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1

Neutron radiation hardness of vacuum compatible two-component adhesives  

NASA Astrophysics Data System (ADS)

This paper reports the investigation of the irradiation dependent bonding strength of two-component glues which have low outgassing compatible with vacuum applications. The strength of the glue joints is compared before and after exposure to a thermal neutron fluence of 2.35×10 neutrons per cm. The goal of this work is to establish a glue which is applicable to join glass and metal parts of the ultra-cold neutron (UCN) guide system at the Paul Scherrer Institute's UCN source.

Bertsch, J.; Goeltl, L.; Kirch, K.; Lauss, B.; Zubler, R.

2009-04-01

2

Radiation from hard objects  

SciTech Connect

The inference of the diameter of hard objects is insensitive to radiation efficiency. Deductions of radiation efficiency from observations are very sensitive - possibly overly so. Inferences of the initial velocity and trajectory vary similarly, and hence are comparably sensitive.

Canavan, G.H.

1997-02-01

3

GfW handbook: Irradiation test guidelines for radiation hardness of electronic components  

Microsoft Academic Search

Irradiation test methods and standardized application are proposed, in order to improve comparison of test results. The interaction of different radiation species with matter (ionization and displacement) is described. Application of appropriate radiation sources, dosimetry problems, and sheilding for simulating space radiation effects by laboratory testing are discussed. Irradiation sources are characterized. Flowcharts of the planning and running of irradiation

D. Braeunig; F. Wulf; W. Gaebler; A. Boden

1982-01-01

4

GfW handbook: Irradiation test guidelines for radiation hardness of electronic components  

NASA Astrophysics Data System (ADS)

Irradiation test methods and standardized application are proposed, in order to improve comparison of test results. The interaction of different radiation species with matter (ionization and displacement) is described. Application of appropriate radiation sources, dosimetry problems, and sheilding for simulating space radiation effects by laboratory testing are discussed. Irradiation sources are characterized. Flowcharts of the planning and running of irradiation tests are given. Guidelines for running the tests are established. The test system can handle devices of high complexity, up to microprocessors.

Braeunig, D.; Wulf, F.; Gaebler, W.; Boden, A.

1982-12-01

5

Radiation Hardness of Trigger Electronics  

NASA Astrophysics Data System (ADS)

As the maximum intensity of particle accelerators increases, probing the most basic questions of the Universe, detectors and electronics must be designed to insure reliability in high-radiation environments. As the Large Hadron Collider (LHC) beam intensity is increased, it is necessary to upgrade the electronics in the Compact Muon Solenoid (CMS). To select interesting events, CMS utilizes fast electronics, which are installed in the experimental cavern. However, much higher post-upgrade levels of radiation in the cavern set tight requirements on the radiation hardness of the new electronics. Damaging effects of high and low energy radiation leads to disruption of digital circuits and accumulated degradation of silicon components. Quantifying the radiation exposure is required for the design of a radiation-tolerant system, but current simulation studies suffer from large uncertainties. We compare simulation predictions with measured performance in two different experimental studies, which evaluate component performance for pre and post irradiation determining the survivability of electronics in the harsh CMS environment.

Zawisza, Irene; Safonov, Alexei; Gilmore, Jason; Khotilovich, Vadim

2011-10-01

6

Radiation Hard Fiber Optics.  

National Technical Information Service (NTIS)

A study of radiation-inducted absorption in low-loss optical waveguides is reported. Step-index optical fibers were prepared from preforms fabricated by the CVD method. The germanium silicate core glass in the fibers was doped with varying amounts of anti...

R. E. Jaeger M. Aslami

1981-01-01

7

Radiation Hard Silicon Nanowire Field Effect Transistors  

Microsoft Academic Search

Silicon nanowire-based transistors were fabricated and tested for their radiation hardness by exposure to Co60 X-ray radiation at doses ranging from 50-250 kRad. Minor degradation of the transistor characteristics was observed at 250 kRad. Our results show the inherent radiation hardness of nanowire devices.

L. Tsakalakos; P. Losee; J. Balch; A. L. Bogorad; W. J. Taft; J. J. Likar; R. Herschitz

2008-01-01

8

Automated radiation hard ASIC design tool  

NASA Technical Reports Server (NTRS)

A commercial based, foundry independent, compiler design tool (ChipCrafter) with custom radiation hardened library cells is described. A unique analysis approach allows low hardness risk for Application Specific IC's (ASIC's). Accomplishments, radiation test results, and applications are described.

White, Mike; Bartholet, Bill; Baze, Mark

1993-01-01

9

Radiation hardness of CMS pixel barrel modules  

NASA Astrophysics Data System (ADS)

Pixel detectors are used in the innermost part of the multi purpose experiments at the LHC and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of all detector components has been thoroughly tested up to the fluences expected at the LHC. In case of an LHC upgrade, the fluence will be much higher and it is not yet clear how long the present pixel modules will stay operative in such a harsh environment. The aim of this study was to establish such a limit as a benchmark for other possible detector concepts considered for the upgrade. As the sensors and the readout chip are the parts most sensitive to radiation damage, samples consisting of a small pixel sensor bump-bonded to a CMS-readout chip (PSI46V2.1) have been irradiated with positive 200 MeV pions at PSI up to 6×1014 neq/cm2 and with 21 GeV protons at CERN up to 5×1015 neq/cm2. After irradiation the response of the system to beta particles from a 90Sr source was measured to characterise the charge collection efficiency of the sensor. Radiation induced changes in the readout chip were also measured. The results show that the present pixel modules can be expected to be still operational after a fluence of 2.8×1015 neq/cm2. Samples irradiated up to 5×1015 neq/cm2 still see the beta particles. However, further tests are needed to confirm whether a stable operation with high particle detection efficiency is possible after such a high fluence.

Rohe, T.; Bean, A.; Erdmann, W.; Kästli, H.-C.; Khalatyan, S.; Meier, B.; Radicci, V.; Sibille, J.

2010-12-01

10

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, ...

F. Markley M. Davidson J. Keller G. Foster A. Pla-Dalmau

1993-01-01

11

Review of radiation hard electronics activities at European Space Agency  

NASA Astrophysics Data System (ADS)

Several Research and Development activities are ongoing at European Space Agency [1] to secure the supply of key electronic parts for current and future space avionics systems. Analogously to astro-particle and high-energy physics, the space missions radiation environment drives the radiation hardness requirements, which limits availability of suitable electronic components. In particular for the future ESA flagship Jupiter science mission, the necessary processing, reliability, mass, power performance requirements are difficult to meet with current components and systems with sufficient radiation tolerance margins. Improved radiation characterisation and modelling of the Jupiter radiation environment as well as operational radiation monitoring during the mission will be key in ensuring adequate margins for the operation of electronic components.

Furano, G.; Jansen, R.; Menicucci, A.

2013-02-01

12

Radiation Hardness Assurance for Space Systems  

NASA Technical Reports Server (NTRS)

The space radiation environment can lead to extremely harsh operating conditions for on-board electronic box and systems. The characteristics of the radiation environment are highly dependent on the type of mission (date, duration and orbit). Radiation accelerates the aging of the electronic parts and material and can lead to a degradation of electrical performance; it can also create transient phenomena on parts. Such damage at the part level can induce damage or functional failure at electronic box, subsystem, and system levels. A rigorous methodology is needed to ensure that the radiation environment does not compromise the functionality and performance of the electronics during the system life. This methodology is called hardness assurance. It consists of those activities undertaken to ensure that the electronic piece parts placed in the space system perform to their design specifications after exposure to the space environment. It deals with system requirements, environmental definitions, part selection, part testing, shielding and radiation tolerant design. All these elements should play together in order to produce a system tolerant to.the radiation environment. An overview of the different steps of a space system hardness assurance program is given in section 2. In order to define the mission radiation specifications and compare these requirements to radiation test data, a detailed knowledge of the space environment and the corresponding electronic device failure mechanisms is required. The presentation by J. Mazur deals with the Earth space radiation environment as well as the internal environment of a spacecraft. The presentation by J. Schwank deals with ionization effects, and the presentation by T. Weatherford deals with Single particle Event Phenomena (SEP) in semiconductor devices and microcircuits. These three presentations provide more detailed background to complement the sections 3 and 4. Part selection and categorization are discussed in section 5. Section 6 presents the organization of the hardness assurance within a project. Section 7 discusses emerging radiation hardness assurance issues.

Poivey, Christian; Day, John H. (Technical Monitor)

2002-01-01

13

Development of radiation hard scintillators  

SciTech Connect

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, so they decided to make the scintillators directly from monomer where the base resin could be easily crosslinked to improve the mechanical properties. They can now demonstrate that scintillators made directly from the monomer, using both styrene and 4-methyl styrene, are also much more radiation resistant when modified with DC705 oil. In fact, they retain from 92% to 95% of their original light output after gamma irradiation to 10 Mrads in nitrogen with air annealing. When these scintillators made directly from monomer are compared with scintillators of the same composition made from polymer the latter have much higher light outputs. They commonly reach 83% while those made form monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetraphenylbutadiene are compared with identical scintillators except that they use 3 hydroxy-flavone as the only luminophore the radiation stability is the same. However the 3HF system gives only 30% as much light as BC408 instead of 83% when both are measured with a green extended Phillips XP2081B phototube.

Markley, F.; Davidson, M.; Keller, J.; Foster, G.; Pla-Dalmau, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Harmon, J.; Biagtan, E.; Schueneman, G. [Univ. of Florida, Gainesville, FL (United States). Physics Dept.; Senchishin, V. [Inst. for Single Crystals, Kharkov (Ukraine); Gustfason, H.; Rivard, M. [Univ. of Michigan, Ann Arbor, MI (United States)

1993-11-01

14

Characterization of Radiation Hard Silicon Materials  

SciTech Connect

Segmented silicon detectors are widely used in modern high-energy physics (HEP) experiments due to their excellent spatial resolution and well-established manufacturing technology. However, in such experiments the detectors are exposed to high fluences of particle radiation, which causes irreversible crystallographic defects in the silicon material. Since 1990's, considerable amount of research has gone into improving the radiation hardness of silicon detectors. One very promising approach is to use magnetic Czochralski silicon (MCz-Si) that has been found to be more radiation hard against charged hadrons than traditional Float Zone silicon material (Fz-Si) used in the current HEP applications. Other approaches include operating the devices at cryogenic temperatures and designing special detector structures such as p-type detectors or semi-3D detectors. In order to demonstrate that the developed technologies are suitable for the HEP experiments, it is necessary to extensively characterize the potentially radiation hard detectors. We have an excellent instrument for this, the Cryogenic Transient Current Technique (C-TCT) measurement setup, which is an effective research tool for studying heavily irradiated silicon detectors. With the C-TCT setup it is possible to extract the full depletion voltage, effective trapping time, electric field distribution and the sign of the space charge in the silicon bulk in the temperature range of 45-300 K. This articles presents a description of this setup and measurement results from detectors processed of MCz-Si.

Luukka, P.; Li, Z.; J. Harkonen, E. Tuovinen, S. Czellar, V. Eremin, E. Tuominen, E. Verbitskaya

2009-02-24

15

Radiation-hard/high-speed data transmission using optical links  

NASA Astrophysics Data System (ADS)

The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgraded LHC with ten times higher luminosity. We investigate the radiation-hardness of various components for possible application in the data transmission upgrade. We study the radiation-hardness of VCSELs (Vertical-Cavity Surface-Emitting Laser) and GaAs and silicon PINs from various sources using 24 GeV/c protons at CERN. The optical power of VCSEL arrays decreases significantly after the irradiation but can be partially annealed with high drive currents. The responsivities of the PIN diodes also decrease significantly after irradiation, especially for the GaAs devices. We have designed the ASICs for the opto-link applications and find that the degradation with radiation is acceptable.

Gan, K. K.; Abi, B.; Fernando, W.; Kagan, H. P.; Kass, R. D.; Lebbai, M. R. M.; Moore, J. R.; Rizatdinova, F.; Skubic, P. L.; Smith, D. S.

2009-12-01

16

Radiation Hardness Assurance (RHA) for Space Systems  

NASA Technical Reports Server (NTRS)

This presentation discusses radiation hardness assurance (RHA) for space systems, providing both the programmatic aspects of RHA and the RHA procedure. RHA consists of all activities undertaken to ensure that the electronics and materials of a space system perform to their design specifications after exposure to the space radiation environment. RHA also pertains to environment definition, part selection, part testing, spacecraft layout, radiation tolerant design, and mission/system/subsystems requirements. RHA procedure consists of establishing mission requirements, defining and evaluating the radiation hazard, selecting and categorizing the appropriate parts, and evaluating circuit response to hazard. The RHA approach is based on risk management and is confined only to parts, it includes spacecraft layout, system/subsystem/circuit design, and system requirements and system operations. RHA should be taken into account in the early phases of a program including the proposal and feasibility analysis phases.

Poivey, Christian; Buchner, Stephen

2007-01-01

17

Radiation Hardness Assurance Testing of Microelectronic Devices and Integrated Circuits: Radiation Environments, Physical Mechanisms, and Foundation for Hardness Assurance.  

National Technical Information Service (NTIS)

This document describes the radiation environments, physical mechanisms, and test philosophies that underpin the radiation hardness assurance test methodologies presented in Parts A and B. The natural space radiation environment is presented, including th...

J. R. Schwank M. R. Shaneyflet P. E. Dodd

2008-01-01

18

Fault-Tolerant, Radiation-Hard DSP  

NASA Technical Reports Server (NTRS)

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-performance signal processing include significant increase in onboard science data processing, enabling orders of magnitude reduction in required communication bandwidth for science data return, orders of magnitude improvement in onboard mission planning and critical decision making, and the ability to rapidly respond to changing mission environments, thus enabling opportunistic science and orders of magnitude reduction in the cost of mission operations through reduction of required staff. Additional benefits of COTS-based, high-performance signal processing include the ability to leverage considerable commercial and academic investments in advanced computing tools, techniques, and infra structure, and the familiarity of the science and IT community with these computing environments.

Czajkowski, David

2011-01-01

19

Radiation hardness of VA1 with submicron process technology  

Microsoft Academic Search

We have studied the radiation hardness of the VA1, a Viking-architecture preamplifier VLSI chip. Large-scale integrated (LSI) samples are fabricated in 0.8 and 0.35 ?m process technologies to improve the radiation hardness of the LSI for the Belle silicon vertex detector upgrade. We have observed significant improvement of the radiation hardness with 0.8-?m technology compared to 1.2-?m technology. Little degradation

M. Yokoyama; H. Aihara; M. Hazumi; H. Ishino; J. Kaneko; Y. Li; D. Marlow; S. Mikkelsen; E. Nygard; H. Tajima; J. Talebi; G. Verner; H. Yamamoto

2001-01-01

20

Radiation hardness of the LHCb Outer Tracker  

NASA Astrophysics Data System (ADS)

This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3 fb-1 of integrated luminosity corresponding to an integrated charge of 0.055 C/cm in the hottest spot of the detector.

van Eijk, D.; Bachmann, S.; Bauer, Th.; Färber, Ch.; Bien, A.; Coco, V.; Deckenhoff, M.; Dettori, F.; Ekelhof, R.; Gersabeck, E.; Karbach, T. M.; Koopman, R.; Kozlinskiy, A.; Langenbruch, Ch.; Linn, Ch.; Merk, M.; Meissner, M.; Morawski, P.; Pellegrino, A.; Serra, N.; Seyfert, P.; Spaan, B.; Swientek, S.; Storaci, B.; Szczekowski, M.; Tuning, N.; Uwer, U.; Visser, E.; Wiedner, D.; Witek, M.

2012-09-01

21

Radiation hardness of COTS EPROMs and E2PROMs  

NASA Astrophysics Data System (ADS)

This paper examines and compares the effects of exposing commercial, off the shelf erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (E2PROM) components to gamma rays. Results obtained for CMOS-based EPROM (NM27C010) and E2PROM (NM93CS46) components provide evidence that EPROMs have a greater radiation hardness than E2PROMs. Moreover, the changes in EPROMs are reversible, and after erasure and reprogramming all EPROM components restore their functionality. On the other hand, changes in E2PROMs are irreversible. The obtained results are analyzed and interpreted on the basis of gamma ray interaction with the CMOS structure.

Vujisi?, Miloš; Stankovi?, Koviljka; Doli?anin, Edin; Osmokrovi?, Predrag

22

High efficiency, radiation-hard solar cells  

SciTech Connect

The direct gap of the In{sub 1-x}Ga{sub x}N alloy system extends continuously from InN (0.7 eV, in the near IR) to GaN (3.4 eV, in the mid-ultraviolet). This opens the intriguing possibility of using this single ternary alloy system in single or multi-junction (MJ) solar cells of the type used for space-based surveillance satellites. To evaluate the suitability of In{sub 1-x}Ga{sub x}N as a material for space applications, high quality thin films were grown with molecular beam epitaxy and extensive damage testing with electron, proton, and alpha particle radiation was performed. Using the room temperature photoluminescence intensity as a indirect measure of minority carrier lifetime, it is shown that In{sub 1-x}Ga{sub x}N retains its optoelectronic properties at radiation damage doses at least 2 orders of magnitude higher than the damage thresholds of the materials (GaAs and GaInP) currently used in high efficiency MJ cells. This indicates that the In{sub 1-x}Ga{sub x}N is well-suited for the future development of ultra radiation-hard optoelectronics. Critical issues affecting development of solar cells using this material system were addressed. The presence of an electron-rich surface layer in InN and In{sub 1-x}Ga{sub x}N (0 < x < 0.63) was investigated; it was shown that this is a less significant effect at large x. Evidence of p-type activity below the surface in Mg-doped InN was obtained; this is a significant step toward achieving photovoltaic action and, ultimately, a solar cell using this material.

Ager III, J.W.; Walukiewicz, W.

2004-10-22

23

Radiation effects on eye components  

NASA Astrophysics Data System (ADS)

The most important water-soluble components of the vertebrate eye (lens proteins, aqueous humor, vitreous, hyaluronic acid, ascorbic acid) have been investigated in aqueous solution, after preceding X- or UV-irradiation. Spectroscopic, chromatographic, electrophoretic, hydrodynamic and analytic techniques have been applied, to monitor several radiation damages such as destruction of aromatic and sulfur-containing amino acids, aggregation, crosslinking, dissociation, fragmentation, and partial unfolding. Various substances were found which were able to protect eye components effectively against radiation, some of them being also of medical relevance.

Durchschlag, H.; Fochler, C.; Abraham, K.; Kulawik, B.

1999-08-01

24

Development of a radiation-hard photomultiplier tube  

NASA Technical Reports Server (NTRS)

In a radiation-hard photomultiplier tube (PMT) such as has been developed for stabilization of the Galileo spacecraft as it goes through the Jovian high energy radiation belts, the primary effects of high energy electron and proton radiation that must be resisted are the production of fluorescence and Cerenkov emission. The present PMT envelope is ceramic rather than glass, and employs a special, electron-focusing design which will collect, accelerate and amplify electrons only from desired photocathode areas. Tests in a Co-60 radiation facility have shown that the radiation-hard PMT produces less than 2.5 percent of the radiation noise of a standard PMT.

Birnbaum, M. M.; Bunker, R. L.; Roderick, J.; Stephenson, K.

1984-01-01

25

Measuring the radiation field and radiation hard detectors at JET: Recent developments  

NASA Astrophysics Data System (ADS)

Since in ITER the radiation field will be much more demanding than that of present day devices, research programmes at JET are aimed at developing radiation hard diagnostics and related components. Initially, significant efforts are devoted to determining the radiation field of both the plasma and in the immediate environment with better accuracy. New developments in MCNP calculations and dedicated measurements provide useful information about the radiation field in the Torus Hall, even during non-operational periods. The effect of using Beryllium in the near future for JET first wall, is being assessed. New materials for activation samples are under consideration and will be tested to improve the calibration accuracy of JET neutron diagnostics. The long-term goal of this work is to obtain spectrometric information from an appropriate combination of different materials. Several studies are under way to modify the radiation field at the detectors by using LiH or pure water as neutron filters, to alleviate the problem of the background in ?-ray measurements. A suite of radiation hard detectors for neutrons, magnetic field and charged particles are being developed. Super-heated fluid neutron detectors, used for yield and imaging, are being upgraded, in order to provide a broad-band spectrometric capability. Chemical vapour deposited diamond diodes are being qualified as counters and as spectrometers. Prototypes of Hall probes made of InSb have been installed on the machine and have provided some preliminary results. Si-on-insulator detectors are under development for use in neutral particle analysers and are currently being bench-tested. Some attention is being devoted to optical components, fibres and mirrors, and to investigating radiation hard electronics using reconfigurable Field Programmable Gate Arrays.

Murari, A.; Edlington, T.; Angelone, M.; Bertalot, L.; Bolshakova, I.; Bonheure, G.; Brzozowski, J.; Coccorese, V.; Holyaka, R.; Kiptily, V.; Lengar, I.; Morgan, P.; Pillon, M.; Popovichev, S.; Prior, P.; Prokopowicz, R.; Quercia, A.; Rubel, M.; Santala, M.; Shevelev, A.; Syme, B.; Vagliasindi, G.; Villari, R.; Zoita, V. L.; JET-EFDA Contributors

26

Development of a radiation-hard photomultiplier tube  

Microsoft Academic Search

In a radiation-hard photomultiplier tube (PMT) such as has been developed for stabilization of the Galileo spacecraft as it goes through the Jovian high energy radiation belts, the primary effects of high energy electron and proton radiation that must be resisted are the production of fluorescence and Cerenkov emission. The present PMT envelope is ceramic rather than glass, and employs

M. M. Birnbaum; R. L. Bunker; J. Roderick; K. Stephenson

1984-01-01

27

GaN as a radiation hard particle detector  

Microsoft Academic Search

Semiconductor tracking detectors at experiments such as ATLAS and LHCb at the CERN Large Hadron Collider (LHC) will be subjected to intense levels of radiation. The proposed machine upgrade, the Super-LHC (SLHC), to 10 times the initial luminosity of the LHC will require detectors that are ultra-radiation hard. Much of the current research into finding a detector that will meet

J. Grant; R. Bates; W. Cunningham; A. Blue; J. Melone; F. McEwan; J. Vaitkus; E. Gaubas; V. O’Shea

2007-01-01

28

Radiation hardness tests performed high gamma field sources. ... measured survive ionizing radiation order Murad survive ...... en Dependence transmission coefficients CCl crystals collared hard .  

EPA Pesticide Factsheets

Did you mean: Radiation hardness tests performed high gamma field sources. ... measured survive ionizing radiation order Murad survive ...... en Dependence transmission coefficients CCl crystals collared hard . ?

29

Radiation-hard optical link for SLHC  

NASA Astrophysics Data System (ADS)

We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via rad-hard SIMM fibres spliced to rad-tolerant GRIN fibres. The link has several nice features. We have measured the bandwidths of the micro twisted-pair cables to be bsim 1 Gb/s and the fusion spliced fibre ribbon to be bsim 2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find the arrays survive to the SLHC dosage. We have also demonstrated the feasibility of fabricating a novel opto-pack for housing VCSEL and PIN arrays with BeO as the substrate.

Gan, K. K.; Abi, B.; Fernando, W.; Kagan, H. P.; Kass, R. D.; Law, A.; Lebbai, M. R. M.; Rau, A.; Rizardinova, F.; Skubic, P. L.; Smith, D. S.

2008-05-01

30

Emerging radiation hardness assurance (RHA) issues: a NASA approach for space flight programs  

Microsoft Academic Search

Spacecraft performance requirements drive the utilization of commercial-off-the-shelf (COTS) components and emerging technologies in systems. The response of these technologies to radiation is often complex. This engenders a set of emerging radiation hardness assurance (RHA) issues which include displacement damage in optocouplers, high-precision and hybrid devices, enhanced low dose rate (ELDR) and proton damage enhancement (PDE) in linear circuits, linear

Kenneth A. LaBel; Allan H. Johnston; Janet L. Barth; Robert A. Reed; Charles E. Barnes

1998-01-01

31

Radiation hard diamond laser beam profiler with subnanosecond temporal resolution  

Microsoft Academic Search

A two-dimensional detector array has been fabricated from a single 10-mm-diam by 100-mum-thick chemical vapor deposition diamond disk by applying a 1×1 mm2 metallization grid of 4×4 pixels with centered bias connections. This diamond has been exposed to high power pulsed laser radiation. It has been shown that this kind of diamond array operates as a radiation hard, ultrafast laser

J. Schein; K. M. Campbell; R. R. Prasad; R. Binder; M. Krishnan

2002-01-01

32

Radiation-hard electrical coil and method for its fabrication  

Microsoft Academic Search

A radiation-hard insulated electrical coil and method for making the same are disclosed. In accordance with the method, a conductor, preferably copper, is wrapped with an aluminum strip and then tightly wound into a coil. The aluminum-wrapped coil is then annealed to relax the conductor in the coiled configuration. The annealed coil is then immersed in an alkaline solution to

R. J. Grieggs; R. D. Blake; F. D. Gac

1982-01-01

33

Curve Fitting Solar Cell Degradation Due to Hard Particle Radiation  

NASA Technical Reports Server (NTRS)

This paper investigates the suitability of the equation for accurately defining solar cell parameter degradation as a function of hard particle radiation. The paper also provides methods for determining the constants in the equation and compares results from this equation to those obtained by the more traditionally used.

Gaddy, Edward M.; Cikoski, Rebecca; Mekadenaumporn, Danchai

2003-01-01

34

Investigation of Radiation Hardness of Germanium Photovoltaic Cells  

Microsoft Academic Search

This contribution discusses the radiation hardness of germanium (Ge) photovoltaic cells under space conditions corresponding to an irradiation dose of 1-MeV 1 × 1015 cm-2 electrons. For this purpose, different germanium photovoltaic cell technologies based on p-type substrates are analyzed. The investigation comprises standard Ge photovoltaic cells with a substrate doping concentration of NA = 1 × 1017 cm-3, as

Raymond Hoheisel; Jara Fernandez; Frank Dimroth; Andreas W. Bett

2010-01-01

35

Solar cell nanotechnology for improved efficiency and radiation hardness  

Microsoft Academic Search

Space electronic equipment, and NASA future exploration missions in particular, require improvements in solar cell efficiency and radiation hardness. Novel nano-engineered materials and quantum-dot array based photovoltaic devices promise to deliver more efficient, lightweight solar cells and arrays which will be of high value to long term space missions. In this paper, we describe issues related to the development of

Alexander I. Fedoseyev; Marek Turowski; Qinghui Shao; Alexander A. Balandin

2006-01-01

36

Silicon carbide devices for radiation hard applications  

SciTech Connect

Silicon carbide has long been recognized as a favorable material for applications at high temperatures and in radiation environments, but device development has been hindered by lack of adequate substrates. This paper reviews the current Westinghouse material development effort aimed at the growth of high quality 6H boules and describes 6H SiC devices fabricated on Westinghouse substrates. MESFET and MOSFET transistors were made in a microwave power design layout. The MESFET and MOSFET transistors were subjected to a total gamma irradiation of 1 megaGray (100 megarad) and exhibited threshold voltage shifts of about 0.4 and 1.2 Volts respectively with little change in bulk material parameters.

McMullin, P.G.; Barrett, D.L.; Hopkins, R.H.; Spitznagel, J.A. (Westinghouse Sciences and Technology Center, 1310 Beulah Road, Pittsburgh, Pennsylvania 15235 (United States)); Powell, J.A. (NASA Lewis Research Center, 21000 Brookpark Road, Cleveland Ohio 44135 (United States)); Thome, F.V. (Sandia National Laboratory, Albuquerque, New Mexico 87123 (United States))

1993-01-15

37

Radiation Hard 0.25 Micron CMOS Library at IHP  

NASA Astrophysics Data System (ADS)

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.

Jagdhold, U.

2008-08-01

38

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak.  

PubMed

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points--three TLDs per point--to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak. PMID:24880371

Rasouli, C; Pourshahab, B; Hosseini Pooya, S M; Orouji, T; Rasouli, H

2014-05-01

39

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak  

NASA Astrophysics Data System (ADS)

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points - three TLDs per point - to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Rasouli, C.; Pourshahab, B.; Hosseini Pooya, S. M.; Orouji, T.; Rasouli, H.

2014-05-01

40

Cryogenic Si detectors for ultra radiation hardness in SLHC environment  

NASA Astrophysics Data System (ADS)

Radiation hardness up to 10 16 neq/cm 2 is required in the future HEP experiments for most inner detectors. However, 10 16 neq/cm 2 fluence is well beyond the radiation tolerance of even the most advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20-30 ?m regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10 16 neq/cm 2). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (?230 K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN 2 temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN 2 temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical cryogenic temperature range that can be used to freeze out the radiation-induced trapping levels, and it is ready for measurements on extremely heavily irradiated silicon detectors. Initial data from this system will be presented.

Li, Zheng; Abreu, M.; Anbinderis, P.; Anbinderis, T.; Ambrosio, N. D.'.; de Boer, W.; Borchi, E.; Borer, K.; Bruzzi, M.; Buontempo, S.; Chen, W.; Cindro, V.; Dierlamm, A.; Eremin, V.; Gaubas, E.; Gorbatenko, V.; Grigoriev, E.; Hauler, F.; Heijne, E.; Heising, S.; Hempel, O.; Herzog, R.; Härkönen, J.; Ilyashenko, I.; Janos, S.; Jungermann, L.; Kalesinskas, V.; Kapturauskas, J.; Laiho, R.; Luukka, P.; Mandic, I.; De Masi, Rita; Menichelli, D.; Mikuz, M.; Militaru, O.; Niinikosky, T. O.; Shea, V. O.'.; Pagano, S.; Paul, S.; Piotrzkowski, K.; Pretzl, K.; Rato Mendes, P.; Rouby, X.; Ruggiero, G.; Smith, K.; Sonderegger, P.; Sousa, P.; Tuominen, E.; Tuovinen, E.; Verbitskaya, E.; Vaitkus, J.; Wobst, E.; Zavrtanik, M.

2007-09-01

41

Development of Radiation Hard Silicon Detectors:. the Smart Project  

NASA Astrophysics Data System (ADS)

The research actitvity of the SMART project, a collaboration of Italian research institutes funded by the I.N.F.N., has been focused on the development of radiation hard silicon position sensitive detectors for the CERN Large Hadron Collider luminosity upgrade. Electrical characterization of pad and micro-strip devices as well as study of microscopic defects on the bulk material have been carried out on silicon 4" wafers of n- and p-type, grown with Standard Float Zone (SFz), high resistivity Magnetic Czochralski (MCz) and epitaxial (EPI) techniques. Manufactured devices have been irradiated with 24 GeV/c and 26 MeV protons up to ~ 3·1015 cm-2 1 MeV neutrons eq. (neq/cm2) and with reactor neutrons up to ~8·1015 neq/cm2. Preliminary results of measurements before and after irradiations as well as material radiation hardness are shown and discussed.

Messineo, A.; Borrello, L.; Segneri, G.; Sentenac, D.; Creanza, D.; Depalma, M.; Manna, N.; Radicci, V.; Borchi, E.; Bruzzi, M.; Focardi, E.; Macchiolo, A.; Menichelli, D.; Scaringella, M.; Tosi, C.; Bisello, D.; Candelori, A.; Khomenkov, V.; Petasecca, M.; Pignatel, G. U.; Boscardin, M.; Dalla Betta, G.-F.; Piemonte, C.; Ronchin, S.; Zorzi, N.

2006-04-01

42

3D silicon detectors and radiation hardness issues  

Microsoft Academic Search

3D silicon technology is a new way to make silicon detectors using Micro-Electro-Mechanical-Systems (MEMS) processing. In this innovative design the electrodes penetrate throughout the silicon bulk perpendicular to the surface. Radiation hardness of 3D and planar devices is compared. A formalism describing the dependence of charge collection efficiency on fluence is derived and compared with data. It is shown to

C. DaVia; G. Anelli; J. Hasi; P. Jarron; C. Kenney; A. Kok; S. Parker; S. J. Watts

2005-01-01

43

Solar cell nanotechnology for improved efficiency and radiation hardness  

NASA Astrophysics Data System (ADS)

Space electronic equipment, and NASA future exploration missions in particular, require improvements in solar cell efficiency and radiation hardness. Novel nano-engineered materials and quantum-dot array based photovoltaic devices promise to deliver more efficient, lightweight solar cells and arrays which will be of high value to long term space missions. In this paper, we describe issues related to the development of the quantum-dot based solar cells and comprehensive software tools for simulation of the nanostructure-based photovoltaic cells. Some experimental results used for the model validation are also reviewed. The novel modeling and simulation tools for the quantum-dot-based nanostructures help to better understand and predict behavior of the nano-devices and novel materials in space environment, assess technologies, devices, and materials for new electronic systems as well as to better evaluate the performance and radiation response of the devices at an early design stage. The overall objective is to investigate and design new photovoltaic structures based on quantum dots (QDs) with improved efficiency and radiation hardness. The inherently radiation tolerant quantum dots of variable sizes maximize absorption of different light wavelengths, i.e., create a "multicolor" cell, which improves photovoltaic efficiency and diminishes the radiation-induced degradation. The QD models described here are being integrated into the advanced photonic-electronic device simulator NanoTCAD, which can be useful for the optimization of QD superlattices as well as for the development and exploring of new solar cell designs.

Fedoseyev, Alexander I.; Turowski, Marek; Shao, Qinghui; Balandin, Alexander A.

2006-09-01

44

The Hard Components of Scattered Gamma-Rays  

Microsoft Academic Search

A summary is given of theoretical information on the three processes by which gamma-rays can be elastically scattered by atoms, viz. Rayleigh scattering by bound electrons, Thomson scattering by the nuclear charge and (exceptionally) nuclear resonant scattering.Interference between the three scattered waves is considered and shown to be of practical importance as between Rayleigh and Thomson scattering of hard gamma-rays

P B Moon

1950-01-01

45

Radiation Hardness of PHENIX Muon Trigger Resistive Plate Chambers  

NASA Astrophysics Data System (ADS)

The measurement of quark and anti-quark helicity distributions through parity violating single spin asymmetries in W-production with the PHENIX experiment at RHIC requires new fast muon trigger detectors. PHENIX utilizes Bakelite RPC technology that has been developed for the CMS experiment at LHC. These new detectors will collect data for many years, and it is important to understand the impact the constant radiation exposure in PHENIX will have on the performance of the detectors. Prototype RPCs were exposed to two 0.6 mCi Fe-55 sources that were embedded in the detector gas. The RPC efficiency for cosmic ray detection was measured as a function of the total radiation dose exposure using a cosmic ray tracking detector at UIUC. This poster will discuss the radiation hardness of PHENIX Bakelite RPC prototypes, and how the results compare to the requirements at RHIC.

Ide, Justine

2009-10-01

46

Radiation-hard electrical coil and method for its fabrication  

DOEpatents

A radiation-hard insulated electrical coil and method for making the same are disclosed. In accordance with the method, a conductor, preferably copper, is wrapped with an aluminum strip and then tightly wound into a coil. The aluminum-wrapped coil is then annealed to relax the conductor in the coiled configuration. The annealed coil is then immersed in an alkaline solution to dissolve the aluminum strip, leaving the bare conductor in a coiled configuration with all of the windings closely packed yet uniformly spaced from one another. The coil is then insulated with a refractory insulating material. In the preferred embodiment, the coil is insulated by coating it with a vitreous enamel and subsequently potting the enamelled coil in a castable ceramic concrete. The resulting coil is substantially insensitive to radiation and may be operated continuously in high radiation environments for long periods of time.

Grieggs, R.J.; Blake, R.D.; Gac, F.D.

1982-06-29

47

Application of hardness-by-design methodology to radiation-tolerant ASIC technologies  

Microsoft Academic Search

Radiation-hard ASIC design is enabled by the trend in commercial microelectronics toward increased radiation hardness, demonstrated here with new radiation results on a 0.25-?m commercial process utilizing shallow trench isolation. A design comparison is made between creating ASICs targeting a traditional rad-hard foundry, which may be more than two generations behind commercial foundries, applying hardness-by-design methodology at a commercial foundry,

Ronald C. Lacoe; Jon V. Osborn; Rocky Koga; Stephanie Brown; Donald C. Mayer

2000-01-01

48

Impact of Radiation Hardness and Operating Temperatures of Silicon Carbide Electronics on Space Power System Mass  

NASA Technical Reports Server (NTRS)

The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kW(e) , 1 MW(e), and 10 MW(e)) for near term technology ( i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature Gas Reactor (HTGR) heat source. The study was conducted for assumed PC radiator temperatures ranging from 370 to 845 K and for three scenarios of electrical energy to heat conversion levels which needed to be rejected to space by means of the PC radiator. In addition, during part of the study the radiation hardness of the PC electronics was varied at a fixed separation distance to estimate its effect on the mass of the instrument rated reactor shadow shield. With both the PC radiator and the conical shadow shield representing major components of the overall power system the influence of the above on total power system mass was also determined. As expected, results show that the greatest actual mass savings achieved by the use of SiC electronics occur with high capacity power systems. Moreover, raising the PC radiator temperature above 600 K yields only small additional system mass savings. The effect of increased radiation hardness on total system mass is to reduce system mass by virtue of lowering the shield mass.

Juhasz, Albert J.; Tew, Roy C.; Schwarze, Gene E.

1998-01-01

49

Laser radiation propagation in the hard and soft dental tissues  

NASA Astrophysics Data System (ADS)

The objective of this study was to compare the penetration effect of the near and mid-infrared laser radiation. For this reason the Er:YAG, Nd:YAG, and alexandrite laser systems were used in the experiments. The spread of the laser radiation energy in the hard dental tissue surrounding the root canal was evaluated and the possible bactericidal effect of these various laser wavelengths was analyzed. During the measurements, three experimental arrangements were used. The energy transport through the tooth tissue was observed for the frontal and side experimental layout. It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully, and the Nd:YAG is partly absorbed in the root canal's wall. On the other hand, it was proved that the alexandrite laser radiation spreads through the canal system space and leaks into the surrounding tooth tissues. All laser radiation can be efficiently used for killing dental bacteria but the spreading of their radiation in the tooth tissues is different.

Dostalova, Tat'jana; Jelinkova, Helena; Sulc, Jan; Cerny, Pavel; Nemec, Michal; Cech, Miroslav; Miyagi, Mitsunobu

2000-03-01

50

Statistical Mechanics of a One-Component Fluid of Charged Hard Rods in 1D.  

National Technical Information Service (NTIS)

The statistical mechanics of a classical one component system of charged hard rods in a neutralizing background is investigated in 1D stressing on the effects of the hard core interactions over the thermodynamic and the structure of the system. The crysta...

F. Vericat L. Blum

1986-01-01

51

Hydrogenated Amorphous Silicon Radiation Detectors: Material Parameters; Radiation Hardness; Charge Collection  

Microsoft Academic Search

Properties of hydrogenated amorphous silicon p -i-n diodes relevant to radiation detection applications were studied. The interest in using this material for radiation detection applications in physics and medicine was motivated by its high radiation hardness and the fact that it can be deposited over large area at relatively low cost. Thick, fully depleted a-Si:H diodes are required for sufficient

Shafi Qureshi

1991-01-01

52

Wheat grain hardness results from highly conserved mutations in the friabilin components puroindoline a and b  

PubMed Central

“Soft” and “hard” are the two main market classes of wheat (Triticum aestivum L.) and are distinguished by expression of the Hardness gene. Friabilin, a marker protein for grain softness (Ha), consists of two proteins, puroindoline a and b (pinA and pinB, respectively). We previously demonstrated that a glycine to serine mutation in pinB is linked inseparably to grain hardness. Here, we report that the pinB serine mutation is present in 9 of 13 additional randomly selected hard wheats and in none of 10 soft wheats. The four exceptional hard wheats not containing the serine mutation in pinB express no pinA, the remaining component of the marker protein friabilin. The absence of pinA protein was linked inseparably to grain hardness among 44 near-isogenic lines created between the soft variety Heron and the hard variety Falcon. Both pinA and pinB apparently are required for the expression of grain softness. The absence of pinA protein and transcript and a glycine-to-serine mutation in pinB are two highly conserved mutations associated with grain hardness, and these friabilin genes are the suggested tightly linked components of the Hardness gene. A previously described grain hardness related gene termed “GSP-1” (grain softness protein) is not controlled by chromosome 5D and is apparently not involved in grain hardness. The association of grain hardness with mutations in both pinA or pinB indicates that these two proteins alone may function together to effect grain softness. Elucidation of the molecular basis for grain hardness opens the way to understanding and eventually manipulating this wheat endosperm property.

Giroux, Michael J.; Morris, Craig F.

1998-01-01

53

A polydisperse hard sphere model for interatomic correlations in multi-component metallic melts  

NASA Astrophysics Data System (ADS)

We propose a polydisperse hard sphere model for numerical calculation of the analytic radial distribution function of multi-component atomic liquids. The vibrational part of atomic thermal motion in liquids is modeled by the effective density profile of polydisperse hard spheres. We applied an orthogonal polynomial technique for the solution of a system of Ornstein-Zernike equations using the hard sphere Percus-Yevick analytic expression for the direct correlation functions. The partial radial distribution functions were calculated for the case of a binary liquid where the size distribution of the components is specified by Schultz distributions.

Yakibchuk, P. M.; Volkov, O. V.; Vakarchuk, S. O.

2009-12-01

54

Slow component suppression and radiation damage in doped BaFâ crystals  

Microsoft Academic Search

The scintillation and radiation damage properties of barium fluoride crystals doped with various rare earths have been studied in an attempt to develop a fast, radiation hard scintillating crystal with a suppressed slow component for use at high counting rates. The light output of doped BaFâ samples was measured with a solar blind (CsTe) photomultiplier tube and compared with a

C. L. Woody; P. W. Levy; J. A. Kierstead

1989-01-01

55

Slow component suppression and radiation damage in doped BaFâ crystals  

Microsoft Academic Search

The scintillation and radiation damage properties of barium fluoride crystals doped with various rare earths have been studied in an attempt to develop a fast, radiation hard scintillating crystal with a suppressed slow component for use at high counting rates. The light output of doped BaFâ samples was measured with a solar blind (CsTe) photomultiplier tube and compared with a

C. L. Woody; P. W. Levy; J. A. Kierstead

1988-01-01

56

Radiation hardness of punch-through and FET biased silicon microstrip detectors  

Microsoft Academic Search

Silicon microstrip detectors can be biased with polysilicon resistors or Field Effect Transistor (FET) biasing structures. Polysilicon resistors are radiation hard, but using the FET biasing principle reduces processing costs and can give better noise performance. A set of microstrip detectors has been manufactured with a standard radiation sensor process in order to assess the radiation hardness of punch-through and

Trond I. Westgaard; Berit S. Avset; Niaz N. Ahmed; Lars Evensen

1996-01-01

57

Strategies for Radiation Hardness Testing of Power Semiconductor Devices  

NASA Technical Reports Server (NTRS)

Plans on the drawing board for future space missions call for much larger power systems than have been flown in the past. These systems would employ much higher voltages and currents to enable more powerful electric propulsion engines and other improvements on what will also be much larger spacecraft. Long term human outposts on the moon and planets would also require high voltage, high current and long life power sources. Only hundreds of watts are produced and controlled on a typical robotic exploration spacecraft today. Megawatt systems are required for tomorrow. Semiconductor devices used to control and convert electrical energy in large space power systems will be exposed to electromagnetic and particle radiation of many types, depending on the trajectory and duration of the mission and on the power source. It is necessary to understand the often very different effects of the radiations on the control and conversion systems. Power semiconductor test strategies that we have developed and employed will be presented, along with selected results. The early results that we have obtained in testing large power semiconductor devices give a good indication of the degradation in electrical performance that can be expected in response to a given dose. We are also able to highlight differences in radiation hardness that may be device or material specific.

Soltis, James V. (Technical Monitor); Patton, Martin O.; Harris, Richard D.; Rohal, Robert G.; Blue, Thomas E.; Kauffman, Andrew C.; Frasca, Albert J.

2005-01-01

58

Investigation of design parameters for radiation hard silicon microstrip detectors  

NASA Astrophysics Data System (ADS)

In the context of the development of radiation hard silicon microstrip detectors for the CMS Tracker, we have investigated the dependence of interstrip and backplane capacitance as well as depletion and breakdown voltage on the design parameters and substrate characteristics of the devices. Measurements have been made for strip pitches between 60 and 240 ?m and various strip implants and metal widths, using multi-geometry devices, fabricated on wafers of either <1 1 1> or <1 0 0> crystal orientation, of resistivities between 1 and 6 k? cm and of thicknesses between 300 and 410 ?m. The effect of irradiation on properties of devices has been studied with 24 GeV/c protons up to a fluence of 4.3×10 14 cm-2.

Braibant, S.; Demaria, N.; Feld, L.; Frey, A.; Fürtjes, A.; Glessing, W.; Hammarström, R.; Honma, A.; Mannelli, M.; Mariotti, C.; Mättig, P.; Migliore, E.; Piperov, S.; Runolfsson, O.; Schmitt, B.; Söldner-Rembold, A.; Surrow, B.

2002-06-01

59

Experimental study of hard photon radiation processes at HERA  

NASA Astrophysics Data System (ADS)

We present an experimental study of the ep? e?+ p and ep? e?+ X processes using data recorded by the H1 detector in 1993 at the electron-proton collider HERA. These processes are employed to measure the luminosity with an accuracy of 4.5 %. A subsample of the ep? e?+ X events in which the hard photon is detected at angles ?{?/'} ? 0.45 mrad with respect to the incident electron direction is used to verify experimentally the size of radiative corrections to the ep? eX inclusive cross section and to investigate the structure of the proton in the Q 2 domain down to 2 GeV2, lower than previously attained at HERA.

Ahmed, T.; Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Baehr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Colombo, M.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dau, W. D.; Daum, K.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; de Roeck, A.; de Wolf, E. A.; di Nezza, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Haynes, W. J.; Heatherington, J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hill, P.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Horisberger, R.; Hudgson, V. L.; Huet, Ph.; Hütte, M.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Köhne, J.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kur?a, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Lanius, P.; Laporte, J.-F.; Lebedev, A.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; List, B.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Mara?ek, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milstead, D.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Ozerov, D.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Peppel, E.; Perez, E.; Phillips, J. P.; Pichler, Ch.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Rick, H.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Rylko, R.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schiek, S.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Schwind, A.; Seehausen, U.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Spiekermann, J.

1995-12-01

60

The role of radiation hard solar cells in minimizing the costs of global satellite communication systems  

NASA Technical Reports Server (NTRS)

An analysis embodied in a PC computer program is presented, which quantitatively demonstrates how the availability of radiation hard solar cells can help minimize the cost of a global satellite communications system. An important distinction between the currently proposed systems, such as Iridium, Odyssey and Ellipsat, is the number of satellites employed and their operating altitudes. Analysis of the major costs associated with implementing these systems shows that operation at orbital altitudes within the earth's radiation belts (10(exp 3) to 10(exp 4)km) can reduce the total cost of a system by several hundred percent, so long as radiation hard components including solar cells can be used. A detailed evaluation of the predicted performance of photovoltaic arrays using several different planar solar cell technologies is given, including commercially available Si and GaAs/Ge, and InP/Si which is currently under development. Several examples of applying the program are given, which show that the end of life (EOL) power density of different technologies can vary by a factor of ten for certain missions. Therefore, although a relatively radiation-soft technology can usually provide the required EOL power by simply increasing the size of the array, the impact upon the total system budget could be unacceptable, due to increased launch and hardware costs. In aggregate, these factors can account for more than a 10% increase in the total system cost. Since the estimated total costs of proposed global-coverage systems range from $1B to $9B, the availability of radiation-hard solar cells could make a decisive difference in the selection of a particular constellation architecture.

Summers, Geoffrey P.; Walters, Robert J.; Messenger, Scott R.; Burke, Edward A.

1996-01-01

61

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry  

PubMed Central

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu2+), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate 137Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu2+, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu2+ dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100–700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0–5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu2+ material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu2+ exhibits strong radiation hardness and lends support for further investigations of this novel material.

Driewer, Joseph P.; Chen, Haijian; Osvet, Andres; Low, Daniel A.; Li, H. Harold

2011-01-01

62

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry  

SciTech Connect

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu{sup 2+}), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate {sup 137}Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu{sup 2+}, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu{sup 2+} dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100-700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0-5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu{sup 2+} material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu{sup 2+} exhibits strong radiation hardness and lends support for further investigations of this novel material.

