Electronic Properties of a Synthetic Single-Crystal Diamond Exposed to High Temperature and High Radiation

Diamond, as a wide band-gap semiconductor material, has the potential to be exploited under a wide range of extreme operating conditions, including those used for radiation detectors. The radiation tolerance of a single- crystal chemical vapor deposition (scCVD) diamond detector was therefore investigated while heating the device to elevated temperatures. In this way, operation under both high-temperature and high-radiation conditions could be tested simultaneously. To selectively introduce damage in small areas of the detector material, a 5 MeV scanning proton microbeam was used as damaging radiation. The charge collection efficiency (CCE) in the damaged areas was monitored using 2 MeV protons and the ion beam induced charge (IBIC) technique, indicating that the CCE decreases with increasing temperature. This decreasing trend saturates in the temperature range of approximately 660 K, after which CCE recovery is observed. These results suggest that the radiation hardness of diamond detectors deteriorates at elevated temperatures, despite the annealing effects that are also observed. It should be noted that the diamond detector investigated herein retained its very good spectroscopic properties even at an operation temperature of 725 K (≈2% for 2 MeV protons)

Charge transport in single crystal CVD diamond studied at high temperatures

The capability of single crystal diamonds to maintain their unique electronic properties even at high temperatures is, in particular, relevant for its applications as a radiation detector. In order to explore characteristics of charge transport at high temperatures (up to 450 °C), diamond was exposed to MeV energy ions, both, to induce radiation damage and to probe subsequent influence on detector’s properties. Dependence of mobility-lifetime product with temperature has been obtained for electrons and holes. For holes, mu-tau displays a linear degradation with rising temperature, while for electrons, change with temperature is less evident. Furthermore, deep trapping levels induced in the material by radiation damage, were studied through time-resolved charge signals. Detrapping time was extracted from this data. Hole trap level, with the activation energy of 0.53 ± 0.01 eV has been detected in the regions of the diamond detector previously irradiated by 5 MeV damaging proton beam, but not in the pristine regions. This indicates that the trap was formed due to defect induction during radiation damage exposure. Activation of this deep level is important for charge transport performance in diamond detectors operating at high temperatures and high radiation conditions

Fast-ion redistribution and loss due to edge perturbations in the ASDEX Upgrade, DIII-D and KSTAR tokamaks

The impact of edge localized modes (ELMs) and externally applied resonant and non-resonant magnetic perturbations (MPs) on fast-ion confinement/transport have been investigated in the ASDEX Upgrade (AUG), DIII-D and KSTAR tokamaks. Two phases with respect to the ELM cycle can be clearly distinguished in ELM-induced fast-ion losses. Inter-ELM losses are characterized by a coherent modulation of the plasma density around the separatrix while intra-ELM losses appear as well-defined bursts. In high collisionality plasmas with mitigated ELMs, externally applied MPs have little effect on kinetic profiles, including fast-ions, while a strong impact on kinetic profiles is observed in low-collisionality, low q(95) plasmas with resonant and non-resonant MPs. In low-collisionality H-mode plasmas, the large fast-ion filaments observed during ELMs are replaced by a loss of fast-ions with a broad-band frequency and an amplitude of up to an order of magnitude higher than the neutral beam injection prompt loss signal without MPs. A clear synergy in the overall fast-ion transport is observed between MPs and neoclassical tearing modes. Measured fast-ion losses are typically on banana orbits that explore the entire pedestal/scrape-off layer. The fast-ion response to externally applied MPs presented here may be of general interest for the community to better understand the MP field penetration and overall plasma response.Ministerio de Economía y Competitividad RYC-2011-09152, ENE2012-31087Marie Curie FP7 Integration PCIG11-GA-2012-321455US Department of Energy DE-FC02-04ER54698, SC-G903402, DEFG02- 04ER54761, DE-AC02-09CH11466, DE-FG02- 08ER54984NRF Korea 2009-008201

Energy loss of MeV protons in diamond: Stopping power and mean ionization energy

The energy loss of protons, in the range between 1.6 MeV and 6 MeV, in a 3.5 μm thick single-crystal diamond membrane was determined by the transmission method. The thickness and surface uniformity of the target were checked by two independent techniques before ion beam irradiation. The stopping power of diamond was evaluated from these data and compared with SRIM Monte Carlo simulations of ion transport, showing a slight overestimate of the simulated values over the experimental stopping powers. In addition, a comparison was made with theoretical calculations based on the Bethe formula to extract the mean ionization potential, I, of carbon atoms in diamond. The obtained I-value was 81 ± 4 eV. A discussion and comparison with results of other authors is given

