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Sample records for electron emitters based

  1. Electron Emitters

    National Research Council Canada - National Science Library

    Tzeng, Yonhua

    2002-01-01

    When two carbon-nanotube coated electrodes are placed at a small distance from each other, electron emission from carbon nanotubes allows a DC or AC electrical current to flow between these two electrodes...

  2. Diamondoid monolayers as electron emitters

    Science.gov (United States)

    Yang, Wanli [El Cerrito, CA; Fabbri, Jason D [San Francisco, CA; Melosh, Nicholas A [Menlo Park, CA; Hussain, Zahid [Orinda, CA; Shen, Zhi-Xun [Stanford, CA

    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.

  3. Low emittance electron storage rings

    Science.gov (United States)

    Levichev, E. B.

    2018-01-01

    Low-emittance electron (positron) beams are essential for synchrotron light sources, linear collider damping rings, and circular Crab Waist colliders. In this review, the principles and methods of emittance minimization are discussed, prospects for developing relativistic electron storage rings with small beam phase volume are assessed, and problems related to emittance minimization are examined together with their possible solutions. The special features and engineering implementation aspects of various facilities are briefly reviewed.

  4. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Li, Kuan-Wei [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Honda, Shin-ichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Lin, Pao-Hung; Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2017-06-01

    Graphical abstract: The pattern design provides a new structure of surface-conduction electron-emitter display (SED). Delta-star shaped vertically aligned CNT (VACNT) arrays with 20o tips can simultaneously provide three emitters to bombard the sides of equilateral triangles pattern of VACNT, which produces numerous secondary electrons and enhance the SED efficiency. - Highlights: • The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. • The vertically aligned CNT (VACNT) arrays with 20° tips of the delta-star arrangement are used as cathodes that easily emit electrons. The cathode pattern simultaneously provides three emitters to bombard the sides of equilateral triangles pattern of VACNT. • The VACNT arrays were covered with magnesium oxide (MgO) nanostructures to promote the surface-conduction electron-emitter display (SED) efficiency (η). • The η was stably maintained in the 75–85% range. The proposed design provides a facile new method for developing SED applications. - Abstract: The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75–85% range. The proposed design provides a facile new method for

  5. High current plasma electron emitter

    International Nuclear Information System (INIS)

    Fiksel, G.; Almagri, A.F.; Craig, D.

    1995-07-01

    A high current plasma electron emitter based on a miniature plasma source has been developed. The emitting plasma is created by a pulsed high current gas discharge. The electron emission current is 1 kA at 300 V at the pulse duration of 10 ms. The prototype injector described in this paper will be used for a 20 kA electrostatic current injection experiment in the Madison Symmetric Torus (MST) reversed-field pinch. The source will be replicated in order to attain this total current requirement. The source has a simple design and has proven very reliable in operation. A high emission current, small size (3.7 cm in diameter), and low impurity generation make the source suitable for a variety of fusion and technological applications

  6. A device for electron gun emittance measurement

    International Nuclear Information System (INIS)

    Aune, B.; Corveller, P.; Jablonka, M.; Joly, J.M.

    1985-05-01

    In order to improve the final emittance of the beam delivered by the ALS electron linac a new gun is going to be installed. To measure its emittance and evaluate the contribution of different factors to emittance growth we have developed an emittance measurement device. We describe the experimental and mathematical procedure we have followed, and give some results of measurements

  7. Phosphorescent rhenium emitters based on two electron-withdrawing diamine ligands: Structure, characterization and electroluminescent performance

    Energy Technology Data Exchange (ETDEWEB)

    Rui, Mei, E-mail: meirui2015@163.com [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Yuhong, Wang [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Yinting, Wang; Na, Zhang [Communication Training Base of The Headquarters of The General Staff, Zhangjiakou 075100, Hebei (China)

    2014-09-15

    In this paper, two diamine ligands having electron-withdrawing oxadiazole group and their corresponding Re(I) complexes were synthesized. Their geometric structure, electronic transition, photophysical property, thermal stability and electrochemical property were discussed in detail. Experimental data suggested that both complexes were promising yellow emitters with suited energy levels and good thermal stability for electroluminescent application. The correlation between emission performance and electron-withdrawing group was analyzed. It was found that electron-withdrawing group favored emission performance improvement. Their electroluminescence performance was also explored. Yellow electroluminescence was observed with maximum brightness of 1743 cd/m{sup 2}. - Highlights: • Oxadiazole derived diamine ligands and their Re(I) complexes were synthesized. • Their characters and properties were analyzed and compared in detail. • Electron-withdrawing group was proved to be positive for PL improvement. • Electroluminescence was obtained with maximum brightness of 1743 cd/m{sup 2}.

  8. Current gain above 10 in sub-10 nm base III-Nitride tunneling hot electron transistors with GaN/AlN emitter

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhichao, E-mail: zcyang.phys@gmail.com; Zhang, Yuewei; Krishnamoorthy, Sriram; Nath, Digbijoy N. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-05-09

    We report on a tunneling hot electron transistor amplifier with common-emitter current gain greater than 10 at a collector current density in excess of 40 kA/cm{sup 2}. The use of a wide-bandgap GaN/AlN (111 nm/2.5 nm) emitter was found to greatly improve injection efficiency of the emitter and reduce cold electron leakage. With an ultra-thin (8 nm) base, 93% of the injected hot electrons were collected, enabling a common-emitter current gain up to 14.5. This work improves understanding of the quasi-ballistic hot electron transport and may impact the development of high speed devices based on unipolar hot electron transport.