Driewer, Joseph P.; Chen, Haijian; Osvet, Andres; Low, Daniel A.; Li, H. Harold [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 and Nuclear Science and Engineering Institute, University of Missouri, E4431 Lafferre Hall, Columbia, Missouri 65211 (United States); Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States); Department of Materials Science and Engineering, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, Erlangen 91058 (Germany); Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)

2011-08-15

63

Radiation-hard/high-speed parallel optical links  

NASA Astrophysics Data System (ADS)

We have designed an ASIC for use in a parallel optical engine for a new layer of the ATLAS pixel detector in the initial phase of the LHC luminosity upgrade. The ASIC is a 12-channel Vertical Cavity Surface Emitting Laser (VCSEL) array driver capable of operating up to 5 Gb/s per channel. The ASIC is designed using a 130 nm CMOS process to enhance the radiation-hardness. A scheme for redundancy has also been implemented to allow bypassing of a broken VCSEL. The ASIC also contains a power-on reset circuit that sets the ASIC to a default configuration with no signal steering. In addition, the bias and modulation currents of the individual channels are programmable. We have tested the ASIC and the performance up to 5 Gb/s is satisfactory. Furthermore, we are able to program the bias and modulation currents and to bypass a broken VCSEL channel. We are currently upgrading our design to allow operation at 10 Gb/s per channel yielding an aggregated bandwidth of 120 Gb/s. Preliminary results of the design will be presented.

Gan, K. K.; Buchholz, P.; Kagan, H. P.; Kass, R. D.; Moore, J.; Smith, D. S.; Wiese, A.; Ziolkowski, M.

2013-12-01

64

Fault tolerant, radiation hard, high performance digital signal processor  

NASA Technical Reports Server (NTRS)

An architecture has been developed for a high-performance VLSI digital signal processor that is highly reliable, fault-tolerant, and radiation-hard. The signal processor, part of a spacecraft receiver designed to support uplink radio science experiments at the outer planets, organizes the connections between redundant arithmetic resources, register files, and memory through a shuffle exchange communication network. The configuration of the network and the state of the processor resources are all under microprogram control, which both maps the resources according to algorithmic needs and reconfigures the processing should a failure occur. In addition, the microprogram is reloadable through the uplink to accommodate changes in the science objectives throughout the course of the mission. The processor will be implemented with silicon compiler tools, and its design will be verified through silicon compilation simulation at all levels from the resources to full functionality. By blending reconfiguration with redundancy the processor implementation is fault-tolerant and reliable, and possesses the long expected lifetime needed for a spacecraft mission to the outer planets.

Holmann, Edgar; Linscott, Ivan R.; Maurer, Michael J.; Tyler, G. L.; Libby, Vibeke

1990-01-01

65

Radiation heating in selected NERVA engine components  

NASA Technical Reports Server (NTRS)

The role of heating from nuclear radiation in design of the NERVA engine is treated. Some components are subjected to very high gamma heating rates in excess of 0.5 Btu/cubic inch/sec in steel in the primary nozzle or 0.25 Btu/cubic inch/sec in aluminum in the pressure vessel. These components must be cooled by a fraction of the liquid hydrogen propellant before it is passed through the core, heated, and expanded out the nozzle as a gas. Other components that are subjected to lower heating rates such as the thrust structure and the disk shield are designed so that they would not require liquid hydrogen cooling. Typical gamma and neutron heating rates, resulting temperatures, and their design consequences are discussed. Calculational techniques used in the nuclear and thermal analyses of the NERVA engine are briefly treated.

Courtney, J. C.; Hertelendy, N. A.; Lindsey, B. A.

1972-01-01

66

Hard X-ray/soft gamma -ray observations of the Galactic Background Radiation: unresolved discrete sources ?  

NASA Astrophysics Data System (ADS)

The Galactic background radiation near the Scutum Arm was observed simultaneously with the Rossi X-Ray Timing Explorer (RXTE) and the Oriented Scintillation Spectrometer Experiment (OSSE) in order to constrain the spectral shape and the origin of the emission in the hard X-ray/soft gamma -ray band. The spectrum in the 3 keV to 1 MeV band is well modeled by 4 components: a high energy continuum dominating above 500 keV that can be characterized by a power law of photon index ~ 1.6 below 1 MeV; a positron annihilation line at 511 keV and positronium continuum; a variable hard X-ray/soft gamma -ray component that dominates between 10-400 keV (with a minimum detected flux of ~ 7.7 x 10-7 photons cm{-2 s-1 keV-1 deg-2} at 100 keV averaged over the field of view of OSSE) and is well modeled by an exponentially cut off power law of photon index ~ 0.6 and energy cut off at ~ 41 keV; and finally a Raymond-Smith thermal plasma model of solar abundances and temperature ~ 2.6 keV that dominates below 10 keV. We estimate that at 60 and 100 keV, the contribution of bright discrete sources to the minimum flux detected by OSSE was ~ 49% and ~ 20%, respectively. This implies that the spectrum of the residual, unresolved emission is harder than that measured with the above power law. This emission may be interpreted either as truly diffuse emission with a hard spectrum (such as that from inverse Compton scattering) or the superposition of discrete sources that have very hard spectra.

Valinia, A.; Marshall, F. E.; Kinzer, R. L.

67

Microstructural variations in radiation hard and soft oxides observed through electron spin resonance  

NASA Astrophysics Data System (ADS)

Microstructural variations have been investigated in radiation-hard and -soft oxides, using electron spin resonance. It is observed that the radiation tolerance of hard and soft oxides grown in both steam and dry oxygen is correlated with two 'trivalent silicon' point defects. One trivalent silicon defect, the P(b) center, is responsible for the radiation-induced interface states. The other center, termed E-prime, appears to be the hole trap.

Lenahan, P. M.; Dressendorfer, P. V.

1983-12-01

68

Radiation hard programmable delay line for LHCb calorimeter upgrade  

NASA Astrophysics Data System (ADS)

This paper describes the implementation of a SPI-programmable clock delay chip based on a Delay Locked Loop (DLL) in order to shift the phase of the LHC clock (25 ns) in steps of 1ns, with less than 5 ps jitter and 23 ps of DNL. The delay lines will be integrated into ICECAL, the LHCb calorimeter front-end analog signal processing ASIC in the near future. The stringent noise requirements on the ASIC imply minimizing the noise contribution of digital components. This is accomplished by implementing the DLL in differential mode. To achieve the required radiation tolerance several techniques are applied: double guard rings between PMOS and NMOS transistors as well as glitch suppressors and TMR Registers. This 5.7 mm2 chip has been implemented in CMOS 0.35 ?m technology.

Mauricio, J.; Gascón, D.; Vilasís, X.; Picatoste, E.; Machefert, F.; Lefrancois, J.; Duarte, O.; Beigbeder, C.

2014-01-01

69

DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A  

SciTech Connect

The extended high-energy gamma-ray (>100 MeV) emission which occurs after prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not clearly revealed such a signature, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. By performing time-resolved spectral fits of GRB 130427A, we found strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Compton emission.

Tam, Pak-Hin Thomas [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Tang Qingwen; Liu Ruoyu; Wang Xiangyu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Hou Shujin, E-mail: phtam@phys.nthu.edu.tw, E-mail: xywang@nju.edu.cn [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

2013-07-01

70

The role of radiation hard solar cells in minimizing the costs of global satellite communications systems  

NASA Technical Reports Server (NTRS)

An analysis embodied in a PC computer program is presented which quantitatively demonstrates how the availability of radiation hard solar cells can minimize the cost of a global satellite communication system. The chief distinction between the currently proposed systems, such as Iridium Odyssey and Ellipsat, is the number of satellites employed and their operating altitudes. Analysis of the major costs associated with implementing these systems shows that operation within the earth's radiation belts can reduce the total system cost by as much as a factor of two, so long as radiation hard components including solar cells, can be used. A detailed evaluation of several types of planar solar cells is given, including commercially available Si and GaAs/Ge cells, and InP/Si cells which are under development. The computer program calculates the end of life (EOL) power density of solar arrays taking into account the cell geometry, coverglass thickness, support frame, electrical interconnects, etc. The EOL power density can be determined for any altitude from low earth orbit (LEO) to geosynchronous (GEO) and for equatorial to polar planes of inclination. The mission duration can be varied over the entire range planned for the proposed satellite systems. An algorithm is included in the program for determining the degradation of cell efficiency for different cell technologies due to proton and electron irradiation. The program can be used to determine the optimum configuration for any cell technology for a particular orbit and for a specified mission life. Several examples of applying the program are presented, in which it is shown that the EOL power density of different technologies can vary by an order of magnitude for certain missions. Therefore, although a relatively radiation soft technology can be made to provide the required EOL power by simply increasing the size of the array, the impact on the total system budget could be unacceptable, due to increased launch and hardware costs. In aggregate these factors can account for more than a 10% increase in the total system cost. Since the estimated total costs of proposed global coverage systems range from $1 Billion to $9 Billion, the availability of radiation hard solar cells could make a decisive difference in the selection of a particular constellation architecture.

Summers, Geoffrey P.; Walters, Robert J.; Messenger, Scott R.; Burke, Edward A.

1995-01-01

71

Foreign technology assessment: Environmental evaluation of a radiation-hard oscillator/divider.  

National Technical Information Service (NTIS)

Salford Electrical Instruments, Ltd., and the General Electric Company's Hirst Research Centre, under contract to the United Kingdom's (UK) Ministry of Defence, developed a radiation-hard, leadless chip-carrier-packaged oscillator/divider. Two preproducti...

M. A. Dvorack

1993-01-01

72

Influence of design variables on radiation hardness of silicon MINP solar cells  

NASA Technical Reports Server (NTRS)

Metal-insulator-N/P silicon (MINP) solar cells were fabricated using different substrate resistivity values, different N-layer designs, and different I-layer designs. A shallow junction into an 0.3 ohm-cm substrate gave best efficiency whereas a deeper junction into a 1 to 4 ohm-cm substrate gave improved radiation hardness. I-layer design variation did little to influence radiation hardness.

Anderson, W. A.; Solaun, S.; Rao, B. B.; Banerjee, S.

1985-01-01

73

The diffuse component of the cosmic X-radiation  

NASA Technical Reports Server (NTRS)

The A-2 experiment on HEAO-1 is specifically developed to study the diffuse radiation of the entire X-ray sky over a wide bandwidth, covering both the soft X-ray emission from nearby regions of the galaxy and the isotropic hard X-radiation indicative of remote extragalactic origins. A partial conclusion from the experiment is that a hot thermal plasma, on a scale comparable to that of the universe, may be the principal source of hard X-radiation characteristic of the extragalactic sky. Some key features of this background were defined.

Boldt, E. A.; Garmire, C.

1978-01-01

74

Radiation Effects on Superconducting Fusion Magnet Components  

NASA Astrophysics Data System (ADS)

Nuclear fusion devices based on the magnetic confinement principle heavily rely on the existence and performance of superconducting magnets and have always significantly contributed to advancing superconductor and magnet technology to their limits. In view of the presently ongoing construction of the tokamak device ITER and the stellerator device Wendelstein 7X and their record breaking parameters concerning size, complexity of design, stored energy, amperage, mechanical and magnetic forces, critical current densities and stability requirements, it is deemed timely to review another critical parameter that is practically unique to these devices, namely the radiation response of all magnet components to the lifetime fluence of fast neutrons and gamma rays produced by the fusion reactions of deuterium and tritium. I will review these radiation effects in turn for the currently employed standard "technical" low temperature superconductors NbTi and Nb3Sn, the stabilizing material (Cu) as well as the magnet insulation materials and conclude by discussing the potential of high temperature superconducting materials for future generations of fusion devices, such as DEMO.

Weber, Harald W.

75

Irradiation tests of critical components for remote handling in gamma radiation environment  

NASA Astrophysics Data System (ADS)

Since the fusion power core of a D-T fusion reactor will be highly activated once it starts operation, personnel access will be prohibited so that assembly and maintenance of the components in the reactor core will have to be totally conducted by remote handling technology. Fusion experimental reactors such as ITER require unprecedented remote handling equipments which are tolerable under gamma radiation of more than 10(exp 6) R/h. For this purpose, the Japan Atomic Energy Research Institute (JAERI) has been developing radiation hard components for remote handling purpose and a number of key components have been tested over 10(exp 9) rad at a radiation dose rate of around 10(exp 6) R/h, using Gamma Ray Radiation Test Facility in JAERI-Takasaki Establishment. This report summarizes the irradiation test results and the latest status of AC servo motor, potentiometer, optical elements, lubricant, sensors and cables, which are key elements of the remote handling system.

Obara, Henjiro; Kakudate, Satoshi; Oka, Kiyoshi; Furuya, Kazuyuki; Taguchi, Kou; Tada, Eisuke; Shibanuma, Kiyoshi; Ohkawa, Yoshinao; Morita, Yousuke; Yokoo, Noriko

1994-08-01

76

Application of spallation neutron sources in support of radiation hardness studies  

Microsoft Academic Search

High-power spallation neutron sources offer a unique opportunity to gather critical measurements on the very early transient displacement damage in semiconductors. This paper discusses the important attributes of spallation neutron facilities used for investigating the transient radiation hardness of semiconductors. By comparing the attributes of some different types of radiation facilities currently used for semiconductor damage characterization, a new and

Patrick Griffin; Donald King; Norm Kolb

2006-01-01

77

Effect Of Clock Mode On Radiation Hardness Of An ADC  

NASA Technical Reports Server (NTRS)

Report discusses techniques for testing and evaluating effects of total dosages of ionizing radiation on performances of high-resolution successive-approximation analog-to-digital converters (ADCs), without having to test each individual bit or transition. Reduces cost of testing by reducing tests to few critical parametric measurements, from which one determines approximate radiation failure levels providing good approximations of responses of converters for purpose of total-dose-radiation evaluations.

Lee, Choon I.; Rax, Bernie G.; Johnston, Allan H.

1995-01-01

78

Final report on LDRD project 52722 : radiation hardened optoelectronic components for space-based applications.  

SciTech Connect

This report describes the research accomplishments achieved under the LDRD Project 'Radiation Hardened Optoelectronic Components for Space-Based Applications.' The aim of this LDRD has been to investigate the radiation hardness of vertical-cavity surface-emitting lasers (VCSELs) and photodiodes by looking at both the effects of total dose and of single-event upsets on the electrical and optical characteristics of VCSELs and photodiodes. These investigations were intended to provide guidance for the eventual integration of radiation hardened VCSELs and photodiodes with rad-hard driver and receiver electronics from an external vendor for space applications. During this one-year project, we have fabricated GaAs-based VCSELs and photodiodes, investigated ionization-induced transient effects due to high-energy protons, and measured the degradation of performance from both high-energy protons and neutrons.

Hargett, Terry W. (L& M Technologies, Inc.); Serkland, Darwin Keith; Blansett, Ethan L.; Geib, Kent Martin; Sullivan, Charles Thomas; Hawkins, Samuel D.; Wrobel, Theodore Frank; Keeler, Gordon Arthur; Klem, John Frederick; Medrano, Melissa R.; Peake, Gregory Merwin; Karpen, Gary D.; Montano, Victoria A. (L& M Technologies, Inc.)

2003-12-01

79

Radiation-hardened optoelectronic components - Sources  

Microsoft Academic Search

The most severe radiation effects for LEDs and laser diodes is light output degradation due to permanent, radiation-induced lattice damage; the present discussion notes that this source of degradation can be minimized through the judicious modification of material and device parameters. In the case of LEDs, the light-emitting region should be heavily doped, and the device should be capable of

C. E. Barnes

1986-01-01

80

Radiation damage to accelerator components of SPring8 storage ring  

Microsoft Academic Search

Radiation damage to the accelerator components of the SPring-8 storage ring became serious after about four years of operation. Some rubber hoses were broken, resulting in water leakage, and some of the Synflex tubes, interlock cables, power cable covers, and so forth became damaged. Measurement of the radiation levels using GafChromic film and TLD showed that the maximum integrated radiation

K. Tsumaki; S. Matsui; M. Oishi; Y. Taniuchi

2006-01-01

81

Development of hard materials by radiation curing technology  

NASA Astrophysics Data System (ADS)

For studying nanoglobular modification effects in radiation cured polymeric composites, we prepared polymerization active silico-organic nanoparticles. With their polymerization active ligands, these nanoparticles form crosslinks by modifying the viscoelastic properties in radiation cured polymeric nanocomposites. In this process, there was a polymerization activity imparted to the particle surfaces of nanopowders, thus applying the physico-chemical modification scheme of a heterogeneous copolymerization to novel scratch and abrasion resistant coatings. By varying the nanoparticle-monomer formulation and the curing method, additional property can be achieved. In this works, we also investigated the influence of various factors such as addition of photoinitiators and other additives into the formulations. The coating materials were applied to the substrate by using different type of coaters. These materials were cured by ultraviolet light and electron beam irradiation. Properties of coatings were characterized using Universal scratch tester and Taber abrasion tester.

Salleh, N. G.; Gläsel, H. J.; Mehnert, R.

2002-03-01

82

MNOS/SOS radiation hardness performance and reliability study  

NASA Astrophysics Data System (ADS)

In this investigation the endurance-retention characteristics of fast-write MNOS memory structure, and radiation tolerance of metal-gate dual-dielectric and polysilicon-gate all-oxide devices have been evaluated. Writing and clearing speed have been studied with respect to the NH3:SiH4 ratio (APCVD), and NH3:SiC12H2 ratio (LPCVD). The films deposited with a low NH3:SiC12 ratios could be written and cleared with shorter pulse widths; however, a degradation in retention was observed. An improvement in the endurance retention product of a drain source protected transistor structure has been realized by oxidizing the memory nitride followed by an H2 anneal immediately after deposition. The film was deposited with a LPCVD reactor at 750 deg with a NH3:SiC12H2 ratio of 9:1. Oxidation was performed in steam at 900 C, as was the subsequent H2 anneal. The effect of total dose radiation was found to be more severe for a positive bias. The all oxide polysilicon gate transistor structures were observed to be relatively soft, however results from capacitor structures shows promise in developing a radiation tolerant polysilicon-gate all-oxide gate structure.

Hampton, F. L.; Cricchi, J. R.

1982-05-01

83

The radiation hardness and temperature stability of Planar Light-wave Circuit splitters for the High Luminosity LHC  

NASA Astrophysics Data System (ADS)

High Luminosity LHC (HL-LHC) Inner Tracker designs may include the sharing of Timing, Trigger and Control (TTC) signals between several tracker modules. This is possible because the highest frequency signals are common to all modules. Such designs are an attractive option because they reduce the number of optical links required and hence the cost. These designs will require optical signal splitters that are radiation hard up to high doses and capable of operating in cold temperatures. Optical splitters are available as either fused-fibre splitters or Planar Light-wave Circuit (PLC) splitters. PLC splitters are preferable because they are smaller than fused-fibre splitters. A selection of PLC splitters from different manufacturers and of two different technologies (silica and glass based) have been tested for radiation hardness up to a dose of 500 kGy(Si) and for temperature stability. All the tested splitters displayed small increases in insertion losses ( < 0.1 dB) in reducing the operating temperature from 25°C to -25°C. The silica based splitters from all manufacturers did not exhibit significant radiation induced insertion losses, despite the high dose they were exposed to. The glass based sample, however, had a per channel radiation induced insertion loss of up to 1.16 dB. Whilst the silica based splitters can be considered as qualified for HL-LHC use with regards to radiation hardness, the glass technology would require further testing at a lower, more realistic, dose to also be considered as a potential component for HL-LHC upgrade designs.

Ryder, N. C.; Hamilton, P.; Huffman, B. T.; Teng, P. K.; Weidberg, A. R.; Issever, C.

2011-10-01

84

Hierarchical radioscopy using polychromatic and partially coherent hard synchrotron radiation.  

PubMed

Pushing synchrotron x-ray radiography to increasingly higher image-acquisition rates (currently up to 100,000 fps) while maintaining spatial resolutions in the micrometer range implies drastically reduced fields of view. As a consequence, either imaging a small subregion of the sample with high spatial resolution or only the complete specimen with moderate resolution is applicable. We introduce a concept to overcome this limitation by making use of a semi-transparent x-ray detector positioned close to the investigated sample. The hard x-rays that pass through the sample either create an image on the first detector or keep on propagating until they are captured by a second x-ray detector located further downstream. In this way, a process can be imaged simultaneously in a hierarchical manner within a single exposure and a projection of the complete object with moderate resolution as well as a subregion with high resolution are obtained. As a proof-of-concept experiment, image sequences of an evolving liquid-metal foam are shown, employing frame rates of 1000??images/s (1.2 ?m pixel size) and 15,000??images/s (18.1 ?m pixel size) for the first and second detector, respectively. PMID:24513767

Rack, Alexander; García-Moreno, Francisco; Helfen, Lukas; Mukherjee, Manas; Jiménez, Catalina; Rack, Tatjana; Cloetens, Peter; Banhart, John

2013-11-20

85

Radiation induced modification in nanoscale hardness of ZnO cone structures  

SciTech Connect

In this paper, the effect of ion irradiation on nanoscale hardness of ZnO microcones is reported. The hardness of ZnO cones determined by nanoindentation using atomic force microscope initially increases from 4.7{+-}1.4 to 9.5{+-}1.6 GPa after irradiation with 1.2 MeV Ar{sup +8} ions at an ion fluence of 10{sup 15} ions cm{sup -2} and then decreases with increasing ion fluence. This change in mechanical hardness has been correlated with the residual stress of the sample revealed by Raman peak shift in the E{sub 2}(H) mode. These results show that the generally reported radiation-hard nature of ZnO depends critically on irradiation conditions, especially the irradiation temperature.

Nagar, Rupali; Mehta, B. R.; Singh, J. P. [Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Teki, R. [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Koratkar, N. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Sathe, V. G. [UGC-DAE, Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, Post Box 10502, New Delhi 110067 (India)

2010-09-15

86

Hard tooth tissue acoustic response under contact of YAG:Er laser radiation processing  

NASA Astrophysics Data System (ADS)

The present paper is the first to results an investigation of parameters of acoustic wave accompanying human tooth enamel and dentine treatment provided with contact YAG:Er submillisecond pulse radiation. It is to define experimentally a dependence of laser-induced acoustic wave integral energy on radiation energy density. And at least, it is to identify Fourier deformations of laser-induced acoustic wave spectrum under contact and non-contact processing of human hard tooth tissue.

Altshuler, Gregory B.; Belikov, Andrey V.; Erofeev, Andrew V.; Scrypnik, Alexei V.

1996-12-01

87

Improvement of optical properties and radiation hardness of NaBi(WO 4) 2 Cherenkov crystals  

NASA Astrophysics Data System (ADS)

On the basis of the data on melt evaporation while growing NaBi(WO 4) 2 Cherenkov crystals, the formation of nonstoichiometry and most probable types of dot defects of the crystals have been considered. The influence of melt nonstoichiometry and doping with Sc on optical transmission and radiation hardness of the crystals has been experimentally investigated. The surplus of WO 3 has been established to increase optical transmission and radiation hardness and lack of Bi 2O 3 in the melt to reduce radiation hardness. Sc doping is shifting the absorption edge to UV region by 30-35 nm and is increasing radiation hardness of the crystals about three-fold. Analytical estimations give the increase of the number of Cherenkov photons by a factor of 1.3, which leads to an improvement of the energy resolution of a calorimeter based on NaBi(WO 4) 2:Sc crystals compared with undoped NaBi(WO 4) 2 of approximately 15%.

Zadneprovski, B. I.; Nefedov, V. A.; Polyansky, E. V.; Devitsin, E. G.; Kozlov, V. A.; Potashov, S. Y.; Terkulov, A. R.

2002-06-01

88

Radiation Hardness and Charge Collection Efficiency of Lithium Irradiated Thin Silicon Diodes  

Microsoft Academic Search

Due to their low depletion voltage, even after high particle fluences, improved tracking precision and momentum resolution, and reduced material budget, thin substrates are one of the possible choices to provide radiation hard detectors for future high energy physics experiments. In the framework of the CERN RD50 Collaboration, we have developed PIN diode detectors on membranes obtained by locally thinning

Maurizio Boscardin; Mara Bruzzi; Andrea Candelori; G.-F. DallaBetta; Ettore Focardi; Volodymyr Khomenkov; Claudio Piemonte; Sabina Ronchin; Carlo Tosi; Nicola Zorzi

2005-01-01

89

Slope effects on shortwave radiation components and net radiation  

NASA Technical Reports Server (NTRS)

The main objective of the International Satellite Land Surface Climatology Project (ISLSCP) has been stated as 'the development of techniques that may be applied to satellite observations of the radiation reflected and emitted from the Earth to yield quantitative information concerning land surface climatological conditions.' The major field study, FIFE (the First ISLSCP Field Experiment), was conducted in 1978-89 to accomplish this objective. Four intensive field campaigns (IFC's) were carried out in 1987 and one in 1989. Factors contributing to observed reflected radiation from the FIFE site must be understood before the radiation observed by satellites can be used to quantify surface processes. Analysis since our last report has focused on slope effects on incoming and outgoing shortwave radiation and net radiation from data collected in 1989.

Walter-Shea, Elizabeth A.; Blad, Blaine L.; Hays, Cynthia J.; Mesarch, Mark A.

1992-01-01

90

Effects of plasma-deposited silicon nitride passivation on the radiation hardness of CMOS integrated circuits  

SciTech Connect

The use of plasma-deposited silicon nitride as a final passivation over metal-gate CMOS integrated circuits degrades the radiation hardness of these devices. The hardness degradation is manifested by increased radiation-induced threshold voltage shifts caused principally by the charging of new interface states and, to a lesser extent, by the trapping of holes created upon exposure to ionizing radiation. The threshold voltage shifts are a strong function of the deposition temperature, and show very little dependence on thickness for films deposited at 300/sup 0/C. There is some correlation between the threshold voltage shifts and the hydrogen content of the PECVD silicon nitride films used as the final passivation layer as a function of deposition temperature. The mechanism by which the hydrogen contained in these films may react with the Si/SiO/sub 2/ interface is not clear at this point.

Clement, J. J.

1980-01-01

91

Radiation size and divergence at the hard x-ray beamline in the PAL-XFEL  

NASA Astrophysics Data System (ADS)

In the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL), recently, the minimum gap of the hard X-ray undulator were changed from 7.2 (undulator period: 24.4 mm) to 8.3 mm (undulator period: 26 mm). To review the physical issues related to the gap change, including the radiation size and divergence, in the PAL-XFEL, we did a simulation study with GENESIS 1.3. The saturation length in the 8.3-mm case will be increased by 10% with respect to the 7.2-mm case. The study also revealed that the divergence of the radiation in 8.3-mm case would be decreased by 4% compared with that in the 7.2-mm case. In this paper, we will present the detailed simulation results to estimate the divergence of radiation at the hard X-ray beamline in the PAL-XFEL.

Parc, Yong Woon; Han, Jang-Hui; Kang, Heung Sik; Kim, Ilyou; Yang, Haeryong; Hwang, Ilmoon; Shim, Chi Hyun; Ko, In Soo

2014-04-01

92

Biochemical Changes in Blood Components after Lethal Doses of Radiation.  

National Technical Information Service (NTIS)

Nonpeptide, peptide, and protein blood components were measured postirradiation in Wistar rats to investigate biochemical changes that might be related to or form the basis of radiation-induced emesis. The rats were irradiated with lethal doses of radiati...

A. M. Magro

1982-01-01

93

Metamaterial-based optical components for THz radiation  

Microsoft Academic Search

We present different metamaterial-based optical components that open exciting new ways to deliberately manipulate the spatial or spectral properties of terahertz (THz) radiation. The central scope of the paper is the design, fabrication and optical characterization of a 3-layer gradient index (GRIN) lens that allows one to strongly focus THz radiation to a spot diameter in the order of one

J. Neu; B. Krolla; O. Paul; B. Reinhard; P. Weis; V. Wollrab; J.-L. Garcia Pomar; R. Beigang; M. Rahm

2011-01-01

94

Radiation hardness of silicon detectors based on pre-irradiated silicon  

NASA Astrophysics Data System (ADS)

Radiation hardness of planar detectors processed from pre-irradiated and thermo-annealed n-type FZ silicon substrates, and standard FZ as a reference, was studied. The high purity n-Si wafers with carrier concentration 4.8×10 11 cm -3 were pre-irradiated in Kiev's nuclear research reactor by fast neutrons to fluence of about 10 16 neutrons/cm 2 and thermo-annealed at a temperature of about 850 °C. Silicon diodes were fabricated from standard and pre-irradiated silicon substrates by IRST (Italy). All diodes were subsequently irradiated by fast neutrons at Kiev and Ljubljana nuclear reactors. The dependence of the effective doping concentration as a function of fluence ( Neff=f( ?)) was measured for reference and pre-irradiated diodes. Pre-irradiation of silicon improves the radiation hardness by decreasing the acceptor introduction rate ( ?), thus mitigating the depletion voltage ( Vdep) increase. In particular, ? in reference samples is about 0.017 cm -1, and for pre-irradiated samples is about 0.008 cm -1. Therefore, the method of preliminary irradiation can be useful to increase the radiation hardness of silicon devices to be used as sensors or detectors in harsh radiation environments.

Litovchenko, P. G.; Groza, A. A.; Lastovetsky, V. F.; Barabash, L. I.; Starchik, M. I.; Dubovoy, V. K.; Bisello, D.; Giubilato, P.; Candelori, A.; Rando, R.; Litovchenko, A. P.; Khomenkov, V.; Wahl, W.; Boscardin, M.; Zorzi, N.; Dalla Betta, G.-F.; Cindro, V.; Mikelsen, M.; Monakhov, E. V.; Svensson, B. G.

2006-11-01

95

Effects of lipophilic components on the compatibility of lipid-based formulations with hard gelatin capsules.  

PubMed

The present study investigated the effect of lipophilic components on the compatibility of propylene glycol (PG)-containing lipid-based drug delivery system (LBDDS) formulations with hard gelatin capsules. The presence of a lipophilic active pharmaceutical ingredient (API) (log P approximately 6.1) and an additional lipophilic excipient (Capmul MCM) significantly affected the activity of PG in the fills and the equilibrium of PG between capsule shells and fills. These changes in activity and equilibrium of PG were furthermore correlated to the mechanical and thermal properties of the liquid-filled capsules and subsequently linked to the shelf-life of the capsules on stability with respect to capsule deformation. The present study also investigated the mechanism by which lipophilic component(s) might affect the activity of PG in the fill formulations and the equilibrium of PG between capsule shells and fills. The activities of PG in two series of "binary" mixtures with Capmul MCM and with Cremophor EL were measured, respectively. The mixtures of PG containing Capmul MCM were found to be more nearly ideal than those containing Cremophor EL. The observed negative deviation from Rauolt's law indicates that the excess free energies of mixing are less then zero indicating favorable interaction between PG and the other component. It is speculated that enhanced hydrogen bonding opportunities with Cremophor EL are responsible for the decreased excess free energy of mixing. Replacement of Cremophor EL with lipophilic API also reduces the hydrogen bonding opportunities for PG in the mixtures. This hypothesis may further explain the increased activity of PG in the fills and the shifted equilibrium of PG toward the capsule shells. Activity determination utilizing headspace gas chromatography (GC) using short 30 min incubation time seems to be a time-efficient approach for assessing capsule-fill compatibility. Direct measurements of PG migration and other physical properties of the capsules took much longer time (7 weeks) for ranking the predicted capsule deformation at 40 degrees C. Asides from the time savings, activity determination can be considered to be material sparing by offering capsule-fill compatibility assessment even without the need for preparing liquid-filled capsules once appropriate positive and negative references are established. With further optimization, this approach should enable high throughput screening of LBDDS for capsule-fill compatibility in liquid-filled capsule development. PMID:19455627

Chen, Feng-Jing; Etzler, Frank M; Ubben, Johanna; Birch, Amy; Zhong, Li; Schwabe, Robert; Dudhedia, Mayur S

2010-01-01

96

Slope effects on shortwave radiation components and net radiation  

Microsoft Academic Search

The main objective of the International Satellite Land Surface Climatology Project (ISLSCP) has been stated as 'the development of techniques that may be applied to satellite observations of the radiation reflected and emitted from the Earth to yield quantitative information concerning land surface climatological conditions.' The major field study, FIFE (the First ISLSCP Field Experiment), was conducted in 1978-89 to

Elizabeth A. Walter-Shea; Blaine L. Blad; Cynthia J. Hays; Mark A. Mesarch

1992-01-01

97

Performance characterization of hard x-ray imaging instruments at synchrotron radiation facility SPring-8  

NASA Astrophysics Data System (ADS)

The relevance of pre-flight calibration of space-born instruments is widely recognized. As an energy region of interest shifts to hard X-rays in these years, measurement setup becomes difficult to be afforded or maintained by a laboratory- or small-collaboration-based resources. In 10 to 100 KeV region X-ray source that is bright and monochromatic enough to calibrate optics in detail is no longer available other than at synchrotron facilities. Focal length becomes longer and this is another aspect that is beyond capabilities of soft-X-ray-oriented facilities. The hard X-ray instruments for balloon program have been characterized at synchrotron facility SPring-8/BL20B2 in Japan. SPring-8 is one of the world's brightest third generation synchrotron radiation facilities. BL20B2 is specialized for medical and imaging experiment, and has 200m-long transport tube. Measurement at BL20B2 has great advantages such as extremely high flux, large sized and less divergent beam, and monochromatic beam covering entire hard X-ray region from 8 to 12keV. 16m-long experiment hutch is capable of long focal length of hard-X-ray telescope. Pt/C multilayer-supermirror hard X-ray telescopes, position-sensitive scintillation counter and scintillator-deposited CCD, have been characterized at the facility. Insttrumentation of the facility and some of measurement results are presented.

Ogasaka, Yasushi; Tamura, Keisuke; Shibata, Ryo; Furuzawa, Akihiro; Nakamura, Tomokazu; Naitou, Masataka; Miyazawa, Takuya; Shimoda, Kenta; Onishi, Katsuhiko; Fukaya, Yoshihiro; Iwahara, Tomonaga; Kanou, Yasushi; Kunieda, Hideyo; Yamashita, Koujun; Miyata, Emi; Mukai, Kenji; Ikegami, Kazuhiro; Aono, Michihiko; Tsunemi, Hiroshi; Uesugi, Kentaro; Suzuki, Yoshio

2006-07-01

98

Improvement of radiation hardness of the sampling calorimeters based on plastic scintillators  

NASA Astrophysics Data System (ADS)

Plastic scintillators are very often used as detecting media in sampling calorimeters of High Energy Physics (HEP). Many modern HEP experimental installations are already operating or proposed to work at high luminosity. Plastic scintillators are the most sensitive part of such setups in terms of their radiation hardness. Improving the light collection from the most irradiated scintillators will ensure their long-term use at high luminosity. The experimental results of the measurements for different assemblies (scintillator SCSN-81 and the WLS fiber Y-11 electron-irradiated (E?4 MeV) were obtained. Calculations of the light yields for different samples based on our experimental results show the possibility of increasing the radiation hardness of plastic scintillators inside the sampling calorimeter up to 20 Mrad.

Afanasiev, S. V.; de Barbaro, P.; Golutvin, I. A.; Emeliantchik, I. F.; Malakhov, A. I.; Moisenz, P. V.; Smirnov, V. A.; Shumeiko, N. M.

2013-07-01

99

The geometrical dependence of radiation hardness in planar and 3D silicon detectors  

Microsoft Academic Search

The radiation hardness of planar and 3D silicon detectors fabricated on Float-Zone and epitaxial silicon substrates is compared after exposure to neutron equivalent fluences greater than 1015cm?2. Following irradiation, the Signal Efficiency (SE), expressed as the ratio of the maximum signal after irradiation divided to the maximum signal before irradiation, is shown to depend only on the geometrical distance, L,

C. Davia; S. J. Watts

2009-01-01

100

Extreme Radiation Hardness and Space Qualification of AlGaN Optoelectronic Devices  

Microsoft Academic Search

Unprecedented radiation hardness and environment robustness are required in the new generation of high energy density physics (HEDP) experiments and deep space exploration. National Ignition Facility (NIF) break-even shots will have a neutron yield of 1015 or higher. The Europa Jupiter System Mission (EJSM) mission instruments will be irradiated with a total fluence of 1012 protons\\/cm2 during the space journey.

Ke-Xun Sun; Lawrence MacNeil; Kathik Balakrishnan; Eric Hultgren; John Goebel; Yuri Bilenko; Jinwei Yang; Wenhong Sun; Max Shatalov; Xuhong Hu; Remis Gaska

2010-01-01

101

Effects of components in seawater on the digging behavior of the hard clam ( Meretrix lusoria)  

Microsoft Academic Search

The clam industry is very important for fishermen in the southwestern part of Taiwan. However, massive die-offs of hard clams unexpectedly and frequently occur during the hot season. This greatly impacts the economic status of these fishermen. Hard clams are benthic organisms, but they usually emerge from the bottom mud after becoming stressed and before dying. Therefore, the digging behavior

An-Chin Lee; Yu-Hsuan Lin; Chwen-Ru Lin; Ming-Cheng Lee; Yu-Ping Chen

2007-01-01

102

HTLT oxygenated silicon detectors: radiation hardness and long-term stability  

NASA Astrophysics Data System (ADS)

Silicon detectors fabricated by BNLs high-temperature, long time (HTLT) oxidation technology have been characterized using various techniques for material/detector properties and radiation hardness with respect to gamma, proton and neutron irradiation. It has been found that a uniform oxygen distribution with a concentration of 4×10 17/cm 3 has been achieved in high-resistivity FZ silicon with our HTLT technology. With the standard HTLT technology, the original high resistivity of FZ silicon will be retained. However, the controlled introduction of thermal donors (TD) with a concentration higher than the original shallow doping impurity can be achieved with a process slightly altered from the standard HTLT technology (HTLT-TD). Detectors made by both technologies (HTLT and HTLT-TD) have been found to be advantageous in radiation hardness to gamma and proton irradiation, in terms of detector full depletion voltage degradation, as compared to the control samples. In fact, these detectors are insensitive to gamma irradiation up to 600 Mrad and more tolerant by at least a factor of two to proton irradiation and the following reverse annealing. However, there is little improvement in radiation hardness to neutron irradiation, which has been attributed to the nature of neutron-induced damage that is dominated by extended defects or defect clusters. Microscopic measurements (I-DLTS) have also been made on control and HTLT samples and will be compared and presented.

Li, Z.; Dezillie, B.; Bruzzi, M.; Chen, W.; Eremin, V.; Verbitskaya, E.; Weilhammer, P.

2001-04-01

103

The impact of morphology upon the radiation hardness of ZnO layers.  

PubMed

It is shown that ZnO nanorods and nanodots grown by MOCVD exhibit enhanced radiation hardness against high energy heavy ion irradiation as compared to bulk layers. The decrease of the luminescence intensity induced by 130 MeV Xe(23+) irradiation at a dose of 1.5 × 10(14) cm(-2) in ZnO nanorods is nearly identical to that induced by a dose of 6 × 10(12) cm(-2) in bulk layers. The damage introduced by irradiation is shown to change the nature of electronic transitions responsible for luminescence. The change of excitonic luminescence to the luminescence related to the tailing of the density of states caused by potential fluctuations occurs at an irradiation dose around 1 × 10(14) cm(-2) and 5 × 10(12) cm(-2) in nanorods and bulk layers, respectively. More than one order of magnitude enhancement of radiation hardness of ZnO nanorods grown by MOCVD as compared to bulk layers is also confirmed by the analysis of the near-bandgap photoluminescence band broadening and the behavior of resonant Raman scattering lines. The resonant Raman scattering analysis demonstrates that ZnO nanostructures are more radiation-hard as compared to nanostructured GaN layers. High energy heavy ion irradiation followed by thermal annealing is shown to be a way for the improvement of the quality of ZnO nanorods grown by electrodeposition and chemical bath deposition. PMID:21730593

Burlacu, A; Ursaki, V V; Skuratov, V A; Lincot, D; Pauporte, T; Elbelghiti, H; Rusu, E V; Tiginyanu, I M

2008-05-28

104

Comparison of proton microbeam and gamma irradiation for the radiation hardness testing of silicon PIN diodes  

NASA Astrophysics Data System (ADS)

Simple and cost-effective solutions using Si PIN diodes as detectors are presently utilized in various radiation-related applications in which excessive exposure to radiation degrades their charge transport properties. One of the conventional methods for the radiation hardness testing of such devices is time-consuming irradiation with electron beam or gamma-ray irradiation facilities, high-energy proton accelerators, or with neutrons from research reactors. Recently, for the purpose of radiation hardness testing, a much faster nuclear microprobe based approach utilizing proton irradiation has been developed. To compare the two different irradiation techniques, silicon PIN diodes have been irradiated with a Co-60 gamma radiation source and with a 6 MeV proton microbeam. The signal degradation in the silicon PIN diodes for both irradiation conditions has been probed by the IBIC (ion beam induced charge) technique, which can precisely monitor changes in charge collection efficiency. The results presented are reviewed on the basis of displacement damage calculations and NIEL (non-ionizing energy loss) concept.

Jakši?, M.; Grilj, V.; Skukan, N.; Majer, M.; Jung, H. K.; Kim, J. Y.; Lee, N. H.

2013-09-01

105

Comparison of hard X-ray spectra obtained by spectrometers on Hinotori and SMM and detection of 'superhot' component  

NASA Technical Reports Server (NTRS)

Hard X-ray spectra in solar flares obtained by the broadband spectrometers aboard Hinotori and SMM are compared. Within the uncertainty brought about by assuming the typical energy of the background X-rays, spectra by the Hinotori spectrometer are usually consistent with those by the SMM spectrometer for flares in 1981. On the contrary, flares in 1982 persistently show 20-50-percent higher flux by Hinotori than by SMM. If this discrepancy is entirely attributable to errors in the calibration of energy ranges, the errors would be about 10 percent. Despite such a discrepancy in absolute flux, in the the decay phase of one flare, spectra revealed a hard X-ray component (probably a 'superhot' component) that could be explained neither by emission from a plasma at about 2 x 10 to the 7th K nor by a nonthermal power-law component. Imaging observations during this period show hard X-ray emission nearly cospatial with soft X-ray emission, in contrast with earlier times at which hard and soft X-rays come from different places.

Nitta, Nariaki

1988-01-01

106

Detection and Evaluation of Surface Decarburization of Steel Components by Means of Rockwell Hardness Test Procedures.  

National Technical Information Service (NTIS)

A test procedure is outlined which permits detection and evaluation of surface decarburization on steel. The procedure consists of making a series of Rockwell hardness tests on the specimen surfaces using several Rockwell test scales. Evaluation of the su...

B. J. Rogus

1965-01-01

107

Investigations on radiation hardness of DEPFET sensors for the Belle II detector  

NASA Astrophysics Data System (ADS)

In the upgrade of the Belle detector at KEK (Tsukuba, Japan) the two innermost layers of the vertex detector will be realized by a pixel detector (PXD) consisting of DEPFET (DEpleted P-channel Field Effect Transistor) matrices. As the position of the detector will be very close to the beam pipe, it will suffer from intense radiation levels. The main radiation background is the luminosity related 4-fermion final state radiation, which damages the silicon bulk material and the silicon dioxide from the gate contacts. With the dose expected at Belle II, the DEPFET suffers mainly from additional leakage current and increase in noise. In addition, defects in the silicon dioxide change transistor parameters, e.g. the threshold voltage. We will show results on the hardness factor of electrons after a 10 MeV electron irradiation which was performed in the dose and energy range relevant for the PXD. In addition, we present X-ray irradiations of DEPFET equivalent test structures and compare radiation hardness for different oxide parameters in the prototype production.

Ritter, Andreas; Andricek, Ladislav; Kleinohl, Tobias; Koffmane, Christian; Lütticke, Florian; Marinas, Carlos; Moser, Hans-Günther; Ninkovic, Jelena; Richter, Rainer; Schaller, Gerhard; Schnecke, Martina; Schopper, Florian

2013-12-01

108

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Low-threshold generation of harmonics and hard x radiation in a laser plasma. 2. Multipeak generation  

NASA Astrophysics Data System (ADS)

The conditions for the generation of hard x radiation with a multipeak structure in a plasma pumped by a long pulse from a free-running CO2 laser at a low intensity (q?10 GW/cm2) have been studied. This x-ray generation had been observed in a previous study by the present authors. It is shown that this generation of hard x radiation with a multipeak structure leads to a more than tenfold increase in the yield of hard x radiation per laser pulse, under optimum conditions. This increase results from the additional peaks in the x-ray signal. An explanation of this effect is proposed.

Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

1993-02-01

109

On the nature of the sources of hard pulse X-ray radiation  

NASA Technical Reports Server (NTRS)

Besides the identified sources of cosmic pulse X-ray radiation with globular clusters NGC 6624, NGC 1851 and MXB 1730-335 several new identifications were made. The source in Norma was probably identified with globular cluster NGC 5927, the source in Aquila with globular cluster NGC 6838 (M71), and the source in Puppis with globular cluster NGC 2298. Gamma pulses discovered by the Vela satellites and X-ray pulses thoroughly measured by the SAS-3, Ariel-5, and ANS satellites are thought to be the same phenomenon. The sources of such a radiation must be some kind of peculiarity at the central part of globular clusters; it is most probably a massive black hole. The sources of hard pulse radiation which cannot be identified with globular clusters are considered to be a new kind of galactic object, invisible globular clusters, which are naked nuclei of globular clusters.

Shklovskiy, I. S.

1978-01-01

110

Exploring the wavefront of hard X-ray free-electron laser radiation.  

PubMed

The high photon flux and femtosecond pulse duration of hard X-ray free-electron lasers have spurred a large variety of novel and fascinating experiments in physical, chemical and biological sciences. Many of these experiments depend fundamentally on a clean, well-defined wavefront. Here we explore the wavefront properties of hard X-ray free-electron laser radiation by means of a grating interferometer, from which we obtain shot-to-shot wavefront information with an excellent angular sensitivity on the order of ten nanoradian. The wavefront distortions introduced by optical elements are observed in-situ and under operational conditions. The source-point position and fluctuations are measured with unprecedented accuracy in longitudinal and lateral direction, both during nominal operation and as the X-ray free-electron laser is driven into saturation. PMID:22781760

Rutishauser, Simon; Samoylova, Liubov; Krzywinski, Jacek; Bunk, Oliver; Grünert, Jan; Sinn, Harald; Cammarata, Marco; Fritz, David M; David, Christian

2012-01-01

111

Development of radiation-hard optical links for the CMS tracker at CERN  

SciTech Connect

A radiation-hard optical link is under development for readout and control of the tracking detector in the future CMS experiment at the CERN Large Hadron Collider. The authors present the optical system architecture based on edge-emitting InGaAsP laser-diode transmitters operating at a wavelength of 1.3 {micro}m, single mode fiber ribbons, multi-way connectors and InGaAsP in photodiode receivers. They report on radiation hardness tests of lasers, photodiodes, fibers and connectors. Increases of laser threshold and pin leakage currents with hadron fluence have been observed together with decreases in laser slope-efficiency and photodiode responsivity. Short lengths of single-mode optical fiber and multi-way connectors have been found to be little affected by radiation damage. They analyze the analog and digital performance of prototype optical links transmitting data generated at a 40 MSample/s rate. Distortion, settling time, bandwidth, noise, dynamic range and bit-error-rate results are discussed.

Vasey, F.; Arbet-Engels, V.; Cervelli, G.; Gill, K.; Grabit, R.; Mommaert, C.; Stefanini, G. [CERN, Geneva (Switzerland). ECP Div.] [CERN, Geneva (Switzerland). ECP Div.; Batten, J.; Troska, J. [Imperial Coll., London (United Kingdom)] [Imperial Coll., London (United Kingdom)

1998-06-01

112

Design of radiation hard CMOS APS image sensors in a 0.35-?m standard process  

NASA Astrophysics Data System (ADS)

A CMOS APS Image sensor test chip was designed employing the physical design techniques of enclosed geometry and guard ring, and according to the design rules of a 0.35-micrometers CMOS standard process that has a gate oxide thickness of approximately 7.0 nm. Three sets of radiation tolerant photodiode active pixels were developed employing these design techniques. They are N-type, and H-type pixels. Each of the pixels is a square pixel with a 16.2 micrometers pitch. The yielded fill-factor is approximately 50 percent. Depending on the pixel-type and the layout, the simulated output voltage swing ranges from 300 mV to 1.1 V. The peripheral circuits, which include decoders, row/column drivers, and I/O pads, were also developed. All NMOS transistors in the peripheral circuits were laid out employing the physical design techniques of enclosed geometry and P-type guard ring. Integrating the pixels and the peripheral circuits into the design of radiation hard CMOS APS image sensor has bene completed. The size of the pixel array is 256 by 256, constituting an imaging area of approximately 4.1 mm X 4.1 mm. The total size of the die is approximately 5.2 mm X 5.0 mm. The total number of the I/O pads is 42. Plans to irradiate these image sensor using Cobalt-60 to determine the level of their radiation hardness are currently being devised.

Eid, Sayed I.; Chan, Tony Y.; Fossum, Eric R.; Tsai, Richard H.; Spagnuolo, Robert; Deily, John J.

