Energy Technology Data Exchange (ETDEWEB)

Four techniques for using LIDAR in Search and Rescue Operations will be discussed. The topic will include laser retroreflection, laser-induced fluorescence in the visible, laser-induced fluorescence during daylight hours, and laser-induced fluorescence in the uv. These techniques use high-repetition rate lasers at a variety of frequencies to induce either fluorescence in dye markers or retroreflection from plastic corner cubes on life preservers and other emergency markers.

International Nuclear Information System (INIS)

Using the Laser-Fluorescence technique, an investigation was made, adopting the standard mix method, on trace uranium concentrations in hot spring water and geothermal water from Lishan region, and in tap water from some major cities in Shanxi province. Totally 40 samples from 27 sites were investigated. Measurement showed that the tap water contains around 10"-"6 g/L of uranium, whose concentrations in both hot spring water and geothermal water are 10"-"5 g/L. Most of samples are at normal radioactive background level, some higher contents were determined in a few samples

Energy Technology Data Exchange (ETDEWEB)

The construction and the development of a UV free electron laser have been started under the cooperation of Nihon U, KEK, PNC, ETL and Tohaku U. The project requires a 100MeV S-band electron linear accelerator to expand the oscillation of FEL using fundamental mode to the UV region. The injection system consists of a thermionic RF-gun with a LaB cathode and an {alpha} magnet for magnetic bunching. We are studying to reduce the back-bombardment electrons to realize the macropulse length of 20{mu}sec. Electron beams, up to the energy of 100MeV, are injected into the optical oscillators. Changing the accelerating energy and/or undulator parameters, this system will cover the range from infrared to ultraviolet for the applications in various fields.

British Library Electronic Table of Contents (United Kingdom)

With an ageing population the demand for cheap, efficient implants is ever increasing. Laser surface treatment offers a unique means of varying biomimetic properties to determine generic parameters to predict cell responses. This paper details how a KrF excimer laser can be employed for both laser-induced patterning and whole area irradiative processing to modulate the wettability characteristics and osteoblast cell response following 24h and 4 day incubation. Through white light interferometry (WLI) it was found that the surface roughness had considerably increased by up to 1.5mm for the laser-induced patterned samples and remained somewhat constant at around 0.1mm for the whole area irradiative processed samples. A sessile drop device determined that the wettability characteristics diffe...

Energy Technology Data Exchange (ETDEWEB)

Micropatterned materials were obtained by a controlled laser ablation of a photoimmobilised homogeneous layer of hyaluronic acid (Hyal) and its sulphated derivative (HyalS). The photoimmobilisation was performed by coating the polysaccharide, adequately functionalised with a photoreactive group, on aminosilanised glass substrate and immobilising it on the surface under UV light. Hyal or HyalS photoimmobilised samples were then subjected to laser ablation with wavelengths in the UV regions in order to drill the pattern. Four different patterns with stripes of 100, 50, 25 and 10 {mu}m were generated. A chemical characterisation by attenuated total reflection/Fourier transform infrared (ATR/FT-IR) and time of flight-secondary ions mass spectrometry (TOF-SIMS) confirmed the success of the laser ablation procedure and the presence of alternating stripes of polysaccharide and native ...

International Nuclear Information System (INIS)

A compact storage ring NIJI-IV free electron laser (FEL) is being developed as a tunable light source which covers a wide wavelength range from the VUV to the IR. To shorten the FEL wavelength in the VUV region, the optical cavity mirror was improved and the original loss of Al_2O_3/SiO_2 multilayer mirror around 195nm was decreased 30% compared with that of the previous one. New optical cavity system equipped with two remotely interchangeable mirrors was installed for the UV/VUV FEL to stabilize the laser and also to extend the tuning range. As for construction of the IR FEL, modification of the beam transport system to make space for installation of the optical cavity was completed. (author)

International Nuclear Information System (INIS)

We have constructed a racetrack-type compact electron storage ring 'NIJI-IV' for UV FEL. The ring has a hexagonal configuration with two 7.25 m-long straight sections, though its circumference is 29.6 m. A 6.3 m optical klystron (OK) for high FEL gain was installed in one of the long straight sections. The experimental setup for FEL lasing was started at the end of April 1992. The setup on the ring with the OK and the cavity mirror alignment have been completed. The FEL lasings using the NIJI-IV were accomplished at 595-589 nm on August 18, 1992 and at 488 nm on September 18, 1992. The final development target is stable FEL lasing in the UV range. (author).

International Nuclear Information System (INIS)

Ultraviolet (UV) upconversion (UC) luminescence in Yb3+/Er3+-codoped yttrium oxide (Y2O3) nanocrystals can be enhanced by orders of magnitude via tridoping further with Li+ ions under diode laser excitation of 970 nm. Sensitized three-photon UC radiations at 390 and 409 nm, corresponding to the 4G11/2?4I15/2 and 4H9/2?4I15/2 of Er3+ ions, respectively, present an enhancement time of about 33 times, which is larger than the 24 times enhancement for the UC green radiation. The UV UC radiation at 320 nm that corresponds to the 2P3/2?4I15/2 of Er3+ ions has also been greatly enhanced. Theoretical calculations interpret that all the observed enhancement times of UV UC radiations arise from the prolonged lifetimes of their intermediate states.

Energy Technology Data Exchange (ETDEWEB)

Nanocrystalline ZnO films were fabricated via a simple method involving the oxidation of Zn films at a remarkably low temperature of 380 C. X-ray diffraction study confirmed that the Zn films were completely oxidized even at the low temperature of 380 C and the ZnO films fabricated were of polycrystalline wurtzite structure. Room temperature optical pumping using a frequency-quintupled Q-switched Nd:YAG laser ({lambda}=213 nm) exhibited that sharp peaks at around 3.12 eV emerged above excitation powers of {proportional_to}7 MW/cm{sup 2}, demonstrating lasing in the ZnO films. These results represent that the process is a simple, promising approach for fabricating ZnO of sufficient optical performance for use as ultraviolet (UV) light emitters and an alternative UV laser source; both are key components in short-wavelength photonic devices. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Results are reported of photoemission studies using laser pulses of 10 ps duration and 4.66 eV photon energy on metal cathodes. These included thin wires, flat surfaces and an yttrium cathode with a grainy surface. The measurements of current density and quantum efficiency under low and high surface fields indicate that field assisted efficiencies exceeding 0.1% and current densities exceeding 10/sup 5/ A/cm/sup 2/ are obtainable. The results are compared to the requirements of switch power applications. 24 refs., 13 figs., 1 tab.

British Library Electronic Table of Contents (United Kingdom)

Acetylacetone is isolated in hydrogen matrices and is investigated by means of infrared spectroscopy, combined with theoretical calculations. The two stable enol and keto tautomers are well characterized. The keto/enol ratio in solid parahydrogen is found to be higher than in classical matrices. While vibrational bands of the enol form are broad, with bandwidths depending on the vibrational mode, those of the keto form are narrow. A KrF laser excitation is used to induce the enol/keto tautomerization in solid parahydrogen. The kinetics of the interconversion is followed, highlighting a non-direct tautomerization process.

Science.gov (United States)

The recent development of matrix-assisted UV laser desorption (LD) mass spectrometry has made possible the ionization and detection of extremely large molecules (with molecular weights exceeding 100,000 Daltons). This technique has generated enormous interest in the biological community for the direct examination of large peptides and oligonucleotides. Although this matrix-assisted ionization method has been developed and used almost exclusively with time-of-flight (TOF) mass spectrometers, research is currently in progress to demonstrate this technique with trapped ion mass spectrometers, such as Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The potential capabilities of FTMS for wide mass range, high resolution measurement, and ion trapping experiments suggest that this instrumental technique should be useful for the detailed structural characterization of large ions generated by the matrix-assisted technique. We have ...

International Nuclear Information System (INIS)

In partnership with the US Navy, high-technology corporations, and research universities, Jefferson Lab is building a superconducting radio-frequency (SRF) accelerator-driven free-electron laser (FEL) and is outfitting an FEL user facility. This first fourth-generation light source - a 1 kW, 3 #mu#m infrared (IR) laser - is the first step in a program to develop high-average-power SRF-based IR and ultraviolet (UV) FELs for multiple manufacturing applications as well as for defense-related applied research and basic scientific research. This initial FEL will be driven by a 42 MeV, 5 m A recirculating SRF linac similar to the much larger SRF linac in Jefferson Lab's 4 GeV, 200 #mu#A Continuous Electron Beam Accelerator Facility (CEBAF). The FEL is expected to demonstrate 75% energy recovery. Its linac will be cooled by the existing CEBAF cryogenic system. At Jefferson Lab, an infrastructure of facilities and people already ...

International Nuclear Information System (INIS)

Thermal conductivity is an important property that governs the behaviour of leaf compost biofilters used in treating gaseous pollutants. Measurements were carried out for the thermal conductivity (K) of 44 samples of leaf compost, covering wide ranges of the volume fractions of water (#xi#_w), solids (#xi#_s) and air (#xi#_a), at 20 deg. C using an unsteady state thermal probe. The results indicated that the compost thermal conductivity increased with an increase in #xi#_w, with a decrease in #xi#_a, and with an increase in the degree of saturation (defined as the volumetric fraction of water in the total void space). The predictions from the Woodside-Messmer quadratic parallel (QP) model for the thermal conductivity of leaf compost were higher than the experimental values. A simple linear relationship was developed between the thermal conductivity and the degree of saturation, ...

Science.gov (United States)

The Boiler and Pressure Vessel Code (BPVC) of the American Society of Mechanical Engineers (ASME) has introduced a risk based approach into Section XI that covers Rules for Inservice Inspection of Nuclear Power Plant Components. The risk based approach requires application of the probabilistic risk assessments (PRA). Because no industry consensus standard existed for PRAs, ASME has developed a standard to evaluate the quality level of an available PRA needed to support a given risk based application. The paper describes the PRA standard, Section XI application of PRAs, and plans for broader applications of PRAs to other ASME nuclear codes and standards. The paper addresses several specific topics of interest to Section XI. Important consideration are special methods (surrogate components) used to overcome the lack of PRA treatments of passive components in PRAs. The approach allows calculations of conditional core ...

International Nuclear Information System (INIS)

The Boiler and Pressure Vessel Code (BPVC) of the American Society of Mechanical Engineers (ASME) has introduced a risk based approach into Section XI that covers Rules for Inservice Inspection of Nuclear Power Plant Components. The risk based approach requires application of the probabilistic risk assessments (PRA). Because no industry consensus standard existed for PRAs, ASME has developed a standard to evaluate the quality level of an available PRA needed to support a given risk based application. The paper describes the PRA standard, Section XI application of PRAs, and plans for broader applications of PRAs to other ASME nuclear codes and standards. The paper addresses several specific topics of interest to Section XI. Important consideration are special methods (surrogate components) used to overcome the lack of PRA treatments of passive components in PRAs. The approach allows calculations of conditional core damage ...

International Nuclear Information System (INIS)

This paper describes the development and a detailed analysis carried out on the luminescence characteristics of Pr"3"+ doped ZrF_4-BaF_2-LaF_3-YF_3-AlF_3-NaF glasses. In the present work our objectives are to elucidate the possible mechanisms that are responsible for NIR to red upconversion process and yellow to blue upconversion emission in terms of energy level schemes from the praseodymium containing fibre optical glass composition. We have studied their different physical and optical properties. Besides our investigation on the upconversion emission of these glasses, normal fluorescence studies have also been undertaken in explaining the mechanisms in demonstrating bright red and blue emissions upon excitations at visible and UV wavelengths. Besides these measurements works, a bright blue colour emission was observed under an UV source (202 nm) and upconverted prominent red emissions were observed with a laser diode (LD ...

