ATLAS Pixel Detector: Operational Experience and Run-1 to Run-2 Transition

The Pixel Detector of the ATLAS experiment has shown excellent performance during the whole Run-1 of LHC. Taking advantage of the long shutdown, the detector was extracted from the experiment and brought to surface, to equip it with new service quarter panels, to repair modules and to ease installation of a new innermost layer, the Insertable B-Layer (IBL). An overview of the operational experience, the refurbishing of the Pixel Detector and of the IBL project as well as the experience in its construction, integration and commissioning are described.Comment: presented at VERTEX 2014 - 23rd International Workshop on Vertex Detectors, Doksy, Czech Republic, 15 Sep 2014. PoS(Vertex2014)00

ATLAS IBL: a challenging first step for ATLAS Upgrade at the sLHC

With the LHC collecting data at 7 TeV, plans are already advancing for a series of upgrades leading eventually to about five times the LHC design luminosity some 10 years from now in the High Luminosity LHC (HL-LHC) project. The upgrades for ATLAS detector will be staged in preparation for HL-LHC. The first upgrade for the Pixel Detector will be the construction of a new pixel layer, which will be installed during the first shutdown of the LHC machine foreseen in 2013-14. The new detector, called the Insertable B-Layer (IBL) will be installed between the existing Pixel Detector and a new, smaller radius beam-pipe at the radius of 3.2 cm. The IBL will require the development of several new technologies to cope with increased radiation and pixel occupancy and also to improve the physics performance through reduction of the pixel size and more stringent material budget. Two different and promising Silicon sensor technologies (planar n-in-n and 3D) are currently under investigation for the IBL. An overview of the IBL module design and the qualification for these sensor technologies are presented in this proceeding. This proceeding also summarizes the improvements expected to the ATLAS detector at the HL-LHC.Comment: 4 pages, 2 figures, Proceeding of XXIst International Europhysics Conference on High Energy Physics (EPS-HEP 2011), Grenoble, 21-27 July 201

Studies on ToF-PET using Cherenkov radiation

La tomografia ad emissione di positroni (PET) è una tecnica di imaging di medicina nucleare, utilizzata oggi diffusamente in ambito clinico. Essa fornisce immagini e informazioni fisiologiche dei processi funzionali all’interno del corpo. La PET si basa sulla rilevazione di fotoni di annichilazione prodotti in seguito al decadimento di un radio farmaco iniettato nel paziente. I rilevatori convenzionali sono costituiti da un materiale scintillatore accoppiato ad un fotomoltiplicatore, solitamente un PMT o SiPM. Uno sviluppo della PET è la Time of Flight PET (ToF PET), attualmente già in commercio ed utilizzata con prestazioni eccellenti. Un’ulteriore modifica, che potenzialmente permetterebbe di ottenere una migliore risoluzione temporale, è la ToF PET basata sulla rilevazione di fotoni tramite radiazione Cherenkov, invece che luce di scintillazione. Questo lavoro di tesi è incentrato dunque su questa tecnica specifica. Si illustra una rassegna di pubblicazioni scientifiche degli ultimi anni riguardo ad essa con i relativi risultati ottenuti e i possibili sviluppi futuri. Infine si propone un approfondimento personale, nel quale, tramite un programma scritto in ROOT, si è realizzata una geometria di un sistema di rilevazione ToF PET. Esso prevede la rilevazione dei fotoni di annichilazione tramite un radiatore Cherenkov accoppiato ad un SiPM. In futuro questo potrà essere implementato e utilizzato per simulare il processo fisico della PET, verificando la validità e le prestazioni del sistema così sviluppato

The particle-hole transformation, supersymmetry and achiral boundaries of the open Hubbard model

We show that the particle-hole transformation in the Hubbard model has a crucial role in relating Shastry's R-matrix to the AdS/CFT S-matrix. In addition, we construct an achiral boundary for the open Hubbard chain which possesses twisted Yangian symmetry

