WorldWideScience

Sample records for billion high emitters

  1. Optimized aperiodic highly directional narrowband infrared emitters

    Science.gov (United States)

    Granier, Christopher H.; Afzal, Francis O.; Min, Changjun; Dowling, Jonathan P.; Veronis, Georgios

    2014-09-01

    Bulk thermal emittance sources possess incoherent, isotropic, and broadband radiation spectra that vary from material to material. However, these radiation spectra can be drastically altered by modifying the geometry of the structures. In particular, several approaches have been proposed to achieve narrowband, highly directional thermal emittance based on photonic crystals, gratings, textured metal surfaces, metamaterials, and shock waves propagating through a crystal. Here we present optimized aperiodic structures for use as narrowband, highly directional thermal infrared emitters for both TE and TM polarizations. One-dimensional layered structures without texturing are preferable to more complex two- and three-dimensional structures because of the relative ease and low cost of fabrication. These aperiodic multilayer structures designed with alternating layers of silicon and silica on top of a semi-infinite tungsten substrate exhibit extremely high emittance peaked around the wavelength at which the structures are optimized. Structures were designed by a genetic optimization algorithm coupled to a transfer matrix code which computed thermal emittance. First, we investigate the properties of the genetic-algorithm optimized aperiodic structures and compare them to a previously proposed resonant cavity design. Second, we investigate a structure optimized to operate at the Wien wavelength corresponding to a near-maximum operating temperature for the materials used in the aperiodic structure. Finally, we present a structure that exhibits nearly monochromatic and highly directional emittance for both TE and TM polarizations at the frequency of one of the molecular resonances of carbon monoxide (CO); hence, the design is suitable for a detector of CO via absorption spectroscopy.

  2. Innovative Field Emitters for High-Voltage Electronic Devices

    Science.gov (United States)

    Sominski, G. G.; Sezonov, V. E.; Taradaev, E. P.; Tumareva, T. A.; Zadiranov, Yu. M.; Kornishin, S. Yu.; Stepanova, A. N.

    2015-12-01

    We describe multitip field emitters with protective coatings, which were developed in Peter the Great St. Petersburg Polytechnic University. The coatings ensure long-term operation of the emitters under high currents and technical vacuum. Innovative multi-layer emitters composed of contacting nanolayers of materials with different work functions are presented as well. The possibility by using the developed emitters in high-voltage electronic devices is demonstrated.

  3. High-temperature plasmonic thermal emitter for thermophotovotaics

    DEFF Research Database (Denmark)

    Liu, Jingjing; Guler, Urcan; Li, Wei; Kildishev, Alexander V.; Boltasseva, Alexandra; Shalaev, Vladimir M.

    2014-01-01

    We use titanium nitride (TiN) to demonstrate an ultra-thin plasmonic thermal emitter operating at high temperatures (830 K). The spectrally selective emitter exhibits a large emittance at around 2.5 μm and below, and suppresses emission at longer wavelengths....

  4. What is so super about super-emitters? Characterizing methane high emitters from natural gas infrastructure

    Science.gov (United States)

    Zavala Araiza, D.; Lyon, D. R.; Alvarez, R.; Harriss, R. C.; Palacios, V.; Hamburg, S.

    2015-12-01

    Methane emissions across the natural gas supply chain are dominated at any one time by a few high-emitters (super-emitters or fat-tail of the distribution), often underrepresented in published datasets used to construct emission inventories. Characterization of high-emitters is essential for improving emission estimates based on atmospheric data (top-down) and emission inventories (bottom-up). The population of high-emitters (e.g. 10-20% of sites that account for 80-90% of the emissions) is temporally and spatially dynamic. As a consequence, it is challenging to design sampling methods and construct estimates that accurately represent their frequency and magnitude of emissions. We present new methods to derive facility-specific emission distribution functions that explicitly integrate the influence of the relatively rare super-emitters. These methods were applied in the Barnett Shale region to construct a custom emission inventory that is then compared to top-down emission estimates for the region. We offer a methodological framework relevant to the design of future sampling campaigns, in which these high-emitters are seamlessly incorporated to representative emissions distributions. This framework can be applied to heterogeneous oil and gas production regions across geographies to obtain accurate regional emission estimates. Additionally, we characterize emissions relative to the fraction of a facility's total methane throughput; an effective metric to identify sites with excess emissions resulting from avoidable operating conditions, such as malfunctioning equipment (defined here as functional super-emitters). This work suggests that identifying functional super-emitters and correcting their avoidable operating conditions would result in significant emission reductions. However, due to their spatiotemporal dynamic behavior, achieving and maintaining uniformly low emissions across the entire population of sites will require mitigation steps (e.g. leak detection

  5. Modelling high redshift Lyman-alpha Emitters

    CERN Document Server

    Garel, Thibault; Guiderdoni, Bruno; Schaerer, Daniel; Verhamme, Anne; Hayes, Matthew

    2012-01-01

    We present a new model for high redshift Lyman-Alpha Emitters (LAEs) in the cosmological context which takes into account the resonant scattering of Ly-a photons through expanding gas. The GALICS semi-analytic model provides us with the physical properties of a large sample of high redshift galaxies. We implement a gas outflow model for each galaxy based on simple scaling arguments. The coupling with a library of numerical experiments of Ly-a transfer through expanding or static dusty shells of gas allows us to derive the Ly-a escape fractions and profiles. The predicted distribution of Ly-a photons escape fraction shows that galaxies with a low star formation rate have a f_esc of the order of unity, suggesting that, for those objects, Ly-a may be used to trace the star formation rate assuming a given conversion law. In galaxies forming stars intensely, the escape fraction spans the whole range from 0 to 1. The model is able to get a good match to the UV and Ly-a luminosity function (LF) data at 3 < z <...

  6. Sharpening of field emitter tips using high-energy ions

    Science.gov (United States)

    Musket, Ronald G.

    1999-11-30

    A process for sharpening arrays of field emitter tips of field emission cathodes, such as found in field-emission, flat-panel video displays. The process uses sputtering by high-energy (more than 30 keV) ions incident along or near the longitudinal axis of the field emitter to sharpen the emitter with a taper from the tip or top of the emitter down to the shank of the emitter. The process is particularly applicable to sharpening tips of emitters having cylindrical or similar (e.g., pyramidal) symmetry. The process will sharpen tips down to radii of less than 12 nm with an included angle of about 20 degrees. Because the ions are incident along or near the longitudinal axis of each emitter, the tips of gated arrays can be sharpened by high-energy ion beams rastered over the arrays using standard ion implantation equipment. While the process is particularly applicable for sharpening of arrays of field emitters in field-emission flat-panel displays, it can be effectively utilized in the fabrication of other vacuum microelectronic devices that rely on field emission of electrons.

  7. High brightness symmetric emittance rf photoinjector preliminary design report

    International Nuclear Information System (INIS)

    A preliminary design for a high bunch charge (8 nC), low emittance (z = 1 mm. Electrical and beam dynamical aspects of the photoinjector design are presented. A description of the proposed experimental program is included

  8. High brightness fiber laser pump sources based on single emitters and multiple single emitters

    Science.gov (United States)

    Scheller, Torsten; Wagner, Lars; Wolf, Jürgen; Bonati, Guido; Dörfel, Falk; Gabler, Thomas

    2008-02-01

    Driven by the potential of the fiber laser market, the development of high brightness pump sources has been pushed during the last years. The main approaches to reach the targets of this market had been the direct coupling of single emitters (SE) on the one hand and the beam shaping of bars and stacks on the other hand, which often causes higher cost per watt. Meanwhile the power of single emitters with 100μm emitter size for direct coupling increased dramatically, which also pushed a new generation of wide stripe emitters or multi emitters (ME) of up to 1000μm emitter size respectively "minibars" with apertures of 3 to 5mm. The advantage of this emitter type compared to traditional bars is it's scalability to power levels of 40W to 60W combined with a small aperture which gives advantages when coupling into a fiber. We show concepts using this multiple single emitters for fiber coupled systems of 25W up to 40W out of a 100μm fiber NA 0.22 with a reasonable optical efficiency. Taking into account a further efficiency optimization and an increase in power of these devices in the near future, the EUR/W ratio pushed by the fiber laser manufacturer will further decrease. Results will be shown as well for higher power pump sources. Additional state of the art tapered fiber bundles for photonic crystal fibers are used to combine 7 (19) pump sources to output powers of 100W (370W) out of a 130μm (250μm) fiber NA 0.6 with nominal 20W per port. Improving those TFB's in the near future and utilizing 40W per pump leg, an output power of even 750W out of 250μm fiber NA 0.6 will be possible. Combined Counter- and Co-Propagated pumping of the fiber will then lead to the first 1kW fiber laser oscillator.

  9. Emittance measurement for high-brightness electron guns

    International Nuclear Information System (INIS)

    An emittance measurement system based on a high-precision pepper-pot technique has been developed for electron guns with low emittance of around πmm-mrad. Electron guns with a 1 mmφ cathode, the material of which is impregnated tungsten or single-crystal lanthanum hexaboride (La1-xCex)B6, have been developed. The performance has been evaluated by putting stress on cathode roughness, which gives rise to an angular divergence, according to the precise emittance measurement system. A new type of cathode holder, which is a modified version of the so called Vogel type, was developed and the beam uniformity has been improved. (Author) 5 figs., tab., 9 refs

  10. Achieving ultra-high temperatures with a resistive emitter array

    Science.gov (United States)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  11. Development of High Intensity Beam Emittance Measurement Unit

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Three sets of High Intensity Beam Emittance Measurement Units (HIBEMUs) are being developed at Peking University. They are HIBEMU-2 (slit-wire type, one direction), HIBEMU-3 (Allison scanner type, one direction) and HIBEMU-4 (slit-wire type, two directions). For HIBEMU-2 and HIBEMU-3, more recent work has been done on software redesign in order to measure beam emittance and to draw phase diagram more efficiently and precisely. Software for control and data processing of them were developed in Labveiw environment, trying to improve calculation rationality and to offer user-friendly interface. Mechanical modification was also done for HIBEMU-3, mainly concentrating on the protection of Faraday cups from being overheated by the high intensity beam and also from interference of secondary electrons. This paper will also cover the mechanical structure as well as the software development of HIBEMU-4, which is a two-direction emittance scanner newly designed and manufactured for the high energy beam transport (HEBT) of Peking University Neutron Imaging FaciliTY (PKUNIFTY). At the end of this paper, comparison and analysis of the three HIBEMUs are given to draw forth better design of the future emittance measurement facility.

  12. Applications using high-Tc superconducting terahertz emitters

    Science.gov (United States)

    Nakade, Kurama; Kashiwagi, Takanari; Saiwai, Yoshihiko; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

    2016-01-01

    Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system. The third is a system with precise temperature control to measure the liquid absorption coefficient. The detailed characteristics of these systems are discussed. PMID:26983905

  13. Effects of surface diffusion on high temperature selective emitters.

    Science.gov (United States)

    Peykov, Daniel; Yeng, Yi Xiang; Celanovic, Ivan; Joannopoulos, John D; Schuh, Christopher A

    2015-04-20

    Using morphological and optical simulations of 1D tantalum photonic crystals at 1200K, surface diffusion was determined to gradually reduce the efficiency of selective emitters. This was attributed to shifting resonance peaks and declining emissivity caused by changes to the cavity dimensions and the aperture width. Decreasing the structure's curvature through larger periods and smaller cavity widths, as well as generating smoother transitions in curvature through the introduction of rounded cavities, was found to alleviate this degradation. An optimized structure, that shows both high efficiency selective emissivity and resistance to surface diffusion, was presented. PMID:25969039

  14. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    Energy Technology Data Exchange (ETDEWEB)

    Davydenko, V. I., E-mail: V.I.Davydenko@inp.nsk.su; Ivanov, A. A., E-mail: A.A.Ivanov@inp.nsk.su; Shul’zhenko, G. I. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  15. High Turndown Ratio, High Delta-Emittance, Variable Emissivity Electrochromics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable-emittance materials are in high demand for applications ranging from manned and unmanned space platforms (e.g. in radiators at the Moon's poles where...

  16. Highly robust stainless steel tips as microelectrospray emitters.

    Science.gov (United States)

    Ishihama, Yasushi; Katayama, Hiroyuki; Asakawa, Naoki; Oda, Yoshiya

    2002-01-01

    Tapered stainless steel spray tips for sheathless microelectrospray ionization (microESI) have been developed. The fabrication procedure for the tapered stainless steel tips was optimized using an electropolishing technique followed by removal of the burr. Using the tip as the microESI emitter, a stable ESI spray was obtained at a flow rate of 20 nL/min. The sensitivity of the microESI system was almost two orders greater than that of the conventional ion spray system. The tip was highly stable, and was successfully used for over 1000 h. Moreover, these stainless steel tips were suitable for use with sheathless capillary electrophoresis/mass spectrometry (CE/MS) and capillary liquid chromatography/mass spectrometry (LC/MS) for routine analysis in proteomic and pharmaceutical applications. PMID:11968120

  17. High-efficient thermoemission electron source with emitter of lanthanum hexaboride

    Energy Technology Data Exchange (ETDEWEB)

    Iremashvili, D.V.; Sukhomlinov, V.V.; Ksenofontov, V.A.; Chanturidze, V.G.; Petrakov, V.E.; Avatinyan, G.A.

    1982-01-01

    A high-efficient thermoemission electron source with LaB/sub 6/ emitter and indirect heating is described. The design of cathode unit with 30 and 50 mm diameters of emitter is given. The technique for investigating the source operation is described. At high reliability of operation the cathode unit provides with approximately 2 kA current at approximately 2000 K working temperature of the emitter. Permissible time of heating is approximately 15 min. Operation life of the cathode unit is 500 h at 2000 K temperature of the emitter multiple depressurizing (> 100 times).

  18. High-Stakes Hustle: Public Schools and the New Billion Dollar Accountability

    Science.gov (United States)

    Baines, Lawrence A.; Stanley, Gregory Kent

    2004-01-01

    High-stakes testing costs up to $50 billion per annum, has no impact on student achievement, and has changed the focus of American public schools. This article analyzes the benefits and costs of the accountability movement, as well as discusses its roots in the eugenics movements of the early 20th century.

  19. Beam emittance investigation in high brightness injector using different driver laser profiles

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Beam emittance plays an important role in any accelerator, and it is a main parameter to judge the performance of an accelerator. Emittance optimization is an indispensable part in conditioning and operation of the facility. For a laser-driven high brightness injector, different time structure of the laser pulse has different effects on transverse emittance. In order to compare Gaussian and flat-top laser pulse, systematic simulations of 500 pC have been done. From the simulation results, one can see that flat-top pulse laser will yield smaller minimal transverse beam size and transverse beam emittance than Gaussian pulse laser.

  20. High Precision Measurement of Muon Beam Emittance Reduction in MICE

    CERN Document Server

    Rogers, Chris

    2005-01-01

    Muon ionization cooling, an essential ingredient of a neutrino factory, will be demonstrated for the first time by the MICE experiment. The central part of MICE consists of a short section of a neutrino factory cooling channel and the emittance reduction achieved in this experiment is quite modest, 10% to 15%. In order to extrapolate the performance of a full cooling channel from these values, it is crucial for MICE to achieve an emittance measurement accuracy of 10

  1. Improving Bilayer Product Quantization for Billion-Scale Approximate Nearest Neighbors in High Dimensions

    OpenAIRE

    Babenko, Artem; Lempitsky, Victor

    2014-01-01

    The top-performing systems for billion-scale high-dimensional approximate nearest neighbor (ANN) search are all based on two-layer architectures that include an indexing structure and a compressed datapoints layer. An indexing structure is crucial as it allows to avoid exhaustive search, while the lossy data compression is needed to fit the dataset into RAM. Several of the most successful systems use product quantization (PQ) for both the indexing and the dataset compression layers. These sys...

  2. Fast two-dimensional super-resolution image reconstruction algorithm for ultra-high emitter density.

    Science.gov (United States)

    Huang, Jiaqing; Gumpper, Kristyn; Chi, Yuejie; Sun, Mingzhai; Ma, Jianjie

    2015-07-01

    Single-molecule localization microscopy achieves sub-diffraction-limit resolution by localizing a sparse subset of stochastically activated emitters in each frame. Its temporal resolution is limited by the maximal emitter density that can be handled by the image reconstruction algorithms. Multiple algorithms have been developed to accurately locate the emitters even when they have significant overlaps. Currently, compressive-sensing-based algorithm (CSSTORM) achieves the highest emitter density. However, CSSTORM is extremely computationally expensive, which limits its practical application. Here, we develop a new algorithm (MempSTORM) based on two-dimensional spectrum analysis. With the same localization accuracy and recall rate, MempSTORM is 100 times faster than CSSTORM with ℓ(1)-homotopy. In addition, MempSTORM can be implemented on a GPU for parallelism, which can further increase its computational speed and make it possible for online super-resolution reconstruction of high-density emitters. PMID:26125349

  3. Emittance measurements of high current heavy ion beams using a single shot pepperpot system

    International Nuclear Information System (INIS)

    The new 1.4 MeV/u high current injector for the Unilac successfully commissioned in 1999 is now accelerating heavy ions close to the calculated intensities. For example an 40Ar1+ beam with 8 emA allows to fill the GSI synchrotron to its inherent intensity limit. For emittance measurements of such intense beams a single shot pepperpot system has been developed. An overview of the hard- and software including mathematical algorithms is given. Results of emittance measurements at different intensities and energies are presented. The influence of stripping and related space charge effects on the emittance could be investigated

  4. High emittance black nickel coating on copper substrate for space applications

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaram, Soniya, E-mail: jrf0013@isac.gov.in; Pillai, Anju M., E-mail: anjum@isac.gov.in; Rajendra, A., E-mail: rajendra@isac.gov.in; Sharma, A.K., E-mail: aks@isac.gov.in

    2015-09-15

    Highlights: • High emittance black nickel coating is obtained on copper substrate. • The effect of various process parameters on IR emittance is studied systematically. • Process parameters are optimized to develop a high emittance black nickel coating. • Coating obtained using the finalized parameters exhibited an emittance of 0.83. • SEM and EDAX are used for coating characterization. - Abstract: Black nickel, an alloy coating of zinc and nickel, is obtained on copper substrate by pulse electrodeposition from a modified Fishlock bath containing nickel sulphate, nickel ammonium sulphate, zinc sulphate and ammonium thiocyanate. A nickel undercoat of 4–5 μm thickness is obtained using Watts bath to increase the corrosion resistance and adhesion of the black nickel coating. The effect of bath composition, temperature, solution pH, current density and plating time on the coating appearance and corresponding infra-red emittance of the coating is investigated systematically. Process parameters are optimized to develop a high emittance space worthy black nickel coating to improve the heat radiation characteristics. The effect of the chemistry of the plating bath on the coating composition was studied using energy dispersive X-ray analysis (EDAX) of the coatings. The 5–6 μm thick uniform jet black zinc–nickel alloy coating obtained with optimized process exhibited an emittance of 0.83 and an absorbance of 0.92. The zinc to nickel ratio of black nickel coatings showing high emittance and appealing appearance was found to be in the range 2.3–2.4.

  5. High emittance black nickel coating on copper substrate for space applications

    International Nuclear Information System (INIS)

    Highlights: • High emittance black nickel coating is obtained on copper substrate. • The effect of various process parameters on IR emittance is studied systematically. • Process parameters are optimized to develop a high emittance black nickel coating. • Coating obtained using the finalized parameters exhibited an emittance of 0.83. • SEM and EDAX are used for coating characterization. - Abstract: Black nickel, an alloy coating of zinc and nickel, is obtained on copper substrate by pulse electrodeposition from a modified Fishlock bath containing nickel sulphate, nickel ammonium sulphate, zinc sulphate and ammonium thiocyanate. A nickel undercoat of 4–5 μm thickness is obtained using Watts bath to increase the corrosion resistance and adhesion of the black nickel coating. The effect of bath composition, temperature, solution pH, current density and plating time on the coating appearance and corresponding infra-red emittance of the coating is investigated systematically. Process parameters are optimized to develop a high emittance space worthy black nickel coating to improve the heat radiation characteristics. The effect of the chemistry of the plating bath on the coating composition was studied using energy dispersive X-ray analysis (EDAX) of the coatings. The 5–6 μm thick uniform jet black zinc–nickel alloy coating obtained with optimized process exhibited an emittance of 0.83 and an absorbance of 0.92. The zinc to nickel ratio of black nickel coatings showing high emittance and appealing appearance was found to be in the range 2.3–2.4

  6. Longitudinal emittance control in high intensity proton synchrotrons

    International Nuclear Information System (INIS)

    Experiments of synchrotron injection using the direct fast chopped H- beam extracted from a surface-plasma-type H- ion source has been successfully achieved. The injection phase of the fast chopped beam from linac into the booster synchrotron is adjustable to the center of rf bucket by using this beam. It was obtained that the longitudinal emittance was controlled at the extraction of the booster synchrotron, and that the beam loss during the injection into main ring of the KEK-PS was reduced by this fast chopped beam. (author)

  7. Field emission behavior of carbon nanotube field emitters after high temperature thermal annealing

    Directory of Open Access Journals (Sweden)

    Yuning Sun

    2014-07-01

    Full Text Available The carbon nanotube (CNT field emitters have been fabricated by attaching a CNT film on a graphite rod using graphite adhesive material. The CNT field emitters showed much improved field emission properties due to increasing crystallinity and decreasing defects in CNTs after the high temperature thermal annealing at 900 °C in vacuum ambient. The CNT field emitters showed the low turn-on electric field of 1.15 V/μm, the low threshold electric field of 1.62 V/μm, and the high emission current of 5.9 mA which corresponds to a current density of 8.5 A/cm2. In addition, the CNT field emitters indicated the enhanced field emission properties due to the multi-stage effect when the length of the graphite rod increases. The CNT field emitter showed good field emission stability after the high temperature thermal annealing. The CNT field emitter revealed a focused electron beam spot without any focusing electrodes and also showed good field emission repeatability.

  8. Demonstration of Cathode Emittance Dominated High Bunch Charge Beams in a DC gun-based Photoinjector

    CERN Document Server

    Gulliford, Colwyn; Bazarov, Ivan; Dunham, Bruce; Cultrera, Luca

    2015-01-01

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (greater than or equal to 100 pC) beams produced in the DC gun-based Cornell Energy Recovery Linac Photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittance measured at 9-9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs (ERLs) and Free Electron Lasers (FELs).

  9. Demonstration of cathode emittance dominated high bunch charge beams in a DC gun-based photoinjector

    International Nuclear Information System (INIS)

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (≥100 pC) beams produced in the DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittances measured at 9–9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs and Free Electron Lasers

  10. Performance and durability of high emittance heat receiver surfaces for solar dynamic power systems

    Science.gov (United States)

    Degroh, Kim K.; Roig, David M.; Burke, Christopher A.; Shah, Dilipkumar R.

    1994-01-01

    Haynes 188, a cobalt-based superalloy, will be used to make thermal energy storage (TES) containment canisters for a 2 kW solar dynamic ground test demonstrator (SD GTD). Haynes 188 containment canisters with a high thermal emittance (epsilon) are desired for radiating heat away from local hot spots, improving the heating distribution, which will in turn improve canister service life. In addition to needing a high emittance, the surface needs to be durable in an elevated temperature, high vacuum environment for an extended time period. Thirty-five Haynes 188 samples were exposed to 14 different types of surface modification techniques for emittance and vacuum heat treatment (VHT) durability enhancement evaluation. Optical properties were obtained for the modified surfaces. Emittance enhanced samples were exposed to VHT for up to 2692 hours at 827 C and less than or equal to 10(exp -6) torr with integral thermal cycling. Optical properties were taken intermittently during exposure, and after final VHT exposure. The various surface modification treatments increased the emittance of pristine Haynes 188 from 0.11 up to 0.86. Seven different surface modification techniques were found to provide surfaces which met the SD GTD receiver VHT durability requirement. Of the 7 surface treatments, 2 were found to display excellent VHT durability: an alumina based (AB) coating and a zirconia based coating. The alumina based coating was chosen for the epsilon enhancement surface modification technique for the SD GTD receiver. Details of the performance and vacuum heat treatment durability of this coating and other Haynes 188 emittance surface modification techniques are discussed. Technology from this program will lead to successful demonstration of solar dynamic power for space applications, and has potential for application in other systems requiring high emittance surfaces.

  11. Yichuan Power’s High-precision Aluminum Belt Project Invests RMB2.95 Billion

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>Yichuan Power Group’s continuous casting and rolling aluminum belt project features an annual production capacity of 250,000 tons and commenced construction in April 2009.Total investment in the project will be RMB2.95 billion, and following production,sales income are projected to reach RMB5.2 billion,with profits and taxes amounting to RMB0.6 billion.

  12. Highly flexible and robust N-doped SiC nanoneedle field emitters

    KAUST Repository

    Chen, Shanliang

    2015-01-23

    Flexible field emission (FE) emitters, whose unique advantages are lightweight and conformable, promise to enable a wide range of technologies, such as roll-up flexible FE displays, e-papers and flexible light-emitting diodes. In this work, we demonstrate for the first time highly flexible SiC field emitters with low turn-on fields and excellent emission stabilities. n-Type SiC nanoneedles with ultra-sharp tips and tailored N-doping levels were synthesized via a catalyst-assisted pyrolysis process on carbon fabrics by controlling the gas mixture and cooling rate. The turn-on field, threshold field and current emission fluctuation of SiC nanoneedle emitters with an N-doping level of 7.58 at.% are 1.11 V μm-1, 1.55 V μm-1 and 8.1%, respectively, suggesting the best overall performance for such flexible field emitters. Furthermore, characterization of the FE properties under repeated bending cycles and different bending states reveal that the SiC field emitters are mechanically and electrically robust with unprecedentedly high flexibility and stabilities. These findings underscore the importance of concurrent morphology and composition controls in nanomaterial synthesis and establish SiC nanoneedles as the most promising candidate for flexible FE applications. © 2015 Nature Publishing Group All rights reserved.

  13. Yucca Mountain, a high-level nuclear waste repository over a billion barrel oil field?

    International Nuclear Information System (INIS)

    New structural models and source rock data suggest that the proposed Yucca Mountain, Nevada, high-level nuclear waste repository lies in the Central Nevada thrust belt. The Central Nevada thrust belt could contain billion-barrel oil fields. The Central Nevada thrust belt coincides with an organic richness fairway and a maturation fairway of Mississippian source rocks that have already produced more than 25 million barrels of oil. Giant thrust-related structures along the thrust belt have yet to be tested. However, new work in the Tempahute Range, which lies between Yucca Mountain and the prolific Grant Canyon field, confirms the thrust belt concept and sheds light on source and reservoir rock quality and thrust belt geometry. Klippen of overmature Mississippian rocks are distinct on maturation maps such as the Diamond Range klippe in central Nevada. Thrust trends suggest that the Eleana Range near Yucca Mountain may be another klippe of overmature rocks over Mississippian source rocks in the oil window. There is a strong possibility that the subthrust source rocks may have generated large quantities of hydrocarbons that may be trapped in large thrust features beneath Yucca Mountain

  14. High Turndown Ratio, High Delta-Emittance, Variable Emissivity Electrochromics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Among thermal control methods, variable-emittance materials remain the most promising for addressing deficiencies of current systems (mechanical louvers, loop heat...

  15. Highly reliable field electron emitters produced from reproducible damage-free carbon nanotube composite pastes with optimal inorganic fillers

    International Nuclear Information System (INIS)

    Highly reliable field electron emitters were developed using a formulation for reproducible damage-free carbon nanotube (CNT) composite pastes with optimal inorganic fillers and a ball-milling method. We carefully controlled the ball-milling sequence and time to avoid any damage to the CNTs, which incorporated fillers that were fully dispersed as paste constituents. The field electron emitters fabricated by printing the CNT pastes were found to exhibit almost perfect adhesion of the CNT emitters to the cathode, along with good uniformity and reproducibility. A high field enhancement factor of around 10 000 was achieved from the CNT field emitters developed. By selecting nano-sized metal alloys and oxides and using the same formulation sequence, we also developed reliable field emitters that could survive high-temperature post processing. These field emitters had high durability to post vacuum annealing at 950 °C, guaranteeing survival of the brazing process used in the sealing of field emission x-ray tubes. We evaluated the field emitters in a triode configuration in the harsh environment of a tiny vacuum-sealed vessel and observed very reliable operation for 30 h at a high current density of 350 mA cm−2. The CNT pastes and related field emitters that were developed could be usefully applied in reliable field emission devices. (paper)

  16. High performance CNT point emitter with graphene interfacial layer

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) have great potential in the development of high-power electron beam sources. However, for such a high-performance electronic device, the electric and thermal contact problem between the metal and CNTs must be improved. Here, we report graphene as an interfacial layer between the metal and CNTs to improve the interfacial contact. The interfacial graphene layer results in a dramatic decrease of the electrical contact resistance by an order of 2 and an increase of the interfacial thermal conductivity by 16%. Such a high improvement in the electrical and thermal interface leads to superior field emission performance with a very low turn-on field of 1.49 V μm−1 at 10 μA cm−2 and a threshold field of 2.00 V μm−1 at 10 mA cm−2, as well as the maximum current of 16 mA (current density of 2300 A cm−2). (paper)

  17. Laser acceleration of low emittance, high energy ions and applications

    Science.gov (United States)

    Fuchs, Julien; Audebert, Patrick; Borghesi, Marco; Pépin, Henri; Willi, Oswald

    2009-03-01

    Laser-accelerated ion sources have exceptional properties, i.e. high brightness and high spectral cut-off (56 MeV at present), high directionality and laminarity (at least 100-fold better than conventional accelerators beams), short burst duration (ps). Thanks to these properties, these sources open new opportunities for applications. Among these, we have already explored their use for proton radiography of fields in plasmas and for warm dense matter generation. These sources could also stimulate development of compact ion accelerators or be used for medical applications. To extend the range of applications, ion energy and conversion efficiency must however be increased. Two strategies for doing so using present-day lasers have been successfully explored in LULI experiments. In view of applications, it is also essential to control (i.e. collimate and energy select) these beams. For this purpose, we have developed an ultra-fast laser-triggered micro-lens providing tuneable control of the beam divergence as well as energy selection. To cite this article: J. Fuchs et al., C. R. Physique 10 (2009).

  18. High gradient quadrupoles for low emittance storage rings

    Science.gov (United States)

    Le Bec, G.; Chavanne, J.; Benabderrahmane, C.; Farvacque, L.; Goirand, L.; Liuzzo, S.; Raimondi, P.; Villar, F.

    2016-05-01

    High gradient quadrupoles are key components for the coming generation of storage ring based light sources. The typical specifications of these magnets are: almost 100 T /m gradient, half a meter long, and a vertical aperture for the extraction of the x-ray beam. This paper presents the preparation work done at the European Synchrotron Radiation Facility, from the design to the manufacture and measurements of a prototype. It demonstrates the feasibility of such magnets. Different aspects of magnet engineering are discussed, including the study of the main scale factors and the preliminary design, the pole shaping, the impact of mechanical errors, and the magnetic measurements of a prototype with a stretched-wire system.

  19. High Temperature Superconducting Terahertz Emitters with Various Mesa Structures

    Science.gov (United States)

    Delfanazari, Kaveh; Tsujimoto, M.; Kashiwagi, T.; Asai, H.; Kitamura, T.; Yamamoto, T.; Sawamura, M.; Ishida, K.; Watanabe, C.; Sekimoto, S.; Minami, H.; Tachiki, M.; Hattori, T.; Klemm, R. A.; Kadowaki, K.

    2013-03-01

    In 2007, the first observation of the coherent terahertz (THz) electromagnetic (EM) waves from a mesa structures of intrinsic Josephson junctions (IJJs) in high temperature superconductor Bi2Sr2CaCu2O8+δ (Bi-2212) is reported. The ac-Josephson effect as well as the cavity resonance conditions is considered as the principle mechanism of the THz radiation. In order to understand the cavity effect in THz radiation from IJJ mesas more clearly, we studied mesas with various geometries; various kinds of triangles, and pentagonal mesas with various sizes and thicknesses. The focused ion beam (FIB) milling technique is used in all mesa fabrications. In this talk, we discuss our recent progress in THz emission observation in pentagonal mesas. This work has been supported in part by CREST-JST (Japan Science and Technology Agency), WPI-MANA project (NIMS).

  20. High-density metallic nano-emitter arrays and their field emission characteristics

    International Nuclear Information System (INIS)

    We report the fabrication and field emission properties of high-density nano-emitter arrays with on-chip electron extraction gate electrodes and up to 106 metallic nanotips that have an apex curvature radius of a few nanometers and a the tip density exceeding 108 cm−2. The gate electrode was fabricated on top of the nano-emitter arrays using a self-aligned polymer mask method. By applying a hot-press step for the polymer planarization, gate–nanotip alignment precision below 10 nm was achieved. Fabricated devices exhibited stable field electron emission with a current density of 0.1 A cm−2, indicating that these are promising for applications that require a miniature high-brightness electron source. (paper)

  1. Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Yoshimasa; Kubo, Shosei; Suzuki, Katsuaki; Kaji, Hironori, E-mail: kaji@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Shizu, Katsuyuki [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Tanaka, Hiroyuki [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Japan Science and Technology Agency (JST), ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2015-11-02

    We developed a thermally activated delayed fluorescence (TADF) emitter, 2,4,6-tris(4-(9,9-dimethylacridan-10-yl)phenyl)-1,3,5-triazine (3ACR-TRZ), suitable for use in solution-processed organic light-emitting diodes (OLEDs). When doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host at 16 wt. %, 3ACR-TRZ showed a high photoluminescence quantum yield of 98%. Transient photoluminescence decay measurements of the 16 wt. % 3ACR-TRZ:CBP film confirmed that 3ACR-TRZ exhibits efficient TADF with a triplet-to-light conversion efficiency of 96%. This high conversion efficiency makes 3ACR-TRZ attractive as an emitting dopant in OLEDs. Using 3ACR-TRZ as an emitter, we fabricated a solution-processed OLED exhibiting a maximum external quantum efficiency of 18.6%.

  2. Effect of very high magnetic field on the optical properties of firefly light emitter oxyluciferin

    International Nuclear Information System (INIS)

    Magnetic field effect on enzymatic reactions is under intensive study in the past decades. Recently, it was reported that firefly bioluminescence was suppressed and red-shifted significantly when exposed to external magnetic field. However in this work, by means of selective excitation, we confirmed that emission properties of firefly light emitter “oxyluciferin” are completely immune to external magnetic field of up to 53 T. These findings pose strong contrast to existing relevant results. Potential reasons for the discrepancies found and the underlying physics towards the understanding of firefly bioluminescence were discussed. - Highlights: • Effect of ultra-high magnetic field on the optical properties of firefly light emitter oxyluciferin was reported. • Emission properties of oxyluciferin were confirmed to be immune to external high magnetic fields up to 53 T. • .Potential reasons for the discrepancies between our results and previous reports and the underlying physics were discussed

  3. Effect of very high magnetic field on the optical properties of firefly light emitter oxyluciferin

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Weihang; Nakamura, Daisuke [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Wang, Yu [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (China); Mochizuki, Toshimitsu [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Fukushima Renewable Energy Institute, National Institute of Advanced Industrial Science and Technology, 2-2-9 Machiike-dai, Koriyama, Fukushima 963-0215 (Japan); Akiyama, Hidefumi [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Takeyama, Shojiro, E-mail: takeyama@issp.u-tokyo.ac.jp [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2015-09-15

    Magnetic field effect on enzymatic reactions is under intensive study in the past decades. Recently, it was reported that firefly bioluminescence was suppressed and red-shifted significantly when exposed to external magnetic field. However in this work, by means of selective excitation, we confirmed that emission properties of firefly light emitter “oxyluciferin” are completely immune to external magnetic field of up to 53 T. These findings pose strong contrast to existing relevant results. Potential reasons for the discrepancies found and the underlying physics towards the understanding of firefly bioluminescence were discussed. - Highlights: • Effect of ultra-high magnetic field on the optical properties of firefly light emitter oxyluciferin was reported. • Emission properties of oxyluciferin were confirmed to be immune to external high magnetic fields up to 53 T. • .Potential reasons for the discrepancies between our results and previous reports and the underlying physics were discussed.

  4. Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter

    International Nuclear Information System (INIS)

    We developed a thermally activated delayed fluorescence (TADF) emitter, 2,4,6-tris(4-(9,9-dimethylacridan-10-yl)phenyl)-1,3,5-triazine (3ACR-TRZ), suitable for use in solution-processed organic light-emitting diodes (OLEDs). When doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host at 16 wt. %, 3ACR-TRZ showed a high photoluminescence quantum yield of 98%. Transient photoluminescence decay measurements of the 16 wt. % 3ACR-TRZ:CBP film confirmed that 3ACR-TRZ exhibits efficient TADF with a triplet-to-light conversion efficiency of 96%. This high conversion efficiency makes 3ACR-TRZ attractive as an emitting dopant in OLEDs. Using 3ACR-TRZ as an emitter, we fabricated a solution-processed OLED exhibiting a maximum external quantum efficiency of 18.6%

  5. Long-lived and highly efficient green and blue phosphorescent emitters and device architectures for OLED displays

    Science.gov (United States)

    Eickhoff, Christian; Murer, Peter; Geßner, Thomas; Birnstock, Jan; Kröger, Michael; Choi, Zungsun; Watanabe, Soichi; May, Falk; Lennartz, Christian; Stengel, Ilona; Münster, Ingo; Kahle, Klaus; Wagenblast, Gerhard; Mangold, Hannah

    2015-09-01

    In this paper, two OLED device concepts are introduced. First, classical phosphorescent green carbene emitters with unsurpassed lifetime, combined with low voltage and high efficiency are presented and the associated optimized OLED stacks are explained. Second, a path towards highly efficient, long-lived deep blue systems is shown. The high efficiencies can be reached by having the charge-recombination on the phosphorescent carbene emitter while at the same time short emissive lifetimes are realized by fast energy transfer to the fluorescent emitter, which eventually allows for higher OLED stability in the deep blue. Device architectures, materials and performance data are presented showing that carbene type emitters have the potential to outperform established phosphorescent green emitters both in terms of lifetime and efficiency. The specific class of green emitters under investigation shows distinctly larger electron affinities (2.1 to 2.5 eV) and ionization potentials (5.6 to 5.8 eV) as compared to the "standard" emitter Ir(ppy)3 (5.0/1.6 eV). This difference in energy levels requires an adopted OLED design, in particular with respect to emitter hosts and blocking layers. Consequently, in the diode setup presented here, the emitter species is electron transporting or electron trapping. For said green carbene emitters, the typical peak wavelength is 525 nm yielding CIE color coordinates of (x = 0.33, y = 0.62). Device data of green OLEDs are shown with EQEs of 26 %. Driving voltage at 1000 cd/m2 is below 3 V. In an optimized stack, a device lifetime of LT95 > 15,000 h (1000 cd/m2) has been reached, thus fulfilling AMOLED display requirements.

  6. Preventing Inductive Output Impedance of High-Frequency Emitter Follower Stages

    OpenAIRE

    Tozer, R. C.; J. Nerad

    1997-01-01

    Large output inductance is one of major issues of high-frequency emitter follower design. The most often suggested technique to reduce its value is the decreasing of AC transconductance which offers small output inductance at the expense of loosing low output resistance. The paper presents a different approach; it is shown that output inductance can be completely cancelled while keeping very low output resistance by introducing a pole at the input node which may be more suitable in many types...

  7. Design of a low emittance and high repetition rate S-band photoinjector

    Science.gov (United States)

    Han, Jang-Hui

    2014-09-01

    As an electron beam injector of X-ray free-electron lasers (FELs), photoinjectors have been developed for the past few decades. Such an injector starting with a photocathode RF gun provides high brightness beams and therefore it is being adopted as an injector of X-ray FELs. In this paper we show how to improve photoinjector performance in terms of emittance and repetition rates by means of injector components optimization, especially with the gun. Transverse emittance at the end of an injector is reduced by optimizing the gun design, gun solenoid position, and accelerating section position. The repetition rate of an injector mainly depends on the gun. It is discussed that a repetition rate of 1 kHz at a normal-conducting S-band photoinjector is feasible by adopting a coaxial RF coupler and improving cooling-water channels surrounding the gun.

  8. Studies of emittance of multiply charged ions extracted from high temperature superconducting electron cyclotron resonance ion source, PKDELIS

    International Nuclear Information System (INIS)

    For the high current injector project at Inter University Accelerator Centre, a high temperature superconducting electron cyclotron resonance (ECR) ion source, PKDELIS, would provide the high charge state ions. The emittance of the ECR ion source is an important parameter to design further beam transport system and to match the acceptances of the downstream radio frequency quadrupole and drift tube linac accelerators of the high current injector. The emittance of the analyzed beam of PKDELIS ECR source has been measured utilizing the three beam size technique. A slit and two beam profile monitors positioned at fixed distances from each other were used to measure the beam size. The digitized beam profiles have been analyzed to determine the emittance of various multiply charged ions. The variation of emittance with gas mixing, ultrahigh frequency power, and extraction energy are discussed in this presentation.

  9. Overview of laserwire beam profile and emittance measurements for high power proton accelerators

    CERN Document Server

    Gibson, S M; Bosco, A; Gabor, C; Pozimski, J; Savage, P; Hofmann, T

    2013-01-01

    Laserwires were originally developed to measure micron-sized electron beams via Compton scattering, where traditional wire scanners are at the limit of their resolution. Laserwires have since been applied to larger beamsize, high power H$^-$ ion beams, where the non-invasive method can probe beam densities that would damage traditional diagnostics. While photo-detachment of H$^-$ ions is now routine to measure beam profiles, extending the technique to transverse and longitudinal emittance measurements is a key aim of the laserwire emittance scanner under construction at the Front End Test Stand (FETS) at the RAL. A pulsed, 30 kHz, 8kW peak power laser is fibrecoupled to motorized collimating optics, which controls the position and thickness of the laserwire delivered to the H- interaction chamber. The laserwire slices out a beamlet of neutralized particles, which propagate to a downstream scintillator and camera. The emittance is reconstructed from 2D images as the laserwire position is scanned. Results from ...

  10. A new method for the estimation of high temperature radiant heat emittance by means of aero-acoustic levitation

    Science.gov (United States)

    Greffrath, Fabian; Prieler, Robert; Telle, Rainer

    2014-11-01

    A new method for the experimental estimation of radiant heat emittance at high temperatures has been developed which involves aero-acoustic levitation of samples, laser heating and contactless temperature measurement. Radiant heat emittance values are determined from the time dependent development of the sample temperature which requires analysis of both the radiant and convective heat transfer towards the surroundings by means of fluid dynamics calculations. First results for the emittance of a corundum sample obtained with this method are presented in this article and found in good agreement with literature values.

  11. High-throughput realization of an infrared selective absorber/emitter by DUV microsphere projection lithography

    Science.gov (United States)

    Bonakdar, Alireza; Rezaei, Mohsen; Dexheimer, Eric; Mohseni, Hooman

    2016-01-01

    In this paper, we present a low-cost and high-throughput nanofabrication method to realize metasurfaces that have selective absorption/emission in the mid-infrared region of the electromagnetic spectrum. We have developed DUV projection lithography to produce arbitrary patterns with sub-80 nm feature sizes. As examples of practical applications, we experimentally demonstrate structures with single and double spectral absorption/emission features, and in close agreement with numerical simulation. The fundamental mechanism of perfect absorption is discussed as well. Selective infrared absorbers/emitters are critical elements in realizing efficient thermophotovoltaic cells and high-performance biosensors.

  12. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

    Science.gov (United States)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1993-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

  13. InGaN micro-LED-pillar as the building block for high brightness emitters

    KAUST Repository

    Shen, Chao

    2013-01-01

    In summary, we confirmed the improved electrical and optical characteristics, with reduced efficiency droop in InGaN μLED-pillars when these devices were scaled down in size. We demonstrated that strain relief contributed to further improvement in EQE characteristics in small InGaN μLED-pillars (D < 50 μm), apart from the current spreading effect. The μLED-pillar can be deployed as the building block for large effective-area, high brightness emitter. © 2013 IEEE.

  14. Preventing Inductive Output Impedance of High-Frequency Emitter Follower Stages

    Directory of Open Access Journals (Sweden)

    R. C. Tozer

    1997-04-01

    Full Text Available Large output inductance is one of major issues of high-frequency emitter follower design. The most often suggested technique to reduce its value is the decreasing of AC transconductance which offers small output inductance at the expense of loosing low output resistance. The paper presents a different approach; it is shown that output inductance can be completely cancelled while keeping very low output resistance by introducing a pole at the input node which may be more suitable in many types of design. Complete analytical evaluation based on the full hybrid-n model of the bipolar transistor device is given.

  15. HIGH AVERAGE CURRENT LOW EMITTANCE BEAM EMPLOYING CW NORMAL CONDUCTING GUN.

    Energy Technology Data Exchange (ETDEWEB)

    CHANG,X.; BEN-ZVI, I.; KEWISCH, J.; PAI, C.

    2007-06-25

    CW normal conducting guns usually do not achieve very high field gradient and waste much RF power at high field gradient compared to superconducting cavities. But they have less trapped modes and wakefields compared to the superconducting cavities due to their low Q. The external bucking coil can also be applied very close to the cathode to improve the beam quality. By using a low frequency gun with a recessed cathode and a carefully designed beam line we can get a high average current and a high quality beam with acceptable RF power loss on the cavity wall. This paper shows that the CW normal conducting gun can be a backup solution for those projects which need high peak and average current, low emittance electron beams such as the Relativistic Heavy Ion Collider (RHIC) e-cooling project and Energy Recovery Linac (Em) project.

  16. Narrow-band surveys for very high redshift Lyman-α emitters

    Science.gov (United States)

    Nilsson, K. K.; Orsi, A.; Lacey, C. G.; Baugh, C. M.; Thommes, E.

    2007-11-01

    Context: Many current and future surveys aim to detect the highest redshift (z ⪆ 7) sources through their Lyman-α (Lyα) emission, using the narrow-band imaging method. However, to date the surveys have only yielded non-detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies. Aims: We aim to calculate model luminosity functions and mock surveys of Lyα emitters at z ⪆ 7 based on a variety of approaches calibrated and tested on observational data at lower redshifts. Methods: We calculate model luminosity functions at different redshifts based on three different approaches: a semi-analytical model based on CDM, a simple phenomenological model, and an extrapolation of observed Schechter functions at lower redshifts. The results of the first two models are compared with observations made at redshifts z ˜ 5.7 and z ˜ 6.5, and they are then extrapolated to higher redshift. Results: We present model luminosity functions for redshifts between z = 7{-}12.5 and give specific number predictions for future planned or possible narrow-band surveys for Lyα emitters. We also investigate what constraints future observations will be able to place on the Lyα luminosity function at very high redshift. Conclusions: It should be possible to observe z = 7{-}10 Lyα emitters with present or near-future instruments if enough observing time is allocated. In particular, large area surveys such as ELVIS (Emission Line galaxies with VISTA Survey) will be useful in collecting a large sample. However, to get a large enough sample to constrain well the z ≥ 10 Lyα luminosity function, instruments further in the future, such as an ELT, will be necessary.

  17. A sweep plate emittance scanner for high-power CW ion beams

    International Nuclear Information System (INIS)

    Sweep plate scanners are preferred for emittance measurement due to their versatility, simplicity, and precision. At the Advanced Technology and Development Center of Northrop Grumman, we have routinely used these devices for characterization of injector beams with less than 20 W/cm2 average power density. To characterize higher power beams, like those required for production of tritium or for radioactive waste transmutation, the scanner pod and data collection algorithm must be redesigned due to the possibility of melting the scanner's protective front face or distorting the precision entrance knife edges. Among the methods we have used to mitigate these effects, one consists of drastically reducing the amount of time required for data collection. In this method, the emittance scanner pod traverses the beam in two passes, each requiring less than 0.5 second. In the first pass, the phase space limits of the beam are determined. In the second pass, data is collected primarily within the phase space region limits determined in the first pass. In this way, enough points are collected to assure that the precision of the measurement is high, even though the data collection time for each scan is less than 0.5 second. This paper will describe the layout of the scanner components, the data collection electronics and algorithm, and the data analysis. (author)

  18. Formation of compressed flat electron beams with high transverse-emittance ratios

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Fermilab; Institute of Fluid Physics, CAEP, China; Piot, P. [Northern Illinois University; Fermilab; Mihalcea, D. [Northern Illinois University; Prokop, C. R. [Northern Illinois University

    2014-08-01

    Flat beams—beams with asymmetric transverse emittances—have important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilab’s Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ~37 MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25 μm (emittance ratio is ~400), 0.13 μm, 15 nm before compression, and 0.41 μm, 0.20 μm, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2-nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  19. Advances In Vertical Solid-State Current Limiters For Individual Field Emitter Regulation In High-Density Arrays

    Science.gov (United States)

    Hill, Frances A.; Velásquez-García, Luis F.

    2015-12-01

    We report the design, fabrication, and characterization of improved solid-state elements intended for individual regulation of field emitters part of high-density arrays. We demonstrate a high-yield, CMOS compatible fabrication process of single-crystal, vertical, ungated, n-type silicon field-effect transistors (FETs); each device behaves as a current source when is biased at a voltage larger than its drain-source saturation voltage. An ungated FET in saturation connected in series to a field emitter can compensate for the wide variation in current-voltage characteristics of the field emitters due to the tip radii spread present in any field emitter array, which should result in emitter burn-out protection, larger array utilization, and smaller array emission non-uniformity. Using 1-2 Ωcm single-crystal n-Si wafers, we fabricated arrays of 25 μm tall vertical ungated FETs with 0.5 μm diameter that span two orders of magnitude of array size. Experimental characterization of the arrays demonstrates that the current is limited with > 3.5 V bias voltage to the same ∼6 μA (6 A.cm-2) per-FET value. Finite element simulations of the device predict a saturation voltage close to the experimental value and a saturation current within a factor of two of the experimental value.

  20. Effect of the electrostatic plasma lens on the emittance of a high-current heavy ion beam

    International Nuclear Information System (INIS)

    We describe measurements we have made of the emittance of a high-current, moderate-energy ion beam after transport through a permanent-magnet electrostatic plasma lens. The results indicate the absence of emittance growth due to the lens, when the lens is adjusted for optimal beam focusing. The measured emittance for a 16 keV Cu2+ ion beam formed by a vacuum arc ion source was about 0.4 π · mm · mrad at a beam current of 50 mA rising more-or-less linearly to 1.5 π · mm · mrad at 250 mA, and was conserved in beam transport through the lens. These results have significance for the application of high-current ion sources and the electrostatic plasma lens to particle accelerator injection

  1. Plume-based analysis of vehicle fleet air pollutant emissions and the contribution from high emitters

    Science.gov (United States)

    Wang, J. M.; Jeong, C.-H.; Zimmerman, N.; Healy, R. M.; Wang, D. K.; Ke, F.; Evans, G. J.

