Archivio della ricerca - Fondazione Bruno Kessler
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The phenomenon of abortion in foreign women living in Northern Italy: a retrospective cohort epidemiological study
No full textSegmented SiPM Readout for Cherenkov Time-of-Flight Positron Emission Tomography Detectors Based on Bismuth Germanate
No full textPositron emission tomography (PET) is the most sensitive biomedical imaging modality for noninvasively detecting and visualizing positron-emitting radiopharmaceuticals within a subject. In PET, measuring the time-of-flight (TOF) information for each pair of 511 keV annihilation photons improves effective sensitivity but requires high timing resolution. Hybrid materials that emit both scintillation and Cherenkov photons, such as bismuth germanate, recently offer the potential for more precise timing information from Cherenkov photons while maintaining adequate energy resolution from scintillation photons. However, a significant challenge in using such hybrid materials for TOF PET applications lies in the event-dependent timing spread caused by the mixed detection of Cherenkov and scintillation photons due to relatively lower production of Cherenkov photons. This study introduces an innovative approach by segmenting silicon photomultiplier (SiPM) pixels coupled to a single crystal, rather than using traditional SiPMs that are as large as or larger than the crystals they read. We demonstrated that multiple timestamps and photon counts obtained from the segmented SiPM can classify events by providing temporal photon density, effectively addressing this challenge. The approach and findings would lead to new opportunities in applications that require precise timing and photon counting
Levitated Ferromagnetic Magnetometer with Energy Resolution Well Below ħ
No full textA quantum limit on the measurement of magnetic fields has been recently pointed out, stating that the so-called energy resolution ER is bounded to ER≳ħ. This limit indeed holds true for the vast majority of existing quantum magnetometers, including superconducting quantum interference devices and solid state spin and optically pumped atomic magnetometers. However, it can be surpassed by highly correlated spin systems, as recently demonstrated with a single-domain spinor BEC. Here, we show that similar and potentially much better resolution can be achieved with a hard ferromagnet levitated above a superconductor at cryogenic temperature. We demonstrate ER=(0.064±0.010) ħ and anticipate that ER<10−3 ħ is within reach with near-future improvements. This finding opens the way to new applications in condensed matter, biophysics, and fundamental science. In particular, we propose an experiment to search for axionlike dark matter and project a sensitivity that is orders of magnitude better than in previous searches
Integration of germanium-vacancy single photon emitters arrays in diamond nanopillars
Get PDFThe nanoscale fabrication of μm-spaced single-photon emitter arrays is crucial for the development of integrated photonic chips. We report on the fabrication and systematic characterization of germanium-vacancy (GeV) color centers arrays in diamond obtained upon ion implantation at the nanoscale. Ge2+ ion implantations at 35 keV and 70 keV energies were carried out using a focused ion beam (FIB) equipped with a liquid metal alloy ion source. The arrays of emitters are subsequently aligned to ø300 nm nanopillar waveguiding structures, fabricated using a combination of electron-beam lithography and plasma etching. The photon collection efficiency and photoluminescence (PL) signal-to-background ratio increased by a factor 8 with respect to the unstructured sample. The photophysical properties of the GeV emitters fabricated by this approach were unaltered with respect to those found in unprocessed diamond. The efficiency of the overall manufacturing process to fabricate individual GeV centers was assessed. Up to 33% of the fabricated nanopillars, depending on ion implantation parameters, were found to contain single emitters
RF Sputtering of Gold Nanoparticles in Liquid and Direct Transfer to Nafion Membrane for PEM Water Electrolysis
No full textSputtering onto liquids is rapidly gaining attention for the green and controlled dry synthesis of ultrapure catalysts nanomaterials. In this study, we present a clean and single-step method for the synthesis of gold nanoparticles directly in polyethylene glycol (PEG) liquid using radio frequency (RF) magnetron sputtering and by subsequently transferring them to Nafion ionomer, fabricating a catalyst-coated membrane (CCM), an essential component of the proton exchange membrane water electrolyzer (PEMWE). The samples were systematically characterized at different stages of process development. The innovative transfer process resulted in a monodispersed homogeneous distribution of catalyst particles inside CCM while retaining their nascent nanoscale topography. The chemical analysis confirmed the complete removal of the trapped PEG through the process optimization. The electrochemical catalytic activity of the optimized CCM was verified, and the hydrogen evolution reaction (HER) in acidic media appeared outstanding, a vital step in water electrolysis toward H2 production. Therefore, this first study highlights the advantages of RF sputtering in liquid for nanoparticle synthesis and its direct application in preparing CCM, paving the way for the development of innovative membrane preparation techniques for water electrolysis
Leveraging Gamification to Address Child Sexual Abuse: A Preliminary Evaluation of the Cesagram Platform
No full textChild Sexual Abuse (CSA) remains a critical global issue, with the rise of online grooming posing new threats to young people’s safety. This paper presents the Cesagram platform, a gamified digital platform designed to prevent CSA by raising awareness of online grooming among children aged 11-14. The platform integrates interactive learning activities within a narrative-driven environment, featuring customizable avatars and four thematic districts. The effectiveness of the Cesagram platform combined with theoretical content was evaluated through 11 workshops involving 195 students
from Lithuania and Greece, utilizing pre- and post-workshop questionnaires. Findings indicate that the workshops effectively improved participants’ knowledge of CSA and grooming, while also
promoting user engagement. This study underscores the potential of gamification in sensitive educational contexts, contributing to digital well-being and safety education
Comparison of Credential Status Mechanisms for the Digital Wallet Ecosystem
No full textDigital identity wallets enable citizens to verify their identity and manage digital credentials. A system that offers the possibility of using and presenting credentials, requires the ability to check for their validity, avoiding the use of revoked or suspended credentials. This paper compares traditional and emerging credential status mechanisms to identify the most suitable solutions for the wallet ecosystem, taking in consideration privacy aspects and the set of available features
Alpha particle production from novel targets via laser-driven proton-boron fusion
No full textNovel targets were implemented in the beam-driven (in-target) proton-boron fusion with beneficial characteristics (chemical composition and density) compared to the commonly used boron nitride. A fusion-generated alpha particle flux of up to (5×107sr−1J−1) was generated via the proton-boron fusion reactions when irradiating the targets with a moderate laser system (10J, 800fs, 1019Wcm−2). Normalized by laser energy, the alpha particle flux generated in this experiment is comparable with the highest alpha particle yields reported in the literature. We present experimental results with supporting simulations and calculations of the expected alpha particle yield
{SHADES}: Towards a Multilingual Assessment of Stereotypes in Large Language Models
No full textLarge Language Models (LLMs) reproduce and exacerbate the social biases present in their training data, and resources to quantify this issue are limited. While research has attempted to identify and mitigate such biases, most efforts have been concentrated around English, lagging the rapid advancement of LLMs in multilingual settings. In this paper, we introduce a new multilingual parallel dataset SHADES to help address this issue, designed for examining culturally-specific stereotypes that may be learned by LLMs. The dataset includes stereotypes from 20 regions around the world and 16 languages, spanning multiple identity categories subject to discrimination worldwide. We demonstrate its utility in a series of exploratory evaluations for both “base” and “instruction-tuned” language models. Our results suggest that stereotypes are consistently reflected across models and languages, with some languages and models indicating much stronger stereotype biases than others