International Nuclear Information System (INIS)

In laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), the properties of laser-generated aerosols, such as size and composition, are crucial for matrix-independent quantification. In this study, the aerosol particle morphology and elemental composition generated by two state-of-the-art laser systems (ArF excimer nanosecond-UV laser and Ti:sapphire femtosecond-IR laser) were investigated by electron microscopic techniques. Electrostatic sampling of the aerosols directly onto transmission electron microscopy (TEM) grids allowed us to study the morphology and elemental composition of the aerosols using TEM and TEM-EDX (energy dispersive X-ray spectroscopy) analyses, respectively. The results of the electron microscopic studies were finally compared to the LA-ICPMS signals of the main matrix components. The investigations were carried out for ...

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The present conference on lens design encompasses physical and geometrical optics, diffractive optics, the optimization of optical design, software packages, ray tracing, the use of artificial intelligence, the achromatization of materials, zoom optics, microoptics and GRIN lenses, and IR lens design. Specific issues addressed include diffraction-performance calculations in lens design, the optimization of the optical transfer function, a rank-down method for automatic lens design, applications of quadric surfaces, the correction of aberrations by using HOEs in UV and visible imaging systems, and an all-refractive telescope for intersatellite communications. Also addressed are automation techniques for optics manufacturing, all-reflective phased-array imaging telescopes, the thermal aberration analysis of a Nd:YAG laser, the analysis of illumination systems, athermalized FLIR optics, and the design of array systems using shared symmetry.

International Nuclear Information System (INIS)

Single crystals of semi-organic L-histidine hydrobromide have been grown by slow evaporation technique from a mixture of L-histidine and hydrobromic acid in aqueous solution at ambient temperature. From high-resolution X-ray diffraction analysis, the crystalline perfection of the grown crystal has been studied. Single crystal X-ray diffraction analyses, Nuclear Magnetic Resonance spectral analysis, Thermo-Gravimetry (TG), Differential Thermal Analysis (DTA) and hardness test have been employed to characterize the as-grown crystals. The UV cutoff wavelength of the grown crystal is below 300 nm and has a wide transparency window, which is suitable for second harmonic generation of laser in the blue region. Nonlinear optical characteristics have been studied using Q switched Nd:YAG laser (#lambda#=1064 nm). The second harmonic generation conversion efficiency of the grown crystals confirms their suitability for frequency ...

CERN Document Server

In a recent breakthrough work, Chatterjee proved a long standing conjecture that relates the transversal exponent \\xi and the fluctuation exponent \\chi in first-passage percolation on Z^d. The purpose of this paper is to introduce a new and intuitive idea that replaces Chatterjee's main argument and gives an alternative proof of this relation. Specifically, we show that under the assumption that exponents (as defined by Chatterjee) exist, one has the relation \\chi \\leq 2\\xi -1. One advantage of our argument is that it does not require a `nearly Gamma' assumption on the edge-weight distribution.

International Nuclear Information System (INIS)

Consensus reached in the last few years that fourth generation light source will most likely be a X-ray or a UV coherent source based on single-pass high-gain free electron laser (FEL), such as Self Amplified Spontaneous Emission (SASE), or seeded high-gain harmonic-generation (HGHG) free electron lasers. High-gain (>10"7) required for single-pass FEL puts great constrain on the quality of electron beam, and demands detailed distribution information of electron beam in six-dimension. The typical accelerator system for single-pass FEL consists of a photocathode RF gun injection system, a linac and magnetic bunch compressors, and a long undulator. The major challenges in beam diagnostics for single-pass FEL are to characterize the pico-seconds high-brightness electron beam in six-dimension produced by photocathode RF gun injector, and improve the stability and reliability of the photocathode RF gun injection system. ...

Energy Technology Data Exchange (ETDEWEB)

In the last 30 years high energy physics could write an impressive story of success. Since the introduction of the Standard Model (SM), it has met every experimental test. However the final confirmation has to prove the mechanism of electroweak symmetry breaking, which could not be confirmed yet. The most favored theory, which includes the introduction of a Higgs field, could not be verified experimentally. Furthermore there is clear evidence, that the SM is only a low energy description of nature and its principles, as the SM describes only 4 % of the known matter in the universe. There are two different approaches in accelerator driven high energy physics to clarify the open questions. The Large Hadron Collider (LHC) have a good opportunity to measure some of the missing pieces with its high center of mass energy. The International Linear Collider (ILC) will then measure their parameters with high precision. To guarantee this high precision the detectors have to be able to identify ...

Science.gov (United States)

... of perylene were measured with the Shimadzu UV-2500 UV-VIS spectrophotometer (Kyoto, Japan) to determine their molar extinction coefficients. ...

International Nuclear Information System (INIS)

In this work an analysis of the influence of the choice of the algorithm or planning system, on the calculus of the same treatment plan is introduced. For this purpose specific software has been developed for comparing plans of a series of IMRT cases of prostate and head and neck cancer calculated using the convolution, superposition and fast superposition algorithms implemented in the XiO 4.40 planning system (CMS). It has also been used for the comparison of the same treatment plan for lung pathology calculated in XiO with the mentioned algorithms, and calculated in the Plan 4.1 planning system (Brainlab) using its pencil beam algorithm. Differences in dose among the treatment plans have been quantified using a set of metrics. The recommendation for the dosimetrist of a careful choice of the algorithm has been numerically confirmed. (Author).

Science.gov (United States)

The following topics are discussed: insertion of incorrect bases in DNA; ability of DNA polymerase to copy uv-irradiated DNA; role of enzymes in repair of DNA; effects of uv radiation on molecular weight of DNA; photoreactivation; repair of DNA in Escherichia coli and xp cells following uv radiation; and synchrotron radiation studies on DNA repair. (HLW)

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

UV dwarf star evolution, using central and gap star models emphasizing photoneutrino emission

Science.gov (United States)

... Title : Transverse Pumping with Diode Lasers. Descriptive Note : Technical rept. ... Subject Categories : LASERS AND MASERS. ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Pollen from four temperate-latitude taxa were treated with UV radiation in a portion of the UV-B (280-320 nm) waveband during in vitro germination. Inhibition of germination was noted in this pollen compared to samples treated identically except for the exclusion of the UV-B portion of the spectrum. Levels similar to maximum solar UV-B found in temperate-latitude areas failed to inhibit pollen germination significantly, while levels similar to maximum solar UV-B found in equatorial alpine locations caused partial inhibition of germination in three of the four taxa examined.

International Nuclear Information System (INIS)

A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern #tau#(#OMEGA#_b)#approx =##tau#(#XI#_b"-)>#tau#(#LAMBDA#_b)#approx =##tau#(#XI#_b"0). However, neither the lifetime ratio #tau#(#LAMBDA#_b)/#tau#(B_d) nor the absolute decay rates of the #LAMBDA#_b baryon and B mesons can be explained. One way of solving both difficulties is to allow the presence of linear 1/m_Q corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass m_H__Q rather than the heavy quark mass m_Q. The hierarchy of bottom baryon lifetimes is dramatically modified to #tau#(#LAMBDA#_b)>#tau#(#XI#_b"-)>#tau#(#XI#_b"0)>#tau#(#OMEGA#_b): The longest-lived #OMEGA#_b among bottom ...

CERN Document Server

In this paper we first establish global pointwise time-space estimates for a class of oscillatory integrals. Then, we use them to establish $L^p-L^q$ estimates for a class of higher order wave-type equations of the form $\\partial_{tt}u+P(D_{x})u=0$, where the symbol $P(\\xi)$ is a real non-degenerate elliptic polynomial of ${\\bf R}^n$.

Energy Technology Data Exchange (ETDEWEB)

Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the ...

International Nuclear Information System (INIS)

In order to follow some of the changes induced by ultraviolet-B (UV-B, 280-320 nm) radiation in Phaseolus vulgaris and Brassica napus, experiments were designed to localize sites of changes in leaves and to correlate some of the physiological and biochemical changes with penetration of UV-B radiation. B.napus was exposed to 8.9 kJ m"-"2 day"-"1 biologically effective UV-B radiation (UV-B_B_E). The penetration of UV-B radiation into the leaf was followed using a quartz fibre optic microprobe. Monochromatic radiation at 310 nm was decreased by ca 50 and 34% in the adaxial and abaxial epidermis, respectively, in plants not exposed to UV-B, whereas the radiation was decreased by ca 70 and 42%, respectively, in the same region in UV-treated plants. Polychromatic radiation showed a wavelength dependent change mainly for the collimated radiation. ...

International Nuclear Information System (INIS)

The effects of eight chemicals on the inactivation rate of ultraviolet radiation on the colony building capabilities of two strains of Saccharomyces cervisae - a wild type strain and a mutant deficient in excision repair - were studied. The insecticide methoxychlor, the herbicide 2,4-dichlorophenoxyacetic acid, the fungicide pentachlorophenol and its metabolite tetrachlorohydroquinone, as well as the chemicals acrylonitrile and 2,3-dichloro-1-propene have no significant impact on the effects of UV radiation in Saccharomyces cerevisae. Depending on the concentration, trichloroethylene increases the sensitivity to UV radiation. The herbicide paraquat provides efficient protection against UV radiation at concentrations where a toxic effect cannot be observed even without UV. The results were rather similar for both strains. (orig.).

UK PubMed Central (United Kingdom)

UV, first, second and third derivative spectrophotometric methods have been developed for the determination of ezetimibe in pharmaceutical formulation. The solutions of standard and sample were prepared...Full Text Available

Science.gov (United States)

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KoreaScience (Korea)

Full Text Available

Science.gov (United States)

Potential strategic missions for laser weapons, particularly those involving space-based lasers, are discussed. The functions of space-based lasers and the history of their conceptual development are summarized, and the problems of implementing such systems, including the building of a suitable laser and power source, and resolving the problem of optics, are discussed. Ongoing development programs are described, and the contrasting views of the necessity and usefulness of strategic laser systems are set forth.

Science.gov (United States)

... Law Parameter 28 Summary 28 6. CIRCULAR VS ANNULAR LASER BEAMS 29 7. HIGH-ENERGY LASER BEAM PROPAGATION THROUGH A ...

Energy Technology Data Exchange (ETDEWEB)

The atmospheric chemical behaviour of 1,1,1,2-tetrafluoroethane (CF{sub 3}CFH{sub 2}, HFC-134a) with respect to its rate and mechanism of degradation in the troposphere has been investigated. The rate coefficient for the reaction of (1a) CF{sub 3}CFH{sub 2}+OH{yields}CF{sub 3}CFH+H{sub 2}O has been determined in direct time-resolved experiments using laser-pulse initiation and laser long-path absorption. A value of k{sub 1a}=(4.6{+-}0.5).10{sup -15} cm{sup 3}/s at T=295 K has been found. The ratio of the rate coefficients for the reactions of the CF{sub 3}CFHO-radical with O{sub 2}, (4) CF{sub 3}CFHO+O{sub 2}{yields}CF{sub 3}CFO+HO{sub 2}, and C-C bond fission, (5) CF{sub 3}CFHO+M{yields}CFHO+CF{sub 3}+M, for T=295 K and p{sub total}=50 mbar (O{sub 2}) has been obtained to be k{sub 4}/(k{sub 5}[M])=1.5.10{sup -19} cm{sup 3}, with the individual values being k{sub 4}=2.7.10{sup -15} cm{sup 3}/s and k{sub 5}[M]=1.8.10{sup 4} s{sup -1}. The ...

