By Topic

Nuclear Science, IEEE Transactions on

Issue 4  Part 3 • Date Aug. 2007

 This issue contains several parts.Go to:  Part 1  | Part 2 

Filter Results

Displaying Results 1 - 25 of 42
  • Table of contents

    Publication Year: 2007 , Page(s): C1 - 1194
    Save to Project icon | Request Permissions | PDF file iconPDF (81 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Nuclear Science publication information

    Publication Year: 2007 , Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (36 KB)  
    Freely Available from IEEE
  • A Low Power and Low Signal 5-bit 25 MS/s Pipelined ADC for Monolithic Active Pixel Sensors

    Publication Year: 2007 , Page(s): 1195 - 1200
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1644 KB) |  | HTML iconHTML  

    For CMOS monolithic active pixels sensor readout, we developed a 5 bit low power analog to digital converter using a pipelined architecture. A non-resetting sample and hold stage is included to amplify the signal by a factor of 4. Due to the very low level of the incoming signal, this first stage compensates both the amplifier offset effect and the input common mode voltage dispersion. The converter consists of three 1.5 bit sub-ADC and a 2 bit flash. We present the results of a prototype, made of eight ADC channels. The maximum sampling rate is 25 MS/s. The total DC power consumption is 1.7 mW/channel on a 3.3 V supply voltage recommended for the process. But at a reduced 2.5 V supply, it consumes only 1.3 mW. The size of each ADC channel layout is only . This corresponds to the pitch of two pixel columns each one would be 20 wide. The full analog part of the converter can be quickly switched to a standby idle mode in less than 1 mum; thus reducing the power dissipation to a ratio better than 1/1000. This fast shutdown is very important for the ILC vertex detector as the total DC power dissipation becomes directly proportional to the low beam duty cycle. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Front-End Electronics Card Comprising a High Gain/High Bandwidth Amplifier and a Fast Discriminator for Time-of-Flight Measurements

    Publication Year: 2007 , Page(s): 1201 - 1206
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (330 KB) |  | HTML iconHTML  

    During the development of the Multi-Strip Multi-Gap Resistive Plate Chambers (MMRPCs) for the time-of-flight (ToF) upgrade of the FOPI detector system, we have designed different versions of the front-end electronics (FEE). The signals from a MMRPC are read out on each side of the anode strips by an amplifier followed by a leading-edge discriminator. They are digitized in a time-to-amplitude converter (TAC) followed by a charge-to-digital converter (QDC). These counters are designed to provide a ToF resolution below sigmat les 60 ps requiring an amplifier-diecriminator stage with an intrinsic electronic resolution below sigmat(FEE) les 20 ps. We describe the design steps of the FEE-card from a 4-channel version (FEE1) for the R&D phase to the final 16-channel card (FEE5) for the readout of 4800 channels of the total detector array. Through these design steps we have kept the following key characteristics: low noise sigman les 25 muV RMS (to the amplifier input), high gain (200) and a high bandwidth (1 GHz). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measurements of Matching and High Count Rate Performance of Multichannel ASIC for Digital X-Ray Imaging Systems

    Publication Year: 2007 , Page(s): 1207 - 1215
    Cited by:  Papers (9)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (903 KB) |  | HTML iconHTML  

    We present the measurements of matching and high count rate performance of a 64 channel readout ASIC called DEDIX for high count rate position-sensitive measurements using semiconductor detectors. The ASIC is designed in 0.35 mum CMOS process and its total area is 3900 times 5000 mum2. The DEDIX has a binary readout architecture. Each channel is built of a charge sensitive amplifier (CSA) with a pole-zero cancellation circuit, a shaper, two independent discriminators and two independent 20-bit counters. The size of the input device in CSA has been optimized for a detector capacitance in the range of 1-3 pF per strip. An equivalent noise charge of 110 el rms has been achieved for a total detector capacitance of 1 pF at the shaper peaking time of 160 ns. Internal correction DAC implemented in each channel independently ensures a low spread of discriminator effective threshold, namely 0.4 mV at one sigma level. The mean gain in the multichannel ASIC is 54 muV/el, with a good uniformity from channel-to-channel (sd/mean ap 0.8%). Low noise performance and high rate capability have been demonstrated by the measurement up to and above 1 MHz average rate of input signals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Complete Read-Out Channel With Embedded Wilkinson A/D Converter for X-Ray Spectrometry

