Design and Characterization of 64K Pixels Chips Working in Single Photon Processing Mode

Progress in CMOS technology and in fine pitch bump bonding has made possible the development of high granularity single photon counting detectors for X-ray imaging. This thesis studies the design and characterization of three pulse processing chips with 65536 square pixels of 55 µm x 55 µm designed in a commercial 0.25 µm 6-metal CMOS technology. The 3 chips share the same architecture and dimensions and are named Medipix2, Mpix2MXR20 and Timepix. The Medipix2 chip is a pixel detector readout chip consisting of 256 x 256 identical elements, each working in single photon counting mode for positive or negative input charge signals. The preamplifier feedback provides compensation for detector leakage current on a pixel by pixel basis. Two identical pulse height discriminators are used to define an energy window. Every event falling inside the energy window is counted with a 13 bit pseudo-random counter. The counter logic, based in a shift register, also behaves as the input/output register for the pixel. Each cell also has an 8-bit configuration register which allows masking, test-enabling and 3-bit individual threshold adjust for each discriminator. The chip can be configured in serial mode and readout either serially or in parallel. Measurements show an electronic noise ~160 e- rms with a gain of ~9 mV/ke-. The threshold spread after equalization of ~120 e- rms brings the full chip minimum detectable charge to ~1100 e-. The analog static power consumption is ~8 µW per pixel with Vdda=2.2 V. The Mpix2MXR20 is an upgraded version of the Medipix2. The main changes in the pixel consist of: an improved tolerance to radiation, improved pixel to pixel threshold uniformity, and a 14-bit counter with overflow control. The chip periphery includes new threshold DACs with smaller step size, improved linearity, and better temperature dependence. Timepix is an evolution of the Mpix2MXR20 which provides independently in each pixel information of arrival time, time-over-threshold or event counting. Timepix uses as a time reference an external clock (Ref_Clk) up to 100 MHz which is distributed all over the pixel matrix during acquisition mode. The preamplifier is improved and there is a single discriminator with 4-bit threshold adjustment in order to reduce the minimum detectable charge limit. Measurements show an electrical noise ~100 e- rms and a gain of ~16.5 mV/ke-. The threshold spread after equalization of ~35 e- rms brings the full chip minimum detectable charge either to ~650 e- with a naked chip (i.e. gas detectors) or ~750 e- when bump-bonded to a detector. The pixel static power consumption is ~13.5 µW per pixel with Vdda=2.2 V and Ref_Clk=80 MHz. This family of chips have been used for a wide variety of applications. During these studies a number of limitations have come to light. Among those are limited energy resolution and surface area. Future developments, such as Medipix3, will aim to address those limitations by carefully exploiting developments in microelectronics

La situació de la formació d'accés dels futurs auditors

Des de la creació de la Comunitat Econòmica Europea s'ha mostrat un especial interès per resoldre l'assumpte de la manca d'homogeneïtat del sistema formatiu universitari, marcat també pels múltiples aspectes culturals derivats dels països integrants del projecte. Amb les successives ampliacions s'ha anat generant una situació més i més dispar entre la formació universitària impartida als diferents països, la qual cosa ha suposat un fre important a la lliure circulació de persones dins l'àmbit laboral professionalitzat (no entrarem en temes de democratització de l'ensenyament i el finançament de la universitat, que podrien ser l'eix central d'altres articles)

Gamificació, simulació, aula inversa, ... noves metodologíes per a la formació en Direcció i Gestió d'Empreses

Barcelona té una llarga tradició i prestigi en universitats i centres privats de formació orientats als ensenyaments de Direcció i Gestió d'Empreses. Escoles de negocis com, per exemple, IESE i ESADE o la Universitat de Barcelona i la Universitat Pompeu Fabra, ocupen els primers llocs a nivell mundial com a referents de centres formatius segons diferents paràmetres i a diferents rànquings internacionals

Aprendre noves eines i metodologies. La formació a partir del canvi de paradigma 120320

La darrera vegada que em van demanar un article per a la revista de l'Auditor (d'això fa uns dos anys) vaig introduir noves metodologies que s'estan emprant en la formació professional orientada a l'àmbit de Direcció i Gestió d'Empreses, des de fa uns anys. Noves metodologies que tenen com a objectiu desenvolupar persones (a diferència de l'orientació anterior d'ensenyar), amb una clara orientació a habilitats directives i de gestió i que busquen utilitzar noves eines que les tecnologies emergents posen a l'abast

Pasaje al acto

El artista se debe a la producción, pero ¿cómo interaccionan producción e investigación artística en el contexto actual? Tras analizar el discurso artístico, la conclusión es que tal vez no deberíamos arrastrar la investigación artística hacia lo que habitualmente llamamos investigación, ya que su forma de proceder raramente conduce a resultados objetivos y la búsqueda experimental se inicia sin planteamientos claros, de modo que el arte acontece, sin que el que lo hace quiera saber de él mientras lo practica. Con todo, sólo la indagación en lo que le rodea puede hacerle evolucionar.The artist has a duty to produce something, but how do artistic research and the production of something interact in today’s context? After analysing artistic discussion, the conclusion is that perhaps we should not drag artistic research towards what we normally call research, since the methods used rarely lead to objective results and experimental searches do not start out with a clearly-formed approach, such that art happens, without the person producing it wishing to know of it at the time. Only by investigating all that surrounds it, can it evolve

