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1. A computer-vision aided Compton-imaging system for radioactive waste characterization and decommissioning of nuclear power plants

Author

Babiano-Suarez, Victor, Balibrea-Correa, Javier, Ladarescu, Ion, Lerendegui-Marco, Jorge, Leganes-Nieto, Jose Luis, and Domingo-Pardo, Cesar

Subjects
Physics - Instrumentation and Detectors
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., Comment: 29 pages, 16 figures, journal article

Published
2024

2. Towards Real Time Compton Imaging in Demanding Conditions

Author

Gameiro, Bernardo, Lerendegui-Marco, Jorge, Babiano-Suarez, Victor, Balibrea-Correa, Javier, Rosales, Gabriel de la Fuente, Ladarescu, Ion, Torres-Sánchez, Pablo, and Pardo, César Domingo

Subjects
Physics - Instrumentation and Detectors, Physics - Computational Physics
Abstract

Compton cameras are radiation detectors that provide spatial information on the origin of the {\gamma}-ray sources based on the Compton scattering effect. Many applications require these detectors to be used at high counting rate. As such, the preprocessing of the detections as well as the imaging algorithms are required to be time-efficient in order for the data to be processed in real time. In this work, optimizations to the preprocessing of events in Compton cameras based on monolithic crystals, with special focus on event identification, were implemented using a parallelizable algorithm. Regarding imaging, an established 3D back projection algorithm was parallelized and implemented using SYCL. The parallel implementation of the algorithm was included without and with several optimizations such as the pre-computing values, discarding low impact contributions based on angle, and selecting an efficient shape of the image universe. The implementations were tested with Intel CPUs, GPUs, and NVIDIA GPUs. An outlook into the study of algorithms to reconstruct the position of interaction within Compton cameras based on monolithic crystals into segmented regions and other next steps is included., Comment: 6 pages, 4 figures, EuroPar Doctoral Symposium 2024

Published
2024

3. The i-TED Compton Camera Array for real-time boron imaging and determination during treatments in Boron Neutron Capture Therapy

Author

Torres-Sánchez, Pablo, Lerendegui-Marco, Jorge, Balibrea-Correa, Javier, Babiano-Suárez, Victor, Gameiro, Bernardo, Ladarescu, Ion, Álvarez-Rodríguez, Patricia, Daugas, Jean-Michel, Koester, Ulli, Michelagnoli, Caterina, Pedrosa-Rivera, Maria, Porras, Ignacio, Ruiz-Magaña, Maria José, Ruiz-Ruiz, Carmen, and Domingo-Pardo, César

Subjects
Physics - Medical Physics
Abstract

This paper explores the adaptation and application of i-TED Compton imagers for real-time dosimetry in Boron Neutron Capture Therapy (BNCT). The i-TED array, previously utilized in nuclear astrophysics experiments at CERN, is being optimized for detecting and imaging 478 keV gamma-rays, critical for accurate BNCT dosimetry. Detailed Monte Carlo simulations were used to optimize the i-TED detector configuration and enhance its performance in the challenging radiation environment typical of BNCT. Additionally, advanced 3D image reconstruction algorithms, including a combination of back-projection and List-Mode Maximum Likelihood Expectation Maximization (LM-MLEM), are implemented and validated through simulations. Preliminary experimental tests at the Institut Laue-Langevin (ILL) demonstrate the potential of i-TED in a clinical setting, with ongoing experiments focusing on improving imaging capabilities in realistic BNCT conditions., Comment: 9 pages, 7 figures, submitted to the Special Issue of Applied Radiation and Isotopes associated to the 20th International Congress on Neutron Capture Therapy (20th ICNCT)

Published
2024

5. Towards machine learning aided real-time range imaging in proton therapy

Author

Lerendegui-Marco, Jorge, Balibrea-Correa, Javier, Babiano-Súarez, Víctor, Ladarescu, Ion, and Domingo-Pardo, César

Subjects
Physics - Medical Physics, Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

In this work, we report on the advantageous aspects of the i-TED Compton imager for proton-range monitoring, based on the results of the first Monte Carlo study of its applicability to this field. i-TED is an array of Compton cameras, that have been designed for neutron-capture nuclear physics experiments, which are characterized by $\gamma$-ray energies spanning up to 5-6 MeV, rather low $\gamma$-ray emission yields and intense neutron induced $\gamma$-ray backgrounds. Our developments to cope with these three aspects are concomitant with those required in the field of hadron therapy, especially in terms of high efficiency for real-time monitoring, low sensitivity to neutron backgrounds and reliable performance at the high $\gamma$-ray energies. We find that signal-to-background ratios can be appreciably improved with i-TED thanks to its light-weight design and the low neutron-capture cross sections of its LaCl$_{3}$ crystals, when compared to other similar systems based on LYSO, CdZnTe or LaBr$_{3}$. Its high time-resolution (CRT$\sim$500 ps) represents an additional advantage for background suppression when operated in pulsed HT mode. Each i-TED module features two detection planes of very large LaCl$_{3}$ monolithic crystals, thereby achieving a high efficiency in coincidence of 0.2% for a point-like 1MeV $\gamma$-ray source at 5 cm distance. This leads to sufficient statistics for reliable image reconstruction with an array of four i-TED detectors assuming clinical intensities of 10$^{8}$ protons per treatment point. The use of a two-plane design instead of three-planes has been preferred owing to the higher attainable efficiency for double time-coincidences than for threefold events. The loss of full-energy events for high energy $\gamma$-rays is compensated by means of Machine-Learning algorithms, which allow one to enhance the signal-to-total ratio up to a factor of 2., Comment: 19 pages, 14 figures. Accepted in Scientific Reports (Submitted: June 2021, Accepted: January 2022)