    Publication Year: 2007 , Page(s): 1216 - 1221
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (741 KB) |  | HTML iconHTML  

    This paper presents a complete read-out channel suitable for large arrays of X-ray detectors to be used for spectrometry applications in space. The system is fully integrated except for the X-ray detector. It basically consists of a front-end circuit for processing the detector signal, a Wilkinson A/D converter for the analog-to-digital conversion and the digital logic required to ensure the correct handshaking between all the blocks of the read-out channel. The system allows us to process the signal provided by the detector down to the final analog-to-digital conversion. All these functionalities are embedded in a single chip that, in its final version, will be bump-bonded to the matrix of X-ray detectors. The chip, designed in a 0.35 mum CMOS technology, achieves an input-referred noise of 34 erms - , consuming 0.9 mW from a 3.3 V power supply. The on-board A/D converter features 10 bits of resolution with a maximum conversion time of 210 mus. The INL and DNL of the whole read-out channel are equal to plusmn3.3 LSB and plusmn0.2 LSB, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pion Decay-Mode Tagging in a Plastic Scintillator Using COPPER 500-MHz FADC

    Publication Year: 2007 , Page(s): 1222 - 1226
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (515 KB) |  | HTML iconHTML  

    The PIENU experiment is going to be carried out at TRIUMF to measure the ratio of pion decay rates, R = Gamma(pi+ rarr e+ nue)/Gamma(pi+ rarr mu+ numu), to an accuracy of 0.1%. In order to achieve this goal, a muon identification with waveform analysis in a target scintillator is necessary. Due to the short lifetime of pions, muon pulses tend to overlap onto the tail of pion pulses. Thus waveform analysis with a high frequency flash-ADC is essential for the identification and separation of muon pulses. We use the 500-MHz flash-ADC of the common pipelined platform for electronics readout system, which was developed at KEK, to readout waveforms from the target scintillator. Muon pulse identification capability of this flash-ADC system was investigated by artificial pulses simulating photomultiplier signals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Easy Procedure for Calibrating Data Acquisition Systems Using Interleaving

    Publication Year: 2007 , Page(s): 1227 - 1231
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1169 KB) |  | HTML iconHTML  

    Interleaving data acquisition channels is a well-known and interesting technique to achieve higher acquisition rates. However, to obtain the expected benefits, a careful look at the interleaving technique and to mismatches that can lead to unwanted harmonic distortion and noise is essential. In this paper we discuss the methods used to interleave existing high-speed, 250 MSPS 8-bit acquisition channels, and the results obtained. The methods presented allowed a good relative channel calibration in amplitude (amplitude mismatch under 0.1 lsb) and in time (time mismatch between acquisition channels in the ps range, under the specified maximum jitter for the ADC used). A dynamic, by software, amplitude level signal-dependent adjustment procedure is also suggested for signals with rich frequency content that can substantially improve the quality of the acquired signal when using interleaved channels. The techniques presented provide good results even in the presence of noise. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Examination of Count-Starved Gamma Spectra Using the Method of Spectral Comparison Ratios

    Publication Year: 2007 , Page(s): 1232 - 1238
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1074 KB) |  | HTML iconHTML  

    We discuss the determination of energy region (bin) boundaries and decision metrics for gamma-ray spectra, acquired using a mid-resolution detector, that are useful for detecting illicit sources at low total counts. The bins are designed to produce the lowest minimum detectable counts using a spectral comparison ratio technique at a given false-positive rate for a specified population of benign-source spectra. Spectra from the benign source population consist of observations taken by a detector on a moving vehicle, as would be obtained during a search for a missing or hidden source. Raw counts in bins are transformed into a vector of background-corrected count differences. Bin boundaries are determined to yield large values of a standardized length of this vector for benign-plus-benchmark sources by applying an optimization technique. The objective function includes penalties for overlap with the spectral features of naturally occurring radioactive materials. We compare estimated minimum detectable count values for such bins applied to depleted uranium and barium-133 sources with those based on gross counting, and we examine the effect of nuisance potassium-, radium- and thorium-dominated sources. Using this methodology, we demonstrate that energy bins may be chosen to be sensitive to special nuclear materials, improving the likelihood of detection in low-count or masked-source searches. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Detector for Measuring Gamma-Ray Fluxes in a Mixed Pulsed Neutron-Gamma Radiation Fields

