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  1. Monitoring SEU parameters at reduced bias

    SciTech Connect

    Roth, D.R.; McNulty, P.J.; Abdel-Kader, W.G.; Strauss, L. . Dept. of Physics and Astronomy); Stassinopoulos, E.G. )

    1993-12-01

    SEU sensitivity of a CMOS SRAM increases with decreasing bias in such a manner that the critical charge exhibits a linear dependence on bias. This should allow proton and neutron monitoring of SEU parameters even for radiation hardened devices. The sensitivity of SEU rates to the thickness of the sensitive volume is demonstrated and procedures for determining the SEU parameters using protons are outlined.

  2. Guidelines for SEU-Resistant Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.

    1986-01-01

    Paper presents recent results of continuing program for increasing resistance of integrated circuits to single-event upset (SEU). Results based on study of test data for heavy-ion SEU in more than 180 different types of devices. (Some devices perform identical functions but made by different processes.) Program also examines developments in mathematical models for SEU.

  3. SEU In An Advanced Bipolar Integrated Circuit

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Secrest, Elaine C.; Berndt, Dale F.

    1989-01-01

    Report summarizes investigation of single-event upsets (SEU) in bipolar integrated-circuit set of flip-flops (memory cells). Device tested made by advanced digital bipolar silicon process of Honeywell, Inc. Circuit chip contained 4 cells. Construction enabled study of effect of size on SEU behavior. Each cell externally biased so effect of bias current on SEU behavior. Results of study provides important information for optimal design of devices fabricated using buried-layer bipolar process operating in heavy-ion SEU environments. Designers use information to provide required levels of suppression of SEU in specific applications via combinations of size and/or cell-current scaling.

  4. SEU measurements on HFETS and HFET SRAMS

    SciTech Connect

    Remke, R.L.; Witmer, S.B.; Jones, S.D.F. ); Barber, F.E. ); Flesner, L.D.; O'Brien, M.E. )

    1989-12-01

    The single event upset (SEU) response of n{sup +}-AlGaAs/GaAs heterostructure field effect transistors(HFETs--also known as SDHTs, HEMTs, MODFETs, and TEGFETs) and HFET static random access memories (SRAMs) was evaluated by measuring their response to focused electron pulses. Initially, focused electron beam pulses were used to measure and model HFET drain and gate SEU responses. Circuit simulations using these SEU models predicted that an HFET memory is most vulnerable to a single particle event in the area between the drain and the source (drain hit) of the OFF pull down HFET. Subsequent testing of an HFET SRAM cell confirmed this prediction. The authors discuss how these first SEU evaluations of HFETs and HFET memories show that measurements on individual HFETs and circuit simulations of SEU hits may be used to predict the SEU response of HFET memories.

  5. SEU induced errors observed in microprocessor systems

    SciTech Connect

    Asenek, V.; Underwood, C.; Oldfield, M.; Velazco, R.; Rezgui, S.; Cheynet, P.; Ecoffet, R.

    1998-12-01

    In this paper, the authors present software tools for predicting the rate and nature of observable SEU induced errors in microprocessor systems. These tools are built around a commercial microprocessor simulator and are used to analyze real satellite application systems. Results obtained from simulating the nature of SEU induced errors are shown to correlate with ground-based radiation test data.

  6. Single event upset (SEU) testing at JPL

    NASA Technical Reports Server (NTRS)

    Coss, James R.

    1987-01-01

    It is believed that the increase in SEUs with more modern devices may have serious consequences for future space missions. The physics behind an SEU is discussed as well as SEU test philosophy and equipment, and testing results. It is concluded that the problem may be ameliorated by careful device selection and the use of redundancy or error correction.

  7. SEU Performance of TAG Based Flip Flops

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L.; Kouba, Coy; O'Neill, Patrick M.

    2005-01-01

    We describe heavy ion test results for two new SEU tolerant latches based on transition nand gates, one for single rail asynchronous and the other for dual rail synchronous designs, implemented in AMI 0.5microprocess.

  8. Critical issues regarding SEU in avionics

    SciTech Connect

    Normand, E. ); McNulty, P.J. )

    1993-01-01

    The energetic neutrons in the atmosphere cause microelectronics in avionic system to malfunction through a mechanism called single-event upsets (SEUs), and single-event latchup is a potential threat. Data from military and experimental flights as well as laboratory testing indicate that typical non-radiation-hardened 64K and 256K static random access memories (SRAMs) can experience a significant SEU rate at aircraft altitudes. Microelectronics in avionics systems have been demonstrated to be susceptible to SEU. Of all device types, RAMs are the most sensitive because they have the largest number of bits on a chip (e.g., an SRAM may have from 64K to 1M bits, a microprocessor 3K to 10K bits, and a logic device like an analog-to-digital converter, 12 bits). Avionics designers will need to take this susceptibility into account in current and future designs. A number of techniques are available for dealing with SEU: EDAC, redundancy, use of SEU-hard parts, reset and/or watchdog timer capability, etc. Specifications should be developed to guide avionics vendors in the analysis, prevention, and verification of neutron-induced SEU. Areas for additional research include better definition of the atmospheric neutrons and protons, development of better calculational models (e.g., those used for protons[sup 11]), and better characterization of neutron-induced latchup.

  9. A simple approach to SEU cross section evaluation

    SciTech Connect

    Miroshkin, V.V.; Tverskoy, M.G.

    1998-12-01

    The simplified method for determination of proton induced SEU cross section is presented. The method is based on results of the analysis of experimental SEU cross sections initiated by fast nucleons. The possibility of SEU cross section measurement at single proton energy for SEU rate prediction is shown.

  10. Serendipitous SEU hardening of resistive load SRAMs

    SciTech Connect

    Koga, R.; Kirshman, J.F.; Pinkerton, S.D.; Hansel, S.J.; Crawford, K.B.; Crain, W.R.

    1996-06-01

    High and low resistive load versions of Micron Technology`s MT5C1008C (128K {times} 8) and MT5C2561C (256K {times} 1) SRAMs were tested for SEU vulnerability. Contrary to computer simulation results, SEU susceptibility decreased with increasing resistive load. A substantially larger number of multiple-bit errors were observed for the low resistive load SRAMs, which also exhibited a 1 {r_arrow} 0 to 0 {r_arrow} 1 bit error ratio close to unity; in contrast, the high resistive load devices displayed a pronounced error bit polarity effect. Two distinct upset mechanisms are proposed to account for these observations.

  11. SEU hardening of CMOS memory circuit

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Canaris, J.; Liu, K.

    1990-01-01

    This paper reports a design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.

  12. Low power SEU immune CMOS memory circuits

    NASA Technical Reports Server (NTRS)

    Liu, M. N.; Whitaker, Sterling

    1992-01-01

    The authors report a design improvement for CMOS static memory circuits hardened against single event upset (SEU) using a recently proposed logic/circuit design technique. This improvement drastically reduces static power consumption, reduces the number of transistors required in a D flip-flop design, and eliminates the possibility of capturing an upset state in the slave section during a clock transition.

  13. Comparative SEU sensitivities to relativistic heavy ions

    SciTech Connect

    Koga, R.; Crain, S.H.; Crain, W.R.; Crawford, K.B.; Hansel, S.J.

    1998-12-01

    SEU sensitivity of microcircuits to relativistic heavy ions is compared to that measured with low-energy ions of comparable LET values. Multiple junction charge collection in a complex circuit seems to mask the effect of varying charge generations due to different iron track structures. Heavy ions at sub-relativistic speeds may generate nuclear fragments, sometimes resulting in SEUs.

  14. SEU/SRAM as a Process Monitor

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Buehler, M. G.

    1993-01-01

    The SEU/SRAM is a 4-kbit Static Random Access Memory (SRAM) designed to detect Single-Event Upsets (SEUs) produced by high energy particles. This device was used to determine the distribution in the memory cell spontaneous flip potential.

  15. An SEU tolerant memory cell derived from fundamental studies of SEU mechanisms in SRAM

    SciTech Connect

    Weaver, H.T.; Axness, C.L.; McBrayer, J.D.; Browning, J.S.; Fu, J.S.; Ochoa, A. Jr.; Koga, R.

    1987-12-01

    A new single event upset (SEU) hardening concept, an LRAM cell, is demonstrated theoretically and experimentally. Decoupling resistors in the LRAM are used only to protect against the short n-channel transient; longer persisting pulses are reduced in magnitude by a voltage divider, a basically new concept for SEU protection. In such a design, smaller resistors provide SEU tolerance, allowing higher performance, hardened memories. As basis for the LRAM idea, techniques were developed to measure time constants for ion induced voltage transients in conventional static random access memories, SRAM. Time constants of 0.8 and 6.3 nsec were measured for transients following strikes at the n- and p-channel drains, respectively - primary areas of SEU sensitivity. These data are the first transient time measurements on full memory chips and the large difference is fundamental to the LRAM concept. Test structures of the new design exhibit equivalent SEU tolerance with resistors 5-to-10 times smaller than currently used in SRAM. Our advanced transport-plus-circuit numerical simulations of the SEU process predicted this result and account for the LRAM experiments, as well as a variety of experiments on conventional SRAM.

  16. Refined Transistor Model For Simulation Of SEU

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Benumof, Reuben

    1988-01-01

    Equivalent base resistance added. Theoretical study develops equations for parameters of Gummel-Poon model of bipolar junction transistor: includes saturation current, amplification factors, charging times, knee currents, capacitances, and resistances. Portion of study concerned with base region goes beyond Gummel-Poon analysis to provide more complete understanding of transistor behavior. Extended theory useful in simulation of single-event upset (SEU) caused in logic circuits by cosmic rays or other ionizing radiation.

  17. Recent trends in parts SEU susceptibility from heavy ions

    SciTech Connect

    Nichols, D.K.; Smith, L.S.; Price, W.E.; Koga, R.; Kolasinski, W.A.

    1987-12-01

    JPL and Aerospace have collected an extensive set of heavy ion single event upset (SEU) test data since their last joint publication in December, 1985. Trends in SEU susceptibility for state-of-the-art parts are presented.

  18. Upper-Bound Estimates Of SEU in CMOS

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    1990-01-01

    Theory of single-event upsets (SEU) (changes in logic state caused by energetic charged subatomic particles) in complementary metal oxide/semiconductor (CMOS) logic devices extended to provide upper-bound estimates of rates of SEU when limited experimental information available and configuration and dimensions of SEU-sensitive regions of devices unknown. Based partly on chord-length-distribution method.

  19. Simulation of SEU transients in CMOS ICs

    SciTech Connect

    Kaul, N.; Bhuva, B.L.; Kerns, S.E. )

    1991-12-01

    This paper reports that available analytical models of the number of single-event-induced errors (SEU) in combinational logic systems are not easily applicable to real integrated circuits (ICs). An efficient computer simulation algorithm set, SITA, predicts the vulnerability of data stored in and processed by complex combinational logic circuits to SEU. SITA is described in detail to allow researchers to incorporate it into their error analysis packages. Required simulation algorithms are based on approximate closed-form equations modeling individual device behavior in CMOS logic units. Device-level simulation is used to estimate the probability that ion-device interactions produce erroneous signals capable of propagating to a latch (or n output node), and logic-level simulation to predict the spread of such erroneous, latched information through the IC. Simulation results are compared to those from SPICE for several circuit and logic configurations. SITA results are comparable to this established circuit-level code, and SITA can analyze circuits with state-of-the-art device densities (which SPICE cannot). At all IC complexity levels, SITAS offers several factors of 10 savings in simulation time over SPICE.

  20. Laser SEU sensitivity mapping of deep submicron CMOS SRAM

    NASA Astrophysics Data System (ADS)

    Yongtao, Yu; Guoqiang, Feng; Rui, Chen; Jianwei, Han

    2014-06-01

    The pulsed laser facility for SEU sensitivity mapping is utilized to study the SEU sensitive regions of a 0.18 μm CMOS SRAM cell. Combined with the device layout micrograph, SEU sensitivity maps of the SRAM cell are obtained. TCAD simulation work is performed to examine the SEU sensitivity characteristics of the SRAM cell. The laser mapping experiment results are discussed and compared with the electron micrograph information of the SRAM cell and the TCAD simulation results. The results present that the test technique is reliable and of high mapping precision for the deep submicron technology device.

  1. Scaling of SEU mapping and cross section, and proton induced SEU at reduced supply voltage

    SciTech Connect

    Barak, J.; Levinson, J.; Akkerman, A.

    1999-12-01

    New experimental study of heavy ion and proton induced SEU at reduced voltage (i.e., reduced critical charge) reveals interesting results. It is shown that the heavy ion cross section and microprobe mapping scale like the threshold LET and the parameter, which is almost invariant under bias changes, is the effective charge collection depth. For studying proton induced SEU and surface-barrier-detector spectra the authors use protons with energies from 5.6 to 300 MeV. The results are analyzed in view of the processes involved in low energy deposition by protons. Detailed calculations show the importance of straggling in proton direct ionization which might be the leading process in very sensitive devices like photodiodes.

  2. Exact Chord-Length Distribution For SEU Calculations

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Luke, Keung L.

    1990-01-01

    Computed rates of SEU's more accurate. Exact integral chord-length distribution derived for use in calculations of rates of single-event upsets (SEU's) (changes in logic states) caused by impingement of cosmic rays or other ionizing radiation on electronic logic circuits.

  3. Simulation of SRAM SEU Sensitivity at Reduced Operating Temperatures

    NASA Technical Reports Server (NTRS)

    Sanathanamurthy, S.; Ramachandran, V.; Alles, M. L.; Reed, R. A.; Massengill, L. W.; Raman, A.; Turowski, M.; Mantooth, A.; Woods, B.; Barlow, M.; Moen, K.; Bellini, M.; Sutton, A.; Cressler, J. D.

    2009-01-01

    A new NanoTCAD-to-Spectre interface is applied to perform mixed-mode SEU simulations of an SRAM cell. Results using newly calibrated TCAD cold temperature substrate mobility models, and BSIM3 compact models extracted explicitly for the cold temperature designs, indicate a 33% reduction in SEU threshold for the range of temperatures simulated.

  4. Impact of technology trends on SEU in CMOS SRAMs

    SciTech Connect

    Dodd, P.E.; Sexton, F.W.; Hash, G.L.; Shaneyfelt, M.R.; Draper, B.L.; Farino, A.J.; Flores, R.S.

    1996-12-01

    The impact of technology trends on the SEU hardness of epitaxial CMOS SRAMs is investigated using three-dimensional simulation. The authors study trends in SEU susceptibility with parameter variations across and within technology generations. Upset mechanisms for various strike locations and their dependence on gate-length scaling are explored. Such studies are useful for technology development and providing input for process and design decisions. An application of SEU simulation to the development of a 0.5-{micro}m radiation-hardened CMOS SRAM is presented.

  5. Single-event upset (SEU) in a dram with on-chip error correction

    SciTech Connect

    Zoutendyk, J.A.; Schwartz, H.R.; Watson, R.K.; Hasnain, Z.; Nevill, L.R.

    1987-12-01

    The results are given of the first SEU measurements ever reported on IC devices with on-chip error correction. This method of SEU abatement could revolutionize the design of SEU-immune electronic systems.

  6. A SEU-Hard Flip-Flop for Antifuse FPGAs

    NASA Technical Reports Server (NTRS)

    Katz, R.; Wang, J. J.; McCollum, J.; Cronquist, B.; Chan, R.; Yu, D.; Kleyner, I.; Day, John H. (Technical Monitor)

    2001-01-01

    A single event upset (SEU)-hardened flip-flop has been designed and developed for antifuse Field Programmable Gate Array (FPGA) application. Design and application issues, testability, test methods, simulation, and results are discussed.

  7. SEU System Analysis: Not Just the Sum of All Parts

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Label, Kenneth

    2014-01-01

    Single event upset (SEU) analysis of complex systems is challenging. Currently, system SEU analysis is performed by component level partitioning and then either: the most dominant SEU cross-sections (SEUs) are used in system error rate calculations; or the partition SEUs are summed to eventually obtain a system error rate. In many cases, system error rates are overestimated because these methods generally overlook system level derating factors. The problem with overestimating is that it can cause overdesign and consequently negatively affect the following: cost, schedule, functionality, and validation/verification. The scope of this presentation is to discuss the risks involved with our current scheme of SEU analysis for complex systems; and to provide alternative methods for improvement.

  8. A new method for using Cf-252 in SEU testing

    NASA Technical Reports Server (NTRS)

    Costantine, A.; Howard, J. W.; Becker, M.; Block, R. C.; Smith, L. S.; Soli, G. A.; Stauber, M. C.

    1990-01-01

    A system using Cf-252 and associated nuclear instrumentation has determined the single-event upset (SEU) cross section versus linear energy transfer (LET) curve for several 2K x 8 static random access memories (SRAMs). The Cf-252 fission fragments pass through a thin-film organic scintillator detector (TFD) on the way to the device under test (DUT). The TFD provides energy information for each transiting fragment. Data analysis provides the energy of the individual ion responsible for each SEU; thus, separate upset cross sections can be developed for different energy and mass regions of the californium spectrum. This californium-based device is quite small and fits onto a bench top. It provides a convenient and inexpensive supplement or alternative to accelerator and high-altitude/space SEU testing.

  9. On the figure of merit model for SEU rate calculations

    SciTech Connect

    Barak, J.; Reed, R.A.; LaBel, K.A.

    1999-12-01

    Petersen has introduced a one parameter characterization of a device by the Figure of Merit (FOM). It was claimed that this parameter was sufficient to estimate the SEU rate in almost all orbits. The present paper presents an analytic study of the FOM concept and compares the FOM model with other empirical models. It is found that indeed the FOM parameter gives, in most cases, a good agreement with the rates found using the full SEU cross section plots of the devices. The agreement is poorer in cases where a high portion of the proton flux comes from low energy protons and for very SEU-hard devices. This is demonstrated for certain devices (FPGAs) where the FOM predicted by proton may be smaller by an order of magnitude than the FOM from heavy ions.

  10. Temporal analysis of SEU in SOI/GAA SRAMs

    SciTech Connect

    Francis, P.; Colinge, J.P.; Berger, G.

    1995-12-01

    This paper analyzes the very strong SEU hardness of a 1k static random-access memory fabricated using the SOI/GAA technology, irradiated with a xenon ion beam at various angles of incidence. The memory has been shown to operate with a supply voltage as low as 2V while still presenting excellent SEU hardness. Since the different physical charge collection mechanisms are particularly slow in SOI devices, it is shown that collected and critical charges must be dynamically compared in order to determine the SEU threshold. A new approach is then proposed to evaluate the time-variable critical charge independently of the pulse shape generated by the incident ion, and a general analytical model is derived. Finally, predictions in good agreement with experimental data are obtained.

  11. Estimating the dimensions of the SEU-sensitive volume

    SciTech Connect

    Abdel-Kader, W.G.; McNulty, P.J.; El-Teleaty, S.; Lynch, J.E.; Khondker, A.N.

    1987-12-01

    Simulations of the diffusion contribution to charge collection in SEU events are carried out under the simple assumption of random walk. The results of the simulation are combined with calculations of the funneling length for the field-assisted drift components to determine the effective thickness of the sensitive volume element to be used in calculations of soft-error rates for heavy-ion-induced and proton-induced upsets in microelectronic circuits. Comparison is made between predicted and measured SEU cross-sections for devices for which the critical charges are known from electrical measurements and the dimensions of the sensitive volume used are determined by the techniques described. The agreement is sufficient to encourage confidence that SEU rates can be calculated from first principles and a knowledge of the material, structural, and electrical characteristics of the device.

  12. SEU43 fuel bundle shielding analysis during spent fuel transport

    SciTech Connect

    Margeanu, C. A.; Ilie, P.; Olteanu, G.

    2006-07-01

    The basic task accomplished by the shielding calculations in a nuclear safety analysis consist in radiation doses calculation, in order to prevent any risks both for personnel protection and impact on the environment during the spent fuel manipulation, transport and storage. The paper investigates the effects induced by fuel bundle geometry modifications on the CANDU SEU spent fuel shielding analysis during transport. For this study, different CANDU-SEU43 fuel bundle projects, developed in INR Pitesti, have been considered. The spent fuel characteristics will be obtained by means of ORIGEN-S code. In order to estimate the corresponding radiation doses for different measuring points the Monte Carlo MORSE-SGC code will be used. Both codes are included in ORNL's SCALE 5 programs package. A comparison between the considered SEU43 fuel bundle projects will be also provided, with CANDU standard fuel bundle taken as reference. (authors)

  13. SEU characterization and design dependence of the SA3300 microprocessor

    SciTech Connect

    Sexton, F.W.; Treece, R.K.; Axness, C.L.; Hughes, K.H.; Hash, G.L.; Hass, K.J.

    1990-01-01

    The SA3300 16-bit microprocessor is a key component for interplanetary space probes to be launched in the 1990's. A full SEU characterization of the D-latches of the SA3300 is given, including pattern sensitivity and temperature. 9 refs., 5 figs.

  14. An SEU-hardened CMOS data latch design

    SciTech Connect

    Rockett, L.R. Jr.

    1988-12-01

    A Single Event Upset (SEU)-hardened Complementary Metal-Oxide Semiconductor (CMOS) data latch design is described. The hardness is achieved by virtue of the latch design, thus no fabrication process or design groundrule development is required. Hardness is gained with comparatively little adverse impact on performance. Cyclotron tests provided hardness verification.

  15. SEU-hardened storage cell validation using a pulsed laser

    SciTech Connect

    Velazco, R.

    1996-12-01

    Laser tests performed on a prototype chip to validate new SEU-hardened storage cell designs revealed unexpected latch-up and single-event upset phenomena. The investigations that identified their location show the existence of a topology-dependent dual node upset mechanism. Design solutions are suggested to avoid its occurrence.

  16. Importance of ion energy on SEU in CMOS SRAMs

    SciTech Connect

    Dodd, P.E.; Shaneyfelt, M.R.; Sexton, F.W.; Hash, G.L.; Winokur, P.S.; Musseau, O.; Leray, J.L.

    1998-03-01

    The single-event upset (SEU) responses of 16 Kbit to 1 Mbit SRAMs irradiated with low and high-energy heavy ions are reported. Standard low-energy heavy ion tests appear to be sufficiently conservative for technologies down to 0.5 {micro}m.

  17. Relationship between IBICC imaging and SEU in CMOS ICs

    SciTech Connect

    Sexton, F.W.; Horn, K.M.; Doyle, B.L.; Laird, J.S.; Cholewa, M.; Saint, A.; Legge, G.J.F.

    1993-03-01

    Ion-beam-induced charge-collection (IBICC) images of the TA670 16K-bit CMOS SRAM are analyzed and compared to previous SEU images. Enhanced charge collection was observed in the n-source/drains regions consistent with bipolar amplification or shunting.

  18. SEU sensitive depth in a submicron SRAM technology

    SciTech Connect

    Detcheverry, C.; Bruguier, G.; Palau, J.M.; Gasiot, J.; Ecoffet, R.; Duzellier, S.; Barak, J.; Lifshitz, Y.

    1998-06-01

    This work determines experimentally and by simulation the SEU sensitive depth in a 0.6 {micro}m SRAM technology. A good correlation is obtained between the two studies in the case of heavy ions deposing energy close to the critical energy. Other simulation results complete the first investigation by studying the minimum sensitive depth for ions deposing higher energies (at greater LET).

  19. Upper-Bound SEU Rates In Anisotropic Fluxes

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    1993-01-01

    Upper bounds on rates of single-event upsets (SEU's) in digital integrated circuits and other electronic devices exposed to anisotropic fluxes of energetic ionizing particles computed by use of improved method. Derived from simplified, worst-case mathematical models of charge-collecting volumes and physical phenomena in electronic devices.

  20. Relationship between IBICC imaging and SEU in CMOS ICs

    SciTech Connect

    Sexton, F.W.; Horn, K.M.; Doyle, B.L. ); Laird, J.S.; Cholewa, M.; Saint, A.; Legge, G.J.F. )

    1993-01-01

    Ion-beam-induced charge-collection (IBICC) images of the TA670 16K-bit CMOS SRAM are analyzed and compared to previous SEU images. Enhanced charge collection was observed in the n-source/drains regions consistent with bipolar amplification or shunting.

  1. Some aspects of application of the two parameter SEU model

    SciTech Connect

    Miroshkin, V.V.; Tverskoy, M.G.

    1995-12-01

    Influence of the projectile type, pion production in nucleon-nucleon interaction inside nucleus and direction of the beam incidence on SEU cross section for INTEL 2164A microcircuit in framework of the two parameter model is investigated. Model parameters for devices, investigated recently are reported. Optimum proton energies for determination of model parameters are proposed.

  2. SEU evaluation of FeRAM memories for space applications

    NASA Technical Reports Server (NTRS)

    Scheick, L.; Guertin, S.; Nguyen, d.

    2002-01-01

    SEU cross-sections were obtained for two different FeRAM memories: The 64 kbit and 256 kbit Ramtron FeRAM and the Hynix 64 kbit device. The devices were seen to have latch-up characteristics typical of commercial CMOS. Also, errors in the memory were also seen from heavy ion irradiation.

  3. Test results for SEU and SEL immune memory circuits

    NASA Technical Reports Server (NTRS)

    Wiseman, D.; Canaris, J.; Whitaker, S.; Gambles, J.; Arave, K.; Arave, L.

    1993-01-01

    Test results for three SEU logic/circuit hardened CMOS memory circuits verify upset and latch-up immunity for two configurations to be in excess of 120 MeV cm(exp 2)/mg using a commercial, non-radiation hardened CMOS process. Test chips from three separate fabrication runs in two different process were evaluated.

  4. SEU mitigation strategies for SRAM-based FPGA

    NASA Astrophysics Data System (ADS)

    Luo, Pei; Zhang, Jian

    2011-08-01

    The type of Field Programmable Gate Arrays (FPGAs) technology and device family used in a design is a key factor for system reliability. Though antifuse-based FPGAs are widely used in aerospace because of their high reliability, current antifuse-based FPGA devices are expensive and leave no room for mistakes or changes since they are not reprogrammable. The substitute for antifuse-based FPGAs are needed in aerospace design, they should be both reprogrammable and highly reliable to Single Event Upset effects (SEUs). SRAM-based FPGAs are widely and systematically used in complex embedding digital systems both in a single chip industry and commercial applications. They are reprogrammable and high in density because of the smaller SRAM cells and logic structures. But the SRAM-based FPGAs are especially sensitive to cosmic radiation because the configuration information is stored in SRAM memory. The ideal FPGA for aerospace use should be high-density SRAM-based which is also insensitive to cosmic radiation induced SEUs. Therefore, in order to enable the use of SRAM-based FPGAs in safety critical applications, new techniques and strategies are essential to mitigate the SEU errors in such devices. In order to improve the reliability of SRAM-based FPGAs which are very sensitive to SEU errors, techniques such as reconfiguration and Triple Module Redundancy (TMR) are widely used in the aerospace electronic systems to mitigate the SEU and Single Event Functional Interrupt (SEFI) errors. Compared to reconfiguration and triplication, scrubbing and partial reconfiguration will utilize fewer or even no internal resources of FPGA. What's more, the detection and repair process can detect and correct SEU errors in configuration memories of the FPGA without affecting or interrupting the proper working of the system while reconfiguration would terminate the operation of the FPGA. This paper presents a payload system realized on Xilinx Virtex-4 FPGA which mitigates SEU effects in the

  5. Variation in SEU sensitivity of dose-imprinted CMOS SRAMs

    SciTech Connect

    Stassinopoulos, E.G. ); Brucker, G.S. ); Van Gunten, O. ); Kim, H.S. )

    1989-12-01

    This paper reports on an experimental study of dose-induced changes in SEU sensitivity of CMOS static RAMs. Two time-regimes were investigated following exposure of memories to Cobalt-60 gamma rays: the near term within a few hours after exposure, and the long term, after many days. Samples were irradiated both at room and at liquid nitrogen temperatures. The latter procedure was used in order to freeze-in the damage state until SEU measurements could be made before annealing would take place. Results show that memories damaged by dose are more sensitive to upsets by heavy ions. The induced changes are substantial: threshold linear energy transfer (LET) values decreased by as much as 46% and asymptotic cross sections increased by factors of 2 to 4 (unannealed samples).

  6. Variation in SEU sensitivity of dose-imprinted CMOS SRAMs

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Brucker, G. J.; Van Gunten, O.; Kim, H. S.

    1989-01-01

    The authors report on an experimental study of dose-induced changes in SEU (single-event-upset) sensitivity of CMOS static RAMs. Two time regimes were investigated following exposure of memories to cobalt-60 gamma rays: the near term, within a few hours after exposure, and the long term, after many days. Samples were irradiated both at room and at liquid nitrogen temperatures. The latter procedure was used in order to freeze in the damage state until SEU measurements could be made prior to annealing. Results show that memories damaged by dose are more sensitive to upsets by heavy ions. The induced changes are substantial: threshold linear energy transfer (LET) values decreased by as much as 46 percent and asymptotic cross sections increased by factors of two to four (unannealed samples).

  7. SEU tolerant computer based on the R3000

    SciTech Connect

    Kaschmitter, J.L.; Butner, D.B.; Shaeffer, D.L.; Colella, N.J.; McKnett, C.L.; Coakley, P.G.

    1993-01-30

    We have built and tested a Single Event Upset (SEU) tolerant computer (STC) based on the MIPS Inc. R3000 processor. Testing in a proton environment is ongoing. The design of this computer was postulated in previous work and based upon extensive radiation effects testing performed by Lawrence Livermore National Laboratory (LLNL). This computer is based entirely on commercially available parts. The purpose of these tests is to demonstrate the capability of using non-radiation hardened parts in an SEU environment, in this case Low Earth Orbit (LEO), with upset mitigation through fault tolerant hardware and software design methodologies. The hardware and software designs are described in detail, the test setup and test parameters are given and test results are presented.

  8. Methods for calculating SEU rates for bipolar and NMOS circuits

    NASA Astrophysics Data System (ADS)

    McNulty, P. J.; Abdel-Kader, W. G.; Bisgrove, J. M.

    1985-12-01

    Computer codes developed at Clarkson for simulating charge generation by proton-induced nuclear reactions in well-defined silicon microstructures can be used to calculate SEU rates for specific devices when the critical charge and the dimensions of all SEU sensitive junctions on the device are known, provided one can estimate the contribution from externally-generated charge which enters the sensitive junction by drift and diffusion. Calculations for two important bipolar devices, the AMD 2901B bit slice and the Fairchild 93L422 RAM, for which the dimensions of the sensitive volumes were estimated from available heavy-ion test data, have been found to be in agreement with experimental data. Circuit data for the Intel 2164A, an alpha sensitive dRAM, was provided by the manufacturer. Calculations based on crude assumptions regarding which nuclear recoils and which alphas trigger upsets in the 2164A were found to agree with experimental data.

  9. SEU design consideration for MESFETs on LT GaAs

    SciTech Connect

    Weatherford, T.R.; Radice, R.; Eskins, D.

    1997-12-01

    Computer simulation results are reported on transistor design and single-event charge collection modeling of metal-semiconductor field effect transistors (MESFETs) fabricated in the Vitesse H-GaAsIII{reg_sign} process on Low Temperature grown (LT) GaAs epitaxial layers. Tradeoffs in Single Event Upset (SEU) immunity and transistor design are discussed. Effects due to active loads and diffusion barriers are examined.

  10. Effects of ion damage on IBICC and SEU imaging

    SciTech Connect

    Sexton, F.W.; Horn, K.M.; Doyle, B.L.; Shaneyfelt, M.R.; Meisenheimer, T.L.

    1995-12-01

    The effect of displacement and ionizing dose damage on ion-beam-induced-charge-collection (IBICC) and single-event-upset (SEU) imaging are explored. IBICC imaging is not affected by ionizing dose damage, and its dependence on displacement damage is a complex function of the structure of the samples used in this study. Degradation of the IBICC signal is controlled by displacement damage that occurs at different rates in the heavily doped substrate and lightly doped epitaxial silicon layer, leading to a non-linear dependence of inverse degradation versus ion fluence. The effect of ion exposure on the electrical performance of complementary metal-oxide-semiconductor (CMOS) static random access memories (SRAMs) is solely related to ionizing dose effects in the transistor oxides. With SEU imaging, the authors found that an additional region became sensitive to upset with ion fluence probably as a result of ionizing dose effects on the restoring transistors. Finally, SEU during IBICC imaging resulted in charge collection from both p-drains of a memory cell. Implications of damage on the use of these microbeam techniques are discussed.

  11. Relationship between IBICC imaging and SEU in CMOS ICs

    SciTech Connect

    Sexton, F.W.; Horn, K.M.; Doyle, B.L. ); Laird, J.S.; Cholewa, M.; Saint, A.; Legge, G.J.F. . Micro Analytical Research Centre)

    1993-12-01

    Ion-beam-induced charge-collection imaging (IBICC) has been used to study the SEU mechanisms of the Sandia TA670 16K-bit SRAM. Quantitative charge-collection spectra from known regions of the memory cell have been derived with this technique. For 2.4-MeV He ions at normal incidence, charge collection depth for a reverse-biased p+ drain strike is estimated to be 4.8[+-]0.4 [mu]m. Heavy-ion strikes to the reverse-biased p-well result in nearly complete collection of deposited charge to a depth of 5.5[+-]0.5 [mu]m. A charge amplification effect in the n-on drain is identified and is due to either bipolar amplification or a shunt effect in the parasitic vertical npn bipolar transistor associated with the n+/n substrate, p-well, and n+ drain. This effect is present only when the n+ drain is at 0V bias. When coupled with previous SEU-imaging, these results strongly suggest that the dominant SEU mechanism in this SRAM is a heavy-ion strike to the n-on transistor drain.

  12. Single event upset (SEU) sensitivity dependence of linear integrated circuits (ICs) on bias conditions

    SciTech Connect

    Koga, R.; Penzin, S.H.; Crawford, K.B.; Crain, W.R.; Moss, S.C.; Pinkerton, S.D.; LaLumondiere, S.D.; Maher, M.C.

    1997-12-01

    The single event upset (SEU) sensitivity of certain types of linear microcircuits is strongly affected by bias conditions. For these devices, a model of upset mechanism and a method for SEU control have been suggested.

  13. S.E.U. experiments on an artificial neural network implemented by means of digital processors

    SciTech Connect

    Velazco, R.; Assoum, A.; Cheynet, P.; Olmos, M.

    1996-12-01

    The SEU sensitivity of an Artificial Neural Network intended to be used in space to detect protonic whistlers is investigated. The authors evaluate its behavior in the presence of SEU-like faults for a hardware implementation, associating a general purpose microprocessor to a dedicated neural processor. Experimental results (SEU simulations and heavy ion ground tests) show the robustness of this implementation.

  14. SEU cross sections derived from a diffusion analysis

    SciTech Connect

    Edmonds, L.D.

    1996-12-01

    A simple theoretical prediction of single-event upset (SEU) cross section versus linear energy transfer (LET) is derived from a diffusion analysis, and the result is compared to some real device curves. It was found that at least some real device curves show two regimes. One regime (high-LET) is characterized by a very good fit to the theoretical prediction, and the other (low-LET) is characterized by a very bad fit. The existence of a high-LET regime provides additional credibility for the increasingly popular postulate that diffusion has an important effect on the shape of the cross-sectional curve.

  15. Threshold LET for SEU induced by low energy ions

    SciTech Connect

    McNulty, P.J.; Roche, P.; Palau, J.M.; Gasiot, J.

    1999-12-01

    Simulations to determine the threshold LET as a function of the length of the ion track are consistent with there being two regions of charge collection. In the top layer which contains the depletion region all the charge generated is collected in time to upset the device. In the next layer, 10% to 20% of the charge generated is collected and contributes to upsetting the device. This second layer of partial charge collection may significantly impact the accuracy of SEU predictions involving low-energy neutrons and protons. A simple method of including this contribution in calculations is proposed.

  16. The SEU Figure of Merit and proton upset rate calculations

    SciTech Connect

    Petersen, E.L.

    1998-12-01

    This paper re-examines the use of the SEU Figure of Merit for heavy ion upset rate predictions. Slightly different orbit dependent rate coefficients are used for unhardened and hardened parts. The two different coefficients allow for the slight changes of LET spectra that occur due to the earth`s magnetic shielding. Accurate heavy ion predictions can be made for any orbit and any part. The authors show that the Figure of Merit can also be used to predict upset rate due to protons in the proton radiation belt. A proton rate coefficient is introduced to describe the upset likelihood in orbits with proton exposures. These results mean that a part susceptibility can be described by a single parameter, rather than the four Weibull parameters and two Bendel parameters used previously. The Figure of Merit completely describes a part`s SEU susceptibility and can be obtained from either proton or heavy ion measurements, eliminating the expense of making both types of experiment. The total upset rate for a part in a particular orbit can be calculated using its characteristic Figure of Merit and a single orbit specific rate coefficient, the sum of the heavy ion and proton rate coefficients.

  17. SEU characterization and design dependence of the SA3300 microprocessor

    SciTech Connect

    Sexton, F.W.; Treece, R.K.; Hass, K.J.; Hash, G.L.; Axness, C.L. ); Hughes, K.L. ); Buchner, S.P.; Kang, K. )

    1990-12-01

    The SEU vulnerability of the SA3300 16-bit microprocessor has been characterized, and the effects of two different design revisions on error rate have been explored. The authors have found that the threshold for upset depends on the data pattern written into the general purpose registers. With all bits in the general purpose registers set to logic one, a design with 2-{mu}m n- and p-channel transistor lengths had a threshold LET of 35 MeV-cm{sup 2}/mg at 25{degrees} C and 4.5 volt operation. With all zero's stored in the registers the upset threshold increased by more than a factor of two to 83 MeV- cm{sup 2}/mg. A second design revision, with 1.25-{mu}m and 1.75-{mu}m n- and p-channel transistor lengths, respectively, was more vulnerable to upset, but exhibited a smaller dependence on logic state.

  18. Charge collection and SEU from angled ion strikes

    SciTech Connect

    Dodd, P.E.; Shaneyfelt, M.R.; Sexton, F.W.

    1997-03-01

    Single event upsets (SEUs) are caused in semiconductor microcircuits when charge is deposited in a sensitive volume of the circuit by an incident energetic particle. Collection of this charge causes a loss of information stored at the struck circuit node. Sensitive regions of a microcircuit typically consist of reverse-biased junctions which efficiently collect deposited charge through the influence of drift fields. During laboratory SEU testing, angled ion strikes are often used to conveniently mimic normally incident particles of higher linear energy transfer (LET). This practice is based on ion pathlengths through a thin rectangular parallelepiped (RPP) sensitive volume. Specifically, the authors assume that an angled strike deposits 1/cos{theta} more charge in the sensitive volume, which in turn is assumed to lead to 1/cos{theta} more charge collection at the sensitive node, and an increase in the particle`s effective LET to 1/cos{theta} higher than at normal incidence.

  19. SEU mitigation for half-latches in xilinx virtex FPGAs.

    SciTech Connect

    Graham, P. S.; Caffrey, M. P.; Wirthlin, M. J.; Johnson, D. E.; Rollins, N.

    2003-01-01

    The performance, in-system reprogrammability, flexibility, and reduced costs of SRAM-based field-programmable gate arrays (FPGAs) make them very interesting for high-speed, on-orbit data processing, but, because the current generation of radiation-tolerant SRAM-based FPGAs are derived directly from COTS versions of the chips, their memory structures are still susceptible to single-event upsets (SEUs) . While previous papers have described the SEU characteristics and mitigation techniques for the configuration and user memory structures on the Xilinx Virtex family of FPGAs, we will concentrate on the effects of SEUs on 'half-latch' structures within the Virtex architecture, describe techniques for mitigating these effects, and provide new experimental data which illustrate the effectiveness of one of these mitigation techniques under proton radiation.

  20. Implications of angle of incidence in SEU testing of modern circuits

    SciTech Connect

    Reed, R.A.; McNulty, P.J.; Abdel-Kadar, W.G. . Dept. of Physics and Astronomy)

    1994-12-01

    Simulations show that ignoring the angular dependence of proton SEU cross sections produces errors in predictions of SEU rates in space. Moreover, they suggest that devices with thin sensitive volumes may upset to protons at grazing incidence despite high threshold LET values (> 80 MeV cm[sup 2]) at normal incidence. Incorporating angular effects in space predictions requires accurate knowledge of the dimensions of the sensitive volume associated with the SEU-sensitive junction, especially the thickness. A method is proposed for using proton SEU measurements at different angles and energies combined with simulations to determine the thickness of the sensitive volume and to test the reliability of the predictions.

  1. An SEU (single event upset) tolerant memory cell derived from fundamental studies of SEU mechanisms in SRAM (static random access memories)

    SciTech Connect

    Weaver, H.T.; Axness, C.L.; McBrayer, J.D.; Browning, J.S.; Fu, J.S.; Ochoa, A. Jr.; Koga, R.

    1987-01-01

    A new single event upset (SEU) hardening concept, an LRAM cell, is demonstrated theoretically and experimentally. As basis for the LRAM idea, techniques were developed to measure time constants for ion induced voltage transients in conventional static random access memories, SRAM. Time constants of 0.8 and 6.0 nsec were measured for transients following strikes at the n- and p-channel drains, respectively - primary areas of SEU sensitivity. These data are the first transient time measurements on full memory chips and the large difference is fundamental to the LRAM concept. Decoupling resistors in the LRAM are used only to protect against the short transient; longer persisting pulses are blocked by a voltage divider, a basically new concept for SEU protection. In such a design, smaller resistors provide SEU tolerance, allowing higher performance, hardened memories. Test structures of the new design exhibit SEU tolerance with resistors 5-to-10 times smaller than currently used in SRAM. Our advanced transport-plus-circuit numerical simulations of the SEU process predicted this result and account for the LRAM experiments, as well as a variety of experiments on conventional SRAM. 16 refs., 6 figs., 1 tab.

  2. SEU response of design- and resistor-hardened D-latches in the SA3300 microprocessor

    SciTech Connect

    Sexton, F.W.; Corbett, W.T.; Axness, C.L.; Wunsch, T.F.; Hughes, K.L.; Treece, R.K.; Hass, K.J.; Hash, G.L.; Shaneyfelt, M.R.

    1991-01-01

    The effectiveness of hardening the SA3300 against SEU using design and design-plus-resistor approaches is presented. The full performance and SEU tolerance requirements are met using R{sub fb} {le} 160 k{Omega}. Lumped-parameter circuit simulations are used to analyze results. 10 refs., 5 figs.

  3. Recent Results on SEU Hardening of SiGe HBT Logic Circuits

    NASA Technical Reports Server (NTRS)

    Krithivasan, Ramkumar; Marshall, Paul W.; Nayeem, Mustayeen; Sutton, Akil K.; Kuo, Wei-Min Lance; Haugerud, Becca M.; Najafizadeh, Laieh; Cressler, John D.; Carts, martin A.; Marshall, Cheryl J.

    2006-01-01

    A viewgraph presentation on SEU tolerant SiGe HBT technology is shown. The topics include: 1) Introduction; 2) TID and SEU in SiGe Technology; 3) RHBD Techniques; 4) Experiment; 5) Heavy-Ion Data and Analysis; and 6) Summary.

  4. Two CMOS memory cells suitable for the design of SEU-tolerant VLSI circuits

    SciTech Connect

    Velazco, R.; Bessot, D. ); Duzellier, S. ); Ecoffet, R. ); Koga, R. )

    1994-12-01

    Two new CMOS memory cells, called HIT cells, designed to be SEU-immune are presented. Compared to previously reported design hardened solutions, the HIT cells feature better electrical performances and consume less silicon area. SEU tests performed on a prototype chip prove the efficiency of the approach.

  5. SEU immunity: The effects of scaling on the peripheral circuits of SRAMs

    SciTech Connect

    Jacunski, L.; Doyle, S.; Jallice, D.; Haddad, N.; Scott, T. )

    1994-12-01

    Heavy ion testing on a scaled 256K SRAM has shown that SEU analysis of the peripheral circuits as well as the memory cell must be performed as circuits are scaled to smaller and smaller dimensions. This paper describes the SEU induce phenomena experienced by the scaled version of a previous 256K radiation hardened SRAM design, affected by circuits in the periphery.

  6. P-well or N-well CMOS technology for advanced SEU-hard SRAMs

    SciTech Connect

    Fu, J.S.

    1988-01-01

    The decoupling resistances required for SEU hardening CMOS SRAMs of the 2..mu..m p-well and n-well technologies are compared. An advanced device-plus-circuit simulator has been used to illuminate the underpinings of why one technology is intrinsically more SEU tolerant than the other. 3 refs., 5 figs.

  7. Measurements of SEU and total dose in geostationary orbit under normal and solar flare conditions

    SciTech Connect

    Adams, L.; Daly, E.J.; Harboe-Sorensen, R. ); Holmes-Siedle, A.G. ); Ward, A.K.; Bull, R.A. )

    1991-12-01

    The Meteosat-3 Radiation Effects Experiment includes two 256 Kbit SRAMs configured for SEU detection and a RADFET array for dose measurement. SEU rates and doses are enhanced during solar flares. In this paper two years of orbital data are compared with ground tests and prediction.

  8. Investigation of single-event upset (SEU) in an advanced bipolar process

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Secrest, Elaine C.; Berndt, Dale F.

    1988-01-01

    An extensive analytical and experimental study SEU in an advanced silicon bipolar process was made. The modeling used process and device parameters to model the SEU charge, collection, and circuit response derived from a special version of PISCES in cylindrical coordinates and SPICE, respectively. Data are reported for test cells of various sizes.

  9. Predictions and observations of SEU rates in space

    SciTech Connect

    Petersen, E.L.

    1997-12-01

    This paper summarizes the available data on the observation and prediction of SEU rates in space. It considers three questions: (1) How good can a prediction be? (2) How bad can a prediction be? (3) How does the quality of the prediction depend on the type of orbit? The paper considers one hundred and twenty-six reports of predicted and observed rates. These include updated predictions for the CRRES devices. The analysis then excludes solar particle events, single event burnout, cases with poor statistics, and cases that are essentially duplicates; leaving 77 comparisons. The heavy ion predictions based on the CREME environments and the proton predictions based on the AP8 environments are both very successful for their basic environments, but are less accurate for low earth orbits (LEO). The quality of the results depends on the use of the proper shielding around the part. The results appear consistent with suggested modifications in these environments based on recent space measurements. The methods that are used for upset rate predictions appear to be adequate for the current generation of devices.

  10. SEU-tolerant IQ detection algorithm for LLRF accelerator system

    NASA Astrophysics Data System (ADS)

    Grecki, M.

    2007-08-01

    High-energy accelerators use RF field to accelerate charged particles. Measurements of effective field parameters (amplitude and phase) are tasks of great importance in these facilities. The RF signal is downconverted in frequency but keeping the information about amplitude and phase and then sampled in ADC. One of the several tasks for LLRF control system is to estimate the amplitude and phase (or I and Q components) of the RF signal. These parameters are further used in the control algorithm. The XFEL accelerator will be built using a single-tunnel concept. Therefore electronic devices (including LLRF control system) will be exposed to ionizing radiation, particularly to a neutron flux generating SEUs in digital circuits. The algorithms implemented in FPGA/DSP should therefore be SEU-tolerant. This paper presents the application of the WCC method to obtain immunity of IQ detection algorithm to SEUs. The VHDL implementation of this algorithm in Xilinx Virtex II Pro FPGA is presented, together with results of simulation proving the algorithm suitability for systems operating in the presence of SEUs.

  11. Energy-resolved neutron SEU measurements from 22 to 160 MeV

    SciTech Connect

    Johansson, K.; Dyreklev, P.; Granbom, B.; Olsson, N.; Blomgren, J.; Renberg, P.U.

    1998-12-01

    The energy dependence of the neutron- induced single-event upset (NSEU) cross section for Static RAMs have been measured, using quasi-monoenergetic neutrons of five different energies from 22 to 160 MeV. The measured SEU cross sections were corrected for the low-energy neutron tail by an iterative folding procedure. A clear energy dependence has been found. The SEU rate has been compared both with results from testing with a neutron spallation spectrum up to 800 MeV and the measured SEU rate from In-Flight experiments at 10 km.

  12. Ion induced charge collection and SEU sensitivity of emitter coupled logic (ECL) devices

    SciTech Connect

    Koga, R.; Crain, W.R.; Hansel, S.J.; Crawford, K.B.; Kirshman, J.F.; Pinkerton, S.D.; Penzin, S.H.; Moss, S.C.; Maher, M.

    1995-12-01

    This paper presents single event upset (SEU) and latchup test results for selected Emitter Coupled Logic (ECL) microcircuits, including several types of low capacity SRAMs and other memory devices. The high speed of ECL memory devices makes them attractive for use in space applications. However, the emitter coupled transistor design increases susceptibility to radiation induced functional errors, especially SEU, because the transistors are not saturated, unlike the transistors in a CMOS device. Charge collection at the sensitive nodes in ECL memory elements differs accordingly. These differences are responsible, in part, for the heightened SEU vulnerability of ECL memory devices relative to their CMOS counterparts.

  13. Verification of a SEU model for advanced 1-micron CMOS structures using heavy ions

    NASA Technical Reports Server (NTRS)

    Cable, J. S.; Carter, J. R.; Witteles, A. A.

    1986-01-01

    Modeling and test results are reported for 1 micron CMOS circuits. Analytical predictions are correlated with experimental data, and sensitivities to process and design variations are discussed. Unique features involved in predicting the SEU performance of these devices are described. The results show that the critical charge for upset exhibits a strong dependence on pulse width for very fast devices, and upset predictions must factor in the pulse shape. Acceptable SEU error rates can be achieved for a 1 micron bulk CMOS process. A thin retrograde well provides complete SEU immunity for N channel hits at normal incidence angle. Source interconnect resistance can be important parameter in determining upset rates, and Cf-252 testing can be a valuable tool for cost-effective SEU testing.

  14. SEU response of an entire SRAM cell simulated as one contiguous three dimensional device domain

    SciTech Connect

    Roche, P.; Palau, J.M.; Bruguier, G.; Gasiot, J.; Belhaddad, K.; Ecoffet, R.

    1998-12-01

    The first SEU response of a complete 3-D SRAM cell is presented. This simulation method allows to verify the accuracy of the commonly used mixed-mode technique and to study coupling effects between different junctions of the cell.

  15. Upper bound SEU rate for devices in an isotropic or nonisotropic flux

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    1991-01-01

    A method for constructing upper bound estimates for device single event upset (SEU) rates is presented. A directional Heinrich flux, as a function of direction, must be known. A computer code, included, converts the directional Heinrich flux into an 'effective flux'. The effective flux provides a simple way to estimate upper bound SEU rates for devices with a known normal incident cross section versus LET curve.

  16. Upper-bound SEU rate for devices in an isotropic or nonisotropic flux

    SciTech Connect

    Edmonds, L.D.

    1991-08-01

    A method for constructing upper bound estimates for device single event upset (SEU) rates is presented. A directional Heinrich flux, as a function of direction, must be known. A computer code, included, converts the directional Heinrich flux into an 'effective flux'. The effective flux provides a simple way to estimate upper bound SEU rates for devices with a known normal incident cross section versus LET curve.

  17. Observation and prediction of SEU in Hitachi SRAMs in low altitude polar orbits

    SciTech Connect

    Harboe-Sorensen, R.; Daly, E.J.; Adams, L. ); Underwood, C.I. . Surrey Satellite Technology); Mueller, R. . Institut fuer Datenverarbeitungsanlagen)

    1993-12-01

    In-orbit SEU data from three microsatellites are separated into Galactic Cosmic Ray (GCR), South Atlantic Anomaly (SAA) and solar flare upsets. Heavy ion and proton testing of the same devices are reported and predictions using LET-dependent ion cross sections and a 2-parameter fit to proton cross section data are compared with in-flight data. SEU trends in memory devices from a single manufacturer, from 16 K-bit to 4 M-bit, are identified.

  18. SEU testing of a novel hardened register implemented using standard CMOS technology

    SciTech Connect

    Monnier, T.; Roche, F.M.; Cosculluela, J.; Velazco, R.

    1999-12-01

    A novel memory structure, designed to tolerate SEU perturbations, has been implemented in registers and tested. The design was completed using a standard submicron nonradiation hardened CMOS technology. This paper presents the results of heavy ions tests which evidence the noticeable improvement of the SEU-robustness with an increased LET threshold and reduced cross-section, without significant impact to die real estate, write time, or power consumption.

  19. Design and qualification of the SEU/TD Radiation Monitor chip

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.; Soli, George A.; Zamani, Nasser; Hicks, Kenneth A.

    1992-01-01

    This report describes the design, fabrication, and testing of the Single-Event Upset/Total Dose (SEU/TD) Radiation Monitor chip. The Radiation Monitor is scheduled to fly on the Mid-Course Space Experiment Satellite (MSX). The Radiation Monitor chip consists of a custom-designed 4-bit SRAM for heavy ion detection and three MOSFET's for monitoring total dose. In addition the Radiation Monitor chip was tested along with three diagnostic chips: the processor monitor and the reliability and fault chips. These chips revealed the quality of the CMOS fabrication process. The SEU/TD Radiation Monitor chip had an initial functional yield of 94.6 percent. Forty-three (43) SEU SRAM's and 14 Total Dose MOSFET's passed the hermeticity and final electrical tests and were delivered to LL.

  20. The Single Event Upset (SEU) response to 590 MeV protons

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Price, W. E.; Smith, L. S.; Soli, G. A.

    1984-01-01

    The presence of high-energy protons in cosmic rays, solar flares, and trapped radiation belts around Jupiter poses a threat to the Galileo project. Results of a test of 10 device types (including 1K RAM, 4-bit microP sequencer, 4-bit slice, 9-bit data register, 4-bit shift register, octal flip-flop, and 4-bit counter) exposed to 590 MeV protons at the Swiss Institute of Nuclear Research are presented to clarify the picture of SEU response to the high-energy proton environment of Jupiter. It is concluded that the data obtained should remove the concern that nuclear reaction products generated by protons external to the device can cause significant alteration in the device SEU response. The data also show only modest increases in SEU cross section as proton energies are increased up to the upper limits of energy for both the terrestrial and Jovian trapped proton belts.

  1. Study on FPGA SEU Mitigation for the Readout Electronics of DAMPE BGO Calorimeter in Space

    NASA Astrophysics Data System (ADS)

    Shen, Zhongtao; Feng, Changqing; Gao, Shanshan; Zhang, Deliang; Jiang, Di; Liu, Shubin; An, Qi

    2015-06-01

    The BGO calorimeter, which provides a wide measurement range of the primary cosmic ray spectrum, is a key sub-detector of Dark Matter Particle Explorer (DAMPE). The readout electronics of calorimeter consists of 16 pieces of Actel ProASIC Plus FLASH-based FPGA, of which the design-level flip-flops and embedded block RAMs are single event upset (SEU) sensitive in the harsh space environment. Therefore to comply with radiation hardness assurance (RHA), SEU mitigation methods, including partial triple modular redundancy (TMR), CRC checksum, and multi-domain reset are analyzed and tested by the heavy-ion beam test. Composed of multi-level redundancy, a FPGA design with the characteristics of SEU tolerance and low resource consumption is implemented for the readout electronics.

  2. SEU rate prediction and measurement of GaAs SRAMs onboard the CRRES satellite

    SciTech Connect

    Weatherford, T.R.; McDonald, P.T. Naval Research Lab., Washington, DC ); Campbell, A.B.; Langworthy, J.B. )

    1993-12-01

    The Combined Release and Radiation Effects Satellite (CRRES) launched in July of 1990 included experiments to study effects of Single Event Upset (SEU) on various microelectronic ICs. The MicroElectronics Package (MEP) subsection of the satellite experiments monitored upset rates on 65 devices over a 15 month period. One of the purposes of the SEU experiments was to determine if the soft error modeling techniques were of sufficient accuracy to predict error rates, and if not, to determine where the deficiencies existed. An analysis is presented on SPICE predicted, SEU ground tested, and CRRES observed heavy ion and proton soft error rates of GaAs SRAMs. Upset rates overestimated the susceptibility of the GaAs SRAMs. Differences are accounted to several factors.

  3. Empirical modeling of Single-Event Upset (SEU) in NMOS depletion-mode-load static RAM (SRAM) chips

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.; Smith, S. L.; Atwood, G. E.

    1986-01-01

    A detailed experimental investigation of single-event upset (SEU) in static RAM (SRAM) chips fabricated using a family of high-performance NMOS (HMOS) depletion-mode-load process technologies, has been done. Empirical SEU models have been developed with the aid of heavy-ion data obtained with a three-stage tandem van de Graaff accelerator. The results of this work demonstrate a method by which SEU may be empirically modeled in NMOS integrated circuits.

  4. Simulation and research on a 4T-cell based duplication redundancy SRAM for SEU radiation hardening

    NASA Astrophysics Data System (ADS)

    Xinhong, Hong; Liyang, Pan; Wendi, Zhang; Dongmei, Ji; Dong, Wu; Chen, Shen; Jun, Xu

    2015-11-01

    A novel 4T-cell based duplication redundancy SRAM is proposed for SEU radiation hardening applications. The memory cell is designed with a 65-nm low leakage process; the operation principle and the SEU radiation hardening mechanism are discussed in detail. The SEE characteristics and failure mechanism are also studied with a 3-D device simulator. The results show that the proposed SRAM structure exhibits high SEU hardening performance with a small cell size.

  5. SPICE analysis of the SEU sensitivity of a fully depleted SOI CMOS SRAM cell

    SciTech Connect

    Alles, M.L. )

    1994-12-01

    Fully depleted silicon-on-insulator (SOI) technologies are of interest for commercial applications as well as for use in harsh (radiation-intensive) environments. In both types of application, effects of charged particles (single-event effects) are of concern. Here, SPICE analysis of SEU sensitivity of a 6-T SRAM cell using commercially-representative fully depleted SOI CMOS technology parameters indicates that reduction of the minority carrier lifetime (parasitic bipolar gain) and use of thinner silicon can significantly reduce SEU sensitivity.

  6. Simulation of SEU Cross-sections using MRED under Conditions of Limited Device Information

    NASA Technical Reports Server (NTRS)

    Lauenstein, J. M.; Reed, R. A.; Weller, R. A.; Mendenhall, M. H.; Warren, K. M.; Pellish, J. A.; Schrimpf, R. D.; Sierawski, B. D.; Massengill, L. W.; Dodd, P. E.; Shaneyfelt, M. R.; Felix, J. A.; Schwank, J. R.

    2007-01-01

    This viewgraph presentation reviews the simulation of Single Event Upset (SEU) cross sections using the membrane electrode assembly (MEA) resistance and electrode diffusion (MRED) tool using "Best guess" assumptions about the process and geometry, and direct ionization, low-energy beam test results. This work will also simulate SEU cross-sections including angular and high energy responses and compare the simulated results with beam test data for the validation of the model. Using MRED, we produced a reasonably accurate upset response model of a low-critical charge SRAM without detailed information about the circuit, device geometry, or fabrication process

  7. Single-Event Upset (SEU) model verification and threshold determination using heavy ions in a bipolar static RAM

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.; Thieberger, P.; Wegner, H. E.

    1985-01-01

    Single-Event Upset (SEU) response of a bipolar low-power Schottky-diode-clamped TTL static RAM has been observed using Br ions in the 100-240 MeV energy range and O ions in the 20-100 MeV range. These data complete the experimental verification of circuit-simulation SEU modeling for this device. The threshold for onset of SEU has been observed by the variation of energy, ion species and angle of incidence. The results obtained from the computer circuit-simulation modeling and experimental model verification demonstrate a viable methodology for modeling SEU in bipolar integrated circuits.

  8. SEU of complementary GaAs static RAMs due to heavy ions

    NASA Technical Reports Server (NTRS)

    Zuleeg, R.; Notthoff, J. K.; Nichols, D. K.

    1984-01-01

    The first measurement of single event upset (SEU) for complementary GaAs static RAMs caused by heavy ions is reported. Upset cross-sections of the circuits for 28 MeV oxygen ions are reported as well as the linear energy transfer (LET) threshold established by using 170 MeV oxygen ions at various angles of beam incidence.

  9. SEU critical charge and sensitive area in a submicron CMOS technology

    SciTech Connect

    Detcheverry, C.; Dachs, C.; Lorfevre, E.; Sudre, C.; Bruguier, G.; Palau, J.M.; Gasiot, J.; Ecoffet, R.

    1997-12-01

    This work presents SEU phenomena in advanced SRAM memory cells. Using mixed-mode simulation, the effects of scaling on the notions of sensitive area and critical charge is shown. Specifically, the authors quantify the influence of parasitic bipolar action in cells fabricated in a submicron technology.

  10. A method to compute SEU fault probabilities in memory arrays with error correction

    NASA Technical Reports Server (NTRS)

    Gercek, Gokhan

    1994-01-01

    With the increasing packing densities in VLSI technology, Single Event Upsets (SEU) due to cosmic radiations are becoming more of a critical issue in the design of space avionics systems. In this paper, a method is introduced to compute the fault (mishap) probability for a computer memory of size M words. It is assumed that a Hamming code is used for each word to provide single error correction. It is also assumed that every time a memory location is read, single errors are corrected. Memory is read randomly whose distribution is assumed to be known. In such a scenario, a mishap is defined as two SEU's corrupting the same memory location prior to a read. The paper introduces a method to compute the overall mishap probability for the entire memory for a mission duration of T hours.

  11. SEU hardened memory cells for a CCSDS Reed-Solomon encoder

    NASA Technical Reports Server (NTRS)

    Whitaker, Sterling; Canaris, John; Liu, Kathy

    1991-01-01

    A design technique to harden CMOS memory circuits against single event upset (SEU) in the space environment is reported. The design technique provides a recovery mechanism which is independent of the shape of the upsetting event. A RAM cell and flip-flop design are presented to demonstrate the method. The flip-flop was used in the control circuitry for a Reed-Solomon encoder designed for the Space Station and Explorer platforms.

  12. Altitude and latitude variations in avionics SEU and atmospheric neutron flux

    SciTech Connect

    Normand, E.; Baker, T.J. )

    1993-12-01

    The direct cause of single event upsets in SRAMs at aircraft altitudes by the atmospheric neutrons has previously been documented. The variation of the in-flight SEU rate with latitude is demonstrated by new data over a wide range of geographical locations. New measurements and models of the atmospheric neutron flux are also evaluated to characterize its variation with altitude, latitude and solar activity.