Published
2022
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7. Pushing the high count rate limits of scintillation detectors for challenging neutron-capture experiments

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Balibrea Correa, Javier, Lerendegui Marco, Jorge, Babiano Suárez, Víctor, Domingo Pardo, César, Ladarescu, Ion, Tarifeño Saldivia, Ariel, Fuente Rosales, Gabriel de la, Alcayne Aicua, Víctor, Cano Ott, Daniel, González Romero, Enrique Miguel, Casanovas Hoste, Adrià, Calviño Tavares, Francisco, Cortés Rossell, Guillem Pere, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Balibrea Correa, Javier, Lerendegui Marco, Jorge, Babiano Suárez, Víctor, Domingo Pardo, César, Ladarescu, Ion, Tarifeño Saldivia, Ariel, Fuente Rosales, Gabriel de la, Alcayne Aicua, Víctor, Cano Ott, Daniel, González Romero, Enrique Miguel, Casanovas Hoste, Adrià, Calviño Tavares, Francisco, and Cortés Rossell, Guillem Pere

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 n_TOF 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 n_TOF 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 197Au(n, gamma), including the saturated 4.9 eV resonance which is an important component of normalization for neutron cross section measurements., This work has been carried out in the framework of a project funded by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant project HYMNS, with grant agreement No. 681740). This work was supported by grant ICJ220-045122-I funded by MCIN/AEI/10.130 39/501100011033 and by European Union NextGenerationEU/PRTR. The authors acknowledge support from the Spanish Ministerio de Ciencia e Innovación under grants PID2019-104714GB-C21, PID2022- 138297NB-C21 and the funding agencies of the participating institutes. The authors acknowledge the financial support from MCIN and the European Union NextGenerationEU and Generalitat Valenciana in the call PRTR PC I+D+i ASFAE/2022/027., Article signat per 132 autors/es: J. Balibrea-Correa, J. Lerendegui-Marco, V. Babiano-Suarez, C. Domingo-Pardo, I. Ladarescu, A. Tarifeño-Saldivia, G. de la Fuente-Rosales, V. Alcayne, D. Cano-Ott, E. González-Romero, T. Martínez, E. Mendoza, A. Pérez de Rada, J. Plaza del Olmo, A. Sánchez-Caballero, A. Casanovas, F. Calviño, S. Valenta, O. Aberle, S. Altieri, S. Amaducci, J. Andrzejewski, M. Bacak, C. Beltrami, S. Bennett, A.P. Bernardes, E. Berthoumieux, R. Beyer, M. Boromiza, D. Bosnar, M. Caamaño, M. Calviani, D.M. Castelluccio, F. Cerutti, G. Cescutti, S. Chasapoglou, E. Chiaveri, P. Colombetti, N. Colonna, P. Console Camprini, G. Cortés, M.A. Cortés-Giraldo, L. Cosentino, S. Cristallo, S. Dellmann, M. Di Castro, S. Di Maria, M. Diakaki, M. Dietz, R. Dressler, E. Dupont, I. Durán, Z. Eleme, S. Fargier, B. Fernández, B. Fernández-Domínguez, P. Finocchiaro, S. Fiore, V. Furman, F. García-Infantes, A. Gawlik-Ramikega, G. Gervino, S. Gilardoni, C. Guerrero, F. Gunsing, C. Gustavino, J. Heyse, W. Hillman, D.G. Jenkins, E. Jericha, A. Junghans, Y. Kadi, K. Kaperoni, G. Kaur, A. Kimura, I. Knapová, M. Kokkoris, Y. Kopatch, M. Krtička, N. Kyritsis, C. Lederer-Woods, G. Lerner, A. Manna, A. Masi, C. Massimi, P. Mastinu, M. Mastromarco, E.A. Maugeri, A. Mazzone, A. Mengoni, V. Michalopoulou, P.M. Milazzo, R. Mucciola, F. Murtas, E. Musacchio-Gonzalez, A. Musumarra, P. Negret, P. Pérez-Maroto, N. Patronis, J.A. Pavón-Rodríguez, M.G. Pellegriti, J. Perkowski, C. Petrone, E. Pirovano, S. Pomp, I. Porras, J. Praena, J.M. Quesada, R. Reifarth, D. Rochman, Y. Romanets, C. Rubbia, M. Sabaté-Gilarte, P. Schillebeeckx, D. Schumann, A. Sekhar, A.G. Smith, N.V. Sosnin, M.E. Stamati, A. Sturniolo, G. Tagliente, D. Tarrío, P. Torres-Sánchez, E. Vagena, V. Variale, P. Vaz, G. Vecchio, D. Vescovi, V. Vlachoudis, R. Vlastou, A. Wallner, P.J. Woods, T. Wright, R. Zarrella, P. Žugec, Postprint (published version)