CERN Document Server

Given a Gibbs point process $\\P^{\\Psi}$ on $\\R^d$ having a weak enough potential $\\Psi$, we consider the random measures $\\mu_\\la := \\sum_{x \\in \\P^{\\Psi} \\cap Q_\\la} \\xi(x, \\P^{\\Psi} \\cap Q_\\la) \\delta_{x/\\la^{1/d}}$, where $Q_{\\la} := [-\\la^{1/d}/2,\\la^{1/d}/2]^d$ is the volume $\\la$ cube and where $\\xi(\\cdot,\\cdot)$ is a translation invariant stabilizing functional. Subject to $\\Psi$ satisfying a localization property and translation invariance, we establish weak laws of large numbers for $\\la^{-1} \\mu_\\la(f)$, $f$ a bounded test function on $\\R^d$, and weak convergence of $\\la^{-1/2} \\mu_\\la(f),$ suitably centered, to a Gaussian field acting on bounded test functions. The result yields limit laws for geometric functionals on Gibbs point processes including the Strauss and area interaction point processes as well as more general point processes defined by the Widom-Rowlinson and hard-core model. We provide ...

British Library Electronic Table of Contents (United Kingdom)

Purpose Ultraviolet-B (UV-B) radiation can cause phototoxic macular injuries in young people who have been sunbathing but not sungazing and in welders. Welders have a reportedly increased risk of uveal melanoma. We analyze phakic and pseudophakic risks for solar and welding arc UV-B exposure. Design Optical radiation measurement, analysis, and perspective. Methods Spectral transmittances were measured for UV-transmitting, UV-blocking, and blue-blocking intraocular lenses (IOLs). The photoprotective performances of crystalline and intraocular lenses were analyzed using relevant epidemiologic and laboratory data and action spectra for acute retinal phototoxicity and melanoma photocarcinogenesis. Results Crystalline lens UV-B retinal protection is deficient in children and young adults, incre...

International Nuclear Information System (INIS)

The optical absorption of the Tm"3"+ ion in the gadolinium oxychloride (GdOCl) matrix in the UV, visible, and NIR range was studied at temperatures between 9 and 300 K. The visible luminescence of GdOCl:Tm"3"+ under Ar"+ ion laser and mercury lamp excitation was recorded at 9, 77, and 300 K, too. The crystal field (CF) splitting of the "3H_4_-_6, "3F_2_-_4, "1G_4, "1D_2, and "1I_6 levels of the Tm"3"+ ion deduced from the spectra was analysed according to the C_4_v point symmetry of the RE"3"+ site. The resulting energy level scheme, consisting of 39 levels (i.e. 55 Stark components) out of the total of 70 (91) for the whole 4f"1"2 configuration, was simulated with the aid of a phenomenological theory taking simultaneously into account both the free-ion and CF effects. The model included 13 adjustable parameters describing the electrostatic (the Racah parameters E_0_-_3) and the configuration interaction (the Trees parameters #alpha#, #beta#, ...

Energy Technology Data Exchange (ETDEWEB)

The rate coefficient for the title reaction has been determined using mixtures of nitric acid (HNO{sub 3}), carbon monoxide (CO), and argon in incident shock wave experiments. Upon shock heating, the nitric acid rapidly decomposes into OH and NO{sub 2}. The OH subsequently reacts predominantly via the title reaction. Quantitative OH time histories were obtained by continuous-wave (cw) narrow-linewidth UV laser absorption of the R{sub 1}(5) line of the A{sup 2}{Sigma}{sup +} {l_arrow} X{sup 2}{Pi}{sub i} (0,0) transition at 32,606.56 cm{sup {minus}1} (vacuum). In some experiments, helium was added to the reactant mixture to examine CO vibrational excitation effects on the rate coefficient determination. It was found that the rate of excited CO (v = 1) with OH is less than the rate of ground-state CO (v = 0) with OH, which is in agreement with previous state-dependent work. The experiments were conducted over the temperature range 1,090--2,370 K ...

Science.gov (United States)

PMID:17508608

ScienceCinema

...spontaneous radiation ...

Energy Technology Data Exchange (ETDEWEB)

Short communication.

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

Depletion of stratospheric ozone increases irradiance of terrestrial ultraviolet (UV) radiation at short wavelengths, which may be harmful to the human health. To understand quantitatively the risks caused by increasing UV radiation to the Finnish population, the actual UV exposure of the population has to be assessed. It was shown that the snow reflection increases the UV exposure to the face and eyes particularly in the northern Finland. In 1993 exceptionally low ozone levels persisted up to the end of May, which resulted in a theoretical increase in the annual UV dose ranging from 8 % to 13 % in Finland. The maximal increase in the measured erythemally effective dose rate was 34 % on 23 April, when compared with the theoretical normal value. During this study exposure models have been developed. The models have been combined them with Green`s radiation transfer model to estimate ...

CERN Document Server

We use UV/optical and X-ray observations of 272 radio-quiet Type 1 AGNs and quasars to investigate the CIV Baldwin Effect (BEff). The UV/optical spectra are drawn from the Hubble Space Telescope, International Ultraviolet Explorer and Sloan Digital Sky Survey archives. The X-ray spectra are from the Chandra and XMM-Newton archives. We apply correlation and partial-correlation analyses to the equivalent widths, continuum monochromatic luminosities, and alpha_ox, which characterizes the relative X-ray to UV brightness. The equivalent width of the CIV 1549 emission line is correlated with both alpha_ox and luminosity. We find that by regressing l_UV with EW(CIV) and alpha_ox, we can obtain tighter correlations than by regressing l_UV with only EW(CIV). Both correlation and regression analyses imply that l_UV is not the only factor controlling the changes of ...

Science.gov (United States)

... The addition of 0.5 pphr of fine thermal carbon black to the polymers gave good resistance to 500 hours of ultraviolet (UV) xposure in a Weather ...

Science.gov (United States)

A sulfonated fluoroalkyl graft polymer (FGP) membrane was prepared as a polymer electrolyte. First, the FGP membrane was grafted with styrene under UV irradiation. The grafted FGP was then sulfonated to functionalize it for proton conductivity. The grafting degree of the membrane increased with increasing grafting time during UV irradiation. The proton conductivity of the membrane increased with increasing grafting degree. The swelling ratio was independent of the grafting time, however, the water uptake increased with increasing grafting degree. Based on these results, it was found that the UV-initiated styrene grafting occurred along the membrane thickness direction. Moreover, the membrane was embedded within the glass fibers of the composite. This composite electrolytic membrane had 1.15 times the proton conductivity of a Nafion 117 membrane.

Wastenet

added to provide resistance to UV degradation, and vulcanization control. ...Sulphur is used to vulcanize the rubber ...additives and solvents age resistors, processing aids, accelerators, vulcanizing agents, softeners and fillers

Energy Technology Data Exchange (ETDEWEB)

The authors have measured the relaxation time of hot electrons in short pulse laser-solid interactions using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. Employing laser intensities of 10{sup 17}, 10{sup 18}, and 10{sup 19} W/cm{sup 2}, they find increased laser coupling to hot electrons as the laser intensity becomes relativistic and thermalization of hot electrons at timescales on the order of 10 ps at all laser intensities. They propose a simple model based on collisional coupling and plasma expansion to describe the rapid relaxation of hot electrons. The agreement between the resulting K{sub {alpha}} time-history from this model with the experiments is best at highest laser intensity and less satisfactory at the two lower laser intensities.

Science.gov (United States)

It is well known that laser oscillation is initiated by spontaneous radiation ''noise.'' Evidence for this is often based on the complete theory of laser oscillation, including the quantization of the electromagnetic field. In this article, the buildup of laser oscillation from quantum noise is demonstrated using the most elementary classical equation describing the amplification of laser intensity.

Energy Technology Data Exchange (ETDEWEB)

The optical absorption of the Tm{sup 3+} ion in the gadolinium oxychloride (GdOCl) matrix in the UV, visible, and NIR range was studied at temperatures between 9 and 300 K. The visible luminescence of GdOCl:Tm{sup 3+} under Ar{sup +} ion laser and mercury lamp excitation was recorded at 9, 77, and 300 K, too. The crystal field (CF) splitting of the {sup 3}H{sub 4-6}, {sup 3}F{sub 2-4}, {sup 1}G{sub 4}, {sup 1}D{sub 2}, and {sup 1}I{sub 6} levels of the Tm{sup 3+} ion deduced from the spectra was analysed according to the C{sub 4v} point symmetry of the RE{sup 3+} site. The resulting energy level scheme, consisting of 39 levels (i.e. 55 Stark components) out of the total of 70 (91) for the whole 4f{sup 12} configuration, was simulated with the aid of a phenomenological theory taking simultaneously into account both the free-ion and CF effects. The model included 13 adjustable parameters describing the electrostatic (the Racah parameters E{sub ...

CERN Document Server

Numerical simulations are used to test the kinetic theory constitutive relations of inertial granular shear flow. These predictions are shown to be accurate in the dilute regime, where only binary collisions are relevant, but underestimate the measured value in the dense regime, where force networks of size $\\xi$ are present. The discrepancy in the dense regime is due to non-collisional forces that we measure directly in our simulations and arise from elastic deformations of the force networks. We model the non-collisional stress by summing over all paths that elastic waves travel through force networks. This results in an analytical theory that successfully predicts the stress tensor over the entire inertial regime without any adjustable parameters.

Energy Technology Data Exchange (ETDEWEB)

Laser assisted solar cell metallization processing which is a one step process is examined. The potential advantages of laser disposition techniques for photovoltaic systems are: a high resolution, no photolithography, clean and contamination free, in-situ sintering, and low contact resistance.

International Nuclear Information System (INIS)

Surface-sensitive UV photoelectron yield spectroscopy was employed to study electron acceptor levels at surfaces of chalcopyrite structure Cu-In-Se thin films. Surface Fermi level pinning was observed for Cu-rich films. Shallow acceptor levels ascribable to defects Cu_I_n and V_C_u were observed for near-stoichiometric and In-rich films respectively. (orig.).

UK PubMed Central (United Kingdom)

The H-D exchange reaction has been measured with the D2-H2O system, for Rhodobacter capsulatus JP91, which lacks the hupSL-encoded hydrogenase, and R. capsulatus BSE16, which lacks the HupUV proteins....Full Text Available

International Nuclear Information System (INIS)

Oxide superconducting thin films were irradiated with X-rays and ultra-violet (UV) light, and induced radiation effects on electrical and chemical properties were examined by transport measurement, X-ray diffraction analysis (XRD), diamagnetization measurement and X-ray photoemission spectroscopy (XPS). After irradiation for ErBa_2Cu_3O_x films with X-rays emitted from a Rh tube for 100 hours, superconductivity was remarkably damaged, destroying the zero-resistance state. The UV-light irradiation for Bi_2Sr_2CaCu_2O_x films was performed in He gas of about 500 Pa with a low pressure mercury lamp. The superconductivity was gradually degraded with the UV irradiation time up to 70 minutes. In both cases, adequate oxygen-annealing treatments restored superconductivity. The X-ray photoemission spectra showed that the mean Cu valence of the films was decreased approximately from +2 to +1 by the irradiation. From these results we ...

