R. Frey

KPiX, an array of self triggered charge sensitive cells generating digital time and amplitude information.

The Silicon Detector proposed for the International Linear Collider (ILC) requires electronic read-out that can be tightly coupled to the silicon detectors envisioned for the tracker and the electromagnetic calorimeter. The KPiX is a 1024-channel read-out chip that bump-bonds to the detector and communicates through a few digital signals, power, and detector bias. The KPiX front-end is a low-noise dual-range charge-amplifier with a dynamic range of 17 bit, achieved by autonomous switching of the feedback capacitor. The device takes advantage of the ILC duty cycle of 1 ms trains at 5 Hz rate by lowering the supply current after the data acquisition cycle for an average power consumption of ≪20 μW/channel. During the 1 ms train, up to four events exceeding a programmable threshold can be stored, the amplitude as a voltage on a capacitor for subsequent digitization, the event time in digital format. The chip can be configured for other than ILC applications.

KPiX - A 1,024 channel readout ASIC for the ILC

KPiX is a 1,024 channel System on a Chip intended for bump bonding to large area Si sensors, enabling low multiple scattering Si strip tracking and high density Particle Flow calorimetry for SiD at the International Linear Collider (ILC). It may be used for hadronic calorimetry readout with RPCs or GEMs, and with a scintillator-based muon system using SiPMs. An electromagnetic calorimeter prototype will be beam-tested in early 2013.

Fine grained silicon-tungsten calorimetry for a linear collider detector

A fine grained silicon-tungsten calorimeter is ideal for use as the electromagnetic calorimeter in a linear collider detector optimized for particle-flow reconstruction. We are designing a calorimeter that is based on readout chips which are bump bonded to the silicon wafers that serve as the active medium in the calorimeter. By using integrated electronics we plan to demonstrate that fine granularity can be achieved at a reasonable price. Our design minimizes the gap between tungsten layers leading to a small Moliere radius, an important figure of merit for particle-flow detectors. Tests of the silicon detectors to be used in a test beam prototype as well as timing measurements based on similar silicon detectors are discussed.

First results from the SLD silicon calorimeters

The small-angle calorimeters of the SLAC Large Detector (SLD) were successfully operated during the recent SLAC Linear Collider (SLC) engineering run. The Luminosity Monitor and Small-Angle Tagger (LMSAT) covers the angular region region between 28 and 68 mrad from the beam axis, while the Medium-Angle Silicon Calorimeter (MASC) covers the 68-190-mrad region. Both are silicon-tungsten sampling calorimeters; the LMSAT employs 23 layers of 0.86 X/sub 0/ sampling, while the MASC has 10 layers of 1.74 X/sub 0/ sampling. The authors present results from the first run of the SLC with the SLD on beamline. The calorimeters and electronics performed reliably with no major problems during a 15-week period with no access. Bhabha events were easily identified, and the 36-68-mrad region of the LMSAT was found to be approximately=100% efficient and background-free, which made it possible to measure L to be 14.4+or-0.5 nb/sup -1/ for this run.<<ETX>>

Study of 18-cm long single-sided AC-coupled silicon microstrip detectors

The SSC GEM silicon Central Tracker design incorporated 18-cm long single-sided AC-coupled silicon microstrip ladders. Compared to the 12-cm long ladders considered in the preliminary stages of the tracker design, the 18-cm long ladders have the advantage of reduced cost, channel count and overall power consumption, and led to a simplified tracker assembly. However, such long ships also present the challenge of maintaining satisfactory performance. The increased capacitance and series resistance contribute to lower signal-to-noise ratios, longer time walk, higher power consumption per channel and increased probability of crosstalk to neighboring channels. In this paper, an accurate method to calculate the geometric capacitance of the AC-coupled microstrips is presented and the calculated results are compared with measurements, SPICE simulations are performed to predict the noise, the extent of interstrip capacitive coupling and the dispersion of the detector signal due to the finite series resistance of the metal strips and the long length of the detector. The influence of the preamplifier current and the shaping time on the signal and noise levels is also presented. The study concludes that the 18-cm long ladders can successfully satisfy the performance goals of the GEM silicon Central Tracker. >

Gold-stud bump bonding for HEP applications

Methods involved in gold-stud bump bonding of VLSI chips to solid state sensors are described. Applicability and limitations of the techniques are discussed in the context of pad size and pitch of the detection elements on the sensors. Recommendations are made for preferred surface preparation of bonding pads.

Beam test of prototype 18 cm silicon-strip detectors with high speed electronics

A prototype silicon microstrip detector for the GEM general purpose detector proposed for the Super Collider was assembled and tested in the laboratory with radioactive sources and an IR-laser, and at SLAC in a 25 GeV electron beam. The system was designed for performance in the GEM environment: 60 MHz bunch crossing at 10/sup 33/ luminosity with inner barrel occupancies of 0.16%. Signals from the strips were amplified by custom designed high-speed, low-power, low-noise, low-mass, integrated microelectronics The mechanical design of the GEM tracker motivated the selection of long (18 cm) strip lengths (achieved by wire-bonding three 6 cm long detectors). Evaluation of the test beam and laboratory results demonstrate the feasibility of this approach.

A prototype silicon preradiator for the SSC

The authors describe the design of and first results from the test of a prototype of a preradiator detector. Such a detector could be used to enhance the identification of photons and electrons at the Superconducting Super Collider (SSC). Specifically, it may be used by the GEM detector to distinguish between single photons from Higgs decay and background photon pairs from pi /sup 0/ decay. The prototype consists of a tungsten radiator followed by silicon strip detectors. Two silicon detectors, oriented in X and Y, consists of 48 strips, each of length 48 mm. The pitch is 1 mm. The readout is achieved by low-noise, low-power custom preamplifier chips mounted directly on the detectors via custom circuit boards. This preradiator was tested in a beam at Brookhaven in July 1992. A lead glass array placed behind the silicon was used to determine energy resolution effects. The results from the test on spatial distributions and energy resolution, including correction of the energy deposited in the preradiator, are presented, along with comparisons to EGS simulations. >

Development of Readout Interconnections for the Si-W Calorimeter of SiD

The SiD collaboration is developing a Si-W sampling electromagnetic calorimeter, with anticipated application for the International Linear Collider. Assembling the modules for such a detector will involve special bonding technologies for the interconnections, especially for attaching a silicon detector wafer to a flex cable readout bus. We review the interconnect technologies involved, including oxidation removal processes, pad surface preparation, solder ball selection and placement, and bond quality assurance. Our results show that solder ball bonding is a promising technique for the Si-W ECAL, and unresolved issues are being addressed.