Browsing by Author "Backhaus, M."

The insertable B-Layer upgrade of the ATLAS pixel detector forsees the installation of a fourth pixel layer close to the beam pipe inside the current ATLAS pixel detector. A new readout chip (FE-I4) has been developed to match the increased requirements in terms of radiation hardness and hit occupancy. A new USE-based test system for ATLAS hybrid pixel detectors (USBpix) will serve as test bench for this new readout chip generation. The performance of USBpix is compared to the performance of the TPLL/TPCC system, used for testing the ATLAS pixel detector readout chips FE-I3 and modules. The main differences between the FE-I3 and the FE-I4 are summarized from the point of view of the test systems and the implementation of the main blocks for chip configuration, data storage and histogramming in the USBpix FPGA firmware for both chip generations is discussed. Results of the first measurements which were done using the FE-I4 emulator developed for debugging purposes are discussed. (C) 2010 Elsevier B.V. All rights reserved.

Various structures for n-in-p planar pixel sensors have been developed at KEK in order to cope with the huge particle fluence in the upcoming LHC upgrades. Performances of the sensors with different structures have been evaluated with testbeam. The n-in-p devices were connected by bump bonding to the ATLAS Pixel front-end chip (FE-14A) and characterized before and after the irradiation to 1 x 10(16) 1 MeV n(eq)/cm(2). Results of measurements with 120 GeV/c momentum pion beam at the CERN Super Proton Synchrotron (SPS) in September 2012 are presented. (C) 2014 Elsevier B.V. All rights reserved.

A new type of n-in-p planar pixel sensors have been developed at KEK/HPK in order to cope with the maximum particle fluence of 1-3 x 10(16) 1 MeV equivalent neutrons per square centimeter (n(eq)/cm(2)) in the upcoming LHC upgrades. Four n-in-p devices were connected by bump-bonding to the new ATLAS Pixel front-end chip (FE-14A) and characterized before and after the irradiation to 2 x 10(15) n(eq)/cm(2). These planar sensors are 150 mu m thick, using biasing structures made out of polysilicon or punch-through dot and isolation structures of common or individual p-stop. Results of measurements with radioactive Sr-90 source and with a 120 GeV/c momentum pion beam at the CERN Super Proton Synchrotron (SPS) are presented. The common p-stop isolation structure shows a better performance than the individual p-stop design, after the irradiation. The flat distribution of the collected charge in the depth direction after the irradiation implies that the effect of charge trapping is small, at the fluence, with the bias voltage well above the full depletion voltage. (C) 2012 Published by Elsevier B.V

The ATLAS Experiment is reworking and upgrading systems during the current LHC shut down. In particular, the Pixel detector has inserted an additional inner layer called the Insertable B-Layer (IBL). The Readout-Driver card (ROD), the Back-of-Crate card (BOC), and the S-Link together form the essential frontend data path of the IBL's off-detector DAQ system. The strategy for IBL ROD firmware development was three-fold: keeping as much of the Pixel ROD datapath firmware logic as possible, employing a complete new scheme of steering and calibration firmware, and designing the overall system to prepare for a future unified code version integrating IBL and Pixel layers. Essential features such as data formatting, frontend-specific error handling, and calibration are added to the ROD data path. An IBL DAQ test bench using a realistic front-end chip model was created to serve as an initial framework for full offline electronic system simulation. In this document, major firmware achievements concerning the IBL ROD data path implementation, test on the test bench and ROD prototypes, will be reported. Recent Pixel collaboration efforts focus on finalizing hardware and firmware tests for the IBL. The plan is to approach a complete IBL DAQ hardware-software installation by the end of 2014.

Objective: To identify classifiers in images obtained with sagittal laser optical tomography ( SLOT) that can be used to distinguish between joints affected and not affected by synovitis. Methods: 78 SLOT images of proximal interphalangeal joints II-IV from 13 patients with rheumatoid arthritis were compared with ultrasound ( US) images and clinical examination (CE). SLOT images showing the spatial distribution of scattering and absorption coefficients within the joint cavity were generated. The means and standard errors for seven different classifiers ( operator score and six quantitative measurements) were determined from SLOT images using CE and US as diagnostic references. For classifiers showing significant differences between affected and non-affected joints, sensitivities and specificities for various cut off parameters were obtained by receiver operating characteristic (ROC) analysis. Results: For five classifiers used to characterise SLOT images the mean between affected and unaffected joints was statistically significant using US as diagnostic reference, but statistically significant for only one classifier with CE as reference. In general, high absorption and scattering coefficients in and around the joint cavity are indicative of synovitis. ROC analysis showed that the minimal absorption classifier yields the largest area under the curve (0.777; sensitivity and specificity 0.705 each) with US as diagnostic reference. Conclusion: Classifiers in SLOT images have been identified that show statistically significant differences between joints with and without synovitis. It is possible to classify a joint as inflamed with SLOT, without the need for a reference measurement. Furthermore, SLOT based diagnosis of synovitis agrees better with US diagnosis than CE.

