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Nuclear Science, IEEE Transactions on

Issue 1 • Date Feb. 1989

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Displaying Results 1 - 25 of 256
  • 1988 Nuclear Science Symposium [Front cover]

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    Freely Available from IEEE
  • Very light tracking detector for jet target experiment in high energy physics

    Page(s): 54 - 57
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    A description is given of a detector that constitutes the inner tracking part of the E760 experiment designed to study charmonium spectroscopy on the antiproton accumulator at FNAL. It is composed of a multiwire proportional chamber and a radial projection chamber on the same mechanical structure with cylindrical symmetry. Some special features are described which makes it possible to achieve field shaping and to minimize space-charge effects, multiple scattering, and photon conversion. The detector has been made as light as possible in order to minimize particle conversion in the sensitive zone ranging from 15 degrees to 50 degrees degrees in polar angle. A data display for a cosmic event is shown.<> View full abstract»

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  • Polarimeters for medium-energy neutrons

    Page(s): 231 - 240
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    Polarimeters for medium-energy neutrons are described which are based on the fact that scattering of polarized neutrons from unpolarized hydrogen nuclei exhibits a left-right (or an up-down) asymmetry. Configurations are described for neutron polarimeters that use the analyzing power of neutron-proton scattering from the hydrogen in an organic scintillator material. The scattering angle theta an the azimuthal (out-of-plane) angle phi for the neutron-proton scattering event are determined from the position of the interaction in each of the two detectors involved in a given event. Consideration is given to V-configuration polarimeters, and axial-configuration polarimeter for use with a solid-angle-limiting aperture of a neutron spin-rotation magnet between the target and the polarimeter, and polarimeters configured with parallel planes of scintillator material.<> View full abstract»

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  • Punch-through currents and floating strip potentials in silicon detectors

    Page(s): 267 - 271
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    Punch-through currents flowing between adjacent p/sup +/ strips on the surface of silicon microstrip drift detectors have been observed. Measurements of the floating strip potential have shown that a p/sup +/ strip acquires a voltage such that the punch-through current and the leakage current are equal and opposite. The factors influencing the threshold for the punch-through effect have been compared with a simple computer model, and the predicted variation with the interstrip gap is found to be in reasonable agreement with measured values for a variety of detectors.<> View full abstract»

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  • Performance of a day time star sensor for a stabilized balloon platform

    Page(s): 876 - 880
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    A modified version of a CCD (charge-coupled device) star tracker originally designed for use on the ROSAT X-ray astronomy satellite has been built for use on a three-axis-stabilized balloon platform. The first flight of this star sensor was planned for May 1988 from the NASA balloon base at Palestine, Texas. Descriptions are given of the star sensor head, flight electronics, and steering system. The expected performance of this instrument is described along with the preflight results, which confirm its performance.<> View full abstract»

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  • A novel method for assessing position-sensitive detector performance

    Page(s): 1127 - 1131
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    A marked-point process model of a position-sensitive detector is developed which includes the effects of detector efficiency, spatial response, energy response, and source statistics. The average mutual information between the incident distribution of gamma -rays and the detector response is derived and used as a performance index of detector optimization. A brief example is presented which uses this figure-of-merit for optimization of light-guide dimensions for the SPRINT IT modular scintillation camera.<> View full abstract»

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  • Gettering in high resistive float zone silicon wafers for silicon detector applications

    Page(s): 290 - 294
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    An intrinsic gettering technique for float-zone highly resistive silicon using TCA+O2 has been described. The capacitance-voltage technique was used to determine the flat-band voltage and stretch-out of MOS (metal oxide semiconductor) structures made on various oxides. It has found that this intrinsic getting process improves minority-carrier-generation lifetime and SiO2/Si interface properties, leading to the reduction of leakage current in the p-i-n detector configuration. Direct comparisons of intrinsic gettering and extrinsic gettering using As ion-implantation have been made. Intrinsic gettering has been found to be the dominant process View full abstract»

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  • Calibration and performance of the Energetic X-ray Imaging Telescope Experiment

