Lerendegui-Marco, J., Cisterna, G., Hallam, J., Babiano-Suarez, V., Balibrea-Correa, J., Calvo, D., et al. (2025). Imaging neutrons with a position-sensitive monolithic CLYC detector. Nucl. Instrum. Methods Phys. Res. A, 1079, 170594–12pp.
Abstract: In this work, we have developed and characterized a position-sensitive CLYC detector that acts as the neutron imaging layer and y-ray Compton scatterer of the novel dual Gamma-ray and Neutron Vision (GN-Vision) system, which aims at simultaneously obtaining information about the spatial origin of y-ray and neutron sources. We first investigated the performance of two large 50 x 50 mm2 monolithic CLYC crystals, 8 and 13 mm thick respectively, coupled to a pixelated SiPM in terms of energy resolution and neutron-gamma discrimination. The response of two different 95% 6Li-enriched CLYC detectors coupled to an array of 8 x 8 SiPMs was studied in comparison to the results of a conventional photo-multiplier tube. An energy resolution of about 6% with PMT and 8% with SiPMs for the 137Cs peak and a figure of merit of 3-4 for the neutron-gamma discrimination have been obtained. The spatial response of the CLYC-SiPM detector to y-rays and neutrons has also been characterized using charge modulation-based multiplexing techniques based on a diode-coupled charge division circuit. Average resolutions close to 5 mm FWHM with good linearity are obtained in the transverse crystal plane. Last, this work presents the first proof-of-concept experiments of the neutron imaging capability using a neutron pinhole collimator attached to the developed position sensitive CLYC detector.
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Babiano-Suarez, V., Balibrea-Correa, J., Ladarescu, I., Lerendegui-Marco, J., & Domingo-Pardo, C. (2025). A computer-vision aided Compton-imaging system for radioactive waste characterization and decommissioning of nuclear power plants. Nucl. Instrum. Methods Phys. Res. A, 1076, 170449–14pp.
Abstract: Nuclear energy production is inherently tied to the management and disposal of radioactive waste. Enhancing classification and monitoring tools is therefore crucial, with significant socioeconomic implications. This paper reports on the applicability and performance of a high-efficiency, cost-effective and portable Compton camera for detecting and visualizing low-and medium-level radioactive waste from the decommissioning and regular operation of nuclear power plants. The results demonstrate the good performance of Compton imaging for this type of application, both in terms of image resolution and reduced measuring time. A technical readiness level of TRL7 has been thus achieved with this system prototype, as demonstrated with dedicated field measurements carried out at the radioactive-waste disposal plant of El Cabril (Spain) utilizing a pluarility of radioactive-waste drums from decomissioned nuclear power plants. The performance of the system has been enhanced by means of computer-vision techniques in combination with advanced Compton-image reconstruction algorithms based on Maximum-Likelihood Expectation Maximization. Finally, we also show the feasibility of 3D tomographic reconstruction from a series of relatively short measurements around the objects of interest. The potential of this imaging system to enhance nuclear waste management makes it a promising innovation for the nuclear industry.
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Perkowski, J. et al, Babiano-Suarez, V., Balibrea-Correa, J., Domingo-Pardo, C., Ladarescu, I., & Lerendegui-Marco, J. (2024). Multi-section fission ionization chamber for measurement of 239Pu(n, γ) reaction in fission tagging method. Nucl. Instrum. Methods Phys. Res. A, 1067, 169649–8pp.
Abstract: The Pu-239(n, gamma) reaction cross section is very important for operation of both thermal and fast reactors, when loaded with MOX fuels. According to the NEA/OECD High Priority Request List the precision of cross section data for this reaction should be improved. The cross section of (n, f) reaction is much higher compared to (n, gamma) for this isotope. In such conditions the fission tagging technique could be applied to identify the fission background. In the past, this technique was successfully used for capture measurements at the nTOF facility at CERN. The multi-section fission ionization chamber was constructed and used in the combination with Total Absorption Calorimeter (TAC) for detecting gamma rays for the precise measurement of Pu-239(n, gamma) reaction cross section at the nTOF facility.
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Lerendegui-Marco, J., Babiano-Suarez, V., Domingo-Pardo, C., Ladarescu, I., Tarifeno-Saldivia, A., & de la Fuente-Rosales, G. (2024). Pushing the high count rate limits of scintillation detectors for challenging neutron-capture experiments. Nucl. Instrum. Methods Phys. Res. A, 1064, 169385–13pp.