    2015-08-01

    An automated identification and integration method has been developed for in-use vehicle emissions under real-world conditions. This technique was applied to high-time-resolution air pollutant measurements of in-use vehicle emissions performed under real-world conditions at a near-road monitoring station in Toronto, Canada, during four seasons, through month-long campaigns in 2013-2014. Based on carbon dioxide measurements, over 100 000 vehicle-related plumes were automatically identified and fuel-based emission factors for nitrogen oxides; carbon monoxide; particle number; black carbon; benzene, toluene, ethylbenzene, and xylenes (BTEX); and methanol were determined for each plume. Thus the automated identification enabled the measurement of an unprecedented number of plumes and pollutants over an extended duration. Emission factors for volatile organic compounds were also measured roadside for the first time using a proton transfer reaction time-of-flight mass spectrometer; this instrument provided the time resolution required for the plume capture technique. Mean emission factors were characteristic of the light-duty gasoline-dominated vehicle fleet present at the measurement site, with mean black carbon and particle number emission factors of 35 mg kg fuel-1 and 7.5 × 1014 # kg fuel-1, respectively. The use of the plume-by-plume analysis enabled isolation of vehicle emissions, and the elucidation of co-emitted pollutants from similar vehicle types, variability of emissions across the fleet, and the relative contribution from heavy emitters. It was found that a small proportion of the fleet (fleet emissions: 100, 100, 81, and 77 % for black carbon, carbon monoxide, BTEX, and particle number, respectively. Emission factors of a single pollutant may help classify a vehicle as a high emitter; however, regulatory strategies to more efficiently target multi-pollutant mixtures may be better developed by considering the co-emitted pollutants as well.

  2. Plume-based analysis of vehicle fleet air pollutant emissions and the contribution from high emitters

    Directory of Open Access Journals (Sweden)

    J. M. Wang

    2015-03-01

    Full Text Available An automated identification and integration method has been developed to investigate in-use vehicle emissions under real-world conditions. This technique was applied to high time resolution air pollutant measurements of in-use vehicle emissions performed under real-world conditions at a near-road monitoring station in Toronto, Canada during four seasons, through month-long campaigns in 2013–2014. Based on carbon dioxide measurements, over 100 000 vehicle-related plumes were automatically identified and fuel-based emission factors for nitrogen oxides; carbon monoxide; particle number, black carbon; benzene, toluene, ethylbenzene, and xylenes (BTEX; and methanol were determined for each plume. Thus the automated identification enabled the measurement of an unprecedented number of plumes and pollutants over an extended duration. Emission factors for volatile organic compounds were also measured roadside for the first time using a proton transfer reaction time-of-flight mass spectrometer; this instrument provided the time resolution required for the plume capture technique. Mean emission factors were characteristic of the light-duty gasoline dominated vehicle fleet present at the measurement site, with mean black carbon and particle number emission factors of 35 mg kg−1 and 7.7 × 1014 kg−1, respectively. The use of the plume-by-plume analysis enabled isolation of vehicle emissions, and the elucidation of co-emitted pollutants from similar vehicle types, variability of emissions across the fleet, and the relative contribution from heavy emitters. It was found that a small proportion of the fleet (< 25% contributed significantly to total fleet emissions; 95, 93, 76, and 75% for black carbon, carbon monoxide, BTEX, and particle number, respectively. Emission factors of a single pollutant may help classify a vehicle as a high emitter. However, regulatory strategies to more efficiently target multi-pollutants mixtures may be better developed by

  3. Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

    Science.gov (United States)

    Baudrenghien, P.; Mastoridis, T.

    2015-10-01

    The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of β* to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

  4. Space-charged-induced emittance growth in the transport of high-brightness electron beams

    International Nuclear Information System (INIS)

    The emittance induced by space charge in a drifting beam of finite length has been investigated, and a scaling law has been obtained from simple considerations of the different rates of expansion of different portions of the beam. The scaling law predicts the initial rate of emittance growth, before the beam shape has distorted significantly, and thus represents an upper bound on the rate of emittance increase. This scaling law has been substantiated by particle-in-cell simulation and the dependence on geometric factors evaluated for specific choices of the beam profile. For long, axially nonuniform beams, the geometric factors have been evaluated explicitly for Gaussian profiles, and other shapes

  5. Design of a high duty cycle, asymmetric emittance RF photocathode injector for linear collider applications

    International Nuclear Information System (INIS)

    One of the attractive features of the superconducting approach to linear collider design is that the transverse emittances demanded are much larger than in normal conducting schemes. For TESLA design parameters, the damping rings appear to be relatively large and expensive, and it is therefore of some interest to look into alternative sources. For electrons, a promising source candidate is an rf photocathode. In this paper, the authors present conceptual design work towards development of an asymmetric emittance rf photocathode source which can operate at the TESLA repetition rates and duty cycle, and is capable of emitting beams with the required emittances and charge per pulse

  6. Thin-film ‘Thermal Well’ Emitters and Absorbers for High-Efficiency Thermophotovoltaics

    OpenAIRE

    Tong, Jonathan K.; Hsu, Wei-Chun; Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2015-01-01

    A new approach is introduced to significantly improve the performance of thermophotovoltaic (TPV) systems using low-dimensional thermal emitters and photovoltaic (PV) cells. By reducing the thickness of both the emitter and the PV cell, strong spectral selectivity in thermal emission and absorption can be achieved by confining photons in trapped waveguide modes inside the thin-films that act as thermal analogs to quantum wells. Simultaneously, photo-excited carriers travel shorter distances a...

  7. Design and test of a new facility for assessing spectral normal emittance of solid materials at high temperature

    Science.gov (United States)

    Mercatelli, L.; Meucci, M.; Sani, E.

    2016-02-01

    The measurement of spectral emittance is a key topic in the study of new compositions, depositions and mechanical machining of materials for solar absorption and for renewable energies. In this work we report on the realization and testing of a new experimental facility for the measurement of directional spectral emittance which provides emittance spectral information in a controlled environment at medium-high temperatures up to 1300 K. The device is composed by a vacuum chamber with electrical heater optically connected with a visible and an FT-IR spectrometer. A split mirror permits to calibrate the system as it directs toward the detector the signal deriving from a calibrated blackbody. A ZnSe window allows to measure normal radiance in 0.6-17 μm spectral range. In this device the first test were carried out comparing the results obtained for HfC and TaB2 ultra-refractory ceramic samples to previous monochromatic measurements performed in a research solar furnace, obtaining a good agreement. Then, in order to confirm the reliability of the acquired spectral emittance curve, we compared it to that calculated from the room temperature spectrum in 2.5-17 μm spectral range, showing a similar spectral trend.

  8. Statistical model for field emitter activation on metallic surfaces used in high-gradient accelerating structures

    Science.gov (United States)

    Lagotzky, S.; Müller, G.

    2016-01-01

    Both super- and normal-conducting high-gradient linear accelerators are limited by enhanced field emission (EFE) in the accelerating structures, e.g. due to power loss or ignition of discharges. We discuss the dependence of the number density of typical emitters, i.e. particulates and surface defects, on the electric field level at which they are activated for naturally oxidized metallic surfaces. This activation is explained by the transition of a metal-insulator interface into geometric features that enhance the EFE process. A statistical model is successfully compared to systematic studies of niobium and copper relevant for recent and future linear accelerators. Our results show that the achievable surface quality of Nb might be sufficient for the suppression of EFE in the superconducting accelerating structures for the actual European XFEL but not for the planned International Linear Collider. Moreover, some effort will be required to reduce EFE and thus the breakdown rate of the normal conducting Cu structures for the Compact Linear Collider.

  9. Acceleration of Ultra-Low Emittance Proton and Ion Beams with High Intensity Lasers

    Science.gov (United States)

    Cowan, Thomas E.

    2002-11-01

    Intense beams of several MeV protons and ions, generated by the interaction of high-intensity short pulse lasers with thin foils, have been observed by many researchers in recent years.(S.P. Hatchett et al., Phys. Plasmas 7, 2076 (2000); T.E. Cowan et al., Nucl. Inst. Meth. A 455, 130 (2000); R.A. Snavely et al., Phys. Rev. Lett. 85, 2945 (2000); S.C. Wilks et al., Phys. Plasmas 8, 532 (2000); E. Clark et al., Phys. Rev. Lett. 84, 670 (2000).) In experiments performed at the 100 TW LULI laser, we have succeeded to control the ion acceleration process to produce ultra high quality proton beams, whose transverse emittance is laser-plasma interaction, of the transport of MA currents of relativistic electrons through the target substrate, and of the surface topology and source material layering on the target foil rear-surface.(M. Roth et al., Phys. Rev. ST Accel. Beams 5, 061002 (2002).) By varying the source material, we also accelerated light ion beams, such as He-like fluorine, to over 5 MeV/nucleon.(M. Hegelich et al., Phys. Rev. Lett. 89, 085002 (2002).) From PIC simulations we understand the highest-energy and lowest-divergence proton acceleration as a transient laser-driven virtual cathode effect occurring at the target rear-surface. We have also confirmed the acceleration of ions from the front surface (A. Maksimchuk et al., Phys. Rev. Lett. 84, 4108 (2000).), which we find exhibits an intense low-energy component, but only a tenuous high-energy component, in agreement with PIC simulations. This work was performed with corporate support of General Atomics.

  10. The artificial control of enhanced optical processes in fluorescent molecules on high-emittance metasurfaces.

    Science.gov (United States)

    Iwanaga, Masanobu; Choi, Bongseok; Miyazaki, Hideki T; Sugimoto, Yoshimasa

    2016-06-01

    Plasmon-enhanced optical processes in molecules have been extensively but individually explored for Raman scattering, fluorescence, and infrared light absorption. In contrast to recent progress in the interfacial control of hot electrons in plasmon-semiconductor hybrid systems, plasmon-molecule hybrid systems have remained to be a conventional scheme, mainly assuming electric-field enhancement. This was because it was difficult to control the plasmon-molecule interface in a well-controlled manner. We here experimentally substantiate an obvious change in artificially enhanced optical processes of fluorescence/Raman scattering in fluorescent molecules on high-emittance plasmo-photonic metasurfaces with/without a self-assembled monolayer of sub-nm thickness. These results indicate that the enhanced optical processes were successfully selected under artificial configurations without any additional chemical treatment that modifies the molecules themselves. Although Raman-scattering efficiency is generally weak in high-fluorescence-yield molecules, it was found that Raman scattering becomes prominent around the molecular fingerprint range on the metasurfaces, being enhanced by more than 2000 fold at the maximum for reference signals. In addition, the highly and uniformly enhancing metasurfaces are able to serve as two-way functional, reproducible, and wavelength-tunable platforms to detect molecules at very low densities, being distinct from other platforms reported so far. The change in the enhanced signals suggests that energy diagrams in fluorescent molecules are changed in the configuration that includes the metal-molecule interface, meaning that plasmon-molecule hybrid systems are rich in the phenomena beyond the conventional scheme. PMID:27227964

  11. Planar field emitters and high efficiency photocathodes based on ultrananocrystalline diamond

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Baryshev, Sergey V.; Antipov, Sergey P.

    2016-08-16

    A method of forming a field emitter comprises disposing a first layer on a substrate. The first layer is seeded with nanodiamond particles. The substrate with the first layer disposed thereon is maintained at a first temperature and a first pressure in a mixture of gases which includes nitrogen. The first layer is exposed to a microwave plasma to form a nitrogen doped ultrananocrystalline diamond film on the first layer, which has a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %. The field emitter has about 10.sup.12 to about 10.sup.14 emitting sites per cm.sup.2. A photocathode can also be formed similarly by forming a nitrogen doped ultrananocrystalline diamond film on a substrate similar to the field emitter, and then hydrogen terminating the film. The photocathode is responsive to near ultraviolet light as well as to visible light.

  12. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    Science.gov (United States)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  13. A highly efficient directional molecular white-light emitter driven by a continuous-wave laser diode.

    Science.gov (United States)

    Rosemann, Nils W; Eußner, Jens P; Beyer, Andreas; Koch, Stephan W; Volz, Kerstin; Dehnen, Stefanie; Chatterjee, Sangam

    2016-06-10

    Tailored light sources have greatly advanced technological and scientific progress by optimizing the emission spectrum or color and the emission characteristics. We demonstrate an efficient spectrally broadband and highly directional warm-white-light emitter based on a nonlinear process driven by a cheap, low-power continuous-wave infrared laser diode. The nonlinear medium is a specially designed amorphous material composed of symmetry-free, diamondoid-like cluster molecules that are readily obtained from ubiquitous resources. The visible part of the spectrum resembles the color of a tungsten-halogen lamp at 2900 kelvin while retaining the superior beam divergence of the driving laser. This approach of functionalizing energy-efficient state-of-the-art semiconductor lasers enables a technology complementary to light-emitting diodes for replacing incandescent white-light emitters in high-brilliance applications. PMID:27284190

  14. A highly efficient directional molecular white-light emitter driven by a continuous-wave laser diode

    Science.gov (United States)

    Rosemann, Nils W.; Eußner, Jens P.; Beyer, Andreas; Koch, Stephan W.; Volz, Kerstin; Dehnen, Stefanie; Chatterjee, Sangam

    2016-06-01

    Tailored light sources have greatly advanced technological and scientific progress by optimizing the emission spectrum or color and the emission characteristics. We demonstrate an efficient spectrally broadband and highly directional warm-white-light emitter based on a nonlinear process driven by a cheap, low-power continuous-wave infrared laser diode. The nonlinear medium is a specially designed amorphous material composed of symmetry-free, diamondoid-like cluster molecules that are readily obtained from ubiquitous resources. The visible part of the spectrum resembles the color of a tungsten-halogen lamp at 2900 kelvin while retaining the superior beam divergence of the driving laser. This approach of functionalizing energy-efficient state-of-the-art semiconductor lasers enables a technology complementary to light-emitting diodes for replacing incandescent white-light emitters in high-brilliance applications.

  15. Ultralow mode-volume photonic crystal nanobeam cavities for high-efficiency coupling to individual carbon nanotube emitters

    Science.gov (United States)

    Miura, R.; Imamura, S.; Ohta, R.; Ishii, A.; Liu, X.; Shimada, T.; Iwamoto, S.; Arakawa, Y.; Kato, Y. K.

    2014-11-01

    The unique emission properties of single-walled carbon nanotubes are attractive for achieving increased functionality in integrated photonics. In addition to being room-temperature telecom-band emitters that can be directly grown on silicon, they are ideal for coupling to nanoscale photonic structures. Here we report on high-efficiency coupling of individual air-suspended carbon nanotubes to silicon photonic crystal nanobeam cavities. Photoluminescence images of dielectric- and air-mode cavities reflect their distinctly different mode profiles and show that fields in the air are important for coupling. We find that the air-mode cavities couple more efficiently, and estimated spontaneous emission coupling factors reach a value as high as 0.85. Our results demonstrate advantages of ultralow mode-volumes in air-mode cavities for coupling to low-dimensional nanoscale emitters.

  16. Highly stable carbon nanotube field emitters on small metal tips against electrical arcing for miniature X-ray tubes

    International Nuclear Information System (INIS)

    If CNT emitters are operated at a high voltage or at a high electric field, electrical arcing (or vacuum breakdown) can occur. Arcing can be initiated by the removed CNTs, impurities on the CNTs or substrates, protrusion of CNTs, low operating vacuum, and a very high electric field. Since arcing is accompanied with a very high current flow and it can produce plasma channel near the emitter, CNTs are seriously damaged or sometimes CNTs are almost completely removed from the substrate by the arcing events. Detachment of CNTs from a substrate is an irreversible catastrophic phenomenon for a device operation. In addition to the detachment of CNTs, arcing induces a sudden voltage drop and thus device operation is stopped. The metal mixture strongly attached CNTs to the tip substrate. Due to the strong adhesion, CNT emitters could be pre-treated with electrical conditioning process without seriously damaging the CNTs even though many intense arcing events were induced at the small and sharp geometry of the tip substrate. Impurities that were loosely bound to the substrates were almost removed and CNTs heights became uniform after the electrical conditioning process

  17. Highly stable carbon nanotube field emitters on small metal tips against electrical arcing for miniature X-ray tubes

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jun Mok; Kim, Hyun Jin; Kim, Hyun Nam; Raza, Hamid Saeed; Cho, Sung Oh [Korea Advanced Institute of Science and Technology Daejeon (Korea, Republic of)

    2015-05-15

    If CNT emitters are operated at a high voltage or at a high electric field, electrical arcing (or vacuum breakdown) can occur. Arcing can be initiated by the removed CNTs, impurities on the CNTs or substrates, protrusion of CNTs, low operating vacuum, and a very high electric field. Since arcing is accompanied with a very high current flow and it can produce plasma channel near the emitter, CNTs are seriously damaged or sometimes CNTs are almost completely removed from the substrate by the arcing events. Detachment of CNTs from a substrate is an irreversible catastrophic phenomenon for a device operation. In addition to the detachment of CNTs, arcing induces a sudden voltage drop and thus device operation is stopped. The metal mixture strongly attached CNTs to the tip substrate. Due to the strong adhesion, CNT emitters could be pre-treated with electrical conditioning process without seriously damaging the CNTs even though many intense arcing events were induced at the small and sharp geometry of the tip substrate. Impurities that were loosely bound to the substrates were almost removed and CNTs heights became uniform after the electrical conditioning process.

  18. Imaging optimizations with non-pure and high-energy positron emitters in small animal positron computed tomography

    International Nuclear Information System (INIS)

    The contribution on imaging optimizations with non-pure and high-energy positron emitters in small animal positron emission tomography (PET) covers the following topics: physical fundamentals of PET, mathematical image reconstruction and data analyses, Monte-Carlo simulations and implemented correction scheme, quantification of cascade gamma coincidences based on simulations and measurements, sinogram based corrections, restoration of the spatial resolution, implementation of full corrections.

  19. Thin-film 'Thermal Well' Emitters and Absorbers for High-Efficiency Thermophotovoltaics

    CERN Document Server

    Tong, Jonathan K; Huang, Yi; Boriskina, Svetlana V; Chen, Gang

    2015-01-01

    A new approach is introduced to significantly improve the performance of thermophotovoltaic (TPV) systems by using low-dimensional thermal emitters and photovoltaic (PV) cells. By reducing the thickness of both the emitter and the PV cell, strong spectral selectivity in both thermal emission and absorption can be achieved by confining photons in trapped waveguide modes inside the thin-films that act as thermal analogs to quantum wells. Simultaneously, photo-excited carriers travel shorter distances across the thin-films reducing bulk recombination losses resulting in a lower saturation current in the PV cell. We predict a TPV efficiency enhancement with near-field coupling between the thermal emitter and the PV cell of up to 38.7% using a germanium (Ge) emitter at 1000 K and a gallium antimonide (GaSb) cell with optimized thicknesses separated by 100 nm. Even in the far-field limit, the efficiency is predicted to reach 31.5%, which is an order of magnitude higher than the Shockley Queisser limit of 1.6% for a...

  20. A bunch compressor for small emittances and high peak currents at the VUV free-electron laser

    International Nuclear Information System (INIS)

    The free-electron laser (FEL) at the TESLA test facility (TTF2) produces laser-like radiation in the vacuum-ultraviolet (VUV) and soft X-ray regime. To reach the minimum radiation wavelength of 6nm, bunches of electrons with an energy of 1 GeV, a peak current of 2500 A and a normalized transverse emittance of less than 2 mm mrad are needed. The high peak current is achieved by compressing the electron bunches longitudinally in two magnetic chicanes. The first chicane is a modified version of bunch compressor 2 (BC2) which was used at TTF1. The second chicane is a new bunch compressor, the so called BC3. Since the charge density is very high when the bunches pass BC3, strong coherent synchrotron radiation (CSR) is emitted by the electrons and the transverse emittance of the bunch is diluted. Within this thesis different chicane layouts are compared analytically and by computer simulations to find a chicane layout which minimizes emittance dilution. A 6-bend S-shaped chicane is found to match the requirements of the VUV-FEL very well. CSR will not only lead to a growth of the transverse emittance, but also to an amplification of small modulations in energy and charge density. The dependence of the amplification on the modulation wavelength is studied for different chicane layouts and various electron bunch parameters. Computer simulations and results obtained by a theoretical model are compared. It is shown that density modulations can be amplified in BC3 by up to one order of magnitude. When the amplification in BC2 and BC3 is taken into account, the total amplification factor might reach up to two orders of magnitude. (orig.)

  1. High-power-efficiency hybrid white organic light-emitting diodes with a single emitting layer doped with blue delayed fluorescent and yellow phosphorescent emitters

    International Nuclear Information System (INIS)

    High-efficiency hybrid white organic light-emitting diodes (HWOLEDs) with a blue thermally activated delayed fluorescent (TADF) emitter and a yellow phosphorescent emitter doped in a single emitting layer were developed. Exciton harvesting by the blue TADF and yellow phosphorescent emitters rendered both singlet and triplet excitons to contribute to the white emission, which leads to a high quantum efficiency of 22.4% and a power efficiency of 60.3 lm W−1 in the HWOLEDs. In addition, the electroluminescence spectra of the HWOLEDs were kept stable from 100 cd m−2 to 5, 000 cd m−2. (paper)

  2. Studies and calculations of transverse emittance growth in high-energy proton storage rings

    International Nuclear Information System (INIS)

    In the operation of proton-antiproton colliders, an important goal is to maximize the integrated luminosity. During such operations in the Fermilab Tevatron, the transverse beam emittances were observed to grow unexpectedly quickly, thus causing a serious reduction of the luminosity. We have studied this phenomenon experimentally and theoretically. A formula for the emittance growth rate, due to random dipole kicks, is derived. In the experiment, RF phase noise of known amplitude was deliberately injected into the Tevatron to kick the beam randomly, via dispersion at the RF cavities. Theory and experiment are found to agree reasonably well. We also briefly discuss the problem of quadrupole kicks. 14 refs., 2 figs., 3 tabs

  3. Beam emittance and output waveforms of high-flux laser ion source

    International Nuclear Information System (INIS)

    A laser ion source with short drift distance has been developed for a driver of heavy ion fusion (HIF). It supplies a copper ion beam of 200 mA (255 mA/cm2) with duration of 400 ns and beam emittance is about 0.8π mm·mrad. Moreover it has fast rising (30 ns), flat-top current waveform and a potential to deliver pure charge states between 1+ - 3+. Experimental results indicate that the laser ion source is a good candidate for the HIF driver. (author)

  4. Current technology for development of low solar absorptance/high emittance coatings. [spacecraft thermal control surface materials

    Science.gov (United States)

    Gilligan, J. E.; Harada, Y.; Gates, D. W.

    1974-01-01

    A comprehensive program to develop low solar absorptance/high emittance coatings, to be successful, must coordinate basic materials preparation, coatings technology, environmental simulation, production, and flight-test evaluation. The prime criteria for 'white' thermal-control coatings are low solar absorptance and, most importantly, solar-absorptance stability. Many variables affect the solar absorptance and its stability. These effects must be discerned and evaluated. The factors involved, however, are not entirely independent; accordingly, the present paper emphasizes the major variables, the relationships among them, and how important they are in improving the properties and performance of the coatings.

  5. High-precision half-life and branching-ratio measurements for superallowed Fermi β+ emitters at TRIUMF – ISAC

    Directory of Open Access Journals (Sweden)

    Laffoley A. T.

    2014-03-01

    Full Text Available A program of high-precision half-life and branching-ratio measurements for superallowed Fermi β emitters is being carried out at TRIUMF’s Isotope Separator and Accelerator (ISAC radioactive ion beam facility. Recent half-life measurements for the superallowed decays of 14O, 18Ne, and 26Alm, as well as branching-ratio measurements for 26Alm and 74Rb are reported. These results provide demanding tests of the Standard Model and the theoretical isospin symmetry breaking (ISB corrections in superallowed Fermi β decays.

  6. [Study on packaging-induced stress in 4 mm cavity length high-power single emitter semiconductor laser].

    Science.gov (United States)

    Zhang, Yong; Yang, Rui-xia; An, Zhen-feng; Xu, Hui-wu

    2014-06-01

    To reduce packaging-induced stress of long cavity length high-power single emitter semiconductor laser, the relationship between the stress and the wavelength shift was deduced on the basis of the theory that the stress can change the band gap. A method was developed for quantitatively calculating the stress by measuring the emission spectrum of the laser under pulse conditions. The results show that the soldering quality is a critical factor affecting thermal stress. The difference in stress can exceed 300 MPa due to the difference in soldering quality. By optimizing the reflowing soldering curve of the laser, the stress of the laser drops from 129.7 to 53.4 MPa. This method can also effectively solve the problem that the stress varies with storage time. This work demonstrates that the measurement and analysis of the emission spectrum of the laser can provide a useful method to study packaging stress of the high-power single emitter semiconductor laser. It is also an available means to evaluate and analyze soldering quality. PMID:25358141

  7. Beam structure and transverse emittance studies of high-energy ion beams

    International Nuclear Information System (INIS)

    A visual diagnostic technique has been developed to monitor and study ion-beam structure, shape, and size along a transport line. In this technique, a commercially available fluorescent screen is used in conjunction with a video camera. The visual representation of the beam structure is digitized enhanced through false-color coding, and displayed on a TV monitor for on-line viewing. The digitized information is stored for further off-line processing (e.g.,extraction of beam profiles). An optional wire grid placed upstream of the fluor screen adds the capability of measuring transverse emittance (or angular spread). This technique allows real-time observation of the beam response to parameter changes (e.g., evolution of the beam structure, shifts in the beam intensity at various spatial locations within the beam perimeter, and shifts in the beam center and position)

  8. X-ray and Multiwavelength Insights into the Inner Structure of High-Luminosity Disc-Like Emitters

    CERN Document Server

    Luo, B; Eracleous, M; Wu, Jian; Hall, P B; Rafiee, A; Schneider, D P; Wu, Jianfeng

    2012-01-01

    We present X-ray and multiwavelength studies of a sample of eight high-luminosity active galactic nuclei (AGNs) with disc-like H\\beta emission-line profiles selected from the Sloan Digital Sky Survey Data Release 7. These sources have higher redshift (z~0.6) than the majority of the known disc-like emitters, and they occupy a largely unexplored space in the luminosity-redshift plane. Seven sources have typical AGN X-ray spectra with power-law photon indices of \\Gamma~1.4-2.0; two of them show some X-ray absorption (column density N_H~10^{21}-10^{22} cm^{-2}$ for neutral gas). The other source, J0850+4451, has only three hard X-ray photons detected and is probably heavily obscured (N_H>3x10^{23} cm^{-2}). This object is also identified as a low-ionization broad absorption line (BAL) quasar based on Mg II \\lambda2799 absorption; it is the first disc-like emitter reported that is also a BAL quasar. The IR-to-UV spectral energy distributions (SEDs) of these eight sources are similar to the mean SEDs of typical qu...

  9. A highly efficient CMOS nanoplasmonic crystal enhanced slow-wave thermal emitter improves infrared gas-sensing devices

    OpenAIRE

    Andreas Pusch; Andrea De Luca; Oh, Sang S.; Sebastian Wuestner; Tyler Roschuk; Yiguo Chen; Sophie Boual; Zeeshan Ali; Phillips, Chris C.; Minghui Hong; Maier, Stefan A.; Florin Udrea; Hopper, Richard H.; Ortwin Hess

    2015-01-01

    The application of plasmonics to thermal emitters is generally assisted by absorptive losses in the metal because Kirchhoff’s law prescribes that only good absorbers make good thermal emitters. Based on a designed plasmonic crystal and exploiting a slow-wave lattice resonance and spontaneous thermal plasmon emission, we engineer a tungsten-based thermal emitter, fabricated in an industrial CMOS process, and demonstrate its markedly improved practical use in a prototype non-dispersive infrared...

  10. Shielding in ungated field emitter arrays

    International Nuclear Information System (INIS)

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can be used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 102–104 are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays

  11. Narrow-band surveys for very high redshift Lyman-alpha emitters

    CERN Document Server

    Nilsson, Kim K; Lacey, Cedric G; Baugh, Carlton M; Thommes, Eduard

    2007-01-01

    Context: Many current and future surveys aim to detect the highest redshift (z >~ 7) sources through their Lyman-alpha (Ly-alpha) emission, using the narrow-band imaging method. However, to date the surveys have only yielded non-detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies. Aims: We aim to calculate model luminosity functions and mock surveys of Ly-alpha emitters at z >~ 7 based on a variety of approaches. Methods: We calculate model luminosity functions at different redshifts based on three different approaches: a semi-analytical model based on CDM, a simple phenomenological model, and an extrapolation of observed Schechter functions at lower redshifts. The results of the first two models are compared with observations made at redshifts z ~ 5.7 and z ~ 6.5, and they are then extrapolated to higher redshift. Results: We present model luminosity functions for redshifts between z = 7 - 12.5 and give specific num...

  12. Capillary Electrophoresis-nanoelectrospray Ionization-selected Reaction Monitoring Mass Spectrometry Via A True Sheathless Metal-coated Emitter Interface For Robust And High Sensitivity Sample Quantification

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xuejiang; Fillmore, Thomas L.; Gao, Yuqian; Tang, Keqi

    2016-03-30

    A new sheathless CITP/CZE-MS interface, based on a commercially available capillary with an integrated metal coated ESI emitter, was developed in this study aiming at overcoming the reproducibility and ruggedness problems, suffered to a certain degree by almost all the available CE-MS interfaces, and pushing the CE-MS technology suitable for routine sample analysis with high sensitivity. The new CITP/CZE-MS interface allows the electric contact between ESI voltage power supply and the CE separation liquid by using a conductive liquid that comes in contact with the metal coated surface of the ESI emitter, making it a true sheathless CE-MS interface. Stable electrospray was established by avoiding the formation of gas bubbles from electro chemical reaction at the emitter tip or inside of the CE capillary. Crucial operating parameters, such as sample loading volume, flow rate, and separation voltage, were systematically evaluated for their effects on both CITP/CZE separation efficiency and MS detection sensitivity. Around one hundred CITP/CZE-MS analyses can be easily achieved by using the new sheathless CITP/CZE interface without a noticeable loss of metal coating on the ESI emitter surface, or degrading of the ESI emitter performance. The reproducibility in analyte migration time and quantitative performance of the new interface was experimentally evaluated to demonstrate a LOQ bellow 5 attomole.

  13. High peak-to-valley current ratio In0.53Ga0.47As/AlAs resonant tunneling diode with a high doping emitter

    International Nuclear Information System (INIS)

    An In0.53Ga0.47As/AlAs resonant tunneling diode (RTD) with a high doping emitter is designed and fabricated using air bridge technology. The RTD exhibits a high peak-to-valley current ratio (PVCR) of more than 40 at room temperature, with a peak current density of 24 kA/cm2. The extraction of device parameters from DC and microwave measurements is presented together with an RTD equivalent circuit. The high PVCR RTD with small intrinsic capacitance is favorable for microwave/THz applications. (semiconductor devices)

  14. High peak-to-valley current ratio In0.53Ga0.47As/AlAs resonant tunneling diode with a high doping emitter

    Science.gov (United States)

    Wei, Wang; Hao, Sun; Teng, Teng; Xiaowei, Sun

    2012-12-01

    An In0.53Ga0.47As/AlAs resonant tunneling diode (RTD) with a high doping emitter is designed and fabricated using air bridge technology. The RTD exhibits a high peak-to-valley current ratio (PVCR) of more than 40 at room temperature, with a peak current density of 24 kA/cm2. The extraction of device parameters from DC and microwave measurements is presented together with an RTD equivalent circuit. The high PVCR RTD with small intrinsic capacitance is favorable for microwave/THz applications.

  15. High peak-to-valley current ratio In0.53Ga0.47As/AlAs resonant tunneling diode with a high doping emitter

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Sun Hao; Teng Teng; Sun Xiaowei

    2012-01-01

    An In0.53Ga0.47As/AlAs resonant tunneling diode (RTD) with a high doping emitter is designed and fabricated using air bridge technology.The RTD exhibits a high peak-to-valley current ratio (PVCR) of more than 40 at room temperature,with a peak current density of 24 kA/cm2.The extraction of device parameters from DC and microwave measurements is presented together with an RTD equivalent circuit.The high PVCR RTD with small intrinsic capacitance is favorable for microwave/THz applications.

  16. Diamondoid monolayers as electron emitters

    Science.gov (United States)

    Yang, Wanli; Fabbri, Jason D.; Melosh, Nicholas A.; Hussain, Zahid; Shen, Zhi-Xun

    2012-04-10

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  17. Magnetic field control of near-field radiative heat transfer and the realization of highly tunable hyperbolic thermal emitters

    Science.gov (United States)

    Moncada-Villa, E.; Fernández-Hurtado, V.; García-Vidal, F. J.; García-Martín, A.; Cuevas, J. C.

    2015-09-01

    We present a comprehensive theoretical study of the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates. We show that when the plates are made of doped semiconductors, the near-field thermal radiation can be severely affected by the application of a static magnetic field. We find that irrespective of its direction, the presence of a magnetic field reduces the radiative heat conductance, and dramatic reductions up to 700% can be found with fields of about 6 T at room temperature. We show that this striking behavior is due to the fact that the magnetic field radically changes the nature of the NFRHT. The field not only affects the electromagnetic surface waves (both plasmons and phonon polaritons) that normally dominate the near-field radiation in doped semiconductors, but it also induces hyperbolic modes that progressively dominate the heat transfer as the field increases. In particular, we show that when the field is perpendicular to the plates, the semiconductors become ideal hyperbolic near-field emitters. More importantly, by changing the magnetic field, the system can be continuously tuned from a situation where the surface waves dominate the heat transfer to a situation where hyperbolic modes completely govern the near-field thermal radiation. We show that this high tunability can be achieved with accessible magnetic fields and very common materials like n -doped InSb or Si. Our study paves the way for an active control of NFRHT and it opens the possibility to study unique hyperbolic thermal emitters without the need to resort to complicated metamaterials.

  18. The preservation of low emittance flat beams

    International Nuclear Information System (INIS)

    Many future linear collider designs require beams with very small transverse emittances and large emittance ratios εx much-gt εy. In this paper, we will discuss issues associated with the preservation of these small emittances during the acceleration of the beams. The primary sources of transverse emittance dilution in a high energy linear accelerator are the transverse wakefields, the dispersive errors, RF deflections, and betatron coupling. We will discuss the estimation of these effects and the calculation of tolerances that will limit the emittance dilution with a high degree of confidence. Since the six-dimensional emittance is conserved and only the projected emittances are increased, these dilutions can be corrected if the beam has not filamented (phase mixed). We discuss methods of correcting the dilutions and easing the tolerances with beam-based alignment and steering techniques, and non-local trajectory bumps. Finally, we discuss another important source of luminosity degradation, namely, pulse-to-pulse jitter

  19. Highly efficient exciplex organic light-emitting diodes using thermally activated delayed fluorescent emitters as donor and acceptor materials

    Science.gov (United States)

    Jeon, Sang Kyu; Yook, Kyoung Soo; Lee, Jun Yeob

    2016-06-01

    Highly efficient exciplex type organic light-emitting diodes were developed using thermally activated delayed fluorescent emitters as donors and acceptors of an exciplex. Blue emitting bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) was a donor and 9,9‧-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole) (DDCzTrz) and 9,9‧,9″-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(9H-carbazole) (TCzTrz) were acceptor materials. The exciplexes of DMAC-DPS:TCzTrz and DMAC-DPS:DDCzTrz resulted in high photoluminescence quantum yield and high quantum efficiency in the green exciplex organic light-emitting diodes. High quantum efficiencies of 13.4% and 15.3% were obtained in the DMAC-DPS:DDCzTrz and DMAC-DPS:TCzTrz exciplex devices.

  20. Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Robertshaw, G.A.; Snyder, A.L.; Weiner, M.M.

    1993-05-14

    The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended for use as an input to the Air Force Environmental Impact Statement as part of the Environmental Impact Analysis Process.

  1. Beam emittance measurements in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Zelenski,A.; Bazilevsky, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y.; Morozov, B.; Nemesure, S.; Russo, t.; Steski, D.; Sivertz, M.

    2009-05-04

    The RHIC proton polarimeters can operate in scanning mode, giving polarization profiles and transverse beam intensity profile (beam emittance) measurements. The polarimeters function as wire scanners, providing a very good signal/noise ratio and high counting rate. This allows accurate bunch-by-bunch emittance measurements during fast target sweeps (<1 s) through the beam. Very thin carbon strip targets make these measurements practically non-destructive. Bunch by bunch emittance measurements are a powerful tool for machine set-up; in RHIC, individual proton beam transverse emittances can only be measured by CNI polarimeter scans. We discuss the consistency of these measurements with Ionization Profile Monitors (IPMs) and vernier scan luminosity measurements. Absolute accuracy limitations and cross-calibration of different techniques are also discussed.

  2. Electron emission from nano-structured carbon composite materials and fabrication of high-quality electron emitters by using plasma technology

    International Nuclear Information System (INIS)

    Many trials have been done to fabricate high-quality electron-emitters from nano-composite carbon materials (such as nano-diamond, carbon nano tubes and others) by means of a variety of plasma chemical-vapor-deposition (CVD) techniques. Based upon the mechanism of electron emission, we have proposed several strategic guide lines for the fabrication of good emitters. Then, following these lines, several types of emitters were tried. One of the emitters has shown a worldclass, top ranking for fabricating very bright lamps: namely, a low turn-on voltage (0.5 ∼ 1 V/μm to induce 10 μA/cm2 emission current) to emit a 1 mA/cm2 current at 3 V/μm and 100 mA/cm2 current at a slightly higher applied voltage. The bright lamps are Mercury-free fluorescence lamps to exhibit brightness of ∼105 cd/m2 with high efficiency of ∼100 lm/w.

  3. Book review: 10 billion

    OpenAIRE

    Saffin, Kate

    2013-01-01

    10 Billion aims to take a dramatic look at the challenges we face today, from over-population to energy wars, to melting ice caps to civil conflict, presented in an eye-catching infographic style. Stephen Emmott has attempted to obtain reach and for all the criticism of his method and writing, it is not as though he is pretending that this would make it in to a journal, an article for which he is more than capable of writing. Science communication is never easy, writes Kate Saffin, and if Emm...

  4. Capillary Electrophoresis-Nanoelectrospray Ionization-Selected Reaction Monitoring Mass Spectrometry via a True Sheathless Metal-Coated Emitter Interface for Robust and High-Sensitivity Sample Quantification.

    Science.gov (United States)

    Guo, Xuejiang; Fillmore, Thomas L; Gao, Yuqian; Tang, Keqi

    2016-04-19

    A new sheathless transient capillary isotachophoresis (CITP)/capillary zone electrophoresis (CZE)-MS interface, based on a commercially available capillary with an integrated metal-coated ESI emitter, was developed in this study aiming at overcoming the reproducibility and ruggedness problems suffered to a certain degree by almost all the available CE-MS interfaces, and pushing the CE-MS technology suitable for routine sample analysis with high sensitivity. The new CITP/CZE-MS interface allows the electric contact between ESI voltage power supply and the CE separation liquid by using a conductive liquid that comes in contact with the metal-coated surface of the ESI emitter, making it a true sheathless CE-MS interface. Stable electrospray was established by avoiding the formation of gas bubbles from electrochemical reaction inside the CE capillary. Crucial operating parameters, such as sample loading volume, flow rate, and separation voltage, were systematically evaluated for their effects on both CITP/CZE separation efficiency and MS detection sensitivity. Around one hundred CITP/CZE-MS analyses can be easily achieved by using the new sheathless CITP/CZE interface without a noticeable loss of metal coating on the ESI emitter surface, or degrading of the ESI emitter performance. The reproducibility in analyte migration time and quantitative performance of the new interface was experimentally evaluated to demonstrate a LOQ below 5 attomole. PMID:27028594

  5. High-Precision Half-Life Measurements for the Superallowed β^{+} Emitter ^{10}C: Implications for Weak Scalar Currents.

    Science.gov (United States)

    Dunlop, M R; Svensson, C E; Ball, G C; Grinyer, G F; Leslie, J R; Andreoiu, C; Austin, R A E; Ballast, T; Bender, P C; Bildstein, V; Diaz Varela, A; Dunlop, R; Garnsworthy, A B; Garrett, P E; Hackman, G; Hadinia, B; Jamieson, D S; Laffoley, A T; MacLean, A D; Miller, D M; Mills, W J; Park, J; Radich, A J; Rajabali, M M; Rand, E T; Unsworth, C; Valencik, A; Wang, Z M; Zganjar, E F

    2016-04-29

    Precision measurements of superallowed Fermi β-decay transitions, particularly for the lightest superallowed emitters ^{10}C and ^{14}O, set stringent limits on possible scalar current contributions to the weak interaction. In the present work, a discrepancy between recent measurements of the ^{10}C half-life is addressed through two high-precision half-life measurements, via γ-ray photopeak and β counting, that yield consistent results for the ^{10}C half-life of T_{1/2}=19.2969±0.0074  s and T_{1/2}=19.3009±0.0017  s, respectively. The latter is the most precise superallowed β-decay half-life measurement reported to date and the first to achieve a relative precision below 10^{-4}. A fit to the world superallowed β-decay data including the ^{10}C half-life measurements reported here yields b_{F}=-0.0018±0.0021 (68% C.L.) for the Fierz interference term and C_{S}/C_{V}=+0.0009±0.0011 for the ratio of the weak scalar to vector couplings assuming left-handed neutrinos. PMID:27176517

  6. Aberration Corrected Emittance Exchange

    CERN Document Server

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  7. Method for maximizing the brightness of the bunches in a particle injector by converting a highly space-charged beam to a relativistic and emittance-dominated beam

    Energy Technology Data Exchange (ETDEWEB)

    Hannon, Fay

    2016-08-02

    A method for maximizing the brightness of the bunches in a particle injector by converting a highly space-charged beam to a relativistic and emittance-dominated beam. The method includes 1) determining the bunch charge and the initial kinetic energy of the highly space-charge dominated input beam; 2) applying the bunch charge and initial kinetic energy properties of the highly space-charge dominated input beam to determine the number of accelerator cavities required to accelerate the bunches to relativistic speed; 3) providing the required number of accelerator cavities; and 4) setting the gradient of the radio frequency (RF) cavities; and 5) operating the phase of the accelerator cavities between -90 and zero degrees of the sinusoid of phase to simultaneously accelerate and bunch the charged particles to maximize brightness, and until the beam is relativistic and emittance-dominated.

  8. High peak power (≥10 mW) quantum cascade superluminescent emitter

    International Nuclear Information System (INIS)

    We report room temperature and milliwatt range mid-infrared superluminescent emission at 5 μm from Quantum Cascade (QC) devices. To achieve high power superluminescence, we utilize an ultrastrong coupling QC laser design, and employ a cavity formed by the combination of a 17° tilted cleaved facet and a wet etched rounded and sloped facet to introduce additional mirror loss. For pulsed mode operation, a 8 mm long and 15 μm wide device achieves ∼1.3 mW peak power at 300 K and a 25 μm wide device with Si3N4 anti-reflection coated rounded facet achieves ∼10.2 mW peak optical output power at 250 K

  9. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  10. High peak power (≥10 mW) quantum cascade superluminescent emitter

    Energy Technology Data Exchange (ETDEWEB)

    Aung, Nyan L., E-mail: naung@princeton.edu; Yu, Zhouchangwan; Yu, Ye; Liu, Peter Q.; Gmachl, Claire F. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Wang, Xiaojun; Fan, Jen-Yu; Troccoli, Mariano [AdTech Optics Inc., City of Industry, California 91748 (United States)

    2014-12-01

    We report room temperature and milliwatt range mid-infrared superluminescent emission at 5 μm from Quantum Cascade (QC) devices. To achieve high power superluminescence, we utilize an ultrastrong coupling QC laser design, and employ a cavity formed by the combination of a 17° tilted cleaved facet and a wet etched rounded and sloped facet to introduce additional mirror loss. For pulsed mode operation, a 8 mm long and 15 μm wide device achieves ∼1.3 mW peak power at 300 K and a 25 μm wide device with Si{sub 3}N{sub 4} anti-reflection coated rounded facet achieves ∼10.2 mW peak optical output power at 250 K.

  11. High-spatial-resolution MWPC for medical imaging with positron emitters

    International Nuclear Information System (INIS)

    The performance of a 15 x 15 cm2 MultiWire Proportional Chamber (MWPC) with lead glass tube converter is presented. A standard Argon-Methane (70-30) gas mixture has been used at various pressures between 1.0 and 2.0 atm. For 511 keV γ-rays incident almost perpendicular onto a 1.0 cm thick lead glass tube converter, a detection efficiency of 4.5%, a time resolution of 130 ns (FWHM) and a spatial resolution of 1.3 mm (FWHM) has been obtained at 2 atm. Fast delay lines, capacitively coupled to the cathodes, standard integrated amplifiers and comparator electronics have been adopted for the position read-out. The use of fast delay lines (specific delay 8 ns/cm) ensures a high rate capability. A multiplanar positron camera is proposed, made of six MWPC modules arranged to form the lateral surface of a hexagonal prism. Each module (50 x 50 cm2) will have a 2 cm thick converter on both sides of the chamber and will be operating at 2 atm. The expected performance is presented and compared with that of a recent multi-ring BGO camera, and is shown to be superior in spatial resolution and comparable in event rate at a considerably lower cost

  12. High Power RF Conditioning and Measurement of Longitudinal Emittance at PITZ

    CERN Document Server

    Bähr, Jürgen; HuiHan, Jang; Krasilnikov, Mikhail; Lipka, Dirk; Miltchev, Velizar; Oppelt, Anne; Petrosyan, Bagrat; Pose, Dietrich; Riemann, S; Staykov, Lazar; Stephan, Frank

    2004-01-01

    In 2003 the PITZ RF-gun at DESY Zeuthen has been fully characterized. After RF conditioning 3.2MW input power at 10Hz and a RF-pulse length of 0.9ms has been reached. This correponds to a gradient of 42MV/m at the cathode. The goal is to increase the accelerating gradient of the gun and the duty cycle significantly. The motivation is based on the expectation of a remarkable increase in beam quality at higher gradients. A high duty cycle is of advantage for FEL users. The conditioning procedure was started in spring 2004. The paper will report about procedure and results of this program. The preparation of an experimental setup for the measurement of the complete longitudinal phase space at about 5 MeV using a streak camera will be finished in summer 2004. Cherenkov light created by Silica aerogel radiators in the dispersive arm of PITZ is transmitted to a streak camera by an optical transmission line. The light distribution of the momentum spectrum is projected onto the entrance slit of the streak camera. The...

  13. High-precision branching-ratio measurement for the superallowed β+ emitter 74Rb

    Science.gov (United States)

    Dunlop, R.; Ball, G. C.; Leslie, J. R.; Svensson, C. E.; Towner, I. S.; Andreoiu, C.; Chagnon-Lessard, S.; Chester, A.; Cross, D. S.; Finlay, P.; Garnsworthy, A. B.; Garrett, P. E.; Glister, J.; Hackman, G.; Hadinia, B.; Leach, K. G.; Rand, E. T.; Starosta, K.; Tardiff, E. R.; Triambak, S.; Williams, S. J.; Wong, J.; Yates, S. W.; Zganjar, E. F.

    2013-10-01

    A high-precision branching-ratio measurement for the superallowed β+ decay of 74Rb was performed at the TRIUMF Isotope Separator and Accelerator (ISAC) radioactive ion-beam facility. The scintillating electron-positron tagging array (SCEPTAR), composed of 10 thin plastic scintillators, was used to detect the emitted β particles; the 8π spectrometer, an array of 20 Compton-suppressed HPGe detectors, was used for detecting γ rays that were emitted following Gamow-Teller and nonanalog Fermi β+ decays of 74Rb; and the Pentagonal Array of Conversion Electron Spectrometers (PACES), an array of 5 Si(Li) detectors, was employed for measuring β-delayed conversion electrons. Twenty-three excited states were identified in 74Kr following 8.241(4)×108 detected 74Rb β decays. A total of 58 γ-ray and electron transitions were placed in the decay scheme, allowing the superallowed branching ratio to be determined as B0=99.545(31)%. Combined with previous half-life and Q-value measurements, the superallowed branching ratio measured in this work leads to a superallowed ft value of 3082.8(65) s. Comparisons between this superallowed ft value and the world-average-corrected Ft¯ value, as well as the nonanalog Fermi branching ratios determined in this work, provide guidance for theoretical models of the isospin-symmetry-breaking corrections in this mass region.

  14. Combustion powered thermophotovoltaic emitter system

    Energy Technology Data Exchange (ETDEWEB)

    McHenry, R.S. [Naval Academy, Annapolis, MD (United States). Naval Architecture, Ocean and Marine Engineering

    1995-07-01

    The US Naval Academy (USNA) has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The final apparatus was to be portable, completely self contained, and was to incorporate cycle efficiency optimization such as exhaust stream recuperation. Through computer modeling and prototype experimentation, a methane fueled emitter system was designed from structural ceramic materials to fulfill the high temperature requirements necessary for high system efficiency. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design.

  15. Emittance Measurement in MICE

    OpenAIRE

    Hart, Terrence L.; Kaplan, Daniel M.

    2008-01-01

    Muon ionization cooling provides the only practical solution to prepare high-brilliance beams necessary for a neutrino factory or muon collider. The Muon Ionization Cooling Experiment (MICE), under development at the Rutherford Appleton Laboratory, is installing the first set of particle detectors ever built to measure to 0.1% the emittance of a 200 MeV/c or so muon beam in and out of a cooling cell, and thus measure the cooling cell's performance. Two identical "emittometers" (a precise scin...

  16. Investigation of spatial resolution and temporal performance of SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) with integrated electrostatic focusing

    Science.gov (United States)

    Scaduto, David A.; Lubinsky, Anthony R.; Rowlands, John A.; Kenmotsu, Hidenori; Nishimoto, Norihito; Nishino, Takeshi; Tanioka, Kenkichi; Zhao, Wei

    2014-03-01

    We have previously proposed SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout), a novel detector concept with potentially superior spatial resolution and low-dose performance compared with existing flat-panel imagers. The detector comprises a scintillator that is optically coupled to an amorphous selenium photoconductor operated with avalanche gain, known as high-gain avalanche rushing photoconductor (HARP). High resolution electron beam readout is achieved using a field emitter array (FEA). This combination of avalanche gain, allowing for very low-dose imaging, and electron emitter readout, providing high spatial resolution, offers potentially superior image quality compared with existing flat-panel imagers, with specific applications to fluoroscopy and breast imaging. Through the present collaboration, a prototype HARP sensor with integrated electrostatic focusing and nano- Spindt FEA readout technology has been fabricated. The integrated electron-optic focusing approach is more suitable for fabricating large-area detectors. We investigate the dependence of spatial resolution on sensor structure and operating conditions, and compare the performance of electrostatic focusing with previous technologies. Our results show a clear dependence of spatial resolution on electrostatic focusing potential, with performance approaching that of the previous design with external mesh-electrode. Further, temporal performance (lag) of the detector is evaluated and the results show that the integrated electrostatic focusing design exhibits comparable or better performance compared with the mesh-electrode design. This study represents the first technical evaluation and characterization of the SAPHIRE concept with integrated electrostatic focusing.

