Ljungvall, J., Perez-Vidal, R. M., Lopez-Martens, A., Michelagnoli, C., Clement, E., Dudouet, J., et al. (2020). Performance of the Advanced GAmma Tracking Array at GANIL. Nucl. Instrum. Methods Phys. Res. A, 955, 163297–13pp.
Abstract: The performance of the Advanced GAmma Tracking Array (AGATA) at GANIL is discussed, on the basis of the analysis of source and in-beam data taken with up to 30 segmented crystals. Data processing is described in detail. The performance of individual detectors are shown. The efficiency of the individual detectors as well as the efficiency after gamma-ray tracking are discussed. Recent developments of gamma-ray tracking are also presented. The experimentally achieved peak-to-total is compared with simulations showing the impact of back-scattered gamma rays on the peak-to-total in a gamma-ray tracking array. An estimate of the achieved position resolution using the Doppler broadening of in-beam data is also given. Angular correlations from source measurements are shown together with different methods to take into account the effects of gamma-ray tracking on the normalization of the angular correlations.
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Capra, S., Mengoni, D., Dueñas, J. A., John, P. R., Gadea, A., Aliaga, R. J., et al. (2019). Performance of the new integrated front-end electronics of the TRACE array commissioned with an early silicon detector prototype. Nucl. Instrum. Methods Phys. Res. A, 935, 178–184.
Abstract: The spectroscopic performances of the new integrated ASIC (Application-Specific Integrated Circuit) preamplifiers for highly segmented silicon detectors have been evaluated with an early silicon detector prototype of the TRacking Array for light Charged Ejectiles (TRACE). The ASICS were mounted on a custom-designed PCB (Printed Circuit Board) and the detector plugged on it. Energy resolution tests, performed on the same detector before and after irradiation, yielded a resolution of 21 keV and 33 keV FWHM respectively. The output signals were acquired with an array of commercial 100-MHz 14-bit digitizers. The preamplifier chip is equipped with an innovative Fast-Reset device that has two functions: it reduces dramatically the dead time of the preamplifier in case of saturation (from milliseconds to microseconds) and extends the spectroscopic dynamic range of the preamplifier by more than one order of magnitude. Other key points of the device are the low noise and the wide bandwidth.
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Valiente-Dobon, J. J. et al, Egea, J., Huyuk, T., Gadea, A., Aliaga, R., Jurado-Gomez, M. L., et al. (2019). NEDA-NEutron Detector Array. Nucl. Instrum. Methods Phys. Res. A, 927, 81–86.
Abstract: The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.
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Llosa, G. (2019). SiPM-based Compton cameras. Nucl. Instrum. Methods Phys. Res. A, 926, 148–152.
Abstract: Compton cameras have been developed for almost fifty years in various fields (astronomy, medical imaging, safety and industrial inspections, etc.), employing different types of detectors. Their potential use has gained renewed interest with the emergence of high light yield scintillator crystals and silicon photomultipliers (SiPMs). This combination provides good performance and operation simplicity at an affordable cost, raising again the interest in this type of systems. SiPM-based Compton cameras are being assessed for diverse applications with promising results.
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Azevedo, C. D. R., Baeza, A., Chauveau, E., Corbacho, J. A., Diaz, J., Domange, J., et al. (2023). Design, setup and routine operation of a water treatment system for the monitoring of low activities of tritium in water. Nucl. Eng. Technol., 55(7), 2349–2355.
Abstract: In the TRITIUM project, an on-site monitoring system is being developed to measure tritium (3H) levels in water near nuclear power plants. The quite low-energy betas emitted by 3H have a very short average path in water (5 mm as shown by simulations for 18 keV electrons). This path would be further reduced by impurities present in the water, resulting in a significant reduction of the detection efficiency. Therefore, one of the essential requirements of the project is the elimination of these impurities through a filtration process and the removal of salts in solution. This paper describes a water treatment system developed for the project that meets the following requirements: the water produced should be of nearpure water quality according to ISO 3696 grade 3 standard (conductivity < 10 mS/cm); the system should operate autonomously and be remotely monitored.
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Liang, J., Singh, B., McCutchan, E. A., Dillmann, I., Birch, M., Sonzogni, A. A., et al. (2020). Compilation and Evaluation of Beta-Delayed Neutron Emission Probabilities and Half-Lives for Z > 28 Precursors. Nucl. Data Sheets, 168, 1–116.
