D. Freytag

Performance Report for Stanford/SLAC Microstore Analog Memory Unit

Tests of a newly developed Analog Memory Unit (AMU) are described. The device contains 256 analog storage cells consisting of pass transistors, a storage capacitor and a differential read out buffer. By addressing the storage cells sequentially, the shape of the signal present at the input can be recorded in time. Fast response and good amplitude resolution were the design goals for the development. Measurements on individual devices will be presented and the status of hybridized subsystems containing eight AMUs discussed.

Performance Report for Stanford/SLAC Multi-Channel Sample-and-Hold Device

Test results on a newly developed Multi-Channel Sample- And-Hold Calorimeter Data Unit (CDU) are presented. The device is organized as 32 input channels, each consisting of four storage cells to take samples of the 32 analog signals at four separate times. The design goals for the development were wide dynamic range and long hold times. Therefore, each storage cell is laid out in a fully differential way and consists of a sampling stage for the signal and another identical stage for a reference voltage. Results on the performance of the device are described.

Waveform Sampler CAMAC Module

A Waveform Sampler Module (WSM) for the measurement of signal shapes coming from the multi-hit drift chambers of the SLAC SLD detector is described. The module uses a high speed, high resolution analog storage device (AMU) developed in collaboration between SLAC and Stanford University. The AMU devices together with high speed TTL clocking circuitry are packaged in a hybrid which is also suitable for mounting on the detector. The module is in CAMAC format and provides eight signal channels, each recording signal amplitude versus time in 512 cells at a sampling rate of up to 360 MHz. Data are digitized by a 12-bit ADC with a 1 ¿s conversion time and stored in an on-board memory accessible through CAMAC.

Analog floating-point BiCMOS sampling chip and architecture of the BaBar CsI calorimeter front-end electronics system at the SLAC B-factory

The design and implementation of an analog floating-point sampling integrated circuit for the BaBar detector at the SLAC B-Factory is described. The CARE (Custom Auto-Range Encoding) circuit is part of an 18-bit dynamic range sampling system with a 4-MHz waveform digitization rate for the CsI calorimeter. The architecture and methodology of the system are described. The CARE integrated circuit receives dual-range (gain of 1 and 32) 13-bit signals from the 18-bit range preamplifiers mounted directly on the CsI crystals and converts the input at a rate of 4 MHz to an auto-range floating-point format with a 10-bit analog mantissa and 2 digital range bits (for 4 ranges). Additional functions integrated on the chip are averaging and selection circuitry for signals originating from two independent diodes per crystal and range-selection overwrite circuitry. The circuit will be mounted within the detector structure and thus low power dissipation is essential. The circuit has been fabricated in a 1.2-/spl mu/m BiCMOS process with polysilicon-to-polysilicon capacitors and polysilicon resistors. Measurement results are presented. One complete CARE channel dissipates 25 mW.

The Analog Processing System for the Liquid Argon Calorimeter for SLD at SLAC

The analog processing system for the Liquid Argon Calorimeter for the SLD project at SLAC is described. Amplification, storage of the analog information, and multiplexing is realized on specially developed hybrids, which will be mounted directly on the detector. This leads to a substantial reduction of the cable plant. Test results for the amplifier and for the sampling and multiplexing hybrid (CDU hybrid) are presented. The latter hybrid contains a custom monolithic device, the Calorimeter Data Unit (CDU).

Polarization Measurement of theΣ+Produced in the Line-Reversed Reactionsπ+p→K+Σ+andK−p→π−Σ+at 7 and 11.6 GeV/c

The polarization of the ..sigma../sup +/ has been measured for the line-reversed reactions ..pi../sup +/p ..-->.. K/sup +/..sigma../sup +/ and K/sup -/p ..-->.. ..pi../sup -/..sigma../sup +/ at 7 and 11.6 GeV/c using the SLAC Hybrid Facility. Since the ..sigma../sup +/ decay is observed in the bubble chamber, the trigger of the flash lamps on a fast K/sup +/(..pi../sup +/) did not bias the polarization measurements. We find that the ..sigma../sup +/ polarizations from the two reactions have opposite signs but similar magnitude and are in much better agreement with the predictions of weak exchange degeneracy than previous lower-energy comparisons.

The front-end analog and digital signal processing electronics for the drift chambers of the Stanford Large Detector

The front-end signal processing electronics for the drift chambers of the Stanford Large Detector (SLD) at the Stanford Linear Collider are described. The system is implemented with printed-circuit boards which are shaped for direct mounting on the detector. Typically, a motherboard comprises 64 channels of transimpedance amplification and analog waveform sampling, analog-to-digital conversion, and associated control and readout circuitry. The loaded motherboard thus forms a processor which records low-level waveforms from 64 detector channels and transforms the information into a 64 kB serial data stream. The package performs calibration functions, measures leakage currents on the wires, and generates wire hit patterns for triggering purposes. The construction and operation of the electronic circuits utilizing monolithic, hybridized, and programmable components are discussed. >

Design and fabrication of advanced hybrid circuits for high energy physics

Current design and fabrication techniques of hybrid devices as applied to the Stanford Linear Collider Large Detector (SLD) are discussed. Methods of developing layouts ranging from hand-cut templates to advanced designs utilizing CAD tools with special hybrid design software were applied. Physical and electrical design rules for good yield and performance are discussed. Fabrication and assembly of of a variety of SLD hybrids using different construction methods are described. >

Evidence for a narrow NN state at 2.02 GeV/c2 in 6 and 9 GeV/c antiproton interactions

Abstract We report evidence for the existence of a charged narrow state of mass M ∼ 2.02 GeV/ c 2 and widtt Γ ⪅ 0.04 GeV/ c 2 , decaying into N N . The state is observed in the reaction p p → p fast n π + π − π − at 6 GeV/ c and in p p →π fast + p n π + π − at 9 GeV/ c in a triggered bubble chamber experiment at the SLAC Hybrid Facility.

Production and decay angular distributions of the Y∗ (1385) in the line-reversed reactions: π+p → K+Y∗ (1385) and K−p → π−Y∗ (1385) at 11.5 GeV/c☆

Abstract We have measured in a single experimental setup, the differential cross sections and decay angular distributions of the Y∗ (1385) produced in the two line-reversed reactions: π + p → K + Y ∗+ (1385) (279 events/ω b ) and K − p → π − Y ∗+ (1385) (190 events/ωb) at 11.5 GeV/c. The data have been derived from a triggered bubble-chamber experiment using the SLAC Hybrid Facility. We find the differential cross sections and Y∗ polarizations for the two reactions to be in agreement with exchange-degeneracy predictions, if kinematic differences are taken into account. The Stodolsky-Sakurai and additive quark model predictions are in agreement with the main features of the decay angular distributions of the Y∗ (1385), except for small violations at low momentum transfer, which can be associated with a finite helicity non-flip contribution in the forward direction.