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1

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy resolution and detection efficiency for the active components of the PIBETA detector system. Beam defining plastic scintillation counters were operated in a ~1 MHz stopped $\\\\pi^+$ beam for a period of 297 days, accumulating radiation doses of up to 2 Mrad. Detectors in the charged particle tracking system--a pair

E. Frlez; T. A. Campbell; I. J. Carey; D. Pocanic

2002-01-01

2

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy res- olution and detection efficiency for the active components ofthe PIBETA de- tector system. Beam defining plastic scintillation counters were operated in a ?1MHz stopped ?+ beam for a period of 297 days, accumulating radiation doses of up to 2 ? 106 rad. Detectors in the charged particle tracking

E. Frleÿz; T. A. Campbell; I. J. Carey; D. Poÿcanic

3

Radiation hardness of the PIBETA detector components  

Microsoft Academic Search

We have examined long term changes in signal amplitude gain, energy\\u000aresolution and detection efficiency for the active components of the PIBETA\\u000adetector system. Beam defining plastic scintillation counters were operated in\\u000aa ~1 MHz stopped $\\\\pi^+$ beam for a period of 297 days, accumulating radiation\\u000adoses of up to 2 Mrad. Detectors in the charged particle tracking system--a\\u000apair

E. Frleÿz; T. A. Campbell; I. J. Carey; D. Poÿcanic

2002-01-01

4

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 2.35×10neutronspercm. 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

5

A New Analysis of Cosmic Radiation Including the Hard Component  

Microsoft Academic Search

A representation of all known data on cosmic-ray intensities in their dependence on geomagnetic latitude and on altitude, respectively, depth below sea level, has been obtained on the following assumptions: 1. A soft component consisting of electrons which follow the Bethe-Heitler theory up to the highest energies with a primary distribution E-n (E=energy, n between 3 and 2). 2. A

L. W. Nordheim

1938-01-01

6

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

7

GFW Handbook: Irradiation Test Guidelines for Radiation Hardness of Electronic Components.  

National Technical Information Service (NTIS)

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...

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

1982-01-01

8

Radiation hard fiber optics  

Microsoft Academic Search

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 antimony, cerium, boron, phosphorus and hydroxyl groups. The effects of such variations in the glass chemistry on the radiation inducted attenuation of the

R. E. Jaeger; M. Aslami

1981-01-01

9

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

10

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosph...

A. Pla-Dalmau D. Woods F. Markley G. Foster R. Blackburn

1992-01-01

11

Evidence for a change in the radiation mechanism in the hard state of GRO J1655-40. Hysteresis in the broad-band noise components  

NASA Astrophysics Data System (ADS)

We have analysed archival data from the Rossi X-ray Timing Explorer (RXTE) to study the aperiodic variability of the black hole binary GRO J1655-40 during the hard state of the 2005 outburst. This work was motivated by the recent finding of a spectral change in the hard state X-ray radiation mechanism in black hole binaries. We computed the 0.008-64 Hz power spectral density during the rise and decay of the 2005 outburst, and we found that they were reasonably well modelled by the sum of two, broad Lorenztian functions in most cases (plus a narrow QPO), which correspond to three different variability components. Our aim is to study the evolution of the timing properties of the source during the outburst, by studying the correlation between the characteristics of the broad-band noise components in the power spectra and the source luminosity. Our results suggest that the whole power spectrum shifts to high (low) frequencies as the source luminosity increases (decreases), in agreement with previous studies of other black hole binaries. However, we also detect a strong `hysteresis' pattern in the `frequency-luminosity' plots, and show that the `critical' luminosity limit, above which the timing properties of the source change, is different during the rise and the decay phase of the outburst. We discuss the general implications of these results in the context of the truncated disc model.

Reig, P.; Papadakis, I. E.; Sobolewska, M. A.; Malzac, J.

2013-09-01

12

Evidence for a change in the radiation mechanism in the hard state of GRO J1655-40. Hysteresis in the broad-band noise components  

NASA Astrophysics Data System (ADS)

We have analysed archival data from the Rossi X-ray Timing Explorer (RXTE) to study the aperiodic variability of the black hole binary GRO J1655-40 during the hard state of the 2005 outburst. This work was motivated by the recent finding of a spectral change in the hard state X-ray radiation mechanism in black hole binaries. We computed the 0.008-64 Hz power spectral density during the rise and decay of the 2005 outburst, and we found that they were reasonably well modelled by the sum of two, broad Lorenztian functions in most cases (plus a narrow QPO), which correspond to three different variability components. Our aim is to study the evolution of the timing properties of the source during the outburst, by studying the correlation between the characteristics of the broad-band noise components in the power spectra and the source luminosity. Our results suggest that the whole power spectrum shifts to high (low) frequencies as the source luminosity increases (decreases), in agreement with previous studies of other black hole binaries. However, we also detect a strong `hysteresis' pattern in the `frequency-luminosity' plots, and show that the `critical' luminosity limit, above which the timing properties of the source change, is different during the rise and the decay phase of the outburst. We discuss the general implications of these results in the context of the truncated disc model.

Reig, P.; Papadakis, I. E.; Sobolewska, M. A.; Malzac, J.

2013-11-01

13

BGO crystals - radiation hard scintillators  

Microsoft Academic Search

A new version of the Bridgman technique of Bi4Ge3O12 (BGO) crystal growth was developed. The first radiation hardness measurement of new BGO grown by this technique shows excellent characteristics. The optical transmission at a peak emission 0.48 mum of these crystals degraded by no more than 10% when irradiated by photons from 60Co decay up to a total dose of

V. V. Yanovsky; V. A. Chizhov; V. M. Skorikov

1991-01-01

14

Impact of aging on radiation hardness  

SciTech Connect

Burn-in effects are used to demonstrate the potential impact of thermally activated aging effects on functional and parametric radiation hardness. These results have implications on hardness assurance testing. Techniques for characterizing aging effects are proposed.

Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M. [and others

1997-07-01

15

Radiation hardness studies of CVD diamond detectors  

Microsoft Academic Search

The inherent properties of diamond make it an ideal material for tracking detectors especially in the high rate, high radiation environments of future colliders such as the LHC. In order to survive in this environment, detectors must be radiation hard. We have constructed charged particle detectors using high quality CVD diamond and performed radiation hardness tests on them. The signal

C. Bauer; I. Baumann; C. Colledani; J. Conway; P. Delpierre; F. Djama; W. Dulinski; A. Fallou; K. K. Gan; R. S. Gilmore; E. Grigoriev; G. Hallewell; S. Han; T. Hessing; K. Honschied; J. Hrubec; D. Husson; H. Kagan; D. Kania; R. Kass; W. Kinnison; K. T. Knöpfle; M. Krammer; T. J. Llewellyn; P. F. Manfredi; L. S. Pan; H. Pernegger; M. Pernicka; R. Plano; V. Re; S. Roe; A. Rudge; M. Schaeffer; S. Schnetzer; S. Somalwar; V. Speziali; R. Stone; R. J. Tapper; R. Tesarek; W. Trischuk; R. Turchetta; G. B. Thomson; R. Wagner; P. Weilhammer; C. White; H. Ziock; M. Zoeller

1995-01-01

16

Radiation Hard Fiber Optic Data Link for in situ gamma dot testing of TTL logic level I\\/O digital components and systems  

Microsoft Academic Search

A radiation Hardened Fiber Optic Data Link which allows Automatic Test Equipment (ATE) to communicate with a device or system under test in a flash X-ray environment was designed, built, installed and tested. The data link uses TTL (Transistor to Transistor Logic) logic. The fiber optic data link has a Total Integrated Dose (TID) hardness greater than 250 krads and

Jeffrey A. Krinsky; Tim R. Majoch; Richard A. Reynolds

1989-01-01

17

Radiation Hard Fiber Optic Data Link for in situ gamma dot testing of TTL logic level I/O digital components and systems  

NASA Astrophysics Data System (ADS)

A radiation Hardened Fiber Optic Data Link which allows Automatic Test Equipment (ATE) to communicate with a device or system under test in a flash X-ray environment was designed, built, installed and tested. The data link uses TTL (Transistor to Transistor Logic) logic. The fiber optic data link has a Total Integrated Dose (TID) hardness greater than 250 krads and a gamma dose rate survivability greater than 1E12 rad (Si)/sec. Test data obtained by interfacing a Tektronix S-3295 with a DUT (which may be either a simple device or a full system) during gamma dose rate irradiation of 1E12 rad(Si)/sec is included. Except for the time delay the data link is transparent to the ATE. The link has a data rate greater than 60Mb/s NRZ (Non Return to Zero). AlGaAs 830nM LEDs and Si PIN diodes are used. The hardness of this link allows it to be used in a variety of applications.

Krinsky, Jeffrey A.; Majoch, Tim R.; Reynolds, Richard A.

18

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

19

Development of radiation hard scintillators  

NASA Astrophysics Data System (ADS)

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyl trimethyl trisiloxane (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 from monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetra phenyl butadiene 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.; Harmon, J.; Biagtan, E.; Schueneman, G.; Senchishin, V.; Gustfason, H.

1993-11-01

20

Radiation Hard Nano-FET based Biosensor  

Microsoft Academic Search

A new nano transistor based biosensor has been developed which has the potential to detect pathogens and thus protect crew safety aboard long term manned flight programs. This work outlines structures which compose the biosensor and demonstrates that the nano transistors utilized herein are total dose radiation hard. The Nano Field Effect Transistors (FET) were designed and fabricated with doped

Eric Cameron; Nirankar Mishra; Paul Winterrowd; Ron Nelson; Shiva Rastogi; Wusi Maki

21

New component of hard X-rays in solar flares  

Microsoft Academic Search

We present high resolution (approx.1 keV FWHM) spectral measurements from 13 to 300 keV of a solar flare hard X-ray burst observed on 1980 June 27 by a balloon-borne array of cooled germanium planar detectors. At energies below approx.35 keV we identify a new component of solar flare hard X-rays. This component is characterized by an extremely steep spectrum which

R. P. Lin; R. A. Schwartz; R. M. Pelling; K. C. Hurley

1981-01-01

22

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

None

2012-05-01

23

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

24

1500 Gate standard cell compatible radiation hard gate array  

SciTech Connect

The G1500 gate array combines Sandia Labs' 4/3..mu.. CMOS silicon gate radiation hard process with a novel gate isolated standard cell compatible design for quick turnaround time, low cost, and radiation hardness. This device is hard to 5 x 10/sup 5/ rads, utilizes a configuration that provides high packing density, and is supported on both the Daisy and Mentor workstations. This paper describes Sandia Labs' radiation hard 4/3..mu.. process, the G1500's unique design, and the complete design capabilities offered by the workstations.

Mills, B.D.; Shafer, B.D.; Melancon, E.P.

1984-11-01

25

New phase for one-component hard spheres  

Microsoft Academic Search

A completely new phase for one-component hard spheres is reported in an unexpected region of the phase diagram. The new phase is observed at compressibility factors intermediate between the solid and the metastable branches. It can be obtained from either Monte Carlo simulations alone or a combination of Monte Carlo and molecular dynamics calculations. An analysis of the intermediate scattering

Guang-Wen Wu; Richard J. Sadus

2004-01-01

26

Integrating Unbounded Software Components into Hard Real-Time Systems  

Microsoft Academic Search

The incorporation of unbounded components (i.e. software modules that cannot be analysed to produce realistic worst case execution\\u000a times) into hard real-time applications has been recognised as a key issue for the next generation of real-time systems. In\\u000a this paper, we present a system model that caters for the three main approaches to integrating unbounded components: milestone\\u000a methods, sieve functions

N. C. Audsley; A. Burns; R. I. Davis; A. J. Wellings

27

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

28

Dynamics and energetics of the thermal and nonthermal components in the solar flare of January 20, 2005, based on data from hard electromagnetic radiation detectors onboard the CORONAS-F satellite  

NASA Astrophysics Data System (ADS)

Based on data from the SONG and SPR-N multichannel hard electromagnetic radiation detectors onboard the CORONAS-F space observatory and the X-ray monitors onboard GOES satellites, we have distinguished the thermal and nonthermal components in the X-ray spectrum of an extreme solar flare on January 20, 2005. In the impulsive flare phase determined from the time of the most efficient electron and proton acceleration, we have obtained parameters of the spectra for both components and their variations in the time interval 06:43-06:54 UT. The spectral index in the energy range 0.2-2 MeV for a single-power-law spectrum of accelerated electrons is shown to have been close to 3.4 for most of the time interval under consideration. We have determined the time dependence of the lower energy cutoff in the energy spectrum of nonthermal photons E ?0( t) at which the spectral flux densities of the thermal and nonthermal components become equal. The power deposited by accelerated electrons into the flare volume has been estimated using the thick-target model under two assumptions about the boundary energy E 0 of the electron spectrum: (i) E 0 is determined by E ?0( t) and (ii) E 0 is determined by the characteristic heated plasma energy (?5 kT ( t)). The reality of the first assumption is proven by the fact that plasma cooling sets in at a time when the radiative losses begin to prevail over the power deposited by electrons only in this case. Comparison of the total energy deposited by electrons with a boundary energy E ?0( t) with the thermal energy of the emitting plasma in the time interval under consideration has shown that the total energy deposited by accelerated electrons at the beginning of the impulsive flare phase before 06:47 UT exceeds the thermal plasma energy by a factor of 1.5-2; subsequently, these energies become approximately equal and are ˜(4-5) × 1030 erg under the assumption that the filling factor is 0.5-0.6.

Kurt, V. G.; Svertilov, S. I.; Yushkov, B. Yu.; Bogomolov, A. V.; Grechnev, V. V.; Galkin, V. I.; Bogomolov, V. V.; Kudela, K.; Logachev, Yu. I.; Morozov, O. V.; Myagkova, I. N.

2010-04-01

29

New phase for one-component hard spheres  

NASA Astrophysics Data System (ADS)

A completely new phase for one-component hard spheres is reported in an unexpected region of the phase diagram. The new phase is observed at compressibility factors intermediate between the solid and the metastable branches. It can be obtained from either Monte Carlo simulations alone or a combination of Monte Carlo and molecular dynamics calculations. An analysis of the intermediate scattering function data shows that the new phase is in a stable equilibrium. Radial distribution function data, configurational snapshots, bond order parameters, and translational order parameters obtained from molecular simulations indicate that the new phase is significantly different from the isotropic liquid, metastable, or crystalline phases traditionally observed in hard sphere systems. This result significantly changes our previous understanding of the behavior of hard spheres.

Wu, Guang-Wen; Sadus, Richard J.

2004-06-01

30

Geometric optimization for radiation hardness assurance  

NASA Astrophysics Data System (ADS)

The probability of a single event effect occurring is generally a function of the energy deposited in a sensitive volume, which is typically expressed as the absorbed dose in that volume. For short segments of high energy particle tracks, the dose due to a single event is proportional to the chord length through the sensitive volume. Thus, the distribution of dose in chord length is likely to relate to the probability of single event effects. For various geometries, a differential chord length distribution was generated and from this the dose distribution, frequency mean chord length, and dose mean chord length were calculated. In every case, the dose mean chord length was greater than the frequency mean chord length by a minimum of 26% and increased with the eccentricity of the volume. The large value of the dose mean chord length relative to the frequency mean chord length demonstrates the need to consider rare, long-chord-length crossings in radiation hardness testing, despite their relatively low probability of occurrence.

Northum, J.; Guetersloh, S.

31

Slow Component Suppression and Radiation Damage in Doped BaF2 Crystals.  

National Technical Information Service (NTIS)

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 ...

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

1988-01-01

32

Slipping surface discharge as a source of hard UV radiation  

NASA Astrophysics Data System (ADS)

The UV-spectrum of a high-current slipping surface discharge radiation has been investigated experimentally by means of a liquid chemical actinometry technique. The photon fluxes emitted in the hard UV (icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/> <190 nm) and soft UV (190 nm <430 nm) regions were determined by the H2 O2 yield in irradiated distilled water and by the Fe II yield in an irradiated solution of K3 Fe(C2 O4 )3 , respectively. The results obtained lead to the conclusion that the spectrum differs from the Planckian one by the presence of an `enriched' short-wavelength (icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/> <190 nm) component.

Bark, Yu B.; Barkhudarov, E. M.; Kozlov, Yu N.; Kossyi, I. A.; Silakov, V. P.; Taktakishvili, M. I.; Temchin, S. M.

2000-04-01

33

Method for producing hard-surfaced tools and machine components  

DOEpatents

In one aspect, the invention comprises a method for producing tools and machine components having superhard crystalline-ceramic work surfaces. Broadly, the method comprises two steps: A tool or machine component having a ceramic near-surface region is mounted in ion-implantation apparatus. The region then is implanted with metal ions to form, in the region, a metastable alloy of the ions and said ceramic. The region containing the alloy is characterized by a significant increase in hardness properties, such as microhardness, fracture-toughness, and/or scratch-resistance. The resulting improved article has good thermal stability at temperatures characteristic of typical tool and machine-component uses. The method is relatively simple and reproducible.

McHargue, Carl J. (Farragut, TN)

1985-01-01

34

Method for producing hard-surfaced tools and machine components  

DOEpatents

In one aspect, the invention comprises a method for producing tools and machine components having superhard crystalline-ceramic work surfaces. Broadly, the method comprises two steps: a tool or machine component having a ceramic near-surface region is mounted in ion-implantation apparatus. The region then is implanted with metal ions to form, in the region, a metastable alloy of the ions and said ceramic. The region containing the alloy is characterized by a significant increase in hardness properties, such as microhardness, fracture-toughness, and/or scratch-resistance. The resulting improved article has good thermal stability at temperatures characteristic of typical tool and machine-component uses. The method is relatively simple and reproducible.

McHargue, C.J.

1981-10-21

35

Radiation-Hard Breadboard Star Tracker.  

National Technical Information Service (NTIS)

Operation in a radiation environment affects the performance of many types of electro-optical sensors. Specifically, noise generated from radiation in the detector and front-end electronics in star trackers can degrade the performance of the sensors. Upse...

M. W. Hubbard D. L. Murata

1985-01-01

36

Tailoring the radiation hardness of fused silica  

NASA Astrophysics Data System (ADS)

The degradation of optical transmission of two types of Heraeus Suprasil synthetic fused silica after exposure to ionising radiation was investigated with regard to usage as a DIRC radiator. These studies led to the discovery of defect mechanisms that are well known for UV laser irradiation also being present for ionising radiation. The dependence of the optical degradation on interstitial hydrogen, as predicted by existing defect models, could be verified. This leads to an improved understanding of the radiation damage processes and allows to specify the composition of synthetic fused silica according to experimental requirements especially in terms of radiation load.

Hoek, Matthias; PANDA Cherenkov Group

2011-05-01

37

Radiation hard 1.0?m CMOS technology  

Microsoft Academic Search

This paper describes radiation test results of a radiation hard CMOS technology with 1.0 ?m minimum geometry features. The radiation goals of this technology are to ensure the MOS devices are functional after 10 Mrad total dose irradiation, are single event upset hardened to less than 1E-10 errors per bit-day, are transient upset immune to 1E9 rads\\/sec and are latch-up

K. H. Lee; John C. Desko; Ross A. Kohler; Cris W. Lawrence; William J. Nagy; Julie A. Shimer; Steven D. Steenwyk; Richard E. Anderson; Julia S. Fu

1987-01-01

38

Golden Rule of Radiation Hardness: a Study of Strain Effect on Controlled Radiation Damage  

NASA Astrophysics Data System (ADS)

Stain is widely presented in microstructures. Strain effect to radiation hardness is critical in understanding and engineering nano-materials. Here we studied the strain effect on the controlled radiation damage in monolayer hexagonal boron nitride (h-BN) through ab initio density functional theory calculations. We observed a general behavior of reduction in the radiation hardness by the strain, for both B-vacancy and N-vacancy configurations, in both compressive and tensive strain states, at the directions of zigzag, armchair and bi-axial. We proposed a golden rule of the radiation hardness states that any effort adding energy to the system will reduce the radiation hardness. Such golden rule of radiation hardness could be widely applied to material design and engineering for those devices working in irradiation-enrich environments, for example, electronic and optoelectronic devices in outer space.

Peng, Qing; Ji, Wei; de, Suvranu

2012-02-01

39

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

40

Optimizing Radiation Hard by Design SRAM Cells  

Microsoft Academic Search

Various radiation hardened by design SRAM cells are explored for their size, electrical performance, and total ionizing dose (TID) immunity. TID experiments using Co-60 testing on 130- and 90-nm transistors and SRAM arrays show that SRAM cells using two-edge transistors, NMOS access transistors, and NMOS reverse-body-bias effectively mitigate TID in both generations. This work experimentally demonstrates that commercial foundry (optimally

Lawrence T. Clark; Karl C. Mohr; Keith E. Holbert; Xiaoyin Yao; Jonathan Knudsen; Harshit Shah

2007-01-01

41

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

42

A software component for estimating solar radiation  

Microsoft Academic Search

GSRad (global solar radiation) is a software component containing models to estimate extra-terrestrial and ground-level solar radiation (global and photosynthetically active; direct, diffuse, and reflected components) from alternative methods. Radiation data are estimated as either 1-h or 24-h values. Moreover, GSRad provides methods to compute clear sky transmissivity, slope and aspect angles of tilted terrains from a grid of elevation

Marcello Donatelli; Laura Carlini; Gianni Bellocchi

2006-01-01

43

The Variation of the Hard Component of Cosmic Rays with Height and the Disintegration of Mesotrons  

Microsoft Academic Search

The vertical intensity of the hard component of cosmic rays was measured at different altitudes with a threefold coincidence counter tube arrangement. Measurements were taken with and without a graphite layer above the counters in order to compare the absorption of the hard component in air and in carbon. The counting rate observed under a given mass of air-plus-carbon was

Bruno Rossi; Norman Hilberry; J. Barton Hoag

1940-01-01

44

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

45

Hard Carbon Coatings for IR-Optical Components.  

National Technical Information Service (NTIS)

Hydrogenated amorphous carbon films (a-C:H) were deposited on glass, silicon and germanium substrates. The films are transparent in the IR and are extremely hard. The a-C:H films were homogeneously deposited at a rate of about 500 A/min in an RF excited d...

A. Bubenzer B. Dischler P. Koidl

1982-01-01

46

Hard X-Radiation from a Fast Coronal Ejection  

NASA Astrophysics Data System (ADS)

We have observed a high-speed coronal ejection in hard X-rays, detectable to an altitude of some 2×105 km in the Yohkoh 23-53 keV energy bands. Simultaneous imaging at 17 and 34 GHz from the Nobeyama radioheliograph shows complex moving features simultaneous with the ejection, including a compact source that we identify with the rapid X-ray source motion. The hard X-ray and microwave observations agree on ejection velocities in the vicinity of 1000 km s-1. The hard X-ray sources also corresponded in position angle to a bright coronal mass ejection (CME) detected about 15 minutes later and temporally to both fast-drift and slow-drift radio bursts in the decimeter-meter bands. Other components of coronal hard X-ray emission were also detected, including an extended long-duration event with a nonthermal spectrum. We suggest that a major eruptive flare occurred in NOAA Active Region 9415, approximately 26° beyond the west limb at the time of the event. Estimating a source density of 4×109 cm-3 from the compact source observed at 17 GHz, we find a total electron number (>20 keV) of approximately N20~1.3×1036 for the compact part of the source. We infer that these electrons were trapped in expanding loops forming a part of the CME and may have contributed substantial pressure within these loops.

Hudson, H. S.; Kosugi, T.; Nitta, N. V.; Shimojo, M.

2001-11-01

47

Radiation-hard semiconductor detectors for SuperLHC  

NASA Astrophysics Data System (ADS)

An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016 cm-2. The CERN-RD50 project “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.

Bruzzi, M.; Adey, J.; Al-Ajili, A.; Alexandrov, P.; Alfieri, G.; Allport, P. P.; Andreazza, A.; Artuso, M.; Assouak, S.; Avset, B. S.; Barabash, L.; Baranova, E.; Barcz, A.; Basile, A.; Bates, R.; Belova, N.; Biagi, S. F.; Bilei, G. M.; Bisello, D.; Blue, A.; Blumenau, A.; Boisvert, V.; Bolla, G.; Bondarenko, G.; Borchi, E.; Borrello, L.; Bortoletto, D.; Boscardin, M.; Bosisio, L.; v. Bowcock, T. J.; Brodbeck, T. J.; Broz, J.; Brukhanov, A.; Brzozowski, A.; Buda, M.; Buhmann, P.; Buttar, C.; Campabadal, F.; Campbell, D.; Candelori, A.; Casse, G.; Cavallini, A.; Chilingarov, A.; Chren, D.; Cindro, V.; Citterio, M.; Collins, P.; Coluccia, R.; Contarato, D.; Coutinho, J.; Creanza, D.; Cunningham, W.; Cvetkov, V.; Dalla Betta, G.-F.; Davies, G.; Dawson, I.; de Boer, W.; de Palma, M.; Demina, R.; Dervan, P.; Dierlamm, A.; Dittongo, S.; Dobrzanski, L.; Dolezal, Z.; Dolgolenko, A.; Eberlein, T.; Eremin, V.; Fall, C.; Fasolo, F.; Ferbel, T.; Fizzotti, F.; Fleta, C.; Focardi, E.; Forton, E.; Franchenko, S.; Fretwurst, E.; Gamaz, F.; Garcia, C.; Garcia-Navarro, J. E.; Gaubas, E.; Genest, M.-H.; Gill, K. A.; Giolo, K.; Glaser, M.; Goessling, C.; Golovine, V.; González Sevilla, S.; Gorelov, I.; Goss, J.; Gouldwell, A.; Grégoire, G.; Gregori, P.; Grigoriev, E.; Grigson, C.; Grillo, A.; Groza, A.; Guskov, J.; Haddad, L.; Härkönen, J.; Harding, R.; Hauler, F.; Hayama, S.; Hoeferkamp, M.; Hönniger, F.; Horazdovsky, T.; Horisberger, R.; Horn, M.; Houdayer, A.; Hourahine, B.; Hruban, A.; Hughes, G.; Ilyashenko, I.; Irmscher, K.; Ivanov, A.; Jarasiunas, K.; Jin, T.; Jones, B. K.; Jones, R.; Joram, C.; Jungermann, L.; Kalinina, E.; Kaminski, P.; Karpenko, A.; Karpov, A.; Kazlauskiene, V.; Kazukauskas, V.; Khivrich, V.; Khomenkov, V.; Kierstead, J.; Klaiber-Lodewigs, J.; Kleverman, M.; Klingenberg, R.; Kodys, P.; Kohout, Z.; Korjenevski, S.; Kowalik, A.; Kozlowski, R.; Kozodaev, M.; Kramberger, G.; Krasel, O.; Kuznetsov, A.; Kwan, S.; Lagomarsino, S.; Lari, T.; Lassila-Perini, K.; Lastovetsky, V.; Latino, G.; Latushkin, S.; Lazanu, S.; Lazanu, I.; Lebel, C.; Leinonen, K.; Leroy, C.; Li, Z.; Lindström, G.; Lindstrom, L.; Linhart, V.; Litovchenko, A.; Litovchenko, P.; Litvinov, V.; Lo Giudice, A.; Lozano, M.; Luczynski, Z.; Luukka, P.; Macchiolo, A.; Mainwood, A.; Makarenko, L. F.; Mandi?, I.; Manfredotti, C.; Marti I Garcia, S.; Marunko, S.; Mathieson, K.; Mozzanti, A.; Melone, J.; Menichelli, D.; Meroni, C.; Messineo, A.; Miglio, S.; Mikuž, M.; Miyamoto, J.; Moll, M.; Monakhov, E.; Moscatelli, F.; Murin, L.; Nava, F.; Naoumov, D.; Nossarzewska-Orlowska, E.; Nummela, S.; Nysten, J.; Olivero, P.; Oshea, V.; Palviainen, T.; Paolini, C.; Parkes, C.; Passeri, D.; Pein, U.; Pellegrini, G.; Perera, L.; Petasecca, M.; Piatkowski, B.; Piemonte, C.; Pignatel, G. U.; Pinho, N.; Pintilie, I.; Pintilie, L.; Polivtsev, L.; Polozov, P.; Popa, A. I.; Popule, J.; Pospisil, S.; Pucker, G.; Radicci, V.; Rafí, J. M.; Ragusa, F.; Rahman, M.; Rando, R.; Roeder, R.; Rohe, T.; Ronchin, S.; Rott, C.; Roy, P.; Roy, A.; Ruzin, A.; Ryazanov, A.; Sadrozinski, H. F. W.; Sakalauskas, S.; Scaringella, M.; Schiavulli, L.; Schnetzer, S.; Schumm, B.; Sciortino, S.; Scorzoni, A.; Segneri, G.; Seidel, S.; Seiden, A.; Sellberg, G.; Sellin, P.; Sentenac, D.; Shipsey, I.; Sicho, P.; Sloan, T.; Solar, M.; Son, S.; Sopko, B.; Spencer, N.; Stahl, J.; Stavitski, I.; Stolze, D.; Stone, R.; Storasta, J.; Strokan, N.; Strupinski, W.; Sudzius, M.; Surma, B.; Suuronen, J.; Suvorov, A.; Svensson, B. G.; Tipton, P.; Tomasek, M.; Troncon, C.; Tsvetkov, A.; Tuominen, E.; Tuovinen, E.; Tuuva, T.; Tylchin, M.; Uebersee, H.; Uher, J.; Ullán, M.; Vaitkus, J. V.; Vanni, P.; Velthuis, J.; Verzellesi, G.; Verbitskaya, E.; Vrba, V.; Wagner, G.; Wilhelm, I.; Worm, S.; Wright, V.; Wunstorf, R.; Zabierowski, P.; Zaluzhny, A.; Zavrtanik, M.; Zen, M.; Zhukov, V.; Zorzi, N.

2005-04-01

48

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

49

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

50

Radiation hardness of silicon detectors for future colliders  

NASA Astrophysics Data System (ADS)

The radiation hardness of silicon pad detectors, especially developed for the PLUG-calorimeter of the H1 experiment at HERA was investigated with respect to neutron and electron irradiation. Be(d,n)-neutrons with an average energy of 6.2 MeV up to a fluence of 1015 n/cm2 and 1.8 MeV electrons up to a dose of 1 MGy (1016 e/cm2) were used. Degradation effects of the diode properties regarding the reverse current, depletion voltage and charge collection efficiency are studied at room temperature and with no bias applied during irradiation. Special emphasis is put on the separation of the respective damage generation and its subsequent self annealing. The observed effects are discussed with respect to radiation levels to be envisioned for experiments with future colliding beam machines.

Fretwurst, E.; Claussen, N.; Croitoru, N.; Lindström, G.; Papendick, B.; Pein, U.; Schatz, H.; Schulz, T.; Wunstorf, R.

1993-03-01

51

New designs of CMS silicon pixel detectors for radiation hardness  

NASA Astrophysics Data System (ADS)

New designs of silicon pixel detectors with n+/n/p+ and double-sided multiguard ring structures have been developed for more radiation-tolerant CMS forward pixel sensors. In a later design modification, guard rings on the n+ side are replaced with a single wide (640?m) n+ implant, and the entire n+ side and the edge region of the p+ side are grounded. All designs were fabricated from both normal and oxygen-enriched silicon wafers, and radiation hardness effects for neutron (1MeV equivalent) and proton (24GeV) irradiation of these detectors were compared. Other electrical characteristics such as leakage current, potential distribution over guard rings and full depletion voltage were tested, using standard techniques of I-V, V-V, C-V and TCT before and after irradiation.

Chien, C. Y.; Cho, H. S.; Huang, W.; Li, Z.; Liang, G. W.; Xie, X. B.

2000-12-01

52

Beetle-a radiation hard readout chip for the LHCb experiment  

NASA Astrophysics Data System (ADS)

A new radiation hard pipelined readout chip is being developed for the LHCb-experiment. Appropriate design measures have been taken to ensure the radiation hardness against total ionising dose effects in excess of 45Mrad, as well as radiation effects induced by single particles.

Agari, M.; van Bakel, N.; Bauer, C.; Baumeister, D.; van Beuzekom, M.; Feuerstack-Raible, M.; Harnew, N.; Hofmann, W.; Jans, E.; Klous, S.; Knöpfle, K. T.; Löchner, S.; Schmelling, M.; Sexauer, E.; Smale, N.; Trunk, U.; Verkooijen, H.

2004-02-01

53

Nanostructuring induced enhancement of radiation hardness in GaN epilayers  

SciTech Connect

The radiation hardness of as-grown and electrochemically nanostructured GaN epilayers against heavy ion irradiation was studied by means of photoluminescence (PL) and resonant Raman scattering (RRS) spectroscopy. A nanostructuring induced enhancement of the GaN radiation hardness by more than one order of magnitude was derived from the PL and RRS analyses. These findings show that electrochemical nanostructuring of GaN layers is a potentially attractive technology for the development of radiation hard devices.

Ursaki, V. V.; Tiginyanu, I. M.; Volciuc, O.; Popa, V.; Skuratov, V. A.; Morkoc, H. [Laboratory of Low-Dimensional Semiconductor Structures, Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of) and National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova); Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna, Moscow region (Russian Federation); Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 and Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)

2007-04-16

54

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

55

Radiation-resistant beamline components at LAMPF  

SciTech Connect

A variety of highly radiation-resistant beamline components have been successfully developed at LAMPF primarily for use in the target cells and beam stop area of the intense proton beamline. Design features and operating experience are reviewed for magnets, instrumentation, targets, vacuum seals, vacuum windows, collimators, and beam stops.

Macek, R.J.; Grisham, D.L.; Lambert, J.e.; Werbeck, R.

1983-01-01

56

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

57

When GRB afterglows get softer, hard components come into play  

SciTech Connect

We investigated the ability of simple spectral models to describe the early afterglow emission of GRBs. We found that four spectra, belonging to the GRB060502A, GRB060729, GRB060904B, GRB061H0A prompt-afterglow transition phase, can be modeled neither by a single power-law nor by the Band model. Instead we find that the data present high-energy (>3 keV, in the observer frame) statistically significant excesses with respect to these models In all four cases, the deviations can be modeled well by adding either a second power law or a blackbody component to the usual synchrotron power law spectrum. Although the data do not allow an unequivocal physical interpretation, the importance of this analysis consists in showing that a simple power-law model or a Band model is insufficient to describe the X-ray spectra of a small homogeneous sample of GRBs at the end of their prompt phase [1].

Moretti, A.; Campana, S.; Covino, S.; Tagliaferri, G. [INAF, Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807, Merate (Italy); Margutti, R.; Pasotti, F.; Chincarini, G.; Guidorzi, C.; Romano, P. [Universita degli Studi di Milano-Bicocca, Piazza delle Scienze 3, I-20126 Milano (Italy); Beardmore, A. P.; Godet, O.; Osborne, J. P. [University of Leicester, LE1 7RH (United Kingdom)

2008-05-22

58

A New Radiation Hard Semiconductor - Semi-Insulating GaN: Photoelectric Properties  

NASA Astrophysics Data System (ADS)

The anticipated upgrade of the CERN Large Hadron Collider to ten times brighter luminosity poses a severe challenge to semiconductor detectors in the CERN experiments. The suitability of semi-insulating GaN (SI-GaN), proposed as an alternative to silicon for the fabrication of radiation hard detectors, is investigated here in MOCVD GaN layers grown on sapphire. The electrical properties of SI-GaN were studied by dc and microwave techniques, and defect parameters determined by the method of thermally stimulated currents. Variations of charge collection efficiency (CCE) in SI-GaN diodes induced by ionizing radiation of 5.48 MeV alpha particles were revealed. Samples were also irradiated by X-rays, reactor neutrons and high-energy proton fluences of up to 1016 cm-2. The high radiation hardness of SI-GaN was demonstrated by the modest reduction in CCE, from 92% to 77%, in the material irradiated by neutrons (up to a fluence of 1015 cm-2). The CCE was unaffected by an X-rays dose of 600 MRad), but decreased to a few % after proton and neutron fluences of 1016 cm-2. The electrical characteristics vary more significantly, depending on irradiation type and dose. Fast decay components and a significant role of percolation effects are observed in the photoconductivity transients.

