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The experimental setup of the new measurement of 239Pu fission and capture cross-section in the n_TOF time-of-flight facility at CERN is presented. The measurement aims to address the needs and demands of nuclear data users. The experiment incorporates an innovative fast Fission Fragment Detector and the n_TOF Total Absorption Calorimeter, enabling the implementation of the fission tagging technique. Preliminary results exhibit the robust performance of the detector systems, along with the high quality of the new 239Pu samples. These samples were exclusively produced for this measurement by the European Commission’s Joint Research Centre in Geel.

Featured Application: An optical readout GEM-based detector based on a matrix of organic photodiodes with an active area of 60 × 80 mm2, called the LaGEMPix, was assembled and characterized, using low energy X-rays as a preliminary step toward the development of a 200 × 200 mm2 detector for use in Quality Assurance in hadron therapy. Quality Assurance (QA) in hadron therapy is crucial to ensure safe and accurate dose delivery to patients. This can be achieved with fast, reliable and high-resolution detectors. In this paper, we present a novel solution that combines a triple Gas Electron Multiplier (GEM) and a highly pixelated readout based on a matrix of organic photodiodes fabricated on top of an oxide-based thin-film transistor backplane. The first LaGEMPix prototype with an active area of 60 × 80 mm2 was developed and characterized using low energy X-rays. The detector comprises a drift gap of 3.5 mm, a triple-GEM stack for electron amplification, and a readout featuring 480 × 640 pixels at a 126 µm pitch. Here, we describe the measurements and results in terms of spatial resolution for various experimental configurations. A comparison with GAFCHROMIC® films and the GEMPix detector used in the charge readout mode was performed to better understand the contribution to the spatial resolution from both the electron diffusion and the isotropic emission of photons. The measurements were compared to Monte Carlo simulations, using the FLUKA code. The simulation predictions are in good agreement with the GEMPix results. Future plans with respect to applications in hadron therapy are discussed. [ABSTRACT FROM AUTHOR]

A reliable and highly scalable Internet of Things (IoT) end-to-end data infrastructure has been developed for environmental radiation monitoring at the European Organization for Nuclear Research (CERN) based on a low-power wide-area network (LPWAN). The proposed system, called Waste radiation MONitoring (W-MON), consists of an interconnected network of thousands of highly sensitive and ultralow-power gamma radiation sensors acting as long range (LoRa) transceivers. The aim of the system is to improve and automatize the radiological controls of conventional waste containers. The end devices measure the radiation levels in the waste containers on a continuous basis and send the data periodically to the LoRaWAN network server. The network has been deployed in an outdoor environment covering hundreds of hectares. A set of web-based user applications for real-time monitoring, data visualization, and status control of the devices have been designed based on open-source tools. The data pipeline infrastructure has been designed to allow an easy integration into the overall CERN Radiation and Environment Monitoring Unified Supervision service (REMUS). [ABSTRACT FROM AUTHOR]

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow of a gas mixture such as Ar:CO2:CF4, Ar:CO2 or propane-based tissue equivalent gas is supplied externally at a rate of 5 L/h. This article reviews the medical applications of the GEMPix. These include relative dose measurements in conventional photon radiation therapy and in carbon ion beams, by which on-line 2D dose images provided a similar or better performance compared to gafchromic films. Depth scans in a water phantom with 12C ions allowed measuring the 3D energy deposition and reconstructing the Bragg curve of a pencil beam. Microdosimetric measurements performed in neutron and photon fields allowed comparing dose spectra with those from Tissue Equivalent Proportional Counters and, additionally, to obtain particle track images. Some preliminary measurements performed to check the capabilities as the detector in proton tomography are also illustrated. The most important on-going developments are: (1) a new, larger area readout to cover the typical maximum field size in radiation therapy of 20 × 20 cm2; (2) a sealed and low-pressure version to facilitate measurements and to increase the equivalent spatial resolution for microdosimetry; (3) 3D particle track reconstruction when operating the GEMPix as a Time Projection Chamber. [ABSTRACT FROM AUTHOR]

Purpose: Commercially available systems for ion beam reference dosimetry in water are mainly based on ionization chambers. In those systems, a large number of small detectors are typically arranged in a two‐dimensional (2D) array or matrix to achieve high spatial resolution (order of several millimeters) and large field coverage at the same time. The goal of this work was to investigate the reliability of a detector of superior spatial resolution to perform three‐dimensional (3D) ionization measurements in carbon ion pencil beams. Methods: The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region (with 2.8 cm3 × 2.8 cm3 × 0.3 cm3 volume), three gas electron multipliers (GEMs) for signal amplification and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. An integrated system was designed and built, which consists of a commercial water phantom with a three‐axis motorized arm, a reference large‐area ionization chamber for signal normalization to the beam output and the GEMPix itself. Measurements at different depths in water have been performed at the Italian National Centre for Oncological Hadrontherapy (CNAO) with three carbon ion beam energies. Lateral beam profiles measured with the GEMPix at the shallowest depth were compared to those measured with radiochromic EBT3 films in air in the position of the reference ionization chamber. The Timepix readout was calibrated in energy by using one independent depth scan with carbon ions of 150 mm range. Bragg peak curves were also simulated using the Monte Carlo FLUKA code as a reference. Results: Beam profiles measured with the GEMPix were smooth and showed similar shape and full width at half maximum when compared to those measured with radiochromic EBT3 films. Smooth, reproducible Bragg curves were obtained with statistical uncertainties of about 2%, matching FLUKA simulations of the Bragg curves within 15% for most data points. This difference is partially explained for the measurement with carbon ions of 150 mm range by a saturation effect in the GEMs. The high granularity of the readout allowed to produce 2D images of the deposited dose at different depths, as well as 3D data distributions. Conclusions: This paper demonstrates the capability of the GEMPix detector to measure the 3D dose distribution of carbon ions in water for a clinical pencil beam reliably. In the future, the detector area will be increased to cover fields of scanned beams. Measurements at higher beam intensities and with protons are planned. [ABSTRACT FROM AUTHOR]

Hadron therapy is an advanced radiation modality for treating cancer, which currently uses protons and carbon ions. Hadrons allow for a highly conformal dose distribution to the tumour, minimising the detrimental side-effects due to radiation received by healthy tissues. Treatment with hadrons requires sub-millimetre spatial resolution and high dosimetric accuracy. This paper discusses the design, fabrication and performance tests of a detector based on Gas Electron Multipliers (GEM) coupled to a matrix of thin-film transistors (TFT), with an active area of 60 × 80 mm 2 and 200 ppi resolution. The experimental results show that this novel detector is able to detect low-energy (40 kVp X-rays), high-energy (6 MeV) photons used in conventional radiation therapy and protons and carbon ions of clinical energies used in hadron therapy. The GEM-TFT is a compact, fully scalable, radiation-hard detector that measures secondary electrons produced by the GEMs with sub-millimetre spatial resolution and a linear response for proton currents from 18 pA to 0.7 nA. Correcting known detector defects may aid in future studies on dose uniformity, LET dependence, and different gas mixture evaluation, improving the accuracy of QA in radiotherapy., (© 2024. The Author(s).)