Direct detection of 5-MeV protons by flexible organic thin-film devices

A Decade of Lead Halide Perovskites for Direct-Conversion X-ray and Gamma Detection: Technology Readiness Level and Challenges

Over the past decade, lead halide perovskites (LHPs) have become a vibrant thrust in the field of direct conversion X-ray and gamma-ray radiation detectors, offering promising cost-effective and robust alternatives to traditional semiconductors. This review article chronicles the significant strides made since the inception of this field, emphasizing the material, structural, and functional advancements. It begins with an overview of the fundamental properties of perovskites that render them suitable for high-energy radiation detection, such as their high atomic number, prominent charge carriers' mobility and lifetime, and high resistivity. The review highlights key developments in material synthesis and processing techniques that have enhanced these detectors' stability, efficiency, and scalability. Furthermore, the review discusses the evolution of device architectures from single-channel photodiodes to complex multi-pixel arrays for imaging applications. The conclusion is focused on the remaining challenges that hamper the immediate progression of LHP radiation detectors to higher technology levels. This review is intended as a resource for academic researchers and industry stakeholders, summarizing the first decade of LHP detectors and forecasting the trajectory of this promising field, while remembering that forecasting the future trajectory, though challenging, is guided by current technological trends.

A wearable tool for real-time dose monitoring during cancer radiation therapies

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 Radiation Beam Monitoring by Flexible Perovskite Thin Film Arrays

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.

Real-time single-proton counting with transmissive perovskite nanocrystal scintillators

High-sensitivity radiation detectors for energetic particles are essential for advanced applications in particle physics, astronomy and cancer therapy. Current particle detectors use bulk crystals, and thin-film organic scintillators have low light yields and limited radiation tolerance. Here we present transmissive thin scintillators made from CsPbBr3 nanocrystals, designed for real-time single-proton counting. These perovskite scintillators exhibit exceptional sensitivity, with a high light yield (~100,000 photons per MeV) when subjected to proton beams. This enhanced sensitivity is attributed to radiative emission from biexcitons generated through proton-induced upconversion and impact ionization. These scintillators can detect as few as seven protons per second, a sensitivity level far below the rates encountered in clinical settings. The combination of rapid response (~336 ps) and pronounced ionostability enables diverse applications, including single-proton tracing, patterned irradiation and super-resolution proton imaging. These advancements have the potential to improve proton dosimetry in proton therapy and radiography.

Large Scale BN-perovskite Nanocomposite Aerogel Scintillator for Thermal Neutron Detection

State-of-the-art thermal neutron scintillation detectors rely on rare isotopes for neutron capture, lack stability and scalability of solid-state scintillation devices, and poorly discriminate between the neutron and gamma rays. The boron nitride (BN)-CsPbBr₃ perovskite nanocomposite aerogel scintillator enables discriminative detection of thermal neutrons, features the largest known size (9 cm across), the lowest density (0.17 g cm^-3 ) among the existing scintillation materials, high BN (50%) perovskite (1%) contents, high optical transparency (85%), and excellent radiation stability. The new detection mechanism relies on thermal neutron capture by ¹⁰ B and effective energy transfer from the charged particles to visible-range scintillation photons between the densely packed BN and CsPbBr₃ nanocrystals. Low density minimizes the gamma ray response. The neutrons and gamma rays are discriminated by complete decoupling of the respective single pulses in time and intensity. These outcomes open new avenues for neutron detection in resource exploration, clean energy, environmental, aerospace, and homeland security applications.

Mixed 3D-2D Perovskite Flexible Films for the Direct Detection of 5 MeV Protons

This study reports on a novel, flexible, proton beam detector based on mixed 3D-2D perovskite films deposited by solution onto thin plastic foils. The 3D-2D mixture allows to obtain micrometer-thick and highly uniform films that constitute the detector's active layer. The devices demonstrate excellent flexibility with stable electric transport properties down to a bending radius of 3.1 mm. The detector is characterized under a 5 MeV proton beam with fluxes in the range [4.5 × 105 - 1.4 × 109 ] H+ cm-2 s-1 , exhibiting a stable response to repetitive irradiation cycles with sensitivity up to (290 ± 40) nC Gy-1 mm-3 and a limit of detection down to (72±2) µGy s-1 . The detector radiation tolerance is also assessed up to a total of 1.7 × 1012 protons impinging on the beam spot area, with a maximum variation of the detector's response of 14%.