  9. Innovative energy efficient low-voltage electron beam emitters

    International Nuclear Information System (INIS)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-01-01

    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

  10. Innovative energy efficient low-voltage electron beam emitters

    Science.gov (United States)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-03-01

    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.

  11. Development of DNA-based radiopharmaceuticals carrying Auger-electron emitters for anti-gene radiotherapy

    International Nuclear Information System (INIS)

    Panyutin, I.G.; Winters, T.A.; Feinendegen, L.E.; Neumann, R.D.

    2000-01-01

    Targeting of radiation damage to specific DNA sequences is the essence of antigene radiotherapy. This technique also provides a tool to study molecular mechanisms of DNA repair on a defined, single radio damaged site. It was achieved such sequence-specific radio damage by combining the highly localized DNA damage produced by the decay of Auger-electron-emitters such as 125 I with the sequence-specific action of triplex-forming oligonucleotides (TFO). TFO complementary to polypurine-polypyrimidine regions of human genes were synthesized and labeled with 125 I-dCTP by the primer extension method. 125 I-TFO were delivered into cells with several delivery systems. In addition, human enzymes capable of supporting DNA single-strand-break repair were isolated and assessed for their role in the repair of this lesion. Also, the mutagenicity and repairability of 125 I-TFO-induced double strand breaks (DSB) were assessed by repair of plasmid possessing a site-specific DSB lesion. Using plasmids containing target polypurine-polypyrimidine tracts, it was obtained the fine structure of sequence-specific DNA breaks produced by decay of 125 I with single-nucleotide resolution. It was showed that the designed 125 I-TFO in nanomolar concentrations could bind to and introduce double-strand breaks into the target sequences in situ, i.e., within isolated nuclei and intact digitonin-permeabilized cells. It was also showed 125 I-TFO-induced DSB to be highly mutagenic lesions resulting in a mutation frequency of nearly 80%, with deletions comprising the majority of mutations. The results obtained demonstrate the ability of 125 I-TFO to target specific sequences in their natural environment - within eukaryotic nucleus. Repair of 125 I-TFO-induced DNA damage should typically result in mutagenic gene inactivation

  12. Emittance measurements of the CLIO electron beam

    Science.gov (United States)

    Chaput, R.; Devanz, G.; Joly, P.; Kergosien, B.; Lesrel, J.

    1997-02-01

    We have designed a setup to measure the transverse emittance at the CLIO accelerator exit, based on the "3 gradients" method. The beam transverse size is measured simply by scanning it with a steering coil across a fixed jaw and recording the transmitted current, at various quadrupole strengths. A code then performs a complete calculation of the emittance using the transfer matrix of the quadrupole instead of the usual classical lens approximation. We have studied the influence of various parameters on the emittance: Magnetic field on the e-gun and the peak current. We have also improved a little the emittance by replacing a mismatched pipe between the buncher and accelerating section to avoid wake-field effects; The resulting improvements of the emittance have led to an increase in the FEL emitted power.

  13. Low emittance thermionic electron guns

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1989-01-01

    The author discusses self-field effects and external field effects for electron guns. He also discusses designs of electron guns and their uses in electron cooling systems and as an injector for electrostatic free electron lasers. He closes by looking at electron guns for linear accelerators. 20 references, 3 figures

  14. Electron emitter pulsed-type cylindrical IEC

    International Nuclear Information System (INIS)

    Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

    1997-01-01

    A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

  15. Manipulating the Electronic Excited State Energies of Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters To Realize Efficient Deep-Blue Emission.

    Science.gov (United States)

    Komatsu, Ryutaro; Ohsawa, Tatsuya; Sasabe, Hisahiro; Nakao, Kohei; Hayasaka, Yuya; Kido, Junji

    2017-02-08

    The development of efficient and robust deep-blue emitters is one of the key issues in organic light-emitting devices (OLEDs) for environmentally friendly, large-area displays or general lighting. As a promising technology that realizes 100% conversion from electrons to photons, thermally activated delayed fluorescence (TADF) emitters have attracted considerable attention. However, only a handful of examples of deep-blue TADF emitters have been reported to date, and the emitters generally show large efficiency roll-off at practical luminance over several hundreds to thousands of cd m -2 , most likely because of the long delayed fluorescent lifetime (τ d ). To overcome this problem, we molecularly manipulated the electronic excited state energies of pyrimidine-based TADF emitters to realize deep-blue emission and reduced τ d . We then systematically investigated the relationships among the chemical structure, properties, and device performances. The resultant novel pyrimidine emitters, called Ac-XMHPMs (X = 1, 2, and 3), contain different numbers of bulky methyl substituents at acceptor moieties, increasing the excited singlet (E S ) and triplet state (E T ) energies. Among them, Ac-3MHPM, with a high E T of 2.95 eV, exhibited a high external quantum efficiency (η ext,max ) of 18% and an η ext of 10% at 100 cd m -2 with Commission Internationale de l'Eclairage chromaticity coordinates of (0.16, 0.15). These efficiencies are among the highest values to date for deep-blue TADF OLEDs. Our molecular design strategy provides fundamental guidance to design novel deep-blue TADF emitters.

  16. Modular low-voltage electron emitters

    International Nuclear Information System (INIS)

    Berejka, Anthony J.