  13. Single-event upset (SEU) in a DRAM with on-chip error correction

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Schwartz, H. R.; Watson, R. K.; Hasnain, Z.; Nevile, L. R.

    1987-01-01

    Results are given of SEU measurements on 256K dynamic RAMs with on-chip error correction. They are claimed to be the first ever reported. A (12/8) Hamming error-correcting code was incorporated in the layout. Physical separation of the bits in each code word was used to guard against multiple bits being disrupted in any given word. Significant reduction in observed errors is reported.

  14. A new approach for the prediction of the neutron-induced SEU rate

    SciTech Connect

    Vial, C.; Palau, J.M.; Gasiot, J.; Calvet, M.C.; Fourtine, S.

    1998-12-01

    A new approach for SEU rate prediction in components submitted to neutron environment is presented. The method aims to take into account the characteristics of the secondary particles in terms of electrical effect. So, in addition to the critical energy/charge criterion generally used until now, two criteria are tentatively proposed: a critical LET and a limited distance in which energy must be deposited. The starting point of each computation is a common neutron-silicon interaction database.

  15. Ion Beam Induced Charge Collection (IBICC) microscopy of ICs: Relation to Single Event Upsets (SEU)

    SciTech Connect

    Horn, K.M.; Doyle, B.L.; Sexton, F.W. ); Laird, J.S.; Saint, A.; Cholewa, M.; Legge, G.J.F. . Micro Analytical Research Center )

    1992-01-01

    Single Event Upset (SEU) Imaging is a new diagnostic technique recently developed using Sandia's nuclear microprobe. This technique directly images, with micron resolution, those regions within an integrated circuit which are susceptible to ion-induced malfunctions. Such malfunctions are an increasing threat to space-based systems which make use of current generation IC designs. A complimentary technique to SEU-Imaging involves measurement of the charge collection volumes within integrated circuits; charge collection is the underlying physical process responsible for single event phenomena. This technique, which we term. Ion Beam Induced Charge Collection (IBICC) has been used here and elsewhere to generate micron resolution maps of the charge collection response of integrated circuits. In this paper, we demonstrate the utility of combining the SEU-Imaging and IBICC techniques in order to gain a better understanding of single event upset phenomena. High resolution IBICC images are used to extract more detailed information from charge collection spectra than that obtained from conventional broad-area ion exposures, such as from radioactive sources. Lastly, we will comment on the applications for IBICC as a replacement of Electron Beam Induced Conduction/Current (EBIC) measurements. As reductions in circuit feature size continue in the sub-micron regime, IBICC could certainly prove to be a technologically valuable replacement for EBlC and an important business opportunity for all nuclear microprobe facilities. 12 ref.

  16. Ion Beam Induced Charge Collection (IBICC) microscopy of ICs: Relation to Single Event Upsets (SEU)

    SciTech Connect

    Horn, K.M.; Doyle, B.L.; Sexton, F.W.; Laird, J.S.; Saint, A.; Cholewa, M.; Legge, G.J.F.

    1992-07-01

    Single Event Upset (SEU) Imaging is a new diagnostic technique recently developed using Sandia`s nuclear microprobe. This technique directly images, with micron resolution, those regions within an integrated circuit which are susceptible to ion-induced malfunctions. Such malfunctions are an increasing threat to space-based systems which make use of current generation IC designs. A complimentary technique to SEU-Imaging involves measurement of the charge collection volumes within integrated circuits; charge collection is the underlying physical process responsible for single event phenomena. This technique, which we term. Ion Beam Induced Charge Collection (IBICC) has been used here and elsewhere to generate micron resolution maps of the charge collection response of integrated circuits. In this paper, we demonstrate the utility of combining the SEU-Imaging and IBICC techniques in order to gain a better understanding of single event upset phenomena. High resolution IBICC images are used to extract more detailed information from charge collection spectra than that obtained from conventional broad-area ion exposures, such as from radioactive sources. Lastly, we will comment on the applications for IBICC as a replacement of Electron Beam Induced Conduction/Current (EBIC) measurements. As reductions in circuit feature size continue in the sub-micron regime, IBICC could certainly prove to be a technologically valuable replacement for EBlC and an important business opportunity for all nuclear microprobe facilities. 12 ref.

  17. SEU-hardened silicon bipolar and GaAs MESFET SRAM cells using local redundancy techniques

    SciTech Connect

    Hauser, J.R. )

    1992-02-01

    Silicon bipolar and GaAs FET SRAM's have proven to be more difficult to harden with respect to single-event upset mechanisms than have silicon CMOS SRAM's. This is a fundamental property of bipolar and JFET or MESFET device technologies which do not have a high-impedance, nonactive isolation between the control electrode and the current or voltage being controlled. All SEU circuit level hardening techniques applied at the local level must use some type of information storage redundancy so that information loss on one node due to an SEU event can be recovered from information stored elsewhere in the cell. In CMOS technologies, this can be achieved by the use of simple cross-coupling resistors, whereas in bipolar and FET technologies, no such simple approach is possible. Several approaches to the use of local redundancy in bipolar and FET technologies are discussed in this paper. At the expense of increased cell complexity and increased power consumption and write time, several approaches are capable of providing complete SEU hardness at the local cell level.

  18. Assessing the SEU resistance of CMOS latches using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Blaes, B.; Nixon, R.

    1990-01-01

    The importance of Cosmic Rays on the performance of integrated circuits (IC's) in a space environment is evident in the upset rate of the Tracking and Data Relay Satellite (TDRS) launched in Apr. 1983. This satellite experiences a single-event-upset (SEU) per day which must be corrected from the ground. Such experience caused a redesign of the Galileo spacecraft with SEU resistant IC's. The solution to the SEU problem continues to be important as the complexity of spacecraft grows, the feature size of IC's decreases, and as space systems are designed with circuits fabricated at non-radiation hardened foundries. This paper describes an approach for verifying the susceptibility of CMOS latches to heavy-ion induced state changes. The approach utilizes alpha particles to induce the upsets in test circuits. These test circuits are standard cells that have offset voltages which sensitize the circuits to upsets. These results are then used to calculate the upsetability at operating voltages. In this study results are presented for the alpha particle upset of a six-transistor static random access memory (SRAM) cell. Then a methodology is described for the analysis of a standard-cell inverter latch.

  19. Experimental evidence for a new single-event upset (SEU) mode in a CMOS SRAM obtained from model verification

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.; Lo, R. Y.

    1987-01-01

    Modeling of SEU has been done in a CMOS static RAM containing 1-micron-channel-length transistors fabricated from a p-well epilayer process using both circuit-simulation and numerical-simulation techniques. The modeling results have been experimentally verified with the aid of heavy-ion beams obtained from a three-stage tandem van de Graaff accelerator. Experimental evidence for a novel SEU mode in an ON n-channel device is presented.

  20. Area overhead analysis of SEF: A design methodology for tolerating SEU

    SciTech Connect

    Blaquiere, Y.; Savaria, Y.

    1987-12-01

    Soft-Error filtering (SEF) is a design methodology proposed recently for implementing machines tolerant to SEU. This paper deals mainly with the evaluation and the reduction of the area overhead brought by SEF. A new shift register filtering latch configuration is proposed. The use of this latch, optimized for minimum area, reduces the area overhead by a factor of 2.6, when compared with latches optimized for time performance. A detailed analysis of the area overhead with SEF implemented on two relatively complex machines produced the following results: a SEF version of the 6800 microprocessor would require an area overhead varying between 12% and 69% depending on the SEF latch used and, a SEF version of the RISCII microprocessor would result in a 38.8% area overhead. An analysis of the cost of implementing the Hamming error correcting code on a register array is presented and this cost is compared with that of implementing SEU tolerance directly with SEF. Finally, a hybrid approach is proposed where a large register array is protected by an error correcting code whereas the isolated latches are replaced by filtering latches. This hybrid approach reduces the area overhead to 18.8% for the RISCII architecture.

  1. The contribution of low-energy protons to the total on-orbit SEU rate

    DOE PAGESBeta

    Dodds, Nathaniel Anson; Martinez, Marino J.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, Jeffrey D.; Lee, David S.; Swanson, Scot E.; Bhuva, B. L.; Warren, K. M.; et al

    2015-11-10

    Low- and high-energy proton experimental data and error rate predictions are presented for many bulk Si and SOI circuits from the 20-90 nm technology nodes to quantify how much low-energy protons (LEPs) can contribute to the total on-orbit single-event upset (SEU) rate. Every effort was made to predict LEP error rates that are conservatively high; even secondary protons generated in the spacecraft shielding have been included in the analysis. Across all the environments and circuits investigated, and when operating within 10% of the nominal operating voltage, LEPs were found to increase the total SEU rate to up to 4.3 timesmore » as high as it would have been in the absence of LEPs. Therefore, the best approach to account for LEP effects may be to calculate the total error rate from high-energy protons and heavy ions, and then multiply it by a safety margin of 5. If that error rate can be tolerated then our findings suggest that it is justified to waive LEP tests in certain situations. Trends were observed in the LEP angular responses of the circuits tested. As a result, grazing angles were the worst case for the SOI circuits, whereas the worst-case angle was at or near normal incidence for the bulk circuits.« less

  2. The contribution of low-energy protons to the total on-orbit SEU rate

    SciTech Connect

    Dodds, Nathaniel Anson; Martinez, Marino J.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, Jeffrey D.; Lee, David S.; Swanson, Scot E.; Bhuva, B. L.; Warren, K. M.; Reed, R. A.; Trippe, J.; Sierawski, B. D.; Weller, R. A.; Mahatme, N.; Gaspard, N.; Assis, T.; Austin, R.; Massengill, L. M.; Swift, G.; Wirthlin, M.; Cannon, M.; Liu, R.; Chen, L.; Kelly, A. T.; Marshall, P.; Trinczek, M.; Blackmore, E. W.; Wen, S. -J.; Wong, R.; Narasimham, B.; Pellish, J. A.; Puchner, H.; Weeden-Wright, S. L.

    2015-11-10

    Low- and high-energy proton experimental data and error rate predictions are presented for many bulk Si and SOI circuits from the 20-90 nm technology nodes to quantify how much low-energy protons (LEPs) can contribute to the total on-orbit single-event upset (SEU) rate. Every effort was made to predict LEP error rates that are conservatively high; even secondary protons generated in the spacecraft shielding have been included in the analysis. Across all the environments and circuits investigated, and when operating within 10% of the nominal operating voltage, LEPs were found to increase the total SEU rate to up to 4.3 times as high as it would have been in the absence of LEPs. Therefore, the best approach to account for LEP effects may be to calculate the total error rate from high-energy protons and heavy ions, and then multiply it by a safety margin of 5. If that error rate can be tolerated then our findings suggest that it is justified to waive LEP tests in certain situations. Trends were observed in the LEP angular responses of the circuits tested. As a result, grazing angles were the worst case for the SOI circuits, whereas the worst-case angle was at or near normal incidence for the bulk circuits.

  3. Measurement of SEU thresholds and cross sections at fixed incidence angles

    SciTech Connect

    Criswell, T.L.; Oberg, D.L.; Wert, J.L.; Measel, P.R.; Wilson, W.E.

    1987-12-01

    Current SEU testing and analysis techniques have as basic assumptions that the charge deposited at a junction depends linearly on the linear energy transfer (LET) of the ion and the pathlength of the ion through an imagined parallelepiped that represents the depletion region. This study tests these assumptions for two bipolar parts, AMD 27LS00 and Fairchild 93L422, by irradiating at fixed angles while varying the LET of two ion species. It was found that the 27LS00 shows a pronounced ion species dependence, and may show a deviation of deposited charge from the usual inverse-cosine times a fixed depletion depth, while the 93L422 exhibited the expected inverse-cosine dependence and no ion species dependence.

  4. The impact of software and CAE tools on SEU in field programmable gate arrays

    SciTech Connect

    Katz, R.; Wang, J.; McCollum, J.; Cronquist, B.

    1999-12-01

    Field programmable gate array (FPGA) devices, heavily used in spacecraft electronics, have grown substantially in size over the past few years, causing designers to work at a higher conceptual level, with computer aided engineering (CAE) tools synthesizing and optimizing the logic from a description. It is shown that the use of commercial-off-the-shelf (COTS) CAE tools can produce unreliable circuit designs when the device is used in a radiation environment and a flip-flop is upset. At a lower level, software can be used to improve the SEU performance of a flip-flop, exploiting the configurable nature of FPGA technology and on-chip delay, parasitic resistive, and capacitive circuit elements.

  5. Using Pipelined XNOR Logic to Reduce SEU Risks in State Machines

    NASA Technical Reports Server (NTRS)

    Le, Martin; Zheng, Xin; Katanyoutant, Sunant

    2008-01-01

    Single-event upsets (SEUs) pose great threats to avionic systems state machine control logic, which are frequently used to control sequence of events and to qualify protocols. The risks of SEUs manifest in two ways: (a) the state machine s state information is changed, causing the state machine to unexpectedly transition to another state; (b) due to the asynchronous nature of SEU, the state machine's state registers become metastable, consequently causing any combinational logic associated with the metastable registers to malfunction temporarily. Effect (a) can be mitigated with methods such as triplemodular redundancy (TMR). However, effect (b) cannot be eliminated and can degrade the effectiveness of any mitigation method of effect (a). Although there is no way to completely eliminate the risk of SEU-induced errors, the risk can be made very small by use of a combination of very fast state-machine logic and error-detection logic. Therefore, one goal of two main elements of the present method is to design the fastest state-machine logic circuitry by basing it on the fastest generic state-machine design, which is that of a one-hot state machine. The other of the two main design elements is to design fast error-detection logic circuitry and to optimize it for implementation in a field-programmable gate array (FPGA) architecture: In the resulting design, the one-hot state machine is fitted with a multiple-input XNOR gate for detection of illegal states. The XNOR gate is implemented with lookup tables and with pipelines for high speed. In this method, the task of designing all the logic must be performed manually because no currently available logic synthesis software tool can produce optimal solutions of design problems of this type. However, some assistance is provided by a script, written for this purpose in the Python language (an object-oriented interpretive computer language) to automatically generate hardware description language (HDL) code from state

  6. Experimental determination of single-event upset (SEU) as a function of collected charge in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Malone, C. J.; Smith, L. S.

    1984-01-01

    Single-Event Upset (SEU) in bipolar integrated circuits (ICs) is caused by charge collection from ion tracks in various regions of a bipolar transistor. This paper presents experimental data which have been obtained wherein the range-energy characteristics of heavy ions (Br) have been utilized to determine the cross section for soft-error generation as a function of charge collected from single-particle tracks which penetrate a bipolar static RAM. The results of this work provide a basis for the experimental verification of circuit-simulation SEU modeling in bipolar ICs.

  7. Validity of Using a Fixed Analog Input for Evaluating the SEU Sensitivity of a Flash Analog-to-Digital Converter

    NASA Technical Reports Server (NTRS)

    Buchner, Stephen; Campbell, Arthur B.; Sternberg, Andrew; Massengill, Lloyd; McMorrow, Dale; Dyer, Clive

    2003-01-01

    The SEU rate in a flash ADC (AD9058) on board a space experiment varied by more than an order of magnitude, depending on the input. A pulsed laser aided in elucidating the reasons, which were found to be the result of the unique design of the AD9058.

  8. Comparison between observed and theoretically determined SEU rates in the Texas TMS4416 DRAMs on-board the UoSAT-2 micro-satellite

    SciTech Connect

    Oldfield, M.K.; Underwood, C.I.

    1998-06-01

    A single event upset (SEU) prediction tool, PRISM (Protons in Semi-conductor Materials) has been used to model the proton induced upset rate in Texas TMS4416 DRAMs on-board the UoSAT-2 micro-satellite. Good agreement is found between the observed and theoretically determined SEU and MBU (multiple-bit upset) rates for this device.

  9. Hardening techniques to counter cumulated dose on SEU and SEL in space environment

    NASA Astrophysics Data System (ADS)

    Bessot, D.

    1991-04-01

    The total dose effect of space particles acting on semiconductor devices by creating charges in the silicon and the silicon dioxide and by creating displacement damage, from the beginning of charge creation to the parameter shifts, is reviewed. Detailed investigations on three phenomena are described: the Single Event Upset (SEU) caused by the heavy ions and the protons which come from the galactic rays and resulting in a transient upset of a critical node voltage; the Single Event Latchup (SEL) caused by the galactic and solar flares cosmic heavy ions and which may be destructive; the displacement damage induced by high energy trapped protons lying in the radiation belts (Van Allen), which involves the creation of permanent defaults over time which act on the mean carrier life, the carrier mobility and the resistivity, thus increasing either generation or recombination rate. These studies allow definition of techniques for the design and fabrication of circuits that are the least vulnerable to radiation. Simulation and test give guarantee that these new techniques assure the margins of the desired specification in space applications.

  10. Pressure/temperature sensitive inorganic phosphors. [La/sub 2/O/sub 2/S:Eu

    SciTech Connect

    Seals, W.O.; Offen, H.W.; Turley, W.D.

    1987-01-01

    Kistler gauges are presently used to monitor pressures generated in various types of experimental tests. When a one-gallon container of stores liquid propellant was impacted by a shaped charge, hydraulic pressures in excess of 100,000 psi were produced. This destroyed the gauges. A class of inorganic phosphors, including rare earth-doped lanthanum oxysulfide (La/sub 2/O/sub 2/S:Eu) and yittrium oxysulfide (Y/sub 2/O/sub 2/S:Eu), show spectral emission characteristics that are strongly pressure dependent. The intensity of the emission lines and fluorescence decay time if individual emission lines show pressure dependence in the range of several kbar to greater than 100 kbar. These properties suggest that these phosphors could be applied as remotely operated pressure transducers. In addition phosphors show temperature dependence. This paper discusses the potential of inorganic phosphors to measure high pressure and also examines temperature effects. 5 refs., 7 figs

  11. IBM powerPC 405 SEU mitigation using processor voting techniques in Xilinx Virtex-I1 pro FPGA

    NASA Technical Reports Server (NTRS)

    Wang, Mandy W.; Bolotin, Gary S.

    2004-01-01

    Not until recently, Xilinx has developed a new field programmable gate array (FPGA) device family, Virtex-I1 Pro. In this single device, not only dies it have density logic cells (3K to125K), gigabit connectivity, on chip memory, digital clock management, but also it can have up to four IBM PowerPC 405 Processor hard cores, running up to 400MHz and 633 Mbps. To utilize this cutting edge device in space applications, a few Single Event Upset (SEU) mitigation techniques need to be implemented to a design for the device. At Jet Propulsion Laboratory (JPL), we have successfully demonstrated the feasibility of running multiple processors running in a lock step fashion to accomplish SEU mitigation and fault tolerance.

  12. Synthesis of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres via homogeneous precipitation route

    NASA Astrophysics Data System (ADS)

    Ai, Peng-Fei; Liu, Ying-Liang; Xiao, Li-Yuan; Wang, Hou-Jin; Meng, Jian-Xin

    2010-06-01

    A phosphorescent material in the form of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres was prepared by homogeneous precipitation using monodispersed carbon spheres as hard templates. Y2O3:Eu3+ hollow microspheres were first synthesized to serve as the precursor. Y2O2S:Eu3+, Mg2+, Ti4+ powders were obtained by calcinating the precursor in a CS2 atmosphere. The crystal structure, morphology and optical properties of the composites were characterized. X-ray diffraction measurements confirmed the purity of the Y2O2S phase. Electron microscopy observations revealed that the Y2O2S:Eu3+, Mg2+, Ti4+ particles inherited the hollow spherical shape from the precursor after being calcined in a CS2 atmosphere and that they had a diameter of 350-450 nm and a wall thickness of about 50-80 nm. After ultraviolet radiation at 265 or 325 nm for 5 min, the particles emitted strong red long-lifetime phosphorescence originating from Eu3+ ions. This phosphorescence is associated with the trapping of charge carriers by Ti4+ and Mg2+ ions.

  13. A new approach to the analysis of SEU and SEL data to obtain the sensitive volume thickness

    SciTech Connect

    Barak, J.; Levinson, J.; Akkerman, A.; Zentner, A.; David, D.; Even, O.; Lifshitz, Y.; Hass, M.; Victoria, M.

    1996-06-01

    It is proposed to use short-range ions (along with long-range ions) to obtain the thickness of the sensitive volume, d, and the SEU and SEL cross sections vs the energy deposited in this volume, {sigma}{sub ion}({var_epsilon}). These {sigma}{sub ion}({var_epsilon}) and d can be used for calculating the proton induced cross sections {sigma}{sub p}. A study of HM65162 demonstrates this method. The calculated {sigma}{sub p} is in good agreement with the experimental {sigma}{sub p}.

  14. A simple algorithm for predicting proton SEU rates in space compared to the rates measured on the CRRES satellite

    SciTech Connect

    Reed, R.A.; McNulty, P.J.; Beauvais, W.J.; Abdel-Kader, W.G. . Dept. of Physics and Astronomy); Stassinopoulos, E.G.; Barth, J.C.L. )

    1994-12-01

    A new simulation code, the Clemson Omnidirectional Spallation Model for Interaction in Circuits (COSMIC), is described and its predictions agree with SEU data from four devices flown as part of the microelectronics package experiment on the CRRES satellite. The code uses CUPID for determining the energy depositions in the sensitive volumes; it allows proton exposures with arbitrary angles of incidence including random omnidirectional exposure; and the user specifies the thickness of shielding on six sides of the sensitive volume. COSMIC is used as part of an algorithm developed to predict the rate proton induced single event upsets occur in the space radiation environment given by AP-8. In testing the algorithm, the position coordinates are taken from the satellite's ephemeris data, but calculations based on position coordinates from orbital codes were also in agreement with the measured values.

  15. Tree Diversity and Dynamics of the Forest of Seu Nico, Viçosa, Minas Gerais, Brazil

    PubMed Central

    Leyh, Werner; Meira-Neto, João A.A.

    2015-01-01

    Abstract Background To understand future changes in community composition due to global changes, the knowledge about forest community dynamics is of crucial importance. To improve our understanding about processes and patterns involved in maintaining species rich Neotropical ecosystems, we provide here a dataset from the one hectare Forest of Seu Nico (FSN) Dynamics Plot from Southeastern Brazil. New information We report diameter at breast height, basal area and height measurements of 2868 trees and treelets identified from two census spanning over a nine-year period. Furthermore, soil properties and understory light availability of all 100 10 x 10m subplots from the one hectare FSN Dynamics Plot during the second census are given. PMID:26312053

  16. SEU measurements using /sup 252/CF fission particles, on CMOS static RAMS, subjected to a continuous period of low dose rate /sup 60/CO irradiation

    SciTech Connect

    Sanderson, T.K.; Mapper, D.; Stephen, J.H.; Farren, J.; Adams, L.; Harboe-Sorensen, R.

    1987-12-01

    SEU measurements have been made on a number of CMOS static RAMs over a period of eight months while they were being continuously irradiated with /sup 60/Co gamma rays. The results are discussed and compared with those of other workers using different methods.

  17. Validity of Using a Fixed Analog Input for Evaluating the SEU Sensitivity of a Flash Analog-to-Digita1 Converter

    NASA Technical Reports Server (NTRS)

    Buchner, Stephen; Campbell, Arthur; Sternberg, Andrew; Massengill, Lloyd; McMorrow, Dale; Dyer, Clive

    2003-01-01

    The SEU rate in a flash ADC (AD9058) on board a space experiment varied by more than an order of magnitude, depending on the input. A pulsed laser aided in elucidating the reasons, which were found to be the result of the unique design of the AD9058.

  18. Evaluation of transuranium isotopes inventory for Candu/ACR standard and SEU spent fuel and the possibility to transmute them

    SciTech Connect

    Ghizdeanu, Elena Nineta; Pavelescu, Alexandru; Balaceanu, Victoria

    2007-07-01

    Available in abstract form only. Full text of publication follows: The main disadvantage of nuclear energy is the quantity of long lived radioactive waste produced in a NPP. Transmutation could be one of the solutions to reduce it. Waste transmutation will require a suitable deployment of techniques for spent fuel reprocessing. At present, reprocessing is done by aqueous methods that are very efficient for Pu separation (up to 99.9%). For transmutation applications, new partitioning processes must be developed for minor actinides separation from the high level waste. Although these processes are still very much at the research stage, industrial scale-up will result in the deployment of new, more specific separation techniques for transmutation applications. Partitioning and Transmutation (P and T) techniques could contribute to reduce the radioactive inventory and its associated radio-toxicity. Scientists are looking for ways to drastically reduce both the mass and the radio-toxicity of the nuclear waste to be stored in a deep geological repository, and to reduce the time needed to reach the radioactivity level of the raw material originally used to produce energy. The first stage in the transmutation process is the isotopes inventory formed in the spent fuel. In this paper is made an intercomparison evaluation using WIMS 5B.12 and ORIGEN computer codes. Using these two codes, there is evaluated the isotopes released by a fuel standard from a Candu reactor. Moreover, there is simulated an inventory released by a Candu-SEU reactor and an ACR reactor. (authors)

  19. Intrinsically Zirconium-89 Labeled Gd2 O2 S:Eu Nanoprobes for In Vivo Positron Emission Tomography and Gamma-Ray-Induced Radioluminescence Imaging.

    PubMed

    Zhan, Yonghua; Ai, Fanrong; Chen, Feng; Valdovinos, Hector F; Orbay, Hakan; Sun, Haiyan; Liang, Jimin; Barnhart, Todd E; Tian, Jie; Cai, Weibo

    2016-06-01

    The engineering of a novel dual-modality imaging probe is reported here by intrinsically labeling zirconium-89 ((89) Zr, a positron emission radioisotope with a half-life of 78.4 h) to PEGylated Gd2 O2 S:Eu nanophorphors, forming [(89) Zr]Gd2 O2 S:Eu@PEG for in vivo positron emission tomography/radioluminescence lymph node mapping. PMID:27106630

  20. Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Cucinotta, F. A.; Wilson, J. W.; Badhwar, G. D.; O'Neill, P. M.; Badavi, F. F.

    1995-01-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

  1. Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions.

    PubMed

    Shinn, J L; Cucinotta, F A; Wilson, J W; Badhwar, G D; O'Neill, P M; Badavi, F F

    1995-12-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects. PMID:11541192

  2. Effects of Target Fragmentation on Evaluation of LET Spectra From Space Radiation in Low-Earth Orbit (LEO) Environment: Impact on SEU Predictions

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Cucinotta, F. A.; Badhwar, G. D.; ONeill, P. M.; Badavi, F. F.

    1995-01-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

  3. Using Classical Reliability Models and Single Event Upset (SEU) Data to Determine Optimum Implementation Schemes for Triple Modular Redundancy (TMR) in SRAM-Based Field Programmable Gate Array (FPGA) Devices

    NASA Technical Reports Server (NTRS)

    Berg, M.; Kim, H.; Phan, A.; Seidleck, C.; LaBel, K.; Pellish, J.; Campola, M.

    2015-01-01

    Space applications are complex systems that require intricate trade analyses for optimum implementations. We focus on a subset of the trade process, using classical reliability theory and SEU data, to illustrate appropriate TMR scheme selection.

  4. The influence of different species of gases on the luminescent and structural properties of pulsed laser-ablated Y2O2S:Eu3+ thin films

    NASA Astrophysics Data System (ADS)

    Ali, A. G.; Dejene, B. F.; Swart, H. C.

    2016-05-01

    Y2O2S:Eu3+ films have been grown on Si (100) substrates by using a pulsed laser deposition technique. The thin films grown under vacuum, argon and oxygen ambient have been characterized using structural and luminescent measurements. The X-ray diffraction patterns showed mixed phases of cubic and hexagonal crystal structures. The crystallinity of the film deposited in vacuum is poor, but improved significantly in argon and oxygen atmosphere. Similarly, both scanning electron microscopy and atomic force microscopy confirmed that different species of gases affected the morphology of the films. The average band gap of the films calculated from diffuse reflectance spectra using the Kubelka-Munk function was about 4.69 eV. The photoluminescence measurements indicated red emission of Y2O2S:Eu3+ thin films with the most intense peak appearing at 612 nm, which is assigned to the 5 D 0-7 F 2 transition of Eu3+. The intensities of this most intense peak greatly depend on the species of gas with argon having the highest peak. This phosphor has applications in the flat panel displays.

  5. A comparative investigation of Lu2SiO5:Ce and Gd2O2S:Eu powder scintillators for use in x-ray mammography detectors

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Fountos, G. P.; David, S. L.; Valais, I. G.; Toutountzis, A. E.; Kalyvas, N. E.; Kandarakis, I. S.; Panayiotakis, G. S.

    2009-10-01

    The dominant powder scintillator in most medical imaging modalities for decades has been Gd2O2S:Tb due to the very good intrinsic properties and overall efficiency. Apart from Gd2O2S:Tb, there are alternative powder phosphor scintillators such as Lu2SiO5:Ce and Gd2O2S:Eu that have been suggested for use in various medical imaging modalities. Gd2O2S:Eu emits red light and can be combined mainly with digital mammography detectors such as CCDs. Lu2SiO5:Ce emits blue light and can be combined with blue sensitivity films, photocathodes and some photodiodes. For the purposes of the present study, two scintillating screens, one from Lu2SiO5:Ce and the other from Gd2O2S:Eu powders, were prepared using the method of sedimentation. The screen coating thicknesses were 25.0 and 33.1 mg cm-2 respectively. The screens were investigated by evaluating the following parameters: the output signal, the modulation transfer function, the noise equivalent passband, the informational efficiency, the quantum detection efficiency and the zero-frequency detective quantum efficiency. Furthermore, the spectral compatibility of those materials with various optical detectors was determined. Results were compared to published data for the commercially employed 'Kodak Min-R film-screen system', based on a 31.7 mg cm-2 thick Gd2O2S:Tb phosphor. For Gd2O2S:Eu, MTF data were found comparable to those of Gd2O2S:Tb, while the MTF of Lu2SiO5:Ce was even higher resulting in better spatial resolution and image sharpness properties. On the other hand, Gd2O2S:Eu was found to exhibit higher output signal and zero-frequency detective quantum efficiency than Lu2SiO5:Ce.

  6. An SEU immune logic family

    NASA Technical Reports Server (NTRS)

    Canaris, J.

    1991-01-01

    A new logic family, which is immune to single event upsets, is described. Members of the logic family are capable of recovery, regardless of the shape of the upsetting event. Glitch propagation from an upset node is also blocked. Logic diagrams for an Inverter, Nor, Nand, and Complex Gates are provided. The logic family can be implemented in a standard, commercial CMOS process with no additional masks. DC, transient, static power, upset recovery and layout characteristics of the new family, based on a commercial 1 micron CMOS N-Well process, are described.

  7. SEU and SEL response of the Westinghouse 64K E{sup 2}PROM, analog devices AD7876 12-bit ADC, and the Intel 82527 Serial Communications Controller

    SciTech Connect

    Sexton, F.W.; Hash, G.L.; Connors, M.P.; Murray, J.R.; Schwank, J.R.; Winokur, P.S.; Bradley, E.G.

    1994-12-01

    The Westinghouse SA3823 64K E{sup 2}PROM radiation-hardened SONOS non-volatile memory exhibited a single-event-upset (SEU) threshold in the read mode of 60 MeV-cm{sup 2}/mg and 40 MeV-cm{sup 2}/mg for data latch errors. The minimum threshold for address latch errors was 35 MeV-cm{sup 2}/mg. Hard errors were observed with Kr at V{sub p} = 8.5 V and with Xe at Programming voltages (V{sub p}) as low as 7.5 V. NO hard errors were observed with Cu at any angle up to V{sub p} = II V. The system specification of no hard errors for Ar ions or lighter was exceeded. No single-event latchup (SEL) was observed in these devices for the conditions examined. The Analog Devices AD7876 12bit analog-to-digital converter (ADC) had an upset threshold of 2 MeV-cm{sup 2}/mg for all values of input voltage (V{sub in}), while the worst-case saturation cross section of {approximately}2 {times} 10{sup {minus}3} cm{sup 2} as measured with V{sub in} = 4.49 V. No latchup was observed. The Intel 82C527 serial communications controller exhibited a minimum threshold for upset of 2 MeV-cm{sup 4}/mLi, and a saturation cross section of about 5 {times} 10{sup {minus}4}cm{sup 2}. For latchup the minimum threshold was measured at 17 MeV-cm{sup 2}/mg, and cross section saturated at about 3 {times} 10{sup {minus}4} cm{sup 2}. Error rates for the expected applications are presented.

  8. Bioactivity-guided fractionation of the triglyceride-lowering component and in vivo and in vitro evaluation of hypolipidemic effects of Calyx seu Fructus Physalis

    PubMed Central

    2012-01-01

    Background In folklore, some people take the decoction of Calyx seu Fructus Physalis (CSFP) for lowering blood lipids. The present study is designed to evaluate the lipid-lowering activities of CSFP, and search for its pharmacodynamical material. Methods CSFP was extracted by water and 75% ethanol, respectively. The extracts of CSFP for reducing serum lipid levels were evaluated on mouse model of hyperlipidemia. The optimized extract was subjected to the bioactivity-guided fractionation in which the liquid-liquid extraction, collumn chromatography, the in vivo and in vitro models of hyperlipidemia were utilized. The structure of active component was determined by 13 C-NMR and 1H-NMR. Results The 75% ethanol extract of CSFP decreased the serum total cholesterol (TC) and triglyceride (TG) levels in mouse model of hyperlipidemia. Followed a separation process for the 75% ethanol extract of CSFP, the fraction B was proved to be an active fraction for lowering lipid in vivo and in vitro experiments, which could significantly decrease the serum TC and TG levels in mouse model of hyperlipidemia, and remarkably decrease the increase of TG in primary mouse hepatocytes induced by high glucose and the increase of TG in HepG2 cells induced by oleic acid. The fraction B2, isolated from B on bioactivity-guided fractionation, could significantly decrease TG level in HepG2 cells. One compound with the highest content in B2 was isolated and determined as luteolin-7-O-beta-D-glucopyranoside by NMR spectra. It could significantly reduce the TG level in HepG2 cells, and inhibited the accumulation of lipids by oil red O stain. Conclusion Our results demonstrated that the 75% ethanol extract of CSFP could improve in vitro and in vivo lipid accumulation. Luteolin-7-O-beta-D-glucopyranoside might be a leading pharmacodynamical material of CSFP for lowering lipids. PMID:22413998

  9. Imaging performance of a thin Lu2O3:Eu nanophosphor scintillating screen coupled to a high resolution CMOS sensor under X-ray radiographic conditions: comparison with Gd2O2S:Eu conventional phosphor screen

    NASA Astrophysics Data System (ADS)

    Seferis, I.; Michail, C.; Valais, I.; Zeler, J.; Liaparinos, P.; Kalyvas, N.; Fountos, G.; Zych, E.; Kandarakis, I.; Panayiotakis, G.

    2014-03-01

    The purpose of the present study was to experimentally evaluate the imaging characteristics of the Lu2O3:Eu nanophosphor thin screen coupled to a high resolution CMOS sensor under radiographic conditions. Parameters such as the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE) were investigated at 70 kVp under three exposure levels (20 mAs, 63 mAs and 90 mAs). Since Lu2O3:Eu emits light in the red wavelength range, the imaging characteristics of a 33.3 mg/cm2 Gd2O2S:Eu conventional phosphor screen were also evaluated for comparison purposes. The Lu2O3:Eu nanophosphor powder was produced by the combustion synthesis, using urea as fuel. A scintillating screen of 30.2 mg/cm2 was prepared by sedimentation of the nanophosphor powder on a fused silica substrate. The CMOS/Lu2O3:Eu detector`s imaging characteristics were evaluated using an experimental method proposed by the International Electrotechnical Commission (IEC) guidelines. It was found that the CMOS/Lu2O3:Eu nanophosphor system has higher MTF values compared to the CMOS/Gd2O2S:Eu sensor/screen combination in the whole frequency range examined. For low frequencies (0 to 2 cycles/mm) NNPS values of the CMOS/Gd2O2S:Eu system were found 90% higher compared to the NNPS values of the CMOS/Lu2O3:Eu nanophosphor system, whereas from medium to high frequencies (2 to 13 cycles/mm) were found 40% higher. In contrast with the CMOS/ Gd2O2S:Eu system, CMOS/Lu2O3:Eu nanophosphor system appears to retain high DQE values in the whole frequency range examined. Our results indicate that Lu2O3:Eu nanophosphor is a promising scintillator for further research in digital X-ray radiography.

  10. Decay time characteristics of La2O2S:Eu and La2O2S:Tb for use within an optical sensor for human skin temperature measurement

    SciTech Connect

    Yap, Sook Voon; Ranson, Robert M.; Cranton, Wayne M.; Koutsogeorgis, Demosthenes

    2008-09-20

    We focus on the development of a remote temperature sensing technology, i.e., an optical laser-based sensor, using thermographic phosphors for medical applications, particularly within an electromagnetically hostile magnetic resonance imaging (MRI) environment. A MRI scanner uses a strong magnetic field and radio waves to generate images of the inside of the body. The quality of the image improves with increasing magnetic resonance; however, the drawback of applying a greater magnetic strength is the inducement of heat into the body tissue. Therefore, monitoring the patient's temperature inside MRI is vital, but until now, a practical solution for temperature measurement did not exist. We show europium doped lanthanum oxysulphide (La2O2S:Eu) and terbium doped lanthanum oxysulphide (La2O2S:Tb) are both temperature sensitive to a low temperature range of 10-50 deg. C when under ultraviolet (UV) excitation. The emission spectra and decay time characteristics of these phosphors were demonstrated. The results indicate that La2O2S:Eu has a quenching rate of 13.7 m deg. C{sup -1} and 4 m deg. C{sup -1} at 512 nm and 538 nm, respectively. In addition, La2O2S:Tb has a lower quenching rate of 4.19 m deg. C{sup -1} at 548 nm due to its faster decay time.

  11. SEU and Test Considerations for FPGA Devices

    NASA Technical Reports Server (NTRS)

    Berg, Malanie

    2006-01-01

    This viewgraph presentation provides an overview of Field Programmable Gate Arrays (FPGAs), what they are, implementations in space missions, and current available technologies. Single Event Upsets (SEUs) and Single Event Transients (SETs) are discussed in relation to their effects on FPGAs. Testing goals, considerations, and data analysis are reviewed.

  12. VIRTEX-4 VQ static SEU Characterization Summary

    NASA Technical Reports Server (NTRS)

    Allen, Gregory; Swift, Gary; Carmichael, Carl

    2008-01-01

    This report is the result of the combined efforts of members within the Xilinx Radiation Test Consortium (XRTC), sometimes known as the Xilinx SEE Test Consortium. The XRTC is a voluntary association of aerospace entities, including leading aerospace companies, universities and national laboratories, combining resources to characterize reconfigurable FPGAs for aerospace applications. Previous publications of Virtex-4 radiation results are for commercial (non-epitaxial) devices; see, for example, Refs. 1-4. A notable exception is Ref. 5, which presents XRTC upset measurements of storage elements in the PowerPC405s in the XQR4VFX60. This report of upset susceptibility to heavy ions and protons of the static memory elements in the Virtex-4QV family is a direct parallel to the XRTC report on the thin epitaxial devices in the Virtex-2 family released four years ago.

  13. Methods and circuitry for reconfigurable SEU/SET tolerance

    NASA Technical Reports Server (NTRS)

    Shuler, Jr., Robert L. (Inventor)

    2010-01-01

    A device is disclosed in one embodiment that has multiple identical sets of programmable functional elements, programmable routing resources, and majority voters that correct errors. The voters accept a mode input for a redundancy mode and a split mode. In the redundancy mode, the programmable functional elements are identical and are programmed identically so the voters produce an output corresponding to the majority of inputs that agree. In a split mode, each voter selects a particular programmable functional element output as the output of the voter. Therefore, in the split mode, the programmable functional elements can perform different functions, operate independently, and/or be connected together to process different parts of the same problem.

  14. SEU sensitivity of power converters with MOSFETS in space

    SciTech Connect

    Brucker, G.J.; Measel, P.; Oberg, D.; Wert, J.; Criswell, T.

    1987-12-01

    This paper presents the results of an investigation into the survivability of power MOSFETs in space. Seventy-two of these devices are presently in geosynchronous orbit on board six communications spacecraft, and operating at 70V which is 70% of the nominal breakdown voltage. No failures have occurred after 94536 device-days in space. The irradiation of discrete parts as well as the prototype flight power converter, containing the same part types, by iron particles with a LET of 10 MeV-cm/sup 2/.mg, and an iron spectrum with a maximum LET of 26 showed these Hi-Rel (''S'') flight parts to be relatively harder than the same type of devices previously ground tested. This appears to be the explanation for the lack of failures in space.

  15. Xilinx Virtex-5QV (V5QV) Independent SEU Data

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Label, Kenneth A.; Pellish, Jonathan

    2014-01-01

    This is an independent study to determine the single event destructive and transient susceptibility of the Xilinx Virtex-5QV (SIRF) device. A framework for evaluating complex digital systems targeted for harsh radiation environments such as space is presented.

  16. SEU/SET Tolerant Phase-Locked Loops

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L., Jr.

    2010-01-01

    The phase-locked loop (PLL) is an old and widely used circuit for frequency and phase demodulation, carrier and clock recovery, and frequency synthesis [1]. Its implementations range from discrete components to fully integrated circuits and even to firmware or software. Often the PLL is a highly critical component of a system, as for example when it is used to derive the on-chip clock, but as of this writing no definitive single-event upset (SET)/single-event transient (SET) tolerant PLL circuit has been described. This chapter hopes to rectify that situation, at least in regard to PLLs that are used to generate clocks. Older literature on fault-tolerant PLLs deals with detection of a hard failure, which is recovered by replacement, repair, or manual restart of discrete component systems. Several patents exist along these lines (6349391, 6272647, and 7089442). A newer approach is to harden the parts of a PLL system, to one degree or another, such as by using a voltage-based charge pump or a triple modular redundant (TMR) voted voltage-controlled oscillator (VCO). A more comprehensive approach is to harden by triplication and voting (TMR) all the digital pieces (primarily the divider) of a frequency synthesis PLL, but this still leaves room for errors in the VCO and the loop filter. Instead of hardening or voting pieces of a system, such as a frequency synthesis system (i.e., clock multiplier), we will show how the entire system can be voted. There are two main ways of doing this, each with advantages and drawbacks. We will show how each has advantages in certain areas, depending on the lock acquisition and tracking characteristics of the PLL. Because of this dependency on PLL characteristics, we will briefly revisit the theory of PLLs. But first we will describe the characteristics of voters and their correct application, as some literature does not follow the voting procedure that guarantees elimination of errors. Additionally, we will find that voting clocks is a bit trickier than voting data where an infallible clock is assumed. It is our job here to produce (or recover) that assumed infallible clock!

  17. The Sustainable Energy Utility (SEU) Model for Energy Service Delivery

    ERIC Educational Resources Information Center

    Houck, Jason; Rickerson, Wilson

    2009-01-01

    Climate change, energy price spikes, and concerns about energy security have reignited interest in state and local efforts to promote end-use energy efficiency, customer-sited renewable energy, and energy conservation. Government agencies and utilities have historically designed and administered such demand-side measures, but innovative…

  18. Two-dimensional thermography using La sub 2 O sub 2 S:Eu and Y sub 2 O sub 2 S:Eu thermal phosphors

    SciTech Connect

    Taliaferro, J.M.; Allison, S.W.; Tobin, K.W.

    1991-11-01

    This report describes efforts to obtain two-dimensional temperature profiles of aerodynamic surfaces by using imaging techniques in conjunction with fluorescence thermometry. The fluorescence of several temperature sensitive phosphors were observed by using an image-intensified, charge coupled device (CCD) camera. The intensity profile of the image for two emission wavelengths was stored and processed to yield temperature profiles of a coated specimen. The best results were obtained with oxysulfide phosphors, which showed temperature dependence from ambient to 200{degree}C. The temperature resolution was about 0.5%C at ambient. 3 refs.

  19. Analysis of the influence of MOS device geometry on predicted SEU cross sections

    SciTech Connect

    Warren, K.; Massengill, L.; Schrimpf, R.; Barnaby, H.

    1999-12-01

    An investigation into the single-event sensitive area geometry of a body-tied-to-source (BTS) SOI nMOS transistor has been performed through a novel simulation technique. Results are presented which demonstrate the influence of spatial variations in charge collection efficiency on the shape of the predicted upset cross section curve. Observations are made on a technique for inferring sensitive area or intra-cell collection efficiencies from cross section data.

  20. Single event upset (SEU) of semiconductor devices - A summary of JPL test data

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Price, W. E.; Malone, C. J.

    1983-01-01

    The data summarized describe single event upset (bit-flips) for 60 device types having data storage elements. The data are from 15 acceleration tests with both protons and heavier ions. Tables are included summarizing the upset threshold data and listing the devices tested for heavy ion induced bit-flip and the devices tested with protons. With regard to the proton data, it is noted that the data are often limited to one proton energy, since the tests were usually motivated by the engineering requirement of comparing similar candidate devices for a system. It is noted that many of the devices exhibited no upset for the given test conditions (the maximum fluence and the maximum proton energy Ep are given for these cases). It is believed, however, that some possibility of upset usually exists because there is a slight chance that the recoil atom may receive up to 10 to 20 MeV of recoil energy (with more energy at higher Ep).

  1. Defect-sensitivity analysis of an SEU immune CMOS logic family

    NASA Technical Reports Server (NTRS)

    Ingermann, Erik H.; Frenzel, James F.

    1992-01-01

    Fault testing of resistive manufacturing defects is done on a recently developed single event upset immune logic family. Resistive ranges and delay times are compared with those of traditional CMOS logic. Reaction of the logic to these defects is observed for a NOR gate, and an evaluation of its ability to cope with them is determined.

  2. Determination of key parameters of SEU occurrence using 3-D full cell SRAM simulations

    SciTech Connect

    Roche, P.; Palau, J.M.; Bruguier, G.; Tavernier, C.; Ecoffet, R.; Gasiot, J.

    1999-12-01

    A 3-D entire SRAM cell, based on a 0.35-{micro}m current CMOS technology, is simulated in this work with a DEVICE simulator. The transient current, resulting from a heavy ion strike in the most sensitive region of the cell, is studied as a function of the LET value, the cell layout and the ion penetration depth. A definition of the critical charge is proposed and two new methods are presented to compute this basic amount of charge only using SPICE simulations. Numerical applications are performed with two different generations of submicron CMOS technologies, including the determination of the sensitive thicknesses.

  3. A guideline for heavy ion radiation testing for Single Event Upset (SEU)

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Price, W. E.; Malone, C.

    1984-01-01

    A guideline for heavy ion radiation testing for single event upset was prepared to assist new experimenters in preparing and directing tests. How to estimate parts vulnerability and select an irradiation facility is described. A broad brush description of JPL equipment is given, certain necessary pre-test procedures are outlined and the roles and testing guidelines for on-site test personnel are indicated. Detailed descriptions of equipment needed to interface with JPL test crew and equipment are not provided, nor does it meet the more generalized and broader requirements of a MIL-STD document. A detailed equipment description is available upon request, and a MIL-STD document is in the early stages of preparation.

  4. Two-dimensional thermography using La{sub 2}O{sub 2}S:Eu and Y{sub 2}O{sub 2}S:Eu thermal phosphors

    SciTech Connect

    Taliaferro, J.M.; Allison, S.W.; Tobin, K.W.

    1991-11-01

    This report describes efforts to obtain two-dimensional temperature profiles of aerodynamic surfaces by using imaging techniques in conjunction with fluorescence thermometry. The fluorescence of several temperature sensitive phosphors were observed by using an image-intensified, charge coupled device (CCD) camera. The intensity profile of the image for two emission wavelengths was stored and processed to yield temperature profiles of a coated specimen. The best results were obtained with oxysulfide phosphors, which showed temperature dependence from ambient to 200{degree}C. The temperature resolution was about 0.5%C at ambient. 3 refs.

  5. Determining the Best-Fit FPGA for a Space Mission: An Analysis of Cost, SEU Sensitivity,and Reliability

    NASA Technical Reports Server (NTRS)

    Berg, Melanie; LaBel, Ken

    2007-01-01

    This viewgraph presentation reviews the selection of the optimum Field Programmable Gate Arrays (FPGA) for space missions. Included in this review is a discussion on differentiating amongst various FPGAs, cost analysis of the various options, the investigation of radiation effects, an expansion of the evaluation criteria, and the application of the evaluation criteria to the selection process.

  6. Experience, lessons learned and methodology in the design of space systems to accommodate total dose and SEU effects

    NASA Technical Reports Server (NTRS)

    Trainor, James H.

    1993-01-01

    We now have considerable experience with successfully designing science systems to function properly, even during and after exposure to ionizing radiation approaching one Megarad, and during large solar particle events with substantial high Z fluxes such as the events that happened in August, 1972 and in the fall of 1989. Nevertheless, with changing device dimensions and properties, newer technologies and new applications, new problems arise. Some recent basic research has shed light on these problems and pointed the way to better diagnostic tests. In the case of single event upsets, clearly one cannot always accurately predict upset probabilities simply by knowing the quiescent Linear Energy Transfer (LET) threshold and the asymptotic cross-section of the device.

  7. SEDS MIL-STD-1773 fiber optic data bus: Proton irradiation test results and spaceflight SEU data

    SciTech Connect

    LaBel, K.A.; Stassinopoulos, E.G.; Miller, J.T. ); Marshall, P. ); Dale, C. ); Crabtree, C.M. ); Gates, M.M. )

    1993-12-01

    The Small Explorer Data System (SEDS) was launched in July of 1992 as part of the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX) mission. The SEDS utilizes NASA's first MIL-STD-1773 Fiber Optic Multiplexed Data Bus (or 1773 bus) to communicate with other spacecraft subsystems in the space environment. The 1773 bus is the fiber optic version of the MIL-STD-1553 Data Bus, a electronic wire bus used in many avionics applications. The authors present proton test and space flight single event effect data for NASA's first fiber optic data bus. Bit error rate predictions based on a new proton direct ionization model agree well with flight data for proton belt and solar flare effects.

  8. Effectiveness of Internal vs. External SEU Scrubbing Mitigation Strategies in a Xilinx FPGA: Design, Test, and Analysis

    NASA Technical Reports Server (NTRS)

    Berg, Melanie; Poivey C.; Petrick, D.; Espinosa, D.; Lesea, Austin; LaBel, K. A.; Friendlich, M; Kim, H; Phan, A.

    2008-01-01

    We compare two scrubbing mitigation schemes for Xilinx FPGA devices. The design of the scrubbers is briefly discussed along with an examination of mitigation limitations. Proton and Heavy Ion data are then presented and analyzed.

  9. A software solution to estimate the SEU-induced soft error rate for systems implemented on SRAM-based FPGAs

    NASA Astrophysics Data System (ADS)

    Zhongming, Wang; Zhibin, Yao; Hongxia, Guo; Min, Lu

    2011-05-01

    SRAM-based FPGAs are very susceptible to radiation-induced Single-Event Upsets (SEUs) in space applications. The failure mechanism in FPGA's configuration memory differs from those in traditional memory device. As a result, there is a growing demand for methodologies which could quantitatively evaluate the impact of this effect. Fault injection appears to meet such requirement. In this paper, we propose a new methodology to analyze the soft errors in SRAM-based FPGAs. This method is based on in depth understanding of the device architecture and failure mechanisms induced by configuration upsets. The developed programs read in the placed and routed netlist, search for critical logic nodes and paths that may destroy the circuit topological structure, and then query a database storing the decoded relationship of the configurable resources and corresponding control bit to get the sensitive bits. Accelerator irradiation test and fault injection experiments were carried out to validate this approach.

  10. Auxin can act independently of CRC, LUG, SEU, SPT and STY1 in style development but not apical-basal patterning of the Arabidopsis gynoecium.

    PubMed

    Ståldal, Veronika; Sohlberg, Joel J; Eklund, D Magnus; Ljung, Karin; Sundberg, Eva

    2008-01-01

    Patterning of the Arabidopsis thaliana gynoecium is dependent on the localization and concentration of the plant hormone auxin and it has been previously reported that STYLISH1 (STY1) activates transcription of the auxin biosynthesis gene YUCCA4 (YUC4) and affects gynoecium development. Here, the relationship between auxin, STY1 and other regulators of gynoecium development was examined. Exogenous auxin in droplets of lanolin paste were applied to young gynoecia; auxin biosynthesis rate was measured and STY1 overexpression or chemically mediated polar auxin transport (PAT) inhibition were induced in various mutants. The style phenotype of sty1-1sty2-1 mutants was restored by exogenous application of auxin, and STY1 over-activation resulted in an elevated auxin biosynthesis rate. Both over-activation of STY1 and inhibition of PAT restored the stylar defects of several unrelated mutants, but with regard to gynoecium apical-basal patterning the mutants responded differently to inhibition of PAT. These results suggest that reduced auxin concentrations cause the sty1-1 sty2-1 phenotype, that STY1 induces auxin biosynthesis, that elevated apical auxin concentrations can compensate for the loss of several style-promoting factors, and that auxin may act downstream of, or in parallel with these during style development but is dependent on their action in apical-basal patterning. PMID:18811619

  11. Co-precipitation synthesis of Y2O2SO4:Eu3+ nanophosphor and comparison of photoluminescence properties with Y2O3:Eu3+ and Y2O2S:Eu3+ nanophosphors

    NASA Astrophysics Data System (ADS)

    Lian, Jingbao; Qin, Hua; Liang, Ping; Liu, Feng

    2015-10-01

    Eu3+ ions activated yttrium oxysulfate (Y2O2SO4:Eu3+) nanophosphor has been successfully synthesized by a co-precipitation method from commercially available Y(NO3)3·6H2O, Eu(NO3)3·6H2O, (NH4)2SO4 and NH3·H2O as the starting materials. Detailed characterizations of the synthetic products were obtained by differential thermal analysis, thermogravimetry and derivative thermogravimetry (DTA-TG-DTG), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The results revealed that the precursor was composed of amorphous yttrium hydroxide sulfate when (NH4)2SO4 was introduced in the reaction system. Moreover, the precursor could be converted into pure Y2O2SO4 phase by calcining at 800 °C for 2 h in air and pure Y2O2S phase could be obtained by calcining Y2O2SO4 at 800 °C for 1 h in hydrogen atmosphere. The as-synthesized Y2O2SO4 phosphor particles are quasi-spherical in shape, slight aggregation and about 20-30 nm in size. PL spectra of the Y2O2SO4:Eu3+ nanophosphor under 270 nm ultraviolet (UV) light excitation show a red emission at 620 nm as the most prominent peak, which attributes to the 5D0→7F2 transition of Eu3+ ions. The quenching concentration of Eu3+ ions was 5 mol%, and its corresponding fluorescence lifetime was 1.49 ms according to the linear fitting result. Furthermore, the Y2O3 nanophosphor was synthesized by similar reaction and comparison of PL properties among three kinds of Eu3+ activated nanophosphors was also systematically discussed.

  12. AVALIAÇÃO DA PRESENÇA DE ENDOSSIMBIONTES Cardinium em DIFERENTES ESPÉCIES DE ARTRÓPODES.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A presença de endossimbiontes do gênero Cardinium em alguns grupos de artrópodes foi recentemente relatada e relacionada com diversas alterações reprodutivas em seus hospedeiros, tais como feminilização de ácaros, partenogênese em parasitóides, incompatibilidade citoplasmática e aumento da fecundida...

  13. Single event upsets calculated from new ENDF/B-VI proton and neutron data up to 150 MeV

    SciTech Connect

    Chadwick, M.B.; Normand, E.

    1999-06-01

    Single-event upsets (SEU) in microelectronics are calculated from newly-developed silicon nuclear reaction recoil data that extend up to 150 MeV, for incident protons and neutrons. Calculated SEU cross sections are compared with measured data.

  14. Single event upset test structures for digital CMOS application specific integrated circuits

    SciTech Connect

    Baze, M.P.; Bartholet, W.G.; Braatz, J.C.; Dao, T.A. )

    1993-12-01

    An approach has been developed for the design and utilization of SEU test structures for digital CMOS ASICs. This approach minimizes the number of test structures required by categorizing ASIC library cells according to their SEU response and designing a structure to characterize each response for each category. Critical SEU response parameters extracted from these structures are used to evaluate the SEU hardness of ASIC libraries and predict the hardness of ASIC chips.

  15. Single event upset cross sections at various data rates

    SciTech Connect

    Reed, R.A.; Marshall, C.J.; McMorrow, D.; Carts, M.A.; Marshall, P.W.; Buchner, S.; La Macchia, M.; Mathes, B.

    1996-12-01

    The authors present data which show that Single Event Upset (SEU) cross section varies linearly with frequency for most devices tested. They show that the SEU cross section can increase dramatically away from a linear relationship when the test setup is not optimized, or when testing near the maximum operating frequency. They also observe non-linear behavior in some complex circuit topologies. Knowledge of the relationship between SEU cross section and frequency is important for estimates of on-orbit SEU rates.

  16. The Self in Decision Making and Decision Implementation.

    ERIC Educational Resources Information Center

    Beach, Lee Roy; Mitchell, Terence R.

    Since the early 1950's the principal prescriptive model in the psychological study of decision making has been maximization of Subjective Expected Utility (SEU). This SEU maximization has come to be regarded as a description of how people go about making decisions. However, while observed decision processes sometimes resemble the SEU model,…

  17. Subjective Expected Utility: A Model of Decision-Making.

    ERIC Educational Resources Information Center

    Fischoff, Baruch; And Others

    1981-01-01

    Outlines a model of decision making known to researchers in the field of behavioral decision theory (BDT) as subjective expected utility (SEU). The descriptive and predictive validity of the SEU model, probability and values assessment using SEU, and decision contexts are examined, and a 54-item reference list is provided. (JL)

  18. Device simulation of charge collection and single-event upset

    SciTech Connect

    Dodd, P.E.

    1996-04-01

    In this paper the author reviews the current status of device simulation of ionizing-radiation-induced charge collection and single-event upset (SEU), with an emphasis on significant results of recent years. The author presents an overview of device-modeling techniques applicable to the SEU problem and the unique challenges this task presents to the device modeler. He examines unloaded simulations of radiation-induced charge collection in simple p/n diodes, SEU in dynamic random access memories (DRAM`s), and SEU in static random access memories (SRAM`s). The author concludes with a few thoughts on future issues likely to confront the SEU device modeler.

  19. SEUSS Integrates Gibberellin Signaling with Transcriptional Inputs from the SHR-SCR-SCL3 Module to Regulate Middle Cortex Formation in the Arabidopsis Root.

    PubMed

    Gong, Xue; Flores-Vergara, Miguel A; Hong, Jing Han; Chu, Huangwei; Lim, Jun; Franks, Robert G; Liu, Zhongchi; Xu, Jian

    2016-03-01

    A decade of studies on middle cortex (MC) formation in the root endodermis of Arabidopsis (Arabidopsis thaliana) have revealed a complex regulatory network that is orchestrated by several GRAS family transcription factors, including SHORT-ROOT (SHR), SCARECROW (SCR), and SCARECROW-LIKE3 (SCL3). However, how their functions are regulated remains obscure. Here we show that mutations in the SEUSS (SEU) gene led to a higher frequency of MC formation. seu mutants had strongly reduced expression of SHR, SCR, and SCL3, suggesting that SEU positively regulates these genes. Our results further indicate that SEU physically associates with upstream regulatory sequences of SHR, SCR, and SCL3; and that SEU has distinct genetic interactions with these genes in the control of MC formation, with SCL3 being epistatic to SEU. Similar to SCL3, SEU was repressed by the phytohormone GA and induced by the GA biosynthesis inhibitor paclobutrazol, suggesting that SEU acts downstream of GA signaling to regulate MC formation. Consistently, we found that SEU mediates the regulation of SCL3 by GA signaling. Together, our study identifies SEU as a new critical player that integrates GA signaling with transcriptional inputs from the SHR-SCR-SCL3 module to regulate MC formation in the Arabidopsis root. PMID:26818732

  20. Impact of temperature on single event upset measurement by heavy ions in SRAM devices

    NASA Astrophysics Data System (ADS)

    Tianqi, Liu; Chao, Geng; Zhangang, Zhang; Fazhan, Zhao; Song, Gu; Teng, Tong; Kai, Xi; Gang, Liu; Zhengsheng, Han; Mingdong, Hou; Jie, Liu

    2014-08-01

    The temperature dependence of single event upset (SEU) measurement both in commercial bulk and silicon on insulator (SOI) static random access memories (SRAMs) has been investigated by experiment in the Heavy Ion Research Facility in Lanzhou (HIRFL). For commercial bulk SRAM, the SEU cross section measured by 12C ions is very sensitive to the temperature. The temperature test of SEU in SOI SRAM was conducted by 209Bi and 12C ions, respectively, and the SEU cross sections display a remarkable growth with the elevated temperature for 12C ions but keep constant for 209Bi ions. The impact of temperature on SEU measurement was analyzed by Monte Carlo simulation. It is revealed that the SEU cross section is significantly affected by the temperature around the threshold linear energy transfer of SEU occurrence. As the SEU occurrence approaches saturation, the SEU cross section gradually exhibits less temperature dependency. Based on this result, the experimental data measured in HIRFL was analyzed, and then a reasonable method of predicting the on-orbit SEU rate was proposed.

