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Sample records for masked helium implantation

  1. Neutron-induced helium implantation in GCFR cladding

    SciTech Connect

    Yamada, H.; Poeppel, R. B.; Sevy, R. H.

    1980-10-01

    The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10/sup 10/ He/cm/sup 2/.s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 ..mu..m, more than 99% of helium particles are implanted in the first 2-..mu..m-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding.

  2. Nanostructures from hydrogen and helium implantation of aluminum.

    SciTech Connect

    McWatters, Bruce Ray; Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2010-03-01

    This study investigates a pathway to nanoporous structures created by hydrogen and helium implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on implantations of hydrogen and helium ions at 25 keV in aluminum. The hydrogen and helium systems result in remarkably different nanostructures of aluminum at the surface. Scanning electron microscopy, focused ion beam, and transmission electron microscopy show that both implantations result in porosity that persists approximately 200 nm deep. However, hydrogen implantations tend to produce larger and more irregular voids that preferentially reside at defects. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce much smaller porosity on the order of 10 nm that is regular and creates a bicontinuous structure in the porous region. The primary difference driving the formation of the contrasting structures is likely the relatively high mobility of hydrogen and the ability of hydrogen to form alanes that are capable of desorbing and etching Al (111) faces.

  3. Multi-part mask for implanting workpieces

    SciTech Connect

    Webb, Aaron P.; Carlson, Charles T.

    2016-05-10

    A multi-part mask has a pattern plate, which includes a planar portion that has the desired aperture pattern to be used during workpiece processing. The multi-part mask also has a mounting frame, which is used to hold the pattern plate. Prior to assembly, the pattern plate has an aligning portion, which has one or more holes through which reusable alignment pins are inserted. These alignment pins enter kinematic joints disposed on the mounting frame, which serve to precisely align the pattern plate to the mounting frame. After the pattern plate has been secured to the mounting frame, the aligning portion can be detached from the pattern plate. The alignment pins can be reused at a later time. In some embodiments, the pattern plate can later be removed from the mounting frame, so that the mounting frame may be reused.

  4. High temperature creep of a helium-implanted titanium aluminide alloy

    NASA Astrophysics Data System (ADS)

    Magnusson, Per; Chen, Jiachao; Hoffelner, Wolfgang

    2011-09-01

    The creep properties of an intermetallic alloy Ti-46Al-2W-0.5Si (at%) including strain rate and time to fracture were investigated in vacuum using helium-implanted and non-implanted samples, at a temperature of 1073 K and a stress of 200 MPa. The implantation was performed using 24 MeV He-ions, homogeneously implanting the samples with up to 1333 appm (atomic parts per million) helium. The size and location of helium bubbles were determined with transmission electron microscopy (TEM). Samples implanted with helium content above 10 appm exhibited strong helium embrittlement, reducing both the time to fracture and the elongation at fracture. The corresponding critical helium bubble size r c was determined to 10 nm.

  5. Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

    SciTech Connect

    Armstrong, D. E. J.; Edmondson, P. D.; Roberts, S. G.

    2013-06-24

    To simulate neutron and helium damage in a fusion reactor first wall sequential self-ion implantation up to 13 dpa followed by helium-ion implantation up to 3000 appm was performed to produce damaged layers of {approx}2 {mu}m depth in pure tungsten. The hardness of these layers was measured using nanoindentation and was studied using transmission electron microscopy. Substantial hardness increases were seen in helium implanted regions, with smaller hardness increases in regions which had already been self-ion implanted, thus, containing pre-existing dislocation loops. This suggests that, for the same helium content, helium trapped in distributed vacancies gives stronger hardening than helium trapped in vacancies condensed into dislocation loops.

  6. Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

    NASA Astrophysics Data System (ADS)

    Armstrong, D. E. J.; Edmondson, P. D.; Roberts, S. G.

    2013-06-01

    To simulate neutron and helium damage in a fusion reactor first wall sequential self-ion implantation up to 13 dpa followed by helium-ion implantation up to 3000 appm was performed to produce damaged layers of ˜2 μm depth in pure tungsten. The hardness of these layers was measured using nanoindentation and was studied using transmission electron microscopy. Substantial hardness increases were seen in helium implanted regions, with smaller hardness increases in regions which had already been self-ion implanted, thus, containing pre-existing dislocation loops. This suggests that, for the same helium content, helium trapped in distributed vacancies gives stronger hardening than helium trapped in vacancies condensed into dislocation loops.

  7. The role of helium implantation induced vacancy defect on hardening of tungsten

    SciTech Connect

    Ou, Xin; Anwand, Wolfgang Kögler, Reinhard; Zhou, Hong-Bo; Richter, Asta

    2014-03-28

    Vacancy-type defects created by helium implantation in tungsten and their impact on the nano-hardness characteristics were investigated by correlating the results from the positron annihilation spectroscopy and the nano-indentation technique. Helium implantation was performed at room temperature (RT) and at an elevated temperate of 600 °C. Also, the effect of post-annealing of the RT implanted sample was studied. The S parameter characterizing the open volume in the material was found to increase after helium irradiation and is significantly enhanced for the samples thermally treated at 600 °C either by irradiation at high temperature or by post-annealing. Two types of helium-vacancy defects were detected after helium irradiation; small defects with high helium-to-vacancy ratio (low S parameter) for RT irradiation and large defects with low helium-to-vacancy ratio (high S parameter) for thermally treated tungsten. The hardness of the heat treated tungsten coincides with the S parameter, and hence is controlled by the large helium-vacancy defects. The hardness of tungsten irradiated at RT without thermal treatment is dominated by manufacturing related defects such as dislocation loops and impurity clusters and additionally by trapped He atoms from irradiation effects, which enhance hardness. He-stabilized dislocation loops mainly cause the very high hardness values in RT irradiated samples without post-annealing.

  8. Migration and release of helium-3 implanted in single-crystal nickel

    SciTech Connect

    Maki, J.T.

    1987-01-01

    Several nickel single-crystal samples were implanted with 150-keV helium-3 ions to doses between 9.2 x 10/sup 18/ and 2.0 x 10/sup 20/ m/sup -2/. After implantation, the samples were isochronally annealed at various temperatures between 300 and 1300/sup 0/C. Following each annealing step, helium distributions were measured by a nuclear-reaction technique called neutron depth profiling. The technique determines a helium profile from the measured energy distribution of emitted protons produced by the /sup 3/He(n,p)/sup 3/H reaction when a sample is placed in a thermal-neutron beam. The measured profiles were then deconvoluted by an iterative chi-square minimization method. The helium depth profiles can be compared to illustrate helium migration or loss as a function of annealing temperature. Two new results were determined by this experiment and may be summarized as follows. The first results was the demonstration of a helium-concentration-dependent release pattern where one sample with an initial helium dose of about 6 x 10/sup 19/ m/sup -2/ was the most stable and displayed the least amount of helium release up to annealing temperatures as high as 1300/sup 0/C. The second result was the observation that profile peaking (a narrowing of the helium distribution with an increase in peak concentration) occurred for samples with initial doses within a certain range when annealed at 1000/sup 0/C.ng-tool

  9. The formation of microvoids in MgO by helium ion implantation and thermal annealing

    NASA Astrophysics Data System (ADS)

    van Veen, A.; Schut, H.; Fedorov, A. V.; Labohm, F.; Neeft, E. A. C.; Konings, R. J. M.

    1999-01-01

    The formation of microvoids in metal oxides by helium implantation and thermal annealing is observed under similar conditions as has been shown earlier for silicon. Cleaved MgO (1 0 0) single crystals were implanted with 30 keV 3He ions with doses varying from 10 15 to 10 16 cm -2 and subsequently thermally annealed from RT to 1500 K. Monitoring of the defect depth profile and the retained amount of helium was performed by positron beam analysis and neutron depth profiling, respectively. For a dose larger than 2 × 10 15 cm -2 annealing of the defects was observed in two stages: at 1000 K helium filled monovacancies dissociated, and other defects still retaining the helium were formed, and at 1300 K all helium left the sample while an increase of positron-valence-electron annihilations was observed, indicating an increase of the volume available in the defects. The voids of nm size were located at shallower depth than the implanted helium. At lower dose no voids were left after high temperature annealing. Voids can also be created, and even more effectively, by hydrogen or deuterium implantation. The voids are stable to temperatures of 1500 K. The use of the nanovoids as a precursor state for nanoprecipitates of metals or other species is discussed.

  10. Growth mechanism of cavities in MeV helium implanted silicon

    NASA Astrophysics Data System (ADS)

    Grisolia, J.; Claverie, A.; Assayag, G. Ben; Godey, S.; Ntsoenzok, E.; Labhom, F.; Van Veen, A.

    2002-06-01

    A study of silicon implanted with 1.55 MeV helium 3 and thermally annealed to generate a subsurface cavity region was performed using neutron depth profiling and transmission electron microscopy (TEM). Results show that about 30% of the initial implanted helium is still present in cavities even after a 900 °C-1 h anneal. In addition, TEM measurement of cavity size on anneal temperature yields an activation energy of 1.65 eV for the growth of cavities. This value is very close to the activation energy (1.7 eV) reported for helium diffusion in silicon. Cavity growth hence results essentially from exchange of helium atoms between cavities.

  11. Helium-Implantation-Induced Damage in NHS Steel Investigated by Slow-Positron Annihilation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Yuan-Fei; Shen, Tie-Long; Gao, Xing; Gao, Ning; Yao, Cun-Feng; Sun, Jian-Rong; Wei, Kong-Fang; Li, Bing-Sheng; Zhang, Peng; Cao, Xing-Zhong; Zhu, Ya-Bin; Pang, Li-Long; Cui, Ming-Huan; Chang, Hai-Long; Wang, Ji; Zhu, Hui-Ping; Wang, Dong; Song, Peng; Sheng, Yan-Bin; Zhang, Hong-Peng; Hu, Bi-Tao; Wang, Zhi-Guang

    2014-03-01

    Evolutions of defects and helium contained defects produced by atomic displacement and helium deposition with helium implantation at different temperatures in novel high silicon (NHS) steel are investigated by a slow positron beam. Differences of the defect information among samples implanted by helium to a fluence of 1 × 1017 ions/cm2 at room temperature, 300°C, 450°C and 750°C are discussed. It is found that the mobility of vacancies and vacancy clusters, a recombination of vacancy-type defects and the formation of the He-V complex lead to the occurrence of these differences. At high temperature irradiations, a change of the diffusion mechanism of He atoms/He bubbles might be one of the reasons for the change of the S-parameter.

  12. Impact of helium implantation and ion-induced damage on reflectivity of molybdenum mirrors

    NASA Astrophysics Data System (ADS)

    Garcia-Carrasco, A.; Petersson, P.; Hallén, A.; Grzonka, J.; Gilbert, M. R.; Fortuna-Zalesna, E.; Rubel, M.

    2016-09-01

    Molybdenum mirrors were irradiated with Mo and He ions to simulate the effect of neutron irradiation on diagnostic first mirrors in next-generation fusion devices. Up to 30 dpa were produced under molybdenum irradiation leading to a slight decrease of reflectivity in the near infrared range. After 3 × 1017 cm-2 of helium irradiation, reflectivity decreased by up to 20%. Combined irradiation by helium and molybdenum led to similar effects on reflectivity as irradiation with helium alone. Ion beam analysis showed that only 7% of the implanted helium was retained in the first 40 nm layer of the mirror. The structure of the near-surface layer after irradiation was studied with scanning transmission electron microscopy and the extent and size distribution of helium bubbles was documented. The consequences of ion-induced damage on the performance of diagnostic components are discussed.

  13. Helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure: A superior option.

    PubMed

    Xu, Qi-Hua; Zhao, Chen; Zhu, Jian-Gang; Chen, Mei-Juan; Liu, Qing-Huai

    2015-09-01

    The aim of the present study was to evaluate the efficacy of helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure and compare the results with those of a combined drugs and surgery regimen. A total of 70 patients with hydroxyapatite orbital implant exposure in 70 eyes were randomly divided into two groups: Helium-neon laser therapy (group A) and drugs plus surgery (group B). Each group contained 35 patients. The healing rates and times of the conjunctival wound were recorded and compared following helium-neon laser treatment or the drugs plus surgery regimen. Changes in the hydroxyapatite orbital implant prior to and following helium-neon laser irradiation were analyzed. A similar animal study was conducted using 24 New Zealand white rabbits, which received orbital implants and were then received drug treatment or helium-neon therapy. In the human experiment, the rates for conjunctival wound healing were 97.14% in group A and 74.29% in group B, with a significant difference between the groups (χ(2)=5.71, P<0.05). Patients with mild exposure were healed after 7.22±2.11 days of helium-neon laser therapy and 14.33±3.20 days of drugs plus surgery. A statistically significant difference was found between the groups (t=8.97, P<0.05). Patients with moderate to severe exposure were healed after 18.19±2.12 days of helium-neon laser therapy and 31.25±4.21 days of drugs plus surgery. The difference between the groups was statistically significant (t=7.91, P<0.05). Enhanced magnetic resonance imaging showed that the helium-neon laser therapy significantly promoted vascularization of the hydroxyapatite orbital implant. These results, combined with pathological findings in animals, which showed that a helium-neon laser promoted vascularization and had anti-inflammatory effects, suggest that helium-neon laser irradiation is an effective method for treating hydroxyapatite orbital implant exposure, thereby avoiding secondary surgery.

  14. Rectangular nanovoids in helium-implanted and thermally annealed MgO(100)

    NASA Astrophysics Data System (ADS)

    Kooi, B. J.; van Veen, A.; De Hosson, J. Th. M.; Schut, H.; Fedorov, A. V.; Labohm, F.

    2000-02-01

    Cleaved MgO(100) single crystals were implanted with 30 keV 3He ions with doses varying from 1×1019 to 1×1020m-2 and subsequently thermally annealed from 100 to 1100 °C. Transmission electron microscopy observations revealed the existence of sharply rectangular nanosize voids at a depth slightly shallower than the helium-implantation range. Monitoring of the defect depth profile and the retained amount of helium was performed by positron-beam analysis and neutron depth profiling, respectively.

  15. Onset of plasticity of helium-implanted ferritic/martensitic steels during nanoindentation

    NASA Astrophysics Data System (ADS)

    Chen, Siwei; Wang, Yongming; Hashimoto, Naoyuki; Ohnuki, Somei

    2014-07-01

    The onset of plasticity during nanoindentation is a new method to investigate the irradiation damage of structural materials in fission and fusion reactors. In this paper, nanoindentation experiment was carried out to helium implanted F82H-IEA and nano-sized oxide dispersion strengthened F82H-ODS steels for studying the elastic-plastic transition at a constant loading rate. The onset of plasticity shifted after helium implantation. By a statistical thermal activation model, activation volume was extracted to discuss the strength of barrier for dislocation motion. The results reveal an increase in the pinning force and number density of effective obstacles for dislocation motion in He-implanted F82H-IEA, and a decrease in the local pinning force without changing the density of effective obstacles in He-implanted F82H-ODS.

  16. Microstructure of a 14Cr-ODS ferritic steel before and after helium ion implantation

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Lu, Zheng; Xie, Rui; Liu, Chunming; Wang, Lumin

    2014-12-01

    A 14Cr-ODS ferritic steel with the nominal compositions of Fe-14Cr-2 W-0.3Ti-0.3Y2O3 (wt.%) was produced by mechanical alloying (MA) and hot isostatic pressing (HIP). Helium ion was implanted into the 14Cr-ODS steel along with Eurofer 97 steel as reference at 400 °C to a fluence of 1 × 1017 He+/cm2. High resolution transmission electron microscopy (HRTEM), high angle annual dark field (HAADF) scanning TEM (STEM) and atom probe tomography (APT) were used to characterize the microstructure of 14Cr-ODS and Eurofer 97 steels before and after helium implantation. High-density Y-Ti-O-rich nanoclusters and Y2Ti2O7 precipitates as well as large Cr-Ti rich oxides were observed in the 14Cr-ODS steel. The average size of Y-Ti-O nanoclusters and Y2Ti2O7 precipitates is 9 nm. After helium implantation, the helium bubbles formed in the 14Cr-ODS steel exhibit the smaller size and the lower volume fraction than that in Eurofer 97 steel, indicating high-density nano-scale precipitates can effectively suppress the coarsening of helium bubbles.

  17. Helium behaviour in UO2 through low fluence ion implantation studies

    NASA Astrophysics Data System (ADS)

    Garcia, P.; Gilabert, E.; Martin, G.; Carlot, G.; Sabathier, C.; Sauvage, T.; Desgardin, P.; Barthe, M.-F.

    2014-05-01

    In this work we focus on experiments involving implantation of 500 keV 3He ions in sintered polycrystalline material. Samples are implanted at low fluences (˜2 ×1013 ions/cm2) and subsequently isothermally annealed in a highly sensitive thermal desorption spectrometry (TDS) device PIAGARA (Plateforme Interdisciplinaire pour l'Analyse des GAz Rares en Aquitaine). The helium fluencies studied are two to three orders of magnitude lower than previous Nuclear Reaction Analysis (NRA) experiments carried out on identical samples implanted at identical energies. The fractional release of helium obtained in the TDS experiments is interpreted using a three-dimensional axisymmetric diffusion model which enables results to be quantitatively compared to previous NRA data. The analysis shows that helium behaviour is qualitatively independent of ion fluency over three orders of magnitude: helium diffusion appears to be strongly inhibited below 1273 K within the centre of the grains presumably as a result of helium bubble precipitation. The scenario involving diffusion at grain boundaries and in regions adjacent to them observed at higher fluencies is quantitatively confirmed at much lower doses. The main difference lies in the average width of the region in which uninhibited diffusion occurs.

  18. Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

    NASA Astrophysics Data System (ADS)

    Pentecoste, Lucile; Thomann, Anne-Lise; Melhem, Amer; Caillard, Amael; Cuynet, Stéphane; Lecas, Thomas; Brault, Pascal; Desgardin, Pierre; Barthe, Marie-France

    2016-09-01

    The aim of this work is to investigate the first stages of defect formation in tungsten (W) due to the accumulation of helium (He) atoms inside the crystal lattice. To reach the required implantation conditions, i.e. low He ion fluxes (1011-1014 ions.cm2.s-1) and kinetic energies below the W atom displacement threshold (about 500 eV for He+), an ICP source has been designed and connected to a diffusion chamber. Implantation conditions have been characterized by means of complementary diagnostics modified for measurements in this very low density helium plasma. It was shown that lowest ion fluxes could only be reached for the discharge working in capacitive mode either in α or γ regime. Special attention was paid to control the energy gained by the ions by acceleration through the sheath at the direct current biased substrate. At very low helium pressure, in α regime, a broad ion energy distribution function was evidenced, whereas a peak centered on the potential difference between the plasma and the biased substrate was found at higher pressures in the γ mode. Polycrystalline tungsten samples were exposed to the helium plasma in both regimes of the discharge and characterized by positron annihilation spectroscopy in order to detect the formed vacancy defects. It was found that W vacancies are able to be formed just by helium accumulation and that the same final implanted state is reached, whatever the operating mode of the capacitive discharge.

  19. Radiation defects induced by helium implantation in gold-based alloys investigated by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Thome, T.; Grynszpan, R. I.

    2006-06-01

    The formation of gas bubbles in metallic materials may result in drastic degradation of in-service properties. In order to investigate this effect in high density and medium-low melting temperature ( T-M ) alloys, positron annihilation spectroscopy measurements were performed on helium-implanted gold-silver solid solutions after isochronal annealing treatments. Three recovery stages are observed, attributed to the migration and elimination of defects not stabilized by helium atoms, helium bubble nucleation and bubble growth. Similarities with other metals are found for the recovery stages involving bubble nucleation and growth processes. Lifetime measurements indicate that He implantation leads to the formation of small and over-pressurized bubbles that generate internal stresses in the material. A comprehensive picture is drawn for possible mechanisms of helium bubble evolution. Two values of activation energy (0.26 and 0.53 eV) are determined below and above 0.7 T-M , respectively, from the variation of the helium bubble radius during the bubble growth stage. The migration and coalescence mechanism, which accounts for these very low activation energies, controls the helium bubble growth.

  20. Cochlear implant speech intelligibility outcomes with structured and unstructured binary mask errors.

    PubMed

    Kressner, Abigail A; Westermann, Adam; Buchholz, Jörg M; Rozell, Christopher J

    2016-02-01

    It has been shown that intelligibility can be improved for cochlear implant (CI) recipients with the ideal binary mask (IBM). In realistic scenarios where prior information is unavailable, however, the IBM must be estimated, and these estimations will inevitably contain errors. Although the effects of both unstructured and structured binary mask errors have been investigated with normal-hearing (NH) listeners, they have not been investigated with CI recipients. This study assesses these effects with CI recipients using masks that have been generated systematically with a statistical model. The results demonstrate that clustering of mask errors substantially decreases the tolerance of errors, that incorrectly removing target-dominated regions can be as detrimental to intelligibility as incorrectly adding interferer-dominated regions, and that the individual tolerances of the different types of errors can change when both are present. These trends follow those of NH listeners. However, analysis with a mixed effects model suggests that CI recipients tend to be less tolerant than NH listeners to mask errors in most conditions, at least with respect to the testing methods in each of the studies. This study clearly demonstrates that structure influences the tolerance of errors and therefore should be considered when analyzing binary-masking algorithms.

  1. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    SciTech Connect

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R.

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.

  2. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    DOE PAGES

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; ...

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with nomore » sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.« less

  3. Annealing behaviour of defects in helium implanted MgO

    NASA Astrophysics Data System (ADS)

    Schut, H.; Van Veen, A.; Labohm, F.; Fedorov, A. V.; Neeft, E. A. C.; Konings, R. J. M.

    1999-01-01

    Virgin MgO (1 1 0) single crystals have been implanted with 30 keV 3He + ions to a dose of 5 × 10 15 cm -2. After implantation the samples have been annealed under air for 30 min in a tube oven. The annealing behaviour of the defects and 3He has been monitored by three experimental techniques: positron beam Doppler broadening, neutron depth profiling (NDP) and optical absorption in the UV to near-IR region. The observations in MgO lead to the conclusion that below 1000 oC the vacancy like defects are stabilised by the implanted He atoms. Above this temperature He may dissociate from these small defects, allowing the formation of larger vacancy clusters.

  4. Effect of helium implantation on mechanical properties and microstructure evolution of reduced-activation 9Cr-2W martensitic steel

    NASA Astrophysics Data System (ADS)

    Kasada, R.; Morimura, T.; Hasegawa, A.; Kimura, A.

    2001-10-01

    A reduced-activation martensitic steel was implanted with helium up to 580 at. ppm by using 36 MeV α-beam between 353 and 423 K along with displacement damage up to 0.226 dpa. The implantation-induced increase in ductile-brittle transition temperature (DBTT) was estimated to be 98 K for the standard charpy V-notched (CVN) specimen implanted with 580 at. ppm He, through the conversion of small punch (SP) test results by an empirical relationship. It is clarified from comparison with neutron irradiation data that the increase in DBTT as well as implantation-induced hardening is interpreted simply in terms of displacement damage, suggesting that there is no significant effect of helium on both the irradiation hardening and the fracture toughness of the steel. No fracture mode change by the helium implantation was observed in the SP tests, showing a complete cleavage fracture mode in the lower shelf energy region.

  5. Forward Masking in Cochlear Implant Users: Electrophysiological and Psychophysical Data Using Pulse Train Maskers.

    PubMed

    Adel, Youssef; Hilkhuysen, Gaston; Noreña, Arnaud; Cazals, Yves; Roman, Stéphane; Macherey, Olivier

    2017-02-21

    Electrical stimulation of auditory nerve fibers using cochlear implants (CI) shows psychophysical forward masking (pFM) up to several hundreds of milliseconds. By contrast, recovery of electrically evoked compound action potentials (eCAPs) from forward masking (eFM) was shown to be more rapid, with time constants no greater than a few milliseconds. These discrepancies suggested two main contributors to pFM: a rapid-recovery process due to refractory properties of the auditory nerve and a slow-recovery process arising from more central structures. In the present study, we investigate whether the use of different maskers between eCAP and psychophysical measures, specifically single-pulse versus pulse train maskers, may have been a source of confound.In experiment 1, we measured eFM using the following: a single-pulse masker, a 300-ms low-rate pulse train masker (LTM, 250 pps), and a 300-ms high-rate pulse train masker (HTM, 5000 pps). The maskers were presented either at same physical current (Φ) or at same perceptual (Ψ) level corresponding to comfortable loudness. Responses to a single-pulse probe were measured for masker-probe intervals ranging from 1 to 512 ms. Recovery from masking was much slower for pulse trains than for the single-pulse masker. When presented at Φ level, HTM produced more and longer-lasting masking than LTM. However, results were inconsistent when LTM and HTM were compared at Ψ level. In experiment 2, masked detection thresholds of single-pulse probes were measured using the same pulse train masker conditions. In line with our eFM findings, masked thresholds for HTM were higher than those for LTM at Φ level. However, the opposite result was found when the pulse trains were presented at Ψ level.Our results confirm the presence of slow-recovery phenomena at the level of the auditory nerve in CI users, as previously shown in animal studies. Inconsistencies between eFM and pFM results, despite using the same masking conditions, further

  6. Irradiation hardening of ODS ferritic steels under helium implantation and heavy-ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Hengqing; Zhang, Chonghong; Yang, Yitao; Meng, Yancheng; Jang, Jinsung; Kimura, Akihiko

    2014-12-01

    Irradiation hardening of ODS ferritic steels after multi-energy He-ion implantation, or after irradiation with energetic heavy ions including Xe and Bi-ions was investigated with nano-indentation technique. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-3.5Al-0.1Zr were used. Data of nano-hardness were analyzed with an approach based on Nix-Gao model. The depth profiles of nano-hardness can be understood by the indentation size effect (ISE) in specimens of MA956 implanted with multi-energy He-ions or irradiated with 328 MeV Xe ions, which produced a plateau damage profile in the near-surface region. However, the damage gradient overlaps the ISE in the specimens irradiated with 9.45 Bi ions. The dose dependence of the nano-hardness shows a rapid increase at low doses and a slowdown at higher doses. An 1/2-power law dependence on dpa level is obtained. The discrepancy in nano-hardness between the helium implantation and Xe-ion irradiation can be understood by using the average damage level instead of the peak dpa level. Helium-implantation to a high dose (7400 appm/0.5 dpa) causes an additional hardening, which is possibly attributed to the impediment of motion dislocations by helium bubbles formed in high concentration in specimens.

  7. Helium implanted Eurofer97 characterized by positron beam Doppler broadening and Thermal Desorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Carvalho, I.; Schut, H.; Fedorov, A.; Luzginova, N.; Desgardin, P.; Sietsma, J.

    2013-11-01

    Reduced Activation Ferritic/Martensitic steels are being extensively studied because of their foreseen application in fusion and Generation IV fission reactors. To produce irradiation induced defects, Eurofer97 samples were implanted with helium at energies of 500 keV and 2 MeV and doses of 1 × 1015-1016 He/cm2, creating atomic displacements in the range 0.07-0.08 dpa. The implantation induced defects were characterized by positron beam Doppler Broadening (DB) and Thermal Desorption Spectroscopy (TDS). Results show that up to ˜600 K peaks that can be attributed to He desorption from overpressured HenVm (n > m) clusters and vacancy assisted mechanism in the case of helium in the substitutional position. The temperature range 600-1200 K is related to the formation of larger clusters HenVm (n < m). The dissociation of the HeV and the phase transition attributed to a sharp peak in the TDS spectra at 1200 K. Above this temperature, the release of helium from bubbles is observed.

  8. Simultaneous suppression of noise and reverberation in cochlear implants using a ratio masking strategy.

    PubMed

    Hazrati, Oldooz; Sadjadi, Seyed Omid; Loizou, Philipos C; Hansen, John H L

    2013-11-01

    Cochlear implant (CI) recipients' ability to identify words is reduced in noisy or reverberant environments. The speech identification task for CI users becomes even more challenging in conditions where both reverberation and noise co-exist as they mask the spectro-temporal cues of speech in a rather complementary fashion. Ideal channel selection (ICS) was found to result in significantly more intelligible speech when applied to the noisy, reverberant, as well as noisy reverberant speech. In this study, a blind single-channel ratio masking strategy is presented to simultaneously suppress the negative effects of reverberation and noise on speech identification performance for CI users. In this strategy, noise power spectrum is estimated from the non-speech segments of the utterance while reverberation spectral variance is computed as a delayed and scaled version of the reverberant speech spectrum. Based on the estimated noise and reverberation power spectra, a weight between 0 and 1 is assigned to each time-frequency unit to form the final mask. Listening experiments conducted with CI users in two reverberant conditions (T60 = 0.6 and 0.8 s) at a signal-to-noise ratio of 15 dB indicate substantial improvements in speech intelligibility in both reverberant-alone and noisy reverberant conditions considered.

  9. Helium effects on microstructural evolution in tempered martensitic steels: In situ helium implanter studies in HFIR

    SciTech Connect

    Yamamoto, Takuya; Odette, George R.; Miao, Pifeng; Edwards, Danny J.; Kurtz, Richard J.

    2009-04-30

    Microstructural evolutions in tempered martensitic steels (TMS) under neutron-irradiation, at fusion relevant He/dpa ratios and dpa rates, were characterized using a novel in situ He-implanter technique. F82H-mod3 was irradiated at 500 C in HFIR to a nominal 9 dpa and 190 or 380 appm He in both in the as-tempered (AT) and 20% cold-worked (CW) conditions. In all cases, a high number density of 1-2 nm He-bubbles were observed, along with fewer but larger 10 nm void-like faceted cavities. The He-bubbles form preferentially on dislocations and various interfaces. A slightly larger number of smaller He bubbles were observed in the CW condition. The lower He/dpa ratio produced slightly smaller and fewer He-bubbles. Comparisons of these observations to the results in nano-structured ferritic alloy (NFA) MA957 provide additional evidence that TMS may be susceptible to He-embrittlement as well as void swelling at fusion relevant He concentrations, while NFA are much more resistant to these degradation phenomena.

  10. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing.

    PubMed

    Williges, Ben; Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-12-30

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types.

  11. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing

    PubMed Central

    Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-01-01

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types. PMID:26721918

  12. Patterned ion beam implantation of Co ions into a SiO2 thin film via ordered nanoporous alumina masks.

    PubMed

    Guan, Wei; Ghatak, Jay; Peng, Yong; Peng, Nianhua; Jeynes, Chris; Inkson, Beverley; Möbus, Günter

    2012-02-03

    Spatially patterned ion beam implantation of 190 keV Co(+) ions into a SiO(2) thin film on a Si substrate has been achieved by using nanoporous anodic aluminum oxide with a pore diameter of 125 nm as a mask. The successful synthesis of periodic embedded Co regions using pattern transfer is demonstrated for the first time using cross-sectional (scanning) transmission electron microscopy (TEM) in combination with analytical TEM. Implanted Co regions are found at the correct relative lateral periodicity given by the mask and at a depth of about 120 nm.

  13. Formation of c-BN nanoparticles by helium, lithium and boron ion implantation

    NASA Astrophysics Data System (ADS)

    Aradi, Emily; Erasmus, Rudolph M.; Derry, Trevor E.

    2012-02-01

    Ion induced phase transformation from the soft graphitic hexagonal boron nitride ( h-BN) to ultrahard cubic boron nitride ( c-BN) nanoparticles is presented in the work herein. Ion implantation was used as a technique to introduce boron lithium and helium ions, at the energy of 150 keV and fluences ranging from 1 × 10 14 to 1 × 10 16 ions/cm 2, into hot pressed, polycrystalline h-BN. Analyses using Raman Spectroscopy showed that He +, Li + and B + led to a h-BN to c-BN phase transition, evident from the longitudinal optical (LO) Raman phonon features occurring in the implanted samples' spectra. The nature of these phonon peaks and their downshifting is explained using the spatial phonon correlation model.

  14. Optoelectronic characteristics and applications of helium ion-implanted silicon devices

    NASA Astrophysics Data System (ADS)

    Liu, Yang

    Silicon-on-insulator (SOI) wafers are an attractive platform for the fabrication of planar lightwave circuits (PLCs) because they offer the potential for low-cost fabrication using mature complementary metal--organic--semiconductor (CMOS) compatible processes developed in the microelectronics industry. At the wavelengths of interest for telecommunications, SOI waveguides can have low optical losses (0.1dB/cm). Besides, the strong optical confinement offered by the high index contrast between silicon (Si) (n=3.45) and silicon dioxide (SiO2) (n=1.45) makes it possible to scale photonic devices to sub-micron level. In addition, the high optical intensity arising from the strong optical confinement inside the waveguide makes it possible to observe nonlinear optical effects, such as Raman and Kerr effects, in chip-scale devices. Helium ion implantation can not only reduce the free-carrier loss, but can also enhance the detection responsivity of below-bandgap wavelengths (1440 1590 nm). We propose and demonstrate an in-line channel power monitor (ICPM) based on helium ion implanted silicon waveguides. The implanted waveguide can detect light at 1440 1590 nm which are normally not detectable by silicon. We study the enhanced photoresponse of helium ion implanted waveguide samples which were annealed at different temperatures and for different durations. We then make use of the ICPM to perform a system application, called optical-burst-and-transient-equalizer (OBTE). The OBTE may provide a compact and low-cost solution to compensate gain-transient, gain-spectrum-tilt and to equalize the upstream packet amplitude in erbium doped fiber amplifier (EDFA) amplified hybrid dense-wavelength-division-multiplexed (DWDM) and time-division-multiplexed (TDM) passive-optical-networks (PONs). The OBTE may be monolithically integrated on SOI platform and is potentially low cost and compact. The OBTE can compensate complicated gain slope shape, which may be generated in cascaded EDFAs or

  15. Directed cell attachment by tropoelastin on masked plasma immersion ion implantation treated PTFE.

    PubMed

    Bax, Daniel V; McKenzie, David R; Bilek, Marcela M M; Weiss, Anthony S

    2011-10-01

    The ability to generate cell patterns on polymer surfaces is critical for the detailed study of cellular biology, the fabrication of cell-based biosensors, cell separation techniques and for tissue engineering. In this study contact tape masking and steel shadow masks were used to exclude plasma immersion ion implantation (PIII) treatment from defined areas of polytetrafluoroethylene (PTFE) surfaces. This process enabled patterned covalent binding of the cell adhesive protein, tropoelastin, without employing chemical linking molecules. Tropoelastin coating rendered the untreated regions cell adhesive and the PIII-treated area non-adhesive, allowing very fine patterning of cell adhesion to PTFE surfaces. A blocking step, such as with BSA or PEG, was not required to prevent cell binding to the underlying PIII-treated regions as tropoelastin coating alone performed this blocking function. Although tropoelastin coated the entire PTFE surface, the cell binding C-terminus of tropoelastin was markedly less solvent exposed on the PIII-treated, hydrophilic regions. The differential exposure of the C-terminus correlated with the patterned distribution of tropoelastin-mediated cell adhesion. This new methodology specifically enables directed cell behavior on a polymer surface using a simple one-step treatment process, by modulating the adhesive activity of a single extracellular matrix protein.

  16. Estimated solar wind-implanted helium-3 distribution on the Moon

    USGS Publications Warehouse

    Johnson, J. R.; Swindle, T.D.; Lucey, P.G.

    1999-01-01

    Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions.

  17. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, S.M. Jr.; Bishop, D.M.; Follstaedt, D.M.

    1998-11-24

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer. 4 figs.

  18. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, Jr., Samuel M.; Bishop, Dawn M.; Follstaedt, David M.

    1998-01-01

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer.

  19. Temperature dependence of helium-implantation-induced lattice swelling in polycrystalline tungsten: X-ray micro-diffraction and Eigenstrain modelling

    SciTech Connect

    de Broglie, I.; Beck, C. E.; Liu, W.; Hofmann, Felix

    2015-05-30

    Using synchrotron X-ray micro-diffraction and Eigenstrain analysis the distribution of lattice swelling near grain boundaries in helium-implanted polycrystalline tungsten is quantified. Samples heat-treated at up to 1473 K after implantation show less uniform lattice swelling that varies significantly from grain to grain compared to as-implanted samples. An increase in lattice swelling is found in the vicinity of some grain boundaries, even at depths beyond the implanted layer. As a result, these findings are discussed in terms of the evolution of helium-ion-implantation-induced defects.

  20. Surface cracking on Σ3, Σ9 CSL and random grain boundaries in helium implanted 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Sakaguchi, N.; Ohguchi, Y.; Shibayama, T.; Watanabe, S.; Kinoshita, H.

    2013-01-01

    The relationship between surface cracking at grain boundaries and the grain boundary nature in helium implanted 316L austenitic stainless steel was investigated by in situ annealing in a high-voltage electron microscope, and by SEM and TEM observations. The nucleation and growth of helium bubbles at a random grain boundary was observed during annealing up to 973 K. After annealing, surface cracking was observed at the random grain boundaries and some coincidence site lattice (CSL) boundaries because of the formation and rupture of the helium bubbles at these grain boundaries. At the faceted CSL boundaries, surface cracking occurred only on one boundary facet plane. This indicates that the twin boundary and pure tilt Σ9 CSL boundary show the highest resistance to cracking because of their low boundary energies.

  1. Effect of simultaneous helium implantation on the microstructure evolution of Inconel X-750 superalloy during dual-beam irradiation

    NASA Astrophysics Data System (ADS)

    Changizian, P.; Zhang, H. K.; Yao, Z.

    2015-12-01

    This study focuses on investigation into the effect of helium implantation on microstructure evolution in Inconel X-750 superalloy during dual-beam (Ni+/He+) irradiation. The 1 MeV Ni+ ions with the damage rate of 10-3 dpa/s as well as 15 keV He+ ions using rate of 200 appm/dpa were simultaneously employed to irradiate specimens at 400 °C to different doses. Microstructure characterization has been conducted using high-resolution analytical transmission electron microscopy (TEM). The TEM results show that simultaneous helium injection has significant influence on irradiation-induced microstructural changes. The disordering of γ‧ (Ni3 (Al, Ti)) precipitates shows noticeable delay in dose level compared to mono heavy ion irradiation, which is attributed to the effect of helium on promoting the dynamic reordering process. In contrast to previous studies on single-beam ion irradiation, in which no cavities were reported even at high doses, very small (2-5 nm) cavities were detected after irradiation to 5 dpa, which proved that helium plays crucial role in cavity formation. TEM characterization also indicates that the helium implantation affects the development of dislocation loops during irradiation. Large 1/3 <1 1 1> Frank loops in the size of 10-20 nm developed during irradiation at 400 °C, whereas similar big loops detected at higher irradiation temperature (500 °C) during sole ion irradiation. This implies that the effect of helium on trapping the vacancies can help to develop the interstitial Frank loops at lower irradiation temperatures.

  2. Surface studies and implanted helium measurements following NOVA high-yield DT experiments

    SciTech Connect

    Stoyer, M.A.; Hudson, G.B.

    1997-02-18

    This paper presents the results of three March 6, 1996 direct-drive high-yield DT NOVA experiments and provides `proof-of-principal` results for the quantitative measurement of energetic He ions. Semiconductor quality Si wafers and an amorphous carbon wafer were exposed to NOVA high-yield implosions. Surface damage was sub-micron in general, although the surface ablation was slightly greater for the carbon wafer than for the Si wafers. Melting of a thin ({approx} 0.1{mu}) layer of Si was evident from microscopic investigation. Electron microscopy indicated melted blobs of many different metals (e.g. Al, Au, Ta, Fe alloys, Cu and even Cd) on the surfaces. The yield measured by determining the numbers of atoms of implanted {sup 4}He and {sup 3}He indicate the number of DT fusions to be 9.1({plus_minus}2.3) X 10{sup 12} and DD fusions to be 4.8({plus_minus}1.0) x 10{sup 10}, respectively. The helium DT fusion yield is slightly lower than that of the Cu activation measurement, which was 1.3({plus_minus}0.l) x 10{sup 13} DT fusions.

  3. Aluminum oxide mask fabrication by focused ion beam implantation combined with wet etching.

    PubMed

    Liu, Zhengjun; Iltanen, Kari; Chekurov, Nikolai; Grigoras, Kestutis; Tittonen, Ilkka

    2013-05-03

    A novel aluminum oxide (Al2O3) hard mask fabrication process with nanoscale resolution is introduced. The Al2O3 mask can be used for various purposes, but in this work it was utilized for silicon patterning using cryogenic deep reactive ion etching (DRIE). The patterning of Al2O3 is a two-step process utilizing focused ion beam (FIB) irradiation combined with wet chemical etching. Gallium (Ga(+)) FIB maskless patterning confers wet etch selectivity between the irradiated region and the non-irradiated one on the Al2O3 layer, and mask patterns can easily be revealed by wet etching. This method is a modification of Ga(+) FIB mask patterning for the silicon etch stop, which eliminates the detrimental lattice damage and doping of the silicon substrate in critical devices. The shallow surface gallium FIB irradiated Al2O3 mask protects the underlying silicon from Ga(+) ions. The performance of the masking capacity was tested by drawing pairs consisting of a line and an empty space with varying width. The best result was seven such pairs for 1 μm. The smallest half pitch was 59 nm. This method is capable of arbitrary pattern generation. The fabrication of a freestanding single-ended tuning fork resonator utilizing the introduced masking method is demonstrated.

  4. Masking patterns for monopolar and phantom electrode stimulation in cochlear implants

    PubMed Central

    Saoji, Aniket A.; Landsberger, David M.; Padilla, Monica; Litvak, Leonid M.

    2013-01-01

    Phantom electrode (PE) stimulation consists of out-of-phase stimulation of two electrodes. When presented at the apex of the electrode array, phantom stimulation is known to produce a lower pitch sensation than monopolar (MP) stimulation on the most apical electrode. The ratio of the current between the primary electrode (PEL) and the compensating electrode (CEL) is represented by the coefficient σ, which ranges from 0 (monopolar) to 1 (full bipolar). The exact mechanism by which PE stimulation produces a lower pitch sensation is unclear. In the present study, unmasked and masked thresholds were obtained using a forward masking paradigm to estimate the spread of current for MP and PE stimulation. Masked thresholds were measured for two phantom electrode configurations (1) PEL = 4, CEL = 5 (lower pitch phantom) and (2) PEL = 4, CEL = 3 (higher pitch phantom). The unmasked thresholds were subtracted from the masked thresholds to obtain masking patterns which were normalized to their peak. The masking patterns reveal (1) differences in the spread of excitation that are consistent with the direction of pitch shift produced by PE stimulation, and (2) narrower spread of electrical excitation for PE stimulation relative to MP stimulation. PMID:23299125

  5. The effect of masking noise on acoustic-phonetic contrasts in post-lingually deafened cochlear implant users

    NASA Astrophysics Data System (ADS)

    Vick, Jennell C.; Perkell, Joseph S.; Stockmann, Ellen; Zandipour, Majid; Lane, Harlan; Tiede, Mark

    2003-10-01

    This study examined the effect on the vowel contrast distance (average inter-vowel distance in the F1-F2 plane) of gradually decreasing the signal-to-noise ratio (SNR) in the auditory feedback of a post-lingually deafened cochlear implant (CI) user at 1-month and 1-year following CI processor activation. Masking noise, mixed with normal levels of speech feedback, was presented through the headpiece of a research sound processor to the CI user. As a control, an analogous procedure was used for a normal-hearing speaker where the masking noise and speech feedback were delivered over headphones. The SNR was gradually decreased over seven steps as the speakers produced ten repetitions of two vowel contrasts (æ\\/[g\\/] and i\\/u). Speech SPL and vowel contrast distance were measured at all seven masking noise levels. Data from both subjects showed that SPL gradually increased with decreased SNR, while contrast distance decreased. The effect was greater after 1 year of experience with a CI than at 1 month. The effect in the NH speaker was similar to that noted in the CI user after 1 year of experience. Data from additional subjects will be analyzed and reported. [Work supported by NIH Grant No. R01 DC03007.

  6. High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol) by helium beam exposure through stencil masks.

    PubMed

    Cacao, Eliedonna E; Nasrullah, Azeem; Sherlock, Tim; Kemper, Steven; Kourentzi, Katerina; Ruchhoeft, Paul; Stein, Gila E; Willson, Richard C

    2013-01-01

    In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2) and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1) and 2870 cm(-1), respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C-O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver nanoparticles.

  7. Optical properties of planar waveguides on ZnWO₄ formed by carbon and helium ion implantation and effects of annealing.

    PubMed

    Zhao, Jin-Hua; Liu, Tao; Guo, Sha-Sha; Guan, Jing; Wang, Xue-Lin

    2010-08-30

    We report on the optical properties of ZnWO(4) planar waveguides created by ion implantation, and the effect annealing has on these structures. Planar optical waveguides in ZnWO(4) crystals are fabricated by 5.0 MeV carbon ion implantation with a fluence of 1 × 10(15) ions/cm(2) or 500 keV helium ion implantation with the a fluence of 1 × 10(16) ions/cm(2). The thermal stability was investigated by 60 minute annealing cycles at different temperatures ranging from 260°C to 550°C in air. The guided modes were measured by a model 2010 prism coupler at wavelengths of 633 nm and 1539 nm. The reflectivity calculation method (RCM) was applied to simulate the refractive index profile in these waveguides. The near-field light intensity profiles were measured using the end-face coupling method. The absorption spectra show that the implantation processes have almost no influence on the visible band absorption.

  8. Lattice modification in KTiOPO4 by hydrogen and helium sequentially implantation in submicrometer depth

    NASA Astrophysics Data System (ADS)

    Ma, Changdong; Lu, Fei; Xu, Bo; Fan, Ranran

    2016-05-01

    We investigated lattice modification and its physical mechanism in H and He co-implanted, z-cut potassium titanyl phosphate (KTiOPO4). The samples were implanted with 110 keV H and 190 keV He, both to a fluence of 4 × 1016 cm-2, at room temperature. Rutherford backscattering/channeling, high-resolution x-ray diffraction, and transmission electron microscopy were used to examine the implantation-induced structural changes and strain. Experimental and simulated x-ray diffraction results show that the strain in the implanted KTiOPO4 crystal is caused by interstitial atoms. The strain and stress are anisotropic and depend on the crystal's orientation. Transmission electron microscopy studies indicate that ion implantation produces many dislocations in the as-implanted samples. Annealing can induce ion aggregation to form nanobubbles, but plastic deformation and ion out-diffusion prevent the KTiOPO4 surface from blistering.

  9. Wafer topography modeling for ionic implantation mask correction dedicated to 2x nm FDSOI technologies

    NASA Astrophysics Data System (ADS)

    Michel, Jean-Christophe; Le Denmat, Jean-Christophe; Sungauer, Elodie; Robert, Frédéric; Yesilada, Emek; Armeanu, Ana-Maria; Entradas, Jorge; Sturtevant, John L.; Do, Thuy; Granik, Yuri

    2013-04-01

    Reflection by wafer topography and underlying layers during optical lithography can cause unwanted exposure in the resist [1]. This wafer stack effect phenomenon which is neglected for larger nodes than 45nm, is becoming problematic for 32nm technology node and below at the ionic implantation process. This phenomenon is expected to be attenuated by the use of anti-reflecting coating but increases process complexity and adds cost and cycle time penalty. As a consequence, an OPC based solution is today under evaluation to cope with stack effects involved in ionic implantation patterning [2] [3]. For the source drain (SD) ionic implantation process step on 28nm Fully Depleted Silicon-on-Insulator (FDSOI) technology, active silicon areas, poly silicon patterns, Shallow Trench Isolation (STI), Silicon-on-Insulator (SOI) areas and the transitions between these different regions result in significant SD implant pattern critical dimension variations. The large number of stack variations involved in these effects implies a complex modeling to simulate pattern degradations. This paper deals with the characterization of stack effects on 28nm node using SOI substrates. The large number of measurements allows to highlight all individual and combined stack effects. A new modeling flow has been developed in order to generate wafer stack aware OPC model. The accuracy and the prediction of the model is presented in this paper.

  10. Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

    SciTech Connect

    Hoffmann, F.; Nguyen-Manh, D.; Gilbert, M. R.; Beck, C. E.; Eliason, J. K.; Maznev, A. A.; Liu, W.; Armstrong, D. E.J.; Nelson, K. A.; Dudarev, S. L.

    2015-02-26

    Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in aW-1% Re alloy after implantation with 3110 appm of helium. An observed lattice expansion of a fraction of a per cent gives rise to an order of magnitude larger reduction in the surface acoustic wave velocity. A multiscale model, combining elasticity and density functional theory, is applied to the interpretation of observations. The measured lattice swelling is consistent with the relaxation volume of self-interstitial and helium-filled vacancy defects that dominate the helium-implanted material microstructure. Larger scale atomistic simulations using an empirical potential confirm the findings of the elasticity and density functional theory model for swelling. The reduction of surface acoustic wave velocity predicted by density functional theory calculations agrees remarkably well with experimental observations.