2001-05-01

113

Radiation hardness tests of GaAs amplifiers operated in liquid argon in the ATLAS calorimeter  

NASA Astrophysics Data System (ADS)

Highly integrated Gallium Arsenide (GaAs) chips of preamplifiers and summing amplifiers have been exposed to high fluence of fast neutrons and ?-dose at the IBR-2 reactor in Dubna. A stable performance of the electronics has been demonstrated up to a fluence of 5×1014 n cm-2 and a ?-dose of 55 kGy. The radiation hardness tests confirm the applicability of the preamplifiers for more than 10 years operation in the ATLAS hadronic end-cap calorimeter at LHC.

Ban, J.; Brettel, H.; Cheplakov, A.; Cwienk, W.; Fent, J.; Golikov, V.; Golubyh, S.; Jakobs, K.; Kukhtin, V.; Kulagin, E.; Kurchaninov, L.; Ladygin, E.; Luschikov, V.; Oberlack, H.; Obudovsky, V.; Schacht, P.; Shalyugin, A.; Stiegler, U.; Zweimüller, T.

2008-09-01

114

Study of Hard Materials for Coating PWR (Pressurized Water Reactor) Components.  

National Technical Information Service (NTIS)

Cobalt free alloys colmonoys, ceniums, nitronics and alloy Ni50Mo35Cr13 are compared to stellite 6 for vane parts in nuclear power plants. No material is as good as stellite, nitronic 60 is fairly good but hardness should be increased possibly by carbide ...

M. Aubert A. Bougault D. Brenet M. Guttmann C. Benhamou

1988-01-01

115

Radiation hardness of plastic scintillating fiber against fast neutron and [gamma]-ray irradiation  

SciTech Connect

In future collider experiments, where a background radiation level is estimated to be very high, e.g. around 10[sup 2] [approximately] 10[sup 5] Gy/yr and 10[sup 11] [approximately] 10[sup 14] n/cm[sup 2]/yr at SSC, the detectors operating around the collision point in the experiments will encounter a considerable amount of radiation. Therefore, the detectors, especially the calorimeter, are required to be resistive against high radiation levels. From this point of view, it is of great importance to study the effects of radiation damage on the performance of the detectors. The authors report preliminary results of measurements of radiation hardness of the plastic scintillating fiber Kuraray SCSF-81 against irradiation with fast neutrons and [sup 60]Co [gamma]-rays in the region of the neutron fluence from 1 [times] 10[sup 11] to 5 [times] 10[sup 13] n/cm[sup 2] and the integrated [gamma]-ray dose from 890 to 10[sup 5] Gy, respectively. Deterioration of both intrinsic light yield and light transmittance of the SCSF-81 has been studied.

Murakami, Akira; Yoshinaka, Hideki; Goto, Minehiko (Saga Univ. (Japan). Dept. of Physics)

1993-08-01

116

Radiation mitigating properties of the lignan component in flaxseed  

PubMed Central

Background Wholegrain flaxseed (FS), and its lignan component (FLC) consisting mainly of secoisolariciresinol diglucoside (SDG), have potent lung radioprotective properties while not abrogating the efficacy of radiotherapy. However, while the whole grain was recently shown to also have potent mitigating properties in a thoracic radiation pneumonopathy model, the bioactive component in the grain responsible for the mitigation of lung damage was never identified. Lungs may be exposed to radiation therapeutically for thoracic malignancies or incidentally following detonation of a radiological dispersion device. This could potentially lead to pulmonary inflammation, oxidative tissue injury, and fibrosis. This study aimed to evaluate the radiation mitigating effects of FLC in a mouse model of radiation pneumonopathy. Methods We evaluated FLC-supplemented diets containing SDG lignan levels comparable to those in 10% and 20% whole grain diets. 10% or 20% FLC diets as compared to an isocaloric control diet (0% FLC) were given to mice (C57/BL6) (n=15-30 mice/group) at 24, 48, or 72-hours after single-dose (13.5 Gy) thoracic x-ray treatment (XRT). Mice were evaluated 4 months post-XRT for blood oxygenation, lung inflammation, fibrosis, cytokine and oxidative damage levels, and survival. Results FLC significantly mitigated radiation-related animal death. Specifically, mice fed 0% FLC demonstrated 36.7% survival 4 months post-XRT compared to 60–73.3% survival in mice fed 10%-20% FLC initiated 24–72 hours post-XRT. FLC also mitigated radiation-induced lung fibrosis whereby 10% FLC initiated 24-hours post-XRT significantly decreased fibrosis as compared to mice fed control diet while the corresponding TGF-beta1 levels detected immunohistochemically were also decreased. Additionally, 10-20% FLC initiated at any time point post radiation exposure, mitigated radiation-induced lung injury evidenced by decreased bronchoalveolar lavage (BAL) protein and inflammatory cytokine/chemokine release at 16 weeks post-XRT. Importantly, neutrophilic and overall inflammatory cell infiltrate in airways and levels of nitrotyrosine and malondialdehyde (protein and lipid oxidation, respectively) were also mitigated by the lignan diet. Conclusions Dietary FLC given early post-XRT mitigated radiation effects by decreasing inflammation, lung injury and eventual fibrosis while improving survival. FLC may be a useful agent, mitigating adverse effects of radiation in individuals exposed to incidental radiation, inhaled radioisotopes or even after the initiation of radiation therapy to treat malignancy.

2013-01-01

117

The radiation hardness of silica optical fiber used in the LED-fiber monitor of BLM and BESIII EMC  

NASA Astrophysics Data System (ADS)

LED-fiber system has been used to monitor BLM and BESIII EMC. A radiation hard silica optical fiber is essential for its stability and reliability. Three types of silica optical fibers, silicone-clad silica optical fiber with high OH - content (SeCS), silica-clad silica optical fiber with low OH - content (SCSL) and silica-clad silica opical fiber with high OH - content (SCSH) were studied. In the experiment, 12 groups of fiber samples were irradiated by 60Co and 3 groups of fiber samples were irradiated by BEPCII background radiation. Radiation hardness: the radiation hardness of SCSH is best and meets the radiation hardness requirement for LED-fiber monitor of BLM and BESIII EMC. The transmission of SeCS and SCSH decreased to around 80% under the 60Co-irradiation of 5 Gy and 10 Gy, respectively. The radiation hardness of SeCS is worst because of its silicone cladding. Recovery characteristics: 60Co-irradiated by the same doses, there were both more annealable and more permanent color centers formed in SeCS than SCSL, and for the same kind of fibers, as long as the irradiated doses are under a certain amount (for example, less than 5 Gy for SeCS), the higher the doses, both the more annealable and the more permanent color centers are formed.

Xue, Zhen; Hu, Tao; Fang, Jian; Xu, Zi-Zong; Wang, Xiao-Lian; Lü, Jun-Guang; Zhou, Li; Cai, Xiao; Yu, Bo-Xiang; Wang, Zhi-Gang; Sun, Li-Jun; Sun, Xi-Lei; Zhang, Ai-Wu

2012-02-01

118

A PCI Express optical link based on low-cost transceivers qualified for radiation hardness  

NASA Astrophysics Data System (ADS)

In this paper we want to demonstrate that an optical physical medium is compatible with the second generation of PCI Express. The benefit introduced by the optical decoupling of a PCI Express endpoint is twofold: it allows for a geographical detachment of the device and it remains compliant with the usual PCI accesses to the legacy I/O and memory spaces. We propose two boards that can bridge the PCI Express protocol over optical fiber. The first is a simple optical translator while the second is a more robust switch developed for connecting up to four devices to a single host. Such adapters are already working in the control and data acquisition system of a particle detector at CERN and hence they had been qualified for radiation hardness. The positive outcomes of the radiation tests of four types of off-the-shelf transceivers are finally reported.

Triossi, A.; Barrientos, D.; Bellato, M.; Bortolato, D.; Isocrate, R.; Rampazzo, G.; Ventura, S.

2013-02-01

119

Foreign technology assessment: Environmental evaluation of a radiation-hard oscillator/divider  

NASA Astrophysics Data System (ADS)

Salford Electrical Instruments, Ltd., and the General Electric Company's Hirst Research Center, under contract to the United Kingdom's (UK) Ministry of Defence, developed a radiation-hard, leadless chip-carrier-packaged oscillator/divider. Two preproduction clocks brought to Sandia National Laboratories (SNL) by a potential SNL customer underwent mechanical and thermal environmental evaluation. Because of the subsequent failure of one device and the deteriorating condition of another device, the devices were not subjected to radiation tests. The specifics of the environmental evaluation performed on these two clocks and the postmortem analysis of one unit, which ultimately failed, are described. Clock startup time versus temperature studies were also performed and compared to an SNL-designed clock having the same fundamental frequency.

Dvorack, M. A.

1993-03-01

120

Ultimate limits for the radiation hardness of silicon strip detectors for sLHC  

NASA Astrophysics Data System (ADS)

The new SuperLHC upgrade will impose severe restrictions on the radiation hardness of silicon detectors since a maximum fluence of 1016 particles/cm2 is foreseen in the innermost region. Microstrip detectors have been fabricated in p-type high resistivity float zone silicon at CNM facilities, been irradiated at the TRIGA reactor in Ljubljana to a fluence of 1016 neutrons/cm2 and characterized at IFIC laboratory. The total collected charge before and after irradiation in the detectors has been measured by Sr90 beta source and by infrared laser illumination. The results show that even after this extreme radiation fluence, p-type substrate detectors collect 3500 electrons when biased at 800 V, which is enough charge to induce a measurable signal with standard readout electronics. P-type strip detectors could be suitable for the middle and even inner regions of sLHC.

Lozano, M.; Campabadal, F.; García, C.; Gonzalez-Sevilla, S.; Lacasta, C.; Lacuesta, V.; Martí, S.; Miñano, M.; Pellegrini, G.; Ullán, M.; Rafí, J. M.

2007-10-01

121

Development of radiation hard semiconductor sensors for charged particle tracking at very high luminosities  

NASA Astrophysics Data System (ADS)

The RD50 collaboration (sponsored by the European Organization for Nuclear Research CERN) has been exploring the development of radiation hard semiconductor devices for very high-luminosity colliders since 2002. The target fluence to qualify detectors set by the anticipated dose for the innermost tracking layers of the future upgrade of the CERN large hadron collider (LHC) is 1016 1 MeV neutron equivalent (neq) cm-2. This is much larger than typical fluences in space, but is mainly limited to displacement and total dose damage, without the single-event effects typical for the space environment. RD50 investigates radiation hardening from many angles, including: Search for alternative semiconductor to replace silicon, improvement of the intrinsic tolerance of the substrate material (p- vs. n-type, initial doping concentration, oxygen concentration), optimization of the readout geometry (collection of holes or electrons, surface treatment), novel detector designs (3D, edge-less, interconnects).

Betancourt, Christopher; Fadeyev, Vitaliy; Sadrozinski, Hartmut F.; Wright, John

2010-08-01

122

Application of spallation neutron sources in support of radiation hardness studies  

NASA Astrophysics Data System (ADS)

High-power spallation neutron sources offer a unique opportunity to gather critical measurements on the very early transient displacement damage in semiconductors. This paper discusses the important attributes of spallation neutron facilities used for investigating the transient radiation hardness of semiconductors. By comparing the attributes of some different types of radiation facilities currently used for semiconductor damage characterization, a new and important role for spallation neutron sources is identified. Comparisons are made between the attributes of the spallation neutron source and fast-burst reactors, water-moderated reactors, ion microbeams, and electron accelerators. By incorporating electromagnetic shielding, photocurrent shunts and new experimental techniques, testing at spallation neutron sources has permitted the earliest measurements of transient gain to be lowered from the previous time of 250 ?s, achieved at fast-burst reactors, to 8 ?s. This is over a factor of 30 improvement in the test capability.

Griffin, Patrick; King, Donald; Kolb, Norm

2006-06-01

123

Radiation damage of electronic components in space environment  

NASA Astrophysics Data System (ADS)

The PAMELA apparatus is dedicated to study cosmic rays on board of a satellite mission scheduled to start at the beginning of 2004. All the electronics components of such a mission have to be chosen carefully, because no replacement is possible after launch. Irradiation tests have been performed in order to study effects of highly ionizing particles on chips and to evaluate thresholds for Single Event Upset and Latch-up. The first effect, observed in digital components, is a radiation-induced change of state in a memory cell and gives rise to loss of the stored information. The second one, present also in analog components, happens when a parasitic conduction channel opens through the chip: this can fuse the component unless a protection circuit limits the current flow. Estimates of on-orbit fluxes and results of dedicated beam tests are reported.

Boscherini, M.; Adriani, O.; Bongi, M.; Bonechi, L.; Castellini, G.; D'Alessandro, R.; Gabbanini, A.; Grandi, M.; Menn, W.; Papini, P.; Ricciarini, S. B.; Simon, M.; Spillantini, P.; Straulino, S.; Taccetti, F.; Tesi, M.; Vannuccini, E.

2003-11-01

124

Hard X-ray component in Sco X-1 spectrum: Synchrotron emission from a nano quasar  

NASA Astrophysics Data System (ADS)

Sco X-1 is a low mass X-ray binary system and with the recent observations of a resolved radio jet, the source has been included in the list of galactic microquasars. The observed spectral data in the 2-20 keV energy band fits a thermal emission. Above 20 keV, a hard tail has been reported on occasions. During our continuing balloon borne X-ray survey in the 20-200 keV region using high sensitivity Large Area Scintillation counter Experiment, Sco X-1 was observed on two different occasions. Even though the total X-ray luminosity of the source was different, the spectral nature of the source did not show any variation. The presence of hard X-ray flux is unmistakable. We present the spectral and temporal data in the hard X-ray band and discuss the results in terms of geometrical characteristics of X-ray source and its observed temporal properties. We note that the jet activity is similar to the microquasars, however, the absence of the large magnitude abrupt changes in X-ray light curve compared to GRS1915 + 105 suggest that the quasar-like behaviour is at a nano scale.

Manchanda, R. K.

125

Radiation hardness of fiber optic sensors for monitoring and remote handling applications in nuclear environments  

Microsoft Academic Search

We report on our irradiation experiments on different types of fiber-optic sensors, including three types of commercially available temperature sensors, a multimode extrinsic Fabry-Perot cavity strain sensor and fiber Bragg- gratings. For the temperature sensors, results show that gamma radiation does not interfere with the basic sensing mechanism and that the most critical component turns out to be the optical

Francis Berghmans; Alberto F. Fernandez; Benoit Brichard; Frans Vos; Marc C. Decreton; Andrei Gusarov; Olivier Deparis; Patrice Megret; Michel Blondel; Serge Caron; Andre Morin

1999-01-01

126

Effects of gamma radiation on hard dental tissues of albino rats using scanning electron microscope – Part 1  

Microsoft Academic Search

In the present study, 40 adult male albino rats were used to study the effect of gamma radiation on the hard dental tissues (enamel surface, dentinal tubules and the cementum surface). The rats were irradiated at 0.2, 0.5, 1.0, 2.0, 4.0 and 6.0 Gy gamma doses. The effects of irradiated hard dental tissues samples were investigated using a scanning electron microscope.

Nabil El-Faramawy; Reham Ameen; Khaled El-Haddad; Ahmed Maghraby; Medhat El-Zainy

2011-01-01

127

Radiation hardness of high resistivity magnetic Czochralski silicon detectors after gamma, neutron, and proton radiations  

Microsoft Academic Search

High resistivity magnetic Czochralski Si detectors were irradiated with 60Co gamma rays, neutrons, and protons to various doses\\/fluences, along with control float zone Si detectors. 1) It has been found that for gamma radiation, magnetic Czochralski Si detectors behave similarly to the high-temperature, long-time (HTLT) oxygenated float zone Si detectors. There is no space charge sign inversion and there is

Zheng Li; Jaakko Harkonen; Wei Chen; J. Kierstead; Panja Luukka; Eija Tuominen; Etuovine Tuovinen; Elea Verbitskaya; Vladimir Eremin

2004-01-01

128

Hard plastic cladding fiber (HPCF) based optical components for high speed short reach optical communications  

Microsoft Academic Search

We developed the primary components applicable to HPCF links for short reach (SR) and very short reach (VSR) data communication systems. We fabricated 4x4 HPCF fused taper splitter, HPCF pigtailed VCSEL and PIN photodiode for high speed short reach communications and characterized back to back transmission performance of the link composed of these components by measuring eye diagrams and jitters.

Jun Ki Kim; Dong Uk Kim; Tae Young Kim; Chang Soo Park; Kyunghwan Oh

2006-01-01

129

Influence of different components in a TPV PP/EPDM based with low hardness  

NASA Astrophysics Data System (ADS)

Thermoplastic vulcanizates (TPVs) are a class of polymeric material obtained by dynamic vulcanization of an elastomer in a melted thermoplastic matrix. This work intend to evaluate different variables in the production of low hardness TPVs made of polypropylene (PP) and ethylene propylene rubber (EPDM), as well the optimization of the variables looking for TPVs with improved performance. In the Study I the influence of PP crystallinity were evaluated, in the Study II the effects of different amounts of dicumyl peroxide (DCP) were evaluated and in the Study III the amount of the phenolic resin were evaluated. This extended abstract presents, in a more detailed way, the results considering the curative phenolic resin content (Study III). The others results and discussions are briefly described in the results and discussions section. The compounds were obtained in a closed mixing chamber and their processability properties, swelling, hardness and tensile strength were evaluated. With the results obtained were possible to evaluate the influence of different ingredients in the TPVs properties. The results were discussed and presented looking for a better understanding of the influence of this variable in the final product, as well the correlation between then.

Gheller, J.; Jacobi, M. M.

2014-05-01

130

Forecasting noise and radiation hardness of CMOS front-end electronics beyond the 100 nm frontier  

NASA Astrophysics Data System (ADS)

The progress of industrial microelectronic technologies has already overtaken the 130 nm CMOS generation that is currently the focus of IC designers for new front-end chips in LHC upgrades and other detector applications. In a broader time span, sub-100 nm CMOS processes may become appealing for the design of very compact front-end systems with advanced integrated functionalities. This is especially true in the case of pixel detectors, both for monolithic devices (MAPS) and for hybrid implementations where a high resistivity sensor is connected to a CMOS readout chip. Technologies beyond the 100 nm frontier have peculiar features, such as the evolution of the device gate material to reduce tunneling currents through the thin dielectric. These new physical device parameters may impact on functional properties such as noise and radiation hardness. On the basis of experimental data relevant to commercial devices, this work studies potential advantages and challenges associated to the design of low-noise and rad-hard analog circuits in these aggressively scaled technologies.

Re, V.; Gaioni, L.; Manghisoni, M.; Ratti, L.; Traversi, G.

2010-05-01

131

EVIDENCE FOR A PHOTOSPHERIC COMPONENT IN THE PROMPT EMISSION OF THE SHORT GRB 120323A AND ITS EFFECTS ON THE GRB HARDNESS-LUMINOSITY RELATION  

SciTech Connect

The short GRB 120323A had the highest flux ever detected with the Gamma-Ray Burst Monitor on board the Fermi Gamma-Ray Space Telescope. Here we study its remarkable spectral properties and their evolution using two spectral models: (1) a single emission component scenario, where the spectrum is modeled by the empirical Band function (a broken power law), and (2) a two-component scenario, where thermal (a Planck-like function) emission is observed simultaneously with a non-thermal component (a Band function). We find that the latter model fits the integrated burst spectrum significantly better than the former, and that their respective spectral parameters are dramatically different: when fit with a Band function only, the E{sub peak} of the event is unusually soft for a short gamma-ray burst (GRB; 70 keV compared to an average of 300 keV), while adding a thermal component leads to more typical short GRB values (E{sub peak} {approx} 300 keV). Our time-resolved spectral analysis produces similar results. We argue here that the two-component model is the preferred interpretation for GRB 120323A based on (1) the values and evolution of the Band function parameters of the two component scenario, which are more typical for a short GRB, and (2) the appearance in the data of a significant hardness-intensity correlation, commonly found in GRBs, when we employee two-component model fits; the correlation is non-existent in the Band-only fits. GRB 110721A, a long burst with an intense photospheric emission, exhibits the exact same behavior. We conclude that GRB 120323A has a strong photospheric emission contribution, observed for the first time in a short GRB. Magnetic dissipation models are difficult to reconcile with these results, which instead favor photospheric thermal emission and fast cooling synchrotron radiation from internal shocks. Finally, we derive a possibly universal hardness-luminosity relation in the source frame using a larger set of GRBs (L{sub i}{sup Band} = (1.59 {+-} 0.84) x 10{sup 50} (E{sub peak,i}){sup 1.33{+-}0.07} erg s{sup -1}), which could be used as a possible redshift estimator for cosmology.

Guiriec, S.; McEnery, J.; Gehrels, N. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Daigne, F.; Hascoeet, R.; Mochkovitch, R. [Institut d'Astrophysique de Paris UMR 7095 Universite Pierre et Marie Curie-Paris 06 (France); CNRS 98 bis bd Arago, F-75014 Paris (France); Vianello, G. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ryde, F. [Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Kouveliotou, C. [Office of Science and Technology, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Xiong, S.; Bhat, P. N.; Burgess, J. M. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Foley, S.; McGlynn, S. [UCD School of Physics, University College Dublin, Dublin 4 (Ireland); Gruber, D., E-mail: sylvain.guiriec@nasa.gov [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)

2013-06-10

132

Pair Distribution Function in Polar Fluid-Hard Wall Systems. Long Range Components.  

National Technical Information Service (NTIS)

Using the diagrammatic technique we prove that the total correlation function for dipolar fluid systems in front of an ideal wall has four long range components. 21 refs. (Atomindex citation 20:064680)

M. E. Boudh-Hir

1989-01-01

133

Spectral differences between the radio-loud and radio-quiet low-hard states of GRS 1915+105: Possible detection of synchrotron radiation in X-rays  

NASA Astrophysics Data System (ADS)

The Galactic microquasar GRS 1915+105 exhibits several episodes of steady X-ray emission characterized by a hard power-law spectrum and intense Quasi Periodic Oscillations. It is known that there are two types of such low-hard states, one with steady radio emission and the other without any significant radio emission. We present the results of a detailed X-ray spectroscopic study of GRS 1915+105, using data from the Rossi X-ray Timing Explorer obtained during various episodes of the low-hard states of the source. We show that there are distinct X-ray spectral differences between the radio-quiet and radio-loud low-hard states of the source. The X-ray spectra of the radio-quiet low-hard state is best described by a model consisting of a multicolor disk-blackbody and a Comptonized component, whereas the X-ray spectra of radio-loud low-hard state requires a model consisting of three components: a multicolor disk-blackbody, a Comptonized component and a power-law, for statistically and physically acceptable fits. We attempt to model the presence of this additional power-law component as due to synchrotron radiation which is responsible for the radio and infrared radiation from the source. We show that a simple adiabatically expanding jet model for the synchrotron radiation can account for the observed X-ray flux for reasonable values of the magnetic field and the mass outflow rate. This is the first report of detection of the synchrotron radiation in the X-ray band for this source.

Vadawale, S. V.; Rao, A. R.; Chakrabarti, S. K.

2001-06-01

134

Radiation hardness of fiber-optic sensors for monitoring and remote handling applications in nuclear environments  

Microsoft Academic Search

We report on our irradiation experiments on different types of fiber-optic sensors, including three types of commercially available temperature sensors, a multimode extrinsic Fabry-Perot cavity strain sensor and fiber Bragg-gratings. For the temperature sensors, results show that gamma radiation does not interfere with the basic sensing mechanism and that the most critical component turns out to be the optical fiber

Francis Berghmans; Alberto Fernandez Fernandez; Benoît Brichard; Frans Vos; Marc Decréton; Andrei Gusarov; Olivier Deparis; Patrice Mégret; Michel Blondel; Serge Caron; André Morin

1998-01-01

135

Modeling of Radiation Hardness of a CCD with High-Speed Column Parallel Readout  

NASA Astrophysics Data System (ADS)

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. Radiation hardness is an important aspect in the CCD development. Bulk radiation damage in the silicon leads to electron traps and hence to charge transfer inefficiency (CTI). The effects of the two trap levels 0.17 and 0.44 eV are considered. We have extended our Analytic Model to include the effects of the shape of the signal charge packet and the clock voltage on the CTI determination. The CTI values determined with the Analytic Model largely agree with those from a full TCAD simulation.

Sopczak, André; Aoulmit, Salim; Bekhouche, Khaled; Bowdery, Chris; Buttar, Craig; Damerell, Chris; Djendaoui, Dahmane; Dehimi, Lakhdar; Greenshaw, Tim; Koziel, Michal; Maneuski, Dzmitry; Nomerotski, Andrei; Stefanov, Konstantin; Tikkanen, Tuomo; Woolliscroft, Tim; Worm, Steve

2009-12-01

136

High Speed, Radiation Hard CMOS Pixel Sensors for Transmission Electron Microscopy  

NASA Astrophysics Data System (ADS)

CMOS monolithic active pixel sensors are currently being established as the technology of choice for new generation digital imaging systems in Transmission Electron Microscopy (TEM). A careful sensor design that couples ?m-level pixel pitches with high frame rate readout and radiation hardness to very high electron doses enables the fabrication of direct electron detectors that are quickly revolutionizing high-resolution TEM imaging in material science and molecular biology. This paper will review the principal characteristics of this novel technology and its advantages over conventional, optically-coupled cameras, and retrace the sensor development driven by the Transmission Electron Aberration corrected Microscope (TEAM) project at the LBNL National Center for Electron Microscopy (NCEM), illustrating in particular the imaging capabilities enabled by single electron detection at high frame rate. Further, the presentation will report on the translation of the TEAM technology to a finer feature size process, resulting in a sensor with higher spatial resolution and superior radiation tolerance currently serving as the baseline for a commercial camera system.

Contarato, Devis; Denes, Peter; Doering, Dionisio; Joseph, John; Krieger, Brad

137

Photodiode radiation hardness, lyman-alpha emitting galaxies and photon detection in liquid argon neutrino detectors  

NASA Astrophysics Data System (ADS)

My dissertation is comprised of three projects: 1) studies of Lyman-alpha Emitting galaxies (LAEs), 2) radiation hardness studies of InGaAs photodiodes (PDs), and 3) scintillation photon detection in liquid argon (LAr) neutrino detectors. I began work on the project that has now become WFIRST, developing a science case that would use WFIRST after launch for the observation of LAEs. The radiation hardness of PDs was as an effort to support the WFIRST calibration team. When WFIRST was significantly delayed, I joined an R&D effort that applied my skills to work on photon detection in LAr neutrino detectors. I report results on a broadband selection method developed to detect high equivalent width (EW) LAEs. Using photometry from the CFHT-Legacy Survey Deep 2 and 3 fields, I have spectroscopically confirmed 63 z=2.5-3.5 LAEs using the WIYN/Hydra spectrograph. Using UV continuum-fitting techniques I computed properties such as EWs, internal reddening and star formation rates. 62 of my LAEs show evidence to be normal dust-free LAEs. Second, I present an investigation into the effects of ionizing proton radiation on commercial off-the-shelf InGaAs PDs. I developed a monochromator-based test apparatus that utilized NIST-calibrated reference PDs. I tested the PDs for changes to their dark current, relative responsivity as a function of wavelength, and absolute responsivity. I irradiated the test PDs using 30, 52, and 98 MeV protons at the IU Cyclotron Facility. I found the InGaAs PDs showed increased dark current as the fluence increased with no evidence of broadband response degradation at the fluences expected at an L2 orbit and a 10-year mission lifetime. Finally, I detail my efforts on technology development of both optical detector technologies and waveshifting light guide construction for LAr vacuum UV scintillation light. Cryogenic neutrino detectors use photon detection for both accelerator based science and for SNe neutrino detection and proton decay. I have developed waveshifter doped cast acrylic light guides that convert scintillation light and guide the waveshifted light to SiPMs detectors.

Baptista, Brian

138

Dynamics of the optical response of Nd:YAG to ionizing radiation: testing for radiation hardness using UV laser radiation  

Microsoft Academic Search

The optical response of single-crystal Nd:YAG and Cr3+:YAG to ionizing radiation has been previously studied using intense pulses of gamma-rays at the HERMES III facility at Sandia National Laboratory, where samples' transmission at 1064 nm was observed during exposure to gamma radiation. A further study of similar samples when exposed to 10-ns UV laser pulses reveals nearly identical dynamics, with

B. L. Glebov; K. Simmons-Potter; D. C. Meister

2009-01-01

139

The effect of oxygen impurities on radiation hardness of FZ silicon detectors for HEP after neutron, proton and gamma irradiation  

Microsoft Academic Search

The radiation hardness for fast neutrons, high energy protons and 60Co gamma rays of planar detectors processed from highly oxygenated silicon detectors obtained by using high temperature (1200°C), long time (> 200 hours) oxidation technology, are compared with standard silicon detectors. For fast neutron irradiation it is found that there is no advantage of using highly oxygenated silicon FZ detectors

B. Dezillie; Z. Li; V. Eremin; W. Chen; L. J. Zhao

2000-01-01

140

The effect of oxygen impurities on radiation hardness of FZ silicon detectors for HEP after neutron, proton and gamma irradiation  

Microsoft Academic Search

Radiation hardness for fast neutrons, high energy protons and 60Co gamma rays of planar detectors processed from highly oxygenated silicon detectors obtained by using the high temperature (1200°C), long time (>200 hours) oxidation technology, are compared with standard silicon detectors. For fast neutron irradiation it is found that there is no advantage of using highly oxygenated silicon FZ detectors as

B. Dezillie; Z. Li; V. Eremin; W. Chen; L. J. Zhao

1999-01-01

141

Investigation of the influence of liner hard-splices on duct radiation\\/propagation and mode scattering  

Microsoft Academic Search

In a turbofan engine, usually, the acoustically lined region consists of several liner segments separated by longitudinal hard-splices due to manufacturing. The non-uniform impedance in the circumferential direction will excite other circumferential modes besides the incident modes. Consequently, the acoustic propagation in and radiation from a turbofan is considerably different from that of an uniform impedance. To investigate the effect

Bing Yang; T. Q. Wang

2008-01-01

142

Irradiation of thin diamond detectors and radiation hardness tests using MeV protons  

NASA Astrophysics Data System (ADS)

Although numerous studies have confirmed the superb radiation hardness of diamond for high-energy (above 100 MeV) protons, almost no data have been reported in the MeV energy range. Because the interaction mechanism that dominates the displacement damage cross section is different for these two energy regimes, it could be misleading to simply extrapolate the results of previous papers down to low energies. Therefore, the radiation tolerance of a 50 ?m thick single-crystal CVD diamond detector was tested by irradiating it with 4.5 MeV protons. The scanning microbeam allowed for the selective introduction of damage to a small area of the detector. The ion beam-induced current (IBIC) was used to monitor the charge collection efficiency (CCE) degradation due to the electrically active defects produced. The irradiation was stopped when a signal degradation of nearly 3% was observed. For comparison, the procedure was repeated on a 50 ?m thick silicon surface barrier detector (SSBD), for which a significantly higher proton fluence was required to reach the same signal decrease as in the diamond detector. This result can be explained by the different recombination rates of the vacancies and interstitials created in the two materials. The transport properties of electrons and holes in the damaged and virgin areas of the diamond detector were also investigated by 500 keV protons and 6 MeV carbon ions as short-range IBIC probes. The mobility-lifetime products calculated for both charge carriers after fitting the single-carrier Hecht equation indicated that there was more pronounced electron trapping by the radiation-induced defects. The frequently reported effect of polarization in diamond was successfully avoided for 500 keV protons but still remained for 6 MeV carbon ions because an order of magnitude higher ionization rate.

Grilj, V.; Skukan, N.; Jakši?, M.; Kada, W.; Kamiya, T.

2013-07-01

143

Tunnel generation and locking stimulated Raman radiation components  

SciTech Connect

Stimulated Raman radiation is considered in a ring optical resonator. It is supposed that the resonator is partly filled with a condensed medium at the full length of the medium close to several tunnel lengths. A Raman-active medium and an optical waveguide are assumed to occupy a part of the condensed medium. The feasibility is shown of tunnel generation and synchronization of a great number of Stokes components of stimulated Raman radiation. Here, femtosecond light pulses are shown to be formed in a spacing adjacent to the Raman-active medium, the pulses being single over the period T=2..pi../..omega.. /SUB R/ (..omega.. /SUB R/ is the Raman frequency shift). Predicted and considered also are tunnel generation and locking of new light modes in an optical parametric oscillator. The effects are due to a correction for the dispersion of the full effective refractive index of the medium inside the resonator. Numerical calculations of the correction for a glass thin-film optical waveguide, quartz, and the Raman-active media CaCO/sub 3/, C/sub 6/H/sub 6/, CS/sub 2/ inside the resonator are represented. Here, five or six Stokes components are shown to be generated and locked for CaCO/sub 3/ and C/sub 6/H/sub 6/, eight Stokes components for CS/sub 2/. A similar numerical calculation is represented for the active medium LiNbO/sub 3/ in the corresponding optical parameteric oscillator. Here, new modes covering a frequency bandwidth of 5000 cm/sup -1/ are shown to be feasible. Noted and discussed is also a higher-order correction for the effective refractive index dispersion making it feasible to broaden the frequency bandwidth for tunnel generation and locking.

Lugovoi, V.N.

1984-08-01

144

Development of a hard nano-structured multi-component ceramic coating by laser cladding  

Microsoft Academic Search

The present paper reports laser-assisted synthesis of a multi-component ceramic composite coating consisting of aluminum oxide, titanium di-boride and titanium carbide (Al2O3–TiB2–TiC). A pre-placed powder mixture of aluminum (Al), titanium oxide (TiO2) and boron carbide (B4C) was made to undergo self-propagating high-temperature synthesis (SHS) by laser triggering. Laser subsequently effected cladding of the products of SHS on the substrate. The

Manoj Masanta; P. Ganesh; Rakesh Kaul; A. K. Nath; A. Roy Choudhury

2009-01-01

145

AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics  

SciTech Connect

This presentation provides an overview of robust, radiation hard AlGaN optoelectronic devices and their applications in space exploration & high energy density physics. Particularly, deep UV LED and deep UV photodiodes are discussed with regard to their applications, radiation hardness and space qualification. AC charge management of UV LED satellite payload instruments, which were to be launched in late 2012, is covered.

Sun, K. X.

2011-05-31

146

X-Ray Ccds for Space Applications: Calibration, Radiation Hardness, and Use for Measuring the Spectrum of the Cosmic X-Ray Background  

NASA Astrophysics Data System (ADS)

This thesis has two distinct components. One concerns the physics of the high energy resolution X-ray charge coupled devices (CCD) detectors used to measure the cosmic X-ray background (XRB) spectrum. The other involves the measurements and analysis of the XRB spectrum and instrumental background with these detectors on board the advanced satellite for cosmology and astrophysics (ASCA). The XRB has a soft component and a hard component divided at ~2 keV. The hard component is extremely isotropic, suggesting a cosmological origin. The soft component is extremely anisotropic. A galactic component most likely dominates the soft band with X-ray line emission due to a hot plasma surrounding the solar system. ASCA is one of the first of a class of missions designed to overlap the hard and soft X-ray bands. The X-ray CCD's energy resolution allows us to spectrally separate the galactic and cosmological components. Also, the resolution offers the ability to test several specific cosmological models which would make up the XRB. I have concentrated on models for the XRB origin which include active galactic nuclei (AGN) as principal components. I use ASCA data to put spectral constraints on the AGN synthesis model for the XRB. The instrumental portion of this thesis concerns the development and calibration of the X-ray CCDs. I designed, built and operated an X-ray calibration facility for these detectors. It makes use of a reflection grating spectrometer to measure absolute detection efficiency, characteristic absorption edge strengths, and spectral redistribution in the CCD response function. Part of my thesis research includes a study of radiation damage mechanisms in CCDs. This work revealed radiation damage-induced degradation in the spectral response to X-rays. It also uncovered systematic effects which affect both data analysis and CCD design. I have developed a model involving trap energy levels in the CCD band gap structure. These traps reduce the efficiency in which charge transfers through the CCD. I have used the model to extract information about characteristic trapping and detrapping times for electrons in these energy levels out of the X-ray data. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Gendreau, Keith Charles

1995-01-01

147

Investigation of the influence of liner hard-splices on duct radiation/propagation and mode scattering  

NASA Astrophysics Data System (ADS)

In a turbofan engine, usually, the acoustically lined region consists of several liner segments separated by longitudinal hard-splices due to manufacturing. The non-uniform impedance in the circumferential direction will excite other circumferential modes besides the incident modes. Consequently, the acoustic propagation in and radiation from a turbofan is considerably different from that of an uniform impedance. To investigate the effect of liner hard-splices on acoustic radiation and propagation, a boundary integral equation method (BIEM) in two-dimensional (2D) is expanded into a three-dimensional form. In this model, an axially uniform inflow passes a cylindrical finite duct and the liner inside the duct may be circumferentially or axially non-uniform. The verifications are presented and the influence of hard-splices is investigated. Then an infinite duct model is developed to investigate the mechanism of mode scattering excited by a circumferentially non-uniform boundary. BIEM is combined with the mode-matching method. The model is validated by comparing with the analytical result in an infinite circular duct with a hard wall. Then a variety of liner configurations containing periodic/non-periodic hard-splices are studied and the mode scattering mechanism is discussed.

Yang, Bing; Wang, T. Q.

2008-09-01

148

Hard plastic cladding fiber (HPCF) based optical components for high speed short reach optical communications  

NASA Astrophysics Data System (ADS)

We developed the primary components applicable to HPCF links for short reach (SR) and very short reach (VSR) data communication systems. We fabricated 4x4 HPCF fused taper splitter, HPCF pigtailed VCSEL and PIN photodiode for high speed short reach communications and characterized back to back transmission performance of the link composed of these components by measuring eye diagrams and jitters. Adapting the fusion-tapering technique for glass optical fiber, we successfully fabricated a 4x4 HPCF fused taper coupler. The HPCF with a core diameter of 200?m and an outer diameter of 230?m had step refractive index of 1.45 and 1.40 for the core and the clad. The optimized fusion length and tapering waist which make minimum insertion loss of about 7dB and uniform output power splitting ratio with less than 0.5dB are 13mm and 150µm, respectively. As a light source for VSR networks, we chose a vertical cavity surface emitting laser (VCSEL) and developed a package with a HPCF pigtail. After positioning VCSEL and HPCF that made a minimum coupling loss, we glued the HPCF inside ceramic ferrule housing. In HPCF-PIN PD packaging, we added a micro polymer lens tip onto the HPCF ends to match the mode field area to the sensitive area of GaAs or InGaAs PIN PD. Coupling between a PIN PD chip and the lensed HPCF was optimized with the radius of curvature of 156µm with a low coupling loss of 0.3dB, which is compatible to conventional MMF-PD packaging. For 1.25 Gbps data rate, the eyes adequate to eye mask in gigabit Ethernet were wide open after all HPCF transmission link and no significant power penalty was observed.

Kim, Jun Ki; Kim, Dong Uk; Kim, Tae Young; Park, Chang Soo; Oh, Kyunghwan

2006-10-01

149

Generation of radicals in hard biological tissues under the action of laser radiation  

NASA Astrophysics Data System (ADS)

The formation of radicals upon UV and IR laser irradiation of some biological tissues and their components was studied by the EPR technique. The radical decay kinetics in body tissue specimens after their irradiation with UV light were described by various models. By the spin trapping technique, it was shown that radicals were not produced during IR laser irradiation of cartilaginous tissue. A change in optical absorption spectra and the dynamics of optical density of cartilaginous tissue, fish scale, and a collagen film under exposure to laser radiation in an air, oxygen, and nitrogen atmosphere was studied.

Sviridov, Alexander P.; Bagratashvili, Victor N.; Sobol, Emil N.; Omelchenko, Alexander I.; Lunina, Elena V.; Zhitnev, Yurii N.; Markaryan, Galina L.; Lunin, Valerii V.

2002-07-01

150

Radiation-Hard SpaceWire/Gigabit Ethernet-Compatible Transponder  

NASA Technical Reports Server (NTRS)

A radiation-hard transponder was developed utilizing submicron/nanotechnology from IBM. The device consumes low power and has a low fabrication cost. This device utilizes a Plug-and-Play concept, and can be integrated into intra-satellite networks, supporting SpaceWire and Gigabit Ethernet I/O. A space-qualified, 100-pin package also was developed, allowing space-qualified (class K) transponders to be delivered within a six-month time frame. The novel, optical, radiation-tolerant transponder was implemented as a standalone board, containing the transponder ASIC (application specific integrated circuit) and optical module, with an FPGA (field-programmable gate array) friendly parallel interface. It features improved radiation tolerance; high-data-rate, low-power consumption; and advanced functionality. The transponder utilizes a patented current mode logic library of radiation-hardened-by-architecture cells. The transponder was developed, fabricated, and radhard tested up to 1 MRad. It was fabricated using 90-nm CMOS (complementary metal oxide semiconductor) 9 SF process from IBM, and incorporates full BIT circuitry, allowing a loop back test. The low-speed parallel LVCMOS (lowvoltage complementary metal oxide semiconductor) bus is compatible with Actel FPGA. The output LVDS (low-voltage differential signaling) interface operates up to 1.5 Gb/s. Built-in CDR (clock-data recovery) circuitry provides robust synchronization and incorporates two alarm signals such as synch loss and signal loss. The ultra-linear peak detector scheme allows on-line control of the amplitude of the input signal. Power consumption is less than 300 mW. The developed transponder with a 1.25 Gb/s serial data rate incorporates a 10-to-1 serializer with an internal clock multiplication unit and a 10-1 deserializer with internal clock and data recovery block, which can operate with 8B10B encoded signals. Three loop-back test modes are provided to facilitate the built-in-test functionality. The design is based on a proprietary library of differential current switching logic cells implemented in the standard 90-nm CMOS 9SF technology from IBM. The proprietary low-power LVDS physical interface is fully compatible with the SpaceWire standard, and can be directly connected to the SFP MSA (small form factor pluggable Multiple Source Agreement) optical transponder. The low-speed parallel interfaces are fully compatible with the standard 1.8 V CMOS input/output devices. The utilized proprietary annular CMOS layout structures provide TID tolerance above 1.2 MRad. The complete chip consumes less than 150 mW of power from a single 1.8-V positive supply source.

Katzman, Vladimir

2012-01-01

151

Synchronous radiation with Er:YAG and Ho:YAG lasers for efficient ablation of hard tissues  

PubMed Central

Er:YAG and Ho:YAG laser beams were combined to irradiate hard tissues to achieve highly efficient ablation with low laser power. The delay time between pulses of the two lasers was controlled to irradiate alumina ceramic balls used as hard tissue models. With optimized delay time, the combined laser beam perforated the sample 40% deeper than independent radiation by either an Er:YAG or Ho:YAG laser. An ultra-high-speed camera and an infrared thermography camera were used to observe and investigate the ablation mechanisms.

Watanabe, Tomonori; Iwai, Katsumasa; Katagiri, Takashi; Matsuura, Yuji

2010-01-01

152

Er:YAG laser radiation for soft and hard urological tissue treatment  

NASA Astrophysics Data System (ADS)

Er:YAG laser (wavelength 2.94 ?m) operating both in free-running and Q-switched regime was designed and developed for the purpose of ureter wall perforation or incision, and urinary stones fragmentation. Component of this system was a special transfer part consisted of a cyclic olefin polymer-coated silver (COP/Ag) hollow glass waveguide (inner/outer diameter 700/850 ?m or 320/450 ?m) with a sealed cap for a contact treatment. Maximum pulse interaction energy and length for free-running Er:YAG laser were 100 mJ and 200 ?s, respectively (corresponding intensity was 130 kW/cm2 for the 700 ?m waveguide and 500 kW/cm2 for the 320 ?m waveguide). Maximum interaction pulse energy and length in Q-switched regime were 30 mJ and 70 ns, respectively (corresponding intensity was 111 MW/cm2 for the 700 ?m waveguide and 357 MW/cm2 for the 320 ?m waveguide). Basic interaction characteristics and parameters of ureter wall perforation and urinary stones fragmentation were found. For that reason the number of pulses needed for the perforation of the ureter wall tissue (thickness ~1mm), ablation threshold and ablation rate were measured for free-running and Q-switched Er:YAG laser radiation. Subsequently, the investigated tissue samples were histologically evaluated after the interaction. The ablation rate of the Q-switched Er:YAG laser radiation was higher compared to the free-running radiation. The application of Q-switched Er:YAG laser radiation on ureter tissue resulted in minimum tissue alteration (up to 50 ?m from the surface) without any influence on the deeper layers. The possibility of urinary stones perforation with free-running Er:YAG laser radiation (with maximum interaction energy) was also demonstrated.

Koranda, Petr; Jelínkova, Helena; N?mec, Michal; Köhler, Oto; Drlík, Pavel; Pokorný, Jan; Miyagi, Mitsunobu; Iwai, Katsumasa; Shi, Yi-Wei; Matsuura, Yuji

2006-03-01

153

Improved radiation hardness to low-energy protons for oxygenated Si detectors with thermal donors  

NASA Astrophysics Data System (ADS)

Silicon detectors have been made on oxygenated silicon with the incorporation of thermal donors during the oxidation process based on BNL's high-temperature long-time (thermal donor) (HTLT(TD)) technology. The initial doping concentration in HTLT(TD) silicon detectors is twice more than that of standard silicon detectors (same starting material, but no HTLT process), with TD being the dominant donor. Standard and HTLT(TD) silicon detectors have been irradiated by 10 MeV protons up to 2.5×10 14 p/ cm2. It has been found that the increase rate ( ?) of the space charge concentration ( Neff) after space charge sign inversion (SCSI) in HTLT(TD) silicon detectors is about half of that in standard silicon detectors. Further improvement in proton radiation hardness has been observed in terms of the SCSI fluence. The SCSI fluence for HTLT(TD) silicon detectors is more than four times higher than that of standard detectors, although the corresponding ratio of initial space charge concentrations between the two groups of detectors is about two. This result implies that the SCSI is greatly delayed in HTLT(TD) silicon detector compared with silicon detectors with similar initial space charge (all phosphorus) concentration (lower resistivity standard silicon detectors).

Houdayer, A.; Lebel, C.; Leroy, C.; Li, Z.; Verbitskaya, E.

2003-10-01

154

Radiation Hard Bandpass Filters for Mid- to Far-IR Planetary Instruments  

NASA Technical Reports Server (NTRS)

We present a novel method to fabricate compact metal mesh bandpass filters for use in mid- to far-infrared planetary instruments operating in the 20-600 micron wavelength spectral regime. Our target applications include thermal mapping instruments on ESA's JUICE as well as on a de-scoped JEO. These filters are novel because they are compact, customizable, free-standing copper mesh resonant bandpass filters with micromachined silicon support frames. The filters are well suited for thermal mapping mission to the outer planets and their moons because the filter material is radiation hard. Furthermore, the silicon support frame allows for effective hybridization with sensors made on silicon substrates. Using a Fourier Transform Spectrometer, we have demonstrated high transmittance within the passband as well as good out-of-band rejection [1]. In addition, we have developed a unique method of filter stacking in order to increase the bandwidth and sharpen the roll-off of the filters. This method allows one to reliably control the spacing between filters to within 2 microns. Furthermore, our method allows for reliable control over the relative position and orienta-tion between the shared faces of the filters.

Brown, Ari D.; Aslam, Shahid; Chervenack, James A.; Huang, Wei-Chung; Merrell, Willie C.; Quijada, Manuel; Steptoe-Jackson, Rosalind; Wollack, Edward J.