Erectile Dysfunction in People with HIV – A Scoping Review

Objetivo: Exponer los factores que han sido asociados al desarrollo de disfunción eréctil (DE) en las personas con virus de la inmunodeficiencia humana (VIH) y cuál es la prevalencia de la disfunción eréctil en esta población. Métodos: Se realizó una revisión de alcance utilizando las siguientes bases de datos: MEDLINE, CENTRAL, Embase, Scopus, Lilacs, y Psycinfo. Los artículos incluidos debían tener cualquier información relacionada con la DE en personas con VIH, su prevalencia, y posibles factores asociados. Se filtraron un total de 2.726 artículos por título y resumen, y, de estos, se seleccionaron 22 referencias para revisión de texto completo y análisis. Resultados: Se encontró que las personas con VIH tienen una mayor probabilidad de presentar DE en comparación con las personas sin VIH. Algunos estudios han establecido una asociación entre la DE y trastornos psicológicos o factores orgánicos, como la lipodistrofia, la hipertensión arterial, la hipercolesterolemia, la diabetes mellitus, la depresión, la ansiedad, y el hipogonadismo. La ingesta de terapia antirretroviral (TARV), más específicamente los inhibidores de la proteasa, sigue siendo cuestionada como causante de DE en pacientes con VIH. Conclusiones: Ante un paciente con diagnóstico de VIH, se debe ahondar sobre DE con el fin de recomendar e iniciar conductas terapéuticas que aseguren un mejoramiento en su calidad de vida.Q4Hombres con Virus de la Inmunodeficiencia Humana (VIH)Aim: To present factors that have been associated with the development of erectile dysfunction (ED) in people with human immunodeficiency virus (HIV) and the frequency of erectile dysfunction among this population. Methods: We performed a scoping review on the following databases: MEDLINE, CENTRAL, Embase, Scopus, Lilacs, and Psycinfo. The articles included information related to ED in people with HIV, its frequency, and possible associated factors. A total of 2,726 articles were filtered by title and abstract, and, from these, 22 references were selected for full-text review and analysis. Results: People with HIV were found to be more likely to have ED compared to people without HIV. Some studies have established an association between ED and psychological disorders or organic factors, such as lipodystrophy, high blood pressure, hypercholesterolemia, diabetes mellitus, depression, anxiety, and hypogonadism. The intake of antiretroviral therapy (ART), more specifically protease inhibitors, continues to be questioned as a cause of ED in patients with HIV. Conclusions: In HIV-positive men, we recommend to actively seek ED in order to initiate therapeutic conducts that can ensure an improvement in their quality of life.https://orcid.org/0000-0002-1416-3201https://orcid.org/0000-0003-3355-2816https://orcid.org/0000-0002-2914-429Xhttps://orcid.org/0000-0002-0885-7960https://orcid.org/0000-0002-5895-3029Revista Nacional - IndexadaCN

Characterisation of the fast-ion edge resonant transport layer induced by 3D perturbative fields in the ASDEX Upgrade tokamak through full orbit simulations

In recent experiments at the ASDEX Upgrade tokamak the existence of an Edge Resonant Transport Layer (ERTL) was revealed as the main transport mechanism responsible for the measured fast-ion losses in the presence of externally applied 3D fields. The Monte Carlo orbit-following code ASCOT was used to study the fast-ion transport including the plasma response calculated with MARS-F, reproducing a strong correlation of fast-ion losses with the poloidal mode spectra of the 3D fields. In this work, a description of the physics underlying the ERTL is presented by means of numerical simulations together with an analytical model and experimental measurements to validate the results. The degradation of fast-ion confinement is calculated in terms of the variation of the toroidal canonical momentum (δPϕ). This analysis reveals resonant patterns at the plasma edge activated by 3D perturbations and emphasizes the relevance of nonlinear resonances. The impact of collisions and the radial electric field on the ERTL is analysed.EUROfusion Consortium 633053French National Research Agency (ANR) ANR-11-IDEX-0001-0

Velocity-space sensitivity and tomography of scintillator-based fast-ion loss detectors

A simple model for the instrument function of scintillator-based fast-ion loss detectors (FILD) has been developed which accounts for the orbit trajectories in the 3D detector geometry and for the scintillator response. It allows us to produce synthetic FILD signals for a direct comparison between experiments and simulations. The model uses a weight function formalism to relate the velocity-space distribution of fast-ion losses reaching the detector pinhole to the scintillator pattern obtained experimentally, which can be understood as a distortion of the velocity-space distribution due to the finite resolution of the system. The tool allows us to recover the undistorted velocity-space distribution of the absolute flux of fast-ion losses reaching the detector pinhole from an experimental measurement using tomographic inversion methods, which can reveal additional details of the velocity-space distribution of the lost ions.Spanish Ministry of Economy and Competitiveness FIS2015-69362-P (MINECO/ FEDER,UE), RYC-2011-09152 and ENE2012-31087Marie Curie FP7 Integration Grant (No. PCIG11-GA-2012-321455)EUROfusion Consortium 63305

Improved objective bayesian estimator for a PLP model hierarchically represented subject to competing risks under minimal repair regime

In this paper, we propose a hierarchical statistical model for a single repairable system subject to several failure modes (competing risks). The paper describes how complex engineered systems may be modelled hierarchically by use of Bayesian methods. It is also assumed that repairs are minimal and each failure mode has a power-law intensity. Our proposed model generalizes another one already presented in the literature and continues the study initiated by us in another published paper. Some properties of the new model are discussed. We conduct statistical inference under an objective Bayesian framework. A simulation study is carried out to investigate the efficiency of the proposed methods. Finally, our methodology is illustrated by two practical situations currently addressed in a project under development arising from a partnership between Petrobras and six research institutes