  11. Forward-Masked Frequency Selectivity Improvements in Simulated and Actual Cochlear Implant Users Using a Preprocessing Algorithm

    PubMed Central

    Jürgens, Tim

    2016-01-01

    Frequency selectivity can be quantified using masking paradigms, such as psychophysical tuning curves (PTCs). Normal-hearing (NH) listeners show sharp PTCs that are level- and frequency-dependent, whereas frequency selectivity is strongly reduced in cochlear implant (CI) users. This study aims at (a) assessing individual shapes of PTCs in CI users, (b) comparing these shapes to those of simulated CI listeners (NH listeners hearing through a CI simulation), and (c) increasing the sharpness of PTCs using a biologically inspired dynamic compression algorithm, BioAid, which has been shown to sharpen the PTC shape in hearing-impaired listeners. A three-alternative-forced-choice forward-masking technique was used to assess PTCs in 8 CI users (with their own speech processor) and 11 NH listeners (with and without listening through a vocoder to simulate electric hearing). CI users showed flat PTCs with large interindividual variability in shape, whereas simulated CI listeners had PTCs of the same average flatness, but more homogeneous shapes across listeners. The algorithm BioAid was used to process the stimuli before entering the CI users’ speech processor or the vocoder simulation. This algorithm was able to partially restore frequency selectivity in both groups, particularly in seven out of eight CI users, meaning significantly sharper PTCs than in the unprocessed condition. The results indicate that algorithms can improve the large-scale sharpness of frequency selectivity in some CI users. This finding may be useful for the design of sound coding strategies particularly for situations in which high frequency selectivity is desired, such as for music perception. PMID:27604785

  12. Ideal time-frequency masking algorithms lead to different speech intelligibility and quality in normal-hearing and cochlear implant listeners.

    PubMed

    Koning, Raphael; Madhu, Nilesh; Wouters, Jan

    2015-01-01

    Hearing impaired listeners using cochlear implants (CIs) suffer from a decrease in speech intelligibility (SI) in adverse listening conditions. Time-frequency masks are often applied to perform noise suppression in an attempt to increase SI. Two important masks are the so-called ideal binary mask (IBM) with its binary weights and the ideal Wiener filter (IWF) with its continuous weights. It is unclear which of the masks has the highest potential for SI and speech quality enhancement in CI users. In this study, both approaches for SI and quality enhancement were compared. The investigations were conducted in normal-hearing (NH) subjects listening to noise vocoder CI simulations and in CI users. The potential for SI improvement was assessed in a sentence recognition task with ideal mask estimates in multitalker babble and with an interfering talker. The robustness of the approaches was evaluated with simulated estimation errors. CI users assessed the speech quality in a preference rating. The IWF outperformed the IBM in NH listeners. In contrast, no significant difference was obtained in CI users. Estimation errors degraded SI in CI users for both approaches. In terms of quality, the IWF outperformed, slightly, the IBM processed signals. The outcomes of this study suggest that the mask pattern is not that crucial for CIs. Results of speech enhancement algorithms obtained with NH subjects listening to vocoded or normally processed stimuli do not translate to CI users. This outcome means that the effect of new strategies has to be quantified with the user group considered.

  13. Evolution kinetics of elementary point defects in ZnO implanted with low fluences of helium at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Bhoodoo, C.; Hupfer, A.; Vines, L.; Monakhov, E. V.; Svensson, B. G.

    2016-11-01

    Hydrothermally grown n -type ZnO samples, implanted with helium (He+) at a sample temperature of ˜40 K and fluences of 5 ×109 and 5 ×1010cm-2 , have been studied in situ by capacitance voltage (CV) and junction spectroscopy measurements. The results are complemented by data from secondary ion mass spectrometry and Fourier transform infrared absorption measurements and first-principles calculations. Removal/passivation of an implantation-induced shallow donor center or alternatively growth of a deep acceptor defect are observed after annealing, monitored via charge carrier concentration (Nd) versus depth profiles extracted from CV data. Isothermal anneals in the temperature range of 290-325 K were performed to study the evolution in Nd, revealing a first-order kinetics with an activation energy, Ea≈0.7 eV and frequency factor, c0˜106s-1 . Two models are discussed in order to explain these annealing results. One relies on transition of oxygen interstitials (Oi) from a split configuration (neutral state) to an octahedral configuration (deep double acceptor state) as a key feature. The other one is based on the migration of Zn interstitials (double donor) and trapping by neutral Zn-vacancy-hydrogen complexes as the core ingredient. In particular, the latter model exhibits good quantitative agreement with the experimental data and gives an activation energy of ˜0.75 eV for the migration of Zn interstitials.

  14. In Situ Electron Microscopy of Helium Bubble Implantation in Metal Hydrides

    SciTech Connect

    Hattar, Khalid Mikhiel; Bufford, Daniel Charles; Robinson, David; Snow, Clark Sheldon

    2014-09-01

    Here we investigated the microstructural response of various Pd physically vapor deposited films and Er and ErD2 samples prepared from neutron Tube targets to implanted He via in situ ion irradiation transmission electron microscopy and subsequent in situ annealing experiments. Small bubbles formed in both systems during implantation, but did not grow with increasing fluence or a short duration room temperature aging (weeks). Annealing produced large cavities with different densities in the two systems. The ErD2 showed increased cavity nucleation compared to Er. The spherical bubbles formed from high fluence implantation and rapid annealing in both Er and ErD2 cases differed from microstructures of naturally aged tritiated samples. Further work is still underway to determine the transition in bubble shape in the Er samples, as well as the mechanism for evolution in Pd films.

  15. Gettering of transition metals by cavities in silicon formed by helium ion implantation

    SciTech Connect

    Petersen, G.A.; Myers, S.M.; Follstaedt, D.M.

    1996-09-01

    We have recently completed studies which quantitatively characterize the ability of nanometer-size cavities formed by He ion implantation to getter detrimental metal impurities in Si. Cavity microstructures formed in Si by ion implantation of He and subsequent annealing have been found to capture metal impurities by two mechanisms: (1) chemisorption on internal walls at low concentrations and (2) silicide precipitation at concentrations exceeding the solid solubility. Experiments utilizing ion-beam analysis, cross-sectional transmission electron microscopy, and secondary ion mass spectrometry were performed to quantitatively characterize the gettering effects and to determine the free energies associated with the chemisorbed metal atoms as a function of temperature. Mathematical models utilizing these results have been developed to predict gettering behavior.

  16. Effect of Helium implantation on gettering and electrical properties of 4H-SiC epilayers

    SciTech Connect

    Biondo, Stephane; Regula, Gabrielle; Ottaviani, Laurent; Palais, Olivier; Pichaud, Bernard

    2011-01-07

    This paper tests the gettering ability of sites created by He implantation in 4H-SiC while heating the sample or not, and their impact on carrier lifetime. The spatial distribution of implantation-induced defects (cavities, stacking faults and dislocations) is studied by transmission electron microscopy (TEM) and is compared to gold profiles performed by Rutherford Backscattering (RBS) in samples intentionally contaminated with gold. Minority carrier lifetimes are also measured with a specific set-up based on microwave photoconductivity decay ({mu}-PCD). Though gold atoms do not seem to be efficiently trapped by cavities, the presence of dislocations is of major importance to monitor gold diffusion. Indeed, they can double both its level and its diffusion length in the bulk. Gold is assumed to diffuse faster along dislocation cores. Besides, the implantation-related defects are found to improve the carrier lifetime in the material, but the role of He{sup 2+} left in cavities remains to be investigated.

  17. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    SciTech Connect

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-07

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst.

  18. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    NASA Astrophysics Data System (ADS)

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-01

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst.

  19. Mask alignment system for semiconductor processing

    DOEpatents

    Webb, Aaron P.; Carlson, Charles T.; Weaver, William T.; Grant, Christopher N.

    2017-02-14

    A mask alignment system for providing precise and repeatable alignment between ion implantation masks and workpieces. The system includes a mask frame having a plurality of ion implantation masks loosely connected thereto. The mask frame is provided with a plurality of frame alignment cavities, and each mask is provided with a plurality of mask alignment cavities. The system further includes a platen for holding workpieces. The platen may be provided with a plurality of mask alignment pins and frame alignment pins configured to engage the mask alignment cavities and frame alignment cavities, respectively. The mask frame can be lowered onto the platen, with the frame alignment cavities moving into registration with the frame alignment pins to provide rough alignment between the masks and workpieces. The mask alignment cavities are then moved into registration with the mask alignment pins, thereby shifting each individual mask into precise alignment with a respective workpiece.

  20. Two-wavelength Raman study of poly(ethylene terephthalate) surfaces modified by helium plasma-based ion implantation

    NASA Astrophysics Data System (ADS)

    Veres, M.; Tóth, A.; Mohai, M.; Bertóti, I.; Szépvölgyi, J.; Tóth, S.; Himics, L.; Koós, M.

    2012-12-01

    The surface of poly(ethylene terephthalate) (PET) was modified by helium plasma-based ion implantation (He PBII). The untreated and surface modified samples were characterised with optical absorption spectroscopy and two-wavelength micro-Raman spectroscopy excited with 488 nm and 785 nm light sources, allowing to examine the chemical bonding configuration of the surface layers on different depths and by selective enhancement of vibrations of different structural units. Upon treatment, simultaneously with the development of the broad D and G bands, a gradual decrease of the peaks corresponding to the Cdbnd C stretching and Cdbnd O stretching modes were observed with both excitations. Downshifting and broadening were detected for the Cdbnd C peak with both excitations and also for the Cdbnd O peak with the 488 nm excitation due to formation of condensed aromatic rings. Oppositely, upshifting was found with 785 nm excitation for the Cdbnd O peak and especially for its broad shoulder newly developed at the high wavenumber side. The latter feature was assigned to Cdbnd O groups attached to polymer chains without conjugation and the bands behaviour was interpreted by breaking of the Cdbnd C bonds of the polymer, leading to the formation of a crosslinked, disordered and stressed structure with still intact Cdbnd O groups, due to the increased nuclear damage at the end of the ion track.

  1. Binding of copper and nickel to cavities in silicon formed by helium ion implantation

    NASA Astrophysics Data System (ADS)

    Myers, S. M.; Follstaedt, D. M.; Bishop, D. M.

    Cavities formed in Si by He ion implantation and annealing are shown to be strong traps for Cu and Ni impurities. Experiments utilizing ion-beam analysis and transmission electron microscopy indicate that Cu is trapped at the internal surfaces of cavities up to approximately 1 monolayer coverage with a binding energy of 2.2 +/- 0.2 eV relative to solution. This is greater than the heat of solution from the precipitated Cu3Si phase, determined to be 1.7 eV in agreement with earlier work. Copper at cavity-wall sites is reversibly replaced by H during heating in H2 gas, indicating the relative stability of the two surface terminations. Initial results for Ni impurities indicate that trapping at cavities is again energetically preferred to silicide formation. The saturation coverage of Ni on the internal surfaces, however, is an order of magnitude smaller for Ni than Cu, consistent with published studies of external-surface adsorption. These results suggest that cavity trapping may getter metallic impurities in Si more effectively than methods based on silicide precipitation.

  2. Binding of copper and nickel to cavities in silicon formed by helium ion implantation

    SciTech Connect

    Myers, S.M.; Follstaedt, D.M.; Bishop, D.M.

    1993-12-01

    Cavities formed in Si by He ion implantation and annealing are shown to be strong traps for Cu and Ni impurities. Experiments utilizing ion-beam analysis and transmission electron microscopy indicate that Cu is trapped at the internal surfaces of cavities up to {approximately}1 monolayer coverage with a binding energy of 2.2{plus_minus}0.2 eV relative to solution. This is greater than the heat of solution from the precipitated Cu{sub 3}Si phase, determined to be 1.7 eV in agreement with earlier work. Copper at cavity-wall sites is reversibly replaced by H during heating in H{sub 2} gas, indicating the relative stability of the two surface terminations. Initial results for Ni impurities indicate that trapping at cavities is again energetically preferred to silicide formation. The saturation coverage of Ni on the internal surfaces, however, is an order of magnitude smaller for Ni than Cu, consistent with published studies of external-surface adsorption. These results suggest that cavity trapping may getter metallic impurities in Si more effectively than methods based on silicide precipitation.

  3. Evaluating multipulse integration as a neural-health correlate in human cochlear-implant users: Relationship to forward-masking recovery.

    PubMed

    Zhou, Ning; Pfingst, Bryan E

    2016-03-01

    The present study evaluated the slopes of threshold-versus-pulse-rate functions (multipulse integration, MPI) in humans with cochlear implants in relation to recovery from 300-ms forward maskers. MPI has been correlated with spiral ganglion cell density in animals. The present study showed that steeper MPI functions were correlated with faster recovery from forward masking. The findings suggested that the variations in the MPI slopes are explained not only by the quantity of neurons contributing to the integration process but also by the neurons' temporal response characteristics and possibly central inhibition.

  4. Effects of helium on ductile-brittle transition behavior of reduced-activation ferritic steels after high-concentration helium implantation at high temperature

    NASA Astrophysics Data System (ADS)

    Hasegawa, A.; Ejiri, M.; Nogami, S.; Ishiga, M.; Kasada, R.; Kimura, A.; Abe, K.; Jitsukawa, S.

    2009-04-01

    The effects of He on the fracture behavior of reduced-activation ferritic/martensitic steels, including oxide dispersion-strengthened (ODS) steels and F82H, was determined by characterizing the microstructural evolution in and fracture behavior of these steels after He implantation up to 1000 appm at around 550 °C. He implantation was carried out by a cyclotron with a beam of 50 MeV α-particles. In the case of F82H, the ductile-to-brittle transition temperature (DBTT) increase induced by He implantation was about 70 °C and the grain boundary fracture surface was only observed in the He-implanted area of all the ruptured specimens in brittle manner. By contrast, no DBTT shift or fracture mode change was observed in He-implanted 9Cr-ODS and 14Cr-ODS steels. Microstructural characterization suggested that the difference in the bubble formation behavior of F82H and ODS steels might be attributed to the grain boundary rupture of He-implanted F82H.

  5. Effects of source-to-listener distance and masking on perception of cochlear implant processed speech in reverberant rooms

    PubMed Central

    Whitmal, Nathaniel A.; Poissant, Sarah F.

    2009-01-01

    Two experiments examined the effects of source-to-listener distance (SLD) on sentence recognition in simulations of cochlear implant usage in noisy, reverberant rooms. Experiment 1 tested sentence recognition for three locations in the reverberant field of a small classroom (volume=79.2 m3). Subjects listened to sentences mixed with speech-spectrum noise that were processed with simulated reverberation followed by either vocoding (6, 12, or 24 spectral channels) or no further processing. Results indicated that changes in SLD within a small room produced only minor changes in recognition performance, a finding likely related to the listener remaining in the reverberant field. Experiment 2 tested sentence recognition for a simulated six-channel implant in a larger classroom (volume=175.9 m3) with varying levels of reverberation that could place the three listening locations in either the direct or reverberant field of the room. Results indicated that reducing SLD did improve performance, particularly when direct sound dominated the signal, but did not completely eliminate the effects of reverberation. Scores for both experiments were predicted accurately from speech transmission index values that modeled the effects of SLD, reverberation, and noise in terms of their effects on modulations of the speech envelope. Such models may prove to be a useful predictive tool for evaluating the quality of listening environments for cochlear implant users. PMID:19894835

  6. Mask cost and specification

    NASA Astrophysics Data System (ADS)

    Watanabe, Hisashi; Higashikawa, Iwao

    2003-12-01

    At the panel discussion of Photomask Japan 2003, we discussed about Mask cost and specification. The topics are (1) Mask price trend and its impact, (2) How to reduce the mask costs; solutions from a mask shop, mask writing tool and mask inspection tool 3) Partnering mask suppliers with mask users; reasonable mask specification and OPC strategies. The choice of DUV laser writer instead of e-beam writer is one solution for reduction of mask cost. The continuous improvement of e-beam writer and resist sensitivity for high throughput is another solution. The partnership between designer, EDA vender, mask maker and wafer lithographer becomes more important.

  7. Clay Mask Workshop

    ERIC Educational Resources Information Center

    Gamble, David L.

    2012-01-01

    Masks can represent so many things, such as emotions (happy, sad, fearful) and power. The familiar "comedy and tragedy" masks, derived from ancient Greek theater, are just one example from mask history. Death masks from the ancient Egyptians influenced the ancient Romans into creating similar masks for their departed. Masks can represent many…

  8. Effect of dislocations on helium retention in deformed pure iron

    NASA Astrophysics Data System (ADS)

    Gong, Y. H.; Cao, X. Z.; Jin, S. X.; Lu, E. Y.; Hu, Y. C.; Zhu, T.; Kuang, P.; Xu, Q.; Wang, B. Y.

    2016-12-01

    The effects of dislocations created by deformation on helium retention in pure iron, including the helium atoms diffusion along the dislocation line and desorption from dislocation trapping sites, were investigated. The dislocation defect was introduced in specimens by cold-rolling, and then 5 keV helium ions were implanted into the deformed specimens. Slow positron beam technology and thermal desorption spectroscopy were used to investigate the evolution of dislocation defects and the desorption behavior of helium atoms under influence of dislocation. The behaviors of S-E, W-E and S-W plots indicate clearly that lots of helium atoms remain in the deformed specimen and helium atoms combining with dislocation change the distribution of electron density. The helium desorption plot indicates that dislocation accelerates helium desorption at 293 K-600 K and facilitates helium dissociation from HenVm (n/m = 1.8) cluster.

  9. Massive inflammatory reaction following the removal of a ruptured silicone implant masking the invasive breast cancer - case report and literature review.

    PubMed

    Nowaczyk, Piotr; Budnicka, Aleksandra; Wichtowski, Mateusz; Kurzawa, Paweł; Murawa, Dawid

    2016-01-01

    This paper presents a case of a patient with invasive ductal breast cancer following breast augmentation. Following breast implants rupture in March 2013 the breast implants have been removed - histopathological examination revealed leaked silicone with inflammatory infiltration, without evidence of cancerous lesions. Diagnostic imaging revealed multiple encapsulated silicone particles and clusters of post-inflammatory macrocalcifications in both breasts. In January 2014 the patient presented with symptoms of massive inflammation of the left breast. Following surgical consultation the patient had undergone radical left-sided mastectomy with lymphadenectomy. Postoperative histopathological examination revealed a multifocal advanced invasive ductal cancer G3 pT3pN3a (vascular invasion, metastases in 11 of 12 examined axillary lymph nodes). Following surgery the patient was qualified for further treatment - chemotherapy, radiotherapy, hormone therapy. The discussion includes a review of literature on the risk evaluation of co-occurrence of breast cancers in women with silicone breast implants and presents diagnostic challenges of breast cancer in this patient group.

  10. Helium tables.

    NASA Technical Reports Server (NTRS)

    Havill, Clinton H

    1928-01-01

    These tables are intended to provide a standard method and to facilitate the calculation of the quantity of "Standard Helium" in high pressure containers. The research data and the formulas used in the preparation of the tables were furnished by the Research Laboratory of Physical Chemistry, of the Massachusetts Institute of Technology.

  11. Masks: Interpretations and Variations.

    ERIC Educational Resources Information Center

    Basso, Robert

    1990-01-01

    Presents a high school art teacher's views of and experiences with masks. Outlines a maskmaking activity in which students were required to create variations on existing masks. Emphasizes use of experimental materials. Displays examples of student-created masks. (DB)

  12. Masks and Other Disguises.

    ERIC Educational Resources Information Center

    Ploghoft, Debra

    Instructions for making simple masks are provided in this guide for teachers of elementary children. Directions with illustrations are given for constructing masks from paper plates, construction paper, plastic milk jugs, and papier-mache. Ideas include a clown mask, a flower mask, a top hat, a paper crown, and "Groucho" glasses. Types…

  13. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation

    PubMed Central

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-01

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density. PMID:28079191

  14. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-01

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density.

  15. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation.

    PubMed

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-12

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density.

  16. Helium diffusion in carbonates

    NASA Astrophysics Data System (ADS)

    Amidon, W. H.; Cherniak, D. J.; Watson, E. B.; Hobbs, D.

    2013-12-01

    The abundance and large grain size of carbonate minerals make them a potentially attractive target for 4He thermochronology and 3He cosmogenic dating, although the diffusive properties of helium in carbonates remain poorly understood. This work characterizes helium diffusion in calcite and dolomite to better understand the crystal-chemical factors controlling He transport and retentivity. Slabs of cleaved natural calcite and dolomite, and polished sections of calcite cut parallel or normal to c, were implanted with 3He at 3 MeV with a dose of 5x1015/cm2. Implanted carbonates were heated in 1-atm furnaces, and 3He distributions following diffusion anneals were profiled with Nuclear Reaction Analysis using the reaction 3He(d,p)4He. For 3He transport normal to cleavage surfaces in calcite, we obtain the following Arrhenius relation over the temperature range 78-300°C: Dcalcite = 9.0x10-9exp(-55 × 6 kJ mol-1/RT) m2sec-1. Diffusion in calcite exhibits marked anisotropy, with diffusion parallel to c about two orders of magnitude slower than diffusion normal to cleavage faces. He diffusivities for transport normal to the c-axis are similar in value to those normal to cleavage surfaces. Our findings are broadly consistent with helium diffusivities from step-heating measurements of calcite by Copeland et al. (2007); these bulk degassing data may reflect varying effects of diffusional anisotropy. Helium diffusion normal to cleavage surfaces in dolomite is significantly slower than diffusion in calcite, and has a much higher activation energy for diffusion. For dolomite, we obtain the following Arrhenius relation for He diffusion over the temperature range 150-400°C: Ddolomite = 9.0x10-8exp(-92 × 9 kJ mol-1/RT) m2sec-1. The role of crystallographic structure in influencing these differences among diffusivities was evaluated using the maximum aperture approach of Cherniak and Watson (2011), in which crystallographic structures are sectioned along possible diffusion

  17. Helium damage and helium effusion in fully stabilised zirconia

    NASA Astrophysics Data System (ADS)

    Damen, P. M. G.; Matzke, Hj.; Ronchi, C.; Hiernaut, J.-P.; Wiss, T.; Fromknecht, R.; van Veen, A.; Labohm, F.

    2002-05-01

    Fully stabilised zirconia (FSZ) samples have been implanted with helium-ions of different energies (200 keV and 1 MeV) and with different fluences (1.4×10 13-1.4×10 16 He +/cm 2). Neutron depth profiling (NDP) for different annealing temperatures and effusion experiments in two different experimental systems with different thermal annealings have been performed on these samples. The samples were analysed by electron microscopy during the various annealing stages. For the low-fluence samples, the diffusion of helium is probably caused by vacancy assisted interstitial diffusion with an activation energy of 1.6 eV. In the highest fluence samples probably high pressure bubbles are formed during thermal annealing.

  18. Masks in Pedagogical Practice

    ERIC Educational Resources Information Center

    Roy, David

    2016-01-01

    In Drama Education mask work is undertaken and presented as both a methodology and knowledge base. There are numerous workshops and journal articles available for teachers that offer knowledge or implementation of mask work. However, empirical examination of the context or potential implementation of masks as a pedagogical tool remains…

  19. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  20. Mask degradation monitoring with aerial mask inspector

    NASA Astrophysics Data System (ADS)

    Tseng, Wen-Jui; Fu, Yung-Ying; Lu, Shih-Ping; Jiang, Ming-Sian; Lin, Jeffrey; Wu, Clare; Lifschitz, Sivan; Tam, Aviram

    2013-06-01

    As design rule continues to shrink, microlithography is becoming more challenging and the photomasks need to comply with high scanner laser energy, low CDU, and ever more aggressive RETs. This give rise to numerous challenges in the semiconductor wafer fabrication plants. Some of these challenges being contamination (mainly haze and particles), mask pattern degradation (MoSi oxidation, chrome migration, etc.) and pellicle degradation. Fabs are constantly working to establish an efficient methodology to manage these challenges mainly using mask inspection, wafer inspection, SEM review and CD SEMs. Aerial technology offers a unique opportunity to address the above mask related challenges using one tool. The Applied Materials Aera3TM system has the inherent ability to inspect for defects (haze, particles, etc.), and track mask degradation (e.g. CDU). This paper focuses on haze monitoring, which is still a significant challenge in semiconductor manufacturing, and mask degradation effects that are starting to emerge as the next challenge for high volume semiconductor manufacturers. The paper describes Aerial inspector (Aera3) early haze methodology and mask degradation tracking related to high volume manufacturing. These will be demonstrated on memory products. At the end of the paper we take a brief look on subsequent work currently conducted on the more general issue of photo mask degradation monitoring by means of an Aerial inspector.

  1. Helium solubility in SON68 nuclear waste glass

    SciTech Connect

    Fares, Toby; Peuget, Sylvain; Bouty, Olivier; Broudic, Veronique; Maugeri, Emilio; Bes, Rene; Jegou, Christophe; Chamssedine, Fadel; Sauvage, Thierry; Deschanels, Xavier

    2012-12-15

    Helium behavior in a sodium borosilicate glass (SON68) dedicated to the immobilization of high-level nuclear waste is examined. Two experimental approaches on nonradioactive glass specimens are implemented: pressurized helium infusion experiments and {sup 3}He ion implantation experiments. The temperature variation of helium solubility in SON68 glass was determined and analyzed with the harmonic oscillator model to determine values of the energy of interaction E(0) at the host sites (about -4000 J/mol), the vibration frequency (about 1.7 x 10{sup 11} s{sup -1}), and the density of solubility sites (2.2 x 10{sup 21} sites cm{sup -3}). The implantation experiments show that a non diffusive transport phenomenon (i.e., athermal diffusion) is involved in the material when the helium concentration exceeds 2.3 x 10{sup 21} He cm{sup -3}, and thus probably as soon as it exceeds the density of solubility sites accessible to helium in the glass. We propose that this transport mechanism could be associated with the relaxation of the stress gradient induced by the implanted helium profile, which is favored by the glass damage. Microstructural characterization by TEM and ESEM of glass specimens implanted with high helium concentrations showed a homogeneous microstructure free of bubbles, pores, or cracking at a scale of 10 nm. (authors)

  2. 2013 mask industry survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt

    2013-09-01

    A comprehensive survey was sent to merchant and captive mask shops to gather information about the mask industry as an objective assessment of its overall condition. 2013 marks the 12th consecutive year for this process. Historical topics including general mask profile, mask processing, data and write time, yield and yield loss, delivery times, maintenance, and returns were included and new topics were added. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. While each year's survey includes minor updates based on feedback from past years and the need to collect additional data on key topics, the bulk of the survey and reporting structure have remained relatively constant. A series of improvements is being phased in beginning in 2013 to add value to a wider audience, while at the same time retaining the historical content required for trend analyses of the traditional metrics. Additions in 2013 include topics such as top challenges, future concerns, and additional details in key aspects of mask masking, such as the number of masks per mask set per ground rule, minimum mask resolution shipped, and yield by ground rule. These expansions beyond the historical topics are aimed at identifying common issues, gaps, and needs. They will also provide a better understanding of real-life mask requirements and capabilities for comparison to the International Technology Roadmap for Semiconductors (ITRS).

  3. Analyzing EUV mask costs

    NASA Astrophysics Data System (ADS)

    Lercel, Michael; Kasprowicz, Bryan

    2016-10-01

    The introduction of Extreme Ultraviolet Lithography (EUV) as a replacement for multiple patterning is based on improvements of cycle time, yield, and cost. Earlier cost studies have assumed a simple assumption that EUV masks (being more complex with the multilayer coated blank) are not more than three times as expensive as advanced ArFi (ArF immersion) masks. EUV masks are expected to be more expensive during the ramp of the technology because of the added cost of the complex mask blank, the use of EUV specific mask tools, and a ramp of yield learning relative to the more mature technologies. This study concludes that, within a range of scenarios, the hypothesis that EUV mask costs are not more than three times that of advanced ArFi masks is valid and conservative.

  4. Helium-3 behavior in some nickel-based amorphous alloys

    SciTech Connect

    Unlu, K.; Vincent, D.H. )

    1992-04-01

    In this paper, helium trapping and release are studied for the nickel-rich amorphous alloys Ni{sub 75.1}Cr{sub 14.0}P{sub 10.1}C{sub 0.08}, Ni{sub 63.5}Zr{sub 36.5}, and Ni{sub 87.7}P{sub 12.3}. Helium-3 is introduced into the samples by implantation at 150-kev energy. The depth distribution of the implanted helium is observed by neutron depth profiling employing he reaction {sup 3}He(n,p){sup 3}H. Two implantation doses are used: 1 {times} 10{sup 16} and 5 {times} 10{sup 16} {sup 3}He/cm{sup 2}. Both implantation doses were chosen to be low enough to avoid blistering or flaking of the surface of the samples. The helium release behavior of the samples is studied by taking depth profiles after each annealing stage. At the same time, electron diffraction is used on parallel samples to observe the microstructure of the samples as a function of annealing. The annealing sequence for each material is broken off when electron diffraction indicated the existence of relatively large crystals in a sample. Only a small fraction of the implanted helium is released in most cases, and a clear correlation between helium release and recrystallization can be found in only one case.

  5. Mask industry assessment: 2003

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2003-12-01

    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was initiated in 2002 with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition.1 This paper presents the results of the second annual survey which is an enhanced version of the inaugural survey building upon its strengths and improving the weak points. The original survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. The assessment is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the critical mask industry. An objective is to create a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. As subsequent years are added, historical profiles can also be created. This assessment includes inputs from ten major global merchant and captive mask manufacturers representing approximately 80% of the global mask market (using revenue as the measure) and making this the most comprehensive mask industry survey ever. The participating companies are: Compugraphics, Dai Nippon Printing, Dupont Photomask, Hoya, IBM, Infineon, Intel, Taiwan Mask Company, Toppan, and TSMC. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the mask industry.

  6. Object Substitution Masking: When Does Mask Preview Work?

    ERIC Educational Resources Information Center

    Lim, Stephen Wee Hun; Chua, Fook K.

    2008-01-01

    When a target is enclosed by a 4-dot mask that persists after the target disappears, target identification is worse than it is when the mask terminates with the target. This masking effect is attributed to object substitution masking (OSM). Previewing the mask, however, attenuates OSM. This study investigated specific conditions under which mask…

  7. Helium-Recycling Plant

    NASA Technical Reports Server (NTRS)

    Cook, Joseph

    1996-01-01

    Proposed system recovers and stores helium gas for reuse. Maintains helium at 99.99-percent purity, preventing water vapor from atmosphere or lubricating oil from pumps from contaminating gas. System takes in gas at nearly constant low back pressure near atmospheric pressure; introduces little or no back pressure into source of helium. Concept also extended to recycling of other gases.

  8. Thermal helium desorption behavior in advanced ferritic steels

    NASA Astrophysics Data System (ADS)

    Kimura, Akihiko; Sugano, R.; Matsushita, Y.; Ukai, S.

    2005-02-01

    Thermal helium desorption measurements were performed to investigate the difference in the helium trapping and accumulation behavior among a reduced activation ferritic (RAF) steel and oxide dispersion strengthening (ODS) steels after implantation of He+ ions at room temperature. Thermal helium desorption spectra (THDS) were obtained during annealing to 1200 °C at a heating rate of 1 °C/s. The THDS of the ODS steels are very similar to that of the RAF steel, except for the presence of the peak in the temperature range from 800 to 1000 °C, where the α γ transformation related helium desorption from the γ-phase is considered to occur in the 9Cr-ODS martensitic steels. The fraction of helium desorption becomes larger at higher temperatures, and this trend is increased with the amount of implanted helium. In the 9Cr-ODS steels, the fraction of helium desorption by bubble migration mechanism was smaller than that in the RAF steel. This suggests that the bubble formation was suppressed in the ODS steels. In the 12Cr-ODS steel, the fraction of helium desorption by bubble migration reached more than 90%, suggesting that the trapping capacity of martensite phase in the 9Cr-ODS steel is rather large.

  9. Enhancement in Informational Masking

    ERIC Educational Resources Information Center

    Cao, Xiang; Richards, Virginia M.

    2012-01-01

    Purpose: The ability to detect a tone added to a random masker improves when a preview of the masker is provided. In 2 experiments, the authors explored the role that perceptual organization plays in this release from masking. Method: Detection thresholds were measured in informational masking studies. The maskers were drawn at random prior to…

  10. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  11. Large area self-assembled masking for photonic applications

    NASA Astrophysics Data System (ADS)

    Nagy, N.; Pap, A. E.; Horváth, E.; Volk, J.; Bársony, I.; Deák, A.; Hórvölgyi, Z.

    2006-08-01

    Ordered porous structures for photonic application were fabricated on p- and n-type silicon by means of masking against ion implantation with Langmuir-Blodgett (LB) films. LB films from Stöber silica spheres [J. Colloid Interface Sci. 26, 62 (1968)] of 350nm diameter were applied in the boron and phosphorus ion-implantation step, thereby offering a laterally periodic doping pattern. Ordered porous silicon structures were obtained after performing an anodic etch and were then removed by alkaline etching resulting in the required two-dimensional photonic arrangement. The LB silica masks and the resulting silicon structures were studied by field emission scanning electron microscope analysis.

  12. 2012 Mask Industry Survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt; Litt, Lloyd C.

    2012-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to semiconductor industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. 2012 marks the 11th consecutive year for the mask industry survey. This year's survey and reporting structure are similar to those of the previous years with minor modifications based on feedback from past years and the need to collect additional data on key topics. Categories include general mask information, mask processing, data and write time, yield and yield loss, delivery times, and maintenance and returns. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. Results, initial observations, and key comparisons between the 2011 and 2012 survey responses are shown here, including multiple indications of a shift towards the manufacturing of higher end photomasks.

  13. A study of helium mobility in polycrystalline uranium dioxide

    NASA Astrophysics Data System (ADS)

    Garcia, P.; Martin, G.; Desgardin, P.; Carlot, G.; Sauvage, T.; Sabathier, C.; Castellier, E.; Khodja, H.; Barthe, M.-F.

    2012-11-01

    The mobility of Helium in polycrystalline uranium dioxide was studied by implanting samples with 3He ions at depths of approximately 1 μm and at concentrations in the region of 0.1 at.%. Samples were subsequently annealed at temperatures ranging between 700 °C and 1100 °C. Helium movement was then characterised using three different types of Nuclear Reaction Analysis (NRA) techniques based on the 3He(d,α)p reaction. The fraction of helium released from samples was measured during annealing at high temperature as a function of time. After each annealing sequence, helium depth profiles were obtained for each sample. In some cases, samples were characterised over small areas (60 × 60 μm2), using a micrometre size deuteron beam. This enables the measurement of helium distributions at the surface of samples. Using this novel approach which provides time and space dependent information relating to helium atom location, we show that grain boundaries act as effective short circuits for helium movement and release at all temperatures. Also, at temperatures above approximately 800 °C, in areas around the grain boundaries extending into the grain over distances of the order of microns, helium diffusion is high. In areas further into the grain, diffusion proceeds much more slowly presumably as a result of helium cluster formation. These observations are interpreted based on radiation damage production and annealing processes.

  14. New mask technology challenges

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2001-09-01

    Mask technology development has accelerated dramatically in recent years from the glacial pace of the last three decades to the rapid and sometimes simultaneous introductions of new wavelengths and mask-based resolution enhancement techniques. The nature of the semiconductor business has also become one driven by time-to-market as an overwhelming factor in capturing market share and profit. These are among the factors that have created enormous stress on the mask industry to produce masks with enhanced capabilities, such as phase-shifting attenuators, sub-resolution assist bars, and optical proximity correction (OPC) features, while maintaining or reducing cost and cycle time. The mask can no longer be considered a commodity item that is purchased form the lowest-cost supplier. Instead, it must now be promoted as an integral part of the technical and business case for a total lithographic solution. Improving partnership between designer, mask-maker, and wafer lithographer will be the harbinger of success in finding a profitable balance of capability, cost, and cycle time. Likewise for equipment infrastructure development, stronger partnership on the international level is necessary to control development cost and mitigate schedule and technical risks.

  15. Mask Industry Assessment: 2011

    NASA Astrophysics Data System (ADS)

    Chan, Y. David

    2011-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the tenth in the current series of annual reports. With ongoing industry support, the report has been used as one of the baselines to gain perspective on the technical and business status of the mask and microelectronics industries. It continues to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was essentially the same as the 2005 through 2010 surveys. Questions are grouped into following categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  16. Mask Industry Assessment: 2010

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Chan, David Y.

    2010-09-01

    A survey created supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the ninth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. It will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was basically the same as the 2005 through 2009 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  17. Masks: The Artist in Me

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2009-01-01

    Whether masks are made from cardboard, papier-mache, metal, wood, leather, fabric, clay or any combination of these materials, they bring out the artist in people. Young children like to wear masks when they play to pretend they were another person or animal. Masks let them fantasize and be creative. The author's students made masks representing…

  18. Helium embrittlement of a lamellar titanium aluminide

    NASA Astrophysics Data System (ADS)

    Magnusson, P.; Chen, J.; Jung, P.; Sauvage, T.; Hoffelner, W.; Spätig, Ph.

    2013-03-01

    Embrittlement by helium was investigated in a lamellar TiAl alloy under two conditions: Specimens were implanted to various amounts of helium up to 762 appm at temperatures from 630 °C to 1000 °C and some of them subsequently creep-tested at the same temperature under stresses from 150 to 300 MPa. The microstructure and fracture surfaces of creep-deformed and non-creep-deformed specimens were then studied by transmission electron microscopy (TEM) and by scanning electron microscopy (SEM), respectively. Specimens were implanted to various amounts of helium at a low temperature (150 °C) and post-implantation annealed at elevated temperatures for TEM studies. Embrittlement was revealed by reduction in time- and strain-to-rupture and by a transition in fracture surface from ductile to an inter-lamellar appearance. Embrittlement occurred above a critical He concentration, which decreased from about 10 appm at 700 °C to below 6 appm at 900 °C. TEM showed that embrittlement could be associated to reaching a critical bubble diameter of about 5 nm. Bubble diameters increased with increasing temperature ranging in high-temperature implanted specimens from about 3 nm (630 °C) to 20 nm (1000 °C) and in post-implantation annealed ones from 1.2 nm (600 °C) to 2.2 nm (900 °C), respectively. With increasing temperature, the bubble distribution grew less homogenous with a lower density of larger bubbles situated preferentially at interfaces and sinks. This was ascribed to a change in bubble nucleation mode from homogeneous di-atomic nucleation at lower temperatures to multi-atomic nucleation at sinks at higher temperature.

  19. Helium bubble evolution in a Zr–Sn–Nb–Fe–Cr alloy during post-annealing: An in-situ investigation

    SciTech Connect

    Shen, H.H.; Peng, S.M.; Chen, B.; Naab, F.N.; Sun, G.A.; Zhou, W.; Xiang, X.; Sun, K.; Zu, X.T.

    2015-09-15

    The formation of helium bubbles is considered to be detrimental to the mechanical performance of the nuclear materials. The growth behaviors of helium bubbles in a helium ion implanted Zr–Sn–Nb–Fe–Cr alloy with respect to the helium fluence and subsequently annealing procedure were investigated by in-situ transmission electron microscopy. In the as-implanted sample, the measured size distributions of the helium bubbles are consistent with the simulated helium concentrations. Moreover, the mean size of the helium bubbles increases with the increase of the irradiation temperatures and the helium fluence. The in-situ heating study performed in a transmission electron microscope indicates that the mean size of the helium bubbles increase slowly below 923 K and dramatically above 923 K. The coarsening mechanism of the helium bubbles in the alloy is suggested based on the study. - Highlights: • Helium bubble growth in zirconium with annealing was in-situ investigated in TEM. • The mean helium bubble size increase with helium fluence and annealing temperature. • Helium bubble size distribution is same as that of helium concentration by SRIM. • Mean bubble size increases slowly and quickly with temperature below and above 923 K. • The growth mechanism of the helium bubbles in Zr alloy has been discussed.

  20. Helium segregation on surfaces of plasma-exposed tungsten

    SciTech Connect

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-01-21

    Here we report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He-n (1 <= n <= 7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. Elastic interaction force induces drift fluxes of these mobile Hen clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. Moreover, these near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.

  1. Helium segregation on surfaces of plasma-exposed tungsten

    DOE PAGES

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; ...

    2016-01-21

    Here we report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He-n (1 <= n <= 7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides themore » thermodynamic driving force for surface segregation. Elastic interaction force induces drift fluxes of these mobile Hen clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. Moreover, these near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.« less

  2. Helium segregation on surfaces of plasma-exposed tungsten

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-02-01

    We report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He n (1  ⩽  n  ⩽  7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. This elastic interaction force induces drift fluxes of these mobile He n clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters’ drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. These near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.

  3. Overview of Mask Metrology

    NASA Astrophysics Data System (ADS)

    Rice, Bryan J.; Jindal, Vibhu; Lin, C. C.; Harris-Jones, Jenah; Kwon, Hyuk Joo; Ma, Hsing-Chien; Goldstein, Michael; Chan, Yau-Wai; Goodwin, Frank

    2011-11-01

    Extreme ultraviolet (EUV) lithography is the successor to optical lithography and will enable advanced patterning in semiconductor manufacturing processes down to the 8 nm half pitch technology node and beyond. However, before EUV can successfully be inserted into high volume manufacturing a few challenges must be overcome. Central among these remaining challenges is the requirement to produce "defect free" EUV masks. Mask blank defects have been one of the top challenges in the commercialization of extreme ultraviolet (EUV) lithography. To determine defect sources and devise mitigation solutions, detailed characterization of defects is critical. However, small defects pose challenges in metrology scale-up. SEMATECH has a comprehensive metrology strategy to address any defect larger than a 20 nm core size to obtain solutions for defect-free EUV mask blanks. SEMATECH's Mask Blank Development Center has been working since 2003 to develop the technology to support defect free EUV mask blanks. Since 2003, EUV mask blank defects have been reduced from 10000 of size greater than 100 nm to about a few tens at size 70 nm. Unfortunately, today's state of the art defect levels are still about 10 to 100 times higher than needed. Closing this gap requires progress in the various processes associated with glass substrate creation and multilayer deposition. That process development improvement in turn relies upon the availability of metrology equipment that can resolve and chemically characterize defects as small as 30 nm. The current defect reduction efforts at SEMATECH have intensively included a focus on inspection and characterization. The facility boasts nearly 100M of metrology hardware, including an FEI Titan TEM, Lasertec M1350 and M7360 tools, an actinic inspection tool, AFM, SPM, and scanning auger capabilities. The newly established Auger tool at SEMATECH can run a standard 6-inch mask blank and is already providing important information on sub-100 nm defects on EUV

  4. Helium mobility in SON68 borosilicate nuclear glass: A nuclear reaction analysis approach

    NASA Astrophysics Data System (ADS)

    Bès, R.; Sauvage, T.; Peuget, S.; Haussy, J.; Chamssedine, F.; Oliviero, E.; Fares, T.; Vincent, L.

    2013-11-01

    The 3He behavior in the non active R7T7 type borosilicate glass called SON68 has been investigated using the implantation method to introduce helium in the material. Nuclear Reaction Analysis (NRA) was performed to follow the helium concentration depth profile evolution as a function of annealing time and temperature. In addition, in situ Transmission Electron Microscopy (TEM) has been implemented to study the formation of helium bubbles during both implantation and annealing processes. Numerical modeling with two different approaches is proposed and discussed to investigate the helium mobility mechanisms. Our study reveals for helium incorporation by implantation at low temperature the presence of several helium populations with disparate diffusivities. The most mobile helium fraction would be attributed to atomic diffusion. The corresponding activation energy value (0.61 eV) extracted from Arrhenius graphs is in good agreement with literature data. The results also highlight that the damages associated to helium sursaturation are the source of small helium clusters formation, with a reduced mobility instead of the atomic mobility measured by the infusion technique. Small cavities that support this assumption have been observed by TEM at low temperature.

  5. MSB for ILT masks

    NASA Astrophysics Data System (ADS)

    Gramss, Juergen; Weidenmueller, Ulf; Stoeckel, Arnd; Jaritz, Renate; Doering, Hans-Joachim; Boettcher, Monika

    2011-03-01

    Multi Shaped Beam (MSB) throughput simulation results have already been published in the past. An IC mask set of a 32nm node logic device was one of the applications that had been analyzed in more detail. In this paper we want to highlight results of shot count and write time evaluations done for Inverse Lithography Technology (ILT) masks targeting the 22nm technology node. The test pattern data we used for these practice-oriented analyses was designed by DNP / Japan and created by Luminescent Technologies, Inc. / USA. To achieve reliable evaluation results, the influence of different MSB configurations on shot count and mask write time has been taken into account and will be discussed here. Exposure results of pattern details are presented and compared with the fracturing result. The MSB engineering tool we used for our investigations covers such major components like an electron-optical column, a precision x/y stage and the MSB data path.

  6. Nanostructures from hydrogen implantation of metals.

    SciTech Connect

    McWatters, Bruce Ray; Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2009-09-01

    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  7. Masked mycotoxins: A review

    PubMed Central

    Berthiller, Franz; Crews, Colin; Dall'Asta, Chiara; Saeger, Sarah De; Haesaert, Geert; Karlovsky, Petr; Oswald, Isabelle P; Seefelder, Walburga; Speijers, Gerrit; Stroka, Joerg

    2013-01-01

    The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders. PMID:23047235

  8. COAs: Behind the Masks.

    ERIC Educational Resources Information Center

    Birke, Szifra

    1993-01-01

    Provides information on alcoholism and codependency to help teachers identify and respond to children of alcoholics (COAs). Discusses characteristics of alcoholic homes and problems encountered by children and adult COAs. Examines survival "masks" of COAs, including hero, rebel, adjustor, clown, and caretaker. Lists organizational,…

  9. Apodized Phase Mask Coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlotti, Alexis

    2013-01-01

    Among the optical instruments proposed to detect and characterize exoplanets, phase masks coronagraphs offer very small inner working angles. Designed for off-axis telescopes, their performance is greatly reduced when used with centrally obstructed apertures such as those of the Palomar telescope, the very large telescope, or the James Webb space telescope. However, a clear circular aperture is not the only pupil shape for which a phase mask coronagraph can work properly. In fact, for a given centrally obstructed aperture, we show that it is possible to compute optimal apodizers that help achieve stellar extinction levels similar to those obtained in the ideal case of an off-axis telescope. Trade-offs exist between these levels, the transmission of the apodizer, and the area covered by the Lyot stop. We detail the Fourier optics formalism that makes these optimizations possible, as well as a few examples of shaped pupils. Some are designed for a four-quadrants phase mask, and some others for a vortex phase mask. We also offer a comparison with a coronagraph solely composed of a shaped pupil.

  10. Masked mycotoxins: a review.

    PubMed

    Berthiller, Franz; Crews, Colin; Dall'Asta, Chiara; Saeger, Sarah De; Haesaert, Geert; Karlovsky, Petr; Oswald, Isabelle P; Seefelder, Walburga; Speijers, Gerrit; Stroka, Joerg

    2013-01-01

    The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.

  11. Competing for Consciousness: Prolonged Mask Exposure Reduces Object Substitution Masking

    ERIC Educational Resources Information Center

    Goodhew, Stephanie C.; Visser, Troy A. W.; Lipp, Ottmar V.; Dux, Paul E.

    2011-01-01

    In object substitution masking (OSM) a sparse, temporally trailing 4-dot mask impairs target identification, even though it has different contours from, and does not spatially overlap with the target. Here, we demonstrate a previously unknown characteristic of OSM: Observers show reduced masking at prolonged (e.g., 640 ms) relative to intermediate…

  12. LSI/VLSI (Large Scale Integration/Very Large Scale Integration) ion implanted GaAs (Gallium Arsenide) IC processing. Appendix A: Feasibility analysis of Gallium-Arsenide mask programmable functions and logic arrays for high performance communications systems

    NASA Astrophysics Data System (ADS)

    Zucca, R. R.; Kirkpatrick, C. G.; Asbeck, P. M.; Eisen, F. H.; Lee, C. P.

    1984-01-01

    Circuits critical to the performance of advanced radio, radar and spread spectrum communications systems require advances in the state-of-the-art in semiconductor technology to meet the demands of advanced systems. As these systems increase in complexity, extensive digital circuitry is required in addition to the typical linear signal processing circuits. The power, size and weight of advanced systems also becomes unacceptable without continuous advances in semiconductor technology. Moreover an increasing trend is seen in the use of metal mask selectable functions, programmable logic arrays and gate arrays to implement system specific circuitry in an attempt to lower non-recurring costs, minimize risk and shorten development times. GaAs and other technologies with very high speed power-performance figures-of-merit are critical ingredients in systems implementations which satisfy these needs. To meet these advanced system requirements this project was initiated as a multi-phase/year program to develop a group of mask programmable gallium arsenide (GaAs) circuit elements applicable to high speed/performance communications systems.

  13. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  14. The Descending Helium Balloon

    ERIC Educational Resources Information Center

    Helseth, Lars Egil

    2014-01-01

    I describe a simple and fascinating experiment wherein helium leaks out of a rubber balloon, thereby causing it to descend. An estimate of the volumetric leakage rate is made by measuring its rate of descent.

  15. Atomistic modeling of growth and coalescence of helium nano-bubbles in tungsten

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Krasheninnikov, S. I.; Guterl, J.

    2015-08-01

    The mechanisms of growth and coalescence of helium nano-bubbles in tungsten are investigated using molecular dynamics simulations. It is shown that crystal symmetries and governed by them properties of dislocations, generated by the growing nano-bubbles, are responsible for main nano-bubble features revealed, including non-spherical shape and anisotropy of surrounding stress field. The transport of helium atoms in non-uniform stress field is simulated at different temperatures and the transport coefficients are determined. The implications of the considered dislocation and helium dynamics on nucleation and growth of bubbles in tungsten with implanted helium are discussed.