Published
2024

8. Advances and new ideas for neutron-capture astrophysics experiments at CERN n_TOF

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Domingo Pardo, César, Babiano Suárez, Víctor, Balibrea Correa, Javier, Lerendegui Marco, Jorge, Taín Enríquez, José Luis, Tarifeño Saldivia, Ariel, Aberle, O., Alcayne Aicua, Víctor, Amaducci, Simone, Andrzejewski, Józef, Calviño Tavares, Francisco, Calviani, Marco, Casanovas Hoste, Adrià, Cortés Rossell, Guillem Pere, Cosentino, Luigi, Dressler, Rugard, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Domingo Pardo, César, Babiano Suárez, Víctor, Balibrea Correa, Javier, Lerendegui Marco, Jorge, Taín Enríquez, José Luis, Tarifeño Saldivia, Ariel, Aberle, O., Alcayne Aicua, Víctor, Amaducci, Simone, Andrzejewski, Józef, Calviño Tavares, Francisco, Calviani, Marco, Casanovas Hoste, Adrià, Cortés Rossell, Guillem Pere, Cosentino, Luigi, and Dressler, Rugard

Abstract

The version of record of this article, first published in [The Europen Physics Journal A], is available online at Publisher’s website: http://dx.doi.org/10.1140/epja/s10050-022-00876-7, This article presents a few selected developments and future ideas related to the measurement of (n,¿) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with ¿ - ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at exploiting the high instantaneous neutron-flux of EAR2. Finally, astrophysics prospects related to the intermediate i neutron-capture process of nucleosynthesis are discussed in the context of the new NEAR activation area, Peer Reviewed, Article escrit per 139 auors/autores C. Domingo-Pardo, V. Babiano-Suarez, J. Balibrea-Correa, L. Caballero, I. Ladarescu, J. Lerendegui-Marco, J. L. Tain, A. Tarifeño-Saldivia, O. Aberle, V. Alcayne, S. Altieri, S. Amaducci, J. Andrzejewski, M. Bacak, C. Beltrami, S. Bennett, A. P. Bernardes, E. Berthoumieux, M. Boromiza, D. Bosnar, M. Caamaño, F. Calviño, M. Calviani, D. Cano-Ott, A. Casanovas, F. Cerutti, G. Cescutti, S. Chasapoglou, E. Chiaveri, N. M. Chiera, P. Colombetti, N. Colonna, P. Console Camprini, G. Cortés, M. A. Cortés-Giraldo, L. Cosentino, S. Cristallo, S. Dellmann, M. Di Castro, S. Di Maria, M. Diakaki, M. Dietz, R. Dressler, E. Dupont, I. Durán, Z. Eleme, S. Fargier, B. Fernández, B. Fernández-Domínguez, P. Finocchiaro, S. Fiore, F. García-Infantes, A. Gawlik-Ramięga , G. Gervino, S. Gilardoni, E. González-Romero, C. Guerrero, F. Gunsing, C. Gustavino, J. Heyse, W. Hillman, D. G. Jenkins, E. Jericha, A. Junghans, Y. Kadi, K. Kaperoni, F. Käppeler, G. Kaur, A. Kimura, I. Knapová, U. Köster, M. Kokkoris, M. Krtička, N. Kyritsis, C. Lederer-Woods, G. Lerner, A. Manna, T. Martínez, A. Masi, C. Massimi, P. Mastinu, M. Mastromarco, E. A. Maugeri, A. Mazzone, E. Mendoza, A. Mengoni, P. M. Milazzo, I. Mönch, R. Mucciola, F. Murtas, E. Musacchio-Gonzalez, A. Musumarra, A. Negret, A. Pérez de Rada, P. Pérez-Maroto, N. Patronis, J. A. Pavón-Rodríguez, M. G. Pellegriti, J. Perkowski, C. Petrone, E. Pirovano, J. Plaza, S. Pomp, I. Porras, J. Praena, J. M. Quesada, R. Reifarth, D. Rochman, Y. Romanets, C. Rubbia, A. Sánchez, M. Sabaté-Gilarte, P. Schillebeeckx, D. Schumann, A. Sekhar, A. G. Smith, N. V. Sosnin, M. Stamati, A. Sturniolo, G. Tagliente, D. Tarrío, P. Torres-Sánchez, J. Turko, S. Urlass, E. Vagena, S. Valenta, V. Variale, P. Vaz, G. Vecchio, D. Vescovi, V. Vlachoudis, R. Vlastou, T. Wallner, P. J. Woods, T. Wright, R. Zarrella, P. Žugec, Postprint (published version)

