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Author Martinez-Reviriego, P.; Esperante, D.; Grudiev, A.; Gimeno, B.; Blanch, C.; Gonzalez-Iglesias, D.; Fuster-Martinez, N.; Martin-Luna, P.; Martinez, E.; Menendez, A.; Fuster, J. url  doi
openurl 
  Title Dielectric assist accelerating structures for compact linear accelerators of low energy particles in hadrontherapy treatments Type Journal Article
  Year 2024 Publication (up) Frontiers in Physics Abbreviated Journal Front. Physics  
  Volume 12 Issue Pages 1345237 - 12pp  
  Keywords dielectric assist accelerating (DAA) structures; radio frequency (RF); LINAC; hadrontherapy; standing wave  
  Abstract Dielectric Assist Accelerating (DAA) structures based on ultralow-loss ceramic are being studied as an alternative to conventional disk-loaded copper cavities. This accelerating structure consists of dielectric disks with irises arranged periodically in metallic structures working under the TM02-pi mode. In this paper, the numerical design of an S-band DAA structure for low beta particles, such as protons or carbon ions used for Hadrontherapy treatments, is shown. Four dielectric materials with different permittivity and loss tangent are studied as well as different particle velocities. Through optimization, a design that concentrates most of the RF power in the vacuum space near the beam axis is obtained, leading to a significant reduction of power loss on the metallic walls. This allows to fabricate cavities with an extremely high quality factor, over 100,000, and shunt impedance over 300 M omega/m at room temperature. During the numerical study, the design optimization has been improved by adjusting some of the cell parameters in order to both increase the shunt impedance and reduce the peak electric field in certain locations of the cavity, which can lead to instabilities in its normal functioning.  
  Address [Martinez-Reviriego, Pablo; Esperante, Daniel; Gimeno, Benito; Blanch, Cesar; Gonzalez-Iglesias, Daniel; Fuster-Martinez, Nuria; Martin-Luna, Pablo; Martinez, Eduardo; Menendez, Abraham; Fuster, Juan] CSIC Univ Valencia, Inst Fis Corpuscular IFIC, Paterna, Spain, Email: pablo.martinez.reviriego@ific.uv.es  
  Corporate Author Thesis  
  Publisher Frontiers Media Sa Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-424x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001162373700001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5953  
Permanent link to this record
 

 
Author Olivares Herrador, J.; Latina, A.; Aksoy, A.; Fuster Martinez, N.; Gimeno, B.; Esperante, D. doi  openurl
  Title Implementation of the beam-loading effect in the tracking code RF-track based on a power-diffusive model Type Journal Article
  Year 2024 Publication (up) Frontiers in Physics Abbreviated Journal Front. Physics  
  Volume 12 Issue Pages 1348042 - 11pp  
  Keywords beam loading; LINAC; energy loss; tracking simulation; transient; high-intensity beam; CLEAR; gradient reduction  
  Abstract The need to achieve high energies in particle accelerators has led to the development of new accelerator technologies, resulting in higher beam intensities and more compact devices with stronger accelerating fields. In such scenarios, beam-loading effects occur, and intensity-dependent gradient reduction affects the accelerated beam as a consequence of its interaction with the surrounding cavity. In this study, a power-diffusive partial differential equation is derived to account for this effect. Its numerical resolution has been implemented in the tracking code RF-Track, allowing the simulation of apparatuses where transient beam loading plays an important role. Finally, measurements of this effect have been carried out in the CERN Linear Electron Accelerator for Research (CLEAR) facility at CERN, finding good agreement with the RF-Track simulations.  