  16. Evaluation of mask manufacturing efficiency using mask data rank information

    NASA Astrophysics Data System (ADS)

    Kato, Kokoro; Endo, Masakazu; Inoue, Tadao; Yamabe, Masaki; Nakatake, Shigetoshi

    2010-05-01

    The photomask cost is becoming one of the challenging issues in the semiconductor industry, as the cost of photomasks has been rising year by year. ASET started Mask D2I (Mask Design, Drawing and Inspection Technology) project with the sponsorship from the NEDO (New Energy and Industrial Technology Development Organization) in 2006 for the purpose of the mask cost reduction. In earlier papers[1-5], we introduced the idea of photomask data prioritization method which is referred to as Mask Data Rank (MDR). We have built our software system to convert Design Intent (DI) to MDR with cooperation of STARC. Then we showed the results of experiments with mask data provided by semiconductor companies. In this paper we show the additional report of mask inspection experiments using real photomasks. Then we show the evaluation results about mask drawing time reduction using MDR flow. Finally we introduce detailed algorithm to extract design intent from analog circuits.

  17. RHIC Prefire Protection Masks

    SciTech Connect

    Drees, A.; Biscardi, C.; Curcio, T.; Gassner, D.; DeMonte, V.; DeSanto, L.; Fu, W.; Liaw, C. J.; Montag, C.; Thieberger, P.; Yip, K.

    2015-01-07

    The protection of the RHIC experimental detectors from damage due to beam hitting close upstream elements in cases of abort kicker prefires requires some dedicated precautionary measures with two general options: to bring the beam close to a limiting aperture (i.e. the beam pipe wall), as far upstream of the detector components as possible or, alternatively, to bring a limiting aperture close to the circulating beam. During the FY 2014 RHIC Heavy Ion run the first option was chosen because of the limited time available for preparation before the start of the run. For future runs the second option, in this case the installation of dual-sided movable masks, is preferred. The installation of the masks, one per ring, is planned before the start of the FY 2015 run.

  18. On Masking Effect

    DTIC Science & Technology

    1993-07-01

    solution will perform better than the others and present experimental data supportive of the analysis. This investigation is based on simulated robot...solution will perform better than the agent’s task is to catch the evasion agent. Both agents others, and present experimental data supportive of the...Masking interception, and the resultant time lost from hiding and The previous section ruled out refinement stratgies replanning. Without the learned rule

  19. Masked multichannel analyzer

    DOEpatents

    Winiecki, Alan L.; Kroop, David C.; McGee, Marilyn K.; Lenkszus, Frank R.

    1986-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  20. Masked multichannel analyzer

    DOEpatents

    Winiecki, A.L.; Kroop, D.C.; McGee, M.K.; Lenkszus, F.R.

    1984-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  1. Masks: Culture and Kids.

    ERIC Educational Resources Information Center

    Patterson, MaryEllen; And Others

    This guide describes a 7-day lesson plan to be used with bilingual 3rd and 4th graders and 6th, 7th, and 8th graders in English-as-a-Second-Language (ESL) classes. The guide shows how mask making can be tied into each class, and then how to pull the classes together for the older students to become peer tutors to the younger ones in the…

  2. Thermal annealing behaviour and defect evolution of helium in fully stabilised zirconia

    NASA Astrophysics Data System (ADS)

    Damen, P. M. G.; van Veen, A.; Labohm, F.; Schut, H.; van Huis, M. A.

    2003-06-01

    Helium implantations in fully stabilised zirconia have been performed with 30 keV ions with high doses (5.1 × 10 16 and 2.6 × 10 16 cm -2) and low doses (6.3 × 10 15 and 1.7 × 10 15 cm -2). The retained amount of helium and depth profiles have been monitored with neutron depth profiling and the damage distribution with positron beam analysis (PBA) after several annealing steps. The temperature dependent helium release was investigated by thermal helium desorption spectrometry. In the low dose samples, helium is released through diffusion as seen by a broadening of the helium distribution peak. PBA, performed with a two-layer model, shows shrinkage of the damage layer during annealing. For the high dose samples the helium peak does not broaden after annealing. Helium is retained up to high temperatures which is ascribed to bubble formation during thermal annealing. Fitting of the PBA results to a three-layer model shows that the ion implanted layer gets narrower after annealing at 600 K, up to 1000 K the S-parameter is increasing because helium is released from the bubbles, whereby vacancy clusters are left behind.

  3. The Attentional Dynamics of Masked Detection

    ERIC Educational Resources Information Center

    Smith, Philip L.; Wolfgang, Bradley J.

    2004-01-01

    A dichoptic masking procedure was used to test whether the mask-dependent cuing effects found in luminance detection by P. L. Smith (2000a) were due to integration masking or interruption masking. Attentional cuing enhanced detection sensitivity (d') when stimuli were backwardly masked with either dichoptic or monoptic masks, whereas no cuing…

  4. Mask strategy at International SEMATECH

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2002-08-01

    International SEMATECH (ISMT) is a consortium consisting of 13 leading semiconductor manufacturers from around the globe. Its objective is to develop the infrastructure necessary for its member companies to realize the International Technology Roadmap for Semiconductors (ITRS) through efficiencies of shared development resources and knowledge. The largest area of effort is lithography, recognized as a crucial enabler for microelectronics technology progress. Within the Lithography Division, most of the efforts center on mask-related issues. The development strategy at International SEMATCH will be presented and the interlock of lithography projects clarified. Because of the limited size of the mask production equipment market, the business case is weak for aggressive investment commensurate with the pace of the International Technology Roadmap for Semiconductors. With masks becoming the overwhelming component of lithography cost, new ways of reducing or eliminating mask costs are being explored. Will mask technology survive without a strong business case? Will the mask industry limit the growth of the semiconductor industry? Are advanced masks worth their escalating cost? An analysis of mask cost from the perspective of mask value imparted to the user is presented with examples and generic formulas for the reader to apply independently. A key part to the success for both International SEMATECH and the industry globally will be partnerships on both the local level between mask-maker and mask-user, and the macro level where global collaborations will be necessary to resolve technology development cost challenges.

  5. EUV mask black border evolution

    NASA Astrophysics Data System (ADS)

    Turley, Christina; Bonam, Ravi; Gallagher, Emily; Grohs, Jonathan; Kagawa, Masayuki; Kindt, Louis; Narita, Eisuke; Nash, Steven; Sakamoto, Yoshifumi

    2014-10-01

    The black border is a frame created by removing all the multilayers on the EUV mask in the region around the chip. It is created to prevent exposure of adjacent fields when printing an EUV mask on a wafer. Papers have documented its effectiveness. As the technology transitions into manufacturing, the black border must be optimized from the initial mask making process through its life. In this work, the black border is evaluated in three stages: the black border during fabrication, the final sidewall profile, and extended lifetime studies. This work evaluates the black border through simulations and physical experiments. The simulations address concerns for defects and sidewall profiles. The physical experiments test the current black border process. Three masks are used: one mask to test how black border affects the image placement of features on mask and two masks to test how the multilayers change through extended cleans. Data incorporated in this study includes: registration, reflectivity, multilayer structure images and simulated wafer effects. By evaluating the black border from both a mask making perspective and a lifetime perspective, we are able to characterize how the structure evolves. The mask data and simulations together predict the performance of the black border and its ability to maintain critical dimensions on wafer. In this paper we explore what mask changes occur and how they will affect mask use.

  6. Masks in imaging flow cytometry.

    PubMed

    Dominical, Venina; Samsel, Leigh; McCoy, J Philip

    2017-01-01

    Data analysis in imaging flow cytometry incorporates elements of flow cytometry together with other aspects of morphological analysis of images. A crucial early step in this analysis is the creation of a mask to distinguish the portion of the image upon which further examination of specified features can be performed. Default masks are provided by the manufacturer of the imaging flow cytometer but additional custom masks can be created by the individual user for specific applications. Flawed or inaccurate masks can have a substantial negative impact on the overall analysis of a sample, thus great care must be taken to ensure the accuracy of masks. Here we discuss various types of masks and cite examples of their use. Furthermore we provide our insight for how to approach selecting and assessing the optimal mask for a specific analysis.

  7. Mask requirements for advanced lithography

    NASA Astrophysics Data System (ADS)

    Trybula, Walter J.; Engelstad, Roxann L.

    1998-06-01

    Within the n ext 10 years, sub-100 nm features will be required for state-of-the-industry devices. The tolerances for errors at 100 nm or less are substantially smaller than can be achieved today. A critical element of the error budget is the mask. For the 100 nm generation, the 4x mask image placement requirement is 20 nm with CD requirements as low as 9 nm. The challenge would be significant if the only improvement were to develop superior optical masks. There are multiple advanced technologies that are vying to be the successor to optical lithography. Each of these has a unique mask requirement. The leading contenders for the next generation are 1x x-ray, projection e-beam, ion beam, EUV and cell projection e-beam. The x-ray design is a proximity system that employs a 1x membrane mask. Projection e-beam uses a membrane mask with stabilizing struts. Ion beam lithography employs a stencil membrane mask with a carbon coating. EUV employs a 13 nm radiation source that requires a reflective mask. Cell projection e-beam has 25x or greater image masks that are stitched on the wafer. All the technologies indicated above. Once a total error budget for the mask is known, it is necessary to divide the total into the constituent parts. The major sources of distortion can be categorized into eight areas: mask blank processing, e- beam writing, pattern transfer, pellicle effects, mounting, thermal loadings, dynamic effects during exposure and radiation damage. The distortions introduced by each of these depend upon the type of mask; so, individual mask calculations must be made. The purpose of this paper is to review the modeling requirements of each of the categories and to highlight some results from each of the mask configurations.

  8. A quantitative μNRA study of helium intergranular and volume diffusion in sintered UO 2

    NASA Astrophysics Data System (ADS)

    Martin, G.; Desgardin, P.; Sauvage, T.; Garcia, P.; Carlot, G.; Khodja, H.; Barthe, M. F.

    2006-08-01

    To understand the mechanisms related to helium migration in nuclear oxide fuels, 3He was implanted at 2 × 1016 at. cm-2 in UO2 sintered disks. The samples were then annealed at temperatures ranging between 800 °C and 1300 °C. Changes in helium concentrations were investigated using two nuclear reaction analysis techniques based on the 3He(d, α)1H reaction. The first technique uses a macrobeam in order to measure helium depth profiles averaged over a 500 × 500 μm2 area. The second technique uses a microbeam and provides a quantitative two-dimensional helium concentration cartography, for which each pixel corresponds to a depth integrated helium signal. The analysed zones were optically characterised which enabled a detailed analysis of the impact of the material microstructure on helium release from the samples, with an emphasis on the study of grain boundary effects.

  9. Irradiation damage effects on helium migration in sintered uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Sabathier, C.; Carlot, G.; Desgardin, P.; Raepsaet, C.; Sauvage, T.; Khodja, H.; Garcia, P.

    2012-02-01

    In this study, the effects of radiation on helium migration are investigated through the analysis of polycrystalline uranium dioxide samples irradiated at fluences up to 5 × 10 15 at. cm -2 with 8 MeV iodine ions. Following irradiation, samples are implanted with 500 keV 3He + ions at fluences in the range of 10 16 at. cm -2. Three nuclear reaction analysis (NRA) techniques are subsequently implemented using the 3He( 2H, 1H) 4He reaction. The influence of temperature using NRA was first studied based upon 3He depth profile changes and the on-line monitoring of helium release. The effect of the sample microstructure was also investigated at the grain scale by performing analyses of the helium spatial distribution with a nuclear microprobe. Neither substantial helium release nor depth profile changes are observed at temperatures below 900 °C in irradiated samples. Following annealing at temperatures above 1000 °C, a substantial proportion of the implanted helium is released from the samples. From this temperature upwards, the two dimensional He cartographies reveal that the gas has been preferentially released in the vicinity of grain boundaries. These results can be interpreted in the light of previous studies in terms of gas precipitation and re-solution. Helium precipitation is enhanced in irradiated samples up to 900 °C because of the presence of irradiation induced defects. At temperatures in excess of 1000 °C, the precipitated helium is partly returned to the matrix hence it is preferentially released in regions adjacent to grain boundaries, which appear to act as defect sinks.

  10. Is solid helium a supersolid?

    SciTech Connect

    Hallock, Robert

    2015-05-15

    Recent experiments suggest that helium-4 atoms can flow through an experimental cell filled with solid helium. But that incompletely understood flow is quite different from the reported superfluid-like motion that so excited physicists a decade ago.

  11. Helium-refrigeration system

    SciTech Connect

    Specht, J.R.; Millar, B.; Sutherland, A.

    1995-08-01

    The design, procurement, and preliminary construction was completed for adding two more wet expansion engines to two helium refrigerators. These will be added in mid-year FY 1995. In addition a variable speed drive will be added to an existing helium compressor. This is part of an energy conservation upgrade project to reduce operating costs from the use of electricity and liquid nitrogen. This project involves the replacement of Joule-Thompson valves in the refrigerators with expansion engines resulting in system efficiency improvements of about 30% and improved system reliability.

  12. Mask fabrication process

    DOEpatents

    Cardinale, Gregory F.

    2000-01-01

    A method for fabricating masks and reticles useful for projection lithography systems. An absorber layer is conventionally patterned using a pattern and etch process. Following the step of patterning, the entire surface of the remaining top patterning photoresist layer as well as that portion of an underlying protective photoresist layer where absorber material has been etched away is exposed to UV radiation. The UV-exposed regions of the protective photoresist layer and the top patterning photoresist layer are then removed by solution development, thereby eliminating the need for an oxygen plasma etch and strip and chances for damaging the surface of the substrate or coatings.

  13. Masks of the Universe

    NASA Astrophysics Data System (ADS)

    Harrison, Edward

    2003-05-01

    Preface; Introducing the masks; Part I. Worlds in the Making: 1. The magic Universe; 2. The mythic Universe; 3. The geometric Universe; 4. The medieval Universe; 5. The infinite Universe; 6. The mechanistic Universe; Part II. The Heart Divine: 7. Dance of the atoms and waves; 8. Fabric of space and time; 9. Nearer to the heart's desire; 10. The cosmic tide; 11. Do dreams ever come true?; Part III. The Cloud of Unknowing: 12. The witch universe; 13. The spear of Archytas; 14. All that is made; 15. The cloud of unknowing; 16. Learned ignorance.

  14. Cavitation in flowing superfluid helium

    NASA Technical Reports Server (NTRS)

    Daney, D. E.

    1988-01-01

    Flowing superfluid helium cavitates much more readily than normal liquid helium, and there is a marked difference in the cavitation behavior of the two fluids as the lambda point is traversed. Examples of cavitation in a turbine meter and centrifugal pump are given, together with measurements of the cavitation strength of flowing superfluid helium. The unusual cavitation behavior of superfluid helium is attributed to its immense thermal conductivity .

  15. Trends in mask data preparation

    NASA Astrophysics Data System (ADS)

    Fujimura, Aki; Pang, Liyong; Su, Bo; Choi, Yohan

    2014-10-01

    Whether for VSB mask writing or for multibeam mask writing, the shapes we need to write on masks are increasingly complex, increasingly curvilinear, and smaller in minimum width and space. The overwhelming trend in mask data preparation (MDP) is the shift from deterministic, rule-based, geometric, context-independent, shape-modulated, rectangular processing to statistical, simulation-based, context-dependent, dose- and shape-modulated any-shape processing. The paper briefly surveys the history of MDP, and explains through a simulation-based study that 50nm line and space is the tipping point where rule-based processing gives away to simulation-based processing.

  16. A Masked Photocathode in Photoinjector

    SciTech Connect

    Qiang, Ji

    2010-12-14

    In this paper, we propose a masked photocathode inside the photoinjector for generating high brightness election beam. Instead of mounting the photocathode onto an electrode, an electrode with small hole is used as a mask to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material easy by rotating the photocathode behind the electrode into the hole. Furthermore, this helps reduce the dark current or secondary electron emission from the photocathode material. The masked photocathode also provides transverse cut-off to a Gaussian laser beam that reduces electron beam emittance growth from nonlinear space-charge effects.

  17. Masked hypertension: a systematic review.

    PubMed

    Bobrie, Guillaume; Clerson, Pierre; Ménard, Joël; Postel-Vinay, Nicolas; Chatellier, Gilles; Plouin, Pierre-François

    2008-09-01

    The purpose of this research was to review the literature on masked hypertension. Studies, reviews and editorials on masked hypertension were identified by PubMed, Pascal BioMed and Cochrane literature systematic searches. Then, we carried out a meta-analysis of the six cohort studies reporting quantitative data for masked hypertension prognosis. There is still no clear consensus definition of masked hypertension and the reproducibility of the phenomenon is unknown. Nevertheless, the prevalence of masked hypertension seems to lie between 8 and 20%, and can be up to 50% in treated hypertensive patients. Subjects with masked hypertension have a higher risk of cardiovascular accidents [hazard ratios: 1.92 (1.51-2.44)] than normotensive subjects. This is due to a possible failure to recognize and appropriately manage this particular form of hypertension, the frequent association with other risk factors and coexisting target organ damage. The remaining unresolved questions are as follows: is masked hypertension a clinical entity that requires identification and characterization or a statistical phenomenon linked to the variability of blood pressure measurements?; because screening of the entire population is not feasible, how to identify individuals with masked hypertension?; and, in the absence of randomized trial, how to treat masked hypertension?

  18. Akathisia masked by hypokinesia.

    PubMed

    Tuisku, K; Lauerma, H; Holi, M M; Honkonen, T; Rimon, R

    2000-07-01

    Here, we will discuss the concept of subjective akathisia and present a patient case. Our patient was suffering from neuroleptic-induced hypokinesia and akathisia at the same time. The typical motor manifestations of akathisia were masked by hypokinesia, which made the diagnosis difficult. However, the subjective symptoms of akathisia were evident and distressing. Although not observable to bare eye, the pathognomonic pattern of motor activity detected in akathisia was demonstrated by actometric recording. Changing the conventional neuroleptic to an atypical one brought relief to the subjective symptoms of akathisia and hypokinesia, while the motor activity was clearly diminished in actometric recording. Actometric recording may be useful in diagnosing akathisia masked by hypokinesia, but the typical subjective symptoms of akathisia should not be ignored, even when actometry is not available to demonstrate the missing motor component of akathisia. Not only akathisia defined by DSM-IV but also subjective akathisia should be adequately treated to relieve the subjective distress, and to diminish the unfavorable effects on psychotic symptoms, behavior, and drug compliance.

  19. A NRA study of temperature and heavy ion irradiation effects on helium migration in sintered uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Garcia, P.; Labrim, H.; Sauvage, T.; Carlot, G.; Desgardin, P.; Barthe, M. F.; Piron, J. P.

    2006-10-01

    Helium implanted uranium dioxide sintered samples were studied using nuclear reaction analysis prior to and following heavy ion irradiations and temperature anneals at 800 °C and 1100 °C. The results show that the heavy ion irradiations do not produce measurable long range movement of helium atoms. However, the ion irradiations do affect the behaviour of helium during subsequent temperature anneals. As regards the 800 °C anneal, the reduced mobility of helium in the ion-irradiated samples is interpreted as resulting from enhanced helium atom segregation produced by the ion-irradiation. Conversely at 1100 °C, the initial heavy ion irradiation appears to produce a greater than expected movement of helium within the bulk of the sample which could be an indication of defect assisted helium diffusion. Thermal diffusion coefficients are also reported at 800 °C and 1100 °C based on an analysis using a one-dimensional diffusion model.

  20. SEMATECH EUVL mask program status

    NASA Astrophysics Data System (ADS)

    Yun, Henry; Goodwin, Frank; Huh, Sungmin; Orvek, Kevin; Cha, Brian; Rastegar, Abbas; Kearney, Patrick

    2009-04-01

    As we approach the 22nm half-pitch (hp) technology node, the industry is rapidly running out of patterning options. Of the several lithography techniques highlighted in the International Technology Roadmap for Semiconductors (ITRS), the leading contender for the 22nm hp insertion is extreme ultraviolet lithography (EUVL). Despite recent advances with EUV resist and improvements in source power, achieving defect free EUV mask blank and enabling the EUV mask infrastructure still remain critical issues. To meet the desired EUV high volume manufacturing (HVM) insertion target date of 2013, these obstacles must be resolved on a timely bases. Many of the EUV mask related challenges remain in the pre-competitive stage and a collaborative industry based consortia, such as SEMATECH can play an important role to enable the EUVL landscape. SEMATECH based in Albany, NY is an international consortium representing several of the largest manufacturers in the semiconductor market. Full members include Intel, Samsung, AMD, IBM, Panasonic, HP, TI, UMC, CNSE (College of Nanoscience and Engineering), and Fuller Road Management. Within the SEMATECH lithography division a major thrust is centered on enabling the EUVL ecosystem from mask development, EUV resist development and addressing EUV manufacturability concerns. An important area of focus for the SEMATECH mask program has been the Mask Blank Development Center (MBDC). At the MBDC key issues in EUV blank development such as defect reduction and inspection capabilities are actively pursued together with research partners, key suppliers and member companies. In addition the mask program continues a successful track record of working with the mask community to manage and fund critical mask tools programs. This paper will highlight recent status of mask projects and longer term strategic direction at the MBDC. It is important that mask technology be ready to support pilot line development HVM by 2013. In several areas progress has been

  1. EUVL alternating phase shift mask

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Yang; Myers, Alan; Shroff, Yashesh; Chandhok, Manish; Zhang, Guojing; Gullikson, Eric; Salmassi, Farhad

    2011-04-01

    Extreme ultra-violet Lithography (EUVL) alternating phase shift mask (APSM) or other optical enhancement techniques are likely needed for 16nm (half pitch) technology generation and beyond. One possible option is the combination of EUVL and APSM. The fabrication of EUVL APSM is more difficult than either the fabrication of an EUVL binary mask or a conventional optical APSM mask. In the case of EUVL APSM, the phase difference in the two regions (0 and 180-degree phase regions) is created by a phase step in the substrate prior to the multilayer (ML) coating. The step height that induces 180-degree phase mismatch in the ML is determined by [λ/(4cosθ)](2m+1), where m are integers (0, 1, 2,...). In this experiment, we targeted for a step height with m=1. The same mask design also contains the standard binary structures so that the comparison between the EUVL APSM and the EUVL binary mask can be performed under the same illumination and wafer process conditions. The EUVL APSM mask was exposed using Nikon's EUV1 scanner in Kumagaya Japan. The wafer level results showed higher dense line resolution for EUVL APSM as compared to that of EUVL binary mask. APSM also showed improved line width roughness (LWR) and depth of focus (DoF) as compared to the best EUVL binary results obtained with C-dipole off-axis illumination (OAI). The wafer CD resolution improvement obtained by APSM in this experiment is partially limited by the resist resolution and the mask phase edge spread during ML deposition. We believe that wafer CD resolution and can further be improved with imaging imbalance compensation mask design and improvements in resist resolution and the phase generation portion of the mask fabrication process. In this paper, we will discuss in detail the mask fabrication process, wafer level data analysis, and our understanding of EUVL APSM related issues.

  2. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  3. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Jabbour Al Maalouf, Elias; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed.

  4. Masked Repetition Priming Using Magnetoencephalography

    ERIC Educational Resources Information Center

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David

    2008-01-01

    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  5. Simplified tooling for spray masking

    NASA Technical Reports Server (NTRS)

    Dinbar, B. J.; Hammons, R. E.

    1978-01-01

    Tooling technique involves positioning tiles within acrylic plastic masking frames that attach magnetically to holding fixture. Plastics are "magnetized" with adhesive mangetic-rubber strips. Technique is simpler and less expensive than conventional methods. L-shaped masks are easily cut and altered.

  6. Defect tolerant transmission lithography mask

    DOEpatents

    Vernon, Stephen P.

    2000-01-01

    A transmission lithography mask that utilizes a transparent substrate or a partially transparent membrane as the active region of the mask. A reflective single layer or multilayer coating is deposited on the membrane surface facing the illumination system. The coating is selectively patterned (removed) to form transmissive (bright) regions. Structural imperfections and defects in the coating have negligible effect on the aerial image of the mask master pattern since the coating is used to reflect radiation out of the entrance pupil of the imaging system. Similarly, structural imperfections in the clear regions of the membrane have little influence on the amplitude or phase of the transmitted electromagnetic fields. Since the mask "discards," rather than absorbs, unwanted radiation, it has reduced optical absorption and reduced thermal loading as compared to conventional designs. For EUV applications, the mask circumvents the phase defect problem, and is independent of the thermal load during exposure.

  7. Auroral helium precipitation.

    NASA Technical Reports Server (NTRS)

    Axford, W. I.; Chivers, H. J. A.; Eberhardt, P.; Geiss, J.; Buehler, F.

    1972-01-01

    Application of the metal foil sampling technique, which has been used to measure helium, neon, and argon fluxes in the solar wind, to the problem of measuring the fluxes of these gases in the auroral primary radiation. Aluminum and platinum foils have been flown into two bright auroras and have been recovered. The foils have been analyzed for helium and neon isotopes with a mass spectrometer; so far only He4 has been detected. In the first flight the precipitating flux of He4 with particle energies above about 1 keV was approximately 1,000,000 per sq cm per sec, and the backscattered flux was smaller by about a factor of 10. In the second flight the aurora was less bright, and the He4 fluxes were lower by a factor of about 2. A rough analysis suggests that the mean energy of the incident particles was greater than 3 keV.

  8. Spatially dependent cluster dynamics modeling of microstructure evolution in low energy helium irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Faney, T.; Wirth, B. D.

    2014-09-01

    In fusion reactors, plasma facing components (PFC) and in particular the divertor will be irradiated with high fluxes of low energy (˜100 eV) helium and hydrogen ions. Tungsten is one of the leading candidate divertor materials for ITER and DEMO fusion reactors. However, the behavior of tungsten under high dose, coupled helium/hydrogen exposure remains to be fully understood. The PFC response and performance changes are intimately related to microstructural changes, such as the formation of point defect clusters, helium and hydrogen bubbles or dislocation loops. Computational materials modeling has been used to investigate the mechanisms controlling microstructural evolution in tungsten following high dose, high temperature helium exposure. The aim of this study is to understand and predict helium implantation, primary defect production and defect diffusion, helium-defect clustering and interactions below a tungsten surface exposed to low energy helium irradiation. The important defects include interstitial clusters, vacancy clusters, helium interstitials and helium-vacancy clusters. We report results from a one-dimensional, spatially dependent cluster dynamics model based on the continuum reaction-diffusion rate theory to describe the evolution in space and time of all these defects. The key parameter inputs to the model (diffusion coefficients, migration and binding energies, initial defect production) are determined from a combination of atomistic materials modeling and available experimental data.

  9. IBA studies of helium mobility in nuclear materials revisited

    NASA Astrophysics Data System (ADS)

    Trocellier, P.; Agarwal, S.; Miro, S.; Vaubaillon, S.; Leprêtre, F.; Serruys, Y.

    2015-12-01

    The aim of this paper is to point out and to discuss some features extracted from the study of helium migration in nuclear materials performed during the last fifteen years using ion beam analysis (IBA) measurements. The first part of this paper is devoted to a brief description of the two main IBA methods used, i.e. deuteron induced nuclear reaction for 3He depth profiling and high-energy heavy-ion induced elastic recoil detection analysis for 4He measurement. In the second part, we provide an overview of the different studies carried out on model nuclear waste matrices and model nuclear reactor structure materials in order to illustrate and discuss specific results in terms of key influence parameters in relation with thermal or radiation activated migration of helium. Finally, we show that among the key parameters we have investigated as able to influence the height of the helium migration barrier, the following can be considered as pertinent: the experimental conditions used to introduce helium (implanted ion energy and implantation fluence), the grain size of the matrix, the lattice cell volume, the Young's modulus, the ionicity degree of the chemical bond between the transition metal atom M and the non-metal atom X, and the width of the band gap.

  10. Effect of using stencil masks made by focused ion beam milling on permalloy (Ni81Fe19) nanostructures.

    PubMed

    Bates, J R; Miyahara, Y; Burgess, J A J; Iglesias-Freire, O; Grütter, P

    2013-03-22

    Focused ion beam (FIB) milling is a common fabrication technique to make nanostencil masks which has the unintended consequence of gallium ion implantation surrounding milled features in silicon nitride membranes. We observe major changes in film structure, chemical composition, and magnetic behaviour of permalloy nanostructures deposited by electron beam evaporation using silicon nitride stencil masks made by a FIB as compared to stencil masks made by regular lithography techniques. We characterize the stenciled structures and both types of masks using transmission electron microscopy, electron energy loss spectroscopy, energy dispersive x-ray spectroscopy, magnetic force microscopy and kelvin probe force microscopy. All these techniques demonstrate distinct differences at a length scale of a 1-100 nm for the structures made using stencil mask fabricated using a FIB. The origin of these differences seems to be related to the presence of implanted ions, a detailed understanding of the mechanism however remains to be developed.

  11. Helium irradiation effects in single crystals of MgAl 2O 4

    NASA Astrophysics Data System (ADS)

    Neeft, E. A. C.; Schram, R. P. C.; van Veen, A.; Labohm, F.; Fedorov, A. V.

    2000-05-01

    Magnesium aluminate spinel, (MgAl2O4), is a promising material as a uranium free matrix for the transmutation of americium. Fission products and α-particles are produced during the transmutation. The impact of α-particles is simulated by 30 keV 3He ion implantations at room temperature (RT) with the doses 6.2, 16, 20 and 53×1015 cm-2. In another set of experiments a single crystal MgAl2O4 (1 0 0) sample is irradiated with α-particles (4.5 MeV) from a 241Am source at RT to a dose of 1.3×1012 cm-2. Helium release from the implanted samples was studied by thermal desorption spectrometry (TDS). The numerical analysis of the experimental thermal desorption results of α-implanted samples to a very low helium concentration (0.0288 appm in the irradiation zone of 12.4 μm) show that helium release is dominated by helium interstitial diffusion with an activation energy of 1.8 eV. In the case of high dose implantation to 1.74 at.% in the implantation zone approximately of 100 nm, helium is released from He-vacancy clusters with the activation energy of 2.35 eV. The evolution of the helium concentration profile in the temperature range from RT to 1483 K is monitored by neutron depth profiling (NDP). It confirms that the release of helium is governed by dissociation from vacancy clusters.

  12. Applications of Groundwater Helium

    USGS Publications Warehouse

    Kulongoski, Justin T.; Hilton, David R.

    2011-01-01

    Helium abundance and isotope variations have widespread application in groundwater-related studies. This stems from the inert nature of this noble gas and the fact that its two isotopes ? helium-3 and helium-4 ? have distinct origins and vary widely in different terrestrial reservoirs. These attributes allow He concentrations and 3He/4He isotope ratios to be used to recognize and quantify the influence of a number of potential contributors to the total He budget of a groundwater sample. These are atmospheric components, such as air-equilibrated and air-entrained He, as well as terrigenic components, including in situ (aquifer) He, deep crustal and/or mantle He and tritiogenic 3He. Each of these components can be exploited to reveal information on a number of topics, from groundwater chronology, through degassing of the Earth?s crust to the role of faults in the transfer of mantle-derived volatiles to the surface. In this review, we present a guide to how groundwater He is collected from aquifer systems and quantitatively measured in the laboratory. We then illustrate the approach of resolving the measured He characteristics into its component structures using assumptions of endmember compositions. This is followed by a discussion of the application of groundwater He to the types of topics mentioned above using case studies from aquifers in California and Australia. Finally, we present possible future research directions involving dissolved He in groundwater.

  13. Education in Helium Refrigeration

    NASA Astrophysics Data System (ADS)

    Gistau Baguer, G. M.

    2004-06-01

    On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics… and so on. Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity.

  14. Education in Helium Refrigeration

    SciTech Connect

    Gistau Baguer, G. M.

    2004-06-23

    On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics... and so on.Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity.

  15. Helium behavior in α-SiC ceramics investigated by NRA technique

    NASA Astrophysics Data System (ADS)

    Sauvage, T.; Carlot, G.; Martin, G.; Vincent, L.; Garcia, P.; Barthe, M. F.; Gentils, A.; Desgardin, P.

    2007-04-01

    The mechanisms involved in helium migration in α-SiC are investigated through the evolution of its microstructure and of the concentration profiles following annealing at 1300 °C/30 min for fluences of 1 and 5 × 1015 3He cm-2 and a He implantation energy of 500 keV. Helium profiling is performed using the 3He(d,α)1H NRA technique with an improved detection limit of 5 at ppm. The NRA and TEM techniques clearly show that depending on the initial fluence, a proportion of the helium is trapped within the grain and a part of the helium is released. Analysis of the helium profile changes after annealing enabled to determine a value of the volume diffusion coefficient close to (8 ± 1) × 10-17 m2 s-1 for both fluences studied.

  16. Sensitivity of coded mask telescopes

    SciTech Connect

    Skinner, Gerald K

    2008-05-20

    Simple formulas are often used to estimate the sensitivity of coded mask x-ray or gamma-ray telescopes, but these are strictly applicable only if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask, or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given that allows the calculation of the sensitivity. We consider certain aspects of the optimization of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

  17. Biological Activity of Masked Endotoxin

    PubMed Central

    Schwarz, Harald; Gornicec, Jan; Neuper, Theresa; Parigiani, Maria Alejandra; Wallner, Michael; Duschl, Albert; Horejs-Hoeck, Jutta

    2017-01-01

    Low endotoxin recovery (LER) is a recently discovered phenomenon describing the inability of limulus amebocyte lysate (LAL)-based assays to detect lipopolysaccharide (LPS) because of a “masking effect” caused by chelators or detergents commonly used in buffer formulations for medical products and recombinant proteins. This study investigates the masking capacities of different buffer formulations and whether masked endotoxin is biologically active. We show that both naturally occurring endotoxin as well as control standard endotoxin can be affected by LER. Furthermore, whereas masked endotoxin cannot be detected in Factor C based assays, it is still detectable in a cell-based TLR4-NF-κB-luciferase reporter gene assay. Moreover, in primary human monocytes, masked LPS induces the expression of pro-inflammatory cytokines and surface activation markers even at very low concentrations. We therefore conclude that masked LPS is a potent trigger of immune responses, which emphasizes the potential danger of masked LPS, as it may pose a health threat in pharmaceutical products or compromise experimental results. PMID:28317862

  18. Sensitivity of coded mask telescopes.

    PubMed

    Skinner, Gerald K

    2008-05-20

    Simple formulas are often used to estimate the sensitivity of coded mask x-ray or gamma-ray telescopes, but these are strictly applicable only if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask, or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given that allows the calculation of the sensitivity. We consider certain aspects of the optimization of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

  19. Helium retention and surface blistering characteristics of tungsten with regard to first wall conditions in an inertial fusion energy reactor

    NASA Astrophysics Data System (ADS)

    Gilliam, S. B.; Gidcumb, S. M.; Forsythe, D.; Parikh, N. R.; Hunn, J. D.; Snead, L. L.; Lamaze, G. P.

    2005-12-01

    The first wall of an inertial fusion energy reactor may suffer from surface blistering and exfoliation due to helium ion fluxes and extreme temperatures. Tungsten is a candidate for the first wall material. A study of helium retention and surface blistering with regard to helium dose, temperature and tungsten microstructure was conducted to learn how the damaging effects of helium may be diminished. Single crystal and polycrystalline tungsten samples were implanted with 1.3 MeV 3He in doses ranging from 1019/m2 to 1022/m2. Implanted samples were analyzed by 3He(d, p)4He nuclear reaction analysis and neutron depth profiling techniques. Surface blistering occurred for doses greater than 1021 He/m2 and was analyzed by scanning electron microscopy. Repeated cycles of implantation and flash annealing indicated that helium retention was reduced with decreasing implant dose per cycle. A carbon foil energy degrader, currently in development, will allow a continuous spectrum of helium implantation energy matching the theoretical models of He ion fluxes within the IFE reactor.

  20. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Maalouf, Elias Jabbour Al; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  1. The winter helium bulge revisited

    NASA Astrophysics Data System (ADS)

    Liu, Xianjing; Wang, Wenbin; Thayer, Jeffrey P.; Burns, Alan; Sutton, Eric; Solomon, Stanley C.; Qian, Liying; Lucas, Greg

    2014-10-01

    A newly implemented helium module in the National Center for Atmospheric Research-Thermosphere Ionosphere Electrodynamics general circulation model offers the first opportunity in three decades to describe helium behavior in the context of a first principles, self-consistent model and to test early theories of wintertime helium bulge formation. This study shows general agreement with the findings of Reber and Hays (1973) but articulates the definitive role of vertical advection in the bulge formation. Our findings indicate vertical advection and molecular diffusion are the dominate processes responsible for the solstice helium distribution. Horizontal winds indirectly contribute to the helium bulge formation by their divergent wind field that leads to vertical winds in order to maintain thermosphere mass continuity. As a minor gas, thermospheric helium does not contribute to mass continuity and its distribution is dictated by more local interactions and constraints.

  2. Hg-Mask Coronagraph

    NASA Astrophysics Data System (ADS)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  3. Mechanical alignment of substrates to a mask

    SciTech Connect

    Webb, Aaron P.; Carlson, Charles T.; Honan, Michael; Amato, Luigi G.; Grant, Christopher Neil; Strassner, James D.

    2016-11-08

    A plurality of masks is attached to the underside of a mask frame. This attachment is made such that each mask can independently move relative to the mask frame in three directions. This relative movement allows each mask to adjust its position to align with respective alignment pins disposed on a working surface. In one embodiment, each mask is attached to the mask frame using fasteners, where the fasteners have a shaft with a diameter smaller than the diameter of the mounting hole disposed on the mask. A bias element may be used to allow relative movement between the mask and the mask frame in the vertical direction. Each mask may also have kinematic features to mate with the respective alignment pins on the working surface.

  4. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  5. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  6. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  7. Helium jet dispersion to atmosphere

    NASA Astrophysics Data System (ADS)

    Khan, Hasna J.

    On the event of loss of vacuum guard of superinsulated helium dewar, high rate of heat transfer into the tank occurs. The rapid boiling of liquid helium causes the burst disk to rupture at four atmospheres and consequently the helium passes to the atmosphere through vent lines. The gaseous helium forms a vertical buoyant jet as it exits the vent line into a stagnant environment. Characterization of the gaseous jet is achieved by detailed analysis of the axial and radial dependence of the flow parameters.

  8. Observation of a helium ion energy threshold for retention in tungsten exposed to hydrogen/helium mixture plasma

    NASA Astrophysics Data System (ADS)

    Thompson, M.; Deslandes, A.; Morgan, T. W.; Elliman, R. G.; De Temmerman, G.; Kluth, P.; Riley, D.; Corr, C. S.

    2016-10-01

    Helium retention is measured in tungsten samples exposed to mixed H/He plasma in the Magnum-PSI linear plasma device. It is observed that there is very little He retention below helium ion impact energies of 9.0+/- 1.4 eV, indicating the existence of a potential barrier which must be overcome for implantation to occur. The helium retention in samples exposed to plasma at temperatures  >1000 K is strongly correlated with nano-bubble formation measured using grazing incidence small-angle x-ray scattering. The diameters of nano-bubbles were not found to increase with increasing helium concentration, indicating that additional helium must be accommodated by increasing the bubble concentration or an increase in bubble pressure. For some samples pre-irradiation with heavy ions of 2.0 MeV energy is investigated to simulate the effects of neutron damage. It is observed that nano-bubble sizes are comparable between samples pre-irradiated with heavy-ions, and those without heavy-ion pre-irradiation.

  9. Vibrotactile masking through the body.

    PubMed

    D'Amour, Sarah; Harris, Laurence R

    2014-09-01

    Touches on one hand or forearm can affect tactile sensitivity at contralateral locations on the opposite side of the body. These interactions suggest an intimate connection between the two sides of the body. Here, we explore the effect of masking not across the body but through the body by measuring the effect of a masking stimulus on the back on the tactile sensitivity of the corresponding point on the front. Tactile sensitivity was measured on each side of the stomach, while vibrotactile masking stimulation was applied to one side of the front and to points on the back including the point directly behind the test point on the front. Results were compared to sensitivity, while vibrotactile stimulation was applied to a control site on the shoulder. A reduction in sensitivity of about .8 dB was found that required the masking stimulus to be within about 2 cm of the corresponding point on the back.

  10. Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

    DOE PAGES

    Parish, Chad M.; Unocic, Kinga A.; Tan, Lizhen; ...

    2016-10-24

    Here we irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ~50 dpa, ~15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ~8 nm, ~1021 m-3 (CNA), and of ~3 nm, 1023 m-3 (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces inmore » all alloys survived ~50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Finally, among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.« less

  11. Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

    NASA Astrophysics Data System (ADS)

    Parish, C. M.; Unocic, K. A.; Tan, L.; Zinkle, S. J.; Kondo, S.; Snead, L. L.; Hoelzer, D. T.; Katoh, Y.

    2017-01-01

    We irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ∼50 dpa, ∼15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ∼8 nm, ∼1021 m-3 (CNA), and of ∼3 nm, 1023 m-3 (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces in all alloys survived ∼50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.

  12. Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

    SciTech Connect

    Parish, Chad M.; Unocic, Kinga A.; Tan, Lizhen; Zinkle, S. J.; Kondo, Sosuke; Snead, Lance Lewis; Hoelzer, David T.; Katoh, Yutai

    2016-10-24

    Here we irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ~50 dpa, ~15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ~8 nm, ~1021 m-3 (CNA), and of ~3 nm, 1023 m-3 (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces in all alloys survived ~50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Finally, among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.

  13. Thermal decomposition of fullerene nanowhiskers protected by amorphous carbon mask

    PubMed Central

    Guo, Hongxuan; Wang, Chengxiang; Miyazawa, Kun’ichi; Wang, Hongxin; Masuda, Hideki; Fujita, Daisuke

    2016-01-01

    Fullerene nanostructures are well known for their unique morphology, physical and mechanical properties. The thermal stability of fullerene nanostructures, such as their sublimation at high temperature is also very important for studying their structures and applications. In this work, We observed fullerene nanowhiskers (FNWs) in situ with scanning helium ion microscopy (HIM) at elevated temperatures. The FNWs exhibited different stabilities with different thermal histories during the observation. The pristine FNWs were decomposed at the temperatures higher than 300 °C in a vacuum environment. Other FNWs were protected from decomposition with an amorphous carbon (aC) film deposited on the surface. Based on high spacial resolution, aC film with periodic structure was deposited by helium ion beam induced deposition (IBID) on the surface of FNWs. Annealed at the high temperature, the fullerene molecules were selectively sublimated from the FNWs. The periodic structure was formed on the surface of FNWs and observed by HIM. Monte Carlo simulation and Raman characterization proved that the morphology of the FNWs was changed by helium IBID at high temperature. This work provides a new method of fabricating artificial structure on the surface of FNWs with periodic aC film as a mask. PMID:27991498

  14. Thermal decomposition of fullerene nanowhiskers protected by amorphous carbon mask

    NASA Astrophysics Data System (ADS)

    Guo, Hongxuan; Wang, Chengxiang; Miyazawa, Kun’Ichi; Wang, Hongxin; Masuda, Hideki; Fujita, Daisuke

    2016-12-01

    Fullerene nanostructures are well known for their unique morphology, physical and mechanical properties. The thermal stability of fullerene nanostructures, such as their sublimation at high temperature is also very important for studying their structures and applications. In this work, We observed fullerene nanowhiskers (FNWs) in situ with scanning helium ion microscopy (HIM) at elevated temperatures. The FNWs exhibited different stabilities with different thermal histories during the observation. The pristine FNWs were decomposed at the temperatures higher than 300 °C in a vacuum environment. Other FNWs were protected from decomposition with an amorphous carbon (aC) film deposited on the surface. Based on high spacial resolution, aC film with periodic structure was deposited by helium ion beam induced deposition (IBID) on the surface of FNWs. Annealed at the high temperature, the fullerene molecules were selectively sublimated from the FNWs. The periodic structure was formed on the surface of FNWs and observed by HIM. Monte Carlo simulation and Raman characterization proved that the morphology of the FNWs was changed by helium IBID at high temperature. This work provides a new method of fabricating artificial structure on the surface of FNWs with periodic aC film as a mask.

  15. Subdivisions with infinitely supported mask

    NASA Astrophysics Data System (ADS)

    Li, Song; Pan, Yali

    2008-04-01

    In this paper we investigate the convergence of subdivision schemes associated with masks being polynomially decay sequences. Two-scale vector refinement equations are the formwhere the vector of functions [phi]=([phi]1,E..,[phi]r)T is in and is polynomially decay sequence of rxr matrices called refinement mask. Associated with the mask a is a linear operator on given byBy using same methods in [B. Han, R. Q. Jia, Characterization of Riesz bases of wavelets generated from multiresolution analysis, manuscript]; [BE Han, Refinable functions and cascade algorithms in weighted spaces with infinitely supported masks, manuscript]; [R.Q. Jia, Q.T. Jiang, Z.W. Shen, Convergence of cascade algorithms associated with nonhomogeneous refinement equations, Proc. Amer. Math. Soc. 129 (2001) 415-427]; [R.Q. Jia, Convergence of vector subdivision schemes and construction of biorthogonal multiple wavelets, in: Advances in Wavelet, Hong Kong,1997, Springer, Singapore, 1998, pp. 199-227], a characterization of convergence of the sequences in the L2-norm is given, which extends the main results in [R.Q. Jia, S.D. Riemenschneider, D.X. Zhou, Vector subdivision schemes and multiple wavelets, Math. Comp. 67 (1998) 1533-1563] on convergence of the subdivision schemes associated with a finitely supported mask to the case in which mask a is polynomially decay sequence. As an application, we also obtain a characterization of smoothness of solutions of the refinement equation mentioned above for the case r=1.

  16. Visual Masking During Pursuit Eye Movements

    ERIC Educational Resources Information Center

    White, Charles W.

    1976-01-01

    Visual masking occurs when one stimulus interferes with the perception of another stimulus. Investigates which matters more for visual masking--that the target and masking stimuli are flashed on the same part of the retina, or, that the target and mask appear in the same place. (Author/RK)

  17. Rayleigh Scattering by Helium in Stellar Atmospheres

    NASA Astrophysics Data System (ADS)

    Fišák, J.; Kubát, J.; Krtička, J.

    2017-02-01

    We study the influence of Rayleigh scattering by helium on synthetic spectra and stellar atmosphere models. Rayleigh scattering by helium is often neglected in hot star atmosphere models. This approximation is justified by the small population of helium in stars with solar composition (about 10% by number) and lower Rayleigh scattering total cross section of helium with respect to neutral hydrogen. However, for stars with large helium abundances Rayleigh scattering by helium can be a significant opacity source.

  18. Helium dilution refrigeration system

    DOEpatents

    Roach, P.R.; Gray, K.E.

    1988-09-13

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

  19. Helium dilution refrigeration system

    DOEpatents

    Roach, Patrick R.; Gray, Kenneth E.

    1988-01-01

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

  20. Contralateral tactile masking between forearms.

    PubMed

    D'Amour, Sarah; Harris, Laurence R

    2014-03-01

    Masking effects have been demonstrated in which tactile sensitivity is affected when one touch is close to another on the body surface. Such effects are likely a result of local lateral inhibitory circuits that sharpen the spatial tuning of a given tactile receptor. Mutually inhibitory pathways have also been demonstrated between cortical tactile maps of the two halves of the body. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at contralateral locations. Here, we measure the spatial tuning and effect of posture on this contralateral masking effect. Tactile sensitivity was measured on one forearm, while vibrotactile masking stimulation was applied to the opposite arm. Results were compared to sensitivity while vibrotactile stimulation was applied to a control site on the right shoulder. Sensitivity on the forearm was reduced by over 3 dB when the arms were touching and by 0.52 dB when they were held parallel. The masking effect depended on the position of the masking stimulus. Its effectiveness fell off by 1 STD when the stimulus was 29 % of arm length from the corresponding contralateral point. This long-range inhibitory effect in the tactile system suggests a surprisingly intimate relationship between the two sides of the body.

  1. Nanofabrication on unconventional substrates using transferred hard masks

    SciTech Connect

    Li, Luozhou; Bayn, Igal; Lu, Ming; Nam, Chang -Yong; Schroder, Tim; Stein, Aaron; Harris, Nicholas C.; Englund, Dirk

    2015-01-15

    Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantation are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.

  2. Dental Implants.

    PubMed

    Zohrabian, Vahe M; Sonick, Michael; Hwang, Debby; Abrahams, James J

    2015-10-01

    Dental implants restore function to near normal in partially or completely edentulous patients. A root-form implant is the most frequently used type of dental implant today. The basis for dental implants is osseointegration, in which osteoblasts grow and directly integrate with the surface of titanium posts surgically embedded into the jaw. Radiologic assessment is critical in the preoperative evaluation of the dental implant patient, as the exact height, width, and contour of the alveolar ridge must be determined. Moreover, the precise locations of the maxillary sinuses and mandibular canals, as well as their relationships to the site of implant surgery must be ascertained. As such, radiologists must be familiar with implant design and surgical placement, as well as augmentation procedures utilized in those patients with insufficient bone in the maxilla and mandible to support dental implants.

  3. Cochlear Implants

    MedlinePlus

    ... NIDCD A cochlear implant is a small, complex electronic device that can help to provide a sense ... are better able to hear, comprehend sound and music, and speak than their peers who receive implants ...

  4. Cochlear implant

    MedlinePlus

    ... antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to ... implants allow deaf people to receive and process sounds and speech. However, these devices do not restore ...

