319 research outputs found
Inverse Low Gain Avalanche Detectors (iLGADs) for precise tracking and timing applications
Low Gain Avalanche Detector (LGAD) is the baseline sensing technology of the
recently proposed Minimum Ionizing Particle (MIP) end-cap timing detectors
(MTD) at the Atlas and CMS experiments. The current MTD sensor is designed as a
multi-pad matrix detector delivering a poor position resolution, due to the
relatively large pad area, around 1 ; and a good timing resolution,
around 20-30 ps. Besides, in his current technological incarnation, the timing
resolution of the MTD LGAD sensors is severely degraded once the MIP particle
hits the inter-pad region since the signal amplification is missing for this
region. This limitation is named as the LGAD fill-factor problem. To overcome
the fill factor problem and the poor position resolution of the MTD LGAD
sensors, a p-in-p LGAD (iLGAD) was introduced. Contrary to the conventional
LGAD, the iLGAD has a non-segmented deep p-well (the multiplication layer).
Therefore, iLGADs should ideally present a constant gain value over all the
sensitive region of the device without gain drops between the signal collecting
electrodes; in other words, iLGADs should have a 100 fill-factor by
design. In this paper, tracking and timing performance of the first iLGAD
prototypes is presented.Comment: Conference Proceedings of VCI2019, 15th Vienna Conference of
Instrumentation, February 18-22, 2019, Vienna, Austri
Recent Technological Developments on LGAD and iLGAD Detectors for Tracking and Timing Applications
This paper reports the last technological development on the Low Gain
Avalanche Detector (LGAD) and introduces a new architecture of these detectors
called inverse-LGAD (iLGAD). Both approaches are based on the standard
Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray
detection applications, including an internal multiplication of the charge
generated by radiation. The multiplication is inherent to the basic n++-p+-p
structure, where the doping profile of the p+ layer is optimized to achieve
high field and high impact ionization at the junction. The LGAD structures are
optimized for applications such as tracking or timing detectors for high energy
physics experiments or medical applications where time resolution lower than 30
ps is required. Detailed TCAD device simulations together with the electrical
and charge collection measurements are presented through this work.Comment: Keywords: silicon detectors, avalanche multiplication, timing
detectors, tracking detectors. 8 pages. 8 Figure
Los Indicadores de calidad de agua como una herramienta para la integración de contenidos de recursos hídricos, mediante la metodología de enseñaza por proyectos
La enseñanza de las ciencias tiene potencialidades muy significativas para desarrollar competencias que requieren los alumnos para su desempeño en la sociedad, esto se lograría a través de dos procesos largos y complejos que son la alfabetización científica y la educación ambiental. Ambos procesos actúan como herramientas para la toma de medidas. Actualmente los temas relacionados con el medio ambiente, se han posicionado en las agendas sociales, políticas y educativas con gran fuerza. La enseñanza de temas medioambientales, dado su complejidad y su abordaje sistémico, implica la reformulación de las estrategias didácticas a utilizar. En particular, el método de enseñanza por proyectos, puede considerarse como apropiado para tal fin. Es por ello que esta metodología de enseñanza permite vincular temáticas o problemas que sean de interés para los alumnos y que merezcan ser tratados por sí mismos, como lo es el Índice de Calidad de Agua (ICA) del Arroyo del Azul, situado en el centro de la Pcia. de Buenos Aires. Así mismo, en el desarrollo de la presente ponencia se incluye la aplicación del ICA en agua del Arroyo del Azul, con el fin de reconocer su Calidad de Agua. Este tipo de trabajos permite reformular prácticas que lleven a los alumnos a trabajar en forma conjunta con el docente, el trabajo en temas que sean de interés o que tengan un significado en la sociedad y que los alumnos realicen actividades y experiencias que los lleve a comprender y realizar un cambio conceptual.Trabajos del área Ciencias NaturalesDepartamento de Ciencias Exactas y Naturale
Los Indicadores de calidad de agua como una herramienta para la integración de contenidos de recursos hídricos, mediante la metodología de enseñaza por proyectos
La enseñanza de las ciencias tiene potencialidades muy significativas para desarrollar competencias que requieren los alumnos para su desempeño en la sociedad, esto se lograría a través de dos procesos largos y complejos que son la alfabetización científica y la educación ambiental. Ambos procesos actúan como herramientas para la toma de medidas. Actualmente los temas relacionados con el medio ambiente, se han posicionado en las agendas sociales, políticas y educativas con gran fuerza. La enseñanza de temas medioambientales, dado su complejidad y su abordaje sistémico, implica la reformulación de las estrategias didácticas a utilizar. En particular, el método de enseñanza por proyectos, puede considerarse como apropiado para tal fin. Es por ello que esta metodología de enseñanza permite vincular temáticas o problemas que sean de interés para los alumnos y que merezcan ser tratados por sí mismos, como lo es el Índice de Calidad de Agua (ICA) del Arroyo del Azul, situado en el centro de la Pcia. de Buenos Aires. Así mismo, en el desarrollo de la presente ponencia se incluye la aplicación del ICA en agua del Arroyo del Azul, con el fin de reconocer su Calidad de Agua. Este tipo de trabajos permite reformular prácticas que lleven a los alumnos a trabajar en forma conjunta con el docente, el trabajo en temas que sean de interés o que tengan un significado en la sociedad y que los alumnos realicen actividades y experiencias que los lleve a comprender y realizar un cambio conceptual.Trabajos del área Ciencias NaturalesDepartamento de Ciencias Exactas y Naturale
Radiation Hardness of Thin Low Gain Avalanche Detectors
Low Gain Avalanche Detectors (LGAD) are based on a n++-p+-p-p++ structure
where an appropriate doping of the multiplication layer (p+) leads to high
enough electric fields for impact ionization. Gain factors of few tens in
charge significantly improve the resolution of timing measurements,
particularly for thin detectors, where the timing performance was shown to be
limited by Landau fluctuations. The main obstacle for their operation is the
decrease of gain with irradiation, attributed to effective acceptor removal in
the gain layer. Sets of thin sensors were produced by two different producers
on different substrates, with different gain layer doping profiles and
thicknesses (45, 50 and 80 um). Their performance in terms of gain/collected
charge and leakage current was compared before and after irradiation with
neutrons and pions up to the equivalent fluences of 5e15 cm-2. Transient
Current Technique and charge collection measurements with LHC speed electronics
were employed to characterize the detectors. The thin LGAD sensors were shown
to perform much better than sensors of standard thickness (~300 um) and offer
larger charge collection with respect to detectors without gain layer for
fluences <2e15 cm-2. Larger initial gain prolongs the beneficial performance of
LGADs. Pions were found to be more damaging than neutrons at the same
equivalent fluence, while no significant difference was found between different
producers. At very high fluences and bias voltages the gain appears due to deep
acceptors in the bulk, hence also in thin standard detectors
Gain and time resolution of 45 m thin Low Gain Avalanche Detectors before and after irradiation up to a fluence of n/cm
Low Gain Avalanche Detectors (LGADs) are silicon sensors with a built-in
charge multiplication layer providing a gain of typically 10 to 50. Due to the
combination of high signal-to-noise ratio and short rise time, thin LGADs
provide good time resolutions.