  1. SEUSS Integrates Gibberellin Signaling with Transcriptional Inputs from the SHR-SCR-SCL3 Module to Regulate Middle Cortex Formation in the Arabidopsis Root1[OPEN

    PubMed Central

    Gong, Xue; Hong, Jing Han; Chu, Huangwei; Lim, Jun

    2016-01-01

    A decade of studies on middle cortex (MC) formation in the root endodermis of Arabidopsis (Arabidopsis thaliana) have revealed a complex regulatory network that is orchestrated by several GRAS family transcription factors, including SHORT-ROOT (SHR), SCARECROW (SCR), and SCARECROW-LIKE3 (SCL3). However, how their functions are regulated remains obscure. Here we show that mutations in the SEUSS (SEU) gene led to a higher frequency of MC formation. seu mutants had strongly reduced expression of SHR, SCR, and SCL3, suggesting that SEU positively regulates these genes. Our results further indicate that SEU physically associates with upstream regulatory sequences of SHR, SCR, and SCL3; and that SEU has distinct genetic interactions with these genes in the control of MC formation, with SCL3 being epistatic to SEU. Similar to SCL3, SEU was repressed by the phytohormone GA and induced by the GA biosynthesis inhibitor paclobutrazol, suggesting that SEU acts downstream of GA signaling to regulate MC formation. Consistently, we found that SEU mediates the regulation of SCL3 by GA signaling. Together, our study identifies SEU as a new critical player that integrates GA signaling with transcriptional inputs from the SHR-SCR-SCL3 module to regulate MC formation in the Arabidopsis root. PMID:26818732

  2. Single event upset in irradiated 16k CMOS SRAMs

    SciTech Connect

    Axness, C.L.; Schwank, J.R.; Winokur, P.S.; Browning, J.S.; Fleetwood, D.M.; Koga, R.

    1988-12-01

    The Single Event Upset (SEU) characteristics of a CMOS SRAM cell irradiated under conditions that simulate the total-dose degradation anticipated in space applications are experimentally and theoretically investigated. Simulations of SEU sensitivity utilizing a 2D circuit/device simulator, with measured transistor threshold-voltage shifts and mobility degradations as inputs, are shown to be in good agreement with experimental data at high total dose. Both simulation and experiment show a strong SRAM cell SEU imbalance, resulting in a more SEU tolerant preferred state and a less tolerant non-preferred state. The resulting cell imbalance causes an overall degradation in SEU immunity which increases with increasing total dose and which should be taken into account in SEU testing and part characterization.

  3. Studies Of Single-Event-Upset Models

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Smith, L. S.; Soli, G. A.

    1988-01-01

    Report presents latest in series of investigations of "soft" bit errors known as single-event upsets (SEU). In this investigation, SEU response of low-power, Schottky-diode-clamped, transistor/transistor-logic (TTL) static random-access memory (RAM) observed during irradiation by Br and O ions in ranges of 100 to 240 and 20 to 100 MeV, respectively. Experimental data complete verification of computer model used to simulate SEU in this circuit.

  4. The NASA Education Forum at SAO on the Structure and Evolution of the Universe

    NASA Technical Reports Server (NTRS)

    Gould, Roy; Rosendhal, Jeffrey (Technical Monitor)

    2001-01-01

    During the past year the SEU Forum has made significant progress on a number of fronts: (1) the Forum has brought several large education projects close to completion; (2) we have greatly expanded our relationship with the SEU missions and programs; and (3) we have started a significant program to better involve space scientists in education and outreach activities. Among our accomplishments for the past year: (1) completed planning and design for Cosmic Questions, a national traveling exhibition on SEU themes; (2) launched the informal Science Education Resource Directory; (3) Coordinating with the SEU and Origins missions; and (4) promoted scientist-educator partnerships.

  5. A New Approach to Neighbourhood Renewal in England.

    ERIC Educational Resources Information Center

    Wallace, Moira

    2001-01-01

    Summarizes the comprehensive approach to tackling problems of poor neighborhoods developed by the British government's Social Exclusion Unit (SEU), analyzing neighborhood decline and describing the SEU's National Strategy for Neighborhood Renewal, which emphasizes improving public services in England, building inclusive partnerships locally that…

  6. Charge collection spectroscopy

    SciTech Connect

    Reed, R.A.; McNulty, P.J.; Beauvais, W.J.; Roth, D.R. . Dept. of Physics and Astronomy)

    1993-12-01

    Monitoring pulses measured between the power pins of a microelectronic device exposed to high LET ions yields important information on the SEU response of the circuit. Analysis is complicated for p-well CMOS devices by the possibility of competition between unctions, but the results suggest that charge collection measurements are still sufficient to determine SEU parameters accurately.

  7. Application of RADSAFE to Model Single Event Upset Response of a 0.25 micron CMOS SRAM

    NASA Technical Reports Server (NTRS)

    Warren, Kevin M.; Weller, Robert A.; Sierawski, Brian; Reed, Robert A.; Mendenhall, Marcus H.; Schrimpf, Ronald D.; Massengill, Lloyd; Porter, Mark; Wilkerson, Jeff; LaBel, Kenneth A.; Adams, James

    2006-01-01

    The RADSAFE simulation framework is described and applied to model Single Event Upsets (SEU) in a 0.25 micron CMOS 4Mbit Static Random Access Memory (SRAM). For this circuit, the RADSAFE approach produces trends similar to those expected from classical models, but more closely represents the physical mechanisms responsible for SEU in the SRAM circuit.

  8. The single event upset environment for avionics at high latitude

    SciTech Connect

    Sims, A.J.; Dyer, C.S.; Peerless, C.L. . Space and Communications Dept.); Johansson, K.; Pettersson, H. ); Farren, J. . Harwell Lab.)

    1994-12-01

    Modern avionic systems for civil and military applications are becoming increasingly reliant upon embedded microprocessors and associated memory devices. The phenomenon of single event upset (SEU) is well known in space systems and designers have generally been careful to use SEU tolerant devices or to implement error detection and correction (EDAC) techniques where appropriate. In the past, avionics designers have had no reason to consider SEU effects but is clear that the more prevalent use of memory devices combined with increasing levels of IC integration will make SEU mitigation an important design consideration for future avionic systems. To this end, it is necessary to work towards producing models of the avionics SEU environment which will permit system designers to choose components and EDAC techniques which are based on predictions of SEU rates correct to much better than an order of magnitude. Measurements of the high latitude SEU environment at avionics altitude have been made on board a commercial airliner. Results are compared with models of primary and secondary cosmic rays and atmospheric neutrons. Ground based SEU tests of static RAMs are used to predict rates in flight.

  9. The Big Picture: The National Achievement Agenda and Minority Ethnic Pupils.

    ERIC Educational Resources Information Center

    Barber, Michael

    1999-01-01

    Describes issues of minority student achievement in the context of United Kingdom government policies and the government's Standards and Effectiveness Unit (SEU). Discusses: (1) the big picture; (2) data on ethnic student achievement; (3) SEU policies; (4) government approaches to the Ethnic Minority Achievement Grant; and (5) issues for the…

  10. Factors Involved in Juveniles' Decisions about Crime.

    ERIC Educational Resources Information Center

    Cimler, Edward; Beach, Lee Roy

    1981-01-01

    Investigated whether delinquency is the result of a rational decision. The Subjective Expected Utility (SEU) model from decision theory was used with male juvenile offenders (N=45) as the model of the decision process. Results showed that the SEU model predicted 62.7 percent of the subjects' decisions. (Author/RC)

  11. Spread Of Charge From Ion Tracks In Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Schwartz, Harvey R.; Watson, R. Kevin; Nevill, Leland R.

    1989-01-01

    Single-event upsets (SEU's) propagate to adjacent cells in integrated memory circuits. Findings of experiments in lateral transport of electrical-charge carriers from ion tracks in 256K dynamic randon-access memories (DRAM's). As dimensions of integrated circuits decrease, vulnerability to SEU's increases. Understanding gained enables design of less vulnerable circuits.

  12. A radiation-hardened 16/32-bit microprocessor

    SciTech Connect

    Hass, K.J.; Treece, R.K.; Giddings, A.E. )

    1989-12-01

    This paper reports on the development of single chip radiation-hardened 16/32-bit microprocessor. This device, the SA3300, is an emulation of National Semiconductor's NS32C016. The SA3300 is designed to withstand high levels of ionizing radiation and is resistant to single event upset (SEU) caused by heavy ions. New techniques were used to improve immunity to SEU effects in combinational logic. The authors' testing has demonstrated that the SA3300 is functional after a total gamma dose of 5 Mrad(Si). The device does not latch up from SEU, and parts without SEU resistors have an SEU linear energy transfer (LET) upset threshold greater than 28 MeV/mg/cm{sup 2}.

  13. Effects of total dose irradiation on single-event upset hardness.

    SciTech Connect

    Paillet, Philippe; Ferlet-Cavrois, V.; Flores, Richard S.; Schwank, James Ralph; Felix, James Andrew; Shaneyfelt, Marty Ray; Hash, Gerald Leon; Cole, Edward Isaac, Jr.; Blackmore, E. W.; Dodd, Paul Emerson; Baggio, J.

    2005-04-01

    The effect of total dose on SEU hardness is investigated as a function of temperature and power supply voltage to determine worst case hardness assurance test conditions for space environments. SRAMs from six different vendors were characterized for single-event upset (SEU) hardness at proton energies from 20 to 500 MeV and at temperatures of 25 and 80 C after total dose irradiating the SRAMs with either protons, Co-60 gamma rays, or low-energy x-rays. It is shown that total dose irradiation and the bias configuration during total dose irradiation and SEU characterization can substantially affect SEU hardness for some SRAMs. For one SRAM, the bias configuration made more than two orders of magnitude difference in SEU cross section at the highest total dose level examined. In addition, it is shown that increasing the temperature during SEU characterization can also increase the effect of total dose on SEU hardness. As a result, worst-case SEU hardness assurance test conditions are the maximum total dose and temperature of the system environment, and the minimum operating voltage of the SRAM. In contrast to previous works, our results using selective area x-ray irradiations show that the source of the effect of total dose on SEU hardness is radiation-induced leakage currents in the memory cells. The increase in SEU cross section with total dose appears to be consistent with radiation-induced currents originating in the memory cells affecting the output bias levels of bias level shift circuitry used to control the voltage levels to the memory cells and/or due to the lowering of the noise margin of individual memory cells caused by radiation-induced leakage currents.

  14. NASA Education Forum at SAO on the Structure and Evolution of the Universe

    NASA Technical Reports Server (NTRS)

    Rosendhal, Jeffrey (Technical Monitor); Gould, Roy R.

    2003-01-01

    NASA's Structure and Evolution of the Universe (SEU) science theme offers an unparalleled opportunity to capture the public's imagination and inspire the next generation of scientific explorers-the generation that will determine America's lead in science and technology in the 21st century. The missions and research programs of SEU science are transporting the public to some of the universe's most exotic destinations: the beginning of time, the edge of space at the entrance to a black hole, and the great cycles of matter and energy that have slowly brought life to the universe. NASA's Office of Space Science (OSS) has put in place an Education and Public Outreach (EPO) initiative designed to do just that. Spanning all of NASA's OSS science themes, the initiative is a far-reaching partnership with the education community. As a result, NASA space science now reaches every avenue of education-from the nation's schools, science museums and planetariums, to libraries, community groups and after-school programs. As a partner in this enterprise, the,SEU Forum has successfully brought SEU science to a large and diverse audience. But this is an ongoing process, and much still needs to be done. Working with our colleagues in the OSS Support Network, and with our partners in the space science and education communities, we look forward to ensuring that the public supports and participates in the great explorations of the SEU theme. Working with the SEU missions and members of the OSS Support Network, the Forum will harness the assets of the SEU science community to: Inform, inspire, and involve the public in the explorations of the SEU science theme. Use the unique resources of the SEU science theme to enhance K-14 science, technology, and mathematics education. Identify and develop high-leverage opportunities for the SEU science community to contribute to education and outreach.

  15. Establishing the Empirical Relationship Between Non-Science Majoring Undergraduate Learners' Spatial Thinking Skills and Their Conceptual Astronomy Knowledge. (Spanish Title: Estableciendo Una Relación Empírica Entre el Razonamiento Espacial de los Estudiantes de Graduación de Carreras no Científicas y su Conocimento Conceptual de la Astronomía.) Estabelecendo Uma Relação Empírica Entre o RacioCínio Espacial dos Estudantes de Graduação EM Carreiras Não Científicas e Seu Conhecimento Conceitual da Astronomia

    NASA Astrophysics Data System (ADS)

    Heyer, Inge; Slater, Stephanie J.; Slater, Timothy F.

    2013-12-01

    The astronomy education community has tacitly assumed that learning astronomy is a conceptual domain resting upon spatial thinking skills. As a first step to formally identify an empirical relationship, undergraduate students in a non-major introductory astronomy survey class at a mediumsized, Ph.D. granting, mid-western US university were given pre- and post-astronomy conceptual diagnostics and spatial reasoning diagnostics, Instruments used were the "Test Of Astronomy Standards" and "What Do You Know?" Using only fully matched data for analysis, our sample consisted of 86 undergraduate non-science majors. Students' normalized gains for astronomy surveys were low at .26 and .13 respectively. Students' spatial thinking was measured using an instrument designed specifically for this study. Correlations between the astronomy instruments' pre- to post-course gain scores and the spatial assessment instrument show moderate to strong relationships suggesting the relationship between spatial reasoning and astronomy ability can explain about 25% of the variation in student achievement. La comunidad de educación en astronomía ha supuesto de forma tácita que el aprendizaje de la astronomía consiste en un dominio conceptual fundamentado en el razonamiento espacial. Como un primer paso para identificar formalmente una relación empírica entre estas dos cosas, utilizamos como muestra los estudantes de graduación de carreras no científicas de un curso experimental en una universidad norteamericana del medioeste de porte mediano con programa de Doctorado em curso, en el cual estos estudiantes se sometieron a un diagnóstico de razonamiento espacial y conceptos astronómicos antes e después del mismo. Las herramientas utilizadas fueron el Test Of Astronomy Standards (TOAST) y el cuestionario What do you know? Utilizando solo los datos completamente consistentes para este análisis, nuestra muestra consistió en 86 estudantes de graduación. Las mejoras, depués de normalizadas, en el desempeño de los estudiantes en estos dos asuntos foram pequenas, 0.26 e 0.13 respectivamente. El razonamiento espacial de los estudiantes fue medido utilizando un instrumento específico desarrollado para este trabaljo. Las correlaciones entre los resultados de los tests astronómicos y este instrumento específico, antes y después del curso mostraron una relación entre moderada y fuerte, sugiriendo que la relación entre el razonamiento espacial y el conocimiento astronómico puede explicar hasta un 25% de la variación em el desempeño de los estudiantes. A comunidade da educação em astronomia tem suposto de forma implícita que o aprendizado da astronomia consiste em um domínio conceitual fundamentado no raciocínio espacial. Como um primeiro passo para identificar formalmente uma relação empírica entre estas duas coisas, utilizamos como amostra os estudantes de graduação de carreiras não científicas de um curso exploratório em uma universidade norte-americana do meio-oeste de médio porte com programa de Doutorado em andamento, onde estes estudantes foram submetidos a um diagnóstico de raciocino espacial e conceitos astronômicos antes e depois do mesmo. As ferramentas utilizadas foram o Test Of Astronomy Standards (TOAST) e o questionário What do you know? Utilizando somente dados completamente consistentes para esta análise, nossa amostra consistiu de 86 estudantes de graduação. As melhoras, depois de normalizadas, do desempenho dos estudantes nos dois quesitos foram pequenas, 0.26 e 0.13 respectivamente. O raciocínio espacial dos estudantes foi medido utilizando um instrumento específico desenhado para este trabalho. As correlações entre os resultados dos testes astronômicos e este instrumento específico antes e depois do curso mostraram uma relação entre moderada e forte, sugerindo que a relação entre o raciocínio espacial e o conhecimento astronômico pode explicar até um 25% na variação no desempenho dos estudantes.

  16. Heavy Ion Irradiation Fluence Dependence for Single-Event Upsets of NAND Flash Memory

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Wilcox, Edward; Ladbury, Raymond; Kim, Hak; Phan, Anthony; Seidleck, Christina; LaBel, Kenneth

    2016-01-01

    We investigated the single-event effect (SEE) susceptibility of the Micron 16 nm NAND flash, and found the single-event upset (SEU) cross section varied inversely with fluence. The SEU cross section decreased with increasing fluence. We attribute the effect to the variable upset sensitivities of the memory cells. The current test standards and procedures assume that SEU follow a Poisson process and do not take into account the variability in the error rate with fluence. Therefore, heavy ion irradiation of devices with variable upset sensitivity distribution using typical fluence levels may underestimate the cross section and on-orbit event rate.

  17. Single event upsets correlated with environment

    SciTech Connect

    Vampola, A.L.; Albin, F. ); Lauriente, M. ); Wilkinson, D.C.; Allen, J. )

    1994-12-01

    Single Event Upset rates on satellites in different Earth orbits are correlated with solar protons and geomagnetic activity and also with the NASA AP8 proton model to extract information about satellite anomalies caused by the space environment. An extensive discussion of the SEU data base from the TOMS solid state recorder and an algorithm for correcting spontaneous upsets in it are included as an Appendix. SAMPEX and TOMS, which have the same memory chips, have similar normalized responses in the South Atlantic Anomaly. SEU rates due to solar protons over the polar caps are within expectations. No geomagnetic activity effects can be discerned in the SEU rates.

  18. Heavy-ion broad-beam and microprobe studies of single-event upsets in 0.20 um SiGe heterojunction bipolar transistors and circuits.

    SciTech Connect

    Fritz, Karl; Irwin, Timothy J.; Niu, Guofu; Fodness, Bryan; Carts, Martin A.; Marshall, Paul W.; Reed, Robert A.; Gilbert, Barry; Randall, Barbara; Prairie, Jason; Riggs, Pam; Pickel, James C.; LaBel, Kenneth; Cressler, John D.; Krithivasan, Ramkumar; Dodd, Paul Emerson; Vizkelethy, Gyorgy

    2003-09-01

    Combining broad-beam circuit level single-event upset (SEU) response with heavy ion microprobe charge collection measurements on single silicon-germanium heterojunction bipolar transistors improves understanding of the charge collection mechanisms responsible for SEU response of digital SiGe HBT technology. This new understanding of the SEU mechanisms shows that the right rectangular parallele-piped model for the sensitive volume is not applicable to this technology. A new first-order physical model is proposed and calibrated with moderate success.

  19. Determination Of LETs Of SRAMs By Use Of A Laser

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup; Mccarty, Kenneth P.; Barnes, Charles E.; Schwartz, Harvey R.; Coss, James R.

    1995-01-01

    Report describes experimental study of use of microelectronic advanced laser scanner (MEALS) to cause single-event upsets (SEUs) in integrated logic circuits. Basic concepts of SEU testing by use of MEALS described in "Laser Scanner Tests for Single-Event Upsets" (NPO-18216), "Single-Event-Upset Laser Scanner With Optical Bias" (NPO-18217), and "More About Laser Scanner Tests for Single-Event Upsets" (NPO-18494). Study part of continuing effort to study SEU effects of ionizing radiation on such circuits and to use MEALS as relatively inexpensive SEU-prescreening laboratory apparatus serving as alternative to heavy-ion acclerator.

  20. Soft-error generation due to heavy-ion tracks in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1984-01-01

    Both bipolar and MOS integrated circuits have been empirically demonstrated to be susceptible to single-particle soft-error generation, commonly referred to as single-event upset (SEU), which is manifested in a bit-flip in a latch-circuit construction. Here, the intrinsic characteristics of SEU in bipolar (static) RAM's are demonstrated through results obtained from the modeling of this effect using computer circuit-simulation techniques. It is shown that as the dimensions of the devices decrease, the critical charge required to cause SEU decreases in proportion to the device cross-section. The overall results of the simulations are applicable to most integrated circuit designs.

  1. An Examination of Environment Perturbation Effects on Single Event Upset Rates

    NASA Technical Reports Server (NTRS)

    Gates, Michele M.; Leidecker, Henning W.; Lewis, Mark J.

    1997-01-01

    This paper presents an analysis of the sensitivity of single event upset (SEU) rate predictions to changes in the direct ionization-inducing environment. An examination based on the nature of the SEU rate equation is presented for the case in which the perturbation is constant across varying particle linear energy transfer (LET). It is shown that the relative variation in SEU rate is equal to the relative perturbation in flux. Results are also presented for the case in which the environment perturbations exist in small LET bins. Through this analysis it is shown that the relative variation in expected SEU rate is equal to that in flux only for the LET regime in which the product of the cross section and differential flux is maximum.

  2. Single event upsets in gallium arsenide dynamic logic

    SciTech Connect

    Fouts, D.J. . ECE Dept.); Weatherford, T. ); McMorrow, C.; Melinger, J.S.; Campbell, A.B. )

    1994-12-01

    The advantages and disadvantages of using gallium arsenide (GaAs) dynamic logic in computers and digital systems are briefly discussed, especially with respect to space applications. A short introduction to the topology and operation of GaAs Two-Phase Dynamic FET Logic (TDFL) circuits is presented. Experiments for testing the SEU sensitivity of GaAs TDFL, using a laser to create charge collection events, are described. Results are used to estimate the heavy-ion, soft error rate for TDFL in a spacecraft in geosynchronous orbit, and the dependence of the SEU sensitivity on clock frequency, clock voltage, and clock phase. Analysis of the data includes a comparison between the SEU sensitivities of TDFL and the more common static form of GaAs logic, Directly Coupled FET Logic (DCFL). This is the first reported SEU testing of GaAs dynamic logic.

  3. Extensions of the burst generation rate method for wider application to proton/neutron-induced single event effects

    SciTech Connect

    Normand, E.

    1998-12-01

    The Burst Generation Rate (BGR) method, originally developed to calculate single event upset (SEU) rates in microelectronics due to neutrons and protons, has been extended for wider application, allowing cross sections for both SEU and single event latchup (SEL) to be calculated, and comparisons to be made with measured data. The method uses the Weibull fit to accurately represent the behavior of the heavy ion SEU cross section. Proton SEU cross sections in RAMs, microprocessors and FPGAs are calculated, with agreement generally to within a factor of 2--3, and similar results are obtained for neutron cross sections for both cosmic ray and fission spectra. The BGR method is also modified to calculate cross sections for proton/neutron induced SEL. Agreement is generally good for SEL for most devices, but there are also limitations, since some very modern devices are shown to have unusually high susceptibility to SEL by protons/neutrons.

  4. Influence of edge effects on single event upset susceptibility of SOI SRAMs

    NASA Astrophysics Data System (ADS)

    Gu, Song; Liu, Jie; Zhao, Fazhan; Zhang, Zhangang; Bi, Jinshun; Geng, Chao; Hou, Mingdong; Liu, Gang; Liu, Tianqi; Xi, Kai

    2015-01-01

    An experimental investigation of the single event upset (SEU) susceptibility for heavy ions at tilted incidence was performed. The differences of SEU cross-sections between tilted incidence and normal incidence at equivalent effective linear energy transfer were 21% and 57% for the silicon-on-insulator (SOI) static random access memories (SRAMs) of 0.5 μm and 0.18 μm feature size, respectively. The difference of SEU cross-section raised dramatically with increasing tilt angle for SOI SRAM of deep-submicron technology. The result of CRÈME-MC simulation for tilted irradiation of the sensitive volume indicates that the energy deposition spectrum has a substantial tail extending into the low energy region. The experimental results show that the influence of edge effects on SEU susceptibility cannot be ignored in particular with device scaling down.

  5. Single event upset studies using the ATLAS SCT

    NASA Astrophysics Data System (ADS)

    Dafinca, A.; Henderson, J.; Weidberg, A. R.

    2014-01-01

    Single Event Upsets (SEU) are expected to occur during high luminosity running of the ATLAS SemiConductor Tracker (SCT). The SEU cross sections were measured in pion beams with momenta in the range 200 to 465 MeV/c and proton test beams at 24 GeV/c but the extrapolation to LHC conditions is non-trivial because of the range of particle types and momenta. The SEUs studied occur in the p-i-n photodiode and the registers in the ABCD chip. Other possible locations for SEU were not investigated in this study. Comparisons between predicted SEU rates and those measured from ATLAS data are presented. The implications for ATLAS operation are discussed.

  6. A Decision Making Analysis of Persuasive Argumentation and the Choice Shift Effect

    ERIC Educational Resources Information Center

    Vinokur, Amiram; And Others

    1975-01-01

    A subjective expected utility (SEU) decision-making analysis was performed on the content of arguments generated by subjects privately or during group discussion in response to choice-dilemmas shown to shift toward risk and caution. (Editor)

  7. Single-event upset and snapback in silicon-on-insulator devices

    SciTech Connect

    DODD,PAUL E.; SHANEYFELT,MARTY R.; SCHWANK,JAMES R.; HASH,GERALD L.; DRAPER,BRUCE L.; WINOKUR,PETER S.

    2000-02-23

    SEU is studied in SOI transistors and circuits with various body tie structures. The importance of impact ionization effects, including single-event snapback, is explored. Implications for hardness assurance testing of SOI integrated circuits are discussed.

  8. Possible role for secondary particles in proton-induced single event upsets of modern devices

    SciTech Connect

    Savage, M.W.; McNulty, P.J.; Roth, D.R.; Foster, C.C.

    1998-12-01

    Increases in the SEU sensitivity of some modern COTS devices suggest that other reactions besides the direct spallation reaction may begin to play a role in proton SEU events, but only in devices with upset thresholds significantly lower than devices currently flown in space or sold commercially for terrestrial applications. Triple coincidence tagged proton exposures and neutron exposures are combined to demonstrate these reactions in the same device.

  9. Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation

    NASA Astrophysics Data System (ADS)

    Xiao, Yao; Guo, Hong-Xia; Zhang, Feng-Qi; Zhao, Wen; Wang, Yan-Ping; Zhang, Ke-Ying; Ding, Li-Li; Fan, Xue; Luo, Yin-Hong; Wang, Yuan-Ming

    2014-11-01

    Synergistic effects of the total ionizing dose (TID) on the single event upset (SEU) sensitivity in static random access memories (SRAMs) were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed.

  10. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  11. Solar Particle Induced Upsets in the TDRS-1 Attitude Control System RAM During the October 1989 Solar Particle Events

    NASA Technical Reports Server (NTRS)

    Croley, D. R.; Garrett, H. B.; Murphy, G. B.; Garrard,T. L.

    1995-01-01

    The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEU's calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU's by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU'S. The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution. The number of calculated proton-induced SEU's was 72, yielding a total of 248 predicted SEU'S, very dose to the 243 observed SEU'S. These calculations uniquely demonstrate the roles that solar heavy ions and protons played in the production of SEU

  12. Transcriptomic Characterization of a Synergistic Genetic Interaction during Carpel Margin Meristem Development in Arabidopsis thaliana

    PubMed Central

    Wynn, April N.; Rueschhoff, Elizabeth E.; Franks, Robert G.

    2011-01-01

    In flowering plants the gynoecium is the female reproductive structure. In Arabidopsis thaliana ovules initiate within the developing gynoecium from meristematic tissue located along the margins of the floral carpels. When fertilized the ovules will develop into seeds. SEUSS (SEU) and AINTEGUMENTA (ANT) encode transcriptional regulators that are critical for the proper formation of ovules from the carpel margin meristem (CMM). The synergistic loss of ovule initiation observed in the seu ant double mutant suggests that SEU and ANT share overlapping functions during CMM development. However the molecular mechanism underlying this synergistic interaction is unknown. Using the ATH1 transcriptomics platform we identified transcripts that were differentially expressed in seu ant double mutant relative to wild type and single mutant gynoecia. In particular we sought to identify transcripts whose expression was dependent on the coordinated activities of the SEU and ANT gene products. Our analysis identifies a diverse set of transcripts that display altered expression in the seu ant double mutant tissues. The analysis of overrepresented Gene Ontology classifications suggests a preponderance of transcriptional regulators including multiple members of the REPRODUCTIVE MERISTEMS (REM) and GROWTH-REGULATING FACTOR (GRF) families are mis-regulated in the seu ant gynoecia. Our in situ hybridization analyses indicate that many of these genes are preferentially expressed within the developing CMM. This study is the first step toward a detailed description of the transcriptional regulatory hierarchies that control the development of the CMM and ovule initiation. Understanding the regulatory hierarchy controlled by SEU and ANT will clarify the molecular mechanism of the functional redundancy of these two genes and illuminate the developmental and molecular events required for CMM development and ovule initiation. PMID:22031826

  13. Measuring Critical Charges For Single-Event Upsets

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.

    1988-01-01

    Concept for determining susceptibility of integrated circuits to single-event upsets (SEU's) based on direct measurement of critical charge causing upset. Test circuit is modified version of standard complementary metal-oxide/semiconductor static cell. Contains six transistors, connected to form latch that retains state of cell set by input pulses. Makes possible to evaluate vulnerability to SEU during design and development of digital equipment.

  14. Single event upsets caused by solar energetic heavy ions

    SciTech Connect

    Tylka, A.J.; Adams, J.H. Jr.; Boberg, P.R.; Dietrich, W.F.; Smith, E.C.

    1996-12-01

    The authors calculate single event upset (SEU) rates due to protons, alphas, and heavier ions in two satellite systems for the major solar particle events of 1989--92, using a new and complete analysis of GOES proton data and high-energy heavy-ion fluences from the University of Chicago Cosmic Ray Telescope on IMP-8. These measurements cover the entire range of energies relevant to SEU studies and therefore overcome shortcomings of previous studies, which relied upon theoretical or semi-empirical estimates of high-energy heavy-ion spectra. They compare the results to the observed SEU rates in these events. The SEU rates in one device were overwhelmingly dominated by protons. However, even after taking into account uncertainties in the ground-test cross-section data, the authors find that at least {approximately}45% of the SEUs in the other device must have been caused by heavy ions. The results demonstrate that both protons and heavy ions must be considered in order to make a reliable assessment of SEU vulnerabilities. Furthermore, the GOES/Chicago database of solar particle events provides a basis for making accurate solar particle SEU calculations and credible worst-case estimates. In particular, measurements of the historic solar particle events of October 1989 are used in worst week and worst day environment models in CREME96, a revision of NRL`s Cosmic Ray Effects on MicroElectronics code.

  15. Single-event phenomena in GaAs devices and circuits

    SciTech Connect

    McMorrow, D.; Melinger, J.S.; Campbell, A.B. III; Weatherford, T.R.; Buchner, S.; Knudson, A.R.; Tran, L.H.

    1996-04-01

    The single-event upset (SEU) characteristics of GaAs devices and circuits are reviewed. GaAs FET-based integrated circuits (IC`s) are susceptible to upsets from both cosmic-ray heavy ions and protons trapped in the Earth`s radiation belts. The origin of the SEU sensitivity of GaAs IC`s is discussed in terms of both device-level and circuit-level considerations. At the device level, efficient charge-enhancement mechanisms through which more charge can be collected than is deposited by the ion have a significant negative impact on the SEU characteristics of GaAs IC`s. At the circuit level, different GaAs digital logic topologies exhibit different levels of sensitivity to SEU because of variations in parameters, including logic levels, capacitances, and the degree of gate or peripheral isolation. The operational and SEU characteristics of several different GaAs logic families are discussed. Recent advances in materials and processing that provide possible solutions to the SEU problem are addressed.

  16. Solar particle induced upsets in the TDRS-1 attitude control system RAM during the October 1989 solar particle events

    SciTech Connect

    Croley, D.R.; Garrett, H.B.; Murphy, G.B.; Garrard, T.L.

    1995-10-01

    The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEU`s calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU`s by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU`s. The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution. The number of calculated proton-induced SEU`s was 72, yielding a total of 248 predicted SEU`s, very close to the 243 observed SEU`s.

  17. Single-event-upset sensitivity analysis on low-swing drivers.

    PubMed

    Mahyuddin, Nor Muzlifah; Russell, Gordon

    2014-01-01

    Technology scaling relies on reduced nodal capacitances and lower voltages in order to improve performance and power consumption, resulting in significant increase in layout density, thus making these submicron technologies more susceptible to soft errors. Previous analysis indicates a significant improvement in SEU tolerance of the driver when the bias current is injected into the circuit but results in increase of power dissipation. Subsequently, other alternatives are considered. The impact of transistor sizes and temperature on SEU tolerance is tested. Results indicate no significant changes in Q(crit) when the effective transistor length is increased by 10%, but there is an improvement when high temperature and high bias currents are applied. However, this is due to other process parameters that are temperature dependent, which contribute to the sharp increase in Q(crit). It is found that, with temperature, there is no clear factor that can justify the direct impact of temperature on the SEU tolerance. Thus, in order to improve the SEU tolerance, high bias currents are still considered to be the most effective method in improving the SEU sensitivity. However, good trade-off is required for the low-swing driver in order to meet the reliability target with minimal power overhead. PMID:24782671

  18. Accelerators for critical experiments involving single-particle upset in solid-state microcircuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1985-01-01

    Charged-particle interactions in microelectronic circuit chips (integrated circuits) present a particularly insidious problem for solid-state electronic systems due to the generation of soft errors or single-particle event upset (SEU) by either cosmic rays or other radiation sources. Particle accelerators are used to provide both light and heavy ions in order to assess the propensity of integrated circuit chips for SEU. Critical aspects of this assessment involve the ability to analytically model SEU for the prediction of error rates in known radiation environments. In order to accurately model SEU, the measurement and prediction of energy deposition in the form of an electron-hole plasma generated along an ion track is of paramount importance. This requires the use of accelerators which allow for ease in both energy control (change of energy) and change of ion species. This and other aspects of ion-beam control and diagnostics (e.g., uniformity and flux) are of critical concern for the experimental verification of theoretical SEU models.

  19. Single-event upset tests on the readout electronics for the pixel detectors of the PANDA experiment

    NASA Astrophysics Data System (ADS)

    Mazza, G.; Balossino, I.; Calvo, D.; De Mori, F.; De Remigis, P.; Filippi, A.; Marcello, S.; Mignone, M.; Wheadon, R.; Zotti, L.; Candelori, A.; Mattiazzo, S.; Silvestrin, L.

    2014-01-01

    The Silicon Pixel Detector (SPD) of the future PANDA experiment is the closest one to the interaction point and therefore the sensor and its electronics are the most exposed to radiation. The Total Ionizing Dose (TID) issue has been addressed by the use of a deep-submicron technology (CMOS 0.13 μm) for the readout ASICs. While this technology is very effective in reducing radiation induced oxide damage, it is also more sensitive to Single Event Upset (SEU) effects due to their extremely reduced dimensions. This problem has to be addressed at the circuit level and generally leads to an area penalty. Several techniques have been proposed in literature with different trade-off between level of protection and cell size. A subset of these techniques has been implemented in the PANDA SPD ToPiX readout ASIC prototypes, ranging from DICE cells to triple redundancy. Two prototypes have been tested with different ion beams at the INFN-LNL facility in order to measure the SEU cross section. Comparative results of the SEU test will be shown, together with an analysis of the SEU tolerance of the various protection schemes and future plans for the SEU protection strategy which will be implemented in the next ToPiX prototype.

  20. Comparative study of MC-50 and ANITA neutron beams by using 55 nm SRAM

    NASA Astrophysics Data System (ADS)

    Baeg, Sanghyeon; Lee, Soonyoung; Bak, Geun Yong; Jeong, Hyunsoo; Jeon, Sang Hoon

    2012-09-01

    Single event upset (SEU) is mainly caused by neutrons in the terrestrial environment. In addition, SEU effects become more and more problematic as technology scales. It is, therefore, important to understand the SEU behaviors of semiconductor devices under neutron reactions. ANITA (atmospheric-like neutrons from thick target) in TSL (The Svedberg Laboratory), Sweden, resembles the neutron energy and flux spectrum to neutrons at the terrestrial level and are typically used to estimate the soft error rate (SER). On the other hand, the neutron energy and flux spectrum from the MC-50 cyclotron at KIRAMS (Korea Institute of Radiological & Medical Sciences) differs greatly from the atmospheric environment. The main objective of this work is finding the efficacy of the neutron beam at KIRAMS for a SEU analysis by using a comparative analysis; 55 nm SRAM is used to determine SEU difference under the beams at two different locations. Since MCU (multi-cell upset) is the dominant effect in emerging technologies with smaller critical charges, the MCU cross sections from the two different beam tests are compared.

  1. Measuring improved patient choice.

    PubMed

    Holmes-Rovner, M; Rovner, D R

    2000-08-01

    Patient decision support (PDS) tools or decision aids have been developed as adjuncts to the clinical encounter. Their aim is to support evidence-based patient choice. Clinical trials of PDS tools have used an array of outcome measures to determine efficacy, including knowledge, satisfaction, health status and consistency between patient choice and values. This paper proposes that the correlation between 'subjective expected utility' (SEU) and decision may be the best primary endpoint for trials. SEU is a measure usually used in behavioural decision theory. The paper first describes how decision support tools may use decision analysis to structure the presentation of evidence and guide patient decision-making. Uses of expected utility (EU) are suggested for evaluating PDS tools when improving population health status is the objective. SEU is the theoretically better measure when internal consistency of patient choices is the objective. PMID:11083037

  2. Single-event effects in resolver-to-digital converters

    SciTech Connect

    Buchner, S.; Tran, L.; Mann, J.; Turflinger, T.; McMorrow, D.; Campbell, A.; Dozier, C.

    1999-12-01

    Single-event effects (SEE's) in two resolver-to-digital converters (RDC's) have been studied using heavy ions and pulsed laser light. The important role of the pulsed laser in establishing single-event upset (SEU) and single-event latchup (SEL) levels prior to accelerator testing is described, as is its role in evaluating the test software and hardware and in gaining a better understanding of the origins of the SEE's. Results from pulsed-laser testing are in quantitative agreement with those from heavy-ion testing: the RDC-19220 is sensitive to both SEU's and SEL's whereas the AD2S80 is less sensitive to SEU's and immune to SEL.

  3. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    DOE PAGESBeta

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino J.; Black, Jeffrey D.; Marshall, P. W.; Reed, R. A.; McCurdy, M. W.; Weller, R. A.; et al

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, andmore » prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.« less

  4. Analysis of radiation induced effects in high-density commercial memories on-board Alsat-1: The impact of extreme solar particle events

    NASA Astrophysics Data System (ADS)

    Bentoutou, Youcef; Bensikaddour, El-Habib

    2015-06-01

    This paper presents a long-term study on radiation effects in non-hardened high density memory devices operating within the main on-board computer system of the Algerian microsatellite Alsat-1 in Low Earth Orbit (LEO). A statistical analysis of single-event upset (SEU) activity is presented for commercial SRAM devices, and their response to extreme solar events shows SEU rate significant increases correlated with high-energy protons (E > 100 MeV). Ground based neutron monitor data are used to illustrate the long-term correlation between galactic cosmic rays and Alsat-1 upsets. The short-term effects of energetic solar particles are illustrated with space environment data from GOES-11. The Alsat-1 observed SEU rates are compared to the predicted rates based on ground test data and environment models. The prediction results are in good agreement with in-flight data.

  5. Radiation-Hardened Electronics for Advanced Communications Systems

    NASA Technical Reports Server (NTRS)

    Whitaker, Sterling

    2015-01-01

    Novel approach enables high-speed special-purpose processors Advanced reconfigurable and reprogrammable communication systems will require sub-130-nanometer electronics. Legacy single event upset (SEU) radiation-tolerant circuits are ineffective at speeds greater than 125 megahertz. In Phase I of this project, ICs, LLC, demonstrated new base-level logic circuits that provide SEU immunity for sub-130-nanometer high-speed circuits. In Phase II, the company developed an innovative self-restoring logic (SRL) circuit and a system approach that provides high-speed, SEU-tolerant solutions that are effective for sub-130-nanometer electronics scalable to at least 22-nanometer processes. The SRL system can be used in the design of NASA's next-generation special-purpose processors, especially reconfigurable communication processors.

  6. Single-event effects in avionics

    SciTech Connect

    Normand, E.

    1996-04-01

    The occurrence of single-event upset (SEU) in aircraft electronics has evolved from a series of interesting anecdotal incidents to accepted fact. A study completed in 1992 demonstrated that SEU`s are real, that the measured in-flight rates correlate with the atmospheric neutron flux, and that the rates can be calculated using laboratory SEU data. Once avionics DEU was shown to be an actual effect, it had to be dealt with in avionics designs. The major concern is in random access memories (RAM`s), both static (SRAM`s) and dynamic (DRAM`s), because these microelectronic devices contain the largest number of bits, but other parts, such as microprocessors, are also potentially susceptible to upset. In addition, other single-event effects (SEE`s), specifically latch-up and burnout, can also be induced by atmospheric neutrons.

  7. Energy spectra and LET spectra of protons behind shielding

    NASA Astrophysics Data System (ADS)

    Katz, Sari; Barak, Joseph

    2014-08-01

    With the advent of devices sensitive to SEU due to direct ionization by protons, it became important to know the flux and energies of protons behind aluminum shielding or within satellites. We present new analytically derived expressions for the energy distribution of incident protons, after passing the shielding, and of secondary protons emitted within the shielding. The results are compared with those of the MULASSIS code. In some cases, like a satellite in a GCR orbit, the contribution of the secondary protons to SEU might be the dominant one. Proton energy-distributions behind shielding are proportional, at low energy values, to inverse proton-LET in aluminum. Their calculated LET-spectra in silicon can be used for evaluating SEU-rate in space. The analytic expressions presented here can be useful in calculating the influence of shielding on other incident ions and secondary ions.

  8. Development of a Nuclear Reaction Database on Silicon for Simulation of Neutron-Induced Single-Event Upsets in Microelectronics and its Application

    SciTech Connect

    Watanabe, Yukinobu; Kodama, Akihiro; Tukamoto, Yasuyuki; Nakashima, Hideki

    2005-05-24

    We have developed a cross-section database for neutron-induced reactions on 28Si in the energy range between 2 MeV and 3 GeV in order to analyze single-event upsets (SEUs) phenomena induced by cosmic-ray neutrons in microelectronic devices. A simplified spherical device model is proposed for simulation of the initial processes of SEUs. The model is applied to SEU cross-section calculations for semiconductor memory devices. The calculated results are compared with measured SEU cross sections and the other simulation result. The dependence of SEU cross sections on incident neutron energy and secondary ions having the most important effects on SEUs are discussed.

  9. The single event upset response of the analog devices, ADSP2100A, digital signal processor

    SciTech Connect

    Harboe-Sorensen, R.; Seran, H.; Armbruster, P.; Adams, L. )

    1992-06-01

    This paper presents the results of a radiation evaluation program carried out by ESTEC on the Analog Devices, ADSP2100A, which is a single chip microprocessor optimized for 12.5 Mips Digital Signal Processing (DSP). Single Event Upset/Latch-up (SEU/SEL) testing using Californium-252 was the primary aim of this program, however, accelerator heavy ion and proton SEU/SEL data as well as total ionizing dose data are also presented. The hardware design and software used will be described and details of the various tests and test facilities will be given. Finally, the authors report on the use of the SEU data for the calculation of expected in-orbit upset rates using the CREME suite of programs.

  10. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    SciTech Connect

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino J.; Black, Jeffrey D.; Marshall, P. W.; Reed, R. A.; McCurdy, M. W.; Weller, R. A.; Pellish, J. A.; Rodbell, K. P.; Gordon, M. S.

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.

  11. Heavy-ion induced single-event upset in integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1991-01-01

    The cosmic ray environment in space can affect the operation of Integrated Circuit (IC) devices via the phenomenon of Single Event Upset (SEU). In particular, heavy ions passing through an IC can induce sufficient integrated current (charge) to alter the state of a bistable circuit, for example a memory cell. The SEU effect is studied in great detail in both static and dynamic memory devices, as well as microprocessors fabricated from bipolar, Complementary Metal Oxide Semiconductor (CMOS) and N channel Metal Oxide Semiconductor (NMOS) technologies. Each device/process reflects its individual characteristics (minimum scale geometry/process parameters) via a unique response to the direct ionization of electron hole pairs by heavy ion tracks. A summary of these analytical and experimental SEU investigations is presented.

  12. Observations of single-event upsets in non-hardened high-density SRAMs in sun-synchronous orbit

    NASA Astrophysics Data System (ADS)

    Underwood, C. I.; Ward, J. W.; Dyer, C. S.; Sims, A. J.

    1992-12-01

    Observations of single-event upset (SEU) activity in nonhardened static and dynamic RAMs of both low (16-kb) and high (256-kb, 1-Mb), density are presented for a family of small spacecraft in low-earth, near-polar, sun-synchronous orbits. The observation of single-event multiple-bit upset (MBU) in these devices is discussed, and the implications of such events for error-protection coding schemes are examined. Contrary to expectations, the 1-Mb static RAMs (SRAMs) are more resilient to SEU than the 246-kb SRAMs, and one type of commercial 1-Mb SRAM shows a particularly low error rate.

  13. Dual-doped thermographic phosphor particles as surrogates for GFP-labelled cells in tests of cytometric neurocatheters

    SciTech Connect

    Allison, Stephen W; Gillies, George

    2010-01-01

    We investigated the laser-induced fluorescence of particles of a compound thermographic phosphor La2O2S:Eu (1%) and Gd2O2S:Eu (1%), to see if they can serve as a surrogate for cells transfected with the green fluorescent protein, in tests of neurocatheters used for intraparenchymal cell delivery. At an excitation wavelength of 337 nm and a concentration of 2x106 particles ml-1, the resulting slurries produced fluorescence intensities at 625 nm that were within a factor of two of those produced by similar number densities of relevant cells, thus suggesting the utility of this approach.

  14. Cosmic ray simulation and testing program

    NASA Technical Reports Server (NTRS)

    Kolasinski, W. A.; Koga, R.; King, C. G.; Imamoto, S. I.

    1985-01-01

    Single event upset (SEU) and latchup vulnerabilities were determined for a number of parts of interest to NASA space programs. In cases where a threshold linear energy transfer (LET) for SEU could be measured, an upset rate in a low inclination Space Shuttle orbit was computed. The predicted upset rates are extremely low, except for the devices with LET thresholds below the geomagnetic cutoff for altitude and inclination of the Space Shuttle orbit. While some of the devices do exhibit latchup, the cross sections and threshold LETs are such that the risk associated with flying these devices in low, near equatorial orbits is small if not negligible.

  15. Radiation hardness evaluations of 65 nm fully depleted silicon on insulator and bulk processes by measuring single event transient pulse widths and single event upset rates

    NASA Astrophysics Data System (ADS)

    Furuta, Jun; Sonezaki, Eiji; Kobayashi, Kazutoshi

    2015-04-01

    We measure single event transient (SET) pulse widths on inverter chains and single event upset (SEU) rates on flip-flops (FFs) fabricated in 65 nm fully depleted silicon on insulator (FD-SOI) and bulk processes. The layout designs of test chips are strictly identical between their processes besides buried oxide (BOX) layers. Experimental results show that neutron-induced SEU and SET rates in the FD-SOI process are 230× and 450× lower than those in the bulk process, respectively.

  16. Reprogrammable field programmable gate array with integrated system for mitigating effects of single event upsets

    NASA Technical Reports Server (NTRS)

    Ng, Tak-kwong (Inventor); Herath, Jeffrey A. (Inventor)

    2010-01-01

    An integrated system mitigates the effects of a single event upset (SEU) on a reprogrammable field programmable gate array (RFPGA). The system includes (i) a RFPGA having an internal configuration memory, and (ii) a memory for storing a configuration associated with the RFPGA. Logic circuitry programmed into the RFPGA and coupled to the memory reloads a portion of the configuration from the memory into the RFPGA's internal configuration memory at predetermined times. Additional SEU mitigation can be provided by logic circuitry on the RFPGA that monitors and maintains synchronized operation of the RFPGA's digital clock managers.

  17. The Reliability of FPGA circuit designs in the presence of radiation induced configuration upsets

    SciTech Connect

    Wirthlin, M. J.; Johnson, E.; Rollins, N.; Caffrey, M. P.; Graham, P. S.

    2003-01-01

    FPGAs are an appealing solution for space-based remote sensing applications. However, an a low-earth orbit, FPGAs are susceptible t o Single-Event Upsets (SEUs). In an effort to understand the effects of SEUs, an SEU simulator based on the SLAAC-1V computing board has been developed. This simulator artifically upsets the conjiguration memory of an FPGA and measures its impact on FPGA designs. The accuracy of this simulation environment has been verified using ground-based radiation testing. This sim{approx}ulataon tool is being used to characterize the reliabilitg of SEU mitigation techniques for PI'GAs.

  18. Use of new ENDF/B-VI proton and neutron cross sections for single event upset calculations

    SciTech Connect

    Chadwick, M.B.; Normand, E.

    1999-12-01

    Single-event upsets (SEU) in microelectronics are calculated from newly-developed silicon nuclear reaction recoil data for incident protons and neutrons with energies up to 150 MeV. This paper focuses on the nuclear reaction physics that is important for calculating recoil spectra, and burst generation rate spectra. Comparisons are made with previous results, obtained from intranuclear cascade calculations as well as from previous ENDF data below 20 MeV, to demonstrate new features in the present calculations. Calculated SEU cross sections are compared with measured data.

  19. Method for characterizing the upset response of CMOS circuits using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G. (Inventor); Blaes, Brent R. (Inventor); Nixon, Robert H. (Inventor); Soli, George A. (Inventor)

    1995-01-01

    A method for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. A technique utilizing test structures to quickly and inexpensively characterize the SEU sensitivity of standard cell latches intended for use in a space environment. This bench-level approach utilizes alpha particles to induce upsets in a low LET sensitive 4-k bit test SRAM. This SRAM consists of cells that employ an offset voltage to adjust their upset sensitivity and an enlarged sensitive drain junction to enhance the cell's upset rate.

  20. Predictions for proton and heavy ions induced SEUs in 65 nm SRAMs

    NASA Astrophysics Data System (ADS)

    Shougang, Du; Suge, Yue; Hongxia, Liu; Long, Fan; Hongchao, Zheng

    2015-11-01

    We report on irradiation induced single event upset (SEU) by high-energy protons and heavy ions. The experiments were performed at the Paul Scherer Institute, and heavy ions at the SEE irradiating Facility on the HI-13 Tandem Accelerator in China's Institute of Atomic Energy, Beijing and the Heavy Ion Research Facility in Lanzhou in the Institute of Modern Physics, Chinese Academy of Sciences. The results of proton and heavy ions induced (SEU) in 65 nm bulk silicon CMOS SRAMS are discussed and the prediction on several typical orbits are presented.

  1. Modeling of single-event upset in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1983-01-01

    The results of work done on the quantitative characterization of single-event upset (SEU) in bipolar random-access memories (RAMs) have been obtained through computer simulation of SEU in RAM cells that contain circuit models for bipolar transistors. The models include current generators that emulate the charge collected from ion tracks. The computer simulation results are compared with test data obtained from a RAM in a bipolar microprocessor chip. This methodology is applicable to other bipolar integrated circuit constructions in addition to RAM cells.

  2. A radiation-hardened 16/32-bit microprocessor

    SciTech Connect

    Hass, K.J.; Treece, R.K.; Giddings, A.E.

    1989-01-01

    A radiation-hardened 16/32-bit microprocessor has been fabricated and tested. Our initial evaluation has demonstrated that it is functional after a total gamma dose of 5Mrad(Si) and is immune to SEU from Krypton ions. 3 refs., 2 figs.

  3. Single event soft error in advanced integrated circuit

    NASA Astrophysics Data System (ADS)

    Yuanfu, Zhao; Suge, Yue; Xinyuan, Zhao; Shijin, Lu; Qiang, Bian; Liang, Wang; Yongshu, Sun

    2015-11-01

    As technology feature size decreases, single event upset (SEU), and single event transient (SET) dominate the radiation response of microcircuits. Multiple bit upset (MBU) (or multi cell upset) effects, digital single event transient (DSET) and analogue single event transient (ASET) cause serious problems for advanced integrated circuits (ICs) applied in a radiation environment and have become a pressing issue. To face this challenge, a lot of work has been put into the single event soft error mechanism and mitigation schemes. This paper presents a review of SEU and SET, including: a brief historical overview, which summarizes the historical development of the SEU and SET since their first observation in the 1970's; effects prominent in advanced technology, which reviews the effects such as MBU, MSET as well as SET broadening and quenching with the influence of temperature, device structure etc.; the present understanding of single event soft error mechanisms, which review the basic mechanism of single event generation including various component of charge collection; and a discussion of various SEU and SET mitigation schemes divided as circuit hardening and layout hardening that could help the designer meet his goals.

  4. Novel functional roles for PERIANTHIA and SEUSS during floral organ identity specification, floral meristem termination, and gynoecial development

    PubMed Central

    Wynn, April N.; Seaman, Andrew A.; Jones, Ashley L.; Franks, Robert G.

    2014-01-01

    The gynoecium is the female reproductive structure of angiosperm flowers. In Arabidopsis thaliana the gynoecium is composed of two carpels that are fused into a tube-like structure. As the gynoecial primordium arises from the floral meristem, a specialized meristematic structure, the carpel margin meristem (CMM), develops from portions of the medial gynoecial domain. The CMM is critical for reproductive competence because it gives rise to the ovules, the precursors of the seeds. Here we report a functional role for the transcription factor PERIANTHIA (PAN) in the development of the gynoecial medial domain and the formation of ovule primordia. This function of PAN is revealed in pan aintegumenta (ant) as well as seuss (seu) pan double mutants that form reduced numbers of ovules. Previously, PAN was identified as a regulator of perianth organ number and as a direct activator of AGAMOUS (AG) expression in floral whorl four. However, the seu pan double mutants display enhanced ectopic AG expression in developing sepals and the partial transformation of sepals to petals indicating a novel role for PAN in the repression of AG in floral whorl one. These results indicate that PAN functions as an activator or repressor of AG expression in a whorl-specific fashion. The seu pan double mutants also display enhanced floral indeterminacy, resulting in the formation of “fifth whorl” structures and disruption of WUSCHEL (WUS) expression patterns revealing a novel role for SEU in floral meristem termination. PMID:24778638

  5. Radiation Hardening of Computers

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Smith, L. S.; Zoutendyk, J. A.; Giddings, A. E.; Hewlett, F. W.; Treece, R. K.

    1986-01-01

    Single-event upsets reduced by use of oversize transistors. Computers made less susceptible to ionizing radiation by replacing bipolar integrated circuits with properly designed, complementary metaloxide-semiconductor (CMOS) circuits. CMOS circuit chips made highly resistant to single-event upset (SEU), especially when certain feedback resistors are incorporated. Redesigned chips also consume less power than original chips.

  6. SEE induced in SRAM operating in a superconducting electron linear accelerator environment

    NASA Astrophysics Data System (ADS)

    Makowski, D.; Mukherjee, Bhaskar; Grecki, M.; Simrock, Stefan

    2005-02-01

    Strong fields of bremsstrahlung photons and photoneutrons are produced during the operation of high-energy electron linacs. Therefore, a mixed gamma and neutron radiation field dominates the accelerators environment. The gamma radiation induced Total Ionizing Dose (TID) effect manifests the long-term deterioration of the electronic devices operating in accelerator environment. On the other hand, the neutron radiation is responsible for Single Event Effects (SEE) and may cause a temporal loss of functionality of electronic systems. This phenomenon is known as Single Event Upset (SEU). The neutron dose (KERMA) was used to scale the neutron induced SEU in the SRAM chips. Hence, in order to estimate the neutron KERMA conversion factor for Silicon (Si), dedicated calibration experiments using an Americium-Beryllium (241Am/Be) neutron standard source was carried out. Single Event Upset (SEU) influences the short-term operation of SRAM compared to the gamma induced TID effect. We are at present investigating the feasibility of an SRAM based real-time beam-loss monitor for high-energy accelerators utilizing the SEU caused by fast neutrons. This paper highlights the effects of gamma and neutron radiations on Static Random Access Memory (SRAM), placed at selected locations near the Superconducting Linear Accelerator driving the Vacuum UV Free Electron Laser (VUVFEL) of DESY.

  7. The Education of Refugees in Africa: The Role of Distance and Open Learning.

    ERIC Educational Resources Information Center

    Dodds, Tony

    1988-01-01

    Description of education services to refugees in Africa focuses on three case studies: Institute of In-Service Teacher Training (IITT) in Somalia; Sudan Extension Unit (SEU); and Namibian Extension Unit (NEU) in Angola and Zambia. Highlights include refugee problems, the relevance of distance and open learning approaches, and international…

  8. Effects of Computer-Assisted Instruction in Using Formal Decision-Making Strategies to Choose a College Major.

    ERIC Educational Resources Information Center

    Mau, Wei-Cheng; Jepsen, David A.

    1992-01-01

    Compared decision-making strategies and college major choice among 113 first-year students assigned to Elimination by Aspects Strategy (EBA), Subjective Expected Utility Strategy (SEU), and control groups. "Rational" EBA students scored significantly higher on choice certainty; lower on choice anxiety and career indecision than "rational"…

  9. Overcoming scaling concerns in a radiation-hardening CMOS technology

    SciTech Connect

    Maimon, J.; Haddad, N.

    1999-12-01

    Scaling efforts to develop an advanced radiation-hardened CMOS process to support a 4M SRAM are described. Issues encountered during scaling of transistor, isolation, and resistor elements are discussed, as well as the solutions used to overcome these issues. Transistor data, total dose radiation results, and the performance of novel resistors for prevention of single event upsets (SEU) are presented.

  10. Reliability design of CMOS image sensor for space applications

    NASA Astrophysics Data System (ADS)

    Xie, Ning; Chen, Shijun; Chen, Yongping

    2013-08-01

    In space applications, sensors work in very harsh space environment. Thus the reliability design must be carefully considered. This paper addresses the techniques which effectively increase the reliability of CMOS image sensors. A radiation tolerant pixel design which is implemented in a sun tracker sensor is presented. Measurement results of total dose radiation, SEL, SEU, etc prove the radiation immunity of the sensor.

  11. Alpha-particle emissivity screening of materials used for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Gordon, Michael; Rodbell, Kenneth

    2015-03-01

    Single-Event Upsets (SEU's) in semiconductor memory and logic devices continue to be a reliability issue in modern CMOS devices. SEU's result from deposited charge in the Si devices caused by the passage of ionizing radiation. With technology scaling, the device area decreases, but the critical charge required to flip bits decreases as well. The interplay between both determines how the SEU rate scales with shrinking device geometries and dimensions. In order to minimize the alpha-particle component of SEU, the radiation in the device environment has to be at the Ultra-Low Alpha (ULA) activity levels, e.g. less than 2 α/khr-cm2. Most detectors have background levels that are significantly larger than that level which makes making these measurements difficult and time consuming. A new class of alpha particle detector, utilizing pulse shape discrimination, is now available which allows one to make measurements quickly with ultra-low detector background. This talk will discuss what is involved in making alpha particle measurements of materials in the ULA activity levels, in terms of calibration, radon adsorption mitigation, the time required for obtaining reasonable statistics and comparisons to other detectors.

  12. SRAM Based Re-programmable FPGA for Space Applications

    NASA Technical Reports Server (NTRS)

    Wang, J. J.; Sun, J. S.; Cronquist, B. E.; McCollum, J. L.; Speers, T. M.; Plants, W. C.; Katz, R. B.

    1999-01-01

    An SRAM (static random access memory)-based reprogrammable FPGA (field programmable gate array) is investigated for space applications. A new commercial prototype, named the RS family, was used as an example for the investigation. The device is fabricated in a 0.25 micrometers CMOS technology. Its architecture is reviewed to provide a better understanding of the impact of single event upset (SEU) on the device during operation. The SEU effect of different memories available on the device is evaluated. Heavy ion test data and SPICE simulations are used integrally to extract the threshold LET (linear energy transfer). Together with the saturation cross-section measurement from the layout, a rate prediction is done on each memory type. The SEU in the configuration SRAM is identified as the dominant failure mode and is discussed in detail. The single event transient error in combinational logic is also investigated and simulated by SPICE. SEU mitigation by hardening the memories and employing EDAC (error detection and correction) at the device level are presented. For the configuration SRAM (CSRAM) cell, the trade-off between resistor de-coupling and redundancy hardening techniques are investigated with interesting results. Preliminary heavy ion test data show no sign of SEL (single event latch-up). With regard to ionizing radiation effects, the increase in static leakage current (static I(sub CC)) measured indicates a device tolerance of approximately 50krad(Si).

  13. Single event effects and laser simulation studies

    NASA Technical Reports Server (NTRS)

    Kim, Q.; Schwartz, H.; Mccarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The single event upset (SEU) linear energy transfer threshold (LETTH) of radiation hardened 64K Static Random Access Memories (SRAM's) was measured with a picosecond pulsed dye laser system. These results were compared with standard heavy ion accelerator (Brookhaven National Laboratory (BNL)) measurements of the same SRAM's. With heavy ions, the LETTH of the Honeywell HC6364 was 27 MeV-sq cm/mg at 125 C compared with a value of 24 MeV-sq cm/mg obtained with the laser. In the case of the second type of 64K SRAM, the IBM640lCRH no upsets were observed at 125 C with the highest LET ions used at BNL. In contrast, the pulsed dye laser tests indicated a value of 90 MeV-sq cm/mg at room temperature for the SEU-hardened IBM SRAM. No latchups or multiple SEU's were observed on any of the SRAM's even under worst case conditions. The results of this study suggest that the laser can be used as an inexpensive laboratory SEU prescreen tool in certain cases.

  14. Neutron induced soft errors in CMOS memories under reduced bias

    SciTech Connect

    Hazucha, P.; Svensson, C.; Johansson, K.

    1998-12-01

    A custom designed 16 kbit CMOS memory was irradiated by 14 MeV neutrons and 100 MeV neutrons. SEU cross sections were evaluated under different supply voltages. The cross section values are compared to those predicted by the BGR model.

  15. Decisions Under Uncertainty III: Rationality Issues, Sex Stereotypes, and Sex Role Appropriateness.

    ERIC Educational Resources Information Center

    Bonoma, Thomas V.

    The explanatory cornerstone of most currently viable social theories is a strict cost-gain assumption. The clearest formal explication of this view is contained in subjective expected utility models (SEU), in which individuals are assumed to scale their subjective likelihood estimates of decisional consequences and the personalistic worth or…

  16. Adolescent Contraceptive Use: Models, Research, and Directions.

    ERIC Educational Resources Information Center

    Whitley, Bernard E., Jr.; Schofield, Janet Ward

    Both the career model and the decision model have been proposed to explain patterns of contraceptive use in teenagers. The career model views contraceptive use as a symbol of a woman's sexuality and implies a clear decision to be sexually active. The decision model is based on the subjective expected utility (SEU) theory which holds that people…

  17. Single Event Testing on Complex Devices: Test Like You Fly Versus Test-Specific Design Structures

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Label, Kenneth

    2016-01-01

    We present a mechanism for evaluating complex digital systems targeted for harsh radiation environments such as space. Focus is limited to analyzing the single event upset (SEU) susceptibility of designs implemented inside Field Programmable Gate Array (FPGA) devices. Tradeoffs are provided between application-specific versus test-specific test structures.