Published
2023

9. Constraints on the dipole photon strength for the odd uranium isotopes

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Berthoumieux, Eric, Dupont, Emmeric, Gunsing, Frank, Serot, Olivier, Aberle, O., Alcayne Aicua, Víctor, Amaducci, Simone, Andrzejewski, Józef, Audouin, Ludmila, Bécares, Vicente, Babiano Suárez, Víctor, Bacak, Michael, Barbagallo, Massimo, Billowes, J., Bosnar, Damir, Caballero Ontanaya, Luis, Calviño Tavares, Francisco, Calviani, Marco, Cano Ott, Daniel, Casanovas Hoste, Adrià, Chiaveri, E., Colonna, Nicola, Cortés Rossell, Guillem Pere, Cortés Giraldo, Miguel Antonio, Cosentino, Luigi, Cristallo, Sergio, Damone, Lucia Anna, Tarifeño Saldivia, Ariel Esteban, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Berthoumieux, Eric, Dupont, Emmeric, Gunsing, Frank, Serot, Olivier, Aberle, O., Alcayne Aicua, Víctor, Amaducci, Simone, Andrzejewski, Józef, Audouin, Ludmila, Bécares, Vicente, Babiano Suárez, Víctor, Bacak, Michael, Barbagallo, Massimo, Billowes, J., Bosnar, Damir, Caballero Ontanaya, Luis, Calviño Tavares, Francisco, Calviani, Marco, Cano Ott, Daniel, Casanovas Hoste, Adrià, Chiaveri, E., Colonna, Nicola, Cortés Rossell, Guillem Pere, Cortés Giraldo, Miguel Antonio, Cosentino, Luigi, Cristallo, Sergio, Damone, Lucia Anna, and Tarifeño Saldivia, Ariel Esteban

Abstract

Nuclear level densities (NLDs) and photon strength functions (PSFs), also called ¿ -ray or radiation strength functions, represent average properties of the nucleus in the regime of excitation where individual levels and transition probabilities by ¿ decay are not readily accessible by experimental or theoretical means. They are key ingredients for statistical calculations of the reaction cross sections involving ¿ rays via the Hauser-Feshbach approach [1], like inelastic scattering or neutron capture reactions., Peer Reviewed, Aquest article té 124 autors/autores J. Moreno-Soto, S. Valenta, E. Berthoumieux, A. Chebboubi, M. Diakaki, W. Dridi, E. Dupont, F. Gunsing, M. Krticka, O. Litaize, O. Serot, O. Aberle, V. Alcayne, S. Amaducci, J. Andrzejewski, L. Audouin, V. Bécares, V. Babiano-Suarez, M. Bacak, M. Barbagallo, Th. Benedikt, S. Bennett, J. Billowes, D. Bosnar, A. Brown, M. Busso, M. Caamaño, L. Caballero-Ontanaya, F. Calviño, M. Calviani, D. Cano-Ott, A. Casanovas, F. Cerutti, E. Chiaveri, N. Colonna, G. Cortés, M. A. Cortés-Giraldo, L. Cosentino, Cristallo, L. A. Damone, P. J. Davies, M. Dietz, C. Domingo-Pardo, R. Dressler, Q. Ducasse, I. Durán, Z. Eleme, B. Fernández-Domínguez, A. Ferrari, P. Finocchiaro, V. Furman, K. Göbel, A. Gawlik-Rami, S. Gilardoni, I. F. Gonçalves, E. González-RomeroC. Guerrero, S. Heinitz, J. Heyse, D. G. Jenkins, A. Junghans, F. Käppeler, Y. Kadi, A. Kimura, I. Knapová, M. Kokkoris, Y. Kopatch, D. Kurtulgil, I. Ladarescu, C. Lampoudis, C. Lederer-Woods, S. J. Lonsdale, D. Macina, A. Manna, T. Martínez, A. Masi, C. Massimi, P. Mastinu, M. Mastromarco, E. A. Maugeri, A. Mazzone, E. Mendoza, A. Mengoni, V. Michalopoulou, P. M. Milazzo, F. MingroneA. Musumarra, A. Negret, R. Nolte, F. Ogállar, A. Oprea, N. Patronis, A. Pavlik, J. Perkowski, L. Piersanti, C. Petrone, E. Pirovano, I. Porras, J. Praena, J. M. Quesada, D. Ramos-Doval, T. Rauscher, R. Reifarth, D. Rochman, M. Sabaté-Gilarte, A. Saxena, P. Schillebeeckx, D. Schumann, A. Sekhar, A. G. Smith, N. V. Sosnin, P. Sprung, A. Stamatopoulos, G. Tagliente, J. L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, P. Torres-Sánchez, A. Tsinganis, J. Ulrich, S. Urlass, G. Vannini, V. Variale, P. Vaz, A. Ventura, D. Vescovi, V. Vlachoudis, R. Vlastou, A. Wallner, P. J. Woods, T. Wright, P. Žugec, Postprint (published version)

Published
2022

10. High resolution 80Se(n,γ) cross section measurement at CERN n_TOF and development of the novel i-TED detection system