  17. Emittance investigation of RF photo-injector

    CERN Document Server

    Yang Mao Rong; Li Zheng; Li Ming; Xu Zhou

    2002-01-01

    A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF find in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. The author analyzes the factors which lead the transverse emittance growth and method how to resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show these results are coincident

  18. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    Science.gov (United States)

    Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  19. Highly efficient non-doped deep blue fluorescent emitters with horizontal emitting dipoles using interconnecting units between chromophores.

    Science.gov (United States)

    Kim, Kwon-Hyeon; Baek, Jang Yeol; Cheon, Chan Woo; Moon, Chang-Ki; Sim, Bomi; Choi, Myeong Yong; Kim, Jang-Joo; Kim, Yun-Hi

    2016-09-21

    New deep blue fluorescent emitters composed of anthracene as an electron rich unit, a diphenyltriazine as a strong electron acceptor unit, and phenyl or xylene as interconnecting units were synthesised. The interconnecting unit between chromophores increased the singlet transition energy and the ratio of horizontal emitting dipoles. As a result, a non-doped blue fluorescent organic light-emitting diode (OLED) using a new emitter was demonstrated, with an external quantum efficiency (EQE) of 6.6% and Commision Internationale de l'Eclairage (CIE) colour coordinates of (0.145, 0.068). This device performance has been the highest EQE observed in deep blue non-doped OLEDs with CIE coordinates less than (0.145, 0.068) to date. PMID:27524501

  20. Bright Single Photon Emitter in Silicon Carbide

    Science.gov (United States)

    Lienhard, Benjamin; Schroeder, Tim; Mouradian, Sara; Dolde, Florian; Trong Tran, Toan; Aharonovich, Igor; Englund, Dirk

    Efficient, on-demand, and robust single photon emitters are of central importance to many areas of quantum information processing. Over the past 10 years, color centers in solids have emerged as excellent single photon emitters. Color centers in diamond are among the most intensively studied single photon emitters, but recently silicon carbide (SiC) has also been demonstrated to be an excellent host material. In contrast to diamond, SiC is a technologically important material that is widely used in optoelectronics, high power electronics, and microelectromechanical systems. It is commercially available in sizes up to 6 inches and processes for device engineering are well developed. We report on a visible-spectrum single photon emitter in 4H-SiC. The emitter is photostable at both room and low temperatures, and it enables 2 million photons/second from unpatterned bulk SiC. We observe two classes of orthogonally polarized emitters, each of which has parallel absorption and emission dipole orientations. Low temperature measurements reveal a narrow zero phonon line with linewidth < 0.1 nm that accounts for more than 30% of the total photoluminescence spectrum. To our knowledge, this SiC color emitter is the brightest stable room-temperature single photon emitter ever observed.

  1. Emittance Measurement in MICE

    CERN Document Server

    Hart, Terrence L

    2008-01-01

    Muon ionization cooling provides the only practical solution to prepare high-brilliance beams necessary for a neutrino factory or muon collider. The Muon Ionization Cooling Experiment (MICE), under development at the Rutherford Appleton Laboratory, is installing the first set of particle detectors ever built to measure to 0.1% the emittance of a 200 MeV/c or so muon beam in and out of a cooling cell, and thus measure the cooling cell's performance. Two identical "emittometers" (a precise scintillating-fiber tracker in solenoidal magnetic field and a 50 ps time-of-flight station) measure the six phase-space coordinates of each muon. Another TOF plane and two Cherenkov counters assure the purity of the incoming muon beam. A downstream electron/muon calorimeter eliminates contamination from decay electrons.

  2. Emittance measurements basing on probe-slit method for a high current grid-controlled pulse electron gun

    International Nuclear Information System (INIS)

    Single slit and probe method has been used for measuring the beam emittance of an electron gun. A movable slit 0.1 mm wide is used for sampling. A probe 0.1 mm in diameter parallel to the slit and moving at a constant velocity, is used to catch the beam through the slit. Using geometrical relation, the divergence r1' and r2' of the beam through the slit can be calculated. In the device used, the distance between the slit and the probe is 59 mm, the angle resolution is 3.4 mrad, and the maximum system acceptance is 6.4 x 10-1 cm · rad. A mechanism is designed to adjust the depth of parallelism between the slit and probe in order to improve the measurement accuracy. There is a water cooled structure in the slit plate, which can bear higher beam power. With fine shielding and rational second-electron suppressor, the current of the order of 10-10 A has been clearly measured. The relative error of the measured phase plots is about 8%. The system is useful to study the effects on the emittance, of electron energy, the grid pulse voltage, cathode temperature and pulse current intensity

  3. Designing power heterojunction bipolar transistors with non-uniform emitter finger lengths to achieve high thermal stability

    International Nuclear Information System (INIS)

    With the aid of a thermal-electrical model, a practical method for designing multi-finger power heterojunction bipolar transistors with finger lengths divided in groups is proposed. The method can effectively enhance the thermal stability of the devices without sacrificing the design time. Taking a 40-finger heterojunction bipolar transistor for example, the device with non-uniform emitter finger lengths is optimized and fabricated. Both the theoretical and the experimental results show that, for the optimum device, the peak temperature is lowered by 26.19 K and the maximum temperature difference is reduced by 56.67% when compared with the conventional heterojunction bipolar transistor with uniform emitter finger length. Furthermore, the ability to improve the uniformity of the temperature profile and to expand the thermal stable operation range is strengthened as the power level increases, which is ascribed to the improvement of the thermal resistance in the optimum device. A detailed design procedure is also summarized to provide a general guide for designing power heterojunction bipolar transistors with non-uniform finger lengths. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

    2011-06-16

    Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA), and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3-inch silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel, can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully-integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics.

  5. Performance comparisons of low emittance lattices

    International Nuclear Information System (INIS)

    In this paper, the results of a performance analysis of several low emittance electron storage ring lattices provided by various members of the Lattice Working Group are presented. Altogether, four lattices were investigated. There are two different functions being considered for the low beam emittance rings discussed here. The first is to serve as a Damping Ring (DR), i.e., to provide the emittance damping required for a high energy linear collider. The second is to provide beams for a short wavelength Free Electron Laser (FEL), which is envisioned to operate in the wavelength region near 40 A

  6. Facile Formation of High-Quality InGaN/GaN Quantum-Disks-in-Nanowires on Bulk-Metal Substrates for High-Power Light-Emitters.

    Science.gov (United States)

    Zhao, Chao; Ng, Tien Khee; Wei, Nini; Prabaswara, Aditya; Alias, Mohd S; Janjua, Bilal; Shen, Chao; Ooi, Boon S

    2016-02-10

    High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light-emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly on metal-substrates. The LEDs exhibited a low turn-on voltage of ∼2 V without efficiency droop up to injection current of 500 mA (1.6 kA/cm(2)) at ∼5 V. This is achieved through the direct growth and optimization of high-quality nanowires on titanium (Ti) coated bulk polycrystalline-molybdenum (Mo) substrates. We performed extensive studies on the growth mechanisms, obtained high-crystal-quality nanowires, and confirmed the epitaxial relationship between the cubic titanium nitride (TiN) transition layer and the hexagonal nanowires. The growth of nanowires on all-metal stack of TiN/Ti/Mo enables simultaneous implementation of n-metal contact, reflector, and heat sink, which greatly simplifies the fabrication process of high-power light-emitters. Our work ushers in a practical platform for high-power nanowires light-emitters, providing versatile solutions for multiple cross-disciplinary applications that are greatly enhanced by leveraging on the chemical stability of nitride materials, large specific surface of nanowires, chemical lift-off ready layer structures, and reusable Mo substrates. PMID:26745217

  7. Facile Formation of High-quality InGaN/GaN Quantum-disks-in-Nanowires on Bulk-Metal Substrates for High-power Light-emitters

    KAUST Repository

    Zhao, Chao

    2016-01-08

    High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly on metal-substrate. The LEDs exhibited a low turn-on voltage of ~2 V without efficiency droop up to injection current of 500 mA (1.6 kA/cm2) at ~5 V. This is achieved through the direct growth and optimization of high-quality nanowires on titanium (Ti) coated bulk polycrystalline-molybdenum (Mo) substrates. We performed extensive studies on the growth mechanisms, obtained high-crystal-quality nanowires, and confirmed the epitaxial relationship between the cubic titanium nitride (TiN) transition layer and the hexagonal nanowires. The growth of nanowires on all-metal stack of TiN/Ti/Mo enables simultaneous implementation of n-metal contact, reflector and heat-sink, which greatly simplifies the fabrication process of high-power light emitters. Our work ushers in a practical platform for high-power nanowires light emitters, providing versatile solutions for multiple cross-disciplinary applications that are greatly enhanced by leveraging on the chemical stability of nitride materials, large specific surface of nanowires, chemical lift-off ready layer structures, and reusable Mo substrates.

  8. Calculations of the high frequency cavity used to make a controlled blow-up of the longitudinal emittance in J-PARC MR

    International Nuclear Information System (INIS)

    RF cavities in J-PARC Main Ring (MR) has realized the high field gradient by using Magnetic Alloy (MA) cores. The fundamental frequency of RF cavity is 1.67 - 1.72 MHz, but one of the longitudinal bram emittance blow-up technique under consideration assumes use of a high frequency cavity of about 90 MHz. This frequency is very high for MA loaded RF cavities. In this frequency band, there was a VHF cavity used by AGS of Brookhaven National Laboratory and the frequency of VHF cavity was about 93 MHz. Therefore, we are examining the RF cavity suitable for J-PARC MR by using this VHF cavity as a reference. In this paper, we describe the outline of our cavity. (author)

  9. Alpha particle emitters in medicine

    International Nuclear Information System (INIS)

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 (211At) and natural bismuth-212 (212Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 (223Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs

  10. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  11. A billion-dollar bonanza

    International Nuclear Information System (INIS)

    In late May -- only weeks after Congress had rejected the president's economic stimulus package because it would add to the federal deficit -- the House of Representatives generously allocated an extra $1.2 billion to the Pentagon. This article discusses some of the rationalizations House members gave for the gift and describes the attempts of a bipartisan group to defeat this request for funds propounded by Pennsylvania Democrat John Murtha. This gist of the arguments for and against the $1.2 billion and the results of votes on the bill are presented

  12. Treatment of solid waste highly contaminated by alpha emitters: recent developments of leaching process with continuous electrolyte regeneration

    International Nuclear Information System (INIS)

    Development of processes for leaching solid waste contaminated by alpha or alpha/beta/gamma emitters has been pursued at the Nuclear Research Center in Fontenay-aux-Roses, France with the recent active commissioning of two pilot facilities: the Elise glove box system in February 1987 and the Prolixe shielded hot cell in March 1988. The Elise facility is designed to handle alpha waste and the Prolixe facility is designed to handle alpha/beta/gamma waste. The common goal of the studies conducted in these facilities is to define the operating conditions for declassification of solid waste, i.e. to ensure that the alpha concentration of this waste will be less than 3.7 x 106 Bq/kg after treatment, packaging and decay prior to storage in surface repositories. The leaching process developed is mainly based on the continuous electrolytic regeneration of an aggressive agent, AgII, which can induce the dissolution of PuO2, the most difficult compound to remove from the solid waste. This paper summarizes recent achievements in the development of this process

  13. Highly efficient and electrically robust carbon irradiated semi-insulating GaAs based photoconductive terahertz emitters

    International Nuclear Information System (INIS)

    We demonstrate here an efficient photoconductive THz source with low electrical power consumption. We have increased the maximum THz radiation power emitted from SI-GaAs based photoconductive emitters (PCEs) by two orders of magnitude. By irradiating the SI-GaAs substrate with Carbon-ions up to 2 μm deep, we have created lot of defects and decreased the lifetime of photo-excited carriers inside the substrate. Depending on the irradiation dose, we find 1 to 2 orders of magnitude decrease in total current flowing in the substrate, resulting in subsequent decrease of heat dissipation in the device. This has resulted in increasing maximum cut-off of the applied voltage across PCE electrodes to operate the device without thermal breakdown from ∼35 V to >150 V for the 25 μm electrode gaps. At optimum operating conditions, carbon irradiated (1014 ions/cm2) PCEs give THz pulses with power about 100 times higher in comparison to the usual PCEs on SI-GaAs and electrical to THz power conversion efficiency has improved by a factor of ∼800

  14. Highly efficient and electrically robust carbon irradiated semi-insulating GaAs based photoconductive terahertz emitters

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Abhishek; Pal, Sanjoy; Surdi, Harshad; Prabhu, S. S., E-mail: prabhu@tifr.res.in; Nanal, Vandana; Pillay, R. G. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2014-02-10

    We demonstrate here an efficient photoconductive THz source with low electrical power consumption. We have increased the maximum THz radiation power emitted from SI-GaAs based photoconductive emitters (PCEs) by two orders of magnitude. By irradiating the SI-GaAs substrate with Carbon-ions up to 2 μm deep, we have created lot of defects and decreased the lifetime of photo-excited carriers inside the substrate. Depending on the irradiation dose, we find 1 to 2 orders of magnitude decrease in total current flowing in the substrate, resulting in subsequent decrease of heat dissipation in the device. This has resulted in increasing maximum cut-off of the applied voltage across PCE electrodes to operate the device without thermal breakdown from ∼35 V to >150 V for the 25 μm electrode gaps. At optimum operating conditions, carbon irradiated (10{sup 14} ions/cm{sup 2}) PCEs give THz pulses with power about 100 times higher in comparison to the usual PCEs on SI-GaAs and electrical to THz power conversion efficiency has improved by a factor of ∼800.

  15. High-efficiency screen-printed solar cell on edge-defined film-fed grown ribbon silicon through optimized rapid belt co-firing of contacts and high-sheet-resistance emitter

    Science.gov (United States)

    Rohatgi, Ajeet; Hilali, Mohamed M.; Nakayashiki, Kenta

    2004-04-01

    High-quality screen-printed contacts were achieved on a high-sheet-resistance emitter (˜100 Ω/sq.) using PV168 Ag paste and rapid co-firing in the belt furnace. The optimized co-firing cycle developed for a 100 Ω/sq. emitter produced 16.1% efficient 4 cm2 planar edge-defined film-fed grown (EFG) ribbon Si cells with a low series-resistance (0.8 Ω cm2), high fill factor of ˜0.77, along with very significant bulk lifetime enhancement from 3 to 100 μs. This represents the highest-efficiency screen-printed EFG Si cells with single-layer antireflection (AR) coating. These cells were fabricated using a simple process involving POCl3 diffusion for a high-sheet-resistance emitter, SiNx AR coating and rapid cofiring of Ag grid and Al-doped back-surface field in a conventional belt furnace. The rapid cofiring process also prevented junction shunting while maintaining very effective SiNx-induced hydrogen passivation of defects, resulting in an average bulk lifetime exceeding 100 μs.

  16. Four billion people facing severe water scarcity

    OpenAIRE

    Mesfin M. Mekonnen; Arjen Y. Hoekstra

    2016-01-01

    Freshwater scarcity is increasingly perceived as a global systemic risk. Previous global water scarcity assessments, measuring water scarcity annually, have underestimated experienced water scarcity by failing to capture the seasonal fluctuations in water consumption and availability. We assess blue water scarcity globally at a high spatial resolution on a monthly basis. We find that two-thirds of the global population (4.0 billion people) live under conditions of severe water scarcity at lea...

  17. Investigation of the high-spin rotational properties of the proton emitter $^{113}$Cs using a particle-number conserving method

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The recently observed two high-spin rotational bands in the proton emitter $^{113}$Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 ($\\pi 3/2^+[422], \\alpha = -1/2$) and band 2 ($\\pi 1/2^+[420], \\alpha = 1/2$), the experimental moments of inertia and quasiparticle alignments can be well reproduced by the present calculations, which in turn strongly support these configuration assignments. Furthermore, by analyzing the occupation probability $n_\\mu$ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.

  18. Intelligent Variable Emittance Panels Using New, ""True"" Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This work further developed a highly promising Variable Emittance technology for spacecraft thermal control based on Conducting Polymer (CP) electrochromics...

  19. Four billion people facing severe water scarcity.

    Science.gov (United States)

    Mekonnen, Mesfin M; Hoekstra, Arjen Y

    2016-02-01

    Freshwater scarcity is increasingly perceived as a global systemic risk. Previous global water scarcity assessments, measuring water scarcity annually, have underestimated experienced water scarcity by failing to capture the seasonal fluctuations in water consumption and availability. We assess blue water scarcity globally at a high spatial resolution on a monthly basis. We find that two-thirds of the global population (4.0 billion people) live under conditions of severe water scarcity at least 1 month of the year. Nearly half of those people live in India and China. Half a billion people in the world face severe water scarcity all year round. Putting caps to water consumption by river basin, increasing water-use efficiencies, and better sharing of the limited freshwater resources will be key in reducing the threat posed by water scarcity on biodiversity and human welfare. PMID:26933676

  20. Cancer from internal emitters

    International Nuclear Information System (INIS)

    Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of 226Ra or medical injections of 224Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes

  1. Growth of GaN-based non- and semipolar heterostructures for high efficiency light emitters; Wachstum von nicht- und semipolaren InAIGaN-Heterostrukturen fuer hocheffiziente Lichtemitter

    Energy Technology Data Exchange (ETDEWEB)

    Wernicke, Tim

    2010-07-01

    Optoelectronic devices based on GaN and its alloys InGaN and AlGaN are capable of emitting light from the visible to the ultraviolet spectral region. Blue and green lasers have applications in laser projectors, DNA sequencing and spectroscopy. But it is extremely difficult to fabricate green laser diodes. Currently almost all of the light emitting diodes (LEDs) and lasers are grown on GaN crystals that are oriented in the polar (0001) c-plane direction, which provides the most stable growth surface. However the resulting polarization fields on (0001)GaN have detrimental effects on the optical properties of nitride light emitters, e.g. causing significant wavelength shifts and reduced efficiencies in InGaN LEDs. Growth on crystal surfaces with non- and semipolar orientations, e.g. (10 anti 10) m-plane or (11 anti 22), could enable devices with new and improved optical properties. For example, for nonpolar and semipolar LEDs the degree of polarization of the emitted light can be tailored. Furthermore easier to grow devices with green light emission, since the indium incorporation is enhanced for semipolar orientations. In contrast to c-plane GaN there is no polarization field across quantum wells on nonpolar GaN. By reducing the polarization fields an increase in the radiative recombination rate can be expected and would lead to higher LED efficiencies and lower laser thresholds. One of the biggest challenges for the growth of light emitters on non- and semipolar GaN is the choice of a suitable substrate: Heteroepitaxial growth on sapphire or LiAlO{sub 2} allows the deposition of GaN on 2'' diameter wafers and larger. However, these layers show a very high defect density in particular basal plane stacking faults, in comparison to c-plane GaN on sapphire. In order to reduce the defect density we applied successfully epitaxial lateral overgrowth to heteroepitaxial nonpolar a-plane GaN and verified the improvement by spatially and spectrally

  2. RFI emitter location techniques

    Science.gov (United States)

    Rao, B. L. J.

    1973-01-01

    The possibility is discussed of using Doppler techniques for determining the location of ground based emitters causing radio frequency interference with low orbiting satellites. An error analysis indicates that it is possible to find the emitter location within an error range of 2 n.mi. The parameters which determine the required satellite receiver characteristic are discussed briefly along with the non-real time signal processing which may by used in obtaining the Doppler curve. Finally, the required characteristics of the satellite antenna are analyzed.

  3. PENCIL LEAD FIELD EMITTER

    OpenAIRE

    Khairnar, R.; Joag, D.

    1989-01-01

    Field electron emission from 2H and HB grades of pencil lead has been studied. The pencil lead field emitter is found to obey the Fowler-Nordheim characteristics. The emission current fluctuations are found to increase with the residual gas pressure and the emission current. The current density of the order of 106 amp/cm2 could be drawn from these emitters. The emission stability over the operation of six hours has been found to be reasonably good. The field ion microscopy of the 2H and HB gr...

  4. Polyaniline: a conductive polymer coating for durable nanospray emitters

    Science.gov (United States)

    Maziarz; Lorenz; White; Wood

    2000-07-01

    Despite the tremendous sensitivity and lower sample requirements for nanospray vs. conventional electrospray, metallized nanospray emitters have suffered from one of two problems: low mechanical stability (leading to emitter failure) or lengthy, tedious production methods. Here, we describe a simple alternative to metallized tips using polyaniline (PANI), a synthetic polymer well known for its high conductivity, anticorrosion properties, antistatic properties, and mechanical stability. A simple method for coating borosilicate emitters (1.2 mm o.d.) pulled to fine tapers (4 +/- 1 microm) with water-soluble and xylene-soluble dispersions of conductive polyaniline (which allows for electrical contact at the emitter outlet) is described. The polyaniline-coated emitters show high durability and are resistant to electrical discharge, likely because of the thick (yet optically transparent) coatings; a single emitter can be used over a period of days for multiple samples with no visible indication of the destruction of the polyaniline coating. The optical transparency of the coating also allows the user to visualize the sample plug loaded into the emitter. Examples of nanospray using coatings of the water-soluble and xylene-soluble polyaniline dispersions are given. A comparison of PANI-coated and gold-coated nanospray emitters to conventional electrospray ionization (ESI) show that PANI-coated emitters provide similar enhanced sensitivity that gold-coated emitters exhibit vs. conventional ESI. PMID:10883822

  5. Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter

    Science.gov (United States)

    Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos

    2015-11-01

    This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.

  6. Fibrous selective emitter structures from sol-gel process

    International Nuclear Information System (INIS)

    Selective emitters have the potential benefit of high efficiency due to the matching of emission spectra to the response of photovoltaic (PV) cells. Continuous uniform rare-earth oxide selective emitter fibers were successfully fabricated using a viscous solution made from metal organic precursors. Cylindrical- and planar configuration emitter structures were made by direct cross-winding or stacking of precursor fiber layers. The combustion and optical performance of the planar emitter structures were tested. The results indicates that both the designing of the fiber packing density and the thickness is critical for high photon and power output

  7. Thermal emittance measurements of a cesium potassium antimonide photocathode

    OpenAIRE

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-01-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56+/-0.03 mm-mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  8. Thermal emittance measurements of a cesium potassium antimonide photocathode

    Science.gov (United States)

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-05-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56±0.03 mm mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  9. Measuring emittance using beam position monitors

    International Nuclear Information System (INIS)

    The Los Alamos Advanced Free Electron Laser uses a high charge (greater than InC), low emittance (normalized rams emittance less than 5π mm mrad) photoinjector driven accelerator. The high brightness achieved is due, in large part, to the rapid acceleration of the electrons to relativistic velocities. As a result, the beam does not have time to thermalize its distribution and its universe profile is, in general, non-Gaussian. This, coupled with the very high brightness, makes it difficult to measure the transverse emittance. Techniques used must be able to withstand the rigors of very intense electron beams, and not be reliant on Gaussian assumptions. Beam position monitors are ideal for this. They are not susceptible to beam damage, and it has been shown previously that they can be used to measure the transverse emittance of a beam with a Gaussian profile. However, this Gaussian restriction is not necessary and, in fact, a transverse emittance measurement using beam position monitors is independent of the beam's distribution

  10. Muon Cooling—emittance exchange

    Science.gov (United States)

    Parsa, Zohreh

    2001-05-01

    Muon Cooling is the key factor in building of a Muon collider, (to a less degree) Muon storage ring, and a Neutrino Factory. Muon colliders potential to provide a probe for fundamental particle physics is very interesting, but may take a considerable time to realize, as much more work and study is needed. Utilizing high intensity Muon sources-Neutrino Factories, and other intermediate steps are very important and will greatly expand our abilities and confidence in the credibility of high energy muon colliders. To obtain the needed collider luminosity, the phase-space volume must be greatly reduced within the muon life time. The Ionization cooling is the preferred method used to compress the phase space and reduce the emittance to obtain high luminosity muon beams. We note that, the ionization losses results not only in damping, but also heating. The use of alternating solenoid lattices has been proposed, where the emittance are large. We present an overview of the cooling and discuss formalism, solenoid magnets and some beam dynamics.

  11. Low-emittance Storage Rings

    CERN Document Server

    Wolski, A

    2014-01-01

    The effects of synchrotron radiation on particle motion in storage rings are discussed. In the absence of radiation, particle motion is symplectic, and the beam emittances are conserved. The inclusion of radiation effects in a classical approximation leads to emittance damping: expressions for the damping times are derived. Then, it is shown that quantum radiation effects lead to excitation of the beam emittances. General expressions for the equilibrium longitudinal and horizontal (natural) emittances are derived. The impact of lattice design on the natural emittance is discussed, with particular attention to the special cases of FODO-, achromat- and theoretical-minimum-emittance-style lattices. Finally, the effects of betatron coupling and vertical dispersion (generated by magnet alignment and lattice tuning errors) on the vertical emittance are considered.

  12. Quarter One:36.25 Billion USD

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    From January to March,2007,China’s total international trade value was 457.74 billion US dollars,and the rise was 23.3% compared with last year.The import made to 205.65 billion US dollars and the export was 252.09 billion US dollars,up

  13. Directional Thermal Emitter Simulation

    OpenAIRE

    Dhaka, Shailja; Sakr, Enas Said; Bermel, Peter

    2015-01-01

    The development of renewable energy sources has attracted increasing interest because of negative externalities associated with fossil fuel use. Thermophotovoltaics is a promising technology, in which a thermal emitter radiates photons which are directly converted into electricity using a photovoltaic diode. However, blackbody emission includes a broad range of wavelengths, but only higher energy photons can be converted into electricity. Thus, tailoring the selectivity of thermal emission is...

  14. Realisation of a ultra-high vacuum system and technique development of microscopical emitters preparation in silicium. First measurements of field emission current and field photoemission

    International Nuclear Information System (INIS)

    The development of research in the domain of photocathode (electron sources) illuminated by laser light to produce intense multiple bunches of electrons in short time is needed by many applications as linear collider e+e-, free electron laser, lasertron, etc... In this way, after a study of field emission, of photoemission and of photofield emission, we prepared microscopical emitters in silicium heavy and weakly doped a boron using a technique of microlithography. Then, we realized a system of ultra-high vacuum of studying property of emission from photocathodes realized. The experiment results obtained in field emission and photofield emission have shown that a behaviour unexpected for P-silicium tips array compared to P+-silicon tips array. With P-type silicon, a quantum yield of 21 percent has been measured for laser power of 140 mW and for applied field of 1.125 x 107 V/m and an instantaneous response to laser light beam has been observed. It has been noted that presence of oxyde at the surface of photocathode limits extensively the emission current. The fluctuations of emission current are due to quality of vacuum

  15. Integrated photonic crystal selective emitter for thermophotovoltaics

    Science.gov (United States)

    Zhou, Zhiguang; Yehia, Omar; Bermel, Peter

    2016-01-01

    Converting blackbody thermal radiation to electricity via thermophotovoltaics (TPV) is inherently inefficient. Photon recycling using cold-side filters offers potentially improved performance but requires extremely close spacing between the thermal emitter and the receiver, namely a high view factor. Here, we propose an alternative approach for thermal energy conversion, the use of an integrated photonic crystal selective emitter (IPSE), which combines two-dimensional photonic crystal selective emitters and filters into a single device. Finite difference time domain and current transport simulations show that IPSEs can significantly suppress sub-bandgap photons. This increases heat-to-electricity conversion for photonic crystal based emitters from 35.2 up to 41.8% at 1573 K for a GaSb photovoltaic (PV) diode with matched bandgaps of 0.7 eV. The physical basis of this enhancement is a shift from a perturbative to a nonperturbative regime, which maximized photon recycling. Furthermore, combining IPSEs with nonconductive optical waveguides eliminates a key difficulty associated with TPV: the need for precise alignment between the hot selective emitter and cool PV diode. The physical effects of both the IPSE and waveguide can be quantified in terms of an extension of the concept of an effective view factor.

  16. Theoretical study of transverse-longitudinal emittance coupling

    Energy Technology Data Exchange (ETDEWEB)

    Qin, H; Davidson, R C; Chung, M; Barnard, J J; Wang, T F

    2011-04-14

    The effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions is investigated using the generalized Courant-Snyder theory for coupled lattices. Recently, the concept and technique of transverse-longitudinal emittance coupling have been proposed for applications in the Linac Coherent Light Source and other free-electron lasers to reduce the transverse emittance of the electron beam. Such techniques can also be applied to the driver beams for the heavy ion fusion and beam-driven high energy density physics, where the transverse emittance budget is typically tighter than the longitudinal emittance. The proposed methods consist of one or several coupling components which completely swap the emittances of one of the transverse directions and the longitudinal direction at the exit of the coupling components. The complete emittance exchange is realized in one pass through the coupling components. In the present study, we investigate the effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions. A weak coupling component is introduced at every focusing lattice, and we would like to determine if such a lattice can realize the function of emittance exchange.

  17. High-Performance Blue OLEDs Based on Phenanthroimidazole Emitters via Substitutions at the C6- and C9-Positions for Improving Exciton Utilization.

    Science.gov (United States)

    Liu, Bin; Yuan, Yi; He, Dan; Huang, De-Yue; Luo, Cheng-Yuan; Zhu, Ze-Lin; Lu, Feng; Tong, Qing-Xiao; Lee, Chun-Sing

    2016-08-16

    Donor-acceptor (D-A) molecular architecture has been shown to be an effective strategy for obtaining high-performance electroluminescent materials. In this work, two D-A molecules, Ph-BPA-BPI and Py-BPA-BPI, have been synthesized by attaching highly fluorescent phenanthrene or pyrene groups to the C6- and C9-positions of a locally excited-state emitting phenylamine-phenanthroimidazole moiety. Equipped with good physical and hybridized local and charge-transfer properties, both molecules show high performances as blue emitters in nondoped organic light-emitting devices (OLEDs). An OLED using Ph-BPA-BPI as the emitting layer exhibits deep-blue emission with CIE coordinates of (0.15, 0.08), and a maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 4.56 %, 3.60 cd A(-1) , and 3.66 lm W(-1) , respectively. On the other hand, a Py-BPA-BPI-based, sky-blue OLED delivers the best results among nondoped OLEDs with CIEy values of < 0.3 reported so far, for which a very low turn-on voltage of 2.15 V, CIE coordinates of (0.17, 0.29), and maximum CE, PE, and EQE values of 10.9 cd A(-1) , 10.5 lm W(-1) , and 5.64 %, were achieved, respectively. More importantly, both devices show little or even no efficiency roll-off and high singlet exciton-utilizing efficiencies of 36.2 % for Ph-BPA-BPI and 39.2 % for Py-BPA-BPI. PMID:27412733

  18. Carbon Nanotube-based Cold Cathode for High Power MicrowaveVacuum Electronic Devices: A Potential Field Emitter

    OpenAIRE

    Verma, P.; S Gautam; Pal, S.; Kumar, P.; Chaturvedi, P; J.S.B.S. Rawat; P. K. Chaudhary; Dr. Harsh; Basu, P K; P. K. Bhatanagar

    2008-01-01

    Carbon nanotubes (CNTs) can be grown in the form of small, sharp spikes capable of carrying very highcurrent densities which suggest great potential application of CNTs as cold cathode in high power microwavevacuum device applications. These cold cathode vacuum microwave devices are expected to be ideally suitedfor air-borne and space applications. This paper  reports the initial efforts made in the development of coldcathode using PECVD grown vertically-aligned matrix of CNTs with uniform he...

  19. Carbon Nanotube-based Cold Cathode for High Power MicrowaveVacuum Electronic Devices: A Potential Field Emitter

    Directory of Open Access Journals (Sweden)

    P. Verma

    2008-09-01

    Full Text Available Carbon nanotubes (CNTs can be grown in the form of small, sharp spikes capable of carrying very highcurrent densities which suggest great potential application of CNTs as cold cathode in high power microwavevacuum device applications. These cold cathode vacuum microwave devices are expected to be ideally suitedfor air-borne and space applications. This paper  reports the initial efforts made in the development of coldcathode using PECVD grown vertically-aligned matrix of CNTs with uniform height and optimum tip densityon silicon substrate. The high aspect ratio (of the order of 10,000 and novel electrical, mechanical, and thermalproperties of the CNT are found to be very attractive characteristics for emission of large and stable currentdensities at reasonably low field. The field emission current voltage characteristics of a typical cathode gaveemission current density in excess of 35 mA/cm2 at reasonably low field. The emission current in most of thesamples is found to be stable over long period of time but is greatly effected by the vacuum condition duringmeasurement. The initial measured data suggests great promise for achieving high current densities at practicalelectric fields.Defence Science Journal, 2008, 58(5, pp.650-654, DOI:http://dx.doi.org/10.14429/dsj.58.1688

  20. Color-converting combinations of nanocrystal emitters for warm-white light generation with high color rendering index

    Science.gov (United States)

    Nizamoglu, Sedat; Zengin, Gulis; Demir, Hilmi Volkan

    2008-01-01

    Warm-white light emitting diodes with high color rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid light sources that incorporate the right color-converting combinations of CdSe /ZnS core-shell nanocrystals hybridized on InGaN /GaN LEDs for high color rendering index. Three sets of proof-of-concept devices are developed to generate high-quality warm-white light with (1) tristimulus coordinates (x,y)=(0.37,0.30), luminous efficacy (LE)=307lm/W, color rending index (CR)=82.4, and correlated color temperature (CCT)=3228K; (2) (x,y)=(0.38,0.31), LE =323lm/W, CRI =81.0, and CCT =3190K; and (3) (x,y)=(0.37,0.30), LE =303lm/W, CRI =79.6, and CCT =1982K.

  1. Development of high sensitivity spectrometric alpha emitter detector for use in monitoring of environment and radio protection

    International Nuclear Information System (INIS)

    The aim of the project was to design and construct a prototype of a reliable high sensitivity alpha particle detector which will complement solid state track detectors in applications which require superior energy resolution and in which the need for etching is inappropriate. A multiwire proportional chamber of alpha particles was developed that is adaptable for samples deposited onto carriers or introduced in a gaseous form. The final report covers in fact the whole duration of the project with a particular attention to the work done during the last year. (R.P.) 7 refs., 8 figs

  2. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    Science.gov (United States)

    Wang, Daojing; Yang, Peidong; Kim, Woong; Fan, Rong

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  3. An erbium(III)-based NIR emitter with a highly conjugated β-diketonate for blue-region sensitization

    Energy Technology Data Exchange (ETDEWEB)

    Martín-Ramos, P., E-mail: pablomartinramos@gmail.com [Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Department of Physics and MALTA Consolider Team, Universidad de La Laguna, E-38206 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Martín, I.R.; Lahoz, F. [Department of Physics and MALTA Consolider Team, Universidad de La Laguna, E-38206 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Hernández-Navarro, S. [Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Pereira da Silva, P.S. [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, P-3004-516 Coimbra (Portugal); Hernández, I. [CITIMAC Dept., Facultad de Ciencias, University of Cantabria, Avenida Los Castros s/n, 39005 Santander (Spain); School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Lavín, V. [Department of Physics and MALTA Consolider Team, Universidad de La Laguna, E-38206 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Ramos Silva, M. [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, P-3004-516 Coimbra (Portugal)

    2015-01-15

    Highlights: • A new highly coordinated Er{sup 3+} complex has been synthesized and its properties studied. • X-ray diffraction shows that complex packs efficiently: no solvent accessible voids. • dnm ligand successfully extends the excitation bands to the blue region up to 550 nm. • Efficient energy transfer by antenna effect results in 1.53 μm emission from Er{sup 3+}. - Abstract: The sensitization of lanthanide complexes in the visible region is of particular interest for practical applications such as labeling, biological analysis and optoelectronics. A visible-light sensitized Er{sup 3+} complex based on the use of a highly conjugated β-diketonate (1,3-di(2-naphthyl)-1,3-propanedione, Hdnm) and 5-nitro-1,10-phenanthroline (5NO{sub 2}phen) as an ancillary ligand, [Er(dnm){sub 3}(5NO{sub 2}phen)], has been synthesized, fully characterized and its photophysical properties have been investigated. Suitably expanded π-conjugation in the complex molecule makes the excitation window red-shifted to the visible region (up to 550 nm). Efficient energy transfer by antenna effect results in 1.53 μm emission from the Er{sup 3+} ion.

  4. Fine Structure in the Decay of the Highly Deformed Proton Emitter E number-sign131u

    International Nuclear Information System (INIS)

    Fine structure in the ground-state proton radioactive decay of highly deformed 131Eu has been identified. In addition to the previously observed ground-state line, measured here with a proton energy of 932(7) keV, a second proton peak with energy 811(7) keV was observed. We interpret this line as proton decay from the 131Eu ground state to the first excited 2+ state of the daughter nucleus 130Sm . Comparing the measured branching ratio with calculations enables the ground-state configuration of 131Eu to be unambiguously assigned to the 3/2+ [411] Nilsson configuration. copyright 1999 The American Physical Society

  5. Performance of wire scanner beam profile monitors to determine the emittance and position of high power CW electron beams of the NBS-Los Alamos racetrack microtron

    International Nuclear Information System (INIS)

    The NBS-LANL Race Track Microtron (RTM) injector produces a sub-millimeter diameter, 600 μA, 5 MeV CW electron beam. In order to steer and focus this electron beam and to measure its emittance and energy spread, a system of wire scanner beam profile monitors has been developed. Three wire scanners are mounted in a straight line with approximately one meter spacing for emittance measurements. The fourth wire scanner is positioned after a 450 bending magnet for energy spread measurements

  6. High Power Beam Test and Measurement of Emittance Evolution of a 1.6-Cell Photocathode RF Gun at Pohang Accelerator Laboratory

    Science.gov (United States)

    Park, Jang-Ho; Park, Sung-Ju; Kim, Changbum; Parc, Yong-Woon; Hong, Ju-Ho; Huang, Jung-Yun; Xiang, Dao; Wang, Xijie; Ko, In Soo

    2007-04-01

    A Brookhaven National Laboratory (BNL) GUN-IV type photocathode rf gun has been fabricated to use in femtosecond electron diffraction (FED), femtosecond far infrared radiation (fs-FIR) facility, and X-ray free electron laser (XFEL) facilities at the Pohang Accelerator Laboratory (PAL). The gun consists of a 1.6-cell cavity with a copper cathode, a solenoid magnet, beam diagnostic components and auxiliary systems. We report here the measurement of the basic beam parameters which confirm a successful fabrication of the photocathode RF gun system. The emittance evolution is measured by an emittance meter and compared with the PARMELA simulation, which shows a good agreement.

  7. A High Fraction of Ly-alpha-Emitters Among Galaxies with Extreme Emission Line Ratios at z ~ 2

    CERN Document Server

    Erb, Dawn K; Steidel, Charles C; Strom, Allison L; Rudie, Gwen C; Trainor, Ryan F; Shapley, Alice E; Reddy, Naveen A

    2016-01-01

    Star-forming galaxies form a sequence in the [OIII]/H-beta vs. [NII]/H-alpha diagnostic diagram, with low metallicity, highly ionized galaxies falling in the upper left corner. Drawing from a large sample of UV-selected star-forming galaxies at z~2 with rest-frame optical nebular emission line measurements from Keck-MOSFIRE, we select the extreme ~5% of the galaxies lying in this upper left corner, requiring log([NII]/H-alpha) = 0.75. These cuts identify galaxies with 12 + log(O/H) 20 A. We compare the equivalent width distribution of a sample of 522 UV-selected galaxies at 2.0

  8. High flow air sampling for determination of alpha long half-life emitters: area monitoring of a radioactive material disposal

    International Nuclear Information System (INIS)

    The Ore Treatment Unit (UTM) is a mine and closed uranium plant, located in Caldas, Minas Gerais, Brazil. It has a radioactive material disposal composed primarily of pie II and mesothorium. It is stored in six sheds designated C-01, C-02, C-05, C-06, C-07 and C-09. This study aims to present the high flow area monitoring program and results obtained in 2009. The threshold derived from concentration in the air was 0.25 Bq m-3. The average of the activity concentrations in 2009 were: for C-01 1.17 Bq m-3; C-02 0.006 Bq m-3; C-05 1.98 Bq m-3; C-06 2.14 Bq m-3; C-07 0.34 Bq m-3 and C-09 0,025 Bq m-3. Such values indicate that the control stay is an important factor in occupational workers' control, as well as the use of EPI's and behavioral care, besides radioprotection training to allow the access to the areas. No worker, supervisor or visitor reached the limit research

  9. Emittance Measurements for Beams Extracted from LECR3 Ion Source

    Institute of Scientific and Technical Information of China (English)

    CaoYun; ZhaoHongwei; MaLei; ZhangZimin

    2003-01-01

    High quality ion beams are required by IMP cyclotron and atomic physics research, so it is important to research and measure beam emitt ance of ECR ion source. Intense beams extracted from ECR ion source usually have low energy, so it is suitable to use Electric-Sweep Scanner to measure the emittance. This kind of measurement is popularly used at ECR ion source, and it has some prominent merits such as high accuracy, very short time of data processing and easy expressing of the emittance pattern. So we designed and built this emittance scanner to measure emittance of the ion beams produced by LECR3 ion source. The structure of the ESS is shown in Fig.l, and the photo of the ESS is shown in Fig.2.

  10. Imaging optimizations with non-pure and high-energy positron emitters in small animal positron computed tomography; Optimierung der Bildgebung mit nichtreinen und hochenergetischen Positronenstrahlern in der Kleintier-Positronen-Emissions-Tomographie

    Energy Technology Data Exchange (ETDEWEB)

    Harzmann, Sophie

    2014-03-21

    The contribution on imaging optimizations with non-pure and high-energy positron emitters in small animal positron emission tomography (PET) covers the following topics: physical fundamentals of PET, mathematical image reconstruction and data analyses, Monte-Carlo simulations and implemented correction scheme, quantification of cascade gamma coincidences based on simulations and measurements, sinogram based corrections, restoration of the spatial resolution, implementation of full corrections.

  11. Endemic Cardiovascular Diseases of the Poorest Billion.

    Science.gov (United States)

    Kwan, Gene F; Mayosi, Bongani M; Mocumbi, Ana O; Miranda, J Jaime; Ezzati, Majid; Jain, Yogesh; Robles, Gisela; Benjamin, Emelia J; Subramanian, S V; Bukhman, Gene

    2016-06-14

    The poorest billion people are distributed throughout the world, though most are concentrated in rural sub-Saharan Africa and South Asia. Cardiovascular disease (CVD) data can be sparse in low- and middle-income countries beyond urban centers. Despite this urban bias, CVD registries from the poorest countries have long revealed a predominance of nonatherosclerotic stroke, hypertensive heart disease, nonischemic and Chagas cardiomyopathies, rheumatic heart disease, and congenital heart anomalies, among others. Ischemic heart disease has been relatively uncommon. Here, we summarize what is known about the epidemiology of CVDs among the world's poorest people and evaluate the relevance of global targets for CVD control in this population. We assessed both primary data sources, and the 2013 Global Burden of Disease Study modeled estimates in the world's 16 poorest countries where 62% of the population are among the poorest billion. We found that ischemic heart disease accounted for only 12% of the combined CVD and congenital heart anomaly disability-adjusted life years (DALYs) in the poorest countries, compared with 51% of DALYs in high-income countries. We found that as little as 53% of the combined CVD and congenital heart anomaly burden (1629/3049 DALYs per 100 000) was attributed to behavioral or metabolic risk factors in the poorest countries (eg, in Niger, 82% of the population among the poorest billion) compared with 85% of the combined CVD and congenital heart anomaly burden (4439/5199 DALYs) in high-income countries. Further, of the combined CVD and congenital heart anomaly burden, 34% was accrued in people under age 30 years in the poorest countries, while only 3% is accrued under age 30 years in high-income countries. We conclude although the current global targets for noncommunicable disease and CVD control will help diminish premature CVD death in the poorest populations, they are not sufficient. Specifically, the current framework (1) excludes deaths of

  12. Effect of plasmonic near field on the emittance of plasmon-enhanced photocathode

    CERN Document Server

    Jiang, Zeng-gong; Li, Xu-dong; Zhang, Meng; Gu, Duan

    2016-01-01

    The introduction of the surface plasmon polarizations makes the emittance of the photocathode complicated. In this paper, the emittance of plasmon-enhanced photocathode is analyzed. It is first demonstrated that the plasmonic near field can increase the emittance of the plasmon-enhanced photocathode. A simulation method has been used to estimate the emittance caused by plasmonic near field, and the suppression method also has been discussed, both of which are significant for the design of high performance plasmon-enhanced photocathode.

  13. Effect of high sheet-resistance emitter on mono-crystalline silicon solar cells performance%高方块电阻发射区对单晶硅太阳电池性能影响

    Institute of Scientific and Technical Information of China (English)

    沈洲; 沈鸿烈; 马跃; 夏正月; 陈军

    2012-01-01

    研究通过提高发射区的方块电阻和采用合适的工艺技术,制备了性能优良的单晶硅太阳电池.采用丝网印刷技术制备了40 Ω/□常规发射区和60 Ω/□高方块电阻发射区单晶硅太阳电池并对其性能进行了分析研究.扩展电阻法分析表明:60Ω/□发射区的表面活性磷杂质浓度和结深比40Ω/□发射区的分别降低了12.8%和14.9%.尽管60 Ω/□发射区太阳电池的串联电阻增加了0.141 Ω/cm2导致填充因子下降了1.24%,但是短路电流密度和开路电压分别提高了1.31 mA/cm2和1.2 mV,最终转换效率仍然提高了0.4%.%The high quality mono-crystalline silicon solar cells were achieved by increasing the sheet-resistance of the emitters and using the favorable technology processing. The mono-crystalline silicon solar cells with 40 ft/D and 60 ft/D emitters were fabricated with screen-printed contacts and their properties were studied. The spreading resistance profiles analysis shows that there is a 12.8% decrease in the surface active phosphorus concentration and a 14.9% decrease in the junction depth for mono-crystalline silicon solar cells with 60 fl/D emitter compared with the conventional solar cells with 40 ft/ □ emitter. The mono-crystalline silicon solar cells with 60 ft/ □ emitter demonstrate an improvement of 1.31 mA/cm2 in short current density, 1.2 mV in open-circuit voltage, and thus 0.4% higher in energy conversion efficiency, in spite of a 1.24% loss in fill factor resulted from a 0.141 ft/cm2 increase in series resistance compared with the conventional solar cells with 40 ft/D emitter.

  14. Spectral beam combining of multi-single emitters

    Science.gov (United States)

    Wang, Baohua; Guo, Weirong; Guo, Zhijie; Xu, Dan; Zhu, Jing; Zhang, Qiang; Yang, Thomas; Chen, Xiaohua

    2016-03-01

    Spectral beam combination expands the output power while keeps the beam quality of the combined beam almost the same as that of a single emitter. Spectral beam combination has been successfully achieved for high power fiber lasers, diode laser arrays and diode laser stacks. We have recently achieved the spectral beam combination of multiple single emitter diode lasers. Spatial beam combination and beam transformation are employed before beams from 25 single emitter diode lasers can be spectrally combined. An average output power about 220W, a spectral bandwidth less than 9 nm (95% energy), a beam quality similar to that of a single emitter and electro-optical conversion efficiency over 46% are achieved. In this paper, Rigorous Coupled Wave analysis is used to numerically evaluate the influence of emitter width, emitter pitch and focal length of transform lens on diffraction efficiency of the grating and spectral bandwidth. To assess the chance of catastrophic optical mirror damage (COMD), the optical power in the internal cavity of a free running emitter and the optical power in the grating external cavity of a wavelength locked emitter are theoretically analyzed. Advantages and disadvantages of spectral beam combination are concluded.

  15. Homoleptic Tris-Cyclometalated Iridium Complexes with Substituted o-Carboranes: Green Phosphorescent Emitters for Highly Efficient Solution-Processed Organic Light-Emitting Diodes.

    Science.gov (United States)

    Kim, Yejin; Park, Sunghee; Lee, Young Hoon; Jung, Jaehoon; Yoo, Seunghyup; Lee, Min Hyung

    2016-01-19

    Homoleptic tris-cyclometalated iridium complexes, fac-Ir[5-(2-RCB)ppy]3 (3a-3c; CB = o-carboran-1-yl; ppy = 2-phenylpyridinato-C(2),N; R = H (3a), Me (3b), (i)Bu (3c)) with 2-R-substituted o-carboranes at the 5-position of the ppy ligand, were prepared and characterized. X-ray diffraction analysis of 3a and 3c revealed that the three C^N ligands adopt a fac-arrangement around the Ir atom and that the carboranyl C-C bond distance increases with increasing steric effects of the 2-R substituent. The phosphorescence wavelengths of the complexes were apparently blue-shifted by ca. 20 nm (λem = 487-493 nm) compared to that of the parent fac-Ir(ppy)3 (4; λem = 508 nm). In particular, 3a-3c were highly emissive in toluene, and the phosphorescence quantum efficiencies of 3a and 3b (ΦPL = 0.95-0.98) were comparable to that of 4. Solution-processed electroluminescent devices incorporating 3a-3c as emitters displayed green light with high performance, and devices based on the 3c dopant showed the highest performance. In particular, the devices based on 3c exhibited performance more than double of that of the device based on 4 in terms of current efficiency (29.6 cd/A for 3c vs 15.8 cd/A for 4 at 4 wt % Ir and 1000 cd/m(2)), power efficiency (11.0 lm/W for 3c vs 6.3 lm/W for 4), and external quantum efficiency (10.2% for 3c vs 4.7% for 4) over a wide range of luminance. The higher PL quantum yields of doped host films with 3c than those with 4 at high dopant concentrations above 8 wt % suggested that along with high phosphorescence quantum efficiency, the steric bulkiness of the 2-(i)Bu-substituted o-carborane in 3c plays a crucial role in improving device performance. PMID:26741792

  16. Beam phase space and emittance

    International Nuclear Information System (INIS)

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation and to treat two particular examples

  17. Emittance growth in rf linacs

    International Nuclear Information System (INIS)

    As the space-charge limit is approached, the current that can be accelerated in an rf linac and the output emittance that can be expected are discussed. The role of the envelope equations to estimate limits is outlined. The results of numerical experiments to explore general properties of emittance growth are given

  18. Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector

    CERN Document Server

    Thangaraj, Jayakar C T; Johnson, A; Lumpkin, A H; Edwards, H; Ruan, J; Santucci, J; Sun, Y E -; Church, M; Piot, P

    2012-01-01

    Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at the A0 photoinjector.

