Laura Basiricò

Several large particle physics experiments rely on scintillation light emitted by liquefied noble gases to detect ionizing radiation. This vacuum‐ultraviolet light is commonly converted to visible light by wavelength‐shifting coatings on photon detectors. Materials combining a large Stokes shift, scalable large‐area fabrication, and cryogenic robustness remain limited. Here we demonstrate solution‐processed Mn‐doped PEA ₂ PbBr ₄ thin films as a wavelength shifter for liquid Ar scintillation readout. Mn incorporation converts the native excitonic emission into a Mn ²⁺ emission band centered at ∼620 nm, providing a large Stokes shift that suppresses reabsorption and shifts the emission to the region of maximum SiPM sensitivity. Cryogenic operation is supported by temperature‐dependent photoluminescence, showing a ∼70% increase in integrated emission at 80K, with preserved film morphology after repeated liquid‐nitrogen thermal shocks and no measurable photobleaching under intense 337 nm pulsed irradiation. Under 265 nm excitation, the Mn‐doped films deliver an effective photon conversion efficiency of (100 ± 20)% (λ _em ≈ 620 nm), lower than state‐of‐the‐art TPB reference films ((150 ± 10)%, λ _em ≈ 420 nm). Despite this, PEA ₂ PbBr ₄ offers scalable large‐area solution processing and superior cryogenic morphological stability compared with TPB, supporting its potential as a wavelength shifter for cryogenic scintillation detection.

Within the framework of the INFN-CSN5 PROVIDE experiment, we fabricated planar detectors by depositing 1-μm-thick films using radio-frequency magnetron sputtering (RF-MS). These films were grown on both commercial and in-house substrates featuring various interdigitated electrode (IDE) geometries on both rigid and flexible platforms. Our characterization revealed that key detector parameters — including an effective room-temperature resitivity ρ ≈ 10 ⁷ Ω cm and a mobility-lifetime product μτ ≈ 2 × 10 ^-7 cm ² /V, derived from a Hecht-expression best-fit under 450 nm UV LED irradiation, remained consistent regardless of the substrate type or electrode configuration. Furthermore, we measured a responsivity of approximately 0.2 A/W for optical powers up to at 450 nm. We also prototyped optimized, fully in-house detectors consisting of thin films grown by the Firenze Unit on flexible Kapton substrates, which were equipped with Cr/Au IDEs produced via lithography and thermal evaporation by the Bologna Unit. When exposed to a 300 ps UV (355 nm) laser pulse, these devices demonstrated a fast response with a 1 ns rise time and slew rates of up to 0.14 V/ns, depending on the applied bias. These performances, comparable to reference silicon photodiodes, will possibly open the way to a new class of high-speed thin-film radiation detectors. The results will be further exploited in the near future for advanced high-energy photon and particle detection.

Large volumes of liquid argon or xenon constitute an excellent medium for the detection of Neutrino interactions and for Dark Matter searches. Traditionally, noble liquid detectors use scintillation light for a timing or calorimetric signal, read out in a time projection chamber configuration, where the liquid is permeated by an electric field. A direct optical reconstruction of the events though the imaging of scintillation light may offer an alternative to charge collection, removing the need for an electric drift field and the associated high-voltage hardware. Using finely segmented silicon photomultipliers arrays and a suitable optical system, it becomes possible to construct cameras that effectively “photograph” the primary scintillation light. A major challenge arises from the fact that both argon and xenon scintillate in the vacuum-ultraviolet range. To address this, we employ coded aperture masks in place of traditional lenses, enabling thin cameras with wide and deep field of view. A reconstruction algorithm based on Maximum Likelihood Expectation Maximization has been developed to obtain a 3D map of energy deposition, outperforming traditional deconvolution techniques in simulation under low-light conditions. The latest results from simulation and reconstruction of neutrino interactions in a liquid argon detector equipped with these cameras will be presented.

Robust, flexible, and scalable detectors for ionizing radiation are critically needed in advanced medical, environmental, and aerospace applications. Here, a polymer–perovskite composite fabricated by mechanical sintering is studied, which enables the production of thick (up to 0.5 mm) free‐standing pellets. They are used in novel vertical detector architecture, with efficient charge collection, which fully exploits the large interaction volume with ionizing radiation, obtaining a low limit of detection of (37.2 ± 1.1) nGy s ⁻¹ . The hybrid matrix ensures excellent radiation hardness and long‐term operational stability preserving device properties over months. The addition of polymer not only enhances the device stability, but also confers mechanical robustness, enabling the thick perovskite‐based detectors to maintain unchanged photoconductivity under extreme bending conditions (1 mm radius, >10% strain), challenging the conventional trade‐off between thickness and flexibility. Additionally, we demonstrate direct detection of 5 MeV proton beam, obtaining a sensitivity of (9.3 ± 0.2)∙10 ⁻¹⁸ C/H ⁺ with an applied electric field of 2 V µm ⁻¹ . Moreover, we show the possibility of further sensitivity improvement by tuning the active layer thickness to maximize energy deposition. Overall, these results establish a scalable and conformable platform for next‐generation radiation detectors, offering a unique combination of structural robustness, stability, and sensitivity to different kinds of radiation.