International Nuclear Information System (INIS)

The University of Georgia, in collaboration with GE Global Research, has investigated the relevant quenching mechanism of phosphor coatings used in white light devices based on UV LEDs. The final goal of the project was the design and fabrication of a high-efficacy white light UV-LED device through improved geometry and optimized phosphor coatings. At the end of the research period, which was extended to seamlessly carry over the research to a follow-up program, we have demonstrated a two-fold improvement in the conversion efficiency of a white light LED device, where the increase efficacy is due to both improved phosphor quantum efficiency and lamp geometry. Working prototypes have been displayed at DOE sponsored meetings and during the final presentation at the DOE Headquarters in Washington, DC. During the first phase of the project, a fundamental understanding of quenching processes in UV-LEDs was obtained, and the ...

International Nuclear Information System (INIS)

2009 p. 200-201 Ukraine Glushkov, AV Odesa State Environmental

KoreaScience (Korea)

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Science.gov (United States)

... iFfficiency-en- enhanced spontaneous radiation at the free-electron- ... as enhanced spontaneous radiation at the free-electron-laser wavelength. ...

Energy Technology Data Exchange (ETDEWEB)

This report details the laser surface mapping activity as described in technical tasks and QA plan 22751-TTQAP-LM.

Energy Technology Data Exchange (ETDEWEB)

A continuous gas laser may be operated reliably with an increased pressure level and current level without significant cathode sputtering. This increases the service life and the specific power of the laser. The design eliminates the formation of arcs in operational conditions, which also has a positive influence on laser operation. The proposed laser is used successfully in modern interferometry, in geodesy and in materials analysis. The laser design is characterized by the presence of separation rings inside the coaxial cathode. The separation rings are fastened to the anode. The anode is a perforated tube that is connected to two final protective rings. Electrodes from the housing pass through the final rings. In order to increase laser power, two or more lasers of such design are used and are positioned on the same axis in a single ...

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are being investigated, developed, and characterized. A literature search was carried out on the various state-of-the-art laser-assisted techniques for metal deposition, including laser chemical vapor deposition and laser photolysis of organometallics, as well as laser-enhanced electroplating. The results of the literature survey are briefly summarized. Experiments were carried out on laser-enhanced electroplating. Deposition of metals by laser-assisted pyrolysis of a variety of metallo-organic inks and metal-bearing polymer solutions spun as films onto silicon wafers was carried out. A detailed study of the various models of localized surface temperature rise in silicon due to laser heating has been carried out. Progress is ...

International Nuclear Information System (INIS)

Purpose: The aim of this study was to assess interinstitutional variations in planning for stereotactic body radiation therapy (SBRT) for lung cancer before the start of the Japan Clinical Oncology Group (JCOG) 0403 trial. Methods and Materials: Eleven institutions created virtual plans for four cases of solitary lung cancer. The created plans should satisfy the target definitions and the dose constraints for the JCOG 0403 protocol. Results: FOCUS/XiO (CMS) was used in six institutions, Eclipse (Varian) in 3, Cadplan (Varian) in one, and Pinnacle3 (Philips/ADAC) in one. Dose calculation algorithms of Clarkson with effective path length correction and superposition were used in FOCUS/XiO; pencil beam convolution with Batho power law correction was used in Eclipse and Cadplan; and collapsed cone convolution superposition was used in Pinnacle3. For the target volumes, the overall coefficient of variation was 16.6%, and the interinstitutional ...

Science.gov (United States)

PMID:15675751

Science.gov (United States)

Steady-state and transient behavior of the longitudinally pumped semiconductor laser is theoretically investigated by using a rate-equation model with distributed gain and photon density. Conditions necessary for bistable operation are derived. Dependencies of such major switching characteristics as turn-on and turn-off powers, delay, and rise times on laser parameters are examined. Influences of spontaneous radiation, impurities, and Auger recombination are studied. The results offer an explanation for the observed nonlinear behavior of face-pumped lasers.

CERN Document Server

We provide an analytic study of the dynamics of semiconductor lasers with injection (pump) of spin-polarized electrons, previously considered in the steady-state regime. Using complementary approaches of quasi-static and small signal analyses, we elucidate how the spin modulation in semiconductor lasers can improve performance, as compared to the conventional (spin-unpolarized) counterparts. We reveal that the spin-polarized injection can lead to an enhanced bandwidth and desirable switching properties of spin-lasers.

International Nuclear Information System (INIS)

... radiation parity photonuclear reactions polarized beams resonance

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

A 1000-watt CO/sub 2/ laser has been demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics have been laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass-reinforced laminates, Kevlar/epoxy composites, fiberglass-reinforced phenolics, nylon/epoxy laminates, ceramics, and disposable tooling made from acrylic.

Energy Technology Data Exchange (ETDEWEB)

In this paper the feasibility of phase locking a FIR laser by injection of a highly stable synthesized signal is examined. The theory of injection locking is revised in order to take into account the characteristic features of FIR lasers and turns out to be in satisfactory agreement with the experimental data reported. From the results obtained, it is inferred that the state of the art of submillimetric multipliers makes it possible to stabilize FIR laser emissions up to about 1 THz.

Energy Technology Data Exchange (ETDEWEB)

None provided

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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British Library Electronic Table of Contents (United Kingdom)

In recent years, increased attention has been focused on the use of lasers in different fabrication steps of solar cells, in particular laser doping to form emitter and/or selective emitter. In this method the laser energy is used to melt silicon, allowing the diffusion of dopant atoms to occur in the liquid phase. The main advantage of this method is the localised nature of the laser beam, which melts and diffuses a limited area without heating the bulk, therefore reducing the possible degradation associated with high temperature processes. At the University of New South Wales a novel laser doping method was developed, which combines the formation of the selective emitter with a self-aligned metallisation pattern. Despite achieving high efficiencies, concerns arose regarding the adhesion ...

British Library Electronic Table of Contents (United Kingdom)

We have measured time-resolved laser-induced incandescence of flame-generated soot under high-vacuum conditions (4.1?10?6 mbar) at an excitation wavelength of 532 nm with laser fluences spanning 0.06?0.5 J/cm2. We generated soot in an ethylene/air diffusion flame, introduced it into the vacuum system with an aerodynamic lens, heated it using a pulsed laser with a spatially homogeneous and temporally smooth laser profile, and recorded LII temporal profiles at 685 nm. At low laser fluences LII signal decay rates are slow, and LII signals persist beyond the residence time of the soot particles in the detection region. At these fluences, the temporal maximum of the LII signal increases nearly linearly with increasing laser fluence until reaching a plateau at ?0.18?J/cm2. At higher fluences, th...

British Library Electronic Table of Contents (United Kingdom)

With conventional heating process, ultraviolet (UV) illumination, and microwave irradiation, we have successfully synthesized UV curable encapsulating adhesives with excellent gas barrier capabilities, good adhesive strength, moderate hardness, and high refractive indices. The experimental results manifest that the physical properties of lab-made encapsulating adhesives are highly dependent on their chemical structures and synthetic procedure. We also discover that the encapsulating adhesive prepared by microwave irradiation (i.e. encapsulating adhesive VI-MW) exhibits better adhesive strength and higher gas resistance than those prepared by conventional heating process and UV illumination. Furthermore, encapsulating adhesive VI-MW has also been applied for the package of organic light emi...

British Library Electronic Table of Contents (United Kingdom)

The mutual influence between the PP/PS polymer blend components during UV photodegradation was studied. Polypropylene (PP) and polystyrene (PS) have different photodegradation mechanisms, due to the larger UV absorption of polystyrene and formation of more stable tertiary carbon radicals. To compare the stabilities the kinetics of carbonyl formation was measured in different blend compositions. The results show that polystyrene presented a faster carbonyl formation than polypropylene, while the blends display faster kinetics than the isolated components. The kinetics of carbonyl formation of the blends was a function of polypropylene content. This result is unexpected if one considers the behaviour of each component alone. The kinetics and mechanism of UV degradation can be only explained ...

British Library Electronic Table of Contents (United Kingdom)

A combined numerical and theoretical study is conducted herein on the penetration of semi-infinite targets by jacketed rods with different r"j"0/r"c"0 ratios where r"j"0 and r"c"0 are the radii of the jacket and the core, respectively. The numerical results show that for smaller r"j"0/r"c"0 ratios the u-v relationship changes only a little compared to that of unitary long rod penetrator of the same core material, hence, the u-v relationship of unitary (homogeneous) long rod penetration is also applicable for jacketed rod penetration. Model for cratering in semi-infinite targets by jacketed rods is then suggested by using the laws of conversation of mass, momentum and energy, together with the u-v relationship of unitary (homogeneous) long rod penetration and an analytical model for predict...

Energy Technology Data Exchange (ETDEWEB)

This paper reports on the results of experiments into efficient higher-order anti-Stokes Raman conversion of tunable short-pulse XeCl laser radiation. The maximum output energy of the pumping laser, in which the radiation of a frequency-doubled dye laser is amplified by two XeCl laser amplifiers, is 55 mJ with a pulse duration of 1 ns FWHM. Using hydrogen gas as a Raman medium, a series of anti-Stokes lines up to the 12th order (121.5 nm) is generated in the vacuum ultraviolet (VUV) region. 16 references.

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are investigated, developed, and characterized. The tasks comprising these investigations are outlined. A new batch of solar cells was processed using the laser decomposition of spun-on silver neodecanoate to metallize cells. Decomposition of silver neodecanoate was carried out at different laser powers on different cells on a given wafer to determine whether this would have any effect on cell performance. Solar cells which were written with laser powers of 5 to 8 watts, gave excellent results with cell efficiencies in the range of 14 to 16%.

International Nuclear Information System (INIS)

Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar(II) 3d4F7/2 to 4p4D05/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the recovery of the background fluorescence after the laser was turned off, the ion diffusion coefficient was deduced and compared with the result inferred from the experiments of ion acoustic wave (IAW) damping.

International Nuclear Information System (INIS)

In a free electron laser (FEL), the electron bunch energy profile at the undulator entrance can have temporal structures. In this paper, we derive analytical expressions for the FEL in the undulator, in the case of the electron bunch having both energy chirp and energy curvature. The FEL properties are studied analytically by convoluting a Gaussian seed laser with the FEL Green's function obtained by solving the coupled Vlasov-Maxwell equations. In particular, for different ratios of the temporal duration of the seed laser and that of the Green's function, interesting behavior is revealed.

International Nuclear Information System (INIS)

I report on some recent work done in collaboration with E. de Rafael on the connection between ultraviolet renormalons in QCD and Nambu-Jona-Lasinio-like Lagrangians as its effective description at low energies. (orig.)

Science.gov (United States)

Apr 20, 2009 ... "YY" is the 2-digit filter identifier .... In our example you can see a point- like optical/UV source in each of the filters at the ... The "sigma" paramter gives the detection threshold in terms of Gaussian sigma. ...

CERN Document Server

We study the expected properties of starbursts in order to provide the point of reference for interpretation of high-z galaxy surveys and of very metal-poor galaxies. We concentrate mainly on the UV characteristics such as the ionizing spectra, the UV continuum, the Ly alpha and HeII 1640 A line and two-photon continuum emission. We use evolutionary synthesis models covering metallicities from Pop III to solar and a wide range of IMFs. We also combine the synthetic SEDs with the CLOUDY photoionization code for more accurate predictions of nebular emission, and to study possible departures from case B assumed in the synthesis models. The ionizing fluxes, UV continuum properties, and predicted Ly alpha and HeII 1640 A line strengths are presented for synthesis models covering a wider range of parameter space than our earlier calculations. Strong departures from case B predictions are obtained for Ly alpha and two-photon ...