  19. Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, Jayakar C.T.; Thurman-Keup, R.; Johnson, A.; Lumpkin, A.H.; Edwards, H.; Ruan, J.; Santucci, J.; Sun, Y.E.-; Church, M.; /Fermilab; Piot, P.; /Fermilab /Northern Illinois U.

    2010-08-01

    Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchanger to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at A0 photoinjector.

  20. THz imaging system with the IJJ emitter

    Science.gov (United States)

    Tsujimoto, Manabu; Minami, Hidetoshi; Sawamura, Masashi; Delfanazari, Kaveh; Yamamoto, Takashi; Kashiwagi, Takanari; Kadowaki, Kazuo

    2011-03-01

    The intrinsic Josephson junction (IJJ) emitter consisted of thousands of IJJs uniformly stacked in single crystalline high-Tc superconductor Bi 2 Sr 2 CaCu 2 O8 + δ (Bi-2212) [L. Ozyuzer et al., Science 318, (2007) 1291.] is expected to be a novel source of the continuous terahertz electromagnetic waves (THz-waves). The maximum emission power of tens of microwatts recently obtained with the mesa structure of IJJs seems to be sufficient to make use of the IJJ emitter for some practical applications such as THz imaging. According to the cavity resonance condition, we can control the radiation frequency by changing the geometrical size of the mesa. In this study, we develop the THz imaging system with IJJ emitter. In the presentation, we will show some transparent images of standard specimens obtained by the raster scanning method. Also, we will mention some problems to be solved for the future applications of the IJJ emitter. CREST-JST, WPI-MANA, Strategic Initiative A (University of Tsukuba).

  1. State carries takes another billions from SPP

    International Nuclear Information System (INIS)

    Financial aspects of activities of the SPP, a.s. are analysed. Economising of SPP of last year means income of 7.8 billions Slovak crowns for exchequer. Besides 3.9 billion of last year's taxes from income the state benefits will be doubled this year. The reason of increase are the dividends which account for 51% share of profit after distinctive deliveries from record clean profit of 8.7 billions Slovak crowns. Dividing of company profit, which doubled in last year to 12.6 billions Slovak crowns was adopted by shareholders in the last week at general assembly of SPP. Gaz de France and Ruhrgas who really began to manage the company in the second half of 2002 will divide remaining 3.7 billions Slovak crowns. (Author)

  2. Evidence for high-energy and low-emittance electron beams using ionization injection of charge in a plasma wakefield accelerator

    CERN Document Server

    Vafaei-Najafabadi, N; Clayton, C E; Joshi, C; Marsh, K A; Mori, W B; Welch, E C; Lu, W; Adli, E; Allen, J; Clarke, C I; Corde, S; Frederico, J; Gessner, S J; Green, S Z; Hogan, M J; Litos, M D; Yakimenko, V

    2015-01-01

    Ionization injection in a plasma wakefield accelerator was investigated experimentally using two lithium plasma sources of different lengths. The ionization of the helium gas, used to confine the lithium, injects electrons in the wake. After acceleration, these injected electrons were observed as a distinct group from the drive beam on the energy spectrometer. They typically have a charge of tens of pC, an energy spread of a few GeV, and a maximum energy of up to 30 GeV. The emittance of this group of electrons can be many times smaller than the initial emittance of the drive beam. The energy scaling for the trapped charge from one plasma length to the other is consistent with the blowout theory of the plasma wakefield.

  3. Effect of thin emitter set-back layer on GaAs delta-doped emitter bipolar junction transistor

    Science.gov (United States)

    Lew, K. L.; Yoon, S. F.

    2005-05-01

    GaAs delta-doped emitter bipolar junction transistors (δ-BJT) with different emitter set-back layer thicknesses of 10to50nm were fabricated to study the emitter set-back layer thickness effect on device dc performance. We found that the current gain decreases following decrease in the emitter set-back layer thickness. A detailed analysis was performed to explain this phenomenon, which is believed to be caused by reduction of the effective barrier height in the δ-BJT. This is due to change in the electric-field distribution in the delta-doped structure caused by the built-in potential of the base-emitter (B-E ) junction. Considering the recombination and barrier height reduction effects, the thickness of the emitter set-back layer should be designed according to the B-E junction depletion width with a tolerance of ±5nm. The dc performance of a δ-BJT designed based on this criteria is compared to that of a Al0.25Ga0.75As /GaAs heterojunction bipolar transistor (HBT). Both devices employed base doping of 2×1019cm-3 and base-to-emitter doping ratio of 40. Large emitter area (AE≈1.6×10-5cm-2) and small emitter area (AE≈1.35×10-6cm-2) device current gains of 40 and 20, respectively, were obtained in both types of transistors passivated by (NH4)2S treatment. The measured current gain of the GaAs δ-BJT is the highest reported for a homojunction device with such high base-to-emitter doping ratio normally used in HBT devices.

  4. What future for quantum dot-based light emitters?

    Science.gov (United States)

    Nurmikko, Arto

    2015-12-01

    Synthesis of semiconductor colloidal quantum dots by low-cost, solution-based methods has produced an abundance of basic science. Can these materials be transformed to high-performance light emitters to disrupt established photonics technologies, particularly semiconductor lasers?

  5. Personnel exposure from positron emitters

    International Nuclear Information System (INIS)

    Positron emitters may contribute considerably to the radiation from induced radioactivity in accelerator environments. In most cases of thick radiating objects (magnets, shielding walls) the dose rate from gamma emitters, including the 511 keV annihilation photons from positron emitters, dominates the radiation field. Direct positron interaction in skin tissue and in the lens of the eye may be an important contribution to absorbed dose in cases of thin targets and beam separating septa. Results of calculations and measurements show, however, that the dose to the lens of the eye is limited by limitations placed on whole-body doses. Irradiation from positron emitters gives rise to about the same absorbed doses as those experienced in the case of an electron exposure. (author)

  6. Emittance problems in Tau-charm factories

    International Nuclear Information System (INIS)

    Tau-charm factory (TCF) was proposed by J. Kirkby for high precision studies of τ-leptons, τ-neutrinos and charmed particles. A number of requirements for TCF physics put hard constraints on the machine. The peak luminosity must be around the τ-lepton production threshold energy of E≅2 GeV and higher than 1033 cm-2s-1. TCF must provide a high average luminosity and high luminosity must be provided is a wide energy range from E≅1.5∼2.85 GeV. In this report, the TCF lattice requirements and possible solutions were discussed. The lattices with FODO regular cells were considered to be suitable for TCF, although larger longitudinal acceptance at low emittance option is desirable. Additional studies for high emittance option with DBA and TBA regular cells are necessary to overcome small dynamic aperture. The main collider parameters of conventional and monochromatic designs were presented. And it was concluded that TCF should be designed with possibility to work not only with marginal values of emittance, but intermediate too. (M.N.)

  7. Depth determination of low-energy photon emitter deposits in tissue by means of high-resolution X-ray spectrometry

    International Nuclear Information System (INIS)

    A method has been developed for ascertaining the depth of low-energy photon emitters deposited in wounds. It is based on the determination of the energy-dependent absorption of the emitted photons by the tissue separating source and detector. The method is applicable to counting for low-energy photon-emitting nuclides that can be characterized by more than one quantum energy. Attenuation coefficients were given for lard, beef, and five tissue- equivalent materials. For spectrometry, a planar Ge(Li) detector proved most suitable. (author)

  8. Nanostructure-induced distortion in single-emitter microscopy

    CERN Document Server

    Lim, Kangmook; Fourkas, John; Shapiro, Benjamin; Waks, Edo

    2016-01-01

    Single-emitter microscopy has emerged as a promising method of imaging nanostructures with nanoscale resolution. This technique uses the centroid position of an emitters far-field radiation pattern to infer its position to a precision that is far below the diffraction limit. However, nanostructures composed of high-dielectric materials such as noble metals can distort the far-field radiation pattern. Nanoparticles also exhibit a more complex range of distortions, because in addition to introducing a high dielectric surface, they also act as efficient scatterers. Thus, the distortion effects of nanoparticles in single-emitter microscopy remains poorly understood. Here we demonstrate that metallic nanoparticles can significantly distort the accuracy of single-emitter imaging at distances exceeding 300 nm. We use a single quantum dot to probe both the magnitude and the direction of the metallic nanoparticle-induced imaging distortion and show that the diffraction spot of the quantum dot can shift by more than 35...

  9. Localization of Narrowband Single Photon Emitters in Nanodiamonds.

    Science.gov (United States)

    Bray, Kerem; Sandstrom, Russell; Elbadawi, Christopher; Fischer, Martin; Schreck, Matthias; Shimoni, Olga; Lobo, Charlene; Toth, Milos; Aharonovich, Igor

    2016-03-23

    Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bioimaging. However, current understanding of the origin of these emitters is extremely limited. In this work, we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond and are directly relevant to fabrication of novel quantum optics devices and sensors. PMID:26937848

  10. Localization of narrowband single photon emitters in nanodiamonds

    CERN Document Server

    Bray, Kerem; Elbadawi, Christopher; Fischer, Martin; Schreck, Matthias; Shimoni, Olga; Lobo, Charlene; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bio-imaging. However, current understanding of the origin of these emitters is extremely limited. In this work we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond, and are directly relevant to fabrication of novel quantum optics devices and sensors.

  11. Optimization of Metamaterial Selective Emitters for Use in Thermophotovoltaic Applications

    Science.gov (United States)

    Pfiester, Nicole A.

    The increasing costs of fossil fuels, both financial and environmental, has motivated many to look into sustainable energy sources. Thermophotovoltaics (TPVs), specialized photovoltaic cells focused on the infrared range, offer an opportunity to achieve both primary energy capture, similar to traditional photovoltaics, as well as secondary energy capture in the form of waste heat. However, to become a feasible energy source, TPV systems must become more efficient. One way to do this is through the development of selective emitters tailored to the bandgap of the TPV diode in question. This thesis proposes the use of metamaterial emitters as an engineerable, highly selective emitter that can withstand the temperatures required to collect waste heat. Metamaterial devices made of platinum and a dielectric such as alumina or silicon nitride were initially designed and tested as perfect absorbers. High temperature robustness testing demonstrates the device's ability to withstand the rigors of operating as a selective emitter.

  12. Emittance measurements on ETA and ATA

    International Nuclear Information System (INIS)

    Emittance measurements on beams produced by the ETA and ATA accelerators are discussed. Emittance and brightness are defined. The significance of emittance for a beam in an accelerator and in gas is discussed. Various measurement techniques and results are presented and contrasted. Implicit calculations of emittance are also reported. Finally, the measurement of the time variation of emittance is discussed and the techniques to be used on the upcoming ATA experiments are outlined

  13. An ultracold low emittance electron source

    CERN Document Server

    Xia, G; Murray, A J; Bellan, L; Bertsche, W; Appleby, R B; Mete, O; Chattopadhyay, S

    2014-01-01

    Ultracold atom-based electron sources have recently been proposed as an alternative to the conventional photo-injectors or thermionic electron guns widely used in modern particle accelerators. The advantages of ultracold atom-based electron sources lie in the fact that the electrons extracted from the plasma (created from near threshold photo-ionization of ultracold atoms) have a very low temperature, i.e. down to tens of Kelvin. Extraction of these electrons has the potential for producing very low emittance electron bunches. These features are crucial for the next generation of particle accelerators, including free electron lasers, plasma-based accelerators and future linear colliders. The source also has many potential direct applications, including ultrafast electron diffraction (UED) and electron microscopy, due to its intrinsically high coherence. In this paper, the basic mechanism of ultracold electron beam production is discussed and our new research facility for an ultracold, low emittance electron s...

  14. Recent developments of low-emittance electron gun for accelerator

    International Nuclear Information System (INIS)

    Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R and D effort is 'accelerated' by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed. (author)

  15. Transverse emittance measurement at REGAE via a solenoid scan

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, Max

    2012-12-15

    The linear accelerator REGAE at DESY produces short and low charged electron bunches, on the one hand to resolve the excitation transitions of atoms temporally by pump probe electron diffraction experiments and on the other hand to investigate principal mechanisms of laser plasma acceleration. For both cases a high quality electron beam is required. A quantity to rate the beam quality is the beam emittance. In the course of this thesis transverse emittance measurements by a solenoid scan could be realized and beyond that an improved theoretical description of a solenoid was successful. The foundation of emittance measurements are constituted by theoretical models which describe the envelope of a beam. Two different models were derived. The first is an often used model to determine the transverse beam emittance without considering space charge effects. More interesting and challenging was the development of an envelope model taking space charge effects into account. It is introduced and cross checked with measurements and simulations.

  16. Innovative energy efficient low-voltage electron beam emitters

    International Nuclear Information System (INIS)

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates

  17. Transverse emittance measurement at REGAE via a solenoid scan

    International Nuclear Information System (INIS)

    The linear accelerator REGAE at DESY produces short and low charged electron bunches, on the one hand to resolve the excitation transitions of atoms temporally by pump probe electron diffraction experiments and on the other hand to investigate principal mechanisms of laser plasma acceleration. For both cases a high quality electron beam is required. A quantity to rate the beam quality is the beam emittance. In the course of this thesis transverse emittance measurements by a solenoid scan could be realized and beyond that an improved theoretical description of a solenoid was successful. The foundation of emittance measurements are constituted by theoretical models which describe the envelope of a beam. Two different models were derived. The first is an often used model to determine the transverse beam emittance without considering space charge effects. More interesting and challenging was the development of an envelope model taking space charge effects into account. It is introduced and cross checked with measurements and simulations.

  18. [OIII] emission line as a tracer of star-forming galaxies at high redshifts: Comparison between H$\\alpha$ and [OIII] emitters at $z$=2.23 in HiZELS

    CERN Document Server

    Suzuki, T L; Sobral, D; Khostovan, A A; Hayashi, M; Shimakawa, R; Koyama, Y; Tadaki, K -i; Tanaka, I; Minowa, Y; Yamamoto, M; Smail, I; Best, P N

    2016-01-01

    We investigate the properties of $z$=2.23 H$\\alpha$ and [OIII]$\\lambda$5007 emitters using the narrow-band-selected samples obtained from the High-$z$ Emission Line Survey (HiZELS: Sobral et al. 2013). We construct two samples of the H$\\alpha$ and [OIII] emitters and compare their integrated physical properties. We find that the distribution of stellar masses, dust extinction, star formation rates (SFRs), and specific SFRs, is not statistically different between the two samples. When we separate the full galaxy sample into three subsamples according to the detections of the H$\\alpha$ and/or [OIII] emission lines, most of the sources detected with both H$\\alpha$ and [OIII] show ${\\rm log(sSFR_{UV})}$$\\gtrsim$-9.5. The comparison of the three subsamples suggests that sources with strong [OIII] line emission tend to have the highest star-forming activity out all galaxies that we study. We argue that the [OIII] emission line can be used as a tracer of star-forming galaxies at high redshift, and that it is especia...

  19. Sectional and projectional emittance measurements a

    International Nuclear Information System (INIS)

    For many applications of ion sources the quality of the generated ion beam plays an increasingly important role. Ion sources consist of the plasma generator and the extraction system. Both parts can, due to high ion temperature or various aberrations, contribute to a degrading of the beam quality. Though the beam quality is determined by many more factors, the transverse motion of the particles certainly is one of the important parameters. Knowledge of it can be obtained by an emittance measurement. This is best done in a four-dimensional phase space, yielding a density distribution as function of the transverse spatial and momentum coordinates. Often, however, due to practical considerations, only two dimensions of the four-dimensional open-quote open-quote trace space close-quote close-quote are being measured. This two-dimensional data can be obtained as a section or as a projection of the four-dimensional trace space, where both methods have their merits. Projectional emittance measurements can usually be performed much easier and quicker, but by the projection of the four-dimensional space onto a two-dimensional plane information is lost. And although not all the particles of the beam are represented in a section of trace space, here aberrative distortions of the emittance can be seen most clearly and allow an easier comparison to numerically obtained data. The advantages and disadvantages of both methods are discussed. Numerical and experimental examples are presented. copyright 1996 American Institute of Physics

  20. Modular low-voltage electron emitters

    International Nuclear Information System (INIS)

    Modular, low-voltage electron emitters simplify electron beam (EB) technology for many industrial uses and for research and development. Modular electron emitters are produced in quantity as sealed systems that are evacuated at the factory, eliminating the need for vacuum pumps at the point of use. A plug-out-plug-in method of replacement facilitates servicing. By using an ultra-thin 6-7 μm titanium foil window, solid-state power supplies, an innovative design to extract and spread the beam (enabling systems to be placed adjacent to each other to extend beam width) and touch-screen computer controls, these modular units combine ease of use and electrical transfer efficiency at voltages that can be varied between 80 kV and 150 kV with beam currents up to 40 mA per 25 cm across the beam window. These new devices have been made in three widths: 5 cm, 25 cm, and 40 cm. Details of the beam construction and illustrations of industrial uses will be presented. Traditional uses in the graphic arts and coatings areas have welcomed this modular technology as well as uses for surface sterilization. Being compact and lightweight (∼15 kg/emitter), these modular beams have been configured around complex shapes to achieve three-dimensional surface curing at high production rates

  1. Billion shot flashlamp for spaceborne lasers

    Science.gov (United States)

    Richter, Linda; Schuda, Felix; Degnan, John

    1990-01-01

    A billion-shot flashlamp developed under a NASA contract for spaceborne laser missions is presented. Lifetime-limiting mechanisms are identified and addressed. Two energy loadings of 15 and 44 Joules were selected for the initial accelerated life testing. A fluorescence-efficiency test station was used for measuring the useful-light output degradation of the lamps. The design characteristics meeting NASA specifications are outlined. Attention is focused on the physical properties of tungsten-matrix cathodes, the chemistry of dispenser cathodes, and anode degradation. It is reported that out of the total 83 lamps tested in the program, 4 lamps reached a billion shots and one lamp is beyond 1.7 billion shots, while at 44 Joules, 4 lamps went beyond 100 million shots and one lamp reached 500 million shots.

  2. Beam phase space and emittance

    International Nuclear Information System (INIS)

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation, with three particular examples, and to introduce a beam envelope-ellipse and the β-function, emphasing the statistical features of its properties. (author) 14 refs.; 11 figs

  3. Ultra Low Emittance Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson,J.

    2008-06-23

    This paper outlines the special issues for reaching sub-nm emittance in a storage ring. Effects of damping wigglers, intra-beam scattering and lifetime issues, dynamic aperture optimization, control of optics, and their interrelations are covered in some detail. The unique choices for the NSLS-II are given as one example.

  4. DC-SC Photoinjector with Low Emittance at Peking University

    CERN Document Server

    Xiang Rong; Hao, J; Huang, Senlin; Lu Xiang Yang; Quan, Shengwen; Zhang, Baocheng; Zhao, Kui

    2005-01-01

    High average power Free Electron Lasers require the high quality electron beams with the low emittance and the sub-picosecond bunches. The design of DC-SC photoinjector, directly combining a DC photoinjector with an SRF cavity, can produce high average current beam with moderate bunch charge and high duty factor. Because of the DC gun, the emittance increases quickly at the beginning, so a carefully design is needed to control that. In this paper, the simulation of an upgraded design has been done to lower the normalized emittance below 1.5mm·mrad. The photoinjector consists of a DC gap and a 2+1/2-cell SRF cavity, and it is designed to produce 4.2 MeV electron beams at 100pC bunch charge and 81.25MHz repetition rate (8 mA average current).

  5. FY97 nuclear-related budgets total 493 billion yen (4.4 billion dollars)

    International Nuclear Information System (INIS)

    On September 13, the Atomic Energy Commission of Japan announced the estimated nuclear-related budget requests for FY1997 (April, 1997 - Mach, 1998), giving the breakdowns for eight ministries and agencies. The total amount requested by the government bodies was 493.3 billion yen, 0.8% increase as compared with FY96. this figure includes the budget requests of the Science and Technology Agency (STA), the Ministry of International Trade and Industry (MITI), the Ministry of Foreign Affairs, the Ministry of Transport, the Ministry of Agriculture, Forestry and Fisheries, the Okinawa Development Agency, and the Ministry of Home Affairs, but excludes the budget request made by the Ministry of Education. The budget requests of STA and MITI are 360 billion yen and 126 billion yen, respectively. On August 29, STA released its estimated FY97 budget request. The nuclear-related 360.4 billion yen is 0.9% more than that in year before. Of this sum, 199.9 billion yen is in the general account, and 160.6 billion yen is in the special account for power source development. The details of the nuclear-related amounts are explained. On August 26, MITI released its estimated budget request for FY97, and of the nuclear-related 125.7 billion yen (0.1% increase from FY96), 200 million yen is in the general account, and 98.9 billion yen and 26.6 billion yen are in the special accounts for power resource development and power source diversification, respectively. (K.I.)

  6. Emittance growth in the DARHT Axis-II Downstream Transport

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Jr., Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Martin E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-14

    Using a particle-in-cell (PIC) code, we investigated the possibilities for emittance growth through the quadrupole magnets of the system used to transport the high-current electron beam from an induction accelerator to the bremsstrahlung converter target used for flash radiography. We found that even highly mismatched beams exhibited little emittance growth (< 6%), which we attribute to softening of their initial hard edge current distributions. We also used this PIC code to evaluate the accuracy of emittance measurements using a solenoid focal scan following the quadrupole magnets. If the beam is round after the solenoids, the simulations indicate that the measurement is highly accurate, but it is substantially inaccurate for elliptical beams

  7. A method to measure the nonlinear force caused emittance growth in a RF photoinjector

    Institute of Scientific and Technical Information of China (English)

    Li Zheng-Hong; Yang Zhen-Ping

    2006-01-01

    Based on the multi-slit method, a new method is introduced to measure the non linear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.

  8. The nonprofit sector's $100 billion opportunity.

    Science.gov (United States)

    Bradley, Bill; Jansen, Paul; Silverman, Les

    2003-05-01

    Imagine what an extra $100 billion a year could do for philanthropic and other nonprofit institutions. According to a new study, the nonprofit sector could free that amount--maybe even more--by making five changes in the way it operates. The study asked two central questions: Does the sector's money flow from its source to its ultimate use as efficiently and effectively as possible? If not, where are the big opportunities to increase social benefit? According to former senator Bill Bradley and McKinsey's Paul Jansen and Les Silverman, nonprofits could save roughly $25 billion a year by changing the way they raise funds. By distributing funds more quickly, they could put an extra $30 billion to work. Organizations could generate more than $60 billion a year by streamlining and restructuring the way in which they provide services and by reducing administrative costs. And they could free up even more money--an amount impossible to estimate--by better allocating funds among service providers. The authors admit that making those changes won't be easy. The nonprofit world, historically seen as a collection of locally focused charities, has become an enormous sector, but it lacks the managerial processes and incentives that help keep the for-profit world on track. And when the baby boomers start to retire in less than a decade, public budgets will be squeezed even more than they are today. If the nonprofit sector is to help the nation cope with the stresses ahead, it must become more efficient and challenge its traditional concepts of stewardship. PMID:12747166

  9. Uncorrelated Energy Spread and Longitudinal Emittance of a Photoinjector Beam

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z; Dowell, D.; Emma, P.; Limborg-Deprey, C.; Stupakov, G.; Wu, J.; /SLAC

    2005-05-25

    Longitudinal phase space properties of a photoinjector beam are important in many areas of high-brightness beam applications such as bunch compression, transverse-to-longitudinal emittance exchange, and high-gain free-electron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laser-driven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with numerical simulations and recent experimental results.

  10. Thermal emittance and response time of a cesium antimonide photocathode

    Science.gov (United States)

    Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

    2011-10-01

    Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

  11. Beam emittance and beam disruption

    International Nuclear Information System (INIS)

    Beam disruption during the collision of intense relativistic bunches has been studied by R. Hollebeek. In the case of oppositely charged bunches, focussing effects occur causing a decrease in the effective bunch cross section, and thereby an increase of luminosity by an enhancement factor H. The term disruption derives from the fact that the beam emittance changes markedly during the collision. 1 ref., 1 fig., 1 tab

  12. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    , and 90Y, using data from a freely available database. Bremsstrahlung yields were calculated for 90Y shielded by lead, aluminium, or perspex. Bremsstrahlung spectrum from 90Y shielded by perspex was measured, and attenuation of spectrum by lead was calculated. Whole-body and finger doses to persons...... the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure....

  13. Beam emittance measurements at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Manfred; Eddy, Nathan; Hu, Martin; Scarpine, Victor; Syphers, Mike; Tassotto, Gianni; Thurman-Keup, Randy; Yang, Ming-Jen; Zagel, James; /Fermilab

    2008-01-01

    We give short overview of various beam emittance measurement methods, currently applied at different machine locations for the Run II collider physics program at Fermilab. All these methods are based on beam profile measurements, and we give some examples of the related instrumentation techniques. At the end we introduce a multi-megawatt proton source project, currently under investigation at Fermilab, with respect to the beam instrumentation challenges.

  14. TPV Generation of Electricity by Waste Heat Recovery from High-temperature Gas Using Rare-earth Emitters%稀土辐射器TPV利用高温余热发电的性能研究

    Institute of Scientific and Technical Information of China (English)

    周洁; 庞志伟; 卢晓啸

    2011-01-01

    利用热光伏(TPV)系统回收高温废气中的余热,并为余热型TPV系统选择适当的辐射器、滤波器和热光伏电池等组件,采用蒙特卡洛法对TPV系统进行了理论分析,同时对不同形式的TPV系统的工作性能进行了试验研究.结果表明:稀土辐射器的光谱选择性能和TCO滤波器的光谱过滤功能可使系统热电转换效率大幅度提高,但同时对系统的输出功率产生不利影响,尤其是TCO滤波器使系统的输出功率降幅较大;与太阳能光伏发电相比,余热TPV系统的发电成本较低,具有较好的经济性.%Using Monte Carlo method, theoretical analysis was performed to a thermophotovoltaic (TPV) system furnished with appropriate emitter, filter and photocell, which was able to recover waste heat from high-temperature exhaust gas, while working performance of various TPV systems studied. Results show that the rare-earth emitter and TCO filter greatly increase the thermoelectric conversion efficiency of the system, but decrease its output power density, especially the TCO filter play an obvious negative role in this aspect. Compared with a solar photovoltaic system, the TPV system has a lower generation cost, and therefore may result in higher economical effects.

  15. A theoretical study on tuning the electronic structures and photophysical properties of newly designed platinum(II) complexes by adding substituents on functionalized ligands as highly efficient OLED emitters.

    Science.gov (United States)

    Zhang, Luqiong; Tian, Li; Li, Ming; He, Rongxing; Shen, Wei

    2014-05-01

    By imitating FIrpic, seven new platinum(II) complexes with pic (pic = picolinate) ligand have been designed to be guest materials by means of adding different substituents to functionalized ligands (ppy and fpy, ppy = phenylpyridyl-N,C and fpy = 2-(9',9'-diethyl-9H-fluorenyl)pyridyl-N,C). In order to reveal their molecular structures, photophysical properties and structure-property relationships with typical host materials, an in-depth theoretical investigation was performed via quantum chemical calculations. The electronic structures and photophysical properties of these complexes were investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT) using the B3LYP functional with LANL2DZ and 6-31G* basis sets. It turns out that electronic structures and photophysical properties can be tuned by substituent modifications on functionalized ligands. This work highlights that the match between guest materials and host materials in typical OLED structures can be weighed by the energy levels of the HOMO and LUMO and the adiabatic triplet energy of each complex. Also, a combined analysis of electronic structures, host-guest match, reorganization energies (λ) and triplet exciton generation fraction (χ(T)) is helpful in exploring triplet emitters with high phosphorescence efficiency in OLEDs, which is an interesting and creative aspect of this work. Thereinto, λ reveals the capability of carrier transport and the balance between holes and electrons, whilst structural parameters and d-orbital splittings show that those complexes that have strong electron-withdrawing and electron-donating groups are nonemissive. Consequently, complexes 3-7 can be better triplet emitters than FIrpic. Moreover, the emission colors could be predicted by the 0-0 transition energy (E(0-0)) instead of the triplet vertical transition energy (E(vert)). Accordingly, complexes 3, 4 and 6 would be efficient phosphorescent materials with different predicted

  16. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  17. Evolution of Lyman-α Emitters, Lyman-break Galaxies and Elliptical Galaxies

    Science.gov (United States)

    Mori, M.; Umemura, M.

    2008-10-01

    High redshift Lyman-α emitters (LAEs) and Lyman-break galaxies (LBGs) possibly provide a significant key for the embryology of galaxies. LBGs have been argued as candidate progenitors of present-day elliptical galaxies in terms of their observed properties. But, what evolutionary stages LBGs correspond to and how they are related to LAEs are still under debate. Here, we present an ultra-high-resolution hydrodynamic simulation of galaxy formation. We show that, at the earliest stages of less than 3×10^8 years, continual supernova explosions produce multitudinous hot bubbles and cooled HI shells in between. The HI shells radiate intense Lyman-α emission like LAEs. We found that the bubbly structures produced are quite similar to the observed features in the Lyman-α surface brightness distribution of the extended LAEs. After 10^9 years, the galaxy emission is dominated by stellar continuum, exhibiting an LBG-like spectrum. Also, we find that, as a result of purely dynamical evolution over 13 billion years, the properties of this galaxy match those of present-day elliptical galaxies well. It is implied that the major episode of star formation and chemical enrichment in elliptical galaxies is almost completed in the evolutionary path from LAEs to LBGs.

  18. Efficient Terahertz Photoconductive Emitters with Improved Electrode Structures

    Institute of Scientific and Technical Information of China (English)

    Ying-Xin Wang; Yi-Jie Niu; Wei Cheng; Zhi-Qiang Li; Zi-Ran Zhao

    2014-01-01

    We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure, which are all modified from a traditional strip line antenna. Numerical simulations and real experiments confirm the good performance of the proposed antennas. An amplitude increase of about 40% is experimentally observed for the terahertz signals generated from the new structures. The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement. Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.

  19. Carbon Nanotube Electron Emitter for X-ray Imaging

    Directory of Open Access Journals (Sweden)

    Jung Su Kang

    2012-11-01

    Full Text Available The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube emitter, and the transmitted X-ray image was of high resolution.

  20. Ultra-Sensitivity Glucose Sensor Based on Field Emitters

    Directory of Open Access Journals (Sweden)

    Song Yinglin

    2009-01-01

    Full Text Available Abstract A new glucose sensor based on field emitter of ZnO nanorod arrays (ZNA was fabricated. This new type of ZNA field emitter-based sensor shows high sensitivity with experimental limit of detection of 1 nM glucose solution and a detection range from 1 nM to 50 μM in air at room temperature, which is lower than that of glucose sensors based on surface plasmon resonance spectroscopy, fluorescence signal transmission, and electrochemical signal transduction. The new glucose sensor provides a key technique for promising consuming application in biological system for detecting low levels of glucose on single cells or bacterial cultures.

  1. Muon Emittance Exchange with a Potato Slicer

    Energy Technology Data Exchange (ETDEWEB)

    Summers, D. J. [Univ. of Mississippi, Oxford, MS (United States); Hart, T. L. [Univ. of Mississippi, Oxford, MS (United States); Acosta, J. G. [Univ. of Mississippi, Oxford, MS (United States); Cremaldi, L. M. [Univ. of Mississippi, Oxford, MS (United States); Oliveros, S. J. [Univ. of Mississippi, Oxford, MS (United States); Perera, L. P. [Univ. of Mississippi, Oxford, MS (United States); Neuffer, D. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-04-15

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.

  2. Emittance minimisation with longitudinal dipole field variation

    International Nuclear Information System (INIS)

    The reduction of horizontal emittance beyond the conventional limit is pursued by introducing a longitudinal variation of the field in a bending magnet. For a given dipole field, the search for the minimal emittance is formulated analytically under different boundary conditions, starting from the achromat condition, preferred for light source rings. With a dipole field rapidly decaying along the longitudinal position, it is shown that the emittance can be further reduced, essentially by rendering the H function to be out of phase with the third power of the local curvature. Under the minimal emittance condition analytically obtained, the optimal dipole field distribution is searched numerically with a polynomial function, analysing at the same time the mechanism of the emittance reduction. The minimal emittance is argued as a function of the required peak field and the field distribution. Adaptability of longitudinally varying dipole fields in a standard magnet lattice for light sources is also addressed

  3. Emittance measurements by variable quadrupole method

    International Nuclear Information System (INIS)

    The beam emittance is a measure of both the beam size and beam divergence, we cannot directly measure its value. If the beam size is measured at different locations or under different focusing conditions such that different parts of the phase space ellipse will be probed by the beam size monitor, the beam emittance can be determined. An emittance measurement can be performed by different methods. Here we will consider the varying quadrupole setting method.

  4. Extremely low vertical-emittance beam in accelerator-test facility at KEK

    International Nuclear Information System (INIS)

    Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping rings which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1 percent of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10-8 rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance

  5. Directional emittance corrections for thermal infrared imaging

    Science.gov (United States)

    Daryabeigi, Kamran; Wright, Robert E., Jr.; Puram, Chith K.; Alderfer, David W.

    1992-01-01

    A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  6. Hybrid emitter all back contact solar cell

    Science.gov (United States)

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

  7. Space Charge Effects in Rectilinear Motion Emittance

    CERN Document Server

    Chen, C

    2000-01-01

    This report summarizes the presentations and discussions over a wide range of topics in Working Group I at the Second ICFA Advanced Accelerator Workshop on Physics of High-Brightness Beams held at University of California at Los $9 Angeles (UCLA), November 9-12, 1999. Latest developments towards to a better understanding of high-brightness photoinjectors were reported. The design and commissioning of the Los Alamos National Laboratory (LANL) Low-Energy $9 Demonstration Accelerator (LEDA) Radio-Frequency Quadrupole (RFQ) were reported. The problem of beam halo formation was discussed in both beam transport systems and the SLAC 50 MW 11.4 GHz periodic permanent magnet (PPM) focusing $9 klystron amplifier. A new class of corkscrewing elliptic beam equilibria was reported, and applications of such novel beam equilibria in controlling of charge-density and velocity fluctuations, beam halo formation and emittance $9 growth were discussed. Pattern formation in proton rings was also discussed.

  8. Scanning electron and tunneling microscopy of palladium-barium emitters

    International Nuclear Information System (INIS)

    The results of study of metal-alloyed palladium-barium emitters' of modern very high frequency high-powered electronic vacuum tubes by scanning electron microscopy (SEM) and scanning tunneling microscopy/spectroscopy (STM/STS) are presented. Since the Pd/Ba foil surface is fairly smooth and is not oxidized in air STM/STS investigations are carried out in air in normal laboratory environment. SEM and STM images show that the emitter surface has a complex porous structure. The cathode surface study by STS in tunneling gap modulation mode allowed to take a map of phase distribution with various work function values and high lateral resolution. Obtained images demonstrate the presence of three phases on the Pd/Ba emitter surface, viz. barium-oxygen compounds, intermetallic, and palladium. As it is seen from presented STS image the phase with a low work function value (barium oxides) is concentrated along boundaries of the substance inclusions with work function corresponding to the intemetallic compound Pd5Ba. This supports the model of low work function areas obtained via Ba segregation from the intermetallic compound and oxidation. The presented methods may be used in the Pd/Ba cathode manufacturing process for increasing the yield of electronic devices in microwave tube production and optimize the emitters' characteristics

  9. A remarkably high fraction of strong Ly_alpha emitters amongst luminous redshift 6.0

    CERN Document Server

    Curtis-Lake, E; Pearce, H J; Dunlop, J S; Cirasuolo, M; Stark, D P; Almaini, O; Bradshaw, E J; Chuter, R; Foucaud, S; Hartley, W G

    2011-01-01

    We present spectroscopic confirmation of ten highly luminous (L >= 2L*) Lyman alpha emitters in the redshift range 6.01= 6 Lyman break galaxies (LBGs) selected from an area of 0.25 square degrees within the UKIDSS Ultra-deep Survey (UDS). Overall, our high rate of spectroscopic confirmation (>= 71%) and low rate of contamination provides a strong vindication of the photometric redshift analysis used to define the original sample. By considering star-formation rate estimates based on the Ly_alpha and UV continuum luminosity we conclude that our sample is consistent with a Ly_alpha escape fraction of ~25%. Moreover, after careful consideration of the potential uncertainties and biases, we find that 40%-50% of our sample of L >= 2L* galaxies at 6.0= 25 Angs), a fraction which is a factor of ~2 higher than previously reported for L =2 L*) LBGs shows a similarly sharp increase to that observed in their lower-luminosity (L <= L*) counterparts.

  10. Origins fourteen billion years of cosmic evolution

    CERN Document Server

    Tyson, Neil deGrasse

    2004-01-01

    Origins explores cosmic science's stunning new insights into the formation and evolution of our universe--of the cosmos, of galaxies and galaxy clusters, of stars within galaxies, of planets that orbit those stars, and of different forms of life that take us back to the first three seconds and forward through three billion years of life on Earth to today's search for life on other planets. Drawing on the current cross-pollination of geology, biology and astrophysics, Origins explains the thrilling daily breakthroughs in our knowledge of the universe from dark energy to life on Mars to the mysteries of space and time. Distilling complex science in clear and lively prose, co-authors Neil deGrasse Tyson and Donald Goldsmith conduct a galvanising tour of the cosmos revealing what the universe has been up to while turning part of itself into us.

  11. Transverse beam emittance measurement using quadrupole variation at KIRAMS-430

    Science.gov (United States)

    An, Dong Hyun; Hahn, Garam; Park, Chawon

    2015-02-01

    In order to produce a 430 MeV/u carbon ion (12 C 6+) beam for medical therapy, the Korea Institute of Radiological & Medical Sciences (KIRAMS) has carried out the development of a superconducting isochronous cyclotron, the KIRAMS-430. At the extraction of the cyclotron, an Energy Selection System (ESS) is located to modulate the fixed beam energy and to drive the ion beam through High Energy Beam Transport (HEBT) into the treatment room. The beam emittance at the ion beamline is to be measured to provide information on designing a beam with high quality. The well-known quadrupole variation method was used to determine the feasibility of measuring the transverse beam emittance. The beam size measured at the beam profile monitor (BPM) is to be utilized and the transformation of beam by transfer matrix is to be applied being taken under various transport condition of varying quadrupole magnetic strength. Two different methods where beam optics are based on the linear matrix formalism and particle tracking with a 3-D magnetic field distribution obtained by using OPERA3D TOSCA, are applied to transport the beam. The fittings for the transformation parameters are used to estimate the transverse emittance and the twiss parameters at the entrance of the quadrupole in the ESS. Including several systematic studies, we conclude that within the uncertainty the estimated emittances are consistent with the ones calculated by using Monte Carlo simulations.

  12. Emittance control and RF bunch compression in the NSRRC photoinjector

    Science.gov (United States)

    Lau, W. K.; Hung, S. B.; Lee, A. P.; Chou, C. S.; Huang, N. Y.

    2011-05-01

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  13. Emittance control and RF bunch compression in the NSRRC photoinjector

    International Nuclear Information System (INIS)

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  14. Design of a 4D Emittance Measurement Device for High Charge State ECR Ion Sources%高电荷态ECR离子源引出束流4D发射度测量仪设计

    Institute of Scientific and Technical Information of China (English)

    赵阳阳; 赵红卫; 孙良亭; 杨尧; 王云; 曹云

    2013-01-01

    For the purpose of on-line beam quality diagnostics and transverse emittance coupling investigation of the ion beams delivered by an Electron Cyclotron Resonance (ECR) ion source, a real-time 4D Pepper Pot type emittance scanner is under development at IMP(Institute of Moden Physics, Chinese Academy of Sciences). The high charge state ECR ion source at IMP could produce CW or pulsed heavy ion beam intensities in the range of 1 eµA∼1 emA with the kinetic energy of 10∼35 keV/q, which needs the design of the Pepper Pot scanner to be optimized accordingly. The Pepper Pot scanner has many features, such as very short response time and wide dynamic working range that the device could be applied. Since intense heavy ion beam bombardment is expected for this device, the structure and the material selection for the device is specially considered during the design, and a feasible solution to analyze the pictures acquired after the data acquisition is also made.%为了进一步探究高电荷态电子回旋共振(ECR)离子源引出束流品质和横向相空间耦合情况,根据中国科学院近代物理研究所高电荷态离子源引出束流发射度测量需求,针对束流流强为1 eµA∼1 emA,能量范围为10∼35 keV/q的直流或脉冲高电荷态重离子束,设计了一台实时四维Pepper-pot发射度测量仪。该Pepper-pot型发射度测量仪具有响应时间快和工作范围宽等特点。针对强流重离子束诊断的特点,在结构与材料选择上做了设计与优化,并对获得图像的处理方法提出了具体的解决办法。

  15. Emitter/absorber interface of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tao [Physics Department, Colorado State University, Fort Collins, Colorado 80523, USA; Kanevce, Ana [National Renewable Energy Laboratory, Golden, Colorado 80401, USA; Sites, James R. [Physics Department, Colorado State University, Fort Collins, Colorado 80523, USA

    2016-06-17

    The performance of CdTe solar cells can be very sensitive to their emitter/absorber interfaces, especially for high-efficiency cells with improved bulk properties. When interface defect states are located at efficient recombination energies, performance losses from acceptor-type interface defects can be significant. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e. defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV high interface defect density, much like with Cu(In,Ga)Se2 (CIGS) cells. The basic principle is that positive ..delta..EC, often referred to as a 'spike', creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (..delta..EC >/= 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a 'cliff' (.delta..EC < 0 eV) is likely to allow many holes in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. In addition, a thin and highly-doped emitter can invert the absorber, form a large hole barrier, and decrease device performance losses due to high interface defect density. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. Other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ..delta..EC. These materials are predicted

  16. Emitter/absorber interface of CdTe solar cells

    Science.gov (United States)

    Song, Tao; Kanevce, Ana; Sites, James R.

    2016-06-01

    The performance of CdTe solar cells can be very sensitive to the emitter/absorber interface, especially for high-efficiency cells with high bulk lifetime. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e., defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV ≤ ΔEC ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se2 (CIGS) cells. The basic principle is that positive ΔEC, often referred to as a "spike," creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (ΔEC ≥ 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a "cliff" (ΔEC CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. The ΔEC of other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ΔEC. These materials are predicted to yield higher voltages and would therefore be better candidates for the CdTe-cell emitter.

  17. TPV Systems with Solar Powered Tungsten Emitters

    International Nuclear Information System (INIS)

    A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at λ > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed

  18. Batch By Batch Longitudinal Emittance Blowup MD

    CERN Document Server

    Mastoridis, T; Butterworth, A; Jaussi, M; Molendijk, J

    2012-01-01

    The transverse bunch emittance increases significantly at 450 GeV from the time of injection till the ramp due to IBS. By selectively blowing up the longitudinal emittance of the incoming batch at each injection, it should be possible to reduce the transverse emittance growth rates due to IBS. An MD was conducted on April 22nd 2012 to test the feasibility and performance of the batch-by-batch longitudinal emittance blowup. There were three main goals during the MD. First, to test the developed hardware, firmware, and software for the batch-by-batch blowup. Then, to measure the transverse emittance growth rates of blown-up and "witness" batches to quantify any improvement, and finally to test the ALLInjectSequencer class, which deals with the complicated gymnastics of introducing or masking the new batch to various RF loops.

  19. Positron emitter labeled enzyme inhibitors

    International Nuclear Information System (INIS)

    This invention involves a new strategy for imagining and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography

  20. Low Emittance Electron Beam Studies

    Energy Technology Data Exchange (ETDEWEB)

    Tikhoplav, Rodion

    2006-04-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*{sub 01} mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  1. Measurements of the transverse emittance at the VUV-FEL

    International Nuclear Information System (INIS)

    The Tesla test facility (TTF) linear accelerator (linac) at DESY has been extended to drive a new Free Electron Laser facility (VUV-FEL) in the wavelength range from the vacuum-ultraviolet (VUV) to soft X-rays. With the upgraded photo injector and increased electron beam energy up to 1 GeV, wavelengths down to 6 nm can be achieved. During the commissioning phase of the VUV-FEL the emphasis is on lasing with a wavelength of 30 nm. A high quality electron beam is required for the lasing process. At the VUV-FEL the design values are 2 mm mrad normalized transverse emittance, 2500 A peak current, and 0.1% energy spread. In order to understand and optimize the electron beam, precise measurements of the beam properties are essential. In this diploma thesis, measurements of the transverse emittance during the commissioning of the VUV-FEL are presented. The transverse beam distribution is measured using optical transition radiation at four positions along the linac. The emittance is determined from the measured distributions using two methods: a fit of the Twiss parameters together with the emittance to the measured beam sizes, and as a second method, the tomographic reconstruction of the phase space density distributions using the Maximum Entropy Algorithm. (orig.)

  2. Low emittance injector design for free electron lasers

    Science.gov (United States)

    Bettoni, S.; Pedrozzi, M.; Reiche, S.

    2015-12-01

    Several parameters determine the performance of free electron lasers: the slice and the projected emittance, the slice energy spread, and the peak current are the most crucial ones. The peak current is essentially obtained by magnetic compression stages along the machine or occasionally assisted by velocity bunching at low energy. The minimum emittance and the alignment of the slices along the bunch are mainly determined in the low energy part of the accelerator (injector). Variations at the per-mille level of several parameters in this section of the machine strongly influence these quantities with highly nonlinear dynamic. We developed a numerical tool to perform the optimization of the injector. We applied this code to optimize the SwissFEL injector, assuming different gun designs, initial bunch lengths and intrinsic emittances. We obtained an emittance along the bunch of 0.14 mm mrad and around 0.08 mm mrad for the maximum and the minimum SwissFEL charges (200 and 10 pC, respectively). We applied the same tool to a running injector, where we automatized the optimization of the machine.

  3. Uranium in Canada: Billion-dollar industry

    International Nuclear Information System (INIS)

    In 1988, Canada maintained its position as the world's leading producer and exporter of uranium; five primary uranium producers reported concentrate output containing 12,400 MT of uranium, or about one-third of Western production. Uranium shipments made by these producers in 1988 exceeded 13,200 MT, worth Canadian $1.1 billion. Because domestic requirements represent only 15% of current Canadian output, most of Canada's uranium production is available for export. Despite continued market uncertainty in 1988, Canada's uranium producers signed new sales contracts for some 14,000 MT, twice the 1987 level. About 90% of this new volume is with the US, now Canada's major uranium customer. The recent implementation of the Canada/US Free Trade agreement brings benefits to both countries; the uranium industries in each can now develop in an orderly, free market. Canada's uranium industry was restructured and consolidated in 1988 through merger and acquisition; three new uranium projects advanced significantly. Canada's new policy on nonresident ownership in the uranium mining sector, designed to encourage both Canadian and foreign investment, should greatly improve efforts to finance the development of recent Canadian uranium discoveries

  4. Experimentally minimized beam emittance from an L-band photoinjector

    Science.gov (United States)

    Krasilnikov, M.; Stephan, F.; Asova, G.; Grabosch, H.-J.; Groß, M.; Hakobyan, L.; Isaev, I.; Ivanisenko, Y.; Jachmann, L.; Khojoyan, M.; Klemz, G.; Köhler, W.; Mahgoub, M.; Malyutin, D.; Nozdrin, M.; Oppelt, A.; Otevrel, M.; Petrosyan, B.; Rimjaem, S.; Shapovalov, A.; Vashchenko, G.; Weidinger, S.; Wenndorff, R.; Flöttmann, K.; Hoffmann, M.; Lederer, S.; Schlarb, H.; Schreiber, S.; Templin, I.; Will, I.; Paramonov, V.; Richter, D.

    2012-10-01

    High brightness electron sources for linac based free-electron lasers (FELs) are being developed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ). Production of electron bunches with extremely small transverse emittance is the focus of the PITZ scientific program. The photoinjector optimization in 2008-2009 for a bunch charge of 1, 0.5, 0.25, and 0.1 nC resulted in measured emittance values which are beyond the requirements of the European XFEL [S. Rimjaem , Nucl. Instrum. Methods Phys. Res., Sect. A 671, 62 (2012)NIMAER0168-900210.1016/j.nima.2011.12.101]. Several essential modifications were commissioned in 2010-2011 at PITZ, resulting in further improvement of the photoinjector performance. Significant improvement of the rf gun phase stability is a major contribution in the reduction of the measured transverse emittance. The old TESLA prototype booster was replaced by a new cut disk structure cavity. This allows acceleration of the electron beam to higher energies and supports much higher flexibility for stable booster operation as well as for longer rf pulses which is of vital importance especially for the emittance optimization of low charge bunches. The transverse phase space of the electron beam was optimized at PITZ for bunch charges in the range between 0.02 and 2 nC, where the quality of the beam measurements was preserved by utilizing long pulse train operation. The experimental optimization yielded worldwide unprecedented low normalized emittance beams in the whole charge range studied.

  5. Warm-white light-emitting diode with high color rendering index fabricated by combining trichromatic InGaN emitter with single red phosphor.

    Science.gov (United States)

    Sheu, Jinn-Kong; Chen, Fu-Bang; Wang, Yen-Chin; Chang, Chih-Chiang; Huang, Shih-Hsien; Liu, Chun-Nan; Lee, Ming-Lun

    2015-04-01

    We present a trichromatic GaN-based light-emitting diode (LED) that emits near-ultraviolet (n-UV) blue and green peaks combined with red phosphor to generate white light with a low correlated color temperature (CCT) and high color rendering index (CRI). The LED structure, blue and green unipolar InGaN/GaN multiple quantum wells (MQWs) stacked with a top p-i-n structure containing an InGaN/GaN MQW emitting n-UV light, was grown epitaxially on a single substrate. The trichromatic LED chips feature a vertical conduction structure on a silicon substrate fabricated through wafer bonding and laser lift-off techniques. The blue and green InGaN/GaN MQWs were pumped with n-UV light to re-emit low-energy photons when the LEDs were electrically driven with a forward current. The emission spectrum included three peaks at approximately 405, 468, and 537 nm. Furthermore, the trichromatic LED chips were combined with red phosphor to generate white light with a CCT and CRI of approximately 2900 and 92, respectively. PMID:25968789

  6. Field emission from optimized structure of carbon nanotube field emitter array

    Science.gov (United States)

    Chouhan, V.; Noguchi, T.; Kato, S.

