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Nuclear Science, IEEE Transactions on

Issue 3 • Date Jun 1995

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Displaying Results 1 - 10 of 10
  • Numerical simulation of single event latchup in the temperature range of 77-450 K

    Page(s): 148 - 154
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    In this paper, the temperature dependence of single event latchup in CMOS structures is studied over a temperature range of 77-450 K through two-dimensional device simulation with full-temperature models. Single event latchup immunity first increases as the temperature decreases from 450 K to 120 K, and then decreases rapidly with further decrease in temperature. Therefore, superior latchup immunity can be expected at about 120 K. Furthermore, latchup immunity at 77 K is almost equal or somewhat inferior to that at room temperature. It can be predicted from our results that CMOS devices become extremely susceptible to single event latchup at temperatures below 77 K just as they do at very high temperatures View full abstract»

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  • A novel radiation imaging sensor based on self-activated pixels

    Page(s): 155 - 162
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    A new position sensitive detector for charged particles and X-rays is proposed based on pixels containing MOS transistors as preamplifiers. The output of the preamplifiers is shorted to strip buses to obtain two-dimensional information with readout requirements similar to a strip detector. The total pixel capacitance is low enough (20-40 fF) to allow a large potential increase at the pixel that collected the charge. The nonlinearity introduced by the large voltage rise effectively switches on the transistors of this pixel and leaves all the other pixels of the same line at a low transconductance state, resulting in an excellent noise performance View full abstract»

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  • CMOS radiation sensor with binary output

    Page(s): 174 - 178
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    A radiation sensor compatible with CMOS technology is presented. It provides a binary output which changes its state when the total radiation dose exceeds a prefixed threshold. This circuit is intended to be used as a built-in sensor in standard circuits, to prevent malfunction due to radiation hazards. After measuring the radiation effects on MOS devices, the sensitivity of different sensor designs has been calculated View full abstract»

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  • Radiation damage factor for ion-implanted silicon detectors irradiated with heavy ions

    Page(s): 163 - 166
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    Ion-implanted silicon detectors were irradiated with 18-150 MeV 16O, 20 MeV 40Ar, and 53 MeV 110Xe. A linear increase of the leakage current was observed as a function of the particle fluence up to 2.2×108 cm-2. Extracted damage factors are proportional to the averaged nuclear stopping power over five orders of magnitude covering heavy ions studied in the present work and also protons of 25-800 MeV energies View full abstract»

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  • Position sensitive photon counting with an ISPA tube

    Page(s): 130 - 133
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    The newly developed Imaging Silicon Pixel Array (ISPA) tube consists of a photocathode viewed at a 30-mm distance by a silicon chip, which contains 1024 pixels with 75 μm×500 μm edges. With this tube we imaged, as an example of a weak light source, β-tracks (90Sr) traversing a fused square bundle (2.5 mm edges), which contains 1600 individual scintillating fibers of 60-μm transverse dimension. Simultaneously we counted the number of photoelectrons/mm (hit density) at different source positions along the 2-m fiber bundle, with potential differences varying from 10 kV to 26 kV between photocathode and pixel anode of the ISPA tube, and at different threshold settings of the pixel chip. The obtained hit densities are compared with those measured with a Hybrid Photomultiplier Tube (HPMT), which contains a silicon pin diode as anode instead of a pixel chip View full abstract»

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  • Gamma-ray imaging laboratory measurements using externally segmented germanium detectors

    Page(s): 121 - 129
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    Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy using an externally segmented germanium sensor has been demonstrated in the laboratory with a calibrated radioactive source. The system employs a single high-purity coaxial detector with its outer electrode segmented into five distinct charge collection regions and a lead coded aperture, with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180°. A nonnegative, linear least-squares algorithm was then employed to reconstruct a two-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process View full abstract»

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  • Calculation of track and vertex errors for detector design studies