  18. Teenage Pregnancy and Sex and Relationship Education: Myths and (Mis)conceptions

    ERIC Educational Resources Information Center

    Vincent, Kerry

    2007-01-01

    This paper explores the role of sex and relationship education (SRE) in reducing teenage pregnancy rates. It critically examines some of the assumptions underlying the emphasis placed on SRE within the teenage pregnancy strategy ( SEU, 1999)--in particular, the view that ignorance of sexual matters plays a key part in teenage conception. An…

  19. Evaluation of an Ultra-Low Power Reed Solomon Encoder for NASA's Space Technology 5 Mission

    NASA Technical Reports Server (NTRS)

    Li, K. E.; Xapsos, M. A.; Poivey, C.; LaBel, K. A.; Stone, R. F.; Yeh, P-S.; Gambles, J.; Hass, J.; Maki, G.; Marguia, J.

    2003-01-01

    This viewgraph presentation provides information on radiation tests on encoders intended for a constellation of microsatellites. The encoders use CMOS Ultra-Low Power Radiation Tolerant (CULPRiT) technology. The presentation addresses power consumption, radiation dosage, and Single Event Upset (SEU).

  20. Single event effect characterization of the mixed-signal ASIC developed for CCD camera in space use

    NASA Astrophysics Data System (ADS)

    Nakajima, Hiroshi; Fujikawa, Mari; Mori, Hideki; Kan, Hiroaki; Ueda, Shutaro; Kosugi, Hiroko; Anabuki, Naohisa; Hayashida, Kiyoshi; Tsunemi, Hiroshi; Doty, John P.; Ikeda, Hirokazu; Kitamura, Hisashi; Uchihori, Yukio

    2013-12-01

    We present the single event effect (SEE) tolerance of a mixed-signal application-specific integrated circuit (ASIC) developed for a charge-coupled device camera onboard a future X-ray astronomical mission. We adopted proton and heavy ion beams at HIMAC/NIRS in Japan. The particles with high linear energy transfer (LET) of 57.9 MeV cm2/mg is used to measure the single event latch-up (SEL) tolerance, which results in a sufficiently low cross-section of σSEL<4.2×10-11 cm2/(Ion×ASIC). The single event upset (SEU) tolerance is estimated with various kinds of species with wide range of energy. Taking into account that a part of the protons creates recoiled heavy ions that have higher LET than that of the incident protons, we derived the probability of SEU event as a function of LET. Then the SEE event rate in a low-earth orbit is estimated considering a simulation result of LET spectrum. SEL rate is below once per 49 years, which satisfies the required latch-up tolerance. The upper limit of the SEU rate is derived to be 1.3×10-3 events/s. Although the SEU events cannot be distinguished from the signals of X-ray photons from astronomical objects, the derived SEU rate is below 1.3% of expected non-X-ray background rate of the detector and hence these events should not be a major component of the instrumental background.

  1. The transcriptional regulator SsuR activates expression of the Corynebacterium glutamicum sulphonate utilization genes in the absence of sulphate.

    PubMed

    Koch, Daniel J; Rückert, Christian; Albersmeier, Andreas; Hüser, Andrea T; Tauch, Andreas; Pühler, Alfred; Kalinowski, Jörn

    2005-10-01

    In a recent study, the putative regulatory gene cg0012 was shown to belong to the regulon of McbR, a global transcriptional regulator of sulphur metabolism in Corynebacterium glutamicum ATCC 13032. A deletion of cg0012, now designated ssuR (sulphonate sulphur utilization regulator), led to the mutant strain C. glutamicum DK100, which was shown to be blocked in the utilization of sulphonates as sulphur sources. According to DNA microarray hybridizations, transcription of the ssu and seu genes, encoding the sulphonate utilization system of C. glutamicum, was considerably decreased in C. glutamicum DK100 when compared with the wild-type strain. Electrophoretic mobility shift assays with purified SsuR protein demonstrated that the upstream regions of ssuI, seuABC, ssuD2 and ssuD1CBA contain SsuR binding sites. A nucleotide sequence alignment of the four DNA fragments containing the SsuR binding sites revealed a common 21 bp motif consisting of T-, GC- and A-rich domains. Mapping of the transcriptional start sites in front of ssuI, seuABC, ssuD2 and ssuD1CBA indicated that the SsuR binding sites are located directly upstream of identified promoter sequences and that the ssu genes are expressed by leaderless transcripts. Binding of the SsuR protein to its operator was shown to be diminished in vitro by the effector substance sulphate and its direct assimilation products adenosine 5'-phosphosulphate, sulphite and sulphide. Real-time reverse transcription polymerase chain reaction experiments verified that the expression of the ssu and seu genes was also repressed in vivo by the presence of sulphate or sulphite. Therefore, the regulatory protein SsuR activates the expression of the ssu and seu genes in C. glutamicum in the absence of the preferred sulphur source sulphate. PMID:16194234

  2. Reconfigurable computing in space: from current technology to reconfigurable systems-on-a-chip.

    SciTech Connect

    Graham, R. C.; Caffrey, M. P.; Johnson, D. E.; Wirthlin, M. J.

    2002-01-01

    The performance, in-system reprogrammability, flexibility, and reduced costs of SRAM-based FPGAs make them very interesting for high-speed, on-orbit data processing, but, because the current generation of radiation-tolerant SRAM-based FPGAs are derived directly from COTS versions of the chips, several issues must be dealt with for space, including SEU sensitivities, power consumption, thermal problems, and support logic. This paper will discuss Los Alamos National Laboratory's approach to using the Xilinx XQVR1000 FPGAs for on-orbit processing in the Cibola Flight Experiment (CFE) as well as the possibilities and challenges of using newer, system-on-a-reprogrammable-chip FPGAs, such as Virtex I1 Pro, in space-based reconfigurable computing. The reconfigurable computing payload for CFE includes three processing boards, each having three radiation-tolerant Xilinx XQVRl 000 FPGAs. The reconfigurable computing architecture for this project is intended for in-flight, real-time processing of two radio fi-equency channels, each producing 12-bit samples at 100 million samples/second. In this system, SEU disruptions in data path operations can be tolerated while disruptions in the control path are much less tolerable. With this system in mind, LANL has developed an SEU management scheme with strategies for handling upsets in all of the FPGA resources known to be sensitive to radiation-induced SEUs. While mitigation schemes for many resources will be discussed, the paper will concentrate on SEU management strategies and tools developed at LANL for the configuration bitstream and 'half latches'. To understand the behavior of specific designs under SEUs in the configuration bitstream, LANL and Brigham Young University have developed an SEU simulator using ISI's SLAACl-V reconfigurable computing board. The simulator can inject single-bit upsets into a design's configuration bitstream to simulate SEUs and observe how these simulated SEUs affect the design's operation. Using fast

  3. NASA Structure and Evolution of the Universe Theme: Science Overview

    NASA Technical Reports Server (NTRS)

    White, Nicholas E.; Margon, Bruce

    2001-01-01

    The NASA Office of Space Science Structure and Evolution of the Universe (SEU) theme covers a wide variety of scientific investigations, from the nearest bodies to the farthest observable distances just after the time of the Big Bang. SEU supports experiments that sense radiation of all wavelengths, together with particle and gravitational wave detection. Recently completed road mapping and strategic planning exercises have identified a number of near- and medium-term space initiatives for the 2003-2023 time frame. Each of these experiments pushes the state of the art technically, but will return incredible new insights on the formation and evolution of the universe, as well as probe fundamental laws of physics in regimes never before tested. The scientific goals and technological highlights of each mission are described.

  4. Eu(3+) doped gadolinium oxysulfide (Gd(2)O(2)S) nanostructures-synthesis and optical and electronic properties.

    PubMed

    Thirumalai, J; Chandramohan, R; Divakar, R; Mohandas, E; Sekar, M; Parameswaran, P

    2008-10-01

    One-dimensional Eu(3+) doped gadolinium oxysulfide (Gd(2)O(2)S:Eu(3+)) nanotubes/nanorods have been synthesized via precursors of Gd(OH)(3) nanostructures using a hydrothermal technique. The blue-shifts in the optical spectra for the Gd(2)O(2)S:Eu(3+) system corresponding to the fundamental absorption and Eu(3+)-X(2-) ligand (X =  O/S) charge transfer bands (CTBs) are significant (∼0.22-0.36 eV) with respect to the bulk counterpart. The nanotubes are good candidates for investigating the size-induced electrical and optical properties of functional oxysulfides. In order to identify the origin and nature of the electronic transitions observed in the visible region, optical and photo-induced impedance measurements have been extended to the nanotubes in this report. PMID:21832604

  5. The Cibola flight experiment

    SciTech Connect

    Caffrey, Michael Paul; Nelson, Anthony; Salazar, Anthony; Roussel - Dupre, Diane; Katko, Kim; Palmer, Joseph; Robinson, Scott; Wirthlin, Michael; Howes, William; Richins, Daniel

    2009-01-01

    The Cibola Flight Experiment (CFE) is an experimental small satellite carrying a reconfigurable processing instrument developed at the Los Alamos National Laboratory that demonstrates the feasibility of using FPGA-based high-performance computing for sensor processing in the space environment. The CFE satellite was launched on March 8, 2007 in low-earth orbit and has operated extremely well since its deployment. The nine Xilinx Virtex FPGAs used in the payload have been used for several high-throughput sensor processing applications and for single-event upset (SEU) monitoring and mitigation. This paper will describe the CFE system and summarize its operational results. In addition, this paper will describe the results from several SEU detection circuits that were performed on the spacecraft.

  6. NASA's Structure and Evolution of the Universe focal plane directions

    NASA Astrophysics Data System (ADS)

    Schwartz, P. C.

    2004-01-01

    The SEU theme encompasses an extremely diverse area of space science. Recent roadmapping efforts been devoted to prioritizing science challenges rather than defining all that is contained in the SEU theme. The highest priorities are the Big Bang and a look at Black Holes and the regions near them. To support these challenges the following technologies are of high priority: Cryogenic Systems, Formation Flying, High Performance Optics: Mid- and Far-IR Optics, X-Ray/UV optics, Advanced Detectors: X-ray and Submm/Far IR, Energy resolving detectors and Large Format Arrays. The initiative, Beyond Einstein, includes baseline missions that utilize technologies that are generally at a laboratory proof of concept level. Technology development plans are established for the flagship missions: Con-X and LISA. Conceptual development is still progressing for some Einstein Probe missions. Vision missions are still in conceptual development.

  7. Electronics Shielding and Reliability Design Tools

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; ONeill, P. M.; Zang, Thomas A., Jr.; Pandolf, John E.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.

    2006-01-01

    It is well known that electronics placement in large-scale human-rated systems provides opportunity to optimize electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within the Shuttle avionic computers during a typical mission. An order of magnitude larger SEU rate would occur without careful placement in the Shuttle design. These results used basic physics models (linear energy transfer (LET), track structure, Auger recombination) combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on human-rated systems provides opportunity to minimize radiation impact on critical and non-critical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements.

  8. SEE Sensitivity Analysis of 180 nm NAND CMOS Logic Cell for Space Applications

    NASA Astrophysics Data System (ADS)

    Sajid, Muhammad

    2016-07-01

    This paper focus on Single Event Effects caused by energetic particle strike on sensitive locations in CMOS NAND logic cell designed in 180nm technology node to be operated in space radiation environment. The generation of SE transients as well as upsets as function of LET of incident particle has been determined for logic devices onboard LEO and GEO satellites. The minimum magnitude pulse and pulse-width for threshold LET was determined to estimate the vulnerability /susceptibility of device for heavy ion strike. The impact of temperature, strike location and logic state of NAND circuit on total SEU/SET rate was estimated with physical mechanism simulations using Visual TCAD, Genius, runSEU program and Crad computer codes.

  9. Redundant single event upset supression system

    DOEpatents

    Hoff, James R.

    2006-04-04

    CMOS transistors are configured to operate as either a redundant, SEU-tolerant, positive-logic, cross-coupled Nor Gate SR-flip flop or a redundant, SEU-tolerant, negative-logic, cross-coupled Nand Gate SR-flip flop. The register can operate as a memory, and further as a memory that can overcome the effects of radiation. As an SR-flip flop, the invention can be altered into any known type of latch or flip-flop by the application of external logic, thereby extending radiation tolerance to devices previously incapable of radiation tolerance. Numerous registers can be logically connected and replicated thereby being electronically configured to operate as a redundant circuit.

  10. 1986 Annual Conference on Nuclear and Space Radiation Effects, 23rd, Providence, RI, July 21-23, 1986, Proceedings

    NASA Technical Reports Server (NTRS)

    Ellis, Thomas D. (Editor)

    1986-01-01

    The present conference on the effects of nuclear and space radiation on electronic hardware gives attention to topics in the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, electronic device radiation hardness assurance, SOI/SOS radiation effects, spacecraft charging and space radiation, IC radiation effects and hardening, single-event upset (SEU) phenomena and hardening, and EMP/SGEMP/IEMP phenomena. Specific treatments encompass the generation of interface states by ionizing radiation in very thin MOS oxides, the microdosimetry of meson energy deposited on 1-micron sites in Si, total dose radiation and engineering studies, plasma interactions with biased concentrator solar cells, the transient imprint memory effect in MOS memories, mechanisms leading to SEU, and the vaporization and breakdown of thin columns of water.

  11. Laser-induced fluorescence of phosphors for remote cryogenic thermometry

    NASA Technical Reports Server (NTRS)

    Beshears, D. L.; Capps, G. J.; Cates, M. R.; Simmons, C. M.; Schwenterly, S. W.

    1990-01-01

    Remote cryogenic temperature measurements can be made by inducing fluorescence in phosphors with temperature-dependent emissions and measuring the emission lifetimes. The thermographic phosphor technique can be used for making precision, noncontact, cryogenic-temperature measurements in electrically hostile environments, such as high dc electric or magnetic fields. The National Aeronautics and Space Administration is interested in using these thermographic phosphors for mapping hot spots on cryogenic tank walls. Europium-doped lanthanum oxysulfide (La2O2S:Eu) and magnesium fluorogermanate doped with manganese (Mg4FGeO6:Mn) are suitable for low-temperature surface thermometry. Several emission lines, excited by a 337-nm ultraviolet laser, provide fluorescence lifetimes having logarithmic dependence with temperature from 4 to above 125 K. A calibration curve for both La2O2S:Eu and Mg4FGeO6:Mn is presented, as well as emission spectra taken at room temperature and 11 K.

  12. Analysis of single-event upset of magnetic tunnel junction used in spintronic circuits caused by radiation-induced current

    NASA Astrophysics Data System (ADS)

    Sakimura, N.; Nebashi, R.; Natsui, M.; Ohno, H.; Sugibayashi, T.; Hanyu, T.

    2014-05-01

    This paper describes the possibility of a switching upset of a magnetic tunnel junction (MTJ) caused by a terrestrial radiation-induced single-event-upset (SEU) current in spintronic integrated circuits. The current waveforms were simulated by using a 3-D device simulator in a basic circuit including MTJs designed using 90-nm CMOS parameters and design rules. The waveforms have a 400 -μA peak and a 200-ps elapsed time when neutron particles with a linear energy transfer value of 14 MeV cm2/mg enter the silicon surface. The authors also found that the SEU current may cause soft errors with a probability of more than 10-12 per event, which was obtained by approximate solution of the ordinary differential equation of switching probability when the intrinsic critical current (IC0) became less than 30 μA.

  13. Simulation of the characteristics of low-energy proton induced single event upset

    NASA Astrophysics Data System (ADS)

    Geng, Chao; Xi, Kai; Liu, TianQi; Liu, Jie

    2014-10-01

    Monte Carlo simulation results are reported on the single event upset (SEU) triggered by the direct ionization effect of low-energy proton. The SEU cross-sections on the 45 nm static random access memory (SRAM) were compared with previous research work, which not only validated the simulation approach used herein, but also exposed the existence of saturated cross-section and the multiple bit upsets (MBUs) when the incident energy was less than 1 MeV. Additionally, it was observed that the saturated cross-section and MBUs are involved with energy loss and critical charge. The amount of deposited charge and the distribution with respect to the critical charge as the supplemental evidence are discussed.

  14. Comparison of single event phenomena for front/back irradiations

    SciTech Connect

    Musseau, O.; Ferlet-Cavrois, V.; Campbell, A.B.; Stapor, W.J.; McDonald, P.T.

    1997-12-01

    For devices irradiated from the front and the back, where ions have the same LET in the sensitive volumes, the SEU sensitivities and charge collection spectra are different. A specific test setup has been developed to make precise measurements of both collected charge and SEU in CMOS SRAMs. The authors present a set of new data and discuss the possible experimental artifacts that could affect these measurements. In all the cases, the device is more sensitive when irradiated from the back than from the front. This phenomenon seems related to energy transfer mechanisms from the ion to the material target, with secondary particles from both electronic and nuclear reactions being forward emitted. This effect may influence to net sensitivity of scaled down devices, with shallow sensitive layers, and heavy metal interconnects.

  15. Simulation of temporal characteristics of ion-velocity susceptibility to single event upset effect

    NASA Astrophysics Data System (ADS)

    Geng, Chao; Xi, Kai; Liu, Tian-Qi; Gu, Song; Liu, Jie

    2014-08-01

    Using a Monte Carlo simulation tool of the multi-functional package for SEEs Analysis (MUFPSA), we study the temporal characteristics of ion-velocity susceptibility to the single event upset (SEU) effect, including the deposited energy, traversed time within the device, and profile of the current pulse. The results show that the averaged dposited energy decreases with the increase of the ion-velocity, and incident ions of 209Bi have a wider distribution of energy deposition than 132Xe at the same ion-velocity. Additionally, the traversed time presents an obvious decreasing trend with the increase of ion-velocity. Concurrently, ion-velocity certainly has an influence on the current pulse and then it presents a particular regularity. The detailed discussion is conducted to estimate the relevant linear energy transfer (LET) of incident ions and the SEU cross section of the testing device from experiment and simulation and to critically consider the metric of LET.

  16. A dual redundancy radiation-hardened flip—flop based on a C-element in a 65 nm process

    NASA Astrophysics Data System (ADS)

    Gang, Chen; Bo, Gao; Min, Gong

    2013-09-01

    A radiation-hardened flip—flop is proposed to mitigate the single event upset (SEU) effect. Immunity was achieved through the use of C-elements and redundant storage elements. It takes advantage of the property of a C-element in which it enters a high impedance mode when its inputs are of different logic values. Redundant storage nodes are then used to drive the C-elements so that a single upset pulse in any storage will be prevented from altering the state of the output of the flip—flop. The flip—flop was implemented using 48 transistors and occupied an area of 30.78 μm2, using 65 nm CMOS process. It consumed 22.6% fewer transistors as compared to the traditional SEU resilient TMR flip—flop.

  17. Modeling and assessing the influence of linear energy transfer on multiple bit upset susceptibility

    NASA Astrophysics Data System (ADS)

    Geng, Chao; Liu, Jie; Xi, Kai; Zhang, Zhan-Gang; Gu, Song; Liu, Tian-Qi

    2013-10-01

    The influence of the metric of linear energy transfer (LET) on single event upset (SEU), particularly multiple bit upset (MBU) in a hypothetical 90-nm static random access memory (SRAM) is explored. To explain the odd point of higher LET incident ion but induced lower cross section in the curve of SEU cross section, MBUs induced by incident ions 132Xe and 209Bi with the same LET but different energies at oblique incidence are investigated using multi-functional package for single event effect analysis (MUFPSA). In addition, a comprehensive analytical model of the radial track structure is incorporated into MUFPSA, which is a complementation for assessing and interpreting MBU susceptibility of SRAM. The results show that (i) with the increase of incident angle, MBU multiplicity and probability each present an increasing trend; (ii) due to the higher ion relative velocity and longer range of δ electrons, higher energy ions trigger the MBU with less probability than lower energy ions.

  18. Single event upset protection circuit and method

    DOEpatents

    Wallner, John; Gorder, Michael

    2016-03-22

    An SEU protection circuit comprises first and second storage means for receiving primary and redundant versions, respectively, of an n-bit wide data value that is to be corrected in case of an SEU occurrence; the correction circuit requires that the data value be a 1-hot encoded value. A parity engine performs a parity operation on the n bits of the primary data value. A multiplexer receives the primary and redundant data values and the parity engine output at respective inputs, and is arranged to pass the primary data value to an output when the parity engine output indicates `odd` parity, and to pass the redundant data value to the output when the parity engine output indicates `even` parity. The primary and redundant data values are suitably state variables, and the parity engine is preferably an n-bit wide XOR or XNOR gate.

  19. Red persistent luminescence and magnetic properties of nanomaterials for multimodal imaging

    NASA Astrophysics Data System (ADS)

    Rosticher, C.; Chanéac, C.; Viana, B.; Fortin, M. A.; Lagueux, J.; Faucher, L.

    2014-03-01

    We present a new generation of nanotracers with persistent luminescence properties in the red-near IR range for small animal imaging. Silicates, oxysulfides and calcium phosphates nanoparticles doped with transition metal and lanthanide ions were developed in this aim. We have focused our attention in this paper on the biocompatible TCP/HAp phosphate compounds doped with Eu, Mn, Dy and on the Gd2O2S:Eu, Mg, Ti materials in the form of nanoparticles. All the nanosensors were hydrothermally synthesized and if the phosphate has a very high interest due to its biocompatibility Gd2O2S:Eu, Mg, Ti was investigated as a multimodal agent for possible in vivo optical imaging and MRI imaging.

  20. On-orbit flight results from the reconfigurable cibola flight experiment satellite (CFEsat)

    SciTech Connect

    Caffrey, Michael; Morgan, Keith; Roussel-dupre, Diane; Robinson, Scott; Nelson, Anthony; Salazar, Anthony; Wirthlin, Michael; Howes, William; Richins, Daniel

    2009-01-01

    The Cibola Flight Experiment (CFE) is an experimental small satellite developed at the Los Alamos National Laboratory to demonstrate the feasibility of using FPGA-based reconfigurable computing for sensor processing in a space environment. The CFE satellite was launched on March 8, 2007 in low-earth orbit and has operated extremely well since its deployment. The nine Xilinx Virtex FPGAs used in the payload have been used for several high-throughput sensor processing applications and for single-event upset (SEU) monitoring and mitigation. This paper will describe the CFE system and summarize its operational results. In addition, this paper will describe the results from several SEU detection circuits that were performed on the spacecraft.

  1. The Structure and Evolution of the Universe

    NASA Technical Reports Server (NTRS)

    Sakimoto, Philip (Technical Monitor); Gould, Roy

    2004-01-01

    Overview. The past year for the new SEU Forum has been a highly productive one and has moved us forward on three major objectives: Involving the public in the major scientific discoveries in our SEU theme this past year, especially the exciting discoveries about dark energy, cosmology, and black holes. Implementing the recommendations of the Knappenberger Report in order to strengthen the educational coherence of our collective activities. Developing strategic partnerships with underserved communities and other key customers . Among our activities for the past year are the following: Serving the Informal Science Education Communities: Summary of Goals, Plans and Activities for the Year 9/15/04 - 9/14/05. Interactions with the Space Science Community.

  2. Method of making silicon on insalator material using oxygen implantation

    DOEpatents

    Hite, Larry R.; Houston, Ted; Matloubian, Mishel

    1989-01-01

    The described embodiments of the present invention provide a semiconductor on insulator structure providing a semiconductor layer less susceptible to single event upset errors (SEU) due to radiation. The semiconductor layer is formed by implanting ions which form an insulating layer beneath the surface of a crystalline semiconductor substrate. The remaining crystalline semiconductor layer above the insulating layer provides nucleation sites for forming a crystalline semiconductor layer above the insulating layer. The damage caused by implantation of the ions for forming an insulating layer is left unannealed before formation of the semiconductor layer by epitaxial growth. The epitaxial layer, thus formed, provides superior characteristics for prevention of SEU errors, in that the carrier lifetime within the epitaxial layer, thus formed, is less than the carrier lifetime in epitaxial layers formed on annealed material while providing adequate semiconductor characteristics.

  3. Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits

    NASA Technical Reports Server (NTRS)

    Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.

    2009-01-01

    This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.

  4. Silicon-on-sapphire fiber optic transceiver technology for space applications

    NASA Astrophysics Data System (ADS)

    Kuznia, C. P.; Ahadian, J. F.; Pommer, R. J.; Hagan, R.

    2007-09-01

    We present Single Event Upset (SEU) testing of a parallel fiber optic transceiver designed for communicating data using commercial Fibre Channel and GbE protocols at data rates up to 2.5 Gbps per channel (on eight parallel channels). This transceiver was developed for aircraft applications, such as the Joint Strike Fighter (JSF), Raptor and F/A-18 aircraft, that deploy fiber optic networks using multi-mode fiber operating at 850 nm wavelength. However, this transceiver may also have applications in space environments. This paper describes the underlying transceiver component technology, which utilizes complementary metal-oxide semiconductor (CMOS) silicon-onsapphire circuitry and GaAs VCSEL and PIN devices. We also present results of SEU testing of this transceiver using heavy ions at Brookhaven National Labs.

  5. Analysis of single-event upset of magnetic tunnel junction used in spintronic circuits caused by radiation-induced current

    SciTech Connect

    Sakimura, N.; Nebashi, R.; Sugibayashi, T.; Natsui, M.; Hanyu, T.; Ohno, H.

    2014-05-07

    This paper describes the possibility of a switching upset of a magnetic tunnel junction (MTJ) caused by a terrestrial radiation-induced single-event-upset (SEU) current in spintronic integrated circuits. The current waveforms were simulated by using a 3-D device simulator in a basic circuit including MTJs designed using 90-nm CMOS parameters and design rules. The waveforms have a 400 -μA peak and a 200-ps elapsed time when neutron particles with a linear energy transfer value of 14 MeV cm{sup 2}/mg enter the silicon surface. The authors also found that the SEU current may cause soft errors with a probability of more than 10{sup −12} per event, which was obtained by approximate solution of the ordinary differential equation of switching probability when the intrinsic critical current (I{sub C0}) became less than 30 μA.

  6. Evaluation of an Ultra-Low Power Reed Solomon Encoder for NASA's Space Technology 5 Mission

    NASA Technical Reports Server (NTRS)

    Lei, K. E.; Xapsos, M. A.; Poivey, C.; LaBel, K. A.; Stone, R. F.; Yeh, P-S.; Gambles, J.; Hass, J.; Maki, G.; Murguia, J.

    2003-01-01

    Radiation test results and analyses are presented for ultra-low power Reed Solomon encoder circuits that are being considered for use on the Space Technology 5 (ST5) mission. The total ionizing dose tolerance is in excess of 100 krad(Si) and is due to the low supply voltage and the use of back-bias, which suppresses radiation-induced leakage currents in the n-channel devices. The circuits do not latch-up for ion LET values of at least 90 MeV-sq cm/mg. A hardened-by-design approach to SEU has achieved an upset threshold of about 20 MeV-sq cm/mg. The SEU rate expected for these circuits in the geosynchronous transfer orbit of ST5 is low.

  7. Single event upset tests of a RISC-based fault-tolerant computer

    SciTech Connect

    Kimbrough, J.R.; Butner, D.N.; Colella, N.J.; Kaschmitter, J.L.; Shaeffer, D.L.; McKnett, C.L.; Coakley, P.G.; Casteneda, C.

    1996-03-23

    The project successfully demonstrated that dual lock-step comparison of commercial RISC processors is a viable fault-tolerant approach to handling SEU in space environment. The fault tolerant approach on orbit error rate was 38 times less than the single processor error rate. The random nature of the upsets and appearance in critical code section show it is essential to incorporate both hardware and software in the design and operation of fault-tolerant computers.

  8. Single event effects in pulse width modulation controllers

    SciTech Connect

    Penzin, S.H.; Crain, W.R.; Crawford, K.B.; Hansel, S.J.; Kirshman, J.F.; Koga, R.

    1996-12-01

    SEE testing was performed on pulse width modulation (PWM) controllers which are commonly used in switching mode power supply systems. The devices are designed using both Set-Reset (SR) flip-flops and Toggle (T) flip-flops which are vulnerable to single event upset (SEU) in a radiation environment. Depending on the implementation of the different devices the effect can be significant in spaceflight hardware.

  9. Fault-Tolerant Coding for State Machines

    NASA Technical Reports Server (NTRS)

    Naegle, Stephanie Taft; Burke, Gary; Newell, Michael

    2008-01-01

    Two reliable fault-tolerant coding schemes have been proposed for state machines that are used in field-programmable gate arrays and application-specific integrated circuits to implement sequential logic functions. The schemes apply to strings of bits in state registers, which are typically implemented in practice as assemblies of flip-flop circuits. If a single-event upset (SEU, a radiation-induced change in the bit in one flip-flop) occurs in a state register, the state machine that contains the register could go into an erroneous state or could hang, by which is meant that the machine could remain in undefined states indefinitely. The proposed fault-tolerant coding schemes are intended to prevent the state machine from going into an erroneous or hang state when an SEU occurs. To ensure reliability of the state machine, the coding scheme for bits in the state register must satisfy the following criteria: 1. All possible states are defined. 2. An SEU brings the state machine to a known state. 3. There is no possibility of a hang state. 4. No false state is entered. 5. An SEU exerts no effect on the state machine. Fault-tolerant coding schemes that have been commonly used include binary encoding and "one-hot" encoding. Binary encoding is the simplest state machine encoding and satisfies criteria 1 through 3 if all possible states are defined. Binary encoding is a binary count of the state machine number in sequence; the table represents an eight-state example. In one-hot encoding, N bits are used to represent N states: All except one of the bits in a string are 0, and the position of the 1 in the string represents the state. With proper circuit design, one-hot encoding can satisfy criteria 1 through 4. Unfortunately, the requirement to use N bits to represent N states makes one-hot coding inefficient.

  10. Characterizing SRAM Single Event Upset in Terms of Single and Double Node Charge Collection

    NASA Technical Reports Server (NTRS)

    Black, J. D.; Ball, D. R., II; Robinson, W. H.; Fleetwood, D. M.; Schrimpf, R. D.; Reed, R. A.; Black, D. A.; Warren, K. M.; Tipton, A. D.; Dodd, P. E.; Haddad, N. F.; Xapsos, M. A.; Kim, H.; Friendlich, M.

    2008-01-01

    A well-collapse source-injection mode for SRAM SEU is demonstrated through TCAD modeling. The recovery of the SRAM s state is shown to be based upon the resistive path from the p+-sources in the SRAM to the well. Multiple cell upset patterns for direct charge collection and the well-collapse source-injection mechanisms are then predicted and compared to recent SRAM test data.

  11. Single-Event Upset and Scaling Trends in New Generation of the Commercial SOI PowerPC Microprocessors

    NASA Technical Reports Server (NTRS)

    Irom, Farokh; Farmanesh, Farhad; Kouba, Coy K.

    2006-01-01

    SEU from heavy-ions is measured for SOI PowerPC microprocessors. Results for 0.13 micron PowerPC with 1.1V core voltages increases over 1.3V versions. This suggests that improvement in SEU for scaled devices may be reversed. In recent years there has been interest in the possible use of unhardened commercial microprocessors in space because of their superior performance compared to hardened processors. However, unhardened devices are susceptible to upset from radiation space. More information is needed on how they respond to radiation before they can be used in space. Only a limited number of advanced microprocessors have been subjected to radiation tests, which are designed with lower clock frequencies and higher internal core voltage voltages than recent devices [1-6]. However the trend for commercial Silicon-on-insulator (SOI) microprocessors is to reduce feature size and internal core voltage and increase the clock frequency. Commercial microprocessors with the PowerPC architecture are now available that use partially depleted SOI processes with feature size of 90 nm and internal core voltage as low as 1.0 V and clock frequency in the GHz range. Previously, we reported SEU measurements for SOI commercial PowerPCs with feature size of 0.18 and 0.13 m [7, 8]. The results showed an order of magnitude reduction in saturated cross section compared to CMOS bulk counterparts. This paper examines SEUs in advanced commercial SOI microprocessors, focusing on SEU sensitivity of D-Cache and hangs with feature size and internal core voltage. Results are presented for the Motorola SOI processor with feature sizes of 0.13 microns and internal core voltages of 1.3 and 1.1 V. These results are compared with results for the Motorola SOI processors with feature size of 0.18 microns and internal core voltage of 1.6 and 1.3 V.

  12. In-flight and ground testing of single event upset sensitivity in static RAMs

    SciTech Connect

    Johansson, K.; Dyreklev, P.; Granbom, B.; Calvet, C.; Fourtine, S.; Feuillatre, O.

    1998-06-01

    This paper presents the results from in-flight measurements of single event upsets (SEU) in static random access memories (SRAM) caused by the atmospheric radiation environment at aircraft altitudes. The memory devices were carried on commercial airlines at high altitude and mainly high latitudes. The SEUs were monitored by a Component Upset Test Equipment (CUTE), designed for this experiment. The in flight results are compared to ground based testing with neutrons from three different sources.

  13. Radiation Tests on 2Gb NAND Flash Memories

    NASA Technical Reports Server (NTRS)

    Nguyen, Duc N.; Guertin, Steven M.; Patterson, J. D.

    2006-01-01

    We report on SEE and TID tests of highly scaled Samsung 2Gbits flash memories. Both in-situ and biased interval irradiations were used to characterize the response of the total accumulated dose failures. The radiation-induced failures can be categorized as followings: single event upset (SEU) read errors in biased and unbiased modes, write errors, and single-event-functional-interrupt (SEFI) failures.

  14. Attenuation of single event induced pulses in CMOS combinational logic

    SciTech Connect

    Baze, M.P.; Buchner, S.P.

    1997-12-01

    Results are presented of a study of SEU generated transient pulse attenuation in combinational logic structures built using common digital CMOS design practices. SPICE circuit analysis, heavy ion tests, and pulsed, focused laser simulations were used to examine the response characteristics of transient pulse behavior in long logic strings. Results show that while there is an observable effect, it cannot be generally assumed that attenuation will significantly reduce observed circuit bit error rates.

  15. Solar and Galactic Cosmic Rays Observed by SOHO

    NASA Astrophysics Data System (ADS)

    Fleck, Bernhard; Curdt, Werner; Olive, Jean-Philippe; van Overbeek, Ton

    2015-04-01

    Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to 75% of its original level over 1 ½ solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mechanism. We compare the daily CRF observed by the Oulu station with the daily SOHO SEU rate and with the degradation curve of the solar arrays. The Oulu CRF and the SOHO SSR SEU rate are both modulated by the solar cycle and are highly correlated, except for sharp spikes in the SEU rate, caused by isolated SEP events, which also show up as discontinuities in the otherwise slowly decreasing solar ray efficiency. This allows to discriminate between effects with solar and non-solar origin and to compare the relative strength of both. We find that the total number of SSR SEUs with solar origin over the 17 ½ years from January 1996 through June 2013 is of the same order as those generated by cosmic ray hits. 49% of the total solar array degradation during that time can be attributed to proton events, i.e. the effect of a series of short-lived, violent events (SEPs) is comparable to the cycle-integrated damage by cosmic rays.

  16. Applications Of Monte Carlo Radiation Transport Simulation Techniques For Predicting Single Event Effects In Microelectronics

    SciTech Connect

    Warren, Kevin; Reed, Robert; Weller, Robert; Mendenhall, Marcus; Sierawski, Brian; Schrimpf, Ronald

    2011-06-01

    MRED (Monte Carlo Radiative Energy Deposition) is Vanderbilt University's Geant4 application for simulating radiation events in semiconductors. Geant4 is comprised of the best available computational physics models for the transport of radiation through matter. In addition to basic radiation transport physics contained in the Geant4 core, MRED has the capability to track energy loss in tetrahedral geometric objects, includes a cross section biasing and track weighting technique for variance reduction, and additional features relevant to semiconductor device applications. The crucial element of predicting Single Event Upset (SEU) parameters using radiation transport software is the creation of a dosimetry model that accurately approximates the net collected charge at transistor contacts as a function of deposited energy. The dosimetry technique described here is the multiple sensitive volume (MSV) model. It is shown to be a reasonable approximation of the charge collection process and its parameters can be calibrated to experimental measurements of SEU cross sections. The MSV model, within the framework of MRED, is examined for heavy ion and high-energy proton SEU measurements of a static random access memory.

  17. For ‘Physitians of the Soule’

    PubMed Central

    Firth-Godbehere, Richard

    2015-01-01

    This article attempts to understand how Thomas Wright’s 1604 work, The Passions of the Minde in Generall, might have fitted into his overall mission as an English Catholic preacher, particularly when read via Wright’s understanding of Thomas Aquinas’s passion of fuga seu abominatio. Some historians claim that Wright was a controversialist, previously describing The Passions as either a radical departure from Wright’s mission, or the work of a different Thomas Wright. Earlier attempts to find a missionary element within The Passions have been inadequate. Through a close reading of The Passions, specifically analysing Wright's interpretation of fuga seu abominatio within the context of Wright’s intended readership, the main message of The Passions, and his background, this article suggests a possible reading of the text as a work aimed specifically at fellow English Catholics. To Wright, the passions of hatred of abomination and flight or detestation, derived primarily from Aquinas’s fuga seu abominatio, were not simply a form of disgust, as often assumed, but the potential worldly or otherworldly harm that someone we love, such as a neighbour, might face from the abominable evil of sin and damnation. By linking hatred of abomination, flight or detestation, and Wright’s particular view of sin together, Wright was teaching English Catholics how these passions might be used to cure diseased souls, turning the work into a guide for preaching. PMID:26870634

  18. Further development of the Heavy Ion Cross section for single event UPset: Model (HICUP)

    SciTech Connect

    Connell, L.W.; Sexton, F.W.; Prinja, A.K.

    1995-12-01

    The Heavy Ion Cross section for single event UPset (HICUP) models the angular dependent heavy ion upset cross section. It pulls together many of the parameters and concepts used to characterize the Single Event Upset (SEU) phenomena, unifying them in a single cohesive model. HICUP is based on a Rectangular Parallelepiped (RPP) geometry for the sensitive volume and the Weibull density function for the upset threshold energy. Excellent agreement is obtained between the model and heavy ion test data. HICUP is used to derive the correct scaling laws for transforming angular cross section data to normal incidence, reconciling two previously proposed inverse cosine scaling corrections. The angle integrated HICUP model, I-HICUP, is used in Galactic Cosmic Ray (GCR) upset rate calculations with results nearly identical to the Space Radiation{trademark} code. Letaw has produced an automated SEU parameter fitting routine based on HICUP and the {chi}{sup 2} method. It ferrets out the best-fit critical SEU parameters embedded within the raw angular test data, including charge collection depth and funnel length. His method couples directly to the upset rate calculation in a self-consistent manner eliminating the need to arbitrarily assume a device depth. Results of this new procedure are presented.

  19. The board implementation of AVR microcontroller checking for single event upsets

    NASA Astrophysics Data System (ADS)

    Lho, Young Hwan; Jang, Dae Jin; Seo, Kang Kuk; Jung, Jae Ho; Kim, Ki Yup

    2005-12-01

    Radiation hardening parts are to be used for satellites and nuclear power plants due to various kinds of radiation particles in space and radiation environment. Here, our focus is to implement a testing board of AVR Microcontroller checking for Single Event Upsets (SEU); the effects of protons on the electronic devices. The SEU results form the level change of stored information due to photon radiation and temperature in the space environment. The impact of SEU on PLD (Programmable Logic Devices) technology is most apparent in SRAM/ROM/DRAM devices wherein the state of storage cell can be upset. In this research, a simple and powerful test technique is suggested, and the results are presented for the analysis and future reference. In our experiment, the proton radiation facility (having the energy of 30 MeV with a beam current of 20 uA in the cyclotron) available at KIRAMS (Korea Institute of Radiological Medical Sciences) has been applied on two kinds of commercially available SRAM and EEPROM.

  20. Tão perto de casa, tão longe de nós: etnografia das novas margens no centro da urbe

    PubMed Central

    Fernandes, Por Luís

    2011-01-01

    Philippe Bourgois é, desde 2007, “Richard Perry University professor” no Departamento de Antropologia e de Medicina Familiar e de Práticas Comunitárias na Universidade da Pensilvânia. Esteve durante largos anos ligado ao Departamento de Antropologia, História e Medicina Social da Universidade da Califórnia, São Francisco. A publicação, em 1995, de In Search of Respect: Selling Crack in El Barrio1 projectaria o seu nome muito para além dos Estados Unidos: uma etnografia no coração porto-riquenho do Harlem, em torno dos actores e dos ambientes da venda de crack. Seguir-se-ia um longo trabalho de terreno em acampamentos de dependentes de heroína em São Francisco, orientando o seu trabalho para as formas mais radicais da pobreza e da marginalidade nos EUA. É deste trabalho de terreno que sai o seu último livro, Righteous Dopefiend2. Em Junho de 2007 esteve em Lisboa para participar na 3.a edição do “Ethnografeast”. Foi então que aproveitámos a oportunidade para ouvir um percurso invulgar contado pelo próprio: uma longa conversa no Hotel Zurique, cujo nome só vem ao caso por evocar o país onde passou uma parte da infância. PMID:22013286

  1. Apparatus for and method of eliminating single event upsets in combinational logic

    NASA Technical Reports Server (NTRS)

    Gambles, Jody W. (Inventor); Hass, Kenneth J. (Inventor); Cameron, Kelly B. (Inventor)

    2001-01-01

    An apparatus for and method of eliminating single event upsets (or SEU) in combinational logic are used to prevent error propagation as a result of cosmic particle strikes to the combinational logic. The apparatus preferably includes a combinational logic block electrically coupled to a delay element, a latch and an output buffer. In operation, a signal from the combinational logic is electrically coupled to a first input of the latch. In addition, the signal is routed through the delay element to produce a delayed signal. The delayed signal is routed to a second input of the latch. The latch used in the apparatus for preventing SEU preferably includes latch outputs and a feature that the latch outputs will not change state unless both latch inputs are correct. For example, the latch outputs may not change state unless both latch inputs have the same logical state. When a cosmic particle strikes the combinational logic, a transient disturbance with a predetermined length may appear in the signal. However, a function of the delay element is to preferably provide a time delay greater than the length of the transient disturbance. Therefore, the transient disturbance will not reach both latch inputs simultaneously. As a result, the latch outputs will not permanently change state in error due to the transient disturbance. In addition, the output buffer preferably combines the latch outputs in such a way that the correct state is preserved at all times. Thus, combinational logic with protection from SEU is provided.

  2. The physics of a single-event upset in integrated circuits: A review and critique of analytical models for charge collection

    NASA Technical Reports Server (NTRS)

    Vonroos, O.; Zoutendyk, J.

    1983-01-01

    When an energetic particle (kinetic energy 0.5 MeV) originating from a radioactive decay or a cosmic ray transverse the active regions of semiconductor devices used in integrated circuit (IC) chips, it leaves along its track a high density electron hole plasma. The subsequent decay of this plasma by drift and diffusion leads to charge collection at the electrodes large enough in most cases to engender a false reading, hence the name single-event upset (SEU). The problem of SEU's is particularly severe within the harsh environment of Jupiter's radiation belts and constitutes therefore a matter of concern for the Galileo mission. The physics of an SEU event is analyzed in some detail. Owing to the predominance of nonlinear space charge effects and the fact that positive (holes) and negative (electrons) charges must be treated on an equal footing, analytical models for the ionized-charge collection and their corresponding currents as a function of time prove to be inadequate even in the simplest case of uniformly doped, abrupt p-n junctions in a one-dimensional geometry. The necessity for full-fledged computer simulation of the pertinent equations governing the electron-hole plasma therefore becomes imperative.

  3. Prediction of error rates in dose-imprinted memories on board CRRES by two different methods. [Combined Release and Radiation Effects Satellite

    NASA Technical Reports Server (NTRS)

    Brucker, G. J.; Stassinopoulos, E. G.

    1991-01-01

    An analysis of the expected space radiation effects on the single event upset (SEU) properties of CMOS/bulk memories onboard the Combined Release and Radiation Effects Satellite (CRRES) is presented. Dose-imprint data from ground test irradiations of identical devices are applied to the predictions of cosmic-ray-induced space upset rates in the memories onboard the spacecraft. The calculations take into account the effect of total dose on the SEU sensitivity of the devices as the dose accumulates in orbit. Estimates of error rates, which involved an arbitrary selection of a single pair of threshold linear energy transfer (LET) and asymptotic cross-section values, were compared to the results of an integration over the cross-section curves versus LET. The integration gave lower upset rates than the use of the selected values of the SEU parameters. Since the integration approach is more accurate and eliminates the need for an arbitrary definition of threshold LET and asymptotic cross section, it is recommended for all error rate predictions where experimental sigma-versus-LET curves are available.

  4. Implementing QML for radiation hardness assurance

    NASA Astrophysics Data System (ADS)

    Winokur, P. S.; Sexton, F. W.; Fleetwood, D. M.; Terry, M. D.; Shaneyfelt, M. R.

    1990-12-01

    The US government has proposed a qualified manufacturers list (QML) methodology to qualify integrated circuits for high reliability and radiation hardness. An approach to implementing QML for single-event upset (SEU) immunity on 16k SRAMs that involves relating values of feedback resistance to system error rates is demonstrated. It is seen that the process capability indices, Cp and Cpk, for the manufacture of 400-k-ohm feedback resistors required to provide SEU tolerance do not conform to 6 sigma quality standards. For total-dose, interface trap charge, Delta Vit, shifts measured on transistors are correlated with circuit response in the space environment. Statistical process control (SPC) is illustrated for Delta Vit, and violations of SPC rules are interpreted in terms of continuous improvement. Design validation for SEU and quality conformance inspections for total-dose are identified as major obstacles to cost-effective QML implementation. Techniques and tools that will help QML provide real cost savings are identified as physical models, 3-D device-plus-circuit codes, and improved design simulators.

  5. Legitimizing Security in the Ivory Tower: Canadian University Corporate Security Services' Public Quest for Legitimacy.

    PubMed

    Wilkinson, Blair

    2016-05-01

    This article examines how university corporate security (UCS) services engage in legitimation work in their attempts to make their university communities (i.e., faculty, staff, students) and political masters (i.e., university administrators, boards of governors, senators) believe that they are honest, trustworthy, and caring and have authority that should be deferred to. This is accomplished through the analysis of interview and observational data collected as part of a research project exploring UCS services at five Canadian universities and an examination of how UCS services at 14 Canadian universities communicate using the social media service Twitter. These UCS services were found to primarily use Twitter for the purposes of soliciting or requesting information and for networking. In communicating through Twitter, UCS services engage in public legitimation work in which they make claims about and attempt to demonstrate their expertise, authority, and accountability. This article argues that both UCS services' particular legitimacy problem (i.e., their possession of both private and public attributes) and the interactive nature of public legitimation work create tensions that may serve to disrupt UCS services' ability to attain legitimacy. Cet article examine la manière dont les services de sécurité d'entreprise à l'université (SEU) s'engagent à légitimer leurs tentatives de persuader leurs communautés universitaires (c'est-à-dire le corps professoral, le personnel et les étudiants) ainsi que la haute administration (c'est-à-dire les administrateurs de l'université, le conseil des gouverneurs et les sénateurs) qu'ils sont honnêtes, attentifs, dignes de confiance, et qu'ils possèdent un niveau d'autorité auquel quiconque devrait se référer. Ceci sera accompli en analysant un corpus d'entrevues et d'observations dans le cadre d'un projet de recherche examinant les services de type SEU dans cinq universités canadiennes, ainsi qu'une étude sur

  6. Solar and Galactic Cosmic Rays Observed by SOHO

    NASA Astrophysics Data System (ADS)

    Curdt, W.; Fleck, B.

    Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to ≈77% of its original level over roughly 1 1/2 solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mechanism. We compare the daily CRF observed by the Oulu station with the daily SOHO SEU rate and with the degradation curve of the solar arrays. The Oulu CRF and the SOHO SSR SEU rate are both modulated by the solar cycle and are highly correlated, except for sharp spikes in the SEU rate, caused by isolated SEP events, which also show up as discontinuities in the otherwise slowly decreasing solar ray efficiency. This allows to discriminate between effects with solar and non-solar origin and to compare the relative strength of both. We find that during solar cycle 23 (1996 Apr 1 -- 2008 Aug 31) only 6% of the total number of SSR SEUs were caused by SEPs; the remaining 94% were due to galactic cosmic rays. During the maximum period of cycle 23 (2000 Jan 1 -- 2003 Dec 31), the SEP contribution increased to 22%, and during 2001, the year with the highest SEP rate, to 30%. About 40% of the total solar array degradation during the 17 years from Jan 1996 through Feb 2013 can be attributed to proton events, i.e. the effect of a series of short-lived, violent SEP events is comparable to the cycle-integrated damage by cosmic rays.

  7. Reconfigurable fault tolerant avionics system

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. M.; Asami, K.; Cho, Mengu

    This paper presents the design of a reconfigurable avionics system based on modern Static Random Access Memory (SRAM)-based Field Programmable Gate Array (FPGA) to be used in future generations of nano satellites. A major concern in satellite systems and especially nano satellites is to build robust systems with low-power consumption profiles. The system is designed to be flexible by providing the capability of reconfiguring itself based on its orbital position. As Single Event Upsets (SEU) do not have the same severity and intensity in all orbital locations, having the maximum at the South Atlantic Anomaly (SAA) and the polar cusps, the system does not have to be fully protected all the time in its orbit. An acceptable level of protection against high-energy cosmic rays and charged particles roaming in space is provided within the majority of the orbit through software fault tolerance. Check pointing and roll back, besides control flow assertions, is used for that level of protection. In the minority part of the orbit where severe SEUs are expected to exist, a reconfiguration for the system FPGA is initiated where the processor systems are triplicated and protection through Triple Modular Redundancy (TMR) with feedback is provided. This technique of reconfiguring the system as per the level of the threat expected from SEU-induced faults helps in reducing the average dynamic power consumption of the system to one-third of its maximum. This technique can be viewed as a smart protection through system reconfiguration. The system is built on the commercial version of the (XC5VLX50) Xilinx Virtex5 FPGA on bulk silicon with 324 IO. Simulations of orbit SEU rates were carried out using the SPENVIS web-based software package.

  8. Calculation of the Local Neutronic Parameters for CANDU Fuel Bundles Using Transport Methods

    SciTech Connect

    Balaceanu, Victoria; Rizoiu, Andrei; Hristea, Viorel

    2006-07-01

    For a realistic neutronic evaluation of the CANDU reactor core it is important to accurately perform the local neutronic parameters (i.e. multigroup macroscopic cross sections for the core materials) calculation. This means using codes that allow a good geometric representation of the CANDU fuel bundle and then solving the transport equation. The paper reported here intends to study in detail the local behavior for two types of CANDU fuel, NU{sub 3}7 (Natural Uranium, 37 elements) and SEU{sub 4}3 (Slightly Enriched Uranium, 43 elements, with 1.1 wt% enrichment). The considered fuel types represent fresh and used bundles. The two types of CANDU super-cells are reference NU{sub 3}7, perturbed NU{sub 3}7, reference SEU{sub 4}3 and perturbed SEU{sub 4}3. The perturbed super-cells contain a Mechanical Control Absorber (a very strong reactivity device). For reaching the proposed objective a methodology is used based on WIMS and PIJXYZ codes. WIMS is a standard lattice-cell code, based on transport theory and it is used for producing fuel cell multigroup macroscopic cross sections. For obtaining the fine local neutronic parameters in the CANDU super-cells (k-eff values, local MCA reactivity worth, flux distributions and reaction rates), the PIJXYZ code is used. PIJXYZ is a 3D integral transport code using the first collision probability method and it has been developed for CANDU cell geometry. It is consistent with WIMS lattice-cell calculations and allows a good geometrical representation of the CANDU bundle in three dimensions. The analysis of the neutronic parameters consists of comparing the obtained results with the similar results calculated with the DRAGON code. This comparison shows a good agreement between these results. (authors)

  9. On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

    NASA Astrophysics Data System (ADS)

    Seferis, I. E.; Zeler, J.; Michail, C.; Valais, I.; Fountos, G.; Kalyvas, N.; Bakas, A.; Kandarakis, I.; Zych, E.

    2016-05-01

    In the present work, we demonstrate the fabrication technique of highly translucent layers of nanoparticulated (~50 nm) LuPO4:Eu phosphor, present their basic luminescent properties and give results of their performance in a planar imaging system coupled to a CMOS photodetector. For comparison, the imaging performance of an opaque Gd2O2S:Eu phosphor screen prepared by sedimentation is also shown. The X-ray detection parameters as well as the luminescence efficiency of the investigated films were discussed. Results show that the in-line transmittance at ~600-700 nm, in the range of the phosphor luminescence, varies with respect to the thickness of the films from 40 to 50 % for a film of 67 μm thick to 4-12 % when the thickness increases to 460 μm. Yet, X-ray detection parameters get enhanced as the thickness of the films increases. Those results affect the luminescence efficiency curves of the films under poly-energetic X-ray radiation of various tube energies. The normalized noise power spectrum values were found similar for LuPO4:Eu films and a phosphor screen made using commercial Gd2O2S:Eu powder. The detective quantum efficiency of our films is clearly lower compared to the Gd2O2S:Eu screen from 2 to 10 cycles mm-1 frequency range while the modulation transfer function is lower from 0 to 5.5 cycles mm-1 frequency range. The acquired data allow to predict that high-temperature sintering of our films under pressure may help to improve their imaging quality, since such a processing should increase the luminescence efficiency without significant growth of the grains and thus without sacrificing their translucent character.

  10. Radiation characterization report for the GPS Receiver microcontroller chip. Final report

    SciTech Connect

    Not Available

    1994-06-20

    The overall objective of this characterization test was to determine the sensitivity of the Motorola 68332 32-bit microcontroller to radiation induced single event upset and latch-up (SEU/SEL). The microcontroller is a key component of the GPS Receiver which will be a subsystem of the satellite required for the {open_quotes}FORTE{close_quotes} experiment. Testing was conducted at the Single Event Effects Laboratory at Brookhaven National Laboratory. The results obtained included a latch-up (SEL) threshold LET (Linear Energy Transfer) of 20 MeV-CM{sub 2}/mg and an upset (SEU) threshold LET of 5 MeV-CM{sup 2}/mg. The SEU threshold is typical of this technology, commercial 0.8{mu}m HCMOS. Some flow errors were observed that were not reset by the internal watchdog timer of the 68332. It is important that the Receiver design include a monitor of the device, such as an external watch-dog timer, that would initiate a reset of the program when this type of upset occurs. The SEL threshold is lower than would be expected for this 12{mu}m epi layer process and suggests the need for a strategy that would allow for a hard reset of the controller when a latch-up event occurs. Analysis of the galactic cosmic ray spectrum for the FORTE orbit was done and the results indicate a worst case latch-up rate for this device of 6.3 {times} 10{sup {minus}5} latch-ups per device day or roughly one latch-up per 43.5 device years.

  11. Radiation characterization report for the GPS Receiver microcontroller chip

    NASA Astrophysics Data System (ADS)

    1994-06-01

    The overall objective of this characterization test was to determine the sensitivity of the Motorola 68332 32-bit microcontroller to radiation induced single event upset and latch-up (SEU/SEL). The microcontroller is a key component of the GPS Receiver which will be a subsystem of the satellite required for the 'FORTE' experiment. Testing was conducted at the Single Event Effects Laboratory at Brookhaven National Laboratory. The results obtained included a latch-up (SEL) threshold LET (Linear Energy Transfer) of 20 MeV-sq cm/mg and an upset (SEU) threshold LET of 5 MeV-sq cm/mg. The SEU threshold is typical of this technology, commercial 0.8 micrometers HCMOS. Some flow errors were observed that were not reset by the internal watchdog timer of the 68332. It is important that the Receiver design include a monitor of the device, such as an external watch-dog timer, that would initiate a reset of the program when this type of upset occurs. The SEL threshold is lower than would be expected for this 12 micrometer epi layer process and suggests the need for a strategy that would allow for a hard reset of the controller when a latch-up event occurs. Analysis of the galactic cosmic ray spectrum for the FORTE orbit was done and the results indicate a worst case latch-up rate for this device of 6.3 x 10(exp -5) latch-ups per device day or roughly one latch-up per 43.5 device years.

  12. Implementing QML (Qualified Manufacturers List) for radiation hardness assurance

    SciTech Connect

    Winokur, P.S.; Sexton, F.W.; Fleetwood, D.M.; Terry, M.D.; Shaneyfelt, M.R.; Dressendorfer, P.V.; Schwank, J.R.

    1990-01-01

    Statistical process control (SPC) of technology parameters relevant to radiation hardness, test structure to Integrated Circuit (IC) correlation, and extrapolation from laboratory to threat scenarios are keys to implementing Qualified Manufacture's List (QML) for radiation hardness assurance in a cost-effective manner. Data from approximately 300 wafer lots fabricated in Sandia's 4/3-{mu}m and Complementry Metal Oxide Semiconductor (CMOS) IIIA (2-{mu}m) technologies are used to demonstrate approaches to, and highlight issues associated with, implementing QML for radiation-hardened CMOS in space applications. An approach is demonstrated to implement QML for signal-event upset SEU immunity on 16k SRAMs that involves relating values of feedback resistance to system error rates. It is seen that the process capability indices, C{sub p} and C{sub pk}, for the manufacture of 400 k{Omega} feedback resistors required to provide SEU tolerance do not conform to 6{sigma}'' quality standards. For total-dose, {triangle}V{sub it} shifts measured on transistors are correlated with circuit response in the space environment. SPC is illustrated for {triangle}V{sub it}, and violations of SPC rules are interpreted in terms of continuous improvement. Finally, design validation for SEU, and quality conformance inspections for total-dose, are identified as major obstacles to cost-effective QML implementation. Techniques and tools that will help QML provide real cost savings are identified as physical models, three-dimensional device-plus-circuit codes, and improved design simulators. 29 refs., 10 figs., 1 tab.

  13. Charge collection at large angles of incidence. [exibited by p-n junctions

    NASA Technical Reports Server (NTRS)

    Mcnulty, P. J.; Beauvais, W. J.; Reed, R. A.; Roth, D. R.; Stassinopoulos, E. G.; Brucker, G. J.

    1992-01-01

    Charge collection exhibited by p-n junctions, which have at least one small dimension, deviates from the geometric assumptions commonly used in SEU (single event upset) testing. The amount of charge collected did not increase with the secant of the angle of incidence. The number of events under the peak in the charge collection spectrum did not decrease as the cosine of the angle of incidence. Both the position of the peak and the number of events under the peak measured at a given angle of incidence depended upon which symmetry axis of the device was chosen to be the axis of rotation.

  14. Advanced flight computer. Special study

    NASA Technical Reports Server (NTRS)

    Coo, Dennis

    1995-01-01

    This report documents a special study to define a 32-bit radiation hardened, SEU tolerant flight computer architecture, and to investigate current or near-term technologies and development efforts that contribute to the Advanced Flight Computer (AFC) design and development. An AFC processing node architecture is defined. Each node may consist of a multi-chip processor as needed. The modular, building block approach uses VLSI technology and packaging methods that demonstrate a feasible AFC module in 1998 that meets that AFC goals. The defined architecture and approach demonstrate a clear low-risk, low-cost path to the 1998 production goal, with intermediate prototypes in 1996.

  15. Use of PuBe source to simulate neutron-induced single event upsets in static RAMS

    SciTech Connect

    Normand, E.; Wert, J.L.; Doherty, W.R.; Oberg, D.L.; Measel, P.R.; Criswell, T.L.

    1988-12-01

    Neutron induced single event upsets were measured in static memory devices using a 10 curie PuBe source. The PuBe source conservatively overestimates the spectrum of fast neutrons emitted by a radioisotope thermoelectric generator (RTG). For the 93L422, the neutron-induced upset rate compared favorably with calculated values derived using the burst generation concept. By accounting for the production of the ionizing particles by the PuBe and RTG neutron spectra, convenient upper bound SEU upset rates for memory devices near an RTG can be derived.

  16. Single event upset and charge collection measurements using high energy protons and neutrons

    SciTech Connect

    Normand, E.; Oberg, D.L.; Wert, J.L.; Ness, J.D.; Majewski, P.P. ); Wender, S.; Gavron, A. )

    1994-12-01

    RAMs, microcontrollers and surface barrier detectors were exposed to beams of high energy protons and neutrons to measure the induced number of upsets as well as energy deposition. The WNR facility at Los Alamos provided a neutron spectrum similar to that of the atmospheric neutrons. Its effect on devices was compared to that of protons with energies of 200, 400, 500, and 800 MeV. Measurements indicate that SEU cross sections for 400 MeV protons are similar to those induced by the atmospheric neutron spectrum.

  17. Scaling and Single Event Effects (SEE) Sensitivity

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.

    2003-01-01

    This paper begins by discussing the potential for scaling down transistors and other components to fit more of them on chips in order to increasing computer processing speed. It also addresses technical challenges to further scaling. Components have been scaled down enough to allow single particles to have an effect, known as a Single Event Effect (SEE). This paper explores the relationship between scaling and the following SEEs: Single Event Upsets (SEU) on DRAMs and SRAMs, Latch-up, Snap-back, Single Event Burnout (SEB), Single Event Gate Rupture (SEGR), and Ion-induced soft breakdown (SBD).

  18. Laser simulation of single event upsets

    SciTech Connect

    Buchner, S.P.; Wilson, D.; Kang, K.; Gill, D.; Mazer, J.A.; Raburn, W.D.; Campbell, A.B.; Knudson, A.R.

    1987-12-01

    A pulsed picosecond laser was used to produce upsets in both a commercial bipolar logic circuit and a specially designed CMOS SRAM test structure. Comparing the laser energy necessary for producing upsets in transistors that have different upset sensitivities with the single event upset (SEU) level predicted from circuit analysis showed that a picosecond laser could measure circuit sensitivity to SEUs. The technique makes it possible not only to test circuits rapidly for upset sensitivity but also, because the beam can be focussed down to a small spot size, to identify sensitive transistors.