Abstract: One of the critical aspects for the accurate determination of neutron capture cross sections when combining time-of-flight and total energy detector techniques is the characterization and control of systematic uncertainties associated to the measuring devices. In this work we explore the most conspicuous effects associated to harsh count rate conditions: dead-time and pile-up effects. Both effects, when not properly treated, can lead to large systematic uncertainties and bias in the determination of neutron cross sections. In the majority of neutron capture measurements carried out at the CERN nTOF facility, the detectors of choice are the C6D6 liquid-based either in form of large-volume cells or recently commissioned sTED detector array, consisting of much smaller-volume modules. To account for the aforementioned effects, we introduce a Monte Carlo model for these detectors mimicking harsh count rate conditions similar to those happening at the CERN nTOF 20 m flight path vertical measuring station. The model parameters are extracted by comparison with the experimental data taken at the same facility during 2022 experimental campaign. We propose a novel methodology to consider both, dead-time and pile-up effects simultaneously for these fast detectors and check the applicability to experimental data from Au-197(n, gamma), including the saturated 4.9 eV resonance which is an important component of normalization for neutron cross section measurements.
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Balibrea-Correa, J., Lerendegui-Marco, J., Babiano-Suarez, V., Caballero, L., Calvo, D., Ladarescu, I., et al. (2021). Machine Learning aided 3D-position reconstruction in large LaCl3 crystals. Nucl. Instrum. Methods Phys. Res. A, 1001, 165249–17pp.
Abstract: We investigate five different models to reconstruct the 3D gamma-ray hit coordinates in five large LaCl3(Ce) monolithic crystals optically coupled to pixelated silicon photomultipliers. These scintillators have a base surface of 50 x 50 mm(2) and five different thicknesses, from 10 mm to 30 mm. Four of these models are analytical prescriptions and one is based on a Convolutional Neural Network. Average resolutions close to 1-2 mm fwhm are obtained in the transverse crystal plane for crystal thicknesses between 10 mm and 20 mm using analytical models. For thicker crystals average resolutions of about 3-5 mm fwhm are obtained. Depth of interaction resolutions between 1 mm and 4 mm are achieved depending on the distance of the interaction point to the photosensor surface. We propose a Machine Learning algorithm to correct for linearity distortions and pin-cushion effects. The latter allows one to keep a large field of view of about 70%-80% of the crystal surface, regardless of crystal thickness. This work is aimed at optimizing the performance of the so-called Total Energy Detector with Compton imaging capability (i-TED) for time-of-flight neutron capture cross-section measurements.
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n_TOF Collaboration(Zugec, P. et al), Babiano-Suarez, V., Caballero-Ontanaya, L., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2025). Measurement of the natC(n,p) and natC(n,d) reactions from n_TOF at CERN. Phys. Lett. B, 868, 139713–7pp.
Abstract: The energy dependence of the cross section of the (n,p) and (n,d) reactions on C-nat has been studied for the first time at the nTOF facility at CERN, from the particle detection threshold up to 25 MeV. The measurement was performed with two telescopes made of position-sensitive silicon Delta E-E detectors, covering the angular range from 20 degrees to 140 degrees. A detector efficiency has been determined by means of Monte Carlo simulations of the experimental setup. Various assumptions on the angular distributions and branching ratios of the excited levels of the residual B-11, B-12, B-13 nuclei were considered. In particular, theoretical calculations based on the TALYS-2.0 code were used and the systematic uncertainties in the analysis results were determined from the variations in these distributions. The nTOF data on the (n,p) and (n,d) reaction on carbon are characterized by a higher accuracy and wider energy range than currently available in literature. A comparison with current evaluations from different libraries reveals a rather significant disagreement with the n_TOF results, while a remarkable agreement is observed with the prediction of TALYS-2.0 for this light element.
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n_TOF Collaboration(Manna, A. et al), Babiano-Suarez, V., Caballero-Ontanaya, L., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2025). New insights on fission of 235U induced by high energy neutrons from a new measurement at n_TOF. Phys. Lett. B, 860, 139213–8pp.
Abstract: The U-235(n, f) reaction cross section was measured relative to neutron-proton elastic scattering for the first time in the energy region from 10 MeV to 440 MeV at the CERN n_TOF facility, extending the upper limit of the only previous measurement in the literature by more than 200 MeV. For neutron energies below 200 MeV, our results agree within one standard deviation with data in literature. Above 200 MeV, the comparison of model calculations to our data indicates the need to introduce a transient time in neutron-induced fission to allow the simultaneous description of (n, f) and (p, f) reactions.