UK PubMed Central (United Kingdom)

Inhibition of photosynthesis by ultraviolet-A radiation (UV-A, 315-380 nanometers) was examined in three marine angiosperms: Halophila engelmannii Aschers, Halodule wrightii...Full Text Available

UK PubMed Central (United Kingdom)

DNA damage is a threat to genomic integrity in all living organisms. Plants and green algae are particularly susceptible to DNA damage especially that caused by UV light, due to their light dependency...Full Text Available

UK PubMed Central (United Kingdom)

Seven mutants of Escherichia coli were isolated that are sensitive to methyl methane sulfonate but not to UV light. They exhibited decreased host cell reactivation capacity for methyl methane sulfonate-treated...Full Text Available

Science.gov (United States)

The electronic transitions and photodissociation of the bromine molecule were studied in the visible-near UV continuum using dynamic simulation. The molar extinction coefficients in this study were obtained in numerical calculations. The quantum yields of the spin-orbit Br*(2 P 1/2) product at different photon frequencies were determined. Time-dependent density functional theory was used to analyze the highest five occupied and lowest five unoccupied Br2 orbitals. The transition to the 1? u state was found to be most probable in the visible-near UV absorption range.

Energy Technology Data Exchange (ETDEWEB)

SO/sub 2/ adsorption onto faujasite-type zeolites (Na-X, Na-Y) was investigated by combined UV and IR spectroscopy. Formation of chemisorbed HSO/sub 3//sup -/ species, indicated by a UV band around 215 nm and a low-frequency IR band at 1240 cm/sup -1/, was shown to depend significantly upon the presence of water. Differences in the behavior of Na-X and Na-Y were discussed in terms of different site populations.

Energy Technology Data Exchange (ETDEWEB)

The aim of this contract is to investigate, develop, and characterize laser-assisted processing techniques utilized to produce the fine-line, thin-metal grid structures that are required to fabricate high-efficiency solar cells. During the first quarter of this contract, a comprehensive literature search was carried out in the various state-of-the-art laser-assisted techniques for metal deposition, including laser chemical vapor deposition and laser photolysis of organometallics, as well as laser-enhanced electroplating. A compact system for the experiments involving laser-assisted photolysis of gas-phase compounds was designed and constructed. The work performed in the second quarter is detailed in this report. Metal deposition experiments have been carried out utilizing laser-assisted pyrolysis of a variety of metal-bearing polymer films ...

International Nuclear Information System (INIS)

The photon rupture method, by which oxide film and metal are removed by focused pulsed Nd-YAG laser beam irradiation, was applied to form artificial micro-pits in Zn-5 mass% Al alloy-coated steel. The zinc alloy-coated layer was removed by pulsed laser irradiation treatment for about one second in a neutral buffer solution with NaCl. The rest potential transient with the laser treatment was measured. In the early stage of the laser treatment the rest potential of zinc alloy-coated steel changed to the negative direction immediately after every irradiation of a laser pulse and then returned to the previous value. However, after the steel substrate was exposed to the solution, the rest potential moved to the positive direction immediately after every irradiation of a laser pulse and then returned to the previous value. The amplitude and duration of the potential ...

International Nuclear Information System (INIS)

The role of the HCR system in the repair of prelethal lesions induced by UV light, #gamma# radiation and alkylating agents was studied in the Bacillus subtilis SPP1 phage, its heat sensitive mutants (N3, N73 nad ts_1) and corresponding infectious DNA. The survival of phages and their transfecting DNA after treatment with UV light is substantially higher in hcr"+ cells than in hcr cells, the differences being more striking in intact phages than in their transfecting DNA's. Repair inhibitors reduce survival in hcr"+ cells: caffeine lowers the survival of UV-irradiated phage SPP1 in exponentially growing hcr"+ cells but has no effect on its survival in competent hcr"+ cells; acriflavin and ethidium bromide decrease the survival of the UV-irradiated SPP1 phage in both exponentially growing and competent hcr"+ cells to the level of survival observed in hcr cells; moreover, ethidium bromide lowers the number ...

Energy Technology Data Exchange (ETDEWEB)

A flowing carbon dioxide laser was operated at low pressures up to 4 torr. Excitation of the laser was provided using various combinations of direct current (DC), pulsed microwave, and continuous wave (CW) microwave excitation. The microwaves were in the 2.45 GHz band and were coupled into the gas using a slow-wave interdigital transmission line. Laser output of 25 milliwatts (mw) was achieved using a DC discharge only. A combination of a DC discharge and pulsed microwaves doubled the output and resulted in some modulation. Changing the laser gas mixture and pulsed microwave field characteristics allowed some flexibility in the modulation. Lasing was not achieved with excitation from the CW microwaves alone due to the formation of localized discharges. Using pulsed microwaves to sustain the discharge and CW microwaves to pump the laser, a quasi-CW output of 55 mw was achieved.

Energy Technology Data Exchange (ETDEWEB)

A design of a compact free-electron laser (FEL), generating ultra-fast, high-peak flux, XUV pulses is presented. The FEL is driven by ahigh-current, 0.5 GeV electron beam from the Lawrence Berkeley National Laboratory (LBNL) laser-plasma accelerator, whose active acceleration length is only a few centimeters. The proposed ultra-fast source (~;;10 fs) would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science. Owing to the high current (>10 kA) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially greater than 10^13 photons/pulse. Devices based both on self-amplified spontaneous emission and high-harmonic generated input seeds, to reduce undulator length and fluctuations, are considered.

Energy Technology Data Exchange (ETDEWEB)

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent ''pulses'' that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus or for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device such as generates sound waves containing a group of frequencies which result in spaced pulses. The spreading of a laser beam at which emanates from the first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam.

International Nuclear Information System (INIS)

One of the main challenges for a high energy #gamma##gamma# collider is the high repetition rate required for the laser-electron-beam collisions to convert into high energy gamma beams. State-of-the-art, high power lasers have a much lower repetition rate than that of the electron pulses. It is therefore highly desirable that the same laser pulse can be reused. As an example, for NLC where beams collide at 120 Hz, within each collision cycle there are 90 electron bunches separated by 1.4 ns between successive bunches. We show, by invoking a recently invented laser optical box, that the laser pulses can be reused for the entire train of bunches within each collision cycle. ((orig.)).

Energy Technology Data Exchange (ETDEWEB)

The fourth in a series of international Leak-Before-Break (LBB) Seminars supported in part by the US Nuclear Regulatory Commission was held at the National Central Library in Taipei, Taiwan on May 11 and 12, 1989. The seminar updated the international polices and supporting research on LBB. Attendees included representatives from regulatory agencies, electric utilities, nuclear power plant fabricators, research organizations, and academic institutions. Regulatory policy was the subject of presentations by Mr. G. Arlotto (US NRC, USA) Dr. B. Jarman (AECB, Canada), Dr.P. Milella (ENEA-DISP, Italy), Dr. C. Faidy (EDF/Septen, France ), and Dr. K. Takumi (NUPEC, Japan). A paper by Mr. K. Wichman and Mr. A. Lee of the US NRC Office of Nuclear Reactor Regulation is included as background material to these proceedings; it discusses the history and status of LBB applications in US nuclear power plants. In addition, several papers on the supporting research programs described regulatory policy ...

Energy Technology Data Exchange (ETDEWEB)

This paper reports on superconductor-semiconductor-superconductor (S-N-S) weak-link junctions with the normal layer of Si or InSb thin films were prepared by using focused ion beam (FIB), and electrical properties were measured. Whereas InSb thin films on single crystals did not have an intrinsic mobility, S-N-S junction with InSb shows the characteristics of Josephson S-N-S junction. A 200nm-thick film of InSb deposited on MgO had a mobility of 83 cm{sup 2}.V {center dot} s and a carrier density of 6.5 {times} 10{sup 17} cm{sup {minus}3} at 4.2K. The coherence length {xi}{sub n} was computed to be 17 nm from these experimental data, and we obtained critical superconducting current Ic of 100 {mu} A for the S-N-S junction which had a line width of 10{mu} m and a channel length of 20 nm.

UK PubMed Central (United Kingdom)

We demonstrate rapid fabrication of submicrometer-diameter pores in borosilicate glass using femtosecond laser machining and subsequent wet-etch techniques. This approach allows direct and repeatable...Full Text Available

UK PubMed Central (United Kingdom)

The refractive error in 15 eyes with threshold retinopathy of prematurity treated with diode laser photocoagulation was compared with 25 eyes with the same disease severity treated by cryotherapy. Myopia...Full Text Available

UK PubMed Central (United Kingdom)

Background and ObjectivesDisruption of the vocal fold extracellular matrix (ECM) can induce a profound and refractory dysphonia. Pulsed dye laser (PDL) irradiation...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

We summarize some initial results in our investigation of the nuclear physics issues of gamma-ray lasers. We describe what is known thus far from existing experimental data and illustrate how theoretical models may be employed for systematic searches of candidate nuclei.

International Nuclear Information System (INIS)

The possibility to compress and to split laser pulses at their nonlinear optical transmission through semiconductor films was investigated

UK PubMed Central (United Kingdom)

The imaging analytical capabilities of laser scanning cytometer (LSC) have been used to assess morphological features considered to be typical of the senescent phenotype. The characteristic “flattening”...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are being investigated, developed, and characterized. The tasks comprising these investigations are outlined.

International Nuclear Information System (INIS)

Physics and technology of free electron laser (FEL) are reviewed. Mechanisms of stimulated emission in FEL and its present status and future prospects are presented. Electromagnetic wiggler, two stage FEL and so on are also interpreted. Finally, accelerators and wigglers for FEL, recent FEL experiments and FEL applications are noted. (author).

Science.gov (United States)

The primary concern of this work is to study the emission characteristics of a series of chiral nematic liquid crystal lasers doped with different laser dyes (DCM, pyrromethene 580, and pyrromethene 597) at varying concentrations by weight (0.5-2 wt %) when optically pumped at 532 nm. Long-wavelength photonic band-edge laser emission is characterized in terms of threshold energy and slope efficiency. At every dye concentration investigated, the pyrromethene 597-doped lasers exhibit the highest slope efficiency (ranging from 15% to 32%) and the DCM-doped lasers the lowest (ranging from 5% to 13%). Similarly, the threshold was found to be, in general, higher for the DCM-doped laser samples in comparison to the pyrromethene-doped laser samples. These results are then compared with the spectral properties, quantum efficiencies and, where ...

UK PubMed Central (United Kingdom)

BackgroundThere are various treatment options for congenital melanocytic nevus (CMN), including surgical excision, dermabrasions, curettage, laser treatment, chemical peels and cryosurgery....Full Text Available

KoreaScience (Korea)

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Science.gov (United States)

PMID:21671451

Science.gov (United States)

The initiation of explosives by laser illumination has been known for many years. In this paper we will discuss the development of a working detonator design that reduces the energy required for detonation in a low-density secondary explosive by vaporizing a thin metal coating. We present data on the development of the design for a workhorse laser detonator that provides enhanced safety over existing exploding bridgewire detonators (EBWs). Comparison of this laser initiated data to an exploding-bridgewire (EBW) provides insight into the mechanism of initiation of detonation in low-density PETN by the plasma source. A novel diagnostic technique to determine the run-distance to detonation also known as the apparent Center-of-Initiation (COI) will also be discussed.