  Address [Olivares Herrador, Javier; Latina, Andrea; Aksoy, Avni] CERN, Meyrin, Switzerland, Email: javier.olivares.herrador@cern.ch  
  Corporate Author Thesis  
  Publisher Frontiers Media Sa Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-424x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001193122800001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6019  
Permanent link to this record
 

 
Author Blanes-Selva, V.; Ruiz-Garcia, V.; Tortajada, S.; Benedi, J.M.; Valdivieso, B.; Garcia-Gomez, J.M. url  doi
openurl 
  Title Design of 1-year mortality forecast at hospital admission: A machine learning approach Type Journal Article
  Year 2021 Publication (up) Health Informatics Journal Abbreviated Journal Health Inform. J.  
  Volume 27 Issue 1 Pages 13pp  
  Keywords machine learning; palliative care; hospital admission data; mortality forecast  
  Abstract Palliative care is referred to a set of programs for patients that suffer life-limiting illnesses. These programs aim to maximize the quality of life (QoL) for the last stage of life. They are currently based on clinical evaluation of the risk of 1-year mortality. The main aim of this work is to develop and validate machine-learning-based models to predict the exitus of a patient within the next year using data gathered at hospital admission. Five machine-learning techniques were applied using a retrospective dataset. The evaluation was performed with five metrics computed by a resampling strategy: Accuracy, the area under the ROC curve, Specificity, Sensitivity, and the Balanced Error Rate. All models reported an AUC ROC from 0.857 to 0.91. Specifically, Gradient Boosting Classifier was the best model, producing an AUC ROC of 0.91, a sensitivity of 0.858, a specificity of 0.808, and a BER of 0.1687. Information from standard procedures at hospital admission combined with machine learning techniques produced models with competitive discriminative power. Our models reach the best results reported in the state of the art. These results demonstrate that they can be used as an accurate data-driven palliative care criteria inclusion.  
  Address [Blanes-Selva, Vicent; Benedi, Jose-Miguel; Garcia-Gomez, Juan M.] Univ Politecn Valencia, Valencia, Spain, Email: viblasel@upv.es  
  Corporate Author Thesis  
  Publisher Sage Publications Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1460-4582 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000645567000008 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5182  
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Author Albiol, F.; Corbi, A.; Albiol, A. doi  openurl
  Title Densitometric Radiographic Imaging With Contour Sensors Type Journal Article
  Year 2019 Publication (up) IEEE Access Abbreviated Journal IEEE Access  
  Volume 7 Issue Pages 18902-18914  
  Keywords Conventional X-ray imaging; contour data; densitometric images; dynamic range; depth information  
  Abstract We present the technical/physical foundations of a new imaging technique that combines ordinary radiographic information (generated by conventional X-ray settings) with the patient's volume to derive densitometric images. Traditionally, these images provide quantitative information about tissues densities. In our approach, they graphically enhance either soft or bony regions. After measuring the patient's volume with contour recognition devices, the physical traversed lengths within it (as the Roentgen beam intersects the patient) are calculated and pixel-wise associated with the original radiograph (X). In order to derive this map of lengths (L), the camera equations of the X-ray system and the contour sensor are determined. The patient's surface is also translated to the point-of-view of the X-ray beam and all its entrance/exit points are sought with the help of ray-casting methods. The derived L is applied to X as a physical operation (subtraction), obtaining soft tissue-(D-S) or bone-enhanced (D'(B)) figures. In the D-S type, the contained graphical information can be linearly mapped to the average electronic density (traversed by the X-ray beam). This feature represents an interesting proof-of-concept of associating density data to radiographs, but most important, their intensity histogram is objectively compressed, i.e., the dynamic range is more shrunk (compared against the corresponding X). This leads to other advantages: improvement in the visibility of border/edge areas (high gradient), extended manual window level/width manipulations during screening, and immediate correction of underexposed X instances. In the D-B' type, high-density elements are highlighted and easier to discern. All these results can be achieved with low-energy beam exposures, saving costs and dose. Future work will deepen this clinical side of our research. In contrast with other image-based modifiers, the proposed method is grounded on the measurement of a physical entity: the span of the X-ray beam within a body while undertaking a radiographic examination.  
