Showing papers by "Peter Fischer published in 2006"

The FEI3 readout chip for the ATLAS pixel detector

Abstract: The latest pixel readout chip FEI3 for the ATLAS detector has been implemented in a standard 0.25 μ m CMOS process using radiation tolerant layout rules. It contains 2880 readout channels with densely packed analogue and digital circuits, a novel analogue front end and a complex time stamp based readout architecture and meets all specifications. Radiation tolerance has been demonstrated up to 100 Mrad of total dose. This paper summarizes the overall chip architecture and describes the most important circuit elements in some detail.

Pixel Detectors: From Fundamentals to Applications

Abstract: The Sensor.- The Front-End Electronics.- Integration and System Aspects.- Pixel Detector Applications.- Trends and New Developments for Pixel Detectors.

Serial powering: Proof of principle demonstration of a scheme for the operation of a large pixel detector at the LHC

Abstract: Large detectors in high-energy physics experiments are mostly built from many identical individual building blocks, called modules, which possess individual parts of the services. The modules are usually also powered by parallel power lines such that they can be individually operated. The main disadvantage of such a parallel powering scheme is the vast amount of necessary power cables which constitutes also a large amount of material in the path of the particles to be detected. For the LHC experiments already now this is a major problem for the optimal performance of the detectors and it has become evident, that for an upgrade programme alternative powering schemes must be investigated. 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. A powering scheme using dedicated voltage regulators and modified flex hybrid circuits has been devised and implemented for ATLAS pixel modules. The modules have been intensively tested in the lab and in test beams and have been compared to those powered in parallel with respect to noise and threshold stability performance. Finally, the equivalent of a pixel ladder consisting of six serially powered pixel modules with about 0.3 Mpixels has been built and the performance with respect to operation failures has been studied.

Compact multiphoton/single photon laser scanning microscope for spectral imaging and fluorescence lifetime imaging

Abstract: An inverted fluorescence microscope was upgraded into a compact three-dimensional laser scanning microscope (LSM) of 65 x 62 x 48 cm dimensions by means of a fast kHz galvoscanner unit, a piezodriven z-stage, and a picosecond (ps) 50 MHz laser diode at 405 nm. In addition, compact turn-key near infrared femtosecond lasers have been employed to perform multiphoton fluorescence and second harmonic generation (SHG) microscopy. To expand the features of the compact LSM, a time-correlated single photon counting unit as well as a Sagnac interferometer have been added to realize fluorescence lifetime imaging (FLIM) and spectral imaging. Using this unique five-dimensional microscope, TauMap, single-photon excited (SPE), and two-photon excited (TPE) cellular fluorescence as well as intratissue autofluorescence of water plant leaves have been investigated with submicron spatial resolution, < 270 ps temporal resolution, and 10 nm spectral resolution.

Spectroscopic performance of the DePMOS detector/amplifier device with respect to different filtering techniques and operating conditions

Abstract: A DePMOS structure provides detection and amplification jointly, and it is free of interconnection stray capacitance. To fully exploit the intrinsic low noise of the device an electrical model has been developed. The most relevant parameters have been measured in order to choose an adequate readout electronics. DePMOS can operate in continuous mode, i.e., without applying any clear pulse during the signal processing, and can be read out by a time-continuous shaper amplifier. An unequalled noise of 2.2 electrons rms at room temperature has been measured. In this mode DePMOS can be used, for example, as the readout device for silicon drift detectors. Anyway , DePMOS was developed to be the basic element of an active pixel sensor suitable to cope with the requirements of the XEUS Wide Field Imager. In a matrix arrangement, each pixel must be read out by a time-variant filter. A multichannel integrated shaping amplifier, based on multicorrelated double sampling, has been designed. Spectroscopic resolution obtained filtering the pixel matrix with this readout chip is in agreement with measurements in continuous mode and matches the predictions of the model presented. It has also been experimentally proved that the clear procedure does not introduce additional noise contribution, even in the very low noise range achieved. This qualifies DePMOS as a "reset-noise-free" device

Multi-Channel Readout ASIC for ToF-PET

Abstract: An architecture for the simultaneous measurement of arrival time and amplitude of PET scintillation signals in a multi-channel chip has been developed. The design of a first prototype chip is described in this paper. An intrinsic time resolution of 105 ps (FWHM) channel-to-channel has been observed with test pulses. In a PET setup with two LYSO crystals equipped with photomultipliers, the coincidence time resolution is 330 ps (FWHM). An energy resolution of 13% could be obtained for 511 keV signals from a Na-22 source using the on-chip charge integrator.