    2016-04-01

    The authors report a detail study on the emission properties of field emitter array (FEA) of micro-circular emitters of multiwall carbon nanotubes (CNTs). The FEAs were fabricated on patterned substrates prepared with an array of circular titanium (Ti) islands on titanium nitride coated tantalum substrates. CNTs were rooted into these Ti islands to prepare an array of circular emitters. The circular emitters were prepared in different diameters and pitches in order to optimize their structure for acquiring a high emission current. The pitch was varied from 0 to 600 μm, while a diameter of circular emitters was kept constant to be 50 μm in order to optimize a pitch. For diameter optimization, a diameter was changed from 50 to 200 μm while keeping a constant edge-to-edge distance of 150 μm between the circular emitters. The FEA with a diameter of 50 μm and a pitch of 120 μm was found to be the best to achieve an emission current of 47 mA corresponding to an effective current density of 30.5 A/cm2 at 7 V/μm. The excellent emission current was attributed to good quality of CNT rooting into the substrate and optimized FEA structure, which provided a high electric field on a whole circular emitter of 50 μm and the best combination of the strong edge effect and CNT coverage. The experimental results were confirmed with computer simulation.

  7. Sneak Peek to the 2016 Billion-Ton Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-06-01

    The 2005 Billion-Ton Study became a landmark resource for bioenergy stakeholders, detailing for the first time the potential to produce at least one billion dry tons of biomass annually in a sustainable manner from U.S. agriculture and forest resources. The 2011 U.S. Billion-Ton Update expanded and updated the analysis, and in 2016, the U.S. Department of Energy’s Bioenergy Technologies Office plans to release the 2016 Billion-Ton Report: Advancing Domestic Resources for a Thriving Bioeconomy.

  8. Increase of emittance by inverse multiple Touschek effect in a single bunch of charged accelerated particles

    International Nuclear Information System (INIS)

    Coulomb scattering of the longitudinal momentum distribution of particles in an accelerated bunch leads to the creation of a transverse emittance which adds to the natural emittance. This process has been calculated for high energy linacs used in high energy e+e- linear colliders. At beam energies of 500 GeV to 1 TeV, it has been found that the effect is weak

  9. Single shot 3 GeV electron transverse emittance with a pepper-pot

    International Nuclear Information System (INIS)

    We present the first measurement of the transverse emittance of an electron bunch at 3 GeV using the pepper-pot technique. The measurements presented in this paper demonstrate the possibility to use such a method for single shot emittance measurement of high energy particles. This measurement presents also the experimental verification of a previous theoretical study, which was predicting in which condition such a measurement can be done. The method may present some technical limitations which are discussed in view of the application to future very small emittance multi-GeV particle accelerators

  10. Single shot 3 GeV electron transverse emittance with a pepper-pot

    Science.gov (United States)

    Thomas, Cyrille; Delerue, Nicolas; Bartolini, Riccardo

    2013-11-01

    We present the first measurement of the transverse emittance of an electron bunch at 3 GeV using the pepper-pot technique. The measurements presented in this paper demonstrate the possibility to use such a method for single shot emittance measurement of high energy particles. This measurement presents also the experimental verification of a previous theoretical study, which was predicting in which condition such a measurement can be done. The method may present some technical limitations which are discussed in view of the application to future very small emittance multi-GeV particle accelerators.

  11. Single shot 3 GeV electron transverse emittance with a pepper-pot

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Cyrille, E-mail: cyrille.thomas@diamond.ac.uk [Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom); Delerue, Nicolas, E-mail: delerue@lal.in2p3.fr [John Adam Institute, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Bartolini, Riccardo, E-mail: riccardo.bartolini@diamond.ac.uk [Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom); John Adam Institute, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

    2013-11-21

    We present the first measurement of the transverse emittance of an electron bunch at 3 GeV using the pepper-pot technique. The measurements presented in this paper demonstrate the possibility to use such a method for single shot emittance measurement of high energy particles. This measurement presents also the experimental verification of a previous theoretical study, which was predicting in which condition such a measurement can be done. The method may present some technical limitations which are discussed in view of the application to future very small emittance multi-GeV particle accelerators.

  12. Slice emittance measurement for photocathode RF gun with solenoid scanning and RF deflecting cavity

    Science.gov (United States)

    Li, Chen; Huang, WenHui; Du, YingChao; Yan, LiXin; Tang, ChuanXiang

    2011-12-01

    The radiation of high-gain short-wavelength free-electron laser depends on the slice transverse emittance of the electron bunch. This essay introduces the method of slice emittance measurement, and shows the brief setup of this experiment using the solenoid scanning and RF deflecting cavity at Tsinghua University. The preliminary experimental results show that the slice rms emittance of the electron bunch generated by photocathode RF gun has considerable variations along the bunch and is typically less than 0.55 mm mrad for the laser rms radius of 0.4 mm.

  13. Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bohler, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ding, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gilevich, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratner, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Vetter, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-12-07

    Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Light Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.

  14. Low Emittance Gun Project based on Field Emission

    CERN Document Server

    Ganter, Romain; Dehler, M; Gobrecht, Jens; Gough, Chris; Ingold, Gerhard; Leemann, Simon C; Shing-Bruce-Li, Kevin; Paraliev, Martin; Pedrozzi, Marco; Raguin, Jean Yves; Rivkin, Leonid; Schlott, Volker; Sehr, Harald; Streun, Andreas; Wrulich, Albin F; Zelenika, Sasa

    2004-01-01

    The design of an electron gun capable of producing beam emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser emitting at 0.1nm. Field emitter arrays (FEAs) including a gate and a focusing layer are an attractive technology for such high brightness sources. Electrons are extracted from micrometric tips thanks to voltage pulses between gate and tips. The focusing layer should then reduce the initial divergence of each emitted beamlets. This FEA will be inserted in a high gradient diode configuration coupled with a radiofrequency structure. In the diode part very high electric field pulses (several hundreds of MV/m) will limit the degradation of emittance due to space charge effect. This first acceleration will be obtained with high voltage pulses (typically a megavolt in a few hundred of nanoseconds) synchronized with the low voltage pulses applied to the FEA (typically one hundred of volts in one nanosecond at frequency below kilohe...

  15. Low emittance upgrade for CANDLE project

    CERN Document Server

    Zanyan, G S

    2015-01-01

    To improve the performance of CANDLE synchrotron light source and stay competitive with recently proposed low emittance upgrade programs in the world we have developed new low emittance lattices for CANDLE booster and storage ring. These lattices have been designed taking into account the new developments in magnet fabrication technology and the multi-bend achromat concept. The main design considerations, the linear and non-linear beam dynamics aspects of the modified lattices are presented.

  16. Alpha-emitters for medical therapy workshop

    Energy Technology Data Exchange (ETDEWEB)

    Feinendegen, L.E.; McClure, J.J.

    1996-12-31

    A workshop on ``Alpha-Emitters for Medical Therapy`` was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference.

  17. Alpha-emitters for medical therapy workshop

    International Nuclear Information System (INIS)

    A workshop on ''Alpha-Emitters for Medical Therapy'' was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference

  18. Emittance growth due to radial density variations of an emittance-dominated electron beam in a channel with continuous acceleration and focusing

    International Nuclear Information System (INIS)

    Simulations have identified charge-density variations as driving the dominant emittance growth mechanism for high-current, low-emittance induction linacs using solenoidal focusing, once the beam enters the emittance-dominated regime. In this paper, we use the radial equation of motion, including the nonlinearities resulting from radial density variations, to understand this effect. Nonlinearities in the beam close-quote s radial motion while in a solenoid arise from the noncancellation of the effects from the diamagnetic axial magnetic field and the potential depression of the beam, if the beam density is nonuniform. Any initial density variation drives a logarithmic increase in additional higher-order density variations (through the differential betatron motion), and an emittance growth that scales logarithmically, or greater (even potentially faster than linear), with the axial distance along the accelerator. The growth rate depends on the beam current, the focusing force, and the accelerating gradient, and for typical machine parameters, the growth rate can be faster than linear with distance. The magnitude of the emittance growth depends critically on the matching of the beam from the injector to the beamline. This formalism leads to a criterion of how uniform the beam density has to be and how well the beam needs to be matched in order not to have an unacceptable emittance growth. copyright 1998 American Institute of Physics

  19. Resonantly enhanced thermal emitters based on nanophotonic structures

    OpenAIRE

    O'Regan, Bryan J.

    2015-01-01

    The manipulation of photons, especially the control of spontaneous emission, has become a core area of photonics research in the 21st century. One of the key challenges is the control of the broadband emission profile of thermal emitters. Recently, attention has focused on resonant nanophotonic structures to control the thermal emission with most of the work concentrating on the mid-infrared wavelength range and/or based on metallic nanostructures. However, the realisation of a high temperatu...

  20. Proton collider breaks the six-billion-dollar barrier

    CERN Multimedia

    Vaughan, C

    1990-01-01

    The SSC will cost at least 1 billion more than its estimated final price of 5.9 billion dollars. Critics in congress believe the final bill could be double that figure. The director of the SSC blames most of the increase in cost on technical problems with developing the superconducting magnets for the SSC (1/2 page).

  1. Economic toll of AIDS put at $10 billion in Canada.

    Science.gov (United States)

    1996-11-29

    John McCallum, Chief economist at the Royal Bank of Canada, announced that AIDS has cost the nation's economy $10 billion since 1981. These calculations included losses in both direct medical care and human capital. This monetary figure is expected to rise to $36 billion by 2010. An estimated 42,500 to 45,000 Canadians are infected with HIV. PMID:11364044

  2. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  3. Two-dimensional VO2 photonic crystal selective emitter

    International Nuclear Information System (INIS)

    The design and simulation of a two-dimensional (2D) photonic crystal (PhC) selective emitter made of vanadium dioxide (VO2), a type metal oxide with a high temperature resistance, are reported. Spectral emission characteristics of the 2D VO2 PhCs were investigated using the finite difference time domain (FDTD) method. The PhC consists of a periodic array of cylindrical air microcavities. The influences of the geometric characteristic parameters are discussed. The influences of the radius and depth on the emission of the 2D VO2 PhC can be explained based on the coupled-mode theory. The emissivities at wavelengths below the cut-off wavelength were enhanced by increasing the depth. When the depth was much larger than the radius, the cut-off wavelength increased with the radius. The effect of the period on the emissivity at wavelengths less than the period was highly influenced by the diffraction modes. The designed 2D VO2 PhC emitter exhibited a selective emission that was well-matched with InGaAs cells. The spectral emissivities within the convertible wavelength range of the InGaAs cells reached 0.95, and the emissivities for non-convertible wavelengths were less than 0.3. - Highlights: • The lattice structure of metal phase VO2 does not change with temperature. • The influences of scales on the emission of a 2D VO2 PhC are discussed. • A 2D VO2 photonic crystal emitter matched well with InGaAs cell is designed. • The matched VO2 PhC emitter can highly improve the TPV system efficiency

  4. A low-emittance lattice for SPEAR

    Science.gov (United States)

    Safranek, J.; Wiedemann, H.

    1992-08-01

    The design and implementation of a low emittance lattice for the SPEAR storage ring including measurements of the performance of the lattice are presented [J. Safranek, Ph.D. thesis, Stanford University, 1991]. The low emittance lattice is designed to optimize the performance of SPEAR as a synchrotron radiation source while keeping SPEAR hardware changes at a minimum. The horizontal emittance of the electron beam in the low emittance lattice is reduced by a factor of 4 from the previous lattice. This reduces the typical horizontal source size and divergence of the photon beams by a factor of 2 each and increases the photon beam brightness. At 3 GeV the horizontal emittance is 129π nm rad, which makes the low emittance lattice the lowest emittance, running synchrotron radiation source in the world in the 1.5 to 4.0 GeV energy range for the emittance scaled to 3 GeV. The measured vertical emittance was reduced to half that typically seen at SPEAR in the past. The brightness of the photon beams was further increased by reducing βy at the insertion devices to 1.1 m and reducing the energy dispersion at the insertion devices by more than a factor of 2 on average. The horizontal dispersion at the rf cavities was reduced by a factor of nearly 4 which gives much less problems with synchrobetatron resonances. The dynamic and physical apertures of the lattice are large, giving long beam lifetimes and easy injection of electrons. The measurements of the linear optics and intensity dependent phenomena gave reasonable agreement with the design. The overall performance of the machine was very good. Injection rates of 10 to 20 mA/min and larger were achieved routinely, and 100 mA total current was stored. Repeated ramping of stored beam from the injection energy of 2.3 GeV to the running energy of 3.0 GeV was achieved with very little beam loss. This low emittance configuration is expected to be the operating configuration for SPEAR starting in January 1992.

  5. Time-zero detector based on microchannel plates and a friable dielectric emitter

    International Nuclear Information System (INIS)

    A microchannel plate detector is used in time - zero detectors as a fast multiplier of secondary electrons. For high energy reaction products emitters efficient for fission fragment detection are inadequate because of the very low secondary electron emission coefficient. One way to increase the detection efficiency is to use emitters with control of secondary electron emission by means of friable dielectrics. Such a set up is presented together with experimental tests with a heavy ion beam

  6. Shaping the electron beams with submicrosecond pulse duration in sources and electron accelerators with plasma emitters

    CERN Document Server

    Gushenets, V I

    2001-01-01

    One studies the techniques in use to shape submicrosecond electron beams and the physical processes associated with extraction of electrons from plasma in plasma emitters. Plasma emitter base sources and accelerators enable to generate pulse beams with currents varying from tens of amperes up to 10 sup 3 A, with current densities up to several amperes per a square centimeter, with pulse duration constituting hundreds of nanoseconds and with high frequencies of repetition

  7. Electron Cloud at Low Emittance in CesrTA

    International Nuclear Information System (INIS)

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  8. Emittance preservation during bunch compression with a magnetized beam

    Science.gov (United States)

    Stratakis, Diktys

    2016-03-01

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based in combining a finite solenoid field where the beam is generated with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth from CSR can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  9. Electron Cloud at Low Emittance in CesrTA

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Mark; /Cornell U., CLASSE; Alexander, James; /Cornell U., CLASSE; Billing, Michael; /Cornell U., CLASSE; Calvey, Joseph; /Cornell U., CLASSE; Conolly, Christopher; /Cornell U., CLASSE; Crittenden, James; /Cornell U., CLASSE; Dobbins, John; /Cornell U., CLASSE; Dugan, Gerald; /Cornell U., CLASSE; Eggert, Nicholas; /Cornell U., CLASSE; Fontes, Ernest; /Cornell U., CLASSE; Forster, Michael; /Cornell U., CLASSE; Gallagher, Richard; /Cornell U., CLASSE; Gray, Steven; /Cornell U., CLASSE; Greenwald, Shlomo; /Cornell U., CLASSE; Hartill, Donald; /Cornell U., CLASSE; Hopkins, Walter; /Cornell U., CLASSE; Kreinick, David; /Cornell U., CLASSE; Kreis, Benjamin; /Cornell U., CLASSE; Leong, Zhidong; /Cornell U., CLASSE; Li, Yulin; /Cornell U., CLASSE; Liu, Xianghong; /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /CERN /CERN /CERN /CERN /CERN /CERN; /more authors..

    2012-07-06

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  10. Emittance preservation during bunch compression with a magnetized beam

    Energy Technology Data Exchange (ETDEWEB)

    Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-02

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based on combining a finite solenoid field where the beam is generated together with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  11. A New SIMOX Emitter Switching Thyristor--BO-ECT

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bo; Alex Q.Huang

    2001-01-01

    SIMOX Emitter switching thyristor(SIMEST) is a new MOS-gated thyristor with highvoltage current saturation capability. In this paper,an improved SIMEST, the Buried-Oxide Emitter Controlled Thyristor (BO-ECT) is proposed. Comparing with the SIMEST, the BO-ECT not only has a simple gate and source metalization structure and is therefore easy for layout design, but it also has an improved high-voltage current saturation capability. The operational mechanism and the forward biased safe operating area (FBSOA) are analyzed. Two-dimensional simulation results indicate that the BO-ECT has a much lower forward voltage drop than that of the IGBT while at the same time has a wider or similar FBSOA as the IGBT.

  12. Emittance Measurements from a Laser Driven Electron Injector

    International Nuclear Information System (INIS)

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 (angstrom), the LCLS requires an electron injector that can produce an electron beam with approximately 1 π mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be ∼ 13 π mm-mrad for 5 ps and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.5 π mm-mrad

  13. Emittance Measurement for Beamline Extension at the PET Cyclotron

    Directory of Open Access Journals (Sweden)

    Sae-Hoon Park

    2016-01-01

    Full Text Available Particle-induced X-ray emission is used for determining the elemental composition of materials. This method uses low-energy protons (of several MeV, which can be obtained from high-energy (of tens MeV accelerators. Instead of manufacturing an accelerator for generating the MeV protons, the use of a PET cyclotron has been suggested for designing the beamline for multipurpose applications, especially for the PIXE experiment, which has a dedicated high-energy (of tens MeV accelerator. The beam properties of the cyclotron were determined at this experimental facility by using an external beamline before transferring the ion beam to the experimental chamber. We measured the beam profile and calculated the emittance using the pepper-pot method. The beam profile was measured as the beam current using a wire scanner, and the emittance was measured as the beam distribution at the beam dump using a radiochromic film. We analyzed the measurement results and are planning to use the results obtained in the simulations of external beamline and aligned beamline components. We will consider energy degradation after computing the beamline simulation. The experimental study focused on measuring the emittance from the cyclotron, and the results of this study are presented in this paper.

  14. Superconducting wiggler magnets for beam-emittance damping rings

    CERN Document Server

    Schoerling, Daniel

    2012-01-01

    Ultra-low emittance beams with a high bunch charge are necessary for the luminosity performance of linear electron-positron colliders, such as the Compact Linear Collider (CLIC). An effective way to create ultra-low emittance beams with a high bunch charge is to use damping rings, or storage rings equipped with strong damping wiggler magnets. The remanent field of the permanent magnet materials and the ohmic losses in normal conductors limit the economically achievable pole field in accelerator magnets operated at around room temperature to below the magnetic saturation induction, which is 2.15 T for iron. In wiggler magnets, the pole field in the center of the gap is reduced further like the hyperbolic cosine of the ratio of the gap size and the period length multiplied by pi. Moreover, damping wiggler magnets require relatively large gaps because they have to accept the un-damped beam and to generate, at a small period length, a large magnetic flux density amplitude to effectively damp the beam emittance....

  15. Comparison between 50 W tapered laser arrays and tapered single emitters

    Science.gov (United States)

    Scholz, Christian; Boucke, Konstantin; Poprawe, Reinhart; Keleman, Marc T.; Weber, Jürgen; Mikulla, Michael; Weimann, Günter

    2006-02-01

    During the last few years high power diode laser arrays have become well established for direct material processing due to their high efficiency of more than 50%. But standard broad-area waveguide designs are susceptible to modal instabilities and filamentations resulting in low beam qualities. The beam quality increases by more than a factor of four by using tapered laser arrays, but so far they suffer from lower efficiencies. Therefore tapered lasers are mainly used today as single emitters in external resonator configurations. With increased output power and lifetime, they will be much more attractive for material processing and for pumping of fiber amplifiers. High efficiency tapered mini bars emitting at a wavelength of 980 nm are developed, and in order to qualify the bars, the characteristics of single emitters and mini bars from the same wafer have been compared. The mini bars have a width of 6 mm with 12 emitters. The ridge waveguide tapered lasers consist of a 500 μm long ridge and a 2000 μm long tapered section. The results show very similar behavior of the electro-optical characteristics and the beam quality for single emitters and bars. Due to different junction temperatures, different slope efficiencies were measured: 0.8 W/A for passively cooled mini bars and 1.0 W/A for actively cooled mini-bars and single emitters. The threshold current of 0.7 A per emitter is the same for single emitters and emitter arrays. Output powers of more than 50 W in continuous wave mode for a mini bar with standard packaging demonstrates the increased power of tapered laser bars.

  16. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core

    OpenAIRE

    Thomas, Jens; Ma, Chung-Pei; McConnell, Nicholas J.; Greene, Jenny E.; Blakeslee, John P.; Janish, Ryan

    2016-01-01

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day dormant descendants of this population of active black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central regio...

  17. Molecular breast imaging with gamma emitters.

    Science.gov (United States)

    Schillaci, O; Spanu, A; Danieli, R; Madeddu, G

    2013-12-01

    Following a diagnosis of breast cancer (BC), the early detection of local recurrence is important to define appropriate therapeutic strategies and increase the chances of a cure. In fact, despite major progress in surgical treatment, radiotherapy, and chemotherapy protocols, tumor recurrence is still a major problem. Moreover, the diagnosis of recurrence with conventional imaging methods can be difficult as a result of the presence of scar tissue. Molecular breast imaging (MBI) with gamma-ray emitting radiotracers may be very useful in this clinical setting, because it is not affected by the post-therapy morphologic changes. This review summarises the applications of 99mTc-sestamibi and 99mTc-tetrofosmin, the two most employed gamma emitter radiopharmaceuticals for MBI, in the diagnosis of local disease recurrence in patients with BC. The main limitation of MBI using conventional gamma-cameras is the low sensitivity for small BCs. The recent development of hybrid single photon emission computed tomography/computed tomography devices and especially of high-resolution specific breast cameras can improve the detection rate of sub-centimetric malignant lesions. Nevertheless, probably only the large availability of dedicated cameras will allow the clinical acceptance of MBI as useful complementary diagnostic technique in BC recurrence. The possible role of MBI with specific cameras in monitoring the local response of BC to neoadjuvant chemotherapy is also briefly discussed. PMID:24322791

  18. Hafnium carbide nanocrystal chains for field emitters

    International Nuclear Information System (INIS)

    A hafnium carbide (HfC) nanostructure, i.e., HfC nanocrystal chain, was synthesized by a chemical vapor deposition (CVD) method. X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray spectrometer were employed to characterize the product. The synthesized one-dimensional (1D) nanostructures with many faceted octahedral nanocrystals possess diameters of tens of nanometers to 500 nm and lengths of a few microns. The chain-like structures possess a single crystalline structure and preferential growth direction along the [1 0 0] crystal orientation. The growth of the chains occurred through the vapor–liquid–solid process along with a negative-feedback mechanism. The field emission (FE) properties of the HfC nanocrystal chains as the cold cathode emitters were examined. The HfC nanocrystal chains display good FE properties with a low turn-on field of about 3.9 V μm−1 and a high field enhancement factor of 2157, implying potential applications in vacuum microelectronics.

  19. Time-Resolved Emittance Characterization of an Induction Linac Beam using Optical Transition Radiation

    CERN Document Server

    Le Sage, G P

    2002-01-01

    An induction linac is used by Lawrence Livermore National Laboratory to perform radiographic testing at the Flash X-ray Radiography facility. Emittance characterization is important since x-ray spot size impacts the resolution of shadow-graphs. Due to the long pulse length, high current, and beam energy, emittance measurement using Optical Transition Radiation is an attractive alternative for reasons that will be described in the text. The utility of OTR-based emittance measurement has been well demonstrated for both RF and induction linacs. We describe the time-resolved emittance characterization of an induction linac electron beam. We have refined the optical collection system for the induction linac application, and have demonstrated a new technique for probing the divergence of a subset of the beam profile. The experimental apparatus, data reduction, and conclusions will be presented. Additionally, a new scheme for characterizing the correlation between beam divergence and spatial coordinates within the b...

  20. Time-Resolved Emittance Characterization of an Induction Linac Beam using Optical Transition Radiation

    International Nuclear Information System (INIS)

    An induction linac is used by Lawrence Livermore National Laboratory to perform radiographic testing at the Flash X-ray Radiography facility. Emittance characterization is important since x-ray spot size impacts the resolution of shadow-graphs. Due to the long pulse length, high current, and beam energy, emittance measurement using Optical Transition Radiation is an attractive alternative for reasons that will be described in the text. The utility of OTR-based emittance measurement has been well demonstrated for both RF and induction linacs. We describe the time-resolved emittance characterization of an induction linac electron beam. We have refined the optical collection system for the induction linac application, and have demonstrated a new technique for probing the divergence of a subset of the beam profile. The experimental apparatus, data reduction, and conclusions will be presented. Additionally, a new scheme for characterizing the correlation between beam divergence and spatial coordinates within the beam profile will be described

  1. Describing a Laser Diode Emulation Tool Using Single Emitter Simulation Results

    Directory of Open Access Journals (Sweden)

    C.K. Amuzuvi

    2013-02-01

    Full Text Available This study describes and explores the use of a laser diode simulation tool at the single emitter level of operation and how they can be degraded. A test of the simulation tool is implemented to complement the by-emitter degradation analysis of high power laser diodes. The simulation tool is called Speclase, designed for the simulation of single emitters. Tests were performed using a 975 nm narrow-angle (<1º tapered laser structure from Alcatel Thales III-V Lab with front and rear facet reflectivities of 3 and 90%, respectively. The tool worked for both the constant current and power modes of operation. Simulation results were obtained for both constant QW trap density, based on the maximum QW temperature and variable QW trap density generation due to local heating. Single emitter degradation results are obtained using the Arrhenius equation to compare the rate of degradation between the constant and variable QW trap densities.

  2. Self-field-driven rms emittances of a field-photoemitted intense short relativistic electron beam

    International Nuclear Information System (INIS)

    The photoinjector is presently considered as the best source for those low-emittance, short relativistic electron beams that various applications require. For high-current beams, the emittance growth is dominated by the self-field effects, and essentially located near the photocathode. In this region the electrons are submitted to a very strong acceleration so that the self-field effects cannot be considered as space-charge ones: relativistic acceleration and retardation phenomena have to be taken into account. A systematic study of transverse, longitudinal and 3D r.m.s. emittances, as a function of beam parameters and RF field intensity is presented, by extending preliminary results on the r.m.s. transverse emittances. (author) 5 refs.; 7 figs

  3. Engineering and localization of quantum emitters in large hexagonal boron nitride layers

    CERN Document Server

    Choi, Sumin; ElBadawi, Christopher; Lobo, Charlene; Wang, Xuewen; Juodkazis, Saulius; Seniutinas, Gediminas; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Hexagonal boron nitride (hBN) is a wide bandgap van der Waals material that has recently emerged as promising platform for quantum photonics experiments. In this work we study the formation and localization of narrowband quantum emitters in large flakes (up to tens of microns wide) of hBN. The emitters can be activated in as-grown hBN by electron irradiation or high temperature annealing, and the emitter formation probability can be increased by ion implantation or focused laser irradiation of the as-grown material. Interestingly, we show that the emitters are always localized at edges of the flakes, unlike most luminescent point defects in 3D materials. Our results constitute an important step on the road map of deploying hBN in nanophotonics applications.

  4. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    Energy Technology Data Exchange (ETDEWEB)

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  5. Diamond-based single-photon emitters

    International Nuclear Information System (INIS)

    The exploitation of emerging quantum technologies requires efficient fabrication of key building blocks. Sources of single photons are extremely important across many applications as they can serve as vectors for quantum information-thereby allowing long-range (perhaps even global-scale) quantum states to be made and manipulated for tasks such as quantum communication or distributed quantum computation. At the single-emitter level, quantum sources also afford new possibilities in terms of nanoscopy and bio-marking. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, as they are a photostable solid-state source of single photons at room temperature. In this review, we discuss the state of the art of diamond-based single-photon emitters and highlight their fabrication methodologies. We present the experimental techniques used to characterize the quantum emitters and discuss their photophysical properties. We outline a number of applications including quantum key distribution, bio-marking and sub-diffraction imaging, where diamond-based single emitters are playing a crucial role. We conclude with a discussion of the main challenges and perspectives for employing diamond emitters in quantum information processing.

  6. Variable emittance behavior of smart radiative coating

    Science.gov (United States)

    Guo, Li; Fan, Desong; Li, Qiang

    2016-02-01

    Smart radiative coating on yttria stabilized zirconia (YSZ) substrate was prepared by the sol-gel La{}1-xSr x MnO3 (x = 0.125, 0.175 and 0.2) nanoparticles and the binder composed of terpineol and ethyl cellulose. The crystallized structure, grain size, chemical compositions, magnetization and the surface morphology were characterized. The thermal radiative properties of coating in the infrared range was evaluated from infrared reflectance spectra at various temperatures. A single perovskite structure is detected in sol-gel nanoparticles with size 200 nm. Magnetization measurement reveals that room temperature phase transition samples can be obtained by appropriate Sr substitution. The influence of surface conditions and sintering temperature on the emittance of coating was observed. For rough coatings with root-mean-square roughness 640 nm (x = 0.125) and 800 nm (x = 0.175) , its emittance increment is 0.24 and 0.26 in in the temperature range of 173-373 K. Increasing sintering temperature to 1673 K, coating emittance variation improves to 0.3 and 0.302 respectively. After mechanical polishing treatment, the emittance increment of coatings are enhanced to 0.31 and 0.3, respectively. The results suggested that the emittance variation can be enhanced by reducing surface roughness and increasing sintering temperature of coating.

  7. Evaluation of an Electrochromic Device for Variable Emittance in Simulated Space Conditions

    Science.gov (United States)

    Puterbaugh, Rebekah L.; Mychkovsky, Alexander G.; Ponnappan, Rengasamy; Kislov, Nikolai

    2005-02-01

    Unprotected skin and external surfaces of a spacecraft in earth orbit may experience temperature variations from -50°C to +100°C during exposure to cold space or sun. As a result, thermal management of spacecraft becomes extremely important. One latest trend is to provide flexibility and control in the thermal design that involves variable emittance surfaces consisting of electrochromic (EC) coatings. For investigational purposes, a sample electrochromic device is evaluated for variable emittance in simulated space conditions. A vacuum chamber with a liquid nitrogen circulated blackbody shroud is employed to simulate space conditions. The 63.5 × 63.5 mm test sample supplied by a small business research firm is mounted on an aluminum plate heated by an electrical resistance heater. The sample is thermally insulated by a heat shield from all surroundings excluding the active front surface facing the shroud. The heat shield is uniformly maintained at the sample temperature using an independent circuit of resistance heaters and temperature controllers. A steady state energy balance is applied to the test sample to determine the emittance as a function of temperature and DC bias voltage applied across the anode and cathode. Tests were performed to verify the switchability from high to low emittance states and vice versa. The difference between the high and low emittance values (Δɛ) obtained in the present calorimetric measurement is compared with the data obtained from FTIR measurements performed by the supplier of the EC sample. Results obtained in the present experiments compare closely with supplier data and prove the effectiveness of the variable emittance sample in space conditions. The validity of the calorimetric experiment is confirmed by testing materials with known emittances, such as black paint and polished metals. Error analysis of the system predicts an emittance accuracy of ±5% at sample temperatures in the range of -50°C to 100°C.

  8. Investigations on the transverse phase space at a photo injector for minimized emittance

    International Nuclear Information System (INIS)

    Radio frequency photoinjectors are electron sources able to generate beams of extremely high brightness, which are applicable to linac driven Free Electron Lasers (FEL). Because of the high phase space density, the dynamics of the electron beam is dominated by space charge interactions between the particles. This thesis studies the transverse phase space of space charge dominated electron beams produced by the Photo Injector Test Facility in Zeuthen (PITZ). The operation conditions for minimizing the transverse emittance are studied experimentally, theoretically and in simulations. The influence of the longitudinal profile of the driving UV laser pulse on the transverse emittance is investigated. Emphasis is placed on the experimental study of the emittance as a function of different machine parameters like the laser beam spot size, the amplitude of the focusing magnetic field, the rf phase and the electron bunch charge. First investigations on the thermal emittance for Cs2Te photocathodes under rf operating conditions are presented. Measurements of the thermal emittance scaling with the photocathode laser spot size are analyzed. The significance of the applied rf field in the emittance formation process is discussed. (orig.)

  9. Investigations on the transverse phase space at a photo injector for minimized emittance

    Energy Technology Data Exchange (ETDEWEB)

    Miltchev, V.

    2006-08-15

    Radio frequency photoinjectors are electron sources able to generate beams of extremely high brightness, which are applicable to linac driven Free Electron Lasers (FEL). Because of the high phase space density, the dynamics of the electron beam is dominated by space charge interactions between the particles. This thesis studies the transverse phase space of space charge dominated electron beams produced by the Photo Injector Test Facility in Zeuthen (PITZ). The operation conditions for minimizing the transverse emittance are studied experimentally, theoretically and in simulations. The influence of the longitudinal profile of the driving UV laser pulse on the transverse emittance is investigated. Emphasis is placed on the experimental study of the emittance as a function of different machine parameters like the laser beam spot size, the amplitude of the focusing magnetic field, the rf phase and the electron bunch charge. First investigations on the thermal emittance for Cs{sub 2}Te photocathodes under rf operating conditions are presented. Measurements of the thermal emittance scaling with the photocathode laser spot size are analyzed. The significance of the applied rf field in the emittance formation process is discussed. (orig.)

  10. Development of real-time emittance monitor using pepper-pot method

    International Nuclear Information System (INIS)

    At Osaka University RCNP cyclotron facility, researches aimed at high-intensity and high quality of the proton beam have been carried out. In the current beam acceleration, there is one problem that the beam generated by the ion source is not injected to the AVF cyclotron downstream efficiently. This is due to the mismatch of acceptance of the AVF and the emittance of the ion source beam. Therefore, in order to realize the beam injection more efficient, it is necessary to measure and evaluate emittance and phase space distributions of the beam rapidly. In our facility, emittance measurements using a slit and a rotating profile monitor have been performed. Thus, the measurement time shortened from 30 minutes to 75 seconds. Thus, it becomes possible to adjust the parameters of the beam transport system and the ion source while the measure emittance, however, in order to improve the control of the beam further, we're aiming the development of real-time emittance measurement system using pepper-pot method. Since we moved a slit in the conventional emittance measurement system mechanically, it took a measurement time of 1 minute because it becomes rate-determining. On the other hand, since there is no mechanical drive in repeated measurements by using a MCP and pepper-pot mask drilled uniformly in pepper-pot method, significant shortening of measurement time is expected than the measurement time using a slit current. (author)

  11. Development of C-band deflector for slice emittance monitoring of new electron gun

    International Nuclear Information System (INIS)

    The advanced RF electron gun was installed for an electronic source of a high charge and a low emittance in KEK e+/e- Linac, and the sliced bunch monitor is needed to achieve the required emittance for the SuperKEKB injection. In the KEK-Linac, we are monitoring using a fluorescent plate on the beam line. It is possible to measure the projection emittance of the beam in this way, however it is not possible to measure the slice emittance. To develop an electron gun which can be generating a beam of super-low emittance corresponding to SuperKEKB, monitoring of the slice emittance is required. The slice of time direction on a beam can be acquired by measuring the beam sliced with the RF-deflector using a fluorescent plate. RF-deflector performance is square root of RF frequency, has developed a high-powered ones corresponding to 10 GeV beam using X-band frequency at near the end of KEK-Linac. However, because the beam energy is about 10 MeV at the RF gun exit, enough resolution is obtained even by low energy. So, we have developed a new low energy RF-deflector using C-band frequency. (author)

  12. Sectional and projectional emittance measurements (abstract)a

    International Nuclear Information System (INIS)

    For many applications of ion sources the quality of the generated ion beam plays an increasingly important role. Ion sources consist of the plasma generator and the extraction system. Both parts can, due to high ion temperature or various aberrations, contribute to a degrading of the beam quality. Though the beam quality is determined by many more factors, the transverse motion of the particles certainly is one of the important parameters. Knowledge of it can be obtained by an emittance measurement. This is best done in a four-dimensional phase space, yielding a density distribution as function of the transverse spatial and momentum coordinates. Often, however, due to practical considerations, only two dimensions of the four-dimensional open-quote open-quote trace space close-quote close-quote are being measured. This two-dimensional data can be obtained as a section or as a projection of the four-dimensional trace space, where both methods have their merits. Projectional emittance measurements can usually be performed much easier and quicker, but by the projection of the four-dimensional space onto a two-dimensional plane information is lost. And although not all the particles of the beam are represented in a section of trace space, here aberrative distortions of the emittance can be seen most clearly and allow an easier comparison to numerically obtained data. The advantages and disadvantages of both methods are discussed. Numerical and experimental examples are presented. copyright 1996 American Institute of Physics

  13. Silicon Carbide Emitter Turn-Off Thyristor

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2008-01-01

    Full Text Available A novel MOS-controlled SiC thyristor device, the SiC emitter turn-off thyristor (ETO is a promising technology for future high-voltage switching applications because it integrates the excellent current conduction capability of a SiC thyristor with a simple MOS-control interface. Through unity-gain turn-off, the SiC ETO also achieves excellent Safe Operation Area (SOA and faster switching speeds than silicon ETOs. The world's first 4.5-kV SiC ETO prototype shows a forward voltage drop of 4.26 V at 26.5 A/cm2 current density at room and elevated temperatures. Tested in an inductive circuit with a 2.5 kV DC link voltage and a 9.56-A load current, the SiC ETO shows a fast turn-off time of 1.63 microseconds and a low 9.88 mJ turn-off energy. The low switching loss indicates that the SiC ETO could operate at about 4 kHz if 100 W/cm2 conduction and the 100 W/cm2 turn-off losses can be removed by the thermal management system. This frequency capability is about 4 times higher than 4.5-kV-class silicon power devices. The preliminary demonstration shows that the SiC ETO is a promising candidate for high-frequency, high-voltage power conversion applications, and additional developments to optimize the device for higher voltage (>5 kV and higher frequency (10 kHz are needed.

  14. Performance comparisons of low emittance lattices

    International Nuclear Information System (INIS)

    The results of a performance analysis of four low emittance electron storage ring lattices provided to the authors by various members of the Lattice Working Group is presented. Altogether, four lattices were investigated. The beam energies of the four lattices are, respectively, 1.1, 2, 3, 4 GeV). A brief summary of the lattice parameters relevant to this study is given. The performance issues studied include an estimation of the longitudinal emittance expected for each lattice based on the effects of the longitudinal microwave instability, an estimation of the transverse emittance growth of the (required) dense bunches under the influence of intrabeam scattering (IBS), and an estimate of the Touschek lifetime. The analysis described here has been carried out with the LBL accelerator physics code ZAP

  15. Academic Pork Barrel Tops $2-Billion for the First Time.

    Science.gov (United States)

    Brainard, Jeffrey; Borrego, Anne Marie

    2003-01-01

    Describes how, despite the growing budget deficit, Congress directed a record $2 billion to college projects in 2003, many of them dealing with security and bioterrorism. Includes data tables on the earmarks. (EV)

  16. God particle disappears down 6 billion pound drain

    CERN Multimedia

    Henderson, M

    2001-01-01

    An estimated 6 billion pounds has been spent looking for the Higgs particle over the last three decades. Recent results from LEP though, are now causing some scientists to doubt that it exists at all (1 page).

  17. Summary and Comparison of the 2016 Billion-Ton Report with the 2011 U.S. Billion-Ton Update

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-06-01

    In terms of the magnitude of the resource potential, the results of the 2016 Billion-Ton Report (BT16) are consistent with the original 2005 Billion-Ton Study (BTS) and the 2011 report, U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry (BT2. An effort was made to reevaluate the potential forestland, agricultural, and waste resources at the roadside, then extend the analysis by adding transportation costs to a biorefinery under specified logistics assumptions to major resource fractions.

  18. Coupling single emitters to quantum plasmonic circuits

    CERN Document Server

    Huck, Alexander

    2016-01-01

    In recent years the controlled coupling of single photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic non-linearity on a nano-scaled platform. In this article we will review the recent progress on coupling single emitters to nano-wires towards the construction of a new platform for strong light-matter interaction. The control over such a platform might open new doors for quantum information processing and quantum sensing at the nanoscale, and for the study of fundamental physics in the ultra-strong coupling regime.

  19. Quadrupole Transfer Function for Emittance Measurement

    CERN Document Server

    Cameron, Peter; Jansson, Andreas; Tan, Cheng-Yang

    2008-01-01

    Historically the use of the quadrupole moment measurement has been impeded by the requirement for large dynamic range, as well as measurement sensitivity to beam position. We investigate the use of the transfer function technique [1-3] in combination with the sensitivity and 160dB revolution line rejection of the direct diode detection analog front end [4] to open the possibility of an emittance diagnostic that may be implemented without operational complication, quasi- parasitic to the operation of existing tune measurement systems. Such a diagnostic would be particularly useful as an emittance monitor during acceleration ramp development in machines like RHIC and the LHC.

  20. Studies of emittance growth in the ATF

    International Nuclear Information System (INIS)

    Several different mechanisms of emittance growth in the Accelerator Test Facility (ATF) at KEK are investigated: the author calculates rise times of the fast beam-ion instability for the damping ring (DR), and discusses the emittance growth caused by coherent synchrotron radiation in the beam-transport line (BT), the effect of quadrupole wake fields in the injector linac, and, finally, a single-bunch head-tail ion effect that can occur in both the DR and the BT. A first attempt to measure the quadrupole wake on the real machine is also reported

  1. Research on Radar Emitter Attribute Recognition Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described in detail. A new attribute recognition method based on attribute measure is presented in this paper. Application example is given, which demonstrates this new method is accurate and effective. Moreover, computer simulation for recognizing the emitter purpose is selected, and compared with classical statistical pattern recognition through simulation. The excellent experimental results demonstrate that this is a brand-new attribute recognition method as compared to existing statistical pattern recognition techniques.

  2. Structural and magnetic effects on thermal emittance of La1−xSrxMnO3 from the first principles calculation

    International Nuclear Information System (INIS)

    Generalized gradient approximation (GGA) exchange-correlation functional was used in the first-principles method to calculate thermal emittance of La1−xSrxMnO3 (LSMO). The effects of structure and magnetism on thermal emittance of LSMO were systematically investigated by the complex dielectric function. It is found that the LSMO with orthorhombic structure has a higher thermal emittance than that with rhombohedral structure at the same temperature. When the magnetism varying with temperature of LSMO is put into consideration, the magnetic different make a significant change on thermal emittance and the variation of thermal emittance of La0.75Sr0.25MnO3 is the biggest among x=0, 0.2, 0.25, 0.5. It is found that thermal emittance have a low value at the low temperature and have a high value at the high temperature, due to the unique feature of variable thermal emittance based on metal-insulator transition, which makes LSMO attractive as potential thermal control materials. - Highlights: • The emittance of La1-xSrxMnO3 (LSMO) varies with different magnetism state. • Orthorhombic LSMO has larger emittance than rhombohedral LSMO at same temperature. • If the magnetism varying with temperature of LSMO is considered, the variation of emittance of La0.75Sr0.25MnO3 is the biggest among x=0, 0.2, 0.25 and 0.5

  3. Double-step annealing and ambient effects on phosphorus implanted emitters in silicon

    International Nuclear Information System (INIS)

    Emitters of npn silicon bipolar transistors have been made by a phosphorus implantation at 50 keV P+ to a dose of 1 x 1016cm-2. This was followed by high temperature processes to reduce lattice disorder, to drive-in the phosphorus atoms, and to form oxide layers. The first process step was carried out by using single- and double-step anneals in various ambients (dry N2, dry 02 and steam) while the drive-in and oxidation steps were common for all structures. Electrical measurements on emitter/base leakage current, low frequency (popcorn) noise and current gain showed that the annealing ambient had a major influence. The transistors with implanted emitters annealed in a dry N2 ambient are comparable to commercial ones with thermally-diffused emitters. Transmission electron microscopy observations on samples annealed in steam ambients revealed dislocations extending into the sidewall of the emitter/base junction. This sidewell penetration of dislocations is the main origin of the degradation of the emitter/base junction characteristics. (author)

  4. Biological effects of positron emitters in thyroid cell cultures

    International Nuclear Information System (INIS)

    Full text of publication follows. Aim: Today, the use of 124I- (β+, half-life 4.2 d) is an increasing field in positron emission tomography (PET). In principle, positrons deposit their energy in the surrounding material like electrons. Therefore, we investigated the biological effects of positron emitters in comparison to electrons in vitro. Materials and Methods: two different thyroid cell lines (Fischer Rat Thyroid Cell Line No. 5 (FRTL5) and human papillary thyroid cancer cell line BCPAP) were investigated in vitro. While FRTL5 has been described to express a high level of sodium iodine transporter (NIS), the NIS expression of BCPAP is known to be low. Parallel cultures were incubated with either 50 -400 kBq/ml 124I- (IBA) or 50-400 kBq/ml 131I- (GE Health care). Cell count and radioiodine uptake were determined 24 h to 144 h after isotope application. Additionally, 4',6-diamidino-2-phenylindole (DAPI) staining of ethanol fixed cells was performed and induced apoptosis was determined by morphological analysis of the cell nucleus (condensation, fragmentation) by fluorescence microscopy. Results: BCPAP showed no significant uptake (<0.1 % per one million cells). The proliferation of BCPAP cells was not significantly influenced by radioiodine incubation. The uptake of NIS-expressing FRTL5 cells ranged between 0.6 % and 4 % per one million cells, independently of the isotope. In FRTL5 cells the incubation with 131I- induced a significant dose-dependent inhibition of proliferation (p<0.05). The positron emitter 124I- induced analogue effects on proliferation compared to the electron emitter 131I- (30-40 % inhibition, 144 h incubation with 400 kBq/ml). In parallel, in FRTL5 cell lines an isotope-independent increase of morphological changes in the cell nuclei (up to 5 fold) could be determined. In contrast, no significant changes could be verified in BCPAP cell nuclei. Conclusions: As expected from the physical point of view, the biological effects of positrons

  5. Mining survival in parts per billion

    International Nuclear Information System (INIS)

    The paper discusses the economic situation in the coal industry of Utah. Coal prices are down for the tenth year in a row, Utah is isolated from major markets and freight rates are high, and the state legislature has not dropped the issue of a coal severance tax. The author believes the only potential for increased use of Utah coal is the Pacific Rim countries. Environmental issues are also discussed

  6. Measurement of alpha emitters in radioactive waste

    International Nuclear Information System (INIS)

    The alpha emitters measurement in radioactive waste (10-2Ci/T) is essential for a good fissil materials management. This paper describes 3 classes of devices: device using a neutronic passive counting, device using a neutronic activation and detection of fission gamma, device using a neutronic activation and detection of prompt neutrons fission

  7. Longitudinal emittance measurements at REX-ISOLDE

    CERN Document Server

    Fraser, M A; Jones, R.M.; Jones, R M; Pasini, M; Posocco, P A; Voulot, D; Wenander, F

    2012-01-01

    We report on measurements of the longitudinal emittance at the Radioactive ion beam EXperiment (REX) at ISOLDE, CERN. The rms longitudinal emittance was measured as 0.34 ± 0.08 π ns keV/u at the output of the RFQ and as 0.36 ± 0.04π ns keV/u in front of the third 7-gap split-ring resonator (7G3) using the three-gradient technique; systematic errors are not included but are estimated at approximately 10%. The 86% emittance was measured a factor of approximately 4.4 times larger than the rms emittance at 1.48 ± 0.2 and 1.55 ± 0.12π ns keV/u at the RFQ and 7G3, respectively. The REX switchyard magnet was used as a spectrometer to analyse the energy spread of the beam as it was manipulated by varying the voltage of the rebuncher (ReB) and 7G3 cavities operating at non-accelerating phases. The transfer matrix for a multi-gap bunching cavity is derived and suitably truncated to allow for the accurate reconstruction of the beam parameters from measurement. The technique for measuring the energy spread was rig...

  8. Emittance in particle and radiation beam techniques

    International Nuclear Information System (INIS)

    The author discusses the important and diverse role of the phase space area - the emittance - in the advanced techniques involving interaction of particle and radiation beams. For undulator radiation from unbunched beams, the radiation phase space is diluted from the coherent phase space of the single electron radiation. When the undulator radiation is used as a light source, it is important to minimize the dilution by decreasing the beam emittance and matching the phase space distributions of the particle and the radiation beams. For optical stochastic cooling, on the other hand, the phase space should be maximally mismatched for efficient cooling. In the case particles are bunched to a length much shorter than the radiation wavelength, the emittance appears as an intensity enhancement factor. In the operation of free electron lasers, the phase space matching becomes doubly important, once as the dilution factor in the initial stage of energy modulation and then as the radiation efficiency factor at the end where the beam is density modulated. The author then discusses some of the beam cooling techniques producing smaller emittances, especially the recent suggestions for relativistic heavy ions in storage rings or electron beams in linacs. These are based on the radiative cooling that occurs when particle beams backscatter powerful laser beams

  9. Alpha-emitters in the workplace

    International Nuclear Information System (INIS)

    A number of groups of workers have been exposed to α;-particle-emitting radionuclides, of particular importance being the radium dial painters, underground hard rock miners exposed to radon and its decay products, and, more recently, plutonium workers. These occupationally exposed groups are of interest because they allow the direct study of the health effects of exposure to alpha-emitters and the comparison with the level of such effects present among groups exposed predominantly to external sources of low-LET radiation. Hence, these worker groups are important in testing the assumptions that underlie radiological protection. The radium dial painters experienced a pronounced excess of bone cancers and cancers of the paranasal sinuses and mastoid air cells, while a clear radon-related excess of lung cancer is present among the underground hard rock miners. There is little evidence for a radiation-related excess risk of other cancers being present in these groups. A number of groups of workers have been exposed to plutonium in the weapons and civil nuclear industries. The group of plutonium workers at the Mayak nuclear facility in Russia is especially important because of the large numbers exposed to high levels. The Mayak workers have pronounced plutonium-related excess risks of lung, liver and bone cancers, and possibly of other solid tumours, but not leukaemia. Where organ-specific internal doses have been derived, which is presently confined to the lung, risk coefficients are compatible with predictions based on standard models. However, further investigations of the Mayak workforce are required before reliable risk estimates for plutonium exposure may be derived, but this group of workers has the potential of generating definitive risk coefficients for health effects arising from exposure to plutonium. (orig.)

  10. Eight billion asteroids in the Oort cloud

    CERN Document Server

    Shannon, Andrew; Veras, Dimitri; Wyatt, Mark

    2014-01-01

    The Oort cloud is usually thought of as a collection of icy comets inhabiting the outer reaches of the Solar system, but this picture is incomplete. We use simulations of the formation of the Oort cloud to show that ~4% of the small bodies in the Oort cloud should have formed within 2.5 au of the Sun, and hence be ice-free rock-iron bodies. If we assume these Oort cloud asteroids have the same size distribution as their cometary counterparts, the Large Synoptic Survey Telescope should find roughly a dozen Oort cloud asteroids during ten years of operations. Measurement of the asteroid fraction within the Oort cloud can serve as an excellent test of the Solar system's formation and dynamical history. Oort cloud asteroids could be of particular concern as impact hazards as their high mass density, high impact velocity, and low visibility make them both hard to detect and hard to divert or destroy. However, they should be a rare class of object, and we estimate globally catastrophic collisions should only occur ...

  11. RF Emitter geolocation using PDOA algorithms and UAVs - A strategy from emitter detection to location prediction

    OpenAIRE

    Engebråten, Sondre Andreas

    2015-01-01

    In this thesis, I explored strategies for locating an RF emitter. Expanding on an idea conceived at Norwegian Defence Research Establishment (FFI), of using small, cheap RSS sensors and Unmanned Aerial Vehicles (UAVs) to search for unknown RF emitters. Cheap and simple, will in most cases, mean that some property of the system suffers, compared to more complicated and expensive systems. This thesis attempts to circumvent these issues by using multiple sensors instead of one ...