2012-01-01

155

Electromagnetic crystal based terahertz thermal radiators and components  

NASA Astrophysics Data System (ADS)

This dissertation presents the investigation of thermal radiation from three-dimensional electromagnetic crystals (EMXT), as well as the development of a THz rapid prototyping fabrication technique and its application in THz EMXT components and micro-system fabrication and integration. First, it is proposed that thermal radiation from a 3-D EMXT would be greatly enhanced at the band gap edge frequency due to the redistribution of photon density of states (DOS) within the crystal. A THz thermal radiator could thus be built upon a THz EMXT by utilizing the exceptional emission peak(s) around its band gap frequency. The thermal radiation enhancement effects of various THz EMXT including both silicon and tungsten woodpile structures (WPS) and cubic photonic cavity (CPC) array are explored. The DOS of all three structures are calculated, and their thermal radiation intensities are predicted using Planck's Equation. These calculations show that the DOS of the silicon and tungsten WPS can be enhanced by a factor of 11.8 around 364 GHz and 2.6 around 406 GHz respectively, in comparison to the normal blackbody radiation at same frequencies. An enhancement factor of more than 100 is obtained in calculation from the CPC array. A silicon WPS with a band gap around 200 GHz has been designed and fabricated. Thermal emissivity of the silicon WPS sample is measured with a control blackbody as reference. And enhancements of the emission from the WPS over the control blackbody are observed at several frequencies quite consistent with the theoretical predictions. Second, the practical challenge of THz EMXT component and system fabrication is met by a THz rapid prototyping technique developed by us. Using this technique, the fabrications of several EMXTs with 3D electromagnetic band gaps in the 100-400 GHz range are demonstrated. Characterization of the samples via THz Time-domain Spectroscopy (THz-TDS) shows very good agreement with simulation, confirming the build accuracy of this prototyping approach. Third, an all-dielectric THz waveguide is designed, fabricated and characterized. The design is based on hollow-core EMXT waveguide, and the fabrication is implemented with the THz prototyping method. Characterization results of the waveguide power loss factor show good consistency with the simulation, and waveguide propagation loss as low as 0.03 dB/mm at 105 GHz is demonstrated. Several design parameters are also varied and their impacts on the waveguide performance investigated theoretically. Finally, a THz EMXT antenna based on expanding the defect radius of the EMXT waveguide to a horn shape is proposed and studied. The boresight directivity and main beam angular width of the optimized EMXT horn antenna is comparable with a copper horn antenna of the same dimensions at low frequencies, and much better than the copper horn at high frequencies. The EMXT antenna has been successfully fabricated via the same THz prototyping, and we believe this is the first time an EMXT antenna of this architecture is fabricated. Far-field measurement of the EMXT antenna radiation pattern is undergoing. Also, in order to integrate planar THz solid-state devices (especially source and detector) and THz samples under test with the potential THz micro-system fabricate-able by the prototyping approach, an EMXT waveguide-to-microstrip line transition structure is designed. The structure uses tapered solid dielectric waveguides on both ends to transit THz energy from the EMXT waveguide defect onto the microstrip line. Simulation of the transition structure in a back-to-back configuration yields about -15 dB insertion loss mainly due to the dielectric material loss. The coupling and radiation loss of the transition structure is estimated to be -2.115 dB. The fabrication and characterization of the transition system is currently underway. With all the above THz components realized in the future, integrated THz micro-systems manufactured by the same prototyping technique will be achieved, with low cost, high quality, self-sufficiency, and great customizability.

Wu, Ziran

156

Staphylococcus equorum subsp. linens, subsp. nov., a starter culture component for surface ripened semi-hard cheeses.  

PubMed

Two staphylococcal strains, RP29T and RP33, were isolated from the main microflora of a surface ripened Swiss mountain cheese made from raw milk. These two strains were differentiated from the most closely related species Staphylococcus equorum on the basis of DNA-DNA hybridisation and phenotypic characteristics and are proposed as Staphylococcus equorum subsp. linens subsp. nov. They could be distinguished phenotypically from S. equorum by their sensitivity to all 14 tested antibiotics, especially to novobiocin, their incapability to ferment alpha-D-lactose, maltose, sucrose, D-trehalose, D-xylose, L-arabinose, salicin, D-ribose, D-raffinose, D-mannitol, and D-alanine. The GenBank accession numbers for the reference sequences of the 16S rDNA and the hsp60 gene used in this study are AF527483 and AF527484, respectively. 30 tons of a semi-hard Swiss cheese were produced with Staphylococcus equorum subsp. linens DSM 15097T as starter culture component in addition to Debaryomyces hansenii, Geotrichum candidum, Brevibacterium linens, Corynebacterium casei for surface ripened cheeses. The products were sensorically and hygienically perfect. Therefore, Staphylococcus equorum subsp. linens DSM 15097T can be proposed as starter culture component for surface ripened cheeses without any detected antibiotic resistances. The type strain of Staphylococcus equorum subsp. linens is DSM 15097T (CIP 107656T). PMID:12747407

Place, Raymond B; Hiestand, Daniel; Gallmann, Hans Rudolf; Teuber, Michael

2003-03-01

157

Radiation hardness evaluation of a 130 nm SiGe BiCMOS technology for high energy physics applications  

NASA Astrophysics Data System (ADS)

Final results for a comprehensive radiation hardness evaluation of a high performance, low cost, 130 nm SiGe BiCMOS technology are presented. After a survey of several available SiGe technologies, one was chosen in terms of performance, power consumption, radiation hardness, and cost and it is presented as a suitable technology for the future upgrades of the ATLAS detector of the High Luminosity LHC. Bipolar devices of different sizes and geometries have been evaluated, along with a prototype Front-End readout ASIC designed for binary readout of silicon microstrip detectors. Gamma, neutron and proton irradiations have been performed up to the expected doses and fluences of the experiment.

Díez, S.; Clark, T.; Grillo, A. A.; Kononenko, W.; Martinez-McKinney, F.; Newcomer, F. M.; Norgren, M.; Rescia, S.; Spencer, E.; Spieler, H.; Ullán, M.; Wilder, M.

2013-10-01

158

Radiative corrections for electron-proton elastic scattering taking into account high orders and hard-photon emission  

NASA Astrophysics Data System (ADS)

We investigate the effect of high-order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. Particular attention is devoted to the ? dependence of radiative corrections, which is directly related to the electric-proton form factor. We consider in particular the effects of the interference terms for soft- and hard-photon emission. The contribution from the emission of a hard photon from the scattered electron should be taken into account. The interference of this term with initial electron and proton emission is also important in leading and next to leading approximation. All these contributions may compensate each other in particular kinematical conditions.

Kuraev, E. A.; Bystritskiy, Yu. M.; Ahmadov, A. I.; Tomasi-Gustafsson, E.

2014-06-01

159

Radiation hardness of Czochralski silicon, Float Zone silicon and oxygenated Float Zone silicon studied by low energy protons  

NASA Astrophysics Data System (ADS)

We processed pin-diodes on Czochralski silicon (Cz-Si), standard Float Zone silicon (Fz-Si) and oxygenated Fz-Si. The diodes were irradiated with 10, 20, and 30 MeV protons. Depletion voltages and leakage currents were measured as a function of the irradiation dose. Additionally, the samples were characterized by TCT and DLTS methods. The high-resistivity Cz-Si was found to be more radiation hard than the other studied materials.

Härkönen, J.; Tuovinen, E.; Luukka, P.; Tuominen, E.; Lassila-Perini, K.; Mehtälä, P.; Nummela, S.; Nysten, J.; Zibellini, A.; Li, Z.; Fretwurst, E.; Lindstroem, G.; Stahl, J.; Hönniger, F.; Eremin, V.; Ivanov, A.; Verbitskaya, E.; Heikkilä, P.; Ovchinnikov, V.; Yli-Koski, M.; Laitinen, P.; Pirojenko, A.; Riihimäki, I.; Virtanen, A.

2004-02-01

160

[Modification of dose distributions of ultra-hard X-radiation by scattering from inhomogeneities (author's transl)].  

PubMed

As a result of modified scattering, implants of all sorts like artificial joints, osteosynthesis nails, gold fillings in teeth, etc. the densities and ordinal numbers of which differ from that of soft tissue, cause a modification of the dose in the marginal zone of the tissues situated before the inhomogeneity. If, for example, an ultra-hard X-radiation is applied, dose increases of about 30% can be measured in the region lying in front of a steel plate. PMID:7456092

Sailer, U

1980-12-01

161

Dense plasma focus PACO as a hard X-ray emitter: a study on the radiation source  

NASA Astrophysics Data System (ADS)

The radiation in the X-ray range detected outside the vacuum chamber of the dense plasma focus (DPF) PACO, are produced on the anode zone. The zone of emission is studied in a shot-to-shot analysis, using pure deuterium as filling gas. We present a diagnostic method to determine the place and size of the hard X-ray source by image analysis of high density radiography plates.

Supán, L.; Guichón, S.; Milanese, M.; Niedbalski, J.; Moroso, R.; Acuña, H.; Malamud, F.

2014-05-01

162

Radiation induced loss properties and hardness enhancement technique for ErYb doped fibers for avionic applications  

NASA Astrophysics Data System (ADS)

We present radiation reliability properties and their enhancement of ErYb doped optical fibers in terms of induced loss and lifetime prediction via master curve analysis method. In this study, we are primarily concerned with the effects of ionizing radiation on the performance of double cladded ErYb doped optical fibers in an accelerated low dose ?-radiation environment (i.e. <120 rad/h rate) for high power optical amplifiers to be used in satellite communication systems. We demonstrate a novel method that utilizes pre-radiation exposure and thermal annealing, for enhancing radiation hardness of the fibers with respect to induced optical loss and lifetime prediction. Based on this method, we are able to modify radiation induced loss-rate properties of the fiber with an initial loss penalty, realizing overall loss-budget improvement for relatively long-term deployment (i.e. >5 years). In a direct comparison to non-hardened ErYb doped fibers, we demonstrate approximately 0.16 dB/m of radiation induced loss improvement including an initial loss penalty of 0.14 dB for radiation-hardened fibers over a 10-year duration in a natural low dose (i.e. <0.3 rad/h) radiation environment, i.e. low earth orbit.

Yeniay, A.; Gao, R. F.

2013-03-01

163

Design of high-efficiency, radiation-hard, GaInP/GaAs solar cells  

NASA Technical Reports Server (NTRS)

In recently years, Ga(0.5)In((0.5)P/GaAs cells have drawn increased attention both because of their high efficiencies and because they are well suited for space applications. They can be grown and processed as two-junction devices with roughly twice the voltage and half the current of GaAs cells. They have low temperature coefficients, and have good potential for radiation hardness. We have previously reported the effects of electron irradiation on test cells which were not optimally designed for space. From those results we estimated that an optimally designed cell could achieve 20 percent after irradiation with 10(exp 15) cm(exp -2) 1 MeV electrons. Modeling studies predicted that slightly higher efficiencies may be achievable. Record efficiencies for EOL performance of other types of cells are significantly lower. Even the best Si and InP cells have BOL efficiencies lower than the EOL efficiency we report here. Good GaAs cells have an EOL efficiency of 16 percent. The InP/Ga(0.5)In(0.5)As two-junction, two-terminal device has a BOL efficiency as high as 22.2 percent, but radiation results for these cells were limited. In this study we use the previous modeling and irradiation results to design a set of Ga(0.5)In(0.5)P/GaAs cells that will demonstrate the importance of the design parameters and result in high-efficiency devices. We report record AMO efficiencies: a BOL efficiency of 25.7 percent for a device optimized for BOL performance and two of different designs with EOL efficiencies of 19.6 percent (at 10(exp 15) cm(exp -2) 1MeV electrons). We vary the bottom-cell base doping and the top-cell thickness to show the effects of these two important design parameters. We get an unexpected result indicating that the dopant added to the bottom-cell base also increases the degradation of the top cell.

Kurtz, Sarah R.; Bertness, K. A.; Kibbler, A. E.; Kramer, C.; Olson, J. M.

1994-01-01

164

Radiation hardness of Ga0.5In0.5 P/GaAs tandem solar cells  

NASA Technical Reports Server (NTRS)

The radiation hardness of a two-junction monolithic Ga sub 0.5 In sub 0.5 P/GaAs cell with tunnel junction interconnect was investigated. Related single junction cells were also studied to identify the origins of the radiation losses. The optimal design of the cell is discussed. The air mass efficiency of an optimized tandem cell after irradiation with 10(exp 15) cm (-2) 1 MeV electrons is estimated to be 20 percent using currently available technology.

Kurtz, Sarah R.; Olson, J. M.; Bertness, K. A.; Friedman, D. J.; Kibbler, A.; Cavicchi, B. T.; Krut, D. D.

1991-01-01

165

Space radiation shielding studies for astronaut and electronic component risk assessment  

Microsoft Academic Search

The space radiation environment is comprised of a complex and variable mix of high energy charged particles, gamma rays and other exotic species. Elements of this radiation field may also interact with intervening matter (such as a spaceship wall) and create secondary radiation particles such as neutrons. Some of the components of the space radiation environment are highly penetrating and

Jordan Fuchs; Brad Gersey; Richard Wilkins

2010-01-01

166

Radiation Hard Hybrid Pixel Detectors, and a bb¯ Cross-Section Measurement at the CMS Experiment  

NASA Astrophysics Data System (ADS)

Measurements of heavy flavor quark production at hadron colliders provide a good test of the perturbative quantum chromodynamics (pQCD) theory. It is also essential to have a good understanding of the heavy quark production in the search for new physics. Heavy quarks contribute to backgrounds and signals in measurements of higher mass objects, such as the Higgs boson. A key component to each of these measurements is good vertex resolution. In order to ensure reliable operation of the pixel detector, as well as confidence in the results of analyses utilizing it, it is important to study the effects of the radiation on the detector. In the first part of this dissertation, the design of the CMS silicon pixel detector is described. Emphasis is placed on the effects of the high radiation environment on the detector operation. Measurements of the charge collection efficiency, interpixel capacitance, and other properties of the pixel sensors as a function of the radiation damage are presented. In the second part, a measurement of the inclusive bb¯ production cross section using the b ? muD 0X, D0 ? Kpi decay chain with data from the CMS experiment at the LHC is presented. The data were recorded with the CMS experiment at the Large Hadron Collider (CERN) in 2010 using unprescaled single muon triggers corresponding to a total luminosity of 25 pb-1. The differential cross section is measured for pD0mT > 6 GeV/c and |eta| < 2.4 corresponding to a total cross section of 4.36+/-0.54(stat.) +0.28-0.25 (sys.)+/-0.17( B )+/-0.23( L ) mu b.

Sibille, Jennifer A.

167

Space Radiation Shielding Studies for Astronaut and Electronic Component Risk Assessment.  

National Technical Information Service (NTIS)

The dosimetry component of the Center for Radiation Engineering and Science for Space Exploration (CRESSE) will design, develop and characterize the response of a suite of radiation detectors and supporting instrumentation and electronics with three prima...

J. R. Fuchs

2010-01-01

168

Rad Hard Active Media For Calorimeters  

SciTech Connect

Zero-degree calorimeters have limited space and extreme levels of radiation. A simple, low cost, radiation hard design uses tungsten metal as the absorber and a suitable liquid as the Cerenkov radiator. In other applications a PPAC (Parallel Plate Avalanche Counter) operating with a suitable atmospheric-pressure gas is an attractive active material for a calorimeter. It can be made radiation hard and has sufficient gain in the gas that no electronic components are needed near the detector. It works well even with the highest concentration of shower particles. For this pressure range, R134A (used in auto air conditioners) has many desirable features.

Norbeck, E.; Olson, J. E.; Moeller, A.; Onel, Y. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA (United States)

2006-10-27

169

Rad Hard Active Media For Calorimeters  

NASA Astrophysics Data System (ADS)

Zero-degree calorimeters have limited space and extreme levels of radiation. A simple, low cost, radiation hard design uses tungsten metal as the absorber and a suitable liquid as the ?erenkov radiator. In other applications a PPAC (Parallel Plate Avalanche Counter) operating with a suitable atmospheric-pressure gas is an attractive active material for a calorimeter. It can be made radiation hard and has sufficient gain in the gas that no electronic components are needed near the detector. It works well even with the highest concentration of shower particles. For this pressure range, R134A (used in auto air conditioners) has many desirable features.

Norbeck, E.; Olson, J. E.; Moeller, A.; Onel, Y.

2006-10-01

170

Biochemical changes in blood components after lethal doses of radiation. Final report Oct 80-Sep 81  

SciTech Connect

Nonpeptide, peptide, and protein blood components were measured postirradiation in Wistar rats to investigate biochemical changes that might be related to or form the basis of radiation-induced emesis. The rats were irradiated with lethal doses of radiation, and blood components were analyzed at various times postirradiation. The blood-component levels were compared to those of nonirradiated controls to determine if any significant changes occurred due to the radiation.

Magro, A.M.

1982-10-01

171

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Hard x-ray radiation yield from a dense plasma as a function of the wavelength of the heating ultrashort laser pulse  

NASA Astrophysics Data System (ADS)

The effect of intensity, length, and wavelength of an ultrashort laser pulse on the formation of a hot electron component in a dense laser-produced plasma was first investigated in a single experiment. For a pulse length of 1 ps (or 200 fs, but with an energy contrast ratio of ~20), it was shown that the principal mechanism of generation of hot electrons is the resonance absorption of laser radiation and that the temperature of hot electrons depends on the laser pulse intensity I and the wavelength ? as Th~(I?2)1/3. The homogenisation of the nanostructures of porous silicon due to a poor contrast ratio or a long duration (1 ps) of the laser pulse lowers the yield of hard x-ray radiation compared to the case of high-contrast 200-fs pulses.

Varanavicius, A.; Vlasov, T. V.; Volkov, Roman V.; Gavrilov, S. A.; Gordienko, Vyacheslav M.; Dubetis, A.; Zeromskis, E.; Piskarskas, A.; Savel'ev, Andrei B.; Tamosauskas, G.

2000-06-01

172

A built-in SRAM for radiation hard CMOS pixel sensors dedicated to high energy physics experiments  

NASA Astrophysics Data System (ADS)

CMOS pixel sensors (CPS) are attractive candidates for charged particle tracking in high energy physics experiments. However, CPS chips fabricated with standard CMOS processes, especially the built-in SRAM IP cores, are not radiation hard enough for this application. This paper presents a radiation hard SRAM for improving the CPS radiation tolerance. The SRAM cell is hardened by increasing the static noise margin (SNM) and adding P+ guard rings in layout. The peripheral circuitry is designed by building a radiation-hardened logic library. The SRAM internal timing control is hardened by a self-adaptive timing design. Finally, the SRAM design was implemented and tested in the Austriamicrosystems (AMS) 0.35 ?m standard CMOS process. The prototype chips are adapted to work with frequencies up to 80 MHz, power supply voltages from 2.9 V to 3.3 V and temperatures from 0 °C to 60 °C. The single event latchup (SEL) tolerance is improved from 5.2 MeV cm2/mg to above 56 MeV cm2/mg. The total ionizing dose (TID) tolerance is enhanced by the P+ guard rings and the self-adaptive timing design. The single event upset (SEU) effects are also alleviated due to the high SNM SRAM cell and the P+ guard rings. In the near future, the presented SRAM will be integrated in the CPS chips for the STAR experiments.

Wei, Xiaomin; Gao, Deyuan; Doziere, Guy; Hu, Yann

2013-02-01

173

Atomically Smooth Epitaxial Ferroelectric (Piezoelectric) Thin Films for the Development of a Nonvolatile, Ultrahigh Density, Fast, Low Voltage, Radiation-Hard Memory.  

National Technical Information Service (NTIS)

The goal of this research program is to develop atomically smooth, nanostructured, single crystalline, epitaxial complex oxide thin films as the basic building block for a nonvolatile, ultrahigh density, fast, low voltage, radiation-hard memory. Oxide mat...

C. H. Ahn

2003-01-01

174

On the Barometer Effect on the Hard Component of the Cosmic Radiation  

Microsoft Academic Search

The interpretation of the observed partial correlation between the meson intensity at sea level and the barometric pressure, the other independent variables of the regression equation being the height of the 100 mb level and the stratospheric temperature, is discussed. It is shown that even though the decay effect due to changes in the height of the meson-producing layer is

H. Trefall

1955-01-01

175

RADECS Short Course Section 4 Radiation Hardness Assurance (RHA) for Space Systems  

NASA Technical Reports Server (NTRS)

Contents include the following: Introduction. Programmatic aspects of RHA. RHA componens: requirements and specifications; mission radiation environment; and parts selection and radiation tolerance. Analysis at the function/subsystem/system level: TID/DD; SEE. Conclusion.

Poivey, Christian

2003-01-01

176

Recent results from the CERN RD39 Collaboration on super-radiation hard cryogenic silicon detectors for LHC and LHC upgrade  

NASA Astrophysics Data System (ADS)

The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applications in experiments of the LHC and the future LHC Upgrade. Radiation hardness up to the fluence of 10 16 n eq/cm 2 is required in the future experiments. Significant improvement in the radiation hardness of silicon sensors has taken place during the past years. However, 10 16 n eq/cm 2 is well beyond the radiation tolerance of even the most advanced semiconductor detectors made by commonly adopted technologies. Furthermore, at this radiation load the carrier trapping will limit the charge collection depth to the range of 20-30 ?m regardless of the depletion depth. The key of our approach is freezing the trapping that affects Charge Collection Efficiency (CCE).

Härkönen, J.; Abreu, M.; Anbinderis, P.; Anbinderis, T.; D'Ambrosio, N.; de Boer, W.; Borchi, E.; Borer, K.; Bruzzi, M.; Buontempo, S.; Chen, W.; Cindro, V.; Dezillie, B.; Dierlamm, A.; Eremin, V.; Gaubas, E.; Gorbatenko, V.; Granata, V.; Grigoriev, E.; Grohmann, S.; Hauler, F.; Heijne, E.; Heising, S.; Hempel, O.; Herzog, R.; Ilyashenko, I.; Janos, S.; Jungermann, L.; Kalesinskas, V.; Kapturauskas, J.; Laiho, R.; Li, Z.; Luukka, P.; Mandic, I.; De Masi, R.; Menichelli, D.; Mikuz, M.; Militaru, O.; Niinikoski, T. O.; Nuessle, G.; O'Shea, V.; Pagano, S.; Paul, S.; Perea Solano, B.; Piotrzkowski, K.; Pirollo, S.; Pretzl, K.; Rahman, M.; Rato Mendes, P.; Rouby, X.; Ruggiero, G.; Smith, K.; Sousa, P.; Tuominen, E.; Tuovinen, E.; Vaitkus, J.; Verbitskaya, E.; Da Viá, C.; Vlasenko, L.; Vlasenko, M.; Wobst, E.; Zavrtanik, M.

2004-12-01

177

Radiation hardness of a polycrystalline chemical-vapor-deposited diamond detector irradiated with 14 MeV neutrons  

NASA Astrophysics Data System (ADS)

Chemical-vapor-deposited (CVD) diamond films are considered as neutron detectors for nuclear fusion devices because of their radiation hardness. Data about the radiation hardness of polycrystalline CVD diamond films exposed to 14 MeV neutron are missing in literature so the actual capability of CVD diamond detectors to withstand fusion device conditions must be truly demonstrated. In this work a polycrystalline CVD diamond detector, 101 ?m thick, was irradiated for the first time with 14 MeV neutrons produced by the Fusion Neutron Source of the Japan Atomic Energy Research Institute with the goal to study its radiation hardness. The 14 MeV neutron fluence was 8×1014 n/cm2. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV ? from 241Am source, both in the pumped and the ``as-grown'' state. A comparison with previous measurements performed in more soft neutron spectra (mean neutron energy of 1-2 MeV) is reported pointing out the more damaging effects of the 14 MeV neutrons. It was found that annealing at 500 °C and redeposition of the gold contact followed by a proper pumping procedure will restore more than 70% the initial working conditions of the irradiated detector. An analysis of the neutron field expected in the neutron camera of the International Thermonuclear Reactor fusion tokamak was also performed, showing the capability of CVD diamond detector to withstand the 14 MeV neutron fluence expected in about one year of operation.

Angelone, M.; Pillon, M.; Balducci, A.; Marinelli, M.; Milani, E.; Morgada, M. E.; Pucella, G.; Tucciarone, A.; Verona-Rinati, G.; Ochiai, Kentaro; Nishitani, Takeo

2006-02-01

178

Radiation hardness of a polycrystalline chemical-vapor-deposited diamond detector irradiated with 14 MeV neutrons  

SciTech Connect

Chemical-vapor-deposited (CVD) diamond films are considered as neutron detectors for nuclear fusion devices because of their radiation hardness. Data about the radiation hardness of polycrystalline CVD diamond films exposed to 14 MeV neutron are missing in literature so the actual capability of CVD diamond detectors to withstand fusion device conditions must be truly demonstrated. In this work a polycrystalline CVD diamond detector, 101 {mu}m thick, was irradiated for the first time with 14 MeV neutrons produced by the Fusion Neutron Source of the Japan Atomic Energy Research Institute with the goal to study its radiation hardness. The 14 MeV neutron fluence was 8x10{sup 14} n/cm{sup 2}. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV {alpha} from {sup 241}Am source, both in the pumped and the 'as-grown' state. A comparison with previous measurements performed in more soft neutron spectra (mean neutron energy of 1-2 MeV) is reported pointing out the more damaging effects of the 14 MeV neutrons. It was found that annealing at 500 deg. C and redeposition of the gold contact followed by a proper pumping procedure will restore more than 70% the initial working conditions of the irradiated detector. An analysis of the neutron field expected in the neutron camera of the International Thermonuclear Reactor fusion tokamak was also performed, showing the capability of CVD diamond detector to withstand the 14 MeV neutron fluence expected in about one year of operation.

Angelone, M.; Pillon, M.; Balducci, A.; Marinelli, M.; Milani, E.; Morgada, M.E.; Pucella, G.; Tucciarone, A.; Verona-Rinati, G.; Ochiai, Kentaro; Nishitani, Takeo [Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, via E. Fermi 45, I-00044 Frascati, Roma (Italy); INFM-Dipartimento di Ingegneria Meccanica, Universita di Roma 'Tor Vergata', via del Politecnico 1, I-00133 Rome (Italy); Department of Fusion Engineering Research, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

2006-02-15

179

Radiation hardness studies of CdTe thin films for clinical high-energy photon beam detectors  

NASA Astrophysics Data System (ADS)

In radiation oncology applications, the need for higher-quality images has been driven by recent advances in radiation delivery systems that require online imaging. The existing electronic imaging devices commonly used to acquire portal images implement amorphous silicon (a-Si) detector, which exhibits poor image quality. Efforts for improvement have mostly been in the areas of noise and scatter reduction through software. This has not been successful due to inherent shortcomings of a-Si material. Cadmium telluride (CdTe) semiconductor has long been recognized as highly suitable for use in X-ray detectors in both spectroscopic and imaging applications. Development of such systems has mostly concentrated on single crystal CdTe. Recent advances in thin-film deposition technology suggest replacement of crystalline material with its polycrystalline counterpart, offering ease of large-area device fabrication and achievement of higher resolution as well as a favorable cost difference. While bulk CdTe material was found to have superior radiation hardness, thin films have not been evaluated from that prospective, in particular under high-energy photon beam typical of radiation treatment applications. We assess the performance of thin-film CdTe devices utilizing 6 MeV photon beam and find no consistent trend for material degradation under doses far exceeding the typical radiation therapy detector lifetime dose.

Shvydka, Diana; Parsai, E. I.; Kang, J.

2008-02-01

180

Radiative properties of the background aerosol: absorption component of extinction.  

PubMed

The light-scattering and light-absorption coefficients of the global background aerosol define its single-scatter albedo. Continuous, simultaneous measurements of these optical coefficients were made on a daily basis for the remote marine mid-troposphere; such measurements are essential for assessment of the effects of aerosol on atmospheric radiative transfer. Measurements of light-absorption coefficients made at the Mauna Loa Observatory in Hawaii were higher than expected, and the single-scatter albedo was lower than the value often used in radiative transfer models. Soot appears to be the most likely primary absorber, and hemispheric dispersal of this combustion-derived material is suggested. PMID:17759145

Clarke, A D; Charlson, R J

1985-07-19

181

Narrow-band Jovian kilometric radiation: A new radio component  

Microsoft Academic Search

We describe in new component of Jupiter's radio spectrum. This component emits in a very narrow bandwith (< or =40 kHz) near 100 kHz. Its waveform is a very smooth and gradual rise and subsequent fall in intensity over typically two hours. The emission is polarized with left-hand polarization associated with the Jovian northern magnetic hemisphere and righthand with the

M. L. Kaiser; M. D. Desch

1980-01-01

182

Tunnel generation and locking stimulated Raman radiation components  

Microsoft Academic Search

Stimulated Raman radiation is considered in a ring optical resonator. It is supposed that the resonator is partly filled with a condensed medium at the full length of the medium close to several tunnel lengths. A Raman-active medium and an optical waveguide are assumed to occupy a part of the condensed medium. The feasibility is shown of tunnel generation and

V. Lugovoi

1984-01-01

183

Radiation Hardness Tests of Flexible, Thin-Film Photovoltaics for Space Applications  

NASA Astrophysics Data System (ADS)

An overview of flexible thin-film photovoltaics (TFPV) radiation-testing program undertaken at the AFRL is presented. This effort has been initiated and supported by the AFRL to develop a space radiation qualification program for the state-of-the-art TFPV. Preliminary radiation studies concentrated on two state-of-the-art technologies, namely amorphous silicon (a-Si) and copper-indium-diselenide (CIS) TFPV. Proton and electron irradiation tests were carried out and the response of the a-Si cells has been characterized via illuminated I-V, dark I-V, and QE measurements. The cells demonstrated relatively high radiation resistance up to high Displacement Damage Dose (Dd) levels. The degradation of the FF, observed at high radiation doses was effectively removed by annealing.

Tlomak, Pawel; Reinhardt, Kitt C.; Walters, Robert J.; Messenger, Scott R.

2002-10-01

184

Single-shot analysis of hard x-ray laser radiation using a noninvasive grating spectrometer.  

PubMed

We present a spectrometer setup based on grating dispersion for hard x-ray free-electron lasers. This setup consists of a focusing spectrometer grating and a charge-integrating microstrip detector. Measurement results acquired at Linac Coherent Light Source are presented, demonstrating noninvasive monitoring of single-shot spectra with a resolution of 2.0×10(-4) ±0.3×10(-4) at photon energy of 6 keV with more than 95% transmission of the main beam. PMID:23258009

Karvinen, Petri; Rutishauser, Simon; Mozzanica, Aldo; Greiffenberg, Dominic; Jurani?, Pavle N; Menzel, Andreas; Lutman, Alberto; Krzywinski, Jacek; Fritz, David M; Lemke, Henrik T; Cammarata, Marco; David, Christian

2012-12-15

185

RADIATION HARDNESS / TOLERANCE OF SI SENSORS / DETECTORS FOR NUCLEAR AND HIGH ENERGY PHYSICS EXPERIMENTS.  

SciTech Connect

Silicon sensors, widely used in high energy and nuclear physics experiments, suffer severe radiation damage that leads to degradations in sensor performance. These degradations include significant increases in leakage current, bulk resistivity, and space charge concentration. The increase in space charge concentration is particularly damaging since it can significantly increase the sensor full depletion voltage, causing either breakdown if operated at high biases or charge collection loss if operated at lower biases than full depletion. Several strategies can be used to make Si detectors more radiation had tolerant to particle radiations. In this paper, the main radiation induced degradations in Si detectors will be reviewed. The details and specifics of the new engineering strategies: material/impurity/defect engineering (MIDE); device structure engineering (DSE); and device operational mode engineering (DOME) will be given.

LI,Z.

2002-09-09

186

Radiation hard and gravimetric efficient thin film InP solar cells  

Microsoft Academic Search

We present characterization results of advanced prototypes of InP based thin film solar cells designed to be gravimetrically efficient (high power to weight ratio), and radiation hardened, especially with respect to operations in orbits flie in the \\

Yanning Sun; Jerry M. Woodall; J. L. Freeout; R. J. Walters

2002-01-01

187

A Radiation Hard ASIC for Thermal Instrumentation on the Europa Clipper Mission  

NASA Astrophysics Data System (ADS)

We describe one key hardware development at Goddard that is undergoing maturation for risk mitigation, a radiation hardened by design (RHBD) multi-channel digitizer (MCD) Application Specific Integrated Circuit (ASIC) for thermopile array readout.

Quilligan, G.; DuMonthier, J.; Kleynor, I.; Katz, R.; Lakew, B.; Aslam, S.

2014-02-01

188

Radiation-hard analog-to-digital converters for space and strategic applications  

NASA Technical Reports Server (NTRS)

During the course of the Jet Propulsion Laboratory's program to study radiation-hardened analog-to-digital converters (ADCs), numerous milestones have been reached in manufacturers' awareness and technology development and transfer, as well as in user awareness of these developments. The testing of ADCs has also continued with twenty different ADCs from seven manufacturers, all tested for total radiation dose and three tested for neutron effects. Results from these tests are reported.

Gauthier, M. K.; Dantas, A. R. V.

1985-01-01

189

Hard tooth tissue acoustic response under contact of YAG:Er laser radiation processing  

Microsoft Academic Search

The present paper is the first to results an investigation of parameters of acoustic wave accompanying human tooth enamel and dentine treatment provided with contact YAG:Er submillisecond pulse radiation. It is to define experimentally a dependence of laser-induced acoustic wave integral energy on radiation energy density. And at least, it is to identify Fourier deformations of laser-induced acoustic wave spectrum

Gregory B. Altshuler; Andrey V. Belikov; Andrew V. Erofeev; Alexei V. Scrypnik

1996-01-01

190

Space Radiation Shielding Studies for Astronaut and Electronic Component Risk Assessment  

NASA Technical Reports Server (NTRS)

The dosimetry component of the Center for Radiation Engineering and Science for Space Exploration (CRESSE) will design, develop and characterize the response of a suite of radiation detectors and supporting instrumentation and electronics with three primary goals that will: (1) Use established space radiation detection systems to characterize the primary and secondary radiation fields existing in the experimental test-bed zones during exposures at particle accelerator facilities. (2) Characterize the responses of newly developed space radiation detection systems in the experimental test-bed zones during exposures at particle accelerator facilities, and (3) Provide CRESSE collaborators with detailed dosimetry information in experimental test-bed zones.

Fuchs, Jordan Robert

2010-01-01

191

Micro welding of electronic components with 532nm laser radiation  

Microsoft Academic Search

Laser micro-welding of electronic components using the wavelength lambda= 1064 nm is state-of-the-art technology. However, in these parts some metals that needs to be welded, especially copper and gold, show high reflection and hence low absorption rates of under 4 % for the infrared wavelength range. Further, for increasing temperatures above the melting point of these metals, the absorption rate

F. Otte; U. Stute; A. Ostendorf

2007-01-01

192

FERMI OBSERVATIONS OF GRB 090510: A SHORT-HARD GAMMA-RAY BURST WITH AN ADDITIONAL, HARD POWER-LAW COMPONENT FROM 10 keV TO GeV ENERGIES  

SciTech Connect

We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi observatory. GRB 090510 is the first burst detected by the LAT that shows strong evidence for a deviation from a Band spectral fitting function during the prompt emission phase. The time-integrated spectrum is fit by the sum of a Band function with E{sub peak} = 3.9 {+-} 0.3 MeV, which is the highest yet measured, and a hard power-law component with photon index -1.62 {+-} 0.03 that dominates the emission below {approx}20 keV and above {approx}100 MeV. The onset of the high-energy spectral component appears to be delayed by {approx}0.1 s with respect to the onset of a component well fit with a single Band function. A faint GBM pulse and a LAT photon are detected 0.5 s before the main pulse. During the prompt phase, the LAT detected a photon with energy 30.5{sup +5.8}{sub -2.6} GeV, the highest ever measured from a short GRB. Observation of this photon sets a minimum bulk outflow Lorentz factor, {Gamma}{approx_gt} 1200, using simple {gamma}{gamma} opacity arguments for this GRB at redshift z = 0.903 and a variability timescale on the order of tens of ms for the {approx}100 keV-few MeV flux. Stricter high confidence estimates imply {Gamma} {approx_gt} 1000 and still require that the outflows powering short GRBs are at least as highly relativistic as those of long-duration GRBs. Implications of the temporal behavior and power-law shape of the additional component on synchrotron/synchrotron self-Compton, external-shock synchrotron, and hadronic models are considered.

Ackermann, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Asano, K. [Interactive Research Center of Science, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551 (Japan); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Axelsson, M. [Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden); Baldini, L.; Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bhat, P. N. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Bissaldi, E. [Max-Planck Institut fuer extraterrestrische Physik, 85748 Garching (Germany); Bonamente, E., E-mail: jchiang@slac.stanford.ed, E-mail: sylvain.guiriec@lpta.in2p3.f, E-mail: j.granot@herts.ac.u, E-mail: ohno@astro.isas.jaxa.j [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)

2010-06-20

193

Effects of ionization radiation on BICMOS components for space application  

NASA Astrophysics Data System (ADS)

In this paper experimental results on radiation effects on a BICMOS high-speed standard commercial technology, manufactured by ST-Microelectronics, are reported. Bipolar transistors were irradiated by neutrons, ions, or by both of them. Fast neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs, the so-called Frenkel pairs. Defects introduce trapping energy states which degrade the common emitter current gain . The gain degradation has bee investigated for collector current, Ic, between 1 ?A and1 mA. It was found a linear dependence of ?(1/?) = 1/?- 1/?i(where ?i and ? are the gain after and before tirradiation) as a function of the concentration of Frenkel pairs. The bipolar transistors made on this technology have shown to be particularly radiation resistant. For instance, npn small area transistors have a gain variation (-i)/, lower than 10% for doses of about 0.5 MRad and collector currents of 1 ?A, well suited for low power consumption space application

Rancoita, P. G.; Croitoru, N.; ‘Angelo, P. D.; de Marchi, M.; Favalli, A.; Seidman, A.; Colder, A.; Levalois, M.; Marie, P.; Fallica, G.; Leonardi, S.; Modica, R.

2002-12-01

194

Radiation hardness of PbWO 4 Cherenkov radiators heavily doped with trivalent rare-earth ions  

NASA Astrophysics Data System (ADS)

PbWO 4 single crystals heavily doped with trivalent rare-earth (RE) ions were proposed a few years ago as one of the heaviest Cherenkov radiators. We have found that their radiation damage due to 60Co ?-rays are almost saturated at 10 3 Gy (1 Gy=100 rad). The radiation-induced absorption coefficient ?ir at 420 nm slightly above the short-wavelength cutoff was 3.1, 5.4 and 7.2 m -1 at 10 5 Gy in PbWO 4:Gd 3+(3 at%), PbWO 4:La 3+(5 at%) and PbWO 4:La 3+(8 at%), respectively.

Kobayashi, M.; Sugimoto, S.; Usuki, Y.

2004-05-01

195

Radiation hard polyimide-coated FBG optical sensors for relative humidity monitoring in the CMS experiment at CERN  

NASA Astrophysics Data System (ADS)

This work investigates the performance and the radiation hardness capability of optical thermo-hygrometers based on Fibre Bragg Gratings (FBG) for humidity monitoring in the Compact Muon Solenoid (CMS), one of the four experiments running at CERN in Geneva. A thorough campaign of characterization was performed on 80 specially produced Polyimide-coated RH FBG sensors and 80 commercial temperature FBG sensors. Sensitivity, repeatability and accuracy were studied on the whole batch, putting in evidence the limits of the sensors, but also showing that they can be used in very dry conditions. In order to extract the humidity measurements from the sensor readings, commercial temperature FBG sensors were characterized in the range of interest. Irradiation campaigns with ionizing radiation (?-rays from a Co60 source) at incremental absorbed doses (up to 210 kGy for the T sensors and up to 90 kGy for the RH sensors) were performed on sample of T and RH-Sensors. The results show that the sensitivity of the sensors is unchanged up to the level attained of the absorbed dose, while the natural wavelength peak of each sensor exhibits a radiation-induced shift (signal offset). The saturation properties of this shift are discussed.

Makovec, A.; Berruti, G.; Consales, M.; Giordano, M.; Petagna, P.; Buontempo, S.; Breglio, G.; Szillasi, Z.; Beni, N.; Cusano, A.

2014-03-01

196

Thermal stability of tungsten zone plates for focusing hard x-ray free-electron laser radiation  

NASA Astrophysics Data System (ADS)

Diffractive Fresnel zone plates made of tungsten show great promise for focusing hard x-ray free-electron laser (XFEL) radiation to very small spot sizes. However, they have to withstand the high-intensity pulses of the beam without being damaged. This might be problematic since each XFEL pulse will create a significant temperature increase in the zone plate nanostructures and it is therefore crucial that the optics are thermally stable, even for a large number of pulses. Here we have studied the thermal stability of tungsten zone-plate-like nanostructures on diamond substrates using a pulsed Nd:YAG laser which creates temperature profiles similar to those expected from XFEL pulses. We found that the structures remained intact up to a laser fluence of 100 mJ cm-2, corresponding to a 6 keV x-ray fluence of 590 mJ cm-2, which is above typical fluence levels in an unfocused XFEL beam. We have also performed an initial damage experiment at the LCLS hard XFEL facility at SLAC National Accelerator Laboratory, where a tungsten zone plate on a diamond substrate was exposed to 105 pulses of 6 keV x-rays with a pulse fluence of 350 mJ cm-2 without any damage occurring.

Nilsson, D.; Uhlén, F.; Reinspach, J.; Hertz, H. M.; Holmberg, A.; Sinn, H.; Vogt, U.

2012-04-01

197

Tests of the radiation hardness of silicon strip detectors under neutron, proton, and gamma irradiation  

Microsoft Academic Search

Summary form only given, as follows. As part of a program to develop silicon central tracking systems for the next generation of high-energy, high-luminosity accelerators such as the Superconducting Super Collider and the Relativistic Heavy Ion Collider, the effects of radiation damage in silicon detectors are being studied in detail. Results on neutron and proton irradiations at Los Alamos National

H. J. Ziock; J. G. Boissevain; K. Holzscheiter; J. S. Kapustinsky; W. W. Kinnison; D. M. Lee; W. C. Sailor; W. F. Sommer; W. E. Sondheim; R. S. Wagner; N. Cartiglia; J. DeWitt; D. Dorfan; B. Hubbard; J. Leslie; K. F. O'Shaughnessy; D. Pitzl; W. A. Rowe; H. F.-W. Sadrozinski; A. Seiden; E. Spencer; J. A. Ellison; S. Jerger; D. Joyce; C. Lietzke; S. Wimpenny; P. Ferguson; J. A. J. Matthews; D. Skinner

1991-01-01

198

Circuit-Level Design Approaches for Radiation-Hard Digital Electronics  

Microsoft Academic Search

In this paper, we present a novel circuit design approach for radiation hardened digital electronics. Our approach is based on the use of shadow gates, whose task it is to protect the primary gate in case it is struck by a heavy cosmic ion. We locally duplicate the gate to be protected, and connect a pair of diode-connected transistors (or

Rajesh Garg; Nikhil Jayakumar; Sunil P. Khatri; Gwan S. Choi

2009-01-01

199

Monolithic, Radiation Hard Charge Sensitive Preamplifier Using Diffused N-channel Junction Field Effect Transistors  

Microsoft Academic Search

A monolithic preamplifier entirely based on epitaxial channel, diffused gate N-JFETs has been designed and thoroughly investigated by means of SPICE simulation and breadboard implement at ion. Integration of the circuit is now in progress on the base of the technological processes that expected to retain the characteristics of noise and radiation tolerance that these JFETs feature as discrete devices.

V. Radeka; S. Rescia; P. F. Manfredi; V. Speziali

1990-01-01

200

Monolithic radiation hard charge sensitive preamplifier using junction field effect transistors  

Microsoft Academic Search

A monolithic preamplifier entirely based on epitaxial channel, diffused gate N-JFETs has been designed and thoroughly investigated by means of SPICE simulation and breadboard implementation. Integration of the circuit is now in progress on the base of the technological processes that expected to retain the characteristics of noise and radiation tolerance that these JFETs feature as discrete devices.

S. Rescia; V. Radeka; P. F. Manfredi; V. Speziali

1990-01-01

201

Monolithic, radiation hard charge sensitive preamplifier using diffused N-channel junction field effect transistors  

SciTech Connect

This paper reports on a monlithic preamplifier based on epitaxial channel, diffused gate N-JFETs designed and investigated by means of SPICE simulation and breadboard implementation. Integration of the circuit is now in progress on the base of the technological processes that expected to retain the characteristics of noise and radiation tolerance that these JFETs feature as discrete devices.

Radeka, V.; Rescia, S. (Brookhaven National Lab., Upton, NY (United States)); Manfredi, P.F.; Speziali, V. (Dipt. di Elettronica, Univ. di Pavia, Via Abbiategrasso 209, 27100 Pavia (IT))

1991-04-01

202

A Numerical Study of Material Parameter Sensitivity in the Production of Hard Metal Components Using Powder Compaction  

NASA Astrophysics Data System (ADS)

Modeling of hard metal powder inserts is analyzed based on a continuum mechanics approach. In particular, one commonly used cutting insert geometry is studied. For a given advanced constitutive description of the powder material, the material parameter space required to accurately model the mechanical behavior is determined. These findings are then compared with the corresponding parameter space that can possibly be determined from a combined numerical/experimental analysis of uniaxial die powder compaction utilizing inverse modeling. The analysis is pertinent to a particular WC/Co powder and the finite element method is used in the numerical investigations of the mechanical behavior of the cutting insert.

Andersson, Daniel C.; Lindskog, Per; Staf, Hjalmar; Larsson, Per-Lennart

2014-04-01

203

A Numerical Study of Material Parameter Sensitivity in the Production of Hard Metal Components Using Powder Compaction  

NASA Astrophysics Data System (ADS)

Modeling of hard metal powder inserts is analyzed based on a continuum mechanics approach. In particular, one commonly used cutting insert geometry is studied. For a given advanced constitutive description of the powder material, the material parameter space required to accurately model the mechanical behavior is determined. These findings are then compared with the corresponding parameter space that can possibly be determined from a combined numerical/experimental analysis of uniaxial die powder compaction utilizing inverse modeling. The analysis is pertinent to a particular WC/Co powder and the finite element method is used in the numerical investigations of the mechanical behavior of the cutting insert.

Andersson, Daniel C.; Lindskog, Per; Staf, Hjalmar; Larsson, Per-Lennart

2014-06-01

204

Radiation Hardness Tests of a Scintillation Detector with Wavelength Shifting Fiber Readout  

SciTech Connect

We have performed radiation tolerance tests on the BCF-99-29MC wavelength shifting fibers and the BC404 plastic scintillator from Bicron as well as on silicon rubber optical couplers. We used the 60Co gamma source at the Instituto de Ciencias Nucleares facility to irradiate 30-cm fiber samples with doses from 50 Krad to 1 Mrad. We also irradiated a 10x10 cm2 scintillator detector with the WLS fibers embedded on it with a 200 krad dose and the optical conectors between the scintillator and the PMT with doses from 100 to 300 krad. We measured the radiation damage on the materials by comparing the pre- and post-irradiation optical transparency as a function of time.

Alfaro, R.; Sandoval, A. [Instituto de Fisica - UNAM (Mexico); Cruz, E.; Martinez, M. I.; Paic, G. [Instituto de Ciencias Nucleares - UNAM (Mexico); Montano, L. M. [CINVESTAV (Mexico)

2006-09-25

205

Radiation interlocks: The choice between conventional hard-wired logic and computer-based systems  

SciTech Connect

During the past few years, the use of computers in radiation safety systems has become more widespread. This is not surprising given the ubiquitous nature of computers in the modern technological world. But is a computer a good choice for the central logic element of a personnel safety system. Recent accidents at computer controlled medical accelerators would indicate that extreme care must be exercised if malfunctions are to be avoided. The Department of Energy has recently established a sub-committee to formulate recommendations on the use of computers in safety systems for accelerators. This paper will review the status of the committee's recommendations, and describe radiation protection interlock systems as applied to both accelerators and to irradiation facilities. Comparisons are made between the conventional relay approach and designs using computers. 6 refs., 6 figs.

Crook, K.F.

1986-11-01

206

A Delay-efficient Radiation-hard Digital Design Approach Using CWSP Elements  

Microsoft Academic Search

In this paper, we present a radiation-hardened digital design approach. This approach is based on the use of code word state preserving (CWSP) elements at each flip-flop of the design, and leaving the rest of the design unaltered. The CWSP element provides 100% SET protection for glitch widths up to min{Dmin\\/2, (Dmax - Delta)\\/2}, where Dmin and Dmax are the

Charu Nagpal; Rajesh Garg; Sunil P. Khatri

2008-01-01

207

A delay-efficient radiation-hard digital design approach using CWSP elements  

Microsoft Academic Search

In this paper, we present a radiation-hardened digital design approach. This approach is based on the use of Code Word State Preserving (CWSP) elements at each flip-flop of the design, and leaving the rest of the design unaltered. The CWSP element provides 100% SET protection for glitch widths up to min{Dmin\\/2, (Dmax --- ?)\\/2}, where Dmin and Dmax are the

Charu Nagpal; Rajesh Garg; Sunil P Khatri

2008-01-01

208

JFET monolithic preamplifier with outstanding noise behaviour and radiation hardness characteristics  

SciTech Connect

A second series of monolithic preamplifiers based on epitaxial channel JFETs and intended for calorimetry at hadron colliders has been realized. The employed buried layer process has been upgraded, resulting in a lower pinch-off voltage and a reduced power dissipation. Results will be presented on noise, dynamic behavior and radiation damage. New versions of the preamplifier have been designed for both large capacitance detectors and for low capacitance pre-shower detectors.