    Publication Year: 2007 , Page(s): 1239 - 1243
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (198 KB) |  | HTML iconHTML  

    An ICI (insulator-conductor-insulator) gamma-ray detector designed for measurement of fast rising, high intensity pulsed gamma-ray fluxes has been developed. Like vacuum Compton diode (VCD) and dielectric Compton diode (DCD) devices, the ICI detector operates by utilization of the Compton effect. It has a very fast time response (rise time is less than 1 ns), a large linearity and a wide dynamic range. It is designed to measure intense and rapidly changing gamma-ray fluxes in highly mixed neutron-gamma radiation fields. Its sensitivity to 1.25 MeV gamma rays is about 1.8 x 10-20, for the 50 mm collimation diameter, which is relatively high compared with VCD and DCD devices. The simulated gamma-ray sensitivity agrees well with the experimental value. The gamma-to-neutron sensitivity ratio is about three orders of magnitudes for neutron energies below 14.1 MeV and 1.25 MeV gamma rays. Compared to existing VCD and DCD devices, the ICI detector requires no vacuum and power supply in operation, and also minimally attenuates a collimated gamma-ray beam due to its overall thickness of 3 mm in beam path. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electrically Erasable Metal–Oxide–Semiconductor Dosimeters

    Publication Year: 2007 , Page(s): 1244 - 1250
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    Metal-oxide-semiconductor (MOS) dosimetry including the reset of the sensor device for its reuse (reutilization) is described. The method consists in restoring the shifted threshold voltage after irradiation to a predefined value by the injection of a Fowler-Nordheim tunnel current. The amount of interface states per unit area is initially saturated in order to ensure repeatability. The method was tested on 70 nm pMOSFETs exposed to a 60Co source. After successive irradiations and erasures amounting several tens of kGy[SiO2], the devices exhibit a dispersion smaller than 2% in the responses. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Micro Reading Mesh Chamber

    Publication Year: 2007 , Page(s): 1251 - 1256
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3295 KB) |  | HTML iconHTML  

    Micro-pattern gas detectors (MPGD) could become suitable devices to carry out time-resolved X-ray diffraction experiments in the sub-millisecond time scale at synchrotron radiation facilities. Here we introduce a new MPGD design we have called micro reading mesh chamber (MRMC). It is a position-sensitive gas proportional counter that is built with advanced printed circuit board (PCB) technology. Its layout is based on a mesh formed by two planes of pick-up strips that is separated from the resistive anode by support pillars that set the multiplication region. The aim of the MRMC design has been to prevent the arising of dielectric breakdown and to avoid charging up. We present detailed simulation/optimization work and first experimental results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Gas Proportional Scintillation Counter With KI and KBr-Covered Microstrip Plate as Photosensor: Experimental Results

    Publication Year: 2007 , Page(s): 1257 - 1262
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    The performance of a xenon-filled gas proportional-scintillation counter is reported, where the VUV Xe scintillation is detected by KI or KBr photocathodes on a microstrip plate. The detector energy resolution R and gain G for 5.9 keV X-rays are presented and compared with previous results obtained with Csl photocathodes. R and G are studied as a function of the halide film thickness and scintillation region length. The best energy resolutions reached values of 12% and 15% for KI and KBr photocathodes, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improving Spectroscopic Performance of a Coplanar-Anode High-Pressure Xenon Gamma-Ray Spectrometer

    Publication Year: 2007 , Page(s): 1263 - 1270
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (719 KB) |  | HTML iconHTML  

