Design and Prototype Performance of the ATLAS Pixel Detector

The ATLAS experiment at the LHC will have three barrel and two times five disk layers of silicon pixel detectors as the innermost elements of the Inner Tracking Detector. the detctor is built adopting the hybrid pixel technology in which 16 highly permormant FE chips are connected to a silicon sensor by means of the bump and flip-chip technique. Owing to the high bunch crossing rate of 40 MHz at the LHC and the high particle fluences a sophisticated design concept is employed. The projet is presently entering the pre-production phase. The various aspects of the detector, the expected performance and the so far obtained prototype results are presented

PIXEL 2010 - a Resume

The Pixel 2010 conference focused on semiconductor pixel detectors for particle tracking/vertexing as well as for imaging, in particular for synchrotron light sources and XFELs. The big LHC hybrid pixel detectors have impressively started showing their capabilities. X-ray imaging detectors, also using the hybrid pixel technology, have greatly advanced the experimental possibilities for diiffraction experiments. Monolithic or semi-monolithic devices like CMOS active pixels and DEPFET pixels have now reached a state such that complete vertex detectors for RHIC and superKEKB are being built with these technologies. Finally, new advances towards fully monolithic active pixel detectors, featuring full CMOS electronics merged with efficient signal charge collection, exploiting standard CMOS technologies, SOI and/or 3D integration, show the path for the future. This r\'esum\'e attempts to extract the main statements of the results and developments presented at this conference.Comment: 8 pages, 19 figures, conference summar

Prospects for the Measurement of the Structure of the Coupling of a Higgs Boson to Weak Gauge Bosons in Weak Boson Fusion with the ATLAS Detector

The prospects for the measurement of the tensor structure of the vertex between a standard model Higgs boson and two weak gauge bosons using the distribution of the azimuthal angles between the two tagging jets in the weak boson fusion channel are studied in a Monte Carlo analysis using the fast simulation of the ATLAS detector. The decay channels $H \rightarrow \tau^+\tau^- \rightarrow ll+4\nu$, $H \rightarrow \tau^+\tau^- \rightarrow lh + 3\nu$ at $m_{H} = 120\,$GeV and $H \rightarrow W^+W^- \rightarrow ll\nu\nu$ at $m_H = 160\,$GeV are used in the analysis. For a standard model Higgs boson it is found that purely anomalous couplings are expected to be excluded at a confidence level corresponding to 2\,$\sigma$ or more at $m_H = 120\,$GeV and more than 5\,$\sigma$ at $m_H = 160\,$GeV from $30\,$fb$^{-1}$ of data. With a value of 1 roughly reproducing the standard model cross section for a purely anomalous coupling, the standard deviation in a measurement of a contribution of a CP even anomalous coupling in addition to the standard model coupling is estimated to be 0.20 at $m_H = 120\,$GeV and 0.08 at $m_H = 160\,$GeV

Readout Concepts for DEPFET Pixel Arrays

Field effect transistors embedded into a depleted silicon bulk (DEPFETs) can be used as the first amplifying element for the detection of small signal charges deposited in the bulk by ionizing particles, X-ray photons or visible light. Very good noise performance at room temperature due to the low capacitance of the collecting electrode has been demonstrated. Regular two dimensional arrangements of DEPFETs can be read out by turning on individual rows and reading currents or voltages in the columns. Such arrangements allow the fast, low power readout of larger arrays with the possibility of random access to selected pixels. In this paper, different readout concepts are discussed as they are required for arrays with incomplete or complete clear and for readout at the source or the drain. Examples of VLSI chips for the steering of the gate and clear rows and for reading out the columns are presented.Comment: 8 pages, 9 figures, submitted to Nucl. Instr. and Methods as proceedings of the 9th European Symposium on Semiconductor Detectors, Elmau, June 23-27, 200

Status of a DEPFET pixel system for the ILC vertex detector

We have developed a prototype system for the ILC vertex detector based on DEPFET pixels. The system operates a 128x64 matrix (with ~35x25 square micron large pixels) and uses two dedicated microchips, the SWITCHER II chip for matrix steering and the CURO II chip for readout. The system development has been driven by the final ILC requirements which above all demand a detector thinned to 50 micron and a row wise read out with line rates of 20MHz and more. The targeted noise performance for the DEPFET technology is in the range of ENC=100 e-. The functionality of the system has been demonstrated using different radioactive sources in an energy range from 6 to 40keV. In recent test beam experiments using 6GeV electrons, a signal-to-noise ratio of S/N~120 has been achieved with present sensors being 450 micron thick. For improved DEPFET systems using 50 micron thin sensors in future, a signal-to-noise of 40 is expected.Comment: Invited poster at the International Symposium on the Development of Detectors for Particle, AstroParticle and Synchrotron Radiation Experiments, Stanford CA (SNIC06) 6 pages, 12 eps figure

First observation of electrons in the ATLAS detector

This poster shows approved plots from https://twiki.cern.ch/twiki/bin/view/Atlas/ElectronGammaApprovedCosmicPlots and will be presented at the Hadron Collider Physics Symposium 16th -20th November 2009 in Evian

Test beam Characterizations of 3D Silicon Pixel detectors

3D silicon detectors are characterized by cylindrical electrodes perpendicular to the surface and penetrating into the bulk material in contrast to standard Si detectors with planar electrodes on its top and bottom. This geometry renders them particularly interesting to be used in environments where standard silicon detectors have limitations, such as for example the radiation environment expected in an LHC upgrade. For the first time, several 3D sensors were assembled as hybrid pixel detectors using the ATLAS-pixel front-end chip and readout electronics. Devices with different electrode configurations have been characterized in a 100 GeV pion beam at the CERN SPS. Here we report results on unirradiated devices with three 3D electrodes per 50 x 400 um2 pixel area. Full charge collection is obtained already with comparatively low bias voltages around 10 V. Spatial resolution with binary readout is obtained as expected from the cell dimensions. Efficiencies of 95.9% +- 0.1 % for tracks parallel to the electrodes and of 99.9% +- 0.1 % at 15 degrees are measured. The homogeneity of the efficiency over the pixel area and charge sharing are characterized.Comment: 5 pages, 7 figure

Concept, realization and characterization of serially powered pixel modules

We prove and demonstrate here for the example of the large scale pixel detector of ATLAS that Serial Powering of pixel modules is a viable alternative and that has been devised and implemented for ATLAS pixel modules using dedicated on-chip voltage regulators and modified flex hybrids circuits. The equivalent of a pixel ladder consisting of six serially powered pixel modules with about 0.3Mpixels has been built and the performance with respect to noise and threshold stability and operation failures has been studied. We believe that Serial Powering in general will be necessary for future large scale tracking detectors