Vaitkus, J.; Gaubas, E.; Kazukauskas, V.; Blue, A.; Cunningham, W.; Rahman, M.; Smith, K.; Sakai, S.

2005-06-01

59

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

60

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

Microsoft Academic Search

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,

P. M. Lenahan; P. V. Dressendorfer

1983-01-01

61

Technological limitations in the isolation of individual components of hard-coal tar by fractional distillation  

SciTech Connect

Hard-coal tar is the source of a valuable raw material for the chemical industry. It contains considerable amounts of naphthalene and its homologs, indole, acenaphthene, dibenzofuran and fluorene. Of the above-mentioned substances, naphthalene is isolated on the industrial scale, and the resources of the other components are scarcely utilized. The difficulties in the creation of a rational technology for isolating the individual components are determined to some degree by the inadequacy of the study of the physicochemical laws of the separation of a hard-coal tar as a polyazeotropic-polyeutectic mixture. In the reported study, the technological limitations arising in the isolation from hard-coal tar by fractional distillation of naphthalene and its homologs, biphenyl, acenaphthene, dibenzofuran and fluorene have been investigated by the method of thermodynamic-topological analysis. 5 refs.

Belousova, O.A.; Lekhova, G.B.; Kharlampovich, G.D.

1981-01-01

62

Vibro-acoustic interaction of components in hard disk drive under seek process  

Microsoft Academic Search

With the increasing use of electro-mechanical systems 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

F. Gao; Y. Yan; F. F. Yap

2003-01-01

63

Technological limitations in the isolation of individual components of hard-coal tar by fractional distillation  

Microsoft Academic Search

Hard-coal tar is the source of a valuable raw material for the chemical industry. It contains considerable amounts of naphthalene and its homologs, indole, acenaphthene, dibenzofuran and fluorene. Of the above-mentioned substances, naphthalene is isolated on the industrial scale, and the resources of the other components are scarcely utilized. The difficulties in the creation of a rational technology for isolating

O. A. Belousova; G. B. Lekhova; G. D. Kharlampovich

1981-01-01

64

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

Microsoft Academic Search

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.

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

2003-01-01

65

An investigation into the effects of hard turning surface integrity on component service life  

NASA Astrophysics Data System (ADS)

Hard machining is the machining of materials at 45 HRC or greater. Recent improvements in machine tools and tool material have made hard machining a viable option. In order for hard machining to gain acceptance, it must be shown that as a finishing process, it will provide surfaces that meet the same quality standards as grinding. This research addressed the relationship between surface integrity generated by finishing processes and component service life. Fatigue and wear testing were utilized to determine the impact of hard turning as compared to the traditional finishing process of grinding. Test specimens were generated under controlled manufacturing processes and included five distinct surface conditions: hard turned with continuous white layer on the surface, hard turned with no white layer, ground, and hard turned and ground specimens subsequently superfinished. Extensive fatigue and wear testing was conducted to determine the performance of each surface condition relative to the other conditions. The surface integrity of each surface condition was thoroughly characterized through surface topography mapping, metallographic inspection, residual stress measurement, TEM analysis, and nanoindentation hardness measurements. The most significant conclusions were that the presence of white layers generated using new tooling did not affect the fatigue life or wear characteristics of the specimens. In fact, the physical evidence resulting from this investigation suggests that under controlled conditions (i.e. limited tool wear), the white layer is nothing more than an artifact resulting from the manufacturing process and does not contribute to the service life of the specimen. While the phase and crystallographic structure of the white layer is identical to the bulk material, the grains within the white layer have undergone significant grain refinement and the white layer is harder. Experiments were conducted that demonstrated that the physical characteristics of white layers resulting from excessive tool wear differ from those generated with new tooling. Although both white layers appeared similar under microscopic inspection, nano-indentation results indicate that white layers developed through tool wear is harder.

Smith, Stephen Ray

66

Low power radiation hard GaAs RAM  

NASA Astrophysics Data System (ADS)

The scope of this program is to demonstrate a 1K GaAs static RAM having very low power dissipation, 1 micro W/bit in standby, and a short access time, 10 ns, to meet the requirements of the DARPA Advanced On-Board Signal Processor (AOSP). In the six month period covered by this report the initial processing of the 1K RAM arrays was begun. Testing of several lots revealed a mask error which is currently being corrected. The isolation studies for ultra-low power devices continued with major emphasis on isolation degradation following the Schottky metal process. A theoretical formulation for the leakage behavior of GaAs substrates was initiated, and good agreement between theory and the experimental data was obtained. Upset measurements have been made on a number of 256 bit RAMs using an Am-241 alpha particle source. The numerical value for the failure cross section was found to be similar in magnitude to the area of the Schottky barrier speed-up capacitor, suggesting that the capacitor is primarily responsible for the magnitude of the upset cross section. Single event upset measurements have also been carried out using 40 meV/protons at the NRL cyclotron facility. The results for this case also demonstrated a lower upset cross section for RAMs fabricated without the n(-) layer in the speed-up capacitor. A conceptual design of a new RAM mask set was begun in order to evaluate a wider range of RAM cell configurations. Both 256 and 1K bit arrays are being considered, and emphasis will be placed both on cell designs for enhanced yield and radiation hardness. Enhancement/depletion devices will also be incorporated into the design.

Kirkpatrick, C. G.; Vahrenkamp, R.

1984-03-01

67

Discovery of an Extra Hard Spectral Component in the High-energy Afterglow Emission of GRB 130427A  

NASA Astrophysics Data System (ADS)

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; Tang, Qing-Wen; Hou, Shu-Jin; Liu, Ruo-Yu; Wang, Xiang-Yu

2013-07-01

68

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

NASA Astrophysics Data System (ADS)

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.

1995-10-01

69

Total dose radiation hardness of MOS devices in hermetic ceramic packages  

Microsoft Academic Search

The total dose radiation hardness of hardened MOS transistors is experimentally shown to be degraded by hydrogen gas commonly trapped in hermetic ceramic package cavities. This introduces another variable to be considered in the manufacture and hardness assurance of total dose hardened integrated circuits. The observation also extends the link between hydrogen and interface state formation and adds to our

R. A. Kohler; R. A. Kushner; Kuo Hua Lee

1988-01-01

70

Optimum laboratory radiation source for hardness assurance testing  

Microsoft Academic Search

Silicon-on-insulator (SOI) and bulk-silicon transistors were irradiated using X-ray, Co-60 gamma, and proton radiation sources. Co-60 gamma irradiation generates larger radiation-induced threshold voltage shifts (by a factor of two) in SOI buried oxides and in parasitic field oxides under low-field conditions than X-ray or proton irradiation. For all devices examined, the radiation-induced threshold voltage shifts generated by X-ray irradiation were

J. R. Schwank; M. R. Shaneyfelt; P. Paillet; D. E. Beutler; V. Ferlet-Cavrois; B. L. Draper; R. A. Loemaker; P. E. Dodd; F. W. Sexton

2001-01-01

71

Radiation hardness by design for mixed signal infrared readout circuit applications  

NASA Astrophysics Data System (ADS)

Readout integrated circuits (ROICs) to support space-based infrared detection applications often have severe radiation tolerance requirements. Radiation hardness-by-design (RHBD) significantly enhances the radiation tolerance of commercially available CMOS and custom radiation hardened fabrication techniques are not required. The combination of application specific design techniques, enclosed gate architecture nFETs and intrinsic thin oxide radiation hardness of 180 nm process node commercial CMOS allows realization of high performance mixed signal circuits. Black Forest Engineering has used RHBD techniques to develop ROICs with integrated A/D conversion that operate over a wide range of temperatures (40K-300K) to support infrared detection. ROIC radiation tolerance capability for 256x256 LWIR area arrays and 1x128 thermopile linear arrays is presented. The use of 130 nm CMOS for future ROIC RHBD applications is discussed.

Gaalema, Stephen; Gates, James; Dobyns, David; Pauls, Greg; Wall, Bruce

2013-09-01

72

Experimental study of hard photon radiation processes at HERA  

Microsoft Academic Search

We present an experimental study of theep?e?+p andep?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 theep?e?+X events in which the hard photon is detected at angles ??' = 0.45 mrad with respect to the incident

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

1995-01-01

73

Duplex Treatment of Tools and Components: Previous or Subsequent Electron Beam Hardening of Thermochemically-Treated and PVD Hard-Coated Steels for Tools and Components  

Microsoft Academic Search

The tribological properties of tools and components are improved by wear resistant coatings deposited by thermochemical processing (nitriding, nitrocarburizing) or physical vapor deposition (PVD) technologies. The properties gradient between the very hard and brittle layer and the soft, ductile, but hardenable matrix material can be significantly improved by previous or subsequent electron beam hardening (EBH). The hardness of matrix material

Gundis Sacher; Rolf Zenker; Heinz-Joachim Spies

2009-01-01

74

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

75

Redistribution of the halogen light source radiation by hard dental tissues  

NASA Astrophysics Data System (ADS)

The effect of redistribution of halogen light source intensity by hard dental tissues is presented. The study was performed on extracted intact molars. Commercially available lamp for light-cured materials was used as halogen light source. The spatial distribution of radiation was registered by CCD camera. The effect of redistribution of halogen light source intensity is caused by waveguide-scattering properties of dentin. This effect may be observed in case of irradiation of light-cured material through hard dental tissues.

Grisimov, Vladimir N.

1997-12-01

76

Observation of annihilation radiation from the galactic center: The point and ridge components  

Microsoft Academic Search

Using the all-sky map obtained with the Medium Energy Detectors (80 keV–2 MeV) of the UCSD\\/MIT Hard X-ray and Low-Energy Gamma Ray Experiment on HEAO-1, a joint determination of the point source and the galactic ridge components of 511 keV annihilation radiation has been made. The ridge determination assumes the longitudinal distribution measured from 90–270 keV, which has a strong

D. E. Gruber; M. S. Briggs

1991-01-01

77

Sliced linear zone plates for hard X-ray radiation  

NASA Astrophysics Data System (ADS)

Linear zone plates for hard ( E > 10 keV) X rays are considered. The technology of the plates includes cutting magnetron-sputtered W5Si3/Si multilayer coatings. The results of numerical computation suggest that this pair of materials provides a high efficiency in the first and second diffraction orders. It is found experimentally that good multilayer structures consisting of several hundreds of layers can be synthesized on silicon and glass substrates. It is shown that they can be cut by ion etching the multilayer coating through a mask.

Artyukov, I. A.; Burtsev, V. A.; Vinogradov, A. V.; Devizenko, A. Yu.; Kalinin, N. V.; Kopylets, I. A.; Kondratenko, V. V.; Pukha, V. E.; Savitskii, B. A.; Feshchenko, R. M.

2012-09-01

78

Radiation hardness studies of cooling fluids epoxies and capacitors for CMS pixel system  

NASA Astrophysics Data System (ADS)

Radiation hardness studies of C6F14 Fluorinert (FC72) fluid, some epoxies and tantalum capacitors were studied for the Compact Muon Solenoidal (CMS) experiment at the Large Hadron Collider (LHC) of CERN. For a successful operation of Forward Silicon Pixel Tracker of the CMS, the cooling fluid, epoxies to be used and the filter capacitors of bias voltage supplies need to be radiation hard. It was also necessary to find out whether the cooling fluid would dissociate under the expected fluence and damage beryllium cooling channels of the Forward Silicon Pixel Discs. This paper is a report of our findings from the performed tests.

Atac, M.; Gobbi, B.; Cremaldi, L.; Hoffman, J.

2002-01-01

79

FPIX2: A radiation-hard pixel readout chip for BTeV  

SciTech Connect

A radiation-hard pixel readout chip, FPIX2, is being developed at Fermilab for the recently approved BTeV experiment. Although designed for BTeV, this chip should also be appropriate for use by CDF and DZero. A short review of this development effort is presented. Particular attention is given to the circuit redesign which was made necessary by the decision to implement FPIX2 using a standard deep-submicron CMOS process rather than an explicitly radiation-hard CMOS technology, as originally planned. The results of initial tests of prototype 0.25{micro} CMOS devices are presented, as are plans for the balance of the development effort.

David C. Christian et al.

2000-12-11

80

Ionizing radiation hardness of GaAs technologies  

SciTech Connect

The radiation response of several GaAs technologies to ionizing radiation has been investigated. Self-aligned gate (SAG) E/D GaAs Metal Semiconductor FET (MESFET), SAG AlGaAs/GaAs Modulation Doped FET (MODFET), and complementary-AlGaAs/GaAs Heterostructure Insulated Gate FET (C-HIGET) devices and circuits all demonstrated minimal sensitivity to total dose effects to 250 Mrad (GaAs). The heterostructure based technologies showed superior tolerance to high dose rate exposures, with upset levels exceeding 1 x 10/sup 10/ rads(GaAs)/s.

Listvan, M.A.; Vold, P.J.; Arch, D.K.

1987-12-01

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

A Radiation Hard MNOS CCD for Low Temperature Applications  

Microsoft Academic Search

P-buried channel charge-coupled devices (CCDs) with a 100 ?? sio2 and 1.2 ?? Si3N4 dual gate insulator have been fabricated and radiation tested. The CCDs are 105-and 150-bit 4-phase linear shift registers with double-level polysilicon gates. Most of the experimental data is obtained on p-buried channel devices because design considerations suggest that the p-buried channel structure will have the greatest

N. S. Saks; J. M. Killiany; P. R. Reid; W. D. Baker

1979-01-01

83

Hardness assurance for long-term ionizing radiation effects on bipolar structures  

Microsoft Academic Search

This work assessed the theoretical understanding of long-term ionization effects in semiconductor bipolar devices in support of developing hardness assurance techniques. The principal effort was directed at investigating transistor gain degradation mechanisms by use of models relating semiconductor physical and electrical parameters to surface properties. Ionizing radiation effects on surface properties were used to identify critical physical parameters for use

A. R. Hart; J. B. Smyth Jr.; J. P. Raymond; V. A. J. Vanlint

1978-01-01

84

Third-Generation Hard X-Ray Synchrotron Radiation Sources: Source Properties, Optics, and Experimental Techniques  

NASA Astrophysics Data System (ADS)

An expert survey of new synchrotron radiation sources and applications Synchrotron radiation continues to be an indispensable tool for physicists, materials scientists, chemists, and macromolecular crystallographers. Researchers in such fields as medicine, geological and environmental studies, structural genomics, and archaeology are finding ever more uses for this technology. This book discusses new third generation synchrotron radiation sources such as the Advanced Photon Source (APS), the European Synchrotron Radiation Facility (ESRF), and the Super Photon Ring-8 GeV (Spring-8). Topics such as accelerator design, radiation properties, and x-ray optics are given detailed treatment. With its coverage of both established and experimental techniques, applications, and specialized topics-all written by renowned experts and practitioners-Third Generation Hard X-ray Synchrotron Radiation Sources provides an indispensable, up-to-date account of the current state of the art.

Mills, Dennis M.

2002-03-01

85

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

86

Creation of a Radiation Hard 0.13 Micron CMOS Library at IHP  

NASA Astrophysics Data System (ADS)

To support space applications we will develop an 0.13 micron CMOS library which should be radiation hard up to 200 krad. By introducing new radiation hard design rules we will minimize IC-level leakage and single event latchup (SEL). To reduce single event upset (SEU) we will add two p-MOS transistors to all flip flops. For reliability reasons we will use double contacts in all library elements. The additional rules and the library elements will then be integrated in our Cadence mixed signal designkit, Virtuoso IC6.1 [1]. A test chip will be produced with our in house 0.13 micron BiCMOS technology, see Ref. [2].Thereafter we will doing radiation tests according the ESA specifications, see Ref. [3], [4].

Jagdhold, U.

2010-08-01

87

Radiation-hardened optoelectronic components - Detectors  

NASA Astrophysics Data System (ADS)

Recent research in the area of radiation-hardened optical detectors are surveyed. Conventional silicon photodiode structures, special radiation-hardened silicon photodiodes, and special double heterojunction AlGaAs/GaAs photodiodes are studied in neutron, gamma, pulsed X-ray and charged particle environments. Results are studied of this work and other research in this area are presented. These studies have shown that detectors can be made to function acceptably after exposures to neutron fluences of 10 to the 15th n/sq cm, total dose gamma exposures of 10 to the 8th rad (Si), and flash X-ray environments of 10 to the 8th rad/sec (Si). Detector structures that can operate through these conditions, prerad and postrad operational characteristics, and experimental conditions that produced these results are described.

Wiczer, James J.

1986-01-01

88

Space-Radiation Damage to Electronic Components and Materials.  

National Technical Information Service (NTIS)

Space radiation damage to electronic components and materials is of increasing concern as the nation's space capability develops. This report is a general compilation of information and is intended for use by electronic design engineers during early desig...

D. J. Hamman J. E. Drennan

1966-01-01

89

Components of Infrared Net Radiation in a Mountain Valley.  

National Technical Information Service (NTIS)

The infrared components of the surface radiation budget in a mountain valley have been investigated theoretically. Calculations were based on a set of winter and summer atmospheric soundings specifying temperature and moisture content and for two valley m...

T. B. McKee C. D. Whiteman

1977-01-01

90

Ultra-low-power radiation hard ADC for particle detector readout applications  

NASA Astrophysics Data System (ADS)

Radiation hard analog to digital converter (ADC) has been designed for future high energy physics experiments. The ADC has been designed in a commercial 130 nm CMOS process and it achieves 12-bit resolution, 25 MS/s sampling speed, 15 mW power consumption and hardness to at least 1.8 Megarad(Si) of total ionizing dose (TID). 16 ADC channels will be placed on one packaged silicon chip. The readout of the Liquid Argon Calorimeter of the ATLAS detector in the planned High-Luminosity Large Hadron Collider is one possible application for this ADC.

Mikkola, E. O.; Swaminathan, V.; Sivakumar, B.; Barnaby, H. J.

2013-04-01

91

10th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors  

NASA Astrophysics Data System (ADS)

The primary goal of the Conference is to review the present status of the Semiconductor Detector apparatuses in the field of High Energy or Astroparticle Physics. In both cases the requests on the detector systems are very demanding: very large instrumented surface, radiation hardness and high reliability. During the conference a large part of the talks will be devoted to describe the pixel and microstrip silicon-based detectors operated in the LHC experiments (Alice, Atlas, CMS, LHCb). The operational experience and the detector performance with the p-p runs 2010-2011 will be discussed. A fraction of the talks will describe possible LHC luminosity upgrade (HL-LHC) and recent developments on detector radiation hardness. The astroparticle detectors activity will also be reviewed. Topics related to the development and applications of detector electronics will be presented too. Finally semiconductor applications in different fields, like medical Dosimetry and Photomultipliers will be rapidly touched.

92

9th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors  

NASA Astrophysics Data System (ADS)

The primary goal of the Conference is to review the present status of the Semiconductor Detector apparatuses in the field of High Energy or Astroparticle Physics. In both cases the requests on the detector systems are very demanding: very large instrumented surface, radiation hardness and high reliability. During the conference a large part of the talks will be devoted to describe the pixel and microstrip silicon-based detectors installed in the LHC experiments (Alice, Atlas, CMS, LHCb). The first operational experience and the detector performance with cosmic rays run will be discussed. A fraction of the talks will describe possible LHC luminosity upgrade (SLHC) and recent developments on detector radiation hardness. The astroparticle detectors activity will also be reviewed. Topics related to the development and applications of detector electronics will be presented too. Finally semiconductor applications in different fields, like medical Dosimetry and Photomultipliers will be rapidly touched.

93

Radiation hardness of pseudomorphic HEMT and dual-gate GaAs MES-FET MMICs  

Microsoft Academic Search

The effects of Co-60 ?-ray irradiation under DC operation for two types of monolithic microwave integrated circuits (MMICs), Pseudomorphic HEMT (PHEMT) and Dual-Gate GaAs MES-FET, were investigated. These two types of MMICs have an excellent radiation hardness exceeding 107 rad(Si). We considered that degradation mechanisms of P-HEMT and MES-FET were the decrease of two dimensional electron gas (2DEG) carrier density

K. Matsuzaki; N. Nemoto; E. Nakamura; T. Akutsu; S. Matsuda; K. Yajima; H. Sasaki; M. Komaru; T. Katoh; T. Kashiwa; T. Asano; K. Mizuguchi

1997-01-01

94

Total dose radiation hard 0.5 ?m SOI CMOS transistors and 256 K SRAMs  

Microsoft Academic Search

The first 2 Mrad(SiO2) total dose hard 0.5 ?m CMOS SOI 256 K SRAM fabricated in SIMOX has been demonstrated. The address access time varied from 15 ns at 3.6 V to 19 ns at 3.0 V. The address access time was nearly independent of temperature from -55°C to 125°C and independent of radiation to 2×106 rad(SiO 2) for a

S. T. Liu; W. C. Jenkins

1996-01-01

95

Hard X-ray polarization measured with a Compton polarimeter at synchrotron radiation facility  

Microsoft Academic Search

A hard X-ray polarimeter with CdTe detectors has been developed for measurement of the degree of X-ray polarization at synchrotron radiation facilities. It utilizes 90° Compton scattering from the low Z targets. Measurements were performed at both facilities of the beamline BL38B1 in SPring-8 and the beamline BL14A in KEK-PF. The degrees of X-ray polarization for 20keV X-rays are 99%

F. Tokanai; H. Sakurai; S. Gunji; S. Motegi; H. Toyokawa; M. Suzuki; K. Hirota; S. Kishimoto; K. Hayashida

2004-01-01

96

Beam test of radiation hardness of a scintillating tile\\/fiber calorimeter  

Microsoft Academic Search

Radiation hardness of a scintillating tile\\/fiber calorimeter is studied by irradiating electromagnetic test modules with 2.5 GeV electrons at the KEK linac. The induced damage is evaluated in a 2 GeV electron test beam by measuring the reduction in pulse height after irradiation. The pulse height peak for 2 GeV electrons is found to decrease by 19.3 +\\/- 1.3% for

S. Funaki; K. Hara; T. Iinuma; T. Kaneko; S. Kim; K. Kondo; Y. Miyamoto; S. Miyashita; Y. Morita; I. Nakano; M. Okabe; J. Suzuki; H. Takahashi; K. Takikawa; N. Uemura; K. Yasuoka; F. Abe; A. Asami; A. Enomoto; K. Furukawa; N. Kamikubota; T. Kamitani; H. Kobayashi; M. Mishina; S. Ohsawa; Y. Yoshimura

1992-01-01

97

Radiation hardness of graded-gap Al x Ga 1? x As X-ray detectors  

Microsoft Academic Search

A study is presented of the influence of alpha-particle irradiation on the current and optical responses of graded-gap AlxGa1?xAs detectors for alpha-particle and X-ray radiation. The current response of the detector decreases by about an order of magnitude at an irradiation dose of 1010particles\\/cm2. Far better alpha-particle irradiation hardness is obtained from detectors with optical response. After an irradiation dose

A. Silenas; L. Dapkus; K. Pozela; J. Pozela; V. Juciene; V. Jasutis

2005-01-01

98

Radiation hardness of minimum ionizing particle detectors based on SiC p+n junctions  

Microsoft Academic Search

In this work we analyzed the radiation hardness of SiC p+\\/n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p+ emitter in an n-type epilayer with thickness equal to 55 ?m and donor doping ND = 2×1014 cm-3. The diode breakdown voltages were above 1000

F. Moscatelli; A. Scorzoni; A. Poggi; M. Bruzzi; S. Sciortino; S. Lagomarsino; G. Wagner; R. Nipoti

2005-01-01

99

Radiation hardness of polysiloxane scintillators analyzed by ion beam induced luminescence  

NASA Astrophysics Data System (ADS)

The radiation hardness of polysiloxane based scintillators has been measured by ion beam induced luminescence (IBIL). The light intensity as a function of the irradiation fluence with an He+ beam at 1.8 MeV (1.0 ?A/cm2) has been measured on undoped polymers synthesized with different amounts of phenyl units and on polysiloxanes doped with two different dye molecules (BBOT and Lumogen Violet) sensitizing the scintillation yield.

Quaranta, A.; Carturan, S.; Marchi, T.; Antonaci, A.; Scian, C.; Kravchuk, V. L.; Degerlier, M.; Gramegna, F.; Maggioni, G.

2010-10-01

100

Temporal and coherence properties of hard x-ray FEL radiation following Bragg diffraction by crystals  

NASA Astrophysics Data System (ADS)

At XFEL sources, coherent and time-resolved experiments will strongly depend on the properties of the incoming radiation passed through beamline optical elements to experimental stations. We investigate analytically and make numerical modeling of SASE pulse propagation through optical transport systems of hard X-ray FEL beamlines. The results on evolution of SASE XFEL pulses and its statistical properties during propagation through a double crystal monochromator in Bragg and Laue diffraction geometry are presented.

Bushuev, Vladimir; Samoylova, Liubov; Sinn, Harald; Tschentscher, Thomas

2011-09-01

101

A Radiation-Hard Analog Memory In The AVLSI-RA Process  

SciTech Connect

A radiation hardened analog memory for an Interpolating Pad Camber has been designed at Oak Ridge National Laboratory and fabricated by Harris Semiconductor in the AVLSI-RA CMOS process. The goal was to develop a rad-hard analog pipeline that would deliver approximately 9-bit performance, a readout settling time of 500ns following read enable, an input and output dynamic range of +/-2.25V, a corrected rms pedestal of approximately 5mV or less, and a power dissipation of less than 10mW/channel. The pre- and post-radiation measurements to 5MRad are presented.

Britton, C.L. Jr.; Wintenberg, A.L.; Read, K.F.; Simpson, M.L.; Young, G.R. [Oak Ridge National Lab., TN (United States); Clonts, L.G., Kennedy, E.J., Smith, R.S., Swann, B.K. [University of Tennessee, Knoxville (United States); Musser, J.A. [Indiana Univ., Bloomington, IN (United States). Dept. of Physics

1995-12-31

102

Testing of Radiation Hardness in the Extreme-Ultraviolet Spectral Region  

SciTech Connect

Currently we are commissioning a second multilayer-based beamline to study the radiation hardness of multilayers under extreme-ultraviolet (EUV) irradiation in an oxidizing atmosphere. Multilayer lifetime is one of the most important issues for the commercialization of extreme-ultraviolet lithography. The beamline employs a spherical multilayer mirror and a beryllium filter. The mirror demagnifies the source and reflects 13.4 nm radiation as well as visible light. The beryllium filter suppresses the visible light reflected by the mirror and provides also a barrier between the extremely clean storage ring vacuum and the water atmosphere of the test chamber.

Arp, U.; Tarrio, C.; Grantham, S.; Hill, S.; Dhez, P.; Lucatorto, T. B. [Electron and Optical Physics Division, National Institute of Standards and Technology, 100 Bureau Dr, MS 8410, Gaithersburg, MD 20899 (United States); Ermanoski, I. [Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)

2007-01-19

103

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

104

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

105

The isotropic-nematic phase transition of tangent hard-sphere chain fluids--pure components.  

PubMed

An extension of Onsager's second virial theory is developed to describe the isotropic-nematic phase transition of tangent hard-sphere chain fluids. Flexibility is introduced by the rod-coil model. The effect of chain-flexibility on the second virial coefficient is described using an accurate, analytical approximation for the orientation-dependent pair-excluded volume. The use of this approximation allows for an analytical treatment of intramolecular flexibility by using a single pure-component parameter. Two approaches to approximate the effect of the higher virial coefficients are considered, i.e., the Vega-Lago rescaling and Scaled Particle Theory (SPT). The Onsager trial function is employed to describe the orientational distribution function. Theoretical predictions for the equation of state and orientational order parameter are tested against the results from Monte Carlo (MC) simulations. For linear chains of length 9 and longer, theoretical results are in excellent agreement with MC data. For smaller chain lengths, small errors introduced by the approximation of the higher virial coefficients become apparent, leading to a small under- and overestimation of the pressure and density difference at the phase transition, respectively. For rod-coil fluids of reasonable rigidity, a quantitative comparison between theory and MC simulations is obtained. For more flexible chains, however, both the Vega-Lago rescaling and SPT lead to a small underestimation of the location of the phase transition. PMID:23883045

van Westen, Thijs; Oyarzún, Bernardo; Vlugt, Thijs J H; Gross, Joachim

2013-07-21

106

Experiences with shape memory alloy: robot grippers for submillimeter hard disk drive components  

NASA Astrophysics Data System (ADS)

Grippers for an automated assembly cell are being developed for handling individual sub-millimeter hard-disc drive components. Processing requirements dictate positive gripping with a strong actuator that meets clean room specifications. Proof-of-concept testing of shape memory alloy (SMA) as an actuator was performed. The response time of Ni-Ti 0.076 mm diameter shape memory wire was found to be 0.15 seconds under forced air convection conditions. Positioning accuracy was held to steady-state oscillations of 0.076 mm proving that SMA actuators meet performance requirements for a precision microactuator. SMA was then used for the actuation of several candidate gripper designs. One promising design consisted of a two-fingered gripper with integral spring sections at the arm base. SMA wire provided the closing actuation force and the spring sections returned the fingers to their rest position. Another design used an external spring to provide the gripping force, while the SMA wire provided the force required to open the gripper. The paper describes design methodologies and overall results. The addition of closed-loop control and improved heat dissipation mechanisms are needed before SMA materials can be used robustly as actuators for sub-mm robot grippers in high volume applications.

MacKenzie, Mark H.; An, Naomi M.; Giere, Matthew D.; Stori, James A.; Wright, Paul

1996-12-01

107

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

108

Upper lobe-dominant pulmonary fibrosis showing deposits of hard metal component in the fibrotic lesions.  

PubMed

We present a 54-year-old man employed in the field of hard metal manufacturing who complained of progressive dyspnea and weight loss. His chest radiograph showed bilateral fibrosis predominantly distributed in the upper lobes with bilateral pleural effusions, and a strong reduction in lung volume. Lung histopathology showed apical cap-like fibrosis but no giant cell interstitial pneumonia. Electron probe microanalysis detected tungsten deposits in the fibrotic region: we therefore considered this to be a case of hard metal disease. Hard metal disease should be considered as one possibility in the differential diagnosis of upper lobe-dominant pulmonary fibrosis. PMID:20930444

Kaneko, Yoshiko; Kikuchi, Norihiro; Ishii, Yukio; Kawabata, Yoshinori; Moriyama, Hiroshi; Terada, Masaki; Suzuki, Eiichi; Kobayashi, Masayoshi; Watanabe, Kouichi; Hizawa, Nobuyuki

2010-10-01

109

Jet quenching parameter in the gluon plasma with soft and hard components  

SciTech Connect

We put forward a model of jet quenching, in which a parton traversing the quark-gluon plasma loses its energy by interacting with hard thermal gluons through the exchanges by soft gluons. The hard gluons are modeled by the Hard Thermal Loop effective theory, the soft gluons by the chromo-magnetic condensate, the interaction mechanism between the two is Landau damping of the soft gluons by the hard ones. Within such a model, we calculate the jet quenching parameter of a gluon in SU(3) quenched QCD and find that, when the temperature varies from T = T{sub c} = 270 MeV to T = 900 MeV, the jet quenching parameter rises from q- circumflex = 0 to approximately 1.8 GeV{sup 2}/fm. We compare our results with the predictions of perturbative QCD and some other nonperturbative calculations.

Antonov, D.; Pirner, H.-J. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany)

2008-08-29

110

Soft X-ray components in the hard state of accreting black holes  

Microsoft Academic Search

Recent observations of two black hole candidates (GX 339-4 and J1753.5-0127) in the low-hard state (L{X}\\/L{Edd} ~= 0.003-0.05) suggest the presence of a cool accretion disk very close to the innermost stable orbit of the black hole. This runs counter to models of the low-hard state in which the cool disk is truncated at a much larger radius. We study

C. D'Angelo; Dimitrios Giannios; Cornelis Dullemond

2008-01-01

111

SPACE-RADIATION DAMAGE TO ELECTRONIC COMPONENTS AND MATERIALS  

Microsoft Academic Search

The results of experiments on the effects of space radiation on ; electronic devices and device materials normally used in circuits and systems are ; compiled. Electron, proton, and bremsstrahlung effects on the electrical and ; physical properties of semiconductor devices and materials are emphasized. Some ; results on other commonly used components are included, and metals are also ;

W. E. Chapin; D. J. Hamman; E. N. Wyler; D. Jones

1963-01-01

112

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.; Batten, J.; Troska, J. [Imperial Coll., London (United Kingdom)

1998-06-01

113

A low-power, radiation-hard gigabit serializer for use in the CMS electromagnetic calorimeter  

SciTech Connect

An integrated fiber-optic bit serializer and VCSEL (Vertical Cavity Surface Emitting Laser) driver has been constructed in radiation-hard complementary heterostructure GaAs FET (CHFET) technology. The serializer, which converts 20 parallel inputs into a high-speed serial output, consumes 60 mW at nominal supply voltage when operating at the Large Hadron Collider (LHC) word rate of 40 MHz (0.8-GB/s serial rate). The integrated driver directly drives a VCSEL and provides 10-mA switched current and 5 mA of prebias. The complete digital optical link thus consumes 90 mW.

Denes, P.; Baier, S.; Bussat, J.M.; Wixted, R.

2000-02-01

114

Development of radiation hard edgeless detectors with current terminating structure on p-type silicon  

NASA Astrophysics Data System (ADS)

The development of edgeless Si detectors was stimulated by the tasks of the total pp cross-section study in the TOTEM experiment at the Large Hadron Collider at CERN. For this, the dead region at the detector diced side should be reduced below 50 ?m. This requirement is successfully realized in edgeless Si detectors with current terminating structure (CTS), which are now operating at LHC. The development of the experiment and future LHC upgrade need the elaboration of radiation hard version of edgeless Si detectors. The current investigation represents an extension in understanding on edgeless detectors operation and development of a new issue - edgeless detectors with CTS on p-type Si.

Verbitskaya, E.; Eremin, V.; Ruggiero, G.

2011-12-01

115

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

116

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

117

Investigation of radiation hardness of SIS junctions for space borne radio astronomy  

NASA Astrophysics Data System (ADS)

Submillimeter astronomy with SIS (Superconductor-Insulator-Superconductor) mixers in space offer access to new wavelength windows and unsurpassed sensitivity. However little is known about the behavior of these devices in space. The Heterodyne Instrument (HIFI) aboard ESA's cornerstone Herschel Space Observatory (formely FIRST) satellite, scheduled for launch in 2007, will be among the first instrument using SIS technology in space. Within this context it is important to study possible radiation damage effects in SIS tunnel junctions. The particular devices used for HERSCHEL-HIFI-Band 1 (480-640 GHz) were fabricated with a new process based on negative resist E-beam lithography and very high current densities (15 kA/cm^2). In this paper, we report on radiation hardness tests with 10 MeV protons on the described high current density Nb/Al-AlOx/Nb junctions.

Péron, I.; Faury, G.; Delorme, Y.; Dauplay, F.; Lecomte, B.; Salez, M.; Schuster, K.-F.

2002-05-01

118

Radiation hardness of pn-CCDs for X-ray astronomy  

SciTech Connect

Results of an extensive radiation hardness test of a full depletion pn-Charge Coupled Device (pn-CCD) detector are presented. The pn-CCD is a new type of Charge Coupled Device designed for X-ray spectroscopy in ESA`s cornerstone X-ray Multi Mirror (XMM) satellite mission. The devices were irradiated with 10 MeV-protons with fluences up to 6.5 {center_dot} 10{sup 9} cm{sup {minus}2}. This is more than one order of magnitude higher than the equivalent proton radiation environment expected for the 10 year mission. The only effect to the device was a degradation of charge transfer efficiency (CTE) at temperatures around 120K. At XMM`s operating temperature between 140K and 170K the performance of the detector will not significantly change during the 10 year mission. The degradation of the CTE was studied, and a method to improve it is described.