  5. Coatings on reflective mask substrates

    SciTech Connect

    Tong, William Man-Wai; Taylor, John S.; Hector, Scott D.; Mangat, Pawitter J. S.; Stivers, Alan R.; Kofron, Patrick G.; Thompson, Matthew A.

    2002-01-01

    A process for creating a mask substrate involving depositing: 1) a coating on one or both sides of a low thermal expansion material EUVL mask substrate to improve defect inspection, surface finishing, and defect levels; and 2) a high dielectric coating, on the backside to facilitate electrostatic chucking and to correct for any bowing caused by the stress imbalance imparted by either other deposited coatings or the multilayer coating of the mask substrate. An film, such as TaSi, may be deposited on the front side and/or back of the low thermal expansion material before the material coating to balance the stress. The low thermal expansion material with a silicon overlayer and a silicon and/or other conductive underlayer enables improved defect inspection and stress balancing.

  6. Precision spectroscopy of Helium

    SciTech Connect

    Cancio, P.; Giusfredi, G.; Mazzotti, D.; De Natale, P.; De Mauro, C.; Krachmalnicoff, V.; Inguscio, M.

    2005-05-05

    Accurate Quantum-Electrodynamics (QED) tests of the simplest bound three body atomic system are performed by precise laser spectroscopic measurements in atomic Helium. In this paper, we present a review of measurements between triplet states at 1083 nm (23S-23P) and at 389 nm (23S-33P). In 4He, such data have been used to measure the fine structure of the triplet P levels and, then, to determine the fine structure constant when compared with equally accurate theoretical calculations. Moreover, the absolute frequencies of the optical transitions have been used for Lamb-shift determinations of the levels involved with unprecedented accuracy. Finally, determination of the He isotopes nuclear structure and, in particular, a measurement of the nuclear charge radius, are performed by using hyperfine structure and isotope-shift measurements.

  7. Helium release in uranium dioxide in relation to grain boundaries and free surfaces

    NASA Astrophysics Data System (ADS)

    Martin, G.; Garcia, P.; Sabathier, C.; Carlot, G.; Sauvage, T.; Desgardin, P.; Raepsaet, C.; Khodja, H.

    2010-06-01

    Nuclear reaction analyses (NRA) based on the 3He( 2H, 4He) 1H reaction were previously performed to follow the evolution of implanted 3He in polycrystalline UO 2 samples. Experimental results pointed to an enhancement above 800 °C of the diffusion coefficient of helium over several microns in the vicinity of the grain boundaries, with respect to the diffusion coefficient within the grain. This was ascribed to the fact that grain boundaries are probably defect sinks which locally modify the defect concentrations. This study aims at demonstrating the particular effect of grain boundaries on helium migration. To this end, 3He implanted polycrystalline UO 2 samples were cracked then annealed at 900 °C. Helium migration in the vicinity of the grain boundaries and near the crack was investigated by means of NRA microanalyses. Helium depletion extends over far larger distances in the vicinity of the grain boundaries than near the crack. Experimental evidence has been collected of the particular effect of grain boundaries on helium migration, which do not act as free surfaces at which helium atoms are simply released.

  8. Informational masking and musical training

    NASA Astrophysics Data System (ADS)

    Oxenham, Andrew J.; Fligor, Brian J.; Mason, Christine R.; Kidd, Gerald

    2003-09-01

    The relationship between musical training and informational masking was studied for 24 young adult listeners with normal hearing. The listeners were divided into two groups based on musical training. In one group, the listeners had little or no musical training; the other group was comprised of highly trained, currently active musicians. The hypothesis was that musicians may be less susceptible to informational masking, which is thought to reflect central, rather than peripheral, limitations on the processing of sound. Masked thresholds were measured in two conditions, similar to those used by Kidd et al. [J. Acoust. Soc. Am. 95, 3475-3480 (1994)]. In both conditions the signal was comprised of a series of repeated tone bursts at 1 kHz. The masker was comprised of a series of multitone bursts, gated with the signal. In one condition the frequencies of the masker were selected randomly for each burst; in the other condition the masker frequencies were selected randomly for the first burst of each interval and then remained constant throughout the interval. The difference in thresholds between the two conditions was taken as a measure of informational masking. Frequency selectivity, using the notched-noise method, was also estimated in the two groups. The results showed no difference in frequency selectivity between the two groups, but showed a large and significant difference in the amount of informational masking between musically trained and untrained listeners. This informational masking task, which requires no knowledge specific to musical training (such as note or interval names) and is generally not susceptible to systematic short- or medium-term training effects, may provide a basis for further studies of analytic listening abilities in different populations.

  9. Production mask composition checking flow

    NASA Astrophysics Data System (ADS)

    Ma, Shou-Yuan; Yang, Chuen-Huei; Tsai, Joe; Wang, Alice; Lin, Roger; Lee, Rachel; Deng, Erwin; Lin, Ling-Chieh; Liao, Hung-Yueh; Tsai, Jenny; Bowhill, Amanda; Vu, Hien; Russell, Gordon

    2016-05-01

    The mask composition checking flow is an evolution of the traditional mask rule check (MRC). In order to differentiate the flow from MRC, we call it Mask Data Correctness Check (MDCC). The mask house does MRC only to identify process limitations including writing, etching, metrology, etc. There still exist many potential errors that could occur when the frame, main circuit and dummies all together form a whole reticle. The MDCC flow combines the design rule check (DRC) and MRC concepts to adapt to the complex patterns in today's wafer production technologies. Although photomask data has unique characteristics, the MRC tool in Calibre® MDP can easily achieve mask composition by using the Extended MEBES job deck (EJB) format. In EJB format, we can customize the combination of any input layers in an IC design layout format, such as OASIS. Calibre MDP provides section-based processing for many standard verification rule format (SVRF) commands that support DRC-like checks on mask data. Integrating DRC-like checking with EJB for layer composition, we actually perform reticle-level DRC, which is the essence of MDCC. The flow also provides an early review environment before the photomask pattern files are available. Furthermore, to incorporate the MDCC in our production flow, runtime is one of the most important indexes we consider. When the MDCC is included in the tape-out flow, the runtime impact is very limited. Calibre, with its multi-threaded processes and good scalability, is the key to achieving acceptable runtime. In this paper, we present real case runtime data for 28nm and 14nm technology nodes, and prove the practicability of placing MDCC into mass production.

  10. Psychometric functions for informational masking

    NASA Astrophysics Data System (ADS)

    Lutfi, Robert A.; Kistler, Doris J.; Callahan, Michael R.; Wightman, Frederic L.

    2003-12-01

    The term informational masking has traditionally been used to refer to elevations in signal threshold resulting from masker uncertainty. In the present study, the method of constant stimuli was used to obtain complete psychometric functions (PFs) from 44 normal-hearing listeners in conditions known to produce varying amounts of informational masking. The listener's task was to detect a pure-tone signal in the presence of a broadband noise masker (low masker uncertainty) and in the presence of multitone maskers with frequencies and amplitudes that varied at random from one presentation to the next (high masker uncertainty). Relative to the broadband noise condition, significant reductions were observed in both the slope and the upper asymptote of the PF for multitone maskers producing large amounts of informational masking. Slope was affected more for some listeners and conditions while asymptote was affected more for others; consequently, neither parameter alone was highly predictive of individual thresholds or the amount of informational masking. Mean slopes and asymptotes varied nonmonotonically with the number of masker components in a manner similar to mean thresholds, particularly when the estimated effect of energetic masking on thresholds was subtracted out. As in past studies, the threshold data were well described by a model in which trial-by-trial judgments are based on a weighted sum of levels in dB at the output of independent auditory filters. The psychometric data, however, complicated the model's interpretation in two ways: First, they suggested that, depending on the listener and condition, the weights can either reflect a fixed influence of masker components on each trial or the effect of occasionally mistaking a masker component for the signal from trial to trial. Second, they indicated that in either case the variance of the underlying decision variable as estimated from PF slope is not by itself great enough to account for the observed changes

  11. Psychometric functions for informational masking

    PubMed Central

    Lutfi, Robert A.; Kistler, Doris J.; Callahan, Michael R.; Wightman, Frederic L.

    2010-01-01

    The term informational masking has traditionally been used to refer to elevations in signal threshold resulting from masker uncertainty. In the present study, the method of constant stimuli was used to obtain complete psychometric functions (PFs) from 44 normal-hearing listeners in conditions known to produce varying amounts of informational masking. The listener’s task was to detect a pure-tone signal in the presence of a broadband noise masker (low masker uncertainty) and in the presence of multitone maskers with frequencies and amplitudes that varied at random from one presentation to the next (high masker uncertainty). Relative to the broadband noise condition, significant reductions were observed in both the slope and the upper asymptote of the PF for multitone maskers producing large amounts of informational masking. Slope was affected more for some listeners and conditions while asymptote was affected more for others; consequently, neither parameter alone was highly predictive of individual thresholds or the amount of informational masking. Mean slopes and asymptotes varied nonmonotonically with the number of masker components in a manner similar to mean thresholds, particularly when the estimated effect of energetic masking on thresholds was subtracted out. As in past studies, the threshold data were well described by a model in which trial-by-trial judgments are based on a weighted sum of levels in dB at the output of independent auditory filters. The psychometric data, however, complicated the model’s interpretation in two ways: First, they suggested that, depending on the listener and condition, the weights can either reflect a fixed influence of masker components on each trial or the effect of occasionally mistaking a masker component for the signal from trial to trial. Second, they indicated that in either case the variance of the underlying decision variable as estimated from PF slope is not by itself great enough to account for the observed

  12. Simulation of Helium-3 Extraction from Lunar Ilmenite

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Kulcinski, G. L.; Schmitt, H. H.

    2004-01-01

    Knowledge of the trapping mechanisms and diffusion characteristics of solar-wind implanted isotopes in the minerals of the lunar regolith will enable the optimization of the processes to extract solar wind gases from regolith particles. Extraction parameters include the temperature and duration of extraction, particle size, and gas yield. Diffusion data will increase the efficiency and profitability of future mining ventures. This data will also assist in optimizing the evaluations of various potential mining sites based on remote sensing data. For instance, if magnesian ilmenite (Mg,Fel.,Ti03) is found to retain He better than stoichiometric ilmenite (FeTi03), remote sensing data for Mg could be considered in addition to Ti and maturity data. The context of the currently discussed work is the mining of helium-3 for potential use as a fuel for fusion energy generation. However, the potential resources deposited by the solar wind include hydrogen (and derived water), helium-4, nitrogen and carbon. Implantation experiments such as those performed for helium isotopes in ilmenite are important for the optimized extraction of these additional resources. These experiments can easily be reproduced for most elements or isotopes of interest.

  13. The man in the mask.

    PubMed

    Zugibe, F T; Costello, J T; Breithaupt, M K

    1987-05-01

    A skeletonized body, wearing a black leather bondage mask, was found in a Revolutionary War smokehouse cave with two bullet holes in the back of the head. The body was skeletonized up to the maxillary area but the head region under the mask was well preserved and permitted a positive visual identification. There was evidence that the body had been eaten by small animals and subsequently burned. Investigations into this brutal murder revealed a tale of a bizarre sadomasochistic ritual that attained national prominence.

  14. Aperture masking interferometry research simulation

    NASA Astrophysics Data System (ADS)

    Wang, Haitao; Luo, Qiufeng; Fan, Weijun; Zhang, Xian Ling; Tao, Chunkan; Zhu, Yongtian; Zhou, Bifang; Chen, Hanliang

    2004-10-01

    Aperture Masking Interferometry (AMI) is one of the high-resolution astronomical image observation technologies. It is also an important research way to the Optical Aperture Synthesis (OAS). The theory of OAS is simply introduced and AMI simulation method is raised. The mathematics model is built and the interferogram fringes are got. The aperture mask u-v coverage is discussed and one image reconstruction method is done. The reconstructed image result is got with CLEAN method. Shortcoming of this work is also referred and the future research work is mentioned at last.

  15. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

    NASA Astrophysics Data System (ADS)

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-01

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90–210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  16. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography.

    PubMed

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-24

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga(+) ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90-210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  17. Resource Letter SH-1: Superfluid Helium.

    ERIC Educational Resources Information Center

    Hallock, Robert B.

    1982-01-01

    Provides an annotated list of books, textbooks, and films on superfluid helium. Also lists research reports/reviews arranged by category, including among others, early history, microscopic understanding, ions in helium, helium in rotation, vortices and quantization, helium films and constricted geometrics, persistence flow, and superfluid helium…

  18. Retention and surface blistering of helium irradiated tungsten as a first wall material

    NASA Astrophysics Data System (ADS)

    Gilliam, S. B.; Gidcumb, S. M.; Parikh, N. R.; Forsythe, D. G.; Patnaik, B. K.; Hunn, J. D.; Snead, L. L.; Lamaze, G. P.

    2005-12-01

    The first wall of an inertial fusion energy reactor may suffer from surface blistering and exfoliation due to helium ion irradiation and extreme temperatures. Tungsten is a candidate for the first wall material. A study of helium retention and surface blistering with regard to helium dose, temperature, pulsed implantation, and tungsten microstructure was conducted to better understand what may occur at the first wall of the reactor. Single crystal and polycrystalline tungsten samples were implanted with 1.3 MeV 3He in doses ranging from 10 19 m -2 to 10 22 m -2. Implanted samples were analyzed by 3He(d,p) 4He nuclear reaction analysis and 3He(n,p)T neutron depth profiling techniques. Surface blistering was observed for doses greater than 10 21 He/m 2. For He fluences of 5 × 10 20 He/m 2, similar retention levels in both microstructures resulted without blistering. Implantation and flash heating in cycles indicated that helium retention was mitigated with decreasing He dose per cycle.

  19. Cost-effective mask-sharing technology for SOI LIGBT and PLDMOS

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Qiao, Ming; Zhou, Xin; Liang, Tao; Li, Yang; Li, Zhaoji; Zhang, Bo

    2016-04-01

    Cost-effective mask-sharing technology for the 200 V silicon-on-insulator (SOI) lateral insulated gate bipolar transistor (LIGBT) and p-channel lateral double-diffused MOS (PLDMOS) are proposed in this paper. N-well and P-body implantations are shared as an N-buffer implantation of the LIGBT and P-buffer implantation of the PLDMOS, respectively, which reduces two masks compared with the conventional process. The structure and process parameters for LIGBT and PLDMOS with the new process are optimized by simulation to achieve good performance. The experimental results indicate that the LIGBT and PLDMOS using the new process maintain the same performance compared to the conventional devices.

  20. The Marine Mask of War

    DTIC Science & Technology

    2011-11-10

    America’s Army. To the Marines, it is teamwork and the subordination of the individual to the common good of the unit. First person pronouns are shunned...As demonstrated over the last decade, this versatility and cost effectiveness is a good deal for the American taxpayer. Having examined the Mask

  1. Imaging With the IBIS Mask

    NASA Astrophysics Data System (ADS)

    Berná, J. A.; Torrejón, J. M.; Bernabeu, G.

    2001-03-01

    We present very preliminary results on the imaging capabilities of the IBIS instrument, the gamma ray imager on board ESA's INTEGRAL satellite, regarding the coded mask subsystem. For this purpose we perform a simulation of a pointed observation to the Galactic Centre region and investigate the detection of the most prominent sources.

  2. Masked Hypertension in Diabetes Mellitus

    PubMed Central

    Franklin, Stanley S.; Thijs, Lutgarde; Li, Yan; Hansen, Tine W.; Boggia, José; Liu, Yanping; Asayama, Kei; Björklund-Bodegård, Kristina; Ohkubo, Takayoshi; Jeppesen, Jørgen; Torp-Pedersen, Christian; Dolan, Eamon; Kuznetsova, Tatiana; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Malyutina, Sofia; Casiglia, Edoardo; Nikitin, Yuri; Lind, Lars; Sandoya, Edgardo; Kawecka-Jaszcz, Kalina; Filipovský, Jan; Imai, Yutaka; Wang, Jiguang; Ibsen, Hans; O’Brien, Eoin; Staessen, Jan A.

    2013-01-01

    Although distinguishing features of masked hypertension in diabetics are well known, the significance of antihypertensive treatment on clinical practice decisions has not been fully explored. We analyzed 9691 subjects from the population-based 11-country International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes. Prevalence of masked hypertension in untreated normotensive participants was higher (P<0.0001) among 229 diabetics (29.3%, n=67) than among 5486 nondiabetics (18.8%, n=1031). Over a median of 11.0 years of follow-up, the adjusted risk for a composite cardiovascular end point in untreated diabetic-masked hypertensives tended to be higher than in normotensives (hazard rate [HR], 1.96; 95% confidence interval [CI], 0.97–3.97; P=0.059), similar to untreated stage 1 hypertensives (HR, 1.07; CI, 0.58–1.98; P=0.82), but less than stage 2 hypertensives (HR, 0.53; CI, 0.29–0.99; P=0.048). In contrast, cardiovascular risk was not significantly different in antihypertensive-treated diabetic-masked hypertensives, as compared with the normotensive comparator group (HR, 1.13; CI, 0.54–2.35; P=0.75), stage 1 hypertensives (HR, 0.91; CI, 0.49–1.69; P=0.76), and stage 2 hypertensives (HR, 0.65; CI, 0.35–1.20; P=0.17). In the untreated diabetic-masked hypertensive population, mean conventional systolic/diastolic blood pressure was 129.2±8.0/76.0±7.3 mm Hg, and mean daytime systolic/diastolic blood pressure 141.5±9.1/83.7±6.5 mm Hg. In conclusion, masked hypertension occurred in 29% of untreated diabetics, had comparable cardiovascular risk as stage 1 hypertension, and would require considerable reduction in conventional blood pressure to reach daytime ambulatory treatment goal. Importantly, many hypertensive diabetics when receiving antihypertensive therapy can present with normalized conventional and elevated ambulatory blood pressure that mimics masked hypertension. PMID:23478096

  3. "The Mask Who Wasn't There": Visual Masking Effect with the Perceptual Absence of the Mask

    ERIC Educational Resources Information Center

    Rey, Amandine Eve; Riou, Benoit; Muller, Dominique; Dabic, Stéphanie; Versace, Rémy

    2015-01-01

    Does a visual mask need to be perceptually present to disrupt processing? In the present research, we proposed to explore the link between perceptual and memory mechanisms by demonstrating that a typical sensory phenomenon (visual masking) can be replicated at a memory level. Experiment 1 highlighted an interference effect of a visual mask on the…

  4. Helium-ion-induced release of hydrogen from graphite

    SciTech Connect

    Langley, R.A.

    1987-01-01

    The ion-induced release of hydrogen from AXF-5Q graphite was studied for 350-eV helium ions. The hydrogen was implanted into the graphite with a low energy (approx.200 eV) and to a high fluence. This achieved a thin (approx.10-nm), saturated near-surface region. The release of hydrogen was measured as a function of helium fluence. A model that includes ion-induced detrapping, retrapping, and surface recombination was used to analyze the experimental data. A value of (1.65 +- 0.2) x 10/sup -16/ cm/sup 2/ was obtained from the detrapping cross section, and a value of (0.5 to 4) x 10/sup -14/ cm/sup 4//atoms was obtained for the recombination coefficient. 11 refs., 4 figs.

  5. Liquid Helium 3 and Solid Helium at Yale and Beyond

    NASA Astrophysics Data System (ADS)

    Lee, D. M.

    2006-03-01

    Many of the foundations of low temperature physics in the latter half of the twentieth century were built at Yale University under the leadership of Professor Cecil T. Lane who came to Yale in 1932 and Henry A. Fairbank who obtained his Ph.D. at Yale in 1944 under Lane's guidance. This discussion will mainly treat the contributions of Henry Fairbank and his students during the period between 1954 and 1963, when Henry Fairbank left Yale to become chairman of the Physics Dept. at Duke University. Following World War II small amounts of helium three became available to low temperature experimenters. Henry Fairbank’s graduate students were provided with the opportunity to investigate second sound in dilute and later concentrated mixtures of helium three in superfluid helium four. These measurements showed strong effects of the phase separation in helium 3 - helium 4 mixtures previously discovered in the laboratory of William Fairbank (a student of Lane and a brother of Henry Fairbank). As more helium three became available, studies of pure helium three were performed, including measurements of the thermal conductivity, the density and the specific heat. Early evidence for the melting curve minimum was found. The main emphasis in this work was to search for Fermi liquid behavior. Much of the later work in this area was performed by the group of John Wheatley at the University of Illinois. In studies of solid helium four at Yale, a surprising observation was made. Hitherto it had been thought that hcp was the stable phase throughout the low temperature part of the phase diagram. It was found via ultrasound experiments that a small silver of bcc solid existed at the lowest pressures. While this author was a graduate student at Yale, Henry Fairbank pointed out to him the possibility of cooling helium three via adiabatic compression from the liquid into the solid phase. (Pomeranchuk Cooling). A brief discussion is given of the use of this technique in the discovery of

  6. Interactions of mobile helium clusters with surfaces and grain boundaries of plasma-exposed tungsten

    NASA Astrophysics Data System (ADS)

    Hu, Lin; Hammond, Karl D.; Wirth, Brian D.; Maroudas, Dimitrios

    2014-05-01

    We report results of atomistic computations for the interactions of small mobile helium clusters (Hen) with free surfaces and grain boundaries (GBs) in tungsten toward development of continuum drift-diffusion-reaction models for the dynamics of mobile helium clusters in plasma-exposed tungsten. Molecular-statics (MS) simulations based on reliable many-body interatomic potentials are carried out for Hen (1 ≤ n ≤ 7) clusters near sinks to obtain the potential energy profiles of the Hen clusters as a function of the clusters' center-of-mass distance from a sink. Sinks investigated include surfaces, GBs, and regions in the vicinity of junctions where GBs intersect free surfaces. Elastic interaction potentials based on elastic inclusion theory provide an excellent description of the MS results for the cluster-sink interactions. The key parameter in the elastic models is the sink segregation strength, which is found to increase with increasing cluster size. Such cluster-sink interactions are responsible for the migration of small helium clusters by drift and for helium segregation on surfaces and grain boundaries in tungsten. Such helium segregation on sinks is observed in large-scale molecular-dynamics simulations of helium aggregation in model polycrystalline tungsten at 933 K upon helium implantation.

  7. Interactions of mobile helium clusters with surfaces and grain boundaries of plasma-exposed tungsten

    SciTech Connect

    Hu, Lin; Maroudas, Dimitrios; Hammond, Karl D.; Wirth, Brian D.

    2014-05-07

    We report results of atomistic computations for the interactions of small mobile helium clusters (He{sub n}) with free surfaces and grain boundaries (GBs) in tungsten toward development of continuum drift-diffusion-reaction models for the dynamics of mobile helium clusters in plasma-exposed tungsten. Molecular-statics (MS) simulations based on reliable many-body interatomic potentials are carried out for He{sub n} (1 ≤ n ≤ 7) clusters near sinks to obtain the potential energy profiles of the He{sub n} clusters as a function of the clusters' center-of-mass distance from a sink. Sinks investigated include surfaces, GBs, and regions in the vicinity of junctions where GBs intersect free surfaces. Elastic interaction potentials based on elastic inclusion theory provide an excellent description of the MS results for the cluster-sink interactions. The key parameter in the elastic models is the sink segregation strength, which is found to increase with increasing cluster size. Such cluster-sink interactions are responsible for the migration of small helium clusters by drift and for helium segregation on surfaces and grain boundaries in tungsten. Such helium segregation on sinks is observed in large-scale molecular-dynamics simulations of helium aggregation in model polycrystalline tungsten at 933 K upon helium implantation.

  8. Physiological functioning of the ear and masking

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The physiological functions of the ear and the role masking plays in speech communication are examined. Topics under investigation include sound analysis of the ear, the aural reflex, and various types of noise masking.

  9. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Office's Authorized List of Federal Helium Suppliers available via the Internet at http://www.nm.blm.gov..., insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  10. Influence of displacement damage on deuterium and helium retention in austenitic and ferritic-martensitic alloys considered for ADS service

    NASA Astrophysics Data System (ADS)

    Voyevodin, V. N.; Karpov, S. A.; Kopanets, I. E.; Ruzhytskyi, V. V.; Tolstolutskaya, G. D.; Garner, F. A.

    2016-01-01

    The behavior of ion-implanted hydrogen (deuterium) and helium in austenitic 18Cr10NiTi stainless steel, EI-852 ferritic steel and ferritic/martensitic steel EP-450 and their interaction with displacement damage were investigated. Energetic argon irradiation was used to produce displacement damage and bubble formation to simulate nuclear power environments. The influence of damage morphology and the features of radiation-induced defects on deuterium and helium trapping in structural alloys was studied using ion implantation, the nuclear reaction D(3He,p)4He, thermal desorption spectrometry and transmission electron microscopy. It was found in the case of helium irradiation that various kinds of helium-radiation defect complexes are formed in the implanted layer that lead to a more complicated spectra of thermal desorption. Additional small changes in the helium spectra after irradiation with argon ions to a dose of ≤25 dpa show that the binding energy of helium with these traps is weakly dependent on the displacement damage. It was established that retention of deuterium in ferritic and ferritic-martensitic alloys is three times less than in austenitic steel at damage of ˜1 dpa. The retention of deuterium in steels is strongly enhanced by presence of radiation damages created by argon ion irradiation, with a shift in the hydrogen release temperature interval of 200 K to higher temperature. At elevated temperatures of irradiation the efficiency of deuterium trapping is reduced by two orders of magnitude.

  11. Method for mask repair using defect compensation

    DOEpatents

    Sweeney, Donald W.; Ray-Chaudhuri, Avijit K.

    2001-01-01

    A method for repair of amplitude and/or phase defects in lithographic masks. The method involves modifying or altering a portion of the absorber pattern on the surface of the mask blank proximate to the mask defect to compensate for the local disturbance (amplitude or phase) of the optical field due to the defect.

  12. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  13. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (m)...

  14. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (o)...

  15. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (o)...

  16. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (m)...

  17. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (m)...

  18. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  19. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  20. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  1. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  2. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  3. Object Substitution Masking Induced by Illusory Masks: Evidence for Higher Object-Level Locus of Interference

    ERIC Educational Resources Information Center

    Hirose, Nobuyuki; Osaka, Naoyuki

    2009-01-01

    A briefly presented target can be rendered invisible by a lingering sparse mask that does not even touch it. This form of visual backward masking, called object substitution masking, is thought to occur at the object level of processing. However, it remains unclear whether object-level interference alone produces substitution masking because…

  4. Repair of sublethal and potentially lethal radiation damage by rat embryos exposed to gamma rays or helium lons.

    PubMed

    Ward, W F; Aceto, H; Sandusky, M

    1976-09-01

    Embryonic survival was examined in rats exposed to a 24-hour split-dose regimen of gamma rays or extended-Bragg-peak (EBP) helium ions on the fifth and sixth days of gestation. The data indicate that EBP helium ions, which are known to have a single-dose relative biological effectiveness (RBE) of 1.0, exhibit a split-dose RBE of 1.5 with respect to embryo killing. Using an experimental rat embryo system, delayed implantation, it was also noted that the embryocidal damage induced by EBP helium ions contains a smaller potentially lethal component than that induced by gamma rays.

  5. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications. PMID:27879873

  6. Crystal orientation effects on helium ion depth distributions and adatom formation processes in plasma-facing tungsten

    NASA Astrophysics Data System (ADS)

    Hammond, Karl D.; Wirth, Brian D.

    2014-10-01

    We present atomistic simulations that show the effect of surface orientation on helium depth distributions and surface feature formation as a result of low-energy helium plasma exposure. We find a pronounced effect of surface orientation on the initial depth of implanted helium ions, as well as a difference in reflection and helium retention across different surface orientations. Our results indicate that single helium interstitials are sufficient to induce the formation of adatom/substitutional helium pairs under certain highly corrugated tungsten surfaces, such as {1 1 1}-orientations, leading to the formation of a relatively concentrated layer of immobile helium immediately below the surface. The energies involved for helium-induced adatom formation on {1 1 1} and {2 1 1} surfaces are exoergic for even a single adatom very close to the surface, while {0 0 1} and {0 1 1} surfaces require two or even three helium atoms in a cluster before a substitutional helium cluster and adatom will form with reasonable probability. This phenomenon results in much higher initial helium retention during helium plasma exposure to {1 1 1} and {2 1 1} tungsten surfaces than is observed for {0 0 1} or {0 1 1} surfaces and is much higher than can be attributed to differences in the initial depth distributions alone. The layer thus formed may serve as nucleation sites for further bubble formation and growth or as a source of material embrittlement or fatigue, which may have implications for the formation of tungsten "fuzz" in plasma-facing divertors for magnetic-confinement nuclear fusion reactors and/or the lifetime of such divertors.

  7. Crystal orientation effects on helium ion depth distributions and adatom formation processes in plasma-facing tungsten

    SciTech Connect

    Hammond, Karl D.; Wirth, Brian D.

    2014-10-14

    We present atomistic simulations that show the effect of surface orientation on helium depth distributions and surface feature formation as a result of low-energy helium plasma exposure. We find a pronounced effect of surface orientation on the initial depth of implanted helium ions, as well as a difference in reflection and helium retention across different surface orientations. Our results indicate that single helium interstitials are sufficient to induce the formation of adatom/substitutional helium pairs under certain highly corrugated tungsten surfaces, such as (1 1 1)-orientations, leading to the formation of a relatively concentrated layer of immobile helium immediately below the surface. The energies involved for helium-induced adatom formation on (1 1 1) and (2 1 1) surfaces are exoergic for even a single adatom very close to the surface, while (0 0 1) and (0 1 1) surfaces require two or even three helium atoms in a cluster before a substitutional helium cluster and adatom will form with reasonable probability. This phenomenon results in much higher initial helium retention during helium plasma exposure to (1 1 1) and (2 1 1) tungsten surfaces than is observed for (0 0 1) or (0 1 1) surfaces and is much higher than can be attributed to differences in the initial depth distributions alone. The layer thus formed may serve as nucleation sites for further bubble formation and growth or as a source of material embrittlement or fatigue, which may have implications for the formation of tungsten “fuzz” in plasma-facing divertors for magnetic-confinement nuclear fusion reactors and/or the lifetime of such divertors.

  8. Performance of GFIS mask repair system for various mask materials

    NASA Astrophysics Data System (ADS)

    Aramaki, Fumio; Kozakai, Tomokazu; Matsuda, Osamu; Yasaka, Anto; Yoshikawa, Shingo; Kanno, Koichi; Miyashita, Hiroyuki; Hayashi, Naoya

    2014-10-01

    We have developed a new focused ion beam (FIB) technology using a gas field ion source (GFIS) for mask repair. Meanwhile, since current high-end photomasks do not have high durability in exposure nor cleaning, some new photomask materials are proposed. In 2012, we reported that our GFIS system had repaired a representative new material "A6L2". It is currently expected to extend the application range of GFIS technology for various new materials and various defect shapes. In this study, we repaired a single bridge, a triple bridge and a missing hole on a phase shift mask (PSM) of "A6L2", and also repaired single bridges on a binary mask of molybdenum silicide (MoSi) material "W4G" and a PSM of high transmittance material "SDC1". The etching selectivity between those new materials and quartz were over 4:1. There were no significant differences of pattern shapes on scanning electron microscopy (SEM) images between repair and non-repair regions. All the critical dimensions (CD) at repair regions were less than +/-3% of those at normal ones on an aerial image metrology system (AIMS). Those results demonstrated that GFIS technology is a reliable solution of repairing new material photomasks that are candidates for 1X nm generation.

  9. Endodontic implants

    PubMed Central

    Yadav, Rakesh K.; Tikku, A. P.; Chandra, Anil; Wadhwani, K. K.; Ashutosh kr; Singh, Mayank

    2014-01-01

    Endodontic implants were introduced back in 1960. Endodontic implants enjoyed few successes and many failures. Various reasons for failures include improper case selection, improper use of materials and sealers and poor preparation for implants. Proper case selection had given remarkable long-term success. Two different cases are being presented here, which have been treated successfully with endodontic implants and mineral trioxide aggregate Fillapex (Andreaus, Brazil), an MTA based sealer. We suggest that carefully selected cases can give a higher success rate and this method should be considered as one of the treatment modalities. PMID:25298723

  10. Through-mask anodization of titania dot- and pillar-like nanostructures on bulk Ti substrates using a nanoporous anodic alumina mask.

    PubMed

    Sjöström, Terje; Fox, Neil; Su, Bo

    2009-04-01

    Nanosized surface topography on an implant material has the capability of stimulating the acceptance of the material in its host surrounding. Fine-tuning of nanotopography feature size has been shown to trigger differentiation of mesenchymal stem cells into bone cells in vitro. For this purpose we have created well defined nanosized titania dot- and pillar-like structures on mechanically polished Ti substrates using a through-mask anodization technique with an anodic porous alumina template. The anodization technique allowed the titania structure dimensions to be precisely tuned in the range 15-140 nm in a single electrolyte system. The fabricated surfaces serve as good model surfaces for precise studies of in vitro cell behaviour. The through-mask anodization technique was used directly on bulk Ti surfaces, thus demonstrating a potential application for patterning of actual Ti implant surfaces.

  11. Improving vision by pupil masking

    PubMed Central

    Bonaque-González, Sergio; Ríos-Rodríguez, Susana; López-Gil, Norberto

    2016-01-01

    We propose an alternative solution to improve visual quality by spatially modulating the amplitude of light passing into the eye (related to the eye's transmittance), in contrast to traditional correction of the wavefront phase (related to the local refractive power). Numerical simulations show that masking the aberrated areas at the pupil plane should enhance visual function, especially in highly aberrated eyes. This correction could be implemented in practice using customized contact or intraocular lenses. PMID:27446688

  12. Mask pattern generator employing EPL technology

    NASA Astrophysics Data System (ADS)

    Yoshioka, Nobuyuki; Yamabe, Masaki; Wakamiya, Wataru; Endo, Nobuhiro

    2003-08-01

    Mask cost is one of crucial issues in device fabrication, especially in SoC (System on a Chip) with small-volume production. The cost mainly depends on productivity of mask manufacturing tools such as mask writers and defect inspection tools. EPL (Electron Projection Lithography) has been developing as a high-throughput electron beam exposure technology that will succeed optical lithography. The application of EPL technology to mask writing will result in high productivity and contribute to decrease the mask cost. The concept of a mask pattern generator employing EPL technology is proposed in this paper. It is very similar to EPL technology used for pattern printing on a wafer. The mask patterns on the glass substrate are exposed by projecting the basic circuit patterns formed on the mother EPL mask. One example of the mother EPL mask is a stencil type made with 200-mm Si wafer. The basic circuit patterns are IP patterns and logical primitive patterns such as cell libraries (AND, OR, Inverter, Flip-Flop and etc.) to express the SoC device patterns. Since the SoC patterns are exposed with its collective units such as IP and logical primitive patterns by using this method, the high throughput will be expected comparing with conventional mask E-beam writers. In this paper, the mask pattern generator with the EPL technology is proposed. The concept, its advantages and issues to be solved are discussed.

  13. Design and development of a helium injection system to improve external leakage detection during liquid nitrogen immersion tests

    NASA Astrophysics Data System (ADS)

    Townsend, Andrew; Mishra, Rakesh

    2016-10-01

    The testing of assemblies for use in cryogenic systems commonly includes evaluation at or near operating (therefore cryogenic) temperature. Typical assemblies include valves and pumps for use in liquid oxygen-liquid hydrogen rocket engines. One frequently specified method of cryogenic external leakage testing requires the assembly, pressurized with gaseous helium (GHe), be immersed in a bath of liquid nitrogen (LN2) and allowed to thermally stabilize. Component interfaces are then visually inspected for leakage (bubbles). Unfortunately the liquid nitrogen will be boiling under normal, bench-top, test conditions. This boiling tends to mask even significant leakage. One little known and perhaps under-utilized property of helium is the seemingly counter-intuitive thermodynamic property that when ambient temperature helium is bubbled through boiling LN2 at a temperature of -195.8 °C, the temperature of the liquid nitrogen will reduce. This paper reports on the design and testing of a novel proof-of-concept helium injection control system confirming that it is possible to reduce the temperature of an LN2 bath below boiling point through the controlled injection of ambient temperature gaseous helium and then to efficiently maintain a reduced helium flow rate to maintain a stabilized liquid temperature, enabling clear visual observation of components immersed within the LN2. Helium saturation testing is performed and injection system sizing is discussed.

  14. Spatial release from informational masking

    NASA Astrophysics Data System (ADS)

    Rakerd, Brad; Aaronson, Neil L.

    2001-05-01

    A new method for investigating spatial release from informational masking was developed and employed in two experiments. The new method is computer controlled and efficient. It employs the versatile coordinate response measure speech stimulus set [Bolia et al., J. Acoust. Soc. Am. 107, 1065 (2000)]. The experiments were conducted in an anechoic room, with a primary loudspeaker in front of the listener and a secondary loudspeaker at 60 deg to the right. Target messages were presented from the primary speaker only. For a standard, distractor messages, simultaneous with the target, were also presented from the primary speaker only. Spatial release was measured by presenting the distractors from both primary and secondary speakers with a temporal offset. Experiment 1 fixed the offset (secondary leading, +4 ms) and varied the number of distractors (1 to 3) and the target-to-distractor ratio (-12 to +4 dB). Masking release, sometimes as large as 10 dB, was found for all combinations of these variables. Experiment 2 varied the offset over a wide range of values. Substantial release from masking was found for both positive and negative offsets, but only in the range in which speech echoes are suppressed (<50 ms). [Work supported by NIDCD grant DC 00181.

  15. History and future of mask making

    NASA Astrophysics Data System (ADS)

    Levy, Ken L.

    1996-12-01

    The history of the mask industry has three main periods, which I call the Classical Period, the Dark Ages, and the Renaissance, by analogy with those periods in the history of Western Europe. During the Classical Period, people developed 1X masks and the technology to make them. In the Dark Ages, people exploited the equipment developed during the Classical Period to make 5X reduction reticle, ending the nobility of mask making. In today's Renaissance of mask making, a proliferation of mask types is requiring a rebirth of innovation and creativity. The Renaissance resembles the Classical Period: masks are once again strategic, and technological capability is once again the driver. Meanwhile, the mask industry is carrying forward the productivity and efficiency gains it achieved during the Dark Ages. We must create a new business and economic model to support these changes in the characteristics of the marketplace.

  16. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito

    2011-03-01

    Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

  17. Fabrication and commercialization of scalpel masks

    NASA Astrophysics Data System (ADS)

    Novembre, Anthony E.; Peabody, Milton L., Jr.; Blakey, Myrtle I.; Farrow, Reginald C.; Kasica, Richard J.; Liddle, James A.; Saunders, Thomas E.; Tennant, Donald M.

    1998-09-01

    SCALPEL masks have been fabricated for use in the Proof-of- Lithography system and to demonstrate the feasibility of having them produced by a commercial blank manufacturer and optical mask shops. Masks blanks are formed from 100 mm diameter silicon wafers. A 100-150 nm thick SiNx layer is LPCVD deposited onto the wafers followed by magnetron sputter deposition of a thin Cr/W metal layer which is used as the scatterer layer for the mask>the mask is supported by an underlying network of struts which are arranged to be compatible with the step and scan writing strategy of the exposure tool and to provide robustness to the mask. Crystallographic wet etching of the silicon wafer forms membranes and struts. To date over 300 mask blanks have been formed and yield data as a function of the thickness of the silicon nitride membrane has been quantified. Recent developments in the mask blank formation process include the production of blanks by MCNC who serve as a commercial source of SCALPEL mask blanks. They have successfully delivered 36 blanks that exhibit equivalent properties to those produced at Lucent. Mask patterning has been performed at the commercial optical mask shops of PHOTRONICS and DUPONT. In this investigation a MEBES exposure system has been used to write patterns. The resist used is ZEP-520 and development and pattern transfer processes are performed in the STEAG-Hammatech spray/spin processing tool. Metrology is performed using a KMS 310 RT optical microscope. Pattern placement accuracy is measured on the LMS 2020 system without modification. The masks are inspected for defects using the optical based KLA 300 series inspection system in a die to die mode and in transmission. Results to date suggest feasibility of producing SCALPEL masks by a commercial blank supplier and by merchant optical mask shops.

  18. Breast Implants

    MedlinePlus

    ... sale in the United States: saline-filled and silicone gel-filled. Both types have a silicone outer shell. They vary in size, shell thickness, ... implant them. Provide information on saline-filled and silicone gel-filled breast implants, including data supporting a ...

  19. Rogue mantle helium and neon.

    PubMed

    Albarède, Francis

    2008-02-15

    The canonical model of helium isotope geochemistry describes the lower mantle as undegassed, but this view conflicts with evidence of recycled material in the source of ocean island basalts. Because mantle helium is efficiently extracted by magmatic activity, it cannot remain in fertile mantle rocks for long periods of time. Here, I suggest that helium with high 3He/4He ratios, as well as neon rich in the solar component, diffused early in Earth's history from low-melting-point primordial material into residual refractory "reservoir" rocks, such as dunites. The difference in 3He/4He ratios of ocean-island and mid-ocean ridge basalts and the preservation of solar neon are ascribed to the reservoir rocks being stretched and tapped to different extents during melting.

  20. High performance mask fabrication process for the next-generation mask production

    NASA Astrophysics Data System (ADS)

    Yagawa, Keisuke; Ugajin, Kunihiro; Suenaga, Machiko; Kobayashi, Yoshihito; Motokawa, Takeharu; Hagihara, Kazuki; Saito, Masato; Itoh, Masamitsu

    2014-07-01

    ArF immersion lithography combined with double patterning has been used for fabricating below half pitch 40nm devices. However, when pattern size shrinks below 20nm, we must use new technology like quadruple patterning process or next generation lithography (NGL) solutions. Moreover, with change in lithography tool, next generation mask production will be needed. According to ITRS 2013, fabrication of finer patterns less than 15nm will be required on mask plate in NGL mask production 5 years later [1]. In order to fabricate finer patterns on mask, higher resolution EB mask writer and high performance fabrication process will be required. In a previous study, we investigated a potential of mask fabrication process for finer patterning and achieved 17nm dense line pattern on mask plate by using VSB (Variable Shaped Beam) type EB mask writer and chemically amplified resist [2][3]. After a further investigation, we constructed higher performance mask process by using new EB mask writer EBM9000. EBM9000 is the equipment supporting hp16nm generation's photomask production and has high accuracy and high throughput. As a result, we achieved 15.5nm pattern on mask with high productivity. Moreover, from evaluation of isolated pattern, we proved that current mask process has the capability for sub-10nm pattern. These results show that the performance of current mask fabrication process have the potential to fabricate the next-generation mask.

  1. Helium release during shale deformation: Experimental validation

    NASA Astrophysics Data System (ADS)

    Bauer, Stephen J.; Gardner, W. Payton; Heath, Jason E.

    2016-07-01

    This work describes initial experimental results of helium tracer release monitoring during deformation of shale. Naturally occurring radiogenic 4He is present in high concentration in most shales. During rock deformation, accumulated helium could be released as fractures are created and new transport pathways are created. We present the results of an experimental study in which confined reservoir shale samples, cored parallel and perpendicular to bedding, which were initially saturated with helium to simulate reservoir conditions, are subjected to triaxial compressive deformation. During the deformation experiment, differential stress, axial, and radial strains are systematically tracked. Release of helium is dynamically measured using a helium mass spectrometer leak detector. Helium released during deformation is observable at the laboratory scale and the release is tightly coupled to the shale deformation. These first measurements of dynamic helium release from rocks undergoing deformation show that helium provides information on the evolution of microstructure as a function of changes in stress and strain.

  2. Pulsed helium ionization detection system

    DOEpatents

    Ramsey, R.S.; Todd, R.A.

    1985-04-09

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  3. Pulsed helium ionization detection system

    DOEpatents

    Ramsey, Roswitha S.; Todd, Richard A.

    1987-01-01

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  4. DIADDHEM set-up: New IBA facility for studying the helium behavior in nuclear glasses

    NASA Astrophysics Data System (ADS)

    Chamssedine, F.; Sauvage, T.; Peuget, S.

    2010-06-01

    The immobilization of fission products and minor actinides by vitrification is the reference process for industrial management of high-level radioactive wastes generated from spent fuel reprocessing. The glassy matrix is subjected to radiation damage and radiogenic helium generation due to the alpha decays of minor actinides. A specific experimental study has been conducted to better understand the behavior of helium and its diffusion mechanisms in the borosilicate glass. Helium production is simulated by external irradiation with 3He + ions at a concentration (2 × 10 15 He cm -2) equivalent to the one obtained after 1000 years of glass storage. He diffusion coefficients as function of temperature are extracted from the evolution of the depth profiles after annealing. The 3He(d, α) 1H Nuclear Reaction Analysis (NRA) technique is successfully used for in situ low-temperature measurements of depth profiles. Its high depth resolution allows detecting helium mobility at a temperature as low as 250 K and the presence of a trapped helium fraction. The good agreement of our first values of diffusion coefficients with the literature data highlights the relevance of the implantation technique in the study of helium diffusion mechanisms in borosilicate glasses.

  5. 21 CFR 184.1355 - Helium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Helium. 184.1355 Section 184.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1355 Helium. (a) Helium (empirical formula He, CAS Reg. No. 7440-59-7) is...

  6. 21 CFR 582.1355 - Helium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Helium. 582.1355 Section 582.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Helium. (a) Product. Helium. (b) Conditions of use. This substance is generally recognized as safe...

  7. 43 CFR 3100.1 - Helium.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Helium. 3100.1 Section 3100.1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE... Helium. The ownership of and the right to extract helium from all gas produced from lands leased...

  8. 43 CFR 3100.1 - Helium.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Helium. 3100.1 Section 3100.1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE... Helium. The ownership of and the right to extract helium from all gas produced from lands leased...

  9. 21 CFR 582.1355 - Helium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Helium. 582.1355 Section 582.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Helium. (a) Product. Helium. (b) Conditions of use. This substance is generally recognized as safe...

  10. 21 CFR 184.1355 - Helium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Helium. 184.1355 Section 184.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1355 Helium. (a) Helium (empirical formula He, CAS Reg. No. 7440-59-7) is...

  11. 21 CFR 184.1355 - Helium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Helium. 184.1355 Section 184.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1355 Helium. (a) Helium (empirical formula He, CAS Reg. No. 7440-59-7) is a colorless,...

  12. 21 CFR 582.1355 - Helium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Helium. 582.1355 Section 582.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Helium. (a) Product. Helium. (b) Conditions of use. This substance is generally recognized as safe...

  13. 43 CFR 3100.1 - Helium.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Helium. 3100.1 Section 3100.1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE... Helium. The ownership of and the right to extract helium from all gas produced from lands leased...

  14. Applying the helium ionization detector in chromatography

    NASA Technical Reports Server (NTRS)

    Gibson, E. K.; Andrawes, F. F.; Brazell, R. S.

    1981-01-01

    High noise levels and oversensitivity of helium detector make flame-ionization and thermal-conductivity detectors more suitable for chromotography. Deficiencies are eliminated by modifying helium device to operate in saturation rather than multiplication mode. Result is low background current, low noise, high stability, and high sensitivity. Detector analyzes halocarbons, hydrocarbons, hydrogen cyanide, ammonia, and inorganics without requiring expensive research-grade helium.

  15. 21 CFR 582.1355 - Helium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Helium. 582.1355 Section 582.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Helium. (a) Product. Helium. (b) Conditions of use. This substance is generally recognized as safe...

  16. 21 CFR 184.1355 - Helium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Helium. 184.1355 Section 184.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1355 Helium. (a) Helium (empirical formula He, CAS Reg. No. 7440-59-7) is...

  17. 43 CFR 3100.1 - Helium.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Helium. 3100.1 Section 3100.1 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE... Helium. The ownership of and the right to extract helium from all gas produced from lands leased...

  18. 21 CFR 582.1355 - Helium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Helium. 582.1355 Section 582.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Helium. (a) Product. Helium. (b) Conditions of use. This substance is generally recognized as safe...

  19. 21 CFR 184.1355 - Helium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Helium. 184.1355 Section 184.1355 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1355 Helium. (a) Helium (empirical formula He, CAS Reg. No. 7440-59-7) is...

  20. Helium abundances on the moon: Assumptions and estimates

    NASA Astrophysics Data System (ADS)

    Taylor, Lawrence A.

    Nuclear energy is a highly desirable source of energy, and He-3 is the most prized of the fusion reactants. As the Wisconsin Group has emphasized, He-3 may be the only true economic ore on the Moon. The lack of a shielding atmosphere on the Moon permits solar-wind alpha particles to impinge upon the lunar regolith and become implanted into the various solid components. In particular, large quantities of helium (5 to 50 ppm) are presented. The measured parameter of Is/FeO, a direct indicator of maturity and exposure age, can be used as a first approximation to predict the abundances of many solar-wind components in the soils. However, because ilmenite has a much higher retentivity for helium than the other phases, the TiO2 contents of the soils are better indicators of helium contents (Taylor, Space 90). High-Ti mare bassalt regions, such as at the Apollo 17 locale, appear to be the best areas for He mining (15 to 50 ppm HeT), versus 3 to 9 ppm in the Highlands. However, the relationships between Is/FeO, TiO2 and He-3 contents are complicated - e.g., many of the most He-rich soils are immature to submature. The amount of He-3 in the regolith of the moon is estimated at 220,000 tons in the outer 2 m of the Maria.