Author

Babiano Suárez, Víctor, Domingo Pardo, César, Balibrea Correa, Javier, Lerendegui Marco, Jorge, and Departament de Física Atòmica, Molecular i Nuclear

Subjects
Dynamic Electronic Collimation, branching point, PETsys Electronics, nucleosynthesis, i-TED, prompt-gamma, UNESCO::FÍSICA::Física atómica y nuclear ::Física nuclear experimental bajas energías, neutron capture cross section, nuclear physics, 79Se, FÍSICA::Física atómica y nuclear ::Física nuclear experimental bajas energías [UNESCO], time of flight, monolithic scintillation crystal, MACS, total energy detectors, background rejection, silicon photomultiplier, s-process, Compton camera, 80Se
Abstract

El proceso (-s) de captura lenta de neutrones es responsable de la formación de la mitad de los elementos más pesados ​​que el hierro en el universo. A pesar de la larga escala de tiempo de este proceso, la larga vida media de algunos isótopos inestables a lo largo del flujo de reacción del proceso-s crea puntos de ramificación que conducen a una división de la ruta de la nucleosíntesis. 79Se (t1/2 = 3.27 x 10^5 y) representa uno de los núcleos ramificados-s más relevantes y debatidos por dos razones principales. Por un lado, la existencia de estados excitados de baja energía en el 79Se, cuya población puede variar con la temperatura del medio estelar, hace que el patrón de abundancia local alrededor de esta ramificación sea especialmente sensible a las condiciones térmicas. Por otro lado, las abundancias observadas de los isótopos de criptón solo-s (80,82Kr) son muy conocidas a partir de datos meteóricos. Por lo tanto, al comparar estas abundancias con las predichas por los modelos estelares, se puede obtener información sobre las condiciones térmicas del medio estelar en el que ocurre el proceso-s. Para este objetivo, los modelos estelares hidrodinámicos de última generación necesitan datos de entrada experimentales sobre la sección transversal de captura de neutrones de los isótopos implicados en la ramificación en un amplio rango de energía térmica. La última afirmación es cierta para el núcleo inestable 79Se y sus núcleos vecinos más cercanos, 78,80Se. Sin embargo, las mediciones de captura de neutrones en núcleos radiactivos son muy desafiantes y, de hecho, hasta el momento, no hay datos experimentales sobre la reacción del 79Se(n,gamma). Además, los datos experimentales previos sobre el 80Se eran bastante limitados en términos de resolución e integridad. En este contexto, el presente trabajo ha contribuido en dos frentes diferentes con el objetivo de arrojar luz sobre la ramificación 79Se del proceso-s. La primera parte de este trabajo describe la medición de la sección transversal de captura de neutrones de 80Se en el CERN n_TOF, con una resolución de energía muy alta y que cubre por primera vez todo el rango de energía estelar de interés. La medición anterior en 80Se(n,gamma) adolece de una resolución de energía muy limitada y un rango corto de energía de neutrones. Estos inconvenientes se han mejorado notablemente en este trabajo mediante una medición del tiempo de vuelo (ToF) de alta resolución empleando una muestra de 80Se de alta pureza de 3.8 g de masa. El uso de detectores de energía total C6D6D en combinación con la técnica de ponderación de altura de pulso (PHWT), nos ha permitido obtener un rendimiento de captura con alta precisión y cubriendo todo el rango de energía de interés astrofísico entre 1 eV y 100 keV. Se han analizado ciento trece resonancias mediante el formalismo de matriz-R, noventa y ocho de ellas por primera vez. El impacto es considerable, siendo el MACS a kT = 8 keV un 36 % más pequeño que el valor recomendado en KADoNiS. La incertidumbre estadística que afecta a este nuevo MACS se ha reducido del 10% al 1%. La precisión sistemática lograda entre el 3,2 % y el 5,7 % es comparable a las incertidumbres de las abundancias isotópicas de los isótopos de Kr solo s, que es el requisito de los modelos hidrodinámicos estelares para ofrecer resultados precisos. La segunda contribución principal de este trabajo al estudio de la ramificación del 79Se consistió en los primeros desarrollos hacia un nuevo sistema de detección, denominado i-TED, para medir secciones transversales (n,gamma) con una relación señal/fondo mejorada. Este nuevo sistema de detección se aplicará por primera vez en la medición de la sección transversal de 79Se(n,gamma) en el CERN n_TOF en 2022. El detector de energía total con capacidad de generación de imágenes i-TED aprovecha la técnica de generación de imágenes de Compton para seleccionar principalmente la gamma -rayos generados en la muestra por los neutrones capturados en la misma, al tiempo que rechaza los rayos gamma contaminantes procedentes de los neutrones perdidos capturados en el entorno. Para implementar técnicamente este concepto, i-TED consta de dos planos de detección que operan en coincidencia temporal, en los que se registran la posición, la energía y el tiempo de las interacciones de los rayos gamma. En este trabajo de tesis se ha desarrollado y caracterizado un primer demostrador denominado i-TED5.3, con tres detectores sensibles a la posición (PSDs), y se ha realizado la primera prueba de concepto experimental. En i-TED5.3, un PSD se coloca en el plano de dispersión mientras que los dos restantes se disponen en una configuración vertical dentro de la capa absorbente. Cada PSD consta de un cristal de centelleo monolítico de LaCl3(Ce) acoplado ópticamente a un fotomultiplicador de silicio, que está conectado a un sistema de lectura basado en ASIC fabricado por PETsys Electronics. Una caracterización completa de este prototipo arrojó resoluciones de posición que oscilan entre 1 mm y 2 mm FWHM, y resoluciones de energía de 6% y 7% FWHM a 661 keV para los espectros de energía simple y depositada por coincidencia, respectivamente. Finalmente, un primer experimento experimental de prueba de concepto realizado en el CERN n_TOF con i-TED5.3 nos permitió validar técnicamente el sistema para experimentos ToF y