Two-dimensional (2D) hybrid perovskite thin films have emerged as promising candidates for high-performance optoelectronic devices, including ionizing radiation detectors, due to their unique layered structure, favorable charge transport properties, and compatibility with low-temperature, solution-based fabrication. In this work, we investigate the role of film morphology (specifically thickness, roughness, and grain size) on the electrical and detection performance of flexible X-ray detectors based on PEA ₂ PbBr ₄ (phenethylammonium lead bromide) perovskite films. Devices were fabricated using a vertical stacked architecture with solution-processed films deposited from solution by spin coating. We systematically tuned film morphology by varying spin-coating speed and precursor concentration. Our results show that while thicker films improve X-ray absorption and sensitivity due to a higher attenuation fraction, they also suffer from increased roughness and reduced charge transport efficiency. Conversely, thinner films exhibit enhanced conductivity and charge collection due to better uniformity and crystallinity, despite their lower intrinsic sensitivity. A trade-off between film compactness and detection performance was also observed when modifying the solution concentration. These findings underscore the critical importance of optimizing film morphology and device architecture to achieve high-performance, flexible perovskite-based X-ray photodetectors. Graphical abstract

2D hybrid perovskites are a novel and promising class of semiconductors for the realization of direct fast neutron detectors because they combine excellent transport properties with a large organic cation, rich in low‐Z elements, which strongly interacts with fast neutrons. Here, this study presents the employment of PEA ₂ PbBr ₄ (PEA = C ₆ H ₅ C ₂ H ₄ NH ₃ ⁺ ) thin films for the direct detection of fast neutrons. By tuning the perovskite deposition process, it achieves a stable and reproducible response capable to monitor in real‐time the flux of fast neutrons (energy = [1–4] MeV; beam flux = [0.4–3] · 10 ⁵ n s ⁻¹ cm ⁻² ) by providing an output electrical signal proportional to the radiation field intensity. Finally, the employment of a thin film‐based device boosts the discrimination capability of this technology and offers the possibility to realize a flexible and easy‐scalable detecting system very appealing for the development of wearable personal dosimeters.

We report on a wearable, human tissue-equivalent, real-time dosimeter designed to quantitatively monitor radiation absorbed by patients during cancer treatments. The fully organic device has been characterized under actual clinical conditions using a high-energy proton beam and an anthropomorphic phantom, with the aim to simulate a prostate cancer proton therapy treatment. We achieved a full control over the dosimeter operation, and we verified its linear response with the received dose. We demonstrate that, by a proper functionalization of the polysiloxane-based scintillator, it is possible to target the effective detection of different kinds of ionizing radiation. Specifically, besides protons, we develop a device able to detect thermal neutrons, targeting its use during Boron Neutron Capture Therapy. This work demonstrates how organic indirect detectors can be considered a universal radiation detecting platform able to monitor in real time and in situ the dose absorbed by patients during cancer treatments under different kinds of radiation.

Real‐time and in‐line transversal monitoring of ionizing radiation beams is a crucial task for several applications which span from medical treatments to particle accelerators in high energy physics. Here a flexible and large area device based on 2D hybrid perovskite thin films (phenylethylammonium lead bromide), fabricated onto a thin flexible polyimide substrate, able to map the transversal beam profile of high energy radiation beams is reported. The performance of this novel tool is here compared with the one offered by standard commercial large‐area technology, namely radiochromic sheets. The great potential of this class of devices is demonstrated by successfully mapping in real‐time a 5 MeV proton beam at fluxes between 10⁸ and 10¹⁰ H⁺ s⁻¹ cm⁻², confirming the capability to operate in a radiation‐harsh environment without output signal saturation issues. The versatility and scalability of here proposed detecting system are demonstrated by the development of a multipixel array able to map in real‐time a 40 kVp X‐ray beam spot (dose rate 8 mGy s⁻¹). Perovskite thin film‐based detectors are thus assessed as a very promising class of thin, flexible devices for real‐time, in‐line, large‐area, conformable, reusable, transparent, and low‐cost transversal beam monitoring of different ionizing radiation.

On‐line in situ monitoring of radiation emitted by radiotracers during intravenous injection is of crucial importance for the safety of patients and personnel involved in nuclear medicine treatments and analysis. The aim of this work is to assess wearable perovskite ionizing radiation detectors for such application. With this purpose pixelated direct detector based on thin films of 2D layered perovskite PEA ₂ PbBr ₄ are tested for the monitoring of gamma‐rays emitted by ¹⁸ F radiopharmaceutical under different experimental conditions. The wearable detector is here demonstrated being able to detect in real‐time the gamma‐rays emitted by annihilation of ¹⁸ F radiotracer. Its reliability is assessed by ¹⁸ F half‐life measurement with a maximum accuracy deviation within 8%. The detector also successes in its validation for the foreseen application, demonstrating able to monitor in real‐time the whole injection process and extravasation event.