  1. Holographically Encoded Volume Phase Masks

    DTIC Science & Technology

    2015-07-13

    experiments have been performed using an HPM recorded in a 1.97-mm thick photo -thermo-refractive (PTR) glass sample as illustrated in Fig. 1. PTR glass is a...spiral phase plate,” Appl. Opt. 43(12), 2397–2399 (2004). 19. K. Peithmann et al., “Low-spatial-frequency refractive-index changes in iron- doped ...Binary volume phase masks in photo -thermo-refrac- tive glass,” Opt. Lett. 37(7), 1190–1192 (2012). 21. M. Bass, Handbook of Optics, 2nd ed., McGraw-Hill

  2. Removal of particles from lithographic masks through plasma-assisted cleaning by metastable atomic neutralization

    NASA Astrophysics Data System (ADS)

    Lytle, W. M.; Szybilski, D. S.; Das, C. E.; Raju, R.; Surla, V.; Neumann, M. J.; Ruzic, D. N.

    2008-11-01

    For extreme ultraviolet lithography (EUVL) to become a high volume manufacturing technology for integrated circuit manufacturing, the cleanliness of the system, especially the photomask, is of high importance. For EUV photomasks, which cannot be protected from contamination by the use of a pellicle, an effective and quick cleaning technology needs to be ready in order to maintain wafer throughput. There are challenges to extend current wet cleaning technologies to meet the future needs for damage-free and high efficiency mask cleaning. Accordingly, a unique process for cleaning particulates from surfaces, specifically photomasks as well as wafers, has been evaluated at the University of Illinois Urbana-Champaign. The removal technique utilizes a high density plasma source as well as pulsed substrate biases to provide for removal. Helium is used as the primary gas in the plasma, which under ionization, provides for a large density of helium metastable atoms present in the plasma. These metastable helium atoms have on the order of 20 eV of energy which can transfer to particles on the substrate to be cleaned. When the substrate is under a small flux of ion bombardment, these bonds then remain broken and it is theorized that this allows the particles to be volatilized for their subsequent removal. 100 % particle removal efficiency has been obtained for 30 nm, 80 nm, and 200 nm polystyrene latex particles. In addition, removal rate has been correlated with helium metastable population density determined by optical emission spectroscopy.

  3. In situ Transmission Electron Microscopy He+ implantation and thermal aging of nanocrystalline iron

    NASA Astrophysics Data System (ADS)

    Muntifering, Brittany; Fang, Youwu; Leff, Asher C.; Dunn, Aaron; Qu, Jianmin; Taheri, Mitra L.; Dingreville, Remi; Hattar, Khalid

    2016-12-01

    The high density of interfaces in nanostructured materials are hypothesized to improve radiation tolerance compared to coarse-grained materials. In order to investigate the roles of vacancies, self-interstitials, and helium, both room temperature in situ TEM He+ implantation and annealing, as well as high temperature He+ implantation was performed on nanocrystalline iron. Dislocation loops are formed by the accumulation of mobile point defects rather than by displacement cascades at intermediate temperatures. Around 600 °C, loops disappeared through gradual shrinking, which is hypothesized to correspond to the annihilation of self-interstitial atoms by mobile vacancies that also resulted in cavity formation. The room temperature implantation resulted in cavities evenly distributed throughout the grain after annealing, whereas cavities were predominately observed at grain boundaries for the elevated temperature implantation. This difference is associated with the formation of stable helium-vacancy complexes in the grains during room temperature implantation, which is not present during high temperature implantation.

  4. Why Helium Ends in "-Ium"

    ERIC Educational Resources Information Center

    Jensen, William B.; Holme, Thomas; Cooper, Melanie; White, Carol

    2004-01-01

    Edward Frankland and Norman Lockyer researched upon a gaseous spectra in relation to the physical constitution of the sun and named it as "helium" (from Greek "helios" meaning "sun"). Since Lockyer apparently never formally proposed the name in print, it is not known why he chose to use a metallic end "ium".

  5. Helium diffusion in the sun

    NASA Technical Reports Server (NTRS)

    Bahcall, J. N.; Pinsonneault, M. H.

    1992-01-01

    We calculate improved standard solar models using the new Livermore (OPAL) opacity tables, an accurate (exportable) nuclear energy generation routine which takes account of recent measurements and analyses, and the recent Anders-Grevesse determination of heavy element abundances. We also evaluate directly the effect of the diffusion of helium with respect to hydrogen on the calculated neutrino fluxes, on the primordial solar helium abundance, and on the depth of the convective zone. Helium diffusion increases the predicted event rates by about 0.8 SNU, or 11 percent of the total rate, in the chlorine solar neutrino experiment, by about 3.5 SNU, or 3 percent, in the gallium solar neutrino experiments, and by about 12 percent in the Kamiokande and SNO solar neutrino experiments. The best standard solar model including helium diffusion and the most accurate nuclear parameters, element abundances, and radiative opacity predicts a value of 8.0 SNU +/- 3.0 SNU for the C1-37 experiment and 132 +21/-17 SNU for the Ga - 71 experiment, where the uncertainties include 3 sigma errors for all measured input parameters.

  6. Helium and neon in lunar ilmenites of different antiquities

    NASA Technical Reports Server (NTRS)

    Nier, A. O.; Schlutter, D. J.

    1994-01-01

    Helium and neon were extracted from individual lunar ilmenite grains, approximately 100 micrometers in diameter, using a pulsed step-heating technique. Grains from lunar samples 71501 and 79035, believed to have been exposed to solar corpuscular radiation at greatly different times, were studied. The results found were consistent with the hypothesis that in addition to solar-wind-implanted gas, a second more deeply implanted component was present in both species of grains. Average isotopic ratios were determined giving equal weight to each of the particles. As found in depth studies employing chemical etching, both the He-3/He-4 and Ne-20/Ne-22 ratios were lower in the more deeply implanted gas than in the solar wind component. The He-3/He-4 ratio in the solar wind component of the more ancient grains was lower than that in the more recently exposed ones, whereas no difference was found for the more deeply embedded He. In the deeply embedded component of the ancient grains, the He-4/Ne-20 ratio was approx. 2x that found in the more recently exposed grains. In the shallowly implanted component, the ratio varied greatly from grain to grain, preventing comparison with the solar wind elemental composition.

  7. Polyurethane Masks Large Areas in Electroplating

    NASA Technical Reports Server (NTRS)

    Beasley, J. L.

    1985-01-01

    Polyurethane foam provides effective mask in electroplating of copper or nickel. Thin layer of Turco maskant painted on area to be masked: Layer ensures polyurethane foam removed easily after served its purpose. Component A, isocyanate, and component B, polyol, mixed together and brushed or sprayed on mask area. Mixture reacts, yielding polyurethane foam. Foam prevents deposition of nickel or copper on covered area. New method saves time, increases productivity and uses less material than older procedures.

  8. Histrelin Implant

    MedlinePlus

    ... implant (Supprelin LA) is used to treat central precocious puberty (CPP; a condition causing children to enter puberty too soon, resulting in faster than normal bone growth and development of sexual characteristics) in girls ...

  9. Penile Implants

    MedlinePlus

    ... placed inside the penis to allow men with erectile dysfunction (ED) to get an erection. Penile implants are ... complications and follow-up care. For most men, erectile dysfunction can be successfully treated with medications or use ...

  10. [A new bite block for laryngeal mask].

    PubMed

    Ohe, Y; Ota, M; Tachibana, C; Aoyama, Y

    2001-05-01

    We devised a new bite block made of a used connector of anesthesia machine (ACOMA medical industry CO., LTD.) for laryngeal mask. Fitness for laryngeal mask and strength against patient's biting are the key for its use. Cutting lengthwise the connector (the outside diameter 22 mm, inside diameter 15-19 mm, 55 mm in length) we made a bite block for laryngeal mask. We studied the strength of a new bite block experimentally and recognized its ability to bear the human biting. We conclude a new bite block for laryngeal mask is clinically useful and can be used during anesthesia for its fitness and safety.

  11. Temporal masking of multidimensional tactual stimuli

    NASA Astrophysics Data System (ADS)

    Tan, Hong Z.; Reed, Charlotte M.; Delhorne, Lorraine A.; Durlach, Nathaniel I.; Wan, Natasha

    2003-12-01

    Experiments were performed to examine the temporal masking properties of multidimensional tactual stimulation patterns delivered to the left index finger. The stimuli consisted of fixed-frequency sinusoidal motions in the kinesthetic (2 or 4 Hz), midfrequency (30 Hz), and cutaneous (300 Hz) frequency ranges. Seven stimuli composed of one, two, or three spectral components were constructed at each of two signal durations (125 or 250 ms). Subjects identified target signals under three different masking paradigms: forward masking, backward masking, and sandwiched masking (in which the target is presented between two maskers). Target identification was studied as a function of interstimulus interval (ISI) in the range 0 to 640 ms. For both signal durations, percent-correct scores increased with ISI for each of the three masking paradigms. Scores with forward and backward masking were similar and significantly higher than scores obtained with sandwiched masking. Analyses of error trials revealed that subjects showed a tendency to respond, more often than chance, with the masker, the composite of the masker and target, or the combination of the target and a component of the masker. The current results are compared to those obtained in previous studies of tactual recognition masking with brief cutaneous spatial patterns. The results are also discussed in terms of estimates of information transfer (IT) and IT rate, are compared to previous studies with multidimensional tactual signals, and are related to research on the development of tactual aids for the deaf.

  12. Evaluation of a native vegetation masking technique

    NASA Technical Reports Server (NTRS)

    Kinsler, M. C.

    1984-01-01

    A crop masking technique based on Ashburn's vegetative index (AVI) was used to evaluate native vegetation as an indicator of crop moisture condition. A mask of the range areas (native vegetation) was generated for each of thirteen Great Plains LANDSAT MSS sample segments. These masks were compared to the digitized ground truth and accuracies were computed. An analysis of the types of errors indicates a consistency in errors among the segments. The mask represents a simple quick-look technique for evaluating vegetative cover.

  13. Cochlear implants.

    PubMed

    Connell, Sarah S; Balkany, Thomas J

    2006-08-01

    Cochlear implants are cost-effective auditory prostheses that safely provide a high-quality sensation of hearing to adults who are severely or profoundly deaf. In the past 5 years, progress has been made in hardware and software design, candidate selection, surgical techniques, device programming, education and rehabilitation,and, most importantly, outcomes. Cochlear implantation in the elderly is well tolerated and provides marked improvement in auditory performance and psychosocial functioning.

  14. Mask lithography for display manufacturing

    NASA Astrophysics Data System (ADS)

    Sandstrom, T.; Ekberg, P.

    2010-05-01

    The last ten years have seen flat displays conquer our briefcases, desktops, and living rooms. There has been an enormous development in production technology, not least in lithography and photomasks. Current masks for large displays are more than 2 m2 and make 4-6 1X prints on glass substrates that are 9 m2. One of the most challenging aspects of photomasks for displays is the so called mura, stripes or blemishes which cause visible defects in the finished display. For the future new and even tighter maskwriter specifications are driven by faster transistors and more complex pixel layouts made necessary by the market's wish for still better image quality, multi-touch panels, 3D TVs, and the next wave of e-book readers. Large OLED screens will pose new challenges. Many new types of displays will be lowcost and use simple lithography, but anything which can show video and high quality photographic images needs a transistor backplane and sophisticated masks for its production.

  15. X-ray lithography masking

    NASA Technical Reports Server (NTRS)

    Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

    1998-01-01

    X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

  16. Method of making low leakage N-channel SOS transistors utilizing positive photoresist masking techniques

    NASA Technical Reports Server (NTRS)

    Policastro, Steven G. (Inventor); Woo, Dae-Shik (Inventor)

    1983-01-01

    A self-aligned method of implanting the edges of NMOS/SOS transistors is described. The method entails covering the silicon islands with a thick oxide layer, applying a protective photoresist layer over the thick oxide layer, and exposing the photoresist layer from the underside of the sapphire substrate thereby using the island as an exposure mask. Only the photoresist on the islands' edges will be exposed. The exposed photoresist is then removed and the thick oxide is removed from the islands edges which are then implanted.

  17. Contraceptive implants.

    PubMed

    McDonald-Mosley, Raegan; Burke, Anne E

    2010-03-01

    Implantable contraception has been extensively used worldwide. Implants are one of the most effective and reversible methods of contraception available. These devices may be particularly appropriate for certain populations of women, including women who cannot use estrogen-containing contraception. Implants are safe for use by women with many chronic medical problems. The newest implant, Implanon (Organon International, Oss, The Netherlands), is the only device currently available in the United States and was approved in 2006. It is registered for 3 years of pregnancy prevention. Contraceptive implants have failure rates similar to tubal ligation, and yet they are readily reversible with a return to fertility within days of removal. Moreover, these contraceptive devices can be safely placed in the immediate postpartum period, ensuring good contraceptive coverage for women who may be at risk for an unintended pregnancy. Irregular bleeding is a common side effect for all progestin-only contraceptive implants. Preinsertion counseling should address possible side effects, and treatment may be offered to women who experience prolonged or frequent bleeding.

  18. High-temperature helium-loop facility

    SciTech Connect

    Tokarz, R.D.

    1981-09-01

    The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100/sup 0/F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system.

  19. Set Size and Mask Duration Do Not Interact in Object-Substitution Masking

    ERIC Educational Resources Information Center

    Argyropoulos, Ioannis; Gellatly, Angus; Pilling, Michael; Carter, Wakefield

    2013-01-01

    Object-substitution masking (OSM) occurs when a mask, such as four dots that surround a brief target item, onsets simultaneously with the target and offsets a short time after the target, rather than simultaneously with it. OSM is a reduction in accuracy of reporting the target with the temporally trailing mask, compared with the simultaneously…

  20. Variations in backward masking with different masking stimuli: I. Local interaction versus attentional switch.

    PubMed

    Bachmann, Talis; Luiga, Iiris; Põder, Endel

    2005-01-01

    The types of stimuli used as targets and masks considerably change the masking functions in a way that requires us to abandon any single mechanism of masking as the sole explanation of backward masking. In the first of two reports in which the problem of the mask-dependence of masking is addressed, we explore the role of the relative spatial positioning of targets and masks in order to differentiate between local interaction and attentional models. If single letters were masked by double-letter masks then the relative spatial arrangement of the letters, which was changed in order to vary the involvement of metacontrast-like processes, had an effect at shorter SOAs, but not at longer SOAs where strong masking still persisted. This poses difficulties for proposing local contour interaction as the main mechanism of masking. Similarly, crowding effects alone cannot explain the results. Backward masking also involves attention being directed to working-memory processing of the succeeding object while abandoning the preceding object.

  1. Alternating phase-shifted mask for logic gate levels, design, and mask manufacturing

    NASA Astrophysics Data System (ADS)

    Liebmann, Lars W.; Graur, Ioana C.; Leipold, William C.; Oberschmidt, James M.; O'Grady, David S.; Regaill, Denis

    1999-07-01

    While the benefits of alternating phase shifted masks in improving lithographic process windows at increased resolution are well known throughout the lithography community, broad implementation of this potentially powerful technique has been slow due to the inherent complexity of the layout design and mask manufacturing process. This paper will review a project undertaken at IBM's Semiconductor Research and Development Center and Mask Manufacturing and Development facility to understand the technical and logistical issues associated with the application of alternating phase shifted mask technology to the gate level of a full microprocessor chip. The work presented here depicts an important milestone toward integration of alternating phase shifted masks into the manufacturing process by demonstrating an automated design solution and yielding a functional alternating phase shifted mask. The design conversion of the microprocessor gate level to a conjugate twin shifter alternating phase shift layout was accomplished with IBM's internal design system that automatically scaled the design, added required phase regions, and resolved phase conflicts. The subsequent fabrication of a nearly defect free phase shifted mask, as verified by SEM based die to die inspection, highlights the maturity of the alternating phase shifted mask manufacturing process in IBM's internal mask facility. Well defined and recognized challenges in mask inspection and repair remain and the layout of alternating phase shifted masks present a design and data preparation overhead, but the data presented here demonstrate the feasibility of designing and building manufacturing quality alternating phase shifted masks for the gate level of a microprocessor.

  2. Approximating the Helium Wavefunction in Positronium-Helium Scattering

    NASA Technical Reports Server (NTRS)

    DiRienzi, Joseph; Drachman, Richard J.

    2003-01-01

    In the Kohn variational treatment of the positronium- hydrogen scattering problem the scattering wave function is approximated by an expansion in some appropriate basis set, but the target and projectile wave functions are known exactly. In the positronium-helium case, however, a difficulty immediately arises in that the wave function of the helium target atom is not known exactly, and there are several ways to deal with the associated eigenvalue in formulating the variational scattering equations to be solved. In this work we will use the Kohn variational principle in the static exchange approximation to d e t e e the zero-energy scattering length for the Ps-He system, using a suite of approximate target functions. The results we obtain will be compared with each other and with corresponding values found by other approximation techniques.

  3. EUVL masks: paving the path for commercialization

    NASA Astrophysics Data System (ADS)

    Mangat, Pawitter J. S.; Hector, Scott D.

    2001-09-01

    Optical projection lithography has been the principal vehicle of semiconductor manufacturing for more than 20 years and is marching aggressively to satisfy the needs of semiconductor manufacturers for 100nm devices. However, the complexity of optical lithography continues to increase as wavelength reduction continues to 157nm. Extreme Ultraviolet Lithography (EUVL), with wavelength from 13-14 nm, is evolving as a leading next generation lithography option for semiconductor industry to stay on the path laid by Moore's Law. Masks are a critical part of the success of any technology and are considered to be high risk both for optical lithography and NGL technologies for sub-100nm lithography. Two key areas of EUV mask fabrication are reflective multilayer deposition and absorber patterning. In the case of reflective multilayers, delivering defect free multilayers for mask blanks is the biggest challenge. Defect mitigation is being explored as a possible option to smooth the multilayer defects in addition to optimization of the deposition process to reduce defect density. The mask patterning process needs focus on the defect-free absorber stack patterning process, mask cleaning, inspection and repair. In addition, there is considerable effort to understand by simulations, the defect printability, thermal and mechanical distortions, and non-telecentric illumination, to mention a few. To protect the finished mask from defects added during use, a removable pellicle strategy combined with thermophoretic protection during exposure is being developed. Recent migration to square form factor using low thermal expansion material (LTEM) is advantageous as historical developments in optical masks can be applied to EUV mask patterning. This paper addresses recent developments in the EUV mask patterning and highlights critical manufacturing process controls needed to fabricate defect-free full field masks with CD and image placement specifications for sub-70nm node lithography. No

  4. A facial mask comprising Dead Sea mud.

    PubMed

    Abu-Jdayil, Basim; Mohameed, Hazim A

    2006-01-01

    Many investigators have proved that Dead Sea salt and mud are useful in treating skin disorders and skin diseases. Therefore, the black mud has been extensively used as a base for the preparation of soaps, creams, and unguents for skin care. This study concerns a facial mask made mainly of Dead Sea mud. The effects of temperature and shearing conditions on the rheological behavior of the facial mask were investigated. The mud facial mask exhibited a shear thinning behavior with a yield stress. It was found that the apparent viscosity of the mask has a strong dependence on the shear rate as well as on the temperature. The facial mask exhibited a maximum yield stress and very shear thinning behavior at 40 degrees C, which is attributed to the gelatinization of the polysaccharide used to stabilize the mud particles. On the other hand, the mud mask exhibited a time-independent behavior at low temperatures and shear rates and changed to a thixotropic behavior upon increasing both the temperature and the shear rate. The shear thinning and thixotropic behaviors have a significant importance in the ability of the facial mask to spread on the skin: the Dead Sea mud mask can break down for easy spreading, and the applied film can gain viscosity instantaneously to resist running. Moreover, particle sedimentation, which in this case would negatively affect consumer acceptance of the product, occurs slowly due to high viscosity at rest conditions.

  5. 21 CFR 868.5590 - Scavenging mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scavenging mask. 868.5590 Section 868.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5590 Scavenging mask. (a) Identification....

  6. 21 CFR 868.5570 - Nonrebreathing mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonrebreathing mask. 868.5570 Section 868.5570 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5570 Nonrebreathing mask....

  7. Spatial processing and visual backward masking.

    PubMed

    Herzog, Michael H

    2008-07-15

    Most theories of visual masking focus prima-rily on the temporal aspects of visual information processing, strongly neglecting spatial factors. In recent years, however, we have shown that this position is not tenable. Spatial aspects cannot be neglected in metacontrast, pattern and un-masking. Here, we review these results.

  8. Spatial processing and visual backward masking

    PubMed Central

    Herzog, Michael H.

    2008-01-01

    Most theories of visual masking focus prima-rily on the temporal aspects of visual information processing, strongly neglecting spatial factors. In recent years, however, we have shown that this position is not tenable. Spatial aspects cannot be neglected in metacontrast, pattern and un-masking. Here, we review these results. PMID:20517500

  9. Masking the Feeling of Being Stupid.

    ERIC Educational Resources Information Center

    Smith, Sally L.

    1988-01-01

    Teaching experience at The Lab School of Washington has shown that learning-disabled children and adults cope with their lack of self-esteem and feelings of stupidity by developing masks to hide their hurt. These include masks of super-competence, helplessness, invisibility, clowning, injustice collecting, indifference, boredom, outrageousness,…

  10. Implicit Semantic Perception in Object Substitution Masking

    ERIC Educational Resources Information Center

    Goodhew, Stephanie C.; Visser, Troy A. W.; Lipp, Ottmar V.; Dux, Paul E.

    2011-01-01

    Decades of research on visual perception has uncovered many phenomena, such as binocular rivalry, backward masking, and the attentional blink, that reflect "failures of consciousness". Although stimuli do not reach awareness in these paradigms, there is evidence that they nevertheless undergo semantic processing. Object substitution masking (OSM),…

  11. Computing Challenges in Coded Mask Imaging

    NASA Technical Reports Server (NTRS)

    Skinner, Gerald

    2009-01-01

    This slide presaentation reviews the complications and challenges in developing computer systems for Coded Mask Imaging telescopes. The coded mask technique is used when there is no other way to create the telescope, (i.e., when there are wide fields of view, high energies for focusing or low energies for the Compton/Tracker Techniques and very good angular resolution.) The coded mask telescope is described, and the mask is reviewed. The coded Masks for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) instruments are shown, and a chart showing the types of position sensitive detectors used for the coded mask telescopes is also reviewed. Slides describe the mechanism of recovering an image from the masked pattern. The correlation with the mask pattern is described. The Matrix approach is reviewed, and other approaches to image reconstruction are described. Included in the presentation is a review of the Energetic X-ray Imaging Survey Telescope (EXIST) / High Energy Telescope (HET), with information about the mission, the operation of the telescope, comparison of the EXIST/HET with the SWIFT/BAT and details of the design of the EXIST/HET.

  12. Hydrogen, helium, and other solar-wind components in lunar soil - Abundances and predictions

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.

    1990-01-01

    The lack of a shielding atmosphere on the moon permits solar-wind particles to impinge upon the lunar soil and become implanted into the various phases which comprise the soil. Relatively large quantities of solar-wind implanted hydrogen (50-100 ppm) and helium (10-50 ppm) are present. The measured parameter of I(s)FeO, a direct indicator of maturity and exposure age, can be used as a first approximation to predict the abundances of many solar-wind components in the soils. However, because ilmenite acts as a 'sponge' for the retention of certain elements, the TiO2 content of the soil is a better indicator for hydrogen and helium contents.

  13. Superfluid helium leak sealant study

    NASA Technical Reports Server (NTRS)

    Vorreiter, J. W.

    1981-01-01

    Twenty-one leak specimens were fabricated in the ends of stainless steel and aluminum tubes. Eighteen of these tubes were coated with a copolymer material to seal the leak. The other three specimens were left uncoated and served as control specimens. All 21 tubes were cold shocked in liquid helium 50 times and then the leak rate was measured while the tubes were submerged in superfluid helium at 1.7 K. During the cold shocks two of the coated specimens were mechanically damaged and eliminated from the test program. Of the remaining 16 coated specimens one suffered a total coating failure and resulting high leak rate. Another three of the coated specimens suffered partial coating failures. The leak rates of the uncoated specimens were also measured and reported. The significance of various leak rates is discussed in view of the infrared astronomical satellite (IRAS) Dewar performance.

  14. Confined helium on Lagrange meshes.

    PubMed

    Baye, D; Dohet-Eraly, J

    2015-12-21

    The Lagrange-mesh method has the simplicity of a calculation on a mesh and can have the accuracy of a variational method. It is applied to the study of a confined helium atom. Two types of confinement are considered. Soft confinements by potentials are studied in perimetric coordinates. Hard confinement in impenetrable spherical cavities is studied in a system of rescaled perimetric coordinates varying in [0,1] intervals. Energies and mean values of the distances between electrons and between an electron and the helium nucleus are calculated. A high accuracy of 11 to 15 significant figures is obtained with small computing times. Pressures acting on the confined atom are also computed. For sphere radii smaller than 1, their relative accuracies are better than 10(-10). For larger radii up to 10, they progressively decrease to 10(-3), still improving the best literature results.

  15. Detecting scintillations in liquid helium

    NASA Astrophysics Data System (ADS)

    Huffman, P. R.; McKinsey, D. N.

    2013-09-01

    We review our work in developing a tetraphenyl butadiene (TPB)-based detection system for a measurement of the neutron lifetime using magnetically confined ultracold neutrons (UCN). As part of the development of the detection system for this experiment, we studied the scintillation properties of liquid helium itself, characterized the fluorescent efficiencies of different fluors, and built and tested three detector geometries. We provide an overview of the results from these studies as well as references for additional information.

  16. Superfluid Helium Tanker (SFHT) study

    NASA Technical Reports Server (NTRS)

    Eberhardt, Ralph N.; Dominick, Sam M.; Anderson, John E.; Gille, John P.; Martin, Tim A.; Marino, John S.; Paynter, Howard L.; Traill, R. Eric; Herzl, Alfred; Gotlib, Sam

    1988-01-01

    Replenishment of superfluid helium (SFHe) offers the potential of extending the on-orbit life of observatories, satellite instruments, sensors and laboratories which operate in the 2 K temperature regime. A reference set of resupply customers was identified as representing realistic helium servicing requirements and interfaces for the first 10 years of superfluid helium tanker (SFHT) operations. These included the Space Infrared Telescope Facility (SIRTF), the Advanced X-ray Astrophysics Facility (AXAF), the Particle Astrophysics Magnet Facility (Astromag), and the Microgravity and Materials Processing Sciences Facility (MMPS)/Critical Point Phenomena Facility (CPPF). A mixed-fleet approach to SFHT utilization was considered. The tanker permits servicing from the Shuttle cargo bay, in situ when attached to the OMV and carried to the user spacecraft, and as a depot at the Space Station. A SFHT Dewar ground servicing concept was developed which uses a dedicated ground cooling heat exchanger to convert all the liquid, after initial fill as normal fluid, to superfluid for launch. This concept permits the tanker to be filled to a near full condition, and then cooled without any loss of fluid. The final load condition can be saturated superfluid with any desired ullage volume, or the tank can be totally filed and pressurized. The SFHT Dewar and helium plumbing system design has sufficient component redundancy to meet fail-operational, fail-safe requirements, and is designed structurally to meet a 50 mission life usage requirement. Technology development recommendations were made for the selected SFHT concept, and a Program Plan and cost estimate prepared for a phase C/D program spanning 72 months from initiation through first launch in 1997.

  17. Vorticity matching in superfluid helium

    NASA Astrophysics Data System (ADS)

    Samuels, David C.

    1991-12-01

    Recent experiments have rekindled interest in high Reynolds number flows using superfluid helium. In a continuing series of experiments, the flow of helium II through various devices (smooth pipes, corrugated pipes, valves, venturies, turbine flowmeters, and coanda flowmeters for example) was investigated. In all cases, the measured values (typically, mass flow rates and pressure drops) were found to be well described by classical relations for high Reynolds flows. This is unexpected since helium II consists of two interpenetrating fluids; one fluid with nonzero viscosity (the normal fluid) and one with zero viscosity (the superfluid). Only the normal fluid component should directly obey classical relations. Since the experiments listed above only measure the external behavior of the flow (i.e., pressure drops over devices), there is a great deal of room for interpretation of their results. One possible interpretation is that in turbulent flows the normal fluid and the superfluid velocity fields are somehow 'locked' together, presumably by the mutual friction force between the superfluid vortex filaments and the normal fluid. We refer to this locking together of the two fluids as 'vorticity matching.'

  18. Germanium implantation into substrates for integrated optics

    NASA Astrophysics Data System (ADS)

    Poumellec, B.; Traverse, A.; Artigaud, S.; Hervo, J.

    1994-04-01

    Germanium and helium implantations have been performed in LiNbO 3, SiO 2 quartz and silica. The agreement between calculated and experimental doping profiles is excellent. The index profiles coincide with the calculated collision profiles but we have observed a surface effect in quartz and LiNbO 3. In the first material, Ge implantation yields a larger decrease of the refractive index at the surface than He, as it is predicted by calculation if we assume the refractive index and the disorder profile to be connected. In contrast, in LiNbO 3 a reverse observation is made with respect to the refractive index. It is accompanied by chemical perturbation which interferes with the structural modification at the origin of the refractive index change. One advantage of the method is that implanted Ge is in a reduced state.

  19. Impact of photolithography and mask variability on interconnect parasitics

    NASA Astrophysics Data System (ADS)

    Tian, Yuxin; Shi, Weiping; Mercer, M. Ray

    2005-11-01

    Due to photolithography effects and manufacture process variations, the actual features printed on wafer are different from the designed ones. This difference results in the inaccuracy on parasitic extraction, which is critical for timing verification and design for manufacturability. Most of the current layout parasitic extraction (LPE) tools ignore these effects and can cause as high as 20% errors. This paper proposes a new strategy to extract interconnect parasitics with the consideration of photolithography effects and process variations. Based on the feedback from lithography simulation, a shape correction process is setup to adjust the interconnect structure for LPE tools. Compared with the traditional extraction methodology, the parasitics extracted from this adjusted geometry are more accurate. This method can be implanted into the current design flow with minimum change. Meanwhile, this paper studies the impacts of mask critical dimension (CD) variations on interconnect parasitics. The variability analysis is based on PROLITH lithography simulation software and is tested on RAPHAEL interconnect library. The results show a high nonlinear relationship between the mask variation and the interconnect parasitics.

  20. Nasal mask ventilation is better than face mask ventilation in edentulous patients

    PubMed Central

    Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

    2016-01-01

    Background and Aims: Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Material and Methods: Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. Results: A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Conclusion: Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients. PMID:27625477

  1. Investigations of levitated helium drops

    NASA Astrophysics Data System (ADS)

    Whitaker, Dwight Lawrence

    1999-11-01

    We report on the development of two systems capable of levitating drops of liquid helium. Helium drops of ˜20 mum have been levitated with the radiation pressure from two counter-propagating Nd:YAG laser beams. Drops are produced with a submerged piezoelectric transducer, and could be held for up to three minutes in our optical trap. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pressure of the curved drop surfaces appears to be a significant effect limiting the drop lifetimes. Helium drops as large as 2 cm in diameter have been suspended in the earth's gravitational field with a magnetic field. A commercial superconducting solenoid provides the necessary field, field-gradient product required to levitate the drops. Drops are cooled to 0.5 K with a helium-3 refrigerator, and can be held in the trap indefinitely. We have found that when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. This effect is a result of the evaporation of liquid from between the two drops, and is found to occur only for normal fluid drops. We can induce shape oscillations in charged, levitated drops with an applied ac electric field. We have measured the resonance frequencies and damping rates for the l = 2 mode of oscillation as function of temperature. We have also developed a theory to describe the small amplitude shape oscillations of a He II drop surrounded by its saturated vapor. In our theory, we have considered two sets of boundary conditions---one where the drop does not evaporate and another in which the liquid and vapor are in thermodynamic equilibrium. We have found that both solutions give a frequency that agrees well with experiment, but that the data for the damping rate agree better with the solution without evaporation.

  2. Masking property of quantum random cipher with phase mask encryption

    NASA Astrophysics Data System (ADS)

    Sohma, Masaki; Hirota, Osamu

    2014-10-01

    The security analysis of physical encryption protocol based on coherent pulse position modulation (CPPM) originated by Yuen is one of the most interesting topics in the study of cryptosystem with a security level beyond the Shannon limit. Although the implementation of CPPM scheme has certain difficulty, several methods have been proposed recently. This paper deals with the CPPM encryption in terms of symplectic transformation, which includes a phase mask encryption as a special example, and formulates a unified security analysis for such encryption schemes. Specifically, we give a lower bound of Eve's symbol error probability using reliability function theory to ensure that our proposed system exceeds the Shannon limit. Then we assume the secret key is given to Eve after her heterodyne measurement. Since this assumption means that Eve has a great advantage in the sense of the conventional cryptography, the lower bound of her error indeed ensures the security level beyond the Shannon limit. In addition, we show some numerical examples of the security performance.

  3. 43 CFR 16.2 - Applications for helium disposition agreements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Applications for helium disposition... HELIUM § 16.2 Applications for helium disposition agreements. The application for a helium disposition... Secretary to determine that the proposal will conserve helium that will otherwise be wasted, drained,...

  4. 43 CFR 16.2 - Applications for helium disposition agreements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Applications for helium disposition... HELIUM § 16.2 Applications for helium disposition agreements. The application for a helium disposition... Secretary to determine that the proposal will conserve helium that will otherwise be wasted, drained,...

  5. 43 CFR 16.2 - Applications for helium disposition agreements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Applications for helium disposition... HELIUM § 16.2 Applications for helium disposition agreements. The application for a helium disposition... Secretary to determine that the proposal will conserve helium that will otherwise be wasted, drained,...

  6. 43 CFR 16.2 - Applications for helium disposition agreements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Applications for helium disposition... HELIUM § 16.2 Applications for helium disposition agreements. The application for a helium disposition... Secretary to determine that the proposal will conserve helium that will otherwise be wasted, drained,...

  7. 43 CFR 16.2 - Applications for helium disposition agreements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Applications for helium disposition... HELIUM § 16.2 Applications for helium disposition agreements. The application for a helium disposition... Secretary to determine that the proposal will conserve helium that will otherwise be wasted, drained,...

  8. Ras Laffan helium recovery unit 2

    NASA Astrophysics Data System (ADS)

    Fauve, Eric Arnaud; Grabié, Veronique; Grillot, David; Delcayre, Franck; Deschildre, Cindy

    2012-06-01

    In May 2010, Air Liquide was awarded a contract for the Engineering Procurement and Construction (Turnkey EPC) for a second helium recovery unit [RLH II] dedicated to the Ras Laffan refinery in Qatar. This unit will come in addition to the one [RLH I] delivered and commissioned by Air Liquide in 2005. It will increase the helium production of Qatar from 10% to 28% of worldwide production. RLH I and RLH II use Air Liquide Advanced Technologies helium liquefiers. With a production of 8 tons of liquid helium per day, the RLH I liquefier is the world largest, but not for long. Thanks to the newly developed turbine TC7, Air Liquide was able to propose for RLH II a single liquefier able to produce over 20 tons per day of liquid helium without liquid nitrogen pre-cooling. This liquefier using 6 Air Liquide turbines (TC series) will set a new record in the world of helium liquefaction.

  9. Helium recovery and purification at CHMFL

    NASA Astrophysics Data System (ADS)

    Li, J.; Meng, Q.; Ouyang, Z.; Shi, L.; Ai, X.; Chen, X.

    2017-02-01

    Currently, rising demand and declining reserves of helium have led to dramatic increases in the helium price. The High Magnetic Field Laboratory of Chinese Academy of Sciences (CHMFL) has made efforts since its foundation to increase the percentage of helium recovered. The piping network connects all the helium experimental facilities to the recovery system, and even exhaust ports of pressure relief valves and vacuum pumps are also connected. In each year, about 30,000 cubic meters helium gas is recovered. The recovery gas is purified, liquefied and supplied to the users again. This paper will provide details about the helium recovery and purification system at CHMFL, including system flowchart, components, problems and solutions.

  10. Thermodynamic properties of hydrogen-helium plasmas.

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1972-01-01

    Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.

  11. Computer studies of reemission and depth profiles for helium on molybdenum

    NASA Astrophysics Data System (ADS)

    Yamamura, Yasunori

    1987-08-01

    Adding the diffusion processes to the existing ACAT code, the reemission mechanisms and depth profiles under heavy bombardments have been investigated for 4 keV 3He + ions on molybdenum, where the ion-induced detrapping or the collisions between newly implanted helium ions and previously trapped heliums are taken into account, and the diffusion of thermalized helium atoms is numerically calculated. It is found that the reemission processes are composed of three mechanisms, i.e., ordinary particle reflection, ion-induced reemission promoted by radiation-enhanced diffusion, and thermal release due to radiation-enhanced diffusion. At low temperatures the ion-induced reemission promoted by the radiation-enhanced diffusion is the most important process. Concerning the critical dose, the helium saturation concentration and the helium retention curve, we have obtained good agreement with the experiments, but the calculated penetration depth has shown a larger values than the experimental results. The calculated reemission rate curve has a sharp peak at the critical dose or shows oscillatory behavior, which is explained explicitly by introducing the critical surface density for the ion-induced reemission.

  12. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... pressure and 70 degrees Fahrenheit temperature) of gaseous helium or 7510 liters of liquid helium delivered... provide to the Contracting Officer the following data within 10 days after the Contractor or...

  13. Energy, helium, and the future: II

    SciTech Connect

    Krupka, M.C.; Hammel, E.F.

    1980-01-01

    The importance of helium as a critical resource material has been recognized specifically by the scientific community and more generally by the 1960 Congressional mandate to institute a long-range conservation program. A major study mandated by the Energy Reorganization Act of 1974 resulted in the publication in 1975 of the document, The Energy-Related Applications of Helium, ERDA-13. This document contained a comprehensive review and analysis relating to helium resources and present and future supply/demand relationships with particular emphasis upon those helium-dependent energy-related technologies projected to be implemented in the post-2000 year time period, e.g., fusion. An updated overview of the helium situation as it exists today is presented. Since publication of ERDA-13, important changes in the data base underlying that document have occurred. The data have since been reexamined, revised, and new information included. Potential supplies of helium from both conventional and unconventional natural gas resources, projected supply/demand relationships to the year 2030 based upon a given power-generation scenario, projected helium demand for specific energy-related technologies, and the supply options (national and international) available to meet that demand are discussed. An updated review will be given of the energy requirements for the extraction of helium from natural gas as they relate to the concentration of helium. A discussion is given concerning the technical and economic feasibility of several methods available both now and conceptually possible, to extract helium from helium-lean natural gas, the atmosphere, and outer space. Finally, a brief review is given of the 1980 Congressional activities with respect to the introduction and possible passage of new helium conservation legislation.

  14. Helium cyclotron resonance within the earth's magnetosphere

    SciTech Connect

    Mauk, B.H.; McIlwain, C.E.; McPherron, R.L.

    1981-01-01

    A histogram of electromagnetic Alfven/ion cyclotron wave frequencies, sampled within the geostationary enviroment and normalized by the equatorial proton cyclotron frequency, shows a dramatic gap centered near the helium (He/sup +/) cyclotron frequency. Also, strongly cyclotron phase bunched helium ions (20--200 eV) have been observed directly within the vicinity of wave environments. These observations are interpreted as resulting from the absorption of the waves through cyclotron resonance by cool ambient populations of helium ions.

  15. Helium isotopic abundance variation in nature

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The isotopic abundance of helium in nature has been reviewed. This atomic weight value is based on the value of helium in the atmosphere, which is invariant around the world and up to a distance of 100,000 feet. Helium does vary in natural gas, volcanic rocks and gases, ocean floor sediments, waters of various types and in radioactive minerals and ores due to {alpha} particle decay of radioactive nuclides.

  16. Damage accumulation in neon implanted silicon

    SciTech Connect

    Oliviero, E.; Peripolli, S.; Amaral, L.; Fichtner, P. F. P.; Beaufort, M. F.; Barbot, J. F.; Donnelly, S. E.

    2006-08-15

    Damage accumulation in neon-implanted silicon with fluences ranging from 5x10{sup 14} to 5x10{sup 16} Ne cm{sup -2} has been studied in detail. As-implanted and annealed samples were investigated by Rutherford backscattering spectrometry under channeling conditions and by transmission electron microscopy in order to quantify and characterize the lattice damage. Wavelength dispersive spectrometry was used to obtain the relative neon content stored in the matrix. Implantation at room temperature leads to the amorphization of the silicon while a high density of nanosized bubbles is observed all along the ion distribution, forming a uniform and continuous layer for implantation temperatures higher than 250 deg.C. Clusters of interstitial defects are also present in the deeper part of the layer corresponding to the end of range of ions. After annealing, the samples implanted at temperatures below 250 deg.C present a polycrystalline structure with blisters at the surface while in the other samples coarsening of bubbles occurs and nanocavities are formed together with extended defects identified as (311) defects. The results are discussed in comparison to the case of helium-implanted silicon and in the light of radiation-enhanced diffusion.

  17. The Sensitivity of Coded Mask Telescopes

    NASA Technical Reports Server (NTRS)

    Skinner, Gerald K.

    2008-01-01

    Simple formulae are often used to estimate the sensitivity of coded mask X-ray or gamma-ray telescopes, but t,hese are strictly only applicable if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given which allows the calculation of the sensitivity. We consider certain aspects of the optimisation of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

  18. Achievements and challenges of EUV mask imaging

    NASA Astrophysics Data System (ADS)

    Davydova, Natalia; van Setten, Eelco; de Kruif, Robert; Connolly, Brid; Fukugami, Norihito; Kodera, Yutaka; Morimoto, Hiroaki; Sakata, Yo; Kotani, Jun; Kondo, Shinpei; Imoto, Tomohiro; Rolff, Haiko; Ullrich, Albrecht; Lammers, Ad; Schiffelers, Guido; van Dijk, Joep

    2014-07-01

    The impact of various mask parameters on CDU combined in a total mask budget is presented, for 22 nm lines, for reticles used for NXE:3300 qualification. Apart from the standard mask CD measurements, actinic spectrometry of multilayer is used to qualify reflectance uniformity over the image field; advanced 3D metrology is applied for absorber profile characterization including absorber height and side wall angle. The predicted mask impact on CDU is verified using actual exposure data collected on multiple NXE:3300 scanners. Mask 3D effects are addressed, manifesting themselves in best focus shifts for different structures exposed with off-axis illumination. Experimental NXE:3300 results for 16 nm dense lines and 20 nm (semi-)isolated spaces are shown: best focus range reaches 24 nm. A mitigation strategy by absorber height optimization is proposed based on experimental results of a special mask with varying absorber heights. Further development of a black image border for EUV mask is considered. The image border is a pattern free area surrounding image field preventing exposure the image field neighborhood on wafer. Normal EUV absorber is not suitable for this purpose as it has 1-3% EUV reflectance. A current solution is etching of ML down to substrate reducing EUV reflectance to <0.05%. A next step in the development of the black border is the reduction of DUV Out-of-Band reflectance (<1.5%) in order to cope with DUV light present in EUV scanners. Promising results achieved in this direction are shown.

  19. Mask Fabrication Using Electron Beam Exposure System

    NASA Astrophysics Data System (ADS)

    Watakabe, Y.; Shigetomi, A.; Morimoto, H.; Kato, T.

    1981-07-01

    This study describes the results of feature size distribution, pattern location accuracy and level to level registration error on chrominum master masks fabricated by EeBES-40. This system has the capability of high speed electron beam blanking at 40MHz, the capacity for large size masks (with 6 inch mask cassette), and the automatic cassette handling system. OEBR-100(PGMA), as the electron beam negative resist, is used for 5 inch and 6 inch chrominum masks. The chrominum etching process is used for both wet and dry plasma technology. Test patterns and 64 K bit memory TEG, as the practical pattern, are used in this study. More than 40 measurements are taken, uniformly distributed over 96 to 112mm square, and the feature size distribution is measured by a laser interferometer X-Y measuring system. Pattern location accuracy and level to level registration error are obtained using EeBES-40 quality assurance programs called MARKET/PLOTMARKET. This program operates by scanning over the resist image of the test pattern, utilizing the normal fiducial mark location hardware. The followinc results are obtained; (1) Feature size distribution within 6 inch mask : -/+0.1 μm (2) Level-to-level registration error2 : less than 0.1 pm High quality masks with about 0.02 defects/cm2 , and rapid throughput of 6 hr./10 masks using the auto-matic 10-cassette handling system are obtained.

  20. Reflective masks for extreme ultraviolet lithography

    SciTech Connect

    Nguyen, Khanh Bao

    1994-05-01

    Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for 0.15 μm wide defect lines. A long-term study of Mo/Si coating reflectivity revealed that Mo/Si coatings with Mo as the top layer suffer significant reductions in reflectivity over time due to oxidation.

  1. Intact crowding and temporal masking in dyslexia.

    PubMed

    Doron, Adi; Manassi, Mauro; Herzog, Michael H; Ahissar, Merav

    2015-01-01

    Phonological deficits in dyslexia are well documented. However, there is an ongoing discussion about whether visual deficits limit the reading skills of people with dyslexia. Here, we investigated visual crowding and backward masking. We presented a Vernier (i.e., two vertical bars slightly offset to the left or right) and asked observers to indicate the offset direction. Vernier stimuli are visually similar to letters and are strongly affected by crowding, even in the fovea. To increase task difficulty, Verniers are often followed by a mask (i.e., backward masking). We measured Vernier offset discrimination thresholds for the basic Vernier task, under crowding, and under backward masking, in students with dyslexia (n = 19) and age and intelligence matched students (n = 27). We found no group differences in any of these conditions. Controls with fast visual processing (good backward masking performance), were faster readers. By contrast, no such correlation was found among the students with dyslexia, suggesting that backward masking does not limit their reading efficiency. These findings indicate that neither elevated crowding nor elevated backward masking pose a bottleneck to reading skills of people with dyslexia.

  2. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  3. Planar InAs photodiodes fabricated using He ion implantation.

    PubMed

    Sandall, Ian; Tan, Chee Hing; Smith, Andrew; Gwilliam, Russell

    2012-04-09

    We have performed Helium (He) ion implantation on InAs and performed post implant annealing to investigate the effect on the sheet resistance. Using the transmission line model (TLM) we have shown that the sheet resistance of a p⁺ InAs layer, with a nominal doping concentration of 1x10¹⁸ cm⁻³, can increase by over 5 orders of magnitude upon implantation. We achieved a sheet resistance of 1x10⁵ Ω/Square in an 'as-implanted' sample and with subsequent annealing this can be further increased to 1x10⁷ Ω/Square. By also performing implantation on p-i-n structures we have shown that it is possible to produce planar photodiodes with comparable dark currents and quantum efficiencies to chemically etched reference mesa InAs photodiodes.

  4. Radioactive transitions in the helium isoelectronic sequence

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1971-01-01

    The principles of the atomic spectrum theory are used to quantitatively analyze radiation transitions in two-electron helium-like atomic systems. Quantum theoretical methods, describing absorption and emission of a single photon in a radiative transition between two stationary states of an atomic system, reproduced the energy level diagram for the low lying states of helium. Reliable values are obtained from accurate variationally determined two-electron nonrelativistic wave functions for radiative transition probabilities of 2 3p states in the helium isoelectric sequence, and for the 2 1s and 2 3s1 states of the helium sequence.

  5. 43 CFR 3195.35 - What happens if I have an outstanding obligation to purchase refined helium under a Helium...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... obligation to purchase refined helium under a Helium Distribution Contract? 3195.35 Section 3195.35 Public... OF THE INTERIOR MINERALS MANAGEMENT (3000) HELIUM CONTRACTS Federal Helium Supplier Requirements § 3195.35 What happens if I have an outstanding obligation to purchase refined helium under a...

  6. 43 CFR 3195.35 - What happens if I have an outstanding obligation to purchase refined helium under a Helium...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... obligation to purchase refined helium under a Helium Distribution Contract? 3195.35 Section 3195.35 Public... OF THE INTERIOR MINERALS MANAGEMENT (3000) HELIUM CONTRACTS Federal Helium Supplier Requirements § 3195.35 What happens if I have an outstanding obligation to purchase refined helium under a...

  7. 43 CFR 3195.35 - What happens if I have an outstanding obligation to purchase refined helium under a Helium...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... obligation to purchase refined helium under a Helium Distribution Contract? 3195.35 Section 3195.35 Public... OF THE INTERIOR MINERALS MANAGEMENT (3000) HELIUM CONTRACTS Federal Helium Supplier Requirements § 3195.35 What happens if I have an outstanding obligation to purchase refined helium under a...

  8. 43 CFR 3195.35 - What happens if I have an outstanding obligation to purchase refined helium under a Helium...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... obligation to purchase refined helium under a Helium Distribution Contract? 3195.35 Section 3195.35 Public... OF THE INTERIOR MINERALS MANAGEMENT (3000) HELIUM CONTRACTS Federal Helium Supplier Requirements § 3195.35 What happens if I have an outstanding obligation to purchase refined helium under a...

  9. 43 CFR 3195.20 - Who must purchase major helium requirements from Federal helium suppliers?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Who must purchase major helium requirements from Federal helium suppliers? 3195.20 Section 3195.20 Public Lands: Interior Regulations Relating... (3000) HELIUM CONTRACTS Federal Agency Requirements § 3195.20 Who must purchase major...