  12. On the Equivalent Dose for Auger Electron Emitters

    OpenAIRE

    Howell, Roger W.; Narra, Venkat R.; Sastry, Kandula S. R.; Rao, Dandamudi V.

    1993-01-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201T1) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET α particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (I...

  13. Impact of forward emitter current gain and geometry of pnp power transistors on radiation tolerance of voltage regulators

    International Nuclear Information System (INIS)

    Low-dropout voltage regulators with various geometries and technological realisations of serial pnp power transistors were exposed to ionizing radiation. Although devices with vertical emitters were considered much less susceptible to the influence of radiation on forward emitter current gain than circuits with round emitters, the experiment showed a similar degradation of current gain in both cases. The main reason of high radiation susceptibility of the examined vertical serial pnp transistor is the implementation of an interdigitated emitter, with high perimeter-to-area ratio, causing the great increase of serial transistors base current, but a minor influence on the maximum output current. Transistors with round emitters with small perimeter-to-area ratio expressed a moderate current gain degradation, but a rapid fall of the emitter injection efficiency, causing a significant decrease of the maximum output current. Regardless of the similar forward emitter current gain degradation, reliability and operational characteristics of two types of low-dropout voltage regulators were completely different. (author)

  14. Small horizontal emittance in the TESLA damping ring

    International Nuclear Information System (INIS)

    The present TESLA damping ring is designed for a normalized horizontal emittance of 8x10-6 m. γ-γ collisions at the TESLA linear collider will benefit from a further decrease of the horizontal emittance. This paper reviews the processes which limit the horizontal emittance in the damping ring. Preliminary estimates on the smallest horizontal emittance for the present TESLA damping ring design as well as an ultimate limit of the emittance reachable with the TESLA damping ring concept will be given

  15. Studying fringe field effect of a field emitter array

    International Nuclear Information System (INIS)

    Field emitter arrays on heavy As-doped Si wafer are studied in vacuum nanoelectronics diode configuration. Different shapes of emitters are considered: cone-shaped point-emitters and cylinder-shaped sharp-edge-emitters are compared. Micro scale field enhancement factor on the edge of cylindrical emitter was calculated via home-developed Matlab application and the results are presented. Two types of anode geometry are proposed: plane anode and spherical anode. Experimental and modelling results of surface electric field distribution are presented. The spherical shape of anode allows higher voltage (and higher field emission current) without destructive arcs risk

  16. Thin semiconducting layers and nanostructures as active and passive emitters for thermophotonics and thermophotovoltaics

    Science.gov (United States)

    Catchpole, K. R.; Lin, K. L.; Green, M. A.; Aberle, A. G.; Corkish, R.; Zhao, J.; Wang, A.

    2002-04-01

    Thermophotovoltaics involves the photovoltaic conversion by a receiver cell of radiation from an emitter which could be heated by various sources including sunlight. A prime difference from normal solar photovoltaics is that emitted energy unable to be used by the receiver, in principle, can be recycled allowing high conversion efficiency. Thermophotonics is a recent development of this concept where the emitter is “active”, namely a heated diode, increasing the rate of energy transfer for a given emitter temperature and concentrating emission in an energy range more suited for conversion by the receiver. Even as “passive selective emitters”, thin semiconducting layers may provide an alternative offering increased design flexibility to standard rare-earth doped ceramics. The decreased emitter band gap at high temperature means that for spectral matching, the room temperature band gap of the emitter should be slightly higher than that of the absorber. Low-dimensional structures such as quantum wells, superlattices and nanocrystals offer scope for such band-gap control and for enhanced luminescence.

  17. Longitudinal emittance: An introduction to the concept and survey of measurement techniques including design of a wall current monitor

    Science.gov (United States)

    Webber, Robert C.

    1990-10-01

    The properties of charged particle beams associated with the distribution of the particles in energy and in time can be grouped together under the category of longitudinal emittance. This article is intended to provide an intuitive introduction to the concepts of longitudinal emittance; to provide an incomplete survey of methods used to measure this emittance and related properties of bunch length and momentum spread; and to describe the detailed design of a 6 Ghz bandwidth resistive wall current monitor useful for measuring bunch shapes of moderate to high intensity beams. Overall, the article is intended to be broad in scope, in most cases deferring details to cited original papers.

  18. Longitudinal emittance: An introduction to the concept and survey of measurement techniques including design of a wall current monitor

    International Nuclear Information System (INIS)

    The properties of charged particle beams associated with the distribution of the particles in energy and in time can be grouped together under the category of longitudinal emittance. This article is intended to provide an intuitive introduction to the concepts of longitudinal emittance; to provide an incomplete survey of methods used to measure this emittance and related properties of bunch length and momentum spread; and to describe the detailed design of a 6 Ghz bandwidth resistive wall current monitor useful for measuring bunch shapes of moderate to high intensity beams. Overall, the article is intended to be broad in scope, in most cases deferring details to cited original papers

  19. Longitudinal emittance: An introduction to the concept and survey of measurement techniques including design of a wall current monitor

    International Nuclear Information System (INIS)

    The properties of charged particle beams associated with the distribution of the particles in energy and in time can be grouped together under the category of longitudinal emittance. This article is intended to provide an intuitive introduction to the concepts longitudinal emittance; to provide an incomplete survey of methods used to measure this emittance and the related properties of bunch length and momentum spread; and to describe the detailed design of a 6 Ghz bandwidth resistive wall current monitor useful for measuring bunch shapes of moderate to high intensity beams. Overall, the article is intended to be broad in scope, in most cases deferring details to cited original papers. 37 refs., 21 figs

  20. Emittance growths in resonance crossing at FFAGs

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab; Pang, X.; Wang, F.; Wang, X.; Lee, S.Y.; /Indiana U.

    2007-10-01

    Scaling laws of the emittance growth for a beam crossing the 6th-order systematic space-charge resonances and the random-octupole driven 4th-order resonance are obtained by numerical multi-particle simulations. These laws can be important in setting the minimum acceleration rate and maximum tolerable resonance strength for the design of non-scaling fixed-field alternating gradient accelerators.

  1. Dissipation-enabled efficient excitation transfer from a single photon to a single quantum emitter

    Science.gov (United States)

    Trautmann, N.; Alber, G.

    2016-05-01

    We propose a scheme for triggering a dissipation-dominated highly efficient excitation transfer from a single-photon wave packet to a single quantum emitter. This single-photon-induced optical pumping turns dominant dissipative processes, such as spontaneous photon emission by the emitter or cavity decay, into valuable tools for quantum information processing and quantum communication. It works for an arbitrarily shaped single-photon wave packet with sufficiently small bandwidth provided a matching condition is satisfied which balances the dissipative rates involved. Our scheme does not require additional laser pulses or quantum feedback and does not rely on high finesse optical resonators. In particular, it can be used to enhance significantly the coupling of a single photon to a single quantum emitter implanted in a one-dimensional waveguide or even in a free space scenario. We demonstrate the usefulness of our scheme for building a deterministic quantum memory and a deterministic frequency converter between photonic qubits of different wavelengths.

  2. A Multi-billion Parcel Atmospheric Trajectory Model

    Science.gov (United States)

    Cruz, C.; Clune, T. L.; Lait, L. R.; Ranawake, U.; Burns, R. W.

    2009-12-01

    We present a new parallel implementation of an atmospheric trajectory modelling framework which provides improved numerical accuracy, greater flexibility for specifying experiments, and sufficient raw performance to simultaneously simulate billions of parcel trajectories on suitable computing platforms. The application is parallelized using the Message Passing Interface (MPI) library and can scale efficiently on a wide variety of modern computing platforms. The ability to treat such large numbers of parcels is expected to enable a new generation of experiments to explore questions related to global stratosphere-troposphere exchange, age-of-air spectra, and transport of trace gases and aerosols. The modelling framework is written in C++ for easy integration with other computing technologies. It also provides a great deal of flexibility by allowing users to select from (or add to) alternative subclasses for vertical coordinates (pressure, potential temperature), integration schemes (Runge-Kutta, Euler), meteorological data sources (NCEP/NCAR Reanalsyis, MERRA), data interpolation methods (linear, log-linear, splines), and output (parcel histories, summary statistics, min/max quantities encountered). Significantly improved numerical accuracy, especially near the poles, is provided by expressing integration in terms of purely geometric constructs which avoid various complications associated with spherical coordinates near the poles. The entire package has been rigorously developed using Test-Driven Development (TDD) which both provides confidence in the implementation and should also assist other developers that wish to extend the framework. Several tests are performed to demonstrate the fourth-order Runge-Kutta integration scheme with our spherical geometric constructs. Tilted solid body rotation provides a baseline synthetic wind field for assessing model performance, and a time-varying case is used to examine the errors introduced by interpolating linearly in time

  3. Terahertz emitters based on intracenter transitions in semiconductors

    Science.gov (United States)

    Kolodzey, James; Gupta, Jay P.

    2013-09-01

    Terahertz emitters are important for fundamental studies in an interesting frequency regime and for applications ranging from medical diagnostics to see-through imaging. A simple approach to THz emission from semiconductors is based on intracenter optical transitions in dopants and impurities in semiconductors. The centers can be excited either electrically or optically, and the THz emission occurs when carriers in the dopant upper energy states relax toward the ground state. Both n-type and p-type dopants as well as deep impurities can be used for THz emission from many host semiconductors including silicon, SiC, and GaN. Unlike with conventional p-n junction devices, the centers for THz emission must be occupied and not thermally ionized, which suggests the need for deep energy levels and/or low temperature operation. Significant center occupation at elevated temperatures favors the wide bandgap semiconductors such as SiC and GaN, in which the dopant ionization energy can greatly exceed the thermal energy kBT at room temperature. For example, electrically pumped THz emitters fabricated from nitrogen-doped SiC can operate at temperatures to about 250 K in pulse mode. The SiC emission spectra had peaks from 5 to 12 THz (20 to 50 meV), and these surface-emitting devices produced a peak power density of 30 milliwatt-cm-2 at 77 K, which is suitable for a wide range of high power THz applications. We report the characteristics and limitations of electrically pumped dopanttransition THz emitters, and their performance in several semiconductor systems.

  4. Phase focusing for finite emittance beams

    International Nuclear Information System (INIS)

    An accelerator is a prime example of a physical system in which a beam of particles absorbs energy continuously from externally imposed electromagnetic fields only by remaining in, or very close to synchronism with the fields. Traveling-wave amplifiers are another example. When the injected beam has finite emittance, deviations from exact synchronism can arise, usually limiting the ultimate energy exchange with the fields, and the ultimate emittance of an accelerated beam. A general theory is provided in this paper for a means of limiting deviations from exact synchronism. This can be achieved by providing a small space-varying detuning from synchronism for a particle near the center of the distribution, thus allowing otherwise nonsynchronous particles brief opportunities to enjoy synchronism, and thus to limit their excursions in phase. To illustrate, an example is given of two-stage cyclotron autoresonance acceleration of a finite emittance beam, with and without detuning in the first stage. Space-varying detuning is shown to provide phase focusing in the first stage, lower phase spread at the entrance of the second stage, and thus higher ultimate energy. copyright 1999 American Institute of Physics

  5. Phase focusing for finite emittance beams

    International Nuclear Information System (INIS)

    An accelerator is a prime example of a physical system in which a beam of particles absorbs energy continuously from externally imposed electromagnetic fields only by remaining in, or very close to synchronism with the fields. Traveling-wave amplifiers are another example. When the injected beam has finite emittance, deviations from exact synchronism can arise, usually limiting the ultimate energy exchange with the fields, and the ultimate emittance of an accelerated beam. A general theory is provided in this paper for a means of limiting deviations from exact synchronism. This can be achieved by providing a small space-varying detuning from synchronism for a particle near the center of the distribution, thus allowing otherwise nonsynchronous particles brief opportunities to enjoy synchronism, and thus to limit their excursions in phase. To illustrate, an example is given of two-stage cyclotron autoresonance acceleration of a finite emittance beam, with and without detuning in the first stage. Space-varying detuning is shown to provide phase focusing in the first stage, lower phase spread at the entrance of the second stage, and thus higher ultimate energy

  6. Urban Poor Receive RMB7.1 Billion Cash Help

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    All levels of government have teamed up to dole out more than RMB7.1 billion (US$855.42 million) during the ilrst half of this year to help more than 21 million Chinese urban residents who are living below the minimum standard of living.

  7. The China-ROK Trade Surpasses US$130 Billion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ In 2006,the important trade partnership between China and POK was further strengthened and consolidated.By the end of 2005,POK recognized China's status of market economy, making the bilateral trade environment more fair and reasonable.The governments of both sides have strived for the target of increasing the bilateral trade to US$200 billion by 2012.

  8. With US$5 Billion,China Purchases 42 Boeing Planes

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ On August 8, Air China, China Eastern Airlines, Shanghai Airlines, Xiamen Airlines signed the final Purchase agreement of 42 Boeing planes with Boeing. The price in catalogue is US$5.04 billion. The first plane will be delivered in 2008.

  9. With US$5 Billion,China Purchases 42 Boeing Planes

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      On August 8, Air China, China Eastern Airlines, Shanghai Airlines, Xiamen Airlines signed the final Purchase agreement of 42 Boeing planes with Boeing. The price in catalogue is US$5.04 billion. The first plane will be delivered in 2008.……

  10. International collaboration in SSC (or any $4 billion scientific project)

    International Nuclear Information System (INIS)

    In this paper, the author discusses the superconducting supercollider. This is a project that costs U.S. $4.4 billion. The author spends a short time giving the motivation (which is a scientific motivation) and also giving the idea of how it is possible, with U.S. deficits

  11. A Sawtooth-like Timeline for the First Billion Year of Lunar Bombardment

    OpenAIRE

    Morbidelli, Alessandro; Marchi, Simone; Bottke, William F.; Kring, David A.

    2012-01-01

    We revisit the early evolution of the Moon's bombardment. Our work combines modeling (based on plausible projectile sources and their dynamical decay rates) with constraints from the lunar crater record, radiometric ages of the youngest lunar basins, and the abundance of highly siderophile elements in the lunar crust and mantle. We deduce that the evolution of the impact flux did not decline exponentially over the first billion years of lunar history, but also there was no prominent and "narr...

  12. Extension of the general thermal field equation for nanosized emitters

    Energy Technology Data Exchange (ETDEWEB)

    Kyritsakis, A., E-mail: akyritsos1@gmail.com; Xanthakis, J. P. [Department of Electrical and Computer Engineering, National Technical University of Athens, Zografou Campus, Athens 15700 (Greece)

    2016-01-28

    During the previous decade, Jensen et al. developed a general analytical model that successfully describes electron emission from metals both in the field and thermionic regimes, as well as in the transition region. In that development, the standard image corrected triangular potential barrier was used. This barrier model is valid only for planar surfaces and therefore cannot be used in general for modern nanometric emitters. In a recent publication, the authors showed that the standard Fowler-Nordheim theory can be generalized for highly curved emitters if a quadratic term is included to the potential model. In this paper, we extend this generalization for high temperatures and include both the thermal and intermediate regimes. This is achieved by applying the general method developed by Jensen to the quadratic barrier model of our previous publication. We obtain results that are in good agreement with fully numerical calculations for radii R > 4 nm, while our calculated current density differs by a factor up to 27 from the one predicted by the Jensen's standard General-Thermal-Field (GTF) equation. Our extended GTF equation has application to modern sharp electron sources, beam simulation models, and vacuum breakdown theory.

  13. Extension of the general thermal field equation for nanosized emitters

    International Nuclear Information System (INIS)

    During the previous decade, Jensen et al. developed a general analytical model that successfully describes electron emission from metals both in the field and thermionic regimes, as well as in the transition region. In that development, the standard image corrected triangular potential barrier was used. This barrier model is valid only for planar surfaces and therefore cannot be used in general for modern nanometric emitters. In a recent publication, the authors showed that the standard Fowler-Nordheim theory can be generalized for highly curved emitters if a quadratic term is included to the potential model. In this paper, we extend this generalization for high temperatures and include both the thermal and intermediate regimes. This is achieved by applying the general method developed by Jensen to the quadratic barrier model of our previous publication. We obtain results that are in good agreement with fully numerical calculations for radii R > 4 nm, while our calculated current density differs by a factor up to 27 from the one predicted by the Jensen's standard General-Thermal-Field (GTF) equation. Our extended GTF equation has application to modern sharp electron sources, beam simulation models, and vacuum breakdown theory

  14. International workshop on emittance preservation in linear colliders

    International Nuclear Information System (INIS)

    The extremely low emittances, which are the essential feature for any linear collider, are far beyond those of the present high-energy accelerators. Every part of the linear-collider accelerator complex is liable to blow up them to a fatal degree. Above all, the main linac is the most critical part, since it will have an unprecedented length, through which very highly populated bunches should be accelerated without a faint increase of emittances. A lot of efforts have been paid, mainly theoretically, to settle this problem at all institutes. Any convincing conclusions are not yet reached. Furthermore, there are six approaches of substantially different schemes (Tesla, DLC, JLC, NLC, VLEPP, CLIC), each requiring its own way to tackle the problem. In this workshop, many up-to-date R and D results were presented by each institute. Judging from what were discussed, we may well say that the R and D work has advanced to such a level that the different approaches are rather helping each other to reach more concrete results. (J.P.N.)

  15. Emissivity Tuned Emitter for RTPV Power Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carl M. Stoots; Robert C. O' Brien; Troy M. Howe

    2012-03-01

    Every mission launched by NASA to the outer planets has produced unexpected results. The Voyager I and II, Galileo, and Cassini missions produced images and collected scientific data that totally revolutionized our understanding of the solar system and the formation of the planetary systems. These missions were enabled by the use of nuclear power. Because of the distances from the Sun, electrical power was produced using the radioactive decay of a plutonium isotope. Radioisotopic Thermoelectric Generators (RTGs) used in the past and currently used Multi-Mission RTGs (MMRTGs) provide power for space missions. Unfortunately, RTGs rely on thermocouples to convert heat to electricity and are inherently inefficient ({approx} 3-7% thermal to electric efficiency). A Radioisotope Thermal Photovoltaic (RTPV) power source has the potential to reduce the specific mass of the onboard power supply by increasing the efficiency of thermal to electric conversion. In an RTPV, a radioisotope heats an emitter, which emits light to a photovoltaic (PV) cell, which converts the light into electricity. Developing an emitter tuned to the desired wavelength of the photovoltaic is a key part in increasing overall performance. Researchers at the NASA Glenn Research Center (GRC) have built a Thermal Photovoltaic (TPV) system, that utilizes a simulated General Purpose Heat Source (GPHS) from a MMRTG to heat a tantalum emitter. The GPHS is a block of graphite roughly 10 cm by 10 cm by 5 cm. A fully loaded GPHS produces 250 w of thermal power and weighs 1.6 kgs. The GRC system relies on the GPHS unit radiating at 1200 K to a tantalum emitter that, in turn, radiates light to a GaInAs photo-voltaic cell. The GRC claims system efficiency of conversion of 15%. The specific mass is around 167 kg/kWe. A RTPV power source that utilized a ceramic or ceramic-metal (cermet) matrix would allow for the combination of the heat source, canister, and emitter into one compact unit, and allow variation in size

  16. Optimization of oxidation processes to improve crystalline silicon solar cell emitters

    Directory of Open Access Journals (Sweden)

    L. Shen

    2014-02-01

    Full Text Available Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 Ω/□ performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 Ω/□ that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 1020 cm−3 and 7.78 × 1020 cm−3 and with junction depths between 0.46 μm and 0.55 μm possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%abs compared to conventional emitters with 50 Ω/□ sheet resistance.

  17. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core.

    Science.gov (United States)

    Thomas, Jens; Ma, Chung-Pei; McConnell, Nicholas J; Greene, Jenny E; Blakeslee, John P; Janish, Ryan

    2016-04-21

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day 'dormant' descendants of this population of 'active' black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall--the largest local structure of galaxies. The most luminous quasars, however, are not confined to such high-density regions of the early Universe; yet dormant black holes of this high mass have not yet been found outside of modern-day rich clusters. Here we report observations of the stellar velocity distribution in the galaxy NGC 1600--a relatively isolated elliptical galaxy near the centre of a galaxy group at a distance of 64 megaparsecs from Earth. We use orbit superposition models to determine that the black hole at the centre of NGC 1600 has a mass of 17 billion solar masses. The spatial distribution of stars near the centre of NGC 1600 is rather diffuse. We find that the region of depleted stellar density in the cores of massive elliptical galaxies extends over the same radius as the gravitational sphere of influence of the central black holes, and interpret this as the dynamical imprint of the black holes. PMID:27049949

  18. Investigating a Hypothetical Semiconductor Laser Bar with a Damaged Single Emitter Using a Laser Diode Simulation/Emulation Tool

    Directory of Open Access Journals (Sweden)

    C.K. Amuzuvi

    2014-02-01

    Full Text Available This study demonstrates the use of Barlase, a semiconductor laser diode emulation tool, to emulate the by-emitter degradation of high power semiconductor laser diodes.Barlase is software that uses a LabView control interface. In this study, a hypothetical laser diode bar (multiple emitters was used to investigate a damaged single emitter randomly located in the bar and its behavior analyzed within the bar. It should however, be noted that, this scenario is valid for devices at the start of the aging process only. When all other relevant effects that affect the performance of laser diodes bars are allowed to interact over time, high levels of defects can also play important role in the degradation process. The results of this simulation scenario show the successful implementation of Barlase in the by-emitter analysis of laser diodes.

  19. Effect of low frequency noise on the evolution of the emittance and halo population

    CERN Document Server

    Fitterer, Miriam; Antoniou, Fanouria; Bravin, Enrico; Bruce, Roderik; Fartoukh, Stephane; Fuchsberger, Kajetan; Hofle, Wolfgang; Gasior, Marek; Jaussi, Michael; Jacquet, Delphine; Kotzian, Gerd; Olexa, Jakub; Papadopoulou, Parthena Stefania; Papotti, Giulia; Papaphilippou, Yannis; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Stancari, Giulio; Trad, Georges; Valuch, Daniel; Valentino, Gianluca; Wagner, Joschka; Wenninger, Jorg; CERN. Geneva. ATS Department

    2016-01-01

    For the High Luminosity upgrade the β* in IR1 and IR5 will be further reduced compared to the current LHC. As the β* decreases the β-functions in the inner triplet (IT) increase resulting in a higher sensitivity of the HL-LHC to ground motion in the IT region or to increases of the low frequency noise. Noise can in general lead to emittance growth and higher halo population and diffusion rate. However, it is usually assumed in the literature that only frequencies close to the betatron frequencies and sidebands have an effect on the emittance and tail population. To test this theory, an MD was carried out to observe if also low frequency noise can lead to emittance growth and stronger halo population and diffusion.

  20. Emittance measurement of a DC gun for Smith-Purcell Backward Wave Oscillator FEL

    International Nuclear Information System (INIS)

    A Terahertz light source using Smith-Purcell Backward Wave Oscillator FEL(S-P BWO-FEL) has been studied at Laboratory of Nuclear Science, Tohoku University. The DC gun employs a high voltage of 50 kV to extract electrons, which is suitable to drive S-P BWO-FEL. A numerical simulation using a 3-D finite deference time domain (FDTD) method implies the S-P BWO-FEL oscillation at the terahertz wavelength region. Emittance measurement has been performed by means of the double slit method. The deduced normalized rms emittance is about 2πmm mrad. We will present the result of emittance measurement and analysis results. (author)

  1. Microelectrode for energy and current control of nanotip field electron emitters

    International Nuclear Information System (INIS)

    Emerging experiments and applications in electron microscopy, holography, and diffraction benefit from miniaturized electron guns for compact experimental setups. We present a highly compact microelectrode integrated field emitter that consists of a tungsten nanotip coated with a few micrometers thick polyimide film followed by a several nanometers thick gold film, both positioned behind the exposed emitter apex by approximately 10–30 μm. The control of the electric field strength at the nanometer scale tip apex allows suppression, extraction, and energy tuning of field-emitted electrons. The performance of the microelectrode is demonstrated experimentally and supported by numerical simulations

  2. Non-linear excitation of quantum emitters in two-dimensional hexagonal boron nitride

    CERN Document Server

    Schell, Andreas W; Takashima, Hideaki; Takeuchi, Shigeki; Aharonovich, Igor

    2016-01-01

    Two-photon absorption is an important non-linear process employed for high resolution bio-imaging and non-linear optics. In this work we realize two-photon excitation of a quantum emitter embedded in a two-dimensional material. We examine defects in hexagonal boron nitride and show that the emitters exhibit similar spectral and quantum properties under one-photon and two-photon excitation. Furthermore, our findings are important to deploy two-dimensional hexagonal boron nitride for quantum non-linear photonic applications.

  3. Computer simulation of the emittance growth due to noise in large hadron colliders

    International Nuclear Information System (INIS)

    The problem of emittance growth due to random fluctuations of the magnetic field in a hadron collider is considered. The results of computer simulations are compared with the analytical theory developed earlier. A good agreement was found between the analytical theory predictions and the computer simulations for the collider tunes located far enough from high order betatron resonances. The dependencies of the emittance growth rate on noise spectral density, beam separation at the Interaction Point (IP) and value of beam separation at long range collisions are studied. The results are applicable to the Superconducting Super Collider (SSC)

  4. Estimation of emittance degradation due to multi-pole fields of XFEL bunch compressors

    International Nuclear Information System (INIS)

    In order to obtain a high-brightness electron beam in an XFEL, the electron bunch should be longitudinally compressed in a linear accelerator using magnetic bunch compressors composed of four bending magnets. The bunch compression requires a large energy chirp on the electron bunch, which produces a horizontal spread of the beam size inside bunch compressors. Since the bending magnets have multi-pole field components, they leak energy-dispersion and degrade emittance downstream of the chicane. In this paper, the emittance degradation due to the multi-pole fields of the bending magnets is estimated using simplified analytical formulae for the XFEL/SPring-8. (author)

  5. Unlocking the Euro 53 billion savings from smart meters in the EU: How increasing the adoption of dynamic tariffs could make or break the EU's smart grid investment

    International Nuclear Information System (INIS)

    We estimate the cost of installing smart meters in the EU to be Euro 51 billion, and that operational savings will be worth between Euro 26 and 41 billion, leaving a gap of Euro 10-25 billion between benefits and costs. Smart meters can fill this gap because they enable the provision of dynamic pricing, which reduces peak demand and lowers the need for building and running expensive peaking power plants. The present value of savings in peaking infrastructure could be as high as Euro 67 billion for the EU if policy-makers can overcome barriers to consumers adopting dynamic tariffs, but only Euro 14 billion otherwise. We outline a number of ways to increase the adoption of dynamic tariffs.

  6. Unlocking the EUR53 billion savings from smart meters in the EU. How increasing the adoption of dynamic tariffs could make or break the EU's smart grid investment

    International Nuclear Information System (INIS)

    We estimate the cost of installing smart meters in the EU to be EUR51 billion, and that operational savings will be worth between EUR26 and 41 billion, leaving a gap of EUR10-25 billion between benefits and costs. Smart meters can fill this gap because they enable the provision of dynamic pricing, which reduces peak demand and lowers the need for building and running expensive peaking power plants. The present value of savings in peaking infrastructure could be as high as EUR67 billion for the EU if policy-makers can overcome barriers to consumers adopting dynamic tariffs, but only EUR14 billion otherwise. We outline a number of ways to increase the adoption of dynamic tariffs. (author)

  7. Final Muon Emittance Exchange in Vacuum for a Collider

    Energy Technology Data Exchange (ETDEWEB)

    Summers, Don [Univ. of Mississippi, Oxford, MS (United States); Acosta, John [Univ. of Mississippi, Oxford, MS (United States); Cremaldi, Lucien [Univ. of Mississippi, Oxford, MS (United States); Hart, Terry [Univ. of Mississippi, Oxford, MS (United States); Oliveros, Sandra [Univ. of Mississippi, Oxford, MS (United States); Perera, Lalith [Univ. of Mississippi, Oxford, MS (United States); Wu, Wanwei [Univ. of Mississippi, Oxford, MS (United States); Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-05-07

    We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low β region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 μs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.

  8. Field Emitter Arrays for a Free Electron Laser Application

    CERN Document Server

    Shing-Bruce-Li, Kevin; Ganter, Romain; Gobrecht, Jens; Raguin, Jean Yves; Rivkin, Leonid; Wrulich, Albin F

    2004-01-01

    The development of a new electron gun with the lowest possible emittance would help reducing the total length and cost of a free electron laser. Field emitter arrays (FEAs) are an attractive technology for electron sources of ultra high brightness. Indeed, several thousands of microscopic tips can be deposited on a 1 mm diameter area. Electrons are then extracted by applying voltage to a first grid layer close to the tip apexes, the so called gate layer, and focused by a second grid layer one micrometer above the tips. The typical aperture diameter of the gate and the focusing layer is in the range of one micrometer. One challenge for such cathodes is to produce peak currents in the ampere range since the usual applications of FEAs require less than milliampere. Encouraging peak current performances have been obtained by applying voltage pulses at low frequency between gate and tips. In this paper we report on different tip materials available on the market: diamond FEAs from Extreme Devices Inc., ZrC single ...

  9. Emittance Measurements from a Laser Driven Electron Injector

    CERN Document Server

    Reis, D

    2003-01-01

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 (angstrom), the LCLS requires an electron injector that can produce an electron beam with approximately 1 pi mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the ...

  10. Infrared spectral normal emittance/emissivity comparison

    Science.gov (United States)

    Hanssen, L.; Wilthan, B.; Filtz, J.-R.; Hameury, J.; Girard, F.; Battuello, M.; Ishii, J.; Hollandt, J.; Monte, C.

    2016-01-01

    The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes' infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide. The comparison has been performed over a spectral range of 2 μm to 14 μm, and a temperature range from 23 °C to 800 °C. Artefacts included in the comparison are potential standards: oxidized Inconel, boron nitride, and silicon carbide. The measurement instrumentation and techniques used for emittance scales are unique for each NMI, including the temperature ranges covered as well as the artefact sizes required. For example, all three common types of spectral instruments are represented: dispersive grating monochromator, Fourier transform and filter-based spectrometers. More than 2000 data points (combinations of material, wavelength and temperature) were compared. Ninety-eight percent (98%) of the data points were in agreement, with differences to weighted mean values less than the expanded uncertainties calculated from the individual NMI uncertainties and uncertainties related to the comparison process. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Conservation of protein structure over four billion years.

    Science.gov (United States)

    Ingles-Prieto, Alvaro; Ibarra-Molero, Beatriz; Delgado-Delgado, Asuncion; Perez-Jimenez, Raul; Fernandez, Julio M; Gaucher, Eric A; Sanchez-Ruiz, Jose M; Gavira, Jose A

    2013-09-01

    Little is known about the evolution of protein structures and the degree of protein structure conservation over planetary time scales. Here, we report the X-ray crystal structures of seven laboratory resurrections of Precambrian thioredoxins dating up to approximately four billion years ago. Despite considerable sequence differences compared with extant enzymes, the ancestral proteins display the canonical thioredoxin fold, whereas only small structural changes have occurred over four billion years. This remarkable degree of structure conservation since a time near the last common ancestor of life supports a punctuated-equilibrium model of structure evolution in which the generation of new folds occurs over comparatively short periods and is followed by long periods of structural stasis. PMID:23932589

  12. Emittance growth from transient coherent synchrotron radiation

    International Nuclear Information System (INIS)

    If the energies of individual particles in a bunch change as the bunch traverses a bending system, even if it is achromatic, betatron oscillations can be excited. Consequently, the transverse emittance of the bunch will grow as it moves downstream. Short bunches may be particularly susceptible to emission of coherent synchrotron radiation which can act back on the particles to change their energies and trajectories. Because a bend spans a well-defined length and angle, the bunch-excited wakefield and its effect back on the bunch are inherently transient. We outline a recently developed theory of this effect and apply it to example bending systems

  13. Summary report on transverse emittance preservation

    International Nuclear Information System (INIS)

    During the past years, significant progress has been made in understanding the beam transverse emittance blow-up and its preservation. However, one often finds him-/herself ignorant when he/she tries to explain what was observed in an existing machine or to predict what will happen in a machine under design. There are a number of such examples given in this report. Some of them are even fundamental. These are the challenges. But they are also the directions leading to new achievements. The workshop gladly acknowledged them and promised to work on them

  14. Experimental studies on coherent synchrotron radiaiton in the emittance exchange line at the Fermilab A0 Photoinjector

    International Nuclear Information System (INIS)

    Future accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. Coherent synchrotron radiation (CSR) in the dipoles could limit the performance of the emittance exchanger. In this paper, we report the experimental studies on measuring CSR and its effects on the beam at the A0 photoinjector in the emittance exchange line. After reporting the CSR power measurements, we report on the diagnostic scheme based on a weak skew quad in the emittance exchange line to study the CSR effects on the beam and other beam dynamics. In this work, we have reported on CSR measurements and the effect of skew quad on the dogleg line with the 5-cell turned on and off. We plan to study CSR effects on the bunch with the 5-cell on at larger chirp. This is will not only increase the CSR self-effect but also reduce the beamsize at the screen for convenient beamsize measurements.

  15. Measurement of the tradeoff between intrinsic emittance and quantum efficiency from a NaKSb photocathode near threshold

    International Nuclear Information System (INIS)

    We measure the tradeoff between the quantum efficiency and intrinsic emittance from a NaKSb photocathode at three increasing wavelengths (635, 650, and 690 nm) at or below the energy of the bandgap plus the electron affinity, hν≤Eg+Ea. These measurements were performed using a high voltage dc gun for varied photocathode surface fields of 1.4−4.4 MV/m. Measurements of intrinsic emittance are performed using two different methods and were found to agree. At the longest wavelength available, 690 nm, the intrinsic emittance was 0.26 μm/mm-rms with a quantum efficiency of ∼10−4. The suitability of NaKSb emitting at threshold for various low emittance applications is discussed

  16. Measurement of the tradeoff between intrinsic emittance and quantum efficiency from a NaKSb photocathode near threshold

    Energy Technology Data Exchange (ETDEWEB)

    Maxson, Jared, E-mail: jmm586@cornell.edu; Cultrera, Luca; Gulliford, Colwyn; Bazarov, Ivan [Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853 (United States)

    2015-06-08

    We measure the tradeoff between the quantum efficiency and intrinsic emittance from a NaKSb photocathode at three increasing wavelengths (635, 650, and 690 nm) at or below the energy of the bandgap plus the electron affinity, hν≤E{sub g}+E{sub a}. These measurements were performed using a high voltage dc gun for varied photocathode surface fields of 1.4−4.4 MV/m. Measurements of intrinsic emittance are performed using two different methods and were found to agree. At the longest wavelength available, 690 nm, the intrinsic emittance was 0.26 μm/mm-rms with a quantum efficiency of ∼10{sup −4}. The suitability of NaKSb emitting at threshold for various low emittance applications is discussed.

  17. Conservation of protein structure over four billion years

    OpenAIRE

    Ingles-Prieto, Alvaro; Ibarra-Molero, Beatriz; Delgado-Delgado, Asuncion; Perez-Jimenez, Raul; Fernandez, Julio M.; Gaucher, Eric A.; Sanchez-Ruiz, Jose M.; Gavira, Jose A.

    2013-01-01

    Little is known with certainty about the evolution of protein structures in general and the degree of protein structure conservation over planetary time scales in particular. Here we report the X-ray crystal structures of seven laboratory resurrections of Precambrian thioredoxins dating back up to ~4 billion years before present. Despite considerable sequence differences compared with extant enzymes, the ancestral proteins display the canonical thioredoxin fold while only small structural cha...

  18. Cost of solving mysteries of universe: $6.7 billion

    CERN Multimedia

    Overbye, Dennis

    2007-01-01

    "An international consortium of physicists on Thursday released the first detailed design of what they believe will be the next big thing in physics. The machine, 20 miles long, will slam together electrons and their opposites, positrons, to produce fireballs of energy re-creating conditions when the universe was only a trillionth of a second old. It would cost about $6.7 billion." (1 page)

  19. Ubiquitous Supercritical Wing Design Cuts Billions in Fuel Costs

    Science.gov (United States)

    2015-01-01

    A Langley Research Center engineer’s work in the 1960s and ’70s to develop a wing with better performance near the speed of sound resulted in a significant increase in subsonic efficiency. The design was shared with industry. Today, Renton, Washington-based Boeing Commercial Airplanes, as well as most other plane manufacturers, apply it to all their aircraft, saving the airline industry billions of dollars in fuel every year.

  20. Tolerances for the vertical emittance in damping rings

    International Nuclear Information System (INIS)

    Future damping rings for linear colliders will need to have very small vertical emittances. In the limit of low beam current, the vertical emittance is primarily determined by the vertical dispersion and the betatron coupling. In this paper, the contributions to these effects from random misalignments are calculated and tolerances are derived to limit the vertical emittance with a 95% confidence level. 10 refs., 5 figs

  1. Silicon heterojunction solar cells: Optimization of emitter and contact properties from analytical calculation and numerical simulation

    International Nuclear Information System (INIS)

    Highlights: ► We relate the open circuit voltage and the band-bending in crystalline silicon. ► We calculate the band-bending in the crystalline part of a silicon heterojunction. ► The band-bending is strongly influenced by the work function and density of states. ► A high defect density in the amorphous silicon emitter increases the band bending. ► A high defect density reduces the impact of the contact on the open circuit voltage. -- Abstract: The key constituent of silicon heterojunction solar cells, the amorphous silicon/crystalline silicon heterojunction (a-Si:H/c-Si), offers a high open-circuit voltage (Voc) potential providing that both the interface defect passivation and the band bending in the c-Si absorber are sufficient. We detail here analytical calculations of the equilibrium band bending in c-Si (ψc-Si) in Transparent Conductive Oxide (TCO)/a-Si:H emitter/c-Si absorber structures. We studied the variation of some electronic parameters (density of states, work function) according to relevant experimental values. This study introduces a discussion on the optimization of the doped emitter layer in relation with the work function of the TCO. In particular, we argue on the advantage of having a highly defective (p)a-Si:H emitter layer that maximizes ψc-Si and reduces the influence of the TCO on Voc

  2. Variable Emittance Electrochromics Using Ionic Electrolytes and Low Solar Absorptance Coatings

    Science.gov (United States)

    Chandrasekhar, Prasanna

    2011-01-01

    One of the last remaining technical hurdles with variable emittance devices or skins based on conducting polymer electrochromics is the high solar absorptance of their top surfaces. This high solar absorptance causes overheating of the skin when facing the Sun in space. Existing technologies such as mechanical louvers or loop heat pipes are virtually inapplicable to micro (coatings lower the solar absorption to Alpha(s) of between 0.30 and 0.46. Coupled with the emittance properties of the variable emittance skins, this lowers the surface temperature of the skins facing the Sun to between 30 and 60 C, which is much lower than previous results of 100 C, and is well within acceptable satellite operations ranges. The performance of this technology is better than that of current new technologies such as microelectromechanical systems (MEMS), electrostatics, and electrophoretics, especially in applications involving micro and nano spacecraft. The coatings are deposited inside a high vacuum, layering multiple coatings onto the top surfaces of variable emittance skins. They are completely transparent in the entire relevant infrared region (about 2 to 45 microns), but highly reflective in the visible-NIR (near infrared) region of relevance to solar absorptance.

  3. Low emittance electron beam optics commissioning in Indus-2

    International Nuclear Information System (INIS)

    Currently Indus-2 is normally operated with beam emittance of 85 nmrad at 2.0 GeV. In order to reduce the beam emittance to half of this value its dispersion function has been modified by properly choosing the quadrupoles strengths of the lattice. At this low beam emittance optics dynamic aperture reduces and may not be sufficient for beam injection thus a procedure has been evolved and implemented to shift the beam emittance of stored beam at 2.0 GeV. (author)

  4. Numerical simulation of low emittance tuning at SuperKEKB

    International Nuclear Information System (INIS)

    SuperKEKB is a double ring e+e- collider aimed to reach new luminosity frontier. The target peak luminosity is 8x103 cm-2s-1, which is 40 times higher than the world recored achieved by the KEKB machine. The basic strategy to break the KEKB's record is 2 times higher beam current and 20 times smaller beam size at the interaction point. In order to obtain the required beam size, we have to stably storage high quality beams and squeez the beta function. Therefore, one of important accelerator topic in the project is the Low Emittance Tuning (LET) as in high brightness light source projects. We have conducted LET study, shush as error sensitivity, alignment strategy and beam optics correction by using numerical approach. Some remarkable simulation results obtained so far are reported. (author)

  5. Thermal emittance measurements on candidate refractory materials for application in nuclear space power systems

    International Nuclear Information System (INIS)

    The development of a highly efficient General Purpose Heat Source (GPHS) space power system requires that all of the available thermal energy from the GPHS modules be utilized in the most thermally efficient manner. This includes defining the heat transfer/thermal gradient profile between the surface of the GPHS's and the surface of the energy converter's hot end whose geometry is dependent on the converter technology selected. Control of the radiant heat transfer between these two surfaces is done by regulating how efficiently the selected converter's hot end surface can reject heat compared to a perfect blackbody, i.e. its infrared emittance. Several refractory materials of interest including niobium-1% zirconium, molybdenum-44.5% rhenium and L-605 (a cobalt-based alloy) were subjected to various surface treatments (grit blasting with either SiC or WC particulates) and heat treatments (up to 1198 K for up to 3000 hours). Room temperature infrared emittance values were then obtained using two different infrared reflectometers. Grit blasting with either SiC or WC tended to increase the emittance of flat or curved L-605 coupons by ∼0.2-0.3 independent of heat treatment. Heat treating L-605 coupons under 773 K for up to 2000 hours had only a slight effect on their emittance, while heat treating L-605 coupons at 973 K for over 150 hours appeared to significantly increase their emittance. For the temperatures and times studied here, the emittance values obtained on niobium-1% zirconium and molybdenum-44.5% rhenium coupons were independent of heat treat times and temperatures (except for the niobium-1% zirconium coupon that was heat treated at 1198 K for 150 hours)

  6. Anthropogenic Methane Emissions in California's San Joaquin Valley: Characterizing Large Point Source Emitters

    Science.gov (United States)

    Hopkins, F. M.; Duren, R. M.; Miller, C. E.; Aubrey, A. D.; Falk, M.; Holland, L.; Hook, S. J.; Hulley, G. C.; Johnson, W. R.; Kuai, L.; Kuwayama, T.; Lin, J. C.; Thorpe, A. K.; Worden, J. R.; Lauvaux, T.; Jeong, S.; Fischer, M. L.

    2015-12-01

    Methane is an important atmospheric pollutant that contributes to global warming and tropospheric ozone production. Methane mitigation could reduce near term climate change and improve air quality, but is hindered by a lack of knowledge of anthropogenic methane sources. Recent work has shown that methane emissions are not evenly distributed in space, or across emission sources, suggesting that a large fraction of anthropogenic methane comes from a few "super-emitters." We studied the distribution of super-emitters in California's southern San Joaquin Valley, where elevated levels of atmospheric CH4 have also been observed from space. Here, we define super-emitters as methane plumes that could be reliably detected (i.e., plume observed more than once in the same location) under varying wind conditions by airborne thermal infrared remote sensing. The detection limit for this technique was determined to be 4.5 kg CH4 h-1 by a controlled release experiment, corresponding to column methane enhancement at the point of emissions greater than 20% above local background levels. We surveyed a major oil production field, and an area with a high concentration of large dairies using a variety of airborne and ground-based measurements. Repeated airborne surveys (n=4) with the Hyperspectral Thermal Emission Spectrometer revealed 28 persistent methane plumes emanating from oil field infrastructure, including tanks, wells, and processing facilities. The likelihood that a given source type was a super-emitter varied from roughly 1/3 for processing facilities to 1/3000 for oil wells. 11 persistent plumes were detected in the dairy area, and all were associated with wet manure management. The majority (11/14) of manure lagoons in the study area were super-emitters. Comparing to a California methane emissions inventory for the surveyed areas, we estimate that super-emitters comprise a minimum of 9% of inventoried dairy emissions, and 13% of inventoried oil emissions in this region.

  7. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  8. Barium depletion in hollow cathode emitters

    International Nuclear Information System (INIS)

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values

  9. Muon Emittance Exchange with a Potato Slicer

    CERN Document Server

    Summers, D J; Acosta, J G; Cremaldi, L M; Oliveros, S J; Perera, L P; Neuffer, D V

    2015-01-01

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long ...

  10. Minimizing Emittance for the CLIC Damping Ring

    CERN Document Server

    Braun, H; Levitchev, E; Piminov, P; Schulte, Daniel; Siniatkin, S; Vobly, P P; Zimmermann, Frank; Zolotarev, Konstantin V; CERN. Geneva

    2006-01-01

    The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6·109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology the other on permanent magnets are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. For optimized wigglers, only bunches for a single machine pulse may need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 36...

  11. Barium depletion in hollow cathode emitters

    Energy Technology Data Exchange (ETDEWEB)

    Polk, James E., E-mail: james.e.polk@jpl.nasa.gov; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Capece, Angela M. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  12. Barium depletion in hollow cathode emitters

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Capece, Angela M.; Katz, Ira

    2016-01-01

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  13. Emittance measurement and optimization for the photocathode RF gun with laser profile shaping

    International Nuclear Information System (INIS)

    The Laser Undulator Compact X-ray source (LUCX) is a test bench for a compact high brightness X-ray generator, based on inverse Compton Scattering at KEK, which requires high intensity multi-bunch trains with low transverse emittance. A photocathode RF gun with emittance compensation solenoid is used as an electron source. Much endeavor has been made to increase the beam intensity in the multi-bunch trains. The cavity of the RF gun is tuned into an unbalanced field in order to reduce space charge effects, so that the field gradient on the cathode surface is relatively higher when the forward RF power into gun cavity is not high enough. A laser profile shaper is employed to convert the driving laser profile from Gaussian into uniform. In this research we seek to find the optimized operational conditions for the decrease of the transverse emittance. With the uniform driving laser and the unbalanced RF gun, the RMS transverse emittance of a 1 nC bunch has been improved effectively from 5.46 πmm.mrad to 3.66 πmm·mrad. (authors)

  14. Evidence for Mature Bulges and an Inside-out Quenching Phase 3 Billion Years After the Big Bang

    CERN Document Server

    Tacchella, S; Renzini, A; Schreiber, N M Förster; Lang, P; Wuyts, S; Cresci, G; Dekel, A; Genzel, R; Lilly, S J; Mancini, C; Newman, S; Onodera, M; Shapley, A; Tacconi, L; Woo, J; Zamorani, G

    2015-01-01

    Most present-day galaxies with stellar masses $\\geq10^{11}$ solar masses show no ongoing star formation and are dense spheroids. Ten billion years ago, similarly massive galaxies were typically forming stars at rates of hundreds solar masses per year. It is debated how star formation ceased, on which timescales, and how this "quenching" relates to the emergence of dense spheroids. We measured stellar mass and star-formation rate surface density distributions in star-forming galaxies at redshift 2.2 with $\\sim1$ kiloparsec resolution. We find that, in the most massive galaxies, star formation is quenched from the inside out, on timescales less than 1 billion years in the inner regions, up to a few billion years in the outer disks. These galaxies sustain high star-formation activity at large radii, while hosting fully grown and already quenched bulges in their cores.

  15. Galaxy evolution. Evidence for mature bulges and an inside-out quenching phase 3 billion years after the Big Bang.

    Science.gov (United States)

    Tacchella, S; Carollo, C M; Renzini, A; Förster Schreiber, N M; Lang, P; Wuyts, S; Cresci, G; Dekel, A; Genzel, R; Lilly, S J; Mancini, C; Newman, S; Onodera, M; Shapley, A; Tacconi, L; Woo, J; Zamorani, G

    2015-04-17

    Most present-day galaxies with stellar masses ≥10(11) solar masses show no ongoing star formation and are dense spheroids. Ten billion years ago, similarly massive galaxies were typically forming stars at rates of hundreds solar masses per year. It is debated how star formation ceased, on which time scales, and how this "quenching" relates to the emergence of dense spheroids. We measured stellar mass and star-formation rate surface density distributions in star-forming galaxies at redshift 2.2 with ~1-kiloparsec resolution. We find that, in the most massive galaxies, star formation is quenched from the inside out, on time scales less than 1 billion years in the inner regions, up to a few billion years in the outer disks. These galaxies sustain high star-formation activity at large radii, while hosting fully grown and already quenched bulges in their cores. PMID:25883353

  16. The anodic emitter effect and its inversion demonstrated by temperature measurements at doped and undoped tungsten electrodes

    Science.gov (United States)

    Hoebing, T.; Bergner, A.; Hermanns, P.; Mentel, J.; Awakowicz, P.

    2016-04-01

    The admixture of a small amount of emitter oxides, e.g. \\text{Th}{{\\text{O}}2} , \\text{L}{{\\text{a}}2}{{\\text{O}}3} or \\text{C}{{\\text{e}}2}{{\\text{O}}3} to tungsten generates the so-called emitter effect. It reduces the work function of tungsten cathodes, that are applied in high intensity discharge (HID) lamps. After leaving the electrode bulk and moving to the surface, a monolayer of Th, La, or Ce atoms is formed on the surface, which reduces the effective work function ϕ. Depending on the coverage of the electrode, the effective reduction in ϕ is subjected to the thermal desorption of the monolayer from the hot electrode surface. The thermal desorption of emitter atoms from the cathode is compensated not only by the supply from the interior of the electrode and by surface diffusion of the emitter material to its tip, but also to a large extent by a repatriation of the emitter ions from the plasma by the strong electric field in front of the cathode. Yet, an emitter ion current from the arc discharge to the anode may only be present, if the anode is cold enough to refrain from thermionic emission. Therefore, the ability of emitter oxides to reduce the temperature of tungsten anodes is only given for a moderate temperature so that the thermal desorption is low and an additional ion current is present in front of the anode. A higher electrode temperature leads to their evaporation and to an inversion of the emitter effect, which increases the temperature of the respective anodes in comparison with pure tungsten anodes. Within this article, the emitter effect of doped tungsten anodes and the transition to its inversion is investigated for thoriated, lanthanated, and ceriated tungsten electrodes by measurements of the electrode temperature in dependence on the discharge current. It is shown for a lanthanated and a ceriated anode that the emitter effect is sustained by an ion current at anode temperatures at which the thermal evaporation of emitter material

  17. Electron Emission from Ultra-Large Area MOS Electron Emitters

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm;

    2009-01-01

    Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from the...... layer is varied from 3 to 10 Å which changes the emission efficiency by more than one order of magnitude. The apparent mean free path of ~5 eV electrons in Au is found to be 52 Å. Deposition of Cs on the Au film increased the electron emission efficiency to 4.3% at 4 V by lowering the work function....... Electron emission under high pressures (up to 2 bars) of Ar was observed. ©2009 American Vacuum Society...