  19. Implications of the spatial dependence of the single-event-upset threshold in SRAMs measured with a pulsed laser

    SciTech Connect

    Buchner, S. SFA Inc., Landover, MD ); Langworthy, J.B.; Stapor, W.J.; Campbell, A.B. ); Rivet, S. )

    1994-12-01

    Pulsed laser light was used to measure single event upset (SEU) thresholds for a large number of memory cells in both CMOS and bipolar SRAMs. Results showed that small variations in intercell upset threshold could not explain the gradual rise in the curve of cross section versus linear energy transfer (LET). The memory cells exhibited greater intracell variations implying that the charge collection efficiency within a memory cell varies spatially and contributes substantially to the shape of the curve of cross section versus LET. The results also suggest that the pulsed laser can be used for hardness-assurance measurements on devices with sensitive areas larger than the diameter of the laser beam.

  20. Radiation tests of CMS RPC muon trigger electronic components

    NASA Astrophysics Data System (ADS)

    Buńkowski, Karol; Kassamakov, Ivan; Królikowski, Jan; Kierzkowski, Krzysztof; Kudła, Maciej; Maenpaa, Teppo; Poźniak, Krzysztof; Rybka, Dominik; Tuominen, Eija; Ungaro, Donatella; Wrochna, Grzegorz; Zabołotny, Wojciech

    2005-02-01

    The results of proton irradiation test of electronic devices, selected for the RPC trigger electronic system of the CMS detector, will be presented. For Xilinx Spartan-IIE FPGA the cross-section for Single Event Upsets (SEUs) in configuration bits was measured. The dynamic SEUs in flip-flops were also investigated, but not observed. For the FLASH memories no single upsets were detected. Only after irradiating with a huge dose permanent damages of devices were observed. For Synchronous Dynamic Random Access Memory (SDRAM), the SEU cross-section was measured.

  1. Irradiation effects in electronic components of the RPC trigger for the CMS experiment

    NASA Astrophysics Data System (ADS)

    Bunkowski, Karol; Kassamakov, Ivan I.; Krolikowski, J.; Kierzkowski, Krzysztof; Kudla, Maciej I.; Maenpaa, Teppo; Pozniak, Krzysztof T.; Rybka, Dominik; Tuominen, Eija; Ungaro, Donatella; Zabolotny, Wojciech M.

    2004-07-01

    The results of proton radiation test of electronic devices for RPC trigger electronic system of CMS detector are presented. For Xilinx Spartan-IIE FPGA the cross section for Single Event Upsets (SEUs) in configuration bits was measured. The dynamic SEUs in flip-flops was also investigated, but not observed. For the FLASH memories no single upsets were detected, but after a huge dose permanent damages of devices were observed. For SDRAM memories, the SEU cross section was measured. A brief description of radiation inducted effects in FPGAs, SRAM and FLASH memories is also presented.

  2. A systems-oriented single event effects test approach for high speed digital phase-locked loops

    SciTech Connect

    Jobe, K.; Shoga, M.; Koga, R.

    1996-12-01

    A systems-oriented single event effects (SEE) test approach is outlined here for two different phase-locked loop (PLL) application specific integrated circuits (ASICs) used for spaceborne local oscillator (LO) generation. The system considerations in designing the upset detection technique is described. This is the only known technique for getting information critical to the system about single event upset (SEU) sensitivity at speed for PLLs. Test results are presented for PLL devices operating at clock speeds of 1.0 and 1.5 GHz. Significant frequency effects were not observed in these devices since the clock speed varied only 50%.

  3. Measurements of dose with individual FAMOS transistors

    SciTech Connect

    Scheick, L.Z.; McNulty, P.J.; Roth, D.R.; Davis, M.G.; Mason, B.E.

    1999-12-01

    A new method is described for measuring the doses absorbed by microstructures from an exposure to ionizing radiation. The decrease in the duration of UltraViolet light (UV) exposure required to erase each cell of a commercial UltraViolet erasable Programmable Read Only Memory (UVPROM) correlates with the dose absorbed by the floating gate of that transistor. This technique facilitates analysis of the microdose distribution across the array and the occurrence of Single Event Upset (SEU) like anomalous shifts due to rare large energy-deposition events.

  4. Evaluation of power costs in applying TMR to FPGA designs.

    SciTech Connect

    Rollins, Nathaniel; Wirthlin, M. J.; Graham, P. S.

    2004-01-01

    Triple modular redundancy (TMR) is a technique commonly used to mitigate against design failures caused by single event upsets (SEUs). The SEU immunity that TMR provides comes at the cost of increased design area and decreased speed. Additionally, the cost of increased power due to TMR must be considered. This paper evaluates the power costs of TMR and validates the evaluations with actual measurements. Sensitivity to design placement is another important part of this study. Power consumption costs due to TMR are also evaluated in different FPGA architectures. This study shows that power consumption rises in the range of 3x to 7x when TMR is applied to a design.

  5. Effects of cosmic rays on single event upsets

    NASA Technical Reports Server (NTRS)

    Venable, D. D.; Zajic, V.; Lowe, C. W.; Olidapupo, A.; Fogarty, T. N.

    1989-01-01

    Assistance was provided to the Brookhaven Single Event Upset (SEU) Test Facility. Computer codes were developed for fragmentation and secondary radiation affecting Very Large Scale Integration (VLSI) in space. A computer controlled CV (HP4192) test was developed for Terman analysis. Also developed were high speed parametric tests which are independent of operator judgment and a charge pumping technique for measurement of D(sub it) (E). The X-ray secondary effects, and parametric degradation as a function of dose rate were simulated. The SPICE simulation of static RAMs with various resistor filters was tested.

  6. Neuroprotective effects of Buyang Huanwu decoction on cerebral ischemia-induced neuronal damage

    PubMed Central

    Mu, Qingchun; Liu, Pengfei; Hu, Xitong; Gao, Haijun; Zheng, Xu; Huang, Haiyan

    2014-01-01

    Among the various treatment methods for stroke, increasing attention has been paid to traditional Chinese medicines. Buyang Huanwu decoction is a commonly used traditional Chinese medicine for the treatment of stroke. This paper summarizes the active components of the Chinese herb, which is composed of Huangqi (Radix Astragali seu Hedysari), Danggui (Radix Angelica sinensis), Chishao (Radix Paeoniae Rubra), Chuanxiong (Rhizoma Ligustici Chuanxiong), Honghua (Flos Carthami), Taoren (Semen Persicae) and Dilong (Pheretima), and identifies the therapeutic targets and underlying mechanisms that contribute to the neuroprotective properties of Buyang Huanwu decoction. PMID:25368650

  7. Single Event Effects on Space Radiation Hardened 64K SRAMS at Room temperature

    NASA Technical Reports Server (NTRS)

    Kim, O.; Schwartz, H.; McCarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The laser threshold linear Energy transfer for single event upsetscan be estimaed, even at room temperature, for space radiation hardened 64K SRAMs. The memories where independently developed to quality for the Qualified Manufacturer's List by IBM and Honeywell. The memory was so hard that high energy heavy ions generated by the Van de Graff could not determine the SEU threshold at room temperature. Use of pulsed Laser tests would meake it possible to forgo very expensive testing at ultra-high energy accelerators.

  8. NASA Space Engineering Research Center for VLSI systems design

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This annual review reports the center's activities and findings on very large scale integration (VLSI) systems design for 1990, including project status, financial support, publications, the NASA Space Engineering Research Center (SERC) Symposium on VLSI Design, research results, and outreach programs. Processor chips completed or under development are listed. Research results summarized include a design technique to harden complementary metal oxide semiconductors (CMOS) memory circuits against single event upset (SEU); improved circuit design procedures; and advances in computer aided design (CAD), communications, computer architectures, and reliability design. Also described is a high school teacher program that exposes teachers to the fundamentals of digital logic design.

  9. Discriminated neutron and X-ray radiography using multi-color scintillation detector

    NASA Astrophysics Data System (ADS)

    Nittoh, Koichi; Takahara, Takeshi; Yoshida, Tadashi; Tamura, Toshiyuki

    1999-06-01

    A new conversion screen Gd 2O 2S:Eu is developed, which emits red light on irradiation by thermal neutrons. By applying this in combination with the currently used Gd 2O 2S:Tb, a green-light scintillator, in the radiography under a neutron + X-ray coexisting field, we can easily separate the neutron image and the X-ray image by simple color-image processing. This technique enables a non-destructive and detailed inspection of industrial products composed both of light elements (water, plastics, etc.) and heavy elements (metals), widening the horizon of new applications.

  10. A machine independent expert system for diagnosing environmentally induced spacecraft anomalies

    NASA Technical Reports Server (NTRS)

    Rolincik, Mark J.

    1991-01-01

    A new rule-based, machine independent analytical tool for diagnosing spacecraft anomalies, the EnviroNET expert system, was developed. Expert systems provide an effective method for storing knowledge, allow computers to sift through large amounts of data pinpointing significant parts, and most importantly, use heuristics in addition to algorithms which allow approximate reasoning and inference, and the ability to attack problems not rigidly defines. The EviroNET expert system knowledge base currently contains over two hundred rules, and links to databases which include past environmental data, satellite data, and previous known anomalies. The environmental causes considered are bulk charging, single event upsets (SEU), surface charging, and total radiation dose.

  11. AVR microcontroller simulator for software implemented hardware fault tolerance algorithms research

    NASA Astrophysics Data System (ADS)

    Piotrowski, Adam; Tarnowski, Szymon; Napieralski, Andrzej

    2008-01-01

    Reliability of new, advanced electronic systems becomes a serious problem especially in places like accelerators and synchrotrons, where sophisticated digital devices operate closely to radiation sources. One of the possible solutions to harden the microprocessor-based system is a strict programming approach known as the Software Implemented Hardware Fault Tolerance. Unfortunately, in real environments it is not possible to perform precise and accurate tests of the new algorithms due to hardware limitation. This paper highlights the AVR-family microcontroller simulator project equipped with an appropriate monitoring and the SEU injection systems.

  12. Radiation Issues and Applications of Floating Gate Memories

    NASA Technical Reports Server (NTRS)

    Scheick, L. Z.; Nguyen, D. N.

    2000-01-01

    The radiation effects that affect various systems that comprise floating gate memories are presented. The wear-out degradation results of unirradiated flash memories are compared to irradiated flash memories. The procedure analyzes the failure to write and erase caused by wear-out and degradation of internal charge pump circuits. A method is described for characterizing the radiation effects of the floating gate itself. The rate dependence, stopping power dependence, SEU susceptibility and applications of floating gate in radiation environment are presented. The ramifications for dosimetry and cell failure are discussed as well as for the long term use aspects of non-volatile memories.

  13. Analysis of space radiation data of semiconductor memories

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Brucker, G. J.; Stauffer, C. A.

    1996-01-01

    This article presents an analysis of radiation effects for several select device types and technologies aboard the Combined Release and Radiation Effects Satellite (CRRES) satellite. These space-flight measurements covered a period of about 14 months of mission lifetime. Single Event Upset (SEU) data of the investigated devices from the Microelectronics Package (MEP) were processed and analyzed. Valid upset measurements were determined by correcting for invalid readings, hard failures, missing data tapes (thus voids in data), and periods over which devices were disabled from interrogation. The basic resolution time of the measurement system was confirmed to be 2 s. Lessons learned, important findings, and recommendations are presented.

  14. The Imagine the Universe! E/PO Program

    NASA Technical Reports Server (NTRS)

    Lochner, James C.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Since 1996, the Imagine the Universe! E/PO program has brought information and curriculum support materials to upper middle school, high school, and lower undergraduate students and their teachers on topics in the Structure and Evolution of the Universe (SEU) theme. The Imagine E/PO program consists of a web site, a series of posters and information/activity booklets, and a repertoire of educator workshops. We involve both scientists and educators in the development and testing of the materials. We describe here the various aspects of this program.

  15. Radiation Testing, Characterization and Qualification Challenges for Modern Microelectronics and Photonics Devices and Technologies

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Cohn, Lewis M.

    2008-01-01

    At GOMAC 2007, we discussed a selection of the challenges for radiation testing of modern semiconductor devices focusing on state-of-the-art memory technologies. This included FLASH non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs). In this presentation, we extend this discussion in device packaging and complexity as well as single event upset (SEU) mechanisms using several technology areas as examples including: system-on-a-chip (SOC) devices and photonic or fiber optic systems. The underlying goal is intended to provoke thought for understanding the limitations and interpretation of radiation testing results.

  16. Laser-induced fluorescence of phosphors for remote cryogenic thermometry

    SciTech Connect

    Beshears, D.L.; Capps, G.J.; Cates, M.R.; Simmons, C.M.; Schwenterly, S.W.

    1990-01-01

    Remote cryogenic temperature measurements can be made by inducing fluorescence in phosphors with temperature-dependent emissions and measuring the emission lifetimes. The thermographic phosphor technique can be used for making precision, non-contact, cryogenic temperature measurements in electrically hostile environments, such as high DC electric or magnetic fields. NASA is interested in utilizing these thermographic phosphors for mapping hot spots on cryogenic tank walls. Europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:Eu) and magnesium fluorogermanate doped with manganese (Mg{sub 4}(F)GeO{sub 6}:Mn) are suitable for low-temperature surface thermometry. Several emission lines, excited by a 337 nm UV laser, provide fluorescence lifetimes having logarithmic dependence with temperatures from 4 to 125 Kelvin. A calibration curve for both La{sub 2}O{sub 2}S:Eu and Mg{sub 4}(F)GeO{sub 6}:Mn are presented as well as emission spectra taken at room temperature and 7 Kelvin.

  17. Adolescent women's contraceptive decision making.

    PubMed

    Weisman, C S; Plichta, S; Nathanson, C A; Chase, G A; Ensminger, M E; Robinson, J C

    1991-06-01

    A modified rational decision model incorporating salient events and social influences (particularly from sexual partners) is used to analyze adolescent women's consistent use of oral contraceptives (OCs) over a six-month period. Data are taken from a panel study of 308 clients of an inner-city family planning clinic. Expected OC use was computed for each subject on the basis of subjective expected utility (SEU) theory, and is found in multivariate analyses to be a significant predictor of actual OC use. In addition, variables representing baseline and follow-up partner influences, the salience of pregnancy for the subject, and positive side effects of OCs during the first months of use are found to predict OC use. Partner's support of OC use during follow-up and positive side effects of OCs are found to predict OC use among subjects for whom OC use was not the expected decision according to baseline SEU. Implications of the findings for models of adolescents' contraceptive behavior and for clinicians are discussed. PMID:1861049

  18. Beyond Einstein

    NASA Astrophysics Data System (ADS)

    Hertz, P.

    2003-03-01

    The Structure and Evolution of the Universe (SEU) theme within NASA's Office of Space Science seeks to explore and understand the dynamic transformations of energy in the Universe - the entire web of biological and physical interactions that determine the evolution of our cosmic habitat. This search for understanding will enrich the human spirit and inspire a new generation of explorers, scientists, and engineers. To that end, NASA's strategic planning process has generated a new Roadmap to enable those goals. Called "Beyond Einstein", this Roadmap identifies three science objectives for the SEU theme: (1) Find out what powered the Big Bang; (2) Observe how black holes manipulate space, time, and matter; and (3) Identify the mysterious dark energy pullingthe Universe apart. These objectives can be realized through a combination of large observatories (Constellation-X, LISA), moderate sized, PI-led missions (the Einstein Probes), and a contuinuing program of technology development, research and analysis, and education/public outreach. In this presentation, NASA's proposed Beyond Einstein Program will be described. The full Roadmap is available at http://universe.nasa.gov/.

  19. Monte Carlo simulation of an x-ray luminescence optical tomography scanner prototype

    SciTech Connect

    Rosas-González, S. E-mail: arnulfo@fisica.unam.mx; Martínez-Dávalos, A. E-mail: arnulfo@fisica.unam.mx; Rodríguez-Villafuerte, M. E-mail: arnulfo@fisica.unam.mx; Murrieta-Rodríguez, T. E-mail: arnulfo@fisica.unam.mx

    2014-11-07

    In this work we report the calculation of the deposited energy distribution produced by an x-ray luminescence optical tomography (XLOT) system in a phantom containing different concentrations of Gd{sub 2}O{sub 2}S:Eu nanoparticles. The calculations were performed via Monte Carlo simulation considering spectra from a W target x-ray tube operating between 30 and 90 kVp, with 1.0 mm Al added filtration. CT and XLOT tomographic images were reconstructed from the same data. The results show that XLOT has better detectability than CT alone, that the dose scales linearly with kVp for a fixed concentration of Gd{sub 2}O{sub 2}S:Eu and air-kerma rate, the scattered radiation contribution to the total dose and signal is about 20% and that the dose ratio for a 3 mm diameter insert containing 10 mg/ml Gd{sub 2}O{sub 2}S embedded in a 30 mm diameter water phantom is 6:1. This ratio drops to less than 2:1 for a 1 mg/ml concentration. Finally we show that the method of conjugate images can be used to correct for artifacts due to attenuation effects in XLOT images.

  20. Contemporary Issues in Ultra-Low Alpha Particle Counting

    NASA Astrophysics Data System (ADS)

    Gordon, Michael

    Single-Event Upsets (SEU) in CMOS devices are caused by the passage of ionizing radiation either from terrestrial neutrons or from the natural alpha particle radiation within the materials surrounding the transistors. Interactions of the neutrons with the silicon cause spallation reactions which emit energetic highly ionizing elements. Alpha particles, on the other hand, can upset the devices through direct ionization rather than through a nuclear reaction as in the case of the neutrons. In order to minimize the alpha-particle component of SEU, the radiation from the materials within a distance 100 μm of the transistors, currently needs to have an alpha particle emissivity of less than 2 alpha particles per khr per square centimeter. Many alpha particle detectors have background levels that are larger than this, which can make these measurements inaccurate and time consuming. This talk will discuss what is involved in making alpha particle emissivity measurements of materials used in the semiconductor industry using an ultra-low background commercially-available ionization detector. Detector calibration and efficiency, radon adsorption on the samples, and the effect of surface charge on electrically insulating samples will be discussed.

  1. UV surface brightness of galaxies from the local universe to z ~ 5

    NASA Astrophysics Data System (ADS)

    Lerner, Eric J.; Falomo, Renato; Scarpa, Riccardo

    2014-05-01

    The Tolman test for surface brightness (SB) dimming was originally proposed as a test for the expansion of the universe. The test, which is independent of the details of the assumed cosmology, is based on comparisons of the SB of identical objects at different cosmological distances. Claims have been made that the Tolman test provides compelling evidence against a static model for the universe. In this paper we reconsider this subject by adopting a static Euclidean universe (SEU) with a linear Hubble relation at all z (which is not the standard Einstein-de Sitter model), resulting in a relation between flux and luminosity that is virtually indistinguishable from the one used for ΛCDM models. Based on the analysis of the UV SB of luminous disk galaxies from HUDF and GALEX datasets, reaching from the local universe to z 5, we show that the SB remains constant as expected in a static universe. A re-analysis of previously published data used for the Tolman test at lower redshift, when treated within the same framework, confirms the results of the present analysis by extending our claim to elliptical galaxies. We conclude that available observations of galactic SB are consistent with a SEU model. We do not claim that the consistency of the adopted model with SB data is sufficient by itself to confirm what would be a radical transformation in our understanding of the cosmos. However, we believe this result is more than sufficient reason to examine this combination of hypotheses further.

  2. Micro-Inspector Avionics Module (MAM): A Self-Contained Low Power, Reconfigurable Avionics Platform for Small Spacecrafts and Instruments

    NASA Technical Reports Server (NTRS)

    Ashtijou, Mohammad; He, Yutao; Watson, R. Kevin; Bolotin, Gary S.

    2006-01-01

    This paper describes development of a radiation tolerant, low power, reconfigurable avionics module aimed at meeting the avionics needs of the JPL Micro-Inspector spacecraft. This module represents a complete avionics system, consisting of two PowerPC 405 CPUs embedded within a reconfigurable FPGA fabric of over 8 Million logic gates, 64MB of EDAC protected Flash storage and 128MB of EDAC protected DDR SDRAM or SDRAM memories, along with FPGA SEU mitigation logic, and all necessary power conversion. Processor SEU mitigation is achieved by running the two processors in a lock-step and compare configuration. All of these building blocks are integrated into a double sided circuit board that takes as little as 6 square inches of board space. This module can be embedded into a user system as part of a bigger circuit assembly or as a self contained module. This module is being developed as part of a JPL led Micro-Inspector Program, funded by NASA ESMD aimed at producing a 10Kg micro spacecraft.

  3. Development of a radiation-hardened SRAM with EDAC algorithm for fast readout CMOS pixel sensors for charged particle tracking

    NASA Astrophysics Data System (ADS)

    Wei, X.; Li, B.; Chen, N.; Wang, J.; Zheng, R.; Gao, W.; Wei, T.; Gao, D.; Hu, Y.

    2014-08-01

    CMOS pixel sensors (CPS) are attractive for use in the innermost particle detectors for charged particle tracking due to their good trade-off between spatial resolution, material budget, radiation hardness, and readout speed. With the requirements of high readout speed and high radiation hardness to total ionizing dose (TID) for particle tracking, fast readout CPS are composed by integrating a data compression block and two SRAM IP cores. However, the radiation hardness of the SRAM IP cores is not as high as that of the other parts in CPS, and thus the radiation hardness of the whole CPS chip is lowered. Especially, when CPS are migrated into 0.18-μm processes, the single event upset (SEU) effects should be also considered besides TID and single event latchup (SEL) effects. This paper presents a radiation-hardened SRAM with enhanced radiation hardness to SEU. An error detection and correction (EDAC) algorithm and a bit-interleaving storage strategy are adopted in the design. The prototype design has been fabricated in a 0.18-μm process. The area of the new SRAM is increased 1.6 times as compared with a non-radiation-hardened SRAM due to the integration of EDAC algorithm and the adoption of radiation hardened layout. The access time is increased from 5 ns to 8 ns due to the integration of EDAC algorithm. The test results indicate that the design satisfy requirements of CPS for charged particle tracking.

  4. Studying the Impact of Space Weather on the RASAT Satellite

    NASA Astrophysics Data System (ADS)

    Kaplan, Mehmet; Hudaverdi, Murat; Ergin, Tulun

    Space radiation composed of highly energetic particles, such as protons, electrons, and heavy ions, has mainly two impacts on satellites: Cumulative effects and single event effects. The single event effect is caused by a single high energy particle interacting with the electronic component of the satellite. Most of the single event effects are not permanent, which are called Single Event Upsets (SEUs). SEUs might change the data in the micro-electronics but it won’t cause irreparable damage. RASAT is a Turkish Remote Sensing Satellite orbiting at LEO and keeping regular logs about SEUs happening on board. In this presentation, we show the results of our correlation studies about the anomalies in the RASAT SEU logs with the solar flares reported by GOES satellites during the period of 2011-2013. In order to better interpret the RASAT SEU logs especially during major solar events, we study the relations between the flux levels at LEO and GEO with the help of the models. So, here we report on our preliminary results about the comparisons between the data produced by the models available in SPENVIS and the measured data.

  5. System level radiation validation studies for the CMS HCAL front-end electronics

    SciTech Connect

    J. Whitmore et al.

    2003-10-20

    Over a 10 year operating period, the CMS Hadron Calorimeter (HCAL) detector will be exposed to radiation fields of approximately 1 kRad of total ionizing dose (TID) and a neutron fluence of 4E11 n/cm{sup 2}. All front-end electronics must be qualified to survive this radiation environment with no degradation in performance. In addition, digital components in this environment can experience single-event upset (SEU) and single-event latchup (SEL). A measurement of these single-event effects (SEE) for all components is necessary in order to understand the level that will be encountered. System level studies of the performance of the front-end boards in a 200 MeV proton beam are presented. Limits on the latch-up immunity along with the expected SEU rate for the full front-end system have been measured. The first results from studies of the performance of the two Fermilab custom-designed chips in a radiation environment also are shown.

  6. The influence of oxygen partial pressure on material properties of Eu3+-doped Y2O2S thin film deposited by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Ali, A. G.; Dejene, B. F.; Swart, H. C.

    2016-01-01

    Eu3+-doping has been of interest to improve the luminescent characteristics of thin-film phosphors. Y2O2S:Eu3+ films have been grown on Si (100) substrates by using a Pulsed Laser Deposition technique. The thin films grown under different oxygen deposition pressure conditions have been characterized using structural and luminescent measurements. The X-ray diffraction patterns showed mixed phases of cubic and hexagonal crystal structures. As the oxygen partial pressure increased, the crystallinity of the films improved. Further increase of the O2 pressure to 140 mtorr reduced the crystallinity of the film. Similarly, both scanning electron microscopy and Atomic Force Microscopy confirmed that an increase in O2 pressure affected the morphology of the films. The average band gap of the films calculated from diffuse reflectance spectra using the Kubelka-Munk function was about 4.75 eV. The photoluminescence measurements indicated red emission of Y2O2S:Eu3+ thin films with the most intense peak appearing at 619 nm, which is assigned to the 5D0-7F2 transition of Eu3+. This most intense peak was totally quenched at higher O2 pressures. This phosphor may be a promising material for applications in the flat panel displays.

  7. The Structure & Evolution of the Universe Education Forum: Opportunities for scientist involvement in education and public outreach

    NASA Astrophysics Data System (ADS)

    Steel, S. J.; Gould, R. R.; Dussault, M. E.; Grier, J. A.

    2004-08-01

    The Universe Forum is one of four Education and Public Outreach forums funded by NASA's Office of Space Science. We are located at the Harvard-Smithsonian Center for Astrophysics. This poster will present examples of high leverage education and public outreach programs developed by the Forum in collaboration with NASA SEU missions and other members of NASA's OSS E/PO effort. These include a professional development experience for teachers in the Cambridge, MA public school system, community workshops with organizations such as the Girl Scouts, and working with SEU mission E/PO partners to present a short course on modeling the universe, which debuted at the 2004 NSTA national meeting and will be offered at the 2004 AAS HEAD meeting. We will also detail future projects and opportunities for scientist involvement in E/PO in both formal and informal education arenas. Particular emphasis will be given to opportunities in 2005, a year that marks both the World Year of Physics and the Einstein Centennial celebrations.

  8. Comparison with industrial oxysulfide phosphors for solid state lighting

    NASA Astrophysics Data System (ADS)

    Pote, S. S.

    2016-05-01

    Y2O2S:Eu3+ was prepared by the flux method which is different from conventional solid state reaction and has many advantages over the conventional method in terms of ease of preparation and yield also. In this paper we have reported the crystal structure, XRD and method of preparation of Y2O2S:Eu3+ along with Eu3+ mechanism of emission and excitation with reference to solid state lighting. In the emission spectra, the strongest red-emission lines at 626 and 616 nm are due to transition from 5D0 → 7F2 level. The stronger emission at λem=626 nm confirms the formation of the oxysulfide host. We also made a comparison of our prepared sample with commercial sample from NICHIA Corporation Japan in terms of PL intensity which results that our sample is equally intense as that of NICHIA's sample. It is suggested that these characteristics can be useful for obtaining a low cost, red phosphor for the solid state lighting using near UV LED.

  9. Simulation of the Effects of Radiation on a Satellite Memory and Improving Its Fault-Tolerant Ability, Using SIHFT

    NASA Astrophysics Data System (ADS)

    Nematollahzadeh, S. M.; Jamshidifar, A. A.

    This chapter describes a software environment based on VirSim tool to simulate the effect of radiation on COTS (commercial off-the-shelf) memories and shows the efficiency of the software EDAC (error detection and correction). As a case study, a sample student LEO (low Earth orbit) satellite with 8-MB (megabytes) RAM (random access memory) is considered and software EDAC for detecting and correcting the faults in the memory is implemented. The software EDAC is responsible for reliability of data in this 8-MB RAM. One separated task in VirSim tool has been developed for injection SEUs (single event upset) to the 8-MB memory of the satellite. The SEUs have been generated based on the ARGOS satellite reports. According to these reports the average of SEUs is about 5.5 SEU/MB per day, where it generates about 5 MBU (multiple bit upset) out of any 100 SEU. About four of these MBUs are double events (2-bit upset in one word) and one of them is triple. The software EDAC detects and corrects all 1-bit SEUs and detects double MBUs but it does not guarantee the detection of triple MBUs. This kind of simulation is very simple, accessible, and very close to the real environment and one can use it for checking effectiveness of the approach. The simulation results demonstrate efficacy of the approach in terms of fault detection and correction capabilities.

  10. Space and military radiation effects in silicon-on-insulator devices

    SciTech Connect

    Schwank, J.R.

    1996-09-01

    Advantages in transient ionizing and single-event upset (SEU) radiation hardness of silicon-on-insulator (SOI) technology spurred much of its early development. Both of these advantages are a direct result of the reduced charge collection volume inherent to SOI technology. The fact that SOI transistor structures do not include parasitic n-p-n-p paths makes them immune to latchup. Even though considerable improvement in transient and single-event radiation hardness can be obtained by using SOI technology, there are some attributes of SOI devices and circuits that tend to limit their overall hardness. These attributes include the bipolar effect that can ultimately reduce the hardness of SOI ICs to SEU and transient ionizing radiation, and charge buildup in buried and sidewall oxides that can degrade the total-dose hardness of SOI devices. Nevertheless, high-performance SOI circuits can be fabricated that are hardened to both space and nuclear radiation environments, and radiation-hardened systems remain an active market for SOI devices. The effects of radiation on SOI MOS devices are reviewed.

  11. Injecting Artificial Memory Errors Into a Running Computer Program

    NASA Technical Reports Server (NTRS)

    Bornstein, Benjamin J.; Granat, Robert A.; Wagstaff, Kiri L.

    2008-01-01

    Single-event upsets (SEUs) or bitflips are computer memory errors caused by radiation. BITFLIPS (Basic Instrumentation Tool for Fault Localized Injection of Probabilistic SEUs) is a computer program that deliberately injects SEUs into another computer program, while the latter is running, for the purpose of evaluating the fault tolerance of that program. BITFLIPS was written as a plug-in extension of the open-source Valgrind debugging and profiling software. BITFLIPS can inject SEUs into any program that can be run on the Linux operating system, without needing to modify the program s source code. Further, if access to the original program source code is available, BITFLIPS offers fine-grained control over exactly when and which areas of memory (as specified via program variables) will be subjected to SEUs. The rate of injection of SEUs is controlled by specifying either a fault probability or a fault rate based on memory size and radiation exposure time, in units of SEUs per byte per second. BITFLIPS can also log each SEU that it injects and, if program source code is available, report the magnitude of effect of the SEU on a floating-point value or other program variable.

  12. A Proposal for a Space Flight Demonstration of a Dynamically Reconfigurable Programmable Module Which Uses Firmware to Realise an Astrium Patented Cosmic Random Number Generator for Generating Secure Cryptographic Keys

    NASA Astrophysics Data System (ADS)

    Taylor, Adam; Bennie, Peter; Guyon, Fredric; Cameron, Iain; Glanfield, James; Emam, Omar

    2013-08-01

    This paper describes a proposal for a space flight demonstration of a low power, compact Dynamically Reconfigurable Programmable Board (DRPB) based upon a minor evolution of the Astrium Janus payload for UKube 1. The Janus payload is one of a number of the payloads selected to be part of the first national UK-Cube satellite (UKube) [1] to be sponsored by the UK Space Agency. In the UKube configuration the demonstrator performs two experiments the first uses firmware to realise an Astrium patented cosmic random number generator for generating secure cryptographic keys while the second monitors the large high performance SRAM based FPGA for SEU and SEFI events allowing correlation with predicted upset rates. This experiment is called the Janus experiment after the two-faced roman god of beginnings and transitions, transitioning from clear text to encrypted and marking the beginning of flying advanced FPGA's on suitable missions.

  13. Heavy ion induced Single Event Phenomena (SEP) data for semiconductor devices from engineering testing

    NASA Technical Reports Server (NTRS)

    Nichols, Donald K.; Huebner, Mark A.; Price, William E.; Smith, L. S.; Coss, James R.

    1988-01-01

    The accumulation of JPL data on Single Event Phenomena (SEP), from 1979 to August 1986, is presented in full report format. It is expected that every two years a supplement report will be issued for the follow-on period. This data for 135 devices expands on the abbreviated test data presented as part of Refs. (1) and (3) by including figures of Single Event Upset (SEU) cross sections as a function of beam Linear Energy Transfer (LET) when available. It also includes some of the data complied in the JPL computer in RADATA and the SPACERAD data bank. This volume encompasses bipolar and MOS (CMOS and MHNOS) device data as two broad categories for both upsets (bit-flips) and latchup. It also includes comments on less well known phenomena, such as transient upsets and permanent damage modes.

  14. Single event upset sensitivity of low power Schottky devices

    NASA Technical Reports Server (NTRS)

    Price, W. E.; Nichols, D. K.; Measel, P. R.; Wahlin, K. L.

    1982-01-01

    Data taken from tests involving heavy ions in the Berkeley 88 in. cyclotron being directed at low power Schottky barrier devices are reported. The tests also included trials in the Harvard cyclotron with 130 MeV protons, and at the U.C. Davis cyclotron using 56 MeV protons. The experiments were performed to study the single event upsets in MSI logic devices containing flip-flops. Results are presented of single-event upsets (SEU) causing functional degradation observed in post-exposure tests of six different devices. The effectiveness of the particles in producing SEUs in logic device functioning was found to be directly proportional to the proton energy. Shielding was determined to offer negligible protection from the particle bombardment. The results are considered significant for the design and fabrication of LS devices for space applications.

  15. Plastic optical fibre sensor for in-vivo radiation monitoring during brachytherapy

    NASA Astrophysics Data System (ADS)

    Woulfe, P.; Sullivan, F. J.; Lewis, E.; O'Keeffe, S.

    2015-09-01

    An optical fibre sensor is presented for applications in real-time in-vivo monitoring of the radiation dose a cancer patient receives during seed implantation in Brachytherapy. The sensor is based on radioluminescence whereby radiation sensitive scintillation material is embedded in the core of a 1mm plastic optical fibre. Three scintillation materials are investigated: thallium-doped caesium iodide (CsI:Tl), terbium-doped gadolinium oxysulphide (Gd2O2S:Tb) and europium-doped lanthanum oxysulphide (La2O2S:Eu). Terbium-doped gadolinium oxysulphide was identified as being the most suitable scintillator and further testing demonstrates its measureable response to different activities of Iodine-125, the radio-active source commonly used in Brachytherapy for treating prostate cancer.

  16. NAND FLASH Radiation Tolerant Intelligent Memory Stack (RTIMS FLASH)

    NASA Astrophysics Data System (ADS)

    Sellier, Charles; Wang, Pierre

    2014-08-01

    The NAND Flash Radiation Tolerant and Intelligent Memory Stack (RTIMS FLASH) is a User's Friendly, Plug-and- Play and Radiation Protected high density NAND Flash Memory. It provides a very high density, radiation hardened by design and non-volatile memory module suitable for all space applications such as commercial or scientific geo-stationary missions, earth observation, navigation, manned space vehicles and deep space scientific exploration. The Intelligent Memory Module embeds a very high density of non-volatile NAND Flash memory and one Intelligent Flash Memory Controller (FMC). The FMC provides the module with a full protection against the radiation effects such as SEL, SEFI and SEU. It's also granting the module with bad block immunity as well as high level service functions that will benefit to the user's applications.

  17. The ToPiX v4 prototype for the triggerless readout of the PANDA silicon pixel detector

    NASA Astrophysics Data System (ADS)

    Mazza, G.; Calvo, D.; De Remigis, P.; Mignone, M.; Olave, J.; Rivetti, A.; Wheadon, R.; Zotti, L.

    2015-01-01

    ToPiX v4 is the prototype for the readout of the silicon pixel sensors for the Micro Vertex Detector of the PANDA experiment. ToPiX provides position, time and energy measurement of the incoming particles and is designed for the triggerless environment foreseen in PANDA. The prototype includes 640 pixels with a size of 100 × 100 μm2, a 160 MHz time stamp distribution circuit to measure both particle arrival time and released energy (via ToT technique) and the full control logic. The ASIC is designed in a 0.13 μm CMOS technology with SEU protection techniques for the digital parts.

  18. Summary of Proton Test on the Quick Logic QL3025 at Indiana University

    NASA Technical Reports Server (NTRS)

    Katz, Richard

    1998-01-01

    This issue of the Programmable Logic Application Notes is a compilation of topics: (1) Proton irradiation tests were performed on the Quick Logic QL3025 at the Indian University Cyclotron facility. The devices, tests, and results are discussed; (2) The functional failure of EEPROM's in heavy ion environment is presented; (3) the Act 1 architecture is summarized; (4) Antifuse hardness and hardness testing is updated; the single even upset (SEU) response of hardwired flip-flops is also presented; (4) Total dose results of the ACT 2 and ACT 3 circuits is presented in a chart; (5) Recent sub-micron devices testing of total dose is presented in a chart along with brief discussion; and (6) a reference to the WWW site for more articles of interest.

  19. Multi-physics modelling contributions to investigate the atmospheric cosmic rays on the single event upset sensitivity along the scaling trend of CMOS technologies.

    PubMed

    Hubert, G; Regis, D; Cheminet, A; Gatti, M; Lacoste, V

    2014-10-01

    Particles originating from primary cosmic radiation, which hit the Earth's atmosphere give rise to a complex field of secondary particles. These particles include neutrons, protons, muons, pions, etc. Since the 1980s it has been known that terrestrial cosmic rays can penetrate the natural shielding of buildings, equipment and circuit package and induce soft errors in integrated circuits. Recently, research has shown that commercial static random access memories are now so small and sufficiently sensitive that single event upsets (SEUs) may be induced from the electronic stopping of a proton. With continued advancements in process size, this downward trend in sensitivity is expected to continue. Then, muon soft errors have been predicted for nano-electronics. This paper describes the effects in the specific cases such as neutron-, proton- and muon-induced SEU observed in complementary metal-oxide semiconductor. The results will allow investigating the technology node sensitivity along the scaling trend. PMID:24500239

  20. [The Paduan doctor Alessandro Pellati, his library and the first edition of De medicorum astrologia].

    PubMed

    Fattori, D

    2008-01-01

    The article prints the text of a document in the Archivio di Stato, Venice, comprising a list of books intended for auction, with an estimate of their value. THey constitute the private library of Alessandro Pellati (d. 1487), a Paduan doctor about whom nothing is known, except his name appears in the colophon of the first edition of a short treatise attributed to Hippocrates, the De medicorum astrologia seu de esse aegrorum, translated into Latin and published in Padua in 1483. The considerable number of astrological works in his library show that Pellati was keenly interested in the subject which, under the title of "natural magic", had assumed a significant place in medical studies at that time, particularly in Padua. PMID:19618535

  1. Single event upsets in gallium arsenide pseudo-complementary MESFET logic

    SciTech Connect

    Fouts, D.J.; Wolfe, K.; Van Dyk, S.E.; Weatherford, T.R.; McMorrow, D.; Melinger, J.S.; Tran, L.H.; Campbell, A.B.

    1995-12-01

    An introduction to gallium arsenide (GaAs) Pseudo-Complementary MESFET Logic (PCML) circuits is presented. PCML was developed to reduce the sensitivity of high-speed GaAs logic to radiation-induced single event upsets (SEUs). Experiments for testing the single-event upset (SEU) sensitivity of GaAs PCML integrated circuits (ICs) are described. The results of the experiments are analyzed. This new type of high-speed, low-power, GaAs logic provides decreased sensitivity to SEUs compared to more traditional circuit designs such as Directly-Coupled FET Logic (DCFL). PCML is fully compatible with existing GaAs E/D MESFET fabrication processes, such as those commonly used to make DCFL.

  2. Technology for Elevated Temperature Tests of Structural Panels

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.

    1999-01-01

    A technique for full-field measurement of surface temperature and in-plane strain using a single grid imaging technique was demonstrated on a sample subjected to thermally-induced strain. The technique is based on digital imaging of a sample marked by an alternating line array of La2O2S:Eu(+3) thermographic phosphor and chromium illuminated by a UV lamp. Digital images of this array in unstrained and strained states were processed using a modified spin filter. Normal strain distribution was determined by combining unstrained and strained grid images using a single grid digital moire technique. Temperature distribution was determined by ratioing images of phosphor intensity at two wavelengths. Combined strain and temperature measurements demonstrated on the thermally heated sample were DELTA-epsilon = +/- 250 microepsilon and DELTA-T = +/- 5 K respectively with a spatial resolution of 0.8 mm.

  3. Spatial Analysis of Galactic Cosmic Ray Particles in Low Earth Orbit/Near Equator Orbit Using SPENVIS

    NASA Astrophysics Data System (ADS)

    Suparta, W.; Zulkeple, S. K.

    2014-04-01

    The space environment has grown intensively harmful to spacecraft and astronauts. Galactic cosmic rays (GCRs) are one of the radiation sources that composed of high energetic particles originated from space and capable of damaging electronic systems through single event upset (SEU) process. In this paper, we analyzed GCR fluxes at different altitudes by using Space Environment Information System (SPENVIS) software and the results are compared to determine their intensities with respect to distance in the Earth's orbit. The altitudes are set at low earth orbit (400 km and 685 km), medium earth orbit (19,100 km and 20,200 km) and high earth orbit (35,793 km and 1,000,000 km). Then, within Low Earth Orbit (LEO) near the equator (NEqO), we used altitude of 685 km to compare GCRs with the intensities of solar particles and trapped particles in the radiation belt to determine the significance of GCRs in the orbit itself.

  4. Single Event Effects Test Results for the Actel ProASIC Plus and Altera Stratix-II Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Allen, Gregory R.; Swift, Gary M.

    2006-01-01

    This work describes radiation testing of Actel's ProASIC Plus and Altera's Stratix-II FPGAs. The Actel Device Under Test (DUT) was a ProASIC Plus APA300-PQ208 nonvolatile, field reprogrammable device which is based on a 0.22micron flash-based LVCMOS technology. Limited investigation has taken place into flash based FPGA technologies, therefore this test served as a preliminary reference point for various SEE behaviors. The Altera DUT was a Stratix-II EP2S60F1020C4. Single Event Upset (SEU) and Single Event Latchup (SEL) were the focus of these studies. For the Actel, a latchup test was done at an effective LET of 75.0 MeV-sq cm/mg at room temperature, and no latchup was detected when irradiated to a total fluence of 1 x 10(exp 7) particles/sq cm. The Altera part was shown to latchup at room temperature.

  5. Simulation of the dynamic inefficiency of the CMS pixel detector

    NASA Astrophysics Data System (ADS)

    Bartók, M.

    2015-05-01

    The Pixel Detector is the innermost part of the CMS Tracker. It therefore has to prevail in the harshest environment in terms of particle fluence and radiation. There are several mechanisms that may decrease the efficiency of the detector. These are mainly caused by data acquisition (DAQ) problems and/or Single Event Upsets (SEU). Any remaining efficiency loss is referred to as the dynamic inefficiency. It is caused by various mechanisms inside the Readout Chip (ROC) and depends strongly on the data occupancy. In the 2012 data, at high values of instantaneous luminosity the inefficiency reached 2% (in the region closest to the interaction point) which is not negligible. In the 2015 run higher instantaneous luminosity is expected, which will result in lower efficiencies; therefore this effect needs to be understood and simulated. A data-driven method has been developed to simulate dynamic inefficiency, which has been shown to successfully simulate the effects.

  6. Radiation effects testing at the 88-Inch Cyclotron

    NASA Astrophysics Data System (ADS)

    Phair, Larry

    2015-10-01

    In addition to basic research, the 88-Inch Cyclotron provides a crucial service to organizations involved in the U.S. space program. The space application testing includes heavy-ion beams for single event upset (SEU) tests on integrated circuits. A ``Cocktail'' beam (where multiple ions of the same mass/charge ratio are injected into the cyclotron) is used to mimic cosmic ray damage of integrated circuits. Plots of the failure cross section versus amount of energy deposited (LET = linear energy transfer) for different beams are used to predict how the circuit components will perform in a radiation environment such as space. We will review the analysis of such data and their trends.

  7. Silicon-on-insulator field effect transistor with improved body ties for rad-hard applications

    DOEpatents

    Schwank, James R.; Shaneyfelt, Marty R.; Draper, Bruce L.; Dodd, Paul E.

    2001-01-01

    A silicon-on-insulator (SOI) field-effect transistor (FET) and a method for making the same are disclosed. The SOI FET is characterized by a source which extends only partially (e.g. about half-way) through the active layer wherein the transistor is formed. Additionally, a minimal-area body tie contact is provided with a short-circuit electrical connection to the source for reducing floating body effects. The body tie contact improves the electrical characteristics of the transistor and also provides an improved single-event-upset (SEU) radiation hardness of the device for terrestrial and space applications. The SOI FET also provides an improvement in total-dose radiation hardness as compared to conventional SOI transistors fabricated without a specially prepared hardened buried oxide layer. Complementary n-channel and p-channel SOI FETs can be fabricated according to the present invention to form integrated circuits (ICs) for commercial and military applications.

  8. Design of high performance and radiation hardened SPARC-V8 processor

    NASA Astrophysics Data System (ADS)

    Yuanfu, Zhao; Hui, Qin; Heping, Peng; Lixin, Yu

    2015-11-01

    Design of a highly reliable SPARC-V8 processor for space applications requires consideration single-event effects including single event upsets, single event transients, single event latch-up, as well as cumulative effects such as the total ionizing dose (TID). In this paper, the fault tolerance of the SPARC-V8 processor to radiation effects is discussed in detail. The SPARC-V8 processor, fabricated in the 65 nm CMOS process, achieves a frequency of 300 MHz with a core area of 9.78 × 9.78 mm2, and it is demonstrated that its radiation hardened performance is suitable for operating in a space environment through the key elements' experiments, which show TID resistance to 300 krad(Si), SEL immunity to greater than 92.5 MeV·cm2/mg, and an SEU error rate of 2.51 × 10-4 per day.

  9. Charge generation by heavy ions in power MOSFETs, burnout space predictions, and dynamic SEB sensitivity

    NASA Astrophysics Data System (ADS)

    Stassinopoulos, E. G.; Brucker, G. J.; Calvel, P.; Baiget, A.; Peyrotte, C.; Gaillard, R.

    1992-12-01

    The transport, energy loss, and charge production of heavy ions in the sensitive regions of IRF 150 power MOSFETs are described. The dependence and variation of transport parameters with ion type and energy relative to the requirements for single event burnout in this part type are discussed. Test data taken with this power MOSFET are used together with analyses by means of a computer code of the ion energy loss and charge production in the device to establish criteria for burnout and parameters for space predictions. These parameters are then used in an application to predict burnout rates in a geostationary orbit for power converters operating in a dynamic mode. Comparisons of rates for different geometries in simulating SEU (single event upset) sensitive volumes are presented.

  10. Radiation Hard 0.13 Micron CMOS Library at IHP

    NASA Astrophysics Data System (ADS)

    Jagdhold, U.

    2013-08-01

    To support space applications we have developed an 0.13 micron CMOS library which should be radiation hard up to 200 krad. The article describes the concept to come to a radiation hard digital circuit and was introduces in 2010 [1]. By introducing new radiation hard design rules we will minimize IC-level leakage and single event latch-up (SEL). To reduce single event upset (SEU) we add two p-MOS transistors to all flip flops. For reliability reasons we use double contacts in all library elements. The additional rules and the library elements are integrated in our Cadence mixed signal design kit, “Virtuoso” IC6.1 [2]. A test chip is produced with our in house 0.13 micron BiCMOS technology, see Ref. [3]. As next step we will doing radiation tests according the european space agency (ESA) specifications, see Ref. [4], [5].

  11. Radiation Hard 0.25 Micron CMOS Library at IHP

    NASA Astrophysics Data System (ADS)

    Jagdhold, U.

    2008-08-01

    To support space applications we have produced a test chip with our in house 0.25 micron BiCMOS- Technology. Then the chips were radiated and measured. During measurements no threshold voltage shift and no single event latchup (SEL) were obtained up to a level of 200 krad. As conclusion of the measurement we developed new radiation hard design rules and according to these rules we created a new radiation hard CMOS library. With this new library we produced a Leon3 chip with triple module redundancy. Single event upsets did occur. Therefore we upgrade the library to make the flip flops more resistant against single event upset (SEU) by adding two p-MOS transistors.

  12. Creation of a Radiation Hard 0.13 Micron CMOS Library at IHP

    NASA Astrophysics Data System (ADS)

    Jagdhold, U.

    2010-08-01

    To support space applications we will develop an 0.13 micron CMOS library which should be radiation hard up to 200 krad. By introducing new radiation hard design rules we will minimize IC-level leakage and single event latchup (SEL). To reduce single event upset (SEU) we will add two p-MOS transistors to all flip flops. For reliability reasons we will use double contacts in all library elements. The additional rules and the library elements will then be integrated in our Cadence mixed signal designkit, Virtuoso IC6.1 [1]. A test chip will be produced with our in house 0.13 micron BiCMOS technology, see Ref. [2].Thereafter we will doing radiation tests according the ESA specifications, see Ref. [3], [4].

  13. Synthesis of Ba2SiO4:Eu(2+) by a Hybrid Process and Its Luminescent Properties.

    PubMed

    Park, Jung Hye; Ahn, Wonsik; Kim, Young Jin

    2015-10-01

    Ba2SiO4:Eu(2+) powders were prepared using a sol-gel-combustion (hybrid) process with tetraethyl orthosilicate (TEOS) and colloidal silica (C-SiO2) as Si sources. The effects of the silicon sources and preparation conditions on phase formation and luminescent properties were investigated. The B2S:Eu(2+) powders synthesized with TEOS were composed of the irregular particles, whereas C-SiO2 was more conducive to uniform particle distribution for the Ba2SiO4:Eu(2+) powders, leading to the enhancement of the emission intensity. The photoluminescence spectra of the synthesized powders exhibited broad excitation bands spanning 250 to 450 nm, and strong green-emission bands, whose intensities and positions were heavily dependent on the concentration of Eu(2+) and Sr(2+) substituted for Ba(2+) in Ba2SiO4. PMID:26726479

  14. The NASA Education Forum at SAO on the Structure and Evolution of the Universe

    NASA Technical Reports Server (NTRS)

    Gould, Roy; Cooper, Larry (Technical Monitor)

    2005-01-01

    The past year for the SEU Forum has been a highly productive one and has moved us forward on three major objectives: 1) Using the Einstein Centennial to involve the public in the Universe Exploration theme, with emphasis on exciting discoveries about dark energy, cosmology, and black holes; 2) Further implementing the recommendations of the Knappenberger Report, in order to strengthen the educational coherence of our collective activities and our collaborations within NASA; and 3) Developing strategic partnerships with underserved communities and other key customers. Among our activities for the past year are the following: 1) Serving the Informal Science Education Communities; 2) Serving the Formal Education (Pre-college) Community; and 3) Serving Minority and Underserved Communities. A summary of goals, plans and activities for the year 9/15/05 through 9/14/06 are also presented.

  15. Test results of the Data Handling Processor for the DEPFET Pixel Vertex Detector

    NASA Astrophysics Data System (ADS)

    Lemarenko, M.; Hemperek, T.; Krüger, H.; Koch, M.; Lütticke, F.; Marinas, C.; Wermes, N.

    2013-01-01

    In the new Belle II detector, which is currently under construction at the SuperKEKB accelerator, a two layer pixel detector will be introduced to improve the vertex reconstruction in a ultra high luminosity environment. The pixel detector will be produced using the DEPFET technology. A new ASIC (Data Handling Processor or DHP) designed to steer the readout process, pre-process and compress the raw data has been developed. The DHP will be directly bump bonded to the balcony of the all-silicon DEPFET module. The current chip prototype has been produced in CMOS 90 nm. Its test results, including the data processing quality, the signal integrity of the gigabit transmission lines will be presented here. For the final chip, which will be produced using CMOS 65 nm, single event upset (SEU) cross sections were measured. An additional chip, containing memory blocks to be tested, was submitted and produced using this technology.

  16. Charge generation by heavy ions in power MOSFETs, burnout space predictions, and dynamic SEB sensitivity

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Brucker, G. J.; Calvel, P.; Baiget, A.; Peyrotte, C.; Gaillard, R.

    1992-01-01

    The transport, energy loss, and charge production of heavy ions in the sensitive regions of IRF 150 power MOSFETs are described. The dependence and variation of transport parameters with ion type and energy relative to the requirements for single event burnout in this part type are discussed. Test data taken with this power MOSFET are used together with analyses by means of a computer code of the ion energy loss and charge production in the device to establish criteria for burnout and parameters for space predictions. These parameters are then used in an application to predict burnout rates in a geostationary orbit for power converters operating in a dynamic mode. Comparisons of rates for different geometries in simulating SEU (single event upset) sensitive volumes are presented.

  17. Satellite anomalies caused by disturbed space weather

    NASA Astrophysics Data System (ADS)

    Allen, J. H.

    2003-04-01

    Seven types of satellite anomalies are discussed and examples are given from historical reports. Types of anomalies and their causes are: o Single Event Upsets (SEU) caused by penetrating energetic ions; o Deep dielectric ("bulk") charging (DDC) by high-energy electrons; o Surface charging by thermal electrons causing electrostatic discharge (ESD) and Phantom Commands (PC); o Magnetopause crossing events (MPE) that reverse ambient fields at geostationary satellite altitudes; o dB/dT of field-aligned currents causing satellite tumbling at lower altitudes; o Optical effects of high-energy ions on star-trackers and limb sensors; and o Power panel degradation from high-energy ions. Recent and older events are considered, in part because the problems recur even though technology has changed to take them into account and awareness of the conditions causing them seems widespread. Systematic anomaly reporting is requested to increase the significance of records collected for particular events.

  18. Bench-level characterization of a CMOS standard-cell D-latch using alpha-particle sensitive test circuits

    SciTech Connect

    Blaes, B.R.; Soli, G.A.; Buehler, M.G. )

    1991-12-01

    This paper describes a methodology for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. Measurements were made on a 1.6-{mu}m n-well CMOS 4k-bit test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 {mu}m was determined using these results and TRIM computer code. Using this collection depth and SPICE derived critical charge results on the latch design, an LET threshold of 34 Mev cm{sup 2}/mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV cm{sup 2}/mg was determined.

  19. Computational Algorithms for Device-Circuit Coupling

    SciTech Connect

    KEITER, ERIC R.; HUTCHINSON, SCOTT A.; HOEKSTRA, ROBERT J.; RANKIN, ERIC LAMONT; RUSSO, THOMAS V.; WATERS, LON J.

    2003-01-01

    Circuit simulation tools (e.g., SPICE) have become invaluable in the development and design of electronic circuits. Similarly, device-scale simulation tools (e.g., DaVinci) are commonly used in the design of individual semiconductor components. Some problems, such as single-event upset (SEU), require the fidelity of a mesh-based device simulator but are only meaningful when dynamically coupled with an external circuit. For such problems a mixed-level simulator is desirable, but the two types of simulation generally have different (sometimes conflicting) numerical requirements. To address these considerations, we have investigated variations of the two-level Newton algorithm, which preserves tight coupling between the circuit and the partial differential equations (PDE) device, while optimizing the numerics for both.

  20. Bench-level characterization of a CMOS standard-cell D-latch using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Soli, G. A.; Buehler, M. G.

    1991-01-01

    A methodology is described for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. Measurements were made on a 1.6-micron n-well CMOS 4-kb test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 micron was determined using these results and TRIM computer code. Using this collection depth and SPICE derived critical charge results on the latch design, an LET threshold of 34 MeV sq cm/mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV sq cm/mg was determined.

  1. Single event effects in static and dynamic registers in a 0.25{micro}m CMOS technology

    SciTech Connect

    Faccio, F.; Kloukinas, K.; Marchioro, A.; Calin, T.; Cosculluela, J.; Nicolaidis, M.; Velazco, R.

    1999-12-01

    The authors have studied Single Event Effects in static and dynamic registers designed in a quarter micron CMOS process. In the design, they systematically used guard rings and enclosed (edgeless) transistor geometry to improve the total dose tolerance. This design technique improved both the SEL and SEU sensitivity of the circuits. Using SPICE simulations, the measured smooth transition of the cross-section curve between LET threshold and saturation has been traced to the presence of four different upset modes, each corresponding to a different critical charge and sensitive area. A new architecture to protect the content of storage cells has been developed, and a threshold LET around 89 MeVcm{sup 2}mg{sup {minus}1} has been measured for this cell at a power supply voltage of 2 V.

  2. Single-event effects experienced by astronauts and microelectronic circuits flown in space

    SciTech Connect

    McNulty, P.J.

    1996-04-01

    Models developed for explaining the light flashes experienced by astronauts on Apollo and Skylab missions were used with slight modification to explain upsets observed in microelectronic circuits. Both phenomena can be explained by the simple assumption that an event occurs whenever a threshold number of ionizations or isomerizations are generated within a sensitive volume. Evidence is consistent with the threshold being sharp in both cases, but fluctuations in the physical stimuli lead to a gradual rather than sharp increase in cross section with LET. Successful use of the model requires knowledge of the dimensions of the sensitive volume and the value of threshold. Techniques have been developed to determine these SEU parameters in modern circuits.

  3. The two-level Newton method and its application to electronic simulation.

    SciTech Connect

    Hoekstra, Robert John; Waters, Lon J.; Rankin, Eric Lamont; Hutchinson, Scott Alan; Keiter, Eric Richard; Russo, Thomas V.

    2004-06-01

    Coupling between transient simulation codes of different fidelity can often be performed at the nonlinear solver level, if the time scales of the two codes are similar. A good example is electrical mixed-mode simulation, in which an analog circuit simulator is coupled to a PDE-based semiconductor device simulator. Semiconductor simulation problems, such as single-event upset (SEU), often require the fidelity of a mesh-based device simulator but are only meaningful when dynamically coupled with an external circuit. For such problems a mixed-level simulator is desirable, but the two types of simulation generally have different (somewhat conflicting) numerical requirements. To address these considerations, we have investigated variations of the two-level Newton algorithm, which preserves tight coupling between the circuit and the PDE device, while optimizing the numerics for both. The research was done within Xyce, a massively parallel electronic simulator under development at Sandia National Laboratories.

  4. A four-interleaving HBD SRAM cell based on dual DICE for multiple node collection mitigation

    NASA Astrophysics Data System (ADS)

    Lin, Liu; Suge, Yue; Shijin, Lu

    2015-11-01

    A 4-interleaving cell of 2-dual interlocked cells (DICE) is proposed, which reduces single event induced multiple node collection between the sensitive nodes of sensitive pairs in a DICE storage cell in 65 nm technology. The technique involves the 4-interleaving of dual DICE cells at a layout level to meet the required spacing between sensitive nodes in an area-efficient manner. Radiation experiments using a 65 nm CMOS test chip demonstrate that the LETth of our 4-interleaving cell of dual DICE encounters are almost 4× larger and the SEU cross section per bit for our proposed dual DICE design is almost two orders of magnitude less compared to the reference traditional DICE cell.

  5. An exact, closed-form expression of the integral chord-length distribution for the calculation of single-event upsets induced by cosmic rays

    NASA Technical Reports Server (NTRS)

    Luke, Keung L.; Buehler, Martin G.

    1988-01-01

    This paper presents a derivation of an exact closed-form expression of the integral chord-length distribution for the calculation of single-event upsets (SEUs) in an electronic memory cell, caused by cosmic rays. Results computed for two rectangular parallelepipeds using this exact expression are compared with those computed with Bradford's (1979) semiexact expression of C(x). It is found that the values of C(x) are identical for x equal or smaller than b but are vastly different for x greater than b. Moreover, while C(x) of Bradford gives reasonably accurate values of SEU rate for certain sets of computational parameters, it gives values more than 10 times larger than the correct values for other sets of parameters.

  6. Analysis of CRRES PHA Data for Low-Energy-Deposition Events

    NASA Technical Reports Server (NTRS)

    McNulty, P. J.; Hardage, Donna

    2004-01-01

    This effort analyzed the low-energy deposition Pulse Height Analyzer (PHA) data from the Combined Release and Radiation Effects Satellite (CRRES). The high-energy deposition data had been previously analyzed and shown to be in agreement with spallation reactions predicted by the Clemson University Proton Interactions in Devices (CUPID) simulation model and existing environmental and orbit positioning models (AP-8 with USAF B-L coordinates). The scope of this project was to develop and improve the CUPID model by increasing its range to lower incident particle energies, and to expand the modeling to include contributions from elastic interactions. Before making changes, it was necessary to identify experimental data suitable for benchmarking the codes; then, the models to the CRRES PHA data could be applied. It was also planned to test the model against available low-energy proton or neutron SEU data obtained with mono-energetic beams.

  7. Radiation Mitigation and Power Optimization Design Tools for Reconfigurable Hardware in Orbit

    NASA Technical Reports Server (NTRS)

    French, Matthew; Graham, Paul; Wirthlin, Michael; Wang, Li; Larchev, Gregory

    2005-01-01

    The Reconfigurable Hardware in Orbit (RHinO)project is focused on creating a set of design tools that facilitate and automate design techniques for reconfigurable computing in space, using SRAM-based field-programmable-gate-array (FPGA) technology. In the second year of the project, design tools that leverage an established FPGA design environment have been created to visualize and analyze an FPGA circuit for radiation weaknesses and power inefficiencies. For radiation, a single event Upset (SEU) emulator, persistence analysis tool, and a half-latch removal tool for Xilinx/Virtex-II devices have been created. Research is underway on a persistence mitigation tool and multiple bit upsets (MBU) studies. For power, synthesis level dynamic power visualization and analysis tools have been completed. Power optimization tools are under development and preliminary test results are positive.

  8. On Nibbles and Bytes: The Conundrum of Memory for Space Systems - NASA Electronic Parts and Packaging (NEPP) and Efforts in Memories

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Ladbury, Ray; Pellish, Jonathan; Sheldon, Douglas; Oldham, Timothy; Berg, Melanie D.; Cohn, Lewis M.