Clear-performance of linear DEPFET devices

Abstract: The proposal of a vertex detector for the International Linear Collider (ILC) using DEPleted Field Effect Transistor (DEPFET) detectors [A DEPFET based vertex detector for the detector at TESLA LC-Note, LC-DET-2002-004, DESY, April 2002] states challenging requirements for the readout-electronics and the sensor itself. In contrast to hybrid pixel technologies, DEPFET sensors integrate a first amplification stage in the detector. As the signal readout is non-destructive, the DEPFET requires a reset (clear) mechanism. Optimization of the clear mechanism addressing radiation hardness and timing are presented. Furthermore, the minimal duration for a clear process resulting in a readout free of reset noise will be shown to satisfy the timing requirements of the DEPFET-ILC readout scheme.

Study of noise and spectroscopic performance of DEPMOSFET matrix prototypes for XEUS

Abstract: The current generation of DEPMOSFET-based Active Pixel Sensor (APS) matrix devices has been developed to cope with the challenging requirements of the XEUS Wide Field Imager. The devices turned out to be a promising new imager concept for a variety of X-ray imaging applications. The devices combine excellent energy resolution, high-speed readout and low power consumption with the attractive feature of random accessibility of pixels. Sensor prototypes, built for row-wise readout, with 64 × 64 pixels with a size of 75 × 75 μ m 2 each have been produced at the MPI semiconductor laboratory in Munich, and their performance has been studied in detail. A spectroscopic resolution of 128 eV has been measured, the readout noise is as low as 3.5 e - ENC. Here, measurements of the dependence of readout noise and spectroscopic resolution on the device temperature are presented.

First test beam results on DEPFET pixels for the ILC

Abstract: By incorporating a field effect transistor into a fully depleted sensor substrate the DEPFET sensor combines radiation detection and amplification in each pixel, resulting in very low noise and high spatial resolution. This makes DEPFET sensors a favorable technology for the vertex detector at the planned International Linear Collider (ILC). A prototype system with fast steering chips, a current-based readout chip and a 64 × 128 pixels DEPFET matrix has been built and was operated successfully in the DESY test beam. First results of the studies on two different DEPFET design options are presented in this paper.

Advancements in DEPMOSFET device developments for XEUS

Abstract: DEPMOSFET based Active Pixel Sensor (APS) matrices are a new detector concept for X-ray imaging spectroscopy missions. They can cope with the challenging requirements of the XEUS Wide Field Imager and combine excellent energy resolution, high speed readout and low power consumption with the attractive feature of random accessibility of pixels. From the evaluation of first prototypes, new concepts have been developed to overcome the minor drawbacks and problems encountered for the older devices. The new devices will have a pixel size of 75 μm × 75 μm. Besides 64 × 64 pixel arrays, prototypes with a sizes of 256 × 256 pixels and 128 × 512 pixels and an active area of about 3.6 cm 2 will be produced, a milestone on the way towards the fully grown XEUS WFI device. The production of these improved devices is currently on the way. At the same time, the development of the next generation of front-end electronics has been started, which will permit to operate the sensor devices with the readout speed required by XEUS. Here, a summary of the DEPFET capabilities, the concept of the sensors of the next generation and the new front-end electronics will be given. Additionally, prospects of new device developments using the DEPFET as a sensitive element are shown, e.g. so-called RNDR- pixels , which feature repetitive non-destructive readout to lower the readout noise below the 1 e - ENC limit.

A DEPFET pixel matrix system for the ILC vertex detector

Abstract: The DEPFET detector offers radiation detection and amplification jointly by embedding a field effect transistor into fully depleted silicon. Due to the excellent noise performance ( ENC = 2.2 e - for single pixel at room temperature and 6 μ s shaping time) and the high spatial resolution of the device ( 4.3 μ m at 22 keV using 50 × 50 μ m 2 pixels), the DEPFET concept is attractive for X-ray astronomy, for biomedical application and for tracking in particle physics. For the vertex detector of a future TeV-scale linear collider, like the proposed ILC (International Linear Collider), a highly granulated pixel system operated row-wise with line rates of 20 MHz at a noise level below 100 e - is needed. Addressing these requirements, improved DEPFET sensors with 22 × 36 μ m 2 pixel size have been fabricated. A prototype system has been developed that uses dedicated chips for steering and readout of a 64 × 128 DEPFET pixel matrix. Due to the current based readout mode provided by the readout chip, a thousand times faster matrix operation than achieved so far is possible. The performance of the single components of the system will be summarized and first results obtained with the entire system will be presented.