Meidinger, N.; Strueder, L. [Max-Planck-Inst. fuer Extraterrestrische Physik, Garching (Germany); Soltau, H.; Zanthier, C. [KETEK GmbH, Oberschleissheim (Germany)

1995-12-01

119

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 10particles/cm 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 10neutrons/cm 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

120

First-principles study of the effects of mechanical strains on the radiation hardness of hexagonal boron nitride monolayers.  

PubMed

We investigate the strain effect on the radiation hardness of hexagonal boron nitride (h-BN) monolayers using density functional theory calculations. Both compressive and tensile strains are studied in elastic domains along the zigzag, armchair, and biaxial directions. We observe a reduction in radiation hardness to form boron and nitrogen monovacancies under all strains. The origin of this effect is the strain-induced reduction of the energy barrier to displace an atom. An implication of our results is the vulnerability of strained nanomaterials to radiation damage. PMID:23223902

Peng, Qing; Ji, Wei; De, Suvranu

2012-12-10

121

First-principles study of the effects of mechanical strains on the radiation hardness of hexagonal boron nitride monolayers  

NASA Astrophysics Data System (ADS)

We investigate the strain effect on the radiation hardness of hexagonal boron nitride (h-BN) monolayers using density functional theory calculations. Both compressive and tensile strains are studied in elastic domains along the zigzag, armchair, and biaxial directions. We observe a reduction in radiation hardness to form boron and nitrogen monovacancies under all strains. The origin of this effect is the strain-induced reduction of the energy barrier to displace an atom. An implication of our results is the vulnerability of strained nanomaterials to radiation damage.

Peng, Qing; Ji, Wei; de, Suvranu

2012-12-01

122

Analysis of the Temporal Variation of Radiation Balance Components in Arid Rice (Oryza Sativa L.) Culture.  

National Technical Information Service (NTIS)

The time variation of measured radiation balance components in a cultived rice area (Oryza sativa L.) under arid conditions in the Brazil central-west region was analysed. The relation between global solar radiation, radiation balance, reflected radiation...

J. E. Prates D. T. Coelho S. Steinmetz

1988-01-01

123

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

124

Hardness of covalent compounds: Roles of metallic component and d valence electrons  

NASA Astrophysics Data System (ADS)

Based on the detailed analysis of chemical bonds, we present a Vickers hardness expression for the covalency-dominant crystals such as transition-metal carbides and nitrides. Hardness is dependent not only on bond length, bond density, and ionicity of bond [F. M. Gao et al., Phys. Rev. Lett. 91, 015502 (2003)] but also on the metallicity of bond and orbital form in the crystal structure of a compound, and all of these parameters can be determined by first-principles calculations. The calculated hardness using our expression has a good agreement with the experimental values for known monocarbides, mononitrides of transition metals, and cubic Zr3N4 with Th3P4 structure. In addition, we have predicted the Vickers hardness of the recently predicted tetragonal BC3 and tetragonal B2CN, and the recently synthesized pyrite PtN2 and marcasite OsN2. Our method offers one useful technique to search for superhard materials in transition-metal carbides and nitrides.

Guo, Xiaoju; Li, Lei; Liu, Zhongyuan; Yu, Dongli; He, Julong; Liu, Riping; Xu, Bo; Tian, Yongjun; Wang, Hui-Tian

2008-07-01

125

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Low-threshold generation of harmonics and hard x radiation in a laser plasma. 1. Single-peak generation  

NASA Astrophysics Data System (ADS)

A source of hard x radiation based on a laser plasma has been studied under conditions such that parametric instabilities are driven in the plasma at low intensities of the pump radiation (below 10 GW/cm2). A qualitative interpretation of the observed effects is offered.

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

1993-02-01

126

Ferromagnetic transition of a two-component Fermi gas of hard spheres  

NASA Astrophysics Data System (ADS)

We use microscopic many-body theory to analyze the problem of itinerant ferromagnetism in a repulsive atomic Fermi gas of hard spheres. Using simple arguments we show that the available theoretical predictions for the onset of the ferromagnetic transition predict a transition point at a density (kFa˜1) that is too large to be compatible with the universal low-density expansion of the energy. We present variational calculations for the hard-sphere Fermi gas, in the framework of Fermi hypernetted chain theory, that shift the transition to higher densities (kFa˜1.8). Backflow correlations, which are mainly active in the unpolarized system, are essential for this shift.

Arias de Saavedra, F.; Mazzanti, F.; Boronat, J.; Polls, A.

2012-03-01

127

Polymer materials and component evaluation in acidic-radiation environments  

NASA Astrophysics Data System (ADS)

Polymeric materials used for cable/wire insulation, electrical connectors, O-rings, seals, and in critical components such as motors, level switches and resistive thermo-devices were evaluated under accelerated degradation conditions in combined radiation-oxidative elevated-temperature acidic-vapor (nitric/oxalic) environments relevant to conditions in isotope processing facilities. Experiments included the assessment of individual materials such as PEEK, polyimides, polyolefin based cable insulation, EPDM rubbers, various epoxy systems, commercial caulking materials as well as some functional testing of components. We discuss how to conduct laboratory experiments to simulate such complex hostile environments, describe some degradation effects encountered, and evaluate the impact on appropriate material and component selection.

Celina, M.; Gillen, K. T.; Malone, G. M.; Clough, R. L.; Nelson, W. H.

2001-07-01

128

Recent advancements in the development of radiation hard semiconductor detectors for S-LHC  

NASA Astrophysics Data System (ADS)

The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 1016 hadrons/cm2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed.

Fretwurst, E.; Adey, J.; Al-Ajili, A.; Alfieri, G.; Allport, P. P.; Artuso, M.; Assouak, S.; Avset, B. S.; Barabash, L.; Barcz, A.; Bates, R.; Biagi, S. F.; Bilei, G. M.; Bisello, D.; Blue, A.; Blumenau, A.; Boisvert, V.; Bolla, G.; Bondarenko, G.; Borchi, E.; Borrello, L.; Bortoletto, D.; Boscardin, M.; Bosisio, L.; Bowcock, T. J. V.; Brodbeck, T. J.; Broz, J.; Bruzzi, M.; Brzozowski, A.; Buda, M.; Buhmann, P.; Buttar, C.; Campabadal, F.; Campbell, D.; Candelori, A.; Casse, G.; Cavallini, A.; Charron, S.; Chilingarov, A.; Chren, D.; Cindro, V.; Collins, P.; Coluccia, R.; Contarato, D.; Coutinho, J.; Creanza, D.; Cunningham, L.; Dalla Betta, G.-F.; Dawson, I.; de Boer, W.; de Palma, M.; Demina, R.; Dervan, P.; Dittongo, S.; Dolezal, Z.; Dolgolenko, A.; Eberlein, T.; Eremin, V.; Fall, C.; Fasolo, F.; Ferbel, T.; Fizzotti, F.; Fleta, C.; Focardi, E.; Forton, E.; Garcia, C.; Garcia-Navarro, J. E.; Gaubas, E.; Genest, M.-H.; Gill, K. A.; Giolo, K.; Glaser, M.; Goessling, C.; Golovine, V.; González Sevilla, S.; Gorelov, I.; Goss, J.; Gouldwell Bates, A.; Grégoire, G.; Gregori, P.; Grigoriev, E.; Grillo, A. A.; Groza, A.; Guskov, J.; Haddad, L.; Härkönen, J.; Hauler, F.; Hoeferkamp, M.; Hönniger, F.; Horazdovsky, T.; Horisberger, R.; Horn, M.; Houdayer, A.; Hourahine, B.; Hughes, G.; Ilyashenko, I.; Irmscher, K.; Ivanov, A.; Jarasiunas, K.; Johansen, K. M. H.; Jones, B. K.; Jones, R.; Joram, C.; Jungermann, L.; Kalinina, E.; Kaminski, P.; Karpenko, A.; Karpov, A.; Kazlauskiene, V.; Kazukauskas, V.; Khivrich, V.; Khomenkov, V.; Kierstead, J.; Klaiber-Lodewigs, J.; Klingenberg, R.; Kodys, P.; Kohout, Z.; Korjenevski, S.; Koski, M.; Kozlowski, R.; Kozodaev, M.; Kramberger, G.; Krasel, O.; Kuznetsov, A.; Kwan, S.; Lagomarsino, S.; Lassila-Perini, K.; Lastovetsky, V.; Latino, G.; Lazanu, I.; Lazanu, S.; Lebedev, A.; Lebel, C.; Leinonen, K.; Leroy, C.; Li, Z.; Lindström, G.; Linhart, V.; Litovchenko, P.; Litovchenko, A.; Lo Giudice, A.; Lozano, M.; Luczynski, Z.; Luukka, P.; Macchiolo, A.; Makarenko, L. F.; Mandi?, I.; Manfredotti, C.; Manna, N.; Marti I Garcia, S.; Marunko, S.; Mathieson, K.; Melone, J.; Menichelli, D.; Messineo, A.; Metcalfe, J.; Miglio, S.; Mikuž, M.; Miyamoto, J.; Moll, M.; Monakhov, E.; Moscatelli, F.; Naoumov, D.; Nossarzewska-Orlowska, E.; Nysten, J.; Olivero, P.; Oshea, V.; Palviainen, T.; Paolini, C.; Parkes, C.; Passeri, D.; Pein, U.; Pellegrini, G.; Perera, L.; Petasecca, M.; Piemonte, C.; Pignatel, G. U.; Pinho, N.; Pintilie, I.; Pintilie, L.; Polivtsev, L.; Polozov, P.; Popa, A.; Popule, J.; Pospisil, S.; Pozza, A.; Radicci, V.; Rafí, J. M.; Rando, R.; Roeder, R.; Rohe, T.; Ronchin, S.; Rott, C.; Roy, A.; Ruzin, A.; Sadrozinski, H. F. W.; Sakalauskas, S.; Scaringella, M.; Schiavulli, L.; Schnetzer, S.; Schumm, B.; Sciortino, S.; Scorzoni, A.; Segneri, G.; Seidel, S.; Seiden, A.; Sellberg, G.; Sellin, P.; Sentenac, D.; Shipsey, I.; Sicho, P.; Sloan, T.; Solar, M.; Son, S.; Sopko, B.; Sopko, V.; Spencer, N.; Stahl, J.; Stolze, D.; Stone, R.; Storasta, J.; Strokan, N.; Sudzius, M.; Surma, B.; Suvorov, A.; Svensson, B. G.; Tipton, P.; Tomasek, M.; Tsvetkov, A.; Tuominen, E.; Tuovinen, E.; Tuuva, T.; Tylchin, M.; Uebersee, H.; Uher, J.; Ullán, M.; Vaitkus, J. V.; Velthuis, J.; Verbitskaya, E.; Vrba, V.; Wagner, G.; Wilhelm, I.; Worm, S.; Wright, V.; Wunstorf, R.; Yiuri, Y.; Zabierowski, P.; Zaluzhny, A.; Zavrtanik, M.; Zen, M.; Zhukov, V.; Zorzi, N.

2005-10-01

129

A radiation hard dipole magnet coils using aluminum clad copper conductors  

SciTech Connect

A C-type septum dipole magnet is located 600 mm downstream of the primary target in an external beam line of the AGS. Conventional use of fiber glass/epoxy electrical insulation for the magnet coils results in their failure after a relatively short running period, therefore a radiation hard insulation system is required. This is accomplished by replacing the existing copper conductor with a copper conductor having a thin aluminum skin which is anodized to provide the electrical insulation. Since the copper supports a current density of 59 A/mm/sup 2/, no reduction in cross sectional area can be tolerated. Design considerations, manufacturing techniques, and operating experience of a prototype dipole is presented. 3 refs., 4 figs.

Leonhardt, W.J.

1989-01-01

130

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

131

Evidence for a Photospheric Component in the Prompt Emission of the Short GRB 120323A and Its Effects on the GRB Hardness-Luminosity Relation  

NASA Astrophysics Data System (ADS)

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 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 peak ~ 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_i^{Band}}={(1.59+/- 0.84) \\times 10^{50} (E_{peak,i}^{rest})^{1.33+/- 0.07}\\ erg\\ s^{-1}}), which could be used as a possible redshift estimator for cosmology.

Guiriec, S.; Daigne, F.; Hascoët, R.; Vianello, G.; Ryde, F.; Mochkovitch, R.; Kouveliotou, C.; Xiong, S.; Bhat, P. N.; Foley, S.; Gruber, D.; Burgess, J. M.; McGlynn, S.; McEnery, J.; Gehrels, N.

2013-06-01

132

Mechanical properties of lunar materials under anhydrous, hard vacuum conditions: applications of lunar glass structural components  

SciTech Connect

Lunar materials and derivatives such as glass may possess very high tensile strengths compared to equivalent materials on earth because of the absence of hydrolytic weakening processes on the moon and in the hard vacuum of free space. Hydrolyzation of Si-O bonds at crack tips or dislocations reduces the strength of silicates by about an order of magnitude in earth environments. However, lunar materials are extremely anhydrous and hydrolytic weakening will be suppressed in free space. Thus, the geomechanical properties of the moon and engineering properties of lunar silicate materials in space environments will be very different than equivalent materials under earth conditions where the action of water cannot be conveniently avoided. Possible substitution of lunar glass for structural metals in a variety of space engineering applications enhances the economic utilization of the moon. 26 references, 3 figures, 2 tables.

Blacic, J.D.

1984-01-01

133

Hard scattering amplitude for the higher helicity components of the pion form factor  

Microsoft Academic Search

For obtaining the spin space wave function of the pion meson in the light-cone formalism from the naive quark model, it is necessary to take into account the Wigner rotation. Consequently there are higher helicity (lambda1+lambda2=+\\/-1) components in the light-cone spin space wave function of pion in addition to the usual helicity (lambda1+lambda2=0) components. For the pion electromagnetic form factor,

Fu-Guang Cao; Jun Cao; Tao Huang; Bo-Qiang Ma; B. Ma; F. Cao

1997-01-01

134

Design optimization of radiation-hard, double-sided, double-metal, AC-coupled silicon sensors  

Microsoft Academic Search

A double-sided, double metal, AC coupled readout silicon microstrip sensor (DDSMS) has been developed for the SVX-II, the upgrade vertex detector for CDF. Key issue in the development is to achieve sufficient radiation hardness for survival in the radiation environment of several kGy\\/yr. The required high-voltage capability and the reduction of the readout capacitance of the double-metal side were critical

T. Ohsugi; Y. Iwata; T. Ohmoto; T. Handa; K. Fujita; H. Kitabayashi; K. Sato; S. Satoh; R. Takashima; I. Nakano; K. Yamamoto; K. Yamamura

1999-01-01

135

Comparative study of the radiation hardness of an analog CMOS pipeline, discrete MOS transistors and interface traps in MOS capacitors  

Microsoft Academic Search

The ZEUS experiment at HERA employs a custom made analog pipeline, manufactured with a 2 ?m CMOS process. The standard transistor layout was not sufficiently radiation hard. After introducing thin oxide extension and guard bands, the pipeline worked after irradiation, up to 500 krad, with only minor performance degradation. The performance of the pipeline and of discrete transistors was studied

S. Bottcher; C. Coldewey; N. Croitoru; A. Seidman; H. Vogt

1995-01-01

136

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

NASA Astrophysics Data System (ADS)

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 3000 fb -1 which directly translates into significantly higher radiation damage. These upgrades consist of the installation of a 4th pixel layer, the insertable b-layer IBL, with a mean sensor radius of only 32 mm from the beam axis, before 2016/17. In addition, the complete pixel detector will be exchanged before 2020/21. Being very close to the beam, the radiation damage of the IBL sensors might be as high as 5 × 10 15 n eq cm - 2 at their end-of-life. The total fluence of the innermost pixel layer after the SLHC upgrade might even reach 2 × 10 16 n eq cm - 2 . To investigate the radiation hardness and suitability of the current ATLAS pixel sensors for these fluences, n + -in-n silicon pixel sensors from the ATLAS Pixel production have been irradiated by reactor neutrons to the IBL design fluence and been tested with pions at the SPS and with electrons from a 90 Sr source in the laboratory. The collected charge after IBL fluences was found to exceed 10 000 electrons per MIP at 1 kV of bias voltage which is in agreement with data collected with strip sensors. After SLHC fluences, still reliable operation of the devices could be observed with a collected charge of more than 5000 electrons per MIP.

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

2011-12-01

137

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

138

Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation  

SciTech Connect

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and {gamma}-ray irradiations at UC Santa Cruz (UCSC). Individual components on single-sided AC-coupled silicon strip detectors and on test structures were tested. Circuits fabricated in a radiation hard CMOS process and individual transistors fabricated using dielectric isolation bipolar technology were also studied. Results indicate that a silicon strip tracking detector system should have a lifetime of at least one decade at the SSC. 17 refs., 17 figs.

Ziock, H.J.; Milner, C.; Sommer, W.F. (Los Alamos National Lab., NM (USA)); Carteglia, N.; DeWitt, J.; Dorfan, D.; Hubbard, B.; Leslie, J.; O'Shaughnessy, K.F.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E. (California Univ., Santa Cruz, CA (USA). Inst. for Particle Physics); Ellison, J.A. (California Univ., Riverside, CA (USA)); Ferguson, P. (Missouri Univ., Rolla, MO (USA)); Giubellino

1990-01-01

139

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

PubMed

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. PMID:21258471

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

2010-08-02

140

Steady jets from radiatively efficient hard states in GRS 1915+105  

NASA Astrophysics Data System (ADS)

Recent studies of different X-ray binaries (XRBs) have shown a clear correlation between the radio and X-ray emission. We present evidence of a close relationship found between the radio and X-ray emission at different epochs for GRS 1915+105, using observations from the Ryle Telescope and Rossi X-ray Timing Explorer satellite. The strongest correlation was found during the hard state (also known as the “plateau” state), where a steady AU-scale jet is known to exist. Both the radio and X-ray emission were found to decay from the start of most plateau states, with the radio emission decaying faster. An empirical relationship of Sradio ? SX-ray? was then fitted to data taken only during the plateau state, resulting in a power-law index of ? 1.7±0.3, which is significantly higher than in other black hole XRBs in a similar state. An advection-flow model was then fitted to this relationship and compared to the universal XRB relationship as described by Gallo et al. (2003, MNRAS, 344, 60). We conclude that either (I) the accretion disk in this source is radiatively efficient, even during the continuous outflow of a compact jet, which could also suggest a universal turn-over from radiatively inefficient to efficient for all stellar-mass black holes at a critical mass accretion rate (dot{m}{c} ? 1018.5 g/s); or (II) the X-rays in the plateau state are dominated by emission from the base of the jet and not the accretion disk (e.g. via inverse Compton scattering from the outflow).

Rushton, A.; Spencer, R.; Fender, R.; Pooley, G.

2010-12-01

141

Problems of component discrimination in space radiation dosimetry.  

PubMed

Resolving the LET spectrum of environmental radiation in space for assessing dose equivalents creates special problems due to superposition effects. Three components of the radiation field in space, trapped protons, tissue disintegration stars, and neutrons, contribute the bulk of the total dose equivalent. While lack of discrimination of neutron recoil and trapped primary protons does not interfere with correct determination of the combined dose equivalent as such, the simultaneous bursts of several low-energy protons and alpha particles from tissue disintegration stars completely defy LET-resolution with conventional instrumentation. So far, the tissue star dose has been determined only semiquantitatively from nuclear emulsion data. The neutron spectrum in space shows a markedly higher relative fluence in the region beyond 5 MeV than the fission neutron spectrum. Therefore, its LET spectrum centers less heavily on LET values near the proton Bragg Peak. This would call for assigning a QF value of less than 10 to the neutron dose in space. Still more serious shortcomings exist with regard to LET interpretation of heavy primaries. PMID:1178828

Schaefer, H J

1975-06-18

142

Detection of a Spectral Break in the Extra Hard Component of GRB 090926A  

NASA Astrophysics Data System (ADS)

We report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other gamma-ray bursts, here we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.

Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chaplin, V.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashi, K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Llena Garde, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mehault, J.; Mészáros, P.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ripken, J.; Ritz, S.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Tanaka, Y.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Tierney, D.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Wilson-Hodge, C.; Winer, B. L.; Wood, K. S.; Wu, X. F.; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

2011-03-01

143

Design and Fabrication of a Radiation-Hard 500-MHz Digitizer Using Deep Submicron Technology  

SciTech Connect

The proposed International Linear Collider (ILC) will use tens of thousands of beam position monitors (BPMs) for precise beam alignment. The signal from each BPM is digitized and processed for feedback control. We proposed the development of an 11-bit (effective) digitizer with 500 MHz bandwidth and 2 G samples/s. The digitizer was somewhat beyond the state-of-the-art. Moreover we planned to design the digitizer chip using the deep-submicron technology with custom transistors that had proven to be very radiation hard (up to at least 60 Mrad). The design mitigated the need for costly shielding and long cables while providing ready access to the electronics for testing and maintenance. In FY06 as we prepared to submit a chip with test circuits and a partial ADC circuit we found that IBM had changed the availability of our chosen IC fabrication process (IBM 6HP SiGe BiCMOS), making it unaffordable for us, at roughly 3 times the previous price. This prompted us to change our design to the IBM 5HPE process with 0.35 µm feature size. We requested funding for FY07 to continue the design work and submit the first prototype chip. Unfortunately, the funding was not continued and we will summarize below the work accomplished so far.

K.K. Gan; M.O. Johnson; R.D. Kass; J. Moore

2008-09-12

144

Tests of Radiation-Hard Silicon Microstrip Sensors for CMS in S-LHC  

SciTech Connect

The tests are to study the performance of various silicon microstrip sensors that are sufficiently radiation-hard to be considered as candidates for the CMS outer (R > 25cm) tracker in the second phase of the currently envisioned S-LHC upgrade. The main goal of the beam test is to test Float Zone (FZ) and Magnetic Czochralski (MCz) silicon sensors that have been procured from Hamamatsu by the CMS collaboration as possible replacements for the CMS outer tracker for phase 2 operations. The detectors under test (DUT) will be isntalled in a cold box that contains 10 slots for modules based on CMS Tracker hybrids. Slots 1-4 and 7-10 are occupied by reference planes and slots 5 and 6 are reserved for DUTs. The box is cooled by Peltier elements in thermal contact with the top and bottom aluminum baseplates and is typically operated at around -25 C. A PCI based version of the CMS DAQ is used to read out the 10 slots based on triggers provided by beam scintillation counters. Given the low rate of beam particles the hybrid APVs will be operated in Peak mode, which maximizes the signal-to-noise performance of the readout chips. The internal clock operates at the LHC frequency of 40 MHz.

Luukka, Panja; Maenpaa, Teppo; Tuovinen, Esa; /Helsinki Institute of Physics; Spiegel, Lenny; /Fermilab; Flight, Robert; /Rochester U.

2011-02-21

145

Radiation-hard ASICs for optical data transmission in the first phase of the LHC upgrade  

NASA Astrophysics Data System (ADS)

We have designed two ASICs for possible applications in the optical links of a new layer of the pixel detector to be install inside the ATLAS Pixel detector for the first phase of the LHC luminosity upgrade. The ASICs include a high-speed driver for a VCSEL and a receiver/decoder to decode the signal received at a PIN diode to extract the data and clock. Both ASICs contain 4 channels for operation with a VCSEL or PIN array. The ASICs were designed using a 130 nm CMOS process to enhance the radiation-hardness. We have characterized the fabricated ASICs and the performance of the ASICs is satisfactory. The receiver/decoder properly decodes the bi-phase marked input stream with low PIN current and the driver can operate a VCSEL up to ˜5 Gb/s. The added functionalities are also successful, including redundancy to bypass a broken VCSEL or PIN channel, individual control of VCSEL current, and power-on reset circuit to set all VCSEL currents to a nominal value.

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

2011-06-01

146

Elastic-Like and Viscous-Like Components of the Shear Viscosity for Nearly Hard Sphere, Brownian Suspensions  

PubMed

The shear properties of Brownian, rigid spheres consisting of sterically stabilized, crosslinked polymethylmethacrylate (PMMA) particles were studied in suspension. Three different volume fractions were used to carry out this study. The suspensions' elastic-like and viscous-like components of the shear stress were measured by a recently developed technique utilizing cessation of steady shear. The elastic-like viscosity component, or the amount of stress retained at the instant of cessation divided by the shear rate, due to Brownian and possible interparticle forces, decreased in magnitude over the entire range of shear rates used (shear thinning). The decay of the elastic-like stress with time after cessation of flow was also analysed and found to fit a power law relation. The viscous-like component, or the amount of stress lost at the instant of cessation divided by the shear rate, is related to hydrodynamic interactions between and drag on particles and remained essentially constant with shear rate. These data are the first of this kind gathered for a model hard sphere system (i.e., mechanical means) and agrees well with results of Bender and Wagner (J. Colloid Interface Sci. 172, 171 (1995) who used an optical technique. PMID:9245312

Kaffashi; O'Brien; Mackay; Underwood

1997-03-01

147

Influence of nitrogen implantation into the buried oxide on the radiation hardness of silicon-on-insulator wafers  

NASA Astrophysics Data System (ADS)

In order to improve the total-dose radiation hardness of the buried oxide of separation by implanted oxygen silicon-on-insulator wafers, nitrogen ions were implanted into the buried oxide with a dose of 1016 cm-2, and subsequent annealing was performed at 1100 °C. The effect of annealing time on the radiation hardness of the nitrogen implanted wafers has been studied by the high frequency capacitance-voltage technique. The results suggest that the improvement of the radiation hardness of the wafers can be achieved through a shorter time annealing after nitrogen implantation. The nitrogen-implanted sample with the shortest annealing time 0.5 h shows the highest tolerance to total-dose radiation. In particular, for the 1.0 and 1.5 h annealing samples, both total dose responses were unusual. After 300-krad(Si) irradiation, both the shifts of capacitance-voltage curve reached a maximum, respectively, and then decreased with increasing total dose. In addition, the wafers were analysed by the Fourier transform infrared spectroscopy technique, and some useful results have been obtained.

Tang, Hai-Ma; Zheng, Zhong-Shan; Zhang, En-Xia; Yu, Fang; Li, Ning; Wang, Ning-Juan

2010-10-01

148

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

149

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

150

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

151

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 30MeV 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

152

Hard X-ray Radiation from Solar Flares in the Second Half of 2001: Preliminary Results of the SPR-N Experiment Onboard the Coronas-F Satellite  

NASA Astrophysics Data System (ADS)

The first results of the experiment with the SPR-N hard X-ray (20-100 keV) polarimeter onboard the Coronas-F observatory (the experiment started on August 15, 2001) are presented. Hard X-ray radiation was detected from several solar flares. The spectral and temporal parameters were determined and the polarization was estimated. Comparison with the GOES observations of thermal X-ray radiation shows that hard X-ray bursts occur at the growth phase of the thermal radiation and that they are associated with the bremsstrahlung of energetic electrons precipitating into the solar atmosphere.

Bogomolov, A. V.; Denisov, Yu. I.; Kuznetsov, S. N.; Lisin, D. V.; Logachev, Yu. I.; Morozov, O. V.; Myagkova, I. N.; Svertilov, S. I.; Zhitnik, I. A.; Ignat'ev, A. P.; Oparin, S. N.; Pertsov, A. A.; Stepanov, A. I.; Tindo, I. P.

2003-03-01

153

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

154

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Effect of compression of a laser plasma on the generation of harmonics and hard x radiation  

NASA Astrophysics Data System (ADS)

A compression of a plasma produced at a conical target by a low-intensity beam (q?10 GW/cm2) from a CO2 laser has been studied. The effect of this compression on the onset of the parametric instability responsible for the generation of harmonics and of hard x radiation has also been studied. A qualitative interpretation of the results is offered.

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

1993-02-01

155

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

156

An Area-Efficient 65 nm Radiation-Hard Dual-Modular Flip-Flop to Avoid Multiple Cell Upsets  

Microsoft Academic Search

A layout structure to avoid upsets due to Multiple Cell Upsets (MCUs) is proposed for rad-hard dual-modular Flip-Flops (FFs) called BCDMR (Bistable Cross-coupled Dual-Modular Redundancy) by separating critical components. We have fabricated a 65 nm chip including 30 kbit dual-modular FF arrays on twin-well and triple-well structures. High-energy broad-spectrum neutron irradiations reveal that no soft error is observed up to

Ryosuke Yamamoto; Chikara Hamanaka; Jun Furuta; Kazutoshi Kobayashi; Hidetoshi Onodera

2011-01-01

157

Method of using infrared radiation for assembling a first component with a second component  

DOEpatents

A method of assembling a first component for assembly with a second component involves a heating device which includes an enclosure having a cavity for inserting a first component. An array of infrared energy generators is disposed within the enclosure. At least a portion of the first component is inserted into the cavity, exposed to infrared energy and thereby heated to a temperature wherein the portion of the first component is sufficiently softened and/or expanded for assembly with a second component.

Sikka, Vinod K. (Oak Ridge, TN); Whitson, Barry G. (Corryton, TN); Blue, Craig A. (Knoxville, TN)

1999-01-01

158

Exact Solution of the One-Dimensional N-Component Bariev Model with a Hard-Core Repulsion under Open Boundary Conditions  

NASA Astrophysics Data System (ADS)

We analyse the integrable boundary conditions for the one-dimensional N-component generalized Bariev model with a hard-core repulsion. The Bethe ansatz equations and the energy spectrum are obtained in the framework of the nested Bethe ansatz method.

Ke, San-Min; Yue, Rui-Hong

2006-02-01

159

An exploratory analysis of the electron donor–acceptor complex formation between risperidone and iodine by principal component analysis, soft- and second-order hard-modelling approaches  

Microsoft Academic Search

An exploratory analysis of the electron donor–acceptor complex formation between risperidone and iodine has been done by a strategy equipped with rank augmentation, principal component analysis (PCA) and soft-modelling approach, orthogonal projection approach (OPA), followed by second-order hard-modelling in two non-aqueous solvents with different polarities. From the results of PCA and OPA, the correct number of chemical components and the

Masoumeh Hasani; Masoud Shariati-Rad; Hamid Abdollahi

2010-01-01

160

Radiation chemistry of polymeric components of radioactive waste  

SciTech Connect

The presentation covers fragments of research on the role of radiation chemistry in radioactive waste management. Radioactive waste often contains polymeric materials contaminated with actinides, which exhibit a activity for thousands of years. Rules of safety of transportation and environmental security of permanent storage demand the understanding of radiation chemistry of typical waste matrices. Due to a slow decay and a short range of penetration of a emitters, the experiments with actinides are not easy. 'Therefore, accelerated experiments have been performed using 10 MeV electrons of high intensity. That way chemical effects proceeding over thousands of years could be reduced to minutes in the laboratory. Simulation of the effect of a-radiolysis on polymers by low LET radiation is justified, because low LET radiation produces multi-ionization spurs resulting in the same chemistry as high LET radiation.

Dziewinski, J. J. (Jacek J.); Zagorski, Z. (Zbigniew)

2002-01-01

161

Response to ``Comment on: `New phase for one-component hard spheres' '' [J. Chem. Phys. 120, 11686 (2004)  

NASA Astrophysics Data System (ADS)

The nature of the phases observed in a hard-sphere system is considered. Simulation data, obtained via both Monte Carlo simulation and molecular dynamics support the existence of a new phase for hard spheres. The data include configurational snapshots, compressibility factors, radial distribution functions, order parameters, and self-intermediate scattering functions. To facilitate further investigation of the new phase, the relevant configuration files are available on the internet.

Wu, Guang-Wen; Sadus, Richard J.

2004-12-01

162

Quasi3D microstructure fabrication technique utilizing hard X-ray lithography of synchrotron radiation  

Microsoft Academic Search

Quasi-three-dimensional (3D) microstructure fabrication technique utilizing hard X-ray lithography (HXL) has been developed.\\u000a In this technique, as the intensity distribution of the X-rays is controlled by a newly developed bending mirror, the exposure\\u000a residual depth of polymethyl methacrylate (PMMA) resist is controlled over the exposed area. The maximum difference of depths\\u000a was approximately 50 ?m over the large area more

H. Mekaru; Y. Utsumi; T. Hattori

2002-01-01

163

DMILL, a mixed analog-digital radiation-hard BICMOS technology for high energy physics electronics  

Microsoft Academic Search

High Energy Physics experiments under preparation at CERN (Geneva, Switzerland) with the future LHC (Large Hadron collider) require a fast, low noise, very rad-hard, mixed analog-digital microelectronics VLSI technology. Readout electronics designed using such a technology for the central parts of the LHC particle detectors must withstand more than 10 Mrad (SiO2) and 1014 neutrons\\/cm2 over 10 years of operation.

M. Dentan; P. Abbon; E. Delagnes; N. Fourches; D. Lachartre; F. Lugiez; B. Paul; M. Rouger; R. Truche; J. P. Blanc; C. Leroux; E. Delevoye-Orsier; J. L. Pelloie; J. de Pontcharra; O. Flament; J. M. Guebhard; J. L. Leray; J. Montaron; O. Musseau; A. Vitez; L. Blanquart; J. J. Aubert; V. Bonzom; P. Delpierre; M. C. Habrard; A. Mekkaoui; R. Potheau; J. Ardelean; A. Hrisoho; D. Breton

1996-01-01

164

Proton radiation testing of laser optical components for NASA Jupiter Europa Orbiter Mission  

NASA Astrophysics Data System (ADS)

The Jupiter Europa Orbiter (JEO) is NASA's element of the joint Europa Jupiter System Mission (EJSM). Based on current trajectories, the spacecraft will spend a significant amount of time in the Jovian radiation belts. Therefore, research endeavors are underway to study the radiation effects on the various parts and components needed to implement the instruments. Data from these studies will be used for component selection and system design to ensure reliable operation throughout the mission duration. The radiation environment en route to Jupiter is nothing new for NASA designed systems, however, the long durations orbiting Jupiter and Europa present new challenges for radiation exposure. High-energy trapped electrons and protons at Jupiter dominate the expected radiation environment. Therefore, most of the initial component level radiation testing is being conducted with proton exposure. In this paper we will present in-situ monitoring of the optical transmission of various laser optical components during proton irradiation. Radiation induced optical attenuation of some components is less than would be expected, based on the authors experiences, and is attributed to the interaction of the protons with the materials. The results are an encouraging first step in screening these optical materials for spaceflight in a high radiation environment.

Thomes, W. Joe, Jr.; Cavanaugh, John F.; Ott, Melanie N.

2011-09-01

165

Optical components and systems for synchrotron radiation: an introduction  

SciTech Connect

A brief description of the nature and origins of synchrotron radiation is given with special reference to its geometrical optical properties and the use of storage rings as light souces. The geographical distribution of SR sources in the world is reviewed and some discussion of the level of experimental activity is given. Estimates of future levels of experimental activity are also made both for existing storage rings and those planned for the future. Calculations of the approximate number of mirrors and gratings that will be required are offered. Some general considerations are outlined showing how synchrotron radiation optical systems couple to the light source and indicating which parameters need to be maximized for best overall performance.

Howells, M.R.

1981-01-01

166

Effects of ionization radiation on BICMOS components for space application  

Microsoft Academic Search

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

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

2002-01-01

167

Effets de la dose, durcissement des composants. (Radiation dose effects, hardening of electronic components).  

National Technical Information Service (NTIS)

This course reviews the mechanism of interaction between ionizing radiation and a silicon oxide type dielectric, in particular the effect of electron-hole pairs creation in the material. Then effects of cumulated dose on electronic components and especial...