    High-pressure xenon (HPXe) gas is a desirable radiation detection medium for homeland security applications because of its good inherent room-temperature energy resolution, potential for large, efficient devices, and stability over a broad temperature range. Past work in HPXe has produced large-diameter gridded ionization chambers with energy resolution at 662 keV between 3.5 and 4% FWHM. However, one major limitation of these detectors is resolution degradation due to Frisch grid microphonics. A coplanar-anode HPXe detector has been developed as an alternative to gridded chambers. An investigation of this detector's energy resolution is reported in this submission. A simulation package is used to investigate the contributions of important physical processes to the measured photopeak broadening. Experimental data is presented for pure Xe and Xe + 0.2%H2 mixtures, including an analysis of interaction location effects on the energy spectrum. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • First Results of a Scintillating GEM Detector for 2-D Dosimetry in an Alpha Beam

    Publication Year: 2007 , Page(s): 1271 - 1278
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB) |  | HTML iconHTML  

    The characterization of a scintillating GEM based gas detector for quality control of clinical radio-therapeutic beams is presented. Photons emitted by the Ar/CF4 gas mixture are detected by means of a CCD camera; in addition, the charge is measured. The detector response has been studied as a function of alpha particle energy and dose rate. The measured signal underestimation, at the Bragg peak depth, is only few percent with respect to an air filled ionization chamber. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal Background Attenuation for Fielded Radiation Detection Systems

    Publication Year: 2007 , Page(s): 1279 - 1284
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    Radiation detectors are often placed in positions difficult to shield from the effects of terrestrial background. This is particularly true in the case of radiation portal monitor (RPM) systems, as their wide viewing angle and outdoor installations make them susceptible to terrestrial background from the surrounding area. A low background is desired in most cases, especially when attempting to extract a weak signal. The problem of shielding a generalized RPM from terrestrial background is considered, to provide strong guidance to the designers of RPM systems. Various detector and shielding scenarios are modeled with the Monte-Carlo N Particle (MCNP) computer code. Amounts of nominal-density shielding needed to attenuate the terrestrial background to varying degrees are given, along with optimal shielding geometry to be used in areas where natural shielding is limited, and where radiation detection must occur in the presence of natural background. Common shielding solutions such as steel plating are evaluated based on the signal to noise ratio (SNR) and the benefits are weighed against the incremental cost. The greatest SNR increases for a generalized system are gained by shielding the internal detector cavity, direct shielding of the ground between the detectors, and the addition of collimators as long as are possible without changing the detector locations, or unnecessarily reducing the field of view. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radiographic Testing of Anomalies in Thick Metal Components: Fitting the Standard Line-Integral Model

    Publication Year: 2007 , Page(s): 1285 - 1297
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2927 KB) |  | HTML iconHTML  

    Radiography is an effective method for nondestructive inspection of thick metal components. However, complete diagnosis of internal defects is a difficult task that needs reliable computer assistance. In particular, fully 3-D reconstruction would be a very valuable tool for the expert, but it is not so clear whether digitized radiographs can be made suitable for reconstruction. We show that this is indeed the case by studying the radiographic image formation process in the context of primary loop piping inspection in pressurized water nuclear reactors. In a more general way, our findings apply to the testing of thick metal pecimens with simple, known geometry. Based on justified simplifications and approximations, we demonstrate that it is possible to process the raw data to closely fit the conventional line-integral projection model. More specifically, we provide a full processing procedure that includes (i) a criterion for subsampling the data without loss of pertinent information, (ii) a novel field-flattening algorithm, and (iii) a calibration method that requires minimal knowledge about the data acquisition parameters. The actual 3-D reconstruction issue is addressed in another paper whose results further validate the present work. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance Results of BGO Block Detectors Based on Flat Panel PS-PMT for PET

    Publication Year: 2007 , Page(s): 1298 - 1301
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB) |  | HTML iconHTML  