    Page(s): 871 - 875
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    The final integration and testing of the Energetic X-ray Imaging Telescope Experiment (EXITE) are described. The detector and telescope as finally assembled are described, and problems as well as solutions are detailed. The preflight calibration of the position-sensitive NaI detector revealed unanticipated effects in the energy spectra. In particular, an effect due to surface roughness (lack of firm optical polishing) on the crystal was found and calibrated. The radial variation of gain and resolution in the detector was also measured, and so-called flat fielding methods have been derived to analyze the data. The integration of the EXITE detector and gondola systems is described. Several novel features were developed for the EXITE gondola, most notably a shock absorber system. The performance of the detector and gondola systems was evaluated on the first balloon flight from Australia (May 1988) and a second flight from Ft. Sumner, NM (October 1988) View full abstract»

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  • Scintillator slurries of barium fluoride sand and index matched liquids

    Page(s): 256 - 259
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    The authors investigated some of the scintillation properties of small quantities of crushed and ground crystalline barium fluoride powders or sands, wetted with a variety of fluid solutions closely matched in refractive index to the barium fluoride, forming a clear scintillator slurry with a density of about 3.8 g/cm3 and a radiation length estimated to be about 2.8 cm. Some successful mixtures used novel liquid scintillators as the fluid base, providing a totally active scintillator detector matrix with a light output on a small sample about 30% of that produced by NaI. It is concluded that these heavy fluid or gel-like materials have the potential of creating relatively dense, short-radiation-length, fast, radiation-hard scintillators for large-scale calorimetric radiation detectors, with much lower cost than single-crystal detectors View full abstract»

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  • High resolution two dimensional readout of microchannel plates with large area delay lines

    Page(s): 227 - 230
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    A large-area (140 mm×140 mm) delay line anode has been used to read out microchannel plates (MCPs) at high resolution. Two-dimensional images in which the individual MCP microchannels were resolved were made at an MCP charge of 2.4×107 e. A FWHM resolution of ~18 μm has been demonstrated View full abstract»

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  • The DELPHI high-density projection chamber

    Page(s): 352 - 356
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    The mechanical design (converter, readout chamber, and trigger counters) and electronics (analog components and digitizers) of the High-Density Projection Chamber are described. Results from tests of production modules both in a test beam. showing observed change as a function of incident energy and observed versus expected track location, are presented. Tests using cosmic rays, showing measured drift-velocity and attenuation length for each pad row, are also presented View full abstract»

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  • 25 ps resolution, 12-bit, 64 channel FASTBUS time-to-digital converter

    Page(s): 426 - 430
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    The design and performance of a 64-channel time-to-digital converter are presented. The full-scale time range of 100 ns is digitized to 12 bits, providing 25-ps resolution. Surface-mount components and digital correction techniques have been used to achieve both the high density and high performance of the device, which is housed in a single-width FASTBUS module. Efficient readout capabilities, including sparse data scans and block transfers of zero-suppressed channel data, are provided. The device also features common start operation linearity over the 100-ns full-scale time range on the order of ±50 ps, fast clear time (200 ns) and conversion time (300 μm); and onboard pedestal subtraction and hit register View full abstract»

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  • A silicon drift photodiode

    Page(s): 295 - 299
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    A low-capacitance photodiode based on the principle of the solid-state drift chamber has been constructed and tested. The device is based on a cellular design with an anode at the center of each of five cells, allowing electrons liberated by ionization to drift up to 1 mm to the readout strip. Two designs were produced with p+ implant widths of 75 μm and 85 μm, respectively, using n-type material of 3.5-kΩ-cm resistivity. The opposite surface is a uniform p-type implant, features matching those of the other surface, and is unmetallized to ensure good photosensitivity. Results on the performance of the detector, including leakage current, capacitance, and drift properties, are presented and compared with simulation results View full abstract»

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  • High speed, low read noise electronics for astronomy detector arrays