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n_TOF Collaboration(Alcayne, V. et al), Babiano-Suarez, V., Caballero-Ontanaya, L., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2026). Measurement of the 244Cm neutron capture cross section at the n_TOF facility at CERN. Ann. Nucl. Energy, 227, 111977–14pp.
Abstract: Accurate neutron capture cross section data for minor actinides are essential for the safe and efficient management of high level radioactive waste produced during the operation of nuclear reactors. In particular, Cm-244, with a half-life of 18.11 years, dominates neutron emission in spent fuel and also contributes significantly to the decay heat and radiotoxicity. Furthermore, neutron capture on Cm-244 opens the pathway for the formation of heavier isotopes such as Bk, Cf, and other Cm isotopes. Sensitivity studies for present and future nuclear reactors have highlighted the need to reduce the uncertainties in the Cm-244 capture cross section. Experimental data on the capture cross section of this isotope are scarce due to the challenges associated with its measurements. Prior to the presented measurement and two recent measurements conducted at J-PARC, only one set of data for the Cm-244 capture cross section existed, obtained in 1969 during an underground nuclear explosion experiment. The capture cross section of Cm-244 has been measured at the nTOF facility at CERN with three different experimental setups: one at Experimental Area 1 (EAR1) using the Total Absorption Calorimeter and two measurements at Experimental Area 2 (EAR2) with C6D6 detectors, employing two different samples. The results from these three measurements were found to be compatible and then combined. In total, 17 resonances of Cm-244 were measured at nTOF below 300 eV. The radiative kernels obtained in this measurement are in good agreement with JENDL-4.0 for the majority of the resonances. Additionally, they are compatible with the recent JENDL-5 library below 50 eV, while at higher energies, the majority of radiative kernels from this evaluation based on the recent measurement by Kawase et al., are not compatible. Additionally, the Cm-244 samples also contained Pu-240. Resonances of this isotope were analyzed in the energy range between 20 and 180 eV, and the results were found to be consistent with previous measurements and evaluations, that enhances confidence in the Cm-244 results.
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Lerendegui-Marco, J., Balibrea-Correa, J., Alvarez-Rodriguez, P., Babiano-Suarez, V., Gameiro, B., Ladarescu, I., et al. (2025). First pilot tests of Compton imaging and boron concentration measurements in BNCT using i-TED. Appl. Radiat. Isot., 225, 112009–9pp.
Abstract: Dosimetry in BNCT poses significant challenges due to the indirect effect of neutrons interacting with elements within the body and uncertainties associated with the uptake of boron compounds used in clinical practice. Current treatment planning relies on unconventional estimates of boron tumor uptake derived from prior PET scans and thus, an online boron-uptake monitor would be highly convenient. This work presents the first pilot experiments carried out at ILL-Grenoble with the high-efficiency Compton camera i-TED, hereby aiming at demonstrating its applicability for BNCT dosimetry by introducing real-time measurement of the boron concentration and imaging capabilities of spatial dose distribution. In this experiment, we measured the 10B uptake of different cancer cells of tongue squamous cell carcinoma, malignant melanoma and glioblastoma treated with BPA (80 ppm of 10B). The samples were irradiated with the thermal neutron spectrum of ILL-Grenoble and the 478 keV 1-rays from the 7Li de-excitation after the neutron-boron reaction were registered both with the Compton imager and the high-sensitivity FIPPS HPGe array. These series of measurements allowed us to demonstrate the imaging capabilities of the Compton imaging device for the 478 keV 1-rays of interest for dosimetry in BNCT, as well as to assess its sensitivity, which was found to be below 1 μg of 10B.
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Lerendegui-Marco, J., Hallam, J., Cisterna, G., Sanchis-Molto, A., Balibrea-Correa, J., Babiano-Suarez, V., et al. (2025). First experimental results and optimization study of the portable neutron-gamma imager GN-Vision. Appl. Radiat. Isot., 224, 111826–13pp.
Abstract: GN-Vision is a compact, dual-modality imaging device designed to simultaneously localize the spatial origin of y-ray and slow neutron sources, with potential applications in nuclear safety, security, and hadron therapy. The system utilizes two position-sensitive detection planes, combining Compton imaging techniques for yray visualization with passive collimation for imaging slow and thermal neutrons (energies below 100 eV). This paper presents the first experimental outcomes from the initial GN-Vision prototype, focused on the development of its neutron imaging capabilities. Following this experimental assessment, we explore the device's performance potential and discuss several Monte Carlo simulation-based optimizations aimed at refining the neutron collimation system. These optimizations seek to improve real-time imaging efficiency and cost-effectiveness, enhancing GN-Vision's applicability for future practical deployments.
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