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Secondary scintillation yield from GEM electron avalanches in [Formula presented]-[Formula presented] and [Formula presented]-[Formula presented]-isobutane for CYGNO — Directional Dark Matter search with an optical TPC
No full textCYGNO is an international collaboration with the aim of operating a [Formula presented] optical time projection chamber (TPC) for directional Dark Matter (DM) searches and solar neutrino spectroscopy, to be deployed at the Laboratori Nazionali del Gran Sasso (LNGS). A [Formula presented]/[Formula presented] (60/40) mixture is used, along with a triple Gas Electron Multiplier (GEM) cascade to amplify the ionisation signal. The scintillation produced in the electron avalanches is read out using a scientific complementary metal–oxide–semiconductor (sCMOS) camera. This solution has proven to provide very high sensitivity to interactions in the few [Formula presented] energy range. The inclusion of a hydrogen-based gas will offer an even lighter target, resulting in a more efficient energy transfer in a DM particle collision, and consequently, a lower detection threshold. Additionally, longer track lengths of light nuclear recoils are easier to detect with a clearer direction. However, the addition of such gas will contribute to quenching the scintillation, jeopardizing the TPC performance. In this work, we demonstrate the feasibility of adding 1% to 5% isobutane to the [Formula presented]/[Formula presented] (60/40) mixture by measuring the respective absolute scintillation yield output. The overall scintillation produced in the charge avalanches is not drastically suppressed by quenching due to the isobutane addition. The presence of Penning transfer from excited He atoms to isobutane molecules increases the number of electrons in the avalanches, partially compensating for the loss of scintillation due to quenching. For the highest applied GEM voltage, the total number of photons produced in the avalanche per [Formula presented] deposited in the absorption region presents a decrease of only a factor of about three, from 2.30(20)×104 to 8.2(4)×103 [Formula presented], as the isobutane content increases from 0 to 5%. The quantification of the visible component of the scintillation shows that isobutane quenches both visible and ultraviolet (UV) photons emitted by [Formula presented]/[Formula presented]
Development of a thermal mass flow meter for heavy liquid metal applications
No full textIn the framework of heavy liquid metal applications, experimental campaigns play an essential role in the development and licensing of new technologies. Reliable experimental results can be achieved with proven methodologies and accurate measuring instruments. ENEA has developed and tested a thermal mass flow meter design for heavy liquid metal applications that proved to be reliable within its range of operation. An experimental campaign has been conducted on the IELLLO facility to test the high range (1–10 kg/s) thermal mass flow meter, already adopted on other facilities, and the new low range (0.1–2 kg/s) prototype, designed for fusion application on the WCLL Test Blanket Module. The results of the two instruments have been reported, with a detailed discussion on error estimation, for which analytical and Monte Carlo calculation have been performed. CFD modelling of the phenomena on both the TFMs have been presented to support the comprehension of the experimental results. The activities demonstrate the capability of the instruments to provide accurate and reliable results while supplying a better understanding of the physics involved
Quantum Big-Bounce as a phenomenology of RQM in the Mini-superspace
Full text linkWe investigate the emergence of a quantum Big-Bounce in the context of an isotropic Universe, filled by a self-interacting scalar field, which plays the role of a physical clock. The bouncing cosmology is the result of a scattering process, driven by the scalar field potential, which presence breaks down the frequency separation of the Wheeler-DeWitt equation, treated in strict analogy to a relativistic quantum system. Differently from previous analyses, we consider a really perturbative self-interaction potential, affecting the dynamics in a finite range of the time labeled by the scalar clock (and in particular we remove the divergent character previously allowed). The main result of the present analysis is that, when the Relativistic Quantum Mechanics formalism is properly implemented in the Mini-superspace analogy, the probability amplitude for the bounce is, both in the standard and polymerized case, characterized by a maximum in correspondence of the quasi-classical condition of a Universe minimum volume
Characterization of Critical Fields and Flux Pinning Energy of REBCO Tapes
No full textREBCO tapes are currently being produced by various companies, each employing unique combinations of materials and deposition processes. To effectively design and optimize their use in power devices, it is crucial to ascertain their critical field characteristics and understand their flux pinning properties. In this work, we conducted a comprehensive investigation involving electrical transport and magnetization measurements on coated conductors (CCs) produced by Shanghai Superconductor Technology Co., Ltd. (SST). Our findings reveal that the flux pinning energy of these CCs exhibits a collective pinning behavior across the entire range of magnetic fields under consideration. Moreover, the behavior of these CCs in high magnetic fields suggests that their design is well-suited for low-temperature, high-power applications
Tomato pomace food waste from different variants as a high antioxidant potential resource
Full text linkPomaces obtained from three San Marzano tomato genotypes including the wild type (WT), Sun Black (SB), and colorless fruit epidermis (CL) were dried at 50 °C and analyzed for nutritional composition, total polyphenol (TPC), flavonoid (TFC) content, polyphenol qualitative profile, total antioxidant capacity (TAC), and antimicrobial activity. Commercial dried tomato powder (CTRP) was included as a control. No differences were detected nutritionally, in TPC and antimicrobial activity, but significant changes were observed for TFC and TAC, underlying variation in the phenolic profile. SB pomace (SBP) had the highest TFC and TAC. LC-HRMS analysis showed a flavonoid-enriched profile in SBP besides the exclusive presence of anthocyanins, with petanin and negretein as the most abundant. Among flavonoids, quercetin-hexose-deoxyhexose-pentose, naringenin, and rutin were the major. Overall, we showed the potential of dried tomato pomace, especially SBP, as an extremely valuable waste product to be transformed into a functional ingredient, reducing the food industry waste