Radeka, V.; Rescia, S. [Brookhaven National Lab., Upton, NY (United States); Manfredi, P.F.; Speziali, V.; Svelto, F. [Pavia Univ. (Italy). Dipt. di Elettronica

1992-10-01

209

Radiation hardness studies of n +-in-n planar pixel sensors for the ATLAS upgrades  

Microsoft Academic Search

The ATLAS experiment at the LHC is planning upgrades of its pixel detector to cope with the luminosity increase foreseen in the coming years within the transition from LHC to Super-LHC (SLHC\\/HL-LHC). Associated with the increase in instantaneous luminosity is a rise of the target integrated luminosity from 730 to about 3000fb?1 which directly translates into significantly higher radiation damage.These

S. Altenheiner; C. Goessling; J. Jentzsch; R. Klingenberg; D. Muenstermann; A. Rummler; G. Troska; T. Wittig

2011-01-01

210

Impact of radiation hardness and operating temperatures of silicon carbide electronics on space power system mass  

Microsoft Academic Search

The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kWe,1 MWe, and 10 MWe) for near term technology (i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature Gas

Albert J. Juhasz; Roy C. Tew; Gene E. Schwarze

1999-01-01

211

Impact of radiation hardness and operating temperatures of silicon carbide electronics on space power system mass  

Microsoft Academic Search

The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kWe, 1 MWe, and 10 MWe) for near term technology (i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature

Albert J. Juhasz; Roy C. Tew; Gene E. Schwarze

1999-01-01

212

Performance of Multilayer Monochromators for Hard X-Ray Imaging with Coherent Synchrotron Radiation  

NASA Astrophysics Data System (ADS)

We present a study in which multilayers of different periodicity (from 2.5 to 5.5 nm), composition (W/Si, Mo/Si, Pd/B4C, Ru/B4C), and numbers of layers have been compared. Particularly, we chose mirrors with similar intrinsic quality (roughness and reflectivity) to study their performance (flatness and coherence of the outgoing beam) as monochromators in synchrotron radiography. The results indicate that material composition is the dominating factor for the performance. This is important to consider for future developments in synchrotron-based hard x-ray imaging methods. In these techniques, multilayer monochromators are popular because of their good tradeoff between spectral bandwidth and photon flux density of the outgoing beam, but sufficient homogeneity and preservation of the coherent properties of the reflected beam are major concerns. The experimental results we collected may help scientists and engineers specify multilayer monochromators and can contribute to better exploitation of the advantages of multilayer monochromators in microtomography and other full-field imaging techniques.

Dietsch, R.; Rack, A.; Weitkamp, T.; Riotte, M.; Rack, T.; Holz, T.; Krämer, M.; Weissbach, D.; Morawe, Ch.; Siewert, F.; Medu?a, M.; Cloetens, P.; Ziegler, E.

2011-09-01

213

On the problem of the radiation hardness of SiC nuclear radiation detectors at high working temperatures  

SciTech Connect

Owing to the radiation-induced pronounced conductivity compensation in silicon carbide, carrier localization (trapping) prevails over recombination in capture of nonequilibrium carriers. This makes it possible, by raising the temperature, to reduce the time of carrier retention by a trapping center to values shorter than the duration of signal shaping by electronic circuits. For structural defects created by 6.5-MeV protons, the temperature excluding degradation of the detector signal via carrier localization is estimated. The values of the appearing generation current the noise of which can restrict the operation of a detector in the spectrometric mode are determined.

Ivanov, A. M., E-mail: Alexandr.Ivanov@mail.ioffe.ru; Sadokhin, A. V.; Strokan, N. B.; Lebedev, A. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2011-10-15

214

Radiation-hard Active Pixel Sensors for HL-LHC Detector Upgrades based on HV-CMOS Technology  

NASA Astrophysics Data System (ADS)

Luminosity upgrades are discussed for the LHC (HL-LHC) which would make updates to the detectors necessary, requiring in particular new, even more radiation-hard and granular, sensors for the inner detector region. A proposal for the next generation of inner detectors is based on HV-CMOS: a new family of silicon sensors based on commercial high-voltage CMOS technology, which enables the fabrication of part of the pixel electronics inside the silicon substrate itself. The main advantages of this technology with respect to the standard silicon sensor technology are: low material budget, fast charge collection time, high radiation tolerance, low cost and operation at room temperature. A traditional readout chip is still needed to receive and organize the data from the active sensor and to handle high-level functionality such as trigger management. HV-CMOS has been designed to be compatible with both pixel and strip readout. In this paper an overview of HV2FEI4, a HV-CMOS prototype in 180 nm AMS technology, will be given. Preliminary results after neutron and X-ray irradiation are shown.

Miucci, A.; Gonella, L.; Hemperek, T.; Hügging, F.; Krüger, H.; Obermann, T.; Wermes, N.; Garcia-Sciveres, M.; Backhaus, M.; Capeans, M.; Feigl, S.; Nessi, M.; Pernegger, H.; Ristic, B.; Gonzalez-Sevilla, S.; Ferrere, D.; Iacobucci, G.; La Rosa, A.; Muenstermann, D.; George, M.; Große-Knetter, J.; Quadt, A.; Rieger, J.; Weingarten, J.; Bates, R.; Blue, A.; Buttar, C.; Hynds, D.; Kreidl, C.; Peric, I.; Breugnon, P.; Pangaud, P.; Godiot-Basolo, S.; Fougeron, D.; Bompard, F.; Clemens, J. C.; Liu, J.; Barbero, M.; Rozanov, A.; for HV-CMOS collaboration

2014-05-01

215

Radiation hardness evaluation of the commercial 150 nm CMOS process using 60Co source  

NASA Astrophysics Data System (ADS)

We present a study of radiation effects on MOSFET transistors irradiated with a 60Co source to a total absorbed dose of 1.5 Mrad. The transistor test structures were manufactured using a commercial 150 nm CMOS process and are composed of transistors of different types (NMOS and PMOS), dimensions and insulation from the bulk material by means of deep n-wells. We have observed a degradation of electrical characteristics of both PMOS and NMOS transistors, namely a large increase of the leakage current of the NMOS transistors after irradiation.

Carna, M.; Havranek, M.; Hejtmanek, M.; Janoska, Z.; Marcisovsky, M.; Neue, G.; Tomasek, L.; Vrba, V.

2014-06-01

216

Principle component analysis (PCA) and second-order global hard-modelling for the complete resolution of transition metal ions complex formation with 1,10-phenantroline.  

PubMed

Second-order global hard-modelling was applied to resolve the complex formation between Co(2+), Ni(2+), and Cd(2+) cations and 1,10-phenantroline. The highly correlated spectral and concentration profiles of the species in these systems and low concentration of some species in the individual collected data matrices prevent the well-resolution of the profiles. Therefore, a collection of six equilibrium data matrices including series of absorption spectra taken with pH changes at different reactant ratios were analyzed. Firstly, a precise principle component analysis (PCA) of different augmented arrangements of the individual data matrices was used to distinguish the number of species involved in the equilibria. Based on the results of PCA, the equilibria included in the data were specified and second-order global hard-modelling of the appropriate arrangement of six collected equilibrium data matrices resulted in well-resolved profiles and equilibrium constants. The protonation constant of the ligand (1,10-phenantroline) and spectral profiles of its protonated and unprotonated forms are the additional information obtained by global analysis. For comparison, multivariate curve resolution-alternating least squares (MCR-ALS) was applied to the same data. The results showed that second-order global hard-modelling is more convenient compared with MCR-ALS especially for systems with completely known model. It can completely resolve the system and the concentration profiles which are closer to correct ones. Moreover, parameters showing the goodness of fit are better with second-order global hard-modelling. PMID:19616690

Shariati-Rad, Masoud; Hasani, Masoumeh

2009-08-19

217

Energy and radiation balance components for three grass surfaces near Kursk, Russia  

NASA Technical Reports Server (NTRS)

The energy and radiation balance components were determined over three grass surfaces, located on the Streletskaya steppe during July 1991. The Bowen ratio energy balance method was used to determine the sensible and latent heat flux densities using six computer controlled systems. A total of 126 variables were sampled, including global, diffuse, and reflected solar radiation, long wave radiation (up and down), net radiation, photosynthetically active radiation above and below the vegetation, infrared surface temperatues, soil temperature and heat flow, air temperature and vapor pressure at two levels, wind speed and direction, and precipitation. The ranking of the sites from greatest to smallest for net radiation and latent heat flux density were preserve, mowed in 1990, and mowed in 1991. The ranking of the sites from greatest to smallest for sensible heat flux density were mowed in 1990, mowed in 1991, and preserve.

Fritschen, Leo J.

1992-01-01

218

Product assurance technology for procuring reliable, radiation-hard, custom LSI/VLSI electronics  

NASA Technical Reports Server (NTRS)

Advanced measurement methods using microelectronic test chips are described. These chips are intended to be used in acquiring the data needed to qualify Application Specific Integrated Circuits (ASIC's) for space use. Efforts were focused on developing the technology for obtaining custom IC's from CMOS/bulk silicon foundries. A series of test chips were developed: a parametric test strip, a fault chip, a set of reliability chips, and the CRRES (Combined Release and Radiation Effects Satellite) chip, a test circuit for monitoring space radiation effects. The technical accomplishments of the effort include: (1) development of a fault chip that contains a set of test structures used to evaluate the density of various process-induced defects; (2) development of new test structures and testing techniques for measuring gate-oxide capacitance, gate-overlap capacitance, and propagation delay; (3) development of a set of reliability chips that are used to evaluate failure mechanisms in CMOS/bulk: interconnect and contact electromigration and time-dependent dielectric breakdown; (4) development of MOSFET parameter extraction procedures for evaluating subthreshold characteristics; (5) evaluation of test chips and test strips on the second CRRES wafer run; (6) two dedicated fabrication runs for the CRRES chip flight parts; and (7) publication of two papers: one on the split-cross bridge resistor and another on asymmetrical SRAM (static random access memory) cells for single-event upset analysis.

Buehler, M. G.; Allen, R. A.; Blaes, B. R.; Hicks, K. A.; Jennings, G. A.; Lin, Y.-S.; Pina, C. A.; Sayah, H. R.; Zamani, N.

1989-01-01

219

Depletion layer recombination effects on the radiation damage hardness of gallium arsenide cells  

NASA Technical Reports Server (NTRS)

The significant effect of junction depletion layer recombination on the efficiency of windowed GaAs cells was demonstrated. The effect becomes more pronounced as radiation damage occurs. The depletion is considered for 1 MeV electron fluences up to 10 to the 16th power e/sq m. The cell modeling separates damage in emitter and base or buffer layers using different damage coefficients is reported. The lower coefficient for the emitter predicts less loss of performance at fluences greater than 10 to the 15th power e/sq cm. A method for obtaining information on junction recombination effects as damage proceeds is described; this enables a more complete diagnosis of damage to be made.

Garlick, G. F. J.

1985-01-01

220

Correlated hard x-ray and gamma-ray radiations from the ions accelerated in cloud regions  

NASA Astrophysics Data System (ADS)

Many discussions about probable acceleration mechanisms in the associations OB-stars/ interstellar molecular clouds were stimulated by published COMPTEL observational result on gamma-ray lines with energy 3-7 MeV from Orion region. (Bloemen et.al., 1994; 1997). Later COMPTEL group has disavowed this experimental result. Nevertheless, taking into account the theoretical arguments pro existence of subrelativistic particles in the cloud regions, we can believe that the mission with higher sensitivity like the INTEGRAL can find the gamma-lines produced by locally accelerated particles. The nuclear gamma-lines are effectively produced by ions with energies from a few MeV/n to ˜ 50 MeV/n. In fact the upper limit on the density of accelerated ions in clouds can be settled on the basis of the hard X-ray observation. The X-ray would be produced by accelerated nuclei due to their bremssrahlung interactions with ambient electrons. The maximum bremsstrahlung photon energy is m/M times less then the ion energy, where m and M are the electron and ion mass respectively. For nonrelativistic ions (T Mpc2 ) and X-ray photons (Ex << mec2 ) the cross-section depends only on relative velocity of interacting particle and cross-section of photon production is the same both for electronnucleus interaction and for the ion-electron interaction. The result of calculations of the hard X-ray intensity and energy spectrum from the cloud matter as a function of the ion energy spectrum and elemental abundances are presented. In the talk the upper limits of the gamma-radiation from some clouds will be given on the basis of hard X-ray observation by former and present missions as, for example, ASCA. These upper limits will be useful for the optimization of the observation program of the INTEGRAL mission. References Bloemen H. et. al., 1994 A&A, 281, L5 Bloemen H. et. al., 1997, ApJ, 475, L25

Kotov, Y. D.

2001-08-01

221

A Radiation Hard Multi-Channel Digitizer ASIC for Operation in the Harsh Jovian Environment  

NASA Technical Reports Server (NTRS)

In 1995, the Galileo spacecraft arrived at Jupiter to conduct follow-up experiments on pathfinder Pioneer and key Voyager discoveries especially at Io, Europa, Ganymede and Callisto. These new observations helped expand our scientific knowledge of the prominent Galilean satellites; studies revealed diversity with respect to their geology, internal structure, evolution and degree of past and present activity. Jupiter's diverse Galilean satellites, of which three are believed to harbor internal oceans, are central to understanding the habitability of icy worlds. Galileo provided for the first time compelling evidence of a near-surface global ocean on Europa. Furthermore, by understanding the Jupiter system and unraveling the history of its evolution from initial formation to the emergence of possible habitats and life, gives insight into how giant planets and their satellite systems form and evolve. Most important, new light is shed on the potential for the emergence and existence of life in icy satellite oceans. In 2009, NASA released a detailed Jupiter Europa Mission Study (EJSM) that proposed an ambitious Flagship Mission to understand more fully the satellites Europa and Ganymede within the context of the Jovian system. Key to EJSM is the NASA led Jupiter Europa Orbiter (JEO) and the ESA led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute a choreographed exploration of the Jovian system before settling into orbit around Europa and Ganymede, respectively. The National Academies Planetary Decadal Survey, 2011 has listed the NASA-led JEO as the second highest priority mission for the decade 2013-2022, and if chosen it would be launched in 2020 with arrival at Jupiter in 2025. If the JEO mission is not chosen it is anticipated that there will be opportunities in future decadal cycles. Jupiter Orbit Insertion (JOI) begins a 30-month Jovian system tour followed by nine months of science mapping after Europa Orbit Insertion (EOI) in July 2028. The orbiter will ultimately impact the surface of Europa after the mission is completed. The current JEO mission concept includes a range of instruments on the payload, to monitor dynamic phenomena (such as Io's volcanoes and Jupiters atmosphere), map the Jovian magnetosphere and its interactions with the Galilean satellites, and characterize water oceans beneath the ice shells of Europa and Ganymede. The payload includes a low mass (3.7 Kg) and low power (< 5 W) Thermal Instrument (TI) concept for measuring possible warm thermal anomalies on Europa s cold surface caused by recent (< 10,000 years) eruptive activity. Regions of anomalously high heat flow will be identified by thermal mapping using a nadir pointing, push-broom filter radiometer that provides far-IR imagery in two broad band spectral wavelength regions, 8-20 m and 20-100 m, for surface temperature measurements with better than a 2 K accuracy and a spatial resolution of 250 m/pixel obtained from a 100 Km orbit. The temperature accuracy permits a search for elevated temperatures when combined with albedo information. The spatial resolution is sufficient to resolve Europa's larger cracks and ridge axial valleys. In order to accomplish the thermal mapping, the TI uses sensitive thermopile arrays that are readout by a custom designed low-noise Multi-Channel Digitizer (MCD) ASIC that resides very close to the thermopile linear array outputs. Both the thermopile array and the MCD ASIC will need to show full functionality within the harsh Jovian radiation environment, operating at cryogenic temperatures, typically 150 K to 170 K. In the following, a radiation mitigation strategy together with a low risk Radiation-Hardened-By-Design (RHBD) methodology using commercial foundry processes is given for the design and manufacture of a MCD ASIC that will meet this challenge.

Aslam, Shahid; Aslam, S.; Akturk, A.; Quilligan, G.

2011-01-01

222

Concept of Double Peak electric field distribution in the development of radiation hard silicon detectors  

NASA Astrophysics Data System (ADS)

The concept of Double Peak (DP) electric field distribution is considered for the analysis of operational characteristics of irradiated silicon detectors. The key point of the model is trapping of equilibrium carriers to the midgap energy levels of radiation-induced defects, which leads to a non-uniform distribution of space charge concentration with positively and negatively charged regions adjacent to the p + and n + contacts, respectively. In our new development of the DP model we consider a non-depleted base region in between the space charge regions as a high resistivity bulk, which operates as a drift region with a non-negligible electric field. Electric field characteristics of detectors processed from n-type MCZ Si wafers using various technological procedures, and irradiated by 1 MeV neutrons and 24 GeV/ c protons, have been compared. Electric field profiles have been reconstructed from DP pulse response of heavily irradiated detectors and calculated by the simulation of DP electric field distribution caused by carrier trapping. It is shown that detectors from n-type MCZ Si irradiated by 24 GeV/ c protons do not show typical space charge sign inversion up to the irradiation fluence of about 2.2×10 15 p/cm 2 and the region with a positive charge dominates over a negatively charged region.

Verbitskaya, E.; Eremin, V.; Li, Z.; Härkönen, J.; Bruzzi, M.

2007-12-01

223

Radiation hardness studies in a CCD with high-speed column parallel readout  

NASA Astrophysics Data System (ADS)

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of the International Linear Collider (ILC). The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. The results of detailed simulations of the charge transfer inefficiency (CTI) of a prototype CPCCD including the variation of model parameters are reported. The effects of bulk radiation damage on the CTI of a CPCCD are studied by simulating the effects of two electron trap levels, 0.17 and 0.44 eV, at different concentrations and operating temperatures. The dependence of the CTI on different occupancy levels (percentage of hit pixels) and readout frequencies is also studied. The optimal operating temperature for the CPCCD, where the effects of the charge trapping are at a minimum, is found to be about 230 K for the range of readout speeds proposed for the ILC. The results of the full simulation have been compared with an analytic model.

Sopczak, A.; Aoulmit, S.; Bekhouche, K.; Bowdery, C.; Buttar, C.; Damerell, C.; Davies, G.; Djendaoui, D.; Dehimi, L.; Greenshaw, T.; Koziel, M.; Maneuski, D.; Stefanov, K.; Tikkanen, T.; Woolliscroft, T.; Worm, S.

2008-05-01

224

Radiation Hardness Studies in a CCD with High-Speed Column Parallel Readout  

NASA Astrophysics Data System (ADS)

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of the International Linear Collider (ILC). The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. The results of detailed simulations of the charge transfer inefficiency (CTI) of a prototype CPCCD are reported and studies of the influence of gate voltage on the CTI described. The effects of bulk radiation damage on the CTI of a CPCCD are studied by simulating the effects of two electron trap levels, 0.17 and 0.44 eV, at different concentrations and operating temperatures. The dependence of the CTI on different occupancy levels (percentage of hit pixels) and readout frequencies is also studied. The optimal operating temperature for the CPCCD, where the effects of the charge trapping are at a minimum, is found to be about 230 K for the range of readout speeds proposed for the ILC. The results of the full simulation have been compared with a simple analytic model.

Sopczak, André

2008-06-01

225

The Galileo attitude and articulation control system - A radiation-hard, high precision, state-of-the-art control system  

NASA Technical Reports Server (NTRS)

The Galileo mission and spacecraft, consisting of a Jupiter-orbiter and an atmospheric entry probe, are discussed. Components will include: magnetometers and plasma-wave antennas on a boom, high-gain antenna, probe vehicle, two different bus electronics packages, and a radioisotope thermoelectric generator. Instruments, investigators and objectives are tabulated for both probe science and orbiter science investigations. Requirements in the design of the attitude and articulation control system are very stringent because of the complex dynamics, flexible body effects, the need for autonomy, and the severe radiation environment in the Jupiter nighborhood. Galileo was intended to be ready for launch via Space Shuttle in May of 1986.

Stephenson, R. Rhoads

1985-01-01

226

Radiation hardness of AlxGa1-xN photodetectors exposed to Extreme UltraViolet (EUV) light beam  

NASA Astrophysics Data System (ADS)

We report on the results of fabrication and optoelectrical characterization of Gallium Nitride (GaN) based Extreme UltraViolet (EUV) photodetectors. Our devices were Schottky photodiodes with a finger-shaped rectifying contact, allowing better penetration of light into the active region. GaN layers were epitaxially grown on Silicon (111) by Metal- Organic-Chemical Vapor Deposition (MOCVD). Spectral responsivity measurements in the Near UltraViolet (NUV) wavelength range (200-400 nm) were performed to verify the solar blindness of the photodetectors. After that the devices were exposed to the EUV focused beam of 13.5 nm wavelength using table-top EUV setup. Radiation hardness was tested up to a dose of 3.3·1019 photons/cm2. Stability of the quantum efficiency was compared to the one measured in the same way for a commercially available silicon based photodiode. Superior behavior of GaN devices was observed at the wavelength of 13.5 nm.

Malinowski, Pawel E.; John, Joachim; Barkusky, Frank; Duboz, Jean Yves; Lorenz, Anne; Cheng, Kai; Derluyn, Joff; Germain, Marianne; de Moor, Piet; Minoglou, Kyriaki; Bayer, Armin; Mann, Klaus; Hochedez, Jean-Francois; Giordanengo, Boris; Borghs, Gustaaf; Mertens, Robert

2009-05-01

227

Recent results of CERN RD39 collaboration on development of radiation hard Si detectors operated at low to cryogenic temperatures  

NASA Astrophysics Data System (ADS)

Recent results of CERN RD39 collaboration on the development of radiation hard Si detectors operated at low to cryogenic temperatures will be presented in this paper. It has been found, in comparisons of results of simulation and charge collection data of pad and strip detectors, the charge-injected-diode (CID) operation mode of Si detectors reduces the free carrier trapping, resulting in a much higher charge collection at the SLHC fluence than that in a standard Si detector. The reduction in free carrier trapping by almost a factor of 3 is due to the fact that the CID mode pre-fills the traps, making them neutral and not active in trapping of particle-induced free carriers (signal). It has been found that, electron traps can be pre-filled by injection of electrons from the n+ contact. The CID mode of detector operation can be achieved by a modestly low temperature of ?-40 °C and a operation bias of <600 V. Results of one CID detector application as LHC beam-loss-monitor (BLM) will be presented. Non-irradiated Si detectors has been shown, with tests by laser using our cryogenic transient-current-technique (TCT), to work quite well at LHe temperature (4 K), which are very stable with no polarization and good charge collection efficiency.

Li, Zheng; Chen, W.; Eremin, V.; Ha¨rko¨nen, J.; Luukka, P.; Tuominen, E.; Tuovinen, E.; Verbitskaya, E.

2013-08-01

228

Fast and Accurate Shortwave Radiative Flux Calculations for Climate Models Using Principal Component Analysis  

NASA Astrophysics Data System (ADS)

Radiative transfer (RT) computations are an essential component of climate models, being used for calculating the Earth's energy budget. In particular, RT models are required for the generation of top of the atmosphere radiative fluxes in the longwave and shortwave spectral regions, especially for aerosol-laden scenarios (Randles et al. [2013]). However, full treatment of RT processes is computationally expensive, prompting usage of 2-stream approximations in operational climate models. Natraj et al. [2005, 2010] and Spurr and Natraj [2013] demonstrated the ability of a technique using principal component analysis (PCA) to speed up RT simulations. In the PCA method for RT performance enhancement, empirical orthogonal functions are developed for binned sets of inherent optical properties that possess some redundancy; costly multiple-scattering RT calculations are only done for those (few) optical states corresponding to the most important principal components, and correction factors are applied to approximate radiation fields. Here, we extend the PCA method to a broadband spectral region covering the ultraviolet, visible and near infrared, including gaseous absorbing regions and intermediate continua. Top of the atmosphere radiative fluxes are calculated for several scenarios with varying aerosol type, optical depth, extinction profile and solar zenith angle and comparisons made between our model and 2-stream methods (such as those used in climate models). We show that very accurate radiative forcing estimates can be obtained, accounting for multiple scattering by aerosol, at speeds comparable to 2-stream models.

Kopparla, P.; Natraj, V.; Spurr, R. J.; Shia, R.; Yung, Y. L.

2013-12-01

229

Modeling the variability of solar radiation data among weather stations by means of principal components analysis  

Microsoft Academic Search

Measurements of global terrestrial solar radiation (Rs) are commonly recorded in meteorological stations. Daily variability of Rs has to be taken into account for the design of photovoltaic systems and energy efficient buildings. Principal components analysis (PCA) was applied to Rs data recorded at 30 stations in the Mediterranean coast of Spain. Due to equipment failures and site operation problems,

Manuel Zarzo; Pau Martí

2011-01-01

230

On the Mechanism of Production of the Neutron Component of the Cosmic Radiation  

Microsoft Academic Search

Experiments have been performed on the neutron component of the cosmic radiation, with a system of BF3 proportional counters embedded in paraffin, capable of recording neutrons in the energy range between ~2 and ~15 Mev. The neutron rate recorded with such a detector is due to both neutrons locally produced inside the detector and neutrons produced outside the detector, i.e.,

Vanna Cocconi Tongiorgi

1949-01-01

231

Estimation of neutron and other radiation exposure components in low earth orbit  

NASA Technical Reports Server (NTRS)

The interaction of high-energy space radiation with spacecraft materials generates a host of secondary particles, some, such as neutrons, are more biologically damaging and penetrating than the original primary particles. Before committing astronauts to long term exposure in such high radiation environments, a quantitative understanding of the exposure and estimates of the associated risks are required. Energetic neutrons are traditionally difficult to measure due to their neutral charge. Measurement methods have been limited by mass and weight requirements in space to nuclear emulsion, activation foils, a limited number of Bonner spheres, and TEPCs. Such measurements have had limited success in quantifying the neutron component relative to the charged components. We will show that a combination of computational models and experimental measurements can be used as a quantitative tool to evaluate the radiation environment within the Shuttle, including neutrons. Comparisons with space measurements are made with special emphasis on neutron sensitive and insensitive devices. c2001 Elsevier Science Ltd. All rights reserved.

Singleterry, R. C. Jr; Badavi, F. F.; Shinn, J. L.; Cucinotta, F. A.; Badhwar, G. D.; Clowdsley, M. S.; Heinbockel, J. H.; Wilson, J. W.; Atwell, W.; Beaujean, R.; Kopp, J.; Reitz, G.

2001-01-01

232

Revealing the Origin of Hard X-rays in the Remarkable O4-O4 Binary Star System in M17: GTO component  

NASA Astrophysics Data System (ADS)

The central massive stars in the closest Galactic Giant HII Region M17 are a pair of O4 stars separated by 1.8('') . A Chandra Large Project has revealed that both of these O4 stars are extraordinary X-ray sources, showing hard spectra and rapid variability typical of the luminous blue variable eta Carinae but almost unknown for normal O stars. Using He-like lines resolved by the HETG, we will diagnose whether this remarkable X-ray emission comes from magnetically-channeled wind shocks in single stars or from colliding-wind binaries; if the latter is the case, this pair of early O stars is really a system of four massive stars and constrains models of massive star formation. This is the GTO component of a combined GO/GTO observation (GO PI Marc Gagné).

Garmire, Gordon

2008-09-01

233

Radiation studies of optical and electronic components used in astronomical satellite studies  

NASA Technical Reports Server (NTRS)

The synchronous orbit of the IUE carries the satellite through Earth's outer electron belt. A 40 mCi Sr90 source was used to simulate these electrons. A 5 mCi source of Co60 was used to simulate bremmstrahlung. A 10 MeV electron Linac and a 1.7 MeV electron Van de Graaf wer used to investigate the energy dependence of radiation effects and to perform radiations at a high flux rate. A 100 MeV proton cyclotron was used to simulate cosmic rays. Results are presented for three instrument systems of the IUE and measurements for specific components are reported. The three instrument systems were the ultraviolet converter, the fine error sensor (FES), and the SEC vidicon camera tube. The components were optical glasses, electronic components, silicon photodiodes, and UV window materials.

Becher, J.; Kernell, R. L.

1981-01-01

234

A new radiation stable plastic scintillator  

Microsoft Academic Search

The influence of various components of a plastic scintillator (high concentrations of primary dopant, secondary fluor, diffusion enhancer and stabilizer) on its radiation hardness has been experimentally determined. The diffusion enhancing technique was shown to be the most powerful tool for improving radiation hardness. A new polystyrene scintillator that decreases its light output by only 4% after 2.8 Mrad irradiation

V. G. Senchishin; F. Markley; V. N. Lebedev; V. E. Kovtun; V. S. Koba; A. V. Kuznichenko; V. D. Tizkaja; J. A. Budagov; G. Bellettini; V. P. Seminozhenko; I. I. Zalubovsky; I. E. Chirikov-Zorin

1995-01-01

235

Space radiation shielding studies for astronaut and electronic component risk assessment  

NASA Astrophysics Data System (ADS)

The space radiation environment is comprised of a complex and variable mix of high energy charged particles, gamma rays and other exotic species. Elements of this radiation field may also interact with intervening matter (such as a spaceship wall) and create secondary radiation particles such as neutrons. Some of the components of the space radiation environment are highly penetrating and can cause adverse effects in humans and electronic components aboard spacecraft. Developing and testing materials capable of providing effective shielding against the space radiation environment presents special challenges to researchers. Researchers at the Cen-ter for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View AM University (PVAMU) perform accelerator based experiments testing the effectiveness of various materials for use as space radiation shields. These experiments take place at the NASA Space Radiation Laboratory at Brookhaven National Laboratory, the proton synchrotron at Loma Linda University Medical Center, and the Los Alamos Neutron Science Center at Los Alamos National Laboratory where charged particles and neutrons are produced at energies similar to those found in the space radiation environment. The work presented in this paper constitutes the beginning phase of an undergraduate research project created to contribute to this ongoing space radiation shielding project. Specifically, this student project entails devel-oping and maintaining a database of information concerning the historical data from shielding experiments along with a systematic categorization and storage system for the actual shielding materials. The shielding materials referred to here range in composition from standard materi-als such as high density polyethylene and aluminum to exotic multifunctional materials such as spectra-fiber infused composites. The categorization process for each material includes deter-mination of the density thickness of individual samples and a clear labeling and filing method that allows immediate cross referencing with other material samples during the experimental design process. Density thickness measurements will be performed using a precision scale that will allow for the fabrication of sets of standard density thicknesses of selected materials for ready use in shielding experiments. The historical data from previous shielding experiments consists primarily of measurements of absorbed dose, dose equivalent and dose distributions from a Tissue Equivalent Proportional Counter (TEPC) as measured downstream of various thicknesses of the materials while being irradiated in one of the aforementioned particle beams. This data has been digitally stored and linked to the composition of each material and may be easily accessed for shielding effectiveness inter-comparisons. This work was designed to facili-tate and increase the efficiency of ongoing space radiation shielding research performed at the CRESSE as well as serve as a way to educate new generations of space radiation researchers.

Fuchs, Jordan; Gersey, Brad; Wilkins, Richard

236

Estimation of the biological danger of the very high energy component of space radiation.  

PubMed

In modelling the action of the high energy component of space radiation in a space ship, the secondary radiation resulting from the interaction of 76 GeV protons with a target was used. The radiation flow consisted of neutrons, mesons of different kinds and charges, protons and gamma-quanta of wide energy spectrum. We studied the influence of radiation on the survival of E. coli B and T4Br+ bacteriophage, on the growth, dry weight and survival of Vicia faba, on the frequency of chromosome aberrations, and number of cells with abnormal mitoses, on the rate of post-irradiation recovery according to these characteristics, and also on the yield of the r-mutants of T4Br+ bacteriophage, their distribution and biochemical identification. The probability of strong interactions with intra-nuclear cascade processes was minor. Their action on the background of the main mass of radiation with an RBE of less than 1 could be considerably masked. Nevertheless, the RBE of combined secondary radiation was sufficiently greater than 137Cs radiation; from approximate curves, it was from 1.2 to 4.0 times as great and in single experimental points it was more than 5. The spectrum of mutation was also different. PMID:12523384

Akoev, I G; Yurov, S S; Leontyeva, G A; Livanova, I A; Achmadiyeva, A H; Fomenko, B S; Lebedev, V N; Lukanin, V N

1973-01-01

237

Effects of gamma radiation on a ventricular assist device and its percutaneous lead components.  

PubMed

A patient supported by a left ventricular assist device (LVAD) presented with an abdominal tumor requiring consolidative radiation therapy. To assess the effects of radiation therapy on the operation of the ventricular assist device (VAD) system and assure that the treatment would be safe for the patient with regard to the operation of the VAD system, sample equipment was irradiated and then tested for functionality. Changes in the mechanical properties of components of the percutaneous lead were measured. After testing, it was concluded that radiation therapy would not impede the operation of the pump or produce deleterious alterations of mechanical properties of the various system components. The patient underwent radiation therapy with a total dose of 2,000 cGy without evident complications. There were no observed effects on the LVAD operation nor any indication of alarms or malfunctions. Subsequently, the patient recovered adequate cardiac function for explant of the LVAD and the recovered components were also analyzed confirming the absence of alterations in material properties that would endanger patient safety. PMID:22210647

Chelikani, Neela M; Masterson, Karen; Down, Linden A; Gill, Russel S; Farar, David J; Horstmanshof, Douglas A; Long, James W; Snyder, Trevor A

2012-01-01

238

Principal Component-Based Radiative Transfer Model (PCRTM) for Hyperspectral Sensors. Part I; Theoretical Concept  

NASA Technical Reports Server (NTRS)

Modern infrared satellite sensors such as Atmospheric Infrared Sounder (AIRS), Cosmic Ray Isotope Spectrometer (CrIS), Thermal Emission Spectrometer (TES), Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and Infrared Atmospheric Sounding Interferometer (IASI) are capable of providing high spatial and spectral resolution infrared spectra. To fully exploit the vast amount of spectral information from these instruments, super fast radiative transfer models are needed. This paper presents a novel radiative transfer model based on principal component analysis. Instead of predicting channel radiance or transmittance spectra directly, the Principal Component-based Radiative Transfer Model (PCRTM) predicts the Principal Component (PC) scores of these quantities. This prediction ability leads to significant savings in computational time. The parameterization of the PCRTM model is derived from properties of PC scores and instrument line shape functions. The PCRTM is very accurate and flexible. Due to its high speed and compressed spectral information format, it has great potential for super fast one-dimensional physical retrievals and for Numerical Weather Prediction (NWP) large volume radiance data assimilation applications. The model has been successfully developed for the National Polar-orbiting Operational Environmental Satellite System Airborne Sounder Testbed - Interferometer (NAST-I) and AIRS instruments. The PCRTM model performs monochromatic radiative transfer calculations and is able to include multiple scattering calculations to account for clouds and aerosols.

Liu, Xu; Smith, William L.; Zhou, Daniel K.; Larar, Allen

2005-01-01

239

Radiation effects on optical components of a laser radar sensor designed for remote metrology in ITER  

SciTech Connect

A frequency modulated laser radar is being developed for in-vessel metrology and viewing of plasma-facing surfaces. Some optical components of this sensor must withstand intense gamma radiation (3 {times} 10{sup 6} rad/h) during operation. The authors have tested the effect of radiation on a silica core polarization maintaining optical fiber and on TeO{sub 2} crystals at doses up to {approximately} 10{sup 9} rad. Additional tests are planned for evaluating the performance of a complete acousto-optic (AO) scanning device. The progress made in these tests is also described.

Menon, M.M.; Grann, E.B. [Oak Ridge National Lab., TN (United States); Slotwinski, A. [Coleman Research Corp., Springfield, VA (United States)

1997-09-01

240

Evaluation of 20-min and Annual Radiation Budget Components and Cloudiness in a Mountainous Valley  

NASA Astrophysics Data System (ADS)

Logan, Utah (USA) is among cities located in the mountainous valley in the western portion of Rocky Mountains in North America. It is the county seat of Cache Valley, a metropolitan area with a population of about 100,000. The valley had the polluted air in the USA during January 2004. To evaluate the daily and annual radiation budget and cloudiness in this mountainous valley, we set up a radiation station in the middle of the valley to measure the 20- min radiation budget components namely: incoming (Rso) and outgoing (Rso) solar or shortwave radiation, using to CM21 Kipp and Zonen (one inverted) and incoming (Rli) (or atmospheric) and outgoing (Rlo) or terrestrial) longwave radiation using two CG1 Kipp and Zonen Pyrgeometers (one inverted) during the year of 2003. All pyranometers and Pyrgeometers were ventilated with four CV2 Kipp and Zonen ventilation systems throughout the year to prevent deposition of dew, frost and snow, which otherwise would disturb the measurements. We also measured the 2-m air temperature and relative humidity along with surface temperature. All measurements were taken every 2 s, averaged to 20 min, continuously throughout the year 2000. A Met One heated rain gauge measured precipitation. Comparison of the annual radiation budget components indicates that about 25% of the annual Rsi (5848.6 MJ/ (squared m-y)) was reflected back to sky as Rso. Rli and Rlo amounted to 9968.7 and 13303.5 MJ/ (squared m-y)), respectively. This yielded about 1364.9 MJ/ (squared m- y)) available energy (Rn). Having the 2-m air temperature and moisture data and comparison between the theoretical and the measured longwave radiation, we evaluated the 20-m cloudy conditions throughout the year of 2003. The average cloud base height was 587 m (ranged from zero for foggy conditions to about 3000 m). Annual cloudiness contributed about 139.1 MJ/ (squared m-y)) more energy in this valley.

Malek, E.

2007-05-01

241

Effect of small flares in the neutral component of secondary cosmic radiation  

NASA Technical Reports Server (NTRS)

The results are presented of an investigation of the effect of small flares, scale divisions 1 and 1(+), in the neutron component of secondary cosmic radiation from the data of neutron supermonitors at the stations of Kiev, Bukhta Tiksi, and Deep River. It is shown that flares of scale divisions 1 and 1(+) are accompanied by an effect in the neutron component amounting to about 0.4%. A mechanism is presented for calculating the outflow of particles accelerated in small flares, owing to diffusion across the magnetic field of a trap.

Bondarenko, V. I.; Raychenko, L. V.; Yukhimuk, A. K.

1974-01-01

242

Natural radiation doses for cosmic and terrestrial components in Costa Rica  

Microsoft Academic Search

A study of external natural radiation, cosmic and terrestrial components, was carried out with in situ measurements using NaI scintillation counters while driving along the roads in Costa Rica for the period July 2003–July 2005. The geographical distribution of the terrestrial air-absorbed dose rates and the total effective dose rates (including cosmic) are represented on contour maps. Information on the

Patricia Mora; Esteban Picado; Susumu Minato

2007-01-01

243

Radiation tests of key components of the ALICE TOF TDC Readout Module  

Microsoft Academic Search

The ALICE Time-of-Flight (TOF) system will be a large area (140 m 2 ) detector made by Multigap Resistive Plate Chambers (MRPC). The read-out will be performed by a VME TDC Readout Module (TRM) hosting each 30 High Performance TDC chips (HPTDC). Radiation tests carried out at Zurich PSI with a 60 MeV proton beam line on key components of

A. Alici; P. Antonioli; A. Mati; S. Meneghini; M. Pieracci; M. Rizzi; C. Tintori

244

An evaluation of radiation damage to solid state components flown in low earth orbit satellites.  

PubMed

The effects of total ionising radiation dose upon commercial off-the-shelf semiconductors fitted to satellites operating in low Earth orbit (LEO) conditions was evaluated. The evaluation was performed for the Korea Institute of Technology SATellite-1, (KITSAT-1) which was equipped with commercial solid state components. Two approximate calculation models for space radiation shielding were developed. Verification was performed by comparing the results with detailed three-dimensional calculations using the Monte-Carlo method and measured data from KITSAT-1. It was confirmed that the developed approximate models were reliable for satellite shielding calculations. It was also found that commercial semiconductor devices, which were not radiation hardened, could be damaged within their lifetime due to the total ionising dose they are subject to in the LEO environment. To conclude, an intensive shielding analysis should be considered when commercial devices are used. PMID:15103058

Shin, Myung-Won; Kim, Myung-Hyun

2004-01-01

245

Summary of the effects of radiation upon the passive optical components of the Versatile Link  

NASA Astrophysics Data System (ADS)

The LHC luminosity upgrade, known as the High Luminosity LHC (HL-LHC) will require high-speed optical links to read out data from its detectors. The ATLAS and CMS experiments in collaboration with CERN have developed the Versatile Link in order to address the technical issues of optical data transmission within the harsh radiation environment experienced by any experiment within the HL-LHC. Passive optical components can suffer damage in the form of reduced optical transparency (radiation induced absorption or RIA), reduced bandwidth, and mechanical damage to the components themselves and their connection hardware. This paper summarizes the results of the optical and mechanical tests that have been performed on the Versatile Link's passive optical components. The authors conclude that two single mode and two multimode fibres, as well as standard connector components, can be qualified for use in the HL-LHC environment. The qualifying fibers are: Corning SMF-28e, DrakaElite® SRH-SMF, Corning Clearcurve® OM4 multimode graded index, and DrakaElite® SRH-MMF.

Huffman, B. T.; Weidberg, A.

2014-01-01

246

Hardness Test  

Microsoft Academic Search

\\u000a The hardness of materials is commonly characterized using indentation techniques. The hardness values depend on the tool employed\\u000a and the measured parameter, for wood, the anisotropy, heterogeneity and hygroscopicity also influence the measurements. In\\u000a this chapter, different methods used for hardness testing of wood are presented. Possible correlations between the different\\u000a hardness figures and other mechanical properties are indicated, in

Mariapaola Riggio; Maurizio Piazza

247

Principal component analysis and radiative transfer modelling of Spitzer Infrared Spectrograph spectra of ultraluminous infrared galaxies  

NASA Astrophysics Data System (ADS)

The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. We further investigate the principal components (PCs) of ULIRGs derived in Wang et al. We quantitatively show that five PCs are optimal for describing the Infrared Spectrograph spectra. These five components (PC1-PC5) and the mean spectrum provide a template basis set that reproduces spectra of all z < 0.35 ULIRGs within the noise. For comparison, the spectra are also modelled with a combination of radiative transfer models of both starbursts and the dusty torus surrounding active galactic nuclei (AGN). The five PCs typically provide better fits than the models. We argue that the radiative transfer models require a colder dust component and have difficulty in modelling strong polycyclic aromatic hydrocarbon features. Aided by the models we also interpret the physical processes that the PCs represent. The third PC is shown to indicate the nature of the dominant power source, while PC1 is related to the inclination of the AGN torus. Finally, we use the five PCs to define a new classification scheme using 5D Gaussian mixture modelling and trained on widely used optical classifications. The five PCs, average spectra for the four classifications and the code to classify objects are made available at: .

Hurley, P. D.; Oliver, S.; Farrah, D.; Wang, L.; Efstathiou, A.

2012-08-01

248

Development of an Adaptive Optical System for Sub-10-nm Focusing of Synchrotron Radiation Hard X-rays  

SciTech Connect

In the hard x-ray region, to obtain the theoretical resolution or diffraction-limited focusing size in an imaging optical system, both ultraprecise optics and highly accurate alignment are necessary. An adaptive optical system is used for the compensation of aberrations in various optical systems, such as optical microscopes and space telescopes. In situ wavefront control of hard x-rays is also effective for realizing ideal performance. The aim of this paper is to develop an adaptive optical system for sub-10-nm hard x-ray focusing. The adaptive optical system performs the wavefront measurement using a phase retrieval algorithm and wavefront control using grazing-incidence deformable mirrors. Several results of experiments using the developed system are reported.

Mimura, H.; Kimura, T.; Matsuyama, S. [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); JST CREST, Yamada-oka, Suita, Osaka 565-0871 (Japan); Yokoyama, H. [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Yumoto, H. [SPring-8/JASRI, 1-1-1 Koto Sayo, Hyogo 679-5148 (Japan); Tamasaku, K.; Koumura, Y.; Yabashi, M. [SPring-8/RIKEN, 1-1-1 Koto Sayo, Hyogo 679-5148 (Japan); Ishikawa, T. [SPring-8/JASRI, 1-1-1 Koto Sayo, Hyogo 679-5148 (Japan); SPring-8/RIKEN, 1-1-1 Koto Sayo, Hyogo 679-5148 (Japan); Yamauchi, K. [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); JST CREST, Yamada-oka, Suita, Osaka 565-0871 (Japan); Center for Ultraprecision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2011-09-09

249

RADIATION MAGNETOHYDRODYNAMICS SIMULATION OF PROTO-STELLAR COLLAPSE: TWO-COMPONENT MOLECULAR OUTFLOW  

SciTech Connect

We perform a three-dimensional nested-grid radiation magnetohydrodynamics (RMHD) simulation with self-gravity to study the early phase of the low-mass star formation process from a rotating molecular cloud core to a first adiabatic core just before the second collapse begins. Radiation transfer is implemented with the flux-limited diffusion approximation, operator-splitting, and implicit time integrator. In the RMHD simulation, the outer region of the first core attains a higher entropy and its size is larger than that in the magnetohydrodynamics simulations with the barotropic approximation. Bipolar molecular outflow consisting of two components is driven by magnetic Lorentz force via different mechanisms, and shock heating by the outflow is observed. Using the RMHD simulation we can predict and interpret the observed properties of star-forming clouds, first cores, and outflows with millimeter/submillimeter radio interferometers, especially the Atacama Large Millimeter/submillimeter Array.

Tomida, Kengo; Tomisaka, Kohji; Ohsuga, Ken [Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), Osawa, Mitaka, Tokyo 181-8588 (Japan); Matsumoto, Tomoaki [Faculty of Humanity and Environment, Hosei University, Fujimi, Chiyodaku, Tokyo 102-8160 (Japan); Machida, Masahiro N.; Saigo, Kazuya [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)], E-mail: tomida@th.nao.ac.jp, E-mail: tomisaka@th.nao.ac.jp, E-mail: ken.ohsuga@nao.ac.jp, E-mail: masahiro.machida@nao.ac.jp, E-mail: saigo@th.nao.ac.jp, E-mail: matsu@hosei.ac.jp

2010-05-01

250

The characterization of dressing component materials and radiation formation of PVA PVP hydrogel  

NASA Astrophysics Data System (ADS)

The characterization of dressing component materials and radiation induced formation of PVA-PVP hydrogel have been carried out. It was found that the purity of PVA and PVP powders were 99.5% and 77.82% based on DSC measurement. The PVA-PVP hydrogels have the water content in the range of 60-80% and water absorption in the range of 40-250%. It was also found that the PVA-PVP hydrogel prepared by irradiation at 20 kGy shows a good barrier for microbes. This characterization are very important for PVA-PVP hydrogel to be used as wound dressing.

Razzak, M. T.; Zainuddin; Erizal; Dewi, S. P.; Lely, H.; Taty, E.; Sukirno

1999-06-01

251

Influence of Natural Convection and Thermal Radiation Multi-Component Transport in MOCVD Reactors  

NASA Technical Reports Server (NTRS)

The influence of Grashof and Reynolds number in Metal Organic Chemical Vapor (MOCVD) reactors is being investigated under a combined empirical/numerical study. As part of that research, the deposition of Indium Phosphide in an MOCVD reactor is modeled using the computational code CFD-ACE. The model includes the effects of convection, conduction, and radiation as well as multi-component diffusion and multi-step surface/gas phase chemistry. The results of the prediction are compared with experimental data for a commercial reactor and analyzed with respect to the model accuracy.

Lowry, S.; Krishnan, A.; Clark, I.

1999-01-01

252

A pixel unit-cell targeting 16 ns resolution and radiation hardness in a column read-out particle vertex detector  

SciTech Connect

A pixel unit cell (PUC) circuit architecture, optimized for a column read out architecture, is reported. Each PUC contains an integrator, active filter, comparator, and optional analog store. The time-over-threshold (TOT) discriminator allows an all-digital interface to the array periphery readout while passing an analog measure of collected charge. Use of (existing) radiation hard processes, to build a detector bump-bonded to a pixel readout array, is targeted. Here, emphasis is on a qualitative explanation of how the unique circuit implementation benefits operation for Super Collider (SSC) detector application.

Wright, M.; Millaud, J.; Nygren, D.

1992-10-01

253

A pixel unit-cell targeting 16ns resolution and radiation hardness in a column read-out particle vertex detector  

NASA Astrophysics Data System (ADS)

A pixel unit cell (PUC) circuit architecture, optimized for a column read out architecture, is reported. Each PUC contains an integrator, active filter, comparator, and optional analog store. The time-over-threshold (TOT) discriminator allows an all-digital interface to the array periphery readout while passing an analog measure of collected charge. Use of (existing) radiation hard processes, to build a detector bump-bonded to a pixel readout array, is targeted. Here emphasis is on a qualitative explanation of how the unique circuit implementation benefits operation for Super Collider (SSC) detector application.