Abstract: We present a compilation and evaluation of experimental beta-delayed neutron emission probabilities (P-n) and half-lives (T-1/2) for known or potential beta-delayed neutron precursors with atomic number Z > 28 (Cu-73 – Fr-233). This article includes the recommended values of both of these quantities, together with a compilation of experimental measurements when available. Some notable cases, as well as proposed standards for beta-delayed neutron measurements are also discussed. Evaluated data has also been compared to systematics using three different approaches. The literature cut-off date for this work is August 15, 2020.
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Fernandez, A., Hufschmidt, D., Colaux, J. L., Valiente-Dobon, J. J., Godinho, V., Jimenez de Haro, M. C., et al. (2020). Low gas consumption fabrication of He-3 solid targets for nuclear reactions. Mater. Des., 186, 108337–10pp.
Abstract: Nanoporous solids that stabilize trapped gas nanobubbles open new possibilities to fabricate solid targets for nuclear reactions. A methodology is described based on the magnetron sputtering (MS) technique operated under quasistatic flux conditions to produce such nanocomposites films with He-3 contents of up to 16 at.% in an amorphous-silicon matrix. In addition to the characteristic low pressure (3-6 Pa) needed for the gas discharge, the method ensures almost complete reduction of the process gas flow during film fabrication. The method could produce similar materials to those obtained under classical dynamic flux conditions for MS. The drastic reduction (>99.5%) of the gas consumption is fundamental for the fabrication of targets with scarce and expensive gases. Si:He-3 and W:He-3 targets are presented together with their microstructural (scanning and transmission electron microscopy, SEM and TEM respectively) and compositional (Ion Beam Analysis, IBA) characterization. The He-3 content achieved was over 1 x 10(18) at/cm(2) for film thicknesses between 1.5 and 3 μm for both Si and W matrices. First experiments to probe the stability of the targets for nuclear reaction studies in inverse kinematics configurations are presented.
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Carrasco-Ribelles, L. A., Pardo-Mas, J. R., Tortajada, S., Saez, C., Valdivieso, B., & Garcia-Gomez, J. M. (2021). Predicting morbidity by local similarities in multi-scale patient trajectories. J. Biomed. Inform., 120, 103837–9pp.
Abstract: Patient Trajectories (PTs) are a method of representing the temporal evolution of patients. They can include information from different sources and be used in socio-medical or clinical domains. PTs have generally been used to generate and study the most common trajectories in, for instance, the development of a disease. On the other hand, healthcare predictive models generally rely on static snapshots of patient information. Only a few works about prediction in healthcare have been found that use PTs, and therefore benefit from their temporal dimension. All of them, however, have used PTs created from single-source information. Therefore, the use of longitudinal multi-scale data to build PTs and use them to obtain predictions about health conditions is yet to be explored. Our hypothesis is that local similarities on small chunks of PTs can identify similar patients concerning their future morbidities. The objectives of this work are (1) to develop a methodology to identify local similarities between PTs before the occurrence of morbidities to predict these on new query individuals; and (2) to validate this methodology on risk prediction of cardiovascular diseases (CVD) occurrence in patients with diabetes. We have proposed a novel formal definition of PTs based on sequences of longitudinal multi-scale data. Moreover, a dynamic programming methodology to identify local alignments on PTs for predicting future morbidities is proposed. Both the proposed methodology for PT definition and the alignment algorithm are generic to be applied on any clinical domain. We validated this solution for predicting CVD in patients with diabetes and we achieved a precision of 0.33, a recall of 0.72 and a specificity of 0.38. Therefore, the proposed solution in the diabetes use case can result of utmost utility to secondary screening.
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Barrientos, L., Borja-Lloret, M., Casaña, J. V., Dendooven, P., Garcia Lopez, J. G., Hueso-Gonzalez, F., et al. (2024). Gamma-ray sources imaging and test-beam results with MACACO III Compton camera. Phys. Medica, 117, 103199–10pp.