  Address [Albiol, Francisco; Corbi, Alberto] CSIC, Inst Fis Corpuscular, Paterna 46980, Spain, Email: kiko@ific.uv.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-3536 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000459591800001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 3920  
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Author Coves, A.; Maestre, H.; Archiles, R.; Andres, M.V.; Gimeno, B. doi  openurl
  Title Surface-Impedance Formulation for Hollow-Core Waveguides Based on Subwavelength Gratings Type Journal Article
  Year 2022 Publication (up) IEEE Access Abbreviated Journal IEEE Access  
  Volume 10 Issue Pages 18843-18854  
  Keywords Electromagnetic waveguides; Optical waveguides; Planar waveguides; Gratings; Surface waves; Surface impedance; Optical surface waves; Surface impedance; hollow-core waveguide; surface-relief grating  
  Abstract A rigorous Surface Impedance (SI) formulation for planar waveguides is presented. This modal technique splits the modal analysis of the waveguide in two steps. First, we obtain the modes characteristic equations as a function of the SI and, second, we need to obtain the surface impedance values using either analytical or numerical methods. We validate the technique by comparison with well-known analytical cases: the parallel-plate waveguide with losses and the dielectric slab waveguide. Then, we analyze an optical hollow-core waveguide defined by two high-contrast subwavelength gratings validating our results by comparison with reported values. Finally, we show the potential of our formulation with the analysis of a THz hollow-core waveguide defined by two surface-relief subwavelength gratings, including material losses in our formulation.  
  Address [Coves, Angela; Maestre, Haroldo] Univ Miguel Hernandez Elche, Dept Commun Engn I3E, Elche 03202, Spain, Email: angela.coves@umh.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-3536 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000760714900001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5139  
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Author Garcfa-Barcelo, J.M.; Melcon, A.A.; Cuendis, S.A.; Diaz-Morcillo, A.; Gimeno, B.; Kanareykin, A.; Lozano-Guerrero, A.J.; Navarro, P.; Wuensch, W. url  doi
openurl 
  Title On the Development of New Tuning and Inter-Coupling Techniques Using Ferroelectric Materials in the Detection of Dark Matter Axions Type Journal Article
  Year 2023 Publication (up) IEEE Access Abbreviated Journal IEEE Access  
  Volume 11 Issue Pages 30360-30372  
  Keywords Tuning; Couplings; Permittivity; Dark matter; Magnetic resonance; Cryogenics; Receivers; Ferroelectrics; Microwave devices; Axion detection; axion-photon interaction; dark matter; ferroelectrics; haloscope; KTO; microwave resonator; STO; tuning  
  Abstract Tuning is an essential requirement for the search of dark matter axions employing haloscopes since its mass is not known yet to the scientific community. At the present day, most haloscope tuning systems are based on mechanical devices which can lead to failures due to the complexity of the environment in which they are used. However, the electronic tuning making use of ferroelectric materials can provide a path that is less vulnerable to mechanical failures and thus complements and expands current tuning systems. In this work, we present and design a novel technique for using the ferroelectric Potassium Tantalate (KTaO3 or KTO) material as a tuning element in haloscopes based on coupled microwave cavities. In this line, the structures used in the Relic Axion Detector Exploratory Setup (RADES) group are based on several cavities that are connected by metallic irises, which act as interresonator coupling elements. In this article, we also show how to use these KTaO3 films as interresonator couplings between cavities, instead of inductive or capacitive metallic windows used in the past. These two techniques represent a crucial upgrade over the current systems employed in the dark matter axions community, achieving a tuning range of 2.23% which represents a major improvement as compared to previous works (<0.1%) for the same class of tuning systems. The theoretical and simulated results shown in this work demonstrate the interest of the novel techniques proposed for the incorporation of this kind of ferroelectric media in multicavity resonant haloscopes in the search for dark matter axions.  