Dreamt Spaces

Beyond a mere interdisciplinary relationship, the symbiosis of cinema, body and architecture conveys an illusion: showing a dreamt architecture. The vision of architecture through a cinematographic filter facilitates infinite possibilities, from creating habitability conditions in impossible spaces to endowing architecture with unimaginable attributes. Aspects such as movement or dematerialization, in principle far from classic architectural values, have a familiar ring due to experiences gained in cinema. Likewise, in recent decades architecture has dared to carry out spatial experiments whose only objective is experimentation on the interrelation between body and space. Despite the importance of this question to the perception of certain architecture, during many years architects absented themselves from this field of experimentation. In the majority of the cases, as mere spectators, they limited themselves exclusively to observe the proposals of some artists and film-makers who transformed space just in another plastic material. Many of these proposals of "space alteration" were left in the dust, however, some of them established a basis for certain events to come which would change forever the traditional ways of understanding space. This new perception emerging from cinematic images poses new processes of connectivity between body and space, as we may observe in some of the works of the US Americans Diller & Scofidio, intimately related to new technologies. Others, like Philippe Rahm, focus on the fusion of biological and sensorial aspects of life forms in determinate spaces. Some like the Fabric team propose a deliberate alteration of perceiving the interior-exterior interaction of habitable spaces by means of addition and fusion. None of the above is science fiction, but we can elaborate a new architectural map with clear cinematographic references

Overconfidence in a Career-Concerns Setting

We study the effects of overconfidence in a two-period investment-decision agency setting. Under common priors, agent risk aversion implies inefficiently low first-period investment. In our model, principal and agent disagree about the profitability of the investment decision conditional on a given public signal. An overconfident agent believes that the principal will update her beliefs upwards more often than not. As a consequence, the agent overestimates the benefits of learning from first-period investment. This implies that agent overconfidence mitigates the agency problems arising from the agent’s career concerns, even though an overconfident agent bears more project and reputational risk in equilibrium.overconfidence, heterogenous beliefs, career concerns

Ataques Especulativos: Un Enfoque de Incertidumbre e Información

Durante la década pasada hemos presenciado una proliferación de crisis cambiarias, tanto en Asia como en Europa y Latinoamérica, acompañada de abundante literatura acerca del tema. Es aceptado que, cuando las políticas monetaria y fiscal no son congruentes entre sí, habrá una crisis de balanza de pagos. La literatura reciente ha avanzado en varias direcciones para explicar los mecanismos de propagación de una crisis, que aplican aún cuando la política del gobierno es sostenible. No obstante, este tipo de modelos explica escasamente la iniciación de un ataque. El objetivo de este artículo es dar una explicación tentativa a esa iniciación. Se presenta un modelo donde la obtención de información es crucial para el inversionista y ésta se deteriora con el tiempo; en este marco, el ataque especulativo es un comportamiento óptimo para un inversionista que tenga la capacidad de llevarlo a cabo. Del modelo puede concluirse, entre otras cosas, que existe una relación inversa entre la frecuencia y la profundidad de los ataques. Además, el tamaño del agente relativo a la economía y la fuerza del efecto manada afectan de manera importante los costos del ataque y, de esta forma, afectan también la vulnerabilidad de cada economía a sufrir ataques especulativos.

Revisión teórica de la técnica de radares de dispersión incoherente y su conexión con las ecuaciones diferenciales estocásticas

The Incoherent Scatter Radar (ISR) technique provides an important tool for ionospheric plasma parameter estimation through the calculation of the electron density spectrum. This quantity is constrained to the ionospheric approximations considered. If these are very realistic, finding an analytical expression for the terms involve in the electron density spectrum could be impossible. In that sense, using the mathematical tool known as stochastic differential equation (SDE) is required. Because of the nature of the equation described the ionospheric particle dynamics, called Langevin equation, stochastic numerical methods have to be studied. In this work, we will present a review of ISR theory and the connection to SDE. Moreover, we list three different methods, which are used to analyze the collisional and magnetized approximation of the ionosphere.Trabajo de investigació