  10. 43 CFR 3195.20 - Who must purchase major helium requirements from Federal helium suppliers?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Who must purchase major helium requirements from Federal helium suppliers? 3195.20 Section 3195.20 Public Lands: Interior Regulations Relating... (3000) HELIUM CONTRACTS Federal Agency Requirements § 3195.20 Who must purchase major...

  11. 43 CFR 3195.20 - Who must purchase major helium requirements from Federal helium suppliers?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Who must purchase major helium requirements from Federal helium suppliers? 3195.20 Section 3195.20 Public Lands: Interior Regulations Relating... (3000) HELIUM CONTRACTS Federal Agency Requirements § 3195.20 Who must purchase major...

  12. 43 CFR 3195.20 - Who must purchase major helium requirements from Federal helium suppliers?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Who must purchase major helium requirements from Federal helium suppliers? 3195.20 Section 3195.20 Public Lands: Interior Regulations Relating... (3000) HELIUM CONTRACTS Federal Agency Requirements § 3195.20 Who must purchase major...

  13. When Bad Masks Turn Good

    NASA Astrophysics Data System (ADS)

    Abraham, Roberto G.

    In keeping with the spirit of a meeting on ‘masks,' this talk presents two short stories on the theme of dust. In the first, dust plays the familiar role of the evil obscurer, the enemy to bedefeated by the cunning observer in order to allow a key future technology (adaptive optics) to be exploited fully by heroic astronomers. In the second story, dust itself emerges as the improbable hero, in the form of a circumstellar debris disks. I will present evidence of a puzzling near-infrared excess in the continuum of high-redshift galaxies and will argue that the seemingly improbable origin of this IR excess is a population of young circumstellar disks formed around high-mass stars in distant galaxies. Assuming circumstellar disks extend down to lower masses,as they do in our own Galaxy, the excess emission presents us with an exciting opportunity to measure the formation rate of planetary systems in distant galaxies at cosmic epochs before our own solar system formed.

  14. Investigation of EUV haze defect: molecular behaviors of mask cleaning chemicals on EUV mask surfaces

    NASA Astrophysics Data System (ADS)

    Choi, Jaehyuck; Novak, Steve; Kandel, Yudhishthir; Denbeaux, Greg; Lee, Han-shin; Ma, Andy; Goodwin, Frank

    2012-03-01

    Photo-induced defects (or haze defects) on 193nm optic masks (haze defects) have been a serious problem not only to reticle engineers working for mask manufacturing and handling but also to photo-lithography engineers. The most widely accepted explanation of the root causes of haze defects is the cleaning chemical residues remaining on the mask surface and unavoidable outgassed molecules that outgas from pellicle materials when exposed to 193nm radiation. These have been significant challenges for reticle cleaning engineers who need to use cleaning chemicals whose residues do not lead to progressive defect formation on the mask and to find improved materials to minimize pellicle outgassing. It is assumed that contamination generation on EUV masks would have a higher probability than on optic masks, primarily since EUV masks are not protected by a pellicle and amorphous carbon films can accumulate during exposure to EUV light. While there is potential to mitigate the generation of carbon contamination by improving the exposure tool environment and removing carbon films using in-situ atomic hydrogen cleaning, it is not yet clear whether the reaction of mask cleaning chemicals to EUV radiation will lead to creation of progressive defects on EUV mask surfaces. With the work to being done it has been observed that carbon contamination on EUV masks dominates any effects of solvent chemicals under normal environmental or exposure conditions (from atmospheric pressure up to a vacuum level of 10-6 Torr) during EUV exposure. However, it is still unknown whether residual cleaning chemicals will provide a nucleus for progressive defect formation during exposure. This lack of understanding needs to be addressed by the industry as EUV masks are expected to undergo more frequent cleaning cycles. In this work, we will report on an investigation of the molecular behavior of cleaning chemicals on EUV mask surfaces during EUV exposure. Movement (e.g., migration or aggregation) of

  15. Dose dependence of helium bubble formation in nano-engineered SiC at 700 °C

    NASA Astrophysics Data System (ADS)

    Chen, C.-H.; Zhang, Y.; Wang, Y.; Crespillo, M. L.; Fontana, C. L.; Graham, J. T.; Duscher, G.; Shannon, S. C.; Weber, W. J.

    2016-04-01

    Knowledge of radiation-induced helium bubble nucleation and growth in SiC is essential for applications in fusion and fission environments. Here we report the evolution of microstructure in nano-engineered (NE) 3C SiC, pre-implanted with helium, under heavy ion irradiation at 700 °C up to doses of 30 displacements per atom (dpa). Elastic recoil detection analysis confirms that the as-implanted helium depth profile does not change under irradiation to 30 dpa at 700 °C. While the helium bubble size distribution becomes narrower with increasing dose, the average size of bubbles remains unchanged and the density of bubbles increases somewhat with dose. These results are consistent with a long helium bubble incubation process under continued irradiation at 700 °C up to 30 dpa, similar to that reported under dual and triple beam irradiation at much higher temperatures. The formation of bubbles at this low temperature is enhanced by the nano-layered stacking fault structure in the NE SiC, which enhances point defect mobility parallel to the stacking faults. This stacking fault structure is stable at 700 °C up to 30 dpa and suppresses the formation of dislocation loops normally observed under these irradiation conditions.

  16. Suppression effect of nano-sized oxide particles on helium irradiation hardening in F82H-ODS steel

    NASA Astrophysics Data System (ADS)

    Chen, S.; Wang, Y.; Tadaki, K.; Hashimoto, N.; Ohnuki, S.

    2014-12-01

    Helium implantation was performed to investigate irradiation hardening in ferritic/martensitic steels. Depth dependence of nano-hardness was obtained using a Berkovich nano-indenter, and then nano-hardness was extracted from Nix-Gao model. The correlation between irradiation hardening and the concentration 500-2000 appm of helium was plotted. Nano-hardness increases as a function of helium concentration. F82H-ODS with a higher nano-hardness provides a lower irradiation hardening than F82H-IEA. Cross-sectional transmission electron microscopy (XTEM) revealed that cavities with a uniform distribution were formed after helium implantation at 2000 appm helium concentration, showing a mean size of 1.1 nm with an average number density of 4.9 × 1023 m-3 in F82H-IEA and 1.3 nm with 7.4 × 1023 m-3 in F82H-ODS. Orowan model was applied to evaluate the hardening from dispersed cavities. The significant difference of hardening between calculation and nano-indentation result of F82H-ODS indicates that oxide particles may shield the hardening effect from cavities because of the complex multi-interaction.

  17. Dose dependence of helium bubble formation in nano-engineered SiC at 700 °C

    DOE PAGES

    Chen, Chien -Hung; Zhang, Yanwen; Wang, Yongqiang; ...

    2016-02-03

    Knowledge of radiation-induced helium bubble nucleation and growth in SiC is essential for applications in fusion and fission environments. Here we report the evolution of microstructure in nano-engineered (NE) 3C SiC, pre-implanted with helium, under heavy ion irradiation at 700 °C up to doses of 30 displacements per atom (dpa). Elastic recoil detection analysis confirms that the as-implanted helium depth profile does not change under irradiation to 30 dpa at 700 °C. While the helium bubble size distribution becomes narrower with increasing dose, the average size of bubbles remains unchanged and the density of bubbles increases somewhat with dose. Thesemore » results are consistent with a long helium bubble incubation process under continued irradiation at 700 °C up to 30 dpa, similar to that reported under dual and triple beam irradiation at much higher temperatures. The formation of bubbles at this low temperature is enhanced by the nano-layered stacking fault structure in the NE SiC, which enhances point defect mobility parallel to the stacking faults. Here, this stacking fault structure is stable at 700 °C up to 30 dpa and suppresses the formation of dislocation loops normally observed under these irradiation conditions.« less

  18. Dose dependence of helium bubble formation in nano-engineered SiC at 700 °C

    SciTech Connect

    Chen, Chien -Hung; Zhang, Yanwen; Wang, Yongqiang; Crespillo, Miguel L.; Fontana, Cristiano L.; Graham, Joseph T.; Duscher, Gerd; Shannon, Steven C.; Weber, William J.

    2016-02-03

    Knowledge of radiation-induced helium bubble nucleation and growth in SiC is essential for applications in fusion and fission environments. Here we report the evolution of microstructure in nano-engineered (NE) 3C SiC, pre-implanted with helium, under heavy ion irradiation at 700 °C up to doses of 30 displacements per atom (dpa). Elastic recoil detection analysis confirms that the as-implanted helium depth profile does not change under irradiation to 30 dpa at 700 °C. While the helium bubble size distribution becomes narrower with increasing dose, the average size of bubbles remains unchanged and the density of bubbles increases somewhat with dose. These results are consistent with a long helium bubble incubation process under continued irradiation at 700 °C up to 30 dpa, similar to that reported under dual and triple beam irradiation at much higher temperatures. The formation of bubbles at this low temperature is enhanced by the nano-layered stacking fault structure in the NE SiC, which enhances point defect mobility parallel to the stacking faults. Here, this stacking fault structure is stable at 700 °C up to 30 dpa and suppresses the formation of dislocation loops normally observed under these irradiation conditions.

  19. Helium II level measurement techniques

    NASA Astrophysics Data System (ADS)

    Celik, D.; Hilton, D. K.; Zhang, T.; Van Sciver, S. W.

    2001-05-01

    In this paper, a survey of cryogenic liquid level measurement techniques applicable to superfluid helium (He II) is given. The survey includes both continuous and discrete measurement techniques. A number of different probes and controlling circuits for this purpose have been described in the literature. They fall into one of the following categories: capacitive liquid level gauges, superconducting wire liquid level gauges, thermodynamic (heat transfer-based) liquid level gauges, resistive gauges, ultrasound and transmission line-based level detectors. The present paper reviews these techniques and their suitability for He II service. In addition to these methods, techniques for measuring the total liquid volume and mass gauging are also discussed.

  20. Superfluid Helium Tanker (SFHT) study

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The accomplishments and recommendations of the two-phase Superfluid Helium Tanker (SFHT) study are presented. During the first phase of the study, the emphasis was on defining a comprehensive set of user requirements, establishing SFHT interface parameters and design requirements, and selecting a fluid subsystem design concept. During the second phase, an overall system design concept was constructed based on appropriate analyses and more detailed definition of requirements. Modifications needed to extend the baseline for use with cryogens other than SFHT have been determined, and technology development needs related to the recommended design have been assessed.

  1. Helium bubble bursting in tungsten

    SciTech Connect

    Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.

    2013-12-28

    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.

  2. Quantum Dynamics of Helium Clusters

    DTIC Science & Technology

    1993-03-01

    helium clusters [10-12]. (10) DMC starts with the time - dependent Schr ~ dinger equation in imaginary time and has been employed most- The approximate...bound. (For example, the binding values may be computed by the Metropolis approach . energy of He 3 is five times greater than that of 1l1lie I We first...or four times for computational effort. If this is also the case with the the larger clusters) its original size. If the maximum en- DMC approach

  3. A study of defects on EUV mask using blank inspection, patterned mask inspection, and wafer inspection

    SciTech Connect

    Huh, S.; Ren, L.; Chan, D.; Wurm, S.; Goldberg, K. A.; Mochi, I.; Nakajima, T.; Kishimoto, M.; Ahn, B.; Kang, I.; Park, J.-O.; Cho, K.; Han, S.-I.; Laursen, T.

    2010-03-12

    The availability of defect-free masks remains one of the key challenges for inserting extreme ultraviolet lithography (EUVL) into high volume manufacturing. yet link data is available for understanding native defects on real masks. In this paper, a full-field EUV mask is fabricated to investigate the printability of various defects on the mask. The printability of defects and identification of their source from mask fabrication to handling were studied using wafer inspection. The printable blank defect density excluding particles and patterns is 0.63 cm{sup 2}. Mask inspection is shown to have better sensitivity than wafer inspection. The sensitivity of wafer inspection must be improved using through-focus analysis and a different wafer stack.

  4. Active Mask Segmentation of Fluorescence Microscope Images

    PubMed Central

    Srinivasa, Gowri; Fickus, Matthew C.; Guo, Yusong; Linstedt, Adam D.; Kovačević, Jelena

    2009-01-01

    We propose a new active mask algorithm for the segmentation of fluorescence microscope images of punctate patterns. It combines the (a) flexibility offered by active-contour methods, (b) speed offered by multiresolution methods, (c) smoothing offered by multiscale methods, and (d) statistical modeling offered by region-growing methods into a fast and accurate segmentation tool. The framework moves from the idea of the “contour” to that of “inside and outside”, or, masks, allowing for easy multidimensional segmentation. It adapts to the topology of the image through the use of multiple masks. The algorithm is almost invariant under initialization, allowing for random initialization, and uses a few easily tunable parameters. Experiments show that the active mask algorithm matches the ground truth well, and outperforms the algorithm widely used in fluorescence microscopy, seeded watershed, both qualitatively as well as quantitatively. PMID:19380268

  5. Masking properties of APD communication systems

    NASA Astrophysics Data System (ADS)

    Fernandez, J. G.; Larrondo, H. A.; Slavin, H. A.; Levin, D. G.; Hidalgo, R. M.; Rivera, R. R.

    2003-10-01

    In this paper, we explore the ability of wavelet multilevel analysis to unmask the information hidden in a chaotic mask. This digital filtering technique has been recently reported as particularly well suited for the detection of coherent structures. In a recent paper the capability of wavelets to unmask a message, in cases where a chaotic signal is just added to the information, has also been demonstrated. The case of an active passive decomposition scheme, where message is mixed with the chaotic signal, is studied here. A representative case employing Daubechies wavelets and a typical Rossler-oscillator-based communication system is reported. Using a time scaling parameter modifies the spectrum of the mask. The results show that wavelets are effective only in particular cases with poor masking. The fast Fourier transform analysis demonstrates that the spectrum of the chaotic mask shows no holes and then other digital filtering techniques such as Wiener filters or comb filters must also been disregarded.

  6. Correction of deflection under mask's own weight by bending mask technology

    NASA Astrophysics Data System (ADS)

    Yagami, Takashi; Kambayashi, Takashi; Azumi, Minako

    2016-10-01

    It is known that the photomask substrate deflects when the mask is set on the frame and the deflection is an obstacle to light exposure. In this study, we introduce "the bending mask" to cancel out the deflection. The surface of the bending mask has the height distribution in advance to cancel out the deflection, owing to Nikon's accurate polishing technology and Nikon's accurate measurement machine.

  7. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, Bill R.; Ashley, Paul R.; Buchal, Christopher J.

    1989-01-01

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO.sub.3 crystals are implanted with high concentrations of Ti dopant at ion energies of about 350 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000.degree. C. produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality single crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguides properties.

  8. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

    1987-03-24

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

  9. Design of subcooled helium II refrigerator with helium-3 cold compressor

    SciTech Connect

    Kato, D.; Saji, N.; Ohya, H.; Asakura, H.; Kubota, M.; Kaneko, Y.; Nagai, S.

    1994-12-31

    This paper will study the possibility of a He II refrigerator made up of three cold compressors by making use of helium-3 characteristics. This system is compact enough to fit inside a small cold box, so it can be easily connected with an existing helium-4 refrigerator. The authors designed the compressors, calculated the He II cooling capacity, 4.4 K refrigeration load, required inventory of helium-3, and Carnot efficiency. Though helium-3 is expensive, the required inventory of helium-3 to be filled inside this He II refrigerator was calculated to be small enough to prove practicality of constructing this refrigerator.

  10. Inspection of lithographic mask blanks for defects

    DOEpatents

    Sommargren, Gary E.

    2001-01-01

    A visible light method for detecting sub-100 nm size defects on mask blanks used for lithography. By using optical heterodyne techniques, detection of the scattered light can be significantly enhanced as compared to standard intensity detection methods. The invention is useful in the inspection of super-polished surfaces for isolated surface defects or particulate contamination and in the inspection of lithographic mask or reticle blanks for surface defects or bulk defects or for surface particulate contamination.

  11. Achromatic phase shifting focal plane masks

    NASA Astrophysics Data System (ADS)

    Newman, Kevin

    The search for life on other worlds is an exciting scientific endeavor that could change the way we perceive our place in the universe. Thousands of extrasolar planets have been discovered using indirect detection techniques. One of the most promising methods for discovering new exoplanets and searching for life is direct imaging with a coronagraph. Exoplanet coronagraphy of Earth-like planets is a challenging task, but we have developed many of the tools necessary to make it feasible. The Phase-Induced Amplitude Apodization (PIAA) Coronagraph is one of the highest-performing architectures for direct exoplanet imaging. With a complex phase-shifting focal plane mask, the PIAA Complex Mask Coronagraph (PIAACMC) can approach the theoretical performance limit for any direct detection technique. The architecture design is flexible enough to be applied to any arbitrary aperture shape, including segmented and obscured apertures. This is an important feature for compatibility with next-generation ground and space-based telescopes. PIAA and PIAACMC focal plane masks have been demonstrated in monochromatic light. An important next step for high-performance coronagraphy is the development of broadband phase-shifting focal plane masks. In this dissertation, we present an algorithm for designing the PIAA and PIAACMC focal plane masks to operate in broadband. We also demonstrate manufacturing of the focal plane masks, and show laboratory results. We use simulations to show the potential performance of the coronagraph system, and the use of wavefront control to correct for mask manufacturing errors. Given the laboratory results and simulations, we show new areas of exoplanet science that can potentially be explored using coronagraph technology. The main conclusion of this dissertation is that we now have the tools required to design and manufacture PIAA and PIAACMC achromatic focal plane masks. These tools can be applied to current and future telescope systems to enable new

  12. Incomplete figure perception and invisible masking.

    PubMed

    Chikhman, Valery; Shelepin, Yuri; Foreman, Nigel; Merkuljev, Aleksey; Pronin, Sergey

    2006-01-01

    The Gollin test (measuring recognition thresholds for fragmented line drawings of everyday objects and animals) has traditionally been regarded as a test of incomplete figure perception or 'closure', though there is a debate about how such closure is achieved. Here, figural incompleteness is considered to be the result of masking, such that absence of contour elements of a fragmented figure is the result of the influence of an 'invisible' mask. It is as though the figure is partly obscured by a mask having parameters identical to those of the background. This mask is 'invisible' only consciously, but for the early stages of visual processing it is real and has properties of multiplicative noise. Incomplete Gollin figures were modeled as the figure covered by the mask with randomly distributed transparent and opaque patches. We adjusted the statistical characteristics of the contour image and empty noise patches and processed those using spatial and spatial-frequency measures. Across 73 figures, despite inter-subject variability, mean recognition threshold was always approximately 15% of total contour in naive observers. Recognition worsened with increasing spectral similarity between the figure and the 'invisible' mask. Near threshold, the spectrum of the fragmented image was equally similar to that of the 'invisible' mask and complete image. The correlation between spectral parameters of figures at threshold and complete figures was greatest for figures that were most easily recognised. Across test sessions, thresholds reduced when either figure or mask parameters were familiar. We argue that recognition thresholds for Gollin stimuli in part reflect the extraction of signal from noise.

  13. No masking between test and mask components in perceptually different depth planes.

    PubMed

    Hibbeler, Patrick J; Olzak, Lynn A

    2011-01-01

    2-D cues to perceived depth organization have been used to segregate test and mask stimulus components in a discrimination task. Observers made either spatial-frequency or orientation judgments on a rectangular test component by itself or in the presence of constant rectangular masks. There were two basic masking conditions: same-plane or different-plane. In the same-plane conditions, the test components and masks are perceived as existing in the same depth plane. In the different-plane conditions, the test and mask components are perceived to exist in different depth planes. The perception of different depth planes was achieved by using perceived occlusion, which could place either component closer or further from the observer. The results suggest that when test and mask components are separated into different depth planes they no longer influence one another. This effect could be observed in either depth organization, test components in front of the masks or mask components in front of the test. These results indicate that the figure-ground organization of components is not important. Only the designation as existing in the same or different depth planes affects whether or not a mask is effective.

  14. Helium and neon abundances and compositions in cometary matter.

    PubMed

    Marty, Bernard; Palma, Russell L; Pepin, Robert O; Zimmermann, Laurent; Schlutter, Dennis J; Burnard, Peter G; Westphal, Andrew J; Snead, Christopher J; Bajt, Sasa; Becker, Richard H; Simones, Jacob E

    2008-01-04

    Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet 81P/Wild 2 are indisputable cometary matter available for laboratory study. Here we report measurements of noble gases in Stardust material. Neon isotope ratios are within the range observed in "phase Q," a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays 3He/4He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are probably carried in high-temperature igneous grains similar to particles found in other Stardust studies. Collectively, the evidence points to gas acquisition in a hot, high ion-flux nebular environment close to the young Sun.

  15. Helium and Neon Abundances and Compositions in Cometary Matter

    SciTech Connect

    Marty, B; Palma, R L; Pepin, R O; Zimmmermann, L; Schlutter, D J; Burnard, P G; Westphal, A J; Snead, C J; Bajt, S; Becker, R H; Simones, J E

    2007-10-15

    Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet Wild 2 are indisputable cometary matter available for laboratory study. Here they report measurements of noble gases in Stardust material. neon isotope ratios are within the range observed in 'phase Q', a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays {sup 3}He/{sup 4}He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are carried in high temperature igneous grains similar to particles found in other Stardust studies. Collectively the evidence points to gas acquisition in a hot, high ion flux nebular environment close to the young Sun.

  16. Mask cost of ownership for advanced lithography

    NASA Astrophysics Data System (ADS)

    Muzio, Edward G.; Seidel, Philip K.

    2000-07-01

    As technology advances, becoming more difficult and more expensive, the cost of ownership (CoO) metric becomes increasingly important in evaluating technical strategies. The International SEMATECH CoC analysis has steadily gained visibility over the past year, as it attempts to level the playing field between technology choices, and create a fair relative comparison. In order to predict mask cots for advanced lithography, mask process flows are modeled using bets-known processing strategies, equipment cost, and yields. Using a newly revised yield mode, and updated mask manufacture flows, representative mask flows can be built. These flows are then used to calculate mask costs for advanced lithography down to the 50 nm node. It is never the goal of this type of work to provide absolute cost estimates for business planning purposes. However, the combination of a quantifiable yield model with a clearly defined set of mask processing flows and a cost model based upon them serves as an excellent starting point for cost driver analysis and process flow discussion.

  17. VSP wave separation by adaptive masking filters

    NASA Astrophysics Data System (ADS)

    Rao, Ying; Wang, Yanghua

    2016-06-01

    In vertical seismic profiling (VSP) data processing, the first step might be to separate the down-going wavefield from the up-going wavefield. When using a masking filter for VSP wave separation, there are difficulties associated with two termination ends of the up-going waves. A critical challenge is how the masking filter can restore the energy tails, the edge effect associated with these terminations uniquely exist in VSP data. An effective strategy is to implement masking filters in both τ-p and f-k domain sequentially. Meanwhile it uses a median filter, producing a clean but smooth version of the down-going wavefield, used as a reference data set for designing the masking filter. The masking filter is implemented adaptively and iteratively, gradually restoring the energy tails cut-out by any surgical mute. While the τ-p and the f-k domain masking filters target different depth ranges of VSP, this combination strategy can accurately perform in wave separation from field VSP data.

  18. Helium Speech: An Application of Standing Waves

    ERIC Educational Resources Information Center

    Wentworth, Christopher D.

    2011-01-01

    Taking a breath of helium gas and then speaking or singing to the class is a favorite demonstration for an introductory physics course, as it usually elicits appreciative laughter, which serves to energize the class session. Students will usually report that the helium speech "raises the frequency" of the voice. A more accurate description of the…

  19. Paramagnetic Attraction of Impurity-Helium Solids

    NASA Technical Reports Server (NTRS)

    Bernard, E. P.; Boltnev, R. E.; Khmelenko, V. V.; Lee, D. M.

    2003-01-01

    Impurity-helium solids are formed when a mixture of impurity and helium gases enters a volume of superfluid helium. Typical choices of impurity gas are hydrogen deuteride, deuterium, nitrogen, neon and argon, or a mixture of these. These solids consist of individual impurity atoms and molecules as well as clusters of impurity atoms and molecules covered with layers of solidified helium. The clusters have an imperfect crystalline structure and diameters ranging up to 90 angstroms, depending somewhat on the choice of impurity. Immediately following formation the clusters aggregate into loosely connected porous solids that are submerged in and completely permeated by the liquid helium. Im-He solids are extremely effective at stabilizing high concentrations of free radicals, which can be introduced by applying a high power RF dis- charge to the impurity gas mixture just before it strikes the super fluid helium. Average concentrations of 10(exp 19) nitrogen atoms/cc and 5 x 10(exp 18) deuterium atoms/cc can be achieved this way. It shows a typical sample formed from a mixture of atomic and molecular hydrogen and deuterium. It shows typical sample formed from atomic and molecular nitrogen. Much of the stability of Im-He solids is attributed to their very large surface area to volume ratio and their permeation by super fluid helium. Heat resulting from a chance meeting and recombination of free radicals is quickly dissipated by the super fluid helium instead of thermally promoting the diffusion of other nearby free radicals.

  20. Theoretical model of the helium pinhole microscope

    NASA Astrophysics Data System (ADS)

    Palau, Adrià Salvador; Bracco, Gianangelo; Holst, Bodil

    2016-12-01

    In recent years, the development of neutral helium microscopes has gained increasing interest. The low energy, charge neutrality, and inertness of the helium atoms makes helium microscopy an attractive candidate for the imaging of a range of samples. The simplest neutral helium microscope is the so-called pinhole microscope. It consists of a supersonic expansion helium beam collimated by two consecutive apertures (skimmer and pinhole), which together determine the beam spot size and hence the resolution at a given working distance to the sample. Due to the high ionization potential of neutral helium atoms, it is difficult to build efficient helium detectors. Therefore, it is crucial to optimize the microscope design to maximize the intensity for a given resolution and working distance. Here we present an optimization model for the helium pinhole microscope system. We show that for a given resolution and working distance, there is a single intensity maximum. Further we show that with present-day state-of-the-art detector technology (ionization efficiency 1 ×10-3 ), a resolution of the order of 600 nm at a working distance of 3 mm is possible. In order to make this quantification, we have assumed a Lambertian reflecting surface and calculated the beam spot size that gives a signal 100 cts/s within a solid angle of 0.02 π sr, following an existing design. Reducing the working distance to the micron range leads to an improved resolution of around 40 nm.

  1. LOX Tank Helium Removal for Propellant Scavenging

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2009-01-01

    System studies have shown a significant advantage to reusing the hydrogen and oxygen left in these tanks after landing on the Moon in fuel cells to generate power and water for surface systems. However in the current lander concepts, the helium used to pressurize the oxygen tank can substantially degrade fuel cell power and water output by covering the reacting surface with inert gas. This presentation documents an experimental investigation of methods to remove the helium pressurant while minimizing the amount of the oxygen lost. This investigation demonstrated that significant quantities of Helium (greater than 90% mole fraction) remain in the tank after draining. Although a single vent cycle reduced the helium quantity, large amounts of helium remained. Cyclic venting appeared to be more effective. Three vent cycles were sufficient to reduce the helium to small (less than 0.2%) quantities. Two vent cycles may be sufficient since once the tank has been brought up to pressure after the second vent cycle the helium concentration has been reduced to the less than 0.2% level. The re-pressurization process seemed to contribute to diluting helium. This is as expected since in order to raise the pressure liquid oxygen must be evaporated. Estimated liquid oxygen loss is on the order of 82 pounds (assuming the third vent cycle is not required).

  2. On the origins of trapped helium, neon and argon isotopic variations in meteorites. I - Gas-rich meteorites, lunar soil and breccia. II - Carbonaceous meteorites.

    NASA Technical Reports Server (NTRS)

    Black, D. C.

    1972-01-01

    Data are presented from stepwise heating experiments and total extractions on five meteorites: Kapoeta, Fayetteville, Holman Island, Cee Vee, and Pultusk. These data reveal the presence of four isotopically distinct trapped neon components. A comparison of trapped neon with trapped helium and argon in bulk analyses indicates the existence of correlated helium, neon and argon isotopic structures. Component B is attributed primarily to direct implantation of rare gas ions by the present day solar wind. Component C is identified with directly implanted low energy (1-10 Mev/n) solar flare rare gases. Component D is associated with rare gas ions implanted in meteoritic material by the primitive, pre-main sequence, solar wind. A fourth component, observed only in Kapoeta and the lunar fines and breccia, is tentatively attributed to parent body 'atmospheric' ions implanted in surface material by a solar wind induced electric field.

  3. 42 CFR 84.117 - Gas mask containers; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Gas mask containers; minimum requirements. 84.117... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.117 Gas mask containers; minimum requirements. (a) Gas masks shall be equipped with a...

  4. 42 CFR 84.117 - Gas mask containers; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Gas mask containers; minimum requirements. 84.117... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.117 Gas mask containers; minimum requirements. (a) Gas masks shall be equipped with a...

  5. 42 CFR 84.117 - Gas mask containers; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Gas mask containers; minimum requirements. 84.117... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.117 Gas mask containers; minimum requirements. (a) Gas masks shall be equipped with a...

  6. 42 CFR 84.117 - Gas mask containers; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Gas mask containers; minimum requirements. 84.117... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.117 Gas mask containers; minimum requirements. (a) Gas masks shall be equipped with a...

  7. Out of Their Heads: Developing the Character behind the Mask.

    ERIC Educational Resources Information Center

    Lecure, Bruce

    1996-01-01

    Discusses mask building as a theatrical exercise. Provides a simple method for building masks. Outlines a format for the classes that follow mask construction, in which a character is gradually built to suit the finished mask, including the birthing process, physical character and voice development, getting to know the character, and what happens…

  8. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  9. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  10. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  11. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  12. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  13. 37 CFR 211.3 - Mask work fees.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Mask work fees. 211.3 Section... PROCEDURES MASK WORK PROTECTION § 211.3 Mask work fees. (a) Section 201.3 of this chapter prescribes the fees or charges established by the Register of Copyrights for services relating to mask works. (b)...

  14. Short Implants: New Horizon in Implant Dentistry.

    PubMed

    Jain, Neha; Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-09-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration.

  15. Short Implants: New Horizon in Implant Dentistry

    PubMed Central

    Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-01-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

  16. Forward-Masking Patterns Produced by Symmetric and Asymmetric Pulse Shapes in Electric Hearing

    PubMed Central

    MACHEREY, OLIVIER; van WIERINGEN, ASTRID; CARLYON, ROBERT P.; DHOOGE, INGEBORG; WOUTERS, JAN

    2010-01-01

    Two forward-masking experiments were conducted with six cochlear implant listeners to test whether asymmetric pulse shapes would improve the place-specificity of stimulation compared to symmetric ones. The maskers were either cathodic-first symmetric biphasic, pseudomonophasic (i.e. with a second anodic phase longer and lower in amplitude than the first phase), or “delayed pseudomonophasic” (identical to pseudomonophasic but with an inter-phase gap) stimuli. In Experiment 1, forward-masking patterns for monopolar maskers were obtained by keeping each masker fixed on a middle electrode of the array and measuring the masked thresholds of a monopolar signal presented on several other electrodes. The results were very variable and no difference between pulse shapes was found. In Experiment 2, six maskers were used in a wide bipolar (BP + 9) configuration: the same three pulse shapes as in Experiment 1, either cathodic-first relative to the most apical or relative to the most basal electrode of the bipolar channel. The pseudomonophasic masker showed a stronger excitation proximal to the electrode of the bipolar pair for which the short, high-amplitude phase was anodic. However, no difference was obtained with the symmetric and, more surprisingly, with the delayed pseudomonophasic maskers. Implications for cochlear implant design are discussed. PMID:20058980

  17. Cellular effects of helium in different organs.

    PubMed

    Oei, Gezina T M L; Weber, Nina C; Hollmann, Markus W; Preckel, Benedikt

    2010-06-01

    Experimental research in cardiac and neuronal tissue has shown that besides volatile anesthetics and xenon, the nonanesthetic noble gas helium also reduces ischemia-reperfusion damage. Even though the distinct mechanisms of helium-induced organ protection are not completely unraveled, several signaling pathways have been identified. Beside the protective effects on heart and brain that are mainly obtained by different pre- and postconditioning protocols, helium also exerts effects in the lungs, the immune system, and the blood vessels. Obviously, this noble gas is biochemically not inert and exerts biologic effects, although until today the question remains open on how these changes are mediated. Because of its favorable characteristics and the lack of hemodynamic side effects, helium is suitable for use also in critically ill patients. This review covers the cellular effects of helium, which may lead to new clinical strategies of tissue salvage in ischemia-reperfusion situations, both within and outside the perioperative setting.

  18. Cryogenic helium 2 systems for space applications

    NASA Technical Reports Server (NTRS)

    Urban, E.; Katz, L.; Hendricks, J.; Karr, G.

    1978-01-01

    Two cryogenic systems are described which will provide cooling for experiments to be flown on Spacelab 2 in the early 1980's. The first system cools a scanning infrared telescope by the transfer of cold helium gas from a separate superfluid helium storage dewar. The flexible design permits the helium storage dewar and transfer assembly to be designed independent of the infrared experiment. Where possible, modified commerical apparatus is used. The second cryogenic system utilizes a specially designed superfluid dewar in which a superfluid helium experiment chamber is immersed. Each dewar system employs a porous plug as a phase separator to hold the liquid helium within the dewar and provide cold gas to a vent line. To maintain the low vapor pressure of the superfluid, each system requires nearly continuous prelaunch vacuum pump service, and each will vent to space during the Spacelab 2 flight.

  19. Ligand-induced Epitope Masking

    PubMed Central

    Mould, A. Paul; Askari, Janet A.; Byron, Adam; Takada, Yoshikazu; Jowitt, Thomas A.; Humphries, Martin J.

    2016-01-01

    We previously demonstrated that Arg-Gly-Asp (RGD)-containing ligand-mimetic inhibitors of integrins are unable to dissociate pre-formed integrin-fibronectin complexes (IFCs). These observations suggested that amino acid residues involved in integrin-fibronectin binding become obscured in the ligand-occupied state. Because the epitopes of some function-blocking anti-integrin monoclonal antibodies (mAbs) lie near the ligand-binding pocket, it follows that the epitopes of these mAbs may become shielded in the ligand-occupied state. Here, we tested whether function-blocking mAbs directed against α5β1 can interact with the integrin after it forms a complex with an RGD-containing fragment of fibronectin. We showed that the anti-α5 subunit mAbs JBS5, SNAKA52, 16, and P1D6 failed to disrupt IFCs and hence appeared unable to bind to the ligand-occupied state. In contrast, the allosteric anti-β1 subunit mAbs 13, 4B4, and AIIB2 could dissociate IFCs and therefore were able to interact with the ligand-bound state. However, another class of function-blocking anti-β1 mAbs, exemplified by Lia1/2, could not disrupt IFCs. This second class of mAbs was also distinguished from 13, 4B4, and AIIB2 by their ability to induce homotypic cell aggregation. Although the epitope of Lia1/2 was closely overlapping with those of 13, 4B4, and AIIB2, it appeared to lie closer to the ligand-binding pocket. A new model of the α5β1-fibronectin complex supports our hypothesis that the epitopes of mAbs that fail to bind to the ligand-occupied state lie within, or very close to, the integrin-fibronectin interface. Importantly, our findings imply that the efficacy of some therapeutic anti-integrin mAbs could be limited by epitope masking. PMID:27484800

  20. Optical inspection of EPL stencil masks

    NASA Astrophysics Data System (ADS)

    Welsh, James; McCallum, Martin; Okada, Masashi

    2003-06-01

    We are now at a major junction in lithography where non-optical lithographies, such as Electron Projection Lithography (EPL) [1], are being introduced. The mask used in EPL is a non-transparent silicon substrate with a thin silicon (~2μm) membrane with openings for electrons to pass through acting as a scatterer. This must be inspected as defects may cause printable defects. Initial mask inspection work has used SEM inspection to find these defects. However, we have historically used optical mask inspection tools, utilising wavelengths at or above what we are using for imaging, to qualify masks. This technology has been increasingly difficult to sustain as we have moved from imaging using mercury lamp based sources to pulsed excimer laser based sources that are not very suited to the inspection imaging. Indeed, review of defects found has moved from optical microscopes to SEM based tools. Inspection tools have also evolved, with the first SEM based mask inspection tools being developed to find the smallest defects, however these have the penalty of very low throughput. We will show the potential of using optical systems for the transmissive inspection of these EPL masks. The high potential of existing tools will be shown together with the need for a next generation of inspection tools. We will show that simulations indicate that an inspection source with 193nm wavelength would be required for the detection of 50nm defects on a mask used to print 70nm dense lines. It will also be shown how the position of the defect within the membrane greatly influences detection as well as the implications of moving to a thinner silicon membrane.

  1. The Intervenor Effect in Masked Priming: How Does Masked Priming Survive across an Intervening Word?

    ERIC Educational Resources Information Center

    Forster, Kenneth I.

    2009-01-01

    Four masked priming experiments are reported investigating the effect of inserting an unrelated word between the masked prime and the target. When the intervening word is visible, identity priming is reduced to the level of one-letter-different form priming, but form priming is largely unaffected. However, when the intervening word is itself…

  2. Electric response in superfluid helium

    NASA Astrophysics Data System (ADS)

    Chagovets, Tymofiy V.

    2016-05-01

    We report an experimental investigation of the electric response of superfluid helium that arises in the presence of a second sound standing wave. It was found that the signal of the electric response is observed in a narrow range of second sound excitation power. The linear dependence of the signal amplitude has been derived at low excitation power, however, above some critical power, the amplitude of the signal is considerably decreased. It was established that the rapid change of the electric response is not associated with a turbulent regime generated by the second sound wave. A model of the appearance of the electric response as a result of the oscillation of electron bubbles in the normal fluid velocity field in the second sound wave is presented. Possible explanation for the decrease of the electric response are presented.

  3. Nondipole effects in helium photoionization

    NASA Astrophysics Data System (ADS)

    Argenti, Luca; Moccia, Roberto

    2010-12-01

    An accurate calculation of the nondipole anisotropy parameter γ in the photoionization of helium below the N = 2 threshold is presented. The calculated results are in fairly good agreement with the experimental results of Krässig et al (2002 Phys. Rev. Lett. 88 203002), but not as good as the accuracy of the calculation should have warranted. A careful examination of the possible causes for the observed discrepancies between theory and experiment seems to rule out any role either of the multipolar terms higher than the electric quadrupole, or of the singlet-triplet spin-orbit mixing. It is argued that such discrepancies might have an instrumental origin, due to the difficulty of measuring vanishingly small total cross sections σtot with the required accuracy. In such eventuality, it might be more appropriate to use a parameter other than γ, such as for instance the drag current, to measure the nondipole anisotropy of the photoelectron angular distribution.

  4. Atom lithography with metastable helium

    SciTech Connect

    Allred, Claire S.; Reeves, Jason; Corder, Christopher; Metcalf, Harold

    2010-02-15

    A bright metastable helium (He*) beam is collimated sequentially with the bichromatic force and three optical molasses velocity compression stages. Each He* atom in the beam has 20 eV of internal energy that can destroy a molecular resist assembled on a gold coated silicon wafer. Patterns in the resist are imprinted onto the gold layer with a standard selective etch. Patterning of the wafer with the He{sup *} was demonstrated with two methods. First, a mesh was used to protect parts of the wafer making an array of grid lines. Second, a standing wave of {lambda}=1083 nm light was used to channel and focus the He* atoms into lines separated by {lambda}/2. The patterns were measured with an atomic force microscope establishing an edge resolution of 80 nm. Our results are reliable and repeatable.

  5. Helium Saturation of Liquid Propellants

    NASA Technical Reports Server (NTRS)

    Yavrouian, A. H.; Moran, Clifford M.

    1990-01-01

    The research is in three areas which are: (1) techniques were devised for achieving the required levels of helium (He) saturation in liquid propellants (limited to monomethylhydrazine (MMH) and nitrogen tetroxide (NTO)); (2) the values were evaluated for equilibrium solubilities of He in liquid propellants as currently used in the industry; and (3) the He dissolved in liquid propellants were accurately measured. Conclusions drawn from these studies include: (1) Techniques for dissolving He in liquid propellants depending upon the capabilities of the testing facility (Verification of the quantity of gas dissolved is essential); (2) Until greater accuracy is obtained, the equilibrium solubility values of He in MMH and NTO as cited in the Air Force Propellant Handbooks should be accepted as standard (There are still enough uncertainties in the He saturation values to warrant further basic experimental studies); and (3) The manometric measurement of gas volume from a frozen sample of propellant should be the accepted method for gas analysis.

  6. Dental Implant Surgery

    MedlinePlus

    Dental implant surgery Overview By Mayo Clinic Staff Dental implant surgery is a procedure that replaces tooth roots with ... look and function much like real ones. Dental implant surgery can offer a welcome alternative to dentures ...

  7. Hip Implant Systems

    MedlinePlus

    ... Devices Products and Medical Procedures Implants and Prosthetics Metal-on-Metal Hip Implants Hip Implants Share Tweet Linkedin Pin ... devices available with different bearing surfaces. These are: Metal-on-Polyethylene: The ball is made of metal ...

  8. Fast adaptive unsharp masking with programmable mediaprocessors.

    PubMed

    Bae, Unmin; Shamdasani, Vijay; Managuli, Ravi; Kim, Yongmin

    2003-06-01

    Unsharp masking is a widely used image-enhancement method in medical imaging. Hardware-based solutions can be developed to support high computational demand for unsharp masking, but they suffer from limited flexibility. Software solutions can easily incorporate new features and modify key parameters, such as filtering kernel size, but they have not been able to meet the fast computing requirement. Modern programmable mediaprocessors can meet both fast computing and flexibility requirements, which will benefit medical image computing. In this article, we present fast adaptive unsharp masking on two leading mediaprocessors or high-end digital signal processors, Hitachi/Equator Technologies MAP-CA and Texas Instruments TMS320C64x. For a 2k x 2k 16-bit image, our adaptive unsharp masking with a 201 x 201 boxcar kernel takes 225 ms on a 300-MHz MAP-CA and 74 ms on a 600-MHz TMS320C64x. This fast unsharp masking enables technologists and/or physicians to adjust parameters interactively for optimal quality assurance and image viewing.

  9. Efficient adaptive thresholding with image masks

    NASA Astrophysics Data System (ADS)

    Oh, Young-Taek; Hwang, Youngkyoo; Kim, Jung-Bae; Bang, Won-Chul

    2014-03-01

    Adaptive thresholding is a useful technique for document analysis. In medical image processing, it is also helpful for segmenting structures, such as diaphragms or blood vessels. This technique sets a threshold using local information around a pixel, then binarizes the pixel according to the value. Although this technique is robust to changes in illumination, it takes a significant amount of time to compute thresholds because it requires adding all of the neighboring pixels. Integral images can alleviate this overhead; however, medical images, such as ultrasound, often come with image masks, and ordinary algorithms often cause artifacts. The main problem is that the shape of the summing area is not rectangular near the boundaries of the image mask. For example, the threshold at the boundary of the mask is incorrect because pixels on the mask image are also counted. Our key idea to cope with this problem is computing the integral image for the image mask to count the valid number of pixels. Our method is implemented on a GPU using CUDA, and experimental results show that our algorithm is 164 times faster than a naïve CPU algorithm for averaging.

  10. Light masking in the field: an experiment with nocturnal and diurnal spiny mice under semi-natural field conditions.

    PubMed

    Rotics, Shay; Dayan, Tamar; Levy, Ofir; Kronfeld-Schor, Noga

    2011-02-01

    Light masking has been studied almost exclusively in the laboratory. The authors populated four field enclosures with locally coexisting nocturnal Acomys cahirinus and diurnal A. russatus, and monitored their body temperatures (T(b)) using implanted temperature-sensitive radio transmitters. A 3-h light pulse was initiated at the beginning of two consecutive nights; preceding nights were controls. A. cahirinus T(b) and calculated activity levels decreased significantly during the light pulse, demonstrating a negative light masking response (light effect on T(b): -0.32 °C ± 0.15 °C; average calculated activity records during the light pulse: 7 ± 1.53, control: 9.8 ± 1.62). Diurnal A. russatus did not respond to the light pulse. We conclude that light masking is not an artifact of laboratory conditions but represents a natural adaptive response in free-living populations.

  11. Helium refrigeration considerations for cryomodule design

    SciTech Connect

    Ganni, V.; Knudsen, P.

    2014-01-29

    Many of the present day accelerators are based on superconducting radio frequency (SRF) cavities, packaged in cryo-modules (CM), which depend on helium refrigeration at sub-atmospheric pressures, nominally 2 K. These specialized helium refrigeration systems are quite cost intensive to produce and operate. Particularly as there is typically no work extraction below the 4.5-K supply, it is important that the exergy loss between this temperature level and the CM load temperature(s) be minimized by the process configuration choices. This paper will present, compare and discuss several possible helium distribution process arrangements to support the CM loads.

  12. 21 CFR 868.1640 - Helium gas analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Helium gas analyzer. 868.1640 Section 868.1640...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1640 Helium gas analyzer. (a) Identification. A helium gas analyzer is a device intended to measure the concentration of helium in a...

  13. 21 CFR 868.1640 - Helium gas analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Helium gas analyzer. 868.1640 Section 868.1640...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1640 Helium gas analyzer. (a) Identification. A helium gas analyzer is a device intended to measure the concentration of helium in a...

  14. 21 CFR 868.1640 - Helium gas analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Helium gas analyzer. 868.1640 Section 868.1640...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1640 Helium gas analyzer. (a) Identification. A helium gas analyzer is a device intended to measure the concentration of helium in a...

  15. 21 CFR 868.1640 - Helium gas analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Helium gas analyzer. 868.1640 Section 868.1640...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1640 Helium gas analyzer. (a) Identification. A helium gas analyzer is a device intended to measure the concentration of helium in a...

  16. 21 CFR 868.1640 - Helium gas analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Helium gas analyzer. 868.1640 Section 868.1640...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1640 Helium gas analyzer. (a) Identification. A helium gas analyzer is a device intended to measure the concentration of helium in a...

  17. Development of an advanced mask and its fabrication system

    NASA Astrophysics Data System (ADS)

    Takigawa, Tadahiro; Tojo, Toru; Ogawa, Yoji; Koyama, Kiyomi; Ono, Akira; Inoue, Soichi; Ito, Shinichi; Goto, Mineo

    1995-07-01

    Masks and their fabrication technologies are keys to the further advancement of optical lithography. A stable SiNx single layer attenuated masks for DUV have been developed. A 0.2 micrometers contact hole pattern was fabricated using a KrF stepper with the SiNx attenuated mask. Toshiba mask fabrication system, including an electron beam writing system, a data base inspection system, and a data conversion system, has been developed for 64 Mbit DRAM class. Required mask improvements for increasing optical lithography resolution include better critical dimension (CD) uniformity, higher mask writing system resolution, and automatic shifter patten generation of alternating phase shifting masks. In addition, improved mask pattern positioning accuracy is also required. In this paper, experimental CD uniformity and resolution improvements, automatic phase shifter assignment method, and improvement in positioning accuracy, are described. The future development of masks will incorporate these key technologies.

  18. Communication masking in marine mammals: A review and research strategy.

    PubMed

    Erbe, Christine; Reichmuth, Colleen; Cunningham, Kane; Lucke, Klaus; Dooling, Robert

    2016-02-15

    Underwater noise, whether of natural or anthropogenic origin, has the ability to interfere with the way in which marine mammals receive acoustic signals (i.e., for communication, social interaction, foraging, navigation, etc.). This phenomenon, termed auditory masking, has been well studied in humans and terrestrial vertebrates (in particular birds), but less so in marine mammals. Anthropogenic underwater noise seems to be increasing in parts of the world's oceans and concerns about associated bioacoustic effects, including masking, are growing. In this article, we review our understanding of masking in marine mammals, summarise data on marine mammal hearing as they relate to masking (including audiograms, critical ratios, critical bandwidths, and auditory integration times), discuss masking release processes of receivers (including comodulation masking release and spatial release from masking) and anti-masking strategies of signalers (e.g. Lombard effect), and set a research framework for improved assessment of potential masking in marine mammals.

  19. Procedural Factors That Affect Psychophysical Measures of Spatial Selectivity in Cochlear Implant Users

    PubMed Central

    Deeks, John M.; Carlyon, Robert P.

    2015-01-01

    Behavioral measures of spatial selectivity in cochlear implants are important both for guiding the programing of individual users’ implants and for the evaluation of different stimulation methods. However, the methods used are subject to a number of confounding factors that can contaminate estimates of spatial selectivity. These factors include off-site listening, charge interactions between masker and probe pulses in interleaved masking paradigms, and confusion effects in forward masking. We review the effects of these confounds and discuss methods for minimizing them. We describe one such method in which the level of a 125-pps masker is adjusted so as to mask a 125-pps probe, and where the masker and probe pulses are temporally interleaved. Five experiments describe the method and evaluate the potential roles of the different potential confounding factors. No evidence was obtained for off-site listening of the type observed in acoustic hearing. The choice of the masking paradigm was shown to alter the measured spatial selectivity. For short gaps between masker and probe pulses, both facilitation and refractory mechanisms had an effect on masking; this finding should inform the choice of stimulation rate in interleaved masking experiments. No evidence for confusion effects in forward masking was revealed. It is concluded that the proposed method avoids many potential confounds but that the choice of method should depend on the research question under investigation. PMID:26420785

  20. Protective mask for airborne toxic substances

    SciTech Connect

    Shoemaker, C.J.; Scavnicky, J.A.; Little, M.E.; Hagy, E.M.; Bloom, A.

