B.K. Hall

Beam test results of the BTeV silicon pixel detector

Abstract The results of the BTeV silicon pixel detector beam test carried out at Fermilab in 1999–2000 are reported. The pixel detector spatial resolution has been studied as a function of track inclination, sensor bias, and readout threshold.

Pixel multichip module design for a high energy physics experiment

At Fermilab, a pixel detector multichip module is being developed for the BTeV experiment. The module is composed of three layers. The lowest layer is formed by the readout integrated circuits (ICs). The back of the ICs is in thermal contact with the supporting structure, while the top is flip-chip bump-bonded to the pixel sensor. A low mass flex-circuit interconnect is glued on the top of this assembly, and the readout IC pads are wire-bounded to the circuit. This paper presents recent results on the development of a multichip module prototype and summarizes its performance characteristics.

Performance of prototype BTeV silicon pixel detectors in a high-energy pion beam

Abstract The silicon pixel vertex detector is a key element of the BTeV spectrometer. Sensors bump bonded to prototype front-end devices were tested in a high-energy pion beam at Fermilab. The spatial resolution and occupancies as a function of the pion incident angle were measured for various sensor-readout combinations. The data are compared with predictions from our Monte Carlo simulation and very good agreement is found.

Development of a readout technique for the high data rate BTeV pixel detector at Fermilab

The pixel detector for the BTeV experiment at Fermilab provides digitized data from approximately 22 million silicon pixel channels. Portions of the detector are six millimeters from the beam providing a substantial hit rate and high radiation dose. The pixel detector data will be employed by the lowest level trigger system for track reconstruction every beam crossing. These requirements impose a considerable constraint on the readout scheme. This paper presents a readout technique that provides the bandwidth that is adequate for high hit rates, minimizes the number of radiation hard components, and satisfies all other design constraints.

Radiation tolerance of prototype BTeV pixel detector readout chips

High-energy and nuclear physics experiments need tracking devices with increasing spatial precision and readout speed in the face of ever-higher track densities and increased radiation environments. The new generation of hybrid pixel detectors (arrays of silicon diodes bump-bonded to arrays of front-end electronic cells) is the state-of-the-art technology able to meet these challenges. We report on irradiation studies performed on BTeV pixel readout chip prototypes exposed to a 200-MeV proton beam at the Indiana University Cyclotron Facility. A prototype pixel readout chip (preFPIX2) has been developed at Fermilab for collider experiments and implemented in standard 0.25-/spl mu/m CMOS technology following radiation-tolerant design rules. The chip contains a variety of functional blocks (analog front ends, registers, state machines, and digital-to-analog converters). The tests confirm the radiation tolerance to proton total dose up to 87 Mrad of all of these circuits. In addition, nondestructive radiation-induced single-event upsets have been observed in on-chip static registers, and the single-bit upset cross-section has been extensively measured.

Study of temperature dependence of bump bonding for the BTeV pixel detector

The pixel detector proposed for the BTeV experiment at the Fermilab Tevatron will use bump-bonding technology based on either Indium or Pb/Sn solder to connect the front-end readout chips to the silicon pixel sensors. We have studied the behavior of the bumps by visual inspection of the bumps bonding silicon sensor modules to dummy chips made out of glass. The studies were done before and after thermal cycles, exposure to intense irradiation, and with the assemblies glued to a graphite substrate. We have also carried out studies on effects of temperature changes on both types of bump bonds by observing the responses of single-chip pixel detectors to a /sup 90/Sr source. We report the results from these studies as well as the noise and threshold behavior of the pixel readout at various temperatures.

Pomone, a PCI based data acquisition system

Pomone is a flexible read-out system, designed in the context of the BTeV pixel test beam, based upon a PCI-compliant board and a custom-built mezzanine card to accommodate different detector front-end components. The system consists of a rich set of C++ classes to provide the backbone functionalities needed to readout a pixel detector in a continuous mode, and a collection of GUIs to allow users to interact with all the hardware components. The system has been designed with a high level of generality in order to accommodate different kind of detectors as well as different event-building strategies. A detailed description of the system, running under the Linux platform, is provided, along with a discussion of specific solutions adopted to meet the requirements of efficiency and modularity posed by the design.

Temperature dependence of pixel multichip module operating performance

At Fermilab, a research program to develop a pixel detector for the BTeV experiment has been ongoing for the last several years. The basic building block of the pixel detector is the pixel multichip module. Prototypes have been built and characterization tests have been performed to verify that the pixel module will meet the stringent requirements of the experiment. One of these requirements is that the operating temperature of the detector will be at -5/spl deg/C, which imposes severe constraints on the pixel multichip module packaging design. This paper presents the temperature dependence of prototypes of the pixel multichip module.

Development of a high density pixel multichip module at Fermilab

At Fermilab, both pixel detector multichip module and sensor hybridization are being developed for the BTeV experiment. The BTeV pixel detector is based on a design relying on a hybrid approach. With this approach, the readout chip and the sensor array are developed separately and the detector is constructed by flip-chip mating the two together. This method offers maximum flexibility in the development process, choice of fabrication technologies, and the choice of sensor material. This paper presents strategies to handle the required data rate and performance results of the first prototype and detector hybridization.

Beam test of BTeV pixel detectors

Abstract The silicon pixel vertex detector is one of the key elements of the BTeV spectrometer. Detector prototypes were tested in a beam at Fermilab. We report here on the measured spatial resolution as a function of the incident angles for different sensor-readout electronics combinations. We compare the results with predictions from our Monte Carlo simulation.