E. Dupont-Nivet

1991-01-01

168

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

169

Radiation hard fiber optics. Final technical report 24 Apr 78-24 Apr 80  

Microsoft Academic Search

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 antimony, cerium, boron, phosphorus and hydroxyl groups. The effects of such variations in the glass chemistry on the radiation inducted attenuation of the

R. E. Jaeger; M. Aslami

1981-01-01

170

Radiation-Hardness Studies of High OH- Content Quartz Fibres Irradiated with 24 GEV Protons  

NASA Astrophysics Data System (ADS)

We investigated the darkening of two high OH- content quartz fibres irradiated with 24 GeV protons at the CERN PS facility IRRAD. The two fibers, 0.6 mm quartz core diameter, one with hard plastic cladding (qp), the other with quartz cladding (qq), are both supplied by the US firm Polymicro Tech. Inc. (PT). These fibres were exposed at more than 1 Grad in 3 weeks. The fibres became opaque below 380 nm, and in the range 580-650 nm. Darkening under irradiation has variation versus dose similar to what we observed with electrons.

Merlo, Jean-Pierre; Cankocak, Kerem

2006-04-01

171

Radiation hardness of a wide-bandgap material by the example of SiC nuclear radiation detectors  

NASA Astrophysics Data System (ADS)

A polarization effect characteristically occurs in detectors based on wide-bandgap materials at considerable concentrations of radiation defects. The appearance of an electromotive force in the bulk of a detector is due to the long-term capture of carriers at deep levels related to radiation centers. The kinetics and strength of the polarization field have been determined. The carrier capture by the radiation centers can be controlled by varying the detector temperature, with a compromise reached at the “optimal” temperature between the generation current and the position of the deepest of the levels whose contribution to the loss of charge via capture is negligible. It has been found that the depth of a level of this kind (related to the energy gap width) is close to 1/3, irrespective of a material. The optimal temperatures are strictly individual for materials.

Ivanov, A. M.; Strokan, N. B.; Lebedev, A. A.

2012-05-01

172

Protecting LHC components against radiation resulting from colliding beam interactions  

SciTech Connect

Beam-induced energy deposition in the LHC high luminosity interaction region (IR) components due to both pp collisions and beam loss in the IR vicinity is a significant challenge for the design of the high luminosity insertions. It was shown in our previous studies that a set of collimators in the machine and absorbers within the low-beta quadrupoles would reduce both the peak power density and total heat load to tolerable levels with a reasonable safety margin. In this paper the results of further optimization and comprehensive MARS calculations are briefly described for the updated IP1 and IP5 layouts and a baseline pp-collision source term. Power density, power dissipation, accumulated dose and residual dose rates are studied in the components of the inner triplets including their TAS absorbers, the TAN neutral beam absorbers, separation dipoles, and quadrupoles of the outer triplets and possible collimators there. It is shown that the optimized absorbers and collimators provide adequate protection of all the critical components.

Nikolai V. Mokhov and Igor L. Rakhno

2001-06-26

173

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

174

The MONOS memory transistor - Application in a radiation-hard nonvolatile RAM  

NASA Astrophysics Data System (ADS)

The fabrication details and characteristics of the metal-oxide-nitride-oxide-silicon (MONOS) nonvolatile memory transistor, a device considered for radiation-hardened random-access memory (RAM) applications, are discussed. The insulator stack of the MONOS devices is fabricated prior to the gate oxidation step for the peripheral MOS devices and is also subjected to annealing steps used to enhance the radiation performance of MOS devices. The MONOS device has an endurance limit in excess of 10 to the 9th write/erase cycles, exhibits retention properties more than adequate for a RAM application, and does not experience permanent damage due to radiation levels up to 10 to the 6th rads.

Brown, W. D.; Jones, R. V.; Nasby, R. D.

1985-09-01

175

Low-mass, intrinsically-hard high temperature radiator. Final report, Phase I  

SciTech Connect

This paper reports on the investigation of layered ceramic/metal composites in the design of low-mass hardened radiators for space heat rejection systems. The investigation is part of the Strategic Defence Initiative. This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a large heat pipe radiator for waste heat rejection from a space nuclear power source. Composite materials evaluations were performed on combinations of refractory metals and ceramic powders. Fabrication experiments were performed to demonstrate weldability. Two titanium/titanium diboride composite tubes were successfully fabricated into potassium heat pipes and operated at temperatures in excess of 700C. Testing and analysis for composite tubes are described in the report. The study has verified the feasibility of using layered composites for forming thin-walled, light weight heat pipe tubes for use in hardened space radiators.

NONE

1990-07-15

176

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

177

New High Energy Electron Component of Earth Radiation Belt  

NASA Astrophysics Data System (ADS)

The Earth Radiation Belt (ERB) was discovered in the course of the first flights of Russian and American satellites with conventional instruments (gas discharge and scintillation counters), which made it possible to investigate many characteristics of trapped particles and simulate adequate radiation belt models. However, the experimental and theoretical evidence accumulated over recent time, needs more elaborate measurements for its interpretation. These measurements became feasible after the development of devices based on more perfect detectors (solid and gas-filled Cherenkov detectors, magnetic spectrometer, scintillation time-of-flight systems). The evidence requiring new direct measurements in the ERB was obtained in the late 1960s in the course of balloon flights carried out by Cosmophysics Laboratory of the Moscow Engineering and Physics Institute. In these flights a correlation between the high energy electron flux in the upper atmosphere and perturbations ofthe Earth's magnetosphere was established. This phenomenon could be explained assuming there exist high energy electron fluxes in the ERB. High energy electron fluxes in the ERB were recorded for the first time in the direct experiments carried out on board orbital station 'Salyut-6' (orbit altitude - 350 km, inclination 51.6 deg). A scintillation-Cherenkov telescope 'Elena' controlled by cosmonauts was preset to different programmed positions. The measurements were made in the periphery of the ERB, namely, in the part which goes as low as several hundred km in the Brazil Anomaly Region (BRA). The flux of electrons with energies above 30 MeV was up to 104 (m2s sr)-1.

Dmitrenko, V. V.; Galper, A. M.; Gratchev, V. M.; Kirillov-Ugryumov, V. G.; Ulin, S. E.; Voronov, S. A.

178

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

179

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

180

Radiation damage effects in Si materials and detectors and rad-hard Si detectors for SLHC  

Microsoft Academic Search

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, space charge concentration, and free carrier trapping. For LHC applications, where the total fluence is in the order of 1 × 1015 neq\\/cm2 for 10 years, the increase

Z. Li

2009-01-01

181

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

NASA Astrophysics Data System (ADS)

Sco X-1 is a low mass X-ray binary system and is the very first X-ray source to be discovered in 1962. From the recent observation of a resolved radio jet the souce has been included in the list of galactic microquasars. The observed spectral data in the 2-20 keV energy band fits a Free-free emission from a hot plasma. Above 20 keV, a hard tail has been reported on occasions. During our continuuing 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. Eventhough the total X-ray luminosity of the source different, the spectral nature of the source did not show any variation. The presence of hard X-ray flux is unmistakable. We present the spectra data in the hard X-ray band and discuss the results in terms of geometrical characteristics of the X-ray source and the observed temporal variations. It is proposed that while a core activity is similar to the micro-quasars, the absence of abrupt changes similar to GRS 1915+105, in the CGRO and RXTE data suggest a with much reduced magnitude.

Manchanda, R. K.

182

Penetrating radiation impact on NIF final optic components  

SciTech Connect

Goal of the National Ignition Facility (NIF) is to achieve thermonuclear ignition in a laboratory environment in inertial confinement fusion (ICF). This will enable NIF to service the DOE stockpile stewardship management program, inertial fusion energy goals, and advance scientific frontiers. All of these applications will make use of the extreme conditions that the facility will create in the target chamber. In the case of a prospected 20 MJ yield scenario, NIF will produce 10{sup 19} neutrons with DT fusion 14 MeV energy per neutron. There will also be high-energy x rays as well as solid, liquid, and gaseous target debris produced either directly or indirectly by the inertial confinement fusion process. A critical design issue is the protection of the final optical components as well as sophisticated target diagnostics in such a harsh environment.

Marshall, C.D.; Speth, J.A.; DeLoach, L.D.; Payne, S.A.

1996-10-15

183

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

184

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

NASA Astrophysics Data System (ADS)

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 10×10 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.; Cruz, E.; Martinez, M. I.; Montaño, L. M.; Paic, G.; Sandoval, A.

2006-09-01

185

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

186

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

187

JFET monolithic preamplifier with outstanding noise behavior 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. (Univ. di Pavia (Italy). Dipt. di Elettronica INFN, Milano (Italy). Sezione di Milano)

1993-08-01

188

Study of the radiation hardness of silicon sensors for the XFEL  

Microsoft Academic Search

Imaging experiments at the XFEL pose unprecedented requirements to the detectors in terms of radiation tolerance: Fluxes of up to 1016(12 keVphotons\\/cm2) corresponding to approximately 109 Gy in silicon, are expected. An irradiation station has been set up in the DORIS beam line F4, MOS test structures have been irradiated, and first results on the dose dependence of the C\\/V-characteristics,

E. Fretwurst; F. Januschek; R. Klanner; H. Perreyl; I. Pintilie; F. Renn

2008-01-01

189

Low-mass, intrinsically-hard high-temperature radiator. Final report, Phase I  

SciTech Connect

Thermacore, Inc. of Lancaster, Pennsylvania has completed a Phase I SBIR program to investigate the use of layered ceramic/metal composites in the design of low-mass hardened radiators for space heat rejection systems. The program is being monitored by the Los Alamos National Laboratory (LANL) for the Strategic Defense Initiative Organization (SDIO). This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a large heat pipe radiator for waste heat rejection from a space nuclear power source. This approach forms an attractive alternative to metal or silicon-carbon fiber reinforced metal heat pipes by offering a combination of low mass and improved fabricability. Titanium has been shown to have a yield strength too low at 875{degrees}K to be a useful radiator material. A silicon carbide fiber reinforced titanium material appears to have sufficient strength at 875{degrees}K. but cannot be welded due to the continuous fibers, and the preferred heat pipe working fluid (potassium) has been demonstrated to be incompatible with silicon carbide at 875{degrees}K. Moreover, titanium does not appear to be acceptable for radiators subjected to anticipated laser threats. As part of this effort, Thermacore performed composite material evaluations on combinations of refractory metals and ceramic powders. Layered composite tube samples with wall thicknesses as thin as 0.012 inches were developed. Fabrication experiments were performed that demonstrated the weldability of layered composites. Two titanium/titanium diboride composite tubes were successfully fabricated into potassium heat pipes and operated at temperatures in excess of 700{degrees}C. A hybrid composite tube was also fabricated into a potassium heat pipe. The tube was composed of alternating layers of niobium-1% zirconium foil and layers of a mixture of titanium powder and titanium diboride powder.

NONE

1990-06-15

190

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

191

Radiation Effects and Propagation in Optical Fibers and Components.  

NASA Astrophysics Data System (ADS)

The power series expansion method was used to solve the wave equation in step-index optical fiber. The cut off frequencies were calculated using 200 coefficients. The cutoff frequencies of TM modes were found to differ from those of TE modes. This difference, which is the error due to the approximations made, was calculated as a function of the relative refractive index difference (Delta ). The intermodal delay between the TE and TM mode was also calculated. The dispersion curves were plotted for several modes and values of Delta. A polarization control system was designed to be used in a coherent optical communication system, to restore the state of polarization (SOP) of the light output of a singlemode fiber. Rotating quarter wave and half wave plates were used to compensate for the changes in SOP. The sensitivity of the system was greatly improved by utilizing the heterodyne principle. The effects of neutron irradiation were studied on fiber optic materials (glasses), optical fibers, and photodetectors. In case of the heavy metal fluoride glasses, a red shift was found in the UV edge, which increased with neutron fluence. A very small amount of recovery was observed after three weeks. The shift could be due to the occurrence of color centers on irradiation and/or due to the shift in the urbach edge itself. The optical fibers showed an increase in the attenuation in the visible/near IR part of the spectrum. Fibers doped with P in the core showed more induced loss compared to the fibers doped with P in the cladding, and showed little or no recovery after a day. Radiation hardened fibers suffered far less induced loss on irradiation compared to the other fibers and also recovered in attenuation by a factor of 3 to 6 after a day. The responsivity of Si-PIN and Ge-PIN photodiodes degraded after irradiation. The relative responsivity was found to have a spectral dependence in case of Si-photodiode but was found to be independent of wavelength in case of Ge-photodiode. The primary photocurrent and current gain of Si-APD degraded after irradiation. This degradation is explained in terms of the defects introduced in the depletion region.

Gedam, Subhash Ganpatrao

1987-09-01

192

Radiation hardness measurements of new permanent magnet materials for high-intensity linac applications  

SciTech Connect

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The radiation resistance of samples of high-strength samarium cobalt permanent-magnet material has been studied. Samples of commercially available material were obtained from four different manufacturers. The remanent field of the samples was measured before and after the samples were irradiated with neutrons produced at the beam stop of the Los Alamos Neutron Science Center (LANSCE) proton accelerator.

Barlow, D.B.; Kraus, R.H.; Borden, M.J.

1998-12-31

193

Year-to-year variability of components of Earth's radiation budget according to satellite measurement data  

NASA Astrophysics Data System (ADS)

The year-to-year variability computed on satellite measurements with scanning radiometers carried by polar orbit satellites were analyzed. Solar-synchronous orbits carried out measurements over the same territory twice each day. The data wre reduced to mean monthly values of the fluxes of outgoing short and long-wave radiation. The analysis of year-to-year variability was based on mean monthly values of the radiation budget, its short and long-wave components and incident solar radiation. The results of computations of the standard deviations of the radiation budget and its components relative to their mean monthly values are represented in three full-page isoline maps. Regions of significant year-to-year variability: Sahara Desert, Kuroshio Current, Gulf Stream Region, Peruvian upwelling, near Cape Horn, in Gulf of Guinea, east of Newfoundland, tropical Atlantic near South America, deserts of Central Asia and South Africa, certain parts of Pacific Ocean , Norwegian Sea. The radiation budget albedo componet, whose main variability is associated with cloud cover is shown. The greatest variability is in the equatorial regions of the Pacific, Indian and Atlantic Oceans. The year-to-year variability of the long-wave component is shown; the highest values are in the Sahara Desert, along the east coast of the Asiatic continent and in North America. The satellite data made it possible to differentiate regions of year-to-year variability with an amplitude of the radiation temperature of the system of 4-5 K.

Marchuk, G. K.; Kondratyev, K. Y.; Avaste, O. A.; Kozoderov, V. V.; Kyarner, O. Y.

1985-05-01

194

Elastic-Like and Viscous-Like Components of the Shear Viscosity for Nearly Hard Sphere, Brownian Suspensions  

Microsoft Academic Search

The shear properties of Brownian, rigid spheres consisting of sterically stabilized, crosslinked polymethylmethacrylate (PMMA) particles were studied in suspension. Three different volume fractions were used to carry out this study. The suspensions’ elastic-like and viscous-like components of the shear stress were measured by a recently developed technique utilizing cessation of steady shear. The elastic-like viscosity component, or the amount of

Babak Kaffashi; Vincent T. O'Brien; Michael E. Mackay; Sylvia M. Underwood

1997-01-01

195

Radiation hardness, excess noise factor and short-term gain instability of vacuum phototriodes for the operation in pseudorapidity range 1.5<=?<=3.0 at CMS ECAL  

NASA Astrophysics Data System (ADS)

The operation of super radiation hard prototypes of vacuum fine-mesh phototriodes (VPT) proposed for application in CMS Endcap ECAL at the pseudorapidity of /?>=2.6 has been investigated in radiation fields up to 50kGy and neutron fluence of 7×1015neutroncm-2. It is shown that anode response and the excess noise factor of VPT are independent of given above radiation dose and neutron fluence. The results of VPT gain variation measurements under rapid changes of counting rate are presented for the operation in the pseudorapidity range /1.5<=?<=3.0.

Blinnikov, Yu.; Gousev, Yu.; Gninenko, S.; Grishin, V.; Goloubev, V.; Katchanov, V.; Lukianov, V.; Levchenko, L.; Moroz, F. V.; Mamaeva, G.; Postoev, V.; Seliverstov, D.; Ukhanov, D.; Yakorev, D.

2003-05-01

196

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

NASA Astrophysics Data System (ADS)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from 252Cf (0.5MeV/uradiation fluence was determined up to at least 109 fission-fragments/cm2 together with more than 3.5×109 neutrons/cm2 and 3×1010?-particles/cm2. This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong ?-source for about 48 h. The intrinsic timing resolution of a 100?m thick polycrystalline CVD diamond detector with a size of 1×1 cm2 was determined to ?int=(283±41)ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180?m show an intrinsic timing resolution of ?int=(106±21)ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%.

Oberstedt, S.; Borcea, R.; Bry?, T.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J.; Oberstedt, A.; Vidali, M.

2013-06-01

197

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

198

A seven-crystal Johann-type hard x-ray spectrometer at the Stanford Synchrotron Radiation Lightsource.  

PubMed

We present a multicrystal Johann-type hard x-ray spectrometer (~5-18 keV) recently developed, installed, and operated at the Stanford Synchrotron Radiation Lightsource. The instrument is set at the wiggler beamline 6-2 equipped with two liquid nitrogen cooled monochromators--Si(111) and Si(311)--as well as collimating and focusing optics. The spectrometer consists of seven spherically bent crystal analyzers placed on intersecting vertical Rowland circles of 1 m of diameter. The spectrometer is scanned vertically capturing an extended backscattering Bragg angular range (88°-74°) while maintaining all crystals on the Rowland circle trace. The instrument operates in atmospheric pressure by means of a helium bag and when all the seven crystals are used (100 mm of projected diameter each), has a solid angle of about 0.45% of 4? sr. The typical resolving power is in the order of E/?E ~ 10,000. The spectrometer's high detection efficiency combined with the beamline 6-2 characteristics permits routine studies of x-ray emission, high energy resolution fluorescence detected x-ray absorption and resonant inelastic x-ray scattering of very diluted samples as well as implementation of demanding in situ environments. PMID:23742527

Sokaras, D; Weng, T-C; Nordlund, D; Alonso-Mori, R; Velikov, P; Wenger, D; Garachtchenko, A; George, M; Borzenets, V; Johnson, B; Rabedeau, T; Bergmann, U

2013-05-01

199

An analysis of the SEU rate of microcircuits exposed by the various components of space radiation  

Microsoft Academic Search

In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR

V. F. Bashkirov; N. V. Kuznetsov; R. A. Nymmik

1999-01-01

200

Generation of the Soft Component of the Cosmic Radiation in Lead  

Microsoft Academic Search

The Rossi transition curve as obtained for the soft component of the cosmic radiation in the atmosphere, is compared with the curves obtained with a 10-cm absorbing lead layer just above and 86 cm above a counter arrangement. The stronger maximum of the curve obtained with the lead layer in the higher position may be attributed to unstable neutral particles

P. H. Stoker

1956-01-01

201

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

202

Anisotropic illumination in AGNs. The reflected component. Comparison to hard X-ray spectra from Seyfert Galaxies  

NASA Astrophysics Data System (ADS)

We calculate the reflection component predicted by the anisotropic illumination model of Henri & Petrucci \\cite{henri}. This component appears to be more important than for isotropic models. The overall X/gamma spectrum is found to be strongly angle-dependent. When the accretion disc is seen with a nearly edge-on orientation the reflection hump is weak, while a face-on viewing angle leads to a proeminent reflection hump with an equivalent reflection coefficient R ~ 50. Such reflection dominated Seyfert 1s galaxies are not observed. By fitting observed X/gamma spectra, we derive inclination angle theta ~ 70degr for MCG 8-11-11 and theta ~ 80degr for IC 4329a and NGC 4151. Although the model succeed in reproducing individual observed spectra, it requires all the Seyfert 1s observed in the X-ray band to be seen with large inclination angles. Such a situation is highly improbable. On the other hand, we show that the ionisation of a fair part of the reflecting disk could represent an interesting improvement of the model, consistent with the data and relaxing the constraints on the high energy cut-off in Seyfert galaxies.

Malzac, J.; Jourdain, E.; Petrucci, P. O.; Henri, G.

1998-08-01

203

Radiation hardness after very high neutron irradiation of minimum ionizing particle detectors based on 4H-SiC p+n junctions  

Microsoft Academic Search

In this work we analyzed the radiation hardness of SiC p+ n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p+ emitter in an n-type epilayer with thickness equal to 55 ?m and donor doping ND=2× 1014cm-3. The diode breakdown voltages were above 1000 V.

F. Moscatelli; A. Scorzoni; A. Poggi; M. Bruzzi; S. Sciortino; S. Lagomarsino; G. Wagner; I. Mandic; R. Nipoti

2006-01-01

204

Field Comparisons of Direct and Component Measurements of Net Radiation under Clear Skies.  

NASA Astrophysics Data System (ADS)

Accurate measurements of net radiation are basic to all studies of the surface energy budget. In preparation for an energy budget experiment significant differences were found between direct and component measurement of net radiation, which prompted this investigation of their cause. The instruments involved were an all-black single-dome Fritschen-type net pyrradiometer, two Eppley model 8 48 pyranometers, and an Eppley model PIR pyrgeometer. Each had recently been calibrated. The accuracy of the component instruments was considered first. Comparisons of about one hour on each of three nights between the pyrgeometer and five empirical formulas showed that the average departure over all formulas from the pyrgeometer average was 1%. Other comparisons between the pyrgeometer and an infrared thermometer viewing the surface yielded similar results. Alternate shading and unshading of the pyrgeometer looking upward during daytime resulted in a formula that was used to correct the downward longwave radiation under clear skies. The correction is dependent on wind speed, in contrast to a recent paper showing negligible dependence, but is in accord with earlier findings. Based on the manufacturer's specifications, the pyranometer calibrations were considered to be within 2% of the World Radiation Reference.Thus a series of experiments was carried out using what were believed to be reasonably accurate component measurements of net radiation and measurements from the net pyrradiometer. The results showed that the sensitivity of the latter was less in the longwave band than in the shortwave band in agreement with findings of others. Speculating on possible further dependence of sensitivity to the upward and downward streams of radiation, a method was developed to determine the magnitude of the individual net pyrmdiometer components. A reflective double-shell hemispherical cup was affixed to the upward or downward face of the net pyrradiometer such that linear regression could be applied to simultaneous measurements from the net pyrradiometer, pyranometer, pyrgeometer, and the inner cup temperature, assumed to he at air temperature, to estimate the individual components. Although a substantial difference in shartwave sensitivity was computed using this method, the result was not definitive because of the limited number and the narrow range of longwave observations. Nevertheless, the method can be employed in the field to verify uniform sensitivity of a net pyrradiometer's sensing surfaces to shortwave and longwave radiation. The method may have particular application to Fritschen-type net pyrradiometers of recently improved design after extended field use.

Duchon, Claude E.; Wilk, Gregory E.

1994-02-01

205

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

206

The degradation of TPX components by oxygen, elevated temperature, and ionizing radiation  

SciTech Connect

TPX is PMP or poly(4-methyl-1-pentene). It has several commercially important characteristics such as high optical transparency, high crystalline melting point, etc., leading to numerous applications including infrared windows, lenses, membranes, food packaging. The life components fabricated from this material may be limited by thermal oxidative and radiation-induced degradation. A preliminary review of the scientific literature was conducted to obtain relevant information on the effects of oxygen, moisture elevated temperature, and radiation on the chemical, thermodynamic, mechanical, and electrical properties of this material. Refs, figs, tabs.

Farmer, J.C.

1996-05-31

207

The Havemann-Taylor Fast Radiative Transfer Code: Exact fast radiative transfer for scattering atmospheres using Principal Components (PCs)  

NASA Astrophysics Data System (ADS)

The Havemann-Taylor Fast Radiative Transfer Code (HT-FRTC) has been developed for the simulation of highly spectrally resolved measurements from satellite based (i.e. Infrared Atmospheric Sounding Interferometer (IASI), Atmospheric Infrared Sounder (AIRS)) and airborne (i.e. Atmospheric Research Interferometer Evaluation System (ARIES)) instruments. The use of principle components enables the calculation of a complete spectrum in less than a second. The principal compoents are derived from a diverse training set of atmospheres and surfaces and contain their spectral characteristics in a highly compressed form. For any given atmosphere/surface, the HT-FRTC calculates the weightings (also called scores) of a few hundred principal components based on selected monochromatic radiative transfer calculations, which is far cheaper than thousands of channel radiance calculations. By intercomparison with line-by-line and other fast models the HT-FRTC has been shown to be accurate. The HT-FRTC has been successfully applied to simultaneous variational retrievals of atmospheric temperature and humidity profiles, surface temperature and surface emissivity over land. This is the subject of another presentation at this conference. The HT-FRTC has now also been extended to include an exact treatment of scattering by aerosols/clouds. The radiative transfer problem is solved using a discrete ordinate method (DISORT). Modelling results at high-spectral resolution for non-clear sky atmospheres obtained with the HT-FRTC are presented.

Havemann, Stephan; Thelen, Jean-Claude; Taylor, Jonathan P.; Keil, Andreas

2009-03-01

208

Estimating Retention Properties of Components of a Block Scale Fracture Network an Example from the Äspö Hard Rock Laboratory, Sweden.  

NASA Astrophysics Data System (ADS)

Crystalline rock is typically viewed as consisting of essentially impervious rock blocks separated by fractures. These fractures include both high-conductivity structures along which most of the flow takes place, and lower- conductivity fractures which are either hydraulically inactive, or carry very low flow. A number of tracer tests ("Tracer Retention Understanding Experiments"-TRUE) have been carried out along high-conductivity fractures (T >10-7 m2/s) since 1995 at the Äspö Hard Rock Laboratory (Sweden), with the purpose of characterizing their retention properties. However, from the safety assessment point of view, lower conductivity fractures (often referred to as "background fractures") could play an important role for the overall retention of radionuclides, since such fractures are most likely to be exposed to the initial release from a leaky radioactive waste canister. The most recent series of tracer tests performed at the Äspö HRL (TRUE Block Scale Continuation) address the issue of radionuclide retention in network pathway including a background fracture. Two tracer injections were performed in a forced flow field involving a high-conductivity fracture/fault (referred to as structure #19) and a pathway including a background fracture (referred to as BG1). These tracer experiments were carried out using a cocktail of tracers with varying sorption properties. In the first case, both injection and pumping were within structure #19, whereas in the second case tracers were injected in BG1 and pumped in structure #19. The Euclidean distance from injection location to extraction location is in both cases about 20 m. However, the hydrostructural model shows that while the actual pathway distance for the Structure #19 pathway may actually be 20 m, the pathway distance for the network pathway including BG1 is probably between 50 and 70 m. The retention properties of fracture BG1 were estimated indirectly, by inferring retention properties of structure #19 from the breakthrough curve of the first injection, and then using that result to deduce retention properties of BG1. We find that the retention material parameter group of BG1 is considerably lower than that of structure #19, but the hydrodynamic control parameter is one order of magnitude higher due to higher water residence time and smaller aperture. This is consistent with the significantly longer path length inferred from the hydrostructural model, and the geologic characterization of BG1 as a "non-fault" fracture. These results provide a clear indication that although the immobile zone retention properties are weaker in BG1, the overall retention is stronger for the BG1 pathway than for structure #19. These results indicate that assessment of transport properties needs to be made as a combination of discrete fracture network analysis to evaluate the pathway geometry, and immobile zone geochemical experiments to assess the retention properties of fractures and fracture populations. The uncertainty of the analysis interpretations presented has been evaluated quantitatively, demonstrating that the uncertainty about the hydrodynamic (pathway length and velocity) parameter group is greater than that for the retention (physical and geochemical) parameter group. This analysis, together with the quantitative analysis of uncertainty supports the development of more realistic retention properties of fractures in discrete fracture network simulations for hazardous chemical and radionuclide transport in crystalline rock.

Cheng, H.; Cvetkovic, V.; Winberg, A.; Dershowitz, W.

2006-12-01

209

The attenuation length of the high energy nucleonic component of the cosmic radiation near sea level  

Microsoft Academic Search

Summary  From the analysis of neutron data obtained at two widely separated stations, it is shown that during 1957 the attenuation\\u000a length of the high energy nucleonic component of the cosmic radiation near sea level was (138.1±0.8) g cm?2 at high geomagnetic latitudes. Analysis of data from a number of stations shows that the amplitudes of Forbush type decreases\\u000a increase by

K. G. McCracken; D. H. Johns

1959-01-01

210

Microclimate of a desert playa: evaluation of annual radiation, energy, and water budgets components  

Microsoft Academic Search

We set up two automatic weather stations over a playa (the flat floor of an undrained desert basin that, at times, becomes a shallow lake), approximately 65 km east-west by 130 km north-south, located in Dugway (40° 08N, 113° 27W, 1124 m above mean sea level) in northwestern Utah, USA, in 1999. These stations measured the radiation budget components, namely:

Esmaiel Malek

2003-01-01

211

Development of an Adaptive Optical System for Sub10-nm Focusing of Synchrotron Radiation Hard X-rays  

Microsoft Academic Search

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

H. Mimura; T. Kimura; H. Yokoyama; H. Yumoto; S. Matsuyama; K. Tamasaku; Y. Koumura; M. Yabashi; T. Ishikawa; K. Yamauchi

2011-01-01

212

Radiation environment on board Foton-M 3: the neutron component  

NASA Astrophysics Data System (ADS)

The recoverable capsule Foton-M 3 (ESA mission) was launched from Baikonur on 2007 September 14 and landed on the Russian-Kazakh border 12 days later. The spacecraft carried on board several ESA experiments. During this space mission a study has been performed on the neutron component of the radiation environment inside the capsule. Neutrons are a not avoidable component of the secondary radiation produced by interaction of primary radiation with the spacecraft shielding. Because of their high LET, neutrons could represent a main risk for both the electronic instruments and the health of the astronauts during space missions. Monte Carlo simulations performed by Geant4 code have been carried out using as input primary proton and alpha spectra, obtained by various tools (i.e. Creme 96, Omere, etc . . . ) and the neutron fluxes and doses, as a function of neutron energies, have been evaluated. The simulation results are compared with experimental data obtained by passive neutron detectors. In this study the effectiveness of various shielding materials useful in space mission has been also investigated.

Falzetta, Giuseppe; Zanini, Alba; Chiorra, Katia; Briccarello, Mauro; Belluco, Maurizio; Longo, Francesco; Jerse, Giovanna

213

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

214

Multiple, independent components of ultraviolet radiation mutagenesis in Escherichia coli K-12 uvrB5.  

PubMed Central

Reversion systems involving the lacZ53(amber) and leuB19)missense) mutations were developed to study the mutant frequency response of Escherichia coli K-12 uvrB5 (SR250) to ultraviolet radiation (254 nm). A one-hit mutant frequency response was discernible at ultraviolet radiation fluences below approximately 0.5 J m-2. At higher fluences the overall mutant frequency response could be resolved into one-hit and two-hit components. A new interpretation of the published data on E. coli K-12 indicates that SR250 is not unique in this respect. In addition, the Lac reversion system showed enhanced mutagenesis after ultraviolet radiation fluences of approximately 1 to 3 J m-2, whereas the Leu reversion system did not. We conclude that the complex ultraviolet radiation mutant frequency response curves for E. coli K-12 uvrB5 were the result of three independent mutagenic processes for Lac reversion and two for Leu reversion.

Smith, K C; Sargentini, N J

1979-01-01

215

Multiple, independent components of ultraviolet radiation mutagenesis in Escherichia coli K-12 uvrB5.  

PubMed

Reversion systems involving the lacZ53(amber) and leuB19)missense) mutations were developed to study the mutant frequency response of Escherichia coli K-12 uvrB5 (SR250) to ultraviolet radiation (254 nm). A one-hit mutant frequency response was discernible at ultraviolet radiation fluences below approximately 0.5 J m-2. At higher fluences the overall mutant frequency response could be resolved into one-hit and two-hit components. A new interpretation of the published data on E. coli K-12 indicates that SR250 is not unique in this respect. In addition, the Lac reversion system showed enhanced mutagenesis after ultraviolet radiation fluences of approximately 1 to 3 J m-2, whereas the Leu reversion system did not. We conclude that the complex ultraviolet radiation mutant frequency response curves for E. coli K-12 uvrB5 were the result of three independent mutagenic processes for Lac reversion and two for Leu reversion. PMID:387735

Smith, K C; Sargentini, N J

1979-11-01

216

Direct solar radiation up to 30 km and stratification of attenuation components in the stratosphere.  

PubMed

The balloon apparatus and some of the results of the direct solar radiation investigations up to 30 km in the middle belt of the Soviet Union in 1961-1965 are briefly described. Measurements of total direct solar radiation showed that the aerosol extinction properties in the free atmosphere are rather considerable, not only up to 30 km but also at the higher levels. The layered character of the stratospheric optical structure is demonstrated. The dynamics of layers and the possible influence of volcanic activity is discussed. Spectral investigations in the 0.35-13 micro region demonstrated that the stratospheric humidity is small, approximating 10(-6)-10(-5) g/g. The measurements in the visible spectrum confirmed that stratospheric aerosol component is essential, the stratospheric optical density being about 10(-4)-10(-3) km(-1). Comparison of the results of spectral and integral investigations indicates that the aerosol ext nction is also dominant above 30 km. PMID:20057727

Kondratiev, K Y; Nicolsky, G A; Badinov, I Y; Andreev, S D

1967-02-01

217

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

218

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

219

Nanopatterned ferroelectrics for ultrahigh density rad-hard nonvolatile memories  

Microsoft Academic Search

Radiation hard nonvolatile random access memory (NVRAM) is a crucial component for DOE and DOD surveillance and defense applications. NVRAMs based upon ferroelectric materials (also known as FERAMs) are proven to work in radiation-rich environments and inherently require less power than many other NVRAM technologies. However, fabrication and integration challenges have led to state-of-the-art FERAMs still being fabricated using a

Geoffrey L. Brennecka; Jeffrey Stevens; David Scrymgeour; Aaron V. Gin; Bruce Andrew Tuttle

2010-01-01

220

Rad Hard Active Media For Calorimeters  

Microsoft Academic Search

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

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

2006-01-01

221

Radiation hardness of passive fibre optic components for the future thermo-nuclear fusion reactor instrumentation links  

Microsoft Academic Search

Abstract: thermon uclearfusionreactor ITER will requireremote-hanA#0 equipment to monNNfl itsoperation anto allow hazard-freemand-freexAN durinitsfrequen tmain ten3#periods. Heavy shielded umbilicals willbe required tocon5N3 thesen2A5 an the actuators with theirinrx0flNj tationMultiplexinsen#0 signfl3turn out tobeessential to ease the umbilicalmancalx5 t. Wearecon33NxF0#fibre optic technxfljN , with itsintrinfl#wavelenflfl multiplexin(WDM) capabilities, tohanA5 these ITERmultiplexin...

A. Fernandez Fernandez

2001-01-01

222

Radiation hardness studies of CdTe and HgI2 for the SIXS particle detector on-board the BepiColombo spacecraft  

NASA Astrophysics Data System (ADS)

We report of the radiation hardness measurements that were performed in the developing work of a particle detector on-board ESA's forthcoming BepiColombo spacecraft. Two different high-Z semiconductor compounds, cadmium telluride (CdTe) and mercuric iodide (HgI2), were irradiated with 22 MeV protons in four steps to attain the estimated total dose of 10p/cm for the mission time. The performance of the detectors was studied before and after every irradiation with radioactive 55Fe source Mn K? 5.9 keV emission line. We studied the impact of the proton beam exposure on detector leakage current, energy resolution and charge collection efficiency (CCE). Also the reconstructive effect of annealing on radiation induced damage was tested for CdTe detector.

Ahoranta, J.; Uunila, M.; Huovelin, J.; Andersson, H.; Vainio, R.; Virtanen, A.; Kettunen, H.

2009-07-01

223

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

224

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

Microsoft Academic Search

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.