    2009-01-01

    Radiation requirements and trends. TID: 1) >90% of NASA applications are < 100 krads-Si in piecepart requirements. a) Many commercial devices (NVM and SDRAMs) meet or come close to this. b) Charge pump TID tolerance has improved an order magnitude over the last 10 years. 2) There are always a few programs with higher level needs and, of course, defense needs SEL: 1) Prefer none or rates that are considered low risk. a) Latent damage is a bear to deal with. 2) As we re packing cells tighter and even with lower Vdd, we re seeing SEL on commercial devices regularly (<90nm). a) Often in power conversion, I/O, or control areas. SEU: 1) It s not the bit errors, it s the SEFIs errors that are the biggest issues. a) Scrubbing concerns for risk, power, speed.

  9. The Effectiveness of TAG or Guard-Gates in SET Suppression Using Delay and Dual-Rail Configurations at 0.35 microns

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L.; Balasubramanian, Anupama; Narasimham, Balaji; Bhuva, Bharat; O'Neill, Patrick M.; Kouba, Coy

    2006-01-01

    Design options for decreasing the susceptibility of integrated circuits to Single Event Upset (SEU) fall into two categories: (1) increasing the critical charge to cause an upset at a particular node, and (2) employing redundancy to mask or correct errors. With decreasing device sizes on an Integrated Circuit (IC), the amount of charge required to represent a logic state has steadily reduced. Critical charge methods such as increasing drive strength or increasing the time required to change state as in capacitive or resistive hardening or delay based approaches extract a steadily increasing penalty as a percentage of device resources and performance. Dual redundancy is commonly assumed only to provide error detection with Triple Modular Redundancy (TMR) required for correction, but less well known methods employ dual redundancy to achieve full error correction by voting two inputs with a prior state to resolve ambiguity. This requires special circuits such as the Whitaker latch [1], or the guard-gate [2] which some of us have called a Transition AND Gate (TAG) [3]. A 2-input guard gate is shown in Figure 1. It is similar to a Muller Completion Element [4] and relies on capacitance at node "out" to retain the prior state when inputs disagree, while eliminating any output buffer which would be susceptible to radiation strikes. This paper experimentally compares delay based and dual rail flip-flop designs wherein both types of circuits employ guard-gates to optimize layout and performance, and draws conclusions about design criteria and suitability of each option. In both cases a design goal is protection against Single Event Transients (SET) in combinational logic as well as SEU in the storage elements. For the delay based design, it is also a goal to allow asynchronous clear or preset inputs on the storage elements, which are often not available in radiation tolerant designs.

  10. [Determination of the contents of trace elements in chinese herbal medicines for treating respiratory system diseases].

    PubMed

    Han, Li-Qin; Dong, Shun-Fu; Liu, Jian-Hua

    2008-02-01

    There is an intimate connection between trace elements and body healthiness, trace elements and organism depend on each other, and each trace element exists with certain proportion, which preserve physio-function. If the balance is of maladjustment, diseases may occur or develop. The trace elements were determined in 16 kinds of Chinese herbal medicines by atomic absorption spectrometry. The medicines include lilium brownii, herba houttuyniae, licorice root, radices isatidis seu baphicacanthi, Sehizandra sinensis Bail, Scutellaria baicalensis Georgi, Beimu, Polygonum multiflorum Thunb, Lithospermum officinalel, Rhizoma acori gramjnoi, Pinellia ternate Breit, Salisburia adiantifolia, Lonicera japonica, Radices puerarire, Bupleurum falcatum and Ligusticum wallichii, all of which could be bought on the market. Sixteen kinds of Chinese herbal medicines commonly used to treat respiratroy system diseases in clinic were selected, dried and powdered, completely mixed, 1.000 0 g was weighed accurately with analytical balance, and 3 portions were used for each kind of sample. The atomic absorption spectrometry was used to determine the contents of trace elements (Cu, Zn, Fe, Cr, Ni and Mn), and the content discrepancy of the trace elements in different medicines was observed the results shows that the contents of the trace elements were rich in the 16 kinds of Chinese herbal medicines, there were more contents of Fe, Zn and Mn, but they were different in different medicines. And there were more trace elements in Salisburia adiantifolia, Polygonum multiflorum Thunb, Bupleurum falcatum, Sehizandra sinensis Bail, Pinellia ternate Breit and Lithospermum officinalel, and lower trace elements in Radices puerarire, Rhizoma acori gramjnoi and Radices isatidis seu baphicacanthi. The analytic results provided useful data for using Chinese herbal medicines and provided theoretical basis for studying Chinese herbal medicines theory. PMID:18479045

  11. A novel orange-red phosphor Ca3B2O6:Sm3+, A+(A = Li, Na, K) for white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Liu, Qingbo; Liu, Yufeng; Yang, Fu; Han, Bing; Feng, Hao; Yu, Quanmao

    2014-03-01

    A novel orange-red phosphor Ca3B2O6:Sm3+, A+(A = Li, Na, K) has been synthesized by solid-state reaction at 950°C. The phase purity and photoluminescence (PL) behavior of the phosphor are studied in detail using the powder X-ray diffraction (XRD) technique and PL measurements. Ca3B2O6:Sm3+ phosphor can be efficiently excited by near ultraviolet (n-UV) and blue light, and the emission spectrum consists of four emission peaks at 563, 599, 646 and 709 nm, generating bright orange-red light. When a cation A+ is introduced into Ca3B2O6:Sm3+ as charge compensator, the emission intensity of Ca3B2O6:Sm3+ is evidently enhanced, but the PL spectral profile is unchanged. The integral intensity of the emission spectrum of Ca2.96Sm0.02Na0.02B2O6 excited at 401 nm is about 1.2 times than that of Y2O2S:Eu3+ commercial red phosphor. The CIE chromaticity coordinates of Ca2.96Sm0.02Na0.02B2O6 phosphor were (0.608, 0.365), which are close to that of the commercial red phosphors Y2O3:Eu3+ (0.655, 0.345), Y2O2S:Eu3+ (0.622, 0.351) and Sr2Si5N8:Eu2+ (0.620, 0.370).

  12. Prediction of DNA-binding residues in proteins from amino acid sequences using a random forest model with a hybrid feature

    PubMed Central

    Wu, Jiansheng; Liu, Hongde; Duan, Xueye; Ding, Yan; Wu, Hongtao; Bai, Yunfei; Sun, Xiao

    2009-01-01

    Motivation: In this work, we aim to develop a computational approach for predicting DNA-binding sites in proteins from amino acid sequences. To avoid overfitting with this method, all available DNA-binding proteins from the Protein Data Bank (PDB) are used to construct the models. The random forest (RF) algorithm is used because it is fast and has robust performance for different parameter values. A novel hybrid feature is presented which incorporates evolutionary information of the amino acid sequence, secondary structure (SS) information and orthogonal binary vector (OBV) information which reflects the characteristics of 20 kinds of amino acids for two physical–chemical properties (dipoles and volumes of the side chains). The numbers of binding and non-binding residues in proteins are highly unbalanced, so a novel scheme is proposed to deal with the problem of imbalanced datasets by downsizing the majority class. Results: The results show that the RF model achieves 91.41% overall accuracy with Matthew's correlation coefficient of 0.70 and an area under the receiver operating characteristic curve (AUC) of 0.913. To our knowledge, the RF method using the hybrid feature is currently the computationally optimal approach for predicting DNA-binding sites in proteins from amino acid sequences without using three-dimensional (3D) structural information. We have demonstrated that the prediction results are useful for understanding protein–DNA interactions. Availability: DBindR web server implementation is freely available at http://www.cbi.seu.edu.cn/DBindR/DBindR.htm. Contact: xsun@seu.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online. PMID:19008251

  13. Early geomorphological evolution of the North Polar Layered Deposits, Mars, from SHARAD radar-facies mapping

    NASA Astrophysics Data System (ADS)

    Nerozzi, Stefano; Holt, John W.

    2014-05-01

    The north polar layered deposits (NPLD) are the largest accumulation of water ice in the northern hemisphere of Mars. Since their discovery, they are thought to hold a valuable record of recent climate change within their stratigraphy (Murray et al., Icarus, 1972; Cutts, JGR, 1973b), yet little is known about their age and accumulation history. Due to exposures in trough walls, detailed stratigraphy of the uppermost layers and their evolution have been studied extensively since the first Mariner 9 images of the NPLD (e.g. Soderblom et al., JGR, 1973). However, large portions of the polar cap are still unmapped and no detailed studies of the lowermost layered deposits have been performed to date, primarily due to a general lack of visible exposures. Correlation of reflectors within radargrams acquired by the Shallow Radar (SHARAD) (Seu et al., Planet. Space Sci., 2004) onboard Mars Reconnaissance Orbiter makes a detailed stratigraphic reconstruction of the NPLD possible. An extensive set of radargrams is available over Planum Boreum and individual reflectors can be traced over hundreds of kilometers (Seu et al., JGR, 2007a; Putzig et al., Icarus, 2009; Holt et al., Nature, 2010) with a theoretical vertical resolution of ~9 m in water ice (Seu et al., JGR, 2007a). In this study, we present a highly-detailed stratigraphic reconstruction of the first ~500 m of the NPLD at a scale down to the single reflector. A set of 8 horizons was tracked across 700+ radargrams, and thicknesses were calculated for each stratigraphic interval assuming a bulk composition of water ice. Along with the quantitative analysis of derived isopach maps, this study is based on the qualitative comparison of "radar facies" in different locations of Planum Boreum with techniques borrowed from traditional sequence stratigraphy. In general, the NPLD is characterized by uniform layering. However, important layer extent and thickness variations are observed within the lowermost sequence. Limited

  14. Study on Radiation Condition in DAMPE Orbit by Analyzing the Engineering Data of BGO Calorimeter

    NASA Astrophysics Data System (ADS)

    Feng, Changqing; Liu, Shubin; Zhang, Yunlong; Ma, Siyuan

    2016-07-01

    The DAMPE (DArk Matter Particle Explorer) is a scientific satellite which was successfully launched into a 500 Km sun-synchronous orbit, on December 17th, 2015, from the Jiuquan Satellite Launch Center of China. The major scientific objectives of the DAMPE mission are primary cosmic ray, gamma ray astronomy and dark matter particles, by observing high energy primary cosmic rays, especially positrons/electrons and gamma rays with an energy range from 5 GeV to 10 TeV. The BGO calorimeter is a critical sub-detector of DAMPE payload, for measuring the energy of cosmic particles, distinguishing positrons/electrons and gamma rays from hadron background, and providing trigger information. It utilizes 308 BGO (Bismuth Germanate Oxide) crystal logs with the size of 2.5cm*2.5cm*60cm for each log, to form a total absorption electromagnetic calorimeter. All the BGO logs are stacked in 14 layers, with each layer consisting of 22 BGO crystal logs and each log is viewed by two Hamamatsu R5610A PMTs (photomultiplier tubes), from both sides respectively. In order to achieve a large dynamic range, each PMT base incorporates a three dynode (2, 5, 8) pick off, which results in 616 PMTs and 1848 signal channels. The readout electronics system, which consists of 16 FEE (Front End Electronics) modules, was developed. Its main functions are based on the Flash-based FPGA (Field Programmable Gate Array) chip and low power, 32-channel VA160 and VATA160 ASICs (Application Specific Integrated Circuits) for precisely measuring the charge of PMT signals and providing "hit" signals as well. The hit signals are sent to the trigger module of PDPU (Payload Data Process Unit) and the hit rates of each layer is real-timely recorded by counters and packed into the engineering data, which directly reflect the flux of particles which fly into or pass through the detectors. In order to mitigate the SEU (Single Event Upset) effect in radioactive space environment, certain protecting methods, such as TMR

  15. New On-board Microprocessors

    NASA Astrophysics Data System (ADS)

    Weigand, R.

    Two new processor devices have been developed for the use on board of spacecrafts. An 8-bit 8032-microcontroller targets typical controlling applications in instruments and sub-systems, or could be used as a main processor on small satellites, whereas the LEON 32-bit SPARC processor can be used for high performance controlling and data processing tasks. The ADV80S32 is fully compliant to the Intel 80x1 architecture and instruction set, extended by additional peripherals, 512 bytes on-chip RAM and a bootstrap PROM, which allows downloading the application software using the CCSDS PacketWire pro- tocol. The memory controller provides a de-multiplexed address/data bus, and allows to access up to 16 MB data and 8 MB program RAM. The peripherals have been de- signed for the specific needs of a spacecraft, such as serial interfaces compatible to RS232, PacketWire and TTC-B-01, counters/timers for extended duration and a CRC calculation unit accelerating the CCSDS TM/TC protocol. The 0.5 um Atmel manu- facturing technology (MG2RT) provides latch-up and total dose immunity; SEU fault immunity is implemented by using SEU hardened Flip-Flops and EDAC protection of internal and external memories. The maximum clock frequency of 20 MHz allows a processing power of 3 MIPS. Engineering samples are available. For SW develop- ment, various SW packages for the 8051 architecture are on the market. The LEON processor implements a 32-bit SPARC V8 architecture, including all the multiply and divide instructions, complemented by a floating-point unit (FPU). It includes several standard peripherals, such as timers/watchdog, interrupt controller, UARTs, parallel I/Os and a memory controller, allowing to use 8, 16 and 32 bit PROM, SRAM or memory mapped I/O. With on-chip separate instruction and data caches, almost one instruction per clock cycle can be reached in some applications. A 33-MHz 32-bit PCI master/target interface and a PCI arbiter allow operating the device in a plug-in card

  16. Cosmic Journeys. To the Edge of Gravity, Space and Time: Structure and Evolution of the Universe Roadmap: 2003-2023

    NASA Astrophysics Data System (ADS)

    1999-09-01

    The Roadmap for the Structure and Evolution of the Universe (SEU) Theme embraces three fundamental, scientific quests: (1) To explain structure in the Universe and forecast our cosmic destiny, (2) To explore the cycles of matter and energy in the evolving Universe, (3) To examine the ultimate limits of gravity and energy in the Universe. We develop these quests into six focused research campaigns: (1) Identify dark matter and learn how it shapes galaxies and systems of galaxies, (2) Explore where and when the chemical elements were made (3) Understand the cycles in which matter, energy, and magnetic field are exchanged between stars and the gas between stars, (4) Discover how gas flows in disks and how cosmic jets are formed, (5) Identify the sources of gamma-ray bursts and high-energy cosmic rays, (6) Measure how strong gravity operates near black holes and how it affects the early Universe. These campaigns lead to a portfolio of future major missions of great scientific interest and popular appeal, strongly endorsed by the scientific community. Many have undergone significant initial study. Some are in a state of readiness that make them ideal candidates for the present Office of Space Science Strategic Plan; others may well feature in the next Plan. Each provides a golden scientific opportunity to advance our understanding of the Universe. We have identified three top-priority near-term science objectives together with missions to accomplish these goals. The three problems span a diverse range of subdisciplines, of observational technique, of timescales, and of cost, and are thus complementary, forming a coherent core program for the SEU theme in the 2003-2007 timeframe.These are : (1) Obtain precise measures of the chemical composition and physical conditions in objects ranging from the closest stars to the most distant quasars, (2) Utilize gravitational radiation as a probe of supermassive blackholes throughout the universe, (3) determine the nature of the

  17. Investigation of HZETRN 2010 as a Tool for Single Event Effect Qualification of Avionics Systems

    NASA Technical Reports Server (NTRS)

    Rojdev, Kristina; Atwell, William; Boeder, Paul; Koontz, Steve

    2014-01-01

    NASA's future missions are focused on deep space for human exploration that do not provide a simple emergency return to Earth. In addition, the deep space environment contains a constant background Galactic Cosmic Ray (GCR) radiation exposure, as well as periodic Solar Particle Events (SPEs) that can produce intense amounts of radiation in a short amount of time. Given these conditions, it is important that the avionics systems for deep space human missions are not susceptible to Single Event Effects (SEE) that can occur from radiation interactions with electronic components. The typical process to minimizing SEE effects is through using heritage hardware and extensive testing programs that are very costly. Previous work by Koontz, et al. [1] utilized an analysis-based method for investigating electronic component susceptibility. In their paper, FLUKA, a Monte Carlo transport code, was used to calculate SEE and single event upset (SEU) rates. This code was then validated against in-flight data. In addition, CREME-96, a deterministic code, was also compared with FLUKA and in-flight data. However, FLUKA has a long run-time (on the order of days), and CREME-96 has not been updated in several years. This paper will investigate the use of HZETRN 2010, a deterministic transport code developed at NASA Langley Research Center, as another tool that can be used to analyze SEE and SEU rates. The benefits to using HZETRN over FLUKA and CREME-96 are that it has a very fast run time (on the order of minutes) and has been shown to be of similar accuracy as other deterministic and Monte Carlo codes when considering dose [2, 3, 4]. The 2010 version of HZETRN has updated its treatment of secondary neutrons and thus has improved its accuracy over previous versions. In this paper, the Linear Energy Transfer (LET) spectra are of interest rather than the total ionizing dose. Therefore, the LET spectra output from HZETRN 2010 will be compared with the FLUKA and in-flight data to validate

  18. An occupational health programme for adults and children in the carpet weaving industry, Mirzapur, India: a case study in the informal sector.

    PubMed

    Das, P K; Shukla, K P; Ory, F G

    1992-11-01

    The Indo-Dutch Environmental and Sanitary Engineering Project under Ganga action Plan in Kanpur and Mirzapur is being executed within the framework of Indo-Dutch bilateral development cooperation. The project aims to integrate technological, social and health related improvements. It is expected that the development approach and methodology can be replicated in other urban settlements in India. The project is being supplemented by a training and institutional strengthening programme, which will facilitate the transfer of new technologies and improvements in operation and maintenance of these new technologies. One of the project's goals is to improve living conditions in the targeted areas by installing drinking water and drainage systems. A socio-economic unit (SEU) in the project supports these technical interventions by encouraging the community to participate in project activities. The Occupational Health Programme in Mirzapur was conceived by the SEU to improve the health and living conditions of child and adult weavers. At the start of the programme, 200 weavers and 60 non-weaver workers from Mirzapur city, matched for age and socio-economic status, were interviewed and underwent a physical examination. The mean age of the weavers is 27 years, reflecting the relatively large percentage of child labour (13.5%). Illiteracy among them is 73%, whereas 14% have had only a primary education. 64.5% of the carpet weavers are Muslims and 35.6% are Hindus. 61% own a loom or work in a family owned loom shed. 95% of the weavers have a monthly income of less than 600 Rs. Complaints of a persistent cough and cough with expectoration, backache, the common cold and joint pains occurred more often in the weaver population than in the comparison group and have been identified as 'occupational hazards'. An intervention programme has been implemented based on the results of the occupational health survey. These interventions include awareness camps, installment of plexiglass

  19. Cosmic Journeys. To the Edge of Gravity, Space and Time: Structure and Evolution of the Universe Roadmap: 2003-2023

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The Roadmap for the Structure and Evolution of the Universe (SEU) Theme embraces three fundamental, scientific quests: (1) To explain structure in the Universe and forecast our cosmic destiny, (2) To explore the cycles of matter and energy in the evolving Universe, (3) To examine the ultimate limits of gravity and energy in the Universe. We develop these quests into six focused research campaigns: (1) Identify dark matter and learn how it shapes galaxies and systems of galaxies, (2) Explore where and when the chemical elements were made (3) Understand the cycles in which matter, energy, and magnetic field are exchanged between stars and the gas between stars, (4) Discover how gas flows in disks and how cosmic jets are formed, (5) Identify the sources of gamma-ray bursts and high-energy cosmic rays, (6) Measure how strong gravity operates near black holes and how it affects the early Universe. These campaigns lead to a portfolio of future major missions of great scientific interest and popular appeal, strongly endorsed by the scientific community. Many have undergone significant initial study. Some are in a state of readiness that make them ideal candidates for the present Office of Space Science Strategic Plan; others may well feature in the next Plan. Each provides a golden scientific opportunity to advance our understanding of the Universe. We have identified three top-priority near-term science objectives together with missions to accomplish these goals. The three problems span a diverse range of subdisciplines, of observational technique, of timescales, and of cost, and are thus complementary, forming a coherent core program for the SEU theme in the 2003-2007 timeframe.These are : (1) Obtain precise measures of the chemical composition and physical conditions in objects ranging from the closest stars to the most distant quasars, (2) Utilize gravitational radiation as a probe of supermassive blackholes throughout the universe, (3) determine the nature of the

  20. Sobre a largura da última superfície de espalhamento

    NASA Astrophysics Data System (ADS)

    Nobre, M. A. S.; Pires, N.; Lima, J. A. S.

    2003-08-01

    De acordo com o modelo do "Big-Bang", no universo primordial a matéria estava em equilíbrio térmico com a radiação. Com a expansão a temperatura da radiação cai. Quando a temperatura chega em torno dos 4.000K, os espalhamentos diminuem, começando a recombinação dos prótons e elétrons em Hidrogênio neutro (era conhecida como da recombinação). Ao final da recombinação, os fótons se propagam livremente sofrendo, em princípio, somente os efeitos do "redshift" cosmológico. Esses fótons nos alcançam hoje como a radiação cósmica de fundo (RCF), e parecem vir de uma superfície esférica ao nosso redor, tal que o raio dela é a distância que ele viajou desde seu último espalhamento na época da recombinação. Naturalmente, esse processo não ocorreu abruptamente, implicando na existência de uma largura no espaço dos "redshifts" que deve depender do modelo cosmológico específico e dos processos físicos considerados. Neste trabalho analisamos os efeitos de diferentes modelos - a saber, aqueles com decaimento do vácuo L(t), criação de matéria, quintessência e gás de Chaplygin - sobre a última superfície de espalhamento da RCF, em particular sua largura e a função visibilidade, que determina a probabilidade de um fóton ter tido seu último espalhamento num "redshift" z. No caso particular dos modelos com decaimento do vácuo, existe uma forte dependência da função visibilidade com L(t). Tais efeitos poderão ser testados através da análise dos resultados de experimentos mais precisos que estão atualmente em andamento, como por exemplo, o WMAP.

  1. Cadmium(II) complex formation with selenourea and thiourea in solution: an XAS and 113Cd NMR study.

    PubMed

    Jalilehvand, Farideh; Amini, Zahra; Parmar, Karnjit

    2012-10-15

    The complexes formed in methanol solutions of Cd(CF(3)SO(3))(2) with selenourea (SeU) or thiourea (TU), for thiourea also in aqueous solution, were studied by combining (113)Cd NMR and X-ray absorption spectroscopy. At low temperature (~200 K), distinct (113)Cd NMR signals were observed, corresponding to CdL(n)(2+) species (n = 0-4, L = TU or SeU) in slow ligand exchange. Peak integrals were used to obtain the speciation in the methanol solutions, allowing stability constants to be estimated. For cadmium(II) complexes with thione (C═S) or selone (C═Se) groups coordinated in Cd(S/Se)O(5) or Cd(S/Se)(2)O(4) (O from MeOH or CF(3)SO(3)(-)) environments, the (113)Cd chemical shifts were quite similar, within 93-97 ppm and 189-193 ppm, respectively. However, the difference in the chemical shift for the Cd(SeU)(4)(2+) (578 pm) and Cd(TU)(4)(2+) (526 ppm) species, with CdSe(4) and CdS(4) coordination, respectively, shows less chemical shielding for the coordinated Se atoms than for S, in contrast to the common trend with increasing shielding in the following order: O > N > Se > S. In solutions dominated by mono- and tetra-thiourea/selenourea complexes, their coordination and bond distances could be evaluated by Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. At ~200 K and high excess of thiourea, a minor amount (up to ~30%) of [Cd(TU)(5-6)](2+) species was detected by an upfield shift of the (113)Cd NMR signal (up to 423 ppm) and an amplitude reduction of the EXAFS oscillation. The amount was estimated by fitting linear combinations of simulated EXAFS spectra for [Cd(TU)(4)](2+) and [Cd(TU)(6)](2+) complexes. At room temperature, [Cd(TU)(4)](2+) was the highest complex formed, also in aqueous solution. Cd L(3)-edge X-ray absorption near edge structure (XANES) spectra of cadmium(II) thiourea solutions in methanol were used to follow changes in the CdS(x)O(y) coordination. The correlations found from the current and previous studies between (113

  2. Otimização de procedimento de manobra para indução de reentrada de um satélite retornável

    NASA Astrophysics Data System (ADS)

    Schulz, W.; Suarez, M.

    2003-08-01

    Veículos espaciais que retornam à Terra passam por regimes de velocidade e condições de vôo distintos. Estas diferenças dificultam sua concepção aerodinâmica e o planejamento de seu retorno. A partir de uma proposta de um veículo orbital retornável (satélite SARA, em desenvolvimento no IAE/CTA) para realização de experimentos científicos e tecnológicos em ambiente de baixa gravidade, surge a necessidade de realizarem-se estudos considerando-se os aspectos relativos à sua aerodinâmica. Após o lançamento, o veículo deve permanecer em órbita pelo tempo necessário para a condução de experimentos, sendo depois direcionado à Terra e recuperado em solo. A concepção aerodinâmica é de importância para o vôo em suas diversas fases e deve considerar aspectos relativos à estabilização Aerodinâmica e ao arrasto atmosférico, sendo este último de importância crucial na análise do aquecimento a ser enfrentado. A manobra de retorno inclui considerações sobre as condições atmosféricas e dinâmica de reentrada, devendo ser calculada de forma mais precisa possível. O trabalho proposto avalia estudos da dinâmica de vôo de um satélite recuperável considerando aspectos relativos à determinação orbital com GPS, técnica utilizada com sucesso na CONAE, e seu comportamento aerodinâmico em vôo balístico de retorno, com ênfase em sua fase de reentrada atmosférica. Busca-se otimizar a manobra de reentrada de tal forma que a utilização do sistema GPS garanta minimizar a área de impacto com o solo.

  3. Fault-Tolerant, Radiation-Hard DSP

    NASA Technical Reports Server (NTRS)

    Czajkowski, David

    2011-01-01

    Commercial digital signal processors (DSPs) for use in high-speed satellite computers are challenged by the damaging effects of space radiation, mainly single event upsets (SEUs) and single event functional interrupts (SEFIs). Innovations have been developed for mitigating the effects of SEUs and SEFIs, enabling the use of very-highspeed commercial DSPs with improved SEU tolerances. Time-triple modular redundancy (TTMR) is a method of applying traditional triple modular redundancy on a single processor, exploiting the VLIW (very long instruction word) class of parallel processors. TTMR improves SEU rates substantially. SEFIs are solved by a SEFI-hardened core circuit, external to the microprocessor. It monitors the health of the processor, and if a SEFI occurs, forces the processor to return to performance through a series of escalating events. TTMR and hardened-core solutions were developed for both DSPs and reconfigurable field-programmable gate arrays (FPGAs). This includes advancement of TTMR algorithms for DSPs and reconfigurable FPGAs, plus a rad-hard, hardened-core integrated circuit that services both the DSP and FPGA. Additionally, a combined DSP and FPGA board architecture was fully developed into a rad-hard engineering product. This technology enables use of commercial off-the-shelf (COTS) DSPs in computers for satellite and other space applications, allowing rapid deployment at a much lower cost. Traditional rad-hard space computers are very expensive and typically have long lead times. These computers are either based on traditional rad-hard processors, which have extremely low computational performance, or triple modular redundant (TMR) FPGA arrays, which suffer from power and complexity issues. Even more frustrating is that the TMR arrays of FPGAs require a fixed, external rad-hard voting element, thereby causing them to lose much of their reconfiguration capability and in some cases significant speed reduction. The benefits of COTS high

  4. The Teaching of Astronomy in Uruguay. (Spanish Title: La Enseñanza de la Astronomía en Uruguay.) O Ensino da Astronomia no Uruguai

    NASA Astrophysics Data System (ADS)

    Pintos Ganón, Reina; Fernández, Julio Angel

    2008-07-01

    We present in this work the development of astronomy in Uruguay since the colony times up to the present, stressing in particular those aspects related to the formal as well as informal teaching of astronomy. The first antecedents of astronomical studies in our country go back to the beginnings of the XVIIIth century related to the scientific expeditions from Europe coming to our shores. The teaching of astronomy was generalized at the high school level as soon as the end of the XIXth century, while itsintroduction at the university level happened much later, around the middle of the last century. We analyze the current situation of this subject, its problems, and some measures to strengthen its development. Se presenta en este trabajo el desarrollo de la astronomía en el Uruguay desde la época colonial hasta el presente, destacando en particular los aspectos vinculados a su enseñanza tanto formal como informal. Los primeros antecedentes de estudios astronómicos datan de la época colonial relacionados con las expediciones científicas del Viejo Mundo que llegaban a nuestras costas. La enseñanza de la Astronomía se generalizó en el ámbito de los estudios secundarios ya a fines del siglo XIX, mientras que en la Universidad su arribo fue mucho más tardío, a mediados del siglo pasado. Se analiza la situación actual de esta disciplina, sus problemas, y algunas medidas para fortalecer su desarrollo. Apresentamos, neste trabalho, o desenvolvimento da Astronomia no Uruguai desde a época colonial até o presente, destacando em particular os aspectos vinculados ao seu ensino tanto formal quanto informal. Os primeiros antecedentes de estudos astronômicos em nosso país datam da época colonial relacionados com as expedições científicas do Velho Mundo que chegavam às nossas costas. O ensino da Astronomia se generalizou no âmbito dos estudos secundários já no final do século XIX, enquanto que sua introdução na universidade foi muito mais tardia, em

  5. The Single Event Effect Characteristics of the 486-DX4 Microprocessor

    NASA Technical Reports Server (NTRS)

    Kouba, Coy; Choi, Gwan

    1996-01-01

    This research describes the development of an experimental radiation testing environment to investigate the single event effect (SEE) susceptibility of the 486-DX4 microprocessor. SEE effects are caused by radiation particles that disrupt the logic state of an operating semiconductor, and include single event upsets (SEU) and single event latchup (SEL). The relevance of this work can be applied directly to digital devices that are used in spaceflight computer systems. The 486-DX4 is a powerful commercial microprocessor that is currently under consideration for use in several spaceflight systems. As part of its selection process, it must be rigorously tested to determine its overall reliability in the space environment, including its radiation susceptibility. The goal of this research is to experimentally test and characterize the single event effects of the 486-DX4 microprocessor using a cyclotron facility as the fault-injection source. The test philosophy is to focus on the "operational susceptibility," by executing real software and monitoring for errors while the device is under irradiation. This research encompasses both experimental and analytical techniques, and yields a characterization of the 486-DX4's behavior for different operating modes. Additionally, the test methodology can accommodate a wide range of digital devices, such as microprocessors, microcontrollers, ASICS, and memory modules, for future testing. The goals were achieved by testing with three heavy-ion species to provide different linear energy transfer rates, and a total of six microprocessor parts were tested from two different vendors. A consistent set of error modes were identified that indicate the manner in which the errors were detected in the processor. The upset cross-section curves were calculated for each error mode, and the SEU threshold and saturation levels were identified for each processor. Results show a distinct difference in the upset rate for different configurations of

  6. Cadmium(II) Complex Formation with Selenourea and Thiourea in Solution: An XAS and 113Cd NMR Study

    PubMed Central

    Jalilehvand, Farideh; Amini, Zahra; Parmar, Karnjit

    2012-01-01

    The complexes formed in methanol solutions of Cd(CF3SO3)2 with selenourea (SeU) or thiourea (TU), for thiourea also in aqueous solution, were studied by combining 113Cd NMR and X-ray absorption spectroscopy. At low temperature (~200 K) distinct 113Cd NMR signals were observed, corresponding to CdLn2+ species (n = 0 - 4, L = TU or SeU) in slow ligand exchange. Peak integrals were used to obtain the speciation in the methanol solutions, allowing stability constants to be estimated. For cadmium(II) complexes with thione (C=S) or selone (C=Se) groups coordinated in Cd(S/Se)O5 or Cd(S/Se)2O4 (O from MeOH or CF3SO3-) environments the 113Cd chemical shifts were quite similar, within 93-97 ppm and 189 – 193 ppm, respectively. However, the difference in the chemical shift for the Cd(SeU)42+ (578 pm) and Cd(TU)42+ (526 ppm) species, with CdSe4 and CdS4 coordination, respectively, shows less chemical shielding for the coordinated Se atoms than for S, in contrast to the common trend with increasing shielding in the order: O > N > Se >S. In solutions dominated by mono- and tetra-thiourea / selenourea complexes, their coordination and bond distances could be evaluated by Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. At ~200 K and high excess of thiourea a minor amount (up to ~30%) of [Cd(TU)5-6]2+ species was detected by an upfield shift of the 113Cd NMR signal (up to 423 ppm) and an amplitude reduction of the EXAFS oscillation. The amount was estimated by fitting linear combinations of simulated EXAFS spectra for [Cd(TU)4]2+ and [Cd(TU)6]2+ complexes. At room temperature, [Cd(TU)4]2+ was the highest complex formed, also in aqueous solution. Cd L3-edge X-ray absorption near edge structure (XANES) spectra of cadmium(II) thiourea solutions in methanol were used to follow changes in the CdSxOy coordination at room temperature. The correlations found from the current and previous studies between 113Cd NMR chemical shifts and different Cd(II) coordination

  7. The Appearance of the Medicean Moons in 17th Century Charts and Books—How Long Did It Take?

    NASA Astrophysics Data System (ADS)

    Mendillo, Michael

    2010-01-01

    Galileo's talents in perspective and chiaroscuro drawing led to his images of the Moon being accepted relatively quickly as the naturalistic portrayal of a truly physical place. In contrast to his resolved views of the Moon, Galileo saw the satellites of Jupiter as only points of light (as with stars). He thus used star symbols in Sidereus Nuncius (1610) for the moons, in constrast to an open disk for Jupiter. In this paper, I describe methods used in subsequent decades to portray objects that could not be seen in any detail but whose very existence challenged the scholastic approach to science. Within fifty years, the existence of the moons was such an accepted component of astronomy that they were depicted in the highly decorative “textbook” Atlas Coelestis seu Harmonia Macrocosmica by Andreas Cellarius (1660). Other symbolic methods, ranging from the routine to the dramatic, were used in subsequent centuries to portray the moons. Actual photographs using ground-based telescopes were not possible until the 20th century, just years before cameras on spaceflight missions captured the true details of the Medicean Stars.

  8. Radiative transfer in layered media: Application to the radar sounding of Martian polar ices. II

    NASA Astrophysics Data System (ADS)

    Ilyushin, Ya. A.

    2007-01-01

    The paper addresses the problem of the retrieval of the physical parameters of the Martian polar ices from the ground-penetrating radar (GPR) measurements. The results of the previous paper [Ilyushin, Y.A., Seu, R., Phillips, R.J., 2005. Subsurface radar sounding of the Martian polar cap: radiative transfer approach. Planet. Space Sci. 53(14-15), 1427-1436, doi: 10.1016/j.pss.2005.08.002] are further developed. Several electrical models of the Martian polar caps are considered, and several radiative transfer models, appropriate for layered media, are reviewed and compared to each other. Both 1D case, applicable to the orbital GPR instruments, and 2D and 3D geometry, applicable to the landed radars, are studied. A technique for retrieval of the average loss in the medium, which can be attributed to the impurities content in the ice, is proposed. The retrieval technique is numerically tested with the exact solutions of electromagnetic equations for the waves in the layered media. Numerical tests show that the loss in the medium can be determined from the observed radar signal in the whole range of values, expected to be the case in Martian polar caps.

  9. Radio wave propagation in the Martian polar deposits: models and implications for radar sounding.

    NASA Astrophysics Data System (ADS)

    Ilyushin, Ya. A.

    In the present study the propagation of electromagnetic waves in the northern polar ice sheet of Mars is considered Several different scenarios of the structure of the polar deposits and composition of the ice compatible with previously published observational data are proposed Both analytical and numerical simulations of ultra wide band chirp radar pulse propagating through the cap are performed Approximate approach based on the non-coherent theory of the radiative transfer in layered media has been applied to the problem of the propagation of radar pulses in the polar caps Both 1D and 2D and 3D geometry applicable to the orbital and landed radar instruments are studied The side clutter and phase distortions of the signal are also addressed analyzed The possibilities of retrieval of the geological information depending on transparency of the polar cap for radio waves are discussed If the polar cap is relatively transparent the echo from the base of the sheet should be clearly distinctive and interpretable in terms of basal topography of the cap In the case of moderate optical thickness coherent basal echo is corrupted by strong multiple scattering in the layered structure However some conclusions about basal conditions could be made from the signals for example the subglacial lakes may be detected Finally optically thick polar caps prevent any sounding of the base so only the medium itself can be characterized by GPR measurements e g the impurity content in the ice can be found Ilyushin Y A R Seu

  10. LET spectra measurements of charged particles in the P0006 experiment on LDEF

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Csige, I.; Oda, K.; Henke, R. P.; Frank, A. L.; Benton, E. R.; Frigo, L. A.; Parnell, T. A.; Watts, J. W., Jr.; Derrickson, J. H.

    1993-01-01

    Measurements are under way of the charged particle radiation environment of the Long Duration Exposure Facility (LDEF) satellite using stacks of plastic nuclear track detectors (PNTD's) placed in different locations of the satellite. In the initial work the charge, energy, and linear energy transfer (LET) spectra of charged particles were measured with CR-39 double layer PNTD's located on the west side of the satellite (Experiment P0006). Primary and secondary stopping heavy ions were measured separately from the more energetic particles. Both trapped and galactic cosmic ray (GCR) particles are included, with the latter component being dominated by relativistic iron particles. The results from the P0006 experiment will be compared with similar measurements in other locations on LDEF with different orientation and shielding conditions. The remarkably detailed investigation of the charged particle radiation environment of the LDEF satellite will lead to a better understanding of the radiation environment of the Space Station Freedom. It will enable more accurate prediction of single event upsets (SEU's) in microelectronics and, especially, more accurate assessment of the risk - contributed by different components of the radiation field (GCR's, trapped protons, secondaries and heavy recoils, etc.) - to the health and safety of crew members.

  11. REE radiation fault model: a tool for organizing and communication radiation test data and construction COTS based spacebourne computing systems

    NASA Technical Reports Server (NTRS)

    Ferraro, R.; Some, R.

    2002-01-01

    The growth in data rates of instruments on future NASA spacecraft continues to outstrip the improvement in communications bandwidth and processing capabilities of radiation-hardened computers. Sophisticated autonomous operations strategies will further increase the processing workload. Given the reductions in spacecraft size and available power, standard radiation hardened computing systems alone will not be able to address the requirements of future missions. The REE project was intended to overcome this obstacle by developing a COTS- based supercomputer suitable for use as a science and autonomy data processor in most space environments. This development required a detailed knowledge of system behavior in the presence of Single Event Effect (SEE) induced faults so that mitigation strategies could be designed to recover system level reliability while maintaining the COTS throughput advantage. The REE project has developed a suite of tools and a methodology for predicting SEU induced transient fault rates in a range of natural space environments from ground-based radiation testing of component parts. In this paper we provide an overview of this methodology and tool set with a concentration on the radiation fault model and its use in the REE system development methodology. Using test data reported elsewhere in this and other conferences, we predict upset rates for a particular COTS single board computer configuration in several space environments.

  12. Antiferromagnetic Interlayer Exchange Coupling in All-Semiconducting EuS/PbS/EuS Trilayers

    NASA Technical Reports Server (NTRS)

    Smits, C. J. P.; Filip, A. T.; Swagten, H. J. M.; Koopmans, B.; deJonge, W. J. M.; Chernyshova, M.; Kowalczyk, L.; Grasza, K.; Szczerbakow, A.; Story, T.

    2003-01-01

    A comprehensive experimental study on the antiferromagnetic interlayer exchange coupling in high quality epitaxial all-semiconducting EuSPbSEuS trilayers is reported. The influence of substrates, the thickness of the non-magnetic PbS spacer layer, and of temperature, was investigated by means of SQUID magnetometry. In trilayers with a PbS thickness between 4 and 12 deg A the low temperature hysteresis loops showed the signature of antiferromagnetic coupling. The value of the interlayer exchange coupling energy was determined by simulating the data with a modified Stoner model, including Zeeman, anisotropy, and exchange coupling energies. An important observation was of a strong dependence of the interlayer exchange coupling energy on temperature, consistent with a power law dependence of the exchange coupling constant on the saturation magnetization of the EuS layers. While no theoretical description is readily available, we conjecture that the observed behavior is due to a dependence of the interlayer exchange coupling energy on the exchange splitting of the EuS conduction band.

  13. The 2005 volcano-tectonic earthquake swarm in the Andaman Sea: Triggered by the 2004 great Sumatra-Andaman earthquake

    NASA Astrophysics Data System (ADS)

    Kundu, Bhaskar; Legrand, Denis; Gahalaut, Kalpna; Gahalaut, Vineet K.; Mahesh, P.; Kamesh Raju, K. A.; Catherine, J. K.; Ambikapthy, A.; Chadha, R. K.

    2012-10-01

    A 6 day duration earthquakes swarm occurred in the Andaman Sea, 31 days after the giant 2004 Sumatra-Andaman earthquake (Mw 9.2). The swarm occurred less than 100 km from the eastern edge of the 2004 earthquake rupture and is the most energetic ever recorded in the world. The earthquakes swarm appear to have occurred on en echelon fault system bounded by the two main right-lateral strike-slip faults, namely, the Seulimeum Strand of Sumatra Fault system (SEU) and the West Andaman Fault (WAF). At the beginning of the swarm, earthquakes with predominantly strike-slip focal mechanisms occurred which were followed by earthquakes with predominantly normal faulting focal mechanisms having significant deviatoric component. Highbvalue, presence of double slope in the Gutenberg-Richter relation, presence of monogenetic submarine volcanoes in the region of the swarm and the earthquake focal mechanisms suggest that the swarm was of volcano-tectonic origin and fluid flow played an important role in its occurrence. Indeed, our modeling suggests that it was triggered by the 2004 Sumatra-Andaman earthquake through poroelastic relaxation of the coseismic stresses.

  14. Effects of space radiation on electronic microcircuits

    NASA Technical Reports Server (NTRS)

    Kolasinski, W. A.

    1989-01-01

    The single event effects or phenomena (SEP), which so far have been observed as events falling on one or another of the SE classes: Single Event Upset (SEU), Single Event Latchup (SEL) and Single Event Burnout (SEB), are examined. Single event upset is defined as a lasting, reversible change in the state of a multistable (usually bistable) electronic circuit such as a flip-flop or latch. In a computer memory, SEUs manifest themselves as unexplained bit flips. Since latchup is in general caused by a single event of short duration, the single event part of the SEL term is superfluous. Nevertheless, it is used customarily to differentiate latchup due to a single heavy charged particle striking a sensitive cell from more ordinary kinds of latchup. Single event burnout (SEB) refers usually to total instantaneous failure of a power FET when struck by a single particle, with the device shorting out the power supply. An unforeseen failure of these kinds can be catastrophic to a space mission, and the possibilities are discussed.

  15. A series of color tunable yellow-orange-red-emitting SrWO4:RE (Sm3+, Eu3+-Sm3+) phosphor for near ultraviolet and blue light-based warm white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Ren, Yandong; Liu, Yonghao; Yang, Rui

    2016-03-01

    A series of wide-range-tunable light emissive SrWO4:Sm3+, SrWO4:Sm3+,Eu3+ phosphors were synthesized via the simple co-precipitation method. The charge compensation can greatly improve SrWO4: Sm3+ phosphors luminous intensity. The critical distance, ηT and energy transfer mechanism of SrWO4:0.01Sm3+,0.12Eu3+ were studied. These obtained phosphors exhibit a high luminous efficiency, purity and lower color temperature of the comfortable warm white LEDs. Hues varying have been generated by appropriately tuning the Sm3+ ions concentration, excitation wavelength or Sm3+, Eu3+ co-doping, which have the color tunable wide gamut light covering the yellow-green, greenish-yellow, yellow, yellow orange, orange, reddish orange and red chromaticity region. In particular, SrWO4:0.01Sm3+,0.12Eu3+ phosphors excited at 404 and 480 nm have higher color saturation than commercially available Y2O2S:Eu3+ red phosphor. These phosphors can be excited efficiently using commercial ultraviolet, blue laser diodes and LEDs, and can be used for developing new color light sources, fluorescent display devices, ultraviolet-sensors and tunable visible lasers.

  16. Fluorescence excitation and propagation through brain phantom gelatins: measurements and potential applications

    SciTech Connect

    Allison, Stephen W; Gillies, George

    2010-01-01

    We have investigated the utility of 0.6% agarose gels as surrogate materials for brain tissues in optical propagation studies for possible diagnostic and therapeutic applications. Centimeter-scale layers of the gel exhibited a Beer's law attenuation factor, , of 0.2 mm 1 for incident illumination via a pulsed LED (100 Hz) at 405 nm. This result was different by only about a factor of 3 from the effective penetration depth at similar wavelengths through in vitro samples of the gray (cortical) matter of human brain, as measured by others. Then, films of the thermographic phosphors La2O2S:Eu, Mg4FGeO6:Mn, YAG:Cr and variants of the latter were formed on aluminum substrates and the fluorescence of these samples was stimulated and observed through layers of the gel up to 4 cm thick. In all cases, the fluorescence was easily excited and distinguishable above the background. The results demonstrate that this gel might serve as an inexpensive and robust test bed for exploratory studies of neurological modalities involving propagation of optical signals within brain tissues.

  17. The pixel detector readout ASIC for the MicroVertex Detector of the PANDA experiment

    NASA Astrophysics Data System (ADS)

    Mazza, G.; Calvo, D.; De Remigis, P.; Kugathasan, T.; Mignone, M.; Rivetti, A.; Toscano, L.; Wheadon, R.

    2013-08-01

    The silicon pixel detector of the PANDA experiment is characterized by both high track density and the absence of a hardware trigger signal, thus leading to a huge amount of data to be acquired and transmitted to the DAQ. In order to cope with such challenging requirements, an ASIC based custom solution for the electronic readout has been chosen. The ASIC, named ToPiX, will provide the time position of each hit and a measure of the charge released with the Time over Threshold (ToT) technique. A reduced scale prototype in a CMOS 0.13 μm technology has been designed and tested. The prototype includes four columns made of 128 pixel cells, four columns of 32 cells and the end of column readout with a 32 cells deep FIFO for each double column. Each cell embeds a charge amplifier with constant current feedback capacitor discharge, a comparator with per cell adjustable threshold, 12-bits leading and trailing edge register for time and ToT measurement and an 8 bits configuration register. All the readout logic has been SEU-hardened by design using either Hamming encoding or triple modular redundancy. The chip has been tested both electrically via a test pulse input and connected to a detector in a beam test.

  18. Bimolecular Fluorescence Complementation (BiFC) Assay for Protein-Protein Interaction in Onion Cells Using the Helios Gene Gun

    PubMed Central

    Hollender, Courtney A.; Liu, Zhongchi

    2010-01-01

    Investigation of gene function in diverse organisms relies on knowledge of how the gene products interact with each other in their normal cellular environment. The Bimolecular Fluorescence Complementation (BiFC) Assay1 allows researchers to visualize protein-protein interactions in living cells and has become an essential research tool. This assay is based on the facilitated association of two fragments of a fluorescent protein (GFP) that are each fused to a potential interacting protein partner. The interaction of the two protein partners would facilitate the association of the N-terminal and C-terminal fragment of GFP, leading to fluorescence. For plant researchers, onion epidermal cells are an ideal experimental system for conducting the BiFC assay because of the ease in obtaining and preparing onion tissues and the direct visualization of fluorescence with minimal background fluorescence. The Helios Gene Gun (BioRad) is commonly used for bombarding plasmid DNA into onion cells. We demonstrate the use of Helios Gene Gun to introduce plasmid constructs for two interacting Arabidopsis thaliana transcription factors, SEUSS (SEU) and LEUNIG HOMOLOG (LUH)2 and the visualization of their interactions mediated by BiFC in onion epidermal cells. PMID:20567209

  19. Experiment in Onboard Synthetic Aperture Radar Data Processing

    NASA Technical Reports Server (NTRS)

    Holland, Matthew

    2011-01-01

    Single event upsets (SEUs) are a threat to any computing system running on hardware that has not been physically radiation hardened. In addition to mandating the use of performance-limited, hardened heritage equipment, prior techniques for dealing with the SEU problem often involved hardware-based error detection and correction (EDAC). With limited computing resources, software- based EDAC, or any more elaborate recovery methods, were often not feasible. Synthetic aperture radars (SARs), when operated in the space environment, are interesting due to their relevance to NASAs objectives, but problematic in the sense of producing prodigious amounts of raw data. Prior implementations of the SAR data processing algorithm have been too slow, too computationally intensive, and require too much application memory for onboard execution to be a realistic option when using the type of heritage processing technology described above. This standard C-language implementation of SAR data processing is distributed over many cores of a Tilera Multicore Processor, and employs novel Radiation Hardening by Software (RHBS) techniques designed to protect the component processes (one per core) and their shared application memory from the sort of SEUs expected in the space environment. The source code includes calls to Tilera APIs, and a specialized Tilera compiler is required to produce a Tilera executable. The compiled application reads input data describing the position and orientation of a radar platform, as well as its radar-burst data, over time and writes out processed data in a form that is useful for analysis of the radar observations.

  20. Low energy CMOS for space applications

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Alkalaj, Leon

    1992-01-01

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  1. Formation Control of the MAXIM L2 Libration Orbit Mission

    NASA Technical Reports Server (NTRS)

    Folta, David; Hartman, Kate; Howell, Kathleen; Marchand, Belinda

    2004-01-01

    The Micro-Arcsecond X-ray Imaging Mission (MAXIM), a proposed concept for the Structure and Evolution of the Universe (SEU) Black Hole Imager mission, is designed to make a ten million-fold improvement in X-ray image clarity of celestial objects by providing better than 0.1 micro-arcsecond imaging. Currently the mission architecture comprises 25 spacecraft, 24 as optics modules and one as the detector, which will form sparse sub-apertures of a grazing incidence X-ray interferometer covering the 0.3-10 keV bandpass. This formation must allow for long duration continuous science observations and also for reconfiguration that permits re-pointing of the formation. To achieve these mission goals, the formation is required to cooperatively point at desired targets. Once pointed, the individual elements of the MAXIM formation must remain stable, maintaining their relative positions and attitudes below a critical threshold. These pointing and formation stability requirements impact the control and design of the formation. In this paper, we provide analysis of control efforts that are dependent upon the stability and the configuration and dimensions of the MAXIM formation. We emphasize the utilization of natural motions in the Lagrangian regions to minimize the control efforts and we address continuous control via input feedback linearization (IFL). Results provide control cost, configuration options, and capabilities as guidelines for the development of this complex mission.

  2. Formation Control of the MAXIM L2 Libration Orbit Mission

    NASA Technical Reports Server (NTRS)

    Folta, David; Hartman, Kate; Howell, Kathleen; Marchand, Belinda

    2004-01-01

    The Micro-Arcsecond Imaging Mission (MAXIM), a proposed concept for the Structure and Evolution of the Universe (SEU) Black Hole Imaging mission, is designed to make a ten million-fold improvement in X-ray image clarity of celestial objects by providing better than 0.1 microarcsecond imaging. To achieve mission requirements, MAXIM will have to improve on pointing by orders of magnitude. This pointing requirement impacts the control and design of the formation. Currently the architecture is comprised of 25 spacecraft, which will form the sparse apertures of a grazing incidence X-ray interferometer covering the 0.3-10 keV bandpass. This configuration will deploy 24 spacecraft as optics modules and one as the detector. The formation must allow for long duration continuous science observations and also for reconfiguration that permits re-pointing of the formation. In this paper, we provide analysis and trades of several control efforts that are dependent upon the pointing requirements and the configuration and dimensions of the MAXIM formation. We emphasize the utilization of natural motions in the Lagrangian regions that minimize the control efforts and we address both continuous and discrete control via LQR and feedback linearization. Results provide control cost, configuration options, and capabilities as guidelines for the development of this complex mission.

  3. PRBP: Prediction of RNA-Binding Proteins Using a Random Forest Algorithm Combined with an RNA-Binding Residue Predictor.

    PubMed

    Ma, Xin; Guo, Jing; Xiao, Ke; Sun, Xiao

    2015-01-01

    The prediction of RNA-binding proteins is an incredibly challenging problem in computational biology. Although great progress has been made using various machine learning approaches with numerous features, the problem is still far from being solved. In this study, we attempt to predict RNA-binding proteins directly from amino acid sequences. A novel approach, PRBP predicts RNA-binding proteins using the information of predicted RNA-binding residues in conjunction with a random forest based method. For a given protein, we first predict its RNA-binding residues and then judge whether the protein binds RNA or not based on information from that prediction. If the protein cannot be identified by the information associated with its predicted RNA-binding residues, then a novel random forest predictor is used to determine if the query protein is a RNA-binding protein. We incorporated features of evolutionary information combined with physicochemical features (EIPP) and amino acid composition feature to establish the random forest predictor. Feature analysis showed that EIPP contributed the most to the prediction of RNA-binding proteins. The results also showed that the information from the RNA-binding residue prediction improved the overall performance of our RNA-binding protein prediction. It is anticipated that the PRBP method will become a useful tool for identifying RNA-binding proteins. A PRBP Web server implementation is freely available at http://www.cbi.seu.edu.cn/PRBP/. PMID:26671809

  4. Summer Schools for European teachers

    NASA Astrophysics Data System (ADS)

    Ros, Rosa M.

    The Summer Schools have been organised by the European Association for Astronomy Education (EAAE) for European teachers. The first was organised in La Seu d'Urgell, Spain, the second was organised in 1998 in Fregene, Italy and the third in 1999, during the week of the eclipse in Briey, France, on the line of total darkness. We had a cloudy eclipse, but fortunately we could observe it. We are preparing the 4th one next July in Tavira, Portugal. A group of 50 participants are involved in each Summer School. In the last one the participants were from 14 countries. The activities are organised in General Lectures, Working Groups and Workshops to reduced groups and day and night Observations. To increase communication, each Summer School has three official languages: the language of the host country, English and another well-known by the participants. The proceedings are published beforehand with all the contents to facilitate participation. Each paper appears in English and another language. The activities are organised in General Lectures, Working Groups and Workshops to reduced groups and day and night Observations. To increase communication, each Summer School has three official languages: the language of the host country, English and another well-known by the participants. The proceedings are published beforehand with all the contents to facilitate participation. Each paper appears in English and another language.

  5. High LET Single Event Upset Cross Sections For Bulk and SOI CMOS SRAMs

    SciTech Connect

    McDaniel, F.D.; Doyle, B.L.; Vizkelethy, G.; Dodd, P.E.; Rossi, P.

    2003-08-26

    Electronics in spacecraft and satellites are exposed to high-energy cosmic radiation. In addition, terrestrial radiation can also affect earth-based electronics. To study the effects of radiation upon integrated circuits and to insure the reliability of electronic devices, cosmic and terrestrial radiations are simulated with ion beams from particle accelerators. A new, higher Linear Energy Transfer (LET) acceleration system for heavy ions has been developed at Sandia National Laboratories. Heavy ions from a 6.5 MV EN tandem Van de Graaff accelerator at 0.25 MeV/amu are injected into a two-stage Radio Frequency Quadrupole (RFQ) linac, which accelerates the ions to 1.9 MeV/amu. These ions together with those from the Brookhaven National Laboratory MP Tandem have been used to measure single event upset (SEU) cross sections as a function of LET for both bulk and Silicon on Insulator (SOI) Complementary Metal Oxide Semiconductor, Static Random Access Memories. The magnitudes of these cross sections indicate that the upsets in both the SOI and bulk parts are caused by OFF-drain strikes.

  6. Detection efficiency and spatial resolution of the SIRAD ion electron emission microscope

    NASA Astrophysics Data System (ADS)

    Bisello, D.; Giubilato, P.; Kaminsky, A.; Mattiazzo, S.; Nigro, M.; Pantano, D.; Silvestrin, L.; Tessaro, M.; Wyss, J.; Bertazzoni, S.; Mongiardo, L.; Salmeri, M.; Salsano, A.

    2009-06-01

    An axial ion electron emission microscope (IEEM) has been built at the SIRAD irradiation facility at the 15 MV Tandem accelerator of INFN Legnaro National Laboratory (Padova, Italy) to obtain a micrometric sensitivity map to single event effects (SEE) of electronic devices. In this contribution we report on two experiments performed with the IEEM. Si 3N 4 ultra-thin membranes with a gold deposition were placed on the device under test (DUT) to ensure a uniform and abundant secondary electron emission In the first experiment we measured an IEEM ion detection efficiency of 83% with a 58Ni (220 MeV) beam, in good agreement with the expected value. The second experiment allowed us to estimate the lateral resolution of the IEEM. The positions of ion induced single event upsets (SEU) in a synchronous dynamic random access memory (SDRAM), used as a reference target, were compared with the corresponding ion impact points reconstructed by the IEEM. The result (FWHM ˜4.4 μm with a 79Br beam of 214 MeV) is encouraging because of the residual presence of distortions of the image and mechanical vibrations.

  7. Image Quality Assessment of a CMOS/Gd2O2S:Pr,Ce,F X-ray Sensor

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Seferis, I. E.; Sideras, T.; Valais, I. G.; Fountos, G. P.; Bakas, A.; Panayiotakis, G. S.; Kandarakis, I. S.

    2015-09-01

    The aim of the present study was to examine the image quality performance of a CMOS digital imaging optical sensor coupled to custom made gadolinium oxysulfide powder scintillators, doped with praseodymium, cerium and fluorine (Gd2O2S:Pr,Ce,F) screens. The screens, with coating thicknesses 35.7 and 71.2 mg/cm2, were prepared in our laboratory from Gd2O2S:Pr,Ce,F powder (Phosphor Technology, Ltd) by sedimentation on silica substrates and were placed in direct contact with the optical sensor. Image quality was determined through a single index image quality parameter (information capacity). The CMOS sensor/Gd2O2S:Pr,Ce,F screens combinations were irradiated under the RQA-5 (IEC 62220-1) beam quality. The detector response function was linear for the exposure range under investigation. Under the general radiography conditions, both Gd2O2S:Pr,Ce,F screen/CMOS combinations exhibited comparable overall imaging properties, in terms of the information capacity, to previously published scintillators, such as Gd2O2S:Eu.

  8. Multi-bits error detection and fast recovery in RISC cores

    NASA Astrophysics Data System (ADS)

    Jing, Wang; Xing, Yang; Yuanfu, Zhao; Weigong, Zhang; Jiao, Shen; Keni, Qiu

    2015-11-01

    The particles-induced soft errors are a major threat to the reliability of microprocessors. Even worse, multi-bits upsets (MBUs) are ever-increased due to the rapidly shrinking feature size of the IC on a chip. Several architecture-level mechanisms have been proposed to protect microprocessors from soft errors, such as dual and triple modular redundancies (DMR and TMR). However, most of them are inefficient to combat the growing multi-bits errors or cannot well balance the critical paths delay, area and power penalty. This paper proposes a novel architecture, self-recovery dual-pipeline (SRDP), to effectively provide soft error detection and recovery with low cost for general RISC structures. We focus on the following three aspects. First, an advanced DMR pipeline is devised to detect soft error, especially MBU. Second, SEU/MBU errors can be located by enhancing self-checking logic into pipelines stage registers. Third, a recovery scheme is proposed with a recovery cost of 1 or 5 clock cycles. Our evaluation of a prototype implementation exhibits that the SRDP can successfully detect particle-induced soft errors up to 100% and recovery is nearly 95%, the other 5% will inter a specific trap.

  9. Noise impact of single-event upsets on an FPGA-based digital filter

    SciTech Connect

    Morgan, Keith S; Caffrey, Michael P; Graham, Paul S; Pratt, Brian H; Wirthlin, Michael J

    2009-01-01

    Field-programmable gate arrays are well-suited to DSP and digital communications applications. SRAM-based FPGAs, however, are susceptible to radiation-induced single-event upsets (SEUs) when deployed in space environments. These effects are often handled with the area and power-intensive TMR mitigation technique. This paper evaluates the effects of SEUs in the FPGA configuration memory as noise in a digital filter, showing that many SEUs in a digital communications system cause effects that could be considered noise rather than circuit failure. Since DSP and digital communications applications are designed to withstand certain types of noise, SEU mitigation techniques that are less costly than TMR may be applicable. This could result in large savings in area and power when implementing a reliable system. Our experiments show that, of the SEUs that affected the digital filter with a 20 dB SNR input signal, less than 14% caused an SNR loss of more than 1 dB at the output.

  10. Group A rotavirus gastroenteritis: post-vaccine era, genotypes and zoonotic transmission.

    PubMed

    Luchs, Adriana; Timenetsky, Maria do Carmo Sampaio Tavares

    2016-01-01

    ABSTRACTThis article provides a review of immunity, diagnosis, and clinical aspects of rotavirus disease. It also informs about the changes in epidemiology of diarrheal disease and genetic diversity of circulating group A rotavirus strains following the introduction of vaccines. Group A rotavirus is the major pathogen causing gastroenteritis in animals. Its segmented RNA genome can lead to the emergence of new or unusual strains in human populations via interspecies transmission and/or reassortment events.RESUMOEste artigo fornece uma revisão sobre imunidade, diagnóstico e aspectos clínicos da doença causada por rotavírus. Também aponta as principais mudanças no perfil epidemiológico da doença diarreica e na diversidade genética das cepas circulantes de rotavírus do grupo A, após a introdução vacinal. O rotavírus do grupo A é o principal patógeno associado à gastroenterite em animais. Seu genoma RNA segmentado pode levar ao surgimento de cepas novas ou incomuns na população humana, por meio de transmissão entre espécies e eventos de rearranjo. PMID:27462899

  11. Resposta do detector de ondas gravitacionais Mario Schenberg ao "ringdown" de buraco negros

    NASA Astrophysics Data System (ADS)

    Costa, C. A.; Aguiar, O. D.; Magalhães, N. S.

