1,721,335 research outputs found
Status of the 3D Silicon Detectors activities at FBK
No full textIn the talk, ongoing activities on 3D processes will be presented. FBK is actively involved in the realization of detectors with RD53 and CROC designs for both ATLAS and CMS experiments. The latest developments and parametric measurements with Temporary Metal for these processes will be discussed. Additionally, FBK is continuing the development of 3D sensors based on trenches. Due to their geometry, these sensors are considered candidates for achieving excellent temporal resolutions along with high damage resistance. In the AIDA Innova project, FBK is producing a batch, and the main characteristics of this batch will be highlighted
Low gain avalanche diodes for photon science applications
No full textLow Gain Avalanche Diodes (LGADs) are silicon sensors designed to achieve an internal gain in the order of 10 through the impact ionization process. The development of LGADs was pushed forward by their application in High Energy Physics (HEP) experiments, where they will be employed to provide measurements of the time of arrival of minimum ionizing particles with a resolution of around 30 ps. The initial technological implementation of the sensors constrains their minimum channel size to be larger than 1 mm2, in order to reduce inefficiencies due to the segmentation of the gain structure. The gain of the sensors is kept in the order of 10 to limit the sensor shot noise and their power consumption. In photon science, the gain provided by the sensor can boost the signal-to-noise ratio of the detector system, effectively reducing the x-ray energy threshold of photon counting detectors and the minimum x-ray energy where single photon resolution is achieved in charge integrating detectors. This can improve the hybrid pixel and strip detectors for soft and tender x-rays by simply changing the sensor element of the detector system. Photon science applications in the soft and tender energy range require improvements over the LGADs developed for HEP, in particular the presence of a thin entrance window to provide a satisfactory quantum efficiency and channel size with a pitch of less than 100 μm. In this review, the fundamental aspects of the LGAD technology are presented, discussing also the ongoing and future developments that are of interest for photon science applications
Radiation Tolerance of Proton-Irradiated LGADs
No full textLow gain avalanche detectors (LGADs), silicon sensors with intrinsic charge amplification, are being considered as a possible technology for tracking and timing in the high luminosity upgrade of the CERN Large Hadron Collider. In order to work in such an environment, LGADs must be sufficiently radiation hard. The characterisation before and after irradiation of properties, such as gain, charge collection, spatial homogeneity, space charge, and leakage current, is vital for assessing the performance and viability of LGADs. This paper presents the results obtained from the study of LGADs irradiated with 24-GeV/c protons up to a maximum fluence of 10 15 neq/cm 2 . The characterisation was performed mainly by means of the transient current technique with red and infrared laser pulses. It was found that the gain decreases with increasing fluence. At a fluence of 10 15 neq/cm 2 , the charge collected is similar to that of a normal p-i-n diode. Whilst this might be explained by an effective acceptor removal, it was also found that there are clear signs of a double junction in these devices, after irradiation. In addition, the spatial charge collection homogeneity before and after irradiation was evaluated
Silicon Sensors for the Upgrades of the CMS Pixel Detector
No full textThe Compact Muon Solenoid (CMS) is a general purpose detector at the Large Hadron Collider (LHC). The LHC luminosity is constantly increased through upgrades of the accelerator and its injection chain. Two major upgrades will take place in the next years. The rst upgrade involves the LHC injector chain and allows the collider to achieve a luminosity of about 2 10 34 cm-2 s-1 A further upgrade of the LHC foreseen for 2025 will boost its luminosity to 5 10 34 cm-2 s1. As a consequence of the increased luminosity, the detectors need to be upgraded. In particular, the CMS pixel detector will undergo two upgrades in the next years. The first upgrade (phase I) consists in the substitution of the current pixel detector in winter 2016/2017. The upgraded pixel detector will implement new readout electronics that allow efficient data taking up to a luminosity of 2 10 34 cm-2s-1,twice as much as the LHC design luminosity. The modules that will constitute the upgraded detector are being produced at different institutes. Hamburg (University and DESY) is responsible for the production of 350 pixel modules. The second upgrade (phase II) of the pixel detector is foreseen for 2025. The innermost pixel layer of the upgraded detector will accumulate a radiation damage corresponding to an equivalent fluence of eq = 2 10 16 cm-2 and a dose of 10 MGy after an integrated luminosity of 3000 fb-1. Several groups are investigating sensor designs and configurations able to withstand such high doses and fluences. This work is divided into two parts related to important aspects of the upgrades of the CMS pixel detector. For the phase I upgrade, a setup has been developed to provide an absolute energy calibration of the pixel modules that will constitute the detector. The calibration is obtained using monochromatic X-rays. The same setup is used to test the buffering capabilities of the modules' readout chip. The maximum rate experienced by the modules produced in Hamburg will be 120 MHz/cm 2 . For this rate the modules' efficiency has been measured to be 99%. In view of the module production, the energy calibration procedure has been automated. The modules assigned to the Hamburg production center should be completed by the end of February 2016. For the phase II upgrade, thin silicon sensors with an active thickness of 100 m irradiated with protons up to eq = 1 : 3 10 16 cm-2 have been characterized. The charge collection efficiency has been measured using pad diodes. Charge multiplication effects have been ob- served for both n- and p-bulk sensors. P-bulk strip sensors with an active thickness of 100 and 200 m have been characterized with a beam test. The signal of these sensors lies be- tween 4000 and 5000 e- after a fluence of 1 : 3 10 16 cm-2. The 200 m thick sensors require a higher bias voltage than the 100 m thick sensors to reach this signal height. The threshold necessary to obtain 95% detection efficiency is found to be around 2000 e- for the 100 m thick sensor
Characterization of thin irradiated epitaxial silicon sensors for the CMS phase II pixel upgrade
No full textThe high-luminosity upgrade of the Large Hadron Collider foreseen for 2023 resulted on the decision to replace the tracker system of the CMS experiment. The innermost layer of the new pixel detector will experience fluences in the order of phi(eq) ≈ 10(16) cm(−)(2) and a dose of ≈ 5 MGy after an integrated luminosity of 3000 fb(−)(1). Several materials and designs are under investigation in order to build a detector that can withstand such high fluences. Thin planar silicon sensors are good candidates to achieve this goal since the degradation of the signal produced by traversing particles is less severe than for thicker devices. A study has been carried out in order to characterize highly irradiated planar epitaxial silicon sensors with an active thickness of 100 μm. The investigation includes pad diodes and strip detectors irradiated up to a fluence of phi(eq) = 1.3 × 10(16) cm(−)(2), and 3 × 10(15) cm(−)(2), respectively. The electrical properties of diodes have been characterized using laboratory measurements, while measurements have been carried out at the DESY II test beam facility to characterize the charge collection of the strip detectors. A beam telescope has been used to determine precisely the impact position of beam particles on the sensor. This allows the unbiased extraction of the charge deposited in the strip sensor and good identification of the noise. In this paper, the results obtained for p-bulk sensors are shown. The charge collection efficiency of the strip sensors is 90% at 1000 V after a fluence of phi(eq) = 3 × 10(15) cm(−)(2). The irradiated diodes show charge multiplication effects. The impact of the threshold applied to a detector on its efficiency is also discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
12th workshop on picosecond timing detectors, electronics and applications (PicoSecond Workshop)
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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