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

2008-01-01

225

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

226

Radiative transfer in the distorted and irradiated atmospheres of close binary components  

NASA Astrophysics Data System (ADS)

We studied the transfer of line radiation in the distorted and expanding atmospheres of close binary components. We assumed that the distortion of the atmosphere is caused by self rotation and tidal force exerted by the presence of the secondary component. The distortion is measured in terms of the ratio of angular velocities at the equator and pole (X), mass ratio of the two components (m2)/(m1), the ratio of centrifugal force to that of gravity at the equator of the primary (f) and ratio of the equatorial radius of the primary to the distance between the centres of gravity of the two components displaystyle (re)/(R). A seventh degree equation is obtained to describe the distorted surface in terms of the above mentioned parameters. We have used X=1 for uniform rotation throughout and used values f=0.1 and 0.5, (m2)/(m1)=1, and (re)/(R)=0.1, 0.3, and 0.5. The equation of line transfer is solved in the comoving frame of the expanding atmosphere of the primary using complete redistribution in the line. We used a linear law of velocity of expansion so that the density varies as r-3 where r is the radius of the star, satisfying the law of conservation of mass. We set va=0 and vb=10 mtu (mean thermal units) where va is the velocity at the surface of the primary with radius r=a(=5*E11) cm and vb is the velocity at the surface of the extended atmosphere with radius r=b(=1012) cm. We also computed lines in a static atmosphere with density changing as rho ~ r-1. We have considered a primary with an effective temperature T* and a point source of secondary with three different temperatures Tc equal to 2x 104 K, 3x 104 K, and 4x 104 K. The maximum change in line fluxes is noticed when the parameters (re)/(R) and f are changed, while the changes due to (m2)/(m1) are minimal. The expansion of the atmosphere produces P Cygni type line profiles. The incident radiation from the secondary increases the line fluxes and absorption in the centre of the line is replaced by emission.

Peraiah, A.; Srinivasa Rao, M.

2002-07-01

227

Fermi Observations of GRB 090510: A Short-Hard Gamma-ray Burst with an Additional, Hard Power-law Component from 10 keV TO GeV Energies  

Microsoft Academic Search

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

M. Ackermann; K. Asano; W. B. Atwood; M. Axelsson; L. Baldini; J. Ballet; G. Barbiellini; M. G. Baring; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; P. N. Bhat; E. Bissaldi; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. S. Briggs; M. Brigida; P. Bruel; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; S. Carrigan; J. M. Casandjian; C. Cecchi; Ö. Çelik; E. Charles; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; V. Connaughton; J. Conrad; C. D. Dermer; F. de Palma; B. L. Dingus; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; J. Finke; W. B. Focke; M. Frailis; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; J. Granot; I. A. Grenier; M.-H. Grondin; J. E. Grove; S. Guiriec; D. Hadasch; A. K. Harding; E. Hays; D. Horan; R. E. Hughes; G. Jóhannesson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; R. M. Kippen; J. Knödlseder; D. Kocevski; C. Kouveliotou; M. Kuss; J. Lande; L. Latronico; M. Lemoine-Goumard; M. Llena Garde; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; A. Makeev; M. N. Mazziotta; J. E. McEnery; S. McGlynn; C. Meegan; P. Mészáros; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; E. Moretti; A. Morselli; I. V. Moskalenko; S. Murgia; H. Nakajima; T. Nakamori; P. L. Nolan; J. P. Norris; E. Nuss; M. Ohno; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; W. S. Paciesas; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; R. Preece; S. Rainò; R. Rando; M. Razzano; S. Razzaque; A. Reimer; S. Ritz; A. Y. Rodriguez; M. Roth; F. Ryde; H. F.-W. Sadrozinski; A. Sander; J. D. Scargle; T. L. Schalk; C. Sgrò; E. J. Siskind; P. D. Smith; G. Spandre; P. Spinelli; M. Stamatikos; F. W. Stecker; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; K. Toma; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. Uehara; T. L. Usher; A. J. van der Horst; V. Vasileiou; N. Vilchez; V. Vitale; A. von Kienlin; A. P. Waite; P. Wang; C. Wilson-Hodge; B. L. Winer; X. F. Wu; R. Yamazaki; Z. Yang; T. Ylinen; M. Ziegler

2010-01-01

228

Industrial transfer and stabilization of a CMOS-JFET-bipolar radiation-hard analog-digital SOI technology  

SciTech Connect

DMILL technology integrates mixed analog-digital very rad-hard (> 10 Mrad and > 10{sup 14} neutron/cm{sup 2}) vertical bipolar, 0.8 {micro}m CMOS and 1.2 {micro}m PJFET transistors on SOI substrate. In this paper, after a presentation of the DMILL program goal, the authors discuss in more detail the main technological choices, the main milestones from the R and D to the industrial implementation, and the main results obtained after stabilization of the final process-flow in the MHS foundry.

Dentan, M.; Abbon, P.; Borgeaud, P. [CEA-DSM-DAPNIA Saclay, Gif-sur-Yvette (France)] [and others

1999-08-01

229

Radiation damage and repair in cells and cell components. Part 2. Physical radiations and biological significance. Final report  

SciTech Connect

The report comprises a teaching text, encompassing all physical radiations likely to be of biological interest, and the relevant biological effects and their significance. Topics include human radiobiology, delayed effects, radiation absorption in organisms, aqueous radiation chemistry, cell radiobiology, mutagenesis, and photobiology. (ACR)

Fluke, D.J.

1984-08-01

230

Occurrence and source characteristics of the high-latitude components of Jovian broadband kilometric radiation  

NASA Astrophysics Data System (ADS)

Ulysses had a "distant encounter" with Jupiter when it was within 0.8 AU of the planet during February, 2004. The passage of the spacecraft was from north to south, and observations of the Jovian radio waves were carried out for a few months from high to low latitudes (+80° to +10°) of Jupiter. The statistical study performed during this "distant encounter" event provided the occurrence characteristics of the Jovian broadband kilometric radiation (bKOM), including the high-latitude component as follows: (1) the emission intensity of bKOM was found to have a sinusoidal dependence with respect to the central meridian longitude (CML), showing a broad peak at ˜180°, (2) bKOM was preferably observed in the magnetic latitudinal range from ˜+30° to +90°, and the emission intensities at the high latitudes were found to be two times larger than that at the equatorial region, and (3) the emission intensity was controlled possibly by the sub solar longitude (SSL) of Jupiter. The intensity had a sharp peak around SSL ˜210°. A 3D ray tracing approach was applied to the bKOM in order to examine the source distribution. It was suggested that: (1) the R-X mode waves generated through the Cyclotron Maser Instability process would be unable to reproduce the intense high-latitude component of the bKOM, (2) the L-O mode, which was assumed to be generated at frequencies near the local plasma frequency, was considered to be the dominant mode for past and present observations at mid- and high-latitudinal regions, and (3) the high-latitude component of bKOM was found to have a source altitude of 0.9-1.5 Rj (Rj: Jovian radii), and to be distributed along magnetic field lines having L>10.

Kimura, Tomoki; Tsuchiya, Fuminori; Misawa, Hiroaki; Morioka, Akira; Nozawa, Hiromasa

2008-06-01

231

Metal/ceramic composite heat pipes for a low-mass, intrinsically-hard 875 K radiator  

NASA Astrophysics Data System (ADS)

The first phase of a development program was recently completed to investigate the use of layered metal/ceramic composites in the design of low-mass hardened radiators for space heat rejection systems. This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a large heat pipe radiator for waste heat rejection from a space nuclear power source. This approach forms an attractive alternative to carbon/carbon, or silicon-carbide fiber reinforced metal heat pipes by offering a combination of low mass and improved fabricability. An approach for fabrication of layered composite thin-walled heat pipes for use in hardened space radiators was developed. Potassium heat pipes with wall thicknesses as low as 0.3 mm have been built and tested. Wall thicknesses as low as 0.13 mm are believed to be achievable with this approach.

Rosenfeld, John H.; Ernst, Donald M.; Nardone, Vincent C.

232

Ionizing-radiation-induced color centers in YAG, Nd:YAG, and Cr:Nd:YAG: Developing and analyzing a radiation-hard laser gain medium  

NASA Astrophysics Data System (ADS)

This report presents results from a series of experiments in which YAG samples (undoped, as well as doped with Nd and Cr3+) were exposed to ionizing radiation (gamma rays and UV). These experiments were performed for the purpose of investigating the various photodarkening processes taking place in these materials in response to the ionizing radiation. The purpose of this investigation was to establish whether and how co-doping YAG with Cr3+ improves the material's resistance to photodarkening due to the ionizing radiation. The experiments tracked time-resolved transmittance of the samples at 1064 nm in immediate response a pulsed exposure to the ionizing radiation, as well as steady-state spectrally-resolved changed in the samples' optical absorption after the irradiation. The investigation revealed a number of photodarkening processes occurring in the samples in response to the ionizing radiation, both transient and permanent. It was further revealed that inclusion of Cr3+ ions in YAG significantly reduces these photodarkening processes, improving the material's radiation resistance. It was observed that materials containing at least 0.5 at% Cr3+ are essentially radiation-hardened, resisting both transient and steady-state changes in transmittance observed in the materials not containing Cr3+.

Glebov, Boris L.

233

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

2012-08-16

234

Metal\\/ceramic composite heat pipes for a low-mass, intrinsically-hard 875 K radiator  

Microsoft Academic Search

Thermacore, Inc. of Lancaster, Pennsylvania has recently completed Phase I of a development program to investigate the use of layered metal\\/ceramic composites in the design of low-mass hardened radiators for space heat rejection systems. This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a

John H. Rosenfeld; Donald M. Ernst; Vincent C. Nardone

1991-01-01

235

Photon multiplicity in the hard radiation of 150 GeV electrons in an aligned germanium crystal  

Microsoft Academic Search

Mean values m of photon multiplicity in the radiation of 150 GeV electrons directed at and near the axis of a 0.185 mm thick Ge crystal cooled to 100 K have been deduced from the measurements of pair conversion probabilities. Depending on the distribution of multiplicity assumed, values of m ranging from 3.8 to 4.3 are obtained for the previously

A. Belkacem; G. Bologna; M. Chevallier; N. Cue; M. J. Gaillard; R. Genre; J. C. Kimball; R. Kirsch; B. B. Marsh; J. P. Peigneux; J. C. Poizat; J. Remillieux; D. Sillou; Maurice Spighel; C. R. Sun

1988-01-01

236

THE EFFECT OF CORONAL RADIATION ON A RESIDUAL INNER DISK IN THE LOW/HARD SPECTRAL STATE OF BLACK HOLE X-RAY BINARY SYSTEMS  

SciTech Connect

Thermal conduction between a cool accretion disk and a hot inner corona can result in either evaporation of the disk or condensation of the hot corona. At low mass accretion rates, evaporation dominates and can completely remove the inner disk. At higher mass accretion rates, condensation becomes more efficient in the very inner regions, so that part of the mass accretes via a weak (initially formed) inner disk which is separated from the outer disk by a fully evaporated region at mid radii. At still higher mass accretion rates, condensation dominates everywhere, so there is a continuous cool disk extending to the innermost stable circular orbit. We extend these calculations by including the effect of irradiation by the hot corona on the disk structure. The flux which is not reflected is reprocessed in the disk, adding to the intrinsic thermal emission from gravitational energy release. This increases the seed photons for Compton cooling of the hot corona, enhancing condensation of the hot flow, and reinforcing the residual inner disk rather than evaporating it. Our calculations confirm that a residual inner disk can coexist with a hard, coronally dominated spectrum over the range of 0.006< m-dot <0.016 (for {alpha} = 0.2). This provides an explanation for the weak thermal component seen recently in the low/hard state of black hole X-ray binary systems.

Liu, B. F. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011 (China); Done, C. [Department of Physics, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Taam, Ronald E., E-mail: bfliu@ynao.ac.cn, E-mail: r-taam@northwestern.edu, E-mail: bfliu@nao.cas.cn [Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States)

2011-01-01

237

Metal/ceramic composite heat pipes for a low-mass, intrinsically-hard 875 K radiator. [Ti  

SciTech Connect

Thermacore, Inc. of Lancaster, Pennsylvania has recently completed Phase I of a development program to investigate the use of layered metal/ceramic composites in the design of low-mass hardened radiators for space heat rejection systems. This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a large heat pipe radiator for waste heat rejection from a space nuclear power source. This approach forms an attractive alternative to carbon/carbon, or silicon-carbide fiber reinforced metal heat pipes by offering a combination of low mass and improved fabricability. Thermacore and United Technologies Research Center have jointly developed an approach for fabrication of layered composite thin-walled heat pipes for use in hardened space radiators. Potassium heat pipes with wall thicknesses as low a 0.3 mm have been built and tested. Wall thicknesses as low as 0.13 mm are believed to be achievable with this approach.

Rosenfeld, J.H.; Ernst, D.M. (Thermacore, Inc., 780 Eden Road, Lancaster, Pennsylvania (USA)); Nardone, V.C. (United Technologies Research Center, Silver Lane, MS 13, East Hartford, Connecticut (USA))

1991-01-10

238

Metal/ceramic composite heat pipes for a low-mass, intrinsically-hard 875 K radiator  

NASA Astrophysics Data System (ADS)

Thermacore, Inc. of Lancaster, Pennsylvania has recently completed Phase I of a development program to investigate the use of layered metal/ceramic composites in the design of low-mass hardened radiators for space heat rejection systems. This effort evaluated the use of layered composites as a material to form thin-walled, vacuum leaktight heat pipes. The heat pipes would be incorporated into a large heat pipe radiator for waste heat rejection from a space nuclear power source. This approach forms an attractive alternative to carbon/carbon, or silicon-carbide fiber reinforced metal heat pipes by offering a combination of low mass and improved fabricability. Thermacore and United Technologies Research Center have jointly developed an approach for fabrication of layered composite thin-walled heat pipes for use in hardened space radiators. Potassium heat pipes with wall thicknesses as low a 0.3 mm have been built and tested. Wall thicknesses as low as 0.13 mm are believed to be achievable with this approach.

Rosenfeld, John H.; Ernst, Donald M.; Nardone, Vincent C.

1991-01-01

239

A comparison of field-only electronic portal imaging hard copies with double exposure port films in radiation therapy treatment setup confirmation to determine its clinical application in a radiotherapy center  

Microsoft Academic Search

Purpose: To determine in which treatment sites field-only hard copy electronic portal images (EPI) captured during a treatment exposure could replace traditional double exposed port films in a busy radiation oncology department.Methods and Materials: The three linear accelerators in the William Buckland Radiotherapy Centre (WBRC) at the Alfred Hospital in Melbourne are each equipped with an electronic portal imaging device

Kay Hatherly; Josephine Smylie; Alan Rodger

1999-01-01

240

Radiation damage and repair in cells and cell components. Final report. Part 1  

SciTech Connect

An overview of research into the direct action of ionizing radiation, especially the effect of radiation temperature, primarily upon enzymes, into induced repair, and into S.O.S.-related phenomena, is presented. (ACR)

Fluke, D.J.

1984-01-01

241

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

Microsoft Academic Search

Second-order global hard-modelling was applied to resolve the complex formation between Co2+, Ni2+, and Cd2+ 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

Masoud Shariati-Rad; Masoumeh Hasani

2009-01-01

242

A novel epitaxially grown LSO-based thin-film scintillator for micro-imaging using hard synchrotron radiation.  

PubMed

The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency: a novel scintillator based on doped Lu(2)SiO(5) (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well. It delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences. PMID:20724778

Douissard, Paul Antoine; Cecilia, Angelica; Martin, Thierry; Chevalier, Valentin; Couchaud, Maurice; Baumbach, Tilo; Dupré, Klaus; Kühbacher, Markus; Rack, Alexander

2010-07-29

243

Characterisation of a radiation hard front-end chip for the vertex detector of the LHCb experiment at CERN  

NASA Astrophysics Data System (ADS)

The Beetle is a 128 channel analog pipelined readout chip which is intended for use in the silicon vertex locator (VELO) of the LHCb experiment at CERN. The Beetle chip is specially designed to withstand high radiation doses. Two Beetle1.1 chips bonded to a silicon strip detector have been tested with minimum ionizing particles. The main goal was to measure the signal-to-noise (S/N) ratio of the Beetle1.1 connected to a prototype VELO detector. Furthermore we investigated the general behaviour of the Beetle1.1. In this note we present the chip architecture, the measured (S/N) numbers as well as some characteristics (e.g. risetime, spillover) of the Beetle1.1 chip. Results from a total ionizing dose irradiation test are reported.

van Bakel, N.; Baumeister, D.; van Beuzekom, M.; Bulten, H. J.; Feuerstack-Raible, M.; Jans, E.; Ketel, T.; Klous, S.; Löchner, S.; Sexauer, E.; Smale, N.; Snoek, H.; Trunk, U.; Verkooijen, H.

2003-08-01

244

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

245

Developments for radiation hard silicon detectors by defect engineering-results by the CERN RD48 (ROSE) Collaboration  

NASA Astrophysics Data System (ADS)

This report summarises the final results obtained by the RD48 collaboration. The emphasis is on the more practical aspects directly relevant for LHC applications. The report is based on the comprehensive survey given in the 1999 status report (RD48 3rd Status Report, CERN/LHCC 2000-009, December 1999), a recent conference report (Lindström et al. (RD48), and some latest experimental results. Additional data have been reported in the last ROSE workshop (5th ROSE workshop, CERN, CERN/LEB 2000-005). A compilation of all RD48 internal reports and a full publication list can be found on the RD48 homepage (http://cern.ch/RD48/). The success of the oxygen enrichment of FZ-silicon as a highly powerful defect engineering technique and its optimisation with various commercial manufacturers are reported. The focus is on the changes of the effective doping concentration (depletion voltage). The RD48 model for the dependence of radiation effects on fluence, temperature and operational time is verified; projections to operational scenarios for main LHC experiments demonstrate vital benefits. Progress in the microscopic understanding of damage effects as well as the application of defect kinetics models and device modelling for the prediction of the macroscopic behaviour has also been achieved but will not be covered in detail.

Lindström, G.; Ahmed, M.; Albergo, S.; Allport, P.; Anderson, D.; Andricek, L.; Angarano, M. M.; Augelli, V.; Bacchetta, N.; Bartalini, P.; Bates, R.; Biggeri, U.; Bilei, G. M.; Bisello, D.; Boemi, D.; Borchi, E.; Botila, T.; Brodbeck, T. J.; Bruzzi, M.; Budzynski, T.; Burger, P.; Campabadal, F.; Casse, G.; Catacchini, E.; Chilingarov, A.; Ciampolini, P.; Cindro, V.; Costa, M. J.; Creanza, D.; Clauws, P.; Da Via, C.; Davies, G.; De Boer, W.; Dell'Orso, R.; De Palma, M.; Dezillie, B.; Eremin, V.; Evrard, O.; Fallica, G.; Fanourakis, G.; Feick, H.; Focardi, E.; Fonseca, L.; Fretwurst, E.; Fuster, J.; Gabathuler, K.; Glaser, M.; Grabiec, P.; Grigoriev, E.; Hall, G.; Hanlon, M.; Hauler, F.; Heising, S.; Holmes-Siedle, A.; Horisberger, R.; Hughes, G.; Huhtinen, M.; Ilyashenko, I.; Ivanov, A.; Jones, B. K.; Jungermann, L.; Kaminsky, A.; Kohout, Z.; Kramberger, G.; Kuhnke, M.; Kwan, S.; Lemeilleur, F.; Leroy, C.; Letheren, M.; Li, Z.; Ligonzo, T.; Linhart, V.; Litovchenko, P.; Loukas, D.; Lozano, M.; Luczynski, Z.; Lutz, G.; MacEvoy, B.; Manolopoulos, S.; Markou, A.; Martinez, C.; Messineo, A.; Miku, M.; Moll, M.; Nossarzewska, E.; Ottaviani, G.; Oshea, V.; Parrini, G.; Passeri, D.; Petre, D.; Pickford, A.; Pintilie, I.; Pintilie, L.; Pospisil, S.; Potenza, R.; Radicci, V.; Raine, C.; Rafi, J. M.; Ratoff, P. N.; Richter, R. H.; Riedler, P.; Roe, S.; Roy, P.; Ruzin, A.; Ryazanov, A. I.; Santocchia, A.; Schiavulli, L.; Sicho, P.; Siotis, I.; Sloan, T.; Slysz, W.; Smith, K.; Solanky, M.; Sopko, B.; Stolze, K.; Sundby Avset, B.; Svensson, B.; Tivarus, C.; Tonelli, G.; Tricomi, A.; Tzamarias, S.; Valvo, G.; Vasilescu, A.; Vayaki, A.; Verbitskaya, E.; Verdini, P.; Vrba, V.; Watts, S.; Weber, E. R.; Wegrzecki, M.; Wegrzecka, I.; Weilhammer, P.; Wheadon, R.; Wilburn, C.; Wilhelm, I.; Wunstorf, R.; Wüstenfeld, J.; Wyss, J.; Zankel, K.; Zabierowski, P.; Zontar, D.

2001-06-01

246

Constant-pitch microprism-array optical device for beam condensers in hard x-ray synchrotron radiation beamlines  

NASA Astrophysics Data System (ADS)

A constant-pitch microprism-array optical device has been developed. It is a modified version of the previously reported quasi-Fresnel lens [Kagoshima et al., Appl. Phys. Lett. 101, 163102 (2012)]. The modification eases the fabrication of the lens, although it degrades some of the focusing performance. It consists of twenty 50-?m-wide right-angle microprisms, whose slope angles gradually increase to 67.8° at the outer side. By inclining the array, the aspect ratio of the microprisms becomes large enough for X-ray use. The effective slope angle can be enlarged to 86.4° at an inclination angle of 80.5°. A 10-keV synchrotron beam with a size of 680 ?m (V) × 660 ?m (H) was two-dimensionally condensed to 130 ?m (V) × 380 ?m (H) with a photon flux density gain of ~3. We also show that the microprism array is suitable for practical use below the critical radiation dose rate.

Kagoshima, Y.; Takano, H.; Takeda, S.

2013-06-01

247

Optimization of the radiation hardness of silicon pixel sensors for high x-ray doses using TCAD simulations  

NASA Astrophysics Data System (ADS)

The European X-ray Free Electron Laser (XFEL) will deliver 27000 fully coherent, high brilliance X-ray pulses per second each with a duration below 100 fs. This will allow the recording of diffraction patterns of single molecules and the study of ultra-fast processes. One of the detector systems under development for the XFEL is the Adaptive Gain Integrating Pixel Detector (AGIPD), which consists of a pixel array with readout ASICs bump-bonded to a silicon sensor with pixels of 200 × 200 ?m2. The particular requirements for the detector are a high dynamic range (0, 1 up to 105 12 keV photons/XFEL-pulse), a fast read-out and radiation tolerance up to doses of 1 GGy of 12 keV X-rays for 3 years of operation. At this X-ray energy no bulk damage in silicon is expected. However fixed oxide charges in the SiO2 layer and interface traps at the Si-SiO2 interface will build up. As function of the 12 keV X-ray dose the microscopic defects in test structures and the macroscopic electrical properties of segmented sensors have been investigated. From the test structures the oxide charge density, the density of interface traps and their properties as function of dose have been determined. It is found that both saturate (and even decrease) for doses above a few MGy. For segmented sensors surface damage introduced by the X-rays increases the full depletion voltage, the surface leakage current and the inter-pixel capacitance. In addition an electron accumulation layer forms at the Si-SiO2 interface which increases with dose and decreases with applied voltage. Using TCAD simulations with the dose dependent damage parameters obtained from the test structures the results of the measurements can be reproduced. This allows the optimization of the sensor design for the XFEL requirements.

Schwandt, J.; Fretwurst, E.; Klanner, R.; Pintilie, I.; Zhang, J.

2012-01-01

248

White noise study of JFET's on a new mixed rad-hard technology  

Microsoft Academic Search

A new technology, called DMILL and based on re-epitaxied SIMOX structures, is being developped, with which both logic (CMOS) and analogic (JFET and BICMOS) devices are available. A good radiation hardness and a complete isolation between components is achieved. Isolation between analog and digital parts of a circuit corresponds to the trends for future low-noise mixed circuit applications. JFET's are

E. Delevoye; A. Chovet

1992-01-01

249

Simulation of radiated narrow band electromagnetic interference for components in the automotive industry (bulk current injection)  

Microsoft Academic Search

Electro-smog is a term which stands for all kind of electromagnetic fields which are around the world, such as RF (radio frequency) field from radio and TV stations, radiation from high voltage transmission lines, mobile communication and high frequency emission from household equipment. In this paper, we will analyze the influence of such radiated fields on products used in the

H. Kunkel; S. Klezar

2003-01-01

250

Analysis of spectroscopic radiation portal monitor data using principal components analysis  

Microsoft Academic Search

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

Robert C. Runkle; Mark F. Tardiff; Kevin K. Anderson; Deborah K. Carlson; L. Eric Smith

2006-01-01

251

Molecular strategies targeting the host component of cancer to enhance tumor response to radiation therapy  

SciTech Connect

The tumor microenvironment, in particular, the tumor vasculature, as an important target for the cytotoxic effects of radiation therapy is an established paradigm for cancer therapy. We review the evidence that the phosphoinositide 3-kinase (PI3K)/Akt pathway is activated in endothelial cells exposed to ionizing radiation (IR) and is a molecular target for the development of novel radiation sensitizing agents. On the basis of this premise, several promising preclinical studies that targeted the inhibition of the PI3K/Akt activation as a potential method of sensitizing the tumor vasculature to the cytotoxic effects of IR have been conducted. An innovative strategy to guide cytotoxic therapy in tumors treated with radiation and PI3K/Akt inhibitors is presented. The evidence supports a need for further investigation of combined-modality therapy that involves radiation therapy and inhibitors of PI3K/Akt pathway as a promising strategy for improving the treatment of patients with cancer.

Kim, Dong Wook [Department of Radiation Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN (United States); Huamani, Jessica [Department of Radiation Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN (United States); Fu, Allie [Department of Radiation Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN (United States); Hallahan, Dennis E. [Department of Radiation Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN (United States)]. E-mail: dennis.hallahan@vanderbilt.edu

2006-01-01

252

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 3×1012 cm-2 (low-dose p-spray) and 5×1012 cm-2 (high-dose p-spray). The samples have undergone irradiations with 26 MeV protons and reactor neutrons up to ˜1016 cm-2 1 MeV equivalent neutrons (neq/cm2), 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

253

Ultraviolet radiation transmittance of the mouse eye and its individual media components.  

PubMed

Recently, the mouse has become the preferred animal model in ophthalmic research. Therefore, there is a need for enhanced understanding of the mouse eye to validate its use in different experimental setting. The purpose of this study was to determine the ocular transmittance of the whole mouse eye, the cornea and the crystalline lens, particularly in the ultraviolet radiation (UVR) wavebands. This was carried out using a non-cuvette based fiber optic spectrometer system and the resulting transmittance curves were compared with published cone spectral response curves and mouse ocular transmittance data. First, transmittance curves of the whole mouse eye were measured by removing a small disc of sclera from the posterior pole to provide an anterior to posterior optical path. No statistical difference was found between left and right eye in each of the four mice sampled, therefore, all eight eyes were included in the final statistical analysis. The average of five test measurements from each left and right eye for the four test mice showed a transmittance cut off at approximately 310 nm. Secondly, the cornea with a scleral rim was excised and transmittance curves obtained for all eight eyes. This data showed an average transmittance cut off at 280 nm for the cornea. Similarly measured data for the excised crystalline lens showed UVR transmittance down to 310 nm. The good correlation between total ocular UVR transmittance and the sum of the individually measured components (i.e. the cornea and the crystalline lens) supported the validity of our method and its findings. This experiment demonstrated that the mouse cornea transmits more UV-B (280-315 nm) than the rabbit and the human corneal transmittance. The mouse crystalline lens on the other hand showed a cut off in the UV-B at 310 nm, which is at a much lower UV-B wavelength than the approximate UV-A (315-400 nm) cut off for the human crystalline lens at around 390 nm. The increased transmittance of UVR in the mouse eye serves its vision, since the mouse has a cone photopigment peaking at approximately 350 nm. Due to the above stated differences between the mouse and the human it is concluded that the mouse is not an ideal model for the human eye in experiments involving UVR. PMID:19925789

Henriksson, Johanna Tukler; Bergmanson, Jan P G; Walsh, James E

2009-11-17

254

Ultra-Hard Low Friction Coating Based on ALMGB14 for Reduced Wear on MEMS and Other Tribiological Components and System.  

National Technical Information Service (NTIS)

Performance and reliability of microelectromechanical system (MEMS) components enhanced dramatically through the incorporation of protective thin film coatings. Current-generation MEMS devices prepared by the LIGA technique employ transition metals such a...

A. M. Russell A. P. Constant B. A. Cook J. L. Harringa Y. Tian

2004-01-01

255

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

256

A Preliminary Investigation of 'In-and-down' and 'In-and-Up' Radiation Components.  

National Technical Information Service (NTIS)

An experiment was designed to measure the attenuation afforded by horizontal barriers both above and below ground to radiation that originated from sources lying on the ground surrounding a structure. Measured attenuation factors in the downward direction...

J. D. Velletri

1966-01-01

257

Year-to-year variability of components of Earth's radiation budget according to satellite measurement data  

Microsoft Academic Search

The year-to-year variability computed on satellite measurements with scanning radiometers carried by polar orbit satellites were analyzed. Solar-synchronous orbits carried out measurements over the same territory twice each day. The data wre reduced to mean monthly values of the fluxes of outgoing short and long-wave radiation. The analysis of year-to-year variability was based on mean monthly values of the radiation

G. K. Marchuk; K. Y. Kondratyev; O. A. Avaste; V. V. Kozoderov; O. Y. Kyarner

1985-01-01

258

Study of the ratio of non-neutron to neutron dose components of cosmic radiation at typical commercial flight altitudes.  

PubMed

CIEMAT, in close co-operation with Iberia Airlines, carried out an extensive programme of in-flight measurements, covering both hemispheres, during the years 2001 and 2002. Although the instrumentation onboard included different active devices, the results presented here were obtained from a polyethylene/tungsten-moderated rem meter (SWENDI2; Eberline) and an ionisation chamber (RSS-131; Reuter-Stokes) used for measuring the ambient dose equivalent due to the neutron and the non-neutron components of cosmic radiation, respectively. This paper presents a study of each of the dose components mentioned as a function of the vertical cut-off rigidity and the flight altitude. The ratio between the two components is also presented to determine the variations in cosmic radiation composition as a function of the aforementioned parameters. The experimental results have also been compared with those predicted by the code EPCARD3.2 for the non-neutron and the neutron components of the ambient dose equivalent. PMID:15353674

Romero, A M; Saez-Vergara, J C; Rodriguez, R; Domínguez-Mompell, R

2004-01-01

259

The Correlation between Radiated Emissions and Power Line Network Components on Indoor Power Line Communications  

Microsoft Academic Search

Residential power lines are one of the most attractive communication media for home networking, since every room in a house has multiple power outlets. In general, in-home power line networks have various network components which are not related to communications. The power line network includes many electrical appliances without communication facilities, switches, and so on. These components will cause electrical

Masahiro Ishihara; Daisuke Umehara; Yoshiteru Morihiro

2006-01-01

260

Radiation-Induced Gene Translation Profiles Reveal Tumor Type and Cancer-Specific Components  

PubMed Central

The microarray analysis of total cellular RNA is a common method used in the evaluation of radiation-induced gene expression. However, profiling the cellular transcriptome does not take into account posttranscriptional processes that affect gene expression. To better define the genes whose expression is influenced by ionizing radiation, we used polysome-bound RNA to generate gene translation profiles for a series of tumor and normal cell lines. Cell lines were exposed to 2 Gy, polysome-bound RNA isolated 6 hours later, and then subjected to microarray analysis. To identify the genes whose translation was affected by radiation, the polysome-bound RNA profiles were compared with their corresponding controls using significance analysis of microarrays (<1% false discovery rate). From the statistically significant genes identified for each cell line, hierarchical clustering was performed by average linkage measurement and Pearson’s correlation metric. Ingenuity Pathway Analysis was used for distributing genes into biological networks and for evaluation of functional significance. Radiation-induced gene translation profiles clustered according to tissue of origin; the cell lines corresponding to each tissue type contained a significant number of commonly affected genes. Network analyses suggested that the biological functions associated with the genes whose translation was affected by radiation were tumor type–specific. There was also a set of genes/networks that were unique to tumor or normal cells. These results indicate that radiation-induced gene translation profiles provide a unique data set for the analysis of cellular radioresponse and suggest a framework for identifying and targeting differences in the regulation of tumor and normal cell radiosensitivity.

Kumaraswamy, Sandhya; Chinnaiyan, Prakash; Shankavaram, Uma T.; Lu, Xing; Camphausen, Kevin; Tofilon, Philip J.

2008-01-01

261

DMILL (Durci Mixte sur Isolant Logico-Linéaire) A mixed analog-digital radiation hard technology for high energy physics electronics  

Microsoft Academic Search

A new rad-hard technology suitable for high energy physics electronics is currently under development. This technology uses a SOI substrate with a thick silicon film. It includes CMOS, CJFET and complementary vertical bipolar transistors with a potential multi-Mrad hardness for all these devices. These devices enable the design of both analog and digital functions. CMOS together with bipolar transistors will

M. Dentan; P. Baron; E. Beuville; P. Borgeaud; N. Fourches; M. Rouger; R. Truche; M. Bruel; E. Delevoye; J. Gautier; J. Pontcharra; Jl. Leray; O. Flament; Jl. Martin; J. Montarron; Mc. Habrard; P. Delpierre; R. Potheau; C. Terrier; G. Borel; Jm. Brice

1993-01-01

262

SRS conversion of XeCl laser radiation into shifted Stokes components  

SciTech Connect

An experimental study and a theoretical simulation were made of stimulated Raman scattering (SRS) conversion into shifted components. It was found that there were optimal values of the pressure and focal distance for conversion into the first 'blue' satellite of the first Stokes component. A study was made of the spatial and temporal dynamics of SRS conversion, which took into account generation of the shifted components. It was demonstrated theoretically and experimentally that the satellite intensity could be enhanced significantly by additional electron-collision excitation of the vibrational levels in the conversion medium or by the application of pairs of pump pulses. The maximum efficiency of conversion to the first 'blue' satellite of the first Stokes component was 10% and the satellite intensity reached one-third of the intensity of the main Stokes line. (nonlinear optical phenomena and devices)

Kaul', V B; Kunts, S E; Mel'chenko, S V [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

1998-01-31

263

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

264

Radiation damage studies of optoelectronic components for the CMS tracker optical links  

Microsoft Academic Search

Optical links are being developed to transfer analogue tracking data and digital timing and control signals in the future Compact Muon Solenoid (CMS) experiment at CERN. The radiation environment inside the CMS tracker will be extreme, with hadron fluences up to ~1014\\/cm2 and ionising doses of ~100 kGy over the experimental lifetime. Prototype link elements, consisting of commercially available 1310

K. Gill; V. Arbet-Engels; J. Batten; G. Cervelli; R. Grabit; C. Mommaert; G. Stefanini; J. Troska; F. Vasey

1997-01-01

265

Principal Component Analysis of Gamma-Ray Spectra for Radiation Portal Monitors  

Microsoft Academic Search

The scanning of cargo for radiological and nuclear material is vital in detecting the illicit trafficking of such materials. The deployment of technologies such as Radiation Portal Monitors (RPMs) has enabled screening for the presence of gamma and neutron emitting radionuclides.