demostrar las capacidades de rechazo en segundo plano. Se logró una reducción de fondo de hasta un factor de 3.8 después de comparar los espectros de energía de neutrones de 56Fe(n,gamma) medidos con el demostrador i-TED5.3 y los detectores C6D6 de última generación. Otras mejoras realizadas fuera del alcance de este trabajo de tesis comprenden el ensamblaje y la caracterización de una matriz de 4 detectores i-TED, cada uno con 5 PSD, y el uso de técnicas de inteligencia artificial y aprendizaje automático para mejorar aún más la capacidad de rechazo de fondo. y el rendimiento general del sistema. The slow neutron capture (s-) process is responsible for the formation of half of the elements heavier than iron in the universe. Despite the long time scale of this process, the long half-life of some unstable isotopes throughout the s-process reaction flow creates branching points that lead to a split of the nucleosynthesis path. 79Se (t1/2 = 3.27 x 10^5 y) represents one of the most relevant and debated s-branching nuclei for two main reasons. On the one hand, the existence of low-energy excited states in 79Se, whose population can vary with the temperature of the stellar medium, makes the local abundance pattern around this branching especially sensitive to the thermal conditions. On the other hand, the observed abundances of the s-only krypton isotopes (80,82Kr) are very well-known from meteoric data. Thus, by comparing these abundances with those predicted by stellar models, information about the thermal conditions of the stellar media in which the s-process occurs can be obtained. To this aim, state-of-the-art hydrodynamic stellar models need experimental input data on the neutron capture cross section of the isotopes involved in the branching over a broad thermal energy range. The latter statement is certainly true for the unstable 79Se and its closest neighboring nuclei, 78,80Se. However, neutron capture measurements on radioactive nuclei are very challenging and indeed, thus far, there is no experimental data on the 79Se(n,gamma) reaction. Also, previous experimental data on 80Se was rather limited in terms of resolution and completeness. In this context, the present work has contributed in two different fronts with the aim of shedding light on to the 79Se s-process branching. The first part of this work describes the neutron capture cross section measurement of 80Se at CERN n_TOF, with very high energy resolution and covering the full stellar energy range of interest for the first time. The previous measurement on 80Se(n,gamma) suffers from a very limited energy resolution and a short neutron-energy range. These drawbacks have been remarkably improved in this work by means of a high-resolution time of flight (ToF) measurement employing a high purity 80Se sample of 3.8 g of mass. The use of C6D6D total energy detectors in combination with the Pulse-Height Weighting Technique (PHWT), have allowed us to obtain a capture yield with high accuracy and covering the entire energy range of astrophysical interest between 1 eV and 100 keV. One hundred and thirteen resonances have been analyzed by means of the R-matrix formalism, ninety-eight of them for the first time. The impact is sizable, being the MACS at kT = 8 keV 36% smaller than the value recommended in KADoNiS. The statistical uncertainty affecting this new MACS has been reduced from 10% down to 1%. The achieved systematic accuracy between 3.2% and 5.7% is comparable to the uncertainties of the isotopic abundances of the s-only Kr-isotopes, which is the requirement of hydrodynamic stellar models to deliver accurate results. The second main contribution of this work to the study of the 79Se branching consisted of the first developments towards a novel detection system, called i-TED, for measuring (n,gamma) cross sections with enhanced signal-to-background ratio. This new detection system will be applied for the first time in the measurement of the 79Se(n,gamma) cross-section at CERN n_TOF in 2022. The i-TED imaging capable Total Energy Detector exploits the Compton imaging technique to select mainly the gamma-rays generated in the sample by neutrons captured therein, while rejecting contaminant gamma-rays coming from stray neutrons captured in the surroundings. In order to technically implement this concept, i-TED consists of two detection planes operating in time coincidence, in which the position, energy and time of the gamma-ray interactions are registered. A first demonstrator called i-TED5.3, with three position sensitive detectors (PSDs), has been developed and characterized in this thesis work and the first experimental proof of concept has been carried out. In i-TED5.3, one PSD is placed in the scatter plane while the remaining two are arranged in a vertical configuration within the absorber layer. Each PSD consists of a monolithic LaCl3(Ce) scintillation crystal optically coupled to a silicon photomultiplier, which is connected to an ASIC-based readout system manufactured by PETsys Electronics. A complete characterization of this prototype yielded position resolutions ranging between 1 mm and 2 mm FWHM, and energy resolutions of 6% and 7% FWHM at 661 keV for the singles and coincidence deposited energy spectra, respectively. Finally, a first experimental proof of concept experiment carried out at CERN n_TOF with i-TED5.3 allowed us to technically validate the system for ToF experiments, and demonstrate the background rejection capabilities. A background reduction by up to a factor of 3.8 was achieved after comparing the 56Fe(n,gamma) neutron energy spectra measured with the i-TED5.3 demonstrator and state-of-the-art C6D6D detectors. Further improvements undertaken outside of the scope of this thesis work comprise the assembly and characterization of an array of 4 i-TED detectors, each one comprising 5 PSDs, and the use of artificial intelligence and machine-learning techniques for enhancing further the background rejection capability and overall system performance.