Wright, Michael; Millaud, Jacques; Nygren, David

1993-05-01

254

Radiation and temperature effects on electronic components investigated under the CSTI High Capacity Power Project  

SciTech Connect

The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the CSTI high capacity power project will be presented in this paper: (1) Neutron, gamma ray, and temperature effects on power semiconductor switches, (2) Temperature and frequency effects on soft magnetic materials; and (3) Temperature effects on rare earth permanent magnets.

Shwarze, G.E. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Niedra, J.M. [Sverdrup Technology, Inc., Brook Park, OH (United States) Lewis Research Center Group; Frasca, A.J. [Wittenberg Univ., Springfield, OH (United States); Wieserman, W.R. [Univ. of Pittsburgh, Johnstown, PA (United States)

1994-09-01

255

A proposed hardness assurance test methodology for bipolar linear circuits and devices in a space ionizing radiation environment  

SciTech Connect

A hardness assurance test approach has been developed for bipolar linear circuits and devices in space. It consists of a screen for dose rate sensitivity and a characterization test method to develop the conditions for a lot acceptance test at high dose rate.

Pease, R.L. [RLP Research, Albuquerque, NM (United States); Brown, D.B. [Naval Research Lab., Washington, DC (United States); Cohn, L. [Defense Special Weapons Agency, Alexandria, VA (United States)] [and others

1997-04-01

256

The hard metal diseases  

SciTech Connect

Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.66 references.

Cugell, D.W. (Department of Medicine, Northwestern University Medical School, Chicago, IL (United States))

1992-06-01

257

A New Approach to the Equation of State of Silicate Melts: An Application of a Hard-Sphere Model to a Multi-Component System  

NASA Astrophysics Data System (ADS)

Compressional properties of silicate liquids including density and bulk modulus at elevated pressures and temperatures (i.e., equation of state) are crucial to our understanding of melting processes such as the generation and differentiation of silicate melts in Earth and hence to explore the geophysical and geochemical consequences of melting. Unlike the solid and gaseous states of a matter for which there are widely accepted idealized models like crystal lattice and ideal gas, describing the properties of liquids are challenging because they are as dense as solids yet there is no long-range order in atomic positions. In the past, equations of state of silicate melts were treated in analogy with that of solids for which the change in internal energy due to the change in inter-atomic distance plays an important role. However, a comparison of compressional properties reveals fundamental differences between silicate liquids and solids: (1) Liquids have much smaller bulk moduli than solids; (2) Liquids do not follow Birch’s law (the relationship between bulk modulus and density) as opposed to solids; (3) The Grüneisen parameter increases with increasing pressure for (non-metallic) liquids but decreases for solids. (4) The radial distribution functions of liquids show that the inter-atomic distances in liquids do not change upon compression as much as solids do. In this work, we show that these differences are due to the different compressional mechanisms of liquids and solids. That is, liquids have the ability of changing structures, and hence the compression of liquids is largely controlled by the entropic contribution of the free energy in addition to the internal energy contribution (reduction in the inter-atomic distances) that is available to solids. In order to account for the role of entropic contribution, we propose a new equation of state for multi-component silicate liquids based on the theory of hard-sphere mixtures. In this model, the cation-anion polyhedra for oxide components in liquids such as the SiO2 tetrahedra and MgO octahedra are considered as impenetrable rigid spheres. The geometrical arrangements of these spheres give the entropic contribution to compression, while the attraction between the spheres give the internal energy contribution to compression. We calibrate the equation of state using the experimental measurements on room-pressure density and bulk modulus of liquids. This equation of state provides a unified explanation for the experimental observations cited above including the bulk moduli of liquids as well as the pressure dependence of Grüneisen parameter. We will also discuss the effect of composition on melt density and other compressional properties based on this equation of state.

Jing, Z.; Karato, S.

2009-12-01

258

RHOBOT: Radiation hardened robotics  

SciTech Connect

A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

259

Hard x-ray scanning microscopy with coherent radiation: Beyond the resolution of conventional x-ray microscopes  

SciTech Connect

We demonstrate x-ray scanning coherent diffraction microscopy (ptychography) with 10 nm spatial resolution, clearly exceeding the resolution limits of conventional hard x-ray microscopy. The spatial resolution in a ptychogram is shown to depend on the shape (structure factor) of a feature and can vary for different features in the object. In addition, the resolution and contrast are shown to increase with increasing coherent fluence. For an optimal ptychographic x-ray microscope, this implies a source with highest possible brilliance and an x-ray optic with a large numerical aperture to generate the optimal probe beam.

Schropp, A.; Hoppe, R.; Patommel, J.; Samberg, D.; Seiboth, F.; Stephan, S.; Schroer, C. G. [Institute of Structural Physics, Technische Universitaet Dresden, D-01062 Dresden (Germany); Wellenreuther, G.; Falkenberg, G. [Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg (Germany)

2012-06-18

260

Narrowband shear wave generation by a Finite-Amplitude radiation force: The fundamental component.  

PubMed

A highly localized source of low-frequency shear waves can be created by the modulated radiation force resulting from two intersecting quasi-continuous-wave ultrasound beams of slightly different frequencies. In contrast to most other radiation force-based methods, these shear waves can be narrowband. Consequently, different frequency-dependent effects will not significantly affect their spectrum as they propagate within a viscoelastic medium, thereby enabling the viscoelastic shear properties of the medium to be determined at any given modulation frequency. This can be achieved by tracking the shear wave phase delay and change in amplitude over a specific distance. In this paper we explore the properties of short duration (dynamic) low-frequency shear wave propagation and study how the shear displacement field depends on the excitation conditions. Our investigations make use of the approximate Green's functions for viscoelastic media, and the evolution of such waves is studied in the spatiotemporal domain from a theoretical perspective. Although nonlinearities are included in our confocal source model, just the properties of the fundamental shear component are examined in this paper. We examine how the shear wave propagation is affected by the shear viscosity, the coupling wave, the spatial distribution of the force, the shear speed, and the duration of the modulated wave. A method is proposed for estimating the shear viscosity of a viscoelastic medium. In addition, it is shown how the Voigt model paremeters can be extracted from the frequency-dependent speed and attenuation. PMID:18334341

Giannoula, Alexia; Cobbold, Richard S C

2008-02-01

261

Analysis of Spectroscopic Radiation Portal Monitor Data Using Principal Components Analysis  

SciTech Connect

Many international border crossings screen cargo for illicit nuclear material using radiation portal monitors (RPMs) that measure the gamma-ray flux emitted by vehicles. Screening often consists of primary, which acts as a trip-wire for suspect vehicles, and secondary, which locates the radiation source and performs isotopic identification. The authors present a method of anomaly detection for primary screening that uses past observations of gamma-ray signatures to define an expected benign vehicle population. Newly acquired spectra are then compared to this expected population using statistical criteria that reflect acceptable alarm rates and probabilities of detection. Shown here is an analysis of spectroscopic RPM data collected at an international border crossing using this technique. The raw data were analyzed to develop an expected benign vehicle population by decimating the original pulse-height channels, extracting composite variables with principal components analysis, and estimating variance-weighted distances from the ''mean vehicle spectra'' with the Mahalanobis distance metric. The following analysis considers data acquired with both NaI(Tl)-based and plastic scintillator-based RPMs. For each system, performance estimates for anomaly sources are compared to common nuisance sources. The algorithm reported here shows promising results in that it is more sensitive to the anomaly sources than common nuisance sources for both RPM types.

Runkle, Robert C.; Tardiff, Mark F.; Anderson, K K.; Carlson, Deborah K.; Smith, L E.

2006-06-01

262

Flavoring components of raw monsooned arabica coffee and their changes during radiation processing.  

PubMed

Volatile aroma principles, nonvolatile taste constituents (caffeine and chlorogenic and caffeic acids), and glycosidically bound aroma compounds of monsooned and nonmonsooned raw arabica coffee were analyzed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Among the most potent odor active constituents known to contribute to the aroma of the green beans, 3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, 4-vinylguaiacol, beta-damascenone, (E)-2-nonenal, trans,trans-2,4-decadienal, phenylacetaldehyde, and 3-methylbutyric acid were detected by GC-MS in both samples. A decrease in content of methoxypyrazines and an increase in 4-vinylguaiacol and isoeugenol resulted in a dominant spicy note of monsooned coffee. These phenolic compounds exist partly as their glycosides, and their release from the bound precursors during monsooning accounted for their higher content in monsooned coffee. A considerable decrease in astringent chlorogenic acid as a consequence of hydrolysis to bitter caffeic acid was noted in monsooned coffee. Radiation processing of nonmonsooned beans at a dose of 5 kGy resulted in an increased rate of monsooning. At this dose a quantitative increase in most of the aroma active components could be observed in all samples studied. Hydrolysis of chlorogenic acid to caffeic acid was noted in radiation-processed monsooned coffee beans irrespective of whether the treatment was carried out before or after monsooning. These changes were, however, not observed in irradiated, nonmonsooned coffee beans, suggesting an enzymatic rather than a radiolytic cleavage of chlorogenic acid. A rationale behind the mechanism of monsooning and radiation-induced enhancement of the monsooning process is discussed. PMID:14690378

Variyar, Prasad S; Ahmad, Rasheed; Bhat, Rajeev; Niyas, Zareena; Sharma, Arun

2003-12-31

263

Evidence for a change in the X-ray radiation mechanism in the hard state of Galactic black holes  

NASA Astrophysics Data System (ADS)

We present results on the spectral variability of two Galactic black hole X-ray binaries, GRO J1655-40 and GX 339-4, in the hard state. We confirm a transition in behaviour of the photon index with luminosity, such that the well-known decrease in X-ray photon index with decreasing luminosity only continues down to Lbol˜ 0.01LE. Below this point, the photon index increases again. For Comptonization models, this implies that the ratio of the Compton luminosity to seed photon luminosity, ?h/?s, changes with bolometric luminosity, consistent with a scenario where seed photons change from cyclo-synchrotron at the lowest luminosities to those from a truncated disc. Alternatively, the transition could mark the point below which the non-thermal jet starts to dominate, or where reprocessed photons replace the viscous photons in an outflowing corona model.

Sobolewska, M. A.; Papadakis, I. E.; Done, C.; Malzac, J.

2011-10-01

264

Radiation-hard erbium optical fiber and fiber amplifier for both low- and high-dose space missions.  

PubMed

We present a new structure for erbium-doped optical fibers [hole-assisted carbon-coated, (HACC)] that, combined with an appropriate choice of codopants in the core, strongly enhances their radiation tolerance. We built an erbium-doped fiber amplifier based on this HACC fiber and characterize its degradation under ?-ray doses up to 315 krad (SiO2) in the ON mode. The 31 dB amplifier is practically radiation insensitive, with a gain change of merely -2.2×10(-3) dB/krad. These performances authorize the use of HACC doped fibers and amplifiers for various applications in environments associated with today's missions (of doses up to 50 krad) and even for future space missions associated with higher dose constraints. PMID:24784040

Girard, S; Laurent, A; Pinsard, E; Robin, T; Cadier, B; Boutillier, M; Marcandella, C; Boukenter, A; Ouerdane, Y

2014-05-01

265

Radiation hardness perspectives for the design of analog detector readout circuits in the 0.18-?m CMOS generation  

Microsoft Academic Search

This paper presents a study of the ionizing radiation tolerance of analog parameters of 0.18-?m CMOS transistors, in view of the application to the design of front-end integrated circuits for detectors in high-energy physics experiments. Static, signal, and noise performances of devices with various gate dimensions were monitored before and after irradiation up to a 300-kGy(Si) total dose of 60Co

Massimo Manghisoni; Lodovico Ratti; Valerio Re; Valeria Speziali

2002-01-01

266

Effects of simulated space radiation on immunoassay components for life-detection experiments in planetary exploration missions.  

PubMed

The Life Marker Chip (LMC) instrument is part of the proposed payload on the ESA ExoMars rover that is scheduled for launch in 2018. The LMC will use antibody-based assays to detect molecular signatures of life in samples obtained from the shallow subsurface of Mars. For the LMC antibodies, the ability to resist inactivation due to space particle radiation (both in transit and on the surface of Mars) will therefore be a prerequisite. The proton and neutron components of the mission radiation environment are those that are expected to have the dominant effect on the operation of the LMC. Modeling of the radiation environment for a mission to Mars led to the calculation of nominal mission fluences for proton and neutron radiation. Various combinations and multiples of these values were used to demonstrate the effects of radiation on antibody activity, primarily at the radiation levels envisaged for the ExoMars mission as well as at much higher levels. Five antibodies were freeze-dried in a variety of protective molecular matrices and were exposed to various radiation conditions generated at a cyclotron facility. After exposure, the antibodies' ability to bind to their respective antigens was assessed and found to be unaffected by ExoMars mission level radiation doses. These experiments indicated that the expected radiation environment of a Mars mission does not pose a significant risk to antibodies packaged in the form anticipated for the LMC instrument. PMID:22897155

Derveni, Mariliza; Hands, Alex; Allen, Marjorie; Sims, Mark R; Cullen, David C

2012-08-01

267

Comparing diffuse radiation models with one predictor for partitioning incident PAR radiation into its diffuse component in the eastern Mediterranean basin  

Microsoft Academic Search

In the photosynthesis process, solar radiation energy is converted to chemical energy by using atmospheric CO2. That is, almost all living species depend on energy produced through photosynthesis for their nourishing components thus making photosynthesis vital to the earth's life. Nevertheless, the knowledge of photosynthetic photon flux density QP (PAR, 400–700 nm) is important in several applications dealing with plants physiology,

C. P. Jacovides; J. Boland; D. N. Asimakopoulos; N. A. Kaltsounides

2010-01-01

268

Solar Load Inputs for USARIEM Thermal Strain Models and the Solar Radiation-Sensitive Components of the WBGT Index  

NASA Astrophysics Data System (ADS)

This report describes processes we have implemented to use global pyranometer-based estimates of mean radiant temperature as the common solar load input for the Scenario model, the USARIEM heat strain model, and for the computation of the solar radiation sensitive components of the Wet Bulb Globe Temperature (WBGT) index.

Matthew, William T.; Santee, William R.; Berglund, Larry G.

2001-06-01

269

Remote detection of radioactive contamination in the atmosphere based on secondary optical and microwave radiation of atmospheric components  

Microsoft Academic Search

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol

Liliya K. Chistyakova; Sergei T. Penin

1999-01-01

270

The radiative-adiabatic model of 2-component (2 + 2) greenhouse effect is applicable for wide range of planetary environment  

Microsoft Academic Search

In earlier works (1) it is shown that the radiative-adiabatic model make it possible the analytical solution for the 2-component (2 + 2) greenhouse effect in the case of the optical dense atmosphere (Earth, Venus). Now we have obtained the analytical estimation of greenhouse effect not only for the planets with the high optical density of atmosphere but also for

A. V. Karnaukhov

2004-01-01

271

Hard metal composition  

SciTech Connect

This patent describes a hard composition of matter having a Rockwell A hardness value of at least approximately 85, comprising the compressed and densified reaction product of: a minor amount of a boron carbide component selected from the group consisting of (a) boron carbide and (b) boron and carbon, the boron and carbon being present in amounts sufficient to form boron carbide in situ, wherein the boron carbide component consists essentially of B/sub 4/C; a major amount of a metal mixture consisting essentially of: (a) a first metal component selected from the group consisting of tungsten and molybdenum and mixtures thereof, and (b) a second metal component selected from the group consisting of nickel and iron and mixtures thereof; wherein the minor amount of the boron carbide component is between 3% and 6% by weight of the composition of matter when the first metal component is tungsten. The minor amount of the boron carbide component is between 6% and 10% by weight of the composition when the first metal component is molybdenum. The boron carbide component is between 3% and 10% when the first metal component is a mixture of tungsten and molybdenum, with the remainder of the composition being formed of the metal mixture, and wherein the first metal component is from 70% to less than about 90% by weight of the metal mixture when the first metal component is tungsten, and wherein the first metal component is from 72% to less than about 90% by weight of the metal mixture when the first metal component is molybdenum.

Sheinberg, H.

1986-12-02

272

Critical Characteristics of Radiation Detection System Components to be Dedicated for use in Safety Class and Safety Significant System  

SciTech Connect

This document identifies critical characteristics of components to be dedicated for use in Safety Significant (SS) Systems, Structures, or Components (SSCs). This document identifies the requirements for the components of the common, radiation area, monitor alarm in the WESF pool cell. These are procured as Commercial Grade Items (CGI), with the qualification testing and formal dedication to be performed at the Waste Encapsulation Storage Facility (WESF) for use in safety significant systems. System modifications are to be performed in accordance with the approved design. Components for this change are commercially available and interchangeable with the existing alarm configuration This document focuses on the operational requirements for alarm, declaration of the safety classification, identification of critical characteristics, and interpretation of requirements for procurement. Critical characteristics are identified herein and must be verified, followed by formal dedication, prior to the components being used in safety related applications.

DAVIS, S.J.

2000-12-28

273

Critical Characteristics of Radiation Detection System Components to be Dedicated for use in Safety Class and Safety Significant System  

SciTech Connect

This document identifies critical characteristics of components to be dedicated for use in Safety Class (SC) or Safety Significant (SS) Systems, Structures, or Components (SSCs). This document identifies the requirements for the components of the common radiation area monitor alarm in the WESF pool cell. These are procured as Commercial Grade Items (CGI), with the qualification testing and formal dedication to be performed at the Waste Encapsulation Storage Facility (WESF), in safety class, safety significant systems. System modifications are to be performed in accordance with the instructions provided on ECN 658230. Components for this change are commercially available and interchangeable with the existing alarm configuration This document focuses on the operational requirements for alarm, declaration of the safety classification, identification of critical characteristics, and interpretation of requirements for procurement. Critical characteristics are identified herein and must be verified, followed by formal dedication, prior to the components being used in safety related applications.

DAVIS, S.J.

2000-05-25

274

Angular dependence of the radiative gluon spectrum and the energy loss of hard jets in QCD media  

SciTech Connect

The induced momentum spectrum of soft gluons radiated from a high energy quark propagating through a QCD medium is derived in the Baier-Dokshitzer-Mueller-Peigne-Schiff formalism. A calorimetric measurement for the medium-dependent energy lost by a jet with opening angle {theta}{sub cone} is proposed. The fraction of this energy loss with respect to the integrated one appears to be the relevant observable. It exhibits a universal behavior in terms of the variable {theta}{sub cone}{sup 2}L{sup 3}q where L is the size of the medium and q the transport coefficient. Phenomenological implications for the differences between cold and hot QCD matter are discussed. (c) 1999 The American Physical Society.

Baier, R. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33501 Bielefeld, (Germany)] [Fakultaet fuer Physik, Universitaet Bielefeld, D-33501 Bielefeld, (Germany); Dokshitzer, Yu. L. [INFN, Sezione di Milano, 20133 Milan, (Italy)] [INFN, Sezione di Milano, 20133 Milan, (Italy); Mueller, A. H. [Physics Department, Columbia University, New York, New York 10027 (United States)] [Physics Department, Columbia University, New York, New York 10027 (United States); Schiff, D. [LPT, Universite Paris-Sud, Batiment 210, F-91405 Orsay, (France)] [LPT, Universite Paris-Sud, Batiment 210, F-91405 Orsay, (France)

1999-12-01

275

Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics  

NASA Astrophysics Data System (ADS)

ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí i García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

1998-02-01

276

Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics  

NASA Astrophysics Data System (ADS)

ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí I García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

1997-02-01

277

Total-dose radiation effects data for semiconductor devices, volume 1. [radiation resistance of components for the Galileo Project  

NASA Technical Reports Server (NTRS)

Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. Data are presented by JPL for various NASA space programs on diodes, bipolar transistors, field effect transistors, silicon-controlled rectifiers, and optical devices. A vendor identification code list is included along with semiconductor device electrical parameter symbols and abbreviations.

Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

1981-01-01

278

Investigation on the long-term radiation hardness of low resistivity starting silicon materials for RT silicon detectors in high energy physics  

SciTech Connect

Relatively low resistivity (200 to 1000 {Omega}-cm) starting silicon materials have been studied in the search of room temperature neutron radiation-hard silicon detectors. It has been found that, moderate resistivity (300-700 {Omega}-cm) silicon detectors, after being irradiated to 5.0 {times} 10{sup 13} to 2.0 {times} 10{sup 14} n/cm{sup 2}, are extremely stable in terms of the detector full depletion voltage (V{sub d}) or the net effective concentration of ionized space charges (N{sub eff} ---- there is little ``reverse annealing`` of N{sub eff} at RT and elevated temperatures as compared with large reverse annealing observed for high resistivity silicon detectors. Detectors with starting resistivity of 300-700 {Omega}-cm have been found to be stable, during the equivalent of one year RT anneal that would reach the saturation of the first stage of reverse anneal, within then N{sub eff} window of {vert_bar}N{sub eff}{vert_bar}{le} 2.5 {times} 10{sup 12} cm{sup {minus}3} (V{sub d} = 180 V for d = 300 {mu}m) in a working range of 5.0 {times} 10{sup 13} to 1.5 {times} 10{sup 14} n/cm{sup 2}, or a net neutron radiation tolerance of 1.0 {times} 10{sup 14} n/cm{sup 2}. The observed effects are in very good agreement with an early proposed model, which predicted among others, that there might be an off set between the reverse annealing effect and the partial annealing of the P-V centers that leads to the partial recovery of the shallow impurity donors.

Li, Z.

1994-02-01

279

The Use of an Industrial X-Ray Source for Electronic Component Radiation Effects Work  

Microsoft Academic Search

Low energy X-ray tubes have been used as a source of ionizing radiation in various past radiation effects studies. In such studies there has not been a requirement for the absolute dose to be known, and little detail has been reported regarding the tube characteristics and the type of dosimetry employed. The use of an industrial X-ray source for space

LEONARD ADAMS; IAN THOMPSON

1980-01-01

280

Radiative Component and Combined Heat Transfer in the Thermal Calculation of Finned Tube Banks  

Microsoft Academic Search

For more exact calculation of combined heat transfer in the case of finned tube banks (e.g., in the convective section of a furnace), the radiative heat transfer cannot be neglected. A new method for relatively simple calculation of total heat flux (convection + radiation + conduction in fins) is fully compatible with that for bare tube banks\\/bundles developed earlier. It

Petr Stehlik

1999-01-01

281

Intensity and polarization of the hard X-ray radiation of solar flares at the top and footpoints of a magnetic loop  

NASA Astrophysics Data System (ADS)

The spatial distributions of the intensity and polarization of hard X-rays (HXR) were modeled based on a numerical solution of the nonstationary kinetic Fokker-Plank equation. Two cases of nonstationary long injections (˜10 s) of nonthermal electrons at the top of a flaring loop are considered. In the first case, the injection occurs anisotropically in a cone directed along the field to one of the loop's footpoints. In the second case, electrons are injected isotropically. In the case of the anisotropic injection, the degree of HXR polarization in the footpoints is low and does not exceed 8%. At the same time, the polarization of the radiation from the top in a range of photon energies from 30 to 60 keV reaches 43% at the beginning of injection. Significantly different spatial distributions of HXR characteristics are obtained for the isotropic injection of electrons. In this case, the calculated degree of HXR polarization from the top exhibits a strong variability: it reaches 15-18% at the beginning of injection at photon energies of 30-90 keV, decreases to zero after 5 s, and then, changing its sign, increases to 8%. In the footpoint of the loop, HXR is in fact nonpolarized. The features of the spatial distributions obtained in the simulation process can be measured with X-ray telescopes-polarimeters in future experiments and used for diagnosing the pitch angle distribution of accelerated electrons.

Charikov, Yu. E.; Mel'nikov, V. F.; Kudryavtsev, I. V.

2012-12-01

282

Comparison of the radiation hardness of Magnetic Czochralski and Epitaxial silicon substrates after 26 MeV proton and reactor neutron irradiation  

NASA Astrophysics Data System (ADS)

We report on the processing and characterization of microstrip sensors and pad detectors produced on n- and p-type Magnetic Czochralski (MCz), Epitaxial (EPI) and Float Zone (FZ) silicon within the SMART project to develop radiation-hard silicon position sensitive detectors for future colliders. Each wafer contains 10 microstrip sensors with different geometries, several diodes and test structures. The isolation in the strip detectors produced on p-type material has been achieved by means of a uniform p-spray implantation, with doping of 3×10 12 cm -2 (low-dose p-spray) and 5×10 12 cm -2 (high-dose p-spray). The samples have undergone irradiations with 26 MeV protons and reactor neutrons up to ˜10 16 cm -2 1 MeV equivalent neutrons (n eq/cm 2), and have been completely characterized before and after irradiation in terms of leakage current, depletion voltage and breakdown voltage. The current damage parameter ? has been determined for all substrates. MCz diodes show less pronounced dependence of effective doping concentration Neff on the fluence when compared to standard FZ silicon, giving results comparable to diffusion oxygenated FZ devices for all irradiation sources. The observed increase of Neff with fluence can be interpreted in EPI material as a net donor introduction process, overcompensating the usual acceptor introduction process. This effect is stronger for 26 MeV proton irradiation than for neutron irradiation.

Creanza, D.; Bassignana, D.; Borrello, L.; Boscardin, M.; Bruzzi, M.; de Palma, M.; Focardi, E.; Macchiolo, A.; Manna, N.; Menichelli, D.; Messineo, A.; Piemonte, C.; Pozza, A.; Radicci, V.; Scaringella, M.; Zorzi, N.

2007-09-01

283

Remote detection of radioactive contamination in the atmosphere based on secondary optical and microwave radiation of atmospheric components  

NASA Astrophysics Data System (ADS)

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol and gaseous components in the form of the excited atoms and ions appear in the atmosphere and relax with emission including microwave and optical wavelengths. The observable luminescence of the air during the emergency events at the nuclea power stations are long enough to be dedected by modern receivers. Intensity of such radiation in a radioactive plume is estimated for ecological monitoring of the atmosphere. Aerosols appearing, as a result of UF6 hydrolysis, in the atmosphere and their behavior have been also shown to be detectable with remote sensing.

Chistyakova, Liliya K.; Penin, Sergei T.

1999-12-01

284

Essential Components of Educational Programming for Students Who Are Deaf or Hard of Hearing. Standards for Special Education, Amended June 2004  

ERIC Educational Resources Information Center

This document is intended for classroom teachers, resource personnel, administrators and parents. It is one of a series of documents developed to facilitate programming for students in grades 1 to 12 who have special education needs. The six essential components listed in this document are contained in "Standards for Special Education, Amended…

Alberta Education, 2007

2007-01-01

285

Superoxide anion is generated from cellular metabolites by solar radiation and its components  

SciTech Connect

Several endogenous cellular constituents were tested for their ability to produce superoxide anion (O2-) from ground-state molecular oxygen upon irradiation by solar radiation. The pyridine cofactors NADPH and NADH, riboflavin, and the nucleosides 2-thiouracil and 4-thiouridine were found to sensitize the transmission of photon energy from solar radiation and monochromatic radiation (290, 334, 365, and 405 nm) to oxygen, resulting in O2- formation, as detected by superoxide dismutase-inhibitable cytochrome c reduction. Quantum yields for the production of O2- indicate that NADPH is the most efficient and riboflavin the least efficient of the compounds tested. These data indicate that endogenous compounds may participate in the production of O2- by solar radiation and imply that O2- may play a role in sunlight-induced erythema and dermal carcinogenesis.

Cunningham, M.L.; Krinsky, N.I.; Giovanazzi, S.M.; Peak, M.J.

1985-01-01

286

MODES, CAVITIES, AND OPTICAL COMPONENTS: New algorithm for numerical simulation of the propagation of laser radiation  

NASA Astrophysics Data System (ADS)

A new more accurate calculation algorithm (with a variable grid-mesh size) is proposed for the propagation of radiation considered in the paraxial approximation based on the Fresnel — Kirchhoff formula. The algorithm was used to develop the FRESNEL program intended for simulation of the propagation of radiation through laser systems. Examples of calculations carried out with the new algorithm are given and they are compared with the traditional method.

Epatko, I. V.; Malyutin, A. A.; Serov, R. V.; Solov'ev, D. A.; Chulkin, A. D.

1998-08-01

287

Photosynthetically active components of global solar radiation: Measurements and model computations  

Microsoft Academic Search

Summary  A three-year(1980–82) record of global solar radiation measurements made at Corvallis, Oregon, U.S.A. (44°34N, 123°14W; 65.5 m) has been utilized to determine the distribution of radiant energy in broad spectral intervals in the visible (0.385–0.695 m) region of the spectrum which is often referred to as the photosynthetically active radiation or PAR band. The mean values of the ratios borne

C. R. Nagaraja Rao

1984-01-01

288

Epigenetic alterations in ultraviolet radiation-induced skin carcinogenesis: interaction of bioactive dietary components on epigenetic targets.  

PubMed

The importance of epigenetic alterations in the development of various diseases including the cancers has been realized. As epigenetic changes are reversible heritable changes, these can be utilized as an effective strategy for the prevention of cancers. DNA methylation is the most characterized epigenetic mechanism that can be inherited without changing the DNA sequence. Although limited available data suggest that silencing of tumor suppressor genes in ultraviolet (UV) radiation-exposed epidermis leads to photocarcinogenesis and is associated with a network of epigenetic modifications including alterations in DNA methylation, DNA methyltransferases and histone acetylations. Various bioactive dietary components have been shown to protect skin from UV radiation-induced skin tumors in animal models. The role of bioactive dietary components, such as, (-)-epicatechins from green tea and proanthocyanidins from grape seeds has been assessed in chemoprevention of UV-induced skin carcinogenesis and underlying epigenetic mechanism in vitro and in vivo animal models. These bioactive components have the ability to block UV-induced DNA hypermethylation and histone modifications in the skin required for the silencing of tumor suppressor genes (e.g. Cip1/p21, p16(INK4a) ). This information is of importance for understanding the role of epigenetic modulation in UV-induced skin tumor and the chemopreventive mechanism of bioactive dietary components. PMID:22017262

Katiyar, Santosh K; Singh, Tripti; Prasad, Ram; Sun, Qian; Vaid, Mudit

2012-01-01

289

Epigenetic Alterations in Ultraviolet Radiation-Induced Skin Carcinogenesis: Interaction of Bioactive Dietary Components on Epigenetic Targets†  

PubMed Central

The importance of epigenetic alterations in the development of various diseases including the cancers has been realized. As epigenetic changes are reversible heritable changes, these can be utilized as an effective strategy for the prevention of cancers. DNA methylation is the most characterized epigenetic mechanism that can be inherited without changing the DNA sequence. Although limited, but available data suggest that silencing of tumor suppressor genes in ultraviolet (UV) radiation-exposed epidermis leads to photocarcinogenesis and is associated with a network of epigenetic modifications including alterations in DNA methylation, DNA methyltransferases and histone acetylations. Various bioactive dietary components have been shown to protect skin from UV radiation-induced skin tumors in animal models. The role of bioactive dietary components, such as, (?)-epicatechins from green tea and proanthocyanidins from grape seeds, has been assessed in chemoprevention of UV-induced skin carcinogenesis and underlying epigenetic mechanism in vitro and in vivo animal models. These bioactive components have the ability to block UV-induced DNA hypermethylation and histone modifications in the skin required for the silencing of tumor suppressor genes (e.g., Cip1/p21, p16INK4a). These information are of importance for understanding the role of epigenetic modulation in UV-induced skin tumor and the chemopreventive mechanism of bioactive dietary components.

Katiyar, Santosh K.; Singh, Tripti; Prasad, Ram; Sun, Qian; Vaid, Mudit

2011-01-01

290

Impact of Bone Marrow Radiation Dose on Acute Hematologic Toxicity in Cervical Cancer: Principal Component Analysis on High Dimensional Data  

SciTech Connect

Purpose: To study the effects of increasing pelvic bone marrow (BM) radiation dose on acute hematologic toxicity in patients undergoing chemoradiotherapy, using a novel modeling approach to preserve the local spatial dose information. Methods and Materials: The study included 37 cervical cancer patients treated with concurrent weekly cisplatin and pelvic radiation therapy. The white blood cell count nadir during treatment was used as the indicator for acute hematologic toxicity. Pelvic BM radiation dose distributions were standardized across patients by registering the pelvic BM volumes to a common template, followed by dose remapping using deformable image registration, resulting in a dose array. Principal component (PC) analysis was applied to the dose array, and the significant eigenvectors were identified by linear regression on the PCs. The coefficients for PC regression and significant eigenvectors were represented in three dimensions to identify critical BM subregions where dose accumulation is associated with hematologic toxicity. Results: We identified five PCs associated with acute hematologic toxicity. PC analysis regression modeling explained a high proportion of the variation in acute hematologicity (adjusted R{sup 2}, 0.49). Three-dimensional rendering of a linear combination of the significant eigenvectors revealed patterns consistent with anatomical distributions of hematopoietically active BM. Conclusions: We have developed a novel approach that preserves spatial dose information to model effects of radiation dose on toxicity, which may be useful in optimizing radiation techniques to avoid critical subregions of normal tissues. Further validation of this approach in a large cohort is ongoing.

Yun Liang [Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California (United States); Messer, Karen [Division of Biostatistics and Bioinformatics, Moores Cancer Center, University of California San Diego, La Jolla, California (United States); Rose, Brent S.; Lewis, John H.; Jiang, Steve B.; Yashar, Catheryn M.; Mundt, Arno J. [Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California (United States); Mell, Loren K., E-mail: lmell@ucsd.ed [Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California (United States)

2010-11-01

291

Unified theories of active galactic nuclei - The hard X-ray spectrum of NGC 1068  

Microsoft Academic Search

We have reanalyzed the Ginga observation of the archetypal Seyfert 2 galaxy NGC 1068. The X-ray spectrum can be decomposed into four components: a hard X-ray power law, iron K-alpha emission-line radiation, reflection from an accretion disc or molecular torus, and emission-line radiation at about 8 keV. Although reflection is not required, its inclusion is consistent with the data and

D. A. Smith; C. Done; K. A. Pounds

1993-01-01

292

Estimates of power deposited via cesium/barium beta and gamma radiation captured in components of a Hanford cesium chloride capsule and by components of overpacked capsules placed in an interim dry storage facility.  

National Technical Information Service (NTIS)

The deposition of power in Hanford cesium chloride capsules and in the components of design concepts for overpacking and interim storage were determined as requested. The power deposition results from the selective capture of gamma and beta radiation comi...

V. E. Roetman

1996-01-01

293

Patient-Assessed Late Toxicity Rates and Principal Component Analysis After Image-Guided Radiation Therapy for Prostate Cancer  

SciTech Connect

Purpose: The aims of this study were to determine the incidence of patient-assessed late toxicity after high-dose, image-guided radiation therapy in a cohort of men with prostate cancer; and to correlate toxicity with conventional dosimetric parameters and rectal and bladder dose-volume histograms (DVH) reduced using principal component analysis. Methods and Materials: Toxicity questionnaires were sent to 690 men treated for localized prostate cancer to 75.6 Gy or 79.8 Gy using three-dimensional conformal radiation therapy (3DCRT) or intensity-modulated radiation therapy (IMRT) between 1997 and 2003 at the Princess Margaret Hospital. Toxicity was graded according to the modified Radiation Therapy Oncology Group (RTOG)-late effects normal tissue (LENT) scoring system. Late rectal and bladder toxicity scores were dichotomized as < Grade 2 and {>=} Grade 2, and correlated with dosimetric parameters and with the first three principal components of rectal and bladder DVHs. Results: In all, 63% of the patients completed the questionnaire. At a median follow-up of 37 months, the incidence of late rectal toxicity RTOG Grades 1, 2, and 3 was 25.2%, 2.5%, and 0.7% respectively. The incidence of late urinary toxicity RTOG Grade 1, 2, and 3 was 16.5%, 8.8%, and 0.9% respectively. Maintenance of erectile function sufficient for intercourse was reported in 68%. No dosimetric parameter analyzed, including principal component analysis reduction of DVHs, correlated with late toxicity. Conclusions: Postal questionnaire was effective for collection of patient-assessed late toxicity data. The incidence of late toxicity was low, with a lack of correlation to dosimetric parameters. We attribute this to the use of conformal techniques and daily image guidance.

Skala, Marketa [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Rosewall, Tara [Department of Radiation Therapy, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Dawson, Laura [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Divanbeigi, Lorella [Department of Radiation Therapy, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Lockwood, Gina [Department of Biostatistics, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Thomas, Christopher [Department of Medical Physics, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Crook, Juanita [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Chung, Peter [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Warde, Padraig [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada); Catton, Charles [Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada)]. E-mail: charles.catton@rmp.uhn.on.ca

2007-07-01

294

Radiation Effects and Hardening Techniques for Spacecraft Microelectronics  

NASA Astrophysics Data System (ADS)

The natural radiation from the Van Allen belts, solar flares, and cosmic rays found outside of the protection of the earth's atmosphere can produce deleterious effects on microelectronics used in space systems. Historically civil space agencies and the commercial satellite industry have been able to utilize components produced in special radiation hardened fabrication process foundries that were developed during the 1970s and 1980s under sponsorship of the Departments of Defense (DoD) and Energy (DoE). In the post--cold war world the DoD and DoE push to advance the rad--hard processes has waned. Today the available rad--hard components lag two-plus technology node generations behind state- of-the-art commercial technologies. As a result space craft designers face a large performance gap when trying to utilize available rad--hard components. Compounding the performance gap problems, rad--hard components are becoming increasingly harder to get. Faced with the economic pitfalls associated with low demand versus the ever increasing investment required for integrated circuit manufacturing equipment most sources of rad--hard parts have simply exited this market in recent years, leaving only two domestic US suppliers of digital rad--hard components. This paper summarizes the radiation induced mechanisms that can cause digital microelectronics to fail in space, techniques that can be applied to mitigate these failure mechanisms, and ground based testing used to validate radiation hardness/tolerance. The radiation hardening techniques can be broken down into two classes, Hardness By Process (HBP) and Hardness By Design (HBD). Fortunately many HBD techniques can be applied to commercial fabrication processes providing space craft designer with radiation tolerant Application Specific Integrated Circuits (ASICs) that can bridge the performance gap between the special HBP foundries and the commercial state-of-the-art performance.

Gambles, J. W.; Maki, G. K.

2002-01-01

295

A radiation hard vacuum switch  

DOEpatents

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

Boettcher, G.E.

1988-07-19

296

Solar heating system, and improved heat collecting and radiating components, for livestock-confining buildings  

SciTech Connect

A system for heating a building adapted to confine animals includes a solar collector, means for storing the heat absorbed by the collector and heat radiating floor mats which use such heat. The collector includes panels each having lightweight, clear, parallel plastic tubes secured at their ends to headers of similar material. The tubes are disposed in troughs in the panel base having inclined reflective side walls to concentrate reflected solar energy on the tubes. The heat radiating floor mats comprise tubes and headers like those used in the solar collector panels.

McAlister, R.E.

1984-12-18

297

Evaluation of highly ionizing components in high-energy nucleon radiation fields  

NASA Technical Reports Server (NTRS)

The data and models for nuclear fragment recoil distribution produced by high-energy nuclear events in tissue are reviewed. Results for linear energy transfer distributions in soft tissue are derived, and a simple model is developed for use in radiation studies and risk estimates.

Wilson, John W.; Townsend, Lawrence W.; Khan, Ferdous

1989-01-01

298

Nimbus-6 and -7 Earth Radiation Budget (ERB) sensor details and component tests  

NASA Technical Reports Server (NTRS)

Construction details and operating characteristics are described for the thermopile (used in the solar and fixed-Earth channels) and the pyroelectric detector (used in the Earth-scanning channels) carried on the Nimbus 6 and the Nimbus 7 satellites for gathering Earth radiation budget data. Properties of the black coating for the detectors, and sensor testing and calibration are discussed.

Soule, H. V.; Kyle, H. L.; Jacobowitz, H.; Hickey, J.

1983-01-01

299

Analysis of the Radiation Environment Effects on Electronic Components in Near-Earth Orbits  

Microsoft Academic Search

The radiation environments at two low altitude orbits have been calculated with the NASA space environment models and codes AP8\\/AE8, Vette, and CREME. LET spectra and device upset rates for various solar activity scenarios have been determined. Dose deposition into silicon targets as a function of Aluminum shielding thickness has been also calculated with a Monte Carlo code. The results

L. Varga; E. B. Horvath; T. Cousins

2001-01-01

300

Generalized cubic equation of state and the radial distribution functions at contact for multi-component hard-sphere mixtures with large size ratio  

NASA Astrophysics Data System (ADS)

A generalized cubic (GC) equation of state (EOS) with two independent parameters is proposed. The GC EOS can include EOS from both virial and compressibility routes of Percus-Yevick theory in it as special cases. The two parameters are determined by fitting well-known virial coefficients of pure fluid. The generalized cubic EOS can be directly and consistently extended to multi-component mixtures merely demanding of the EOS of mixtures also is cubic, and combining two strict physical conditions for the radial distribution functions at contact (RDFC) of mixtures. The calculated virial coefficients of pure fluid and predicted compressibility factors and RDFC for both pure fluid and mixtures are excellent as compared with the simulation data. The values of RDFC for mixtures with extremely large size ratio are far better than the expressions in literature.

Sun, Jiu-Xun; Wu, Qiang; Cai, Ling-Cang; Jin, Ke

2014-06-01

301

Modelling of multi-vortex convection of fine alloying components in the molten pool under the laser radiation  

NASA Astrophysics Data System (ADS)

The work is devoted to the mathematical modelling and numerical solution of the problems of conjugate micro-convection, which arises under the laser radiation action in the metal melt with surface-active refractory disperse components added for the modification, hardening, and doping of the treated surface. A multi-vortex structure of the melt flow has been obtained, the number of vortices in which depends on the surface tension variation, on the temperature and power of laser radiation. Special attention is paid to the numerical modelling of the behavior in the melt of the substrate of disperse admixture consisting of the tungsten carbide particles. The role of microconvection in the distribution of powder particles in the surface layer of the substrate after its cooling is shown.

Gurin, A. M.; Kovalev, O. B.

2013-06-01

302

The Suzaku Discovery of A Hard Power-Law Component in the Spectra of Short Bursts from SGR 0501+4516  

NASA Astrophysics Data System (ADS)

Using data with the Suzaku XIS and HXD, spectral studies of short bursts from the soft gamma repeater SGR 0501+4516 were performed. In total, 32 bursts were detected during the ˜60 ks of observation conducted in the 2008 August activity. Excluding the strongest one, the remaining 31 bursts showed an average 2-40 keV fluence of (1.0+0.3-0.5) × 10-9 erg cm-2. A 1-40 keV spectrum summed over them leaves significant positive residuals in the HXD-PIN band with ?2/d.o.f. = 74/50, when fitted with a two-blackbody function. By adding a power-law model, the fit became acceptable with ?2/d.o.f. = 56/48, yielding a photon index of ? = 1.0+0.4-0.3. This photon index is comparable to ? = 1.33+0.23-0.16 (Enoto et al. 2010, ApJ, 715, 665) for the persistent emission of the same object obtained with Suzaku. The two-blackbody components showed very similar ratios, both in the temperature and the emission radii, to those comprising the persistent emission. However, the power-law to two-blackbody flux ratio was possibly higher than that of the persistent emission at the 2.6? level. Based on these measurements, average wide-band properties of these relatively weak bursts are compared with those of the persistent emission.

Nakagawa, Yujin E.; Makishima, Kazuo; Enoto, Teruaki

2011-11-01

303

Distinct Pigmentary and Melanocortin 1 Receptor–Dependent Components of Cutaneous Defense against Ultraviolet Radiation  

Microsoft Academic Search

Genetic variation at the melanocortin 1 receptor (MC1R) is an important risk factor for developing ultraviolet (UV) radiation–induced skin cancer, the most common form of cancer in humans. The underlying mechanisms by which the MC1R defends against UV-induced skin cancer are not known. We used neonatal mouse skin (which, like human skin, contains a mixture of melanocytes and keratinocytes) to

Craig S April; Gregory S Barsh

2007-01-01

304

Nuclear Bursts Produced in the Low Energy Nucleonic Component of the Cosmic Radiations  

Microsoft Academic Search

The production rate of low energy nuclear bursts or stars has been measured as a function of altitude and geomagnetic lactitude, lambda, at 0°, 40° N and 52° N through 65° N. The measurements were obtained in aircraft using fast electron collection pulse chambers. Exponential absorption paths, Lb(lambda), for the nuclear burst or star producing radiation below ~200 g-cm-2 are

J. A. Simpson; H. W. Baldwin; R. B. Uretz

1951-01-01

305

Aerosol characteristics and surface radiative forcing components during a dust outbreak in Gwangju, Republic of Korea  

Microsoft Academic Search

Atmospheric surface aerosol radiative forcing (SARF) ?F, forcing efficiency ?Fe and fractional forcing efficiency ?FFe evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust\\u000a outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical\\u000a depth (AOD), ?\\u000a a?, Angstrom exponent ?, mass concentration of fine and coarse mode

K. O. Ogunjobi; Y. J. Kim

2008-01-01

306

Prevention of ultraviolet radiation-induced suppression of contact hypersensitivity by Aloe vera gel components  

Microsoft Academic Search

We have recently reported that Aloe vera gel contains small molecular weight immunomodulators, G1C2F1, that restore ultraviolet B (UVB)-suppressed accessory cell function of epidermal Langerhans cells (LC) in vitro. In the present study we evaluated the UVB-protective activity of G1C2F1 in vivo. Exposure of the shaved abdominal skin of mice to 2.4 KJ\\/m2 of UVB radiation resulted in suppression of contact

Chong Kil Lee; Seong Sun Han; Young Keun Shin; Myung Hee Chung; Young In Park; Seung Ki Lee; Yeong Shik Kim

1999-01-01

307

Feasibility of modifying the high resolution infrared radiation sounder (HIRS/2) for measuring spectral components of Earth radiation budget  

NASA Technical Reports Server (NTRS)

The concept of adding four spectral channels to the 20 channel HIRS/2 instrument for the purpose of determining the origin and profile of radiant existence from the Earth's atmosphere is considered. Methods of addition of three channels at 0.5, 1.0 and 1.6 micron m to the present 0.7 micron m visible channel and an 18-25 micron m channel to the present 19 channels spaced from 3.7 micron m to 15 micron m are addressed. Optical components and physical positions were found that permit inclusion of these added channels with negligible effect on the performance of the present 20 channels. Data format changes permit inclusion of the ERB data in the 288 bits allocated to HIRS for each scan element. A lamp and collimating optic assembly may replace one of the on board radiometric black bodies to provide a reference source for the albedo channels. Some increase in instrument dimensions, weight and power will be required to accommodate the modifications.

Koenig, E. W.; Holman, K. A.

1980-01-01

308

Radiation pressure-assisted acceleration of ions using multi-component foils in high-intensity laser-matter interactions  

NASA Astrophysics Data System (ADS)

Experimental results on the acceleration of protons and carbon ions from ultra-thin polymer foils at intensities of up to 6 × 1019 W cm-2 are presented revealing quasi-monoenergetic spectral characteristics for different ion species at the same time. For carbon ions and protons, a linear correlation between the cutoff energy and the peak energy is observed when the laser intensity is increased. Particle-in-cell simulations supporting the experimental results imply an ion acceleration mechanism driven by the radiation pressure as predicted for multi-component foils at these intensities.

Aurand, B.; Kuschel, S.; Jäckel, O.; Rödel, C.; Zhao, H. Y.; Herzer, S.; Paz, A. E.; Bierbach, J.; Polz, J.; Elkin, B.; Paulus, G. G.; Karmakar, A.; Gibbon, P.; Kuehl, T.; Kaluza, M. C.

2013-03-01

309

Direct and indirect effects of UV radiation on DNA and its components  

Microsoft Academic Search

In this survey, emphasis was placed on the main photoreactions of nucleic acid components, involving both direct and indirect effects. The main UVB- and UVA-induced DNA photoproducts, together with the mechanisms of their formation, are described. Information on the photoproduct distribution within cellular DNA is also provided, taking into account the limitations of the different analytical methods applied to monitor

Jean-Luc Ravanat; Thierry Douki; Jean Cadet

2001-01-01

310

Latitude Variation of the Diffuse Component of the Mean Energy gamma Radiation.  

National Technical Information Service (NTIS)

For determining the diffuse component of gamma ray in the 15 to 75 MeV range arriving from near the galactic center, a digitized spark chamber was launched aboard two balloons from Resende, Brazil on 19 November and 3 December 1975. In each flight the det...

C. M. Espirito Santo

1981-01-01

311

Assessment of the Water Quality Components in Turbid Estuarine Waters Based on Radiative Transfer Approximations  

EPA Science Inventory

Bio-geo-optical data collected in the Neuse River Estuary, North Carolina, USA were used to develop a semi-empirical optical algorithm for assessing inherent optical properties associated with water quality components (WQCs). Three wavelengths (560, 665 and 709 nm) were explored ...