Estrategia, estructura, cultura y recursos humanos

Relación entre la estrategia empresarial, la estructura de una empresa, su cultura y la gestión de personas en el marco de una control adecuado de la gestión de las compañías

X-ray imaging using single photon processing with semiconductor pixel detectors

More than 10 years experience with semiconductor pixel detectors for vertex detection in high energy physics experiments together with the steady progress in CMOS technology opened the way for the development of single photon processing pixel detectors for various applications including medical X-ray imaging. The state of the art of such pixel devices consists of pixel dimensions as small as 55x55 um2, electronic noise per pixel <100 e- rms, signal-to-noise discrimination levels around 1000 e- with a spread <50 e- and a dynamic range up to 32 bits per pixel. Moreover, the high granularity of hybrid pixel detectors makes it possible to probe inhomogeneities of the attached semiconductor sensor

Expansion of the exotic unionid Sinanodonta woodiana in low Ter River flood plain (Catalonia)

Póster presentado en: 2nd International Seminar Rearing of unionoid mussels (Clervaux, Luxembourg - Tuesday 24th November – Friday 27th November 2015)In the northeast Catalonia, 4 native unionid species have been cited: Potomida littoralis (Cuvier, 1798), Unio mancus Lamarck, 1819, Unio ravoisieri Deshayes, 1847, and Anodonta anatina (L, 1758). Recently the exotic Sinanodonta woodiana (Lea, 1834), has been cited on Ter and Fluvià rivers. Between 1995 and 2014, several specific surveys were carried out, always below the Pasteral dam, both in the Ter river and in several of its tributaries, including Lake Banyoles. Moreover, from 2010 to 2014 a thorough freshwater bivalves prospection campaign was performed in the alluvial plain of lower Ter, including the river and secondary water masses, mainly irrigation channels associated with the traditional system of agricultural irrigation. The prospections were done by manually on the river bed bottom. All over since 2010 a total of 90 sampling stations has been surveyed in this alluvial plain. Status of native species is precarious, with populations intensely fragmented, and densities often low and heavily aged for lack of recruitment. This situation is clearly attributable to the severe rarefaction of native fish species, since in some areas even completely inexistent. In contrast, the exotic S. woodiana is expanding and occupies already the whole alluvial plain and the lower course of the Ter river, where it is very abundant. Moreover, S. woodiana presents a well-structured global population in the alluvial plain of Ter River and a regular recruitment can be observed thanks to the fact that several exotic fish species are abundant in the area, are potential hosts to them. This exotic unionoid appeared in most of the surveyed localities (81%), and was present in all the types of water bodies surveyed. In 16 % of the localities it was the only unionoid found, and it was present in all of the localities were other unionoid species were present. Specimens of this exotic species found alive constituted the 72 % of the total of alive unionoids collected during the surveying campaigns. Besides this species were quantitatively dominant in the whole of the alluvial plain. Therefore, it is the most spread and abundant unionoid species at present, often with very high densities. It presented a continuous distribution in the lower Ter river basin, as well as in the main irrigation canals.Peer reviewe

A Study on Goodwill Accounting Based on the Corporate Competence Theory

在一个多世纪的时间里，商誉问题一直是会计研究领域内极具魅力的主题之一。如今，随着企业的价值创造过程日益依赖于无形资源，随着企业并购市场的日趋扩大，人们对于商誉这个超越了具体产品和服务、提升了企业整体价值的战略性资产日益重视，也更加渴求有关它的高质量会计信息。有关商誉的论述浩如烟海，然而，人们对于商誉的许多问题仍争辩激烈，莫衷一是。本文依据战略管理领域内迅速发展的一种理论——“企业能力论”来对商誉作一系统的研究，希望通过相关学科知识的引入来为商誉研究的发展作出一些贡献。 本文分为八章来进行论述：第一章为引言。第二章进行了系统的文献回顾。第三章介绍了企业能力论，并提出了资源和能力基础的商誉定义，...Since the beginning of last century, goodwill has been an extremely attractive topic in accounting. Nowadays, with the corporate value creation process depending more on intangible resources, and the acquisition and merger market growing dramatically, people pay more attention to goodwill, which overtakes specific product and service and adds to the whole corporate value. Also, people desire for m...学位：管理学硕士院系专业：管理学院会计系_会计学学号：2005130118

20-ps resolution Clock Distribution Network for a fast-timing single photon detector

The time resolution of active pixel sensors whose timestamp mechanism is based on Time-to-Digital Converters is critically linked to the accuracy in the distribution of the master clock signal that latches the timestamp values across the detector. The Clock Distribution Network that delivers the master clock signal must compensate process-voltage-temperature variations to reduce static time errors (skew), and minimize the power supply bounce to prevent dynamic time errors (jitter). To achieve sub-100ps time resolution within pixel detectors and thus enable a step forward in multiple imaging applications, the network latencies must be adjusted in steps well below that value. Power consumption must be kept as low as possible. In this work, a self-regulated Clock Distribution Network that fulfills these requirements is presented for the FastICpix single photon detector ¿ aiming at a 65nm process. A 40 MHz master clock is distributed to 64x64 pixels over an area of 2.4x2.4 cm2 using digital Delay-Locked Loops, achieving clock leaf skew below 20 ps with a power consumption of 26 mW. Guidelines are provided to adapt the system to arbitrary chip area and pixel pitch values, yielding a versatile design with very fine time resolution