    2005-01-01

    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

  17. Modular low-voltage electron emitters

    Science.gov (United States)

    Berejka, Anthony J.

    2005-12-01

    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.

  18. Emittance measurement for high-brightness electron guns

    International Nuclear Information System (INIS)

    Kobayashi, H.; Kurihara, T.; Sato, I.; Asami, A.; Yamazaki, Y.; Otani, S.; Ishizawa, Y.

    1992-01-01

    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 (La 1-x Ce x )B 6 , 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

  19. Transverse emittance-preserving arc compressor for high-brightness electron beam-based light sources and colliders

    Science.gov (United States)

    Di Mitri, S.; Cornacchia, M.

    2015-03-01

    Bunch length magnetic compression is used in high-brightness linacs driving free-electron lasers (FELs) and particle colliders to increase the peak current of the injected beam. To date, it is performed in dedicated insertions made of few degrees bending magnets and the compression factor is limited by the degradation of the beam transverse emittance owing to emission of coherent synchrotron radiation (CSR). We reformulate the known concept of CSR-driven optics balance for the general case of varying bunch length and demonstrate, through analytical and numerical results, that a 500 pC charge beam can be time-compressed in a periodic 180 deg arc at 2.4 GeV beam energy and lower, by a factor of up to 45, reaching peak currents of up to 2 kA and with a normalized emittance growth at the 0.1 μ \\text{m} rad level. The proposed solution offers new schemes of beam longitudinal gymnastics; an application to an energy recovery linac driving FEL is discussed.

  20. 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

  1. Plasma treatment for producing electron emitters

    Science.gov (United States)

    Coates, Don Mayo; Walter, Kevin Carl

    2001-01-01

    Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

  2. Low emittance lattices for electron storage rings revisited

    International Nuclear Information System (INIS)

    Trbojevic, D.; Courant, E.

    1994-01-01

    Conditions for the lowest possible emittance of the lattice for electron storage rings are obtained by a simplified analytical approach. Examples of electron storage lattices with minimum emittances are presented. A simple graphical presentation in the normalized dispersion space (Floquet's transformation) is used to illustrate the conditions and results

  3. Laser-assisted electron emission from gated field-emitters

    CERN Document Server

    Ishizuka, H; Yokoo, K; Mimura, H; Shimawaki, H; Hosono, A

    2002-01-01

    Enhancement of electron emission by illumination of gated field-emitters was studied using a 100 mW cw YAG laser at a wavelength of 532 nm, intensities up to 10 sup 7 W/m sup 2 and mechanically chopped with a rise time of 4 mu s. When shining an array of 640 silicon emitters, the emission current responded quickly to on-off of the laser. The increase of the emission current was proportional to the basic emission current at low gate voltages, but it was saturated at approx 3 mu A as the basic current approached 100 mu A with the increase of gate voltage. The emission increase was proportional to the square root of laser power at low gate voltages and to the laser power at elevated gate voltages. For 1- and 3-tip silicon emitters, the rise and fall of the current due to on-off of the laser showed a significant time lag. The magnitude of emission increase was independent of the position of laser spot on the emitter base and reached 2 mu A at a basic current of 5 mu A without showing signs of saturation. The mech...

  4. Evaluations of carbon nanotube field emitters for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nakahara, Hitoshi, E-mail: nakahara@nagoya-u.jp [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2009-11-30

    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 2.6x10{sup 9} A/m{sup 2} 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.

  5. Evaluations of carbon nanotube field emitters for electron microscopy

    Science.gov (United States)

    Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

    2009-11-01

    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 2.6×109 A/m 2 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.

  6. 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...... 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...

  7. Device for the radiation centering at electron emitters

    International Nuclear Information System (INIS)

    Panzer, S.; Ardenne, T. von; Jessat, K.; Bahr, G.

    1985-01-01

    The invention has been directed at a device for a simplified and reliable centering of electron beams at electron emitters in particular for welding and thermal surface modifications. The electron beam has been focussed relatively to an electron-optical lens. A movable masked electron detector has been arranged at the electron beam deflection plane. The electron detector is connected with an electronic data evaluation equipment

  8. A compact electron gun using field emitter array

    International Nuclear Information System (INIS)

    Asakawa, M.R.; Ikeda, A.; Miyabe, N.; Yamaguchi, S.; Kusaba, M.; Tsunawaki, Y.

    2008-01-01

    A compact electron gun using field emitter array has been developed. With a simple triode configuration consisting of FEA, mid-electrode and anode electrode, the electron gun produces a parallel beam with a diameter of 0.5 mm. This electron gun is applicable for compact radiation sources such as Cherenkov free-electron lasers

  9. Diamond-based single-photon emitters

    International Nuclear Information System (INIS)

    Aharonovich, I; Castelletto, S; Simpson, D A; Su, C-H; Greentree, A D; Prawer, S

    2011-01-01

    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.

  10. Modified theoretical minimum emittance lattice for an electron storage ring with extreme-low emittance

    Directory of Open Access Journals (Sweden)

    Yi Jiao

    2011-05-01

    Full Text Available In the continuing efforts to reduce the beam emittance of an electron storage ring composed of theoretical minimum emittance (TME lattice, down to a level of several tens of picometers, nonlinear dynamics grows to be a great challenge to the performance of the storage ring because of the strong sextupoles needed to compensate for its large global natural chomaticities coupled with its small average dispersion function. To help in dealing with the challenge of nonlinear optimization, we propose a novel variation of theoretical minimum emittance (TME lattice, named as “modified-TME” lattice, with minimal emittance about 3 times of the exact theoretical minimum, while with more compact layout, lower phase advance per cell, smaller natural chromaticities, and more relaxed optical functions than that in a TME cell, by using horizontally defocusing quadrupole closer to the dipole or simply combined-function dipole with horizontally defocusing gradient. We present approximate scaling formulas to describe the relationships of the design parameters in a modified-TME cell. The applications of modified-TME lattice in the PEP-X storage ring design are illustrated and the proposed lattice appears a good candidate for synchrotron radiation light source with extremely low emittance.