David Boardman; Mark Reinhard; Alison Flynn

2012-01-01

266

The use of passive personal neutron dosemeters to determine the neutron component of cosmic radiation fields in spacecraft  

NASA Astrophysics Data System (ADS)

For the altitude range and inclination of the International Space Station (ISS), secondary neutrons can be a major contributor to dose equivalent inside a spacecraft. The exact proportion is very dependent on the amount of shielding of the primary galactic cosmic radiation and trapped particles, but is likely to lie in the range of 10% to 50%. Personal neutron dosemeters of simple design, and processed using simple techniques developed for personal dosimetry may be used to estimate this neutron component. For the etch regime employed, the combination of high LET threshold (there is little response below a restricted LET200 in PADC of about 40 keV ?m-1), and poor angle dependence of response to high-energy charged particles (HZE), results in a much reduced overall response of the neutron dosimeter to the HZE component of the field in spacecraft and no response to protons of energy greater than about 2 MeV. Preliminary measurements indicate that for examples of the HZE component of the radiation fields in spacecraft, a correction of 5 to 10 % is necessary to account for the detector HZE response. Alternatively, an additional chemical etch can be carried out which allows discrimination. Recent results for exposures in low Earth orbit are reported.

Bartlett, D. T.; Hager, L. G.; Tanner, R. T.

267

Annual Conference on Nuclear and Space Radiation Effects, 17th, Cornell University, Ithaca, N.Y., July 15-18, 1980, Proceedings  

Microsoft Academic Search

The conference covered the radiation effects on devices, circuits, and systems, physics and basic radiation effects in materials, dosimetry and radiation transport, spacecraft charging, and space radiation effects. Other subjects included single particle upset phenomena, systems-generated electromagnetic pulse phenomena, fabrication of hardened components, testing techniques, and hardness assurance. Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

J. M. McGarrity

1980-01-01

268

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

NASA Astrophysics Data System (ADS)

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 indicate that parameters such as orbit altitude, shielding thickness, and solar activity strongly affect the SEU rates.

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

2001-02-01

269

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

270

Sensor and method for measurment of select components of a material based on detection of radiation after interaction with the material  

SciTech Connect

A sensor is described for measuring one or more select components of a sheet, comprising: a radiation source for emitting radiation toward the sheet; a plurality of detecting means, wherein at least one detecting means is offset from the source, for detecting radiation after interaction with the sheet; means for directing the radiation so that the radiation makes multiple interactions with the sheet in moving from the source to the detecting means, wherein the directing means includes a first reflector and second reflector defining a sheet space for the sheet to occupy; means for computing a ratio of the intensity of the detected radiation when the sheet is absent from the sheet space and the intensity of the detected radiation when the sheet occupies the sheet space; and means for computing the absorption power of the sheet from the intensity of the detected radiation.

Chase, L.M.; Anderson, L.M.; Norton, M.K.

1993-08-10

271

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

272

Fusion Reactor Materials and Components: Issues Related to Radioactivity and Radiation-Induced Effects  

Microsoft Academic Search

A concise overview is given on materials applied in fusion technology. The influence of plasma operation on the behaviour of reactor components and diagnostic systems is discussed with emphasis on effects caused by fast particles reaching the reactor wall. Issues related to primary and induced radioactivity are reviewed: tritium inventory and transmutation. Tritium breeding in the reactor blanket, separation of

M. Rubel

2004-01-01

273

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

Microsoft Academic Search

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

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

1994-01-01

274

Effects of radiation heat transfer space non-uniformity of combustion chamber components on in-cylinder soot emission formation in diesel engine  

Microsoft Academic Search

Combustion chamber components (cylinder head-cylinder liner-piston assembly-fuel film) were treated as a coupled body. Based\\u000a on the three-dimensional numerical simulation of heat transfer of the coupled body, the multi-dimensional simulation computation\\u000a coupling flow and solid on working process and combustion chamber components of internal combustion engine was performed using\\u000a Discrete Transfer Radiation Model (DTRM) radiation heat transfer model, zoning solution

JiZu Lü; MinLi Bai; XiaoJie Li

2010-01-01

275

Transformation of the multipolar components of gravitational radiation under rotations and boosts  

NASA Astrophysics Data System (ADS)

We study the transformation of multipolar decompositions of gravitational radiation under rotations and boosts. Rotations to the remnant black hole’s frame simplify the waveforms from the merger of generic spinning black hole binaries. Boosts may be important to get an accurate gravitational-wave phasing, especially for configurations leading to large recoil velocities of the remnant. As a test of the formalism we revisit the classic problem of point particles falling into a Schwarzschild black hole. Then we highlight by specific examples the importance of choosing the right frame in numerical simulations of unequal mass, spinning binary black-hole mergers.

Gualtieri, Leonardo; Berti, Emanuele; Cardoso, Vitor; Sperhake, Ulrich

2008-08-01

276

Effect of radiation damping on the spectral response of plasmonic components.  

PubMed

We explore the relationship between the near-field enhancement, absorption, and scattering spectra of localized plasmonic elements. A simple oscillator model including both internal and radiative damping is developed, and is shown to accurately capture the near- and far-field spectral features of linear optical antennas, including their phase response. At wavelengths away from the interband transitions of the metal, we expect the absorption of a plasmonic element to be red-shifted relative to the scattering, and the near-field to be red-shifted relative to both. PMID:22109025

Kats, Mikhail A; Yu, Nanfang; Genevet, Patrice; Gaburro, Zeno; Capasso, Federico

2011-10-24

277

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

278

The magnetic, basal, and radiative-equilibrium components in Mount Wilson Ca II H + K fluxes  

SciTech Connect

Mount Wilson Ca II H + K flux measurements of cool dwarf stars are analyzed and compared with stellar Mg II h + k fluxes, variability amplitudes, rotation rates, and solar data. It is concluded that the Mount Wilson Ca II H + K fluxes comprise three principal parts: (1) a photospheric contribution in the line wings, (2) a basal chromospheric component that appears to be unrelated to stellar magnetic activity and is, therefore, possibly nonmagnetic in origin, and (3) a chromospheric component which is associated with magnetically active regions and the (quiet and active) network. The basal chromosphere appears to cover the entire surface of magnetically inactive stars. The basal Ca II H + K flux density for solar-type stars equals the average emission observed in the centers of solar supergranulation cells, where the magnetic flux density is small. 27 refs.

Schrijver, C.J.; Dobson, A.K.; Radick, R.R. (National Solar Observatory, Sunspot, NM (USA); Joint Institute for Laboratory Astrophysics, Boulder, CO (USA))

1989-06-01

279

Oxidation and radiation buildup on stainless steel components of boiling water reactors  

SciTech Connect

The buildup of radioactivity was measured on Type 304 stainless steel and carbon steel coupons exposed to reactor water in a test loop, which operated for about 3 yr in a commercial boiling water reactor. Most of the activity buildup could be ascribed to /sup 60/Co. After an initial rapid increase, the activity buildup slowed down and kept increasing linearly up to 10,000 h of effective exposure to reactor water. No correlation was found between the /sup 60/Co activity in reactor water and the /sup 60/Co activity on the coupons. Preoxidation of Type 304 stainless steel coupons reduced the initial activity buildup. Carbon steel picked up much less activity than stainless steel during the tests. Measurements of the activity buildup after filtration of the primary coolant indicated that soluble impurities rather than particulates are primarily responsible for the radiation buildup phenomena. Increasing the coolant velocity also resulted in a reduction of the initial activity buildup on the coupons.

Romeo, G.

1983-10-01

280

Oxidation and radiation buildup on stainless steel components of boiling water reactors  

SciTech Connect

The buildup of radioactivity was measured on Type 304 stainless steel and carbon steel coupons exposed to reactor water in a test loop, which operated for about3 yr in a commercial boiling water reactor. Most of the activity buildup could be ascribed to /sup 60/Co. After an initial rapid increase, the activity buildup slowed down and kept increasing linearly up to 10000 h of effective exposure to reactor water. No correlation was found between the /sup 60/Co activity in reactor water and the /sup 60/Co activity on the coupons. Preoxidation of Type 304 stainless steel coupons reduced the initial activity buildup. Carbon steel picked up much less activity than stainless steel during the tests. Measurements of the activity buildup after filtration of the primary coolant indicated that soluble impurities rather than particulates are primarily responsible for the radiation buildup phenomena. Increasing the coolant velocity also resulted in a reduction of the initial activity buildup on the coupons.

Romeo, G.

1983-10-01

281

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

282

Survey of atmospheric radiation components for the Gamma and Cosmic Ray Astrophysics Branch of the Space Science Division of the Naval Research Laboratory  

NASA Astrophysics Data System (ADS)

A survey of atmospheric radiation components for the gamma and cosmic ray astrophysics branch of the Naval Research Laboratory has the following contents: Electron Capture Decay of Cosmic Rays; Cosmic Ray Heavy Ions at and Above 40,000 Feet; Neutron Generated Single Event Upsets in the Atmosphere; Nuclear Cross Sections, Cosmic Ray Propagation and Source Composition; Radiation Transport of Cosmic Ray Nuclei in Lunar Material and Radiation Doses; Non-Geometric Behavior of Nucleus Nucleus Total Inelastic Cross Sections; Environmental Models for Single Event Upset Estimation; Uncertainties in Cosmic Ray Source Composition; Late Stage in Acceleration of Cosmic Rays; Ultraheavy Cosmic Rays and Electron Capture; Propagation of Heavy Cosmic Ray Nuclei; On the Abundances of Ultraheavy Cosmic Rays; LET-Distributions and Doses of HZE Radiation Components at Near Earth Orbits; and Radiation Doses and LET (Linear Energy Transfer) Distributions of Cosmic Rays.

1985-05-01

283

Radiation Effects in Corundum Single Crystals  

Microsoft Academic Search

Corundum is a unique optical and insulation material because of its great hardness and high heat, chemical, and radiation resistance. In the last few years, it has been considered as one of the most promising insulators for thermonuclear reactors. In addition, it is a component of many alumina-rich materials widely used as structural materials in the nuclear technology. Consequently, an

I. Kh. Abdukadyrova

2004-01-01

284

Results of measurements on shuttle missions to the ISS of the neutron component of the radiation field  

NASA Astrophysics Data System (ADS)

Secondary neutrons can be a major contributor to dose equivalent and effective dose inside a spacecraft for the altitude range and inclination of the International Space Station. The exact proportion is very dependent on the amount of shielding of the primary galactic cosmic radiation and trapped particles, but is likely to lie in the range of 10 60%. Neutron personal dosemeters of simple design, processed using simple techniques developed for routine personal dosimetry, have been used to determine the neutron component, including the neutron-like interactions of high energy protons. For the etch regime employed, the combination of high LET threshold (there is little response below a restricted LET200 in PADC of 30 40 keV/?m) and poor angle dependence of response to high-energy charged particles results in a much reduced overall response of the neutron dosemeter to the HZE component of the field in spacecraft and no response to protons of energy greater than about 1 MeV. A correction of 10 20% is necessary to account for the detector HZE response. Alternatively, an additional chemical etch can be carried out which allows discrimination.

Bartlett, D. T.; Hager, L. G.; Tanner, R. J.

285

Roller burnishing of hard turned surfaces  

Microsoft Academic Search

In a hard roller burnishing operation, a hydrostatically borne ceramic ball rolls over the component surface under high pressures. The roughness peaks are flattened and the quality of the workpiece surface is improved. When combined with hard turning, this process provides a manufacturing alternative to grinding and honing operations.The studies determined optimum working parameter ranges. Parameter settings were shown to

F. Klocke; J. Liermann

1998-01-01

286

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

287

X-ray emission from cataclysmic variables with accretion disks. I - Hard X-rays. II - EUV\\/soft X-ray radiation  

Microsoft Academic Search

Theoretical models explaining the hard-X-ray, soft-X-ray, and EUV emission of accretion-disk cataclysmic variables in terms of the disk boundary layer (DBL) are developed on the basis of a survey of the published observational data. The data are compared with model predictions in graphs for systems with high or low (greater than or less than 10-Pg\\/s) accretion rates. Good agreement is

J. Patterson; J. C. Raymond

1985-01-01

288

Future hard disk drive systems  

NASA Astrophysics Data System (ADS)

This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

Wood, Roger

2009-03-01

289

Hard Metal Disease  

PubMed Central

In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images

Bech, A. O.; Kipling, M. D.; Heather, J. C.

1962-01-01

290

Calculating radiation exposures during use of (14)C-labeled nutrients, food components, and biopharmaceuticals to quantify metabolic behavior in humans.  

PubMed

(14)C has long been used as a tracer for quantifying the in vivo human metabolism of food components, biopharmaceuticals, and nutrients. Minute amounts (< or =1 x 10 (-18) mol) of (14)C can be measured with high-throughput (14)C-accelerator mass spectrometry (HT (14)C-AMS) in isolated chemical extracts of biological, biomedical, and environmental samples. Availability of in vivo human data sets using a (14)C tracer would enable current concepts of the metabolic behavior of food components, biopharmaceuticals, or nutrients to be organized into models suitable for quantitative hypothesis testing and determination of metabolic parameters. In vivo models are important for specification of intake levels for food components, biopharmaceuticals, and nutrients. Accurate estimation of the radiation exposure from ingested (14)C is an essential component of the experimental design. Therefore, this paper illustrates the calculation involved in determining the radiation exposure from a minute dose of orally administered (14)C-beta-carotene, (14)C-alpha-tocopherol, (14)C-lutein, and (14)C-folic acid from four prior experiments. The administered doses ranged from 36 to 100 nCi, and radiation exposure ranged from 0.12 to 5.2 microSv to whole body and from 0.2 to 3.4 microSv to liver with consideration of tissue weighting factor and fractional nutrient. In comparison, radiation exposure experienced during a 4 h airline flight across the United States at 37000 ft was 20 microSv. PMID:20349979

Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

2010-04-28

291

Radiation loads onto plasma-facing components of JET during transient events - Experimental results and implications for ITER  

NASA Astrophysics Data System (ADS)

This contribution examines the impact on plasma radiation and on power load to the divertor (i) of large type I ELMs with energies 0.25-1.3 MJ in high current H-mode JET discharges and (ii) of disruptions.The ELMs provoke strong radiation losses, mostly confined to the inner divertor region. Large type I ELMs with ?WELM ? 0.72 MJ show enhanced radiation losses which are associated with the ablation of carbon layers in the inner divertor. Such large ELMs are usually followed by a phase of type III ELMs with an increased radiation in the plasma core.The unmitigated disruptions exhibit small radiation fractions with strong poloidal radiation asymmetry during the thermal quench, which could cause Be melting by radiation in ITER. In dedicated experiments on massive gas injection, about 60% of the thermal energy and a significant part of the magnetic energy was converted in radiation and spread uniformly over the first walls.

Jet Efda Contributors Huber, A.; Arnoux, G.; Beurskens, M. N. A.; Bozhenkov, S. A.; Brezinsek, S.; Eich, T.; Fuchs, C.; Fundamenski, W.; Jachmich, S.; Kruezi, U.; Lehnen, M.; Loarte, A.; Matthews, G. F.; Mertens, Ph.; Morgan, P. D.; Philipps, V.; Pitts, R. A.; Riccardo, V.; Samm, U.; Schweer, B.; Sergienko, G.; Stamp, M.

2011-08-01

292

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

293

Survey of atmospheric radiation components for the Gamma and Cosmic Ray Astrophysics Branch of the Space Science Division of the Naval Research Laboratory  

NASA Astrophysics Data System (ADS)

The objects of this study were: (1) Conduct a comprehensive literature search to determine the state-of-the-art knowledge of the effect of atmospheric radiation components on semiconductor materials from sea level to the top atmospheric layers. Emphasis shall be placed on particle propagation, radiation effects on semiconductor materials, and methods of calculating nuclear reaction cross sections. A comprehensive survey shall be made on the interactions between atmospheric components and cosmic rays and the secondary emissions and energy spectra produced. (2) Generate propagation algorithms to describe the penetration of primary cosmic rays into the atmosphere and the production of secondry emissions. (3) Calculate the energy loss rates in semiconductor materials for various cosmic ray components as a function of altitude, geomagnetic location, and zenith and azimuthal angles.

1984-02-01

294

A radiation-hard dual channel 4-bit pipeline for a 12-bit 40 MS/s ADC prototype with extended dynamic range for the ATLAS Liquid Argon Calorimeter readout electronics upgrade at the CERN LHC  

NASA Astrophysics Data System (ADS)

The design of a radiation-hard dual-channel 12-bit 40 MS/s pipeline ADC with extended dynamic range is presented, for use in the readout electronics upgrade for the ATLAS Liquid Argon Calorimeters at the CERN Large Hadron Collider. The design consists of two pipeline A/D channels with four Multiplying Digital-to-Analog Converters with nominal 12-bit resolution each. The design, fabricated in the IBM 130 nm CMOS process, shows a performance of 68 dB SNDR at 18 MHz for a single channel at 40 MS/s while consuming 55 mW/channel from a 2.5 V supply, and exhibits no performance degradation after irradiation. Various gain selection algorithms to achieve the extended dynamic range are implemented and tested.

Kuppambatti, J.; Ban, J.; Andeen, T.; Kinget, P.; Brooijmans, G.

2013-09-01

295

Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation  

Microsoft Academic Search

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and γ-ray irradiations at UC Santa

H. J. Ziock; C. Milner; W. F. Sommer; N. Carteglia; J. DeWitt; D. Dorfan; B. Hubbard; J. Leslie; K. F. OShaughnessy; D. Pitzl; W. A. Rowe; H. F. W. Sadrozinski; A. Seiden; E. Spencer; J. A. Ellison; P. Ferguson; Giubellino

1990-01-01

296

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable combinatorial surface. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither of which is homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2008-01-01

297

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable surface without boundary. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable with respect

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2006-01-01

298

RAD hard PROM design study  

NASA Astrophysics Data System (ADS)

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.

1981-07-01

299

BRIEF COMMUNICATIONS: Influence of stimulated Brillouin scattering on the radiation characteristics of stimulated Raman scattering components in multimode fiber-optical waveguides  

NASA Astrophysics Data System (ADS)

Spectral, temporal, and spatial characteristics of the nonlinearly converted radiation were obtained for cases when stimulated Raman scattering (STRS) and stimulated Brillouin scattering (STBS) occurred jointly and separately in fused quartz multimode fiber-optic waveguides. A tenfold decrease in the pulse duration was achieved. Specific characteristics of the evolution of STRS and aspects associated with the formation and propagation of the Stokes components of STRS in fiber-optic waveguides under the conditions achieved are discussed. It is shown that STBS influences the characteristics of the STRS radiation when the material of the waveguide core is variously doped.

Solov'ev, Veniamin V.; Nesterova, Z. V.; Petrovski?, G. T.

1987-02-01

300

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

Microsoft Academic Search

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

Keith Charles Gendreau

1995-01-01

301

Two-dimensional ground motion at a soft viscoelastic layer/hard substratum site in response to SH cylindrical seismic waves radiated by deep and shallow line sources-II. Numerical results  

NASA Astrophysics Data System (ADS)

We consider, using theory and associated synthetic seismograms, the seismic response of a site comprising a horizontal, homogeneous, soft viscoelastic layer of infinite lateral extent overlying, and in welded contact with, a homogeneous, hard elastic substratum of half-infinite radial extent. We show that for shear-horizontal motion: (1) coupling to Love modes is all the weaker the deeper the source (modelled as a line, assumed to lie in the substratum) is from the lower boundary of the soft layer, (2) for a line source close to the lower boundary of the soft layer, the ground response is characterized by possible beating phenomena, and is of significantly longer duration than for excitation by cylindrical waves radiated by deep sources. Numerical applications of the theory show, for instance, that a line source, located 40 m below the lower boundary of a 60-m-thick soft layer in a hypothetical Mexico-City-like site, radiating a SH pulse of 4 s duration, produces substantial ground motion during 200 s, with marked beating, at an epicentral distance of 3 km. Results from this modelling study are supported by field examples taken from published literature.

Groby, Jean-Philippe; Wirgin, Armand

2005-10-01

302

Modeling of Residual Stress Profile in Finish Hard Turning  

Microsoft Academic Search

Mechanical components shaped by hard turning processes are commonly used under high stress and repeated loading conditions. The physical strength and fatigue life of these components is known to be significantly affected by the residual stress distributions induced by finish hard turning. A thorough understanding of the residual stress profile including both magnitude and direction along the depth of the

Jing Ying Zhang; Steven Y. Liang; Guowei Zhang; David Yen

2006-01-01

303

Development of a high total radiation dose-resistant vertical-cavity surface-emitting laser driver with discrete COTS components  

NASA Astrophysics Data System (ADS)

Radiation tolerant fiber optic transmission links are desired for their potential use in future thermonuclear fusion reactors and other harsh radiation fields. As part of it, we design and test a radiation opto-electronic transmitter based on vertical-cavity surface-emitting lasers (VCSELs) and dedicated driver electronics consisting of discrete components. VCSELs have already demonstrated their high radiation acceptance level. We confirm this by on-line irradiation experiments on such devices up to 10 MGy total dose. For the design of the driver circuit, we rely on discrete commercial-off-the-shelf (COTS) bipolar transistors. When the radiation induced degradation of these components is considered within the time design of the circuits, total dose levels larger than 1 MGy can be tolerated. The driver uses standard TTL input signals and delivers a forward current of 12 mA to a pigtailed 840 nm VCSEL. SPICE simulations show that the driver still delivers a sufficient forward current to the VCSEL, in spite of the radiation induced degradation of the Hfe and VCEsat values of the transistors. These simulations are verified by our experiments. At a total dose of 1 MGy, the measured decrease of the forward current is only about 8%. This induces an optical output power decrease that can still be tolerated with irradiated VCSELs, as shown by our experiments. We conclude that a high total dose hardened optical transmitter for use in nuclear instrumentation systems can be fabricated using discrete COTS bipolar transistors, COTS vertical-cavity surface-emitting lasers and COTS optical fiber.

Van Uffelen, Marco; Embrechts, Kathleen; Berghmans, Francis; Coenen, Simon; Decreton, Marc C.; Van Gorp, Juergen

2002-01-01

304

Hardness assurance statistical methodology for semiconductor devices  

NASA Astrophysics Data System (ADS)

A statistical method is developed for determining electrical end-point limits for semiconductor devices subjected to radiation stress. The approach utilizes multiple lot radiation data and can be applied where lot-to-lot variations in radiation response are large compared to variations within a lot. Such limits may be used as design parameter limits or as failure limits for lot acceptance testing of future hardness-assured, semiconductor production lots. The method was applied for neutron and total gamma dose effects on low power bipolar transistors, digital TTL ICs, and a power transistor for which an adequate multiple-lot radiation database existed.

Arimura, I.; Namenson, A. I.

1983-12-01

305

Microscopic models of hardness  

Microsoft Academic Search

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness\\u000a is described as a function of the bond density and bond strength. The bond strength may be characterized by energy gap, reference\\u000a potential, electron-holding energy or Gibbs free energy, and different expressions of bond strength may lead to different\\u000a hardness models. In

F. M. Gao; L. H. Gao

2010-01-01

306

Design and Assessment of a Circuit and Layout Level Radiation Hardened CMOS VCSEL Driver  

Microsoft Academic Search

The radiation hard design of a 155 Mb\\/s, 0.7 mum CMOS driver for a vertical-cavity surface-emitting laser (VCSEL) is presented. The circuit features enhanced tolerance to radiation induced shifts in the device characteristics by employing a replica-based feedback mechanism. The layout was achieved using an in-house developed radiation hardened component library. At a low dose rate of 4.5 Gy\\/h or

Paul Leroux; Steven Lens; Reinhard Voorspoels; Marco Van Uffelen; Wouter De Cock; Michiel Steyaert; Francis Berghmans

2007-01-01

307

Radiation Hardness Studies of InGaAs and Si Photodiodes at 30, 52, & 98 MeV and Fluences to 5 × 1011 PROTONS/CM2  

NASA Astrophysics Data System (ADS)

Here we report the results of an investigation into the effects of ionizing radiation on commercial off-the-shelf InGaAs and Si photodiodes. The photodiodes were exposed to 30, 52, and 98 MeV protons with fluences ranging from 108 -5 ×1011 protons/cm2 at the Indiana University Cyclotron Facility. We tested the photodiodes for changes to their dark current and their relative responsivity as a function of wavelength. The Si photodiodes showed increasing damage to their responsivity with increasing fluence; the InGaAs photodiodes showed significantly increased dark current as the fluence increased. In addition, we monitored the absolute responsivity of the InGaAs photodiodes over their entire bandpass. Our measurements showed no evidence for broadband degradation or graying of the response at the fluences tested. All measurements in this investigation were made relative to detectors traceable to NIST standards.

Baptista, B. J.; Mufson, S. L.

308

How Hard is Chocolate?  

NSDL National Science Digital Library

Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

2007-12-20

309

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

310

Ordering of hard particles between hard walls  

NASA Astrophysics Data System (ADS)

The structure of a fluid of hard Gaussian overlap particles of elongation ? = 5, confined between two hard walls, has been calculated from density-functional theory and Monte Carlo simulations. By using the exact expression for the excluded volume kernel (Velasco E and Mederos L 1998 J. Chem. Phys. 109 2361) and solving the appropriate Euler-Lagrange equation entirely numerically, we have been able to extend our theoretical predictions into the nematic phase, which had up till now remained relatively unexplored due to the high computational cost. Simulation reveals a rich adsorption behaviour with increasing bulk density, which is described semi-quantitatively by the theory without any adjustable parameters.

Chrzanowska, A.; Teixeira, P. I. C.; Ehrentraut, H.; Cleaver, D. J.

2001-05-01

311

An Internet-based exercise as a component of an overall training program addressing medical aspects of radiation emergency management.  

PubMed

The use of ionizing radiation and radioactive materials continues to increase worldwide in industry, medicine, agriculture, research, electrical power generation, and nuclear weaponry. The risk of terrorism using weapons of mass destruction or simple radiological devices also has increased, leading to heightened concerns. Radiation accidents occur as a consequence of errors in transportation of radionuclides, use of radiation in medical diagnosis and therapy, industrial monitoring and sterilization procedures, and rarely, nuclear power generation. Compared to other industries, a small number of serious radiation accidents have occurred over the last six decades with recent cases in the Republic of Georgia, Peru, Japan, and Thailand. The medical, psychological, and political consequences of such accidents can be considerable. A number of programs designed to train medical responders in the techniques of radiation accident management have been developed and delivered in many countries. The low frequency of serious radiation accidents requires constant re-training, as skills are lost and medical staff turnover occurs. Not all of the training involves drills or exercises in which responders demonstrate learning or communication over the broad spectrum of medical response capabilities. Medical preparedness within the context of a total emergency response program is lacking in many parts of the world, particularly in Central and Eastern Europe and the Newly Independent States. This paper describes an effort to enhance medical preparedness in the context of a total program of international cooperation and conventions facilitated by the International Atomic Energy Agency. The paper concludes that novel application of telecommunications technology as part of a training activity in radiation accident preparedness can help address gaps in training in this field in which preparedness is essential but experience and practical field exercises are lacking. PMID:11183457

Levy, K; Aghababian, R V; Hirsch, E F; Screnci, D; Boshyan, A; Ricks, R C; Samiei, M

312

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

313

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

2012-10-24

314

Session: Hard Rock Penetration  

SciTech Connect

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 Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

1992-01-01

315

Space Radiation Environment as it Relates to Electronic System Performance: Or Why Not to Fly Commercial Electronic Components in Space.  

National Technical Information Service (NTIS)

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 aff...

J. L. Barth M. A. Xapsos K. A. LaBel C. Polvey

2005-01-01

316

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

317

On the quality of the hardness kernel and the Fukui function to evaluate the global hardness.  

PubMed

An approximated hardness kernel, which includes the second derivative with respect to the density of the kinetic energy, the electron-electron coulomb repulsion, and the exchange density functionals, has been tested for the calculation of the global hardness. The results obtained for a series of 40 cations and neutral systems and 16 anions represent in most cases an improvement of the results obtained using the HOMO-LUMO gap approach and indicate the viability of this approach to evaluate global hardness. In addition, the relevance of the Fukui function approximation and the role of the three components of the hardness kernel in the evaluation of the global hardness have been analyzed. PMID:17186480

Torrent-Sucarrat, Miquel; Salvador, Pedro; Geerlings, Paul; Solà, Miquel

2007-01-30

318

An energy-conserving two-temperature model of radiation damage in single-component and binary Lennard-Jones crystals  

SciTech Connect

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.

Phillips, Carolyn L. [Applied Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Crozier, Paul S. [Department of Multiscale Dynamic Materials Modeling, Sandia National Laboratories, P.O. Box 5800, MS 1322, Albuquerque, New Mexico 87185-1322 (United States)

2009-08-21

319

Classification and prediction of maize hardness-associated properties using multivariate statistical analyses  

Microsoft Academic Search

Maize kernel hardness and proximate constituents were evaluated by several methods. Proximate constituents and hardness-associated properties were significantly correlated, and their correlation coefficients were improved when moisture, protein, and oil contents were kept constant. Multivariate techniques were applied to create new sets of variables to characterize maize hardness. The principal component scores created by principal component analysis were subjected to

Kyung-Min Lee; Timothy J. Herrman; Jane Lingenfelser; David S. Jackson

2005-01-01

320

Hard Probes 2006: Theoretical Summary  

NASA Astrophysics Data System (ADS)

What makes a hard process a hard probe of hot and dense nuclear matter? In the context of this question, I review recent results shown by the theory speakers at the 2nd Hard Probes Conference in Asilomar.

Wiedemann, Urs Achim

2007-02-01

321

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

322

Radiation Chemistry of Fluoronaphthalene as a Candidate for Absorption Enhancement Component of Chemically Amplified Extreme Ultraviolet Resists  

NASA Astrophysics Data System (ADS)

With the reduction of resist thickness accompanying the miniaturization of feature sizes, increasing the absorption coefficient of extreme ultraviolet (EUV) resists is becoming increasingly important from the viewpoint of the efficient use of incident radiation. The fluorination of the resist polymer is the most effective means of increasing the absorption coefficient. However, it has been pointed out that the dissociative electron attachment of the fluorinated polymer is a problem in the application of the fluorinated polymer to chemically amplified resists used for ionizing radiation. In this study, the electron flow in fluorinated resists was examined using fluoronaphthalene as a possible candidate for suppressing the dissociative electron attachment. The molecular structure dependence of the reactivity with tetrahydrofuran-solvated electrons, the electron transfer from fluoronaphthalene radical anions to triphenylsulfonium-triflate, the dissociation of fluoronaphthalene radical anions, and the charge recombination of fluoronaphthalene radical anions with protons were clarified by the comparison of octafluoronaphthalene, 1-fluoronaphthalene, and naphthalene. The dissociation of fluoronaphthalene radical anions was negligibly slow. Also, the recombination of octafluoronaphthalene radical anions with protons was significantly delayed compared with that of naphthalene radical anions. These results suggest that the molecular structure of fluoronaphthalene is suitable for the molecular design of chemically amplified EUV resists from the viewpoint of the control of electron flow in the acid generation processes.

Ikeda, Sadatatsu; Okamoto, Kazumasa; Yamamoto, Hiroki; Saeki, Akinori; Tagawa, Seiichi; Kozawa, Takahiro

2010-09-01

323

Polydisperse hard spheres at a hard wall  

NASA Astrophysics Data System (ADS)

The structural properties of polydisperse hard spheres in the presence of a hard wall are investigated via Monte Carlo simulation and density functional theory (DFT). Attention is focused on the local density distribution ?(?,z), measuring the number density of particles of diameter ? at a distance z from the wall. Estimates of ?(?,z) are obtained for bulk volume fractions ?b=0.2 and ?b=0.4, and for two choices of the bulk parent distribution: a top-hat form, which we study for degrees of polydispersity ?=11.5% and ?=40.4%, and a truncated Schulz form having ?=40.7%. Excellent overall agreement is found between the DFT and simulation results, particularly at ?b=0.2. A detailed analysis of ?(?,z) confirms the presence of oscillatory size segregation effects, as observed in a previous DFT study [I. Pagonabarraga, M. E. Cates, and G. J. Ackland, Phys. Rev. Lett. 84, 911 (2000)]. For large ?, the character of these oscillation is observed to depend strongly on the shape of the parent distribution. In the vicinity of the wall, attractive ?-dependent depletion interactions are found to greatly enhance the density of the largest particles. The local degree of polydispersity ?(z) is suppressed in this region, while further from the wall it exhibits oscillations.

Buzzacchi, Matteo; Pagonabarraga, Ignacio; Wilding, Nigel B.

2004-12-01

324

Optimum component test plans for systems with dependent components  

Microsoft Academic Search

An unrealistic and very restrictive assumption of component testing models in the literature is the stochastic independence of the components. The independence assumption is hardly true for a complex system where all components operate under the same environmental conditions which may change randomly in time. We consider such a model where stochastic dependence is due to the common environment that

?. Kuban Altinel; Süleyman Özekici

1998-01-01

325

A fiber detector radiation hardness test  

NASA Astrophysics Data System (ADS)

An intense 146MeV/c pion beam was stopped inside a scintillating fiber detector made out of 12 planes with 16 pixels each, where every pixel consists of /8×8 densely packed scintillating fibers of 500 /?m diameter. The detector was irradiated for 52 h to more than 10 kGy at its center. Before and directly after the irradiation the detector had been exposed to a particle beam to compare the corresponding light output. This study was continued during the following three months using cosmic rays. No damage was found taking into account the measurement errors of 5-10%. A 9 cm deep lucite degrader became irreversibly non-transparent in the irradiation region.

Bähr, J.; Nahnhauer, R.; Nerreter, S.; Shanidze, R.

2000-07-01

326

Radiation Hard by Design Techniques for EEPROM  

Microsoft Academic Search

We present the design and test results for a ra- diation hardened by design 2 k Byte EEPROM fabricated in a commercially available 0.5µm CMOS process. The EEPROM will be used in a small on-chip memory to store key instrument parameters and simple control programs for a microcontroller compatible with Martian surface temperatures on the low end ( 125 C)

Yanyi L. Wong; Mark N. Martin; Richard C. Meitzler; Martin E. Fraeman

2005-01-01

327

Hard superconducting nitrides  

PubMed Central

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic ?-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments.

Chen, Xiao-Jia; Struzhkin, Viktor V.; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel N?rlund; Zhao, Yusheng; Cohen, Ronald E.; Mao, Ho-kwang; Hemley, Russell J.

2005-01-01

328

Hard superconducting nitrides.  

PubMed

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic delta-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments. PMID:15728352

Chen, Xiao-Jia; Struzhkin, Viktor V; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel Nørlund; Zhao, Yusheng; Cohen, Ronald E; Mao, Ho-kwang; Hemley, Russell J

2005-02-22

329

Persistence of the irradiated host component in thymocyte populations from bone marrow radiation chimeras infected with lymphocytic choriomeningitis virus  

SciTech Connect

The thymus of chimeras made using T cell-depleted donor bone marrow from Thy1.1+ mice and 950 rad Thy 1.2+ recipients is dominated initially by cells expressing the Thy 1.2+ phenotype of the irradiated host. The thymocyte population recovered at 2 weeks after reconstitution comprises 80% Thy 1.2+ cells (host), the remainder being Thy 1.1+ (donor). This situation is normally reversed within a further week, with the host Ty 1.2+ (donor). This situation is normally reversed within a further week, with the host Thy 1.2+ thymocytes being present at a frequency of less than 5% from Week 4. Infection with lymphocytic choriomeningitis virus (LCMV) at 1 week after reconstitution with bone marrow causes a profound and persistent drop in the total number of thymocytes. The decline is equivalent for all categories of donor-derived thymocytes defined by two-color flow microfluorometric analysis for CD4 and CD8. However, there is a partial compensation by the retention of cells originating from the Thy 1.2+ host, which constitute 30-40% of the total thymocyte pool as late as 8 weeks after administration of bone marrow in the LCMV-infected chimeras. These radiation-resistant precursors give rise to CD4-8-, CD4-8+, CD4+8-, and CD4+8+ thymocytes, with the latter category being present at increased frequency. The potential skewing of the mature T cell repertoire as a consequence of persistent virus infection is discussed.