312

Diagnostic components in harsh radiation environments: Possible overlap in R and D requirements of inertial confinement and magnetic fusion systems  

SciTech Connect

The next generation of large scale fusion devices--ITER/LMJ/NIF--will require diagnostic components to operate in environments far more severe than those encountered in present facilities. This harsh environment is the result of high fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiation, and in some cases, debris and shrapnel, at levels several orders of magnitude higher than those experienced in today's devices. The similarities and dissimilarities between environmental effects on diagnostic components for the inertial confinement and magnetic confinement fusion fields have been assessed. Areas in which considerable overlap have been identified are optical transmission materials and optical fibers in particular, neutron detection systems and electronics needs. Although both fields extensively use cables in the hostile environment, there is little overlap because the environments and requirements are very different.

Bourgade, J. L.; Leray, J. L.; Baggio, J.; Girard, S. [CEA/DAM Ile de France, Bruyeres le Chatel, 91297 Arpajon Cedex (France); Costley, A. E.; Dentan, M.; Bertalot, L.; Vayakis, G. [ITER Organization, Cadarache, 13108 St Paul-Les-Durance (France); Reichle, R.; Hutter, T. [Association EURATOM-CEA, DSM/IRFM, CEA-Cadarache, 13108 St. Paul-lez-Durance (France); Hodgson, E. R.; Morono, A. [EURATOM/CIEMAT Fusion Association, 28040 Madrid (Spain); Hsing, W.; Eder, D.; Moran, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Glebov, V.; Shmayda, W.; Sangster, T. C.; Stoeckl, C.; Pien, G. [Laboratory for Laser Energetics (LLE), University of Rochester, 250E. River Rd, Rochester, New York 14623 (United States)] (and others)

2008-10-15

313

Inferring ultraviolet anatomical exposure patterns while distinguishing the relative contribution of radiation components  

SciTech Connect

Exposure to solar ultraviolet (UV) radiation is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors, but individual exposure data remain scarce. While ground UV irradiance is monitored via different techniques, it is difficult to translate such observations into human UV exposure or dose because of confounding factors. A multi-disciplinary collaboration developed a model predicting the dose and distribution of UV exposure on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a simulation tool that estimates solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by various body locations is computed for direct, diffuse and reflected radiation separately. Dosimetric measurements obtained in field conditions were used to assess the model performance. The model predicted exposure to solar UV adequately with a symmetric mean absolute percentage error of 13% and half of the predictions within 17% range of the measurements. Using this tool, solar UV exposure patterns were investigated with respect to the relative contribution of the direct, diffuse and reflected radiation. Exposure doses for various body parts and exposure scenarios of a standing individual were assessed using erythemally-weighted UV ground irradiance data measured in 2009 at Payerne, Switzerland as input. For most anatomical sites, mean daily doses were high (typically 6.2-14.6 Standard Erythemal Dose, SED) and exceeded recommended exposure values. Direct exposure was important during specific periods (e.g. midday during summer), but contributed moderately to the annual dose, ranging from 15 to 24% for vertical and horizontal body parts, respectively. Diffuse irradiation explained about 80% of the cumulative annual exposure dose.

Vuilleumier, Laurent [Federal Office of Meteorology and Climatology, MeteoSwiss, Payerne (Switzerland); Milon, Antoine; Vernez, David [Institute of Work and Health, University of Lausanne and Geneva, Lausanne (Switzerland); Bulliard, Jean-Luc [Cancer Epidemiology Unit, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne (Switzerland); Moccozet, Laurent [Institute of Services Science, University of Geneva (Switzerland)

2013-05-10

314

The radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. III. Effect of diundecyl phthalate: chemical kinetics of a three-component system  

Microsoft Academic Search

The radiation chemistry of poly(vinyl chloride) (PVC) blended with trimethylolpropanetrimethacrylate (TMPTMA) and diundecyl phthalate (DUP) has been examined. This three-component mixture contains a base resin (PVC), a crosslinking sensitizer (TMPTMA), and a physical modifier (DUP). These are the basic components in any radiation-curable coating. The kinetics and mechanism of the crosslinking reactions were studied with reference to the dependence on

T. N. Bowmer; W. I. Vroom; M. Y. Hellman

1983-01-01

315

Muon Decay with Parity Nonconserving Interactions and Radiative Corrections in the Two-Component Theory  

Microsoft Academic Search

The decay of a polarized muon is studied in the case of the general four-component neutrino theory with the most general parity-nonconserving interaction. A three-parameter formula for the decay-electron distribution is obtained as a generalization of the Michel formula for an unpolarized muon. This general formula is examined to determine to what extent the observed spectrum enables one to decide

Toichiro Kinoshita; Alberto Sirlin

1957-01-01

316

Radiation-induced infrared absorption in nuclear-pumped laser cavity components  

SciTech Connect

The transient transmission of laser activity cavity materials has been measured when they are subjected to 20 ms, fat, and nominal $3 nuclear radiation pulses from Sandia National Laboratories ACRR reactor. Infrasil and 7940 fused silica, and AR and high reflectance coatings have been transient tested at 1.06, 1.73, and 2.03 microns for gamma doses ranging from 0.3 to 0.65 Mrad and neutron fluences ranging from 4.0 to 1.5 10{sup 14} n/cm{sup 2}. pulse widths range from 12 to 250 ms. Transient absorption in 7940 silica and the AR coatings is less than the noise for the conditions of this experiment. At the wavelengths listed above the upper bound for the absorption coefficient of 17940 is 0.00158 cm{sup {minus}1} for single pulse operation. The reflectivity of the HR coating does not change when it is irradiated. Infrasil has both a transient and a permanent induced absorption when it is subjected to radiation. For single pulse operation the absorption coefficients at 1.06, 1.73, and 2.03 microns are 0.0115, 0.0026, and 0.0039 cm{sup {minus}1}, respectively.

Brannon, P.J.; Bodette, D.E.; McArthur, D.A.

1992-07-01

317

Radiation-induced infrared absorption in nuclear-pumped laser cavity components  

NASA Astrophysics Data System (ADS)

The transient transmission of laser activity cavity materials has been measured when they are subjected to 20 ms, fat, and nominal $3 nuclear radiation pulses from Sandia National Laboratories ACRR reactor. Infrasil and 7940 fused silica, and AR and high reflectance coatings have been transient tested at 1.06, 1.73, and 2.03 microns for gamma doses ranging from 0.3 to 0.65 Mrad and neutron fluences ranging from 4.0 to 1.5 10(sup 14) n/cm(sup 2). pulse widths range from 12 to 250 ms. Transient absorption in 7940 silica and the AR coatings is less than the noise for the conditions of this experiment. At the wavelengths listed above the upper bound for the absorption coefficient of 17940 is 0.00158 cm(sup -1) for single pulse operation. The reflectivity of the HR coating does not change when it is irradiated. Infrasil has both a transient and a permanent induced absorption when it is subjected to radiation. For single pulse operation the absorption coefficients at 1.06, 1.73, and 2.03 microns are 0.0115, 0.0026, and 0.0039 cm(sup -1), respectively.

Brannon, P. J.; Bodette, D. E.; McArthur, D. A.

1992-07-01

318

Successful Treatment of High Risk and Recurrent Pediatric Desmoids Using Radiation as a Component of Multimodality Therapy  

SciTech Connect

Purpose: To evaluate the role of radiation therapy (RT) as a component of multimodality therapy for pediatric desmoids. Methods and Materials: Twenty-one children diagnosed between 1987 and 2005 were identified. Median age at start of treatment was 13 years (range, 2-21). Primary therapy consisted of resection alone (10), resection + external beam radiation therapy (EBRT) (5), resection + chemotherapy (CT; 3), EBRT alone (1), and CT alone (2). Results: The median follow-up from start of treatment is 75.7 months (range, 16-162). Examining patients with gross total resections (GTRs) (-) margins and those who had GTRs (+) margins followed by EBRT, only 2 of 7 failed primary treatment. Conversely, 13 of 14 patients with other primary treatments failed locally. Of the 15 patients who recurred, only 1 patient had a GTR (-) margins. Seven of these patients had salvage therapy that did not include RT, and of these only 2 have no evidence of disease (NED) at last follow-up. In contrast, the remaining 8 patients received RT as a component of their final salvage therapy and 7 of these are NED at last follow-up. At last follow-up, no patient has died, although toxicities of therapy have occurred. Conclusions: Local control is difficult to achieve in pediatric patients with desmoids. In the setting in which negative surgical margins cannot be achieved, RT plays a key role in achieving NED status. Even after multiple recurrences, successful salvage is achievable, particularly when high-dose focal therapy is incorporated.

Jabbari, Siavash [Department of Radiation Oncology, University of California, San Francisco, CA (United States); Andolino, David [Department of Radiation Oncology, Indiana University, Indianapolis, IN (United States); Weinberg, Vivian [Department of Biostatistics, University of California, San Francisco, CA (United States); Missett, Brian T. [Kaiser Permanente Medical Group, Santa Clara, CA (United States); Law, Jason [Department of Pediatrics, University of California, San Francisco, CA (United States); Wara, William M. [Department of Radiation Oncology, University of California, San Francisco, CA (United States); O'Donnell, Richard J. [Department of Orthopedic Surgery, University of California, San Francisco, CA (United States); Matthay, Katherine K.; DuBois, Steven G.; Goldsby, Robert [Department of Pediatrics, University of California, San Francisco, CA (United States); Haas-Kogan, Daphne A. [Department of Radiation Oncology, University of California, San Francisco, CA (United States)], E-mail: dhaaskogan@radonc.ucsf.edu

2009-09-01

319

IC and Component Selection for Space Systems  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the integrated circuit (IC) and selections of the IC components for space systems. Included in the discussion are a overview of semiconductors and the evolution of integrated circuit. It also reviews the three different viewpoints of the IC selection: technical, programmatic, and risk. From a radiation perspective there are four criteria for selecting ICs for space systems: guaranteed hardness, historical ground-based data, historical flight usage, and unknown assurance.

Label, Kenneth A.; Cohn, Lewis M.

2007-01-01

320

Polaradiometric pyrometer in which the parallel and perpendicular components of radiation reflected from an unpolarized light source are equalized with the thermal radiation emitted from a measured object to determine its true temperature  

NASA Technical Reports Server (NTRS)

A radiation pyrometer for measuring the true temperature of a body is provided by detecting and measuring thermal radiation from the body based on the principle that the effects of angular emission I(sub 1) and reflection I(sub 2) on the polarization states p and s of radiation are complementary such that upon detecting the combined partial polarization state components I(sub p) =I(sub 1p) + I(sub 2p) and I(sub s)=I(sub 1s) + I(sub 2s) and adjusting the intensity of the variable radiation source of the reflected radiation I(sub 2) until the combined partial radiation components I(sub p) and I(sub s) are equal, the effects of emissivity as well as diffusivity of the surface of the body are eliminated, thus obviating the need for any post processing of brightness temperature data.

Abtahi, Ali A. (Inventor)

1995-01-01

321

Hard Wear-Resistant Coatings: A Review  

Microsoft Academic Search

\\u000a Hard coatings have been used for many decades to provide wear resistance. In this paper, the industrial requirements and benefits\\u000a of such hard coatings are introduced. Common hard coatings (nitrides, carbides, multi-components, etc.) and some of the new\\u000a generation coatings (multiple layers, multi-layers, gradient and nano-scaled) are reviewed and compared. Furthermore, typical\\u000a industrial applications and performances as well as common

T. Hoornaert; Z. K. Hua; J. H. Zhang

322

Aerosol characteristics and surface radiative forcing components during a dust outbreak in Gwangju, Republic of Korea.  

PubMed

Atmospheric surface aerosol radiative forcing (SARF) DeltaF, forcing efficiency DeltaF(e) and fractional forcing efficiency DeltaFF(e) evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical depth (AOD), tau (alambda), Angstrom exponent alpha, mass concentration of fine and coarse mode particles) were also reported for the station between January 2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25-0.45 while some high aerosol events in which AODs > or = 0.6 were observed during the severe dust episodes. For example, AOD increases from annual average value of 0.34 +/- 0.13 at 501 nm to values >0.60 during the major dust events of March 27-30 and April 7-9, 2000, respectively. The alpha (501-870 nm) which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal forcing efficiency DeltaDF(e) at Gwangju was estimated to be -81.10 +/- 5.14 W m (-2)/tau (501 nm) and -47.09 +/- 2.20 W m (-2)/tau (501 nm) for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency DeltaFDF(e) were -15.8 +/- 0.64%/tau (501 nm) and -22.87 +/- 1.13%/tau (501 nm) for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to classify the air-mass and types of aerosol reaching the site during the Asia dust episodes. PMID:17458510

Ogunjobi, K O; Kim, Y J

2008-02-01

323

Componentes Do Balanco de Radiacao Acima DA Copa DA Floresta Amazonica (Terceira Campanha de Coleta de Dados) (Radiation Balance Components Above the Tropical Evergreen Amazon Forests (3rd Campaign of Data Collection)).  

National Technical Information Service (NTIS)

Daytime variation of radiation balance components of solar radiation K(incident), reflected radiation K(reflected), net radiation Q(net) and net longwave radiation L(net), from July to August 1984, over the tropical evergreen Amazon forest was investigate...

Y. Viswanadham R. G. B. Andre L. Deanedeabreusa A. O. Manzi V. Depaulasilvafilho

1987-01-01

324

Advanced radiation techniques for inspection of diesel engine combustion chamber materials components. Final report  

SciTech Connect

Heavy duty truck engines must meet stringent life cycle cost and regulatory requirements. Meeting these requirements has resulted in convergence on 4-stroke 6-in-line, turbocharged, and after-cooled engines with direct-injection combustion systems. These engines provide much higher efficiencies (42%, fuel consumption 200 g/kW-hr) than automotive engines (31%, fuel consumption 270 g/kW-hr), but at higher initial cost. Significant near-term diesel engine improvements are necessary and are spurred by continuing competitive, Middle - East oil problems and Congressional legislation. As a result of these trends and pressures, Caterpillar has been actively pursuing a low-fuel consumption engine research program with emphasis on product quality through process control and product inspection. The goal of this project is to combine the nondestructive evaluation and computational resources and expertise available at LLNL with the diesel engine and manufacturing expertise of the Caterpillar Corporation to develop in-process monitoring and inspection techniques for diesel engine combustion chamber components and materials. Early development of these techniques will assure the optimization of the manufacturing process by design/inspection interface. The transition from the development stage to the manufacturing stage requires a both a thorough understanding of the processes and a way of verifying conformance to process standards. NDE is one of the essential tools in accomplishing both elements and in this project will be integrated with Caterpillar`s technological and manufacturing expertise to accomplish the project goals.

NONE

1995-10-09

325

A technique using principal component analysis to compare seasonal cycles of Earth radiation from CERES and model computations  

NASA Astrophysics Data System (ADS)

A method for quantitatively comparing the seasonal cycles of two global data sets is presented. The seasonal cycles of absorbed solar radiation (ASR) and outgoing longwave radiation (OLR) have been computed from an eight-year data set from the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers and from a model data set produced by the NASA Goddard Space Flight Center Global Modeling and Assimilation Office. To compare the seasonal cycles from these two data sets, principal component (PC) analysis is used, where the PCs express the time variations and the corresponding empirical orthogonal functions (EOFs) describe the geographic variations. Ocean has a long thermal response time compared to land, so land and ocean are separated for the analysis. The root-mean square values for the seasonal cycles of ASR and OLR are extremely close for the two data sets. The first three PCs are quite close, showing that the time responses and magnitudes over the globe are very similar. The agreement between the two sets of PCs is quantified by computing the matrix of inner products of the two sets. For ASR over land, the first PCs of CERES and the model agree to better than 99.9%. The EOF maps are similar for most of the globe, but differ in a few places, and the agreement of the EOF maps is likewise quantified. Maps of differences between the annual cycles show regions of agreement and disagreement.

Smith, G. Louis; Mlynczak, Pamela E.; Potter, Gerald L.

2012-05-01

326

Diagnostic Components in Harsh Radiation Environments: Possible Overlap in R&D Requirements of IC and MF Systems  

SciTech Connect

The next generation of large scale fusion devices--ITER/LMJ/NIF--will require diagnostic components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiation, and in some cases debris and shrapnel, at levels several orders of magnitude higher than those experienced in today's devices. For several years the question of possible synergy between inertial and the magnetic confinement research has been pursued by members of the respective communities. A first joint workshop specifically devoted to the identification and promotion of these synergies was organized in France, at Aix-en-Provence from June 27th to 29th, 2007. The workshop was attended by about 50 invited specialists. The participants identified a number of subject areas where common overlapping interests could benefit from additional interactions and meetings: windows, optical fibers, mirrors, cables, electronic components and 14 MeV neutron sources. In this paper we summarize the findings of these working groups. We put the discussion into context by including a brief description of the environments and the physical effects that have to be handled.

Bourgade, J L; Costley, A E; Reichle, R; Hodgson, E R; Hsing, W; Glebov, V; Decreton, M; Leeper, R; Leray, J L; Dentan, M; Hutter, T; Morono, A; Eder, D; Shmayda, W; Brichard, B; Baggio, J; Bertalot, L; Vayakis, G; Moran, M; Sangster, T C; Vermeeren, L; Stoeckl, C; Girard, S; Pien, G

2008-05-08

327

Xanthophyll cycle components and capacity for non-radiative energy dissipation in sun and shade leaves of Ligustrum ovalifolium exposed to conditions limiting photosynthesis  

Microsoft Academic Search

The relationships between photosynthetic efficiency, non-radiative energy dissipation and carotenoid composition were studied in leaves ofLigustrum ovalifolium developed either under full sunlight or in the shade. Sun leaves contained a much greater pool of xanthophyll cycle components than shade leaves. The rate of non-radiative energy dissipation, measured as non-photochemical fluorescence quenching (NPQ), was strictly related to the deepoxidation state (DPS)

Enrico Brugnoli; Alessandra Cona; Marco Lauteri

1994-01-01

328

MIL-STD-1553 VLSI components  

NASA Astrophysics Data System (ADS)

The performance, physical and electrical characteristics of novel VLSI components which will support all MIL-STD-1553 terminals are described. A transceiver, protocol, and computer interface set of chips supports remote terminal unit, bus controller, and bus monitor modes of operation. A discussion of these VLSI components is given, and their special features are explored. These features include size and packaging options, radiation hardness, power, and reliability considerations. The special capabilities of these devices are highlighted, along with programming options that facilitate a broad array of applications.

Friedman, Steven N.

329

Hard Rock Penetration Technology.  

National Technical Information Service (NTIS)

This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: 'Hard Rock Penetration - Summary' by George P. Tennyson, Jr.; 'Overview - Hard Rock Penetration' by James C. Dunn; 'An Overvi...

2005-01-01

330

Wear of hard materials by hard particles  

SciTech Connect

Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

Hawk, Jeffrey A.

2003-10-01

331

Hardness of Covalent Crystals  

Microsoft Academic Search

Based on the idea that the hardness of covalent crystal is intrinsic and equivalent to the sum of the resistance to the indenter of each bond per unit area, a semiempirical method for the evaluation of hardness of multicomponent crystals is presented. Applied to beta-BC2N crystal, the predicted value of hardness is in good agreement with the experimental value. It

Faming Gao; Julong He; Erdong Wu; Shimin Liu; Dongli Yu; Dongchun Li; Siyuan Zhang; Yongjun Tian

2003-01-01

332

Considerations for IC and Component Selection for Space Systems  

NASA Technical Reports Server (NTRS)

This viewgraph presentation addresses the integrated cycling and component selection technologies for aerospace systems. The topics include: 1) Semiconductors: The Evolution of ICs - Availability and Technology; 2) IC Selection Requirements - three fields of thought, "The Good", "The Bad" and "The Ugly"; 3) Reliability and Radiation; 4) Radiation Perspective-Four methods of selecting ICs for space systems, Guaranteed hardness, historical ground-based radiation data, historical flight usage, and unknown assurance; 5) Understanding Risk, including risk trade space and ASICs and FPGA sample selection criteria.

LaBel, Kenneth A.; Cohn, Lewis M.

2008-01-01

333

Bandwidths of micro twisted-pair cables and fusion spliced SIMM-GRIN fiber and radiation hardness of PIN/VCSEL arrays  

NASA Astrophysics Data System (ADS)

We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via rad-hard SIMM fibers spliced to rad-tolerant GRIN fibers. The link has several nice features. We have measured the bandwidths of the transmission lines and the results indicate that the micro twisted-pair cables can transmit signals up to ˜1 Gb/s and the fusion spliced fiber ribbon can transmit signals up to ˜2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find at least one candidate PIN and one VCSEL array that can survive to the SLHC dosage.

Gan, K. K.; Fernando, W.; Kagan, H. P.; Kass, R. D.; Law, A.; Lebbai, M. R. M.; Skubic, P. L.; Smith, D. S.

2007-10-01

334

Rad-hard electronics development program for SSC liquid-argon calorimeters  

SciTech Connect

The development program for radiation-hard low-noise low-power front-end electronics for SSC calorimetry is described. Radiation doses of up to 20 MRad and neutron fluences of 10{sup 14} neutrons/cm{sup 2} are expected over ten years of operation. These effects are simulated by exposing JFETs to neutrons and ionizing radiation and measuring the resulting bias, leakage current and noise variations. In the case of liquid-argon calorimeters, a large part of the front-end circuitry may be located directly within the low-temperature environment (90 K), placing additional constraints on the choice of components and on the design. This approach minimizes the noise and the response time. The radiation damage test facilities at Argonne will also be described. These include sources of neutrons, electrons, and gamma radiation. 8 refs., 9 figs.

Stevens, A.; Dawson, J. (Argonne National Lab., IL (USA). High Energy Physics Div.); Kraner, H.; Radeka, V.; Rescia, S. (Brookhaven National Lab., Upton, NY (USA))

1990-01-01

335

Handbook of hard coatings  

SciTech Connect

This book discusses the hard coatings classified as tribologically hard, which are wear resistant and low friction. Three sections discuss tribological properties and new developments. With the development of modern technology in the areas of optical, optoelectronic, and defense related applications, the traditional term hard coatings can be extended. Thus, a system which operates satisfactorily, in a given environment can be said to be hard with respect to that environment. Many hard coatings are ceramic compounds such as oxides, carbides, nitrides, ceramic alloys, cements, diamonds and cubic nitride.

Bunshah, R.; Weissmantel, C. [eds.

2000-07-01

336

Ultra-Low Power High Temperature and Radiation Hard Complementary Metal-Oxide-Semiconductor (CMOS) Silicon-on-Insulator (SOI) Voltage Reference  

PubMed Central

This paper presents an ultra-low power CMOS voltage reference circuit which is robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of ?40–200 °C and for different process corners. Robustness to radiation was simulated using custom model parameters including TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e., 1 Mrad (Si) performed at three different temperatures (room temperature, 100 °C and 200 °C). The maximum drift of the reference voltage VREF depends on the considered temperature and on radiation dose; however, it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage is about 20 ?W at room temperature and only 75 ?W at a high temperature of 200 °C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the used SOI MOSFETs were extracted under different conditions. The evolution of VREF and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The total occupied area including pad-ring is less than 0.09 mm2.

Boufouss, El Hafed; Francis, Laurent A.; Kilchytska, Valeriya; Gerard, Pierre; Simon, Pascal; Flandre, Denis

2013-01-01

337

Ultra-low power high temperature and radiation hard complementary metal-oxide-semiconductor (CMOS) silicon-on-insulator (SOI) voltage reference.  

PubMed

This paper presents an ultra-low power CMOS voltage reference circuit which is robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of -40-200 °C and for different process corners. Robustness to radiation was simulated using custom model parameters including TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e., 1 Mrad (Si) performed at three different temperatures (room temperature, 100 °C and 200 °C). The maximum drift of the reference voltage V(REF) depends on the considered temperature and on radiation dose; however, it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage is about 20 ?W at room temperature and only 75 ?W at a high temperature of 200 °C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the used SOI MOSFETs were extracted under different conditions. The evolution of V(REF) and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The total occupied area including pad-ring is less than 0.09 mm2. PMID:24351635

Boufouss, El Hafed; Francis, Laurent A; Kilchytska, Valeriya; Gérard, Pierre; Simon, Pascal; Flandre, Denis

2013-01-01

338

RAD hard PROM design study  

NASA Technical Reports Server (NTRS)

The results of a preliminary study on the design of a radiation hardened fusible link programmable read-only memory (PROM) are presented. Various fuse technologies and the effects of radiation on MOS integrated circuits are surveyed. A set of design rules allowing the fabrication of a radiation hardened PROM using a Si-gate CMOS process is defined. A preliminary cell layout was completed and the programming concept defined. A block diagram is used to describe the circuit components required for a 4 K design. A design goal data sheet giving target values for the AC, DC, and radiation parameters of the circuit is presented.

1981-01-01

339

THE IMPACT OF BONE MARROW RADIATION DOSE ON ACUTE HEMATOLOGIC TOXICITY IN CERVICAL CANCER: PRINCIPAL COMPONENT ANALYSIS ON HIGH DIMENSIONAL DATA  

PubMed Central

Purpose To study the effects of increasing pelvic bone marrow (BM) radiation dose on acute hematologic toxicity in patients undergoing chemoradiotherapy, using a novel modeling approach to preserve the local spatial dose information. Methods The study includes 37 cervical cancer patients treated with concurrent weekly cisplatin and pelvic radiation therapy. The white blood cell count (WBC) nadir during treatment was used as the indicator of acute hematologic toxicity. Pelvic BM radiation dose distributions were standardized across patients by registering the pelvic BM volumes to a common template followed by dose remapping using deformable image registration, resulting in a dose array. Principal component analysis (PCA) was applied to the dose array and the significant eigenvectors were identified by linear regression on the principal components (PCs). The coefficients for PC regression and significant eigenvectors were represented in 3-D to identify critical BM subregions where dose accumulation is associated with hematologic toxicity. Results We identified five PCs associated with acute hematologic toxicity. PCA regression modeling explained a high proportion of the variation in acute hematologicity (adjusted R2 0.49). Three-dimensional rendering of a linear combination of the significant eigenvectors revealed patterns consistent with anatomical distributions of hematopoietically active BM. Conclusions We have developed a novel approach that preserves spatial dose information to model effects of radiation dose on toxicity, which may be useful in optimizing radiation techniques to avoid critical subregions of normal tissues. Further validation of this approach in a large cohort is ongoing.

Liang, Yun; Messer, Karen; Rose, Brent S.; Lewis, John H.; Jiang, Steve B.; Yashar, Catheryn M.; Mundt, Arno J.; Mell, Loren K.

2009-01-01

340

Vibration effect on hardness measurement  

Microsoft Academic Search

In this paper, the effect of ground vibration on hardness measurement, Rockwell scale C hardness, Vickers scale HV1 hardness and Leeb hardness is studied. The hardness machines were placed on the vibration table. The vibration signal is single frequency sinusoidal wave, which frequency and amplitude of vibration can be controlled. The hardness value at free from vibration state is used

Tassanai Sanponpute; Apichaya Meesaplak

2010-01-01

341

Analysis of radiation hardness and subcell I-V characteristics of GaInP/GaAs/Ge solar cells using electroluminescence measurements  

NASA Astrophysics Data System (ADS)

The voltage degradation of GaInP/GaAs/Ge triple-junction solar cells after exposure to proton irradiation is analyzed using electroluminescence (EL) measurements. It is shown that EL measurements in combination with the reciprocity relationship allow accurate determination of the degradation of the open-circuit voltage (Voc) of each individual subcell. The impact of different proton energies on the voltage degradation of each subcell is analyzed. For solar cells exposed to extremely high radiation levels, a correlation between the degradation of the quantum efficiency of the Ge subcell and its EL properties is presented.

Hoheisel, R.; Messenger, S.; Scheiman, D.; Jenkins, P. P.; Walters, R. J.

2012-02-01

342

Study of Column Grid Array components for space systems  

Microsoft Academic Search

This paper addresses the approaches for using Ceramic Column Grid Arrays (CCGAs) in high reliability (Hi-Rel) space systems. While other grid array packaging exist (i.e. Ball Grid Arrays), the part quality (Military “Class S”) and radiation hardness requirements of Hi-Rel space systems drive the use of hermetic ceramic components. As will be discussed, the issues of thermal mismatch between ceramic

Jonathan Fleisher; Walter Willing

2012-01-01

343

Radiation  

Cancer.gov

DCEG researchers carry out a broad-based research program designed to identify, understand, and quantify the risk of cancer in populations exposed to medical, occupational, or environmental radiation. They study ionizing radiation exposures (e.g., x-rays,

344

Hardness of Quasicrystals  

NASA Astrophysics Data System (ADS)

Vickers hardness measurements have been made at room temperature for four thermodynamically stable quasicrystals. The hardness value of Al-Li-Cu icosahedral quasicrystal is about 500 (kg/mm2) and those of Al-transition metal quasicrystals are commonly around 1000, which is extremely high for aluminum based alloys. Anisotropy in the hardness in Al-Co-Ni decagonal quasicrystal is rather small.

Takeuchi, Shin; Iwanaga, Hiroshi; Shibuya, Tadaharu

1991-03-01

345

Ultrasonic material hardness depth measurement  

DOEpatents

The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part. 12 figs.

Good, M.S.; Schuster, G.J.; Skorpik, J.R.

1997-07-08

346

Ultrasonic material hardness depth measurement  

DOEpatents

The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

Good, Morris S. (Richland, WA); Schuster, George J. (Kennewick, WA); Skorpik, James R. (Kennewick, WA)

1997-01-01

347

Study of radiative leptonic events with hard photons and search for excited charged leptons at ?s = 130-136 GeV  

NASA Astrophysics Data System (ADS)

During the last 1995 data acquisition period at LEP, the DELPHI experiment collected an integrated luminosity of 5.9 pb -1 at centre-of-mass energies of 130 GeV and 136 GeV. Radiative leptonic events ( e, ?, ?) with high energy photons were studied and compared to Standard Model predictions. The data were used to search for charged excited leptons decaying through an electromagnetic transition. No significant signal was found. From the search for pair produced excited leptons, the limits m e ? > 62.5 GeV/c 2, m ? ? > 62.6 GeV/c 2 and m ? ? > 62.2 GeV/c 2 at 95% confidence level were established. For single excited lepton production, upper limits on the ratio {?}/{m l ?} of the coupling of the excited charged lepton to its mass were derived.

Abreu, P.; Adam, W.; Adye, T.; Agasi, E.; Ajinenko, I.; Aleksan, R.; Alekseev, G. D.; Alemany, R.; Allport, P. P.; Almehed, S.; Amaldi, U.; Amato, S.; Andreazza, A.; Andrieux, M. L.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Åsman, B.; Augustin, J.-E.; Augustinus, A.; Baillon, P.; Bambade, P.; Barao, F.; Barate, R.; Barbi, M.; Barbiellini, G.; Bardin, D. Y.; Baroncelli, A.; Barring, O.; Barrio, J. A.; Bartl, W.; Bates, M. J.; Battaglia, M.; Baubillier, M.; Baudot, J.; Becks, K.-H.; Begalli, M.; Beilliere, P.; Belokopytov, Yu.; Benvenuti, A. C.; Berggren, M.; Bertini, D.; Bertrand, D.; Bianchi, F.; Bigi, M.; Bilenky, M. S.; Billoir, P.; Bloch, D.; Blume, M.; Bolognese, T.; Bonesini, M.; Bonivento, W.; Booth, P. S. L.; Bosio, C.; Botner, O.; Boudinov, E.; Bouquet, B.; Bourdarios, C.; Bowcock, T. J. V.; Bozzo, M.; Branchini, P.; Brand, K. D.; Brenke, T.; Brenner, R. A.; Bricman, C.; Brown, R. C. A.; Bruckman, P.; Brunet, J.-M.; Bugge, L.; Buran, T.; Burgsmueller, T.; Buschmann, P.; Buys, A.; Cabrera, S.; Caccia, M.; Calvi, M.; Camacho Rozas, A. J.; Camporesi, T.; Canale, V.; Canepa, M.; Cankocak, K.; Cao, F.; Carena, F.; Carroll, L.; Caso, C.; Castillo Gimenez, M. V.; Cattai, A.; Cavallo, F. R.; Chabaud, V.; Charpentier, Ph.; Chaussard, L.; Chauveau, J.; Checchia, P.; Chelkov, G. A.; Chen, M.; Chierici, R.; Chliapnikov, P.; Chochula, P.; Chorowicz, V.; Cindro, V.; Collins, P.; Contreras, J. L.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Crawley, H. B.; Crennell, D.; Crosetti, G.; Cuevas Maestro, J.; Czellar, S.; Dahl-Jensen, E.; Dahm, J.; Dalmagne, B.; Dam, M.; Damgaard, G.; Dauncey, P. D.; Davenport, M.; da Silva, W.; Defoix, C.; Deghorain, A.; Della Ricca, G.; Delpierre, P.; Demaria, N.; de Angelis, A.; de Boer, W.; de Brabandere, S.; de Clercq, C.; de La Vaissiere, C.; de Lotto, B.; de Min, A.; de Paula, J.; de Saint-Jean, C.; Dijkstra, H.; di Ciaccio, L.; Djama, F.; Dolbeau, J.; Donszelmann, M.; Doroba, K.; Dracos, M.; Drees, J.; Drees, K.-A.; Dris, M.; Durand, J.-D.; Edsall, D.; Ehret, R.; Eigen, G.; Ekelof, T.; Ekspong, G.; Elsing, M.; Engel, J.-P.; Erzen, B.; Espirito Santo, M.; Falk, E.; Fassouliotis, D.; Feindt, M.; Fenyuk, A.; Ferrer, A.; Fichet, S.; Filippas, T. A.; Firestone, A.; Fischer, P.-A.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Formenti, F.; Franek, B.; Frenkiel, P.; Fries, D. C.; Frodesen, A. G.; Fruhwirth, R.; Fulda-Quenzer, F.; Fuster, J.; Galloni, A.; Gamba, D.; Gandelman, M.; Garcia, C.; Garcia, J.; Gaspar, C.; Gasparini, U.; Gavillet, Ph.; Gazis, E. N.; Gele, D.; Gerber, J.-P.; Gibbs, M.; Gokieli, R.; Golob, B.; Gopal, G.; Gorn, L.; Gorski, M.; Gouz, Yu.; Gracco, V.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Gumenyuk, S.; Gunnarsson, P.; Gunther, M.; Guy, J.; Hahn, F.; Hahn, S.; Hajduk, Z.; Hallgren, A.; Hamacher, K.; Hao, W.; Harris, F. J.; Hedberg, V.; Henriques, R.; Hernandez, J. J.; Herquet, P.; Herr, H.; Hessing, T. L.; Higon, E.; Hilke, H. J.; Hill, T. S.; Holmgren, S.-O.; Holt, P. J.; Holthuizen, D.; Hoorelbeke, S.; Houlden, M.; Hrubec, J.; Huet, K.; Hultqvist, K.; Jackson, J. N.; Jacobsson, R.; Jalocha, P.; Janik, R.; Jarlskog, Ch.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Johansson, E. K.; Jonsson, L.; Jonsson, P.; Joram, C.; Juillot, P.; Kaiser, M.; Kapusta, F.; Karafasoulis, K.; Karlsson, M.; Karvelas, E.; Katsanevas, S.; Katsoufis, E. C.; Keranen, R.; Khokhlov, Yu.; Khomenko, B. A.; Khovanski, N. N.; King, B.; Kjaer, N. J.; Klein, H.; Klovning, A.; Kluit, P.; Koene, B.; Kokkinias, P.; Koratzinos, M.; Korcyl, K.; Kostioukhine, V.; Kourkoumelis, C.; Kouznetsov, O.; Kramer, P.-H.; Krammer, M.; Kreuter, C.; Kronkvist, I.; Krumstein, Z.; Krupinski, W.; Kubinec, P.; Kucewicz, W.; Kurvinen, K.; Lacasta, C.; Laktineh, I.; Lamblot, S.; Lamsa, J. W.; Lanceri, L.; Lane, D. W.; Langefld, P.; Lapin, V.; Last, I.; Laugier, J.-P.; Lauhakangas, R.; Ledroit, F.; Lefebure, V.; Legan, C. K.; Leitner, R.; Lemoigne, Y.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Libby, J.; Liko, D.; Lindner, R.; Lipniacka, A.; Lippi, I.; Loerstad, B.; Loken, J. G.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Maehlum, G.; Maio, A.; Malychev, V.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Maron, T.; Martinez-Rivero, C.; Martinez-Vidal, F.; Marti I Garcia, S.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazzucato, M.; Mc Cubbin, M.; Mc Kay, R.; Mc Nulty, R.; Medbo, J.; Merk, M.; Meroni, C.; Meyer, S.; Meyer, W. T.; Miagkov, A.; Michelotto, M.; Migliore, E.; Mirabito, L.; Mitaroff, W. A.; Mjoernmark, U.; Moa, T.; Moeller, R.; Moenig, K.; Monge, M. R.; Morettini, P.; Mueller, H.; Mundim, L. M.; Murray, W. J.; Muryn, B.; Myatt, G.; Naraghi, F.; Navarria, F. L.; Navas, S.; Nawrocki, K.; Negri, P.; Nemecek, S.; Neumann, W.

1996-02-01

348

Metastable decay of DNA components and their compositions - a perspective on the role of reactive electron scattering in radiation damage  

NASA Astrophysics Data System (ADS)

Here we review recent studies on the metastable fragmentation of individual DNA and RNA building blocks and their compositions using matrix assisted laser desorption/ionization mass spectrometry (MALDI). To compare the fragmentation channels of small DNA components with larger compositions we have studied the metastable fragmentation of the deprotonated nucleobases, ribose, ribose-monophoshates, the nucleosides, the nucleoside 5'-monophosphates and selected oligonucleotides. Both previously published and unpublished data are reported. To gain a comprehensive picture of the fragmentation of individual components, metastable fragmentation of native components are in many cases compared to chemically modified components and isotopic labelling is used to unambiguously identify fragments. Furthermore, to shed light on the underlying fragmentation mechanisms we complement the experimental studies with classical dynamics simulations of the fragmentation of selected compounds. For the DNA and RNA components where dissociative electron attachment studies have been conducted we compare these to the metastable fragmentation channels observed here.

Flosadóttir, H. D.; Ómarsson, B.; Bald, I.; Ingólfsson, O.

2012-01-01

349

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system.  

PubMed

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites (Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite (Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species (T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition. PMID:23093097

Tachi, Fuyuki; Osakabe, Masahiro

2012-12-01

350

New BNL 3D-Trench electrode Si detectors for radiation hard detectors for sLHC and for X-ray applications  

NASA Astrophysics Data System (ADS)

A new international-patent-pending (PCT/US2010/52887) detector type, named here as 3D-Trench electrode Si detectors, is proposed in this work. In this new 3D electrode configuration, one or both types of electrodes are etched as trenches deep into the Si (fully penetrating with SOI or supporting wafer, or non-fully penetrating into 50-90% of the thickness), instead of columns as in the conventional ("standard") 3D electrode Si detectors. With trench etched electrodes, the electric field in the new 3D electrode detectors are well defined without low or zero field regions. Except near both surfaces of the detector, the electric field in the concentric type 3D-Trench electrode Si detectors is nearly radial with little or no angular dependence in the circular and hexangular (concentric-type) pixel cell geometries. In the case of parallel plate 3D trench pixels, the field is nearly linear (like the planar 2D electrode detectors), with simple and well-defined boundary conditions. Since each pixel cell in a 3D-Trench electrode detector is isolated from others by highly doped trenches, it is an electrically independent cell. Therefore, an alternative name "Independent Coaxial Detector Array", or ICDA, is assigned to an array of 3D-Trench electrode detectors. The electric field in the detector can be reduced by a factor of nearly 10 with an optimal 3D-Trench configuration where the junction is on the surrounding trench side. The full depletion voltage in this optimal configuration can be up to 7 times less than that of a conventional 3D detector, and even a factor of two less than that of a 2D planar detector with a thickness the same as the electrode spacing in the 3D-Trench electrode detector. In the case of non-fully penetrating trench electrodes, the processing is true one-sided with backside being unprocessed. The charge loss due to the dead space associated with the trenches is insignificant as compared to that due to radiation-induced trapping in sLHC environment. Since the large electrode spacing (up to 500 ?m) can be realized in the 3D-Trench electrode detector due to their advantage of greatly reduced full depletion voltage, detectors with large pixel cells (therefore small dead volume) can be made for applications in photon science (e.g. X-ray).

Li, Zheng

2011-12-01

351

New BNL 3D-Trench Electrode Si Detectors for Radiation Hard Detectors for sLHC and for X-ray Applications  

SciTech Connect

A new international-patent-pending (PCT/US2010/52887) detector type, named here as 3D-Trench electrode Si detectors, is proposed in this work. In this new 3D electrode configuration, one or both types of electrodes are etched as trenches deep into the Si (fully penetrating with SOI or supporting wafer, or non-fully penetrating into 50-90% of the thickness), instead of columns as in the conventional ('standard') 3D electrode Si detectors. With trench etched electrodes, the electric field in the new 3D electrode detectors are well defined without low or zero field regions. Except near both surfaces of the detector, the electric field in the concentric type 3D-Trench electrode Si detectors is nearly radial with little or no angular dependence in the circular and hexangular (concentric-type) pixel cell geometries. In the case of parallel plate 3D trench pixels, the field is nearly linear (like the planar 2D electrode detectors), with simple and well-defined boundary conditions. Since each pixel cell in a 3D-Trench electrode detector is isolated from others by highly doped trenches, it is an electrically independent cell. Therefore, an alternative name 'Independent Coaxial Detector Array', or ICDA, is assigned to an array of 3D-Trench electrode detectors. The electric field in the detector can be reduced by a factor of nearly 10 with an optimal 3D-Trench configuration where the junction is on the surrounding trench side. The full depletion voltage in this optimal configuration can be up to 7 times less than that of a conventional 3D detector, and even a factor of two less than that of a 2D planar detector with a thickness the same as the electrode spacing in the 3D-Trench electrode detector. In the case of non-fully penetrating trench electrodes, the processing is true one-sided with backside being unprocessed. The charge loss due to the dead space associated with the trenches is insignificant as compared to that due to radiation-induced trapping in sLHC environment. Since the large electrode spacing (up to 500 {micro}m) can be realized in the 3D-Trench electrode detector due to their advantage of greatly reduced full depletion voltage, detectors with large pixel cells (therefore small dead volume) can be made for applications in photon science (e.g. X-ray).

Li Z.

2011-05-11

352

Solar Load Inputs for USARIEM Thermal Strain Models and the Solar Radiation-Sensitive Components of the WBGT Index.  

National Technical Information Service (NTIS)

This report describes processes we have implemented to use global pyranometer-based estimates of mean radiant temperature as the common solar load input for the Scenario model, the USARIEM heat strain model, and for the computation of the solar radiation ...

W. T. Matthew W. R. Santee L. G. Berglund

2001-01-01

353

The eCDR, a Radiation-Hard 40/80/160/320 Mbit/s CDR with internal VCO frequency calibration and 195 ps programmable phase resolution in 130 nm CMOS  

NASA Astrophysics Data System (ADS)

A clock and data recovery IP, the eCDR, is presented which is intended to be implemented on the detector front-end ASICs that need to communicate with the GBTX by means of e-links. The programmable CDR accepts data at 40, 80, 160 or 320Mbit/s and generates retimed data as well as 40, 80, 160 and 320MHz clocks that are aligned to the retimed data. Moreover, all the outputs have a programmable phase with a resolution of 195ps. An internal calibration mechanism enables the eCDR to lock on incoming data even without the availability of any form of reference clock. The radiation-hard design, integrated in a 130nm CMOS technology, operates at a supply voltage between 1.2V and 1.5V. The power consumption is between 28.5mW and 34.5mW, depending on the settings. The eCDR can achieve a very low RMS jitter below 10ps.

Tavernier, F.; Francisco, R.; Bonacini, S.; Poltorak, K.; Moreira, P.

2013-12-01

354

Characterization of the role of the RadS/RadR two-component system in the radiation resistance of Deinococcus radiodurans.  

PubMed

Deinococcus radiodurans shows extraordinary tolerance to DNA damage, and exhibits differential gene expression and protein recycling. A putative response regulator, the DRB0091 (RadR) ORF, was identified from a pool of DNA-binding proteins induced in response to gamma radiation in this bacterium. radR is located upstream of drB0090, which encodes a putative sensor histidine kinase (RadS) on the megaplasmid. Deletion of these genes both individually and together resulted in hypersensitivity to DNA-damaging agents and a delayed or altered double-strand break repair. A ?radRradS double mutant and a ?radR single mutant showed nearly identical responses to gamma radiation and UVC. Wild-type RadR and RadS complemented the corresponding mutant strains, but also exhibited significant cross-complementation, albeit at lower doses of gamma radiation. The radS transcript was not detected in the ?radR mutant, suggesting the existence of a radRS operon. Recombinant RadS was autophosphorylated and could catalyse the transfer of ? phosphate from ATP to RadR in vitro. These results indicated the functional interaction of RadS and RadR, and suggested a role for the RadS/RadR two-component system in the radiation resistance of this bacterium. PMID:21737498

Desai, Shruti S; Rajpurohit, Yogendra S; Misra, Hari S; Deobagkar, Dileep N

2011-10-01

355

Resistance of Bacillus subtilis Spore DNA to Lethal Ionizing Radiation Damage Relies Primarily on Spore Core Components and DNA Repair, with Minor Effects of Oxygen Radical Detoxification  

PubMed Central

The roles of various core components, including ?/?/?-type small acid-soluble spore proteins (SASP), dipicolinic acid (DPA), core water content, and DNA repair by apurinic/apyrimidinic (AP) endonucleases or nonhomologous end joining (NHEJ), in Bacillus subtilis spore resistance to different types of ionizing radiation including X rays, protons, and high-energy charged iron ions have been studied. Spores deficient in DNA repair by NHEJ or AP endonucleases, the oxidative stress response, or protection by major ?/?-type SASP, DPA, and decreased core water content were significantly more sensitive to ionizing radiation than wild-type spores, with highest sensitivity to high-energy-charged iron ions. DNA repair via NHEJ and AP endonucleases appears to be the most important mechanism for spore resistance to ionizing radiation, whereas oxygen radical detoxification via the MrgA-mediated oxidative stress response or KatX catalase activity plays only a very minor role. Synergistic radioprotective effects of ?/?-type but not ?-type SASP were also identified, indicating that ?/?-type SASP's binding to spore DNA is important in preventing DNA damage due to reactive oxygen species generated by ionizing radiation.

Raguse, Marina; Reitz, Gunther; Okayasu, Ryuichi; Li, Zuofeng; Klein, Stuart; Setlow, Peter; Nicholson, Wayne L.

2014-01-01

356

An energy-conserving two-temperature model of radiation damage in single-component and binary Lennard-Jones crystals.  

PubMed

Two-temperature models are used to represent the interaction between atoms and free electrons during thermal transients such as radiation damage, laser heating, and cascade simulations. In this paper, we introduce an energy-conserving version of an inhomogeneous finite reservoir two-temperature model using a Langevin thermostat to communicate energy between the electronic and atomic subsystems. This energy-conserving modification allows the inhomogeneous two-temperature model to be used for longer and larger simulations and simulations of small energy phenomena, without introducing nonphysical energy fluctuations that may affect simulation results. We test this model on the annealing of Frenkel defects. We find that Frenkel defect annealing is largely indifferent to the electronic subsystem, unless the electronic subsystem is very tightly coupled to the atomic subsystem. We also consider radiation damage due to local deposition of heat in two idealized systems. We first consider radiation damage in a large face-centered-cubic Lennard-Jones (LJ) single-component crystal that readily recrystallizes. Second, we consider radiation damage in a large binary glass-forming LJ crystal that retains permanent damage. We find that the electronic subsystem parameters can influence the way heat is transported through the system and have a significant impact on the number of defects after the heat deposition event. We also find that the two idealized systems have different responses to the electronic subsystem. The single-component LJ system anneals most rapidly with an intermediate electron-ion coupling and a high electronic thermal conductivity. If sufficiently damaged, the binary glass-forming LJ system retains the least permanent damage with both a high electron-ion coupling and a high electronic thermal conductivity. In general, we find that the presence of an electronic gas can affect short and long term material annealing. PMID:19708752

Phillips, Carolyn L; Crozier, Paul S

2009-08-21

357

Enhancement of the aerosol direct radiative effect by semi-volatile aerosol components: airborne measurements in North-Western Europe  

Microsoft Academic Search

A case study of atmospheric aerosol measurements exploring the impact of the vertical distribution of aerosol chemical composition upon the radiative budget in North-Western Europe is presented. Sub-micron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) on both an airborne platform and a ground-based site at Cabauw in the Netherlands. The examined period in May 2008

W. T. Morgan; J. D. Allan; K. N. Bower; M. Esselborn; B. Harris; J. S. Henzing; E. J. Highwood; A. Kiendler-Scharr; G. R. McMeeking; A. A. Mensah; M. J. Northway; S. Osborne; P. I. Williams; R. Krejci; H. Coe

2010-01-01

358

Irradiate-anneal screening of total dose effects in semiconductor devices. [radiation hardening of spacecraft components of Mariner spacecraft  

NASA Technical Reports Server (NTRS)

An extensive investigation of irradiate-anneal (IRAN) screening against total dose radiation effects was carried out as part of a program to harden the Mariner Jupiter/Saturn 1977 (MJS'77) spacecraft to survive the Jupiter radiation belts. The method consists of irradiating semiconductor devices with Cobalt-60 to a suitable total dose under representative bias conditions and of separating the parts in the undesired tail of the distribution from the bulk of the parts by means of a predetermined acceptance limit. The acceptable devices are then restored close to their preirradiation condition by annealing them at an elevated temperature. IRAN was used when lot screen methods were impracticable due to lack of time, and when members of a lot showed a diversity of radiation response. The feasibility of the technique was determined by testing of a number of types of linear bipolar integrated circuits, analog switches, n-channel JFETS and bipolar transistors. Based on the results of these experiments a number of device types were selected for IRAN of flight parts in the MJS'77 spacecraft systems. The part types, screening doses, acceptance criteria, number of parts tested and rejected as well as the program steps are detailed.