  11. Industrial application of electron sources with plasma emitters

    CERN Document Server

    Belyuk, S I; Rempe, N G

    2001-01-01

    Paper contains a description, operation, design and parameters of electron sources with plasma emitters. One presents examples of application of these sources as part of automated electron-beam welding lines. Paper describes application of such sources for electron-beam deposition of composite powders. Electron-beam deposition is used to rebuild worn out part and to increase strength of new parts of machines and tools. Paper presents some examples of rebuilding part and the advantages gained in this case

  12. Auger electron emitters: Insights gained from in vitro experiments

    International Nuclear Information System (INIS)

    Makrigiorgos, G.; Adelstein, S.J.; Kassis, A.I.

    1990-01-01

    This paper outlines the evolution of the current rationale for research into the biological effects of tissue-incorporated Auger electron emitters. The first section is a brief review of the research conducted by several groups in the last fifteen years. The second section describes the in vitro model used in our studies, dosimetric calculations, experimental techniques and recent findings. The third section focuses on the use of Auger electron emitters as in vitro microprobes for the investigation of the radiosensitivity of distinct subcellular components. Examination of the biological effects of the Auger electron emitter 125 I located in different cellular compartments of a single cell line (V 79 hamster lung fibroblast) verifies that DNA is the critical cell structure for radiation damage and that the sensitive sites are of nanometer dimensions. The data from incorporation of several Auger electron emitters at the same location within DNA suggest that there are no saturation effects from the decay of these isotopes (i.e. all the emitted energy is biologically effective) and provide some insight into which of the numerous physical mechanisms accompanying the Auger decay are most important in causing cell damage. Finally the implications of Auger electron emission for radiotherapy and radiation protection in diagnostic nuclear medicine are detailed and further research possibilities are suggested. (orig.)

  13. Nanodiamond composite as a material for cold electron emitters

    International Nuclear Information System (INIS)

    Arkhipov, A V; Sominski, G G; Uvarov, A A; Gordeev, S K; Korchagina, S B

    2008-01-01

    Characteristics of field-induced electron emission were investigated for one of newly designed all-carbon materials - nanodiamond composite (NDC). The composite is comprised by 4-6 nm diamond grains covered with 0.2-1 nm-thick graphite-like shells that merge at grain junctions and determine such properties as mechanical strength and high electric conductivity. Large number of uniformly distributed sp 3 -sp 2 interfaces allowed to expect enhanced electron emission in electric field. Combination of these features makes NDC a promising material for cold electron emitters in various applications. Experimental testing confirmed high efficiency of electron emission from NDC. In comparison with previousely tested forms of nanocarbon, NDC emitters demonstrated better stabily and tolerance to performance conditions. Unusual activation scenarios and thermal dependencies of emission characteristics observed in experiments with NDC can add new background for explanation of facilitated electron emission from nanocarbons with relatively 'smooth' surface morphology

  14. Nanodiamond composite as a material for cold electron emitters

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, A V; Sominski, G G; Uvarov, A A [St.Petersburg State Polytechnic University, 29 Politchnicheskaya, St.Petersburg, 195251 (Russian Federation); Gordeev, S K; Korchagina, S B [FSUE ' Central Research Institute for Materials' , 8 Paradnaya Street, St.Petersburg, 191014 (Russian Federation)], E-mail: arkhipov@rphf.spbstu.ru

    2008-03-15

    Characteristics of field-induced electron emission were investigated for one of newly designed all-carbon materials - nanodiamond composite (NDC). The composite is comprised by 4-6 nm diamond grains covered with 0.2-1 nm-thick graphite-like shells that merge at grain junctions and determine such properties as mechanical strength and high electric conductivity. Large number of uniformly distributed sp{sup 3}-sp{sup 2} interfaces allowed to expect enhanced electron emission in electric field. Combination of these features makes NDC a promising material for cold electron emitters in various applications. Experimental testing confirmed high efficiency of electron emission from NDC. In comparison with previousely tested forms of nanocarbon, NDC emitters demonstrated better stabily and tolerance to performance conditions. Unusual activation scenarios and thermal dependencies of emission characteristics observed in experiments with NDC can add new background for explanation of facilitated electron emission from nanocarbons with relatively 'smooth' surface morphology.

  15. Emittance growth in laser-driven RF electron guns

    International Nuclear Information System (INIS)

    Kim, K.J.