  18. Jamming of Quantum Emitters by Active Coated Nanoparticles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2013-01-01

    effectively cloak the emitters to a far-field observer is reported and explained through thorough near- and far-field investigations. This property offers an interesting route toward the jamming of quantum emitters/nanoantennas that might be of potential use, for instance, in biological fluorescence assays...

  19. Emittance formula for slits and pepper-pot measurement

    International Nuclear Information System (INIS)

    In this note, a rigid formula for slits and pepper-pot emittance measurement is derived. The derivation is based on the one- dimensional slit measurement setup. A mathematical generalization of the slit emittance formula to the pepper-pot measurement is discussed

  20. Thermionic scanner pinpoints work function of emitter surfaces

    Science.gov (United States)

    Rasor, N. S.

    1966-01-01

    In the electron tube testing, a thermionic scanner makes accurate spatial resolution measurements of the metallic surface work functions of emitters. The scanner determines the emitter function and its local departures from the mean value on a point-by-point basis for display on an oscilloscope.

  1. Emittance measurements of low-energy beam line at KVI

    NARCIS (Netherlands)

    Toprek, D; Formanoy, [No Value

    2006-01-01

    In this paper is represented the results of beam profile measurements of He-3(+) beam delivered from ECR ion source at KVI. The beam emittance is estimated by varying quadrupole method. The estimated values for the beam emittance at the different profile grid locations along the transport beam line

  2. Emittance growth due to dipole ripple and sextupole

    International Nuclear Information System (INIS)

    Ripple in the power supplies for storage ring magnets can have adverse effects on the circulating beams: orbit distortion and emittance growth from dipole ripple, tune modulation and dynamic aperture reduction from quadrupole ripple, etc. In this paper, we study the effects of ripple in the horizontal bending field of the SSC in the presence of nonlinearity, in particular, the growth in beam emittance

  3. Emittance growth due to dipole ripple and sextupole

    Energy Technology Data Exchange (ETDEWEB)

    Shih, H.J.; Ellison, J.A.; Syphers, M.J.; Newberger, B.S.

    1993-05-01

    Ripple in the power supplies for storage ring magnets can have adverse effects on the circulating beams: orbit distortion and emittance growth from dipole ripple, tune modulation and dynamic aperture reduction from quadrupole ripple, etc. In this paper, we study the effects of ripple in the horizontal bending field of the SSC in the presence of nonlinearity, in particular, the growth in beam emittance.

  4. Coated nano-particle jamming of quantum emitters

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2012-01-01

    Spherical active coated nano-particles are examined analytically and numerically in the presence of one, two or four quantum emitters (electric Hertzian dipoles). The ability of the coated nano-particle to effectively cloak the emitters to a far-field observer is reported. This offers an...

  5. TOU' rates hold out $13-billion prize

    Energy Technology Data Exchange (ETDEWEB)

    Slaboszewicz, C.

    1994-03-15

    By 2000, U.S. electric utilities will add 90,000 MW of generating capacity to meet peaking needs. Rather than spend $45 billion on these power plants, which will be used only a couple of hundred hours each year, electric utilities could use incentive pricing-residential time-of-use (TOU) rates-to save consumers up to $13 billion. The combination of market forces and new technology to support automatic meter reading and other applications makes these savings not only possible but practical. Unlike prices at other capacity-constrained industries such as airlines or telephone companies, electric utility prices usually do not vary by time of day. The result is average capacity factors of 43.8 percent (based on 1989 data), compared to a U.S. airlines average of 63.2 percent. Significantly, the airline average use to be below 50 percent in 1970, when they, like electric utilities, were closely regulated. Through incentive pricing, airlines were able to achieve almost a 30-percent increase in efficiency. According to studies by the Electric Power Research Institute (EPRI) and Edison Electric Institute (EEI), TOU pricing could increase the efficiency of U.S. power plant use by nearly 15 percent. Power plant needs for the next seven years offer an excellent opportunity to use TOU pricing to save consumers billions of dollars. According to Burns McDonnell, an engineering firm, new electric generation resources will not be needed before the turn of the century to prevent to projected deficit of peaking capacity. Indeed, Burns McDonnell estimates a current excess of 152,000 MW in nation-wide baseload capacity. TOU pricing, according to EPRI and EEI, causes residential consumers to reduce their onpeak electricity consumption by 20 percent. With a residential peak load of 183,000 MW, this reduction translates into over 36,000 MW of capacity.

  6. Billion particle linac simulations for future light sources

    International Nuclear Information System (INIS)

    In this paper we report on multi-physics, multi-billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of RF acceleration and focusing. We discuss the need for and the challenges associated with such large-scale simulation. Applications to the study of the microbunching instability in an FEL linac are also presented

  7. Developing economic environment: energy for a billion people

    International Nuclear Information System (INIS)

    The ongoing reforms in the Indian economy provide an interesting canvas for optimal development of the energy sector serving the needs for a billion people. It will be necessary in the global interest, to avoid the pitfalls of developing an energy intensive society as in the west and remain within the realms of sustainable development. It also deals with the strategies to be adopted for energy conservation, rehabilitation of existing plants and optimal utilisation of hydro thermal capacities by integrated grid operation on a commercial basis and setting up of pumped storage plants. 9 tabs

  8. Billion silicon-disc markets in solar cells

    International Nuclear Information System (INIS)

    The generation of solar power is estimated to increase ten times higher than it is at present. The nominal power is estimated to be 150 MW by the year 2010. The capacity of a solar cell (100 cm2; efficiency 15%) is 1.5W under good illumination conditions. So the growth estimate, given by the Swiss Saras Bank, requires the processing of over one billion silicon discs in ten years to pn-junction solar cells. The researches, carried out at Helsinki University of Technology and VTT Electronics are presented in the article

  9. Structural and magnetic effects on thermal emittance of La{sub 1−x}Sr{sub x}MnO{sub 3} from the first principles calculation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiang-Fei [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Tang, Fu-Ling, E-mail: tfl03@mails.tsinghua.edu.cn [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Xue, Hong-Tao; Lu, Wen-Jiang [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Feng, Yu-Dong [Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000 (China)

    2015-09-15

    Generalized gradient approximation (GGA) exchange-correlation functional was used in the first-principles method to calculate thermal emittance of La{sub 1−x}Sr{sub x}MnO{sub 3} (LSMO). The effects of structure and magnetism on thermal emittance of LSMO were systematically investigated by the complex dielectric function. It is found that the LSMO with orthorhombic structure has a higher thermal emittance than that with rhombohedral structure at the same temperature. When the magnetism varying with temperature of LSMO is put into consideration, the magnetic different make a significant change on thermal emittance and the variation of thermal emittance of La{sub 0.75}Sr{sub 0.25}MnO{sub 3} is the biggest among x=0, 0.2, 0.25, 0.5. It is found that thermal emittance have a low value at the low temperature and have a high value at the high temperature, due to the unique feature of variable thermal emittance based on metal-insulator transition, which makes LSMO attractive as potential thermal control materials. - Highlights: • The emittance of La{sub 1-x}Sr{sub x}MnO{sub 3} (LSMO) varies with different magnetism state. • Orthorhombic LSMO has larger emittance than rhombohedral LSMO at same temperature. • If the magnetism varying with temperature of LSMO is considered, the variation of emittance of La{sub 0.75}Sr{sub 0.25}MnO{sub 3} is the biggest among x=0, 0.2, 0.25 and 0.5.

  10. Emittance compensation of CW DC-gun photoinjector

    International Nuclear Information System (INIS)

    Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)

  11. Vacuum Rabi spectra of a single quantum emitter

    CERN Document Server

    Ota, Yasutomo; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2015-01-01

    We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

  12. Properties of nanolasers based on few discrete emitters

    DEFF Research Database (Denmark)

    Lund, Anders Mølbjerg; Nielsen, Per Kær; Lorke, Michael;

    2012-01-01

    The laser has evolved from table size apparatuses to truly nano sized devices, in much the same way that computer chips have been continuously minimized. The few-emitter nanolaser represents an extreme in terms of size. The emitters can be either atoms or quantum dots, and they are coupled to a......-level systems are pumped incoherently by a rate P. Solutions are found using the corresponding master equation. However, with cavity populations exceeding 100 and several emitters, the dimension of the Hilbert space of the system becomes too large to handle efficiently on a conventional computer. E.g. for four...... population of the cavity, na, and the occupation of the emitters. Fig. 1a) shows na for up to 4 emitters coupled to a cavity, as a function of the pumping rate P. The figure also shows results from a full master equation solution, and the correspondence is very good for large values of P. In Fig. 1b) the...

  13. Evaluations of carbon nanotube field emitters for electron microscopy

    International Nuclear Information System (INIS)

    Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I-V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6x109 A/m2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

  14. Gamma emitters in Hong Kong water

    International Nuclear Information System (INIS)

    Radioactivity in water originates from natural and artificial sources. The development of a nuclear powerplant near Hong Kong necessitates that attention be given to formulating techniques to assess the possible resultant environmental radioactive contamination. Water samples collected from various sites in Hong Kong in the spring and summer of 1987, representing seawater, river water, reservoir water, drinking water, and underground water were studied through gamma-ray spectral analysis. Only gamma emitters in the U238 and Th232 series and K40 were detected. No fission product was detected with specific activity above 0.1 Bq/kg. The data could be the baseline for future monitoring of the radioactivity released from a nuclear plant being built at a 50-km distance from Hong Kong. The variation of detected specific activities may be due to geological differences and the effect of plants. 1 ref., 3 tabs

  15. Mesoscopic quantum emitters coupled to plasmonic nanostructures

    DEFF Research Database (Denmark)

    Andersen, Mads Lykke

    -photon sources using self-assembled quantum dots. The measured decay dynamics of quantum dots in proximity to semiconductor/ metal interfaces reveal that the dipole approximation generally does not hold for quantum dots due to their mesoscopic size. In order to explain the observations, a theoretical model for...... the spontaneous emission of mesoscopic quantum emitters is developed. The light-matter interaction is in this model modied beyond the dipole expectancy and found to both suppress and enhance the coupling to plasmonic modes in excellent agreement with our measurements. We demonstrate that this...... mesoscopic effect can be utilized to strongly modify the coupling to plasmonic modes on metal nanowires and gap waveguides and we propose its use for spontaneous-emission control beyond the dipole approximation in nano-structured environments in general. The mesoscopic effect can be utilized to strongly...

  16. Preparation of an emittance transfer experiment

    CERN Document Server

    Xiao, C; Groening, L; Leibrock, H; Maier, M

    2012-01-01

    Flat beams feature unequal emittances in the horizontal and vertical phase space. Those beams were created successfully in lepton machines. Although a number of applications will profit also from flat hadron beams, to our knowledge they have never been created systematically. Multi-turn injection schemes, spectrometers, and colliders will directly benefit from those beams. The present paper covers the preparation of the experimental proof of principle for flat hadron beam creation in a beam transport section. Detailed simulations of the experiment, based on charge state stripping inside of a solenoid [L. Groening, Phys. Rev. ST Accel. Beams 14, 064201 (2011)], are performed. The matrix formalism was benchmarked with tracking through three-dimensional magnetic field maps of solenoids. An error analysis targeting at investigation of the impact of machine errors on the round-to-flat beam transformation has been performed. The remarkable flexibility of the set-up w.r.t. decoupling is addressed, as it can provide ...

  17. Emittance compensation for an SRF photo injector

    Energy Technology Data Exchange (ETDEWEB)

    Vennekate, H.; Lu, P. [HZDR (Germany); TU Dresden (Germany); Arnold, A.; Mucek, P.; Teichert, J.; Xiang, R. [HZDR (Germany); Kamps, T. [HZB (Germany); Kneisel, P. [JLab (Germany); Voelker, J. [HZB (Germany); Humboldt Universitaet Berlin (Germany); Volkov, V. [BINP (Germany); Will, I. [MBI (Germany)

    2013-07-01

    The development of a superconducting photo injector is an ongoing challenge at the HZDR in Dresden. Several milestones like the first operation of a half cell niobium cavity in 2002 and the worldwide first beam transfer from a 3 1/2-cell SRF gun into an actual accelerator structure have already been accomplished. Nevertheless, as superconducting electron sources are of great interest for future ERL or cw operated FEL projects, studies to improve their output parameters and stability continue to get them on the same level as their normal conducting counterparts. The talk discusses several of the current approaches to reduce the transversal emittance of the next 3 1/2-cell cavity at the HZDR including the installation of a superconducting solenoid within the gun's cryostat.

  18. Radiation dosimetry in radiotherapy with internal emitters

    Energy Technology Data Exchange (ETDEWEB)

    Stabin, Michael G. [Oak Ridge Inst. for Science and Education, TN (United States)

    1997-12-31

    Full text. Radiation dosimetry radionuclides are currently being labeled to various biological agents used in internal emitter radiotherapy. This talk will review the various technologies and types of radiolabel in current use, with focus on the characterization of the radiation dose to the various important tissues of the body. Methods for obtaining data, developing kinetic models, and calculating radiation doses will be reviewed. Monoclonal antibodies are currently being labeled with both alpha and beta emitting radionuclides in attempts to find effective agents against cancer. Several radionuclides are also being used as bone pain palliation agents. These agents must be studied in clinical trials to determine the biokinetics and radiation dosimetry prior to approval for general use. In such studies, it is important to ensure the collection of the appropriate kinds of data and to collect the data at appropriate time intervals. The uptake and retention of activity in all significant source organs and in excreta be measured periodically (with at least 2 data points phase of uptake or clearance). Then, correct dosimetry methods must be applied - the best available methods for characterizing the radionuclide kinetic and for estimating the dosimetry in the various organs of the body especially the marrow, should be used. Attempts are also under way to develop methods for estimating true patient-specific dosimetry. Cellular and animal studies are also. Valuable in evaluating the efficacy of the agents in shrinking or eliminating tumors; some results from such studies will also be discussed. The estimation of radiation doses to patients in therapy with internal emitters involves several complex phases of analysis. Careful attention to detail and the use of the best available methods are essential to the protection of the patient and a successful outcome

  19. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core

    Science.gov (United States)

    Thomas, Jens; Ma, Chung-Pei; McConnell, Nicholas J.; Greene, Jenny E.; Blakeslee, John P.; Janish, Ryan

    2016-04-01

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day ‘dormant’ descendants of this population of ‘active’ black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall—the largest local structure of galaxies. The most luminous quasars, however, are not confined to such high-density regions of the early Universe; yet dormant black holes of this high mass have not yet been found outside of modern-day rich clusters. Here we report observations of the stellar velocity distribution in the galaxy NGC 1600—a relatively isolated elliptical galaxy near the centre of a galaxy group at a distance of 64 megaparsecs from Earth. We use orbit superposition models to determine that the black hole at the centre of NGC 1600 has a mass of 17 billion solar masses. The spatial distribution of stars near the centre of NGC 1600 is rather diffuse. We find that the region of depleted stellar density in the cores of massive elliptical galaxies extends over the same radius as the gravitational sphere of influence of the central black holes, and interpret this as the dynamical imprint of the black holes.

  20. Fabrication of fiber-optic broadband ultrasound emitters by micro-opto-mechanical technology

    International Nuclear Information System (INIS)

    A micro-opto-mechanical system (MOMS) technology for the fabrication of fiber-optic optoacoustic emitters is presented. The described devices are based on the thermoelastic generation of ultrasonic waves from patterned carbon films obtained by the controlled pyrolysis of photoresist layers and fabricated on miniaturized single-crystal silicon frames used to mount the emitters on the tip of an optical fiber. Thanks to the micromachining process adopted, high miniaturization levels are reached in the fabrication of the emitters, and self-standing devices on optical fiber with diameter around 350 µm are demonstrated, potentially suited to minimally invasive medical applications. The functional testing of fiber-optic emitter prototypes in water performed by using a 1064 nm Q-switched Nd-YAG excitation laser source is also presented, yielding broadband emission spectra extended from low frequencies up to more than 40 MHz, and focused emission fields with a maximum peak-to-peak pressure level of about 1.2 MPa at a distance of 1 mm from the devices. (paper)

  1. Flexible Field Emitter for X-ray Generation by Implanting CNTs into Nickel Foil

    Science.gov (United States)

    Sun, Bin; Wang, Yan; Ding, Guifu

    2016-07-01

    This paper reports a novel implanting micromachining technology. By using this method, for the first time, we could implant nano-scale materials into milli-scale metal substrates at room temperature. Ni-based flexible carbon nanotube (CNT) field emitters were fabricated by the novel micromachining method. By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved. As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability. Moreover, the emitter was highly flexible with preservation of the field emission properties. The excellent field emission characteristics attributed to the direct contact and the strong interactions between CNTs and the substrate. To check the practical application of the novel emitter, a simple X-ray imaging system was set up by modifying a traditional tube. The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray.

  2. MICE: the Muon Ionization Cooling Experiment. Step I: First Measurement of Emittance with Particle Physics Detectors

    CERN Document Server

    Bravar, U; Karadzhov, Y; Kolev, D; Russinov, I; Tsenov, R; Wang, L; Xu, F Y; Zheng, S X; Bertoni, R; Bonesini, M; Mazza, R; Palladino, V; Cecchet, G; de Bari, A; Capponi, M; Iaciofano, A; Orestano, D; Pastore, F; Tortora, L; Ishimoto, S; Suzuki, S; Yoshimura, K; Mori, Y; Kuno, Y; Sakamoto, H; Sato, A; Yano, T; Yoshida, M; Filthaut, F; Vretenar, M; Ramberger, S; Blondel, A; Cadoux, F; Masciocchi, F; Graulich, J S; Verguilov, V; Wisting, H; Petitjean, C; Seviour, R; Ellis, M; Kyberd, P; Littlefield, M; Nebrensky, J J; Forrest, D; Soler, F J P; Walaron, K; Cooke, P; Gamet, R; Alecou, A; Apollonio, M; Barber, G; Dobbs, A; Dornan, P; Fish, A; Hare, R; Jamdagni, A; Kasey, V; Khaleeq, M; Long, K; Pasternak, J; Sakamoto, H; Sashalmi, T; Blackmore, V; Cobb, J; Lau, W; Rayner, M; Tunnell, C D; Witte, H; Yang, S; Alexander, J; Charnley, G; Griffiths, S; Martlew, B; Moss, A; Mullacrane, I; Oats, A; York, S; Apsimon, R; Alexander, R J; Barclay, P; Baynham, D E; Bradshaw, T W; Courthold, M; Hayler, R Edgecock T; Hills, M; Jones, T; McNubbin, N; Murray, W J; Nelson, C; Nicholls, A; Norton, P R; Prior, C; Rochford, J H; Rogers, C; Spensley, W; Tilley, K; Booth, C N; Hodgson, P; Nicholson, R; Overton, E; Robinson, M; Smith, P; Adey, D; Back, J; Boyd, S; Harrison, P; Norem, J; Bross, A D; Geer, S; Moretti, A; Neuffer, D; Popovic, M; Qian, Z; Raja, R; Stefanski, R; Cummings, M A C; Roberts, T J; DeMello, A; Green, M A; Li, D; Sessler, A M; Virostek, S; Zisman, M S; Freemire, B; Hanlet, P; Huang, D; Kafka, G; Kaplan, D M; Snopok, P; Torun, Y; Onel, Y; Cline, D; Lee, K; Fukui, Y; Yang, X; Rimmer, R A; Cremaldi, L M; Hart, T L; Summers, D J; Coney, L; Fletcher, R; Hanson, G G; Heidt, C; Gallardo, J; Kahn, S; Kirk, H; Palmer, R B

    2011-01-01

    The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) de...

  3. Flexible Field Emitter for X-ray Generation by Implanting CNTs into Nickel Foil.

    Science.gov (United States)

    Sun, Bin; Wang, Yan; Ding, Guifu

    2016-12-01

    This paper reports a novel implanting micromachining technology. By using this method, for the first time, we could implant nano-scale materials into milli-scale metal substrates at room temperature. Ni-based flexible carbon nanotube (CNT) field emitters were fabricated by the novel micromachining method. By embedding CNT roots into Ni foil using polymer matrix as transfer media, effective direct contact between Ni and CNTs was achieved. As a result, our novel emitter shows relatively good field emission properties such as low turn-on field and good stability. Moreover, the emitter was highly flexible with preservation of the field emission properties. The excellent field emission characteristics attributed to the direct contact and the strong interactions between CNTs and the substrate. To check the practical application of the novel emitter, a simple X-ray imaging system was set up by modifying a traditional tube. The gray shadow that appears on the sensitive film after being exposed to the radiation confirms the successful generation of X-ray. PMID:27401089

  4. Empowering billions with food safety and food security

    International Nuclear Information System (INIS)

    Full text: There are virtually millions of people -who die needlessly every year due to contaminated water and food. There are virtually many millions more who are starving due to an inadequate supply of food. Billions of pounds of food are unnecessarily wasted due to insect and other damage. Deaths and illness due to contaminated food or inadequate food are at catastrophic levels in many regions of the world. A majority of the food and water borne illnesses and deaths are preventable. It can be prevented by improved food production methods, improved food processing technologies, improved food distribution systems and improved personal hygiene. Food irradiation technology is over 100 years old. Yet, this technology is poorly understood by governments and corporate decision makers all around the world. Many consumers also are unfortunately misinformed of this technology. There is an urgent need for nations and people around the world to empower themselves with the knowledge and the expertise to harness this powerful technology. Widespread and sensible adoption of this technology can empower billions around the world with clean and abundant food supplies. It is unconscionable in the 21st century for governments to allow people to die or go hungry when the technology to prevent them is readily available

  5. Electron microscopy reveals unique microfossil preservation in 1 billion-year-old lakes

    International Nuclear Information System (INIS)

    Electron microscopy was applied to the study of 1 billion-year-old microfossils from northwest Scotland in order to investigate their 3D morphology and mode of fossilization. 3D-FIB-SEM revealed high quality preservation of organic cell walls with only minor amounts of post-mortem decomposition, followed by variable degrees of morphological alteration (folding and compression of cell walls) during sediment compaction. EFTEM mapping plus SAED revealed a diverse fossilizing mineral assemblage including K-rich clay, Fe-Mg-rich clay and calcium phosphate, with each mineral occupying specific microenvironments in proximity to carbonaceous microfossil cell walls

  6. Barium fluoride whispering-gallery-mode disk-resonator with one billion quality-factor

    OpenAIRE

    Lin, Guoping; Diallo, Souleymane; Henriet, Rémi; Jacquot, Maxime; Chembo, Yanne K.

    2015-01-01

    We demonstrate a monolithic optical whispering gallery mode resonator fabricated with barium fluoride (BaF$_2$) with an ultra-high quality ($Q$) factor above $10^9$ at $1550$ nm, and measured with both the linewidth and cavity-ring-down methods. Vertical scanning optical profilometry shows that the root mean square surface roughness of $2$ nm is achieved for our mm-size disk. To the best of our knowledge, we show for the first time that one billion $Q$-factor is achievable by precision polish...

  7. Fabrication of a Cryogenic Terahertz Emitter for Bolometer Focal Plane Calibrations

    Science.gov (United States)

    Chervenak, James; Brown, Ari; Wollack, Edward

    2012-01-01

    A fabrication process is reported for prototype emitters of THz radiation, which operate cryogenically, and should provide a fast, stable blackbody source suitable for characterization of THz devices. The fabrication has been demonstrated and, at the time of this reporting, testing was underway. The emitter is similar to a monolithic silicon bolometer in design, using both a low-noise thermometer and a heater element on a thermally isolated stage. An impedance-matched, high-emissivity coat ing is also integrated to tune the blackbody properties. This emitter is designed to emit a precise amount of power as a blackbody spectrum centered on terahertz frequencies. The emission is a function of the blackbody temperature. An integrated resistive heater and thermometer system can control the temperature of the blackbody with greater precision than previous incarnations of calibration sources that relied on blackbody emission. The emitter is fabricated using a silicon- on-insulator substrate wafer. The buried oxide is chosen to be less than 1 micron thick, and the silicon device thickness is 1-2 microns. Layers of phosphorus compensated with boron are implanted into and diffused throughout the full thickness of the silicon device layer to create the thermometer and heater components. Degenerately doped wiring is implanted to connect the devices to wire-bondable contact pads at the edge of the emitter chip. Then the device is micromachined to remove the thick-handle silicon behind the thermometer and heater components, and to thermally isolate it on a silicon membrane. An impedance- matched emissive coating (ion assisted evaporated Bi) is applied to the back of the membrane to enable high-efficiency emission of the blackbody spectrum.

  8. Design and characterization of a movable emittance meter for low-energy electron beams

    International Nuclear Information System (INIS)

    In order to characterize and optimize the beam emittance compensation scheme [L. Serafini and J. B. Rosenzweig, Phys. Rev. E 55, 7565 (1997)] of the Sorgente Pulsata Autoamplificata di Radiazione Coerente project [D. Alesini et al., Nucl. Instrum. Methods Phys. Res. A 507, 345 (2003)] high brightness preinjector a system to accurately measure the beam rms emittance evolution downstream of the rf gun has been developed. Since in a space charge dominated beam the quadrupole-scan method is not applicable, a movable emittance measurement device has been built based on the pepper-pot technique. The device consists of a double system of horizontal and vertical slit arrays and a downstream screen, all installed on a longitudinally movable support equipped with bellows and spanning the ≅1.2 m long drift space between gun and first accelerating section. The system allows the measuring of the beam rms emittance all along the spanned region so as to accurately reconstruct its evolution along the beam trajectory. More than a simple improvement over more conventional beam emittance measurement tools this device defines a new strategy for characterizing high performance photoinjectors as it allows a detailed analysis of the beam behavior over a section of the accelerator where crucial beam shaping takes place. Numerical simulations of the measurement, mainly based on PARMELA [J. Billen, PARMELA Report No. LA-UR 96-1835, 1996 (unpublished)], have been used to estimate the achievable accuracy and to optimize the experimental setup. Wake field effects induced by the beam propagation through the bellows have also been investigated with HOMDYN [M. Ferrario et al., LCLS Report No. SLAC-PUB 84000, 1999 (unpublished)]. A series of laboratory tests to evaluate its performance has been carried out at LNF in Frascati. The system was then moved to DESY Zeuthen and installed on the Photo Injector Test Facility PITZ, for further testing with beam. Design criteria and tests carried out to

  9. Physical electrostatics of small field emitter arrays/clusters

    Science.gov (United States)

    Forbes, Richard G.

    2016-08-01

    This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field emitter arrays/clusters. Using the "floating sphere at emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like emitters. For the isolated emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated emitters) image charges. For the 2-emitter system, formulas are found for charge-transfer ("charge-blunting") effects and neighbor-field effects, for widely spaced and for "sufficiently closely spaced" emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-emitter equispaced linear array, differential charge-blunting and differential neighbor-field effects occur, but differential charge-blunting effects are dominant, and cause the "exposed" outer emitters to have higher AFEF (γ0) than the central emitter (γ1). Formulas are found for the exposure ratio Ξ = γ0/γ1, for large and for sufficiently small separations. The FSEPP model for an isolated emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM implementations is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which is different from the FSEPP-model formulas. This discrepancy needs to be investigated, using systematic Laplace-based simulations and appropriate results

  10. Low-emittance tuning at the Cornell Electron Storage Ring

    CERN Document Server

    Shanks, James; Sagan, David

    2013-01-01

    In 2008 the Cornell Electron/Positron Storage Ring (CESR) was reconfigured from an electron/positron collider to serve as a testbed for the International Linear Collider (ILC) damping rings. One of the primary goals of the CESR Test Accelerator (CesrTA) project is to develop low emittance tuning techniques to achieve sub-10pm geometric vertical emittance at 2.085 GeV. This paper discusses the tuning methods used at CesrTA to achieve low-emittance conditions. A minimum vertical emittance of 8.7 +2.9/-3.4(sys) +/-0.2(stat) pm has been achieved at 2.085 GeV. In various configurations and beam energies the correction technique routinely achieves vertical emittance <15 pm after correction. Beam-based measurement and correction requires about 15 minutes. Simulations modeling the effects of magnet misalignments, BPM errors, and emittance correction algorithm suggest the residual vertical emittance measured at the conclusion of the tuning procedure is dominated by sources other than optics errors and misalignments...

  11. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core

    CERN Document Server

    Thomas, Jens; McConnell, Nicholas J; Greene, Jenny E; Blakeslee, John P; Janish, Ryan

    2016-01-01

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day dormant descendants of this population of active black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall - the largest local structure of galaxies. The most luminous quasars, however, are not confined to such high-density regions of the early Universe; yet dormant black holes of this high mass have not yet been found outside of modern-day rich clusters. Here we report observations of the stellar velocity distribution in the galaxy NGC 1600 - a relatively isolated elliptical galaxy near the centre of a galaxy group at a distance of 64 Mpc from Earth. We use orbit superposition models to determine that the ...

  12. Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

    International Nuclear Information System (INIS)

    Microfabricated electrospray thrusters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1–100 kg). We present the modeling, design, fabrication and characterization of a new generation of devices, for the first time integrating in the fabrication process individual accelerator electrodes capable of focusing and accelerating the emitted sprays. Integrating these electrodes is a key milestone in the development of this technology; in addition to increasing the critical performance metrics of thrust, specific impulse and propulsive efficiency, the accelerators enable a number of new system features such as power tuning and thrust vectoring and balancing. Through microfabrication, we produced high density arrays (213 emitters cm−2) of capillary emitters, assembling them at wafer-level with an extractor/accelerator electrode pair separated by micro-sandblasted glass. Through IV measurements, we could confirm that acceleration could be decoupled from the extraction of the spray—an important element towards the flexibility of this technology. We present the largest reported internally fed microfabricated arrays operation, with 127 emitters spraying in parallel, for a total beam of 10–30 µA composed by 95% of ions. Effective beam focusing was also demonstrated, with plume half-angles being reduced from approximately 30° to 15° with 2000 V acceleration. Based on these results, we predict, with 3000 V acceleration, thrust per emitter of 38.4 nN, specific impulse of 1103 s and a propulsive efficiency of 22% with <1 mW/emitter power consumption. (paper)

  13. Method and apparatus for multispray emitter for mass spectrometry

    Science.gov (United States)

    Smith, Richard D.; Tang, Keqi; Lin, Yuehe

    2004-12-14

    A method and apparatus that utilizes two or more emitters simultaneously to form an electrospray of a sample that is then directed into a mass spectrometer, thereby increasing the total ion current introduced into an electrospray ionization mass spectrometer, given a liquid flow rate of a sample. The method and apparatus are most conveniently constructed as an array of spray emitters fabricated on a single chip, however, the present invention encompasses any apparatus wherein two or more emitters are simultaneously utilized to form an electrospray of a sample that is then directed into a mass spectrometer.

  14. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  15. A General Slice Moment Decomposition of RMS Beam Emittance

    CERN Document Server

    Mitchell, Chad

    2015-01-01

    The square of the horizontal projected (rms) beam emittance is expressed as the sum of four nonnegative contributions, each described using the slice moments of the beam and possessing a natural interpretation in terms of the geometrical properties of the beam in the six-dimensional phase space. The mathematical formalism describing the relationships between projected beam quantities and slice beam quantities is reviewed. The results may be used to reconstruct the moments and emittances of the beam from the moments of its subpopulations, as well as to isolate and better understand a variety of slice and interslice dynamical contributions to the projected beam emittance growth.

  16. Scaled, circular-emitter Penning SPS for intense H- beams

    International Nuclear Information System (INIS)

    The Los Alamos versions of the Penning Surface-Plasma Source (SPS) routinely generate H- ion beams with pulsed currents over 100 mA. However, these sources employ geometries that result in the extraction of slit beams (0.5 x 10 mm2). Our modeling with the SNOW code indicates that the beam from a 5.4-mm-diam circular emitter will have lower emittance and divergence for transport to and injection into our radio-frequency quadrupole (RFQ) accelerator. This paper describes a newly constructed Penning SPS that has most of its discharge chamber dimensions scaled up by a factor of 4 to accommodate this circular emitter

  17. Emittance Measurement with Upgraded RF Gun System at SPring-8

    CERN Document Server

    Mizuno, Akihiko; Hanaki, Hirofumi; Taniuchi, Tsutomu; Tomizawa, Hiromitsu; Uesaka, Mitsuru

    2005-01-01

    A single cell S-band RFgun has been developed at the SPring-8 since 1996. The minimum normalized beam emittance, measured with double slits' scanning method in 2002, was 2.3 pi mm mrad at the exit of the gun cavity with charge of 0.1 nC/bunch. In 2004, we installed a following accelerator structure to investigate beam behavior of the whole injector system. In this paper, we report emittance measurement results of upgraded system, using variable quadrupole magnet method. The minimum emittance of 2.0 pi mm mrad with a net charge of 0.14 nC/bunch were able to be measured.

  18. Emittance Adapter for a Diffraction Limited Synchrotron Radiation Source

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alexander Wu; /SLAC; Raimondi, Pantaleo; /Frascati

    2012-03-01

    We investigate the possibility of reaching very small horizontal and vertical emittances inside an undulator in a storage ring, by means of a local exchange of the apparent horizontal and vertical emittances, performed with a combination of skew quadrupoles and one solenoid in a dedicated insertion line in the storage ring. The insertion leaves the ring parameters and its optical properties unaffected. This scheme could greatly relax the emittance requirements for a diffraction limited synchrotron light source. The lattice derivation and design is described.

  19. Performance of fast reactor irradiated fueled emitters at goal burnup

    International Nuclear Information System (INIS)

    UO2-fueled W emitters were examined that had been irradiated to goal burnups of approximately 4 at.% at emitter surface temperatures to 1820 K in a fast reactor to establish their performance for use in thermionic reactors with power levels from tens of kilowatts to multimegawatts. The examinations provided first-time data on structural integrity, dimensional stability, component compatibility, and fuel and fission product behavior. The data are consistent with similar measurements at approximately 2 at.% burnup with the exception of one emitter which breached the W during irradiation

  20. Multi-dimensional beam emittance and β-functions

    International Nuclear Information System (INIS)

    The concept of r.m.s. emittance is extended to the case of several degrees of freedom that are coupled. That multi-dimensional emittance is lower than the product of the emittances attached to each degree of freedom, but is conserved in a linear motion. An envelope-hyperellipsoid is introduced to define the β-functions of the beam envelope. On the contrary of an one-degree of freedom motion, it is emphasized that these envelope functions differ from the amplitude functions of the normal modes of motion as a result of the difference between the Liouville and Lagrange invariants. (author) 4 refs

  1. Orbital forcing of climate 1.4 billion years ago

    DEFF Research Database (Denmark)

    Zhang, Shuichang; Wang, Xiaomei; Hammarlund, Emma U.;

    2015-01-01

    Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally...... well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe two patterns of climate fluctuations: On long time scales, over what amounts to tens of millions of years, sediments of the Xiamaling Formation record changes in geochemistry consistent with long-term changes...... reflect what appear to be orbitally forced changes in wind patterns and ocean circulation as they influenced rates of organic carbon flux, trace metal accumulation, and the source of detrital particles to the sediment....

  2. The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud

    NARCIS (Netherlands)

    A. Abramowski; al et; A. Balzer; D. Berge; M. Bryan; D. Salek; J. Vink

    2015-01-01

    The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most en

  3. Efficient field emission characteristics from a planar-gate surface-conduction electron source with ZnO emitters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.A.; Chu, Z.H.; Zhou, X.T., E-mail: xtzhou@fzu.edu.cn; Guo, T.L., E-mail: gtl_fzu@hotmail.com

    2015-09-25

    Highlights: • The planar-gate surface-conduction electron source has been fabricated. • ZnO nanorods deposited on the cathode are used as field emission emitters. • ZnO nanorods deposited in the C–G gap are used as surface conduction emitters. • High electron emission efficiency is obtained at low gate voltage. • The fabricated electron source has an efficient field emission property. - Abstract: A planar-gate surface-conduction electron source with ZnO nanorods has been successfully fabricated, where ZnO nanorods deposited on the cathode are used as field emission emitters and ZnO nanorods deposited in the gap between cathode and gate electrode (C–G gap) are used as surface-conduction emitters. Field emission investigations indicate that the turn-on voltage at emission current of 10 μA is approximately 85 V. The emission current and conduction current reach to 520 V and 450 V at the gate voltage and anode voltage of 140 V and 2000 V, respectively. High electron emission efficiency (56.2%) is obtained at low gate voltage of 140 V. The maximum brightness can reach 1200 cd/m{sup 2} and the emission current fluctuation is smaller than 5% for 6 h. These results indicate that the electron source based on the planar-gate surface-conduction triode with ZnO emitters has efficient field emission characteristics.

  4. Minimization of the emittance growth of multi-charge particle beams in the charge stripping section of RAON

    International Nuclear Information System (INIS)

    The charge stripping section of the Rare isotope Accelerator Of Newness (RAON), which is one of the critical components to achieve a high power of 400 kW with a short lianc, is a source of transverse emittance growth. The dominant effects are the angular straggling in the charge stripper required to increase the charge state of the beam and chromatic aberrations in the dispersive section required to separate the selected ion beam from the various ion beams produced in the stripper. Since the main source of transverse emittance growth in the stripper is the angular straggling, it can be compensated for by changing the angle of the phase ellipse. Therefore the emittance growth is minimized by optimizing the Twiss parameters at the stripper. The emittance growth in the charge selection section is also minimized by the correction of high-order aberrations using six sextupole magnets. In this paper, we present a method to minimize the transverse emittance growth in the stripper by changing the Twiss parameters and in the charge selection section by using sextupole magnets

  5. Novalike Cataclysmic Variables are Significant Radio Emitters

    CERN Document Server

    Coppejans, Deanne L; Miller-Jones, James C A; Rupen, Michael P; Knigge, Christian; Sivakoff, Gregory R; Groot, Paul J

    2015-01-01

    Radio emission from non-magnetic cataclysmic variables (CVs, accreting white dwarfs) could allow detailed studies of outflows and possibly accretion flows in these nearby, numerous and non-relativistic compact accretors. Up to now, however, very few CVs have been detected in the radio. We have conducted a VLA pilot survey of four close and optically-bright novalike CVs at 6 GHz, detecting three, and thereby doubling the number of radio detections of these systems. RW Sex, V603 Aql and the old nova TT Ari were detected in both of the epochs, while V1084 Her was not detected (to a $3\\sigma$ upper-limit of 7.8 $\\mu\\rm{Jy}\\,\\rm{beam}^{-1}$). These observations clearly show that the sensitivity of previous surveys was typically too low to detect these objects and that non-magnetic CVs can indeed be significant radio emitters. The three detected sources show a range of properties, including flaring and variability on both short ($\\sim$200 s) and longer-term (days) time-scales, as well as circular polarization level...

  6. Evidence of minority carrier injection efficiency >90% in an epitaxial graphene/SiC Schottky emitter bipolar junction phototransistor for ultraviolet detection

    Energy Technology Data Exchange (ETDEWEB)

    Chava, Venkata S. N., E-mail: vchava@email.sc.edu; Omar, Sabih U.; Brown, Gabriel; Shetu, Shamaita S.; Andrews, J.; Sudarshan, T. S.; Chandrashekhar, M. V. S. [Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States)

    2016-01-25

    In this letter, we report the UV detection characteristics of an epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistor (SEPT) with EG on top as the transparent Schottky emitter layer. Under 0.43 μW UV illumination, the device showed a maximum common emitter current gain of 113, when operated in the Schottky emitter mode. We argue that avalanche gain and photoconductive gain can be excluded, indicating minority carrier injection efficiency, γ, as high as 99% at the EG/p-SiC Schottky junction. This high γ is attributed to the large, highly asymmetric barrier, which EG forms with the p-SiC. The maximum responsivity of the UV phototransistor is estimated to be 7.1 A/W. The observed decrease in gain with increase in UV power is attributed to recombination in the base region, which reduces the minority carrier lifetime.

  7. Evidence of minority carrier injection efficiency >90% in an epitaxial graphene/SiC Schottky emitter bipolar junction phototransistor for ultraviolet detection

    International Nuclear Information System (INIS)

    In this letter, we report the UV detection characteristics of an epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistor (SEPT) with EG on top as the transparent Schottky emitter layer. Under 0.43 μW UV illumination, the device showed a maximum common emitter current gain of 113, when operated in the Schottky emitter mode. We argue that avalanche gain and photoconductive gain can be excluded, indicating minority carrier injection efficiency, γ, as high as 99% at the EG/p-SiC Schottky junction. This high γ is attributed to the large, highly asymmetric barrier, which EG forms with the p-SiC. The maximum responsivity of the UV phototransistor is estimated to be 7.1 A/W. The observed decrease in gain with increase in UV power is attributed to recombination in the base region, which reduces the minority carrier lifetime

  8. Non-blinking single-photon emitters in silica

    Science.gov (United States)

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; Stam, Ward van der; Vanmaekelbergh, Daniel; Koenderink, A. Femius; Krauss, Todd D.; Donega, Celso de Mello

    2016-01-01

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters, do not blink, and have photoluminescence lifetimes of a few nanoseconds. Photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots. PMID:26892489

  9. Beam Emittance Measurement for PLS-II Linac

    CERN Document Server

    Lee, Byung-Joon; Park, Chong do; Chunjarean, SomJai; Kim, Changbum

    2016-01-01

    The PLS-II has a 100 MeV pre-injector for the 3 GeV Linac. A thermionic gun produces electron charge of 200 pC with a bunch duration of 500 ps by a 250 ps triggering pulser. At the pre-injector, one of the most important beam parameters to identify the beam quality is a transverse emittance of electron bunches. Therefore we measure the beam emittance and twiss functions at 100 MeV in order to match the beam optics to beam transport line and go through it to the storage ring. To get the transverse emittance measurement, well-known technique, quadrupole scan, is used at the pre-injector. The emittance were 0.591 mm-mrad in horizontal and 0.774 mm-mrad in vertical direction.

  10. CSR-induced emittance growth in achromats: Linear formalism revisited

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.

    2015-09-11

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  11. CSR-induced emittance growth in achromats: Linear formalism revisited

    Science.gov (United States)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  12. Emitter Design and Numerical Simulation Based on the Extenics Theory

    Directory of Open Access Journals (Sweden)

    Jiang Fan

    2014-05-01

    Full Text Available In order to improve the performance of emitter, the extenics theory is introduced, whose divergent thinking is used to resolve the conflict of anti-clogging and energy dissipation and a new structure is proposed. The wide triangular areas are designed to reduce the flow rate behind of the each orifice and be easy to precipitation of impurities. The orifices are set to gradually decrease water kinetic energy and the flow channel is designed to be dismantle. The numerical simulation technology is used to analyze the internal flow field of emitter, the flow field results show that the improved emitter has great effect of energy dissipation and anti-clogging. As the same time, the structure of emitter is optimized and L1 = 31 mm, L2 = 21 mm, L3 = 8 mm and L4 = 5 mm are the optimization size values.

  13. The emittance of space radiator materials measured at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mirtich, M.J. [Lewis Research Center, Cleveland, OH (United States); DiFilippo, F. [Case Western Reserve Univ., Cleveland, OH (United States); Barry, J.; Kussmaul, M. [Cleveland State Univ., OH (United States)

    1994-09-01

    The spectral emittances of textured space radiator materials between 1.7 and 14.7 {mu}m have been evaluated at room temperature and elevated temperature (630{degrees}C) in air. Heating in air caused a permanent increase in spectral emittance for all materials tested: HCl/ion beam textured 304 stainless steel, untextured Ti (6 percent Al, 4 percent V), and sandblasted Ti (6 percent Al, 4 percent V). Changes in the surface chemistry and/or surface morphology of these materials were also observed. Elevated temperature spectral emittance was measured in an argon atmosphere and compared to the measurements in air. Similarity between the room temperature and elevated temperature spectral emittance measurements was also investigated, and limited agreement was found.

  14. Intelligent Variable Emittance Panels Using New, ?True? Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This firm has, in ongoing work in collaboration with the Air Force, NASA and JPL, developed a unique Variable Emittance technology based on the electrochromism of...

  15. 128x96 pixel field emitter-array image sensor with HARP target

    Science.gov (United States)

    Yamagishi, Toshio; Nanba, Masakazu; Osada, Katsunori; Takiguchi, Yoshiro; Okazaki, Saburo; Egami, Norifumi; Tanioka, Kenkichi; Tanaka, Mitsuru; Itoh, Shigeo

    2002-04-01

    In pursuit of developing a next-generation pick-up device having high definition and ultrahigh sensitivity features, research continues on a new type of image sensor that combines a HARP target and a field emitter array. A new field emitter array on a small-sized substrate is designed and a unique packaging technique is proposed. The prototype device is sealed in a vacuum package with a thickness of only about 10 mm and has 128 horizontal and 96 vertical pixels. Experimental results show that images could be successfully reproduced for the first time ever in a device of this type. Highly sensitive characteristics and propr resolution were also obtained with the device. The prototype image sensor can operate stably for more than 250 hours, demonstrating its feasibility and potential as a next- generation image pickup device.

  16. Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromat

    CERN Document Server

    Huang, Xiyang; Cui, Xiaohao; Xu, Gang

    2014-01-01

    Coherent synchrotron radiation (CSR) effect at a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and of high peak current. Suppression of the emittance growth induced by CSR is essential and critical to preserve the beam quality and to help improve the machine performance. To evaluate the CSR effect analytically, we have proposed a novel method, which enabled us to obtain generic conditions of cancelling the CSR linear effect in a two-dipole achromat. In this paper, it illustrates that with this method the CSR-cancellation condition can be obtained for a TBA with symmetric layout, which is independent of concrete element parameters, and to a large extent, the initial beam distribution. Implementation of found condition in concrete optics design of a TBA is discussed, and the proposed condition is verified through numerical simulations.

  17. Inducing electron emission from field emitter arrays by fs near infrared laser pulses

    International Nuclear Information System (INIS)

    Full text: Field-emitter array (FEA) cathode generates electron beam by electron tunneling under intense electric field. Although FEA are capable of delivering very high current-density, production of short electron bunches with the duration of picosecond or below by electrical switching is challenging limiting their application. In this work, we trigger field emission from ultrasharp tip arrays by 50 fs near infrared laser pulses. Despite small total emission area of FEAs, generation of up 107 electron per laser pulse was observed. Laser-intensity dependence indicated photo-field emission from FEAs as the electron emission process. Electromagnetic simulations demonstrated that sharp tips can enhance emission yields through shape-induced local field enhancement. The observed high charge generation indicates the feasibility of using field-emitter array cathode for applications in THz vacuum electronic as well as accelerator applications like SwissFEL X-ray free electron laser. (author)

  18. Optimization of the emittance of electrons (positrons) storage rings

    International Nuclear Information System (INIS)

    An important parameter of the source characteristics of a synchrotron radiation facility, is the beam emittance. The general structure presently adopted, is of the achromatic arc, or adapted dispersion type. This structure allows analytical treatment of dispersion and β function in the arcs, and then, the minimization of the dimension invariant. Practical formulae are given, allowing scaling of momentum compaction factor, minimum emittance limit and β value in the magnets. Limitations in chromaticity correction possibilities are also discussed

  19. Internal emitter limits for iodine, radium and radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Schlenker, R.A.

    1984-08-15

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (/sup 131/I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables.

  20. Evaluation of Production Reactions for Medically Important Positron Emitters

    International Nuclear Information System (INIS)

    Research activities of direct relevance to the CRP are based on the proposed evaluation of a range of medically important positron emitters. The production and assessment of excitation functions for various novel positron emitters has been recommended for investigation and quantification. Hence, the research group at Lahore has developed an evaluation methodology for charged-particle induced reactions. The main steps of the adopted procedure are listed

  1. Radiation swelling of emitters in nuclear thermoemission converters

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, V.S.

    1976-01-01

    A mathematical model is proposed for the radiation swelling of emitters in nuclear thermoemission converters. This model takes into account the temperature gradients and concentrations of uranium decay products along the emitter cross-section, and also the external pressure and the simultaneous action of various mechanisms of swelling. In the particular case of swelling caused by an increase in gaseous pores, a solution is obtained for this model that is in qualitative agreement with the experiment data.

  2. Emittance growth due to dipole ripple and sextupole

    International Nuclear Information System (INIS)

    Ripple in the power supplies for storage ring magnets can have adverse effects on the circulating beams: orbit distortion and emittance growth from dipole ripple, tune modulation and dynamic aperture reduction from quadrupole ripple, etc. In this paper, the authors study the effects of ripple in the horizontal bending field of the SSC in the presence of nonlinearity, in particular, the growth in beam emittance

  3. Fabrication of VO2-based multilayer structure with variable emittance

    International Nuclear Information System (INIS)

    Highlights: • Multilayer structures consisted of VO2 layer, HfO2 layer and Ag layer. • Influence of VO2 and HfO2 layer thickness on the emittance variability was studied. • Emittance variation of 0.55 and transition temperature (Tc) of 58 °C was obtained. • Multilayer structures with W-doped VO2 film were deposited. • Influence of W doping concentration on emittance variability was investigated. - Abstract: VO2 film holds promise for smart radiation device (SRD) use because of its infrared reflection change through the semiconductor-to-metal transition (SMT). In present study, a multilayer structure which consisted of VO2 layer, HfO2 layer and Ag layer was fabricated to achieve variable emittance based on the principle of reflection filter and SMT of VO2. It was found that with optimal 50 nm-thick VO2 layer, emittance of the multilayer structure could reversibly change from 0.13 at 30 °C to 0.68 at 80 °C with emittance variability of 0.55. Emittance hysteresis loop with transition temperature (Tc) of 58 °C and narrow width of 4 °C was obtained. Finally, multilayer structures with W-doped VO2 films were deposited and transition temperature decreased from 58 to 5 °C as W doping concentration increased from 0% to 3%, with Tc decreasing efficiency of −17.2 °C/at%. However, W doping also led to increased low temperature infrared absorption of VO2 film, which resulted in decreased emittance variability for the multilayer structure, from 0.55 to 0.37 as the W doping concentration in VO2 layer increase from 0% to 3%

  4. A Novel Depletion-Mode MOS Gated Emitter Shorted Thyristor

    Institute of Scientific and Technical Information of China (English)

    张鹤鸣; 戴显英; 张义门; 马晓华; 林大松

    2000-01-01

    A Novel MOS-gated thyristor, depletion-mode MOS gated emitter shorted thyristor (DMST),and its two structures are proposed. In DMST,the channel of depletion-mode MOS makes the thyristor emitter-based junction inherently short. The operation of the device is controlled by the interruption and recovery of the depletion-mode MOS P channel. The perfect properties have been demonstrated by 2-D numerical simulations and the tests on the fabricated chips.