On the Elusive Crystallography of Lithium-Rich Layered Oxides: Novel Structural Models
Full text linkLithium-rich layered oxides (LRLOs) are one of the most attractive families among future positive electrode materials for the so-called fourth generation of lithium-ion batteries (LIBs). Their electrochemical performance is enabled by the unique ambiguous crystal structure that is still not well understood despite decades of research. In the literature, a clear structural model able to describe their crystallographic features is missing thereby hindering a clear rationalization of the interplay between synthesis, structure, and functional properties. Here, the structure of a specific LRLO, Li1.28Mn0.54Ni0.13Co0.02Al0.03O2, using synchrotron X-ray diffraction (XRD), neutron diffraction (ND), and High-Resolution Transmission Electron Microscopy (HR-TEM), is analyzed. A systematic approach is applied to model diffraction patterns of Li1.28Mn0.54Ni0.13Co0.02Al0.03O2 by using the Rietveld refinement method considering the R (Formula presented.) m and C2/m unit cells as the prototype structures. Here, the relative ability of a variety of structural models is compared to match the experimental diffraction pattern evaluating the impact of defects and supercells derived from the R (Formula presented.) m structure. To summarize, two possible models able to reconcile the description of experimental data are proposed here for the structure of Li1.28Mn0.54Ni0.13Co0.02Al0.03O2: namely a monoclinic C2/m defective lattice (prototype Li2MnO3) and a monoclinic defective supercell derived from the rhombohedral R (Formula presented.) m unit cell (prototype LiCoO2)
The PREFOS project: fiber optic monitoring system for prefabricated buildings
No full textStructural health monitoring (SHM) is a crucial aspect of understanding the safety of in-service civil engineering structures. Real-time monitoring offers an effective solution for the timely detection of defects and structural damages, facilitating focused routine maintenance and mitigating the need for costly extraordinary structural repairs. While various technologies have been developed to monitor structural safety, identifying and quantifying anomalies in different materials, many of them exhibit high intrusiveness and sensitivity to electromagnetic interferences. Therefore, a more convenient approach is to implement a sensor monitoring system during the industrial production of pre-cast reinforced concrete (RC) structures. Embedding sensors in pre-cast beams, columns, etc., during construction enables quality control, aiding in the early detection of defects that may compromise load capacity and durability. To address issues related to intrusiveness and electromagnetic interference, the PREFOS research project employs fiber optical systems (FOS), utilizing quasi-distributed Fiber Bragg Grating (FBG) technology sensors. FBG sensors are well-suited for both static and dynamic measurements, allowing for the monitoring of strains, displacements, and temperature variations. This approach ensures that the final precast elements are inherently ready for monitoring at the construction site, eliminating the need for subsequent instrumentation steps
A virtuous alliance between ecologists, taxonomists and citizens
No full textThe results of the study of lacewings collected in an ecological study project of urban forestation are interpreted in light of a perspective of multi-disciplinary collaboration with the involvement of citizens
Effective prediction of SnO2 conduction band edge potential: The key role of surface oxygen vacancies
Full text linkSeveral theoretical studies at different levels of theory have attempted to calculate the absolute position of the SnO2 conduction band, whose knowledge is key for its effective application in optoelectronic devices such us, for example, perovskite solar cells. However, the predicted band edges fall outside the experimentally measured range. In this work, we introduce a computational scheme designed to calculate the conduction band minimum values of SnO2, yielding results aligned with experiments. Our analysis points out the fundamental role of encompassing surface oxygen vacancies to properly describe the electronic profile of this material. We explore the impact of both bridge and in-plane oxygen vacancy defects on the structural and electronic properties of SnO2, explaining from an atomistic perspective the experimental observables. The results underscore the importance of simulating both types of defects to accurately predict SnO2 features and provide new fundamental insights that can guide future studies concerning design and optimization of SnO2-based materials and functional interfaces
A decade (2008-2017) of water stable isotope composition of precipitation at Concordia Station, East Antarctica
Full text linkA 10-year record of oxygen and hydrogen isotopic composition of precipitation is presented here: from 2008 to 2017, 1483 daily precipitation samples were collected year-round on a raised platform at Concordia Station, East Antarctica. Weather data were retrieved from the Italian Antarctic Meteo-Climatological Observatory automatic weather station (AWS), while ERA5 was used to estimate total precipitation. The δ-temperature relationships were moderately high for daily data (r2=0.63 and 0.64 for δ18O and δ2H, respectively) and stronger using monthly data (r2=0.82 for both δ18O and δ2H), with a slope of about 0.5 ‰ °C-1 for δ18O/TAWS (3.5 ‰ °C-1 for δ2H/TAWS), which remains consistent also using annual averages. The isotopic composition of precipitation is the input signal of the snow-ice system, and this dataset will be useful to improve the interpretation of paleoclimate records and promote a better understanding of the post-depositional processes affecting the isotopic signal in ice cores. This dataset represents a benchmark for the evaluation of isotope-enabled general circulation models. Here, the ECHAM6-wiso output was compared to experimental data, showing moderately good relationships for δ18O and δ2H but not for d-excess, nonetheless marking a substantial improvement from the previous release of the model