    2003-08-01

    Acredita-se que quando duas estrelas de nêutrons coalescem, elas, eventualmente, formam um buraco negro com massa igual a soma das massas dos objetos originais. Durante a formação do buraco negro, o espaço-tempo em torno do sistema sofre perturbações que se propagam na forma de radiação gravitacional. A forma de onda associada a radiação gravitacional, durante este estágio, aproxima-se a uma senóide exponencialmente amortecida. Este tipo de sinal é conhecido como "ringdown", e seu comportamento e parametrização são muito bem conhecidos. Neste trabalho, simulamos computacionalmente sinais provenientes do "ringdown" de buracos negros, com a finalidade de testar o desempenho do detector de ondas gravitacionais Mario Schenberg em observá-los, quando entrar em funcionamento. Este primeiro teste teórico ajudou-nos a criar estratégias de detecção de sinais imersos no ruído instrumental. Calculamos a relação sinal-ruído como uma função da frequência, bem como sua integral dentro da faixa de sensibilidade do detector. Os resultados obtidos mostraram que o detector Schenberg terá sensibilidade suficiente para detectar este tipo de sinal, proveniente de fontes astrofísicas localizadas dentro de um raio de ~100kpc.

  12. Single channel flow blockage accident phenomena identification and ranking table (PIRT) for the advanced Candu reactor

    SciTech Connect

    Popov, N.K.; Abdul-Razzak, A.; Snell, V.G.; Langman, V.; Sills, H.

    2004-07-01

    The Advanced Candu Reactor (ACRTM) is an evolutionary advancement of the current Candu 6{sup R} reactor, aimed at producing electrical power for a capital cost and at a unit-energy cost significantly less than that of the current reactor designs. The ACR retains the modular concept of horizontal fuel channels surrounded by a heavy water moderator, as with all Candu reactors. However, ACR uses slightly enriched uranium (SEU) fuel, compared to the natural uranium used in Candu 6. This achieves the twin goals of improved economics (e.g., via reductions in the heavy water requirements and the use of a light water coolant), as well as improved safety. This paper documents the results of Phenomena Identification and Ranking Table (PIRT) results for a very limited frequency, beyond design basis event of the ACR design. This PIRT is developed in a highly structured process of expert elicitation that is well supported by experimental data and analytical results. The single-channel flow blockage event in an ACR reactor assumes a severe flow blockage of one of the reactor fuel channels, which leads to a reduction of the flow in the affected channel, leading to fuel cladding and fuel temperature increase. The paper outlines the design characteristics of the ACR reactor that impact the PIRT process and computer code applicability. It also describes the flow blockage phenomena, lists all components and systems that have an important role during the event, discusses the PIRT process and results, and presents the finalized PIRT tables. (authors)

  13. Space Environment Information System (SPENVIS)

    NASA Astrophysics Data System (ADS)

    Kruglanski, Michel; de Donder, Erwin; Messios, Neophytos; Hetey, Laszlo; Calders, Stijn; Evans, Hugh; Daly, Eamonn

    SPENVIS is an ESA operational software developed and maintained at BIRA-IASB since 1996. It provides standardized access to most of the recent models of the hazardous space environment, through a user-friendly Web interface (http://www.spenvis.oma.be/). The system allows spacecraft engineers to perform a rapid analysis of environmental problems related to natural radiation belts, solar energetic particles, cosmic rays, plasmas, gases, magnetic fields and micro-particles. Various reporting and graphical utilities and extensive help facilities are included to allow engineers with relatively little familiarity to produce reliable results. SPENVIS also contains an active, integrated version of the ECSS Space Environment Standard and access to in-flight data on the space environment. Although SPENVIS in the first place is designed to help spacecraft designers, it is also used by technical universities in their educational programs. In the framework of the ESA Space Situational Awareness Preparatory Programme, SPENVIS will be part of the initial set of precursor services of the Space Weather segment. SPENVIS includes several engineering models to assess to effects of the space environment on spacecrafts such as surface and internal charging, energy deposition, solar cell damage and SEU rates. The presentation will review how such models could be connected to in situ measurements or forecasting models of the space environment in order to produce post event analysis or in orbit effects alert. The last developments and models implemented in SPENVIS will also be presented.

  14. Plug-and-Play Environmental Monitoring Spacecraft Subsystem

    NASA Technical Reports Server (NTRS)

    Patel, Jagdish; Brinza, David E.; Tran, Tuan A.; Blaes, Brent R.

    2011-01-01

    A Space Environment Monitor (SEM) subsystem architecture has been developed and demonstrated that can benefit future spacecraft by providing (1) real-time knowledge of the spacecraft state in terms of exposure to the environment; (2) critical, instantaneous information for anomaly resolution; and (3) invaluable environmental data for designing future missions. The SEM architecture consists of a network of plug-and- play (PnP) Sensor Interface Units (SIUs), each servicing one or more environmental sensors. The SEM architecture is influenced by the IEEE Smart Transducer Interface Bus standard (IEEE Std 1451) for its PnP functionality. A network of PnP Spacecraft SIUs is enabling technology for gathering continuous real-time information critical to validating spacecraft health in harsh space environments. The demonstrated system that provided a proof-of-concept of the SEM architecture consisted of three SIUs for measurement of total ionizing dose (TID) and single event upset (SEU) radiation effects, electromagnetic interference (EMI), and deep dielectric charging through use of a prototype Internal Electro-Static Discharge Monitor (IESDM). Each SIU consists of two stacked 2X2 in. (approximately 5X5 cm) circuit boards: a Bus Interface Unit (BIU) board that provides data conversion, processing and connection to the SEM power-and-data bus, and a Sensor Interface Electronics (SIE) board that provides sensor interface needs and data path connection to the BIU.

  15. Uranium comparison by means of AMS and ICP-MS and Pu and 137Cs results around an Italian Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    De Cesare, M.; Tims, S. G.; Fifield, L. K.

    2015-04-01

    Italy built and commissioned 4 nuclear power plants between 1958-1978, which delivered a total of 1500 MW. All four were closed down after the Chernobyl accident following a referendum in 1987. One of the plants was Garigliano, commissioned in 1959. This plant used a 160 MW BWR1 (SEU of 2.3 %) and was operational from 1964 to 1979, when it was switched off for maintenance. It was definitively stopped in 1982, and is presently being decommissioned. We report here details on the chemistry procedure and on the measurements for soil samples, collected up to 4.5 km from the Nuclear Plant. A comparison between uranium (238U) concentration as determined by means of AMS (Accelerator Mass Spectrometry) and by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) techniques respectively at the ANU (Australian National University) and at the Ecowise company in Canberra, Australia, is reported, as well as 236U and 239;240Pu concentration results detected by AMS. 236U/238U and 240Pu/239Pu isotopic ratios by means of AMS are also provided. A contamination from Chernobyl is visible in the 137Cs/239+240Pu activity ratio measurements.

  16. Cathodoluminescence of Ca/sub 1//sub -/ /sub x/ Mg /sub x/ S:A (A = Eu or Ce)

    SciTech Connect

    Kasano, J.; Megumi, K.; Yamamoto, H.

    1984-08-01

    Cathodoluminescent properties of Eu/sup 2 +/ - or Ce/sup 3 +/ -activated MgS and Ca/sub 1//sub -/..integral.. Mg..integral..S phosphors are investigated at 300 K. It found that MgS:Eu(0.01 mole percent (m/o) exhibits a high energy efficiency (about 16%) and a improved waterresistance if residual oxide content is less than 1 m/o. Under these highly sulfurizing conditions MgS is confirmed to be completely miscible with CaS in any compositional ratio. The composition Ca /sub 0.1/ Mg /sub 0.9/ S:Eu(0.05 m/o), Ba(0.1 m/o), whose color coordinates are comparable to the red phosphor (Y /sub 0.964/ Eu /sub 0.036/ )/sub 2/O/sub 2/S, exceeds the latter in brightness by 15% at 18 kV excitation. Additionally, Eu/sup 2 +/-activated alkaline-earth binary sulfides are examined. A complete miscibility is ascertained in the pseudobinary system where the difference in cation radius is less than 0.035 nm. Stress-induced peak shifts are observed in MgS:Eu and A/sub 1//sub -/ /sub y/ B /sub y/ S (A or B is identical to Mg, Ca, Sr or Ba, A is identical to B). Some mechanisms for these shifts are proposed.

  17. Prediction Accuracy of Error Rates for MPTB Space Experiment

    NASA Technical Reports Server (NTRS)

    Buchner, S. P.; Campbell, A. B.; Davis, D.; McMorrow, D.; Petersen, E. L.; Stassinopoulos, E. G.; Ritter, J. C.

    1998-01-01

    This paper addresses the accuracy of radiation-induced upset-rate predictions in space using the results of ground-based measurements together with standard environmental and device models. The study is focused on two part types - 16 Mb NEC DRAM's (UPD4216) and 1 Kb SRAM's (AMD93L422) - both of which are currently in space on board the Microelectronics and Photonics Test Bed (MPTB). To date, ground-based measurements of proton-induced single event upset (SEM cross sections as a function of energy have been obtained and combined with models of the proton environment to predict proton-induced error rates in space. The role played by uncertainties in the environmental models will be determined by comparing the modeled radiation environment with the actual environment measured aboard MPTB. Heavy-ion induced upsets have also been obtained from MPTB and will be compared with the "predicted" error rate following ground testing that will be done in the near future. These results should help identify sources of uncertainty in predictions of SEU rates in space.

  18. South Atlantic anomaly and CubeSat design considerations

    NASA Astrophysics Data System (ADS)

    Fennelly, Judy A.; Johnston, William R.; Ober, Daniel M.; Wilson, Gordon R.; O'Brien, T. Paul; Huston, Stuart L.

    2015-09-01

    Effects of the South Atlantic Anomaly (SAA) on spacecraft in low Earth orbit (LEO) are well known and documented. The SAA exposes spacecraft in LEO to high dose of ionizing radiation as well as higher than normal rates of Single Event Upsets (SEU) and Single Event Latch-ups (SEL). CubeSats, spacecraft built around 10 x 10 x 10 cm cubes, are even more susceptible to SEUs and SELs due to the use of commercial off-the-shelf components for electronics and payload instrumentation. Examination of the SAA using both data from the Defense Meteorological Satellite Program (DMSP) and a new set of models for the flux of particles is presented. The models, AE9, AP9, and SPM for energetic electrons, energetic protons and space plasma, were developed for use in space system design. These models introduce databased statistical constraints on the uncertainties from measurements and climatological variability. Discussion of the models' capabilities and limitations with regard to LEO CubeSat design is presented.

  19. Nonvolatile Memory Solution for Near-Term NASA Missions

    NASA Technical Reports Server (NTRS)

    Patel, J. U.; Blaes, B. R.; Mojarradi, M. M.

    2001-01-01

    Nonvolatile memory (NVM) system that could reliably function in extreme environments is one of the most critical components for many spacecrafts being developed for NASA missions to be launched in next four to seven years. NVM supports the computer system in saving and updating critical state data required for a warm restart after power cycling or in case of a power bus failure. It also provides a power independent mass storage capacity for the scientific data gathered by the instruments. In some cases the window for gathering such data is very small and occurs only once in a given mission. Commercially popular and fully developed Flash NVM technology is inappropriate for many reasons such as the limited read write cycles with slower access speeds, radiation intolerance, higher Single Event Upsets (SEU) rates, etc. It is desirable to have an NVM system based upon a robust cell technology making it immune to the SEUs and with sufficient radiation hardness. Availability of such NVM system seems to be still 5 to 10 years in the future. Meanwhile, it is possible to provide an interim hybrid solution by combining the existing rad-hard technologies. Additional information is contained in the original extended abstract.

  20. [Textual research on adulteration of Chinese materia medica in ancient China].

    PubMed

    Xie, Jin; Wang, De-Qun

    2013-09-01

    By investigating the mainstream works of herbal classics of successive ages, it is found that adulteration of Chinese materia medica appeared early in ancient China. The main methods of adulteration was producing fraud medicines in the Northern-Southern Dynasties, fake medicines began to appear in the Tang Dynasty, and status of adulteration of Chinese materia medica ran unchecked since the Ming and Qing Dynasty. By statistics, there were 76 kinds of adulteration varieties before the Republican period. The main varieties were precious drugs, animal drugs and artifacts. Commonly methods used in the process included forging and adulterating, dealing with 11 kinds and 68 kinds respectively. Adulteration probably lead to the result of imposing the changes of the used medicinal parts of Herba Pogostemonis; Radix Aconiti Lateralis prepared by adding salt, Radix Angelica Sinensis processed by wine, and Radix Astragalis seu Hedysaris processed with bee honey. However, the root cause of adulteration in Chinese materia medica was the dissociation of professional physician and pharmacist, resulting in the ignorance of medical practitioners became unable to recognize Chinese materia medica; and the immorality of medicinal merchants. Besides, rating the quality of materia medica based on its producing areas without differentiating the false from the genuine may also contribute to this result passively. PMID:24429032

  1. Report on final recommendations for IMPS engineering-science payload

    NASA Technical Reports Server (NTRS)

    Garrett, H. B.

    1984-01-01

    Six general categories of key scientific and engineering concerns for the interactions measurements payload for shuttle (IMPS) mission are addressed: (1) dielectric charging; (2) material property changes; (3) electromagnetic interference, plasma interactions, and plasma wake effects associated with high-voltage solar arrays and large space structures; (4) radio frequency distortion and nonlinearities due to the enhanced plasma in the shuttle ram/wake; (5) shuttle glow and contamination; and (6) plasma interactions with the space-based radar. Lesser concerns are the interactions associated with EVA; the radiation and SEU effects peculiar to the auroral/polar cap environments; and space debris. The measurements needed to address the concerns associated with the general categories are described and a list of generic investigations capable of making the required measurements, emphasizing the spectrum of measurements necessary to quantize the interactions in the auroral/polar environments are included. A suggested ground-test plan for the IMPS project, a description of proposed follow-on IMPS missions, and a detailed bibliography for each of the interactions discussed are included.

  2. Solar flare proton evaluation at geostationary orbits for engineering applications

    SciTech Connect

    Stassinopoulos, E.G.; Barth, J.L.; Brucker, G.J.; Nakamura, D.W.; Stauffer, C.A.; Gee, G.B.

    1996-04-01

    This work presents the results of novel analyses of spacecraft solar flare proton measurements for solar cycles 20, 21, and 22. Solar events and cycles were classified and ranked by fluence and frequency of occurrence, and events were characterized by the mean energy of the proton spectral distributions. Spacecraft observations permitted a detailed study of event characteristics, such as special consideration of solar minimum flares and cycle variability. Tables and curves are presented to allow evaluations of potential threats to spacecraft survivability at GEO, particularly for types of flare environments that emulate solar cycle 22. Upsets for major events are calculated for several Bendel A parameter values and shield thicknesses, and effective energy thresholds of events are determined as a function of these variables. Critical fluence levels, required to cause errors, versus A are presented. SEU`s (single event upsets) of 93L422 devices on TDRS-1 are evaluated for various shielding conditions. Finally, upset dependencies on A and shield thickness are correlated with event fluences for threshold energies of >30, >50, and >60 MeV.

  3. Two common structural motifs for TCR recognition by staphylococcal enterotoxins.

    PubMed

    Rödström, Karin E J; Regenthal, Paulina; Bahl, Christopher; Ford, Alex; Baker, David; Lindkvist-Petersson, Karin

    2016-01-01

    Superantigens are toxins produced by Staphylococcus aureus, called staphylococcal enterotoxins (abbreviated SEA to SEU). They can cross-link the T cell receptor (TCR) and major histocompatibility complex class II, triggering a massive T cell activation and hence disease. Due to high stability and toxicity, superantigens are potential agents of bioterrorism. Hence, antagonists may not only be useful in the treatment of disease but also serve as countermeasures to biological warfare. Of particular interest are inhibitors against SEA and SEB. SEA is the main cause of food poisoning, while SEB is a common toxin manufactured as a biological weapon. Here, we present the crystal structures of SEA in complex with TCR and SEE in complex with the same TCR, complemented with computational alanine-scanning mutagenesis of SEA, SEB, SEC3, SEE, and SEH. We have identified two common areas that contribute to the general TCR binding for these superantigens. This paves the way for design of single antagonists directed towards multiple toxins. PMID:27180909

  4. Two common structural motifs for TCR recognition by staphylococcal enterotoxins

    PubMed Central

    Rödström, Karin E. J.; Regenthal, Paulina; Bahl, Christopher; Ford, Alex; Baker, David; Lindkvist-Petersson, Karin

    2016-01-01

    Superantigens are toxins produced by Staphylococcus aureus, called staphylococcal enterotoxins (abbreviated SEA to SEU). They can cross-link the T cell receptor (TCR) and major histocompatibility complex class II, triggering a massive T cell activation and hence disease. Due to high stability and toxicity, superantigens are potential agents of bioterrorism. Hence, antagonists may not only be useful in the treatment of disease but also serve as countermeasures to biological warfare. Of particular interest are inhibitors against SEA and SEB. SEA is the main cause of food poisoning, while SEB is a common toxin manufactured as a biological weapon. Here, we present the crystal structures of SEA in complex with TCR and SEE in complex with the same TCR, complemented with computational alanine-scanning mutagenesis of SEA, SEB, SEC3, SEE, and SEH. We have identified two common areas that contribute to the general TCR binding for these superantigens. This paves the way for design of single antagonists directed towards multiple toxins. PMID:27180909

  5. Time resolved ion beam induced charge collection

    SciTech Connect

    SEXTON,FREDERICK W.; WALSH,DAVID S.; DOYLE,BARNEY L.; DODD,PAUL E.

    2000-04-01

    Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a {minus}.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients.

  6. A correlação índice espectral vs. luminosidade em QSOs e suas implicações

    NASA Astrophysics Data System (ADS)

    Garcia-Rissmann, A.

    2003-08-01

    Estudos de variabilidade de núcleos ativos já demonstraram ser comum o fato de seu contínuo óptico/UV tornar-se mais "duro" à medida que a luminosidade aumenta. Essa tendência ocorre tanto de forma individual quanto global, e pode ter implicações importantes (1) para estudos fotométricos de variabilidade conduzidos numa banda fixa no referencial do observador, comparando objetos a diferentes redshifts, e (2) no cálculo da correção K, com consequente impacto na determinação de massas de buracos negros e bojos de galáxias hospedeiras (através da relação de Magorrian). Confirmo aqui as correlações positivas entre o índice espectral e a luminosidade óptica, utilizando dados espectroscópicos de 11 QSOs monitorados no Brasil e no Chile, durante ~2 anos. O estudo é complementado com parâmetros extraídos de espectros e de dados fotométricos públicos de quasares. Destaco ainda as diferenças observadas em tais correlações para objetos do tipo radio-loud e radio-quiet. Este projeto é financiado pelo I. Milênio/CNPq.

  7. Perfil de temperatura dos funis magnetosféricos de estrelas T Tauri com aquecimento alfvênico

    NASA Astrophysics Data System (ADS)

    Vasconcelos, M. J.

    2003-08-01

    Estrelas T Tauri Clássicas são objetos jovens circundados por discos de gás e poeira e que apresentam uma intensa atividade magnética. Seu espectro mostra linhas de emissão alargadas que são razoavelmente reproduzidas nos modelos de acresção magnetosférica. No entanto, o perfil de temperatura dos funis magnéticos é desconhecido. Aquecimento magnético compressional e difusão ambipolar foram considerados para estas estruturas, porém as temperaturas obtidas não são suficientes para explicar as observações. Neste trabalho, examinamos o aquecimento gerado pelo amortecimento de ondas Alfvén através de quatro mecanismos, os amortecimentos não-linear, turbulento, viscoso-resistivo e colisional como função da freqüência da onda. Inicialmente, a temperatura é ajustada para reproduzir as observações e o grau de turbulência requerido para que o mecanismo seja viável é calculado. Os resultados mostram que este é compatível com os dados observacionais. Apresentam-se, também, resultados preliminares do cálculo auto-consistente do perfil de temperatura dos funis, levando-se em conta fontes de aquecimento Alfvênica e fontes de resfriamento.

  8. The advances and new technologies for the study of mitochondrial diseases.

    PubMed

    Bianco, Bianca; Montagna, Erik

    2016-01-01

    ABSTRACTGenetic mitochondrial disorders are responsible for the most common inborn errors of metabolism, caused by mutations in either nuclear genes or in mitochondrial DNA. This article presents the prokaryotic origin of the organelle and the relation between nuclear and mitochondrial genomes, as well as current evolutionary models for such mechanisms. It also addresses the structure of mitochondrial genes, their expression pattern, clinical features of gene defects, risk of transmission and current techniques to avoid these events in assisted human reproduction. Finally, it discusses the ethical implications of these possibilities.RESUMOAs doenças genéticas mitocondriais são responsáveis pelos erros inatos do metabolismo mais comuns, causados por mutações tanto em genes nucleares como no DNA mitocondrial. Este artigo apresenta a origem procariótica dessa organela, e a relação entre os genomas nuclear e mitocondrial, bem como modelos evolutivos correntes para esses mecanismos. Também trata da estrutura dos genes mitocondriais, seu padrão de expressão, características clínicas de defeitos genéticos, riscos de transmissão e técnicas atualmente utilizadas para evitar esses eventos em reprodução humana assistida. Finalmente, discute as implicações éticas dessas possibilidades. PMID:27462900

  9. Use of SX Series Devices and IEEE 1149.1 JTAG Circuitry

    NASA Technical Reports Server (NTRS)

    Katz, Richard B.; Wang, J. J.

    1998-01-01

    This report summarizes the use of SX series devices and their JTAG 1149.1 circuitry. 'JTAG' circuitry was originally designed to standardize testing of boards via a simple control port interface electrically without having to use devices such as a bed of nails tester. JTAG is also used for other functions such as executing built-in-test sequences, identifying devices, or, through custom instructions, other functions designed in by the chip designer. The JTAG circuitry is designed for test only; it has no functional use in the integrated circuit during normal operations. The JTAG circuitry and the mode of the device is controlled by a circuit block known as the 'TAP controller,' which is a sixteen-state state machine along with various registers. The controller is normally in an operational state known as TEST-LOGIC-RESET. In this state, the device is held in a fully functional, operational mode. However, a Single Event Upset (SEU) may remove the TAP controller from this state, causing a loss of control of the integrated circuit, unless certain precautions are taken, such as grounding the optional JTAG TRST signal.

  10. Preliminary test results for the SVX4

    SciTech Connect

    Christofek, L.; Hanagaki, K.; Rapidis, P.; Utes, M.; /Fermilab

    2005-06-01

    We present and summarize the preliminary test results for SVX4 chip testing. There are presently two versions of the SVX4. Version 2 has on-chip bypassing and Version 1 does not. The on-chip bypassing is a layer of transistors under the front-end analog pipeline that acts as a bypassing capacitor for the voltage supply. Its size is about a microfarad. We aggressively choose to test Version 2 because of this feature. The feature is advantageous for hybrid design because it eliminates the need for an additional passive component on the hybrid itself by placing it on the actual SVX4 die. Also, the SVX4 was designed to operate in two modes: D. and CDF. One can set which mode the chip will operate by placing a jumper in the proper position on the SVX4 chip carrier. In either mode, the chip can either use the operating parameters from the shift register or the shadow register. Similarly, this is selected by placing a jumper on the SVX4 chip carrier. This chip has this feature because it was unknown whether the new design of the shadow register would be operable. The shadow register is also call the SEU register or Single Event Upset register. An introduction into the functionality of the chip and an explanation on the difference between D. and CDF mode can be found in the SVX4 User's Manual [1].

  11. Virtex-II Pro SEE Test Methods and Results

    NASA Technical Reports Server (NTRS)

    Petrick, David; Powell, Wesley; Howard, James

    2004-01-01

    The Xilinx Virtex-II Pro is a platform FPGA that embeds multiple microprocessors within the fabric of an SRAM-based reprogrammable FPGA. The variety and quantity of resources provided by this family of devices make them very attractive for spaceflight applications. However, these devices will be susceptible to single event effects (SEE), which must be mitigated. To use the Virtex-II Pro reliably in space applications, these devices must first be tested to determine if they are susceptible to single event latchup (SEL), the degree to which they are susceptible to single event upsets (SEU) and single event transients (SET), and how these effects are manifested in the device. With this information, mitigations schemes can be developed and tested that address the specific susceptiblities of these devices. This initial SEE test uses a commercial off the shelf Virtex-II Pro evaluation board, with a single processor XC2VP7 FPGA. The FPGA on this board is an acid etched device, which can be partially covered with a shield. The shield covers a portion of the logic, routing, and memory resources along with some of the RocketIO transceivers. The processor, along with a large portion of logic, routing, memory, and transceivers are left exposed. This test will be performed at the Cyclotron Laboratories at Texas A&M University and Michigan State University using ions of varying energy levels and fluencies.

  12. Reliability concerns with logical constants in Xilinx FPGA designs

    SciTech Connect

    Quinn, Heather M; Graham, Paul; Morgan, Keith; Ostler, Patrick; Allen, Greg; Swift, Gary; Tseng, Chen W

    2009-01-01

    In Xilinx Field Programmable Gate Arrays logical constants, which ground unused inputs and provide constants for designs, are implemented in SEU-susceptible logic. In the past, these logical constants have been shown to cause the user circuit to output bad data and were not resetable through off-line rcconfiguration. In the more recent devices, logical constants are less problematic, though mitigation should still be considered for high reliability applications. In conclusion, we have presented a number of reliability concerns with logical constants in the Xilinx Virtex family. There are two main categories of logical constants: implicit and explicit logical constants. In all of the Virtex devices, the implicit logical constants are implemented using half latches, which in the most recent devices are several orders of magnitudes smaller than configuration bit cells. Explicit logical constants are implemented exclusively using constant LUTs in the Virtex-I and Virtex-II, and use a combination of constant LUTs and architectural posts to the ground plane in the Virtex-4. We have also presented mitigation methods and options for these devices. While SEUs in implicit and some types of explicit logical constants can cause data corrupt, the chance of failure from these components is now much smaller than it was in the Virtex-I device. Therefore, for many cases, mitigation might not be necessary, except under extremely high reliability situations.

  13. The effect of tou nong san on transplanted tumor growth in nude mice.

    PubMed

    Fang, Liang-Hua; Wang, Rui-Ping; Hu, Shou-You; Teng, Yu-Hao; Xie, Wei-Bing

    2015-01-01

    Tou Nong San (TNS) is a traditional Chinese medicinal decoction used to treat sores and carbuncles. It contains four herbal drugs and one animal medicine: Radix Astragaliseu Seu Hedysari, Angelica sinensis, Ligustici Chuanxiong, Spina Gleditsiae, and stir-baked Squama Manis. Previous studies have shown that it has anticancer effects. This report validates in vivo antitumor properties of TNS. The compounds contained in TNSE were confirmed by liquid chromatographmass spectrometer (LC-MS) analysis. The in vivo antitumor activity of TNS extract (TNSE) was tested by feeding it to athymic mice harboring a human colonic tumor subcutaneous xenograft. Toxicity was monitored by recording behavior and weight parameters. Seven compounds were detected in TNSE by LC-MS. TNSE was fed to athymic mice for 2 weeks. No adverse reactions were reported. Compared to the control group, administration of TNSE to tumor bearing mice significantly reduced both tumor weight and volume. The expressions of p-PI3K, p-AKT, p-mTOR, p-p70s6k1, VEGF, and CD31 were significantly reduced, the expression levels of cleaved Caspase-9 and cleaved Caspase-3 were significantly increased in the TNSE groups compared to the control group as determined by western blot and immunohistochemistry. TNSE produced anticolonic cancer effects and the underlying mechanisms involved inhibition of the PI3K/AKT signal transduction pathway, inhibition of angiogenesis, and promotion of apoptotic proteins. PMID:25788964

  14. Investigation and compensation of the nonlinear response in photomultiplier tubes for quantitative single-shot measurements.

    PubMed

    Knappe, C; Lindén, J; Abou Nada, F; Richter, M; Aldén, M

    2012-03-01

    A concept for time-sensitive optical detectors is described that shows how to confirm whether the detection device is operating in the linear response regime. By evaluating the recorded time decay of a thermographic phosphor, even weak saturation effects far from obvious situations can be identified and further related to either optical or electrical saturation. The concept has been validated by running a PMT detector close to saturation and exposing it to the optical signal decay of two different thermographic phosphors, La(2)O(2)S:Eu and CdWO(4). It was confirmed that short but intense light exposures at the beginning of an individual time decay influence the detector response for the rest of the decaying signal including temporal areas, where the anode current has dropped well below the manufacturer specified current limit. Such situations are common when applying, e.g., phosphor thermometry where it is necessary to retrieve the full decay curve from a single-shot event, i.e., standard techniques based on single-photon counting are omitted. Finally, means of compensation are introduced in order to facilitate the retrieval of useful information from the measurement data when operation in the non-linear response regime is inevitable. PMID:22462946

  15. Compendium of Current Single Event Effects for Candidate Spacecraft Electronics for NASA

    NASA Technical Reports Server (NTRS)

    O'Bryan, Martha V.; Label, Kenneth A.; Chen, Dakai; Campola, Michael J.; Casey, Megan C.; Lauenstein, Jean-Marie; Pellish, Jonathan A.; Ladbury, Raymond L.; Berg, Melanie D.

    2015-01-01

    NASA spacecraft are subjected to a harsh space environment that includes exposure to various types of ionizing radiation. The performance of electronic devices in a space radiation environment are often limited by their susceptibility to single event effects (SEE). Ground-based testing is used to evaluate candidate spacecraft electronics to determine risk to spaceflight applications. Interpreting the results of radiation testing of complex devices is and adequate understanding of the test condition is critical. Studies discussed herein were undertaken to establish the application-specific sensitivities of candidate spacecraft and emerging electronic devices to single-event upset (SEU), single-event latchup (SEL), single-event gate rupture (SEGR), single-event burnout (SEB), and single-event transient (SET). For total ionizing dose (TID) and displacement damage dose (DDD) results, see a companion paper submitted to the 2015 Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space Radiation Effects Conference (NSREC) Radiation Effects Data Workshop (REDW) entitled "compendium of Current Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA by M. Campola, et al.

  16. An experimental study on drugs for improving blood circulation and removing blood stasis in treating mild chronic hepatic damage.

    PubMed

    Xie, F; Li, X; Sun, K; Chu, Y; Cao, H; Chen, N; Wang, W; Liu, M; Liu, W; Mao, D

    2001-09-01

    Large and small doses of drugs for improving blood circulation and removing blood stasis were used in model rats to treat mild chronic hepatic damage induced by carbon tetrachloride (CCl4). The results show that large dose of Dang Gui ([symbol: see text] Radix Angelicae Sinensis) and Dan Shen ([symbol: see text] Radix Salviae Miltiorrhizae) (drugs for regulating blood flow) and small dose of Yu Jin ([symbol: see text] Radix Curcumae) and Niu Xi ([symbol: see text] Radix Achyranthis Bidentatae) (drugs for activating blood flow) can significantly elevate the activity of SOD (P < 0.05) and/or lower the T/K ratio, markedly reduce the MDA content (P < 0.05 or P < 0.01) and significantly decrease the activities of ALT and AST (P < 0.05 or P < 0.01), demonstrating that these drugs are effective in combating oxygen free radicals (OFR) in chronic liver damage. On the contrary, large dose of Tu Bie Chong ([symbol: see text] Eupolyphaga seu Steleophaga) and E Zhu ([symbol: see text] Rhizoma Curcumae) (drugs for removing blood stasis) tend to increase the ALT and AST (P < 0.05) activities. The results suggest that the synergism of elevation of the SOD activity and reduction of T/K ratio contributes to the action of drugs for improving blood circulation and removing blood stasis in combating the liver damage induced by CCl4. PMID:11789334

  17. An Integrative Method for Identifying the Over-Annotated Protein-Coding Genes in Microbial Genomes

    PubMed Central

    Yu, Jia-Feng; Xiao, Ke; Jiang, Dong-Ke; Guo, Jing; Wang, Ji-Hua; Sun, Xiao

    2011-01-01

    The falsely annotated protein-coding genes have been deemed one of the major causes accounting for the annotating errors in public databases. Although many filtering approaches have been designed for the over-annotated protein-coding genes, some are questionable due to the resultant increase in false negative. Furthermore, there is no webserver or software specifically devised for the problem of over-annotation. In this study, we propose an integrative algorithm for detecting the over-annotated protein-coding genes in microorganisms. Overall, an average accuracy of 99.94% is achieved over 61 microbial genomes. The extremely high accuracy indicates that the presented algorithm is efficient to differentiate the protein-coding genes from the non-coding open reading frames. Abundant analyses show that the predicting results are reliable and the integrative algorithm is robust and convenient. Our analysis also indicates that the over-annotated protein-coding genes can cause the false positive of horizontal gene transfers detection. The webserver of the proposed algorithm can be freely accessible from www.cbi.seu.edu.cn/RPGM. PMID:21903723

  18. Diagnosing anomalies of spacecraft for space maintenance and servicing

    NASA Astrophysics Data System (ADS)

    Lauriente, Michael; Rolincik, Mark; Koons, Harry C.; Gorney, David

    1994-01-01

    Very often servicing of satellites is necessary to replace components which are responsible for anomalous behavior of satellite operations due to adverse interactions with the natural space environment. A major difficulty with this diagnosis is that those responsible for diagnosing these anomalies do not have the tools to assess the role of the space environment causing the anomaly. To address this issue, we have under development a new rule-based, expert system for diagnosing spacecraft anomalies. The knowledge base consists of over two-hundred rules and provides links to historical and environmental databases. Environmental causes considered are bulk charging, single event upsets (SEU), surface charging, and total radiation dose. The system's driver translates forward chaining rules into a backward chaining sequence, prompting the user for information pertinent to the causes considered. When the user selects the novice mode, the system automatically gives detailed explanations and descriptions of terms and reasoning as the session progresses, in a sense teaching the user. As such it is an effective tutoring tool. The use of heuristics frees the user from searching through large amounts of irrelevant information and allows the user to input partial information (varying degrees of confidence in an answer) or 'unknown' to any question. The system is available on-line and uses C Language Integrated Production System (CLIPS), an expert shell developed by the NASA Johnson Space Center AI Laboratory in Houston.

  19. An Intelligent computer-aided tutoring system for diagnosing anomalies of spacecraft in operation

    NASA Technical Reports Server (NTRS)

    Rolincik, Mark; Lauriente, Michael; Koons, Harry C.; Gorney, David

    1993-01-01

    A new rule-based, expert system for diagnosing spacecraft anomalies is under development. The knowledge base consists of over two-hundred (200) rules and provides links to historical and environmental databases. Environmental causes considered are bulk charging, single event upsets (SEU), surface charging, and total radiation dose. The system's driver translates forward chaining rules into a backward chaining sequence, prompting the user for information pertinent to the causes considered. When the user selects the novice mode, the system automatically gives detailed explanations and descriptions of terms and reasoning as the session progresses, in a sense teaching the user. As such it is an effective tutoring tool. The use of heuristics frees the user from searching through large amounts of irrelevant information and allows the user to input partial information (varying degrees of confidence in an answer) or 'unknown' to any question. The system is available on-line and uses C Language Integrated Production System (CLIPS), an expert shell developed by the NASA Johnson Space Center AI Laboratory in Houston.

  20. An expert system for diagnosing environmentally induced spacecraft anomalies

    NASA Technical Reports Server (NTRS)

    Rolincik, Mark; Lauriente, Michael; Koons, Harry C.; Gorney, David

    1992-01-01

    A new rule-based, machine independent analytical tool was designed for diagnosing spacecraft anomalies using an expert system. Expert systems provide an effective method for saving knowledge, allow computers to sift through large amounts of data pinpointing significant parts, and most importantly, use heuristics in addition to algorithms, which allow approximate reasoning and inference and the ability to attack problems not rigidly defined. The knowledge base consists of over two-hundred (200) rules and provides links to historical and environmental databases. The environmental causes considered are bulk charging, single event upsets (SEU), surface charging, and total radiation dose. The system's driver translates forward chaining rules into a backward chaining sequence, prompting the user for information pertinent to the causes considered. The use of heuristics frees the user from searching through large amounts of irrelevant information and allows the user to input partial information (varying degrees of confidence in an answer) or 'unknown' to any question. The modularity of the expert system allows for easy updates and modifications. It not only provides scientists with needed risk analysis and confidence not found in algorithmic programs, but is also an effective learning tool, and the window implementation makes it very easy to use. The system currently runs on a Micro VAX II at Goddard Space Flight Center (GSFC). The inference engine used is NASA's C Language Integrated Production System (CLIPS).

  1. An on-line expert system for diagnosing environmentally induced spacecraft anomalies using CLIPS

    NASA Technical Reports Server (NTRS)

    Lauriente, Michael; Rolincik, Mark; Koons, Harry C; Gorney, David

    1993-01-01

    A new rule-based, expert system for diagnosing spacecraft anomalies is under development. The knowledge base consists of over two-hundred rules and provide links to historical and environmental databases. Environmental causes considered are bulk charging, single event upsets (SEU), surface charging, and total radiation dose. The system's driver translates forward chaining rules into a backward chaining sequence, prompting the user for information pertinent to the causes considered. The use of heuristics frees the user from searching through large amounts of irrelevant information (varying degrees of confidence in an answer) or 'unknown' to any question. The expert system not only provides scientists with needed risk analysis and confidence estimates not available in standard numerical models or databases, but it is also an effective learning tool. In addition, the architecture of the expert system allows easy additions to the knowledge base and the database. For example, new frames concerning orbital debris and ionospheric scintillation are being considered. The system currently runs on a MicroVAX and uses the C Language Integrated Production System (CLIPS).

  2. Use of SX Series Devices and IEEE 1149.1 JTAG Circuitry. Revised

    NASA Technical Reports Server (NTRS)

    Katz, Richard B.; Wang, J. J.

    1998-01-01

    This report summarizes the use of SX series devices and their JTAG 1149.1 circuitry. 'JTAG' circuitry was originally designed to standardize testing of boards via a simple control port interface electrically without having to use devices such as a bed of nails tester. JTAG is also used for other functions such as executing built-in-test sequences, identifying devices, or, through custom instructions, other functions designed in by the chip designer. The JTAG circuitry is designed for test only; it has no functional use in the integrated circuit during normal operations. The JTAG circuitry and the mode of the device is controlled by a circuit block known as the 'TAP controller,' which is a sixteen-state state machine along with various registers. The controller is normally in an operational state known as TEST-LOGIC-RESET. In this state, the device is held in a fully functional, operating mode. However, a Single Event Upset (SEU) may remove the TAP controller from this state, causing a loss of control of the integrated circuit, unless certain precautions are taken, such as grounding the optional JTAG TRST signal.

  3. A Re-programmable Platform for Dynamic Burn-in Test of Xilinx Virtexll 3000 FPGA for Military and Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Roosta, Ramin; Wang, Xinchen; Sadigursky, Michael; Tracton, Phil

    2004-01-01

    Field Programmable Gate Arrays (FPGA) have played increasingly important roles in military and aerospace applications. Xilinx SRAM-based FPGAs have been extensively used in commercial applications. They have been used less frequently in space flight applications due to their susceptibility to single-event upsets. Reliability of these devices in space applications is a concern that has not been addressed. The objective of this project is to design a fully programmable hardware/software platform that allows (but is not limited to) comprehensive static/dynamic burn-in test of Virtex-II 3000 FPGAs, at speed test and SEU test. Conventional methods test very few discrete AC parameters (primarily switching) of a given integrated circuit. This approach will test any possible configuration of the FPGA and any associated performance parameters. It allows complete or partial re-programming of the FPGA and verification of the program by using read back followed by dynamic test. Designers have full control over which functional elements of the FPGA to stress. They can completely simulate all possible types of configurations/functions. Another benefit of this platform is that it allows collecting information on elevation of the junction temperature as a function of gate utilization, operating frequency and functionality. A software tool has been implemented to demonstrate the various features of the system. The software consists of three major parts: the parallel interface driver, main system procedure and a graphical user interface (GUI).

  4. Fluorescence excitation and propagation through brain phantom gelatins: measurements and potential applications

    NASA Astrophysics Data System (ADS)

    Allison, S. W.; Gillies, G. T.

    2010-08-01

    We have investigated the utility of 0.6% agarose gels as surrogate materials for brain tissues in optical propagation studies for possible diagnostic and therapeutic applications. Centimeter-scale layers of the gel exhibited a Beer's law attenuation factor, δ, of ≈0.2 mm-1 for incident illumination via a pulsed LED (100 Hz) at 405 nm. This result was different by only about a factor of 3 from the effective penetration depth at similar wavelengths through in vitro samples of the gray (cortical) matter of human brain, as measured by others. Then, films of the thermographic phosphors La2O2S:Eu, Mg4FGeO6:Mn, YAG:Cr and variants of the latter were formed on aluminum substrates and the fluorescence of these samples was stimulated and observed through layers of the gel up to 4 cm thick. In all cases, the fluorescence was easily excited and distinguishable above the background. The results demonstrate that this gel might serve as an inexpensive and robust test bed for exploratory studies of neurological modalities involving propagation of optical signals within brain tissues.

  5. Cometas: Das Lendas aos Fatos

    NASA Astrophysics Data System (ADS)

    Voelzke, M. R.

    O descobrimento de cometas, devido ao seu aparecimento espetacular, tem registro nas mais antigas culturas humanas. A primeira referência situa-se no ano de 1095 antes de Cristo [a.C.; HO; HO, 1962]. A quantidade de registros de descobrimentos cometários, principalmente provenientes do território chinês em particular e do oriente em geral, aumentou gradualmente a partir do quarto século depois de Cristo (d.C.). É de origem chinesa a primeira referência ao cometa P/Halley no ano de 240 a.C. [VOELZKE, 1993]. Com o desenvolvimento da astronomia relativamente às técnicas observacionais os descobrimentos bem como as observações cometárias aumentaram sensivelmente a partir do século XVII, sendo que a partir do século XIX um novo incremento ocorreu devido ao emprego da fotografia e a resultante melhora de sensibilidade na observação.

  6. Evaluation of commercial ADC radiation tolerance for accelerator experiments

    NASA Astrophysics Data System (ADS)

    Chen, K.; Chen, H.; Kierstead, J.; Takai, H.; Rescia, S.; Hu, X.; Xu, H.; Mead, J.; Lanni, F.; Minelli, M.

    2015-08-01

    Electronic components used in high energy physics experiments are subjected to a radiation background composed of high energy hadrons, mesons and photons. These particles can induce permanent and transient effects that affect the normal device operation. Ionizing dose and displacement damage can cause chronic damage which disable the device permanently. Transient effects or single event effects are in general recoverable with time intervals that depend on the nature of the failure. The magnitude of these effects is technology dependent with feature size being one of the key parameters. Analog to digital converters are components that are frequently used in detector front end electronics, generally placed as close as possible to the sensing elements to maximize signal fidelity. We report on the development of a technique for testing analog to digital converters for radiation effects, in particular for single event effects. A total of seventeen commercial ADCs were evaluated for ionizing dose tolerance and extensive SEU measurements performed on a twelve and fourteen bit ADCs. Mitigation strategies for single event effects (SEE) are discussed for their use in the large hadron collider environment.

  7. MCNP6 fragmentation of light nuclei at intermediate energies

    NASA Astrophysics Data System (ADS)

    Mashnik, Stepan G.; Kerby, Leslie M.

    2014-11-01

    Fragmentation reactions induced on light target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the latest Los Alamos Monte Carlo transport code MCNP6 and with its cascade-exciton model (CEM) and Los Alamos version of the quark-gluon string model (LAQGSM) event generators, version 03.03, used as stand-alone codes. Such reactions are involved in different applications, like cosmic-ray-induced single event upsets (SEU's), radiation protection, and cancer therapy with proton and ion beams, among others; therefore, it is important that MCNP6 simulates them as well as possible. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. Both CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  8. [Enterobius vermicularis in preschool children from a suburban area in San Félix, Bolívar State, Venezuela].

    PubMed

    Requena, Ixora; Jiménez, Yolimar; Rodríguez, Natacha; Sandoval, Maria; Alcala, Frannegy; Blanco, Ytalia; Devera, Rodolfo

    2007-09-01

    To determine the enterobiosis prevalence in preschool children, a study was carried out from may-july 2003, in the SEU "Teresa de la Parra" in San Félix, Bolívar State, Venezuela. Three samples from the perianal region were obtained from every child, by applying the Graham method, and one sample was obtained of the subungucal deposit by scraping and cutting off their finger nails. These samples were preserved in 10% formol and processed by the formol-ether method. Also, a stool sample was collected and analyzed by direct examination and the formol-ether method. The prevalence of Enterobius vermicularis was 45.8% (27/59). No differences in relation to age (chi2 = 1.23 d. f. = 2) and sex (p > 0.05) were observed between the infected children. The eggs E. vermicularis were not observed in the 59 samples of subungueal deposits. In conclusion, although the enterobiosis prevalence was high, as determined by the Graham method, a relationship could not be found between E. vermicularis in the scotch tape and the finger nail samples of the children evaluated. PMID:17853787

  9. SPi User Manual V0.1

    SciTech Connect

    Trimpl, M.; Yarema, R.; Newcomer, M.; Dressnandt, N.; Villani, G.; Weber, M.; Holt, R.; /Rutherford

    2011-05-01

    This document describes the Serial Powering Interface (SPi) ASIC. SPi is a general purpose ASIC prototype designed for use in serial powering of silicon detector instrumentation. This description is written as a user manual to aid application, not as a design description. SPi is a generic custom ASIC, manufactured in 0.25 {mu}m CMOS by TSMC, to interface between a constant current source and silicon detector read-out chips. There is no SEU (single event upset) protection, but most (not all) components are radiation tolerant design. An operating voltage of 1.2 to 2.5 volts and other design features make the IC suitable for a variety of serial powering architectures and ROICs. It should be noted that the device is likely to be a prototype for demonstration rather than a product for inclusion in a detector. The next design(s), SPin, are likely to be designed for a specific application (eg SLHC). The component includes: (1) Seven bi-directional LVDS-like buffers for high data rate links to/from the read-out chips. These are AC coupled (series capacitor) off-chip for DC level conversion; (2) A programmable internal programmable shunt regulator to provide a defined voltage to readout chips when linked in a serial powering chain; (3) A programmable internal shunt regulator control circuit for external transistor control; (4) Shunt current measurement (for internal shunt regulator); (5) A programmable internal shunt regulator current alarm; and (6) Two programmable linear regulators.

  10. Non-volatile, high density, high speed, Micromagnet-Hall effect Random Access Memory (MHRAM)

    NASA Technical Reports Server (NTRS)

    Wu, Jiin C.; Katti, Romney R.; Stadler, Henry L.

    1991-01-01

    The micromagnetic Hall effect random access memory (MHRAM) has the potential of replacing ROMs, EPROMs, EEPROMs, and SRAMs because of its ability to achieve non-volatility, radiation hardness, high density, and fast access times, simultaneously. Information is stored magnetically in small magnetic elements (micromagnets), allowing unlimited data retention time, unlimited numbers of rewrite cycles, and inherent radiation hardness and SEU immunity, making the MHRAM suitable for ground based as well as spaceflight applications. The MHRAM device design is not affected by areal property fluctuations in the micromagnet, so high operating margins and high yield can be achieved in large scale integrated circuit (IC) fabrication. The MHRAM has short access times (less than 100 nsec). Write access time is short because on-chip transistors are used to gate current quickly, and magnetization reversal in the micromagnet can occur in a matter of a few nanoseconds. Read access time is short because the high electron mobility sensor (InAs or InSb) produces a large signal voltage in response to the fringing magnetic field from the micromagnet. High storage density is achieved since a unit cell consists only of two transistors and one micromagnet Hall effect element. By comparison, a DRAM unit cell has one transistor and one capacitor, and a SRAM unit cell has six transistors.

  11. Virtex-II Pro SEE Test Methods and Results

    NASA Technical Reports Server (NTRS)

    Petrick, David; Powell, Wesley; Howard, James W., Jr.; LaBel, Kenneth A.

    2004-01-01

    The objective of this coarse Single Event Effect (SEE) test is to determine the suitability of the commercial Virtex-II Pro family for use in spaceflight applications. To this end, this test is primarily intended to determine any Singe Event Latchup (SEL) susceptibilities for these devices. Secondly, this test is intended to measure the level of Single Event Upset (SEU) susceptibilities and in a general sense where they occur. The coarse SEE test was performed on a commercial XC2VP7 device, a relatively small single processor version of the Virtex-II Pro. As the XC2VP7 shares the same functional block design and fabrication process with the larger Virtex-II Pro devices, the results of this test should also be applicable to the larger devices. The XC2VP7 device was tested on a commercial Virtex-II Pro development board. The testing was performed at the Cyclotron laboratories at Texas A&M and Michigan State Universities using ions of varying energy levels and fluences.

  12. Low energy CMOS for space applications

    NASA Astrophysics Data System (ADS)

    Panwar, Ramesh; Alkalaj, Leon

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  13. Bimolecular fluorescence complementation (BiFC) assay for protein-protein interaction in onion cells using the helios gene gun.

    PubMed

    Hollender, Courtney A; Liu, Zhongchi

    2010-01-01

    Investigation of gene function in diverse organisms relies on knowledge of how the gene products interact with each other in their normal cellular environment. The Bimolecular Fluorescence Complementation (BiFC) Assay(1) allows researchers to visualize protein-protein interactions in living cells and has become an essential research tool. This assay is based on the facilitated association of two fragments of a fluorescent protein (GFP) that are each fused to a potential interacting protein partner. The interaction of the two protein partners would facilitate the association of the N-terminal and C-terminal fragment of GFP, leading to fluorescence. For plant researchers, onion epidermal cells are an ideal experimental system for conducting the BiFC assay because of the ease in obtaining and preparing onion tissues and the direct visualization of fluorescence with minimal background fluorescence. The Helios Gene Gun (BioRad) is commonly used for bombarding plasmid DNA into onion cells. We demonstrate the use of Helios Gene Gun to introduce plasmid constructs for two interacting Arabidopsis thaliana transcription factors, SEUSS (SEU) and LEUNIG HOMOLOG (LUH)(2) and the visualization of their interactions mediated by BiFC in onion epidermal cells. PMID:20567209

  14. Multibeam Mapping of the West Andaman Fault, NW Sumatra Fault, Andaman Volcanic Arc and Their Tectonic and Magmatic Implications

    NASA Astrophysics Data System (ADS)

    Kattoju, K. A.; Mudholkar, A. V.; Murty, G.; Vadakkeyakath, Y.; Singh, S. C.; Kiranmai, S.; Moeremans, R.

    2012-12-01

    West Andaman Fault (WAF) is a major structural feature in the Andaman Offshore region that plays an important role in modulating the strain partitioning within the Andaman Sea, well known for its complex tectonics and seismic hazard potential. However, detailed configuration of the WAF and its interaction with the Sumatra fault system in the Andaman sector are not well understood. Here we present near complete coverage of about 800 km long section of the WAF with special emphasis on the zone of confluence of the WAF and the Sumatra Fault systems, and the adjacent volcanic arc in the offshore region of the Great Nicobar Island. We have examined the fault system, and the volcanic arc feature by combining the newly acquired multibeam bathymetry data with the available data northwest of Sumatra. New multibeam map revealed a pattern of faults that are formed in the region of joining of the Seulimeum (SEU) and Aceh strands (AS) of the Sumatra fault with the WAF off Great Nicobar Island. Sandwiched between these faults, at this location, is a 50 km long and 7 km wide conspicuous NS elongated block that rises to 500 m from an adjacent seafloor of about 2000 m. The surface of the block has a westward dipping topographic fabric. Serpentinites were recovered from the eastern cliff of this block, suggestive of mantle origin. A deformed zone with corrugated surface is documented southeast of this elongated block at water depth ranging from 1000 to 1500 m. The mantle block and the deformed zone are bifurcated by a fault, which might be a branch of the WAF. Further south the expression of the Sumatra platform, northern boundary of the Aceh basin pinching out to WAF, extension of the SEU, AS strands towards south, and the northern limit of Weh basin are observed. The other prominent feature that is documented for the first time is the expression of the Andaman volcanic arc. Twenty-three submarine volcanoes of varying sizes have been mapped between 6°30‧N to 8°15‧N. Magnetic

  15. What Reliability Engineers Should Know about Space Radiation Effects

    NASA Technical Reports Server (NTRS)

    DiBari, Rebecca

    2013-01-01

    current of a nearby Thermal Electric Cooler (turning the TEC into a heater). The elevated temperature caused the PIN diode to anneal and the device to recover. It was by lot qualification testing that NEAR knew the diode would recover when annealed. This paper will look at these effects on a variety of devices in a variety of applications. Single Event Effects (SEE): (1) In contrast to TID and displacement damage, Single Event Effects (SEE) resemble random failures. SEE modes can range from changes in device logic (single-event upset, or SEU). temporary disturbances (single-event transient) to catastrophic effects such as the destructive SEE modes, single-event latchup (SEL). single-event gate rupture (SEGR) and single-event burnout (SEB) (2) The consequences of nondestructive SEE modes such as SEU and SET depend critically on their application--and may range from trivial nuisance errors to catastrophic loss of mission. It is critical not just to ensure that potentially susceptible devices are well characterized for their susceptibility, but also to work with design engineers to understand the implications of each error mode. -For destructive SEE, the predominant risk mitigation strategy is to avoid susceptible parts, or if that is not possible. to avoid conditions under which the part may be susceptible. Destructive SEE mechanisms are often not well understood, and testing is slow and expensive, making rate prediction very challenging. (3) Because the consequences of radiation failure and degradation modes depend so critically on the application as well as the component technology, it is essential that radiation, component. design and system engineers work togetherpreferably starting early in the program to ensure critical applications are addressed in time to optimize the probability of mission success.

  16. Non-radiation hardened microprocessors in space-based remote sensing systems

    NASA Astrophysics Data System (ADS)

    DeCoursey, R.; Melton, Ryan; Estes, Robert R., Jr.

    2006-09-01

    normal Single Event Upset (SEU) and Single Event Latch-up (SEL) rates. Although less significant, spacecraft flying in the area around the poles experience similar upsets. Finally, powerful solar proton events in the range of 10MeV/10pfu to 100MeV/1pfu as are forecasted and tracked by NOAA's Space Environment Center in Colorado can result in SingleEvent Upset (SEU), Single Event Latch-up (SEL) and permanent failures such as Single Event Gate Rupture (SEGR) in some technologies. (Galactic Cosmic Rays (GCRs) are another source, especially for gate rupture) CALIPSO mitigates common radiation concerns in its data handling through the use of redundant processors, radiation-hardened Application Specific Integrated Circuits (ASIC), hardware-based Error Detection and Correction (EDAC), processor and memory scrubbing, redundant boot code and mirrored files. After presenting a system overview this paper will expand on each of these strategies. Where applicable, related on-orbit data collected since the CALIPSO initial boot on May 4, 2006 will be noted.

  17. Non Radiation Hardened Microprocessors in Spaced Based Remote Sensing Systems

    NASA Technical Reports Server (NTRS)

    Decoursey, Robert J.; Estes, Robert F.; Melton, Ryan

    2006-01-01

    (SEU) and Single Event Latch-up (SEL) rates. Although less significant, spacecraft flying in the area around the poles experience similar upsets. Finally, powerful solar proton events in the range of 10MeV/10pfu to 100MeV/1pfu as are forecasted and tracked by NOAA's Space Environment Center in Colorado can result in Single Event Upset (SEU), Single Event Latch-up (SEL) and permanent failures such as Single Event Gate Rupture (SEGR) in some technologies. (Galactic Cosmic Rays (GCRs) are another source, especially for gate rupture) CALIPSO mitigates common radiation concerns in its data handling through the use of redundant processors, radiation-hardened Application Specific Integrated Circuits (ASIC), hardware-based Error Detection and Correction (EDAC), processor and memory scrubbing, redundant boot code and mirrored files. After presenting a system overview this paper will expand on each of these strategies. Where applicable, related on-orbit data collected since the CALIPSO initial boot on May 4, 2006 will be noted.

  18. The North Polar Layered Deposits on Mars: The Internal Layering of Gemina Lingula and Implications for Ice Flow

    NASA Astrophysics Data System (ADS)

    Karlsson, Nanna B.; Holt, John W.; Hindmarsh, Richard C. A.; Choudhary, Prateek

    2010-05-01

    The North Polar Layered Deposits (NPLD) is one of the largest reservoirs of surface water on Mars and, via an active exchange of water vapour with the atmosphere, it plays an important role in the Martian climate. The impact of ice flow on the overall shape of the NPLD is still widely debated. A study by Winebrenner et al. (2008) found evidence for relict flow lines in the southernmost part of the NPLD called Gemina Lingula (GL). Other studies have concluded that the upper part of the NPLD shows no evidence of flow (Fishbaugh and Hvidberg, 2006) and that surface mass balance alone can produce the topography (Greve et al., 2004 and Greve and Mahajan, 2005) . This paper presents results from an analysis of radar data from the SHARAD (SHallow RADar) instrument on board NASA's Mars Reconnaissance Orbiter. The SHARAD instrument operates with a 20MHz centre frequency and a 10MHz bandwidth and one of its primary mission goals is to map the state and distribution of water on Mars. For more details on the SHARAD instrument please refer to Seu et al. (2007). In the SHARAD data we identified and mapped six internal horizons from over 80 radar lines retrieved over GL. All horizons were easily identifiable in the majority of the data and were on average present in over 80% of the radar data considered. The observed layers were then compared to modelled layers from a 3D ice flow model. The model uses a smoothed surface topography, where troughs and scarps have been filled in, and assumes that the shape and the mass balance of the NPLD are constant in time. The shape of the internal layers are then calculated as they would appear in a flowing ice cap given those parameters. More information on the model can be found in Hindmarsh et al. (2009). The overall fit between modelled and observed layers is reasonably good, but the goodness of the fit varies both between the different horizons and the different regions of GL. Horizons in the upper part of the ice fit less well than

  19. Variable Depth Bragg Peak Method for Single Event Effects Testing

    NASA Technical Reports Server (NTRS)

    Buchner, S.; Kanyogoro, N.; Foster, C.; O'Neill, P.

    2011-01-01

    Traditionally, accelerator SEE testing is accomplished by removing the tops of packages so that the IC chips are accessible to heavy ions. However, ICs in some advanced packages cannot be de-lidded so a different approach is used that involves grinding and/or chemically etching away part of the package and the chip from the back side. The parts are then tested from the back side with ions having sufficient range to reach the sensitive volume. More recently, the entire silicon substrate in an SOI/SRAM was removed, making it possible to use low-energy ions with shorter ranges. Where removal of part of the package is not possible, facilities at Michigan State, NASA Space Radiation Laboratory, GANIL (France) and GSI (Germany) offer high-energy heavy ions with long ranges so that the ions can reach the devices' sensitive volumes without much change in the LET. Unfortunately, a run will typically involve only one ion species having a single energy and LET due to the long time it takes to tune a new energy. The Variable Depth Bragg Peak (VDBP) method is similar to the above method in that it involves the use of high-energy heavy ions that are able to pass through the packaging material and reach the device, obviating the need to remove the package. However, the method provides a broad range of LETs from a single ion by inserting degraders in the beam that modify the ion energy and, therefore, the LET. The crux of the method involves establishing a fiduciary point for degrader thickness, i.e., where the Bragg peak is located precisely at the sensitive volume in the device, for which the measured SEU cross-section and the ion LET are both also maxima and can be calculated using a Monte-Carlo program, TRIM. Once the fiduciary point has been established, calibrated high density polyethylene (HDPE) degraders are inserted into or removed from the beam to vary the ion LET at the device in a known manner. After each change of degrader thickness, the SEU cross-section is measured

  20. Are Current SEE Test Procedures Adequate for Modern Devices and Electronics Technologies?

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Cohn, Lewis M.; Ladbury, Ray

    2008-01-01

    Believe it or not, this has been a simplistic look at starting a checklist for SEE testing. Given a memory that has 68 operating modes, when a SEU occurs that changes the mode, just how do you determine what's going on? Laser and microbeam tests can help, but not easily for modern packaged devices. Expanding this approach to other more complex devices such as ADCs or processors as well as analog devices should be considered. The recommendation is to use the existing text standards as the starting point. Just make your own checklist for the device/technology/issues being considered. At HEART 2007, we presented some of the burgeoning challenges associated with single event effect(SEE) testing of modern commercial memories: a) Package, device complexity, test fixture, and data analysis issues were discussed; b) "Complete" SEE Characterization would take 15 years; c) Qualification test costs have a greater than 4 times increase over the last decade. In this talk, we continue to explore the roles of technology with an emphasis on the existing SEE Test Procedures and some of the concerns related to modern devices. The primary objective of the briefing is to provide some overarching guidance concerning the many considerations involved in the formulation of a SEE test plan provided in a " Checklist" format.we note that there is no such thing as a complete check list and that the best approach is to develop a flexible test plan that takes into account the device type and functions, the device technology, circuit and package design, and, of course, test facility and beam characteristics.

  1. Ionizing Radiation Environment on the International Space Station: Performance vs. Expectations for Avionics and Material

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Boeder, Paul A.; Pankop, Courtney; Reddell, Brandon

    2005-01-01

    The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported. Detailed consideration of the effects of both the natural and induced ionizing radiation environment during ISS design, development, and flight operations has produced a safe, efficient manned space platform that is largely immune to deleterious effects of the LEO ionizing radiation environment. The assumption of a small shielding mass for purposes of design and verification has been shown to be a valid worst-case approximation approach to design for reliability, though predicted dependences of single event effect (SEE) effects on latitude, longitude, SEP events, and spacecraft structural shielding mass are not observed. The Figure of Merit (FOM) method over predicts the rate for median shielding masses of about 10g/cm(exp 2) by only a factor of 3, while the Scott Effective Flux Approach (SEFA) method overestimated by about one order of magnitude as expected. The Integral Rectangular Parallelepiped (IRPP), SEFA, and FOM methods for estimating on-orbit (Single Event Upsets) SEU rates all utilize some version of the CREME-96 treatment of energetic particle interaction with structural shielding, which has been shown to underestimate the production of secondary particles in heavily shielded manned spacecraft. The need for more work directed to development of a practical understanding of secondary particle production in massive structural shielding for SEE design and verification is indicated. In contrast, total dose estimates using CAD based shielding mass distributions functions and the Shieldose Code provided a reasonable accurate estimate of accumulated dose in Grays internal to the ISS pressurized elements, albeit as a result of using worst-on-worst case assumptions (500 km altitude x 2) that compensate for ignoring both GCR and secondary particle

  2. Molecular Types and Genetic Profiles of Staphylococcus aureus Strains Isolated from Bovine Intramammary Infections and Extramammary Sites▿

    PubMed Central

    Haveri, M.; Hovinen, M.; Roslöf, A.; Pyörälä, S.