Lynch, F.; Ceredig, R.; Hartley, D.; Doherty, P.C.

1989-02-01

330

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

331

Study of metallic components of historical organ pipes using synchrotron radiation X-ray microfluorescence imaging and grazing incidence X-ray diffraction.  

PubMed

A comparative study of the composition and microstructure of two different brass alloys from reed pipes, one from a Spanish baroque organ and the other from a modern one, was carried out. This study allowed us to determine the procedure followed to produce the brass used to make ancient reed pipes. Moreover the distribution and correlation of lead and other trace elements present into the main component of the brass, the copper and zinc phases, of the historical tongues and shallots were established. This chemical composition was compared with that of a tongue from a twentieth-century organ. The whole study was accomplished using a combination of laboratory and synchrotron radiation techniques. X-ray fluorescence was the technique used to obtain elemental and chemical imaging of the main phases and the trace elements at a sub-micrometer scale. PMID:19730830

Herrera, L K; Justo, A; Muñoz-Páez, A; Sans, J A; Martínez-Criado, G

2009-12-01

332

Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components  

NASA Astrophysics Data System (ADS)

The recently reported finding that plant matter and living plants produce significant amounts of the important greenhouse gas methane under aerobic conditions has led to an intense scientific and public controversy. Whereas some studies question the up-scaling method that was used to estimate the global source strength, others have suggested that experimental artifacts could have caused the reported signals, and two studies, one based on isotope labeling, have recently reported the absence of CH4 emissions from plants. Here we show using several independent experimental analysis techniques that dry and detached fresh plant matter, as well as several structural plant components, emit significant amounts of methane upon irradiation with UV light and/or heating. Emissions from UV irradiation are almost instantaneous, indicating a direct photochemical process. Long-time irradiation experiments demonstrate that the size of the CH4 producing reservoir is large, exceeding potential interferences from degassing or desorption processes by several orders of magnitude. A dry leaf of a pure 13C plant produces 13CH4 at a similar rate as dry leaves of non-labeled plants produce non-labeled methane.

Vigano, I.; van Weelden, H.; Holzinger, R.; Keppler, F.; McLeod, A.; Röckmann, T.

2008-06-01

333

Polysiloxane-based scintillators doped with oligophenylenes: Effect of color centers on radiation stability  

NASA Astrophysics Data System (ADS)

Radiation hardness of polysiloxane-based scintillators doped with oligophenylene fluors has been investigated. Radiation damage to the chromophores themselves is negligible. The main component of light output loss under irradiation is due to production of color centers by substituents introduced into the fluors to increase solubility. When these oligophenylenes are used as primary fluors they are stable to exposures in excess of 107 rad.

Feygelman, Vladimir M.; Walker, James K.; Harmon, Julie P.

1990-05-01

334

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

335

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

336

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

337

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

338

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

339

Rad-hard electronics study for SSC detectors  

Microsoft Academic Search

The radiation environment in a SSC detector operating at a luminosity of 10³³ cm⁻²s⁻¹ will put stringent requirements on radiation hardness of the electronics. Over the expected 10 year life-time of a large detector, ionizing radiation doses of up to 20 MRad and neutron fluences of 10¹⁶ neutrons\\/cm² are projected. At a luminosity of 10³⁴ cm⁻²s⁻¹ even higher total doses

T. Ekenberg; J. Dawson; A. Stevens; W. Haberichter

1991-01-01

340

Effect of hard bake process on LER  

NASA Astrophysics Data System (ADS)

Line-edge roughness (LER) continues to be one of the biggest challenges as the CD size shrinks down to sub 100 nm. It is shown that resist components as well as illumination conditions play a big role. Influence of resist components in both 248 and 193nm chemically amplified resist formulations has been reported but the root cause is not fully understood and may be platform or even specific formulation dependent. This paper attempts to tackle the issue from the processing side. Effects of a simple hard bake process on the LER were studied. In the hard bake process, a given resist pattern was typically baked close to the glass-transition temperature after the development process. LER improved dramatically due to melting down of the rough surface. However, the wall angle of the edge lines also started to degrade at the optimum hard bake temperature. Studies on the effects of polymer Tg, hard bake temperature and time and the issues of the process are discussed.

Padmanaban, Munirathna; Rentkiewicz, David; Lee, SangHo; Hong, Chisun; Lee, Dongkwan; Rahman, Dalil; Sakamuri, Raj; Dammel, Ralph R.

2005-05-01

341

Comparison of Ultrasonic-Hardness-Tester Hardness and Micro-Vickers Hardness  

NASA Astrophysics Data System (ADS)

Examination methods of industrial hardnesses such as Vickers hardness and Rockwell hardness are used for the characteristic measurement of materials. These methods assume that the length of the plastic deformation is a reliable index of hardness. Since the indenters used in these methods produce deformation imprints and the methods themselves are difficult to perform, they cannot be used for the ready measurement of hardness. Recently, a nondestructive ultrasonic hardness tester that is capable of measuring the hardness of materials has been developed by the authors. This tester can measure small areas rapidly and accurately. Another advantage of this tester is that it can measure a wide range of hardness. Therefore, we consider that it is highly advantageous to replace conventional hardness testers with ultrasonic hardness testers. In this study, ultrasonic hardness was compared with micro-Vickers hardness. As a result, it was clarified that micro-Vickers hardness was in proportion to the 4.25th power of the index of ultrasonic hardness.

Aoyagi, Ryoji; Umezu, Kaoru

2007-07-01

342

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

343

Radiation tolerant IP Cores for the control and readout of Front-End electronics in High Energy Physics experiments  

Microsoft Academic Search

In future HEP experiments the increased luminosity and the need of higher detector performance will push toward severe requirements on radiation hardness and power dissipation of hardware components. The use of “standard” and flexible protocols, modular architectures and IP-cores available to ASIC and FPGA designers will contribute to meet these requirements, while keeping development and production costs under control. The

G. Bianchi; N. Costantino; L. Fanucci; J. Incandela; G. Magazzu; C. Tongiani; S. Saponara

2011-01-01

344

Hard surface detergency  

Microsoft Academic Search

In a study of hard surface detergency using glyceryl trioleate, oleic acid, and octanoic acid soils with three types of anionic\\u000a and three types of nonionic syndets, only potassium laurate showed maximum detergency at the CMC (critical micelle concentration),\\u000a with the potassium laurateoctanoic acid system being an exception. In general glyceryl trioleate and oleic soil removal (180°F.)\\u000a at the CMC

A. M. Mankowich

1961-01-01

345

Eat Smart. Play Hard.  

NSDL National Science Digital Library

The Food and Nutrition Service of the US Department of Agriculture offers online educational material as part of "Eat Smart. Play Hard." -- a public information campaign designed to promote healthy living in American children. While the site and its materials are geared for use by state and local program coordinators, anyone is welcome to download the available information and activity sheets. Click on Cool Stuff for Kids for nutrition-related puzzles and games. Parents Place offers informational brochures and an educational bookmark.

346

Fabrication of Hard Glass Plates.  

National Technical Information Service (NTIS)

This report describes the fabrication of hard glass for use in ballistic application. The work consisted of establishing optimum composition and process conditions for several different glasses. Properties such as Knoop hardness, density, flexural strengt...

A. Z. Hed M. A. Ali

1974-01-01

347

SUPER HARD SURFACED POLYMERS  

SciTech Connect

High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

Mansur, Louis K [ORNL; Bhattacharya, R [UES, Incorporated, Dayton, OH; Blau, Peter Julian [ORNL; Clemons, Art [ORNL; Eberle, Cliff [ORNL; Evans, H B [UES, Incorporated, Dayton, OH; Janke, Christopher James [ORNL; Jolly, Brian C [ORNL; Lee, E H [Consultant, Milpitas, CA; Leonard, Keith J [ORNL; Trejo, Rosa M [ORNL; Rivard, John D [ORNL

2010-01-01

348

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

349

Hard-pan soils - Management  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hard pans, hard layers, or compacted horizons, either surface or subsurface, are universal problems that limit crop production. Hard layers can be caused by traffic or soil genetic properties that result in horizons with high density or cemented soil particles; these horizons have elevated penetrati...

350

Hard diffraction in CDF  

SciTech Connect

The aim of these studies is to use hard (large Q{sup 2}) processes to investigate the partonic nature of the pomeron. We have measured events with large rapidity gaps between balancing high E{sub T} jets, events with two forward (same-side) jets and a large gap (diffractive di-jet production), diffractive W{sup {+-}} production and diffractive heavy flavor (J/{psi} and b-quark) production. Candidate events of the type double-pomeron {yields} di-jet are observed. I close with a look at the future (Run II).

Albrow, M.G.; CDF Collaboration

1997-10-01

351

Hard metal composition  

DOEpatents

A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

Sheinberg, Haskell (Los Alamos, NM)

1986-01-01

352

Inverse Compton Origin of the Hard X-ray and Soft gamma-ray Emission from the Galactic Ridge  

SciTech Connect

A recent re-determination of the non-thermal component of the hard X-ray to soft {gamma}-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary electrons and positrons contribute to the emission. The prediction uses the GALPROP model and includes a new calculation of the interstellar radiation field. This may solve a long-standing mystery of the origin of this emission, and potentially opens a new window on Galactic cosmic rays.

Porter, Troy A.; Moskalenko, Igor V.; Strong, Andrew W.; Orlando, Elena; Bouchet, Laurent

2008-09-30

353

[Hard metal interstitial lung disease].  

PubMed

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 metals. The evaluation of wedge biopsies by scanning electronic microscope can be very helpful in those cases without a specific diagnosis. PMID:19962814

Montero, M Angeles; de Gracia, Javier; Morell, Ferràn

2009-12-04

354

Diffusion welding of hard alloys  

Microsoft Academic Search

1.The hot pressing method, which is characterized by induction heating in graphite dies, can be used for the diffusion welding of tungsten-cobalt hard alloys and the “baking-on” of new hard-alloy layers consisting of hard-alloy powder mixtures.2.Mechanical tests have shown that the strength secured by means of diffusion welding at 1400° according to the proposed method approaches the strength of the

K. S. Gerasimenko; S. I. Spirina

1967-01-01

355

Microstructure, Composition, and Hardness of Rockwell C Hardness Blocks.  

National Technical Information Service (NTIS)

The microstructure, composition, and hardness of hardness blocks (Rockwell C scale) that are commonly available in the country were examined. Blocks near HRC levels of 25, 45, and 65 were obtained from each of six sources to represent the HRC measurement ...

T. A. Siewert A. Tomer

1991-01-01

356

HARD X-RAY EMISSION ASSOCIATED WITH WHITE DWARFS. III  

SciTech Connect

Hard X-ray emission associated with white dwarfs (WDs) can be used to diagnose the presence of late-type binary companions, mass accretion from companions, or physical processes with unknown origins. Since our previous systematic searches for hard X-ray emission associated with WDs, the Galactic WD catalog has been augmented by >10,000 new WDs from the Sloan Digital Sky Survey and new X-ray point-source catalogs from XMM-Newton and ROSAT have become available. Therefore, we have extended the search using the updated catalogs, and found 17 new cases of WDs associated with hard X-ray emission. The 32 WDs associated with hard X-ray emission, from the current and previous searches, can be divided into five categories: (1) binary WD with a coronal companion, (2) binary WD with mass transfer from a companion, (3) single hot WD with a hard X-ray component peaking near 1 keV in addition to a soft photospheric component, (4) two PG 1159 stars with very faint X-ray emission in the 0.9-2.0 keV band, and (5) two DA WDs whose photospheric emission component has a hard shoulder extending to 0.5-0.9 keV. The origin of the hard X-ray emission in the latter three categories is not yet known. Deeper X-ray observations with higher angular and spectral resolutions are needed to help us understand these WDs' hard X-ray emission.

BilIkova, Jana; Chu, You-Hua; Gruendl, Robert A.; Maddox, Larry A. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green St., Urbana, IL 61801 (United States)

2010-11-15

357

Development of hard X-ray polarimeter for ?-ray bursts  

Microsoft Academic Search

The radiation mechanism of gamma-ray bursts (GRBs) is one of the most interesting topics in the field of astrophysics. According to the fireball model, the ?-rays from GRBs should be much polarized. So we have been developing a Compton scattering type hard X-ray polarimeter for GRBs using segmented scintillators and multianode photomultipliers. We carried out basic experiments and computer simulations

S. Gunji; T. Suzuki; F. Sato; H. Sakurai; F. Tokanai; Y. Saito; A. Kubota

2004-01-01

358

Post-irradiation effects in a rad-hard technology  

Microsoft Academic Search

We studied radiation and post-irradiation effects in a CMOS rad-hard technology. The physical properties of charge detrapping in the gate oxide, investigated by isothermal and isochronal annealings, are dependent on the experimental procedure (bias, time storage, temperature, dose level)

C. Chabrerie; O. Musseau; O. Flament; J.-L. Leray; J.-C. Boudenot; B. Shipman; H. Callewaert

1995-01-01

359

The hard gluon component of the QCD Pomeron  

SciTech Connect

The authors argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Super-Critical phase of Reggeon Field Theory. That the color compensation takes place at a longer distance is consistent with the Pomeron carrying odd color charge parity.

White, A.R. [Argonne National Lab., IL (United States). High Energy Physics Div.

1996-10-20

360

Measuring the Hardness of Minerals  

ERIC Educational Resources Information Center

|The author discusses Moh's hardness scale, a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness. Development history of the scale is outlined, as well as a description of how the scale is used…

Bushby, Jessica

2005-01-01

361

Nonconventional Hard-Metal Compositions.  

National Technical Information Service (NTIS)

A novel hard-metal composition comprising borides and carbides of tungsten, nickel, and iron is made by reaction hot-pressing mixtures of elemental tungsten, nickel, and iron powders with small quantities of boron carbide. The hardness of these compositio...

H. Sheinberg

1982-01-01

362

Hard Disk Drive Manufacturing Optimization  

Microsoft Academic Search

Rapid increase in demand for high hard disk data storage density is forcing R&D centers and manufacturing companies to focus on continuous improvement of hard disk drive (HDD) performance. Current HDD records data on the magnetic disk or platter by controlling a magnetizing ferromagnetic material directionally. The data are read from the disk using a magnetic head by detecting the

Riadh Zaier; Jamil Abdo

2012-01-01

363

Photospheric thermal radiation from GRB collapsar jets  

NASA Astrophysics Data System (ADS)

Photospheric thermal radiation components from gamma-ray burst (GRB) jets are estimated based on relativistic hydrodynamic simulations of jet propagation. The light curves and spectra are derived, considering viewing angle effects. The light curves exhibit several seconds time variability and the luminosity is as large as that of GRB prompt emission. For observers at a viewing angle of several degrees the spectra below the peak energy are much softer than that of Planck distribution and close to typical GRB spectrum. Whereas the spectra for observers at small viewing angle are hard and close to Planck distribution. Numerical Amati and Yonetoku relations are reproduced.

Mizuta, Akira; Nagataki, Shigehiro

2012-09-01

364

Synchrotron radiation total reflection X-ray fluorescence and energy dispersive X-ray fluorescence analysis on AP1™ films applied to the analysis of trace elements in metal alloys for the construction of nuclear reactor core components: a comparison  

Microsoft Academic Search

Synchrotron radiation induced total reflection X-ray fluorescence and conventional 45° energy dispersive X-ray fluorescence analysis using a 150-nm-thick AP1™ film as sample carrier have been exploited for the elemental analysis of traces in alloys used for the construction of reactor core components of nuclear power plants. Both techniques are well suited for the analysis since they require a low amount

G. Pepponi; P. Wobrauschek; F. Hegedüs; C. Streli; N. Zöger; C. Jokubonis; G. Falkenberg; H. Grimmer

2001-01-01

365

Failure analysis of components in compressor vane  

Microsoft Academic Search

The paper presents a failure analysis of components damaged in compressor vane. In order to investigate the damage mechanism and failure causes of components, macroscopic and microscopic observations, microstructural investigations, chemical analysis and hardness measurement have been performed. The results show that the damaged components are caused by fractured blades of 1st stage rotor. In all 1st stage rotor blades,

Fengjun Lv; Guoru Fu; Zhigang Cai; Dong Zhang

2009-01-01

366

Automated Component Adaptation by Forced Simulation  

Microsoft Academic Search

Embedded systems are often designed by experienced designers by interfacing appropriate programmable components to a microprocessor to meet particular design requirements. However, during automated synthesis of these systems, reuse of programmable components hardly takes place. The primary reason is the lack of algorithms that can perform component adaptation like a human designer. In this paper, we present an algorithm based

Partha S. Roop; Arcot Sowmya; S. Ramesh

2000-01-01

367

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

368

RADIATION BALANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The balance of energy on the earth's surface represents the difference between incoming and outgoing radiation. There are two components in both the incoming and ongoing fractions and are separated by wavelength as shortwave (less than 5 um) and longwave (greater than 5 um). Shortwave radiation or...

369

Nanopatterned ferroelectrics for ultrahigh density rad-hard nonvolatile memories.  

SciTech Connect

Radiation hard nonvolatile random access memory (NVRAM) is a crucial component for DOE and DOD surveillance and defense applications. NVRAMs based upon ferroelectric materials (also known as FERAMs) are proven to work in radiation-rich environments and inherently require less power than many other NVRAM technologies. However, fabrication and integration challenges have led to state-of-the-art FERAMs still being fabricated using a 130nm process while competing phase-change memory (PRAM) has been demonstrated with a 20nm process. Use of block copolymer lithography is a promising approach to patterning at the sub-32nm scale, but is currently limited to self-assembly directly on Si or SiO{sub 2} layers. Successful integration of ferroelectrics with discrete and addressable features of {approx}15-20nm would represent a 100-fold improvement in areal memory density and would enable more highly integrated electronic devices required for systems advances. Towards this end, we have developed a technique that allows us to carry out block copolymer self-assembly directly on a huge variety of different materials and have investigated the fabrication, integration, and characterization of electroceramic materials - primarily focused on solution-derived ferroelectrics - with discrete features of {approx}20nm and below. Significant challenges remain before such techniques will be capable of fabricating fully integrated NVRAM devices, but the tools developed for this effort are already finding broader use. This report introduces the nanopatterned NVRAM device concept as a mechanism for motivating the subsequent studies, but the bulk of the document will focus on the platform and technology development.

Brennecka, Geoffrey L.; Stevens, Jeffrey; Scrymgeour, David; Gin, Aaron V.; Tuttle, Bruce Andrew

2010-09-01

370

Structure and Properties of Free Radicals: An Electron Spin Resonance Study of Radiation Damage to Nucleic Acid and Protein Components and to Some Sulfur-Substituted Derivitives.  

National Technical Information Service (NTIS)

When cellular systems are exposed to ionizing radiation the long-term effects may range from minor disturbances to such dramatic changes as mutations and cell death. The processes leading to these macroscopical injuries are primarily confined at the molec...

E. Sagstuen

1979-01-01

371

Diffuse hard X-ray and gamma-ray emission from M87  

SciTech Connect

Radio measurements are used to infer the relativistic electron distributions in the central and halo regions of M87. From these distributions and the inferred relativistic proton components, the hard X-ray and gamma-ray spectrum of M87, is predicted, taking into account all relevant radiative processes. The feasibility of measuring the high-energy spectrum of M87 with the High Energy Gamma-Ray Telescope (Egret) on board the Gamma Ray Observatory (GRO) is discussed. Comparison of our calculation with present gamma-ray flux upper limits leads to a lower limit of 1.5 micro-G on the mean value of the halo magnetic field. 37 references.

Dermer, C.D.; Rephaeli, Y.

1988-06-01

372

Eikonal Corrections to Hard Processes.  

National Technical Information Service (NTIS)

We consider within Quantum Chromodynamics those semi-inclusive hard processes where two large mass scales appear. Summation of single and double logarithms arising from soft gluonic emission introduces eikonal form factors. We obtain a satisfactory agreem...

G. Bordes A. Nicolaidis

1981-01-01

373

Melting of polydisperse hard disks  

NASA Astrophysics Data System (ADS)

The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find that while there is pronounced fractionation in polydispersity, the apparent density-polydispersity gap does not increase in width, contrary to 3D polydisperse hard spheres. The point where the Young’s modulus is low enough for the dislocation unbinding to occur moves with the apparent melting point, but stays within the density gap, just like for the monodisperse hard-disk system. Additionally, we find that throughout the accessible polydispersity range, the bound dislocation-pair concentration is high enough to affect the dislocation-unbinding melting as predicted by Kosterlitz, Thouless, Halperin, Nelson, and Young.

Pronk, Sander; Frenkel, Daan

2004-06-01

374

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

375

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

376

Interfacial phenomena in hard-rod fluids  

NASA Astrophysics Data System (ADS)

This thesis addresses questions of interfacial ordering in hard-rod fluids at coexistence of the isotropic and nematic phases and in their contact with simple model substrates. It is organized as follows. Chapter II provides some background information about the relation between the statistical mechanical and thermodynamical level of descriptions of bulk hard-rod fluids, as well as introduces the asymptotically exact Onsager model, and some basic facts of interfacial thermodynamics. Chapter III represents studies of the simplest free IN interface in a fluid of monodisperse Onsager hard rods. For the analysis of this system we develop an efficient perturbative method to determine the (biaxial) one-particle distribution function in inhomogeneous systems. Studies of the free planar isotropic-nematic interfaces are continued in Chapter IV, where they are considered in binary mixtures of hard rods. For sufficiently different particle shapes the bulk phase diagrams of these mixtures exhibit a triple point, where an isotropic (I) phase coexists with two nematic phases (N1 and N2) of different composition. For all explored mixtures we find that upon approach of the triple point the IN2 interface shows complete wetting by an intervening N1 film. We compute the surface tension of isotropic-nematic interfaces, and find a remarkable increase with fractionation. These studies are complemented by an analysis of bulk phase behavior and interfacial properties of nonadditive binary mixtures of thin and thick hard rods in Chapter V. The formulation of this model was motivated by recent experiments in the group of Fraden, who explored the phase behavior of a mixture of viruses with different effective diameters. In our model, species of the same types are considered as interacting with the hard-core repulsive potential, whereas the excluded volume for dissimilar rods is taken to be larger (smaller) then for the pure hard rods. Such a nonadditivity enhances (reduces) fractionation at the isotropic-nematic (IN) coexistence and may induce (suppress) a demixing of the high-density nematic phase into two nematic phases of different composition (N1 and N2). Studies of their interfaces show an increase of the surface tension with fractionation at the IN interface, and complete wetting of the IN2 interface by the N1 phase upon approach of the triple point coexistence. In all explored cases bulk and interfacial properties of the nonadditive mixtures exhibit a surprising similarity with the properties of additive mixtures of larger diameter ratio. In Chapter VI we consider properties of a monodisperse hard-rod fluid in contact with the single wall (W). Studies of surface properties of a fluid of Onsager hard rods represent significant numerical difficulties, therefore we consider a simpler model fluid of hard rods with a restricted number of allowed orientations. Within this model, known as the Zwanzig model, we explore the thermodynamic properties of a fluid of monodisperse hard rods in contact with a model substrate represented by a hard wall with a short-ranged attractive or repulsive ``tail''. The attraction enhances the orientational ordering near the wall in both isotropic and nematic phases, and shifts the transition from uniaxial (U) to biaxial (B) symmetry in the isotropic surface layer to lower chemical potentials, whereas the wetting properties of the substrate remain similar to those of the pure hard wall. The soft repulsion reduces the density in the surface layer, which leads to the shift (or even suppression) of the UB transition, and strong modification of wetting properties. At the WI interface one always finds the wetting transition at sufficiently large repulsion, whereas a drying transition at the WN interface is observed only for sufficiently long-ranged potentials. In Chapter VII we explore some limitations of models of hard-rod fluids with a finite number of allowed orientations. Within Onsager's second virial theory we construct their bulk phase diagrams. For a one-component fluid, we show that the discretization of the orien

Shundyak, K. Y.

2004-05-01

377

30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

378

30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

379

Synchrotron Radiation  

SciTech Connect

This book covers the physical aspects of synchrotron radiation generation and is designed as a textbook and reference for graduate students, teachers and scientists utilizing synchrotron radiation. It is my hope that this text may help especially students and young researchers entering this exciting field to gain insight into the characteristics of synchrotron radiation. Discovered in 1945, synchrotron radiation has become the source of photons from the infrared to hard x-rays for a large community of researchers in basic and applied sciences. This process was particularly supported by the development of electron accelerators for basic research in high energy physics. Specifically, the development of the store ring and associated technologies resulted in the availability of high brightness photon beams far exceeding other sources. In this text, the physics of synchrotron radiation for a variety of magnets is derived from first principles resulting in useful formulas for the practitioner. Since the characteristics and quality of synchrotron radiation are intimately connected with the accelerator and electron beam producing this radiation, a short overview of relevant accelerator physics is included.

Wiedemann, Helmut

2003-08-11

380

Novel method for indirect sensing of hard disk drive imbalance  

Microsoft Academic Search

At present, hard disk drives (HDD) are balanced using external balancing machine after all components of HDD are assembled. Therefore, company's throughput is limited by number of available balancing machines. Besides, imbalance is measured only once after assembly, and for this reason there is no possibility to measure if there is any change in imbalance of HDD during its operation.

Branislav Hredzak; Guoxiao Guo

2004-01-01

381

New Method for Sensorless Measurement of Hard Disk Drives Imbalance  

Microsoft Academic Search

At present, hard disk drives (HDDs) are balanced using external balancing machine after all the components of the HDD are assembled. Therefore, company's throughput is limited by a number of available balancing machines. Besides, an imbalance is measured only once after assembly, and for this reason, there is no possibility to measure if there is any change in imbalance of

Branislav Hredzak; Guoxiao Guo; Jingliang Zhang

2006-01-01

382

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

383

Experimental procedure influence on total dose CMOS inverters hardness  

Microsoft Academic Search

This issue deals with Co60 irradiation results on three commercial CMOS inverters. About ten years ago, it was proved that this type of “soft oxide” component could undergo rebound effect although only rad-hard NMOS was concerned. The work presented here takes into account dose rate (tested over 5 decades) and bias effects. The results of prediction with linear system theory

E. Mondot; J. P. David

1993-01-01

384

Measuring complexity of component based architecture: a graph based approach  

Microsoft Academic Search

Component based software development (CBSD) is an evolving paradigm where emphasis is laid on reuse of existing components and effective designing of components. As complexity of software systems increases, the challenge of CBSD lies in designing highly cohesive, testable components. Researcher community is striving hard to identify the attributes characterizing component-based development and proposing metrics that may help in controlling

Sabnam Sengupta; Ananya Kanjilal; Swapan Bhattacharya

2011-01-01

385

Reliability of CoolMOS™ under extremely hard repetitive electrical working conditions  

Microsoft Academic Search

The papers deals with the behavior of CoolMOS transistors under extremely hard repetitive working conditions like transient avalanche and short-circuit operations. The repetition of these severe working operations is responsible for the devices ageing and results unavoidably in the components failures. A long term campaign of experimental tests was made in order to determine the number of hard working operations

F. Saint-Eve; S. Lefebvre; Z. Khatir

2003-01-01

386

Two-dimensional ground motion at a soft viscoelastic layer/hard substratum site in response to SH cylindrical seismic waves radiated by deep and shallow line sources-I. Theory  

NASA Astrophysics Data System (ADS)

We consider, using theory (herein) and associated synthetic seismograms (in a companion paper), the seismic response of a site comprising a horizontal, homogeneous, soft viscoelastic layer of infinite lateral extent overlying, and in welded contact with, a homogeneous, hard elastic substratum of half-infinite radial extent. We show that for shear-horizontal motion: (1) coupling to Love modes is all the stronger the closer (in the vertical direction) the source (modelled as a line, assumed to lie in the substratum) is to the lower boundary of the soft layer, (2) all anomalous features (such as long duration) of the seismic wavefield, including those for regional earthquakes, are primarily the result of strong excitation of Love modes, (3) 1-D (body wave) type of response is: non-resonant, obtained for deep sources and usually characterized by relatively short durations, (4) for shallow sources and hypocentral distances that are not very large, the response results from a complex interplay of Love mode and body wave contributions, which requires a numerical description (furnished in the companion paper).

Groby, Jean-Philippe; Wirgin, Armand

2005-10-01

387

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

388

Investigation of Plasma Spray Coatings as an Alternative to Hard Chrome Plating on Internal Surfaces.  

National Technical Information Service (NTIS)

Hard chromium electroplating is extensively used by aircraft manufacturers and military maintenance depots to provide wear and/or corrosion resistance or to restore dimensional tolerance to components. However, chrome plating utlizes hexavalent chromium, ...

K. O. Legg B. D. Sartwell J. Legoux M. Nestler C. Dambra

2006-01-01

389

Charged hard spheres in a uniform neutralizing background: The role of thermodynamics selfconsistence.  

National Technical Information Service (NTIS)

Calculations of the thermodynamic properties and pair distribution function of a one-component classical fluid of charged hard spheres in a uniform neutralizing background are reported and compared with Monte Carlo results of Hansen and Weis. Thermodynami...

Z. Badirkhan G. Pastore M. P. Tosi

1991-01-01

390

Indentation hardness evaluation of cathodic arc deposited thin hard coatings  

Microsoft Academic Search

One trend in the development of wear-resistant vapour deposited coatings is to make them increasingly harder and thinner, by improvement and optimisation of the deposition processes. A complex interdependence exists between the individual properties of a coating and a substrate on the one hand, and those of the ‘composite’ coated system on the other. For example, system stiffness and hardness

J. R. Tuck; A. M. Korsunsky; D. G. Bhat; S. J. Bulla

2001-01-01

391

Magnetic levitation for hard superconductors  

SciTech Connect

An approach for calculating the interaction between a hard superconductor and a permanent magnet in the field-cooled case is proposed. The exact solutions were obtained for the point magnetic dipole over a flat ideally hard superconductor. We have shown that such an approach is adaptable to a wide practical range of melt-textured high-temperature superconductors{close_quote} systems with magnetic levitation. In this case, the energy losses can be calculated from the alternating magnetic field distribution on the superconducting sample surface. {copyright} {ital 1998 American Institute of Physics.}

Kordyuk, A.A. [Institute of Metal Physics, 252680 Kiev 142 (Ukraine)

1998-01-01

392

COMPONENTS OF LASER SYSTEMS AND PROCESSES OCCURRING IN THEM: Fast-response system for stabilization of the axis of the angular distribution of laser radiation  

NASA Astrophysics Data System (ADS)

A fast-acting system for stabilization of the axis of the angular distribution of radiation from a continuous-flow CO2 laser is considered. The results of a simulation experiment are reported: they show that it is possible to suppress, by 24-28 dB, fluctuations of the position of the axis in the spectral range 0-20 Hz. This makes the proposed system a promising method for large-aperture laser beams.

Vinogradov, E. G.; Glebova, S. N.; Pavlov, N. V.; Razhenkov, E. T.

1988-09-01

393

On a spatial and temporal asymmetry of the hard X-ray footpoints in solar flares  

NASA Astrophysics Data System (ADS)

The HXT/YOHKOH observations of the hard X-ray footpoints revealed their significant brightness asymmetry in most of the considered flares with one feet showing higher brightness appearing in a shorter timescale than the other one. The corresponding microwave observation of the same flares also showed a spatial and temporal asymmetry between the two footpoints although the feet with higher X-ray emission revealed the lower microwave radiation than from the other one while appearing with some delay. Many authors interpreted these phenomena as a result of the magnetic field difference in these footpoints. However, there is also a significant difference in the energy spectra emitted from different footpoints: one of them has power-law energy distributions while the second one reveals the maxwellian energy distributions. This allows suggesting that there are some topological specifics in the particle acceleration during solar flares. In the present work an attempt is made to describe a collisionless acceleration by the electric field of electrons and protons in a non-neutral current sheet formed by the reconnecting magnetic loops. The proton and electron trajectories inside the current sheet and their energy and pitch-angular spectra were found from a solution of the motion equation for different parameters of electric and magnetic field components. The most important result of the acceleration by a direct current is that the protons and electrons were found ejected into different loop legs corresponding to the opposite signs of the transversal component of the current sheet magnetic field with nearly coherent energies up to 0.1 MeV for protons and 1 MeV for electrons. Since electrons have higher speed of precipitation than protons, so they precipitate faster into deeper atmosphere than the protons. This, in turn, results in a faster appearance of hard X-ray emission in the leg with electrons while in the leg with protons hard X-ray mission occurs later owing to the ambient plasma electrons being energized by the protons, which precipitate slower. An estimation of the electron and proton precipitation times for a standard size loop gives a lower limit for the temporal delay of about 10 seconds that is a very reasonable agreement with the presented hard X-ray RHESSI observations for the flares of 20th and 23rd July 2002.

Zharkova, V. V.; Gordovskyy, M.

2003-04-01

394

Arsenic ion implant energy effects on CMOS gate oxide hardness.  

SciTech Connect

Under conditions that were predicted as 'safe' by well-established TCAD packages, radiation hardness can still be significantly degraded by a few lucky arsenic ions reaching the gate oxide during self-aligned CMOS source/drain ion implantation. The most likely explanation is that both oxide traps and interface traps are created when ions penetrate and damage the gate oxide after channeling or traveling along polysilicon grain boundaries during the implantation process.

Dondero, Richard; Headley, Thomas Jeffrey; Young, Ralph Watson; Draper, Bruce Leroy; Shaneyfelt, Marty Ray

2005-07-01

395

Coherent hard x-ray focusing optics and applications  

Microsoft Academic Search

Coherent hard x-ray beams with a flux exceeding 10⁹ photons\\/second with a bandwidth of 0.1% will be provided by the undulator at the third generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of

W. B. Yun; P. J. Viccaro; J. Chrzas; B. Lai

1991-01-01

396

Coherent hard x-ray focusing optics and applications  

Microsoft Academic Search

Coherent hard x-ray beams with a flux exceeding 10⁹ photons\\/sec with a bandwidth of 0.1% will be provided by undulators at the third-generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic

W. B. Yun; P. J. Viccaro; B. Lai; J. Chrzas

1992-01-01

397

Coherent hard x-ray focusing optics and applications  

Microsoft Academic Search

Coherent hard x-ray beams with a flux exceeding 109 photons\\/sec with a bandwidth of 0.1% will be provided by undulators at the third-generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic

W. B. Yun; P. J. Viccaro; B. Lai; J. Chrzas

1992-01-01

398

Radiation effects microscopy for failure analysis of microelectronic devices.  

SciTech Connect

Microelectronic devices in satellites and spacecraft are exposed to high energy cosmic radiation. Furthermore, Earth-based electronics can be affected by terrestrial radiation. The radiation causes a variety of Single Event Effects (SEE) that can lead to failure of the devices. High energy heavy ion beams are being used to simulate both the cosmic and terrestrial radiation to study radiation effects and to ensure the reliability of electronic devices. Broad beam experiments can provide a measure of the radiation hardness of a device (SEE cross section) but they are unable to pinpoint the failing components in the circuit. A nuclear microbeam is an ideal tool to map SEE on a microscopic scale and find the circuit elements (transistors, capacitors, etc.) that are responsible for the failure of the device. In this paper a review of the latest radiation effects microscopy (REM) work at Sandia will be given. Different SEE mechanisms (Single Event Upset, Single Event Transient, etc.) and the methods to study them (Ion Beam Induced Charge (IBIC), Single Event Upset mapping, etc.) will be discussed. Several examples of using REM to study the basic effects of radiation in electronic devices and failure analysis of integrated circuits will be given.