  Address [Garcia-Barcelo, J. M.; Melcon, A. Alvarez; Diaz-Morcillo, A.; Lozano-Guerrero, A. J.; Navarro, P.] Tech Univ Cartagena, Dept Informat & Commun Technol, Cartagena 30203, Spain, Email: josemaria.garcia@upct.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-3536 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000966674500001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5513  
Permanent link to this record
 

 
Author Berenguer, A.; Coves, A.; Gimeno, B.; Bronchalo, E.; Boria, V.E. doi  openurl
  Title Experimental Study of the Multipactor Effect in a Partially Dielectric-Loaded Rectangular Waveguide Type Journal Article
  Year 2019 Publication (up) IEEE Microwave and Wireless Components Letters Abbreviated Journal IEEE Microw. Wirel. Compon. Lett.  
  Volume 29 Issue 9 Pages 595-597  
  Keywords Dielectric; multipactor effect; rectangular waveguide; RF breakdown; Secondary Electron Yield (SEY); waveguide transformer  
  Abstract This letter presents the experimental study of the multipactor threshold in a partially dielectric-loaded rectangular waveguide, whose results validate a multipactor model recently developed by the authors, which includes the charge distribution appearing on the dielectric surface during the multipactor discharge. First, the variation of the multipactor RF voltage threshold has been theoretically analyzed in different waveguide configurations: in an empty waveguide, and also in the cases of a one-sided and two-sided dielectric-loaded waveguides. To reach this aim, an in-house Monte Carlo simulation tool has been developed. The Secondary Electron Yield (SEY) of the metallic and dielectric materials used in the numerical simulations have been measured experimentally. Finally, an aluminum WR-75 symmetric E-plane rectangular waveguide transformer has been designed and fabricated, in which several multipaction tests have been carried out to validate the in-house software tool, demonstrating an excellent agreement between the simulation results and the experimental data.  
  Address [Berenguer, Andres; Coves, Angela; Bronchalo, Enrique] Univ Miguel Hernandez Elche, Dept Commun Engn, Elche 03202, Spain, Email: angela.coves@umh.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1531-1309 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000489754400009 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4170  
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Author Zhang, X.; Chang, C.; Gimeno, B. doi  openurl
  Title Multipactor Analysis in Circular Waveguides Excited by TM01 Mode Type Journal Article
  Year 2019 Publication (up) IEEE Transactions on Electron Devices Abbreviated Journal IEEE Trans. Electron Devices  
  Volume 66 Issue 11 Pages 4943-4951  
  Keywords Circular waveguide; multipactor; ponderomotive force; TM01 mode  
  Abstract A series of detailed numerical simulations are used to investigate the properties ofmultipactor breakdown in circularwaveguidespropagating the TM01 mode. AMonte Carlo model is constructed to track the motion of the electrons, study the multipactor scenarios, and predict the multipactor thresholds. The theoretical and numerical analyses indicate that the product of the frequency and the gap (f . D) affects both the intensity of the ponderomotive force and its spatial distribution, which results from the nonuniformity of the radio frequency (RF) field and significantly influences the electrons' trajectoriesandmultipactor trends. The decrease in f . D results in a remarkable enhancement in the magnitude of the ponderomotive force, while the maximal intensity gradually moves toward the half radius R/2 area. Low values of f . D correspond to high ponderomotive potential, which sustains the short-range electrons and triggers the single-sidedmultipactor. In contrast, high values of f . D correspond to low ponderomotive potential, contributing to long-range electrons and exciting the double-sided multipactor. Fitting to the susceptibility diagram produces the border line and a modified f . D threshold of (f . D) th approximate to 338.4 GHz mm, which separates the susceptibility diagram into single-sided, double-sided, andmixed-sided zones. The initial electron energy influences their trajectories at high f . D and low RF power. This effect tends to dominate the multipactor behavior in the mixed-sided region.  