    1989-01-01

    A simple analysis for the evolution of the electron-beam phase space distribution in laser-driven rf guns is presented. In particular, formulas are derived for the transverse and longitudinal emittances at the exit of the gun. The results are compared and found to agree well with those from simulation. (Author). 9 refs.; 4 figs

  16. RF emittance in a low energy electron linear accelerator

    Science.gov (United States)

    Sanaye Hajari, Sh.; Haghtalab, S.; Shaker, H.; Kelisani, M. Dayyani

    2018-04-01

    Transverse beam dynamics of an 8 MeV low current (10 mA) S-band traveling wave electron linear accelerator has been studied and optimized. The main issue is to limit the beam emittance, mainly induced by the transverse RF forces. The linac is being constructed at Institute for Research in Fundamental Science (IPM), Tehran Iran Labeled as Iran's First Linac, nearly all components of this accelerator are designed and constructed within the country. This paper discusses the RF coupler induced field asymmetry and the corresponding emittance at different focusing levels, introduces a detailed beam dynamics design of a solenoid focusing channel aiming to reduce the emittance growth and studies the solenoid misalignment tolerances. In addition it has been demonstrated that a prebuncher cavity with appropriate parameters can help improving the beam quality in the transverse plane.

  17. Growth rate of non-thermodynamic emittance of intense electron beams

    International Nuclear Information System (INIS)

    Carlsten, B.E.

    1998-01-01

    The nonlinear free-energy concept has been particularly useful in estimating the emittance growth resulting from any excess energy of electron beams in periodic and uniform channels. However, additional emittance growth, that is geometrical rather than thermodynamic in origin, is induced if the particles have different kinetic energies and axial velocities, which is common for mildly relativistic, very intense electron beams. This effect is especially strong if particles lose or gain significant kinetic energy due to the beam's potential depression, as the beam converges and diverges. In this paper we analyze these geometric emittance growth mechanisms for a uniform, continuous, intense electron beam in a focusing transport channel consisting of discrete solenoidal magnets, over distances short enough that the beam does not reach equilibrium. These emittance growth mechanisms are based on the effects of (1) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (2) an axial velocity shear radially along the beam due to the beam's azimuthal motion in the solenoids, and (3) an energy redistribution of the beam as the beam compresses or expands. The geometric emittance growth is compared in magnitude with that resulting from the nonlinear free energy, for the case of a mismatched beam in a uniform channel, and is shown to dominate for certain experimental conditions. Rules for minimizing the emittance along a beamline are outlined. copyright 1998 The American Physical Society

  18. Emittance simulation for a different electron bunch charges with upgraded PITZ setup

    Energy Technology Data Exchange (ETDEWEB)

    Vashchenko, Grygorii [DESY, Platanenallee 6, 15738 Zeuthen (Germany)

    2013-07-01

    The photo injector test facility at DESY, Zeuthen site (PITZ) was invented with an aim to develop, characterize and optimize the electron sources for linac driven free electron lasers like FLASH and European XFEL. As a prerequisite for a successful experimental emittance optimization, emittance dependencies on the majority of linac parameters have to be studied in simulations. Despite that the nominal electron bunch charge for the operation of FLASH and XFEL is 1nC, there is an interest of the community to operate with other bunch charges. Emittance dependencies on such machine parameters like laser spot size on the photo cathode, laser pulse length, gun launching phase, focusing solenoid current and first accelerating structure gradient are simulated for different electron bunch charges. Based on the simulations data the systematic errors caused by detuning of the different machine parameters from their optimum values are estimated.

  19. Emittance Measurements from a Laser Driven Electron Injector

    Energy Technology Data Exchange (ETDEWEB)

    Reis, David A

    2003-07-28

    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 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 {approx} 13 {pi} 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 {pi} mm-mrad.

  20. Electron beam emittance monitor for the SSC

    International Nuclear Information System (INIS)

    Tsyganov, E.; Meinke, R.; Nexsen, W.; Kauffmann, S.; Zinchenko, A.; Taratin, A.

    1993-05-01

    A nondestructive beam profile monitor for the Superconducting Super Collider (SSC) is presented using as a probe a low-energy electron beam interacting with the proton bunch charge. Results using a full Monte Carlo simulation code look promising for the transverse and longitudinal beam profile measurements

  1. Electron Cloud at Low Emittance in CesrTA

    CERN Document Server

    Palmer, Mark; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; Livezey, Jesse; Lyndaker, Aaron; Makita, Junki; McDonald, Michael; Medjidzade, Valeri; Meller, Robert; O'Connell, Tim; Peck, Stuart; Peterson, Daniel; Ramirez, Gabriel; Rendina, Matthew; Revesz, Peter; Rider, Nate; Rice, David; Rubin, David; Sagan, David; Savino, James; Schwartz, Robert; Seeley, Robert; Sexton, James; Shanks, James; Sikora, John; Smith, Eric; Strohman, Charles; Williams, Heather; Antoniou, Fanouria; Calatroni, Sergio; Gasior, Marek; Jones, Owain Rhodri; Papaphilippou, Yannis; Pfingstner, Juergen; Rumolo, Giovanni; Schmickler, Hermann; Taborelli, Mauro; Asner, David; Boon, Laura; Garfinkel, Arthur; Byrd, John; Celata, Christine; Corlett, John; De Santis, Stefano; Furman, Miguel; Jackson, Alan; Kraft, Rick; Munson, Dawn; Penn, Gregory; Plate, David; Venturini, Marco; Carlson, Benjamin; Demma, Theo; Dowd, Rohan; Flanagan, John; Jain, Puneet; Kanazawa, Ken-ichi; Kubo, Kiyoshi; Ohmi, Kazuhito; Sakai, Hiroshi; Shibata, Kyo; Suetsugu, Yusuke; Tobiyama, Makoto; Gonnella, Daniel; Guo, Weiming; Harkay, Katherine; Holtzapple, Robert; Jones, James; Wolski, Andrzej; Kharakh, David; Ng, Johnny; Pivi, Mauro; Wang, Lanfa; Ross, Marc; Tan, Cheng-Yang; Zwaska, Robert; Schachter, Levi; Wilkinson, Eric

    2010-01-01

    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

  2. Low Emittance Guns for the ILC Polarized Electron Beam

    International Nuclear Information System (INIS)

    Clendenin, J. E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R. E.; Maruyama, T.; Miller, R. H.; Wang, J. W.; Zhou, F.

