arXiv subjects

I. Viola

Publications and source records attributed to I. Viola.

7 recordsLinked to original sources

arXiv2026

Thin single-crystal perovskite detector for high-energy charged particles

The organometal halide perovskites (OMHP) semi-conductors have shown recently a strong potential as radiation detectors, beside the well-known success in photovoltaics and as photo-detectors. Many studies have been published on X-rays detection, and a few studies about detection of alpha, beta-particles and protons. Less literature is present for high energy charged particles. OMHP-based devices for tracking and real-time monitoring for high energy particles may offer many advantages. OMHPs can be directly grown on pixelated electronics, even on curved substrates, without the need of complex and expensive bump-bonding procedures. Moreover, OMHPs have shown self-healing features after radiation exposure, which makes them attractive for high-flux applications. In this paper we report a device based on a thin single OMHP crystal, about 150 mum thick, directly grown on a patterned substrate through dewetting technique, able to detect high-energy charged particles in a high dynamic range of incident fluxes. A dedicated electronics circuit has been developed to match the expected time characteristics of the OMHP crystals. This is the first demonstration of thin OMHP single crystals being able to detect high energy charged particles of hundreds of MeV.

physics.ins-det↗

arXiv2024

Micro and Nano 3D investigation of complex gut alterations-dementia interplay

Alzheimer's disease (AD), a debilitating neurodegenerative disorder, remains one of the foremost public health challenges of our time. Despite decades of research, its etiology largely remains enigmatic. Recently, attention has turned to the gut-brain axis, a complex network of communication between the gastrointestinal tract and the brain, as a potential player in the pathogenesis of AD. Here we exploited X-ray Phase Contrast Tomography to provide an in-depth analysis of the link between the gut condition and AD, exploring gut anatomy and structure in murine models. We conducted a comprehensive analysis by comparing the outcomes in various mouse models of cognitive impairment, including AD, frail mice, and frontotemporal dementia (FTD) affected mice. We discovered an association between substantial changes in the gut structure and the presence of amyloid-beta (A\b{eta}) in the brain. We found that the most important gut alterations are related to A\b{eta} occurrence in the brain. In particular, we investigated the gut morphology, the distribution of enteric micro-processes and neurons in the ileum. Understanding the intricate interplay between gut condition and dementia may open new avenues for early AD diagnosis and treatment offering hope for a future where these diseases may be more effectively addressed.

physics.app-ph↗

arXiv2022

Electrical switching of a chiral lasing from polariton condensate in a Rashba-Dresselhaus regime

Efficient optical classical and quantum information processing imposes on light novel requirements: chirality with low threshold non-linearities. In this work we demonstrate a chiral lasing from an optical modes due to emerging photonic Rashba-Dresselhaus spin-orbit coupling (SOC). For this purpose we developed a new electrically tunable device based on an optical cavity filled with birefringent liquid crystal (LC) and perovskite crystals. Our novel method for the growth of single crystals of CsPbBr$_3$ inorganic perovskite in polymer templates allows us to reach a strong light-matter coupling regime between perovskite excitons and cavity modes, and induce polariton condensation. The sensitivity of the LC to external electric fields lets us to tune the condensate energy in situ and induce synthetic SOC. This shapes the condensate between a single linearly polarized or two circularly polarized separated in momentum, emitting coherent light. The difference in the condensation thresholds between the two SOC regimes can be used to switch on and off the chiral condensate emission with a voltage.

physics.optics↗

arXiv2022

Immuno-Histo X-ray Phase Contrast Tomography: New 3D imaging technique for molecular tomography

The still unmet ability of following the fate of specific cells or molecules within the whole body would give an outstanding breakthrough in the comprehension of disease mechanisms and in the monitoring of therapeutic approaches. Our idea is to push forward the bio-nanotechnology to a level where it serves the most advanced 3D bio-medical imaging to provide a multi-scale imaging ranging from the whole organ down to the cellular level, enabling high-resolution visualization of disease-relevant cells within the whole disease-altered biological context. We present here the first proof-of-concept of a novel tomography procedure, Immuno-Histo-X-ray Phase Contrast Tomography (XPCT) that combines cutting-edge XPCT, which provides detailed image of the whole organ, with molecular imaging at the cellular level, identifying the relevant cells via an immunohistochemistry-based approach. We combine metal nanoparticles and a single-domain antibody that target relevant cells. Our results lay the foundation for a new generation of 3D-bio-medical X-ray imaging.

physics.app-ph↗

arXiv2015

Experimental evidence of replica symmetry breaking in random lasers

Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics, and many other research fields. According to this theory, identical systems under identical conditions may reach different states and provide different values for observable quantities. This effect is known as Replica Symmetry Breaking and is revealed by the shape of the probability distribution function of an order parameter named the Parisi overlap. However, a direct experimental evidence in any field of research is still missing. Here we investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, and we find that the distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking.

cond-mat.dis-nn↗

arXiv2014

Transition from non-resonant to resonant random lasers by the geometrical confinement of disorder

We report on a novel kind of transition in random lasers induced by the geometrical confinement of the emitting material. Different dye doped paper devices with controlled geometry are fabricated by soft-lithography and show two distinguished behaviors in the stimulated emission: in the absence of boundary constraints the energy threshold decreases for larger laser volumes showing the typical trend of diffusive {\it non-resonant} random lasers, while when the same material in lithographed into channels, the walls act as cavity and the {\it resonant} behavior typical of standard lasers is observed. The experimental results are consistent with the general theories of random and standard lasers and a clear phase diagram of the transition is reported.

physics.optics↗

arXiv2013

Random laser from engineered nanostructures obtained by surface tension driven lithography

The random laser emission from the functionalized thienyl-S,S-dioxide quinquethiophene (T5OCx) in confined patterns with different shapes is demonstrated. Functional patterning of the light emitter organic material in well defined features is obtained by spontaneous molecular self-assembly guided by surface tension driven (STD) lithography. Such controlled supramolecular nano-aggregates act as scattering centers allowing the fabrication of one-component organic lasers with no external resonator and with desired shape and efficiency. Atomic force microscopy shows that different geometric pattern with different supramolecular organization obtained by the lithographic process tailors the coherent emission properties by controlling the distribution and the size of the random scatterers.

physics.optics↗