International Nuclear Information System (INIS)

The problem of search for new materials for spectrally positioned laser sources, which is central for modern photonics, is discussed. The use of the stimulated Raman scattering effect in crystals offers a highly efficient way to the design of such sources. The recent results of investigations into this effect for a large number of various types of crystalline materials are presented. The most promising compounds, as regards the realisation of different laser operation modes, are considered, including calcium, strontium, barium and lead molybdates and tungstates. Several examples of functioning efficient lasers based on novel materials exhibiting the stimulated Raman light scattering effect are given.

Energy Technology Data Exchange (ETDEWEB)

New technologies make multi-megajoule glass lasers economically feasible. Laser architectures using harmonic switchout, target plane holographic injection, phase conjugation, continuous apodization and higher amplifier efficiencies have been devised. A plan for a multi-megajoule laser which can be built for an acceptable cost relies on manufacturing economies of scale and the demonstration of the new technologies presented here. These include continuous pour glass production, rapid harmonic crystal growth, switching of large blocks of power using larger capcaitors packed more economically and by using large identical parts counts.

Science.gov (United States)

This letter describes the first lasing experiment of the heterostructure semiconductor Raman laser with lateral confinement of both the Stokes and pump fields. It has a GaP Raman active layer with thickness of 10 ..mu..m and Al/sub 0.1/Ga/sub 0.9/P cladding layers. The stripe of the active layer has been fabricated by a plasma etching technique. Steps should be taken to realize the semiconductor Raman laser pumped by an injection laser, applicable to wideband optical communication.

Science.gov (United States)

... space vehicles, robot and machine guidance systems, and in various types of autonomous UUV docking situations. Page 3. ...

Energy Technology Data Exchange (ETDEWEB)

The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

Science.gov (United States)

Spectral and energy luminescence characteristics of R6G dye solutions in ethanol with addition of Ag nanoparticle suspensions in different aggregate states are experimentally investigated. It is demonstrated that incorporation of non-aggregated and aggregated nanoparticles causes the superluminescence thresholds in R6G solutions to decrease. It is established that the optical properties of the laser beam propagation channel are transformed when low-power (20 mW) cw laser radiation passes through the suspension of nanoparticles. This is manifested through the occurrence of a region with enhanced nanoparticle density in the laser beam center, on which diffraction of laser radiation is observed.

Energy Technology Data Exchange (ETDEWEB)

High-power diode laser arrays emitting at 690 nm have been developed for solid-state laser pumping. The laser diode bars (fill factor [approx]0.7) have been fabricated from single quantum well AlGaInP-based heterostructures. Using silicon microchannel heatsinks, a record high 360 W/cm[sup 2] per emitting aperture is achieved under continuous wave operation.

International Nuclear Information System (INIS)

In terms of the kinetic theory of the interaction between the high-power short-time laser pulses with plasma based on the propagator plotting for the plasma particle distribution functions one studied the generation of the hot electrons and of the fast ions as the relativistic femtosecond laser pulses travelled through the supercritical density plasma. One performed calculations based on the various values of the laser pulse intensity, types of the multiple-charged ions, the plasma inhomogeneity degree. One studied the acceleration mechanisms both of the plasma electrons and ions

International Nuclear Information System (INIS)

Coherent x-ray production by a seeded free electron laser (FEL) is important for next generation synchrotron light sources. The authors examine the feasibility and features of FEL emission seeded by a high-order harmonic generation (HHG) of an infrared laser. In addition to the intrinsic FEL chirp, the longitudinal profile and spectral bandwidth of the HHG seed are modified significantly by the FEL interaction well before saturation. This smears out the original attosecond pulselet structure. The authors introduce criteria for this smearing effect on the pulselet and the stretching effect on the entire pulse. They discuss the noise issue in such a seeded FEL.

Science.gov (United States)

... Acousto-optic programmable dispersive filters (AOPDF) have been developed for optical signal processing, polarization switching in lasers, and ...

Science.gov (United States)

... Personal Author(s) : ROTHSCHILD, M. ; EHRLICH, DJ ; SHAVER, DC. Report Date : 1989. Pagination or Media Count : 3. ...

British Library Electronic Table of Contents (United Kingdom)

The subband structure and optical properties of a cylindrical quantum well wire under intense non-resonant laser field are investigated by taking into account the correct dressing effect for the confinement potential. The energy levels and wave functions are calculated within the effective mass- approximation using a finite element method. It is found that the absorption coefficient and the saturation intensity are strongly affected by the laser amplitude and frequency as well as by the incident light polarization. As a key result, a large anisotropy in the linear and nonlinear optical absorptions for very intense laser field is predicted. These effects can be useful for the design of polarization sensitive devices.

Energy Technology Data Exchange (ETDEWEB)

The wavelength dependence of the threshold in an InGaP-InAlGaP vertical cavity surface emitting laser is investigated using a microscopic theory of the semiconductor gain medium. Good agreement is found between experiment and theory for the minimum threshold lasing wavelength for a range of laser structures.

International Nuclear Information System (INIS)

Recent progress with the (Al_xGa_1_-_x)_0_._5In_0_._5P alloy system has resulted in laser diodes which operate at room temperature at wavelengths below 640 nm. OMVPE is used to grow the multi-quantum-well devices in a graded-index separate-confinement configuration. Laser threshold currents as low as 75 mA have been achieved.

Energy Technology Data Exchange (ETDEWEB)

The peculiarities of pulsed laser melting and evaporation of the superconducting ceramics are analyzed by means of numerical simulation. The appearance of the overheated metastable states in solid and liquid phases is shown as a result of the phase front dynamics and volume nature of laser energy release. A method of dynamic adaptation for the multifront Stefan problem is proposed.

Energy Technology Data Exchange (ETDEWEB)

Laser safety standards and eye protection (filters) are designed to limit ocular exposures to prevent retinal lesions, yet eyesafe laser exposures can disrupt vision by causing glare and flashblindness. Protective filters can have opposing effects on vision function. They reduce laser exposures but also reduce task luminance and contrast. Filters alone may interfere with vision and consequently reduce work safety and performance. It is therefore important to be able to predict the effects of both laser exposures and protective filters to assess trade-offs between protection and visual function. This paper briefly reviews the methods, concepts, and experimental database used in our laboratory to predict laser, filter, and laser-plus-filter effects on tasks involving visual detection. The modeling approach uses estimates of the spatial distribution of light in the ...

Energy Technology Data Exchange (ETDEWEB)

Values of frequency splittings in the lithium isotopes have been determined with the aid of laser-induced fluorescene in a supersonic beam, perpendicularly irradiated by a CW ring dye laser. The residual 2s-2p isotope shift has been found to bw 4721.8 +- 2.0 MHz, leading to a specific mass shift for the 2p level of -3610.8 +- 5 MHz.

Energy Technology Data Exchange (ETDEWEB)

The Westinghouse Electric Corporation has undertaken to investigate, develop, and characterize laser-assisted processing techniques utilized to produce the fine line, thin metal grid structures that are required to fabricate high-efficiency solar cells. Two basic techniques for metal deposition will be investigated, as follows: (1) photochemical decomposition of liquid or gas phase organometallic compounds utilizing either a focused, CW ultraviolet laser (System 1) or a mask and ultraviolet flood illumination, such as that provided by a repetitively pulsed, defocused excimer laser (System 2), for pattern definition, and (2) thermal deposition of metals from organometallic solutions or vapors utilizing a focused, CW laser beam as a local heat source to draw the metallization pattern. The purpose of this contract is to investigate the various existing laser-assisted film deposition ...

International Nuclear Information System (INIS)

A 10.6-micron wavelength free-electron laser (FEL) amplifier has been operated using a 45-MeV, 600-A electron beam from the Advanced Test Accelerator (ATA) and a 15.36-meter long electromagnetic wiggler. The peak small signal power gain was 27 dB(500). Gain guiding was observed to confine the amplified laser beam.

Energy Technology Data Exchange (ETDEWEB)

Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

Energy Technology Data Exchange (ETDEWEB)

Under coaxial flash lamp pumping the laser efficiency of coumarin-4 in slightly basic ethyl alcohol solution as an active medium has reached a value of 0.14%. That is three times higher than that in the basic aqueous solution. Its tunable wavelength range of laser output has extended from 440 to 510 nm with the maximum at 460 nm.

International Nuclear Information System (INIS)

We present our plans for a Monte-Carlo code simulating all possible combinations of (electromagnetic) interactions between colliding electron, positron, and both high-energy and laser photon beams, based, on the ABEL code for beam-beam interaction. The implementation and first results for the laser-e"- interaction are described.

International Nuclear Information System (INIS)

An 'electron-bridge' mechanism of nuclear reaction in an atom or ion by ultra-intense laser fields is presented. A preliminary estimate of the intensity dependence of the rate of disintegration reaction of deuteron nucleus in deuterium atom is made for 800 nm laser fields. For intensities below 5x1021 W/cm2, the rate of disintegration by the 'electron-bridge' mechanism is found to be small, but it rises sharply and becomes large already for ?1022 W/cm2.

International Nuclear Information System (INIS)

Exposure of cells to light of less than 320 nanometers wavelengths may lead to lethal lesions and perhaps carcinogenesis. Many organisms have evolved mechanisms to repair U.V. light-induced damage. Organisms such as deep-sea bacteria are presumably never exposed to U.V. light and perhaps occasionally to visible from bioluminescence. Thus, the repair of U.V. damage in deep-sea bacterial DNA might be inefficient and repair by photoreactivation unlikely. The bacteria utilized in this investigation are temperature sensitive and barophilic. Four deep-sea isolates were chosen for this study: PE-36 from 3584 m, CNPT-3 from 5782 m, HS-34 from 5682 m, and MT-41 from 10,476 m, all are from the North Pacific ocean. The deep-sea extends from 1100 m to depths greater than 7000 m. It is a region of relatively uniform conditions. The temperature ranges from 5 to -1"0C. There is no solar light in the deep-sea. Deep-sea bacteria are ...

International Nuclear Information System (INIS)

We describe the growth, fabrication, and characterization of an ultraviolet (UV) photoconductive detector based on In_xAl_yGa_1_-_x_-_yN quaternary alloy that is lattice matched to GaN. The detector consisted of 0.1 #mu#m In_xAl_yGa_1_-_x_-_yN alloy grown on 0.5-1.0 #mu#m GaN epilayer by metalorganic chemical vapor deposition. With varying indium concentration, the cut-off wavelength of the In_xAl_yGa_1_-_x_-_yN detectors could be varied to the deep UV range. The most important and intriguing result is that the responsivity of the In_xAl_yGa_1_-_x_-_yN quaternary alloy exceeded that of AlGaN alloy of a comparable cutoff wavelength by a factor of five. This makes the nitride quaternary alloy very important material for solar blind UV detectors applications particularly in the deep UV range where Al rich AlGaN alloys have problems with low quantum efficiency and cracks due in part to lattice mismatch with ...