    2007-01-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of ≥200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while ≥500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

  3. Low Emittance Guns for the ILC Polarized Electron Beam

    International Nuclear Information System (INIS)

    Clendenin, J.E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R.E.; Maruyama, T.; Miller, R.H.; Wang, J.W.; Zhou, F.; SLAC

    2006-01-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of (ge)200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while (ge)500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

  4. Improvement of electron emission characteristics of porous silicon emitter by using cathode reduction and electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, He; Wenjiang, Wang, E-mail: wwj@mail.xjtu.edu.cn; Xiaoning, Zhang

    2017-03-31

    Highlights: • An electron emitter based on porous silicon having the strong application potential was prepared in the studying. • A new simple and convenient post-treat technique was proposed to improve the electron emission properties of the PS emitter. • It demonstrated that the improving of the PS morphology and the oxygen distribution is very important to the PS emitter. - Abstract: A new simple and convenient post-treat technique combined the cathode reduction (CR) and electrochemical oxidation (ECO) was proposed to improve the electron emission properties of the surface-emitting cold cathodes based on the porous silicon (PS). It is demonstrated here that by introducing this new technique combined CR and ECO, the emission properties of the diode have been significantly improved than those as-prepared samples. The experimental results showed that the emission current densities and efficiencies of sample treated by CR were 62 μA/cm{sup 2} and 12.10‰, respectively, nearly 2 orders of magnitude higher than those of as-prepared sample. Furthermore, the CR-treated PS emitter shows higher repeatability and stability compared with the as-prepared PS emitter. The scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectrometer (EDS), furier transformed infrared (FTIR) spectroscopy results indicated that the improved mechanism is mainly due to the passivation of the PS, which not only improve the PS morphology by the passivation of the H{sup +} but also improve the uniformity of the oxygen content distribution in the whole PS layer. Therefore, the method combined the CR treatment and ECO is expected to be a valuable technique to enhance the electron emission characteristics of the PS emitter.

  5. Improvement of electron emission characteristics of porous silicon emitter by using cathode reduction and electrochemical oxidation

    International Nuclear Information System (INIS)

    Li, He; Wenjiang, Wang; Xiaoning, Zhang

    2017-01-01

    Highlights: • An electron emitter based on porous silicon having the strong application potential was prepared in the studying. • A new simple and convenient post-treat technique was proposed to improve the electron emission properties of the PS emitter. • It demonstrated that the improving of the PS morphology and the oxygen distribution is very important to the PS emitter. - Abstract: A new simple and convenient post-treat technique combined the cathode reduction (CR) and electrochemical oxidation (ECO) was proposed to improve the electron emission properties of the surface-emitting cold cathodes based on the porous silicon (PS). It is demonstrated here that by introducing this new technique combined CR and ECO, the emission properties of the diode have been significantly improved than those as-prepared samples. The experimental results showed that the emission current densities and efficiencies of sample treated by CR were 62 μA/cm"2 and 12.10‰, respectively, nearly 2 orders of magnitude higher than those of as-prepared sample. Furthermore, the CR-treated PS emitter shows higher repeatability and stability compared with the as-prepared PS emitter. The scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectrometer (EDS), furier transformed infrared (FTIR) spectroscopy results indicated that the improved mechanism is mainly due to the passivation of the PS, which not only improve the PS morphology by the passivation of the H"+ but also improve the uniformity of the oxygen content distribution in the whole PS layer. Therefore, the method combined the CR treatment and ECO is expected to be a valuable technique to enhance the electron emission characteristics of the PS emitter.

  6. Scaling laws with current for equilibrium momentum spread and emittances from intrabeam scattering and electron cooling

    International Nuclear Information System (INIS)

    Hasse, R.W.; Boine-Frankenheim, O.

    2004-01-01

    Based on the theories of Piwinski, Bjorken-Mtingawa and Martini of Coulomb scattering, expressions for the heating rates due to intrabeam scattering were known since a long time. Simplifications by Wei-Parzen and Rao and Piwinski led to analytic approximations which are easily applicable to existing lattices. We use these approximations and also the formulae from thermal equilibration of Struckmeier and equate them to either constant cooling rates from electron cooling or to the Novosibirsk cooling rates for electron cooling to calculate the equilibrium values of the horizontal and vertical emittances and the momentum spread (longitudinal emittance) for typical beams in the ESR or in the HESR. For constant cooling and all approximation formulae the ratio of current to the product of the three emittances remains almost constant. This yields a slope of the momentum spread with current between 0.2 and 0.3, in agreement with experimental data. Using the Novosibirsk cooling rates this slope is much larger

  7. Emittance growth induced by electron cloud in proton storage rings

    CERN Document Server

    Benedetto, Elena; Coppa, G

    2006-01-01

    In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

  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. Fowler Nordheim theory of carbon nanotube based field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Parveen, Shama; Kumar, Avshish [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Samina [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Mushahid, E-mail: mush_reslab@rediffmail.com [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India)

