A CMOS integrated circuit (IC) for pulse-shape discrimination (PSD) has been developed. The IC performs discrimination of gamma-rays and neutrons as part of a monitoring system for stored nuclear materials. The method extracts the pulse tail decay time constant using a leading edge trigger for identifying the start of the pulse and a zero-crossing discriminator to determine the zero crossing of the bipolar shaped signal. The circuit is designed to interface with two photomultiplier tubes-one for pulse processing and one for coincidence detection. Two outputs from the IC, a start and stop, can be used with a high speed timing system for pulse characterization with minimal external control. The circuit was fabricated in Orbit 1.2 μm CMOS and operates from a 5-V supply. Specifics of the design including overall topology, charge-sensitive preamplifier and discriminator characteristics, shaping method and time constant selections, system timing, and implementation are discussed. Circuit performance is presented including timing walk, system dead time, and power consumption

A miniaturized multichannel scaler instrument has been developed to address size and operational constraints for data acquisition in a portable laser-induced luminescence system. The multichannel scaling (MCS) function is implemented as a programmable application specific integrated circuit (ASIC) with standard interfaces for control and data-acquisition. The instrument is microcontroller-based with sufficient computing power for data manipulation and algorithmic processing. The unit includes electronics for laser control and amplification and pulse height discrimination of PMT pulses. Modification of the instrument should allow use in nuclear, chemical, and spectroscopy-related applications including Mossbauer experiments. Interfaces are incorporated allowing both computer-controlled and stand-alone operation. Implementation of the MCS function as an ASIC and comparison with conventional implementations are discussed. Full characterization of the MCS is presented including differential nonlinearity, bin dead time, and bandwidth measurements

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.< >

The chemical compatibility of wave length shifting fibers with several liquid scintillators has been investigated. Based on systematic characterization of the behavior of the BC-517 family, a time of life of 70–450 years was estimated for the polystyrene based wave length shifting fiber in BC-517P scintillator. Wavelength shifting (WLS) fibers irradiated continuously to a dose of 6.4 Mrads (at .377 Mrad/hr of 60Co) were observed to decrease from 100% to 5% transmission; however, after 100 hours of annealing, the transmission increased to 90%. GEANT3 simulations of a simplified calorimeter located behind a BaF2 electromagnetic calorimeter for the GEM detector at SSC showed that the constant term in the energy resolution will change from 1.8 to 2.9 in five years at 1034 luminosity for pseudorapidity η=3.

The authors present a four-channel, low-power-consumption bipolar monolithic preamplifier designed to amplify signals from pads with detector capacitance values from 20 pF to 50 pF used in an RHIC (Relativistic Heavy Ion Collider) dimuon experiment. The circuit utilizes a folded-cascode topology with a novel feedforward compensation that improves the low-capacitance transient response and provides self-biasing without resorting to bandgap or current references. The circuit was fabricated in the VHF dielectrically isolated complementary bipolar process. Data for gamma pre- and post-irradiation to 1.25 Mrad indicated that the dynamic characteristics of the circuit were unchanged and that the biasing and noise showed only a few percent change after exposure to radiation.< >