International Nuclear Information System (INIS)

The helicase action of the Escherichia coli UvrAB complex on a covalently closed circular DNA template was monitored using bacterial DNA topoisomerase I, which specifically removes negative supercoils. In the presence of E. coli DNA topoisomerase I and ATP, the UvrAB complex gradually introduced positive supercoils into the input relaxed plasmid DNA template. Positive supercoils were not produced when E. coli DNA topoisomerase I was replaced by eukaryotic DNA topoisomerase I or when both E. coli and eukaryotic DNA topoisomerases I were added simultaneously. These results suggest that like other DNA helix-tracking processes, the ATP-dependent action of the UvrAM complex on duplex DNA simultaneously generates both positive and negative supercoils, which are not constrained by protein binding but are torsionally strained. The supercoiling activity of UvrAB on UV-damaged DNA was also studied using UV-damaged plasmid DNA and a mutant UvrA protein ...

British Library Electronic Table of Contents (United Kingdom)

We fabricate a low noise erbium-doped fiber ring laser that can be continuously tuned over 102nm by insertion of the fiber Fabry-Perot tunable filter (FFP-TF) in the ring cavity with a novel cavity structure and the optimal gain medium length. As an application of this fiber ring laser, we performed the absorption spectroscopy of acetylene (13C2H2) and hydrogen cyanide (H13C14N) and measure the absorption spectra of more than 50 transition lines of these gases with an excellent signal to noise ratio (SNR). The pressure broadening coefficients of four acetylene transition lines are obtained using this fiber ring laser and an external cavity laser diode.

International Nuclear Information System (INIS)

Pulsed atomic beams produced in vacuum by laser induced ablation from a lithium target are analyzed by laser induced fluorescence (LIF). The 1-mixing processes induced in the n = 9, 10 Li Rydberg states by collisions with CO_2 molecules illustrate the application of the method. Resolution is limited by the 1 mm diameter of the probe laser beam. Combining LIF and absorption measurements gives n_L_i as a function of time at various distances from the target surface. The investigation of the Li-C0_2 1-mixing process in a heat pipe oven proved impossible due to the high reactivity of Li with C0_2. This problem was solved by renewing the Li atoms at each laser shot. Values obtained for n = 9, n = 10 are k = 17 x 10"-"8 and 15 x 10"-"8 cc/sec, respectively.

Energy Technology Data Exchange (ETDEWEB)

The spectroscopic properties of Cr{sup 2+}, Co{sup 2+}, and Ni{sup 2+}-doped single crystals of ZnS, ZnSe, and ZnTe have been investigated to understand their potential application as mid-IR tunable solid-state laser media. The spectroscopy indicated divalent Cr was the most favorable candidate for efficient room temperature lasing, and accordingly, a laser-pumped laser demonstration of Cr:ZnS and Cr:ZnSe has been performed. The lasers` output were peaked at {approximately} 2.35 {mu}m and the highest measured slope efficiencies were {approximately} 20% in both cases.

International Nuclear Information System (INIS)

It is known that a high-power laser propagating through an underdense plasma can acquire a minimum spot size due to relativistic self-focusing. Beyond the focus, the nonlinear refraction starts weakening, and the spot size of the laser increases, showing periodic self-focusing/ defocusing behavior with the distance of propagation. To overcome the defocusing, we propose the introduction of a localized upward plasma density ramp. In the presence of an upward ramp of plasma density, the laser beam obtains a minimum spot size and maintains it with only a mild ripple. For suitable parameters of the laser and the plasma, we have deduced conditions for the self-focusing. This kind of plasma density ramp may be observed in a gas-jet plasma experiment and resembles a plasma lens.

Energy Technology Data Exchange (ETDEWEB)

An investigation was made of the accumulation of laser damage to transparent polymers irradiated with nanosecond pulses from neodymium and ruby lasers. The damage was investigated by the method of scattering and luminescence in the visible and near ultraviolet parts of the spectrum. It was established that there were two stages in laser damage by repeated irradiation with pulses of intensity below the single-shot damage threshold. An absorbing defect evolved during the first stage in such a way as to create a thermal instability in the surrounding matrix. During the second stage this thermal instability caused spatial growth of laser damage because of propagation of an ionization-inducing absorption wave with a front traveling at the rate governed by the electron component of the thermal conductivity.

Energy Technology Data Exchange (ETDEWEB)

In this contract, Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are being investigated, developed, and characterized. The tasks comprising these investigations are outlined. Four new batches of solar cells were processed, in addition to several test runs on wafers, using the laser decomposition of spun-on silver neodecanoate to metallize cells. Decomposition of silver neodecanoate was carried out at different laser powers on different cells on a given wafer to determine whether this would have any effect on cell performance. A one watt laser power gave an electroplated linewidth of 50 ..mu..m, while at 8 watts the line width was 90 ..mu..m.

Energy Technology Data Exchange (ETDEWEB)

The high repetition rate and low single-pass gain inherent in an rf-driven Free Electron Laser (FEL) dictate that the laser system be configured as an oscillator. This allows the laser's electric field to build up over many passes around a high Q cavity. By way of contrast, the high-current capability of the Induction Linac (IL) system permits high single-pass optical gain, but the relatively low duty factor precludes oscillator operation; the pulses are neither long enough nor often enough to permit a field to accumulate in a cavity. The IL is thus configured as a MOPA (master oscillator/power amplifier) with a conventional laser serving as the MO. This report concentrates on the status of IL-driven FEL research at LLNL and gives a description of several applications for the high-peak-power radiation produced by an induction linac FEL.

International Nuclear Information System (INIS)

The paper proposes a concept of power driver for industrial thermonuclear reactor based on inertial thermonuclear synthesis (ITS). The circuit is based on the application of free electron laser (FEL) as a energy source for thermonuclear target compression which becomes feasible due to the application of a radically new circuit of FEL-amplifier. In the project under consideration the FEL-based laser system operates on the wave length of 0.5 micrometer. The full energy of laser radiation equals 1 MJ. This energy is delivered to the target in the pulse whose length is controlled within the range of 0.1-2 ns. The laser system brightness is 4 x 10"2"2 W cm"-"2. The FEL operating pulse repetition frequency is 40 Hz, full efficiency of electricity conversion into the energy of optical radiation is 11%. 9 refs., 3 figs., 2 tabs.

International Nuclear Information System (INIS)

We present and characterize a very efficient optical device that employs the plasma mirror technique to increase the contrast of high-power laser systems. Contrast improvements higher than 104 with 50% transmission are shown to be routinely achieved on a typical 10 TW laser system when the pulse is reflected on two consecutive plasma mirrors. Used at the end of the laser system, this double plasma mirror preserves the spatial profile of the initial beam, is unaffected by shot-to-shot fluctuations, and is suitable for most high peak power laser systems. We use the generation of high-order harmonics as an effective test for the contrast improvement produced by the double plasma mirrors. (authors)

British Library Electronic Table of Contents (United Kingdom)

Within the framework of the effective-mass approximation, using a variational method, we have calculated the effect of intense laser radiation on the binding energy of the shallow-donor impurities in a Ga1- x In x N y As1- y /GaAs single quantum well for different nitrogen and indium mole concentrations. Our numerical results show that the binding energy strongly depends on the laser intensity and frequency (via the laser dressing parameter) and it also depends on the nitrogen and indium concentrations. Impurity binding energy under intense laser fields can be tuned by changing the nitrogen and indium mole fraction.

International Nuclear Information System (INIS)

A static plasma grating has been demonstrated experimentally in a large optical cavity FIB-DBR GaAlAs/GaAs laser diode. The grating is formed by implanting stripes of dopants with a focused ion beam (FIB). The dopants ionize to form periodic fluctuations in the carrier concentration which, through the Kramers-Kronig relations, form an index grating. A model of the grating strength for optimization of the laser design is developed and presented here. The computed results show that #kappa# can be increased by more than an order of magnitude over the 15 cm"-"1 experimentally. Therefore, FIB-DBR (or -DFB) lasers with performance comparable to that of conventional DBR (or DFB) lasers can be expected.

British Library Electronic Table of Contents (United Kingdom)

Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) has been proposed several years ago as an approach for quantitative analysis of Laser-Induced Breakdown Spectroscopy spectra. Recently developed refinement of the spectral processing method is described in the present work. Accurate quantitative results have been demonstrated for several metallic alloys. However, the degree of accuracy that can be achieved with Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of generic samples still needs to be thoroughly investigated. The authors have undertaken a systematic study of errors and biasing factors affecting the calculation in the Calibration-Free Laser-Induced Breakdown Spectroscopy spectra processing. These factors may be classified in three main groups: 1) experi...

Energy Technology Data Exchange (ETDEWEB)

The effects of the contrast of the pump field interference pattern, that is, the effectiveness of the dynamic amplitude-phase grid, and various optical arrangements on the lasing efficiency and tuning range of a dynamic distributed-feedback dye laser are investigated. It is shown that the proper choice of prism apex angle, prism material and dye solvent in a laser in the range 400-1000 microns pumped by two beams of different intensity directed through the congruent sides of an isosceles prism in contact with the active medium solution on its third side can lead to optical losses of less than 2% from the boundaries of the prism. Measurements of polymethine dye laser efficiency and tuning range as a function of the relative intensity of the two ruby-laser pump beams reveals that as the contrast of the pump beam interference pattern decreases, the tuning range remains practically constant and the ...

Energy Technology Data Exchange (ETDEWEB)

In order to improve the long term reliability of lead-salt diode lasers, ohmic contacts of multilayer, thin-film structures consisting of In plus Au, Pt, Ni, and Pd have been studied. Diode lasers of PbSnTe fabricated with a variety of contacts were tested during room-temperature storage and during accelerated aging tests. The results show that contact reliablility can be improved when multiple overlapping films are used. After 4500 h of baking at 60 /sup 0/C, lasers with In-Au-Pd-Au contacts on both sides showed the least resistance increase (10%). For lasers with In-Au-Pt-Au contacts, 1 h of baking at 60 /sup 0/C is equivalent to 2 d storage at room temperature. Extrapolating these results, a 70% increase in contact resistance is expected for this type of laser after 9000 d of storage at room temperture. Our data also suggests that a smaller increase in contact resistance can be ...

International Nuclear Information System (INIS)

Tm3+ and Dy3+ ions co-doped aluminoborosilicate glasses were prepared in this study. The luminescence properties of the glasses were analyzed. A combination of blue, green, yellow, and red emission bands was shown for these glasses, and white light emission could be observed under UV light excitation. White light luminescence color could be changed by varying the excitation wavelength. Concentration quenching effect was investigated in this paper. Furthermore, the dependence of luminescence properties on glass compositions was studied. Results showed that the luminescence intensity changed with different network modifier oxides, while the white color luminescence was not affected significantly. - Graphical abstract: Tm3+ and Dy3+ ions co-doped aluminoborosilicate glasses, which emit white light under UV light excitation, were prepared. The dependence of luminescence properties on glass compositions was studied, and results showed that the white ...

International Nuclear Information System (INIS)

Ethidium bromide (EB) and ultraviolet light (UV) in combination are known to produce a synergistic induction of 'petite' mutants in yeast. Two other agents were combined with EB, 3-Carbethoxypsoralene (3 CPs) activated by 365 nm light or #gamma# rays. EB in combination with 3 CPs also resulted in an enhanced production of 'petite' mutants. After the photoaddition of 3 CPs in exponential phase cells, recovery of the 'petite' mutation during dark liquid holding was inhibited by the presence of EB producing an enhanced number of 'petite' mutants. The behavior of mitochondrial antibiotic resistance markers after individual and combined treatments with EB and 3 CPs indicates a random loss of markers after EB and a preferential loss of a certain region for the 3 CPs photoaddition. The combination of the two agents leads to an additivity of total drug marker losses rather than a synergistic loss. The combination of EB with #gamma# rays produced no enhancement in 'petite' ...

