arXiv subjects

Lorenzo Malagutti

Publications and source records attributed to Lorenzo Malagutti.

5 recordsLinked to original sources

arXiv2025

Strong Enhancement of Electromagnetic Shower Development in Oriented Scintillating Crystals and Implications for Particle Detectors

A particle traversing a crystal aligned with one of its crystallographic axes experiences a strong electromagnetic field that is constant along the direction of motion over macroscopic distances. For $e^\pm$ and $γ$-rays with energies above a few $\mathrm{GeV}$, this field is amplified by the Lorentz boost, to the point of exceeding the Schwinger critical field $\mathcal{E}_0 \sim 1.32 \times 10^{16}~\mathrm{V/cm}$. In this regime, nonlinear quantum-electrodynamical effects occur, such as the enhancement of intense electromagnetic radiation emission and pair production, so that the electromagnetic shower development is accelerated and the effective shower length is reduced compared to amorphous materials. We have investigated this phenomenon in lead tungstate (PbWO$_4$), a high-$Z$ scintillator widely used in particle detection. We have observed a substantial increase in scintillation light at small incidence angles with respect to the main lattice axes. Measurements with $120$-$\mathrm{GeV}$ electrons and $γ$-rays between $5$ and $100~\mathrm{GeV}$ demonstrate up to a threefold increase in energy deposition in oriented samples. These findings challenge the current models of shower development in crystal scintillators and could guide the development of next-generation accelerator- and space-borne detectors.

hep-ex↗

arXiv2025

Apparatus for the measurement of birefringence maps of optical materials: the case of crystalline silicon for Einstein Telescope

Einstein Telescope (ET) is expected to achieve sensitivity improvements exceeding an order of magnitude compared to current gravitational-wave detectors. The rigorous characterization in optical birefringence of materials and coatings has become a critical task for next-generation detectors, especially since this birefringence is generally spatially non-uniform. A highly sensitive optical polarimeter has been developed at the Department of Physics and Earth Sciences of the University of Ferrara and INFN - Ferrara Section, Italy, aimed at performing two-dimensional birefringence mapping of substrates. In this paper we describe the design and working principle of the system and present results for crystalline silicon, a candidate material for substrates in the low-frequency (LF) interferometers of ET. We find that the birefringence is of order $10^{-7}$ for commercially available samples and is position dependent in the silicon (100)-oriented samples, with variations in both magnitude and axis orientation. We also measure the intrinsic birefringence of the (110) surface. Implications for the performance of gravitational-wave interferometers are discussed.

physics.optics↗

arXiv2025

High-Precision Alignment Techniques for Realizing an Ultracompact Electromagnetic Calorimeters Using Oriented high-Z Scintillator Crystals

Electromagnetic calorimeters used in high-energy physics and astrophysics rely heavily on high-Z inorganic scintillators, such as lead tungstate (PbWO4 or PWO). The crystalline structure and lattice orientation of inorganic scintillators are frequently underestimated in detector design, even though it is known that the crystalline lattice strongly modifies the features of the electromagnetic processes inside the crystal. A novel method has been developed for precisely bonding PWO crystals with aligned atomic planes within 100 μrad, exploiting X-ray diffraction (XRD) to accurately measure miscut angles. This method demonstrates the possibility to align a layer of crystals along the same crystallographic direction, opening a new technological path towards the development of next-generation electromagnetic calorimeters.

physics.ins-det↗

arXiv2025

FCC-ee positron source from conventional to crystal-based

The high-luminosity requirement in future lepton colliders imposes a need for a high-intensity positron source. In the conventional scheme, positron beams are obtained by the conversion of bremsstrahlung photons into electron-positron pairs through the interaction between a high-energy electron beam and a high-Z amorphous target. One method to enhance the number of produced positrons is by boosting the incident electron beam power. However, the maximum heat load and thermo-mechanical stresses bearable by the target severely limit the beam power of the incident electrons. To overcome these limitations, an innovative approach using lattice coherent effects in oriented crystals appears promising. This approach uses a single thick crystal that serves as a radiator and a converter. In this paper, we investigate the application of this scheme as an alternative to the conventional positron source at the Future Circular Collider (FCC-ee). Simulations were carried out from the positron production stage to the entrance of the damping ring to estimate the accepted positron yield. The results demonstrate the advantages of the crystal-based positron source: it requires thinner targets than the conventional scheme, resulting in a 14% reduction in the deposited power while achieving a 10% increase in accepted positron yield.

physics.acc-ph↗

arXiv2024

Particle identification capability of a homogeneous calorimeter composed of oriented crystals

Recent studies have shown that the electromagnetic shower induced by a high-energy electron, positron or photon incident along the axis of an oriented crystal develops in a space more compact than the ordinary. On the other hand, the properties of the hadronic interactions are not affected by the lattice structure. This means that, inside an oriented crystal, the natural difference between the hadronic and the electromagnetic shower profile is strongly accentuated. Thus, a calorimeter composed of oriented crystals could be intrinsically capable of identifying more accurately the nature of the incident particles, with respect to a detector composed only of non-aligned crystals. Since no oriented calorimeter has ever been developed, this possibility remains largely unexplored and can be investigated only by mean of numerical simulations. In this work, we report the first quantitative evaluation of the particle identification capability of such a calorimeter, focusing on the case of neutron-gamma discrimination. We demonstrate through Geant4 simulations that the use of oriented crystals significantly improves the performance of a Random Forest classifier trained on the detector data. This work is a proof that oriented calorimeters could be a viable option for all the environments where particle identification must be performed with a very high accuracy, such as future high-intensity particle physics experiments and satellite-based gamma-ray telescopes.

hep-ex↗