    Page(s): 134 - 147
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    The Kalman filter technique has come into wide use for charged track reconstruction in high-energy physics experiments. It is also well suited for detector design studies, allowing for the efficient estimation of optimal track covariance matrices without the need of a hit level Monte Carlo simulation. Although much has been published about the Kalman filter equations, there is a lack of previous literature explaining how to implement the equations. In this paper, the operators necessary to implement the Kalman filter equations for two common detector configurations are worked out: a central detector in a uniform solenoidal magnetic field, and a fixed-target detector with no magnetic field in the region of the interactions. With the track covariance matrices in hand, vertex and invariant mass errors are readily calculable. These quantities are particularly interesting for evaluating experiments designed to study weakly decaying particles which give rise to displaced vertices. The optimal vertex errors are obtained via a constrained vertex fit. Solutions are presented to the constrained vertex problem with and without kinematic constraints. Invariant mass errors are obtained via propagation of errors; the use of vertex constrained track parameters is discussed. Many of the derivations are new or previously unpublished View full abstract»

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  • Evaluation of K X-ray escape and crosstalk in CdTe detectors and multi-channel detectors

    Page(s): 179 - 184
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    The simple structure of CdTe semiconductor detectors facilitates their downsizing, and their possible application to radiographic sensors has been studied. The escape of K X-rays from these detectors increases with reduction of their dimensions and affects the measurements of X- and gamma-ray spectra. K X-rays also produce crosstalk in multi-channel detectors with adjacent channels. Therefore, K X-rays which escape from the detector elements degrade both the precision of energy spectra and spatial resolution. The ratios of escape peak integrated counts to total photon counts for various sizes of CdTe single detectors were calculated for gamma rays using the Monte Carlo method. Also, escape and crosstalk ratios were simulated for the CdTe multi-channel detectors. The theoretical results were tested experimentally for 59.54-keV gamma rays from a 241Am radioactive source. Results showed that escape ratios for single detectors were strongly dependent on element size and thickness. The escape and crosstalk ratios increased with closer channel pitch. Our calculated results showed a good agreement with the experimental data. The calculations made it clear that K X-rays which escaped to neighboring channels induced crosstalk more frequently at smaller channel pitch in multi-channel detectors. A radiation shielding grid which blocked incident photons between the boundary channels was also tested by experiment and by calculation. It was effective in reducing the probability of escape and crosstalk View full abstract»

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  • A systematic study of the initial electrical and radiation hardness properties of reoxidized nitrided oxides by rapid thermal processing

    Page(s): 167 - 173
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    The initial electrical and radiation hardness properties of MOS capacitors with reoxidized nitrided oxides (RNO) structures are systematically investigated by changing the pressure, temperature, and times of nitridation and reoxidation in rapid thermal processes. It was found that the initial flat-band voltage (Vfb) and midgap interface trap density (Ditm) are strongly dependent on the growth conditions and show concave or convex “turnaround” dependency on some process parameters. This may be explained by the hydrogen evaporation and oxygen passivation mechanisms. The radiation induced flat-band voltage shift (ΔVfb) and midgap interface trap density shift (ΔDitm) are also growth-condition dependent and show different “turnaround” dependencies on some process parameters from those observed in initial properties. This may be explained by the variations of the amount of hydrogen-related species such as Si-NH, Si-H, or Si-OH, and nitrogen-related species, such as Si-N, in the oxide bulk and at the Si/SiO2 interface. Finally, the sample with a reoxidation pressure of 250 torr, a reoxidation temperature of 1050°C, and a reoxidation time of 100 s is suggested to be the most radiation-hard together with good initial properties for RNO devices View full abstract»

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  • Pulsed X-ray induced transient absorption in LiNbO3, TiO 2:LiNbO2, and MgO:LiNbO3 at 1061 nm

    Page(s): 117 - 120
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    Characteristics of pulsed X-ray induced transient absorption at 1061 mm have been determined for LiNbO3, TiO2:LiNbO3, and MgO:LiNbO3. The addition of the dopants TiO2 and MgO reduces the induced absorption significantly. The two materials, LiNbO3 and TiO 2:LiNbO3, decay with an approximate 1/t1/4 time dependence for the time interval 0.01 to 8 ms. After 8 ms, the decay rate for LiNbO3 is faster than 1/t1/4, and the decay rate for TiO2:LiNbO3 is slower than that initial rate. A low-intensity absorption which lasts for about 20 μs is observed for the MgO:LiNbO3. Peak radiation induced absorption coefficients for LiNbO3, TiO2:LiNbO3, and MgO:LiNbO3 have been determined View full abstract»

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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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