    2008-01-01

    Staphylococcus aureus isolates collected from sites of intramammary infection during a 10-month period and from extramammary sites (dairy cow teat skin, teat canals, and skin lesions; milking liners; and hands and nostrils of milking personnel) at two separately managed Finnish dairy herd establishments were analyzed to study the sources and reservoirs of bovine S. aureus intramammary infection. Selected isolates were subjected to pulsed-field gel electrophoresis (PFGE) typing and PCR analysis for genes encoding hemolysins (hla to hlg), leukocidins (lukED and lukM), superantigens (sea, sec, sed, seg to seo, seu, and tst), adhesins (fnbA and fnbB), and penicillin and methicillin resistance (blaZ and mecA). S. aureus was found throughout the herds in 94% of the cows. Nine PFGE types were found, with the herds each having their own predominant type and sharing one type. The degree of diversity of PFGE types in herd II, which integrated foreign heifers, was higher than that in herd I. For both herds, the majority of the PFGE-typed isolates both from milk and from extramammary sites represented the predominant PFGE types. In isolates from herd I, the most prevalent genes were hla-hlg, lukED, and fnbA; in those from herd II, they were hla, hld, hlg, lukED, and fnbA. The other genes were pulsotype linked within the herds. The predominant PFGE types carried both fnbA and fnbB; only fnbA was detected in the other PFGE types. No connection between specific virulence genes and the origins of isolates was found. The results suggest that for the two herds, most S. aureus isolates from extramammary sites were indistinguishable from the isolates infecting the mammary gland and that those sites can thus act as origins and reservoirs of intramammary infections. However, contamination in the opposite direction cannot be excluded. PMID:18799704

  3. A eficiência de formação estelar em Musca

    NASA Astrophysics Data System (ADS)

    Hickel, G. R.; Vilas-Boas, J. W. S.; Roberto, A. J.., Jr.; Khan, R. P.

    2003-08-01

    Apresentamos os resultados de um survey no infravermelho próximo (bandas J e H), executado no Laboratório Nacional de Astrofísica, na direção da nuvem escura em forma de filamento de Musca (observamos ao longo de todo o filamento, além de todas as fontes pontuais IRAS e/ou fontes ROSAT brilhantes a uma distância de 2o da nuvem). Nosso objetivo é determinar a eficiência de formação estelar para esta nuvem escura (massa de estrelas formadas/massa da nuvem), procurando por objetos estelares jovens de pequena massa no seu interior e/ou evoluídos o suficiente para estarem afastados do local de nascimento, mas ainda mostrando características de objetos pré-seqüência principal como emissão de raios-X e excesso de emissão no infravermelho próximo. Este survey não estabeleceu nenhum viés na seleção de fontes pontuais IRAS ou fontes ROSAT, uma vez que a imensa maioria das fontes pontuais IRAS nesta região têm qualidade de fluxo ruim. Os candidatos a objetos estelares jovens foram selecionados pelo excesso no índice de cor (J-H), descontados os efeitos da extinção interestelar na linha de visada, determinada através da emissão estendida no infravermelho distante (IRAS). Estimativas de massa foram feitas para estes candidatos, através da relação massa-luminosidade, para calcular a eficiência de formação estelar de Musca.

  4. Incorporando a variabilidade no processo de identificação do modelo de máximo global no Grade of Membership (GoM): considerações metodológicas

    PubMed Central

    Guedes, Gilvan Ramalho; Siviero, Pamila Cristina Lima; Caetano, André Junqueira; Machado, Carla Jorge; Brondízio, Eduardo

    2012-01-01

    A disponibilidade de bases de dados cada vez mais complexas e multidimensionais é um dos principais motivadores para o aumento do número de estudos que utilizam análises multivariadas baseadas em lógica de conjuntos nebulosos. Apesar da disseminação do método Grade of Membership nos trabalhos empíricos brasileiros da área de ciências sociais e saúde, questões relativas à identificabilidade e estabilidade dos parâmetros finais estimados pelo programa GoM 3.4 não foram suficientemente aprofundadas. Dada a relevância de se obterem parâmetros únicos e estáveis, Guedes et al. (2010) propuseram um procedimento empírico para localizar um modelo de máximo global (MG) com parâmetros estáveis. Entretanto, seu localizador de MG não incorpora qualquer medida de variabilidade. Neste artigo, tal limitação é contornada por meio da utilização de uma estatística de ponderação – Máximo Global Ponderado (MGP) – semelhante ao coeficiente de variação. Esse indicador busca não penalizar de forma desproporcional situações nas quais os desvios médios, apesar de diferentes de zero, são muito pequenos. Apresentam-se evidências de que o localizador MGP reduz a distância do modelo identificado à real estrutura latente dos dados em análise, quando comparados ao modelo identificado pelo localizador não ponderado, MG. PMID:23293402

  5. OV-Wav: um novo pacote para análise multiescalar em astronomia

    NASA Astrophysics Data System (ADS)

    Pereira, D. N. E.; Rabaça, C. R.

    2003-08-01

    Wavelets e outras formas de análise multiescalar têm sido amplamente empregadas em diversas áreas do conhecimento, sendo reconhecidamente superiores a técnicas mais tradicionais, como as análises de Fourier e de Gabor, em certas aplicações. Embora a teoria dos wavelets tenha começado a ser elaborada há quase trinta anos, seu impacto no estudo de imagens astronômicas tem sido pequeno até bem recentemente. Apresentamos um conjunto de programas desenvolvidos ao longo dos últimos três anos no Observatório do Valongo/UFRJ que possibilitam aplicar essa poderosa ferramenta a problemas comuns em astronomia, como a remoção de ruído, a detecção hierárquica de fontes e a modelagem de objetos com perfis de brilho arbitrários em condições não ideais. Este pacote, desenvolvido para execução em plataforma IDL, teve sua primeira versão concluída recentemente e está sendo disponibilizado à comunidade científica de forma aberta. Mostramos também resultados de testes controlados ao quais submetemos os programas, com a sua aplicação a imagens artificiais, com resultados satisfatórios. Algumas aplicações astrofísicas foram estudadas com o uso do pacote, em caráter experimental, incluindo a análise da componente de luz difusa em grupos compactos de galáxias de Hickson e o estudo de subestruturas de nebulosas planetárias no espaço multiescalar.

  6. A framework for energy use indicators and their reporting in life cycle assessment.

    PubMed

    Arvidsson, Rickard; Svanström, Magdalena

    2016-07-01

    Energy use is a common impact category in life cycle assessment (LCA). Many different energy use indicators are used in LCA studies, accounting for energy use in different ways. Often, however, the choice behind which energy use indicator is applied is poorly described and motivated. To contribute to a more purposeful selection of energy use indicators and to ensure consistent and transparent reporting of energy use in LCA, a general framework for energy use indicator construction and reporting in LCA studies will be presented in this article. The framework differentiates between 1) renewable and nonrenewable energies, 2) primary and secondary energies, and 3) energy intended for energy purposes versus energy intended for material purposes. This framework is described both graphically and mathematically. Furthermore, the framework is illustrated through application to a number of energy use indicators that are frequently used in LCA studies: cumulative energy demand (CED), nonrenewable cumulative energy demand (NRCED), fossil energy use (FEU), primary fossil energy use (PFEU), and secondary energy use (SEU). To illustrate how the application of different energy use indicators may lead to different results, cradle-to-gate energy use of the bionanomaterial cellulose nanofibrils (CNF) is assessed using 5 different indicators and showing a factor of 3 differences between the highest and lowest results. The relevance of different energy use indicators to different actors and contexts will be discussed, and further developments of the framework are then suggested. Integr Environ Assess Manag 2016;12:429-436. © 2015 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:26551582

  7. [J.E. GILIBERT'S DIDACTIC VIEWS].

    PubMed

    Grębecka, Wanda

    2015-01-01

    When J.E. Gilibert was nominated to head the Chair of Natural History in Vilnius, his task was to introduce education with European standards. He was aware of the potential of his students and the level of their secondary school education. At that time (1781), no textbooks were available in Poland presenting knowledge of botany; the first was written in 1785. Teachers were using assorted, sometimes hardly practical materials, such as excerpts from Roman authors. Gilibert was familiar with this situation from his experience in Grodno, where he had taught for 6 years. At best, learners, i.e. prospective students, were using guidebooks for farmers by Ch. Kluk. This state of affairs was essentially in accordance with original plans of the National Educational Committee, which intended a very practical course of Natural History. The Chair in Vilnius was founded to implement university level education; and Gilibert dedicated a lot of time to didactic recommendations which would help students to develop the competence of botanists capable of studying European literature and communicating with international scientists. This presentation focuses on two important documents. The first one, Prospectus praelectionum cursus Historiae Naturalis. Ad usum Alumnorum Alma uniwersitatis Vilnensis, containing the curriculum of Natural History in Vilnius, will be analyzed from the point of view of its philosophical, epistemic and practical significance. The other one, Exercitium botanicum in schola principe universitatis Vilnensis habendum die mensie Julii anno 1782 seu enumaratio metodica plantarum, will be of interest from the point of view of various methodical comments regarding other works by Gilibert. PMID:26445746

  8. Clementine Sensor Processing System

    NASA Technical Reports Server (NTRS)

    Feldstein, A. A.

    1993-01-01

    The design of the DSPSE Satellite Controller (DSC) is baselined as a single-string satellite controller. The DSC performs two main functions: health and maintenance of the spacecraft; and image capture, storage, and playback. The DSC contains two processors: a radiation-hardened Mil-Std-1750, and a commercial R3000. The Mil-Std-1750 processor performs all housekeeping operations, while the R3000 is mainly used to perform the image processing functions associated with the navigation functions, as well as performing various experiments. The DSC also contains a data handling unit (DHU) used to interface to various spacecraft imaging sensors and to capture, compress, and store selected images onto the solid-state data recorder. The development of the DSC evolved from several key requirements; the DSPSE satellite was to do the following: (1) have a radiation-hardened spacecraft control system and be immune to single-event upsets (SEU's); (2) use an R3000-based processor to run the star tracker software that was developed by SDIO (due to schedule and cost constraints, there was no time to port the software to a radiation-hardened processor); and (3) fly a commercial processor to verify its suitability for use in a space environment. In order to enhance the DSC reliability, the system was designed with multiple processing paths. These multiple processing paths provide for greater tolerance to various component failures. The DSC was designed so that all housekeeping processing functions are performed by either the Mil-Std-1750 processor or the R3000 processor. The image capture and storage is performed either by the DHU or the R3000 processor.

  9. MOPITT Mechanisms 16 Years In-Orbit Operation on TERRA

    NASA Technical Reports Server (NTRS)

    Gibson, Andrew S.; Nichitiu, Florian; Caldwell, Dwight

    2016-01-01

    and SEU effects on accelerometers are also discussed.

  10. The history of the parathyroid surgery.

    PubMed

    Toneto, Marcelo Garcia; Prill, Shandi; Debon, Leticia Manoel; Furlan, Fernando Zucuni; Steffen, Nedio

    2016-01-01

    The authors conducted a review of the major aspects of progression of knowledge about the surgical treatment of hyperparathyroidism. Through literature review, we analyzed articles on the history of the evolution of anatomical, physiological, pathological and surgical knowledge of the parathyroid glands. Because of their unique anatomical features, the parathyroid glands were the last of the endocrine glands to be discovered, which greatly hindered proper treatment until the first decades of the twentieth century. Technological developments in the last 30 years greatly facilitated the location of the glands and hyperparathyroidism surgery. However, an experienced and dedicated surgeon is still essential to the excellence of treatment. RESUMO Os autores fizeram uma revisão dos principais aspectos históricos da progressão do conhecimento sobre o tratamento cirúrgico do hiperparatireoidismo. Por meio de revisão bibliográfica, foram analisados artigos selecionados sobre a história da evolução do conhecimento anatômico, fisiológico, patológico e cirúrgico das glândulas paratireoides. Devido às suas características anatômicas peculiares, as paratireoides foram as últimas das glândulas endócrinas a serem descobertas, o que dificultou sobremaneira seu tratamento adequado até as primeiras décadas do Século XX. A evolução tecnológica ocorrida nos últimos 30 anos facilitou sobremaneira a localização das glândulas e a cirurgia do hiperparatireoidismo. Contudo, um cirurgião experiente e dedicado ao tratamento dessa enfermidade ainda é fundamental para a excelência do tratamento. PMID:27556546

  11. The magnitude and effects of extreme solar particle events

    NASA Astrophysics Data System (ADS)

    Jiggens, Piers; Chavy-Macdonald, Marc-Andre; Santin, Giovanni; Menicucci, Alessandra; Evans, Hugh; Hilgers, Alain

    2014-06-01

    The solar energetic particle (SEP) radiation environment is an important consideration for spacecraft design, spacecraft mission planning and human spaceflight. Herein is presented an investigation into the likely severity of effects of a very large Solar Particle Event (SPE) on technology and humans in space. Fluences for SPEs derived using statistical models are compared to historical SPEs to verify their appropriateness for use in the analysis which follows. By combining environment tools with tools to model effects behind varying layers of spacecraft shielding it is possible to predict what impact a large SPE would be likely to have on a spacecraft in Near-Earth interplanetary space or geostationary Earth orbit. Also presented is a comparison of results generated using the traditional method of inputting the environment spectra, determined using a statistical model, into effects tools and a new method developed as part of the ESA SEPEM Project allowing for the creation of an effect time series on which statistics, previously applied to the flux data, can be run directly. The SPE environment spectra is determined and presented as energy integrated proton fluence (cm-2) as a function of particle energy (in MeV). This is input into the SHIELDOSE-2, MULASSIS, NIEL, GRAS and SEU effects tools to provide the output results. In the case of the new method for analysis, the flux time series is fed directly into the MULASSIS and GEMAT tools integrated into the SEPEM system. The output effect quantities include total ionising dose (in rads), non-ionising energy loss (MeV g-1), single event upsets (upsets/bit) and the dose in humans compared to established limits for stochastic (or cancer-causing) effects and tissue reactions (such as acute radiation sickness) in humans given in grey-equivalent and sieverts respectively.

  12. Fabrication of phosphor micro-grids using proton beam lithography.

    SciTech Connect

    Rossi, Paolo; Antolak, Arlyn J.; Provencio, Paula Polyak; Doyle, Barney Lee; Malmqvist, Klas; Hearne, Sean Joseph; Nilsson, Christer; Kristiansson, Per; Wegden, Marie; Elfman, Mikael; Pallon, Jan; Auzelyte, Vaida

    2005-07-01

    A new nuclear microscopy technique called ion photon emission microscopy or IPEM was recently invented. IPEM allows analysis involving single ions, such as ion beam induced charge (IBIC) or single event upset (SEU) imaging using a slightly modified optical microscope. The spatial resolution of IPEM is currently limited to more than 10 {micro}m by the scattering and reflection of ion-induced photons, i.e. light blooming or spreading, in the ionoluminescent phosphor layer. We are developing a 'Microscopic Gridded Phosphor' (also called Black Matrix) where the phosphor nanocrystals are confined within the gaps of a micrometer scale opaque grid, which limits the amount of detrimental light blooming. MeV-energy proton beam lithography is ideally suited to lithographically form masks for the grid because of high aspect ratio, pattern density and sub-micron resolution of this technique. In brief, the fabrication of the grids was made in the following manner: (1) a MeV proton beam focused to 1.5-2 {micro}m directly fabricated a matrix of pillars in a 15 {micro}m thick SU-8 lithographic resist; (2) 7:1 aspect ratio pillars were then formed by developing the proton exposed area; (3) Ni (Au) was electrochemically deposited onto Cu-coated Si from a sulfamate bath (or buffered CN bath); (4) the SU-8 pillars were removed by chemical etching; finally (5) the metal micro-grid was freed from its substrate by etching the underlying Cu layer. Our proposed metal micro-grids promise an order-of-magnitude improvement in the resolution of IPEM.

  13. Causal relationships between solar proton events and single event upsets for communication satellites

    NASA Astrophysics Data System (ADS)

    Lohmeyer, W. Q.; Cahoy, K.; Liu, Shiyang

    In this work, we analyze a historical archive of single event upsets (SEUs) maintained by Inmarsat, one of the world's leading providers of global mobile satellite communications services. Inmarsat has operated its geostationary communication satellites and collected extensive satellite anomaly and telemetry data since 1990. Over the course of the past twenty years, the satellites have experienced more than 226 single event upsets (SEUs), a catch-all term for anomalies that occur in a satellite's electronics such as bit-flips, trips in power supplies, and memory changes in attitude control systems. While SEUs are seemingly random and difficult to predict, we correlate their occurrences to space weather phenomena, and specifically show correlations between SEUs and solar proton events (SPEs). SPEs are highly energetic protons that originate from solar coronal mass ejections (CMEs). It is thought that when these particles impact geostationary (GEO) satellites they can cause SEUs as well as solar array degradation. We calculate the associated statistical correlations that each SEU occurs within one day, one week, two weeks, and one month of 10 MeV SPEs between 10 - 10,000 particle flux units (pfu). However, we find that SPEs are most prevalent at solar maximum and that the SEUs on Inmarsat's satellites occur out of phase with the solar maximum. Ultimately, this suggests that SPEs are not the primary cause of the Inmarsat SEUs. A better understanding of the causal relationship between SPEs and SEUs will help the satellite communications industry develop component and operational space weather mitigation techniques as well as help the space weather community to refine radiation models.

  14. Single Event Effects Test Facility Options at the Oak Ridge National Laboratory

    SciTech Connect

    Riemer, Bernie; Gallmeier, Franz X; Dominik, Laura J

    2015-01-01

    Increasing use of microelectronics of ever diminishing feature size in avionics systems has led to a growing Single Event Effects (SEE) susceptibility arising from the highly ionizing interactions of cosmic rays and solar particles. Single event effects caused by atmospheric radiation have been recognized in recent years as a design issue for avionics equipment and systems. To ensure a system meets all its safety and reliability requirements, SEE induced upsets and potential system failures need to be considered, including testing of the components and systems in a neutron beam. Testing of integrated circuits (ICs) and systems for use in radiation environments requires the utilization of highly advanced laboratory facilities that can run evaluations on microcircuits for the effects of radiation. This paper provides a background of the atmospheric radiation phenomenon and the resulting single event effects, including single event upset (SEU) and latch up conditions. A study investigating requirements for future single event effect irradiation test facilities and developing options at the Spallation Neutron Source (SNS) is summarized. The relatively new SNS with its 1.0 GeV proton beam, typical operation of 5000 h per year, expertise in spallation neutron sources, user program infrastructure, and decades of useful life ahead is well suited for hosting a world-class SEE test facility in North America. Emphasis was put on testing of large avionics systems while still providing tunable high flux irradiation conditions for component tests. Makers of ground-based systems would also be served well by these facilities. Three options are described; the most capable, flexible, and highest-test-capacity option is a new stand-alone target station using about one kW of proton beam power on a gas-cooled tungsten target, with dual test enclosures. Less expensive options are also described.

  15. Perda de massa em ventos empoeirados de estrelas supergigantes

    NASA Astrophysics Data System (ADS)

    Vidotto, A. A.; Jatenco-Pereira, V.

    2003-08-01

    Em praticamente todas as regiões do diagrama HR, as estrelas apresentam evidências observacionais de perda de massa. Na literatura, pode-se encontrar trabalhos que tratam tanto do diagnóstico da perda de massa como da construção de modelos que visam explicá-la. O amortecimento de ondas Alfvén tem sido utilizado como mecanismo de aceleração de ventos homogêneos. Entretanto, sabe-se que os envelopes de estrelas frias contêm grãos sólidos e moléculas. Com o intuito de estudar a interação entre as ondas Alfvén e a poeira e a sua conseqüência na aceleração do vento estelar, Falceta-Gonçalves & Jatenco-Pereira (2002) desenvolveram um modelo de perda de massa para estrelas supergigantes. Neste trabalho, apresentamos um estudo do modelo acima proposto para avaliar a dependência da taxa de perda de massa com alguns parâmetros iniciais como, por exemplo, a densidade r0, o campo magnético B0, o comprimento de amortecimento da onda L0, seu fluxo f0, entre outros. Sendo assim, aumentando f0 de 10% a partir de valores de referência, vimos que aumenta consideravelmente, enquanto que um aumento de mesmo valor em r0, B0 e L0 acarreta uma diminuição em .

  16. The Illness Experience: Palliative Care Given the impossibility of Healing.

    PubMed

    Dantas, Margarida Maria Florêncio; Amazonas, Maria Cristina Lopes de Almeida

    2016-06-01

    This paper presents a reflection about being terminally ill and the various ways that the subject has at its disposal to deal with this event. The objective is to understand the experience of palliation for patients undergoing no therapeutic possibilities of cure. The methodology of this study has the instruments to semi-structured interview, the participant observation and the field diary, and the Descriptive Analysis of Foucault's inspiration how the narratives of the subjects were perceived. The Results of paper there was the possibility of looking at the experience of illness through the eyes of a subject position assumed by the very sick. As conclusion we have than when choosing palliative care, the terminally ill opts for a way to feel more comfortable and resists the impositions of the medical model of prolonging life. O presente trabalho traz uma reflexão a respeito do ser um doente terminal e das várias maneiras que o sujeito tem a seu dispor para lidar com esse acontecimento. Nosso objetivo foi compreender a experiência da paliação por sujeitos doentes sem possibilidades terapêuticas de cura. A metodologia deste estudo teve como instrumentos a Entrevista Narrativa, a Observação Participante e o Diário de Campo, sendo a Análise Descritiva de inspiração foucaultiana o modo como as narrativas dos sujeitos foram percebidas. O resultado do estudo mostrou a possibilidade de olhar a experiência do adoecer através da ótica de uma posição de sujeito assumida pelo próprio enfermo. E concluímos que ao escolher os cuidados paliativos, o doente terminal opta por um modo de se sentir mais confortável e resiste às imposições do modelo médico de prolongamento da vida. PMID:27384275

  17. Mars Express and Venus Express Data Retention In-Flight Performance

    NASA Astrophysics Data System (ADS)

    Lebrédonchel, J.; Rombeck, F.-J.

    2007-08-01

    Venus, Mars and Earth, three out of the four inner or 'rocky' planets of the Solar System, have a lot in common: a solid surface you could walk on, a comparable surface composition, an atmosphere and a weather system. European Space Agency (ESA) Mars Express (MEx) and Venus Express (VEx) pioneer scientific missions aim at exploring these two neighbours of the Earth, in order to enrich our knowledge of our planet and of the Solar System. Both projects are based on the same spacecraft bus, and in particular on 'sister' Solid State Mass Memory (SSMM) units, in charge of the acquisition, storage and retrieval of all on board data, relevant both to the platform and to the instruments. This paper recalls the common SSMM design and the inner fault tolerant memory array module architecture based on Computer Off The Shelf (COTS) Samsung 64 Mbit Synchronous Dynamic Random Access Memory (SDRAM) chips, and presents the comparative in-flight data retention performance for both MEx and Vex units, since their respective June 2003 and November 2005 launches. Both units have shown to successfully withstand the radiative deep space environment, including during the outstanding October 2003 solar flare, and no uncorrectable data corruption was ever reported. Beyond this stable retention performance over time, the memory scrubbing correctable error accounting feedback allows evaluating the deep space Single Event Upset (SEU) rates, to be compared with the theoretical SSMM radiation assessment as well as with other previous missions in-flight qualitative reference performance records, and finally enables to derive a couple of recommendations from the lessons' learnt.

  18. A promising RVO4:Eu(3+), Li(+)@SiO2 (R = Gd, Y and Gd/Y) red-emitting phosphor with improved luminescence (cd/m(2)) and colour purity for optical display applications.

    PubMed

    Rambabu, Urlagaddala; Munirathnam, Nagegownivari Ramachandra; Reddy, Busireddy Sudhakar; Chatterjee, Sandip

    2016-02-01

    Red emission intensity was optimized in three stages, by investigating the effects of: (i) host composition (Gd, Y and Gd/Y), (ii) codoping Li(+) as a sensitizer and, finally, (iii) with a SiO2 shell coating as a protecting layer. Lanthanide vanadate powder phosphors were synthesized using a modified colloidal precipitation technique. The effects of SiO2 coating on phosphor particles were characterized using scanning electron microscopy (SEM)-EDAX, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and photoluminescence (PL) measurements. An improvement in the PL intensity on Li codoping was due to improved crystallinity, which led to higher oscillating strengths for the optical transitions, and also a lowering of the inversion symmetry of Eu(3+) ions. Red emission intensity due to (5)D0  → (5)D2 transition of the phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01 was enhanced by 22.28% compared with Y0.95VO4:Eu(3+)0.05, and was further improved by 58.73% with SiO2 coating. The luminescence intensity (I) and colour coordinates (x, y) of the optimized phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01@SiO2, where I = 13.07 cd/m(2) and (x = 0.6721, y = 0.3240), were compared with values for a commercial red phosphor (Y2O2S:Eu(3+)), where I = 27 cd/m(2) and (x = 0.6522, y = 0.3437). The measured colour coordinates are superior to those of the commercial red phosphor, and moreover, match well with standard NTSC values (x = 0.67, y = 0.33). PMID:25989734

  19. On Ensino de Astronomia: Desafios para Implantação

    NASA Astrophysics Data System (ADS)

    Faria, R. Z.; Voelzke, M. R.

    2008-09-01

    Em 2002 o ensino de Astronomia foi proposto como um dos temas estruturadores pelos Parâmetros Curriculares Nacionais e sugerido como facilitador para que o aluno compreendesse a Física como construção humana e parte do seu mundo vivencial, mas raramente seus conceitos foram ensinados. A presente pesquisa discute dois aspectos relacionados à abordagem de Astronomia. O primeiro aspecto é se ela está sendo abordada pelos professores do Ensino Médio e o segundo, aborda a maneira como ela está sendo ensinada. Optou-se pela aplicação de um questionário a partir do 2° semestre de 2006 e durante o ano de 2007 com professores que ministram a disciplina de Física, os quais trabalham em escolas estaduais em Rio Grande da Serra, Ribeirão Pires e Mauá no estado São Paulo. Dos 66,2% dos professores que responderam ao questionário nos municípios de Rio Grande da Serra, Ribeirão Pires e Mauá, 57,4% não aplicaram nenhum tópico de astronomia, 70,2% não utilizaram laboratório, 89,4% não utilizaram qualquer tipo de programa computacional, 83,0% nunca fizeram visitas com alunos a museus e planetários e 38,3% não indicaram qualquer tipo de livro ou revista referente à astronomia aos seus alunos. Mesmo considerando a Astronomia um conteúdo potencialmente significativo, esta não fez parte dos planejamentos escolares. Portanto são necessárias propostas que visem estratégias para a educação continuada dos professores como, por exemplo, cursos específicos sobre o ensino em Astronomia.

  20. Compact CMOS Camera Demonstrator (C3D) for Ukube-1

    NASA Astrophysics Data System (ADS)

    Harriss, R. D.; Holland, A. D.; Barber, S. J.; Karout, S.; Burgon, R.; Dryer, B. J.; Murray, N. J.; Hall, D. J.; Smith, P. H.; Grieg, T.; Tutt, J. H.; Endicott, J.; Jerram, P.; Morris, D.; Robbins, M.; Prevost, V.; Holland, K.

    2011-09-01

    The Open University, in collaboration with e2v technologies and XCAM Ltd, have been selected to fly an EO (Earth Observation) technology demonstrator and in-orbit radiation damage characterisation instrument on board the UK Space Agency's UKube-1 pilot Cubesat programme. Cubesat payloads offer a unique opportunity to rapidly build and fly space hardware for minimal cost, providing easy access to the space environment. Based around the e2v 1.3 MPixel 0.18 micron process eye-on-Si CMOS devices, the instrument consists of a radiation characterisation imager as well as a narrow field imager (NFI) and a wide field imager (WFI). The narrow and wide field imagers are expected to achieve resolutions of 25 m and 350 m respectively from a 650 km orbit, providing sufficient swathe width to view the southern UK with the WFI and London with the NFI. The radiation characterisation experiment has been designed to verify and reinforce ground based testing that has been conducted on the e2v eye-on-Si family of devices and includes TEC temperature control circuitry as well as RADFET in-orbit dosimetry. Of particular interest are SEU and SEL effects. The novel instrument design allows for a wide range of capabilities within highly constrained mass, power and space budgets providing a model for future use on similarly constrained missions, such as planetary rovers. Scheduled for launch in December 2011, this 1 year low cost programme should not only provide valuable data and outreach opportunities but also help to prove flight heritage for future missions.

  1. A combination of radar and thermal approaches to search for methane clathrate in the Martian subsurface

    NASA Astrophysics Data System (ADS)

    Duxbury, N. S.; Abyzov, S. S.; Romanovsky, V. E.; Yoshikawa, K.

    2004-01-01

    It has been suggested that methane clathrate is stable in the subsurface of Mars (Max and Clifford, (J. Geophys. Res.-Planets 105 (E2) (2000) 4165). Max and Clifford (Geophys. Res. Lett. 28(9) (2001) 1787) have proposed that the Martian chaotic terrain could be a surface manifestation of the dissociation of subsurface methane clathrate hydrate. They have used the large terrestrial sub-oceanic landforms (which have formed due to dissociation of methane clathrate) as an analog. The detection of methane (either in the form of gas or in the solid form of clathrate hydrate) would be evidence of indigenous life in the Martian subsurface, since methane on Earth has mostly biogenic origin. Moreover, methane is a valuable resource for the human exploration of Mars. We propose a novel approach to search for potential Martian methane clathrate hydrate and perform related computations. Our method uses the effect of latent heat of clathrate-phase transitions on the internal heat flow, and hence on permafrost thickness above the clathrate deposit. It will allow one to extract related information out of the radar data that will be used to search for the ground ice/ground water interface. The interpretation of the radar data of ground ice/ground water boundary, which we propose here, can be used to analyze the SHARAD radar data set (Seu et al., 2003) on the Mars Reconnaissance Orbiter (MRO) 2005 mission and the potential Ground Penetrating Radar data on the Mars Science Laboratory, currently planned to be launched in 2009. From this viewpoint we make recommendations for future orbiting/landed missions to Mars.

  2. Education and Public Outreach Programs for Structure and Evolution of the Universe Themed Missions: CHIPS and SPIDR

    NASA Astrophysics Data System (ADS)

    Mendez, B. J.; Craig, N.

    2003-05-01

    The Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) is the first NASA University-Class Explorer (UNEX) mission, and was launched on January 12th, 2003. It will study the extremely diffuse, hot gas inside the region surrounding the Sun out to a radius of about 300 light years known as the Local Bubble. The focus of the CHIPS education and outreach will be disseminating products produced during Phases C, and D to classrooms, and through professional development programs, science teacher conferences and other NASA OSS and SEU Education Forum branches. We have also developed an eight-page Educational Brief, titled "Cosmic Bubbles in the Interstellar Medium," for educators and students containing background information on the Interstellar Medium (ISM). Additional classroom testing and presentation of CHIPS activities will occur during Summer 2003 in Berkeley's Academic Talent Development (ATDP) program. One of NASA's newest SMEX missions is SPIDR (Spectroscopy and Photometry of the Intergalactic Medium's Diffuse Radiation), which when launched in 2005 will study the "cosmic web" of intergalactic gas spanning the Universe. The E/PO during Phase B of SPIDR will focus on partnerships with UC Berkeley's Lawrence Hall of Science GEMS program (Great Explorations in Math and Science). The first joint venture of GEMS and SPIDR will be the launch of a new GEMS site at the Lodestar Astronomy Center located in the New Mexico Museum of Natural History and Science in Albuquerque, NM in June, 2003. The SPIDR E/PO team is also partnering with LHS in the development of a new GEMS Space Science Strand that will include activities focused on the size and scale of the Universe.

  3. Comparação de modelos para o cálculo de perturbações orbitais devidas à maré terrestre

    NASA Astrophysics Data System (ADS)

    Vieira Pinto, J.; Vilhena de Moraes, R.

    2003-08-01

    Aplicações recentes de satélites artificiais com finalidades geodinâmicas requerem órbitas determinadas com bastante precisão. Em particular marés terrestres influenciam o potencial terrestre causando perturbações adicionais no movimento de satélites artificiais, as quais tem sido medidas por diversos processos. A atração exercida pela lua e pelo sol sobre a terra produz deslocamentos elásticos em seu interior e uma protuberância em sua superfície. O resultado é uma pequena variação na distribuição da massa na terra, consequentemente no geopotencial. As perturbações nos elementos orbitais de satélites artificiais terrestres devidas a maré terrestre podem ser estudadas a partir das equações de Lagrange, considerando-se um conveniente potencial. Por outro lado, como tem sido feito pelo IERS, as mudanças induzidas pela maré terrestre no geopotencial podem ser convenientemente modeladas como variações nos coeficientes Cnm e Snm do geopotencial. As duas teorias ainda não foram comparados para um mesmo satélite. Neste trabalho são apresentadas e comparadas as variações de longo período e seculares nas perturbações orbitais devidas à maré terrestre, calculadas por um modelo simples, o de Kozai, e pelo modelo do IERS. Resultados preliminares mostram, para os satélites SCD2 e CBERS1, e para a Lua em movimento elíptico e precessionando, as perturbações seculares no argumento do perigeu e na longitude do nodo ascendente.

  4. SINGLE EVENT EFFECTS TEST FACILITY AT OAK RIDGE NATIONAL LABORATORY

    SciTech Connect

    Riemer, Bernie; Gallmeier, Franz X; Dominik, Laura J

    2015-01-01

    Increasing use of microelectronics of ever diminishing feature size in avionics systems has led to a growing Single Event Effects (SEE) susceptibility arising from the highly ionizing interactions of cosmic rays and solar particles. Single event effects caused by atmospheric radiation have been recognized in recent years as a design issue for avionics equipment and systems. To ensure a system meets all its safety and reliability requirements, SEE induced upsets and potential system failures need to be considered, including testing of the components and systems in a neutron beam. Testing of ICs and systems for use in radiation environments requires the utilization of highly advanced laboratory facilities that can run evaluations on microcircuits for the effects of radiation. This paper provides a background of the atmospheric radiation phenomenon and the resulting single event effects, including single event upset (SEU) and latch up conditions. A study investigating requirements for future single event effect irradiation test facilities and developing options at the Spallation Neutron Source (SNS) is summarized. The relatively new SNS with its 1.0 GeV proton beam, typical operation of 5000 h per year, expertise in spallation neutron sources, user program infrastructure, and decades of useful life ahead is well suited for hosting a world-class SEE test facility in North America. Emphasis was put on testing of large avionics systems while still providing tunable high flux irradiation conditions for component tests. Makers of ground-based systems would also be served well by these facilities. Three options are described; the most capable, flexible, and highest-test-capacity option is a new stand-alone target station using about one kW of proton beam power on a gas-cooled tungsten target, with dual test enclosures. Less expensive options are also described.

  5. Polymeric Materials With Additives for Durability and Radiation Shielding in Space

    NASA Technical Reports Server (NTRS)

    Kiefer, Richard

    2011-01-01

    Polymeric materials are attractive for use in space structures because of their light weight and high strength In addition, polymers are made of elements with low atomic numbers (Z), primarily carbon (C), hydrogen (H), oxygen (0), and nitrogen (N) which provide the best shielding from galactic cosmic rays (GCR) (ref. 1). Galactic cosmic rays are composed primarily of nuclei (i.e., fully ionized atoms) plus a contribution of about 2% from electrons and positrons. There is a small but significant component of GCR particles with high charge (Z > 10) and high energy (E >100 GeV) (ref. 2). These so-called HZE particles comprise only 1 to 2% of the cosmic ray fluence but they interact with very high specific ionization and contribute 50% of the long- term dose to humans. The best shield for this radiation would be liquid hydrogen, which is not feasible. For this reason, hydrogen-containing polymers make the most effective practical shields. Moreover, neutrons are formed in the interactions of GCR particles with materials. Neutrons can only lose energy by collisions or reactions with a nucleus since they are uncharged. This is a process that is much less probable than the Coulombic interactions of charged particles. Thus, neutrons migrate far from the site of the reaction in which they were formed. This increases the probability of neutrons reaching humans or electronic equipment. Fast neutrons (> 1 MeV) can interact with silicon chips in electronic equipment resulting in the production of recoil ions which can cause single event upsets (SEU) in sensitive components (ref. 3). Neutrons lose energy most effectively by elastic collisions with light atoms, particularly hydrogen atoms. Therefore, hydrogen-containing polymers are not only effective in interacting with GCR particles; they are also effective in reducing the energy of the neutrons formed in the interactions.

  6. Modeling indirect detectors for performance optimization of a digital mammographic detector for dual energy applications

    NASA Astrophysics Data System (ADS)

    Martini, N.; Koukou, V.; Kalyvas, N.; Sotiropoulou, P.; Michail, C.; Valais, I.; Bakas, A.; Kandarakis, I.; Nikiforidis, G.; Fountos, G.

    2015-01-01

    Dual Energy imaging is a promising method for visualizing masses and microcalcifications in digital mammography. The advent of two X-ray energies (low and high) requires a suitable detector. The scope of this work is to determine optimum detector parameters for dual energy applications. The detector was modeled through the linear cascaded (LCS) theory. It was assumed that a phosphor material was coupled to a CMOS photodetector (indirect detection). The pixel size was 22.5 μm. The phosphor thickness was allowed to vary between 20mg/cm2 and 160mg/cm2 The phosphor materials examined where Gd2O2S:Tb and Gd2O2S:Eu. Two Tungsten (W) anode X-ray spectra at 35 kV (filtered with 100 μm Palladium (Pd)) and 70 kV (filtered with 800 pm Ytterbium (Yb)), corresponding to low and high energy respectively, were considered to be incident on the detector. For each combination the contrast- to-noise ratio (CNR) and the detector optical gain (DOG), showing the sensitivity of the detector, were calculated. The 40 mg/cm2 and 70 mg/cm2 Gd2O2S:Tb exhibited the higher DOG values for the low and high energy correspondingly. Higher CNR between microcalcification and mammary gland exhibited the 70mg/cm2 and the 100mg/cm2 Gd2O2S:Tb for the low and the high energy correspondingly.

  7. Study of the VMM1 read-out chip in a neutron irradiation environment

    NASA Astrophysics Data System (ADS)

    Alexopoulos, T.; Fanourakis, G.; Geralis, T.; Kokkoris, M.; Kourkoumeli-Charalampidi, A.; Papageorgiou, K.; Tsipolitis, G.

    2016-05-01

    Within 2015, the LHC operated close to the design energy of √s = 13–14 TeV delivering instantaneous luminosities up to Script L = 5 × 1033 cm‑2s‑1. The ATLAS Phase-I upgrade in 2018/19 will introduce the MicroMEGAS detectors in the area of the small wheel at the end caps. Accompanying new electronics are designed and built such as the VMM front end ASIC, which provides energy, timing and triggering information and allows fast data read-out. The first VMM version (VMM1) has been widely produced and tested in various test beams, whilst the second version (VMM2) is currently being tested. This paper focuses on the VMM1 single event upset studies and more specifically on the response of the configuration registers under harsh radiation environments. Similar conditions are expected at Run III with Script L = 2 × 1034 cm‑2s‑1 and a mean of 55 interactions per bunch crossing. Two VMM1s were exposed in a neutron irradiation environment using the TANDEM Van Der Graaff accelerator at NSCR Demokritos, Athens, Greece. The results showed a rate of SEU occurrences at a measured cross section of (4.1±0.8)×10‑14 cm2/bit for each VMM. Consequently, when extrapolating this value to the luminosity expected in Run III, the occurrence is roughly 6 SEUs/min in all the read-out system comprising 40,000 VMMs installed during the Phase-I upgrade.

  8. Our Understanding of Space Weather features responsible for geostationary satellite anamolies (P39)

    NASA Astrophysics Data System (ADS)

    Rajaram, G.; et al.

    2006-11-01

    girija60@yahoo.com The topic of space weather effects on operational anomalies on spacecraft is one of considerable research investigation, with both pure and applied aspects. This is because of the very high costs involved in fabricating and operating spacecraft, and in insuring them against the harmful effects of space weather. This is more true for geostationary satellites than of low-orbiting spacecraft, as the former operate in the high-risk environment of the Earth’s outer radiation belts, with its large vagaries in spatial and time variations of high- energy electron and proton distributions (BAKER 2003). Without doubt, plasma and magnetic field emissions from active regions on the Sun are the root cause for spacecraft anomalies. Our study for 2005 shows that over 95% of anomalies can be related to some definite activity on the Sun, ranging from high-speed solar wind streams with their 27-day recurrence patterns/coronal holes/coronal mass ejections preceded by X or M type of flares/and magnetic cloud events. The most energetic solar activity events are generally accompanied by a large rise in solar MeV proton densities at geo-stationary orbit (WILKINSON 1994), and they account for definite anomalies classified as SEU (Single Event Upsets which most often are reversible through resetting commands). Any particles in the low energy ranges (eV and keV, and these could be of magnetospheric or ionospheric origin), are believed to cause external charging effects in exposed parts of the spacecraft such as solar power arrays and power cables. These mainly result in power losses which are debilitating over a period of time. The most dangerous and often irrecoverable damage is due to electronics in the 1-5 MeV range which cause deep dielectric discharge of arc type in semi-conductors comprising spacecraft instruments. Following major solar activity, the populations of these rise to more than (5x103) particles/cm2.ster.sec, with large spatial and time variations (LOVE

  9. Broad Beam and Ion Microprobe Studies of Single-Event Upsets in High Speed 0.18micron Silicon Germanium Heterojunction Bipolar Transistors and Circuits

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Marshall, Paul W.; Pickel, Jim; Carts, Martin A.; Irwin, TIm; Niu, Guofu; Cressler, John; Krithivasan, Ramkumar; Fritz, Karl; Riggs, Pam

    2003-01-01

    SiGe based technology is widely recognized for its tremendous potential to impact the high speed microelectronic industry, and therefore the space industry, by monolithic incorporation of low power complementary logic with extremely high speed SiGe Heterojunction Bipolar Transistor (HBT) logic. A variety of studies have examined the ionizing dose, displacement damage and single event characteristics, and are reported. Accessibility to SiGe through an increasing number of manufacturers adds to the importance of understanding its intrinsic radiation characteristics, and in particular the single event effect (SEE) characteristics of the high bandwidth HBT based circuits. IBM is now manufacturing in its 3rd generation of their commercial SiGe processes, and access is currently available to the first two generations (known as and 6HP) through the MOSIS shared mask services with anticipated future release of the latest (7HP) process. The 5 HP process is described and is characterized by a emitter spacing of 0.5 micron and a cutoff frequency ff of 50 GHz, whereas the fully scaled 7HP HBT employs a 0.18 micron emitter and has an fT of 120 GHz. Previous investigations have the examined SEE response of 5 HP HBT circuits through both circuit testing and modeling. Charge collection modeling studies in the 5 H P process have also been conducted, but to date no measurements have been reported of charge collection in any SiGe HBT structures. Nor have circuit models for charge collection been developed in any version other than the 5 HP HBT structure. Our investigation reports the first indications of both charge collection and circuit response in IBM s 7HP-based SiGe process. We compare broad beam heavy ion SEU test results in a fully function Pseudo-Random Number (PRN) sequence generator up to frequencies of 12 Gbps versus effective LET, and also report proton test results in the same circuit. In addition, we examine the charge collection characteristics of individual 7HP HBT

  10. The Universe in a Box: Introduction to the Study of Astronomy in the Initial Formation of Physics Teachers. (Spanish Title: El Universo Representado en Una Caja: Introducción al Estudio de la Astronomía en la Formación Inicial de Profesores de Física.) O Universo Representado em Uma Caixa: Introdução ao Estudo da Astronomia NA Formação Inicial de Professores de Física

    NASA Astrophysics Data System (ADS)

    Longhini, Marcos Daniel

    2009-07-01

    modelos de universo que os participantes possuíam. Os resultados, que foram categorizados em universo miscelânea, geocêntrico, heliocêntrico e acêntrico, foram analisados qualitativamente. São apontadas as análises da atividade na ótica dos participantes, além de tecidas considerações sobre seu emprego como recurso ao ensino de Astronomia e na formação docente.

  11. Monitoring pH-Triggered Drug Release from Radioluminescent Nanocapsules with X-Ray Excited Optical Luminescence

    PubMed Central

    Chen, Hongyu; Moore, Thomas; Qi, Bin; Colvin, Daniel C.; Jelen, Erika K.; Hitchcock, Dale A.; He, Jian; Mefford, O. Thompson; Gore, John C.; Alexis, Frank; Anker, Jeffrey N.

    2013-01-01

    One of the greatest challenges in cancer therapy is to develop methods to deliver chemotherapy agents to tumor cells while reducing systemic toxicity to non-cancerous cells. A promising approach to localizing drug release is to employ drug-loaded nanoparticles with coatings that release the drugs only in the presence of specific triggers found in the target cells such as pH, enzymes, or light. However, many parameters affect the nanoparticle distribution and drug release rate and it is difficult to quantify drug release in situ. In this work, we show proof of principle for a “smart” radioluminescent nanocapsule with X-ray excited optical luminescence (XEOL) spectrum that changes during release of the optically absorbing chemotherapy drug, doxorubicin. XEOL provides an almost background-free luminescent signal for measuring drug release from particles irradiated by a narrow X-ray beam. We study in vitro pH triggered release rates of doxorubicin from nanocapsules coated with a pH responsive polyelectrolyte multilayer using HPLC and XEOL spectroscopy. The doxorubicin was loaded to over 5 % by weight, and released from the capsule with a time constant in vitro of ~ 36 days at pH 7.4, and 21.4 hr at pH 5.0, respectively. The Gd2O2S:Eu nanocapsules are also paramagnetic at room temperature with similar magnetic susceptibility and similarly good MRI T2 relaxivities to Gd2O3, but the sulfur increases the radioluminescence intensity and shifts the spectrum. Empty nanocapsules did not affect cell viability up to concentrations of at least 250 μ/ml. These empty nanocapsules accumulated in a mouse liver and spleen following tail vein injection, and could be observed in vivo using XEOL. The particles are synthesized with a versatile template synthesis technique which allows for control of particle size and shape. The XEOL analysis technique opens the door to non-invasive quantification of drug release as a function of nanoparticle size, shape, surface chemistry and tissue

  12. Network as transconcept: elements for a conceptual demarcation in the field of public health.

    PubMed

    Amaral, Carlos Eduardo Menezes; Bosi, Maria Lúcia Magalhães

    2016-06-10

    The main proposal to set up an articulated mode of operation of health services has been the concept of network, which has been appropriated in different ways in the field of public health, as it is used in other disciplinary fields or even taking it from common sense. Amid the diversity of uses and concepts, we recognize the need for rigorous conceptual demarcation about networks in the field of health. Such concern aims to preserve the strategic potential of this concept in the research and planning in the field, overcoming uncertainties and distortions still observed in its discourse-analytic circulation in public health. To this end, we will introduce the current uses of network in different disciplinary fields, emphasizing dialogues with the field of public health. With this, we intend to stimulate discussions about the development of empirical dimensions and analytical models that may allow us to understand the processes produced within and around health networks. RESUMO A principal proposta para configurar um modo articulado de funcionamento dos serviços de saúde tem sido o conceito de rede, que vem sendo apropriado de diferentes formas no campo da saúde coletiva, conforme seu emprego em outros campos disciplinares ou mesmo tomando-o do senso comum. Em meio à pluralidade de usos e concepções, reconhecemos a necessidade de rigorosa demarcação conceitual acerca de redes no campo da saúde. Tal preocupação visa a preservar o potencial estratégico desse conceito na investigação e planificação no campo, superando precariedades e distorções ainda observadas em sua circulação discursivo-analítica na saúde coletiva. Para tanto, apresentaremos os usos correntes de rede em diferentes campos disciplinares, destacando interlocuções com o campo da saúde coletiva. Com isso, pretendemos estimular o debate acerca do desenvolvimento de dimensões empíricas e modelos de análise que permitam compreender os processos produzidos no interior e ao redor

  13. Camões e a cosmogonia

    NASA Astrophysics Data System (ADS)

    Costa, J. M.

    2003-08-01

    Os Lusíadas, escrito por Luis de Camões em 1572, é um poema épico renascentista e a visão Cosmogônica do autor é apresentada, principalmente, no último canto do poema, quando Tétis mostra ao Gama a Máquina do Mundo. A Cosmogonia de Camões neste poema reflete uma visão de uma época de transição, que ainda não incorporou os elementos da revolução Copernicana. É uma visão Grego- Ptolomaica e também medieval. O poeta guia-se pela tradução e notas feita por Pedro Nunes, inventor do Nonio, do Tratado da Esfera "De Sphaera" do Astrônomo Inglês John Holywood, mais conhecido pelo nome latinizado de Johannes Sacrobosco. Outra provável fonte de Camões, de acordo com Luciano Antonio Pereira da Silva em Astronomia de os Lusíadas, é o "Theoricae novae Planetarum" (1460) do astrólogo Alemão Jorge Purbáquio (1423 - 1461). A Astronomia de Os Lusíadas representa a ciência do tempo de Camões. Camões nunca emprega a palavra constelação e seu catálogo é bastante completo. A Máquina do Mundo tem a Terra no centro. Em redor, em círculos concêntricos, a lua (Diana), Mercúrio, Vênus, o Sol (Febo), Marte, Júpiter e Saturno. Envolvendo estes astros tem o firmamento seguido pelo "Céu Áqueo" ou cristalino, depois o 1o Móbil, esfera que arrasta todas as outras consigo. Este trabalho, multidisciplinar, serve tanto para ensinar aos alunos da Física como das Ciências Humanas, a concepção de mundo do renascimento de uma forma belamente poética em versos decassílabos Este trabalho também ajuda na apreciação do maior clássico da língua portuguesa e mostra como as Ciências e as artes, em geral, estão correlacionadas e refletem a visão de mundo da época em que foi produzida.

  14. FPGA-Based, Self-Checking, Fault-Tolerant Computers

    NASA Technical Reports Server (NTRS)

    Some, Raphael; Rennels, David

    2004-01-01

    A proposed computer architecture would exploit the capabilities of commercially available field-programmable gate arrays (FPGAs) to enable computers to detect and recover from bit errors. The main purpose of the proposed architecture is to enable fault-tolerant computing in the presence of single-event upsets (SEUs). [An SEU is a spurious bit flip (also called a soft error) caused by a single impact of ionizing radiation.] The architecture would also enable recovery from some soft errors caused by electrical transients and, to some extent, from intermittent and permanent (hard) errors caused by aging of electronic components. A typical FPGA of the current generation contains one or more complete processor cores, memories, and highspeed serial input/output (I/O) channels, making it possible to shrink a board-level processor node to a single integrated-circuit chip. Custom, highly efficient microcontrollers, general-purpose computers, custom I/O processors, and signal processors can be rapidly and efficiently implemented by use of FPGAs. Unfortunately, FPGAs are susceptible to SEUs. Prior efforts to mitigate the effects of SEUs have yielded solutions that degrade performance of the system and require support from external hardware and software. In comparison with other fault-tolerant- computing architectures (e.g., triple modular redundancy), the proposed architecture could be implemented with less circuitry and lower power demand. Moreover, the fault-tolerant computing functions would require only minimal support from circuitry outside the central processing units (CPUs) of computers, would not require any software support, and would be largely transparent to software and to other computer hardware. There would be two types of modules: a self-checking processor module and a memory system (see figure). The self-checking processor module would be implemented on a single FPGA and would be capable of detecting its own internal errors. It would contain two CPUs executing

  15. Fisica a escala de Planck usando o principio de incerteza generalizado: efeitos nas flutuações primordiais e buracos negros

    NASA Astrophysics Data System (ADS)

    Horvath, J. E.; Custódio, P. S.

    2003-08-01

    Em escalas proximas à escala de Planck todas as teorias perturbativas de cordas produzem essenciamente a mesma relação de conmutação entre as coordenadas e impulsos (a chamada "álgebra deformada"), permitindo assim estudar a física resultante independentemente dos detalhes da teoria de cordas que seja considerada correta. Este resultado completamente geral, que inclui as interações gravitacionais junto com o resto dos campos pode ser considerada uma versão generalizada (GUP) do Princípio de Incerteza de Heisenberg. Aplicamos neste trabalho essas relações de conmutação para dois sistemas físicos bem definidos: buracos negros de massas próximas à massa de Planck, e flutuações quânticas em pequenas escalas antes do universo sofrer inflação. Obtemos dois resultados concretos dos efeitos do GUP : o primeiro é que o GUP impede a evaporação completa de buracos negros microscópicos na extensão do formalismo semiclássico, deixando assim remanescentes de pequena massa que já foram postulados como candidatos a matéria escura. O segundo resultado é o 'smoothing' das flutuações primordiais em pequenas escalas que levariam à produção de buracos negros primordiais após a inflação, impedindo assim a produção abundante destes últimos e predizendo abundancias atuais bem menores do que os limites disponíveis. Concluimos que, analogamente a utilização do Princípio de Incerteza de Heisenberg para estudar e determinar propriedades fundamentais das interações sem gravitação, o GUP e uma ferramenta poderosa para estudar uma ampla variedade de sistemas trans-Planckianos e predizer seu comportamento dispensando cálculos mais detalhados proprios da teoria quântica da gravitação.

  16. A atuação do Observatório Nacional registrada nos relatórios ministeriais 1889 a 1930

    NASA Astrophysics Data System (ADS)

    Rodrigues, T.

    2003-08-01

    O período republicano até 1930 foi marcante na história do Observatório Nacional. Diversas reformas levaram a instituição a três ministérios diferentes e mudaram a ênfase do seu trabalho. A tão aguardada mudança para uma nova sede, em São Cristóvão, em 1920, não foi suficiente para que a instituição acompanhasse o ritmo tomado pela astronomia no mundo e se firmasse como ambiente de pesquisa. Uma análise simplificada poderia caracterizar um período de produção científica insignificante, dado o distanciamento da instituição dos novos rumos da astrofísica e da rápida inovação dos instrumentos, além do pequeno volume de publicações. Era uma época em que ainda não existiam os mecanismos formais de apoio e avaliação da atividade científica. Esse trabalho procura identificar a real atividade do Observatório no conteúdo dos Relatórios Ministeriais que, ao final de cada ano, apresentava as atividades, sucessos e problemas enfrentados pela instituição. Questões como instrumental e recursos humanos necessários; entraves burocráticos e financeiros; e articulações com outros observatórios se complementaram entre si ao longo desses anos para definir o perfil institucional e alguns aspectos fundamentais para a construção da astronomia no país. É possível concluir que a ênfase em serviços geográficos e de meteorologia, ao lado da inadequação dos instrumentos e do local, quase fizeram desaparecer a pesquisa em astronomia. Porém, vale destacar a sobrevivência de alguns trabalhos, como, por exemplo, variação de latitude e observação de estrelas duplas que mantiveram importante intercâmbio com outros grupos de pesquisa, demonstrando o constante esforço dos astrônomos e das diretorias em defesa da atividade científica.

  17. Uso de modelos mecânicos em curso informal de astronomia para deficientes visuais. Resgate de uma experiência

    NASA Astrophysics Data System (ADS)

    Tavares, E. T., Jr.; Klafke, J. C.

    2003-08-01

    O presente trabalho propõe-se a resgatar uma experiência que teve lugar no Planetário de São Paulo nos anos 60. Em 1962, o Sr. Acácio, então com 37 anos, deficiente visual desde os 27, passou a assistir às aulas ministradas pelo Prof. Aristóteles Orsini aos integrantes do corpo de servidores do Planetário. O Sr. Acácio era o único deficiente da turma e, embora possuísse conhecimentos básicos e relativamente avançados de matemática, enfrentava dificuldades na compreensão e acompanhamento da exposição, como também em estudos posteriores. Com o intuito de auxiliá-lo na superação desses problemas, o Prof. Orsini solicitou a construção de modelos mecânicos que, através do sentido do tato, permitissem o acompanhamento das aulas e a transposição do modelo para o "constructo" mental. Essa prática mostrou-se tão eficaz que facilitou sobejamente o aprendizado da matéria pelo sujeito. O Sr. Acácio passou a integrar o corpo de professores do Planetário/Escola Municipal de Astrofísica, tendo ficado responsável pelo curso de "Introdução à Astronomia" por vários anos. Além disso, a experiência foi tão bem sucedida que alguns dos modelos tiveram seus elementos constitutivos pintados diferencialmente para serem utilizados em cursos regulares do Planetário, tornando-se parte integrante do conjunto de recursos didáticos da instituição. É pensando nessa eficácia, tanto em seu objetivo original permitir o aprendizado de um deficiente visual quanto no subsidiário recurso didático sistemático da instituição que decidimos resgatar essa experiência. Estribados nela, acreditamos ser extremamente produtivo, em termos educacionais, o aperfeiçoamento dos modelos originais, agora resgatados e restaurados, e a criação de outros que pudessem ser utilizados no ensino dessa ciência a deficientes visuais.

  18. Identificação de radiofontes puntiformes presentes na região observada pelo telescópio BEAST

    NASA Astrophysics Data System (ADS)

    Oliveira, M. S.; Wuensche, C. A.; Leonardi, R.; Tello, C.

    2003-08-01

    Radiofontes extragalácticas são um dos principais contaminantes nas medidas da Radiação Cósmica de Fundo (RCF) em freqüências abaixo de 200 GHz. O estudo de seu comportamento espectral permite determinar a contribuição destas fontes às anisotropias intrísincas da RCF. Um dos experimentos recentes concebidos para estudar a RCF é o BEAST (Background Emission Anisotropy Scanning Telescope), cujos primeiros resultados foram publicados em fevereiro de 2003. Nos últimos meses, geramos mapas do céu nas freqüências de 30 GHz e 41 GHz, para um total de 648 horas de observação entre julho e outubro de 2002. Identificamos 4 fontes puntiformes extragalácticas na região do céu situada entre 0h < RA < 24 h e +32° < DEC < +42°, com relação S/R > 4,3 e situadas a pelo menos 25° acima do Plano Galáctico. Suas contrapartidas em 5 GHz, segundo o catálogo GB6, são: J1613+3412, J1635+3808, J0927+3902 e J1642+3948. Estas fontes também foram identificadas pelo satélite WMAP sendo que três coincidem com as observadas pelo BEAST dentro da incerteza do feixe do telescópio e a quarta encontra-se bastante próxima (J1613+3412), embora não seja coincidente. As estimativas preliminares de fluxos obtidas para esses objetos são, respectivamente, 0,51; 0,97; 1,08 e 1,6 Jy em 41 GHz. Usando estes resultados e medidas de fluxos em outras frequências existentes na literatura, apresentamos uma estimativa dos índices espectrais destes objetos no intervalo de frequências entre 4,85 GHz e 41 GHz.

  19. Method development for compensating temperature effects in pressure sensitive paint measurements

    NASA Technical Reports Server (NTRS)

    Demandante, Carlo Greg N.

    1994-01-01

    Pressure sensitive luminescent paints (PSP) have recently emerged as a viable technique for aerodynamic pressure measurements. The technique uses a surface coating which contains probe molecules that luminesce when excited by light of an appropriate wavelength. The photoluminescence of these materials is known to be quenched by the presence of molecular oxygen. Since oxygen is a fixed mole fraction of the air, the coating's luminescence intensity varies inversely with air pressure. Digital imaging of the luminescence varying across a coated surface produces a pressure distribution map over that surface. One difficulty encountered with this technique is the temperature effect on the luminescence intensity. Present PSP formulations have significant sensitivity to temperature. At the moment, the most practical way of correcting for temperature effects is to calibrate the paint in place at the operating temperatures by using a few well-placed pressure taps. This study is looking at development of temperature indicating coatings that can be applied and measured concurrently with PSP, and use the temperature measurement to compute the correct pressure. Two methods for this dual paint formulation are proposed. One method will use a coating that consists of temperature sensitive phosphors in a polymer matrix. This is similar in construction to PSP, except that the probe molecules used are selected primarily for their temperature sensitivity. Both organic phosphors (e.g., europium thenoyltrifluoroacetonate, bioprobes) and inorganic phosphors (e.g., Mg4(F)GeO6:Mn, La2O2S:Eu, Radelin Type phosphors, Sylvania Type phosphors) will be evaluated for their temperature sensing potential. The next method will involve a novel coating composing of five membered heterocyclic conducting polymers which are known to show temperature dependent luminescence (e.g., poly(3-alkylthiopene), poly(3-alkylselenophene), poly(3-alkylfuran)). Both methods will involve applying a bottom layer of

  20. The Evolving Universe: Structure and Evolution of the Universe Roadmap 2000-2020

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Roadmap for the Structure and Evolution of the Universe (SEU) theme embraces three fundamental, scientific quests: (1) To explain structure in the Universe and forecast our cosmic destiny. (2) To explore the cycles of matter and energy in the evolving Universe. (3) To examine the ultimate limits of gravity and energy in the Universe. These quests are developed into six, focused research campaigns addressing the objectives of one or more quests: Identify dark matter and learn how it shapes galaxies and systems of galaxies; Find out where and when the chemical elements were made; Understand the cycles in which matter, energy, and magnetic field are exchanged between stars and the gas between stars; Discover how gas flows in disks and how cosmic jets are formed; Identify the sources of gamma-ray bursts and high-energy cosmic rays; and Measure how strong gravity operates near black holes and how it affects the early Universe. These campaigns lead to a portfolio of future major missions of strong scientific and popular appeal, strongly endorsed by the scientific community and which has undergone significant initial study. Some of these missions are in a state of readiness that makes ideal candidates for the present Office of Space Science Strategic Plan; others may well feature in the next Strategic Plan. Each provides a golden scientific opportunity to advance our understanding of the Universe. Our highest priority science objectives are addressed by five Observatory Class Missions, unranked by science, but in approximate order of readiness: A high-energy gamma-ray facility that will observe relativistic jets and study the sources of cosmic gamma ray bursts; An ultra-sensitive X-ray telescope, optimized for spectroscopy, to examine the hot gas linked with clusters of galaxies, the disks around black holes, and supernova explosions; A large, radio telescope in deep space to map central regions of distant quasars and perform astrometric investigations; An orbiting