energy range of astrophysical interest (E[sub.cm] ≈ 0–1 MeV), showing, for the first time, the presence of resonant structures within the astrophysical energy range. THM has been also applied for the study of the F19(p,α[sub.π] )[sup.16] O reaction; data analysis is ongoing.
Coulomb-free 1S0p − p scattering length from the quasi-free p + d → p + p + n reaction and its relation to universality
The Coulomb-free 1 S 0 proton-proton ( p - p ) scattering length relies heavily on numerous and distinct theoretical techniques to remove the Coulomb contribution. Here, it has been determined from the half-off-the-energy-shell p - p scattering cross section measured at center-of-mass energies below 1 MeV using the quasi-free p  +  d  →  p  +  p  +  n reaction. A Bayesian data-fitting approach using the expression of the s-wave nucleon-nucleon scattering cross section returned a p - p scattering length a p p = − 18.1 7 − 0.58 + 0.52 ∣ s t a t ± 0.0 1 s y s t fm and effective range r 0  = 2.80 ± 0.05 s t a t  ± 0.001 s y s t fm. A model based on universality concepts has been developed to interpret this result. It accounts for the short-range interaction as a whole, nuclear and residual electromagnetic, according to what the s-wave phase-shift δ does in the description of low-energy nucleon-nucleon scattering data. We conclude that our parameters are representative of the short-range physics and propose to assess the charge symmetry breaking of the short-range interaction instead of just the nuclear interaction. This is consistent with the current understanding that the charge dependence of nuclear forces is due to different masses of up-down quarks and their electromagnetic interactions. This achievement suggests that these properties have a lesser than expected impact in the context of the charge symmetry breaking. The difference in proton-proton and neutron-neutron scattering lengths contributes to understanding the charges symmetry breaking of nuclear forces, yet, the Coulomb-free proton-proton scattering length (app) cannot be measured directly. The authors apply an innovative technique, the so called Trojan Horse Method, to experimentally determine the Coulomb-free app value and exploit the potentialities of the universal window to assess the short-range physics.
Cutaneous Malignant Melanoma with Testicular Metastases in a Wild Rabbit (Oryctolagus cuniculus)
Melanocytic skin tumours have been rarely described in pet rabbits, and exposure to UV light in sparsely haired areas has been hypothesised to play a cancerogenic role. Here, we describe a case of cutaneous malignant melanoma arising from the skin of the scrotum in an 8-year-old male wild rabbit, with testicular metastases as an unusual metastatic site for melanoma reported in humans to date. The tumour was nearly 5 cm in size, firm, and highly pigmented, with multifocal superficial ulcerations and large areas of intratumoural necrosis. The adjacent testis was 1.5 cm, multinodular, and black, obscuring tissue morphology. Histologically, the dermis was expanded by an infiltrative, densely cellular neoplasm composed of nests and sheets of polygonal to spindle neoplastic melanocytes, supported by scant fibrovascular stroma. Neoplastic cells showed intermediate N/C ratio, moderate basophilic cytoplasm, often obscured by abundant brownish granular pigment, and eccentric nuclei with prominent nucleoli. Cellular pleomorphism and nuclear atypia were severe, and high mitotic activity was observed. Diffuse dermal lymphovascular invasion was also observed. The testis was delimited by a thin tunica albuginea, and the parenchyma was largely obscured in its morphology by densely packed neoplastic cells. Seminiferous tubules, lined with a thin basement membrane and containing neoplastic and scattered spermatogenic cells, were occasionally observed. Neoplastic cells within the skin and the testis were positive for HMB-45, Melan-A, and S-100. The growing popularity of rabbits as pets allows for a greater ability to accumulate data on the spontaneous occurrence of tumours in these animals. Furthermore, descriptions of the biological aspects of spontaneously occurring tumours may serve to improve current knowledge in animal species and humans in which the same neoplasm may occur.
Investigation of a light Dark Boson existence: The New JEDI project
Several experiments around the world are looking for a new particle, named Dark Boson, which may do the link between the Ordinary Matter (which forms basically stars, planets, interstellar gas...) and the Hidden Sectors of the Universe. This particle, if it exists, would act as the messenger of a new fundamental interaction of nature. In this paper, the underlying Dark Sectors theory will be introduced first. A non-exhaustive summary of experimental studies carried out to date and foreseen in the incoming years will be presented after,including the 8 Be anomaly. The last section will provide a status of the New JEDI*** project which aims to investigate the existence or not of a Dark Boson in the MeV range.
Nuclear Physics in Stellar Lifestyles with the Trojan Horse Method
The Trojan Horse Method is an indirect technique to measure nuclear reactions of astrophysical relevance at the energies of interest, free of Coulomb suppression and electron screening effects. Its basic features in the framework of the theory of direct reactions will be discussed and the physics case of the 12 C +12 C fusion will be addressed.