    Page(s): 950 - 954
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    A description is given of the third-generation electronics system of the Berkeley infrared camera, which offers improved frame rate, size, manufacturability, and real-time data processing power. The flexibility to operate a variety of detectors and the vast improvement in speed was achieved by using DSP56001 digital signal processors (DSPs) to serve as controllers and processing elements throughout the system. The data acquisition system has one DSP per analog channel, making the system scalable to match the sensor being used. Each channel can run at up to 1-MHz sampling rate (analog/digital limited), using 20% of the DSPs 10-30-MIPS (million instructions per second) bandwidth for interrupt-driven data acquisition and leaving 80% for background processes. The analog board is dynamically configurable and is capable of performing self-diagnostics and -calibration. The computer system hardware and software are layered, supporting real-time interrupt response down to the microsecond level. The system is the prototype for the electronics for the 1-5 μm and 8.24-μm cameras being designed for the Keck Telescope View full abstract»

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  • Diagnostic software and hardware for critical real-time systems

    Page(s): 1291 - 1298
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    The authors describe a diagnostic software library which contains algorithms to test read-only memory, read/write memory, address lines, the main processor instruction set, the numeric data processor instruction set, and mutual exclusion hardware. The software library also contains algorithms to respond to unexpected software interrupts. A dedicated subsystem diagnostics board called the Multibus Diagnostic Monitor (MDM) is also described View full abstract»

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  • A highly selective monitor for air-borne iodine-125

    Page(s): 1276 - 1279
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    A description is given of an instrument which achieves high specificity for 125I with a standard sodium iodide scintillation detector, by using matched foils on indium and cadmium. An iodine-absorbing air filter is counted alternately through indium and cadmium. Only for 125I is there a significant difference in counting rate, due to the difference in k-edge energy for the two metals. The differential rate is averaged by a digital filter, and the 125I activity present is calculated and displayed. The air concentration of 125I is also estimated from the rate of change of the counting rate View full abstract»

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  • Multi-element imaging CT using a tube source of X-rays

    Page(s): 1138 - 1143
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    An experimental and theoretical study has been made of the imaging of several atomic elements in a single CT (computed tomography) scan using a tube source of X-rays. This work is part of a preliminary study of techniques to correct for matrix effects. Without such corrections, accurate quantitative measurements of element concentrations cannot be made. While not as sensitive as elemental imaging using synchrotron radiation, the technique described is capable of imaging medium-mass atomic elements at concentrations down to 0.1 kg/m3 in a water-like matrix several centimeters across using less than 108 photons. Several elements can be imaged in a single scan View full abstract»

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  • Compensating hadron calorimeters with Cerenkov light

    Page(s): 334 - 338
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    Because only a small fraction (~10%) of the energy deposition in the purely hadronic portion of a hadron shower is by minimum ionizing particles, the authors investigated the possibility of compensating calorimetry in homogeneous transparent materials by measuring separately the ionization energy (by scintillation or drifted ions) and the Cerenkov light. This can be used to separate the electromagnetic fluctuations in the shower, thereby correcting calorimeter response. They discuss potential media and methods to accomplish this, together with calculated responses. The possibility of compensation with a constant term less than 0.5% has been demonstrated in a highly idealized liquid argon device. Resolution for hadrons in the ideal case is shown to be comparable to that of heterogeneous calorimeters and offers the option of using the Cerenkov compensation at high energies and using ionization alone at low energies. In principle, such calorimeters could have superior electron resolution and substantial e/π separation, relative to most hadron calorimeters. Several configurations are suggested as ways to realize these devices, but a practical device awaits further detailed Monte Carlo studies and design View full abstract»

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  • A matched filter data smoothing algorithm

    Page(s): 1227 - 1231
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    An efficient spatial smoothing algorithm for filtering data while preserving spatial detail is obtained using the system (impulse response) function of the sensor. In contrast to the normal procedure for determining the filter coefficients for an arbitrary system function, this technique does not involve the use of Fourier transforms. The algorithm results in optimal smoothing within the constraints of retaining good vertical detail after only three or four iterations. A refinement of this procedure involving higher-order filter functions produced the equivalent operation in a single pass. The spatial filtering coefficients are obtained analytically for the frequently applicable Gaussian system function. The efficiency of this procedure is illustrated by filtering simulation, logs, and spectral data. For real-time smoothing of nuclear log data, a filter length of five times the vertical resolution is required View full abstract»