The high-voltage (NV-) CMOS pixel sensors offer several good properties: a fast charge collection by drift, the possibility to implement relatively complex CMOS in-pixel electronics and the compatibility with commercial processes. The sensor element is a deep n-well diode in a p-type substrate. The n-well contains CMOS pixel electronics. The main charge collection mechanism is drift in a shallow, high held region, which leads to a fast charge collection and a high radiation tolerance. We are currently evaluating the use of the high-voltage detectors implemented in 180 nm I-IV-CMOS technology for the highluminosity ATLAS upgrade. Our approach is replacing the existing pixel and strip sensors with the CMOS sensors while keeping the presently used readout ASICs. By intelligence we mean the ability of the sensor to recognize a particle hit and generate the address information. In this way we could benefit from the advantages of the NV sensor technology such as lower cost, lower mass, lower operating voltage, smaller pitch, smaller clusters at high incidence angles. Additionally we expect to achieve a radiation hardness necessary for ATLAS upgrade. In order to test the concept we have designed two I-IVCMOS prototypes that can be readout in two ways: using pixel and strip readout chips. In the case of the pixel readout, the connection between 1-1V-CIV1OS sensor and the readout AMC can be established capacitively. (C) 2014 Elsevier B.V. All rights reserved

In order to extend its discovery potential, the Large Hadron Collider (LHC) will have a major upgrade (Phase II Upgrade) scheduled for 2022. The LHC after the upgrade, called High-Luminosity LHC (HL-LHC), will operate at a nominal leveled instantaneous luminosity of 5 x 10(34) cm(-2) s(-1), more than twice the expected Phase I. The new Inner Tracker needs to cope with this extremely high luminosity. Therefore it requires higher granularity, reduced material budget and increased radiation hardness of all components. A new pixel detector based on High Voltage CMOS (HVCMOS) technology targeting the upgraded ATLAS pixel detector is under study. The main advantages of the HVCMOS technology are its potential for low material budget, use of possible cheaper interconnection technologies, reduced pixel size and lower cost with respect to traditional hybrid pixel detector. Several first prototypes were produced and characterized within ATLAS upgrade R&D effort, to explore the performance and radiation hardness of this technology. In this paper, an overview of the HVCMOS sensor concepts is given. Laboratory tests and irradiation tests of two technologies, HVCMOS AMS and HVCMOS GF, are also given.

Objective: To assess the interobserver reliability of the main periarticular and intra-articular ultrasonographic pathologies and to establish the principal disagreements on scanning technique and diagnostic criteria between a group of experts in musculoskeletal ultrasonography. Methods: The shoulder, wrist/hand, ankle/foot, or knee of 24 patients with rheumatic diseases were evaluated by 23 musculoskeletal ultrasound experts from different European countries randomly assigned to six groups. The participants did not reach consensus on scanning method or diagnostic criteria before the investigation. They were unaware of the patients' clinical and imaging data. The experts from each group undertook a blinded ultrasound examination of the four anatomical regions. The ultrasound investigation included the presence/absence of joint effusion/synovitis, bony cortex abnormalities, tenosynovitis, tendon lesions, bursitis, and power Doppler signal. Afterwards they compared the ultrasound findings and re-examined the patients together while discussing their results. Results: Overall agreements were 91% for joint effusion/synovitis and tendon lesions, 87% for cortical abnormalities, 84% for tenosynovitis, 83.5% for bursitis, and 83% for power Doppler signal; k values were good for the wrist/hand and knee (0.61 and 0.60) and fair for the shoulder and ankle/foot (0.50 and 0.54). The principal differences in scanning method and diagnostic criteria between experts were related to dynamic examination, definition of tendon lesions, and pathological v physiological fluid within joints, tendon sheaths, and bursae. Conclusions: Musculoskeletal ultrasound has a moderate to good interobserver reliability. Further consensus on standardisation of scanning technique and diagnostic criteria is necessary to improve musculoskeletal ultrasonography reproducibility.

Objective: To evaluate the interobserver reliability among 14 experts in musculoskeletal ultrasonography ( US) and to determine the overall agreement about the US results compared with magnetic resonance imaging (MRI), which served as the imaging "gold standard'. Methods: The clinically dominant joint regions ( shoulder, knee, ankle/toe, wrist/finger) of four patients with inflammatory rheumatic diseases were ultrasonographically examined by 14 experts. US results were compared with MRI. Overall agreements, sensitivities, specificities, and interobserver reliabilities were assessed. Results: Taking an agreement in US examination of 10 out of 14 experts into account, the overall kappa for all examined joints was 0.76. Calculations for each joint region showed high kappa values for the knee ( 1), moderate values for the shoulder ( 0.76) and hand/finger (0.59), and low agreement for ankle/toe joints (0.28). kappa Values for bone lesions, bursitis, and tendon tears were high (kappa = 1). Relatively good agreement for most US findings, compared with MRI, was found for the shoulder ( overall agreement 81%, sensitivity 76%, specificity 89%) and knee joint ( overall agreement 88%, sensitivity 91%, specificity 88%). Sensitivities were lower for wrist/finger ( overall agreement 73%, sensitivity 66%, specificity 88%) and ankle/toe joints ( overall agreement 82%, sensitivity 61%, specificity 92%). Conclusion: Interobserver reliabilities, sensitivities, and specificities in comparison with MRI were moderate to good. Further standardisation of US scanning techniques and definitions of different pathological US lesions are necessary to increase the interobserver agreement in musculoskeletal US.