Stanley, A. G.; Price, W. E.

1976-01-01

359

Radiation  

NASA Video Gallery

Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

360

Radiators  

SciTech Connect

A heat-exchange radiator is connected to a fluid flow circuit by a connector which provides one member of an interengageable spigot and socket pair for push-fit, fluid-tight, engagement between the connector and the radiator, with latching formations at least one of which is resilient. Preferably the connector carries the spigot which tapers and engages with a socket of corresponding shape, the spigot carrying an O-ring seal and either latching fingers or a resilient latching circlip.

Webster, D. M.

1985-07-30

361

A Comparison of Out-of-Field Dose and Its Constituent Components for Intensity-Modulated Radiation Therapy Versus Conformal Radiation Therapy: Implications for Carcinogenesis  

SciTech Connect

Purpose: To investigate differences in scatter and leakage between 6-MV intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3DCRT); to describe the relative contributions of internal patient scatter, collimator scatter, and head leakage; and to discuss implications for second cancer induction. Methods and Materials: Dose was measured at increasing distances from the field edge in a water bath with a sloping wall (1) under full scatter conditions, (2) with the field edge abutting but outside the bath to prevent internal (water) scatter, and (3) with the beam aperture plugged to reflect leakage only. Results: Internal patient scatter from IMRT is 11% lower than 3DCRT, but collimator scatter and head leakage are five and three times higher, respectively. Ultimately, total scattered dose is 80% higher with IMRT; however this difference is small in absolute terms, being 0.14% of prescribed dose. Secondary dose from 3DCRT is mostly due to internal patient scatter, which contributes 70% of the total and predominates until 25 cm from the field edge. For IMRT, however, machine scatter/leakage is the dominant source, contributing 65% of the secondary dose. Internal scatter predominates for just the first 10 cm from field edge, collimator scatter for the next 10 cm, and head leakage thereafter. Conclusions: Out-of-field dose is 80% higher with IMRT, but differences are tiny in absolute terms. Reductions in internal patient scatter with IMRT are outweighed by increased machine scatter and leakage, at least for small fields. Reductions from IMRT in dose to tissues within the portals and in internal scatter, which predominates close to the field edge, means that calculations based solely on dose to distant tissues may overestimate carcinogenic risks.

Ruben, Jeremy D., E-mail: jeremy.ruben@wbrc.org.au [William Buckland Radiotherapy Centre, The Alfred, Melbourne (Australia); Monash University, Melbourne (Australia); Lancaster, Craig M.; Jones, Phillip; Smith, Ryan L. [William Buckland Radiotherapy Centre, The Alfred, Melbourne (Australia)

2011-12-01

362

AMORPHOUS ALLOY SURFACE COATINGS FOR HARD CHROMIUM REPLACEMENT - PHASE I  

EPA Science Inventory

Hard chromium coatings (0.25 to10 mil thick) are used extensively for imparting wear and erosion resistance to components in both industrial and military applications. The most common means of depositing hard chromium has been through the use of chromic acid baths containing ...

363

Radiation-hypersensitive cancer patients do not manifest protein expression abnormalities in components of the nonhomologous end-joining (NHEJ) pathway  

PubMed Central

Radiation therapy (RT) is utilised for the treatment of around half of all oncology patients during the course of their illness. Despite great clinical progress in the rational deployment of RT, the underlying molecular basis for its efficacy and toxicity are currently imperfectly understood. In this study, we took a biochemical approach to evaluate the potential role of key ionising radiation repair proteins in the treatment outcomes of patients with severe acute or late RT side effects. Lymphoblastoid cell lines were established from blood samples from 36 radiosensitive cases and a number of controls (the latter had had RT but did not develop significant toxicity). The expression level and migration of key proteins from the nonhomologous end-joining (NHEJ) pathway was evaluated by Western blot analysis on cases and controls. We did not observe any abnormalities in expression level or migration pattern of the following NHEJ proteins in radiosensitive cancer cases: Ku70, Ku80, XRCC4, DNA Ligase IV. These important negative results provide evidence that mutations that affect protein expression of these NHEJ components are unlikely to underlie clinical radiation sensitivity.

Leong, T; Chao, M; Bassal, S; McKay, M

2003-01-01

364

Spectral Characteristics of the Hard X Ray Emission from a Plasma Focus Device  

SciTech Connect

An indirect method to infer the spectra, based on the measurement of the beam intensity transmission through different metallic samples, is described in this communication. A Plasma Focus device (5.67 kJ, 30 kV) was studied as a pulsed hard x ray source, operated with deuterium at a filling pressure in the range of 3 to 5 mbar. Relevant spectral components belonging to the 50 - 150 keV range with a single maximum located in the 75 - 85 keV region were obtained for the radiation coming out of the Plasma Focus chamber, which is made of stainless steel.

Raspa, V.; Sigaut, L.; Moreno, C. [Laboratorio Plasma Focus - PLADEMA - Instituto de Fisica del Plasma - Departamento de Fisica, FCEyN - Universidad de Buenos Aires (Argentina); Vieytes, R. [Laboratorio Plasma Focus - PLADEMA - Instituto de Fisica del Plasma - Departamento de Fisica, FCEyN - Universidad de Buenos Aires (Argentina); Escuela Superior Tecnica Manuel N. Savio, EST (Argentina); Clausse, A. [Universidad Nacional del Centro, PLADEMA-CNEA - CONICET (Argentina)

2006-12-04

365

The Effect of Total Ionizing Dose Degradation of Laptop Hard Disks  

NASA Technical Reports Server (NTRS)

A series of total ionizing dose (TID) measurements were performed on commercial hard drives to explore the possible uses of the devices for the high radiation mission, and to help the understanding of the reliability of current hard drive technology. Three different models from three major manufacturers were tested with the aid of a commercial hard drive test system.

Nguyen, D. N.; Guertin, S. M.; Patterson, J. D.

2005-01-01

366

Diffractive hard scattering  

SciTech Connect

I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

1986-03-01

367

Work Hard. Be Nice  

ERIC Educational Resources Information Center

In 1994, fresh from a two-year stint with Teach for America, Mike Feinberg and Dave Levin inaugurated the Knowledge Is Power Program (KIPP) in Houston with an enrollment of 49 5th graders. By this Fall, 75 KIPP schools will be up and running, setting children from poor and minority families on a path to college through a combination of hard work,…

Mathews, Jay

2009-01-01

368

Overview: Hard Rock Penetration  

Microsoft Academic Search

The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry\\/DOE cost shared projects of the Geothermal Drilling organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure

Dunn

1992-01-01

369

Overview - Hard Rock Penetration  

Microsoft Academic Search

The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry\\/DOE cost shared projects of the Geothermal Drilling Organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure

Dunn; James C

1992-01-01

370

CSI: Hard Drive  

ERIC Educational Resources Information Center

Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

Sturgeon, Julie

2008-01-01

371

Budgeting in Hard Times.  

ERIC Educational Resources Information Center

Interviews with school board members and administrators produced a list of suggestions for balancing a budget in hard times. Among these are changing calendars and schedules to reduce heating and cooling costs; sharing personnel; rescheduling some extracurricular activities; and forming cooperative agreements with other districts. (MLF)

Parrino, Frank M.

2003-01-01

372

Running in Hard Times  

ERIC Educational Resources Information Center

Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

Berry, John N., III

2009-01-01

373

Hard Sphere Gas Model  

NSDL National Science Digital Library

The Ejs Hard Sphere Gas model displays a three-dimensional (ideal) gas made out of hard disks. Particles are initialized with a random speed and in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Sphere Gas model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardShpereGas.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for statistical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

374

Investigations of radiation induced transient absorption and emission in the quartz-polymer optical fiber  

Microsoft Academic Search

The radiation hardness properties of fused-silica core and polymer-clad optical fibers (OF) are studied using intense bremsstrahlung gamma sources in situ. The post-irradiation degree of recovery in minute time scales as a function of total integrated dose is used for separation of stable and unstable attenuation components. The gamma induced emission of OF are measured and analyzed

M. Ashurov; M. Baydjanov; E. Gasanov; N. Ivanov; I. Rustamov; A. Safarov; R. Suleymanov; B. Yuldashev

2005-01-01

375

Radiation Is an Important Component of Multimodality Therapy for Pediatric Non-Pineal Supratentorial Primitive Neuroectodermal Tumors  

SciTech Connect

Purpose: To review a historical cohort of pediatric patients with supratentorial primitive neuroectodermal tumors (sPNET), to clarify the role of radiation in the treatment of these tumors. Patients and Methods: Fifteen children aged <18 years with non-pineal sPNETs diagnosed between 1992 and 2006 were identified. Initial therapy consisted of surgical resection and chemotherapy in all patients and up-front radiotherapy (RT) in 5 patients. Five patients had RT at the time of progression, and 5 received no RT whatever. Kaplan-Meier estimates of overall survival were then calculated. Results: The median follow-up from diagnosis for all patients was 31 months (range, 0.5-165 months) and for surviving patients was 49 months (range, 10-165). Of the 5 patients who received up-front RT, all were alive without evidence of disease at a median follow-up of 50 months (range, 25-165 months). Only 5 of the 10 patients who did not receive up-front RT were alive at last follow-up. There was a statistically significant difference in overall survival between the patient group that received up-front RT and the group that did not (p = 0.048). In addition, we found a trend toward a statistically significant improvement in overall survival for those patients who received gross total resections (p = 0.10). Conclusions: Up-front RT and gross total resection may confer a survival benefit in patients with sPNET. Local failure was the dominant pattern of recurrence. Efforts should be made to determine patients most likely to have local failure exclusively or as a first recurrence, in order to delay or eliminate craniospinal irradiation.

McBride, Sean M.; Daganzo, Sally M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Banerjee, Anuradha [Department of Pediatrics, University of California-San Francisco, San Francisco, CA (United States); Gupta, Nalin; Lamborn, Kathleen R.; Prados, Michael D.; Berger, Mitchel S. [Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States); Wara, William M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Haas-Kogan, Daphne A. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States)], E-mail: dhaaskogan@radonc.ucsf.edu

2008-12-01

376

The hardness assurance wafer probe - HAWP  

NASA Astrophysics Data System (ADS)

Complete radiation sensitivity assessments of integrated circuits can now be performed at the wafer level using a new system, the Hardness Assurance Wafer Probe, HAWP. This system utilizes a pulsed Nd:YAG infrared laser impinging on the backside of the wafer to evaluate the transient behavior of the circuits. A low energy X ray source collimated to a single die site actually performs total dose irradiations. Finally, special electrical measurements are used to enable a prediction of the neutron sensitivity of bipolar devices. The HAWP System is described and correlations of wafer probe results to conventional radiation tests for a digital part type are provided.

King, E. E.; Tettemer, G. L.; Linderman, P. B.; Micheletti, P. E.

1983-12-01

377

ATP-type DNA ligase requires other proteins for its activity in vitro and its operon components for radiation resistance in Deinococcus radiodurans in vivo.  

PubMed

A multiprotein DNA processing complex isolated from Deinococcus radiodurans contains the DNA repair protein PprA, an ATP-type DNA repair ligase (LigB) encoded by the drB0100 gene, and protein kinase activity. An ATP-dependent DNA end-joining activity was detected in the complex. To elucidate the function of the drB0100 gene, we generated the deletion mutant for the DR_B0100 ORF. The mutant exhibited a nearly 2-log cycle reduction in growth rate when exposed to a 10,000 Gray dose of ?-radiation, and a significant loss in mitomycin C and methylmethane sulphonate tolerance as compared with wild type. Functional complementation of these phenotypes required the wild-type copy of drB0100 along with other genes such as drb0099 and drb0098, organized downstream in the operon. The in vitro DNA ligase activity of LigB was stimulated severalfold by PprA in the presence of the recombinant DRB0098 protein. However, this activity did not improve when PprA was substituted with purified DRB0099 protein or when DRB0098 protein was substituted with the DRB0099 protein in the presence of PprA in solution. These results suggest that PprA and DRB0098 protein are required for LigB function. Furthermore, they also suggest that the LigB operon components contribute to radiation resistance and double-strand break (DSB) repair in D. radiodurans. PMID:20921990

Kota, Swathi; Kamble, Vidya A; Rajpurohit, Yogendra S; Misra, Hari S

2010-10-01

378

Hadron component of cosmic radiation at atmospheric depth 800 g/cm(2) in Energy Range 70 to 700 GeV  

NASA Astrophysics Data System (ADS)

A spark spectrometer was developed for registry of cosmic radiation hardons. The study of this instrument in the particle beams of the Serpukhovo accelerator made it possible to reduce the systematic errors in the measurement of cosmic radiation hardons to a minimum. Existing methods for studying the hadron component; the characteristics of interaction between pions and protons and spark spectrometer matter obtained using the Serpukhovo accelerator; the parameters of hadron showers in the spark spectrometer, used in studying hadron fluxes in cosmic rays; the ratios of fluxes of pions and protons, the absolute intensities of the flux of neutrons and the total hadron flux at an elevation of 2,000 m above sea level; and the measurement data are discussed. The integral intensities of fluxes of neutrons and hadrons in the energy range 240 GeV were determined. It is found that there is a systematic increase in the eta/P ratio of fluxes in the energy range 120 to 330 GeV.

Vasilyev, P. S.

1985-11-01

379

Estimates of power deposited via cesium/barium beta and gamma radiation captured in components of a Hanford cesium chloride capsule and by components of overpacked capsules placed in an interim dry storage facility  

SciTech Connect

The deposition of power in Hanford cesium chloride capsules and in the components of design concepts for overpacking and interim storage were determined as requested (Randklev, 1996a). The power deposition results from the selective capture of gamma and beta radiation coming from the decay of the 137CS isotope in the CsCl contained in the capsules. The following three cases were analyzed: (a) a single CsCl capsule, (b) an overpack containing eight CsCl capsules, and (c) an infinite square array of such overpacks as placed in tubes of a interim dry storage facility. The power deposition was expressed as watts per gram for each of the respective physical design components in these three cases. Per the analyses request and guidance (Randklev 1996a), the primary analysis objective was to characterize, for each case, the power deposition across the radial cross-section at the expected axial position of maximum deposition. As requested, this primary part of the analysis work was done using choices for component dimension and material properties that would reasonably characterize the maximum deposition profile across the salt (CsCl) and the inner capsule barrier of the double walled metal capsule system used to construct the Hanford capsules. The secondary objective was to further evaluate the deposition behavior relative to the influence of axial position. The guidance (Randklev 1996a) also requested 1797 an analysis case that involved a lag-storage pit in a hot-cell, in which a cylindrical metal basket from a transportation cask would be used to position several capsules in the lag-storage pit. Although the basic model for the lag storage concept evaluation was essentially completed by the end of FY-96, the analysis was not run because of the need to prioritize and limit the work scope due to funding limitations for FY-97. The specific purpose for performing the subject set of analyses (Randklev 1996a) is to obtain power deposition values (i.e., per the decay of T37cs) that can then be used as input into an analysis of the heat transfer (i.e., component temperature) response (Randklev 1996d) for such cases. The overall objective is to support the TWRS program evaluations of capsule disposal options, which could be implemented if, and when the DOE changes their current designation as `by-product` material, to `waste` material. It was found that the Hanford reference literature concerning the capsules does contain a few reports on previous Monte Carlo code determinations of the power deposition values for assemblages involving the Hanford CsCl capsules. However, in one case (Campbell, 1981) the results are now believed to be seriously in error, and the other two reported analyses (Sasmor, et al, 1988; Midgett, 1995) involve capsule + other components in assemblages that differed significantly from the subject concepts addressed in this present analysis.

Roetman, V.E., Westinghouse Hanford

1996-12-23

380

Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions  

PubMed Central

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

Sonntag, Robert; Reinders, Jorn; Rieger, Johannes S.; Heitzmann, Daniel W. W.; Kretzer, J. Philippe

2013-01-01

381

Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.  

PubMed

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

2013-01-01

382

Hard Metal Interstitial Lung Disease  

Microsoft Academic Search

Hard metal lung disease is an unusual disease which can occur in individuals exposed to hard metals. Clinically, the condition resembles hypersensitivity pneumonitis depending mainly on individual susceptibility, which eventually progresses to pulmonary fibrosis. We present two patients with pulmonary fibrosis, who were actually diagnosed after an exhaustive anamnesis and examination of the tissue by scanning microscope to discard hard

M. Ángeles Montero; Javier de Gracia; Ferràn Morell

2010-01-01

383

Hard and soft acids and bases: structure and process.  

PubMed

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases. PMID:22668421

Reed, James L

2012-07-01

384

A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries  

NASA Astrophysics Data System (ADS)

We predict a thin diffuse component of the Galactic ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. This scattered component has the same scale height as that of the gaseous disk (~80 pc) and is therefore thinner than the GRXE of stellar origin (scale height ~130 pc). The morphology of the scattered component is furthermore expected to trace the clumpy molecular and HI clouds. We calculate this contribution to the GRXE from known Galactic XBs assuming that they are all persistent. The known XBs sample is incomplete, however, because it is flux limited and spans the lifetime of X-ray astronomy (~50 years), which is very short compared with the characteristic time of 1000-10 000 years that would have contributed to the diffuse emission observed today due to time delays. We therefore also use a simulated sample of sources, to estimate the diffuse emission we should expect in an optimistic case assuming that the X-ray luminosity of our Galaxy is on average similar to that of other galaxies. In the calculations we also take into account the enhancement of the total scattering cross-section due to coherence effects in the elastic scattering from multi-electron atoms and molecules. This scattered emission can be distinguished from the contribution of low X-ray luminosity stars by the presence of narrow fluorescent K-? lines of Fe, Si, and other abundant elements present in the interstellar medium and by directly resolving the contribution of low X-ray luminosity stars. We find that within 1° latitude of the Galactic plane the scattered emission contributes on average 10 - 30% of the GRXE flux in the case of known sources and over 50% in the case of simulated sources. In the latter case, the scattered component is found to even dominate the stellar emission in certain parts of the Galactic plane. X-rays with energies ?1 keV from XBs should also penetrate deep inside the HI and molecular clouds, where they are absorbed and heat the interstellar medium. We find that this heating rate dominates the heating by cosmic rays (assuming a solar neighborhood energy density) in a considerable part of the Galaxy. Appendices are available in electronic form at http://www.aanda.org

Molaro, Margherita; Khatri, Rishi; Sunyaev, Rashid A.

2014-04-01

385

Survival of Hard-on-Hard Bearings in Total Hip Arthroplasty: A Systematic Review  

Microsoft Academic Search

Background  Improvements in prosthetic materials, designs, and implant fixation for THA have led to bearing surface wear being the limitation\\u000a of this technology. Hard-on-hard bearings promise decreased wear rates and increased survival. However, there may be different\\u000a survival rates based on bearing materials, manufacturing technologies, and femoral component designs. Additionally, survival\\u000a rate variability may be based on study design.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We determined

Michael G. Zywiel; Siraj A. Sayeed; Aaron J. Johnson; Thomas P. Schmalzried; Michael A. Mont

2011-01-01

386

Hard noncommutative loops resummation.  

PubMed

The noncommutative version of the Euclidean g2phi4 theory is considered. By using Wilsonian flow equations the ultraviolet renormalizability can be proved to all orders in perturbation theory. On the other hand, the infrared sector cannot be treated perturbatively and requires a resummation of the leading divergences in the two-point function. This is analogous to what is done in the hard thermal loops resummation of finite temperature field theory. Next-to-leading order corrections to the self-energy are computed, resulting in O(g3) contributions in the massless case, and O(g6logg2) in the massive one. PMID:11863880

Griguolo, Luca; Pietroni, Massimo

2002-02-18

387

Low power hard-rad electronics for particle detection in space plasmas  

NASA Astrophysics Data System (ADS)

Particle detection in highly-radiative environment is one of the experimental challenges of planetary exploration. We present the design and performances of a compact electron detector that takes advantage of the development of a hard-rad and ultra low-power front-end electronics. The Applied Specific Integrated Circuit (ASIC) consists of charge sensitive amplifiers and discriminators allowing a 4.5MHz periodic counting rate. The 16-channels ASIC only takes 30mW of power which is the power budget of single channel hybrid components with similar performances. Each channel can be independently configured in order to adjust the detection threshold of the discriminator. An internal test circuitry is used to monitor the behavior of the electronics. This component, that has been tested at high ionizing doses, is immune to Single Event Latchups up to at least 80 MeV.cm^2/mg and it will fly on the Solar Orbiter ESA mission.

Berthomier, Matthieu; Techer, Jean-Denis

2014-05-01

388

Flank wear prediction of ceramic tools in hard turning  

Microsoft Academic Search

Due to technical and economical factors, hard turning is competing successfully with the grinding process in the industries.\\u000a Many practical applications require components to be hardened in order to improve their wear behavior. Higher productivity\\u000a and good surface quality are the requirements of the modern industries. However, tool wear is the major problem in hard turning.\\u000a The tool wear models,

Dilbag Singh; P. Venkateswara Rao

2010-01-01

389

Effects of differences in hardness measurement procedures on the traceability chain and calibration process  

NASA Astrophysics Data System (ADS)

Establishment of traceability in hardness measurement is still under discussion at the ISO TC 164 SC 3 subcommittee on hardness testing. Two paths for establishing traceability are proposed for the Rockwell hardness measurement in ISO 6508-1. One way is taking a route to SI units through direct calibration of machine components, and the other way is taking a route to a hardness measurement standard through indirect calibration of machine performance. In addition to this, the difference in hardness measurement procedures between Rockwell and Brinell/Vickers hardness causes further confusion in establishing a traceability chain and an uncertainty evaluation process. This confusion is partly caused by the characteristics of hardness value, i.e. a procedure-dependent property. In this paper, methods used for the establishment of traceability for Rockwell, Brinell and Vickers hardness measurements are discussed based on the concept defined in the VIM.

Tak, Nae Hyung; Moo Lee, Hae; Bahng, Gunwoong

2013-06-01

390

Hard and soft spectral states of ULXs  

NASA Astrophysics Data System (ADS)

I discuss some differences between the observed spectral states of ultraluminous X-ray sources (ULXs) and the canonical scheme of spectral states defined in Galactic black holes. The standard interpretation of ULXs with a curved spectrum, or a moderately steep power-law with soft excess and high-energy downturn, is that they are an extension of the very high state, up to luminosities {? 1}-3 L_Edd. Two competing models are Comptonization in a warm corona, and slim disk; I suggest bulk motion Comptonization in the radiatively-driven outflow as another possibility. The interpretation of ULXs with a hard power-law spectrum is more problematic. Some of them remain in that state over a large range of luminosities; others switch directly to a curved state without going through a canonical high/soft state. I suggest that those ULXs are in a high/hard state not seen in Galactic black holes; that state may overlap with the low/hard state at lower accretion rates, and extend all the way to Eddington accretion rates. If some black holes can reach Eddington accretion rates without switching to a standard-disk-dominated state, it is also possible that they never quench their steady jets.

Soria, R.

2011-05-01

391

Generation of hard quanta in the cross-grooved resonator of a free electron laser  

SciTech Connect

A new approach to the generation of powerful tunable hard radiation in the cross-grooved resonator (CGR) of a free electron laser is proposed and discussed. Gamma quanta are generated upon backward Compton scattering of intracavity radiation by the electron beam of a free electron laser with a CGR. The use of a CGR considerably increases the power of intracavity radiation, and hence the power of gamma radiation, and also solves the problem of extraction of hard radiation by eliminating the losses in the depth of the cavity mirror, which were inevitable earlier. (lasers)

Baryshnikov, F F; Perebeinos, V V; Cheburkin, N V [State Unitary Enterprise, V.K. Orlov Granat Design Bureau, Moscow (Russian Federation)

2002-06-30

392

LASERS: Generation of hard quanta in the cross-grooved resonator of a free electron laser  

NASA Astrophysics Data System (ADS)

A new approach to the generation of powerful tunable hard radiation in the cross-grooved resonator (CGR) of a free electron laser is proposed and discussed. Gamma quanta are generated upon backward Compton scattering of intracavity radiation by the electron beam of a free electron laser with a CGR. The use of a CGR considerably increases the power of intracavity radiation, and hence the power of gamma radiation, and also solves the problem of extraction of hard radiation by eliminating the losses in the depth of the cavity mirror, which were inevitable earlier.

Baryshnikov, F. F.; Perebeinos, V. V.; Cheburkin, N. V.

2002-06-01

393

Total-Dose Hardness Assurance for Low Earth Orbit  

Microsoft Academic Search

The Low Earth Orbit radiation environment has two significant characteristics that make laboratory simulation exposures difficult: (1) a low dose rate and (2) many cycles of low dose accumulation followed by dose-free annealing. Hardness assurance considerations for this environment are discussed and related to data from the testing of Advanced Low Power Schottky and High-speed CMOS devices.

R. H. Maurer; J. J. Suter

1987-01-01

394

Analytical Representation of Luminous Solar Radiation Components. Clear Sky Conditions Representations Analytiques des Composantes du Rayonnement Lumineux Solaire. Conditions de Ciel Serein.  

National Technical Information Service (NTIS)

Various components of luminous solar rays under clear sky conditions were analyzed. Parameters characterizing atmospheric transparence were determined. The direct luminosity component is described mathematically and the luminous efficiency of direct solar...

R. Dogniaux

1974-01-01

395

Imaging hard X-ray telescope developments in United States and Europe  

NASA Astrophysics Data System (ADS)

The hard X-ray (20 keV up to 1 MeV) energy band is a good window for us to learn the high energy radiation processes in astrophysics. The imaging hard X-ray telescopes provide better resolution and sensitivity for studying hard X-ray astrophysics. In this paper, the recent years developments of imaging hard X-ray telescopes in United States and Europe are introduced, including 1) EXITE2 - a phoswich imaging hard X-ray telescope designed and operated by Harvard-Smithsonian Center for Astrophysics (CfA); 2) EXIST - an imaging hard X-ray all-sky survey, which will be carried by ULDB (EXIST-LITE) or mounted on international space station (EXIST-ISS) in the year of 2010 and 3) HERO - a newly developed hard X-ray optics instrument, built by NASA/MSFC.

Zhou, Yi

396

Qualifying drillstring components for deep drilling  

Microsoft Academic Search

Deep, hard or directional drilling imposes extraordinary stresses on drill string components. Because of the additional economic risks of deep drilling, the use of drill string components should be based upon their compliance with API or user acceptance standards. Inspection procedures which provide the highest probability of finding and eliminating unacceptable components should also be employed. Often, too much reliance

T. H. Hill; R. C. Money; C. R. Palmer

1984-01-01

397

Qualifying Drillstring Components for Deep Drilling  

Microsoft Academic Search

Deep, hard, or directional drilling imposes extraordinary stresses on drillstring components. Because of the additional economic risks of deep drilling, the inspection and acceptance of drillstring components should be based on their compliance with API and user standards. Inspection procedures that provide the highest probability of finding and eliminating unacceptable components should be used. Often, too much reliance is placed

T. H. Hill; R. C. Money; C. R. Palmer

1985-01-01

398

Comparative study of carp otolith hardness: lapillus and asteriscus.  

PubMed

Otoliths are calcium carbonate biominerals in the inner ear of vertebrates; they play a role in balance, movement, and sound perception. Two types of otoliths in freshwater carp are investigated using nano- and micro-indentation: asteriscus and lapillus. The hardness, modulus, and creep of asteriscus (vaterite crystals) and lapillus (aragonite crystals) are compared. The hardness and modulus of lapillus are higher than those of asteriscus both in nano- and micro-testing, which is attributed to the different crystal polymorphs. Both materials exhibit a certain degree of creep, which indicates some time dependence of the mechanical behavior and is attributed to the organic components. The nano-indentation hardnesses are higher than micro-hardnesses for both otoliths, a direct result of the scale dependence of strength; fewer flaws are encountered by the nano than by the microindenter. PMID:23498208

Ren, Dongni; Meyers, Marc André; Zhou, Bo; Feng, Qingling

2013-05-01

399

Crystalline assembly of hard polyhedra via directional entropic forces  

NASA Astrophysics Data System (ADS)

Entropic forces are effective forces that result from a system's statistical tendency to increase its entropy. Hard rods and disks spontaneously align and can assemble into layers and columns if those structures increase the configurational space available to the particles. Hard spheres, cubes and even tetrahedra order for the same reason. Here we extend those findings by showing that hard polyhedra can self-assemble into a variety of complex phases, most of them never before reported in systems of single-component hard particles. The role of shape and directional entropic forces in stabilizing these structures will be discussed. Our results suggest new possibilities for self-assembling complex target structures from colloidal building blocks. [4pt] [1] Damasceno, PF; Engel, M; Glotzer, SC. arXiv:1109.1323v1

Damasceno, Pablo F.; Engel, Michael; Glotzer, Sharon C.

2012-02-01

400

The Space Radiation Environment as it Relates to Electronic System Performance: Or Why Not to Fly Commercial Electronic Components in Space  

NASA Technical Reports Server (NTRS)

This viewgraph presentation offers an overview of the space radiation environment, primarily in near-Earth environments such as Low Earth Orbit (LEO). The presentation describes the Halloween solar event of 2003 as an example of how solar activity can affect spacecraft electronic systems. The lunar radiation environment is also briefly summarized.

Barth, Janet L.; Xapsos, Michael A.; LaBel, Kenneth A.; Polvey, Christian

2005-01-01

401

Determining the X-ray Contribution of Hard State X-ray Binary Jets: New Results from Simultaneous Broadband Spectral Fitting  

NASA Astrophysics Data System (ADS)

The hard state of X-ray binaries (XRBs) is associated with a hard power law spectrum in the X-ray band, generally modeled via inverse Comptonization of thermal disk photons by a corona. This state is also associated with compact, continuous jets whose radio synchrotron emission is correlated with the hard X-rays. The exact nature of this relationship is still under debate, and an effective way of addressing this question is to model the entire broadband spectrum self-consistently. Depending on the location of the optically thick-to-thin break and the emitting particle distribution, jet synchrotron radiation can contribute significantly to the X-ray band, in addition to synchrotron self-Compton emission from near the base of the jets. We have imported our jet models into X-ray data analysis software to allow the simultaneous fitting of radio and IR data along with the traditional X-ray bands. We present the fits to broadband simultaneous data sets, including X-ray data from the Rossi XTE mission, for several XRBs, including Cyg X-1 and GX 339-4. Our best results show contributions from both direct synchrotron radiation as well as a strong SSC component. With the addition of line and reflection features, jet models provide as good a description of the X-ray data as thermal Comptonization models, while also addressing the radio/IR components. S.M. is supported by an NSF Astronomy & Astrophysics postdoctoral fellowship.

Markoff, S.; Nowak, M. A.; Wilms, J.

2004-08-01

402

Multidensity integral-equation theory for short diblock hard-sphere-sticky-hard-sphere chains.  

PubMed

The multidensity Ornstein-Zernike integral equation theory is applied to study a simple model of hard sphere/sticky hard sphere diblock chains. The multidensity integral equation formalism has been successfully used to model the equilibrium structure and thermodynamic properties of homonuclear chains and shorter dimer fluids; to our knowledge it has not been applied to model diblock chains. In this work, a diblock chain fluids is represented by an m-component equal molar mixture of hard spheres with species 1,2,...,mh and sticky hard spheres with species mh+1,mh+2,...,m. Each spherical particle has two attractive sites A and B except species 1 and m, which have only one site per particle. In the limit of complete association, this mixture yields a system of monodisperse diblock chains. A general solution of this model is obtained in the Percus-Yevick, Polymer Percus-Yevick and ideal chain approximations. Both structural and thermodynamic properties of this model are investigated. From this study, a microphase separation is predicted for relatively short diblock symmetric and asymmetric chains. This microphase separation is enhanced at lower temperature and higher density. When chain length increases, the phase transition changes from a microphase level to a macrophase level. The size of microdomain structure is found to be dependent on total chain length, relative ratio of block lengths, temperature, and density. PMID:20481746

Wu, Ning; Chiew, Y C

2010-04-01

403

Ultraviolet radiation diagnostics of the flare transient layer  

NASA Astrophysics Data System (ADS)

The correlation between the pulsed and smooth components of ultraviolet radiation and hard X-rays from solar flares has been interpreted on the basis of the time behavior of the energy flux penetrating from the magnetic field reconnection region to the boundary of the heated region. It has been shown that the time behavior of the primary flare energy flux is easily reconstructed from the time profile of the intensity of hard X-rays, and the time profile of the intensity of ultraviolet radiation represents the release of the flare energy in the flare transient layer. The smooth or pulsed component of the ultraviolet radiation depends on the form of the primary energy release. Information on the dynamics of the heating process and the formation and equalization of the gas pressure in the flare transient layer has been obtained from the observed temperature dependence of the emission measure. The described scheme explains the set of flare phenomena and the correlation between hard X-rays with pulsed ultraviolet bursts.

Shmeleva, O. P.; Krasil'Nikova, L. L.; Sukhova, N. S.

2010-08-01

404

The Effect of Radiation Dosages and UV\\/EB Radiation on the Properties of Nanocomposite Coatings  

Microsoft Academic Search

The aim of this study was to compare the effects of ultraviolet (UV) and electron beam (EB) radiation on the properties of cured nanocomposite coatings. Surface hardness increased with increasing radiation dosages (number of passes) for all samples. This was due to the increase in crosslinking with increasing radiation dosages. Pendulum hardness, gel content, and thumb twist results were analyzed

Nik Ghazali Nik Salleh; Mohd Firdaus Yhaya; Azman Hassan; Aznizam Abu Bakar; Munirah Mokhtar

2009-01-01

405

Residual stress control and design of next-generation ultra-hard gear steels  

NASA Astrophysics Data System (ADS)

In high power density transmission systems, Ni-Co secondary hardening steels have shown great potential for next-generation gear applications due to their excellent strength, toughness and superior fatigue performance. Study of residual stress generation and evolution in Ferrium C61 and C67 gear steels revealed that shot peening and laser peening processes effectively produce desired beneficial residual stress in the steels for enhanced fatigue performance. Surface residual stress levels of -1.4GPa and -1.5GPa were achieved in shot peened C61 and laser peened C67, respectively, without introducing large surface roughness or defects. Higher compressive residual stress is expected in C67 according to a demonstrated correlation between attainable residual stress and material hardness. Due to the lack of appropriate shot media, dual laser peening is proposed for future peening optimization in C67. A novel non-destructive synchrotron radiation technique was implemented and applied for the first time for residual stress distribution analysis in gear steels with large composition and property gradients. Observed substantial residual stress redistribution and material microstructure change during the rolling contact fatigue screening test with extremely high 5.4GPa load indicates the unsuitability of the test as a fatigue life predictor. To exploit benefits of higher case hardness and associated residual stress, a new material and process (CryoForm70) aiming at 70Rc surface hardness was designed utilizing the systems approach based on thermodynamics and secondary hardening mechanisms. The composition design was first validated by the excellent agreement between experimental and theoretical core martensite start temperature in the prototype. A novel cryogenic deformation process was concurrently designed to increase the case martensite volume fraction from 76% to 92% for enhanced strengthening efficiency and surface hardness. High temperature vacuum carburizing was optimized for desired carbon content profiles using carbon diffusion simulation in the multi-component system. After cyclic tempering with intermediate cryogenic treatment, a case hardness of 68.5 +/- 0.3Rc at 0.72 +/- 0.2wt% carbon content was achieved. The design demonstrated the effectiveness of cryogenic deformation in promoting martensite transformation for high carbon and high alloy steels. Good agreement between achieved and predicted case and core hardness supports the effectiveness of the computational design approach.

Qian, Yana

406

Neutron Hardness Assurance for Bipolar Transistors through Determination of Physical Parameters.  

National Technical Information Service (NTIS)

A nondestructive method of neutron radiation hardness assurance is developed for bipolar transistors using a detailed one-dimensional model to obtain the powers (sensitivity parameters) relating postirradiation h sub FE and V sub CE(sat) at any operating ...

R. D. Blice, J. A. Munarin

1975-01-01

407

STP Hard Disks MD Program  

NSDL National Science Digital Library

The STP Hard Disks MD program simulates the dynamics of a system of hard disks. The default parameters are N=64 particles in a box of length L = 18.0 and a temperature T=1.0. The particles are initially in a regular array. STP HardDisksMD is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_HardDisksMD.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-06

408

Water Hardness and Cardiovascular Disease.  

National Technical Information Service (NTIS)

A brief review of the present state of knowledge regarding the relationship of water hardness to cardiovascular disease. Also included are recommendations for future research and a statement on the appropriateness of modifying current water treatment prac...

1979-01-01

409

Confined Hard Disk System Model  

NSDL National Science Digital Library

The Confined Hard Disk System is an idealized statistical mechanics model that simulates a two-dimensional system of hard disks confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the time evolution of the kinetic energy K per particle, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Hard Disk System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-12-27

410

Ejs Hard Disk Gas Model  

NSDL National Science Digital Library

The Ejs Hard Disk Gas model displays a two-dimensional gas made out of hard disks. Particles are initialized with a speed v=1 in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Disk Gas model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardDiskGas.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for statistical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

411

Experiment with the SPR-N Instrument Onboard the CORONAS-F Satellite: Polarization, Temporal, and Spectral Characteristics of the Hard X-Ray of the Solar Flares  

NASA Astrophysics Data System (ADS)

During the experiment with a polarimeter SPR-N onboard the CORONAS-F satellite, polarization of the X-ray of solar flares within the energy ranges of 20-40, 40-60, and 60-100 keV was measured according to Thomson scattering of X-ray photons in Beryllium plates with the following registration of the scattered photons by means of a system of six scintillation detectors based on Cs I(Na). As a result of observations for the period from August 2001 till December 2005, hard X-ray radiation was registered for 128 solar flares. During the event of 29 October 2003 degree of polarization of the radiation within the channels 40-60 and 60-100 keV exceeded 70 %, and within the channel 20-40 keV—50 %. Time profiles of the part of polarized radiation, orientation of the maximum polarization on the solar disc were obtained. The upper limit of the polarized radiation part for 25 events was estimated at the level of 8-40 %. For all registered flares time profiles (with resolution of up to 4 s) were registered, hard X-ray fluxes were determined, and spectrum factor was estimated. For the most powerful events which were observed during October-November 2003 and on January 20, 2005, the data on the dynamics of the characteristics of thermal and non-thermal components of X-radiation were obtained.

Zhitnik, I. A.; Logachev, Yu. I.; Bogomolov, A. V.; Bogomolov, V. V.; Denisov, Yu. I.; Kavanosyan, S. S.; Kuznetsov, S. N.; Morozov, O. V.; Myagkova, I. N.; Svertilov, S. I.; Ignatiev, A. P.; Oparin, S. N.; Pertsov, A. A.

412

Charpy Impact Energy and Microindentation Hardness of 60-NITINOL  

NASA Technical Reports Server (NTRS)

60-NITINOL (60 wt.% Ni 40 wt.% Ti) is being studied as a material for advanced aerospace components. The Charpy impact energy and microindentation hardness has been studied for this material, fabricated by vacuum induction skull melting (casting) and by hot isostatic pressing. Test specimens were prepared in various hardened and annealed heat treatment conditions. The average impact energy ranged from 0.33 to 0.49J for the hardened specimens while the annealed specimens had impact energies ranging from 0.89 to 1.18J. The average hardness values of the hardened specimens ranged from 590 to 676 HV while that of the annealed specimens ranged from 298 to 366 HV, suggesting an inverse relationship between impact energy and hardness. These results are expected to provide guidance in the selection of heat treatment processes for the design of mechanical components.

Stanford, Malcolm K.

2012-01-01

413

Elastic recovery at hardness indentations  

Microsoft Academic Search

The mechanics of hardness indentation are considered. On the basis of a cycle in which the loading is elastic-plastic and the unloading (and subsequent reloading) elastic, an expression is derived for the relative depth recovery of the impression as a function of hardness\\/modulus,H\\/E. Experimental observations on indented surfaces of selected materials, mostly ceramics, using a tilting procedure in the scanning

B. R. Lawn; V. R. Howes

1981-01-01

414

QPX Disease in Hard Clams  

NSDL National Science Digital Library

This New York SeaGrant PDF-brochure examines QPX (Quahog Parasite Unknown, a disease-causing parasite) as it relates to the hard clam fishery in New York. It discusses the origin of QPX, how it infects hard clams, where it has been found, signs of QPX disease, why people in New York should be concerned, and what is being done to control its spread.

Barnes, Debra; Allam, Bassem; Gall, Ken; Seagrant, New Y.

415

Microstructural design of hard coatings  

Microsoft Academic Search

Microstructural design has attracted increasing interest in modern development of hard coatings for wear-resistant applications. In plasma-assisted vapor deposited thin films, the material’s microstructure can be designed during growth or post-deposition annealing treatments. In this review, we demonstrate the correlation between microstructure and mechanical as well as tribological properties of hard ceramic coatings. This is done for single-phase coatings and

Paul H. Mayrhofer; Christian Mitterer; Lars Hultman; Helmut Clemens

2006-01-01

416

Charpy Impact Energy and Microindentation Hardness of 60-NITINOL.  

National Technical Information Service (NTIS)

60-NITINOL (60 wt.% Ni 40 wt.% Ti) is being studied as a material for advanced aerospace components. The Charpy impact energy and microindentation hardness has been studied for this material, fabricated by vacuum induction skull melting (casting) and by h...

M. K. Stanford

2012-01-01

417

Active Noise Control Using Piezoelectric Actuators in Hard Disk Drives  

Microsoft Academic Search

With the increasing use of electromechanical microsystems, such as hard disk drives, CD-ROM drives, and DVD drives in the consumer electronics industry, there is a growing demand for quieter products. The noise emitted from these devices may originate from the vibration of mechanical components in operation, such as bearings, gears, and actuators. The vibration is then transmitted to other parts

Feng Gao; Ying Yan; Fook Fah Yap

2003-01-01

418

Hard-on-Hard Total Hip Impingement Causes Extreme Contact Stress Concentrations  

PubMed Central

Background Impingement events, in addition to their role immediately proximate to frank dislocation, hold the potential to damage new-generation hard-on-hard bearings as a result of the relatively unforgiving nature of the materials and designs. Because of the higher stiffness and tighter design tolerances of metal-on-metal and ceramic implants, surgical positioning plausibly has become even more important. Questions/purposes We asked (1) whether, and under what cup orientation conditions, hard-on-hard impingements might challenge implant material failure strength; and (2) whether particle generation propensity at impingement and egress sites would show similar dependence on cup orientation. Methods Realistic computational simulations were enabled by multistage finite element analyses, addressing both global construct motion and loading, and focal stress concentrations at neck impingement and rim egress sites. The global model, validated by a cadaveric simulation in a servohydraulic hip simulator, included both hardware components and advanced anisotropic capsule characterization. Parametric computational runs explored the effect of cup orientation for both ceramic-on-ceramic and metal-on-metal bearing couples for two distinct motion sequences associated with dislocation. Results Stress concentrations from impingement increased nearly linearly with increased cup tilt and with cup anteversion. In some situations, peak values of stress approached or exceeded 1 GPa, levels challenging the yield strength of cobalt-chromium implants, and potentially the fracture strength of ceramics. The tendency for impingement events to generate debris, indexed in terms of a new scraping severity metric, showed orientation dependences similar to that for bulk material failure. Conclusions Damage propensity arising from impingement events in hard total hip bearings is highly orientation-dependent.

Elkins, Jacob M.; O'Brien, Megan K.; Stroud, Nicholas J.; Pedersen, Douglas R.; Callaghan, John J.

2010-01-01

419

Radiation damage and annealing of scintillating glasses  

Microsoft Academic Search

Measurements of the radiation hardness, of cerium and terbium doped scintillating glasses, are reported in this work. Annealing tests have demonstrated the efficacy of violet-blue light in the repairing of radiation damage.

P. Pavan; G. Zanella; R. Zannoni; P. Polato

1991-01-01

420

The radiative deceleration of ultrarelativistic jets in active galactic nuclei  

NASA Technical Reports Server (NTRS)

A detailed study of the dynamical interaction between a highly relativistic jet and the thermal radiation field from an AGN accretion disk is reported, and the Comptonized spectrum arising from this interaction is self-consistently determined. A simple model that captures the essential radiative and geometrical features of realistic disk configurations is presented, and the disk radiation field is calculated. The results confirm Phinney's (1987) suggestion that the thermal radiation field produced by accretion in an AGN could be very effective in decelerating ultrarelativistic jets that are accreted by electromagnetic or hydromagnetic forces closer to the central black hole. Terminal Lorentz factors are consistent with the values inferred in superluminal radio sources are readily produced in this model for plausible disk and jet parameters without additional acceleration in the interaction zone. A new interpretation of the hard X-ray component detected in BL Lac spectra is proposed.

Melia, Fulvio; Konigl, Arieh

1989-01-01

421

Experimental investigation of hard pellicle purge processes  

NASA Astrophysics Data System (ADS)

Optical lithography with 157-nm light is expected to bridge the gap between 193-nm technology and next-generation lithography. One important practical difficulty facing the implementation of 157-nm technology is gas absorption of 157-nm light. The exposure process for 193-nm technology is carried out in air. However, oxygen and water vapor attenuate 157-nm radiation. Alternatively, the exposure can be carried out in a nitrogen-purged environment. The purification of the volume trapped between the reticle and the hard pellicle is challenging because of the delicate pellicle geometry. In this paper, experimental results are presented that support the design and development of pellicle purge processes for 157-nm optical lithography. Specifically, a hard pellicle was installed in the Pressure Bulge Tool (at the UW Computational Mechanics Center) and experimental measurements of the pressure-induced pellicle distortion were obtained. The pressure loads imposed on the pellicle are representative of those expected during in-tool purge processes. Separate testing quantified the pellicle fracture stress and the flow characteristics of the pellicle/reticle geometry for a particular vent configuration (i.e., frame vent hole size and number, and filter system). These flow characteristics are important, as they ultimately dictate the pressure difference imposed on the pellicle during any purging process. These various experimental measurements, when taken together, facilitate the assessment of the feasibility and requirements associated with alternative pellicle purging strategies for 157-nm lithography.

Abdo, Amr Y.; Nellis, Gregory F.; Diab, Aya K.; Cotte, Eric P.; Chalekian, Aaron J.; Engelstad, Roxann L.; Lovell, Edward G.; Peski, Chris V.

2003-12-01

422

CONTROL OF LASER RADIATION PARAMETERS: Generation of Stark spectral components in Nd:YAP and Nd:YAG lasers by using volume Bragg gratings  

NASA Astrophysics Data System (ADS)

Generation of Stark spectral components in free-running Q-switched Nd:YAP (1064 nm and 1073 nm) and Nd:YAG (1062 nm) lasers is obtained. For this purpose reflecting volume Bragg gratings placed into the laser resonator and permitting to tune the laser emission spectrum were used. Stable generation of Stark components in both lasers is obtained. The possibility of obtaining two-frequency generation in an Nd-glass laser with the help of these gratings is shown.

Vorob'ev, Nikolai S.; Glebov, L. B.; Smirnov, V. I.; Chapurin, I. V.

2009-01-01

423

Complementary X-ray tomography techniques for histology-validated 3D imaging of soft and hard tissues using plaque-containing blood vessels as examples.  

PubMed

A key problem in X-ray computed tomography is choosing photon energies for postmortem specimens containing both soft and hard tissues. Increasing X-ray energy reduces image artifacts from highly absorbing