  5. Internal emitter limits for iodine, radium and radon daughters

    International Nuclear Information System (INIS)

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (131I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables

  6. Study of ultra-low emittance design for SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M. -H.; Huang, X.; Safranek, J.; /SLAC

    2015-09-17

    Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now, to further enhance the performance of SPEAR3, we are looking into the possibility of converting SPEAR3 to an ultra-low emittance storage ring within its site constraint.

  7. Final report for Frequency selective surfaces for rugged thermophotovoltaic emitters

    Energy Technology Data Exchange (ETDEWEB)

    Daly, James

    2001-04-05

    Ion Optics created an array of regularly spaced holes in a thin conductive surface film on a dielectric substrate. When heated, this pattern behaved as a selective emitter, with more than 50% of total radiation in a well-defined peak with a center frequency determined by geometrical spacing. Peak wavelength did not alter with change in temperature, and materials easily survived 10 hours at 1000 C in air. The selective emitter will increase efficiency of thermophotovoltaic power converters.

  8. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    Science.gov (United States)

    2011-01-01

    Background The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters. PMID:21658266

  9. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    Directory of Open Access Journals (Sweden)

    Guag Joshua W

    2011-06-01

    Full Text Available Abstract Background The objective of this study is to investigate electromagnetic compatibility (EMC of implantable neurostimulators with the emissions from radio frequency identification (RFID emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  10. Fundamental Limits to Coherent Scattering and Photon Coalescence from Solid-State Quantum Emitters

    OpenAIRE

    Iles-Smith, Jake; McCutcheon, Dara P. S.; Mørk, Jesper; Nazir, Ahsan

    2016-01-01

    The desire to produce high-quality single photons for applications in quantum information science has lead to renewed interest in exploring solid-state emitters in the weak excitation regime. Under these conditions it is expected that photons are coherently scattered, and so benefit from a substantial suppression of detrimental interactions between the source and its phonon environment. Nevertheless, we demonstrate here that this reasoning is incomplete, and phonon interactions continue to pl...

  11. A scintillator based time-of-flight hodoscope with a new type of emitter follower divider

    International Nuclear Information System (INIS)

    A high precision, time-of-flight hodoscope has been constructed to analyse the secondary pion beam at GSI, Darmstadt. The hodoscope comprises three scintillator planes with the individual scintillator rods read out by photomultipliers in both ends. A new active base of the emitter follower type has been developed for stabilization of voltages at the last dynodes of the photomultiplier. The time resolution of this system was found to be σ=<150ps for counting rates up to 2MHz

  12. Suppression of the emittance growth induced by CSR in a DBA cell

    CERN Document Server

    Xiao-Hao, Cui; Gang, Xu; Xi-Yang, Huang

    2013-01-01

    The Emittace growth induced by Coherent Synchrotron Radiation(CSR) is an important issue when electron bunches with short bunch length and high peak current are transported in a bending magnet. In this paper, a single kick method is introduced which could give the same result as the R-matrix method, and much easier to use. Then with this method, an optics design technique which could minimize the emittance dilution within a single achromatic cell.

  13. Detection of nitrite by flow injection analysis using a novel paired emitter-detector diode (PEDD) as a photometric detector

    Science.gov (United States)

    O'Toole, Martina; Shepherd, Roderick; Lau, King-Tong; Diamond, Dermot

    2007-09-01

    An inexpensive flow injection analysis system for determining low concentration levels of nitrite employing the Griess reagent spectrophotometric method is reported. The novel photometric detector applied within this manifold is a highly sensitive, low cost, miniaturized light emitting diode (LED) based flow detector. This colorimetric detector employs two LEDs, operating one as a light source and the other as a light detector. The emitter LED is forward biased and the detector reverse biased. The emitter and detector LED had a λmax of 530 nm and 623 nm respectively. The emission spectrum of the emitter LED efficiently overlapped with the absorbance spectrum of 9 µM NO2 and Griess reagent complex. A simple timer circuit measures the time taken for the photocurrent generated by the emitter LED to discharge the detector LED from 5 V (logic 1) to 1.7 V (logic 0). The Griess reagent method employed for nitrite determination is based on the formation of an azo dye, the intensity of which is directly related to nitrite concentration. The linear range, reproducibility and limit of detection were investigated. Detection limits in the nanomolar range were achieved using the Paired Emitter-Detector Diode (PEDD) flow analysis device. For a comparative study the linear range and limit of detection were also investigated using a platewell reader. Higher sensitivity and improved precision were obtained from the PEDD compared to the commercially available plate well reader.

  14. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  15. 100 W/100 μm passively cooled fiber coupled diode laser at 976 nm based on multiple 100 μm single emitters

    Science.gov (United States)

    Werner, Marcel; Wessling, Christian; Hengesbach, Stefan; Traub, Martin; Hoffmann, Hans-Dieter

    2009-02-01

    We developed a high brightness fiber coupled diode laser module based on single diode lasers providing more than 60 Watts output power from a 100 micron fiber at the optimum fiber laser pump wavelength of 976 nm. The advantage of using multiple single emitters on a submount compared to using bars or mini bars is the direct fiber coupling by use of optical stacking and the fact that no beam transformation is needed. We achieved best brightness with a high fill factor, optical efficiency of more then 80% and wall-plug efficiency of more then 40%. The use of single emitters on a submount also extends the life span due to reduced failure (xn vs. x) per device (n individual emitters vs. n emitters on a bar (mini array)). Low drive current enables modulation.

  16. Prolixe-prototype reprocessing unit for irradiating wastes contamined with alpha emitters

    International Nuclear Information System (INIS)

    A large number of hot cells are employed for research on nuclear fuel reprocessing and the production of isotope of transuranium elements. These activities generate solid wastes highly contaminated with alpha, beta, gamma emitters. The Prolixe hot cell was built in order to: 1/ reprocess the solid wastes contaminated with alpha, beta, gamma emitters produced in the Radiochemistry building: 2/ produce package wastes storable in shallow-ground disposal sites: 3/ develop a process sufficiently flexible to make it applicable to waste produced in other installations. The process is based on waste leaching after grinding. Depending on the type of wastes the leaching reactant will have a different composition 1/ nitric acid solution for cellulose waste: 2/ nitric solutions containing Ag(II) for other material. The complete process should achieve: 1/ a high waste volume reduction factor: 2/ the production of immobilized waste packages storage in shallow-ground disposal sites: 3/ the recycling of transuranium elements: 4/ the generation of a minimal volume of effluents. This process can be considered as an alternative process to incineration for the reprocessing of solid wastes highly contaminated with alpha, beta, gamma emitters

  17. Single-Particle Dynamics in Electron Storage Rings with Extremely Low Emittance

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yunhai; /SLAC

    2011-05-31

    Electron storage rings are widely used for high luminosity colliders, damping rings in high-energy linear colliders, and synchrotron light sources. They have become essential facilities to study high-energy physics and material and medical sciences. To further increase the luminosity of colliders or the brightness of synchrotron light sources, the beam emittance is being continually pushed downward, recently to the nanometer region. In the next decade, another order of reduction is expected. This requirement of ultra-low emittance presents many design challenges in beam dynamics, including better analysis of maps and improvement of dynamic apertures. To meet these challenges, we have refined transfer maps of common elements in storage rings and developed a new method to compute the resonance driving terms as they are built up along a beamline. The method is successfully applied to a design of PEP-X as a future light source with 100-pm emittance. As a result, we discovered many unexpected cancelations of the fourth-order resonance terms driven by sextupoles within an achromat.

  18. Design studies for minimization of beam emittance in the LEHIPA LEBT

    International Nuclear Information System (INIS)

    The main design criterion in the Low Energy Beam Transport (LEBT) system is to transport and match the beam from the ion source into the RFQ with minimum emittance growth and loss of beam current. The LEHIPA LEBT is required to match a 30 mA, 50 keV, CW proton beam from the ion source to the RFQ. At these energies, for such high currents, the space charge forces, which are due to the coulomb repulsion between the particles, are very strong. These forces are highly non-linear and can lead to rapid increase in emittance and beam size. The beam quality and transmission through the RFQ is very sensitive to the beam parameters at its input. Also beam quality degradation is initiated mainly in the low energy sections of the linacs and later manifests itself in the form of beam halos at high energies. So careful studies in matching the beam from the ion source to the RFQ is required for minimizing emittance growth. The beam from the ion source also contains other species like H2+ and H3+ . An important function of the LEBT is also to reject these fractions and prevent them from entering the RFQ. Based on these criterions, detailed beam dynamics simulations have been done to optimize the design of the LEHIPA LEBT which will be presented in this paper. (author)

  19. Miniature electron beam column with a silicon micro field emitter

    International Nuclear Information System (INIS)

    Silicon micro field emitters (Si-MFEs) are expected to be promising as electron sources for their high brightness and ease in making arrayed microcolumns due to small physical size. We have developed a Si-MFE electron gun assembly that produces an electron beam of 1 keV. All components including the Si acceleration electrode are mounted on an integrated circuit (IC) package stem (TO-8) by anodic and eutectic bonding. A high brightness (75 μA/sr) and a long lifetime (>1000 h) have been observed. To overcome the intrinsic emission instability of Si-MFEs, we developed a simple feedback circuit which controls an extraction voltage. The source position shift and the aberration coefficient change caused by stabilization were evaluated analytically and found to be negligible due to the scaling law as applied to micron size. We confirmed that the total emission fluctuation could be stabilized to less than 1% by detecting the absorption current but also found that this detection should be done in the electron beam column to stabilize the probe current due to the instability of the emission angle. Using the Si-MFE electron gun along with a miniature electron beam column 5 cm in length, we evaluated the electron optical properties and succeeded in demonstrating a scanning electron microscope operation with a resolution less than 0.5 μm. copyright 1997 American Vacuum Society

  20. Dust production 0.7-1.5 billion years after the Big Bang

    CERN Document Server

    Michałowski, Michał J

    2015-01-01

    Cosmic dust is an important component of the Universe, and its origin, especially at high redshifts, is still unknown. I present a simple but powerful method of assessing whether dust observed in a given galaxy could in principle have been formed by asymptotic giant branch (AGB) stars or supernovae (SNe). Using this method I show that for most of the galaxies with detected dust emission between z=4 and z=7.5 (1.5-0.7 billion years after the Big Bang) AGB stars are not numerous and efficient enough to be responsible for the measured dust masses. Supernovae could account for most of the dust, but only if all of them had efficiencies close to the maximal theoretically allowed value. This suggests that a different mechanism is responsible for dust production at high redshifts, and the most likely possibility is the grain growth in the interstellar medium.

  1. Barium fluoride whispering-gallery-mode disk-resonator with one billion quality-factor

    CERN Document Server

    Lin, Guoping; Henriet, Rémi; Jacquot, Maxime; Chembo, Yanne K

    2015-01-01

    We demonstrate a monolithic optical whispering gallery mode resonator fabricated with barium fluoride (BaF$_2$) with an ultra-high quality ($Q$) factor above $10^9$ at $1550$ nm, and measured with both the linewidth and cavity-ring-down methods. Vertical scanning optical profilometry shows that the root mean square surface roughness of $2$ nm is achieved for our mm-size disk. To the best of our knowledge, we show for the first time that one billion $Q$-factor is achievable by precision polishing in relatively soft crystals with mohs hardness of ~$3$. We show that complex thermo-optical dynamics can take place in these resonators. Beside usual applications in nonlinear optics and microwave photonics, high energy particle scintillation detection utilizing monolithic BaF$_2$ resonators potentially becomes feasible.

  2. Barium fluoride whispering-gallery-mode disk-resonator with one billion quality-factor.

    Science.gov (United States)

    Lin, Guoping; Diallo, Souleymane; Henriet, Rémi; Jacquot, Maxime; Chembo, Yanne K

    2014-10-15

    We demonstrate a monolithic optical whispering-gallery-mode resonator fabricated with barium fluoride (BaF₂) with an ultra-high quality (Q) factor above 10⁹ at 1550 nm, and measured with both the linewidth and cavity-ring-down methods. Vertical scanning optical profilometry shows that the root mean square surface roughness of 2 nm is achieved for our mm-size disk. To the best of our knowledge, we show for the first time that one billion Q-factor is achievable by precision polishing in relatively soft crystals with mohs hardness of 3. We show that complex thermo-optical dynamics can take place in these resonators. Beside usual applications in nonlinear optics and microwave photonics, high-energy particle scintillation detection utilizing monolithic BaF₂ resonators potentially becomes feasible. PMID:25361142

  3. X-ray Fresnel diffractometry for micron light source size measurement of ultralow-emittance next-generation storage ring

    International Nuclear Information System (INIS)

    A novel emittance diagnostics technique with high sensitivity using X-ray Fresnel diffraction by a single slit has been developed to measure micron-order electron beam sizes at insertion devices (IDs) of photon beamlines. The X-ray Fresnel diffractometry (XFD) is promising for diagnostics of next-generation light sources, where a tuning of ultra-low emittance at IDs is essentially important to ensure the absence of degradation of brilliance and transverse coherence of radiation at beamlines due to distortion of lattice functions. The validity of the new method was theoretically and experimentally studied at SPring-8. The achievable resolution of XFD is also discussed. (author)

  4. Effect of Beamstrahlung on Bunch Length and Emittance in Future Circular e+e- Colliders

    CERN Document Server

    Valdivia Garcia, Marco Alan

    2016-01-01

    In future circular e+e− colliders, beamstrahlung may limit the beam lifetime at high energies, and increase the energy spread and bunch length at low energies. If the dispersion or slope of the dispersion is not zero at the collision point, beamstrahlung will also affect the transverse emittance. In this paper, we first examine the beamstrahlung properties, and show that for the proposed FCC-ee, the radiation is fairly well modelled by the classical formulae describing synchrotron radiation in bending magnets. We then derive a set of equations determining the equilibrium emittances in the presence of a nonzero dispersion at the collision point. An example case from FCC-ee will serve as an illustration.

  5. A Multislit Transverse-Emittance Diagnostic for Space-Charge-Dominated Electron Beams

    Science.gov (United States)

    Piot, P.; Song, J.; Li, R.; Krafft, G. A.; Jordan, K.; Feldl, E.; Kehne, D.; Denard, J.-C.

    1997-05-01

    Jefferson Lab is building a 10 MeV injector to provide electron beam for a high-power free-electron laser (FEL). To characterize the transverse phase space of the space-charged-dominated beam produced by this injector, we designed an interceptive multislit emittance diagnostic. It incorporates an algorithm for phase-space reconstruction and subsequent calculation of the Twiss parameters and emittance for both transverse directions at an update rate exceeding 1 Hz, a speed that will facilitate the transverse-phase-space matching between the injector and the FEL's accelerator that is critical for proper operation. This paper describes issues pertaining to the diagnostic's design. It also discusses the acquisition system, as well as the software algorithm and its implementation in the FEL control system. First results obtained from testing this diagnostic in Jefferson Lab's Injector Test Stand are also included.

  6. Towards a Small Emittance Design of the JLEIC Electron Collider Ring

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Fanglei [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hutton, Andrew M. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Morozov, Vasiliy [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Pilat, Fulvia C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The electron collider ring of the Jefferson Lab Electron-Ion Collider (JLEIC) is designed to provide an electron beam with a small beam size at the IP for collisions with an ion beam in order to reach a desired high luminosity. For a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance that can be obtained through a linear optics design. This paper briefly describes the baseline design of the electron collider ring reusing PEP-II components and considering their parameters (such as dipole sagitta, magnet field strengths and acceptable synchrotron radiation power) and reports a few approaches to reducing the equilibrium emittance in the electron collider ring.

  7. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide

    Science.gov (United States)

    Fuchs, F.; Stender, B.; Trupke, M.; Simin, D.; Pflaum, J.; Dyakonov, V.; Astakhov, G. V.

    2015-07-01

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  8. Noninterceptive transverse emittance measurements using BPM for Chinese ADS R&D project

    Science.gov (United States)

    Wang, Zhi-Jun; Feng, Chi; He, Yuan; Dou, Weiping; Tao, Yue; Chen, Wei-long; Jia, Huan; Liu, Shu-hui; Wang, Wang-sheng; Zhang, Yong; Wu, Jian-qiang; Zhang, Sheng-hu; Zhang, X. L.

    2016-04-01

    The noninterceptive four-dimensional transverse emittance measurements are essential for commissioning the high power continue-wave (CW) proton linacs as well as their operations. The conventional emittance measuring devices such as slits and wire scanners are not well suited under these conditions due to sure beam damages. Therefore, the method of using noninterceptive Beam Position Monitor (BPM) is developed and demonstrated on Injector Scheme II at the Chinese Accelerator Driven Sub-critical System (China-ADS) proofing facility inside Institute of Modern Physics (IMP) [1]. The results of measurements are in good agreements with wire scanners and slits at low duty-factor pulsed (LDFP) beam. In this paper, the detailed experiment designs, data analysis and result benchmarking are presented.

  9. Effects of surface and volume production on emittance in a volume type negative ion source

    International Nuclear Information System (INIS)

    A volume-type negative ion source has been modeled using a version of the Negative Ion Injector Design Analysis Program (NIIDeAP). The purpose of the study was to investigate the relative effects of surface-produced ions and volume-produced ions on the emittance of the total extracted beam. The differences between the two types of ion production can be expected to influence energy and emittance distributions for several reasons. Even though the fundamental physics of ion production in the source imply a low temperature, the effects of magnetic field, internal surface geometry, plasma potential, and superposition of two different populations can result in a significant increase of the apparent temperature. A high precision ion trajectory integrator was used. (Author) 5 figs., 5 refs

  10. Using Spread Spectrum Transform for Fast and Robust Simultaneous Measurement in Active Sensors with Multiple Emitters

    DEFF Research Database (Denmark)

    Harbo, Anders La-Cour; Stoustrup, Jakob

    2002-01-01

    We present a signal processing algorithm for making robust and simultaneous measurements in an active sensor, which has one or more emitters and a receiver, and which employs some sort of signal processing hardware. Robustness means low sensitivity to time and frequency localized disturbances, and...... to white noise. This is achieved partly by using a orthogonal spread spectrum transform for modulating the signals transmitted from the emitters to the receiver, and partly by using a number of transmission channels. The method is fast since the signals are short, and since the method does not rely...... on previously transmitted signals. This also means that only few calculations are needed. Furthermore, the suggested spread spectrum transform has a low complexity, a high numerical stability, and is easily implemented in simple signal processing hardware. The presented method is therefore suitable...

  11. Vacuum Rabi splitting in a plasmonic cavity at the single quantum emitter limit

    CERN Document Server

    Santhosh, Kotni; Chuntonov, Lev; Haran, Gilad

    2015-01-01

    The strong interaction of individual quantum emitters with resonant cavities is of fundamental interest for understanding light matter interactions, as well as for quantum information processing and quantum communication applications. Plasmonic cavities hold the promise of attaining the strong coupling regime even under ambient conditions and within subdiffraction volumes. Recent experiments revealed strong coupling between individual plasmonic structures and multiple organic molecules, but so far strong coupling at the limit of a single quantum emitter has not been reported. Here we demonstrate vacuum Rabi splitting, a manifestation of strong coupling, using silver bowtie plasmonic cavities loaded with semiconductor quantum dots (QDs). A transparency dip is observed in the scattering spectra of individual bowties with one to a few QDs in their gaps. Rabi splitting values as high as 180 meV are registered with a single QD. These observations are verified by polarization-dependent experiments and validated by ...

  12. Growth of carbon nanotube field emitters on single strand carbon fiber: a linear electron source

    International Nuclear Information System (INIS)

    The multi-stage effect has been revisited through growing carbon nanotube field emitters on single strand carbon fiber with a thickness of 11 μm. A prepared linear electron source exhibits a turn-on field as low as 0.4 V μm-1 and an extremely high field enhancement factor of 19 300, when compared with those results from reference nanotube emitters grown on flat silicone wafer; 3.0 V μm-1 and 2500, respectively. In addition, we introduce a novel method to grow nanotubes uniformly around the circumference of carbon fibers by using direct resistive heating on the continuously feeding carbon threads. These results open up not only a new path for synthesizing nanocomposites, but also offer an excellent linear electron source for special applications such as backlight units for liquid crystal displays and multi-array x-ray sources.

  13. Emittance growth and energy loss due to coherent synchrotron radiation in a bunch compressor

    International Nuclear Information System (INIS)

    Electron bunches of high charge (up to 10 nC) are compressed in length in the Compact Linear Collider Test Facility magnetic chicane to less than 0.4 mm rms. The short bunches radiate coherently in the chicane magnetic field, and the horizontal and longitudinal phase space density distributions are affected. This paper reports the results of beam emittance and momentum measurements. Horizontal and vertical emittances and momentum spectra were measured for different bunch compression factors and bunch charges. In particular, for 10 nC bunches, the mean beam momentum decreased by about 5% while the rms momentum spread increased from 2% to 8%. The experimental results are compared with simulations made with the code TRAFIC4

  14. Methods for measuring sub-pm rad vertical emittance at the Swiss Light Source

    Science.gov (United States)

    Breunlin, J.; Andersson, Å.; Milas, N.; Saá Hernández, Á.; Schlott, V.

    2015-12-01

    We report on methods capable of measuring a rms vertical electron beam size of 3 μm with a rms error of less than 10% at a diagnostic beamline at the Swiss Light Source (SLS). This corresponds to a vertical emittance of 0.6 pm rad with a 20% rms error. We showed this capability by presenting the theoretical basis for, and the data from, a series of measurements on a stable beam at 1.6 pm rad vertical emittance at the SLS. The methods presented utilized either π- or σ-polarized synchrotron radiation (SR) in the visible to ultra violet (vis-UV) spectral range. In addition to the established π-polarization method, we introduced a diffraction method with a potentially high resolution capability. Also an intensity imbalanced diffraction scheme was introduced, but was found to be prone to SR induced carbon contamination on optical elements.

  15. Rotating system for four-dimensional transverse rms-emittance measurements

    CERN Document Server

    Xiao, C; Du, X N; Gerhard, P; Groening, L; Mickat, S; Vormann, H

    2016-01-01

    Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the removal of inter-plane correlations to reduce the projected emittances. A dedicated ROtating System for Emittance measurements (ROSE) has been proposed, developed, and successfully commissioned to fully determine the four-dimensional beam matrix. This device has been used at the High Charge injector (HLI) at GSI using a beam line which is composed of a skew quadrupole triplet, a normal quadrupole doublet, and ROSE. Mathematical algorithms, measurements, and results for ion beams of 83Kr13+ at 1.4 MeV/u are reported in this paper.

  16. Efficient mode conversion in an optical nanoantenna mediated by quantum emitters.

    Science.gov (United States)

    Straubel, J; Filter, R; Rockstuhl, C; Słowik, K

    2016-05-15

    Converting signals at low intensities between different electromagnetic modes is an asset for future information technologies. In general, slightly asymmetric optical nanoantennas enable the coupling between bright and dark modes that they sustain. However, the conversion efficiency might be very low. Here, we show that the additional incorporation of a quantum emitter allows us to tremendously enhance this efficiency. The enhanced local density of states cycles the quantum emitter between its upper and lower level at an extremely high rate, hence converting the energy very efficiently. The process is robust with respect to possible experimental tolerances, and adds a new ingredient to be exploited while studying and applying coupling phenomena in optical nanosystems. PMID:27176986

  17. Performance of tantalum-tungsten alloy selective emitters in thermophotovoltaic systems

    Science.gov (United States)

    Stelmakh, Veronika; Rinnerbauer, Veronika; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan

    2014-06-01

    A tantalum tungsten solid solution alloy, Ta 3% W, based 2D photonic crystal (PhC) was designed and fabricated for high-temperature energy conversion applications. Ta 3% W presents advantages compared to the non-alloys as it combines the better high-temperature thermomechanical properties of W with the more compliant material properties of Ta, allowing for a direct system integration path of the PhC as selective emitter/absorber into a spectrum of energy conversion systems. Indeed metallic PhCs are promising as high performance selective thermal emitters for thermophotovoltaics (TPV), solar thermal, and solar TPV applications due to the ability to tune their spectral properties and achieve highly selective emission. A 2D PhC was designed to have high spectral selectivity matched to the bandgap of a TPV cell using numerical simulations and fabricated using standard semiconductor processes. The emittance of the Ta 3% WPhC was obtained from near-normal reectance measurements at room temperature before and after annealing at 1200 °C for 24h in vacuum with a protective coating of 40 nm HfO2, showing high selectivity in agreement with simulations. SEM images of the cross section of the PhC prepared by FIB confirm the structural stability of the PhC after anneal, i.e. the coating effectively prevented structural degradation due to surface diffusion. The mechanical and thermal stability of the substrate was characterized as well as the optical properties of the fabricated PhC. To evaluate the performance of the selective emitters, the spectral selectivity and useful emitted power density are calculated as a function of operating temperature. At 1200 °C, the useful emitted irradiance is selectively increased by a factor of 3 using the selective emitter as compared to the non-structured surface. All in all, this paper demonstrates the suitability of 2D PhCs fabricated on polycrystalline Ta-W substrates with an HfO2 coating for TPV applications.

  18. Interband Tunneling for Hole Injection in III-Nitride Ultraviolet Emitters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuewei [The Ohio State Univ., Columbus, OH (United States); Krishnamoorthy, Sriram [The Ohio State Univ., Columbus, OH (United States); Johnson, Jared M. [The Ohio State Univ., Columbus, OH (United States); Akyol, Fatih [The Ohio State Univ., Columbus, OH (United States); Allerman, Andrew A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moseley, Michael William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Armstrong, Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hwang, Jinwoo [The Ohio State Univ., Columbus, OH (United States); Rajan, Siddharth [The Ohio State Univ., Columbus, OH (United States)

    2015-04-09

    Low p-type conductivity and high contact resistance remain a critical problem in wide band gap AlGaN-based ultraviolet light emitters due to the high acceptor ionization energy. In this work, interband tunneling is demonstrated for non-equilibrium injection of holes through the use of ultra-thin polarization-engineered layers that enhance tunneling probability by several orders of magnitude over a PN homojunction. Al0.3Ga0.7N interband tunnel junctions with a lowresistance of 5.6 × 10-4 Ω cm2 were obtained and integrated on ultraviolet light emitting diodes.Tunnel injection of holes was used to realize GaN-free ultraviolet light emitters with bottom and top n-type Al0.3Ga0.7N contacts. At an emission wavelength of 327 nm, stable output power of 6 W/cm2 at a current density of 120 A/cm2 with a forward voltage of 5.9 V was achieved. Our demonstration of efficient interband tunneling could enable device designs for higher efficiency ultraviolet emitters.

  19. All-Solid-State Electrochromic Variable Emittance Coatings for Thermal Management in Space

    Science.gov (United States)

    Kislov, Nikolai; Groger, Howard; Ponnappan, Rengasamy

    2003-01-01

    The results presented in this article demonstrate the feasibility of ``all-solid-state'' inorganic electrochromic (EC) variable emittance coatings (VEC) for thermal management in space. VECs were built on glass substrates, flexible polyimide (Kapton™) films, and on high resistance silicon wafers. The best VECs were found to modulate mid-infrared emittance from 0.15 to 0.46 on a Kapton film and from 0.24 to 0.48 on a silicon wafer that performs the dual role as both infrared window and substrate. The results of thermal estimations for a two-dimensional plate showed that EC systems with emittance modulation ratio ɛhigh/Vegr low = 3 can be practically used to advantage in providing enhanced thermal control for lightweight structures in space. In addition, EC variable solar reflectance coatings (VSRCs) were built on polyethylene terephthalate (PET) film. The average reflection of the VSRC in a visual spectral range was 63% in the bleached condition and 20% in the colored condition. Thermal analysis shows that a combination of VECs and VSRCs described in this work provides an enhanced range of thermal control for satellites and small space vehicles in the space environment.

  20. Beam-target interaction and intrabeam scattering in the HESR ring. Emittance, momentum resolution and luminosity

    International Nuclear Information System (INIS)

    The beam-target interaction is studied with respect to the transverse and longitudinal emittance growth of the HESR antiproton beam. The transverse emittance growth caused by the small angle Coulomb scattering can be described analytically using the differential cross section of the Coulomb interaction. Similarly, the longitudinal emittance growth caused by the energy loss of the beam can be calculated using the differential cross section of the energy-loss distribution. It is shown that particles with energy losses near the maximum energy loss in a head-on collision with a target electron are lost due to momentum acceptance of the HESR ring. Taking a relative momentum acceptance of about 1 x 10-3 into account yields an order of magnitude smaller growth rate of the mean square momentum deviation. The necessary cooling rates for the High Resolution mode and the High Luminosity mode are deduced assuming that the beam-target interaction is the dominant beam heating process. For comparison the effects of intrabeam scattering are estimated. For electron and stochastic cooling, analytic expressions are quoted in order to evaluate the momentum resolution and cooling rate. The potentialities of electron and stochastic cooling are discussed with respect to the achievable momentum resolution and beam-target overlap. Beam loss rates and average luminosities are evaluated taking the total hadronic cross section, the restricted momentum acceptance of the HESR ring, the large angle Coulomb scattering and the Touschek effect into account. (orig.)

  1. Effects of emitter junction and passive base region on low dose rate effect in bipolar devices

    International Nuclear Information System (INIS)

    Low dose rate effect in bipolar devices consists in the increase of peripheral surface recombination current with dose rate decrease. This is due to the more rapid positive oxide charge and interface trap density build-up as the dose rate becomes lower. High dose rate elevated temperature irradiation is proposed for simulation if the low dose rate effect. In the present we tried to separate the effect of radiation-induced charge in the thick passivation oxide over the emitter junction and passive base regions of npn bipolar transistor. Its goal is to improve bipolar device design for use in space environments and nuclear installations. Three experiments were made during this work. 1. Experiment on radiation-induced charge neutralization (RICN) effect under elevated temperature was performed to show transistor degradation dependence on emitter-base bias. 2. High dose rate elevated and room temperature irradiation of bipolar transistors were performed to separate effects of emitter-junction and passive base regions. 3. Pre- and post- irradiation hydrogen ambient storage was used to investigate its effect on radiation-induced charge build-up over the passive base region. All experiments were performed with npn and pnp transistors. (authors)

  2. Beam-target interaction and intrabeam scattering in the HESR ring. Emittance, momentum resolution and luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Hinterberger, F. [Bonn Univ. (Germany). Inst. fuer Strahlen- und Kernphysik

    2006-02-15

    The beam-target interaction is studied with respect to the transverse and longitudinal emittance growth of the HESR antiproton beam. The transverse emittance growth caused by the small angle Coulomb scattering can be described analytically using the differential cross section of the Coulomb interaction. Similarly, the longitudinal emittance growth caused by the energy loss of the beam can be calculated using the differential cross section of the energy-loss distribution. It is shown that particles with energy losses near the maximum energy loss in a head-on collision with a target electron are lost due to momentum acceptance of the HESR ring. Taking a relative momentum acceptance of about 1 x 10{sup -3} into account yields an order of magnitude smaller growth rate of the mean square momentum deviation. The necessary cooling rates for the High Resolution mode and the High Luminosity mode are deduced assuming that the beam-target interaction is the dominant beam heating process. For comparison the effects of intrabeam scattering are estimated. For electron and stochastic cooling, analytic expressions are quoted in order to evaluate the momentum resolution and cooling rate. The potentialities of electron and stochastic cooling are discussed with respect to the achievable momentum resolution and beam-target overlap. Beam loss rates and average luminosities are evaluated taking the total hadronic cross section, the restricted momentum acceptance of the HESR ring, the large angle Coulomb scattering and the Touschek effect into account. (orig.)

  3. Alpha Particle Emitter Radiolabeled Antibody for Metastatic Cancer: What Can We Learn from Heavy Ion Beam Radiobiology?

    Directory of Open Access Journals (Sweden)

    Hong Song

    2012-06-01

    Full Text Available Alpha-particle emitter labeled monoclonal antibodies are being actively developed for treatment of metastatic cancer due to the high linear energy transfer (LET and the resulting greater biological efficacy of alpha-emitters. Our knowledge of high LET particle radiobiology derives primarily from accelerated heavy ion beam studies. In heavy ion beam therapy of loco-regional tumors, the modulation of steep transition to very high LET peak as the particle approaches the end of its track (known as the Bragg peak enables greater delivery of biologically potent radiation to the deep seated tumors while sparing normal tissues surrounding the tumor with the relatively low LET track segment part of the heavy ion beam. Moreover, fractionation of the heavy ion beam can further enhance the peak-to-plateau relative biological effectiveness (RBE ratio. In contrast, internally delivered alpha particle radiopharmaceutical therapy lack the control of Bragg peak energy deposition and the dose rate is determined by the administered activity, alpha-emitter half-life and biological kinetics of the radiopharmaceutical. The therapeutic ratio of tumor to normal tissue is mainly achieved by tumor specific targeting of the carrier antibody. In this brief overview, we review the radiobiology of high LET radiations learned from ion beam studies and identify the features that are also applicable for the development of alpha-emitter labeled antibodies. The molecular mechanisms underlying DNA double strand break repair response to high LET radiation are also discussed.

  4. Iodine-124: a promising positron emitter for organic PET chemistry.

    Science.gov (United States)

    Koehler, Lena; Gagnon, Katherine; McQuarrie, Steve; Wuest, Frank

    2010-04-01

    The use of radiopharmaceuticals for molecular imaging of biochemical and physiological processes in vivo has evolved into an important diagnostic tool in modern nuclear medicine and medical research. Positron emission tomography (PET) is currently the most sophisticated molecular imaging methodology, mainly due to the unrivalled high sensitivity which allows for the studying of biochemistry in vivo on the molecular level. The most frequently used radionuclides for PET have relatively short half-lives (e.g. 11C: 20.4 min; 18F: 109.8 min) which may limit both the synthesis procedures and the time frame of PET studies. Iodine-124 (124I, t1/2 = 4.2 d) is an alternative long-lived PET radionuclide attracting increasing interest for long term clinical and small animal PET studies. The present review gives a survey on the use of 124I as promising PET radionuclide for molecular imaging. The first part describes the production of 124I. The second part covers basic radiochemistry with 124I focused on the synthesis of 124I-labeled compounds for molecular imaging purposes. The review concludes with a summary and an outlook on the future prospective of using the long-lived positron emitter 124I in the field of organic PET chemistry and molecular imaging. PMID:20428073

  5. Iodine-124: A Promising Positron Emitter for Organic PET Chemistry

    Directory of Open Access Journals (Sweden)

    Lena Koehler

    2010-04-01

    Full Text Available The use of radiopharmaceuticals for molecular imaging of biochemical and physiological processes in vivo has evolved into an important diagnostic tool in modern nuclear medicine and medical research. Positron emission tomography (PET is currently the most sophisticated molecular imaging methodology, mainly due to the unrivalled high sensitivity which allows for the studying of biochemistry in vivo on the molecular level. The most frequently used radionuclides for PET have relatively short half-lives (e.g. 11C: 20.4 min; 18F: 109.8 min which may limit both the synthesis procedures and the time frame of PET studies. Iodine-124 (124I, t1/2 = 4.2 d is an alternative long-lived PET radionuclide attracting increasing interest for long term clinical and small animal PET studies. The present review gives a survey on the use of 124I as promising PET radionuclide for molecular imaging. The first part describes the production of 124I. The second part covers basic radiochemistry with 124I focused on the synthesis of 124I-labeled compounds for molecular imaging purposes. The review concludes with a summary and an outlook on the future prospective of using the long-lived positron emitter 124I in the field of organic PET chemistry and molecular imaging.

  6. Rapid screening methods for beta-emitters in food samples

    International Nuclear Information System (INIS)

    In case of a nuclear emergency, many samples need to be measured in a short time period. Therefore, it is of vital importance to have a quick and reliable (screening)method. Most methods to determine total beta activity are time-consuming because of extensive sample preparation, such as ashing. In this article three different rapid screening methods for beta emitting nuclides in agriculture, livestock and fishery products were tested and compared to each other, and to an accurate but more time consuming reference method. The goal was to find the method with the optimal trade-off between accuracy, speed and minimal detectable activity (MDA). All of the methods rely on liquid scintillation counting (LSC) or Cerenkov counting, and differ mainly in sample preparation. For matrices with little or no colour, the direct LSC-method is the most accurate and fastest option, while for darker coloured samples this method is not suitable because of high colour quenching. For such samples, two additional methods using a microwave digestion during sample preparation, produced good results. - Highlights: • Comparison of rapid screening methods for beta-emitters. • Sample preparation and measurement done within 1.5–7.5 h instead of 56 h. • MDA less than 100 Bq/kg fresh product. • Recoveries for all rapid screening methods higher than 73%

  7. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    CERN Document Server

    Dowell, David H

    2015-01-01

    It is well-known that the electron beam quality required for applications such as FELs and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field's time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  8. A new shipping container for an intense neutron emitter

    International Nuclear Information System (INIS)

    Californium-252 is an intense neutron emitter (2.34 x 1012 n/s·g) used in medicine, research, and industry. The western world's sole source of this rare radioisotope is the Californium Facility at Oak Ridge National Laboratory's Radiochemical Engineering Development Center (REDC). A project has been initiated at the REDC to design a new Type B Californium Shipping Container. This effort is essential for future transportation of californium to meet the needs of users all over the world. The shipping container must meet all requirements for transport by motor freight, air, vessel, and rail, both domestic and foreign. There are unique problems in the design, fabrication, and licensing of a new Type B shipping container that will accommodate up to 60 milligrams of californium-252. One of the first challenges in the design phase of the project is the selection of a material to shield the high neutron flux. The more stringent safety precautions of today's world impel us to consider more exotic materials for such a purpose. The candidate materials must be examined not just for their neutron shielding properties, but also in conjunction with other properties such as thermal and structural requirements to withstand the hypothetical accident conditions. The design and building of such a container is a formidable task requiring much planning. The licensing process, with the complex, interactive federal codes, is a special challenge and may be the biggest on the project in terms of time and money

  9. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    Energy Technology Data Exchange (ETDEWEB)

    Houck, T L; Brown, C G; Ong, M M; Paul, A C; Wargo, P E; Zentler, J M

    2006-08-11

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented.

  10. The first simplest indicator based on LMMT field emitter

    International Nuclear Information System (INIS)

    Full text: Liquid metal multiple tip (LMMT) electron emitter was created by pulling liquid metal (indium gallium eutectic) through holes in a nuclear membrane of polyethylene terephtalate. The track membranes presently employed in selective clean-up filters are obtained by bombarding a film with heavy ions having energy of several tens of megaelectron volts. After irradiation, the film is illuminated by ultraviolet light and subjected to chemical etching. These membranes are produced by cyclotron of Physico-technical Institute. Liquid metal multiple tip field emitters have some advantages in comparison with solid-state field emitters and explosive electron emitters: unlimited life expectancy, large current densities (>100 mA per sq. cm), practically unlimited surface, stable emission in poor vacuum (10-4 Torr). In this work we report about use of LMMT field emitter on the base of polyethylene terephtalate film with 3 μm-diameter holes as the simplest light indicator. The design of the indicator consists of flat accelerating grid and phosphor glass as collecting electrode. The work stability, surface distribution, longlife are discussed in paper. Refs. 2 (author)

  11. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line

    Energy Technology Data Exchange (ETDEWEB)

    Alabau, M.; Faus-Golfe, A.; /Valencia U., IFIC; Alabau, M.; Bambade, P.; Brossard, J.; Le Meur, G.; Rimbault, C.; Touze, F.; /Orsay, LAL; Angal-Kalinin, D.; Jones, J.K.; /Daresbury; Appleby, R.; Scarfe, A.; /Manchester U.; Kuroda, S.; /KEK, Tsukuba; White, G.R.; Woodley, M.; /SLAC; Zimmermann, F.; /CERN

    2011-11-04

    Since several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This longstanding problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experimented by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.

  12. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    International Nuclear Information System (INIS)

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented

  13. Active N(2)O emission from bacterial microbiota of Andisol farmland and characterization of some N(2)O emitters.

    Science.gov (United States)

    Takeda, Hisahaya; Takahashi, Naoki; Hatano, Ryusuke; Hashidoko, Yasuyuki

    2012-08-01

    Andisol in farmland located in Hokkaido, Japan, is known to actively flux nitrous oxide (N(2)O) during the spring to summer seasons. Using a culturing system which mimics farm soils, nitrous oxide (N(2)O) emission potentials of the soils or soil microorganisms were investigated. A total of thirty-three soil samples from the farmland showed high N(2)O production potential, of which the maximum level of N(2)O emission was 3.69 μg per ml of the cultured medium per day (ml(-1) d(-1)) in the assay system. However, only three eubacteria (Leptothrix sp., Paenibacillus sp., and Streptomyces sp.) were isolated as culturable N(2)O emitters among a total of 92 bacterial isolates and 2 fungi obtained from the assayed soil suspensions. N(2)O production from all the isolated N(2)O emitters was more active within a weakly acidic region (pH 4.5-5.0) than neutral regions. However, unlike N(2)O emitters isolated from tropical peat soils, they did not respond to supplemental 0.5% sucrose. In the acetylene inhibition assay for the evaluation of complete denitrification, Leptothrix sp. P3-15D and Streptomyces sp. M2-0C indicated that these culturable N(2)O emitters are not effective denitrifiers but weak N(2)O emitters in the Andisol. Conversely, Rhodococcus sp. that was isolated from the Andisol collected in another season using a KNO(3)-enriched plate, showed 3.2-fold higher N(2)O emission with 10% C(2) H(2). Instead of the culturable bacteria, it is probable that the N(2)O emitters in viable but non-culturable (VBNC) state or obligately anaerobic denitrifiers are the major contributors to N(2)O emission from the vitric Andisol. PMID:22144290

  14. GERLUMPH Data Release 2: 2.5 billion simulated microlensing light curves

    CERN Document Server

    Vernardos, Georgios; Bate, Nicholas F; Croton, Darren; Vohl, Dany

    2015-01-01

    In the upcoming synoptic all--sky survey era of astronomy, thousands of new multiply imaged quasars are expected to be discovered and monitored regularly. Light curves from the images of gravitationally lensed quasars are further affected by superimposed variability due to microlensing. In order to disentangle the microlensing from the intrinsic variability of the light curves, the time delays between the multiple images have to be accurately measured. The resulting microlensing light curves can then be analyzed to reveal information about the background source, such as the size of the quasar accretion disc. In this paper we present the most extensive and coherent collection of simulated microlensing light curves; we have generated $>2.5$ billion light curves using the GERLUMPH high resolution microlensing magnification maps. Our simulations can be used to: train algorithms to measure lensed quasar time delays, plan future monitoring campaigns, and study light curve properties throughout parameter space. Our ...

  15. Exploring the Impact of Galaxy Interactions over Seven Billion Years with CAS

    CERN Document Server

    Miller, Sarah H; Conselice, C; Penner, K; Bell, E; Zheng, X; Papovich, C; Skelton, R; Somerville, R; Rix, H; Barazza, F; Barden, M; Borch, A; Beckwith, S; Caldwell, J; Haeussler, B; Heymans, C; Jahnke, K; McIntosh, D; Meisenheimer, K; Peng, C; Robaina, A; Sanchez, S; Wisotzki, L; Wolf, C

    2008-01-01

    We explore galaxy assembly over the last seven billion years by characterizing "normal" galaxies along the Hubble sequence, against strongly disturbed merging/interacting galaxies with the widely used CAS system of concentration (C), asymmetry (A), and 'clumpiness' (S) parameters, as well as visual classification. We analyze Hubble Space Telescope (HST) ACS images of ~4000 intermediate and high mass (> 10^9 solar masses) galaxies from the GEMS survey, one of the largest HST surveys conducted to date in two filters. We explore the effectiveness of the CAS criteria [A>S and A>~0.35] in separating normal and strongly disturbed galaxies at different redshifts, and quantify the recovery and contamination rate. We also compare the average star formation rate and the cosmic star formation rate density as a function of redshift between normal and interacting systems identified by CAS.

  16. Leveraging Billions of Faces to Overcome Performance Barriers in Unconstrained Face Recognition

    CERN Document Server

    Taigman, Yaniv

    2011-01-01

    We employ the face recognition technology developed in house at face.com to a well accepted benchmark and show that without any tuning we are able to considerably surpass state of the art results. Much of the improvement is concentrated in the high-valued performance point of zero false positive matches, where the obtained recall rate almost doubles the best reported result to date. We discuss the various components and innovations of our system that enable this significant performance gap. These components include extensive utilization of an accurate 3D reconstructed shape model dealing with challenges arising from pose and illumination. In addition, discriminative models based on billions of faces are used in order to overcome aging and facial expression as well as low light and overexposure. Finally, we identify a challenging set of identification queries that might provide useful focus for future research.

  17. SU-E-J-03: A Comprehensive Comparison Between Alpha and Beta Emitters for Cancer Radioimmunotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, C.Y. [University of Sydney, Camperdown, NSW (Australia); Guatelli, S [University of Wollongong, Wollongong, NSW (Australia); Oborn, B [Illawarra Cancer Care Centre, Wollongong, NSW (Australia); Allen, B [University of Western Sydney, Liverpool, NSW (Australia)

    2014-06-01

    Purpose: The purpose of this study is to perform a comprehensive comparison of the therapeutic efficacy and cytotoxicity of alpha and beta emitters for Radioimmunotherapy (RIT). For each stage of cancer development, specific models were built for the separate objectives of RIT to be addressed:a) kill isolated cancer cells in transit in the lymphatic and vascular circulation,b) regress avascular cell clusters,c) regress tumor vasculature and tumors. Methods: Because of the nature of short range, high LET alpha and long energy beta radiation and heterogeneous antigen expression among cancer cells, the microdosimetric approach is essential for the RIT assessment. Geant4 based microdosimetric models are developed for the three different stages of cancer progression: cancer cells, cell clusters and tumors. The energy deposition, specific energy resulted from different source distribution in the three models was calculated separately for 4 alpha emitting radioisotopes ({sup 211}At, {sup 213}Bi, {sup 223}Ra and {sup 225}Ac) and 6 beta emitters ({sup 32}P, {sup 33}P, {sup 67}Cu, {sup 90}Y, {sup 131}I and {sup 177}Lu). The cell survival, therapeutic efficacy and cytotoxicity are determined and compared between alpha and beta emitters. Results: We show that internal targeted alpha radiation has advantages over beta radiation for killing isolated cancer cells, regressing small cell clusters and also solid tumors. Alpha particles have much higher dose specificity and potency than beta particles. They can deposit 3 logs more dose than beta emitters to single cells and solid tumor. Tumor control probability relies on deep penetration of radioisotopes to cancer cell clusters and solid tumors. Conclusion: The results of this study provide a quantitative understanding of the efficacy and cytotoxicity of RIT for each stage of cancer development.

  18. Clinical use of bone-targeting radiopharmaceuticals with focus on alpha-emitters

    Institute of Scientific and Technical Information of China (English)

    Hinrich; A; Wieder; Michael; Lassmann; Martin; S; Allen-Auerbach; Johannes; Czernin; Ken; Herrmann

    2014-01-01

    Various single or multi-modality therapeutic options are available to treat pain of bone metastasis in patients with prostate cancer.Different radionuclides that emitβ-rays such as 153Samarium and 89Strontium and achieve palliation are commercially available.In contrast toβ-emitters,223Radium as a a-emitter has a short path-length.The advantage of the a-emitter is thus a highly localized biological effect that is caused by radiation induced DNA double-strand breaks and subsequent cell killing and/or limited effectiveness of cellular repair mechanisms.Due to the limited range of the a-particles the bone surface to red bone marrow dose ratio is also lower for 223Radium which is expressed in a lower myelotoxicity.The a emitter 223Radium dichloride is the first radiopharmaceutical that significantly prolongslife in castrate resistant prostate cancer patients with wide-spread bone metastatic disease.In a phaseⅢ,randomized,double-blind,placebo-controlled study 921patients with castration-resistant prostate cancer and bone metastases were randomly assigned.The analysis confirmed the 223Radium survival benefit compared to the placebo(median,14.9 mo vs 11.3 mo;P<0.001).In addition,the treatment results in pain palliation and thus,improved quality of life and a delay of skeletal related events.At the same time the toxicity profile of223Radium was favourable.Since May 2013,223Radium dichloride(Xofigo?)is approved by the US Food and Drug Administration.

  19. SU-E-J-03: A Comprehensive Comparison Between Alpha and Beta Emitters for Cancer Radioimmunotherapy

    International Nuclear Information System (INIS)

    Purpose: The purpose of this study is to perform a comprehensive comparison of the therapeutic efficacy and cytotoxicity of alpha and beta emitters for Radioimmunotherapy (RIT). For each stage of cancer development, specific models were built for the separate objectives of RIT to be addressed:a) kill isolated cancer cells in transit in the lymphatic and vascular circulation,b) regress avascular cell clusters,c) regress tumor vasculature and tumors. Methods: Because of the nature of short range, high LET alpha and long energy beta radiation and heterogeneous antigen expression among cancer cells, the microdosimetric approach is essential for the RIT assessment. Geant4 based microdosimetric models are developed for the three different stages of cancer progression: cancer cells, cell clusters and tumors. The energy deposition, specific energy resulted from different source distribution in the three models was calculated separately for 4 alpha emitting radioisotopes (211At, 213Bi, 223Ra and 225Ac) and 6 beta emitters (32P, 33P, 67Cu, 90Y, 131I and 177Lu). The cell survival, therapeutic efficacy and cytotoxicity are determined and compared between alpha and beta emitters. Results: We show that internal targeted alpha radiation has advantages over beta radiation for killing isolated cancer cells, regressing small cell clusters and also solid tumors. Alpha particles have much higher dose specificity and potency than beta particles. They can deposit 3 logs more dose than beta emitters to single cells and solid tumor. Tumor control probability relies on deep penetration of radioisotopes to cancer cell clusters and solid tumors. Conclusion: The results of this study provide a quantitative understanding of the efficacy and cytotoxicity of RIT for each stage of cancer development

  20. A correction for emittance-measurement errors caused by finite slit and collector widths

    International Nuclear Information System (INIS)

    One method of measuring the transverse phase-space distribution of a particle beam is to intercept the beam with a slit and measure the angular distribution of the beam passing through the slit using a parallel-strip collector. Together the finite widths of the slit and each collector strip form an acceptance window in phase space whose size and orientation are determined by the slit width, the strip width, and the slit-collector distance. If a beam is measured using a detector with a finite-size phase-space window, the measured distribution is different from the true distribution. The calculated emittance is larger than the true emittance, and the error depends both on the dimensions of the detector and on the Courant-Snyder parameters of the beam. Specifically, the error gets larger as the beam drifts farther from a waist. This can be important for measurements made on high-brightness beams, since power density considerations require that the beam be intercepted far from a waist. In this paper we calculate the measurement error and we show how the calculated emittance and Courant-Snyder parameters can be corrected for the effects of finite sizes of slit and collector. (Author) 5 figs., 3 refs