Abstract: Hadron therapy is a radiotherapy modality which offers a precise energy deposition to the tumors and a dose reduction to healthy tissue as compared to conventional methods. However, methods for real-time monitoring are required to ensure that the radiation dose is deposited on the target. The IRIS group of IFIC-Valencia developed a Compton camera prototype for this purpose, intending to image the Prompt Gammas emitted by the tissue during irradiation. The system detectors are composed of Lanthanum (III) bromide scintillator crystals coupled to silicon photomultipliers. After an initial characterization in the laboratory, in order to assess the system capabilities for future experiments in proton therapy centers, different tests were carried out in two facilities: PARTREC (Groningen, The Netherlands) and the CNA cyclotron (Sevilla, Spain). Characterization studies performed at PARTREC indicated that the detectors linearity was improved with respect to the previous version and an energy resolution of 5.2 % FWHM at 511 keV was achieved. Moreover, the imaging capabilities of the system were evaluated with a line source of 68Ge and a point-like source of 241Am-9Be. Images at 4.439 MeV were obtained from irradiation of a graphite target with an 18 MeV proton beam at CNA, to perform a study of the system potential to detect shifts at different intensities. In this sense, the system was able to distinguish 1 mm variations in the target position at different beam current intensities for measurement times of 1800 and 600 s.
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Oliver, S., Rodriguez Bosca, S., & Gimenez-Alventosa, V. (2024). Enabling particle transport on CAD-based geometries for radiation simulations with penRed. Comput. Phys. Commun., 298, 109091–11pp.
Abstract: Geometry construction is a fundamental aspect of any radiation transport simulation, regardless of the Monte Carlo code being used. Typically, this process is tedious, time-consuming, and error-prone. The conventional approach involves defining geometries using mathematical objects or surfaces. However, this method comes with several limitations, especially when dealing with complex models, particularly those with organic shapes. Furthermore, since each code employs its own format and methodology for defining geometries, sharing and reproducing simulations among researchers becomes a challenging task. Consequently, many codes have implemented support for simulating over geometries constructed via Computer-Aided Design (CAD) tools. Unfortunately, this feature is lacking in penRed and other PENELOPE physics-based codes. Therefore, the objective of this work is to implement such support within the penRed framework. New version program summary Program Title: Parallel Engine for Radiation Energy Deposition (penRed) CPC Library link to program files: https://doi.org/10.17632/rkw6tvtngy.2 Developer's repository link: https://github.com/PenRed/PenRed Code Ocean capsule: https://codeocean.com/capsule/1041417/tree Licensing provisions: GNU Affero General Public License v3 Programming language: C++ standard 2011. Journal reference of previous version: V. Gimenez-Alventosa, V. Gimenez Gomez, S. Oliver, PenRed: An extensible and parallel Monte-Carlo framework for radiation transport based on PENELOPE, Computer Physics Communications 267 (2021) 108065. doi:https://doi.org/10.1016/j.cpc.2021.108065. Does the new version supersede the previous version?: Yes Reasons for the new version: Implements the capability to simulate on CAD constructed geometries, among many other features and fixes. Summary of revisions: All changes applied through the code versions are summarized in the file CHANGELOG.md in the repository package. Nature of problem: While Monte Carlo codes have proven valuable in simulating complex radiation scenarios, they rely heavily on accurate geometrical representations. In the same way as many other Monte Carlo codes, penRed employs simple geometric quadric surfaces like planes, spheres and cylinders to define geometries. However, since these geometric models offer a certain level of flexibility, these representations have limitations when it comes to simulating highly intricate and irregular shapes. Anatomic structures, for example, require detailed representations of organs, tissues and bones, which are difficult to achieve using basic geometric objects. Similarly, complex devices or intricate mechanical systems may have designs that cannot be accurately represented within the constraints of such geometric models. Moreover, when the complexity of the model increases, geometry construction process becomes more difficult, tedious, time-consuming and error-prone [2]. Also, as each Monte Carlo geometry library uses its own format and construction method, reproducing the same geometry among different codes is a challenging task. Solution method: To face the problems stated above, the objective of this work is to implement the capability to simulate using irregular and adaptable meshed geometries in the penRed framework. This kind of meshes can be constructed using Computer-Aided Design (CAD) tools, the use of which is very widespread and streamline the design process. This feature has been implemented in a new geometry module named “MESH_BODY” specific for this kind of geometries. This one is freely available and usable within the official penRed package1. It can be used since penRed version 1.9.3b and above.
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