Doyle, Barney Lee; Dodd, Paul Emerson; Vizkelethy, Gyorgy; Shaneyfelt, Marty Ray; Brice, David Kenneth; Schwank, James Ralph

2004-10-01

399

Electrochemical deposition of hard magnetic materials for MEMS applications  

NASA Astrophysics Data System (ADS)

In this dissertation, electrochemical deposition techniques of cobalt-based hard magnetic alloys and magnetic particle-ferromagnetic matrix composites are investigated in detail. Two cobalt alloy electrodeposition techniques have been developed to deposit thick (>10mum) hard magnetic films for MEMS applications. Residual stress induced by electrodeposition in these materials has been predicted and reduced based on the experimental results. The concept of magnetic composite electrodeposition (MCE) is proposed and its feasibility has been confirmed by experimental results. The MCE technique is further optimized by using a BaFe12O19-CoNiP system based on a systemic investigation of a variety of processing factors, which can affect the magnetic particle incorporation fraction. Using this optimized technique, micro-arrays with various shapes have been realized with a minimum feature size of 8mum. These micro-arrays exhibit excellent hard magnetic properties which are particularly well suited for use as magnetic MEMS actuator components.

Guan, Shan

400

A hard case for modeling  

Microsoft Academic Search

What happens to a human head when it is hit in an accident or by a weapon, or subjected to the violence of an emergency ejection from a combat plane? This question is something that interests QinetiQ, part of the former UK Defence Evaluation and Research Agency (DERA). Controlled experimentation on live subjects is hardly an option, but computer modeling

George Marsh

2002-01-01

401

Hard Probes 2012: Experimental Summary  

NASA Astrophysics Data System (ADS)

The 5thinternational Conference on Hard and Electromagnetic Probes in High-Energy Nuclear Collisions was held in May 2012 in Cagliari, Italy. This contribution summarises some of the experimental highlights presented at the meeting, concentrating on new results from LHC and RHIC on parton energy loss ('jet-quenching') and heavy quark meson production ('quarkonia suppression').

Schukraft, J.

2013-08-01

402

Hard scattering in ?p interactions  

NASA Astrophysics Data System (ADS)

We report on the investigation of the final state in interactions of quasi-real photons with protons. The data were taken with the H1 detector at the HERA ep collider. Evidence for hard interactions is seen in both single particle spectra and jet formation. The data can best be described by inclusion of resolved photon processess as predicted by QCD.

Ahmed, T.; Andreev, V.; Andrieu, B.; Arpagaus, M.; Babayev, A.; Bärwolff, H.; Ban, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, G. A.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Berthon, U.; Bertrand-Coremans, G.; Besancon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, C.; Cozzika, G.; Criegee, L.; Cvach, J.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Delbuono, L.; Devel, M.; Deroeck, A.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Feng, Y.; Fensome, I. F.; Ference, J.; Ferrarotto, F.; Flauger, W.; Fleischer, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formanek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gellrich, A.; Gennis, M.; Gensch, U.; Genzel, H.; Gerhards, R.; Gillespie, D.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Goldberg, M.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Handschuh, D.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Hartz, P.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Hedgecock, R.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladky, J.; Hoeger, K. C.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Jabiol, M. A.; Jacholkowska, A.; Jacobson, C.; Jaffre, M.; Jönsson, L.; Johannsen, K.; Johnson, D.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kasarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurca, T.; Kurzhöfer, J.; Kuznik, B.; Lander, R.; Landon, M. P. J.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Lenhardt, U.; Leuschner, A.; Leverenz, C.; Levin, D.; Levonian, S.; Ley, Ch.; Lindström, G.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milone, V.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Morton, J. M.; Müller, K.; Murin, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newton, D.; Nguyen, H. K.; Niebergall, F.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prosi, R.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Ribarics, P.; Riech, V.; Riedlberger, J.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Ryseck, E.; Sacton, J.; Sahlmann, N.; Sanchez, E.; Sankey, D. P.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schröder, V.; Schulz, M.; Schwind, A.; Scobel, W.; Seehausen, U.; Sell, R.; Seman, M.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Smolik, L.; Soloviev, Y.; Spitzer, H.; Staroba, P.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Stella, B.; Stephens, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Thompson, G.; Thompson, R. J.; Tichomirov, I.; Trenkel, C.; Truöl, P.; Tchernyshov, V.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Vanesch, P.; Vartapetian, A.; Vasdik, J.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegner, A.

1992-12-01

403

Infinite Hard-Sphere System.  

National Technical Information Service (NTIS)

The time-evolution for the system of infinitely many particles in space interacting by a hard-sphere potential is constructed. Examples abound of configurations of the infinite system having more than one solution to the Newtonian equations of motion. A r...

R. K. Alexander

1975-01-01

404

Fatigue of biomaterials: Hard tissues  

Microsoft Academic Search

The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the mineralized (roughly 50% mineral by volume or greater) and load-bearing tissues of the human body; it includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g.

D. Arola; D. Bajaj; J. Ivancik; H. Majd; D. Zhang

2010-01-01

405

Evaluation of aging degradation of structural components  

SciTech Connect

Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center_dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

Chopra, O.K.; Shack, W.J.

1992-03-01

406

Evaluation of aging degradation of structural components  

SciTech Connect

Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

Chopra, O.K.; Shack, W.J.

1992-03-01

407

Methane emissions from six crop species exposed to three components of global climate change: temperature, ultraviolet-B radiation and water stress.  

PubMed

We examined the effects of temperature, ultraviolet-B (UVB) radiation and watering regime on aerobic methane (CH(4)) emission from six crops-faba bean, sunflower, pea, canola, barley and wheat. Plants were grown in controlled-environment growth chambers under two temperature regimes (24/20 and 30/26 degrees C), three levels of UVB radiation [0 (zero), 5 (ambient) and 10 (enhanced) kJ m(-2) d(-1)] and two watering regimes (well watered and water stressed). A gas chromatograph with a flame ionization detector was used to measure CH(4) emission rates [ng g(-1) dry weight (DW) h(-1)] from detached fresh leaves of each species and attached leaves of pea plants. Plant growth [stem height, leaf area (LA) and aboveground dry matter (AG biomass)] and gas exchange [net CO(2) assimilation (A(N)), transpiration (E) and water use efficiency (WUE)] were also determined. We found that higher temperature, water stress and UVB radiation at the zero and enhanced levels significantly enhanced CH(4) emissions. Crop species varied in CH(4) emission, which was highest for pea and lowest for barley. Higher temperature and water stress reduced all growth parameters, whereas ambient and enhanced UVB decreased stem height but increased LA and AG biomass. Higher temperature decreased A(N) and WUE but increased E, whereas water stress decreased A(N) but increased E and WUE. Zero and enhanced UVB reduced A(N) and E. Growth and gas exchange varied with species. Overall, CH(4) emission was negatively correlated with stem height and AG biomass. We conclude that CH(4) emissions may increase under climatic stress conditions and this extra source might contribute to the 'greenhouse effect'. PMID:19678898

Qaderi, Mirwais M; Reid, David M

2009-07-14

408

LIFE Materials: Topical Assessment Report for LIFE Volume 1 TOPIC: Solid First Wall and Structural Components TASK: Radiation Effects on First Wall  

SciTech Connect

This report consists of the following chapters: CHAPTER A: LIFE Requirements for Materials. Part 1: The structure of the First Wall--Basic requirements; A qualitative view of the challenge; The candidate materials; and Base-line material's properties. CHAPTER B: Summary of Existing Knowledge--Brief historical introduction; Design window; The temperature window; Evolution of the design window with damage; Damage calculations; He and H production; Swelling resistance; Incubation dose for swelling; Design criterion No. 1, Strength; Design criterion No. 2, Corrosion resistance; Design criterion No. 3, Creep resistance; Design criterion No. 4, Radiation induced embrittlement; and Conclusions. CHAPTER C: Identification of Gaps in Knowledge & Vulnerabilities. CHAPTER D: Strategy and Future Work.

Caro, A

2008-11-26

409

Effects of UV radiation on the growth, photosynthetic and photoprotective components, and reproduction of the Caribbean shallow-water coral Porites furcata  

NASA Astrophysics Data System (ADS)

Shallow reef corals can frequently be subjected to high doses of ultraviolet radiation [280-400 nm (UVR)] and have developed mechanisms to cope with this. Nevertheless, slight changes in this stressor may impact their physiology and ultimately their survival. Here, we present results on the effects of artificially enhanced UVR on the growth, reproduction, production of photosynthetic pigments and photoprotective compounds of the Caribbean shallow-water branching coral Porites furcata. Corals were randomly located in one of the three different treatments: normal photosynthetically active radiation (PAR) + UVR; normal PAR+ enhanced UVR; normal PAR+ depleted UVR. Growth rates were measured using the Alizarin red staining method, photosynthetic pigments as well as mycosporine-like amino acids (MAAs) were quantified through high-performance liquid chromatography, and fecundity was estimated after histological analyses. Growth and photosynthetic pigment concentration were negatively correlated with increased UVR, compared to controls exposed to normal UVR. A significant increase in MAAs was also found in colonies under enhanced UVR. Based on their respective concentrations, the primary mycosporine-glycine (?max = 310 nm) and shinorine (?max = 333 nm) are the main contributors to UVR absorption in this species, while the levels of the secondary MAA palythine (?max = 320 nm) tripled toward the end of the 128 days of the experimental period. While several physical factors may influence reef coral physiology, the results suggest that slight increases in UVR can debilitate the skeletal constitution and severely reduce the fecundity of corals living in shallow waters.

Torres-Pérez, J. L.; Armstrong, R. A.

2012-12-01

410

Optimal Component Selection for Component-Based Systems  

NASA Astrophysics Data System (ADS)

In Component-based Software (CBS) development, it is desirable to choose software components that provide all necessary functionalities and at the same time optimize certain nonfunctional attributes of the system (for example, system cost). In this paper we investigate the problem of selecting software components to optimize one or more nonfunctional attributes of a CBS. We approach the problem through the lexicographic multi-objective optimization perspective and develop a scheme that produces Pareto-optimal solutions. Furthermore we show that the Component Selection Problem (CSP) can be solved in polynomial time if the components are connected by serial interfaces and all the objectives are to be minimized, whereas the corresponding maximization problem is NP-hard.

Khan, Muhammad Ali; Mahmood, Sajjad

411

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

Microsoft Academic Search

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 10¹⁴ neutrons\\/cm² 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

A. Stevens; J. Dawson; H. Kraner; V. Radeka; S. Rescia

1990-01-01

412

The underlying event in hard scattering collisions of proton and antiproton at 1.8 TeV  

NASA Astrophysics Data System (ADS)

The structure of events created from hard scattering pp¯ collisions at s = 1.8 TeV is investigated. Among the various sources which produce observable features, the underlying event represents a poorly understood component. The underlying event consists of particles arising from beam beam remnants, initial state radiation, and possible multiple parton interactions. The non-perturbative QCD dynamics which influence the development of the underlying event obfuscate analytic predictions necessitating the use of parameterizations. In order to characterize the underlying event and validate Monte Carlo predictions for QCD hard scattering events, three data samples are formed. Angular regions with respect to objects assumed to arise from hard scattering interactions are defined in the plane transverse to the beam axis allowing specific behavior to be isolated. The toward and away regions contain dominant contributions from outgoing jets and final state gluon radiation. The transverse region is orthogonal to the plane of the hard scattering collision and is particularly sensitive to the underlying event. Min-Bias and Jet20 data are combined into the dijet sample and leading charged jet employed as a reference. The Z boson sample is derived from inclusive electron data and the Z transverse momentum used to form angular regions. The J/? B sample is constructed from dimuon data selected to be compatible with J/? decay. Both leading charged jet and J/? are used to define the correlations in azimuth. The overall structure in dijet and Z boson events is found to be similar and in approximate agreement with the QCD models of HERWIG, ISAJET, and PYTHIA. For the transverse region, HERWIG and ISAJET do not reproduce the data accurately while PYTHIA provides a faithful description of the observations. Comparisons between J/? B data and the dijet and Z boson samples indicate behavior which is consistent. Subtle differences appear between the Z boson and J/? B as a function of J/? data potentially indicating a dependence of the underlying event on the particle created in the hard scattering collision. In order to obtain reliable predictions for physics backgrounds in Run II environments, the underlying event must be correctly modeled.

Haas, Richard Martin

413

Hard spheres out of equilibrium  

NASA Astrophysics Data System (ADS)

In this thesis, experiments and simulations are combined to investigate the nonequilibrium behaviour of hard spheres. In the first chapters we use Molecular Dynamics simulations to investigate the dynamic glass transition of polydisperse hard spheres. We show that this dynamic transition is accompanied by a thermodynamic signature. The higher-order derivatives of the pressure change abruptly at the dynamic glass transition. If a system is compressed beyond this dynamic transition, the pressure increases until it diverges when the system is completely jammed. The density at which the pressure diverges depends on the compression speed. We proceed with experiments on colloidal polymethylmethacrylate (PMMA) particles which closely resemble hard spheres. We investigate the effect of compression using gravity and electric field gradients on the nucleation and on the glass transition. The transition from glass to crystal is gradual and is strongly effected by gravity. We go back to computer simulations to investigate two different techniques to calculate the rate at which a hard-sphere system nucleates. We find that the two techniques yield similar results for the nucleation rate as well as the critical nucleus shape. From this we conclude that the simulation techniques are valid. A combination of simulations and experiments is used to study the nucleation of hard spheres on seed structures. We initiate the nucleation with a seed of particles kept in place by optical tweezers. We show that whereas the nucleation itself can be well described as an equilibrium process, the growth after nucleation can not. We demonstrate that defects play an important role in the growth of the crystal. Colloidal hard spheres can also be driven out of equilibrium using shear. We perform experiments on an equilibrium fluid phase below the coexistence density of the fluid. We show that we can induce order in an equilibrium fluid using oscillatory shear. We find five different phases for varying frequency and amplitude: four known phases and one new phase. The formation of all phases occurs via nucleation and growth and the melting, when the shear is stopped, starts on the edges and near the defects of the crystal phases. In the final chapter, we investigate the interactions between rough colloidal particles in the presence of polymers. We investigate whether surface roughness can be used to reduce the depletion attraction. We find that when the polymer is smaller than the surface roughness the attraction can be reduced significantly compared to smooth colloids.

Hermes, M.

2010-05-01

414

Estimates of HZE particle contributions to SPE radiation exposures on interplanetary missions.  

PubMed

Estimates of radiation doses resulting from possible HZE (high energy heavy ion) components of solar particle events (SPEs) are presented for crews of manned interplanetary missions. The calculations assume a model spectrum obtained by folding measured solar flare HZE particle abundances with the measured energy spectra of SPE alpha particles. These hypothetical spectra are then transported through aluminum spacecraft shielding. The results, presented as estimates of absorbed dose and dose equivalent, indicate that HZE components by themselves are not a major concern for crew protection but should be included in any overall risk assessment. The predictions are found to be sensitive to the assumed spectral hardness parameters. PMID:11538032

Townsend, L W; Cucinotta, F A; Wilson, J W; Bagga, R

1994-01-01

415

Multifactorial Resistance of Bacillus subtilis Spores to High-Energy Proton Radiation: Role of Spore Structural Components and the Homologous Recombination and Non-Homologous End Joining DNA Repair Pathways  

PubMed Central

Abstract The space environment contains high-energy charged particles (e.g., protons, neutrons, electrons, ?-particles, heavy ions) emitted by the Sun and galactic sources or trapped in the radiation belts. Protons constitute the majority (87%) of high-energy charged particles. Spores of Bacillus species are one of the model systems used for astro- and radiobiological studies. In this study, spores of different Bacillus subtilis strains were used to study the effects of high energetic proton irradiation on spore survival. Spores of the wild-type B. subtilis strain [mutants deficient in the homologous recombination (HR) and non-homologous end joining (NHEJ) DNA repair pathways and mutants deficient in various spore structural components such as dipicolinic acid (DPA), ?/?-type small, acid-soluble spore protein (SASP) formation, spore coats, pigmentation, or spore core water content] were irradiated as air-dried multilayers on spacecraft-qualified aluminum coupons with 218 MeV protons [with a linear energy transfer (LET) of 0.4?keV/?m] to various final doses up to 2500 Gy. Spores deficient in NHEJ- and HR-mediated DNA repair were significantly more sensitive to proton radiation than wild-type spores, indicating that both HR and NHEJ DNA repair pathways are needed for spore survival. Spores lacking DPA, ?/?-type SASP, or with increased core water content were also significantly more sensitive to proton radiation, whereas the resistance of spores lacking pigmentation or spore coats was essentially identical to that of the wild-type spores. Our results indicate that ?/?-type SASP, core water content, and DPA play an important role in spore resistance to high-energy proton irradiation, suggesting their essential function as radioprotectants of the spore interior. Key Words: Bacillus—Spores—DNA repair—Protection—High-energy proton radiation. Astrobiology 12, 1069–1077.

Reitz, Gunther; Li, Zuofeng; Klein, Stuart; Nicholson, Wayne L.

2012-01-01

416

X-rays sensing properties of MEH-PPV, Alq? and additive components: a new organic dosimeter as a candidate for minimizing the risk of accidents of patients undergoing radiation oncology.  

PubMed

In this paper, we report our experimental design in searching a smart and easy-to-read dosimeter used to detect 6 MV X-rays for improving patient safety in radiation oncology. The device was based on an organic emissive solutions of poly(2-methoxy-5(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV), aluminum-tris-(8-hydroxyquinoline) (Alq?) and additive components which were characterized by UV-Vis absorption, photoluminescence and CIE color coordinate diagram. The optical properties of MEH-PPV/Alq? solutions have been examined as function of radiation dose over the range of 0-100 Gy. It has shown that MEH-PPV/Alq? solutions are specifically sensitive to X-rays, since the effect of radiation on this organic system is strongly correlated with the efficient spectral overlap between Alq? emission and the absorption of degraded MEH-PPV, which alters the color and photoemission of MEH-PPV/Alq? mixtures from red to yellow, and then to green. The rate of this change is more sensitive when MEH-PPV/Alq? is irradiated in the presence of benzoyl peroxide than when in the presence of hindered phenolic stabilizers, respectively, an accelerator and an inhibitor to activate or inhibit free radical formation. This gives rise to optimize the response curve of the dosimeter. It is clear from the experimental results that organic emissive semiconductors have potential to be used as dedicated and low-cost dosimeters to provide an independent check of beam output of a linear accelerator and therefore to give patients the opportunity to have information on the dose prescription or equipment-related problems a few minutes before being exposed to radiation. PMID:22959619

Schimitberger, T; Ferreira, G R; Akcelrud, L C; Saraiva, M F; Bianchi, R F

2012-09-07

417

Murine natural resistance to Trypanosoma lewisi involves complement component C3 and radiation-resistant, silica dust-sensitive effector cells  

SciTech Connect

The phenomenon of natural (innate) resistance is exemplified by the solid resistance of mice to infection with the rat-specific Trypanosoma lewisi. We provide more information about the mechanism of resistance in this model system. Resistance was not diminished in aged mice or reduced by ionizing radiation or splenectomy. There was no difference in resistance of C5-deficient mice (B10.D2/oSn and AKR) compared with their normocomplementemic counterparts (B10.D2/nSn and C57BL/6). Treatment of mice with cobra venom factor resulted in greatly prolonged survival of T. lewisi in mice. Combined treatment of mice with cobra venom factor and silica dust resulted in not only prolonged survival but also considerable intravascular growth of the parasite and resultant death of the mice. T. lewisi cells from irradiated donor rats, or after surface coat removal with trypsin, were eliminated by inoculated mice more efficiently than were parasites acquired from normal rats. Incubation of trypanosomes obtained from irradiated rats in normal rat serum restored their resistance to rapid elimination. From the results of these studies and other recent investigations, we have concluded that murine resistance to T. lewisi involves activation and binding of C3b by uncoated trypanosomes and concomitant participation of radiation-resistant, silica dust-sensitive effector cells (probably macrophages and neutrophils), and rat plasma proteins, integrated into the trypanosome surface coat, stabilize the coat, make it less susceptible to removal when the trypanosome is present in the mouse bloodstream, and thus delay exposure of underlying molecules (receptors) that activate murine C3.

Albright, J.W.; Albright, J.F.

1985-01-01

418

Hard Photodisintegration of 3He  

NASA Astrophysics Data System (ADS)

Large angle photodisintegration of two nucleons from the 3He nucleus is studied within the framework of the hard rescattering model (HRM). In the HRM the incoming photon is absorbed by one nucleon's valence quark that then undergoes a hard rescattering reaction with a valence quark from the second nucleon producing two nucleons emerging at large transverse momentum . Parameter free cross sections for pp and pn break up channels are calculated through the input of experimental cross sections on pp and pn elastic scattering. The calculated cross section for pp breakup and its predicted energy dependency are in good agreement with recent experimental data. Predictions on spectator momentum distributions and helicity transfer are also presented.

Granados, Carlos

2011-02-01

419

Weld cladding of hard surfaces  

NASA Astrophysics Data System (ADS)

A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

Habrekke, T.

1993-02-01

420

Kinetics of hardness evolution during annealing of gamma-irradiated polycarbonate  

SciTech Connect

This study focuses on the evolution in microhardness values that accompany isothermal annealing in gamma-irradiated polycarbonate (PC). Hardness increases with increasing annealing time, temperature, and gamma radiation dose. A model composed of a mixture of first and zero order structure relaxation is proposed to interpret the hardness data. The rate constant data fit the Arrhenius equation, and the corresponding activation energy decreases with increasing dose. The extent of structural relaxation that controls the hardness in post-annealed PC increases with increasing annealing temperature and dose. The model demonstrates that hardness evolution in PC is an endothermic process. By contrast, when the model is applied to irradiated poly(methyl methacrylate) and hydroxyethyl methacrylate copolymer, hardness evolution is an exothermic process.

Yeh, S. H.; Chen, P. Y.; Lee, Sanboh [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Harmon, Julie [Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250 (United States)

2012-12-01

421

Cyclic strength of hard metals  

Microsoft Academic Search

The fatigue limit of the titanium carbide and tungsten carbide alloys investigated on a basis of 5·108 cycles lies in the range (20–30)·107 Pa, and is thus comparable with the endurance of type ShKh high-carbon (~1% C-Mn-Si-Cr) ball-bearing steels. The strength and character of fracture of the hard metals are determined by the properties and structural state of their phase

N. N. Sereda; A. K. Gerikhanov; M. S. Koval'chenko; L. G. Pedanov

1985-01-01

422

What's on Your Hard Drive?  

Microsoft Academic Search

What’s on Your Hard Drive? Whether you love ’em or hate ’em, dev tools play an integral role in a programmer’s existence. They were (hopefully!) designed to make your job easier, although all too often the exact opposite seems to be the case. Is there a tool so exceptionally brilliant that you just can’t live without it? Have you encountered

Charlene O'Hanlon

2006-01-01

423

Radiation applications: An overview  

SciTech Connect

Radiation has been successfully utilized for medical, industrial, and research applications since Roentgen first discovered X rays in the late 19th century. Today, intense fields of electron, photon, and neutron radiation are used for defense applications, and industrial processing, and both radiation sources and focused beams of radiation are routinely used in medicine for therapy and imaging. These advances in radiation technology have been coupled with the development of high-power reactors and high-power accelerators as well as continued improvements in the dosimetry of the delivered radiation. Radiation also can be a problem that must be dealt with. Aside from the obvious need to shield people and critical apparatus from the harmful effects of ionizing radiation, there are cases where the system must be designed to operate successfully in a radiation field. Reactor components such as fuel, internals, and pressure vessels must operate in neutron fields; fusion systems must operate in intense high-energy neutron fields; microelectronics used in space must operate in electron, proton, and cosmic ray fields; and accelerator components must operate in proton, neutron, and photon fields. Frequently, these components cannot be tested directly in the radiation fields to which they will be subjected, so simulation of the radiation fields with reactors, accelerators, or radiation sources has been developed to cope with this problem. This paper focuses on current applications of radiation processing, radiation effects in electronics, and radiation imaging.

Block, R.C. (Rensselaer Polytechnic Institute, Troy, NY (United States))

1993-01-01

424

Erosion of hard-metal coatings. [Ni-Cr-B  

Microsoft Academic Search

The use of protective coatings on components in fossil-fuel energy processes to provide thermal insulation, corrosion resistance and\\/or wear resistance is becoming more prevalent. In those applications where small, erosive particles occur in the environment, such as in the use of pulverized coal, erosion behavior of the coating becomes an important design consideration. The erosion of several protective, hard-metal-type coatings

A. Levy; T. Bakker; E. Sholz; M. Azadabeh

1982-01-01

425

Surface Integrity Generated by Precision Hard Turning  

Microsoft Academic Search

Rolling contact fatigue tests were conducted to find the effect of precision hard turning. The tests showed that hard turning provides as good a fatigue performance as grinding. Hard turning produces compressive residual stresses in a deep subsurface, which contribute to a long fatigue life. The effect of cutting parameters on residual stress was investigated in order to find why

Y. Matsumoto; F. Hashimoto; G. Lahoti

1999-01-01

426

COMPONENTS OF LASER SYSTEMS AND PROCESSES OCCURRING IN THEM: Utilization of competition between counterpropagating waves for modulation and stabilization of the radiation emitted from a ring laser  

NASA Astrophysics Data System (ADS)

Theoretical and experimental investigations were made of the possibility of increasing the efficiency of intracavity modulation and stabilization of the radiation emitted from ring lasers by utilization of the competition between counterpropagating waves. It was established that in the case of solid-state ring lasers one can switch rapidly the direction of counterpropagating waves both in the case of forced mode locking and in the case of single-mode emission without spike transient processes at a relaxation frequency typical of solid-state lasers. An analysis was made of the conditions for significant reduction of the switching time and a method is suggested for achieving this by simultaneous modulation of the amplitude nonreciprocity and of the coupling between counterpropagating waves. It is shown that highly stable unidirectional single-mode operation of a solid-state ring laser can be achieved as a result of weak modulation of the resonator perimeter. Various time dependences of the intensities of counterpropagating waves and stabilization of bidirectional operation of a solid-state ring laser were achieved using a magnetooptic feedback loop.

Kornienko, L. S.; Nani?, O. E.; Shelaev, A. N.

1988-09-01

427

A first-principles approach to total-dose hardness assurance  

SciTech Connect

A first-principles approach to radiation hardness assurance was described that provides the technical background to the present US and European total-dose radiation hardness assurance test methods for MOS technologies, TM 1019.4 and BS 22900. These test methods could not have been developed otherwise, as their existence depends not on a wealth of empirical comparisons of IC data from ground and space testing, but on a fundamental understanding of MOS defect growth and annealing processes. Rebound testing should become less of a problem for advanced MOS small-signal electronics technologies for systems with total dose requirements below 50--100 krad(SiO{sub 2}) because of trends toward much thinner gate oxides. For older technologies with thicker gate oxides and for power devices, rebound testing is unavoidable without detailed characterization studies to assess the impact of interface traps on devices response in space. The QML approach is promising for future hardened technologies. A sufficient understanding of process effects on radiation hardness has been developed that should be able to reduce testing costs in the future for hardened parts. Finally, it is hoped that the above discussions have demonstrated that the foundation for cost-effective hardness assurance tests is laid with studies of the basic mechanisms of radiation effects. Without a diligent assessment of new radiation effects mechanisms in future technologies, one cannot be assured that the present generation of radiation test standards will continue to apply.

Fleetwood, D.M. [Sandia National Labs., Albuquerque, NM (United States). Radiation Technology and Assurance Dept.

1995-11-01

428

Stationary radiation of objects with scattering media  

Microsoft Academic Search

The radiation observed inside or outside a stationary radiator with a scattering medium is a sum of components, each being determined by, first, the primary radiation from some part of the radiator and, second, the probability of this radiation reaching the region where it is observed. In this review, general and rather simple relations between these components are discussed. These

Inna A Vasileva

2001-01-01

429

Brownian dynamics simulations with hard-body interactions: Spherical particles  

NASA Astrophysics Data System (ADS)

A novel approach to account for hard-body interactions in (overdamped) Brownian dynamics simulations is proposed for systems with non-vanishing force fields. The scheme exploits the analytically known transition probability for a Brownian particle on a one-dimensional half-line. The motion of a Brownian particle is decomposed into a component that is affected by hard-body interactions and into components that are unaffected. The hard-body interactions are incorporated by replacing the ``affected'' component of motion by the evolution on a half-line. It is discussed under which circumstances this approach is justified. In particular, the algorithm is developed and formulated for systems with space-fixed obstacles and for systems comprising spherical particles. The validity and justification of the algorithm is investigated numerically by looking at exemplary model systems of soft matter, namely at colloids in flow fields and at protein interactions. Furthermore, a thorough discussion of properties of other heuristic algorithms is carried out.

Behringer, Hans; Eichhorn, Ralf

2012-10-01

430

Preliminary ground test radiation results of NASA's MPTB dual-rate 1773 experiment  

NASA Astrophysics Data System (ADS)

NASA Goddard Space Flight Center (GSFC) along with the Naval Research Laboratory (NRL) has been at the forefront of the space community in terms of the use of fiber optic data busses and links in the space radiation environment. Previously, we have described the ground radiation test program of the small explorer data system (SEDS) 1773 1 Mbps fiber optic data bus (FODB), as well as its associated in- flight space radiation-induced performance. Further work has also been presented covering higher speed photonic components utilizing III-V materials. Because of the success of the SEDS 1773 FODB coupled with the radiation testing of III-V devices, a second generation FODB capable of both 1 Mbps and 20 Mbps operation is being developed for spaceflight utilization. We present herein preliminary ground test radiation results of hybrid transceiver devices manufactured by Boeing Space Systems that perform the electro-optic and opto-electric translations in support of this medium rate FODB, the AS1773 bus. These devices, designed to be radiation hard (or rad hard), will be flying on NRL's Microelectronics and Photonics Testbed (MPTB) payload as a NASA experiment. This experiment is described in detail elsewhere in this proceedings.

Label, Kenneth A.; Flanegan, Mark; Jackson, George L.; Hawkins, Donald K.; Dale, Cheryl J.; Marshall, Paul W.; Johnson, Donald; Seidleck, Christina; Bonebright, Rodney K.; Kim, Jae H.; Chan, Eric Y.; Bocek, Thomas M.; Bartholet, William G.

1996-10-01

431

Component Lifing.  

National Technical Information Service (NTIS)

Failure mechanisms which can occur in an aircraft engine component in service are categorized into low life failures, macroscopically nonlocalized damage accumulation, and macroscopically localized damage accumulation. The methods used to avoid these fail...

A. C. Pickard

1986-01-01

432

Silicon Refractive optics for hard X-rays  

NASA Astrophysics Data System (ADS)

X-rays refractive optics has made a real success in a hard radiation domain promising for many applications. An analysis made of refractive materials properties, which are most suitable for this new kind of X-ray focusing optics shows that in silicon refraction effects prevail on attenuation. A wide variety of technologies dedicated to microstructure formation on Si make it as a most suitable one. Using electron beam lithography and deep plasma etching planar parabolic profiles are produced with the focal distance 1 m on 17.4 keV radiation. They are tested on synchrotron radiation at beamline X47 SPRING-8. Experiments carried out open the way to construct kinoform refracting profiles, which exceed simple parabolas in gain and aperture. A number of kinoform profiles on silicon is created for energies up to 50 keV, which at apertures 2 mm have calculated gain up to 5000. Some focusing properties of such planar refracting profiles are discussed. .

Aristov, V.; Firsov, A.; Grigoriev, M.; Ishikawa, T.; Kikuta, S.; Kohmura, Y.; Kuznetsov, S.; Shabelnikov, L.; Yunkin, V.

2000-05-01

433

The maximum hardness principle implies the hard/soft acid/base rule  

NASA Astrophysics Data System (ADS)

A recent paper [P. W. Ayers, J. Chem. Phys122, 141102 (2005)] considered the hard/soft acid/base exchange reaction, showing that the products associated with the hard/soft acid/base rule (in which the hard acid and hard base are bound, as are the soft acid and soft base) have lower energy than the alternative (in which the hard acid and soft base would have been bound and similarly the soft acid and hard base). Here we show that the maximum hardness principle also predicts this result. Unlike the previous derivation, we do not need to make any assumptions about the relative strength of the acids and bases.

Chattaraj, Pratim K.; Ayers, Paul W.

2005-08-01

434

Measurements of the hard-x-ray reflectivity of iridium  

SciTech Connect

In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

Romaine, S.; Bruni, R.; Gorenstein, P.; Zhong, Z

2007-01-10

435

Evaluation of absolute hardness: a new approach.  

PubMed

By taking the energy to be a Morse-like function of the number of electrons, E(N) = ?{1 - e(-?(N-?))}(2) - ?, the electronic chemical potential and global hardness values for a set of atoms and some molecules are calculated from the accurate definitions of these two concepts and using the hybrid B3LYP functional and 6-311++G** basis set. By a comparison between the obtained hardnesses and the corresponding experimental values, it is found that the proposed model yields better values for hardnesses with respect to those that are obtained from the other frequently used methods. It is claimed that the difference between the calculated and experimental hardness values may arise from the approximate equation used for the evaluation of experimental hardnesses. Both of the calculated and experimental molecular hardnesses are used to investigate the change of hardness during the course of some exothermic reactions according to the maximum hardness principle (MHP). It is shown that the obtained hardnesses of reactions from the calculated hardnesses (??(calc)) are more successful in predicting the directions of these reactions than those that are evaluated from the experimental hardnesses (??(exp)). PMID:23360416

Noorizadeh, Siamak; Parsa, Hadi

2013-01-29

436

Local hardness equalization: Exploiting the ambiguity  

NASA Astrophysics Data System (ADS)

In the density-functional theory of chemical reactivity, the local hardness is known to be an ambiguous concept. The mathematical structure associated with this problematic situation is elaborated and three common definitions for the local hardness are critically examined: the frontier local hardness [S. K. Ghosh, Chem. Phys. Lett. 172, 77 (1990)], the total local hardness [S. K. Ghosh and M. Berkowitz, J. Chem. Phys. 83, 2976 (1985)], and the unconstrained local hardness [P. W. Ayers and R. G. Parr, J. Am. Chem. Soc. 122, 2010 (2000)]. The frontier local hardness has particularly nice properties: (a) it has smaller norm than most, if not all, other choices of the local hardness and (b) it is ``unbiased'' in an information-theoretic sense. For the ground electronic state of a molecular system, the frontier local hardness is equal to the global hardness. For an electronic system in its ground state, both the chemical potential and the frontier local hardness are equalized. The frontier local hardness equalization principle provides a computational approach for designing reagents with desirable chemical reactivity profiles.

Ayers, Paul W.; Parr, Robert G.

2008-05-01

437

Hard sphere gas state equation  

NASA Astrophysics Data System (ADS)

The dynamic evolution of a gas of N hard spheres determines the equation of state once the equilibrium is reached, after a short transient. The system is investigated in the thermodynamic limit. The algorithms based on a tricky management of the collisions list allow to simulate up to N=10 spheres, rendering the statistical error sufficiently small in simulations involving 10 collisions. The effect of boundaries is discussed, and, to avoid any dependence, periodic boundary conditions are chosen in a box, whose edge is much larger than the spheres radius. The initial state is the symmetric close packing and, by reducing the hard spheres radius, we follow the evolution of the mean free path as a function of the density y (where y is the ratio between the volume of the spheres and the total volume). We observe the solid-fluid first-order phase transition and follow the fluid branch until the hard spheres gas is very dilute. The phase transition is well resolved due to the improved statistics and to the choice, as order parameter, of the mean free path rather than Z=PV/NkT, which has a singularity at zero mean free path. The equations of state in the fluid and solid branches are compared with the Taylor series for the mean free path, obtained from the virial expansions of Z. The second-order truncations P2(y), appear to provide the best fit to the mean free path. This suggests an approximation to Z as Z=1+B2y/P2(y), where B2 is the second virial coefficient.

Rambaldi, Sandro; Salustri, Giovanna; Benedetti, Carlo

2006-02-01

438

The Hard Problem of Cooperation  

PubMed Central

Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior.

Eriksson, Kimmo; Strimling, Pontus

2012-01-01