Performance of a DEPFET pixel system for particle detection

Abstract: Driven by the requirements of the ILC (International Linear Collider) vertex detector, a prototype system based on DEPFET pixels has been developed. The system utilizes a 64 × 128 pixel matrix with 28.5 × 36 μ m 2 pixels, operated by dedicated chips for fast steering and readout. This paper will report on results for X-ray detection in the energy range between 6 and 40 keV. In addition, the system has been operated in a test beam and first results using the 6 GeV electron beam at the DESY synchrotron will be presented. The observed noise performance of the system will be compared with calculations. It will be shown that a noise figure of below ENC = 100 e - is achievable with DEPFET pixels for the ILC application leading to a signal-to-noise ratio of S / N > 40 for sensors as thin as 50 μ m .

Method for generating and/or memorising a retrievable cryptographic key during the production of a topographical structure

Abstract: The invention relates to a method for generating and memorising a retrievable cryptographic key during the production of a topographical structure, in particular for microelectronic or micromechanical components. According to said method, several measuring circuits (11) are created in the topographical structure, each circuit generating a measured value based on a magnitude of at least one electric or physical characteristic in the topographical structure, said characteristic being subjected to random fluctuations during the production of the topographical structure that is equipped with the measuring circuits (11). The cryptographic key is formed or derived from the measured values produced by the measuring circuits (11). The latter (11) comprise three-dimensional electric conductor structures (9, 10), each of which is predefined with a random design and created in the topographical structure and which generate the measured values based on the magnitude of a parasitic electric characteristic of the conductor structures (9, 10).

Test setup for DEPMOSFET matrices for XEUS

Abstract: The DEPMOSFET (Depleted p-channel MOSFET) is an Active Pixel Sensor (APS) for the XEUS Wide Field Imager (WFI), which is developed and produced by the MPI semiconductor laboratory in Munich (HLL). The current prototype detector consists of a hybrid where a 64 x 64 pixel matrix with 75 μm x 75 μm pixel size each is mounted together with CMOS SWITCHER II ICs for row-selection and a CAMEX 64 ASIC for readout. First measurements for this device have shown the high energy resolution and quantum efficiency as well as the potential for fast readout. For fast timing studies on XEUS an instrument is needed which is able to deal with count rates up to 106 photons s-1 with 10 μs time resolution. At the Institut fuer Astronomie und Astrophysik, we have built a setup to investigate the timing performance of the current prototype detector and to study the capability of the DEPMOSFET detector to handle high count rates. In this paper we present the Data Acquisition System and the future plans for this setup.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Status of DEPFET

Abstract: In a DEPFET sensor a MOSFET is integrated on a sidewards depleted p-on-n silicon detector, therefore combining the advantages of a fully depleted silicon sensor with in-pixel amplification. Presently, the DEPFET is mainly developed for two different kinds of applications: imaging spectroscopy in X-ray astronomy and the vertex detector for the International Linear Collider (ILC). In X-ray astronomy, the DEPFET sensor is chosen as focal plane detector for the XEUS mission mainly for its low noise and power consumption. In addition, the scalable pixel size makes it suitable for missions like SIMBOL-X, BepiColombo and WIMS. Using the source follower readout mode, a noise of 1.6e − is obtained at room temperature for single pixel devices. Two types of ILC devices, with and without a high energy (HE) implant, were tested in a testbeam. The signal-to-noise ratios were 100 with and 126 without HE implant. The position resolutions for both devices were found to be better than 6 μm.

Concept, realization and characterization of serially powered pixel modules

Abstract: 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 0.3 Mpixels 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.

Concept, realization and characterization of serially powered pixel modules (Serial Powering)

Abstract: 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 hybrid circuits. The equivalent of a pixel ladder consisting of six serially powered pixel modules with about 0.3 Mpixels 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.

The DEPFET Active Pixel Sensor as Vertex Detector for the ILC

Abstract: For the International Linear Collider a vertex detector with unprecedented performance is needed. The DEPFET, which integrates a MOSFET into the high resistivity detector substrate offers such performance: large signal/noise, small pixel size, thin detectors, low power consumption, high readout speed and radiation tolerance. This paper presents the concept of the DEPFET and results of a complete prototype system with dedicated control and readout electronics. Measurements of the radiation hardness will be presented and the technology to achieve thin detectors (50 μm) will be discussed.