    2017-01-15

    Field emission (FE) phenomena are generally explained in the frame-work of Fowler Nordheim (FN) theory which was given for flat metal surfaces. In this work, an effort has been made to present the field emission mechanism in carbon nanotubes (CNTs) which have tip type geometry at nanoscale. High aspect ratio of CNTs leads to large field enhancement factor and lower operating voltages because the electric field strength in the vicinity of the nanotubes tip can be enhanced by thousand times. The work function of nanostructure by using FN plot has been calculated with reverse engineering. With the help of modified FN equation, an important formula for effective emitting area (active area for emission of electrons) has been derived and employed to calculate the active emitting area for CNT field emitters. Therefore, it is of great interest to present a state of art study on the complete solution of FN equation for CNTs based field emitter displays. This manuscript will also provide a better understanding of calculation of different FE parameters of CNTs field emitters using FN equation.

  11. ROLE OF DIAMOND SECONDARY EMITTERS IN HIGH BRIGHTNESS ELECTRON SOURCES

    International Nuclear Information System (INIS)

    2005-01-01

    In this paper we explore the possibility of using diamond secondary emitter in a high average current electron injector to amplify the current from the photocathode and to isolate the cathode and the injector from each other to increase the life time of the cathode and preserve the performance of the injector. Secondary electron yield of 225 and current density of 0.8 a/cm 2 have been measured in the transmission mode from type 2 a natural diamond. Although the diamond will be heated during normal operation in the injector, calculations indicate that by cryogenically cooling the diamond, the temperature gradient along the diamond can be maintained within the acceptable range. The electron energy and temporal distributions are expected to be narrow from this device resulting in high brightness beams. Plans are underway to measure the SEY in emission mode, fabricate photocathode-diamond capsule and test diamond and capsule in superconducting RF injector

  12. Silicon Based Mid Infrared SiGeSn Heterostructure Emitters and Detectors

    Science.gov (United States)

    2016-05-16

    AFRL-AFOSR-JP-TR-2016-0054 Silicon based mid infrared SiGeSn heterostrcture emitters and detectors Greg Sun UNIVERSITY OF MASSACHUSETTS Final Report... Silicon Based Mid Infrared SiGeSn Heterostructure Emitters and Detectors ” February 10, 2016 Principal Investigator: Greg Sun Engineering...diodes are incompatible with the CMOS process and therefore cannot be easily integrated with Si electronics . The GeSn mid IR detectors developed in

  13. Spectral line shape simulation for electron stark-broadening of ion emitters in plasmas

    International Nuclear Information System (INIS)

    Dufour, Emmanuelle; Calisti, Annette; Talin, Bernard; Gigosos, Marco A.; Gonzalez, Manuel A.; Dufty, Jim W.

    2002-01-01

    Electron broadening for ions in plasmas is investigated in the framework of a simplified semi-classical model involving an ionic emitter imbedded in an electron gas. A regularized Coulomb potential that removes the divergence at short distances is postulated for the ion-electron interaction. Line shape simulations based on Molecular Dynamics for the ion impurity and the electrons, accounting for all the correlations, are reported. Comparisons with line shapes obtained with a quasi-particle model show expected correlation effects. Through an analysis of the results with the line shape code PPP, it is inferred that the correlation effect results mainly from the microfield dynamic properties

  14. Transport and acceleration of low-emittance electron beams

    International Nuclear Information System (INIS)

    Henke, H.

    1989-01-01

    Linear accelerators for colliders and for free-electron lasers require beams with both high brightness and low emittance. Their transport and acceleration is limited by single-particle effects originating from injection jitter, from the unavoidable position jitter of components, and from chromaticity. Collective phenomena, essentially due to wake fields acting within the bunch, are most severe in the case of high-frequency structures, i.e. a small aperture. Whilst, in the past, the transverse wake-field effects were believed to be most serious, we know that they can even be beneficial when inducing a corresponding spread in betatron oscillation either by an energy spread along the bunch or by an RF focusing system acting on the bunch scale. This paper evaluates the different effects by simple analytical means after making use of the smooth focusing approximation and the two-particle model. Numerical simulation results are used for verification. 14 refs., 6 figs., 2 tabs

  15. Novel non-intercepting diagnostic techniques for low-emittance relativistic electron beams

    International Nuclear Information System (INIS)

    Moran, M.J.; Chang, B.

    1988-01-01

    Relativistic electron beams are being generated with emittances low enough that diffraction radiation can be used for beam diagnostics. Techniques based on diffraction radiation can be used to measure the beam transverse momentum distribution and to measure the transverse spatial distribution. The radiation is intense and can be in the visible spectral region where optical diagnostic techniques can be used to maximum advantage. 4 refs. 3 figs

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

    Energy Technology Data Exchange (ETDEWEB)

    Gulliford, Colwyn, E-mail: cg248@cornell.edu; Bartnik, Adam, E-mail: acb20@cornell.edu; Bazarov, Ivan; Dunham, Bruce; Cultrera, Luca [CLASSE, Cornell University, 161 Synchrotron Drive Ithaca, New York 14853-8001 (United States)

    2015-03-02

    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.