    1983-10-21

    A protective mask is described which includes a one-piece face piece molded of a transparent elastomer. A visor in the face piece provides panoramic visibility and is resilient enough to deform under applied force to permit improved use of optical devices. Identical left and right cheek fittings permit installation of a canister on either side so that the same mask can be used by right-handed and left-handed wearers voice for use with a telephone and the like. Air deflectors inside the mask adjacent the left and right cheek fittings deflect de-foging air along the inside surface of the visor when either left or right or both cheek fittings are used for attachment of a canister. A sealing adapter permits sealing around earpiece shafts of eyeglasses.

  1. Layer aware source mask target optimization

    NASA Astrophysics Data System (ADS)

    Chen, Ao; Foong, Yee Mei; Schramm, Jessy; Ji, Liang; Hsu, Stephen; Guerrero, James; Li, Xiaoyang; Shaw, Joe; Wang, Joe

    2016-03-01

    In this paper, we present the approach and results of layer-aware source mask target optimization. In this approach, the design target is co-optimized during source mask optimization (SMO) by considering inter-layer constraints. We tested the method on a 2x nm node metal layer by using both standard and customized cost functions for source optimization. Variable targets were defined for two process window limiting critical pattern cells, with contact-to-metal and metal-tovia coverage rules taken into consideration. The results indicate that layer-aware source mask target optimization gives consistent process window improvement over conventional SMO. The optimized targets prove to be a good balance between lithography process window and post-etch inter-layer coverage margin.

  2. Metacontrast masking is processed before grapheme-color synesthesia.

    PubMed

    Bacon, Michael Patrick; Bridgeman, Bruce; Ramachandran, Vilayanur S

    2013-01-01

    We investigated the physiological mechanism of grapheme-color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, because it can be obtained dichoptically. To compare the data for synesthetes and controls, we developed a metacontrast design in which nonsynesthete controls showed weaker dichromatic masking (i.e., the target and mask were in different colors) than monochromatic masking. We accomplished this with an equiluminant target, mask, and background for each observer. If synesthetic color affected metacontrast, synesthetes should show monochromatic masking more similar to the weak dichromatic masking among controls, because synesthetes could add their synesthetic color to the monochromatic condition. The target-mask pairs used for each synesthete were graphemes that elicited strong synesthetic colors. We found stronger monochromatic than dichromatic U-shaped metacontrast for both synesthetes and controls, with optimal masking at an asynchrony of 66 ms. The difference in performance between the monochromatic and dichromatic conditions in the synesthetes indicates that synesthesia occurs at a later processing stage than does metacontrast masking.

  3. Helium resources of the United States, 1987. Information Circular/1988

    SciTech Connect

    Miller, R.D.

    1987-01-01

    The helium-resources base of the United States was estimated by the Bureau of Mines to be 1040 Bcf as of January 1, 1987. These resources are divided into four categories in decreasing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 265 Bcf, (2) helium in probable natural gas resources, 228 Bcf, (3) helium in possible natural gas resources, 320 Bcf, and (4) helium in speculative natural gas resources, 227 Bcf. These helium resources are further divided into depleting and nondepleting, with the helium in storage being in a separate classification.

  4. Carbon contamination topography analysis of EUV masks

    SciTech Connect

    Fan, Y.-J.; Yankulin, L.; Thomas, P.; Mbanaso, C.; Antohe, A.; Garg, R.; Wang, Y.; Murray, T.; Wuest, A.; Goodwin, F.; Huh, S.; Cordes, A.; Naulleau, P.; Goldberg, K. A.; Mochi, I.; Gullikson, E.; Denbeaux, G.

    2010-03-12

    The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and potential effects on imaging performance. Current carbon contamination research primarily focuses on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on absorbing features and the printed images, as well as impacting the efficiency of cleaning process. In this work, several different techniques were used to determine possible contamination topography. Lithographic simulations were also performed and the results compared with the experimental data.

  5. Free electron laser with masked chicane

    DOEpatents

    Nguyen, Dinh C.; Carlsten, Bruce E.

    1999-01-01

    A free electron laser (FEL) is provided with an accelerator for outputting electron beam pulses; a buncher for modulating each one of the electron beam pulses to form each pulse into longitudinally dispersed bunches of electrons; and a wiggler for generating coherent light from the longitudinally dispersed bunches of electrons. The electron beam buncher is a chicane having a mask for physically modulating the electron beam pulses to form a series of electron beam bunches for input to the wiggler. In a preferred embodiment, the mask is located in the chicane at a position where each electron beam pulse has a maximum dispersion.

  6. Spatial and Temporal Visual Masking and Visibility.

    DTIC Science & Technology

    1984-10-01

    the 2AFC task. Harmonically Pure Stimuli and the Method of Adjustment The evidence presented so far supports our two-criterion 0 hypothesis for masking...the subject can still recognize this repetitive beat pattern. Figure 7 sh3ws 2AFC thresholds in the presence of a 2 c/deg mask for several tests...at all 4 rr 1.2- 1.0 W S08 N."- 0.6 b L0 12 14 16 REPLICATIONS Figlure 4 ilope of the 2AFC mssinq function with a continuall coanginq ai$& 1solid lines

  7. Development of a transferline connecting a helium liquefier coldbox and a liquid helium Dewar

    NASA Astrophysics Data System (ADS)

    Menon, Rajendran S.; Rane, Tejas; Chakravarty, Anindya; Joemon, V.

    2017-02-01

    A helium liquefier with demonstrated capacity of 32 1/hr has been developed by BARC. Mumbai. A transferline for two way flow of helium between the helium liquefier coldbox and receiver Dewar has been developed in-house at BARC. Further, a functionally similar, but structurally improved transferline has been developed through a local fabricator. This paper describes and discusses issues related to the development of these cryogenic transferlines. The developed transferlines have been tested with a flow of liquid nitrogen and successfully utilised later in the helium liquefier plant.

  8. Robust source and mask optimization compensating for mask topography effects in computational lithography.

    PubMed

    Li, Jia; Lam, Edmund Y

    2014-04-21

    Mask topography effects need to be taken into consideration for a more accurate solution of source mask optimization (SMO) in advanced optical lithography. However, rigorous 3D mask models generally involve intensive computation and conventional SMO fails to manipulate the mask-induced undesired phase errors that degrade the usable depth of focus (uDOF) and process yield. In this work, an optimization approach incorporating pupil wavefront aberrations into SMO procedure is developed as an alternative to maximize the uDOF. We first design the pupil wavefront function by adding primary and secondary spherical aberrations through the coefficients of the Zernike polynomials, and then apply the conjugate gradient method to achieve an optimal source-mask pair under the condition of aberrated pupil. We also use a statistical model to determine the Zernike coefficients for the phase control and adjustment. Rigorous simulations of thick masks show that this approach provides compensation for mask topography effects by improving the pattern fidelity and increasing uDOF.

  9. Compensation of overlay errors due to mask bending and non-flatness for EUV masks

    NASA Astrophysics Data System (ADS)

    Chandhok, Manish; Goyal, Sanjay; Carson, Steven; Park, Seh-Jin; Zhang, Guojing; Myers, Alan M.; Leeson, Michael L.; Kamna, Marilyn; Martinez, Fabian C.; Stivers, Alan R.; Lorusso, Gian F.; Hermans, Jan; Hendrickx, Eric; Govindjee, Sanjay; Brandstetter, Gerd; Laursen, Tod

    2009-03-01

    EUV blank non-flatness results in both out of plane distortion (OPD) and in-plane distortion (IPD) [3-5]. Even for extremely flat masks (~50 nm peak to valley (PV)), the overlay error is estimated to be greater than the allocation in the overlay budget. In addition, due to multilayer and other thin film induced stresses, EUV masks have severe bow (~1 um PV). Since there is no electrostatic chuck to flatten the mask during the e-beam write step, EUV masks are written in a bent state that can result in ~15 nm of overlay error. In this article we present the use of physically-based models of mask bending and non-flatness induced overlay errors, to compensate for pattern placement of EUV masks during the e-beam write step in a process we refer to as E-beam Writer based Overlay error Correction (EWOC). This work could result in less restrictive tolerances for the mask blank non-flatness specs which in turn would result in less blank defects.

  10. Extinction controlled adaptive mask coronagraph Lyot and phase mask dual concept for wide extinction area

    NASA Astrophysics Data System (ADS)

    Bourget, P.; Schuhler, N.; Mawet, D.; Haguenauer, P.; Girard, J.; Gonte, Frederic

    2012-09-01

    A dual coronagraph based on the Adaptive Mask concept is presented in this paper. ALyot coronagraph with a variable diameter occulting disk anda nulling stellar coronagraph based on the Adaptive Phase Mask concept using polarization interferometry are presented in this work. Observations on sky and numerical simulations show the usefulness of the proposed method to optimize the nulling efficiency of the coronagraphs. In the case of the phase mask, the active control system will correct for the detrimental effects of image instabilities on the destructive interference (low-order aberrations such as tip-tilt and focus). The phase mask adaptability both in size, phase and amplitude also compensate for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve the achromatic π phase shift in the core of the PSF by rotating the polarization by 180°.A compressed mercury (Hg) drop is used as an occulting disk for the Lyot mask, its size control offers an adaptation to the seeing conditions and provides an optimization of the Tip-tilt correction.

  11. High quality mask storage in an advanced Logic-Fab

    NASA Astrophysics Data System (ADS)

    Jähnert, Carmen; Fritsche, Silvio

    2012-02-01

    High efficient mask logistics as well as safe and high quality mask storage are essential requirements within an advanced lithography area of a modern logic waferfab. Fast operational availability of the required masks at the exposure tool with excellent mask condition requires a safe mask handling, safeguarding of high mask quality over the whole mask usage time without any quality degradation and an intelligent mask logistics. One big challenge is the prevention of haze on high advanced phase shift masks used in a high volume production line for some thousands of 248nm or 193nm exposures. In 2008 Infineon Dresden qualified a customer specific developed semi-bare mask storage system from DMSDynamic Micro Systems in combination with a high advanced mask handling and an interconnected complex logistic system. This high-capacity mask storage system DMS M1900.22 for more than 3000 masks with fully automated mask and box handling as well as full-blown XCDA purge has been developed and adapted to the Infineon Lithotoollandscape using Nikon and SMIF reticle cases. Advanced features for ESD safety and mask security, mask tracking via RFID and interactions with the exposure tools were developed and implemented. The stocker is remote controlled by the iCADA-RSM system, ordering of the requested mask directly from the affected exposure tool allows fast access. This paper discusses the advantages and challenges for this approach as well as the practical experience gained during the implementation of the new system which improves the fab performance with respect to mask quality, security and throughput. Especially the realization of an extremely low and stable humidity level in addition with a well controlled air flow at each mask surface, preventing masks from haze degradation and particle contamination, turns out to be a notable technical achievement. The longterm stability of haze critical masks has been improved significantly. Relevant environmental parameters like

  12. Helium Plants and Storage. Design Manual 24.2.

    DTIC Science & Technology

    1980-06-01

    Helium Air Separation System for a Supersonic Wind Tunnel.. 24.2-6 4 Four-Way Four-Port Valve ................................... 24.2-11 5 Friction...7) Weather and climatic conditions. 5. FACTS ON HELIUM. Federal agencies use helium in helium-shielded arc weld- ing, supersonic wind tunnels, and...station at the nearest railroad connection for transferring helium from railroad tank car to truck trailer. c. Compressor Station. Generally , the initial

  13. Development of charcoal sorbents for helium cryopumping

    SciTech Connect

    Sedgley, D.W.; Tobin, A.G.

    1984-01-01

    Testing of the cryogenically cooled charcoal using fusion-compatible binders for pumping helium has shown promising results. The program demonstrated comparable or improved performance with these binders compared to the charcoal (type and size) using an epoxy binder.

  14. Primary helium heater for propellant pressurization systems

    NASA Technical Reports Server (NTRS)

    Reichmuth, D. M.; Nguyen, T. V.; Pieper, J. L.

    1991-01-01

    The primary helium heater is a unique design that provides direct heating of pressurant gas for large pressure fed propulsion systems. It has been conceptually designed to supply a heated (800-1000 R) pressurization gas to both a liquid oxygen and an RP-1 propellant tank. This pressurization gas is generated within the heater by mixing super critical helium (40-300 R and 3000-1600 psi) with an appropriate amount of combustion products from a 4:1 throttling stoichiometric LO2/LH2 combustor. This simple, low cost and reliable mixer utilizes the large quantity of helium to provide stoichiometric combustor cooling, extend the throttling limits and enhance the combustion stability margin. Preliminary combustion, thermal, and CFD analyses confirm that this low-pressure-drop direct helium heater can provide the constant-temperature pressurant suitable for tank pressurization of both fuel and oxidizer tanks of large pressure fed vehicles.

  15. Helium Dilution Cryocooler for Space Applications

    NASA Technical Reports Server (NTRS)

    Roach, Pat; Hogan, Robert (Technical Monitor)

    2001-01-01

    NASA's New Millenium Program Space Technology presents the Helium Dilution Cryocooler for Space Applications. The topics include: 1) Capability; 2) Applications; and 3) Advantages. This paper is in viewgraph form.

  16. Helium Find Thaws the Cold Fusion Trail.

    ERIC Educational Resources Information Center

    Pennisi, E.

    1991-01-01

    Reported is a study of cold fusion in which trace amounts of helium, possible evidence of an actual fusion reaction, were found. Research methodology is detailed. The controversy over the validity of experimental results with cold fusion are reviewed. (CW)

  17. Helium and Enhanced Image of the Sun

    NASA Video Gallery

    This video blinks between an image in Helium and an enhanced image. The original image is from AIA on SDO and the enhanced image was created at the LM Solar and Astrophysics Laboratory (LMSAL) by D...

  18. Advances in mask fabrication and alignment for masked ion-beam lithography

    NASA Astrophysics Data System (ADS)

    Stumbo, David P.; Damm, George A.; Engler, D. W.; Fong, F. O.; Sen, S.; Wolfe, John C.; Randall, John N.; Mauger, Phillip E.; Shimkunas, Alex R.; Loeschne, Hans

    1990-05-01

    This paper describes recent developments in three areas ofmasked ion beam lithography (MIBL). These are 1) fabrication oflarge area, low distortion, silicon stencilmasks for demagnifying ion projection lithography, 2) fabrication ofstencil masks with nanometer scale resolution for 1:1 proximity printing, and 3) development of a direct method of alignment using the ion beam induced fluorescence of Si02. These topics are discussed below. Demagnifying ion projection masks: We describe the fabrication of stencil masks in large area, low stress (10 MPa), n-type silicon membranes. The projection masks have a silicon foil area 95 mm in diameter, thicknesses between 1.5-5 and resolution of0.6um. Measured distortion (3a) in the IPL masks ranges between 0.23gm and 0.65,um, with an experimental error of 0.20 1um. Proximity printing masks: A process is described for fabricating stencil masks with 50 nm resolution in low stress, n-type silicon membranes. Membranes less than 0.5 ,ttm thick are shown to be free of the sidewall taper that limits resolution in thicker masks. These thin membranes show a slightly flared profile due to the imperfectly collimated etching ions. Alignment: A direct method of alignment is being developed which uses the ion beam induced fluorescence of Si02 marks. Fluorescence yield is characterized as a function of ion energy and resist coating thickness. The yield for Si02 is in the range between 0.1-1.0 photons/proton, while the yields for Si, Al, and photoresist are negligibly small. Thus, a simple alignment technique can be implemented where registration of a grating in the mask with a corresponding oxide pattern is detected as a fluorescence maximum. A simple model predicts that 50 nm alignment can be accomplished, following a 1 im prealignment, in 2 seconds.

  19. Radiation Resistance of Structural Materials of Nuclear Reactors on Irradiation with High-Energy Hydrogen and Helium Ions

    NASA Astrophysics Data System (ADS)

    Komarov, F. F.; Komarov, A. F.; Pil‧ko, Vl. V.; Pil‧ko, V. V.

    2013-11-01

    Basic principles of determination of the radiation resistance of structural materials of nuclear reactors with implantation of high-energy hydrogen and helium atoms have been presented. The parameters of the process of implantation of light irons have been calculated. By scanning-electron-microscopy, optical-microscopy, and interference methods, the authors have studied the surface structure of samples of steel-3, stainless steel, and D16 alloy immediately after irradiating them with hydrogen and helium atoms with an energy of 200 to 400 keV in the range of doses from 1016 to 3 · 1017 ions/cm2 and after annealing these samples thermally at temperatures from 300 to 550°C. Threshold blistering doses for all the studied materials and annealing temperatures for visualizing structural defects have been determined.

  20. Cosmic Ballet or Devil's Mask?

    NASA Astrophysics Data System (ADS)

    2004-04-01

    Stars like our Sun are members of galaxies, and most galaxies are themselves members of clusters of galaxies. In these, they move around among each other in a mostly slow and graceful ballet. But every now and then, two or more of the members may get too close for comfort - the movements become hectic, sometimes indeed dramatic, as when galaxies end up colliding. ESO PR Photo 12/04 shows an example of such a cosmic tango. This is the superb triple system NGC 6769-71, located in the southern Pavo constellation (the Peacock) at a distance of 190 million light-years. This composite image was obtained on April 1, 2004, the day of the Fifth Anniversary of ESO's Very Large Telescope (VLT). It was taken in the imaging mode of the VIsible Multi-Object Spectrograph (VIMOS) on Melipal, one of the four 8.2-m Unit Telescopes of the VLT at the Paranal Observatory (Chile). The two upper galaxies, NGC 6769 (upper right) and NGC 6770 (upper left), are of equal brightness and size, while NGC 6771 (below) is about half as bright and slightly smaller. All three galaxies possess a central bulge of similar brightness. They consist of elderly, reddish stars and that of NGC 6771 is remarkable for its "boxy" shape, a rare occurrence among galaxies. Gravitational interaction in a small galaxy group NGC 6769 is a spiral galaxy with very tightly wound spiral arms, while NGC 6770 has two major spiral arms, one of which is rather straight and points towards the outer disc of NGC 6769. NGC 6770 is also peculiar in that it presents two comparatively straight dark lanes and a fainter arc that curves towards the third galaxy, NGC 6771 (below). It is also obvious from this new VLT photo that stars and gas have been stripped off NGC 6769 and NGC 6770, starting to form a common envelope around them, in the shape of a Devil's Mask. There is also a weak hint of a tenuous bridge between NGC 6769 and NGC 6771. All of these features testify to strong gravitational interaction between the three galaxies

  1. CHARACTERIZING TRITIUM WASTE USING HELIUM RATIOS

    SciTech Connect

    Ovink, R.W.; McMahon, W.J.; Borghese, J.V.; Olsen, K.B.

    2003-02-27

    When routine sampling revealed greatly elevated tritium levels (3.14 x 105 Bq/L [8.5-million pCi/liter]) in the groundwater near a solid waste landfill at the Hanford Site, an innovative technique was used to assess the extent of the plume. Helium-3/helium-4 ratios, relative to ambient air-in-soil gas samples, were used to identify the tritium source and initially delineate the extent of the groundwater tritium plume. This approach is a modification of a technique developed in the late 1960s to age-date deep ocean water as part of the GEOSECS ocean monitoring program. Poreda, et al. (1) and Schlosser, et al. (2) applied this modified technique to shallow aquifers. A study was also conducted to demonstrate the concept of using helium-3 as a tool to locate vadose zone sources of tritium and tracking groundwater tritium plumes at Hanford (3). Seventy sampling points were installed around the perimeter and along four transects downgradient of the burial ground. Soil gas samples were collected, analyzed for helium isotopes, and helium-3/helium-4 ratios were calculated for these 70 points. The helium ratios indicated a vadose zone source of tritium along the northern edge of the burial ground that is likely the source of tritium in the groundwater. The helium ratios also indicate the groundwater plume is traveling east-northeast from the burial ground and that no up-gradient tritium sources are affecting the burial ground. Based on the helium ratio results, six downgradient groundwater sampling locations were identified to verify the tritium plume extent and groundwater tritium concentrations. The tritium results from the initial groundwater samples confirmed that elevated helium ratios were indicative of tritium contamination in the local groundwater. The measurement of helium isotopes in soil gas provided a rapid and cost- effective technique to define the shape and extent of tritium contamination from the burial ground. Using this soil gas sampling approach, the

  2. Radioactive Ions and Atoms in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Dendooven, P.; Purushothaman, S.; Gloos, K.; ńystö, J.; Takahashi, N.; Huang, W. X.

    2006-04-01

    We are investigating the use of superfluid helium as a medium to handle and manipulate radioactive ions and atoms. Preliminary results on the extraction of positive ions from superfluid helium at temperatures close to 1 K are described. Increasing the electric field up to 1.2 kV/cm did not improve the extraction. Evaporating a thin surface layer of the liquid using second-sound pulses gave an extraction efficiency of 7.2 %.

  3. Helium Reionization in From New Sightlines

    NASA Astrophysics Data System (ADS)

    Syphers, David

    2017-01-01

    A very small number of sightlines to z~3 quasars have been studied in detail to show the progress of helium reionization. Although studying the same sightlines with each new UV spectrograph lead to a better understanding of them, the sightline variance is very strong during this patchy and extended process. We discuss detailed R>10,000 COS data from new sightlines, and what they reveal about the progress and end of helium reionization.

  4. Cosmogenic helium in a terrestrial igneous rock

    NASA Technical Reports Server (NTRS)

    Kurz, M. D.

    1986-01-01

    New helium isotopic measurements on samples from the Kula formation of Haleakala volcano of Hawaii are presented that are best explained by an in situ cosmogenic origin for a significant fraction of the He-3. Results from crushing and stepwise heating experiments, and consideration of the exposure age of the sample at the surface and the cosmic ray fluxes strongly support this hypothesis. Although crustal cosmogenic helium has been proposed previously, this represents its first unambiguous identification in a terrestrial sample.

  5. Perspectives on Lunar Helium-3

    NASA Astrophysics Data System (ADS)

    Schmitt, Harrison H.

    1999-01-01

    Global demand for energy will likely increase by a factor of six or eight by the mid-point of the 21st Century due to a combination of population increase, new energy intensive technologies, and aspirations for improved standards of living in the less-developed world (1). Lunar helium-3 (3He), with a resource base in the Tranquillitatis titanium-rich lunar maria (2,3) of at least 10,000 tonnes (4), represents one potential energy source to meet this rapidly escalating demand. The energy equivalent value of 3He delivered to operating fusion power plants on Earth would be about 3 billion per tonne relative to today's coal which supplies most of the approximately 90 billion domestic electrical power market (5). These numbers illustrate the magnitude of the business opportunity. The results from the Lunar Prospector neutron spectrometer (6) suggests that 3He also may be concentrated at the lunar poles along with solar wind hydrogen (7). Mining, extraction, processing, and transportation of helium to Earth requires new innovations in engineering but no known new engineering concepts (1). By-products of lunar 3He extraction, largely hydrogen, oxygen, and water, have large potential markets in space and ultimately will add to the economic attractiveness of this business opportunity (5). Inertial electrostatic confinement (IEC) fusion technology appears to be the most attractive and least capital intensive approach to terrestrial fusion power plants (8). Heavy lift launch costs comprise the largest cost uncertainty facing initial business planning, however, many factors, particularly long term production contracts, promise to lower these costs into the range of 1-2000 per kilogram versus about 70,000 per kilogram fully burdened for the Apollo Saturn V rocket (1). A private enterprise approach to developing lunar 3He and terrestrial IEC fusion power would be the most expeditious means of realizing this unique opportunity (9). In spite of the large, long-term potential

  6. Helium diffusion coefficient measurements in R7T7 nuclear glass by 3He(d,α) 1H nuclear reaction analysis

    NASA Astrophysics Data System (ADS)

    Chamssedine, F.; Sauvage, T.; Peuget, S.; Fares, T.; Martin, G.

    2010-05-01

    The immobilization of fission products and minor actinides by vitrification is the reference process for industrial management of high-level radioactive wastes generated by spent fuel reprocessing. Radiation damage and radiogenic helium accumulation must be specifically studied to evaluate the effects of minor actinide alpha decay on the glass long-term behavior under repository conditions. A specific experimental study was conducted for a comprehensive evaluation of the behavior of helium and its diffusion mechanisms in borosilicate nuclear waste glass. Helium production was simulated by external implantation with 3He ions at a concentration (≈1 at.%) 30 times higher than obtained after 10,000 years of storage. Helium diffusion coefficients as a function of temperature were extracted from the depth profiles after annealing. The 3He(d,α) 1H nuclear reaction analysis (NRA) technique was successfully adopted for low-temperature in situ measurements of depth profiles. Its high depth resolution revealed helium mobility at temperatures as low as 253 K and the presence of a trapped helium fraction. The diffusion coefficients of un-trapped helium atoms follow an Arrhenius law between 253 K and 323 K. An activation energy of 0.55 ± 0.03 eV was determined, which is consistent with a process controlled by diffusion in the glass free volume.

  7. The effect of spatial separation on informational and energetic masking of speech.

    PubMed

    Arbogast, Tanya L; Mason, Christine R; Kidd, Gerald

    2002-11-01

    The effect of spatial separation of sources on the masking of a speech signal was investigated for three types of maskers, ranging from energetic to informational. Normal-hearing listeners performed a closed-set speech identification task in the presence of a masker at various signal-to-noise ratios. Stimuli were presented in a quiet sound field. The signal was played from 0 degrees azimuth and a masker was played either from the same location or from 90 degrees to the right. Signals and maskers were derived from sentences that were preprocessed by a modified cochlear-implant simulation program that filtered each sentence into 15 frequency bands, extracted the envelopes from each band, and used these envelopes to modulate pure tones at the center frequencies of the bands. In each trial, the signal was generated by summing together eight randomly selected frequency bands from the preprocessed signal sentence. Three maskers were derived from the preprocessed masker sentences: (1) different-band sentence, which was generated by summing together six randomly selected frequency bands out of the seven bands not present in the signal (resulting in primarily informational masking); (2) different-band noise, which was generated by convolving the different-band sentence with Gaussian noise; and (3) same-band noise, which was generated by summing the same eight bands from the preprocessed masker sentence that were used in the signal sentence and convolving the result with Gaussian noise (resulting in primarily energetic masking). Results revealed that in the different-band sentence masker, the effect of spatial separation averaged 18 dB (at 51% correct), while in the different-band and same-band noise maskers the effect was less than 10 dB. These results suggest that, in these conditions, the advantage due to spatial separation of sources is greater for informational masking than for energetic masking.

  8. Microstructure of HIPed and SPSed 9Cr-ODS steel and its effect on helium bubble formation

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Lu, Zheng; Xie, Rui; Liu, Chunming; Wang, Lumin

    2016-06-01

    Two 9Cr-ODS steels with the same nominal composition were consolidated by hot isostatic pressing (HIP, named COS-1) and spark plasma sintering (SPS, named COS-2). Helium ions were implanted into COS-1, COS-2 and non-ODS Eurofer 97 steels up at 673 K. Microstructures before and after helium ion implantations were carefully characterized. The results show a bimodal grain size distribution in COS-2 and a more uniform grain size distribution in COS-1. Nanoscale clusters of GP-zone type Y-Ti-O and Y2Ti2O7 pyrochlore as well as large spinel Mn(Ti)Cr2O4 particles are all observed in the two ODS steels. The Y-Ti-enriched nano-oxides in COS-1 exhibit higher number density and smaller size than in COS-2. The Y-Ti-enriched nano-oxides in fine grains of COS-2 show higher number density and smaller size than that in coarse grains of COS-2. Nano-oxides effectively trap helium atoms and lead to the formation of high density and ultra-fine helium bubbles.

  9. Continuous and Localized Mn Implantation of ZnO

    PubMed Central

    2009-01-01

    We present results derived from continuous and localized 35 keV55Mn+ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature. PMID:20596285

  10. Sonic helium detectors in the Fermilab Tevatron

    SciTech Connect

    Bossert, R.J.; /Fermilab

    2006-01-01

    In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years.

  11. Advanced helium magnetometer for space applications

    NASA Technical Reports Server (NTRS)

    Slocum, Robert E.

    1987-01-01

    The goal of this effort was demonstration of the concepts for an advanced helium magnetometer which meets the demands of future NASA earth orbiting, interplanetary, solar, and interstellar missions. The technical effort focused on optical pumping of helium with tunable solid state lasers. We were able to demonstrate the concept of a laser pumped helium magnetometer with improved accuracy, low power, and sensitivity of the order of 1 pT. A number of technical approaches were investigated for building a solid state laser tunable to the helium absorption line at 1083 nm. The laser selected was an Nd-doped LNA crystal pumped by a diode laser. Two laboratory versions of the lanthanum neodymium hexa-aluminate (LNA) laser were fabricated and used to conduct optical pumping experiments in helium and demonstrate laser pumped magnetometer concepts for both the low field vector mode and the scalar mode of operation. A digital resonance spectrometer was designed and built in order to evaluate the helium resonance signals and observe scalar magnetometer operation. The results indicate that the laser pumped sensor in the VHM mode is 45 times more sensitive than a lamp pumped sensor for identical system noise levels. A study was made of typical laser pumped resonance signals in the conventional magnetic resonance mode. The laser pumped sensor was operated as a scalar magnetometer, and it is concluded that magnetometers with 1 pT sensitivity can be achieved with the use of laser pumping and stable laser pump sources.

  12. High efficiency pump for space helium transfer

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael G.; Swift, Walter L.; Sixsmith, Herbert

    1991-01-01

    A centrifugal pump was developed for the efficient and reliable transfer of liquid helium in space. The pump can be used to refill cryostats on orbiting satellites which use liquid helium for refrigeration at extremely low temperatures. The pump meets the head and flow requirements of on-orbit helium transfer: a flow rate of 800 L/hr at a head of 128 J/kg. The overall pump efficiency at the design point is 0.45. The design head and flow requirements are met with zero net positive suction head, which is the condition in an orbiting helium supply Dewar. The mass transfer efficiency calculated for a space transfer operation is 0.99. Steel ball bearings are used with gas fiber-reinforced teflon retainers to provide solid lubrication. These bearings have demonstrated the longest life in liquid helium endurance tests under simulated pumping conditions. Technology developed in the project also has application for liquid helium circulation in terrestrial facilities and for transfer of cryogenic rocket propellants in space.

  13. Adaptation to different noninvasive ventilation masks in critically ill patients*

    PubMed Central

    da Silva, Renata Matos; Timenetsky, Karina Tavares; Neves, Renata Cristina Miranda; Shigemichi, Liane Hirano; Kanda, Sandra Sayuri; Maekawa, Carla; Silva, Eliezer; Eid, Raquel Afonso Caserta

    2013-01-01

    OBJECTIVE: To identify which noninvasive ventilation (NIV) masks are most commonly used and the problems related to the adaptation to such masks in critically ill patients admitted to a hospital in the city of São Paulo, Brazil. METHODS: An observational study involving patients ≥ 18 years of age admitted to intensive care units and submitted to NIV. The reason for NIV use, type of mask, NIV regimen, adaptation to the mask, and reasons for non-adaptation to the mask were investigated. RESULTS: We evaluated 245 patients, with a median age of 82 years. Acute respiratory failure was the most common reason for NIV use (in 71.3%). Total face masks were the most commonly used (in 74.7%), followed by full face masks and near-total face masks (in 24.5% and 0.8%, respectively). Intermittent NIV was used in 82.4% of the patients. Adequate adaptation to the mask was found in 76% of the patients. Masks had to be replaced by another type of mask in 24% of the patients. Adequate adaptation to total face masks and full face masks was found in 75.5% and 80.0% of the patients, respectively. Non-adaptation occurred in the 2 patients using near-total facial masks. The most common reason for non-adaptation was the shape of the face, in 30.5% of the patients. CONCLUSIONS: In our sample, acute respiratory failure was the most common reason for NIV use, and total face masks were the most commonly used. The most common reason for non-adaptation to the mask was the shape of the face, which was resolved by changing the type of mask employed. PMID:24068269

  14. Proton implantation for the isolation of AlGaAs/GaAs quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Szerling, A.; Kosiel, K.; Kozubal, M.; Myśliwiec, M.; Jakieła, R.; Kuc, M.; Czyszanowski, T.; Kruszka, R.; Pągowska, K.; Karbownik, P.; Barcz, A.; Kamińska, E.; Piotrowska, A.

    2016-07-01

    The novel fabrication scheme of the mid-infrared (∼9.5 μm) Al0.45Ga0.55As/GaAs plasmon-enhanced-waveguide quantum cascade laser (QCL) is reported. The electric isolation was made exclusively by 6.5 μm-deep proton implantation. The applied implantation allowed us to suppress the current spreading and at the same time enabled the laser radiation confinement without any mesa formation. A galvanic gold layer at least 3.5 μm thick covering the top ohmic contact was used as a mask for implantation. This mask was not removed after the implantation, but it served for heat spreading from the laser. A considerable reduction in the necessary technological steps was obtained with the presented novel fabrication scheme, in comparison with the standard mesa-etching-based method.

  15. Clean induced feature CD shift of EUV mask

    NASA Astrophysics Data System (ADS)

    Nesládek, Pavel; Schedel, Thorsten; Bender, Markus

    2016-05-01

    EUV developed in the last decade to the most promising <7nm technology candidate. Defects are considered to be one of the most critical issues of the EUV mask. There are several contributors which make the EUV mask so different from the optical one. First one is the significantly more complicated mask stack consisting currently of 40 Mo/Si double layers, covered by Ru capping layer and TaN/TaO absorber/anti-reflective coating on top of the front face of the mask. Backside is in contrary to optical mask covered as well by conductive layer consisting of Cr or CrN. Second contributor is the fact that EUV mask is currently in contrary to optical mask not yet equipped with sealed pellicle, leading to much higher risk of mask contamination. Third reason is use of EUV mask in vacuum, possibly leading to deposition of vacuum contaminants on the EUV mask surface. Latter reason in combination with tight requirements on backside cleanliness lead to the request of frequent recleaning of the EUV mask, in order to sustain mask lifetime similar to that of optical mask. Mask cleaning process alters slightly the surface of any mask - binary COG mask, as well as phase shift mask of any type and naturally also of the EUV mask as well. In case of optical masks the changes are almost negligible, as the mask is exposed to max. 10-20 re-cleans within its life time. These modifications can be expressed in terms of different specified parameters, e.g. CD shift, phase/trans shift, change of the surface roughness etc. The CD shift, expressed as thinning (or exceptionally thickening) of the dark features on the mask is typically in order of magnitude 0.1nm per process run, which is completely acceptable for optical mask. Projected on the lifetime of EUV mask, assuming 100 clean process cycles, this will lead to CD change of about 10nm. For this reason the requirements for EUV mask cleaning are significantly tighter, << 0.1 nm per process run. This task will look even more challenging, when

  16. Masked object registration in the Fourier domain.

    PubMed

    Padfield, Dirk

    2012-05-01

    Registration is one of the most common tasks of image analysis and computer vision applications. The requirements of most registration algorithms include large capture range and fast computation so that the algorithms are robust to different scenarios and can be computed in a reasonable amount of time. For these purposes, registration in the Fourier domain using normalized cross-correlation is well suited and has been extensively studied in the literature. Another common requirement is masking, which is necessary for applications where certain regions of the image that would adversely affect the registration result should be ignored. To address these requirements, we have derived a mathematical model that describes an exact form for embedding the masking step fully into the Fourier domain so that all steps of translation registration can be computed efficiently using Fast Fourier Transforms. We provide algorithms and implementation details that demonstrate the correctness of our derivations. We also demonstrate how this masked FFT registration approach can be applied to improve the Fourier-Mellin algorithm that calculates translation, rotation, and scale in the Fourier domain. We demonstrate the computational efficiency, advantages, and correctness of our algorithm on a number of images from real-world applications. Our framework enables fast, global, parameter-free registration of images with masked regions.

  17. Mask cycle time reduction for foundry projects

    NASA Astrophysics Data System (ADS)

    Balasinski, A.

    2011-11-01

    One of key deliverables of foundry based manufacturing is low cycletime. Building new and enhancing existing products by mask changes involves significant logistical effort, which could be reduced by standardizing data management and communication procedures among design house, mask shop, and foundry (fab) [1]. As an example, a typical process of taping out can take up to two weeks in addition to technical effort, for database handling, mask form completion, management approval, PO signoff and JDV review, translating into loss of revenue. In order to reduce this delay, we are proposing to develop a unified online system which should assist with the following functions: database edits, final verifications, document approvals, mask order entries, and JDV review with engineering signoff as required. This would help a growing number of semiconductor products to be flexibly manufactured at different manufacturing sites. We discuss how the data architecture based on a non-relational database management system (NRDMBS) extracted into a relational one (RDMBS) should provide quality information [2], to reduce cycle time significantly beyond 70% for an example 2 week tapeout schedule.

  18. Associative Learning of Discrimination with Masked Stimuli

    ERIC Educational Resources Information Center

    Marcos, Jose L.

    2007-01-01

    Great controversy exists on whether associative learning occurs without awareness. In Experiment 1, 31 participants received discrimination training by repeated presentations of two stimulus sequences (S1[subscript A] right arrow S2[subscript A], and S1[subscript B] right arrow S2[subscript B]), S1 being a masked stimulus. S2 were imperative…

  19. Testing Tactile Masking between the Forearms.

    PubMed

    D'Amour, Sarah; Harris, Laurence R

    2016-02-10

    Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, usually using stimuli that are close together to reveal local interactions. Masking effects have also been demonstrated in which a tactile stimulus alters the perception of a touch at a distant location. Such effects can provide insight into how components of the body's representations in the brain may be linked. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at corresponding contralateral locations. To explore the matching of corresponding points across the body, we can measure the spatial tuning and effect of posture on contralateral masking. Careful controls are required to rule out direct effects of the remote stimulus, for example by mechanical transmission, and also attention effects in which thresholds may be altered by the participant's attention being drawn away from the stimulus of interest. The use of this technique is beneficial as a behavioural measure for exploring which parts of the body are functionally connected and whether the two sides of the body interact in a somatotopic representation. This manuscript describes a behavioural protocol that can be used for studying contralateral tactile masking.

  20. Helium and Neon in Comets

    NASA Technical Reports Server (NTRS)

    Jewitt, David

    1996-01-01

    Two comets were observed with EUVE in late 1994. Both comet Mueller and comet Borrelly are short-period comets having well established orbital elements and accurate ephemerides. Spectra of 40 ksec were taken of each. No evidence for emission lines from either Helium or Neon was detected. We calculated limits on the production rates of these atoms (relative to solar) assuming a standard isotropic outflow model, with a gas streaming speed of 1 km/s. The 3-sigma (99.7% confidence) limits (1/100,000 for He, 0.8 for Ne) are based on a conservative estimate of the noise in the EUVE spectra. They are also weakly dependent on the precise pointing and tracking of the EUVE field of view relative to the comet during the integrations. These limits are consistent with ice formation temperatures T greater than or equal to 30 K, as judged from the gas trapping experiments of Bar-Nun. For comparison, the solar abundances of these elements are He/O = 110, Ne/O = 1/16. Neither limit was as constraining as we had initially hoped, mainly because comets Mueller and Borrelly were intrinsically less active than anticipated.

  1. Measurement of Helium-3/Helium-4 Ratios in Soil Gas at the 618-11 Burial Ground

    SciTech Connect

    Olsen, Khris B.; Dresel, P Evan; Evans, John C.

    2001-10-31

    Seventy soil gas-sampling points were installed around the perimeter of the 618-11 Burial Ground, approximately 400 feet downgradient of well 699-13-3A, and in four transects downgradient of the burial ground to a maximum distance of 3,100 feet. Soil gas samples were collected and analyzed for helium-3/helium-4 ratios from these 70 points. Helium-3/helium-4 ratios determined from the soil gas sampling points showed significant enrichments, relative to ambient air helium-3 concentrations. The highest concentrations were located along the northern perimeter of the burial ground. Helium-3/helium-4 ratios (normalized to the abundances in ambient air) ranged from 1.0 to 62 around the burial ground. The helium-3/helium-4 ratios from the 4 transect downgradient of the burial ground ranged from 0.988 to 1.68. The helium-3/helium-4 ratios from around the burial ground suggest there is a vadose zone source of tritium along the north side of the burial ground. This vadose zone source is likely the source of tritium in the groundwater. The helium-3/helium-4 ratios also suggest the groundwater plume is traveling east-northeast from the burial ground and the highest groundwater tritium value may be to the north of well 699-13-3A. Finally, there appears to be no immediately upgradient sources of tritium impacting the burial ground since all the upgradient helium-3/helium-4 ratios are approximately 1.0.

  2. [Bilateral cochlear implantation].

    PubMed

    Kronenberg, Jona; Migirov, Lela; Taitelbaum-Swead, Rikey; Hildesheimer, Minka

    2010-06-01

    Cochlear implant surgery became the standard of care in hearing rehabilitation of patients with severe to profound sensorineural hearing loss. This procedure may alter the lives of children and adults enabling them to integrate with the hearing population. In the past, implantation was performed only in one ear, despite the fact that binaural hearing is superior to unilateral, especially in noisy conditions. Cochlear implantation may be performed sequentially or simultaneously. The "sensitive period" of time between hearing loss and implantation and between the two implantations, when performed sequentially, significantly influences the results. Shorter time spans between implantations improve the hearing results after implantation. Hearing success after implantation is highly dependent on the rehabilitation process which includes mapping, implant adjustments and hearing training. Bilateral cochlear implantation in children is recommended as the proposed procedure in spite of the additional financial burden.

  3. EUVL mask manufacturing: technologies and results

    NASA Astrophysics Data System (ADS)

    Letzkus, Florian; Butschke, Joerg; Irmscher, Mathias; Sailer, Holger; Dersch, Uwe; Holfeld, Christian

    2005-11-01

    Extreme Ultraviolet Lithography (EUVL) is the favourite next generation lithography candidate for IC device manufacturing with feature sizes beyond 32nm. Different stacks and manufacturing concepts have been published for the fabrication of the reflective EUVL masks. Patterning processes for two different absorber-buffer combinations on top of the reflective multi layer mirror have been developed. A TaN/SiO2 absorber-buffer stack was provided by supplier A and TaBN/Cr by supplier B. In addition both absorbers were covered by an anti reflective coating (ARC) layer. An e-beam patterned 300nm thick film of Fuji FEP171 was used as resist mask. We optimized the etching processes for maximum selectivities between absorber, buffer and capping layers on the one hand and rectangular profiles and low etch bias on the other hand. While both TaN based absorbers have been dry etched in an UNAXIS mask etcher III, wet and dry etch steps have been evaluated for the two different buffer layers. The minimum feature size of lines and holes in our test designs was 100nm. After freezing the processes a proximity correction was determined considering both, the influence of electron scattering due to e-beam exposure and the influence of the patterning steps. Due to the correction an outstanding linearity and iso/dense bias on different test designs was achieved. Various masks for printing experiments at the small-field Micro Exposure Tool (MET) in Berkeley and the fabrication of the ASML α-tool setup mask within the European MEDEA+ EXTUMASK project were done using the developed processes. Finally, we will compare and discuss the results of the two stack approaches.

  4. Infrared Signature Masking by Air Plasma Radiation

    NASA Technical Reports Server (NTRS)

    Kruger, C. H.; Laux, C. O.

    1998-01-01

    This report describes progress during the second year of our research program on Infrared Signature Masking by Air Plasmas at Stanford University. This program is intended to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. Our previous annual report described spectral measurements and modeling of the radiation emitted between 3.2 and 5.5 microns by an atmospheric pressure air plasma in chemical and thermal equilibrium at a temperature of approximately 3100 K. One of our goals was to examine the spectral emission of secondary species such as water vapor or carbon dioxide. The cold air stream injected in the plasma torch contained approximately 330 parts per million Of CO2, which is the natural CO2 concentration in atmospheric air at room temperature, and a small amount of water vapor with an estimated mole fraction of 3.8 x 10(exp -4). As can be seen from Figure 1, it was found that the measured spectrum exhibited intense spectral features due to the fundamental rovibrational bands of NO at 4.9 - 5.5 microns and the V(3) band of CO2 (antisymmetric stretch) at 4.2-4.8 microns. These observations confirmed the well-known fact that infrared signatures between 4.15 - 5.5 microns can be masked by radiative emission in the interceptor's bow-shock. Figure I also suggested that the range 3.2 - 4.15 microns did not contain any significant emission features (lines or continuum) that could mask IR signatures. However, the signal-to-noise level, close to one in that range, precluded definite conclusions. Thus, in an effort to further investigate the spectral emission in the range of interest to signature masking problem, new measurements were made with a higher signal-to-noise ratio and an extended wavelength range.

  5. Green binary and phase shifting mask

    NASA Astrophysics Data System (ADS)

    Shy, S. L.; Hong, Chao-Sin; Wu, Cheng-San; Chen, S. J.; Wu, Hung-Yu; Ting, Yung-Chiang

    2009-12-01

    SixNy/Ni thin film green mask blanks were developed , and are now going to be used to replace general chromium film used for binary mask as well as to replace molydium silicide embedded material for AttPSM for I-line (365 nm), KrF (248 nm), ArF (193 nm) and Contact/Proximity lithography. A bilayer structure of a 1 nm thick opaque, conductive nickel layer and a SixNy layer is proposed for binary and phase-shifting mask. With the good controlling of plasma CVD of SixNy under silane (50 sccm), ammonia (5 sccm) and nitrogen (100 sccm), the pressure is 250 mTorr. and RF frequency 13.56 MHz and power 50 W. SixNy has enough deposition latitude to meet the requirements as an embedded layer for required phase shift 180 degree, and the T% in 193, 248 and 365 nm can be adjusted between 2% to 20% for binary and phase shifting mask usage. Ni can be deposited by E-gun, its sheet resistance Rs is less than 1.435 kΩ/square. Jeol e-beam system and I-line stepper are used to evaluate these thin film green mask blanks, feature size less than 200 nm half pitch pattern and 0.558 μm pitch contact hole can be printed. Transmission spectrums of various thickness of SixNy film are inspected by using UV spectrometer and FTIR. Optical constants of the SixNy film are measured by n & k meter and surface roughness is inspected by using Atomic Force Microscope (AFM).

  6. Sensorimotor supremacy: Investigating conscious and unconscious vision by masked priming

    PubMed Central

    Ansorge, Ulrich; Neumann, Odmar; Becker, Stefanie I.; Kälberer, Holger; Cruse, Holk

    2008-01-01

    According to the sensorimotor supremacy hypothesis, conscious perception draws on motor action. In the present report, we will sketch two lines of potential development in the field of masking research based on the sensorimotor supremacy hypothesis. In the first part of the report, evidence is reviewed that masked, invisible stimuli can affect motor responses, attention shifts, and semantic processes. After the review of the corresponding evidence – so-called masked priming effects – an approach based on the sensorimotor supremacy hypothesis is detailed as to how the question of a unitary mechanism of unconscious vision can be pursued by masked priming studies. In the second part of the report, different models and theories of backward masking and masked priming are reviewed. Types of models based on the sensorimotor hypothesis are discussed that can take into account ways in which sensorimotor processes (reflected in masked priming effects) can affect conscious vision under backward masking conditions. PMID:20517513

  7. Lithographic performance evaluation of a contaminated EUV mask after cleaning

    SciTech Connect

    George, Simi; Naulleau, Patrick; Okoroanyanwu, Uzodinma; Dittmar, Kornelia; Holfeld, Christian; Wuest, Andrea

    2009-11-16

    The effect of surface contamination and subsequent mask surface cleaning on the lithographic performance of a EUV mask is investigated. SEMATECH's Berkeley micro-field exposure tool (MET) printed 40 nm and 50 nm line and space (L/S) patterns are evaluated to compare the performance of a contaminated and cleaned mask to an uncontaminated mask. Since the two EUV masks have distinct absorber architectures, optical imaging models and aerial image calculations were completed to determine any expected differences in performance. Measured and calculated Bossung curves, process windows, and exposure latitudes for the two sets of L/S patterns are compared to determine how the contamination and cleaning impacts the lithographic performance of EUV masks. The observed differences in mask performance are shown to be insignificant, indicating that the cleaning process did not appreciably affect mask performance.

  8. Variations in backward masking with different masking stimuli: II. The effects of spatially quantised masks in the light of local contour interaction, interchannel inhibition, perceptual retouch, and substitution theories.

    PubMed

    Bachmann, Talis; Luiga, Iiris; Põder, Endel

    2005-01-01

    In part I we showed that with spatially non-overlapping targets and masks both local metacontrast-like interactions and attentional processes are involved in backward masking. In this second part we extend the strategy of varying the contents of masks to pattern masking where targets and masks overlap in space, in order to compare different masking theories. Images of human faces were backward-masked by three types of spatially quantised masks (the same faces as targets, faces different from targets, and Gaussian noise with power spectra typical for faces). Configural characteristics, rather than the spectral content of the mask, predicted the extent of masking at relatively long stimulus onset asynchronies (SOAs). This poses difficulties for the theory of transient-on-sustained inhibition as the principal mechanism of masking and also for local contour interaction being a decisive factor in pattern masking. The scale of quantisation had no effect on the masking capacity of noise masks and a strong effect on the capacity of different-face masks. Also, the decrease of configural masking with an increase in the coarseness of the quantisation of the mask highlights ambiguities inherent in the re-entrance-based substitution theory of masking. Different masking theories cannot solve the problems of masking separately. They should be combined in order to create a complex, yet comprehensible mode of interaction for the different mechanisms involved in visual backward masking.