    We have developed a new detector composed of a 20times20 array of 2times2times20 mm3 Bi4Ge3O12 (BGO) scintillators and a novel flat panel position sensitive photomultiplier tube(FP-PS-PMT) - Hamamatsu R8400-00-M256. The performance of the block detector was evaluated in terms of applicability to positron emission tomography (PET). The energy resolution was about 23% FWHM for 511 keV gamma-rays. The spatial resolution of the detector was evaluated by measuring the detector response functions (DRFs) for each BGO segment and by measuring the coincidence response functions (CRFs). The average FWHM values of the DRFs were 2.0 mm. For the CRFs performance, the average FWHM values were 2.82 mm at 0deg and 5.20 mm at 30deg. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Power Reconstruction of Fuel Rods by Support Vector Regression for CANDU Reactors

    Publication Year: 2007 , Page(s): 1302 - 1310
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB) |  | HTML iconHTML  

    A support vector regression (SVR) model has been presented for reconstructing fuel rod powers from Canada deuterium uranium core calculations performed with a coarse-mesh finite difference diffusion approximation and single-assembly lattice calculations. The SVR is to nonlinearly map the original data into a higher dimensional feature space. Parameters related to the SVR are optimized by a genetic algorithm using the partial core calculation results of two 6 times 6 fuel bundle models (for training data). Verification has been conducted for two other partial core benchmark problems composed of 6 times 6 and 3 times 3 fuel bundles (for test data). The reconstructed fuel rod powers are compared with the reference solutions obtained with the detailed collision probability calculations using the HELIOS lattice analysis code. It is known from simulation results that the proposed rod power reconstruction algorithm is accurate, yielding the error due to the reconstruction scheme of less than 0.35%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Way of Single Optical Photon Detection: Beating the 1/f Noise Limit With Ultra High Resolution DEPFET-RNDR Devices

    Publication Year: 2007 , Page(s): 1311 - 1318
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1097 KB) |  | HTML iconHTML  

    In this work we demonstrate theoretically and experimentally the capability to reduce the readout noise of an optical and X-ray photon detector based on the semiconductor DEPFET device below a level of only 0.3e- ENC (equivalent noise charge). The readout method used is called "repetitive non destructive readout" (RNDR) and was realized by placing two single DEPFET-devices next to each other and by coupling their charge storing region by an additional gate. By transferring the stored charge from one DEPFET to the other and vice versa the same charge can be measured non-destructively and arbitrarily often. Taking the average value of a large number n of these measurements, the noise is reduced by 1/radicn. The main advantage of such a detector is to greatly reduce the contribution of the 1/f noise to the readout noise. The theoretically and experimentally achievable resolution for different operating parameters (leakage current, readout noise, number and duration of readouts) was investigated by Monte-Carlo simulations and verified on a real RNDR minimatrix (pixelarray). Single optical photon detection with high quantum efficiency and, even more fascinating, the possibility to distinguish between different numbers of photons, e.g., 100 from 101 are demonstrated in measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gamma-Ray Induced Radiation Damage in Large Size LSO and LYSO Crystal Samples

    Publication Year: 2007 , Page(s): 1319 - 1326
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1482 KB) |  | HTML iconHTML  

    This paper presents a study of the gamma-ray induced radiation damage effect in large size (2.5 times 2.5 times 20 cm3) LSO and LYSO crystal samples. Optical and scintillation properties, including longitudinal transmittance and photo-luminescence spectra, light output and light response uniformity with PMT and APD readout, are measured before and after gamma-ray irradiations with an integrated dose up to 106 rad for three LSO and LYSO samples from different vendors. It was found that 300degC thermal annealing removes all radiation induced absorption. The photo-luminescence spectra measured before and after the irradiations were found to be consistent, indicating that the scintillation mechanism is not damaged. The radiation damage recovers very slow under the room temperature, indicating that the radiation damage level in LSO and LYSO crystals is not dose rate dependent. It was also found that the overall radiation damage in LSO and LYSO crystals is small as compared to other crystal scintillators commonly used in high energy and nuclear physics experiments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Total Dose and Single Event Transients in Linear Voltage Regulators

    Publication Year: 2007 , Page(s): 1327 - 1334
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB) |  | HTML iconHTML  