Published
2022

12. A first prototype of C6D6 total-energy detector with SiPM readout for neutron capture time-of-flight experiments

Author

Balibrea-Correa, J., Lerendegui Marco, Jorge, Calvo Diaz-Aldagalán, David, Caballero Ontanaya, Luis, Babiano Suárez, Víctor, Tolosa Delgado, Alvaro, Domingo Pardo, César, Calviño Tavares, Francisco|||0000-0002-7198-4639, Tarifeño Saldivia, Ariel Esteban|||0000-0001-8552-5030, Casanovas Hoste, Adrià|||0000-0002-7138-0894, Cano Ott, Daniel, Alcayne Aicua, Víctor, Bacak, Michael, Barbagallo, Massimo, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya. Doctorat en Enginyeria Nuclear i de les Radiacions Ionitzants, and Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group

Subjects
Física [Àrees temàtiques de la UPC], Physics::Instrumentation and Detectors, Time-of-flight, Radiative capture, Nuclear physics, Total energy detector, Física nuclear, Neutrons--Captura, Silicon photomultiplier, Pulse-height weighting technique, Neutrons--Capture, Radiation detectors
Abstract

Low efficiency total-energy detectors (TEDs) are one of the main tools for neutron capture cross section measurements utilizing the time-of-flight (TOF) technique. State-of-the-art TEDs are based on a CD liquid-scintillation cell optically coupled to a fast photomultiplier tube. The large photomultiplier tube represents yet a significant contribution to the so-called neutron sensitivity background, which is one of the most conspicuous sources of uncertainty in this type of experiments. Here we report on the development of a first prototype of a TED based on a silicon-photomultiplier (SiPM) readout, thus resulting in a lightweight and much more compact detector. Apart from the envisaged improvement in neutron sensitivity, the new system uses low voltage (+28 V) and low current supply (50 mA), which is more practical than the kV supply required by conventional photomultipliers. One important difficulty hindering the earlier implementation of SiPM readout for this type of detector was the large capacitance for the output signal when all pixels of a SiPM array are summed together. The latter leads to long pulse rise and decay times, which are not suitable for time-of-flight experiments. In this work we demonstrate the feasibility of a Schottky-diode multiplexing readout approach, that allows one to preserve the excellent timing properties of SiPMs, hereby paving the way for their implementation in future neutron TOF experiments.

Published
2021

13. First results of the140ce(N,¿)141ce cross-section measurement at n_tof

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Amaducci, Simone, Colonna, Nicola, Cosentino, Luigi, Cristallo, Sergio, Finocchio, Elisabetta, Massimi, Cristian, Mastromarco, Mario, Aberle, O., Alcayne Aicua, Víctor, Andrzejewski, Józef, Babiano Suárez, Víctor, Bacak, Michael, Barbagallo, Massimo, Berthoumieux, Eric, Calviño Tavares, Francisco, Casanovas Hoste, Adrià, Cortés Rossell, Guillem Pere, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Amaducci, Simone, Colonna, Nicola, Cosentino, Luigi, Cristallo, Sergio, Finocchio, Elisabetta, Massimi, Cristian, Mastromarco, Mario, Aberle, O., Alcayne Aicua, Víctor, Andrzejewski, Józef, Babiano Suárez, Víctor, Bacak, Michael, Barbagallo, Massimo, Berthoumieux, Eric, Calviño Tavares, Francisco, Casanovas Hoste, Adrià, and Cortés Rossell, Guillem Pere

