N. Bingefors

A novel technique for fast pulse-shaping using a slow amplifier at LHC

Abstract We describe a new technique for front end signal processing for LHC type applications, where a shaping amplifier with a time constant of several beam crossing intervals is used. The method is based on discrete time filtering of data extracted from an analog pipeline after a first level trigger. A finite impulse response type filter deconvolutes the sampled voltages of the shaped pulse to retrieve the original impulse signal with high precision. Measurements showing the performance of the technique and its implication for signal to noise are presented. The method is well matched to CMOS front ends, where low power consumption and low noise is achieved for silicon strip readout by utilizing pulse shapes with time constants ∼ 50 ns. A CMOS circuit emulating the filter has been built. It has been implemented with very low power consumption (

First results from a silicon-strip detector with VLSI readout

Abstract A 256-strip silicon detector with 25 μm strip pitch, connected to two 128-channel NMOS VLSI chips (Microplex), has been tested using straight-through tracks from a ruthenium beta source. The readout channels have a pitch of 47.5 μm. A single multiplexed output provides voltages proportional to the integrated charge from each strip. The most probable signal height from the beta traversals is approximately 14 times the rms noise in any single channel.

Progress in the construction of the delphi microvertex detector

Abstract The design and progress in the construction of the DELPHI microvertex detector are presented. The layout is described, together with results on precision mounting of silicon detectors. The development of ac-coupled silicon microstrip detectors was an important contribution to the design. The use of low-power CMOS readout chips facilitates the cooling of the detector. A description of the fourth-generation readout processor for silicon strip detectors, the SIROCCO IV, implemented in FASTBUS, is given. Finally, two complementary systems for in-situ position monitoring of the detectors are described.

The delphi silicon strip microvertex detector

Abstract The silicon strip microvertex detector for the DELPHI experiment at LEP is presented. It consists of two cylindrical layers with a total of 165 888 strips. The design parameters of the final project are described. The microstrip counters have a pitch of 16.6 μm, and are read out every 50 μm using the capacitive charge division method. The electronics used is the Microplex chip, an NMOS integrated circuit, which provides 128 channels of low noise charge sensitive amplifiers with multiplexed analog output. Results of signal-to-noise ratio from beam tests on prototype detectors are given and discussed.

The detector control system of the ATLAS SemiConductor Tracker during macro-assembly and integration

The ATLAS SemiConductor Tracker (SCT) is one of the largest existing semiconductor detectors. It is situated between the Pixel detector and the Transition Radiation Tracker at one of the four interaction points of the Large Hadron Collider (LHC). During 2006-2007 the detector was lowered into the ATLAS cavern and installed in its final position. For the assembly, integration and commissioning phase, a complete Detector Control System (DCS) was developed to ensure the safe operation of the tracker. This included control of the individual powering of the silicon modules, a bi-phase cooling system and various types of sensors monitoring the SCT environment and the surrounding test enclosure. The DCS software architecture, performance and operational experience will be presented in the view of a validation of the DCS for the final SCT installation and operation phase.

Performance of a pixel readout chip with two counters for X-ray imaging

A pixel readout chip for X-ray imaging has been developed and tested. It will he used in a hybrid pixel detector, where it is flip-chip bonded to a sensor. The sensor material can be silicon or a compound semiconductor, such as CdZnTe. A novel feature of the chip is the implementation of two counters inside each pixel cell. The chip consists of 992 pixels arranged in 31 columns and 32 rows. Each pixel size is 270 micrometer square and it consists of a preamplifier, shaper, discriminator and two counters. The circuit design with two integrated counters in each pixel cell makes it possible to acquire two images very close in time with practically no dead time in between. An externally adjustable threshold permits the discrimination of a portion of the X-ray spectrum. The detector is primarily aimed for dynamic medical X-ray imaging up to 100 frames per second. A characterization of the performance of the chip is presented and discussed.

Position-sensitive focal plane detectors for electron (ESCA) spectrometers

Abstract Different techniques for multidetectors in electron spectrometers are presented. The techniques are the parallel plate channel multipliers, micro channel plates followed by a phosphor plate viewed by a video camera, micro channel plates followed by a resistive strip detector, electron accelerating grid followed by a diode array detector, micro channel plates followed by a multiple anode detector and a new concept with a position sensitive electron detector with integrated electronic circuitry on a chip.

Wireless data transfer with mm-waves for future tracking detectors

Wireless data transfer has revolutionized the consumer market for the last decade generating many products equipped with transmitters and receivers for wireless data transfer. Wireless technology opens attractive possibilities for data transfer in future tracking detectors. The reduction of wires and connectors for data links is certainly beneficial both for the material budget and the reliability of the system. An advantage of wireless data transfer is the freedom of routing signals which today is particularly complicated when bringing the data the first 50 cm out of the tracker. With wireless links intelligence can be built into a tracker by introducing communication between tracking layers within a region of interest which would allow the construction of track primitives in real time. The wireless technology used in consumer products is however not suitable for tracker readouts. The low data transfer capacity of current 5 GHz transceivers and the relatively large feature sizes of the components is a disadvantage.Due to the requirement of high data rates in tracking detectors high bandwidth is required. The frequency band around 60 GHz turns out to be a very promising candidate for data transfer in a detector system. The high baseband frequency allows for data transfer in the order of several Gbit/s. Due to the small wavelength in the mm range only small structures are needed for the transmitting and receiving electronics. The 60 GHz frequency band is a strong candidate for future WLAN applications hence components are already starting to be available on the market.Patch antennas produced on flexible Printed Circuit Board substrate that can be used for wireless communication in future trackers are presented in this article. The antennas can be connected to transceivers for data transmission/reception or be connected by wave-guides to structures capable of bringing the 60 GHz signal behind boundaries. Results on simulation and fabrication of these antennas are presented as well as studies on the sensitivity of production tolerances.

Evaluation of a humidity sensor for use in an environment exposed to radiation

Humidity sensors tolerant to ionizing radiation are used in high-energy physics experiments where radiation doses are large and the sensors are inaccessible for replacement due to the highly activated environment. Other fields that have to meet the same demands are nuclear industry and space technology. In this paper cellulose crystallite humidity sensors that have been qualified by the manufacturer for use in radiation environments have been characterized and calibrated with the purpose of evaluating their suitability for use in the CERN ATLAS experiment for high-energy physics research. The impact of protons on the sensor was studied up to a fluence of 2∙1014 p/cm2.

Latest results from silicon microstrip detectors with VLSI readout for the delphi microvertex detector

Abstract A silicon microstrip counter with 25 μm strip pitch and two 128-channel low noise VLSI readout chips (“MICROPLEX”) has been tested in a 3.5 GeV negative pion beam at CERN. Results are given on the signal-to-noise ratio and on the cluster size spreading due to capacitive crosstalk.