Scientific Open-access Literature Archive and Repository
Not a member yet
16397 research outputs found
Sort by
Anisotropies in the highest-energy cosmic rays with data from the Pierre Auger Observatory
No full textAfter 15 years of operations, the Pierre Auger Observatory has gathered more data on the highest-energy cosmic rays than any other experiment in the past. With this data, new light has been shed on the origin of such high-energy particles, albeit no final word on their sources has been said yet
Latest results of dark matter detection with the DarkSide experiment
No full textIn this contribution the latest results of dark matter direct detection obtained by the DarkSide Collaboration are discussed. New limits on the scattering cross-section between dark matter particles and baryonic matter have been set. The results have been reached using the DarkSide-50 detector, a double-phase Time Projection Chamber (TPC) filled with 40Ar and installed at Laboratori Nazionali del Gran Sasso (LNGS). In 2018, the DarkSide Collaboration has performed three different types of analysis. The so-called high-mass analysis into the range between ∼ 10 GeV and ∼ 1000 GeV is discussed under the hypothesis of scattering between dark matter and Ar nuclei. The low-mass analysis, performed using the same hypothesis, extends the limit down to ∼1.8 GeV. Through a different hypothesis, that predicts dark matter scattering off the electrons inside of the Ar atom, it has been
possible to set limits for sub-GeV dark matter masses
Two-loop corrections to electron-muon scattering at NNLO in QED
No full textIn this paper, we discuss the evaluation of the two-loop virtual corrections to the electron-muon scattering at next-to-next-to-leading order (NNLO) in QED. These radiative corrections are relevant for the analysis of the MUonE experiment, recently proposed at CERN. MUonE aims at the high-precision determination of the QED running coupling constant in the space-like region from the
measurement of the differential cross section of the elastic scattering of high-energy muons on atomic electrons. The precise theoretical knowledge of QED corrections to the process will allow to extract from the experimental data the full hadronic contribution to the running coupling constant. This will provide a new and independent determination of the leading-order hadronic correction to the muon g − 2. As an essential step towards the full theoretical prediction, we present the decomposition of the NNLO virtual amplitude in terms of basic integrals and the analytical evaluation of the latter by means of differential equations and the Magnus exponential method. We work in the massless electron approximation, while we retain full dependence on the muon mass. The presented results are also relevant for crossingrelated processes, such as di-muon production at e+e− colliders, as well as for the QCD corrections to top-pair production at hadron colliders
Long-range selective transport of anions and cations in graphene oxide membranes, causing selective crystallization on the macroscale
Get PDFMonoatomic nanosheets can form 2-dimensional channels with tunable chemical properties, for ion storage and filtering applications. Here, we demonstrate transport of K+, Na+, and Li+ cations and F− and Cl− anions on the centimeter scale in graphene oxide membranes (GOMs), triggered by an electric bias. Besides ion transport, the GOM channels foster also the aggregation of the selected ions in salt crystals, whose composition is not the same as that of the pristine salt present in solution, highlighting the difference between the chemical environment in the 2D channels and in bulk solutions
Core–shell graphene oxide–polymer hollow fibers as water filters with enhanced performance and selectivity
Get PDFCommercial hollow fiber filters for micro- and ultrafiltration are based on size exclusion and do not allow the removal of small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone–polyvinylpyrrolidone hollow fiber (Versatile PES®, hereafter PES) modules and that the resulting core–shell fibers inherits the microfiltration ability of the pristine PES fibers and the adsorption selectivity of GO. GO nanosheets were deposited on the fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1–0.2 μm), then fixed by thermal annealing at 80 °C, rendering the GO coating stably fixed and unsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water and bovine plasma spiked with bovine serum albumin (BSA, 66 kDa, ≈15 nm size), monodisperse polystyrene nanoparticles (52 nm and 303 nm sizes), with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that the microfiltration capability of PES was retained by HF-GO, and in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show that the separation mechanism does not rely only on physical size exclusion, but involves intercalation of solute molecules between the GO layers
High space resolution μ-RWELL for high particle rate
No full textThe μ-RWELL is a single-amplification stage-resisitive MPGD. The amplification element is realized on a polyimide foil micro-patterned with high density blind-holes (wells) and is embedded through a thin resistive film in the readout PCB. The introduction of the resistive layer suppresses the transition from streamer to spark giving the possibility to achieve large gains (> 104). As a drawback the capability to stand high particle fluxes is reduced. To avoid such a limitation different resistive layouts have been designed. The study of the performance of such layouts done at PSI, together with the measurement of the space resolution for orthogonal and inclined tracks performed at CERN are presented in this work
Design of the 16 T bending dipole for the Future Circular Collider
No full textThe EuroCirCol project is part of the Future Circular Collider (FCC) study, a 100 km post-LHC accelerator, which will allow achieving about 100 TeV energy in the center of mass. The INFN sections of Genoa and Milan (LASA) developed the baseline design of the 16 T bending dipole for the hadron collider (FCC-hh). This work is part of the Conceptual Design Report (CDR), which has been published at the beginning of 2019
Pressure evolution of the optical phonons of MoTe2
No full textIn this work, we report a study on the evolution of the MoTe2 phonons under pressure, performed through optical spectroscopy on bulk samples. Raman and infrared measurements were carried out at room temperature (RT) up to ∼20 GPa. The analysis of the phonon frequencies as a function of pressure confirms the absence of structural transition, already observed in the literature. The abrupt
broadening of the Raman peaks above 18 GPa suggests an increase of the charge carriers, also supported by the rapid decrease of the infrared peak area in the range 13–19 GPa. The asymmetric line-shape of the infrared peak at low pressure has been interpreted in the framework of the Fano theory, in analogy to the results obtained for graphene, and related to the presence of doping levels in the band structure
Design and performance of the Calorimeter for the FOOT experiment
No full textHadrotherapy is a highly effective method for treating deep-seated tumours. However, the lack of information about cross sections for fragments produced by beam-tissue nuclear interactions limits the precision of clinical treatment planning systems. The FOOT Collaboration is building a detector optimized for the identification of heavy fragments in a reverse-kinematics configuration, through the measurement of their momentum, energy and time of flight. The energy will be measured with a calorimeter composed by 320 BGO crystals coupled with SiPM arrays, which will allow a compact design. Design and performance of the calorimeter tested at the facilities of CNAO will be presented
Influence of saccharides on the dosimetric properties of PVA-GTA Fricke gels
No full textThe Fricke gels (FG) composition has been modified over the years in order to improve their dosimetric characteristic for spatial dose evaluation in radiotherapy. Some problems have limited the clinical use of FG and still represent significant challenges for the scientific community working in the field of gel dosimetry. With this study, the effects of saccharides like sucrose and glucose on the dosimetric properties of Fricke gels based on poly(vinyl-alcohol) (PVA) as gelling
agent and glutaraldehyde (GTA) as cross-linker have been tested. The dose-response curves of PVA-GTA Fricke gel dosimeters prepared using different sucrose and glucose concentrations were investigated by optical absorbance measurements. The shape of the optical absorbance spectra of the gel dosimeters in the wavelength interval 360–720 nm have shown a slight dependence on the saccharides concentration and varied with the absorbed dose. The results demonstrated that the use of different concentrations of sucrose and glucose does not produce significant dosimetric consequences in the interval of linearity (0–16 Gy) of the dose-response curve of the PVA-GTA Fricke gel dosimeters