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  • Fast data acquisition with the CDF event builder

    Page(s): 440 - 445
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    The CDF (Collider Detector at Fermilab) event builder is an intelligent FASTBUS device that performs parallel readout of a set of FASTBUS slaves on multiple-cable segments, formats the data, and writes the reformatted data to a FASTBUS slave module. The authors review the properties of this device and summarize its performance in the CDF data acquisition system. Preliminary performance of the prototype is being evaluated, and an event rate of ~30 Hz appears possible in the near future View full abstract»

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  • Design of a volume-imaging positron emission tomograph

    Page(s): 993 - 997
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    Progress is reported in several areas of design of a positron volume imaging tomograph. As a means of increasing the volume imaged and the detector packing fraction, a lens system of detector light coupling is considered. A prototype layered scintillator detector demonstrates improved spatial resolution due to a unique Compton rejection capability. The conceptual design of a novel mechanism for measuring scattered radiation during emission scans has been tested by Monte Carlo simulation. The problem of how to use effectively the resulting sampled scattered radiation projections is discussed View full abstract»

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  • Defense-in-depth concept for nuclear power plant normal plant control systems using probability analysis

    Page(s): 1284 - 1290
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    The author describes some of the problems facing a designer and the solutions adopted to satisfy a probability approach to normal controls system design. This approach is intended to improve the overall plant reliability and minimize the probability of reactor trip. Of prime importance is knowledge of the reliability data of nuclear plant components and components failure rates. This can be achieved by a systematic analysis of field experience gained in operational power plants. The main importance of the proposed method lies in its ability to identify areas of relative weakness of a normal control system, which when rectified would provide an optimum design, and to improve the availability of nuclear power plants View full abstract»

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  • A proportional-scintillation counter beta spectrometer

    Page(s): 1166 - 1171
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    Using a proportional counter for coincidence gating of events in a plastic scintillator provides selective registration of beta interactions in the scintillator. The technique has been used to construct a field instrument that can selectively collect beta spectra (coincidence gating) or gamma spectra (anticoincidence gating). The technique provides a means of studying the energy structure of the radiation fields to correct dosimeter response and to aid in radiological engineering studies. Dose rates can be calculated from the spectra and compared with results obtained with conventional instruments. The system has proved to be an effective tool for studying beta spectra in the field View full abstract»

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  • An astronomy camera for low background applications in the 1.0 to 2.5 μm spectral region

    Page(s): 941 - 945
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    A description is given of a low-background astronomy camera system based on a short wavelength (1.0-2.5 μm) 128×128 focal plane array. The camera is designed to accept either a HgCdTe array for the 1-2.5 μm spectral region or an InSb array for the 3-5 μm spectral region. A cryogenic folded optical system is utilized to control excess stray light along with a cold eight-position filter wheel for spectral filtering. The camera head and electronics will also accept a 256×256 focal plane. Engineering evaluation of the system and two engineering runs at the JPL Table Mountain Observatory have been completed. System design, engineering performance, and sample imagery are presented View full abstract»

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  • Front end electronics and trigger system for the KARMEN neutrino experiment

    Page(s): 718 - 722
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    KARMEN is a 56-t liquid scintillation calorimeter for neutrino experiments using beam-dump neutrinos from the spallation neutron source ISIS of the Rutherford Appleton Laboratory. The central detector is surrounded by two layers of antidetectors to define the fiducial volume for v reactions. The architecture of the electronics system of the KARMEN detector is described. The readout of the position-sensitive calorimeter is controlled by a trigger processor that analyzes the sum energy and multiplicity of the 512 central detector modules. Zero suppression during the ADC (analog/digital converter) scan facilitates a fast readout. A sophisticated, high degree of multiplexing leads to an economical system View full abstract»

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Aims & Scope

IEEE Transactions on Nuclear Science focuses on all aspects of the theory and applications of nuclear science and engineering, including instrumentation for the detection and measurement of ionizing radiation; particle accelerators and their controls; nuclear medicine and its application; effects of radiation on materials, components, and systems; reactor instrumentation and controls; and measurement of radiation in space.

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