CERN Document Server

We present ultraviolet spectra of Mira's companion star from the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). The companion is generally assumed to be a white dwarf surrounded by an accretion disk fed by Mira's wind, which dominates the UV emission from the system. The STIS UV spectrum is dominated by numerous, narrow H2 lines fluoresced by H I Ly-alpha, which were not detected in any of the numerous observations of Mira B by the International Ultraviolet Explorer (IUE). The high temperature lines detected by IUE (e.g., C IV 1550) still exist in the STIS spectrum but with dramatically lower fluxes. The continuum fluxes in the STIS spectra are also much lower, being more than an order of magnitude lower than ever observed by IUE, and also an order of magnitude lower than fluxes observed in more recent HST Faint Object Camera objective prism spectra from 1995. Thus, the accretion rate onto Mira ...

British Library Electronic Table of Contents (United Kingdom)

Fe-doped TiO2 hollow spheres (Fe-THs) were synthesized by sol?gel process using carbon spheres as templates. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV?vis diffuse reflectance spectrum (DRS), N2 adsorption?desorption isotherms, Electron paramagnetic resonance (EPR) spectroscopy and Photoluminescence emission spectroscopy (PL). UV?vis spectra showed that Fe3+ doping could extend the absorption edge to the visible region. EPR spectra showed that Fe3+ was incorporated into the crystal lattice of TiO2, which could inhibit the recombination of photo-induced electron?hole pairs and improve the photocatalytic activity. The photocatalytic activities of the prepared samples were evaluated for the degradation of dye Reactive Brillia...

Energy Technology Data Exchange (ETDEWEB)

In this paper we present status and developments of the Duke storage ring facility. The Duke storage ring facility provides the unique combination of phase-locked light sources ranging from high power OK-4 XUV FEL to quasimonochromatic {gamma}-ray beam and IR/X-ray spontaneous radiation. The XUV OK-4 FEL, which is collaborative project with BlNP, Novosibirsk, is in operation since November, 1996. The OK-4 UV FEL is also used for production of nearly monochromatic {gamma}-ray s with tunable energy. We present the results of UV lasing with the OK4 FEL and selected results of its applications. We will discuss our future plans for extension of this source and status of the construction of dedicated used facility adjacent to the FEL building. (author)

Energy Technology Data Exchange (ETDEWEB)

Medicinal plants i.e. dried seeds of myristica argentea, myristica fragrans, coriandrum sativum and foeniculum vulgare were stored for 0 and 6 months, with and without gamma irradiation at 5 kGy. No detectable changes were seen in infrared and UV spectra, GLC chromatograms and refraction indices of steam distilled, essential oils from the irradiated medicinal plants. The same results were also obtained from irradiated samples stored for 6 months at ambient conditions. Storage for 6 months caused significant changes in the gas liquid chromatograms and UV spectra of all samples compared to non-stored samples. The moisture content of all samples packed in polyethylene bags seems to be constant after 6 months of storage. No measurable changes were found in the amount of essential oil content caused by irradiation.

British Library Electronic Table of Contents (United Kingdom)

The degradation of irradiated human insulin in aqueous solutions was investigated in order to protect the protein against ionizing radiation. The influence of the drug concentration, excipients and irradiation temperature were studied.Aqueous solutions at pH 2 were irradiated by gamma rays or by accelerated electrons. Two different high-performance liquid chromatography (HPLC) methods were used: reverse-phase high-performance liquid chromatography (RP-HPLC)/UV and size exclusion liquid chromatography (SEC/UV) to investigate both the fragmentation and the formation of higher molecular weight proteins.In solution without excipients irradiated at ambient temperature at 10kGy, the loss of human insulin is almost complete. Addition of radio-protecting excipients (free radicals scavengers) and c...

CERN Document Server

The Warm-Hot Intergalactic Medium (WHIM) arises from shock-heated gas collapsing in large-scale filaments and probably harbours a substantial fraction of the baryons in the local Universe. Absorption-line measurements in the ultraviolet (UV) and in the X-ray band currently represent the best method to study the WHIM at low redshifts. We here describe the physical properties of the WHIM and the concepts behind WHIM absorption line measurements of H I and high ions such as O VI, O VII, and O VIII in the far-ultraviolet and X-ray band. We review results of recent WHIM absorption line studies carried out with UV and X-ray satellites such as FUSE, HST, Chandra, and XMM-Newton and discuss their implications for our knowledge of the WHIM.

CERN Document Server

Assuming the hoop conjecture in classical general relativity and quantum mechanics, any observer who attempts to perform an experiment in an arbitrarily small region will be stymied by the formation of a black hole within the spatial domain of the experiment. This behavior is often invoked in arguments for a fundamental minimum length. Extending a proof of the hoop conjecture for spherical symmetry to include higher curvature terms we investigate this minimum length argument when the gravitational couplings run with energy in the manner predicted by asymptotically safe gravity. We show that argument for the mandatory formation of a black hole within the domain of an experiment fails. Neither is there a proof that a black hole doesn't form. Instead, whether or not an observer can perform measurements in arbitrarily small regions depends on the specific numerical values of the couplings near the UV fixed point. We further argue that when an experiment is localized on ...

British Library Electronic Table of Contents (United Kingdom)

Nowadays there are many sun-protection cosmetics incorporating organic or inorganic UV filters as active ingredients. Chemically stable inorganic sunscreen agents, usually metal oxides, are widely employed in high-SPF (sun protection factor) products. Titanium dioxide is one of the most frequently used inorganic UV filters. It has been used as a pigment for a long period of cosmetic history. With the development of micronization techniques, it has become possible to incorporate titanium dioxide in sunscreen formulations without the previous whitening effect, and hence its use in cosmetics has become an important research topic. However, there are very few works related to quantitation of titanium dioxide in sunscreen products. In this research, we analysed the amounts of titanium dioxide i...

Energy Technology Data Exchange (ETDEWEB)

This work presents the development of a streak camera 'jitter free' sweep unit synchronized on a femtosecond laser. This application of high voltage photoconductive switches ('High voltage Auston switch') yields subpicosecond resolution for accumulated images on streak camera on a few hundreds micro joule femtosecond laser. Two others applications of these photoconductive switches are studied: - ultrafast optical commutation by a Pockels cell directly driven by a photoconductive switch (rising edge < 100 ps and jitter < 2 ps), - laser pulse energy self-stabilization experimentally proving that driving a Pockels cell by a photoconductive switch can increase the stability of the laser pulse energy from 7 % to 0.7 % rms. Additionally, the application of the acoustic-optical programmable dispersive filter (Dazzler) to the self referenced spectral phase ...

Science.gov (United States)

We report on recent progress and improvements in the metal-organic chemical vapor deposition (MOCVD) growth of mid-infrared lasers and using a high speed rotating disk reactor (RDR). The devices contain AlAsSb active regions. These lasers have multi-stage, type I InAsSb/InAsP quantum well active regions. A semi-metal GaAsSb/InAs layer acts as an internal electron source for the multi-stage injection lasers and AlAsSb is an electron confinement layer. These structures are the first MOCVD multi-stage devices. Growth in an RDR was necessary to avoid the previously observed Al memory effects found in conventional horizontal reactors. A single stage, optically pumped laser yielded improved power (greater than 650 mW/facet) at 80K and 3.8um. A multi-stage 3.8-3.9um laser structure operated up to T=170K. At 80K, peak power greater than 100mW and a high slope- efficiency were observed in ...

Energy Technology Data Exchange (ETDEWEB)

(Al{sub y}Ga{sub 1{minus}y}){sup 1{minus}x}In{sub x}P semiconductor alloys lattice-matched to GaAs are widely used in visible optoelectronic devices. One of the most recent developments in this area is the AlGaInP-based red vertical cavity surface emitting laser (VCSEL). These lasers, which employ AlGaInP active regions and AlGaAs distributed Bragg reflectors (DBRs), have demonstrated continuous-wave (CW) lasing over the 630--690 nm region of the spectrum. Applications for these lasers include plastic fiber data communications, laser printing and bar code scanning. In this paper, the authors present an overview of recent developments in the processing and performance of AlGaInP based VCSELs. This overview will include a review of the general heterostructure designs that have been employed, as well as the performance of lasers fabricated by both ion implantation and selective ...

Energy Technology Data Exchange (ETDEWEB)

The following work deals with the realization, characterization and modeling of GaInP / AlGaInP high power semiconductor laser diodes in the visible wavelength range. In addition to the exploration and optimization of efficiency, temperature stability and maximum output power of multi-mode lasers especially methods for longitudinal and lateral mode stabilization of high power laser diodes have been investigated. Although often the focus of optimization is on the threshold current density, in this work the performance of the laser diode for an operation point around 1 Watt under continous wave operation is regarded as the figure of merit. It turns out that low carrier densities are key for an efficient reduction of the heterobarrier leakage currents. In addition, large optical cavity structures with low internal losses enable high external quantum efficiencies even for long cavities. Finally high ...

Science.gov (United States)

... uv{otxhdbehuSZ\\aed``USff[`shi~tnbocrwnuutvmx???????????v?rz??{|untokwqjl{~ ...... \\]OK]code[P\\XDYTM^NBEJN[Ug`9XXz?xa`c=L9VZBW^OGaVSWeheh}?????n[SZaHWd\\U> ...... ^SMO;RNmu[[XGULLY>6GABUYULE0KXUNU^hguwuegl???matocVAd`POLU;EHDCN=>SV? ...

UK PubMed Central (United Kingdom)

A mixed copper complex with deprotonated nalidixic acid (nal) and histamine (hsm) was synthesized and characterized by FTIR, UV-Vis, elemental analysis, and conductivity. The crystal structure of [Cu(hsm)(nal)H₂O]Cl·3H₂O...Full Text Available

UK PubMed Central (United Kingdom)

Epidermal gamma delta T cells (γδ T) and Langerhans cells (LC) are immune cells altered by exposure to ultraviolet radiation (UVB), a powerful stressor resulting in immune suppression....Full Text Available

CERN Document Server

The Rayleigh scattering length has been calculated for rare-gas liquids in the ultraviolet for the frequencies at which they luminesce. The calculations are based on the measured dielectric constants in the gas phase, except in the case of xenon for which measurements are available in the liquid. The scattering length mayplace constraints on the design of some large-scale detectors, using uv luminescence, being proposed to observe solar neutrinos and dark matter. Rayleigh scattering in mixtures of rare-gas mixtures is also discussed.

International Nuclear Information System (INIS)

We use UV/optical and X-ray observations of 272 radio-quiet Type 1 active galactic nuclei and quasars to investigate the C IV Baldwin Effect (BEff). The UV/optical spectra are drawn from the Hubble Space Telescope, International Ultraviolet Explorer and Sloan Digital Sky Survey archives. The X-ray spectra are from the Chandra and XMM-Newton archives. We apply correlation and partial-correlation analyses to the equivalent widths (EWs), continuum monochromatic luminosities, and ?ox, which characterizes the relative X-ray to UV brightness. The EW of the C IV ?1549 emission line is correlated with both ?ox and luminosity. We find that by regressing l?(2500 A) with EW(C IV) and ?ox, we can obtain tighter correlations than by regressing l?(2500 A) with only EW(C IV). Both correlation and regression analyses imply that l?(2500 A) is not the only factor controlling the changes of EW(C IV); ?ox (or, equivalently, the soft X-ray ...