  9. Automated mask creation from a 3D model using Faethm.

    SciTech Connect

    Schiek, Richard Louis; Schmidt, Rodney Cannon

    2007-11-01

    We have developed and implemented a method which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micro-machining. The masks produced by this design tool can be generic, process independent masks, or if given process constraints, specific for a target process. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology of the model.

  10. Gas Diffusion in Metals: Fundamental Study of Helium-Point Defect Interactions in Iron and Kinetics of Hydrogen Desorption from Zirconium Hydride

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang

    The behavior of gaseous foreign species (e.g., helium and hydrogen), which are either generated, adsorbed or implanted within the structural materials (e.g., iron and zirconium) exposed to irradiation environments, is an important and largely unsolved topic, as they intensively interact with the irradiation-induced defects, or bond with the lattice atoms to form new compounds, and impose significant effects on their microstructural and mechanical properties in fission and fusion reactors. This research investigates two cases of gas diffusion in metals (i.e., the helium-point defect interactions in iron and kinetics of hydrogen desorption from zirconium hydride) through extensive experimental and modeling studies, with the objective of improving the understanding of helium effects on the microstructures of iron under irradiation and demonstrating the kinetics of hydrogen diffusion and precipitation behavior in zirconium that are crucial to predict cladding failures and hydride fuel performance. The study of helium effects in structural materials aims to develop a self-consistent, experimentally validated model of helium---point defect, defect cluster and intrinsic defects through detailed inter-comparisons between experimental measurements on helium ion implanted iron single crystals and computational models. The combination of thermal helium desorption spectrometry (THDS) experiment with the cluster dynamic model helps to reveal the influence of impurities on the energetics and kinetics of the He-defect interactions and to realize the identification of possible mechanisms governing helium desorption peaks. Positron annihilation spectroscopy is employed to acquire additional information on He-vacancy cluster evolution, which provides an opportunity to validate the model qualitatively. The inclusion of He---self-interstitial clusters extends the cluster dynamic model while MD simulations explore the effects of dislocation loops on helium clustering. In addition, the

  11. Helium transport in plasma edge regions

    NASA Astrophysics Data System (ADS)

    Abou-Gabal, Hanaa Hassan

    The transport of neutral helium atoms near diverter or limiter target plates in fusion devices was studied. Two simulation codes, based on Monte Carlo techniques, were developed. The first treats the problem in one-dimensional geometry and the second considers two-dimensional effects. The atomic processes of ionization of helium atoms by electron impact and elastic scattering with plasma ions are included. The total and differential elastic scattering cross-sections were calculated classically using an ab initio calculation of the interatomic potential. The thermal motion and the streaming of the ions along the magnetic field, which can be at an angle to the target plate, are included. Results obtained with the one-dimensional code show significant effects of elastic collisions below about 10 eV, causing a substantial fraction of the helium atoms to be reflected back to the target plate. This effect can be beneficial for the pumping of helium from the discharge chamber. The two-dimensional Monte Carlo code was used to study helium recycling near a flat, vented target plate. A parametric study is performed to examine the dependence of the pumping efficiency on plasma parameters and geometric aspects. Results show that the pumping of neutral helium can be increased by shortening and widening the ports as well as by increasing the angle between the magnetic field and the target plate. Also, keeping the ion temperature below about 10 eV and the plasma density around a few 10(exp 14) cu cm near the targe plate can be beneficial for the pumping of helium gas.

  12. How Does Target Duration Affect Object Substitution Masking?

    ERIC Educational Resources Information Center

    Gellatly, Angus; Pilling, Michael; Carter, Wakefield; Guest, Duncan

    2010-01-01

    Object substitution masking (OSM) is typically studied using a brief search display. The target item may be indicated by a cue/mask surrounding but not overlapping it. Report of the target is reduced when mask offset trails target offset rather than being simultaneous with it. We report 5 experiments investigating whether OSM can be obtained if…

  13. How color, regularity, and good Gestalt determine backward masking.

    PubMed

    Sayim, Bilge; Manassi, Mauro; Herzog, Michael

    2014-06-18

    The strength of visual backward masking depends on the stimulus onset asynchrony (SOA) between target and mask. Recently, it was shown that the conjoint spatial layout of target and mask is as crucial as SOA. Particularly, masking strength depends on whether target and mask group with each other. The same is true in crowding where the global spatial layout of the flankers and target-flanker grouping determine crowding strength. Here, we presented a vernier target followed by different flanker configurations at varying SOAs. Similar to crowding, masking of a red vernier target was strongly reduced for arrays of 10 green compared with 10 red flanking lines. Unlike crowding, single green lines flanking the red vernier showed strong masking. Irregularly arranged flanking lines yielded stronger masking than did regularly arranged lines, again similar to crowding. While cuboid flankers reduced crowding compared with single lines, this was not the case in masking. We propose that, first, masking is reduced when the flankers are part of a larger spatial structure. Second, spatial factors counteract color differences between the target and the flankers. Third, complex Gestalts, such as cuboids, seem to need longer processing times to show ungrouping effects as observed in crowding. Strong parallels between masking and crowding suggest similar underlying mechanism; however, temporal factors in masking additionally modulate performance, acting as an additional grouping cue.

  14. Homophone Dominance Modulates the Phonemic-Masking Effect.

    ERIC Educational Resources Information Center

    Berent, Iris; Van Orden, Guy C.

    2000-01-01

    Finds (1) positive phonemic-masking effects occurred for dominant homophones; (2) null phonemic-masking effects occurred for subordinate homophones; and (3) subordinate homophones were much more likely to be falsely identified as their dominant mate. Suggests the source of these null phonemic-masking is itself a phonology effect. Concludes…

  15. Scatterometry on pelliclized masks: an option for wafer fabs

    NASA Astrophysics Data System (ADS)

    Gallagher, Emily; Benson, Craig; Higuchi, Masaru; Okumoto, Yasuhiro; Kwon, Michael; Yedur, Sanjay; Li, Shifang; Lee, Sangbong; Tabet, Milad

    2007-03-01

    Optical scatterometry-based metrology is now widely used in wafer fabs for lithography, etch, and CMP applications. This acceptance of a new metrology method occurred despite the abundance of wellestablished CD-SEM and AFM methods. It was driven by the desire to make measurements faster and with a lower cost of ownership. Over the last year, scatterometry has also been introduced in advanced mask shops for mask measurements. Binary and phase shift masks have been successfully measured at all desired points during photomask production before the pellicle is mounted. There is a significant benefit to measuring masks with the pellicle in place. From the wafer fab's perspective, through-pellicle metrology would verify mask effects on the same features that are characterized on wafer. On-site mask verification would enable quality control and trouble-shooting without returning the mask to a mask house. Another potential application is monitoring changes to mask films once the mask has been delivered to the fab (haze, oxide growth, etc.). Similar opportunities apply to the mask metrologist receiving line returns from a wafer fab. The ability to make line-return measurements without risking defect introduction is clearly attractive. This paper will evaluate the feasibility of collecting scatterometry data on pelliclized masks. We explore the effects of several different pellicle types on scatterometry measurements made with broadband light in the range of 320-780 nm. The complexity introduced by the pellicles' optical behavior will be studied.

  16. 21 CFR 868.5550 - Anesthetic gas mask.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Anesthetic gas mask. 868.5550 Section 868.5550...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5550 Anesthetic gas mask. (a) Identification. An anesthetic gas mask is a device, usually made of conductive rubber, that is positioned over...

  17. 21 CFR 868.5550 - Anesthetic gas mask.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Anesthetic gas mask. 868.5550 Section 868.5550...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5550 Anesthetic gas mask. (a) Identification. An anesthetic gas mask is a device, usually made of conductive rubber, that is positioned over...

  18. 21 CFR 868.5550 - Anesthetic gas mask.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Anesthetic gas mask. 868.5550 Section 868.5550...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5550 Anesthetic gas mask. (a) Identification. An anesthetic gas mask is a device, usually made of conductive rubber, that is positioned over...

  19. 21 CFR 868.5550 - Anesthetic gas mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anesthetic gas mask. 868.5550 Section 868.5550...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5550 Anesthetic gas mask. (a) Identification. An anesthetic gas mask is a device, usually made of conductive rubber, that is positioned over...

  20. 21 CFR 868.5550 - Anesthetic gas mask.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Anesthetic gas mask. 868.5550 Section 868.5550...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5550 Anesthetic gas mask. (a) Identification. An anesthetic gas mask is a device, usually made of conductive rubber, that is positioned over...

  1. An unattended mask makes an attended target disappear.

    PubMed

    Veenemans, Arielle A; Cavanagh, Patrick

    2015-01-01

    In pattern masking, the target and mask are presented at the same location and follow one another very closely in time. When the observer attends to the target, he or she must also attend to the mask, as the switching time for attention is quite slow. In a series of experiments, we present mask-target-mask sequences staggered in time and location (Cavanagh, Holcombe, & Chou, 2008) that allow participants to attentively track the target location without attending to the masks. The results show that the strength of masking is on average unaffected by the removal of attention from the masks. Moreover, after isolating the target location perceptually with moving attention, it is clear that the target, when at threshold, has not been degraded or integrated with a persisting mask but it has vanished. We also show that the strength of masking is unaffected by the lateral spacing between adjacent target and mask sequences until the spacing is so large that the apparent motion driving the attentive tracking breaks down. Finally, we compare the effect of the pre- and postmask and find that the premask is responsible for the larger part of the masking.

  2. Model-based mask data preparation (MB-MDP) for ArF and EUV mask process correction

    NASA Astrophysics Data System (ADS)

    Hagiwara, Kazuyuki; Bork, Ingo; Fujimura, Aki

    2011-05-01

    Using Model-Based Mask Data Preparation (MB-MDP) complex masks with complex sub-resolution assist features (SRAFs) can be written in practical write times with today's leading-edge production VSB machines by allowing overlapping VSB shots. This simulation-based approach reduces shot count by taking advantage of the added flexibility in being able to overlap shots. The freedom to overlap shots, it turns out, also increases mask fidelity, CDU on the mask, and CDU on the wafer by writing sub-100nm mask features more accurately, and with better dose margin. This paper describes how overlapping shots enhance mask and wafer quality for various sub-100nm features on ArF masks. In addition, this paper describes how EUV mask accuracy can be enhanced uniquely by allowing overlapping shots.

  3. Helium isotopes in ferromanganese crusts from the central Pacific Ocean

    USGS Publications Warehouse

    Basu, S.; Stuart, F.M.; Klemm, V.; Korschinek, G.; Knie, K.; Hein, J.R.

    2006-01-01

    Helium isotopes have been measured in samples of two ferromanganese crusts (VA13/2 and CD29-2) from the central Pacific Ocean. With the exception of the deepest part of crust CD29-2 the data can be explained by a mixture of implanted solar- and galactic cosmic ray-produced (GCR) He, in extraterrestrial grains, and radiogenic He in wind-borne continental dust grains. 4He concentrations are invariant and require retention of less than 12% of the in situ He produced since crust formation. Loss has occurred by recoil and diffusion. High 4He in CD29-2 samples older than 42 Ma are correlated with phosphatization and can be explained by retention of up to 12% of the in situ-produced 4He. 3He/4He of VA13/2 samples varies from 18.5 to 1852 Ra due almost entirely to variation in the extraterrestrial He contribution. The highest 3He/4He is comparable to the highest values measured in interplanetary dust particles (IDPs) and micrometeorites (MMs). Helium concentrations are orders of magnitude lower than in oceanic sediments reflecting the low trapping efficiency for in-falling terrestrial and extraterrestrial grains of Fe-Mn crusts. The extraterrestrial 3He concentration of the crusts rules out whole, undegassed 4–40 μm diameter IDPs as the host. Instead it requires that the extraterrestrial He inventory is carried by numerous particles with significantly lower He concentrations, and occasional high concentration GCR-He-bearing particles.

  4. 42 CFR 84.118 - Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.118 Half-mask facepieces, full facepieces, and... reduce the respiratory protective qualities of the gas mask. (c) Half-mask facepieces shall not...

  5. 42 CFR 84.118 - Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.118 Half-mask facepieces, full facepieces, and... reduce the respiratory protective qualities of the gas mask. (c) Half-mask facepieces shall not...

  6. 42 CFR 84.118 - Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.118 Half-mask facepieces, full facepieces, and... reduce the respiratory protective qualities of the gas mask. (c) Half-mask facepieces shall not...

  7. 42 CFR 84.118 - Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.118 Half-mask facepieces, full facepieces, and... reduce the respiratory protective qualities of the gas mask. (c) Half-mask facepieces shall not...

  8. 42 CFR 84.118 - Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.118 Half-mask facepieces, full facepieces, and... reduce the respiratory protective qualities of the gas mask. (c) Half-mask facepieces shall not...

  9. Effects Of Unsharp Masking On Color Reproduction

    NASA Astrophysics Data System (ADS)

    Molla, R. K.

    1990-06-01

    Unsharp Masking, abbreviated as USM, is one of the few terms that is transferred from photographic color separation technique to modern electronic separation in a scanner. In photographic separation, the color correction mask is made unsharp to enhance details in the reproduction. In a color separation scanner, the principles remained the same, however, a different technique is used to create an optical illusion to enhance sharpness or details in the reproduction. During scanning, when there is a change of density in the copy, two fine lines are generated at the borders of the transition, a lighter line and a darker line at the borders of light and dark edges respectively of the density change. This is possible by scanning the copy with the main aperture as well as a separate larger aperture called unsharp masking aperture. When the separation is in progress, the signal from the unsharp masking aperture is compared with the signal from the main scanning aperture at a differential stage in the computer. If there is a density change in the copy, the larger unsharp masking aperture senses the change sooner than the smaller main aperture, and at this point, an additional signal is generated and added to the main signal. This makes it possible to create the black and white lines at the borders of a density change. In addition to this function, the same black and white lines can also be produced at the borders of transition of a color by transmitting the unsharp masking beam through any one of red, green, or blue filters. A combination of these apertures and filters can be selected by adjusting a pair of wheels located on the scanning head as in Hell scanners, or by changing specific inserts as in Dainippon Screen scanners. When used moderately, the black and white lines at the borders of a density or color change will create the effects of sharper details in the reproduction. In addition to the above mechanical controls, electronic controls are also provided in most

  10. Ion Implanted Gaas Integrated Optics Fabrication Technology

    NASA Astrophysics Data System (ADS)

    Mentzer, M. A.; Hunsperger, R. G.; Bartko, J.; Zavada, J. M.; Jenkinson, H. A.

    1985-01-01

    Ion implantation of semiconductor materials is a fabrication technique that offers a number of distinct advantages for the formation of guided-wave components and microelectronic devices. Implanted damage and dopants produce optical and electronic changes that can be utilized for sensing and signal processing applications. GaAs is a very attractive material for optical fabrication since it is transparent out to the far infrared. It can be used to fabricate optical waveguides, directional couplers, EO modulators, and detectors, as well as other guided wave structures. The presence of free carriers in GaAs lowers the refractive index from that of the pure semiconductor material. This depression of the refractive index is primarily due to the negative contribution of the free carrier plasma to the dielectric constant of the semiconductor. Bombardment of n-type GaAs by protons creates damage sites near the surface of the crystal structure where free carriers are trapped. This "free carrier compensated" region in the GaAs has a higher refractive index than the bulk region. If the compensated region is sufficiently thick and has a refractive index which is sufficiently larger than that of the bulk n-type region, an optical waveguide is formed. In this paper, a description of ion implantation techniques for the fabrication of both planar and channel integrated optical structures in GaAs is presented, and is related to the selection of ion species, implant energy and fluence, and to the physical processes involved. Lithographic technology and masking techniques are discussed for achieving a particular desired implant profile. Finally, the results of a set of ion implantation experiments are presented.

  11. Suicide by asphyxiation due to helium inhalation.

    PubMed

    Howard, Matthew O; Hall, Martin T; Edwards, Jeffrey D; Vaughn, Michael G; Perron, Brian E; Winecker, Ruth E

    2011-03-01

    Suicide by asphyxiation using helium is the most widely-promoted method of "self-deliverance" by right-to-die advocates. However, little is known about persons committing such suicides or the circumstances and manner in which they are completed. Prior reports of suicides by asphyxiation involving helium were reviewed and deaths determined by the North Carolina Office of the Chief Medical Examiner to be helium-associated asphyxial suicides occurring between January 1, 2000 and December 31, 2008 were included in a new case series examined in this article. The 10 asphyxial suicides involving helium identified in North Carolina tended to occur almost exclusively in non-Hispanic, white men who were relatively young (M age = 41.1 T 11.6). In 6 of 10 cases, decedents suffered from significant psychiatric dysfunction; in 3 of these 6 cases, psychiatric disorders were present comorbidly with substance abuse. In none of these cases were decedents suffering from terminal illness. Most persons committing suicide with helium were free of terminal illness but suffered from psychiatric and/or substance use disorders.

  12. Thermal Performance of the XRS Helium Insert

    NASA Technical Reports Server (NTRS)

    Breon, Susan R.; DiPirro, Michael J.; Tuttle, James G.; Shirron, Peter J.; Warner, Brent A.; Boyle, Robert F.; Canavan, Edgar R.

    1999-01-01

    The X-Ray Spectrometer (XRS) is an instrument on the Japanese Astro-E satellite, scheduled for launch early in the year 2000. The XRS Helium Insert comprises a superfluid helium cryostat, an Adiabatic Demagnetization Refrigerator (ADR), and the XRS calorimeters with their cold electronics. The calorimeters are capable of detecting X-rays over the energy range 0.1 to 10 keV with a resolution of 12 eV. The Helium Insert completed its performance and verification testing at Goddard in January 1999. It was shipped to Japan, where it has been integrated with the neon dewar built by Sumitomo Heavy Industries. The Helium Insert was given a challenging lifetime requirement of 2.0 years with a goal of 2.5 years. Based on the results of the thermal performance tests, the predicted on-orbit lifetime is 2.6 years with a margin of 30%. This is the result of both higher efficiency in the ADR cycle and the low temperature top-off, more than compensating for an increase in the parasitic heat load. This paper presents a summary of the key design features and the results of the thermal testing of the XRS Helium Insert.

  13. BASG thermomechanical pump helium 2 transfer tests

    NASA Technical Reports Server (NTRS)

    Mills, G. L.; Newell, D. A.; Urbach, A. R.

    1990-01-01

    The purpose of the effort described was to perform experiments and calculations related to using a thermomechanical pump in the space-based resupply of the Space Infrared Telescope Facility (SIRTF) with Helium 2. Thermomechanical (fountain effect) pumps have long been suggested as a means for pumping large quantities of Helium 2. The unique properties of Helium 2 have made it useful for cooling space instruments. Several space science missions, including SIRTF, are now being planned which would benefit greatly from on-orbit resupply of Helium 2. A series of experiments were performed to demonstrate that large volumes of Helium 2 can be transferred with a thermomechanical pump at high flow rates and at high efficiency from one dewar to another through valves and lines that are similar to the plumbing arrangement that would be necessary to accomplish such a transfer on-orbit. In addition, temperature, pressure, and flow rate data taken during the tests were used to verify and refine a computer model which was developed.

  14. Hydrodynamic simulations of the core helium flash

    NASA Astrophysics Data System (ADS)

    Mocák, Miroslav; Müller, Ewald; Weiss, Achim; Kifonidis, Konstantinos

    2008-10-01

    We desribe and discuss hydrodynamic simulations of the core helium flash using an initial model of a 1.25 M⊙ star with a metallicity of 0.02 near at its peak. Past research concerned with the dynamics of the core helium flash is inconclusive. Its results range from a confirmation of the standard picture, where the star remains in hydrostatic equilibrium during the flash (Deupree 1996), to a disruption or a significant mass loss of the star (Edwards 1969; Cole & Deupree 1980). However, the most recent multidimensional hydrodynamic study (Dearborn et al. 2006) suggests a quiescent behavior of the core helium flash and seems to rule out an explosive scenario. Here we present partial results of a new comprehensive study of the core helium flash, which seem to confirm this qualitative behavior and give a better insight into operation of the convection zone powered by helium burning during the flash. The hydrodynamic evolution is followed on a computational grid in spherical coordinates using our new version of the multi-dimensional hydrodynamic code HERAKLES, which is based on a direct Eulerian implementation of the piecewise parabolic method.

  15. TRANSPARENT HELIUM IN STRIPPED ENVELOPE SUPERNOVAE

    SciTech Connect

    Piro, Anthony L.; Morozova, Viktoriya S.

    2014-09-01

    Using simple arguments based on photometric light curves and velocity evolution, we propose that some stripped envelope supernovae (SNe) show signs that a significant fraction of their helium is effectively transparent. The main pieces of evidence are the relatively low velocities with little velocity evolution, as are expected deep inside an exploding star, along with temperatures that are too low to ionize helium. This means that the helium should not contribute to the shaping of the main SN light curve, and thus the total helium mass may be difficult to measure from simple light curve modeling. Conversely, such modeling may be more useful for constraining the mass of the carbon/oxygen core of the SN progenitor. Other stripped envelope SNe show higher velocities and larger velocity gradients, which require an additional opacity source (perhaps the mixing of heavier elements or radioactive nickel) to prevent the helium from being transparent. We discuss ways in which similar analysis can provide insights into the differences and similarities between SNe Ib and Ic, which will lead to a better understanding of their respective formation mechanisms.

  16. Oronasal Masks Require a Higher Pressure than Nasal and Nasal Pillow Masks for the Treatment of Obstructive Sleep Apnea

    PubMed Central

    Deshpande, Sheetal; Joosten, Simon; Turton, Anthony; Edwards, Bradley A.; Landry, Shane; Mansfield, Darren R.; Hamilton, Garun S.

    2016-01-01

    Study Objectives: Oronasal masks are frequently used for continuous positive airway pressure (CPAP) treatment in patients with obstructive sleep apnea (OSA). The aim of this study was to (1) determine if CPAP requirements are higher for oronasal masks compared to nasal mask interfaces and (2) assess whether polysomnography and patient characteristics differed among mask preference groups. Methods: Retrospective analysis of all CPAP implementation polysomnograms between July 2013 and June 2014. Prescribed CPAP level, polysomnography results and patient data were compared according to mask type (n = 358). Results: Oronasal masks were used in 46%, nasal masks in 35% and nasal pillow masks in 19%. There was no difference according to mask type for baseline apnea-hypopnea index (AHI), body mass index (BMI), waist or neck circumference. CPAP level was higher for oronasal masks, 12 (10–15.5) cm H2O compared to nasal pillow masks, 11 (8–12.5) cm H2O and nasal masks, 10 (8–12) cm H2O, p < 0.0001 (Median [interquartile range]). Oronasal mask type, AHI, age, and BMI were independent predictors of a higher CPAP pressure (p < 0.0005, adjusted R2 = 0.26.). For patients with CPAP ≥ 15 cm H2O, there was an odds ratio of 4.5 (95% CI 2.5–8.0) for having an oronasal compared to a nasal or nasal pillow mask. Residual median AHI was higher for oronasal masks (11.3 events/h) than for nasal masks (6.4 events/h) and nasal pillows (6.7 events/h), p < 0.001. Conclusions: Compared to nasal mask types, oronasal masks are associated with higher CPAP pressures (particularly pressures ≥ 15 cm H2O) and a higher residual AHI. Further evaluation with a randomized control trial is required to definitively establish the effect of mask type on pressure requirements. Commentary: A commentary on this article appears in this issue on page 1209. Citation: Deshpande S, Joosten S, Turton A, Edwards BA, Landry S, Mansfield DR, Hamilton GS. Oronasal masks require a higher pressure than nasal and

  17. In collaboration with mask suppliers for change management enhancement

    NASA Astrophysics Data System (ADS)

    Deng, Erwin; Lee, Chun Der; Lee, Rachel

    2013-06-01

    For those wafer fabs that have no their own maskshops, the main target of mask quality department is to gain stable mask quality performance through effective supplier management, and therefore achieves competitive business results. After dealing with lots of mask data preparation (MDP) quality problems with suppliers, we have found that incomplete change management procedures are one of major sources that induce incorrect mask data for writing. This article will share our experience in how to enhance change management flows with mask suppliers together and will also show the utility after a series of flow improvement actions.

  18. Diffusion of helium in carbonates: Effects of mineral structure and composition

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Amidon, W.; Hobbs, D.; Watson, E. B.

    2015-09-01

    Diffusion of helium has been characterized in four carbonates: calcite, dolomite, magnesite, and aragonite. Cleaved or oriented and polished slabs of carbonate minerals were implanted with 100 keV or 3 MeV 3He at doses of 5 × 10153He/cm2 and 1 × 10163He/cm2, respectively, and annealed in 1-atm furnaces. 3He distributions following diffusion experiments were measured with nuclear reaction analysis using the reaction 3He(d,p)4He. Our results show that He diffusion in calcite is the fastest among the carbonates studied, with diffusivities progressively slower in magnesite, dolomite and aragonite. In the case of the isomorphic trigonal carbonates (calcite, dolomite, magnesite), these observations are broadly consistent with predictions based on lattice characteristics such as unit cell size and inter-atomic apertures, with diffusivities faster in more open carbonate structures. Dolomite is an exception to this trend, suggesting that its unique ordered R3 crystal structure may play a role in slowing helium diffusion. Diffusion is anisotropic in all of the trigonal carbonates, and is typically slowest for diffusion along the c direction, and faster for diffusion normal to c and in directions normal to cleavage surfaces. The patterns of diffusional anisotropy are predicted to first order by the size of limiting inter-atomic apertures along any given crystallographic direction, providing additional support to the concept of modeling crystal lattices as "molecular sieves" with regard to diffusion of helium. When the effects of anisotropy and diffusion domain size are considered, our results are in reasonable agreement with previous results from bulk degassing of natural samples. Modeling of helium diffusive loss shows that calcite and magnesite are unlikely to be retentive of helium on the Earth's surface for typical grain sizes and time/temperature conditions. Dolomite and aragonite may be retentive under cooler conditions, but because helium retention is strongly

  19. Applicability of e-beam mask inspection to EUV mask production

    NASA Astrophysics Data System (ADS)

    Shoval, Lior; Mangan, Shmoolik; Schwarzband, Ishai; Khristo, Sergey; Balasubramanian, Vivek; Goldstein, Shay; Brikman, Ran; Shoshani, Nir

    2012-03-01

    Ever since the 180nm technology node the semiconductor industry has been battling the sub-wavelength regime in optical lithography. During the same time development for a 13.5nm Extreme Ultraviolet [EUV] solution has been in development, which would take us back from a λ/10 to a >λ regime again - at least for one node. Add to this the potential to increase the wafer size as well, and we are at a major crossroads. The introduction of EUV has been marred by many delays, but we are finally seeing the hardware development efforts converge and multiple customers around the world embarking on this adventure. As it becomes clear that this preproduction phase will occur at or below 20nmHP, it also becomes clear that this will happen at the limiting edge of existing 19x-based patterned mask inspection technology, reaching the practical resolution limits at around 20nm HP mask densities. Resolution is coupled with sensitivity and throughput such that the extended sensitivity may come at an unreasonable throughput. Loss of resolution also badly impacts defect dispositioning, or classification, which becomes impractical. As resolution is especially critical for die to database inspection, single die masks and masks with high flare bias are at risk of not being inspectable with 19xnm based inspectors. E-Beam based mask inspection has been proposed and demonstrated as a viable technology for patterned EUV mask inspection. In this paper, we study the key questions of sensitivity and throughput, in both die-to-die and die-to-database applications. We present new results, based on a new generation of E-Beam inspection technology, which has a higher data rate at smaller spot sizes. We will demonstrate the feasibility of acceptable inspection time with EBMI. We also will discuss die-to-data-base inspection and the advantage of using E-Beam imaging for meeting future requirements of single- die EUV masks.

  20. IBIS mask pre-calibration matrix

    NASA Astrophysics Data System (ADS)

    Reglero, V.; Sánchez, F.; Rodrigo, J.; Velasco, T.; Gasent, J. L.; Chato, R.; Alamo, J.; Burgos, J. A.; Suso, J.; Blay, P.; Martínez, S.; Doñate, M.; Reina, M.; Sabau, D.; Ruiz-Urien, I.; Santos, I.; Zarauz, J.; Vázquez, J.

    2001-09-01

    Coded Aperture System performances are defined by the geometry of the code, detector pixel geometry relationship and focal length. Physical Coded Aperture Systems deviate from the ideal ones on two basic aspects: uncertainties on pixel location and size coming form the manufacturing process and deviations from their theoretical transparency/opacity values (1/0, 0/1), when support structures are required. Mask support structure imposes penalties on transparency as a function of the energy and angle of the incident photons. Pixel position and size values include uncertainties coming from the code cut in tungsten plates and assembly process. The scope of this paper is to summarize the results of the code elements position and size, as well as transparency/opacity values found for the IBIS Coded Aperture System. Both sets of data define the optical performances of the IBIS Mask required to perform accurate imaging of celestial gamma-ray sources.

  1. Phase measurements of EUV mask defects

    DOE PAGES

    Claus, Rene A.; Wang, Yow-Gwo; Wojdyla, Antoine; ...

    2015-02-22

    Extreme Ultraviolet (EUV) Lithography mask defects were examined on the actinic mask imaging system, SHARP, at Lawrence Berkeley National Laboratory. Also, a quantitative phase retrieval algorithm based on the Weak Object Transfer Function was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects. The accuracy of the algorithm was demonstrated by comparing the results of measurements using a phase contrast zone plate and a standard zone plate. Using partially coherent illumination to measure frequencies that would otherwise fall outside the numerical aperture (NA), it was shown that some defects are smaller than themore » conventional resolution of the microscope. We found that the programmed defects of various sizes were measured and shown to have both an amplitude and a phase component that the algorithm is able to recover.« less

  2. Phase measurements of EUV mask defects

    SciTech Connect

    Claus, Rene A.; Wang, Yow-Gwo; Wojdyla, Antoine; Benk, Markus P.; Goldberg, Kenneth A.; Neureuther, Andrew R.; Naulleau, Patrick P.; Waller, Laura

    2015-02-22

    Extreme Ultraviolet (EUV) Lithography mask defects were examined on the actinic mask imaging system, SHARP, at Lawrence Berkeley National Laboratory. Also, a quantitative phase retrieval algorithm based on the Weak Object Transfer Function was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects. The accuracy of the algorithm was demonstrated by comparing the results of measurements using a phase contrast zone plate and a standard zone plate. Using partially coherent illumination to measure frequencies that would otherwise fall outside the numerical aperture (NA), it was shown that some defects are smaller than the conventional resolution of the microscope. We found that the programmed defects of various sizes were measured and shown to have both an amplitude and a phase component that the algorithm is able to recover.

  3. Masking mediated print defect visibility predictor

    NASA Astrophysics Data System (ADS)

    Jing, Xiaochen; Nachlieli, Hila; Shaked, Doron; Shiffman, Smadar; Allebach, Jan P.

    2012-01-01

    Banding is a well-known artifact produced by printing systems. It usually appears as lines perpendicular to the process direction of the print. Therefore, banding is an important print quality issue which has been analyzed and assessed by many researchers. However, little literature has focused on the study of the masking effect of content for this kind of print quality issue. Compared with other image and print quality research, our work is focused on the print quality of typical documents printed on a digital commercial printing press. In this paper, we propose a Masking Mediated Print Defect Visibility Predictor (MMPDVP) to predict the visibility of defects in the presence of customer content. The parameters of the algorithm are trained from ground-truth images that have been marked by subjects. The MMPDVP could help the press operator decide whether the print quality is acceptable for specific customer requirements. Ultimately, this model can be used to optimize the print-shop workflow.

  4. Latent inhibition in human adults without masking.

    PubMed

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R

    2003-09-01

    Latent inhibition refers to attenuated responding to Cue X observed when the X-outcome pairings are preceded by X-alone presentations. It has proven difficult to obtain in human adults unless the preexposure (X-alone) presentations are embedded within a masking (i.e., distracting) task. The authors hypothesized that the difficulty in obtaining latent inhibition with unmasked tasks is related to the usual training procedures, in which the preexposure and conditioning experiences are separated by a set of instructions. Experiment 1 reports latent inhibition without masking in a task in which preexposure and conditioning occur without interruption. Experiments 2 and 3 demonstrate that this attenuation in responding to target Cue X does not pass a summation test for conditioned inhibition and is context specific, thereby confirming that it is latent inhibition. Experiments 3 and 4 confirm that introducing instructions between preexposure and conditioning disrupts latent inhibition.

  5. Site specific isolated nanostructure array formation on a large area by broad ion beam without any mask and resist

    SciTech Connect

    Karmakar, Prasanta

    2014-06-09

    We report the formation of isolated nanostructure arrays on a large area via broad ion beam implantation without the aid of any mask or resist. Desired ions have been implanted at specific locations of the prefabricated silicon ripple or triangular structures by exploiting the variation of local ion impact angles. We have shown that the implantation of Fe ions on an O{sup +} ions induced pre fabricated triangular shaped patterned Si surface results in a self-organized periodic array of striped magnetic nanostructures having several micron length and about 50 nm width arranged with a spacial separation of ∼200 nm. The morphology, composition, crystalline structure, and magnetic property of these nanopatterns have been analyzed using high-resolution cross-sectional transmission electron microscopy and atomic force microscopy. A geometrical model has been proposed to explain the fundamental features of such ion-induced nanopattern structures.

  6. The EOS CERES Global Cloud Mask

    NASA Technical Reports Server (NTRS)

    Berendes, T. A.; Welch, R. M.; Trepte, Q.; Schaaf, C.; Baum, B. A.

    1996-01-01

    To detect long-term climate trends, it is essential to produce long-term and consistent data sets from a variety of different satellite platforms. With current global cloud climatology data sets, such as the International Satellite Cloud Climatology Experiment (ISCCP) or CLAVR (Clouds from Advanced Very High Resolution Radiometer), one of the first processing steps is to determine whether an imager pixel is obstructed between the satellite and the surface, i.e., determine a cloud 'mask.' A cloud mask is essential to studies monitoring changes over ocean, land, or snow-covered surfaces. As part of the Earth Observing System (EOS) program, a series of platforms will be flown beginning in 1997 with the Tropical Rainfall Measurement Mission (TRMM) and subsequently the EOS-AM and EOS-PM platforms in following years. The cloud imager on TRMM is the Visible/Infrared Sensor (VIRS), while the Moderate Resolution Imaging Spectroradiometer (MODIS) is the imager on the EOS platforms. To be useful for long term studies, a cloud masking algorithm should produce consistent results between existing (AVHRR) data, and future VIRS and MODIS data. The present work outlines both existing and proposed approaches to detecting cloud using multispectral narrowband radiance data. Clouds generally are characterized by higher albedos and lower temperatures than the underlying surface. However, there are numerous conditions when this characterization is inappropriate, most notably over snow and ice of the cloud types, cirrus, stratocumulus and cumulus are the most difficult to detect. Other problems arise when analyzing data from sun-glint areas over oceans or lakes over deserts or over regions containing numerous fires and smoke. The cloud mask effort builds upon operational experience of several groups that will now be discussed.

  7. Mask Analysis Program (MAP) reference manual

    NASA Technical Reports Server (NTRS)

    Mitchell, C. L.

    1976-01-01

    A document intended to serve as a User's Manual and a Programmer's Manual for the Mask Analysis Program is presented. The first portion of the document is devoted to the user. It contains all of the information required to execute MAP. The remainder of the document describes the details of MAP software logic. Although the information in this portion is not required to run the program, it is recommended that every user review it to gain an appreciation for the program functions.

  8. Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

    NASA Astrophysics Data System (ADS)

    Himics, L.; Tóth, S.; Veres, M.; Tóth, A.; Koós, M.

    2015-02-01

    Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750 °C, 450 °C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71 eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation.

  9. Mask image position correction for double patterning lithography

    NASA Astrophysics Data System (ADS)

    Saito, Masato; Itoh, Masamitsu; Ikenaga, Osamu; Ishigo, Kazutaka

    2008-05-01

    Application of double patterning technique has been discussed for lithography of HP 3X nm device generation. In this case, overlay budget for lithography becomes so hard that it is difficult to achieve it with only improvement of photomask's position accuracy. One of the factors of overlay error will be induced by distortion of photomask after chucking on the mask stage of exposure tool, because photomasks are bended by the force of vacuum chucking. Recently, mask flatness prediction technique was developed. This technique is simulating the surface shape of mask when it is on the mask stage by using the flatness data of free-standing state blank and the information of mask chucking stage. To use this predicted flatness data, it is possible to predict a pattern position error after exposed and it is possible to correct it on the photomask. A blank supplier developed the flatness data transfer system to mask vender. Every blanks are distinguished individually by 2D barcode mark on blank which including serial number. The flatness data of each blank is linked with this serial number, and mask vender can use this serial number as a key code to mask flatness data. We developed mask image position correction system by using 2D barcode mark linked to predicted flatness data, and position accuracy assurance system for these masks. And with these systems, we made some masks actually.

  10. Helium Speech: An Application of Standing Waves

    NASA Astrophysics Data System (ADS)

    Wentworth, Christopher D.

    2011-04-01

    Taking a breath of helium gas and then speaking or singing to the class is a favorite demonstration for an introductory physics course, as it usually elicits appreciative laughter, which serves to energize the class session. Students will usually report that the helium speech "raises the frequency" of the voice. A more accurate description of the phenomenon requires that we distinguish between the frequencies of sound produced by the larynx and the filtering of those frequencies by the vocal tract. We will describe here an experiment done by introductory physics students that uses helium speech as a context for learning about the human vocal system and as an application of the standing sound-wave concept. Modern acoustic analysis software easily obtained by instructors for student use allows data to be obtained and analyzed quickly.

  11. Quantum Halo States in Helium Tetramers.

    PubMed

    Stipanović, Petar; Vranješ Markić, Leandra; Boronat, Jordi

    2017-01-12

    The universality of quantum halo states enables a comparison of systems from different fields of physics, as demonstrated in two- and three-body clusters. In the present work, we studied weakly bound helium tetramers in order to test whether some of these four-body realistic systems qualify as halos. Their ground-state binding energies and structural properties were thoroughly estimated using the diffusion Monte Carlo method with pure estimators. Helium tetramer properties proved to be less sensitive on the potential model than previously evaluated trimer properties. We predict the existence of realistic four-body halo (4)He2(3)He2, whereas (4)He4 and (4)He3(3)He are close to the border and thus can be used as prototypes of quasi-halo systems. Our results could be tested by the experimental determination of the tetramers' structural properties using a setup similar to the one developed for the study of helium trimers.

  12. Helium corona-assisted air discharge

    SciTech Connect

    Jiang Nan; Gao Lei; Ji Ailing; Cao Zexian

    2011-10-15

    Operation of atmospheric discharge of electronegative gases including air at low voltages yet without consuming any inert gas will enormously promote the application of non-thermal plasmas. By taking advantage of the low onset voltage for helium corona, air discharge was successfully launched at much reduced voltages with a needle-plate system partly contained in a helium-filled glass bulb--for a needle-plate distance of 12 mm, 1.0 kV suffices. Ultraviolet emission from helium corona facilitates the discharging of air, and the discharge current manifests distinct features such as relatively broad Trichel pulses in both half periods. This design allows safe and economic implementation of atmospheric discharge of electronegative gases, which will find a broad palette of applications in surface modification, plasma medicine and gas treatment, etc.

  13. Feasibility of lunar Helium-3 mining

    NASA Astrophysics Data System (ADS)

    Kleinschneider, Andreas; Van Overstraeten, Dmitry; Van der Reijnst, Roy; Van Hoorn, Niels; Lamers, Marvin; Hubert, Laurent; Dijk, Bert; Blangé, Joey; Hogeveen, Joel; De Boer, Lennaert; Noomen, Ron

    With fossil fuels running out and global energy demand increasing, the need for alternative energy sources is apparent. Nuclear fusion using Helium-3 may be a solution. Helium-3 is a rare isotope on Earth, but it is abundant on the Moon. Throughout the space community lunar Helium-3 is often cited as a major reason to return to the Moon. Despite the potential of lunar Helium-3 mining, little research has been conducted on a full end-to-end mission. This abstract presents the results of a feasibility study conducted by students from Delft University of Technology. The goal of the study was to assess whether a continuous end-to-end mission to mine Helium-3 on the Moon and return it to Earth is a viable option for the future energy market. The set requirements for the representative end-to-end mission were to provide 10% of the global energy demand in the year 2040. The mission elements have been selected with multiple trade-offs among both conservative and novel concepts. A mission architecture with multiple decoupled elements for each transportation segment (LEO, transfer, lunar surface) was found to be the best option. It was found that the most critical element is the lunar mining operation itself. To supply 10% of the global energy demand in 2040, 200 tons of Helium-3 would be required per year. The resulting regolith mining rate would be 630 tons per second, based on an optimistic concentration of 20 ppb Helium-3 in lunar regolith. Between 1,700 to 2,000 Helium-3 mining vehicles would be required, if using University of Wisconsin’s Mark III miner. The required heating power, if mining both day and night, would add up to 39 GW. The resulting power system mass for the lunar operations would be in the order of 60,000 to 200,000 tons. A fleet of three lunar ascent/descent vehicles and 22 continuous-thrust vehicles for orbit transfer would be required. The costs of the mission elements have been spread out over expected lifetimes. The resulting profits from Helium

  14. Thermodynamic properties of hydrogen-helium plasmas

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1971-01-01

    The thermodynamic properties of an atomic hydrogen-helium plasma are calculated and tabulated for temperatures from 10,000 to 100,000 K as a function of the mass fraction ratio of atomic hydrogen. The tabulation is for densities from 10 to the minus 10th power to 10 to the minus 6th power gm/cu cm and for hydrogen mass fraction ratios of 0, 0.333, 0.600, 0.800, and 1.0, which correspond to pure helium, 50 percent hydrogen per unit volume, 75 percent hydrogen per unit volume, 89 percent hydrogen per unit volume, and pure hydrogen plasmas, respectively. From an appended computer program, calculations can be made at other densities and mass fractions. The program output agrees well with previous thermodynamic property calculations for limiting cases of pure hydrogen and pure helium plasmas.

  15. Laser spectroscopic measurement of helium isotope ratios.

    SciTech Connect

    Wang, L.-B.; Mueller, P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Sano, Y.; Sturchio, N.; Univ. of Illinois; Univ. of Tokyo; Univ. of Illinois at Chicago

    2003-06-13

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of {sup 3}He/{sup 4}He = 10{sup -7}--10{sup -5}. The resonant absorption of 1083 nm laser light by the metastable {sup 3}He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of {sup 4}He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3{sigma} detection limit of {sup 3}He in helium is 4 x 10{sup -9}. This demonstration required a 200 {mu}L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  16. Superfluid helium-4 in one dimensional channel

    NASA Astrophysics Data System (ADS)

    Kim, Duk Y.; Banavar, Samhita; Chan, Moses H. W.; Hayes, John; Sazio, Pier

    2013-03-01

    Superfluidity, as superconductivity, cannot exist in a strict one-dimensional system. However, the experiments employing porous media showed that superfluid helium can flow through the pores of nanometer size. Here we report a study of the flow of liquid helium through a single hollow glass fiber of 4 cm in length with an open id of 150 nm between 1.6 and 2.3 K. We found the superfluid transition temperature was suppressed in the hollow cylinder and that there is no flow above the transition. Critical velocity at temperature below the transition temperature was determined. Our results bear some similarity to that found by Savard et. al. studying the flow of helium through a nanohole in a silicon nitrite membrane. Experimental study at Penn State is supported by NSF Grants No. DMR 1103159.

  17. Dose masking feature for BNCT radiotherapy planning

    DOEpatents

    Cook, Jeremy L.; Wessol, Daniel E.; Wheeler, Floyd J.

    2000-01-01

    A system for displaying an accurate model of isodoses to be used in radiotherapy so that appropriate planning can be performed prior to actual treatment on a patient. The nature of the simulation of the radiotherapy planning for BNCT and Fast Neutron Therapy, etc., requires that the doses be computed in the entire volume. The "entire volume" includes the patient and beam geometries as well as the air spaces in between. Isodoses derived from the computed doses will therefore extend into the air regions between the patient and beam geometries and thus depict the unrealistic possibility that radiation deposition occurs in regions containing no physical media. This problem is solved by computing the doses for the entire geometry and then masking the physical and air regions along with the isodose contours superimposed over the patient image at the corresponding plane. The user is thus able to mask out (remove) the contour lines from the unwanted areas of the image by selecting the appropriate contour masking region from the raster image.

  18. Mask-to-wafer alignment system

    DOEpatents

    Sweatt, William C.; Tichenor, Daniel A.; Haney, Steven J.

    2003-11-04

    A modified beam splitter that has a hole pattern that is symmetric in one axis and anti-symmetric in the other can be employed in a mask-to-wafer alignment device. The device is particularly suited for rough alignment using visible light. The modified beam splitter transmits and reflects light from a source of electromagnetic radiation and it includes a substrate that has a first surface facing the source of electromagnetic radiation and second surface that is reflective of said electromagnetic radiation. The substrate defines a hole pattern about a central line of the substrate. In operation, an input beam from a camera is directed toward the modified beam splitter and the light from the camera that passes through the holes illuminates the reticle on the wafer. The light beam from the camera also projects an image of a corresponding reticle pattern that is formed on the mask surface of the that is positioned downstream from the camera. Alignment can be accomplished by detecting the radiation that is reflected from the second surface of the modified beam splitter since the reflected radiation contains both the image of the pattern from the mask and a corresponding pattern on the wafer.

  19. Component separation of oceanic helium

    NASA Astrophysics Data System (ADS)

    Roether, Wolfgang; Well, Roland; Putzka, Alfred; Rüth, Christine

    1998-11-01

    A new procedure to quantify the components of oceanic helium ("terrigenic" 3He and 4He released from the ocean floor and "tritiugenic" 3He from tritium decay) is described. Terrigenic He and nonatmospheric 3He (i.e., terrigenic and tritiugenic combined) are obtained in terms of measured concentrations of the He isotopes and also of neon (Ne) (which improves the separation considerably), assuming terrigenic He to vanish in the mixed layer. For the subsequent separation of terrigenic and tritiugenic 3He, additional information is required and 3He due to natural tritium represents a complication. The procedure is applied to data from a hydrographic section in the South Atlantic (19°S, 1991) and one in the Eastern Mediterranean (1987). The 1σ data precisions and a systematic error accounting for uncertainties in mixed-layer He are approximately 0.3%. Sections of the new representations of oceanic He and 3He and comparisons to the nearest classical quantities (i.e., 3He, He) are presented. In the South Atlantic the 3He distribution reflects the hydrographic structure. East of 20°W the average 3He/4He ratio of terrigenic He below 800 m is 4.5±0.8 times the atmospheric ratio, which implies a substantial contribution of crustal He. In the upper waters, tritiugenic 3He (0.5 tritium units, ±20%) is separated from terrigenic 3He. In the Eastern Mediterranean, tritiugenic 3He is quantified throughout the water column in the presence of substantial levels of terrigenic He; the release rate of terrigenic He from the sea floor is found to be 3.1±1.2 1010 atoms m-2 s-1, similar to the rate for continental crust, with a mantle He contribution of 5±1.2% only. Recommendations for future work are to reduce the mentioned systematic error and the uncertainty margins of the He and Ne solubilities and of 3He due to natural tritium.

  20. Mask design rules (45 nm): time for standardization

    NASA Astrophysics Data System (ADS)

    Mason, Mark; Progler, Christopher J.; Martin, Patrick; Ham, Young-Mog; Dillon, Brian; Pack, Robert; Heins, Mitch; Gookassian, John; Garcia, John; Boksha, Victor

    2005-11-01

    Time-to-mask (ttm) has been growing exponentially in the subwavelength era with the increased application of advanced RET's (Resolution Enhancement Technology). Not only are a greater number of design/mask layers impacted but more-and-more layers also have more severe restrictions on critical dimension uniformity (CDU) despite operating at a very low k1 factors necessitating rigorous but practical tolerancing. Furthermore, designs are also more complex, may be built up from blocks spanning different design styles, and occupy increasingly-large Rayleigh field areas. Given these factors and scales, it's no wonder that the cycle time for verification of a design following RET, is growing however it is doing so exponentially and that this is a critical factor impeding ttm. Until an unambiguously interprable and standard Mask Design Rule (MaskDR) set is created, neither the designer nor the mask supplier can reliably verify manufacturability of the mask for the simple reason that ambiguity and inter-rule conflict are at the source of the problem and that the problem increasingly requires cooperation spanning a large ecosystem of tool, IP, and mask suppliers all needing to essentially speak the same language. Since the 130 nm node, Texas Instruments has enforced a strict set of mask rule checks (MRCs) in their mask data preparation (MDP) flow based on MaskDRs negotiated with their mask suppliers. The purpose of this effort has been to provide an a-priori guarantee that the data shipped to the mask shop can be used to manufacture a mask reliably and with high yield both from a mask standpoint and from the silicon standpoint. As has been reported earlier, mask manufacturing rules are usually determined from assumed or experimentally acquired/validated mask-manufacturing limits. These rules are then applied during RET/MDP data treatment to guide and/or limit pattern correction strategies. With increasing RET and low-k1 lithography challenges, the importance of MRCs