  Address [Zhang, Xue] Xiangtan Univ, Coll Informat Engn, Xiangtan 411105, Hunan, Peoples R China, Email: zhangxue.iecas@yahoo.com;  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0018-9383 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000494419900066 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4191  
Permanent link to this record
 

 
Author Zhang, X.; Xiao, Y.T.; Gimeno, B. doi  openurl
  Title Multipactor Suppression by a Resonant Static Magnetic Field on a Dielectric Surface Type Journal Article
  Year 2020 Publication (up) IEEE Transactions on Electron Devices Abbreviated Journal IEEE Trans. Electron Devices  
  Volume 67 Issue 12 Pages 5723-5728  
  Keywords Radio frequency; Dielectrics; Magnetic resonance; Discharges (electric); Surface discharges; Surface waves; Electrostatics; Monte Carlo simulation; multipactor discharge; orthogonal waves; resonant static magnetic field; secondary electron yield  
  Abstract In this article, we study the suppression of the multipactor phenomenon on a dielectric surface by a resonant static magnetic field. A homemade Monte Carlo algorithm is developed for multipactor simulations on a dielectric surface driven by two orthogonal radio frequency (RF) electric field components. When the static magnetic field is perpendicular to the tangential and normal RF electric fields, it is shown that if the normal electric field lags the tangential electric field by pi/2, the superposition of the normal and tangential electric fields will trigger a gyro-acceleration of the electron cloud and restrain the multipactor discharge effectively. By contrast, when the normal electric field is in advance of the tangential electric field by pi/2, the difference between the normal and tangential electric fields drives gyro-motion of the electron cloud. Consequently, two enhanced discharge zones are inevitable. The suppression effects of the resonant static magnetic field that is parallel to the tangential RF electric field or to the normal RF electric field are also presented.  
  Address [Zhang, Xue; Xiao, Yuting] Xiangtan Univ, Sch Automat & Elect Informat, Xiangtan 411105, Hunan, Peoples R China, Email: zhangxue.iecas@yahoo.com;  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0018-9383 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000594337700064 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4627  
Permanent link to this record
 

 
Author Gonzalez-Iglesias, D.; Esperante, D.; Gimeno, B.; Blanch, C.; Fuster-Martinez, N.; Martinez-Reviriego, P.; Martin-Luna, P.; Fuster, J.; Alesini, D. doi  openurl
  Title Analysis of the Multipactor Effect in an RF Electron Gun Photoinjector Type Journal Article
  Year 2023 Publication (up) IEEE Transactions on Electron Devices Abbreviated Journal IEEE Trans. Electron Devices  
  Volume 70 Issue 1 Pages 288-295  
  Keywords Magnetic tunneling; Multipactor effect; photoinjector; RF breakdown; RF gun  
  Abstract The objective of this work is the evaluation of the risk of suffering a multipactor discharge within an RF electron gun photoinjector. Photoinjectors are a type of source for intense electron beams, which are the main electron source for synchrotron light sources, such as free-electron lasers. The analyzed device consists of 1.6 cells and it has been designed to operate at the S-band. Besides, around the RF gun there is an emittance compensation solenoid, whose magnetic field prevents the growth of the electron beam emittance, and thus the degradation of the properties of the beam. The multipactor analysis is based on a set of numerical simulations by tracking the trajectories of the electron cloud in the cells of the device. To reach this aim, an in-house multipactor code was developed. Specifically, two different cases were explored: with the emittance compensation solenoid assumed to be off and with the emittance compensation solenoid in operation. For both the cases, multipactor simulations were carried out exploring different RF electric field amplitudes. Moreover, for a better understanding of the multipactor phenomenon, the resonant trajectories of the electrons and the growth rate of the electrons population are investigated.  
  Address [Gonzalez-Iglesias, D.; Esperante, D.; Gimeno, B.; Blanch, C.; Fuster-Martinez, N.; Martinez-Reviriego, P.; Martin-Luna, P.; Fuster, J.] Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, Paterna 46980, Spain, Email: Daniel.Gonzalez-Iglesias@uv.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0018-9383 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000890813600001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5427  
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