    Radiation effects on four common DC linear voltage regulators are investigated. Increasing total dose is shown to degrade converter regulation by degrading the loop gain and phase response. Regulator single event transient (SET) response is characterized, and a mitigation technique is proposed. Shunt regulator topologies are found to be superior to series regulator topologies in terms of radiation tolerance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Radiation Hardened by Design Register File With Lightweight Error Detection and Correction

    Publication Year: 2007 , Page(s): 1335 - 1342
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1109 KB) |  | HTML iconHTML  

    A radiation hardened by design 32times36 b register file with error detection and correction (EDAC) capability is presented. The lightweight EDAC scheme (LEDAC) supports fine granularity (byte) writes, with low area and latency overhead, suitable for small, fast memories such as register file and first-level cache memory. The LEDAC scheme is described and its impact on memory efficiency and speed are quantified. The register file has been tested to be functional on a foundry 0.13 mum bulk CMOS process with a measured speed over 1 GHz at VDD=1.5 V. The LEDAC scheme is implemented in an external FPGA. Accelerated heavy ion testing results are also described. The experimentally measured RHBD register file SEE behavior is examined, and the proposed LEDAC scheme is shown to alleviate all soft errors in accelerated testing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Total Ionizing Dose Mitigation by Means of Reconfigurable FPGA Computing

    Publication Year: 2007 , Page(s): 1343 - 1349
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    We present a novel design technique for hardening field programmable gate arrays (FPGAs) against total ionizing dose (TID). There is increasing use of commercial components in space technology and it is important to recognize that the space radiation environment poses the risk of permanent malfunction due to radiation. Therefore, the integrated circuits used for spacecraft electronics must be resistant to radiation. The amount of threshold voltage shift in MOS devices caused by ionizing radiation is strongly dependant on the bias voltage applied to the gate terminal during radiation. The threshold voltage shift is much less severe under the influence of ionizing radiation if the gate voltage is 0 V with respect to the device substrate. We have direct control of the bias voltage applied to the gate terminal, and therefore can control the rate of threshold voltage shift in the MOS device. Digital electronic circuits can be hardened against TID effects by selectively applying modular redundancy. By applying Double Modular redundancy, hence, activating one module while the other is inactivated, allows the inactive modules to stop degrading during its ldquooffrdquo cycle. It is shown by means of experimentation that this new design technique provides greatly improved TID tolerance for field programmable gate arrays by means of reconfigurable computing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ultra High Flux 2-D CdZnTe Monolithic Detector Arrays for X-Ray Imaging Applications

    Publication Year: 2007 , Page(s): 1350 - 1358
    Cited by:  Papers (25)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2661 KB) |  | HTML iconHTML  

    The performance of 2-D CdZnTe monolithic detector arrays designed for high flux X-ray imaging applications was studied. For the first time we have obtained 5 times 106 counts/s/mm2 count-rate for a CdZnTe pixelated detector array. This count-rate is more than twice the highest count-rate ever achieved using a CdZnTe detector array. Such excellent performance was demonstrated for more than 600 individual CdZnTe detector arrays. The 2-D CdZnTe monolithic arrays were 16 x 16 pixel devices with 0.4 mm times 0.4 mm area pixels on a 0.5 mm pitch and were fabricated using 8.7 mm times 8.7 mm times 3.0 mm CdZnTe single crystals grown by the high-pressure, electro-dynamic gradient freeze technique. The CdZnTe detector arrays were bonded to a ceramic substrate with the Z-bondtrade technique. This enabled performance testing of the individual detector arrays before bonding to the read-out ASIC chip. The detector arrays were characterized in a custom designed test system. The measurement and data acquisition system consisted of a 16 times 16 pin probe head and 256-channel read-out electronics controlled by a host PC. We utilized our 8-channel fast bipolar ASIC chip and computer controlled 120 kVp X-ray source. In order to measure the true throughput of the CdZnTe devices a counts correction method was developed and implemented that compensates for the counting system non-linearity caused by pile-up and amplifier shaping time effects. Survey of detector array performance as a function of CdZnTe charge transport properties showed that the maximum achievable count-rate of these detectors strongly depends on the hole charge transport properties of the crystals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Paul Dressendorfer
11509 Paseo del Oso NE
Albuquerque, NM  87111  USA