Abstract

An accurate measurement of the 140Ce(n,¿) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the 140Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in 140Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the 140Ce Maxwellian-averaged cross-section., Peer Reviewed, Article signat per 130 autors/es: Simone Amaducci, Nicola Colonna, Luigi Cosentino, Sergio Cristallo, Paolo Finocchiaro, Milan Krtiˇcka, Cristian Massimi, Mario Mastromarco, Annamaria Mazzone, Alberto Mengoni, Stanislav Valenta, Oliver Aberle, Victor Alcayne, Józef Andrzejewski, Laurent Audouin, Victor Babiano-Suarez, Michael Bacak, Massimo Barbagallo, Samuel Bennett, Eric Berthoumieux, Jon Billowes, Damir Bosnar, Adam Brown, Maurizio Busso, Manuel Caamaño, Luis Caballero-Ontanaya, Francisco Calviño, Marco Calviani, Daniel Cano-Ott, Adria Casanovas, Francesco Cerutti, Enrico Chiaveri, Guillem Cortés, Miguel Cortés-Giraldo, Lucia-Anna Damone, Paul-John Davies, Maria Diakaki, Mirco Dietz, Cesar Domingo-Pardo, Rugard Dressler, Quentin Ducasse, Emmeric Dupont, Ignacio Durán, Zinovia Eleme, Beatriz Fernández-Domínguez, Alfredo Ferrari, Valter Furman, Kathrin Göbel, Ruchi Garg, Aleksandra Gawlik, Simone Gilardoni, Isabel Gonçalves, Enrique González-Romero, Carlos Guerrero, Frank Gunsing, Hideo Harada, Stephan Heinitz, Jan Heyse, David Jenkins, Arnd Junghans, Franz Käppeler, Yacine Kadi, Atsushi Kimura, Ingrid Knapova, Michael Kokkoris, Yuri Kopatch, Deniz Kurtulgil, Ion Ladarescu, Claudia Lederer-Woods, Helmut Leeb, Jorge Lerendegui-Marco, Sarah-Jane Lonsdale, Daniela Macina, Alice Manna, Trinitario Martínez, Alessandro Masi, Pierfrancesco Mastinu, Emilio-Andrea Maugeri, Emilio Mendoza, Veatriki Michalopoulou, Paolo Milazzo, Federica Mingrone, Javier Moreno-Soto, Agatino Musumarra, Alexandru Negret, Francisco Ogállar, Andreea Oprea, Nikolas Patronis, Andreas Pavlik, Jarosław Perkowski, Luciano Piersanti, Cristina Petrone, Elisa Pirovano, Ignacio Porras, Javier Praena, José-Manuel Quesada, Diego Ramos-Doval, Thomas Rauscher, René Reifarth, Dimitri Rochman, Carlo Rubbia, Marta Sabaté-Gilarte, Alok Saxena, Peter Schillebeeckx, Dorothea Schumann, Adhitya Sekhar, Gavin Smith, Nikolay Sosnin, Peter Sprung, Athanasios Stamatopoulos, Giuseppe Tagliente, José Tain, Ariel Tarifeño, Postprint (author's final draft)

Published
2021

14. A first prototype of C6D6 total-energy detector with SiPM readout for neutron capture time-of-flight experiments

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya. Doctorat en Enginyeria Nuclear i de les Radiacions Ionitzants, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Balibrea-Correa, J., Lerendegui Marco, Jorge, Calvo Diaz-Aldagalán, David, Caballero Ontanaya, Luis, Babiano Suárez, Víctor, Tolosa Delgado, Alvaro, Domingo Pardo, César, Calviño Tavares, Francisco, Tarifeño Saldivia, Ariel Esteban, Casanovas Hoste, Adrià, Cano Ott, Daniel, Alcayne Aicua, Víctor, Bacak, Michael, Barbagallo, Massimo, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya. Doctorat en Enginyeria Nuclear i de les Radiacions Ionitzants, Universitat Politècnica de Catalunya. ANT - Advanced Nuclear Technologies Research Group, Balibrea-Correa, J., Lerendegui Marco, Jorge, Calvo Diaz-Aldagalán, David, Caballero Ontanaya, Luis, Babiano Suárez, Víctor, Tolosa Delgado, Alvaro, Domingo Pardo, César, Calviño Tavares, Francisco, Tarifeño Saldivia, Ariel Esteban, Casanovas Hoste, Adrià, Cano Ott, Daniel, Alcayne Aicua, Víctor, Bacak, Michael, and Barbagallo, Massimo

Abstract

Low efficiency total-energy detectors (TEDs) are one of the main tools for neutron capture cross section measurements utilizing the time-of-flight (TOF) technique. State-of-the-art TEDs are based on a CD liquid-scintillation cell optically coupled to a fast photomultiplier tube. The large photomultiplier tube represents yet a significant contribution to the so-called neutron sensitivity background, which is one of the most conspicuous sources of uncertainty in this type of experiments. Here we report on the development of a first prototype of a TED based on a silicon-photomultiplier (SiPM) readout, thus resulting in a lightweight and much more compact detector. Apart from the envisaged improvement in neutron sensitivity, the new system uses low voltage (+28 V) and low current supply (50 mA), which is more practical than the kV supply required by conventional photomultipliers. One important difficulty hindering the earlier implementation of SiPM readout for this type of detector was the large capacitance for the output signal when all pixels of a SiPM array are summed together. The latter leads to long pulse rise and decay times, which are not suitable for time-of-flight experiments. In this work we demonstrate the feasibility of a Schottky-diode multiplexing readout approach, that allows one to preserve the excellent timing properties of SiPMs, hereby paving the way for their implementation in future neutron TOF experiments., Postprint (published version)

Published
2021

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