LGADs with an active thickness of about 45 m were produced at CNM
Barcelona. Their gains and time resolutions were studied in beam tests for two
different multiplication layer implantation doses, as well as before and after
irradiation with neutrons up to n/cm.
The gain showed the expected decrease at a fixed voltage for a lower initial
implantation dose, as well as for a higher fluence due to effective acceptor
removal in the multiplication layer. Time resolutions below 30 ps were obtained
at the highest applied voltages for both implantation doses before irradiation.
Also after an intermediate fluence of n/cm, similar
values were measured since a higher applicable reverse bias voltage could
recover most of the pre-irradiation gain. At n/cm, the
time resolution at the maximum applicable voltage of 620 V during the beam test
was measured to be 57 ps since the voltage stability was not good enough to
compensate for the gain layer loss. The time resolutions were found to follow
approximately a universal function of gain for all implantation doses and
fluences.Comment: 17 page
Recent technological developments on LGAD and iLGAD detectors for tracking and timing applications
Proceeding of the 10th International “Hiroshima” Symposium on the Development and Application of Semiconductor Tracking Detectors.-- et al.This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n–p–p structure, where the doping profile of the p layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.This work was developed in the framework of the CERN RD50 collaboration and financed by the Spanish Ministry of Economy and Competitiveness through the Particle Physics National Program (FPA2013-48308-C2-2-P, FPA2014-55295-C3-2-R and FPA2013-48387-C6-1-P). This project has received funding from the European Union's Horizon 2020 Research and Innovation program under Grant Agreement no. 654168 (AIDA-2020).Open Access funded by CERN.Peer Reviewe
Defense Related Phytohormones Regulation in Arbuscular Mycorrhizal Symbioses Depends on the Partner Genotypes
Sero-epidemiologia de la toxoplasmosis en dos comunidades de Rwanda (Africa Central)
Se ha estudiado la prevalência de anticuerpos antitoxoplasma en dos comunidades rurales rwandesas, utilizando sangre total desecada en papel de filtro que se procesó por la técnica de Aglutinación Directa. En ambas comunidades están afectados el 50% de los adultos. La adquisición de los anticuerpos se hace tardiamente en NGD (a los 14 años sólo un 12% de la problación muestra anticuerpos antitoxoplasma) y más pronto en NVU (31% de la población estudiada tiene anticuerpos antitoxoplasma a los 14 años). Se destaca el posible papel que juega esta enfermedad en la patología materno-fetal, y la necesidad de nuevos studios que aumenten el conocimiento de la epidemiología de la toxoplasmosis y sus mecanismos de transmisión en Rwanda.We collected dry blood specimens from two rural areas in Rwanda, that were tested for anti bodies to Toxoplasma gondii through the Direct Agglutination technique. 50% of the adults in both communities had antibodies to T. gondii. The Ngenda (NGD) po pulation apparently acquired antibodies at a la ter stage of its life (only 12% were positive at 14 years of age). The Nyarutovu (NVU) popula tion already showed a 31% positivity at the same age. We would like to point out the pathogenic role played by toxoplasmosis during pregnancy and the need of new studies about the epidemiology of the disease as well as the transmission mechanism in Rwanda
Farmacología y toxicología en I+D+i: adquisición de competencias a través de un ejemplo de desarrollo de un fármaco
The implementation of the subject Pharmacology and Toxicology in R+D+i in the Pharmacy Degree, has led to the launch of a new methodological approach and teaching performance with the aim of developing the generic skills of the University of Barcelona (e.g., self-learning, team-working). An additional objective was students' integration of knowledge from different subjects in the degree which form the basis of the preclinical and clinical development of a drug. For this purpose, the teaching strategy used in the development of the subject was based on: 1) re-developing the content that students had been taught previously or were being taught in the same semester as a part of other subjects, and framing them in the environment of the pharmaceutical industry, 2) introducing new and previously unseen contents to do with drug development and toxicology, 3) developing a battery of activities to be undertaken by teams of students relating to the R+D+i of a particular drug. During the development of these activities, students have to acquire generic skills in addition to the subject-specific skills. The results obtained from the student survey give us grounds for satisfaction and allow us to consider that we have reached the goal of improving students' learning in Pharmacology and Toxicology applied to drug development in the pharmaceutical world today
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