  17. Measuring Beam Sizes and Ultra-Small Electron Emittances Using an X-ray Pinhole Camera.

    Science.gov (United States)

    Elleaume, P; Fortgang, C; Penel, C; Tarazona, E

    1995-09-01

    A very simple pinhole camera set-up has been built to diagnose the electron beam emittance of the ESRF. The pinhole is placed in the air next to an Al window. An image is obtained with a CCD camera imaging a fluorescent screen. The emittance is deduced from the size of the image. The relationship between the measured beam size and the electron beam emittance depends upon the lattice functions alpha, beta and eta, the screen resolution, pinhole size and photon beam divergence. The set-up is capable of measuring emittances as low as 5 pm rad and is presently routinely used as both an electron beam imaging device and an emittance diagnostic.

  18. Emittance growth caused by bends in the Los Alamos free-electron laser energy recovery experiment

    International Nuclear Information System (INIS)

    Carlsten, B.E.

    1987-01-01

    Experimentally transporting the beam from the wiggler to the decelerators in the energy recovery experiment (ERX) at the Los Alamos National Laboratory free-electron laser was more difficult than expected because of the large initial emittance in the beam. This emittance was apparently caused in an early 60 0 achromatic bend. To get this beam through subsequent bends without wall interception, the quadrupole focusing had to be changed from the design amount; as a result, the emittance grew further. This paper discusses various mechanisms for this emittance growth in the 60 0 bend, including effects caused by path changes in the bend resulting from wake-field-induced energy changes of particles in the beam and examines emittance filters, ranging from a simple aperture near a beam crossover to more complicated telescope schemes designed to regain the original emittance before the 60 0 bend

  19. Integrated circuits with emitter coupling and their application in nanosecond nuclear electronics

    International Nuclear Information System (INIS)

    Basiladze, S.G.

    1976-01-01

    Principal static and dynamic characteristics are considered of integrated circuits with emitter coupling, as well as problems of signal transmission. Diagrams are given of amplifiers, discriminators, time interval drivers, generators, etc. Systems and units of nanosecond electronics employing integrated circuits with emitter coupling are briefly described

  20. Generation of low-emittance electron beams in electrostatic accelerators for FEL applications

    Science.gov (United States)

    Teng, Chen; Elias, Luis R.

    1995-02-01

    This paper reports results of transverse emittance studies and beam propagation in electrostatic accelerators for free electron laser applications. In particular, we discuss emittance growth analysis of a low current electron beam system consisting of a miniature thermoionic electron gun and a National Electrostatics Accelerator (NEC) tube. The emittance growth phenomenon is discussed in terms of thermal effects in the electron gun cathode and aberrations produced by field gradient changes occurring inside the electron gun and throughout the accelerator tube. A method of reducing aberrations using a magnetic solenoidal field is described. Analysis of electron beam emittance was done with the EGUN code. Beam propagation along the accelerator tube was studied using a cylindrically symmetric beam envelope equation that included beam self-fields and the external accelerator fields which were derived from POISSON simulations.

  1. Generation of low-emittance electron beams in electrostatic accelerators for FEL applications

    International Nuclear Information System (INIS)

    Chen Teng; Central Florida Univ., Orlando, FL; Elias, L.R. R.; Central Florida Univ., Orlando, FL

    1995-01-01

    This paper reports results of transverse emittance studies and beam propagation in electrostatic accelerators for free electron laser applications. In particular, we discuss emittance growth analysis of a low current electron beam system consisting of a miniature thermoionic electron gun and a National Electrostatics Accelerator (NEC) tube. The emittance growth phenomenon is discussed in terms of thermal effects in the electron gun cathode and aberrations produced by field gradient changes occurring inside the electron gun and throughout the accelerator tube. A method of reducing aberrations using a magnetic solenoidal field is described. Analysis of electron beam emittance was done with the EGUN code. Beam propagation along the accelerator tube was studied using a cylindrically symmetric beam envelope equation that included beam self-fields and the external accelerator fields which were derived from POISSON simulations. ((orig.))

  2. Generation of low-emittance electron beams in electrostatic accelerators for FEL applications

    Energy Technology Data Exchange (ETDEWEB)

    Chen Teng [University of Central Florida, Orlando, FL (United States). Center for Research in Electro-Optics and Lasers (CREOL)]|[Central Florida Univ., Orlando, FL (United States). Dept. of Physics; Elias, L.R. R. [University of Central Florida, Orlando, FL (United States). Center for Research in Electro-Optics and Lasers (CREOL)]|[Central Florida Univ., Orlando, FL (United States). Dept. of Physics

    1995-01-30

    This paper reports results of transverse emittance studies and beam propagation in electrostatic accelerators for free electron laser applications. In particular, we discuss emittance growth analysis of a low current electron beam system consisting of a miniature thermoionic electron gun and a National Electrostatics Accelerator (NEC) tube. The emittance growth phenomenon is discussed in terms of thermal effects in the electron gun cathode and aberrations produced by field gradient changes occurring inside the electron gun and throughout the accelerator tube. A method of reducing aberrations using a magnetic solenoidal field is described. Analysis of electron beam emittance was done with the EGUN code. Beam propagation along the accelerator tube was studied using a cylindrically symmetric beam envelope equation that included beam self-fields and the external accelerator fields which were derived from POISSON simulations. ((orig.))

  3. Modulation characteristics of graphene-based thermal emitters

    Science.gov (United States)

    Mahlmeister, Nathan Howard; Lawton, Lorreta Maria; Luxmoore, Isaac John; Nash, Geoffrey Richard

    2016-01-01

    We have investigated the modulation characteristics of the emission from a graphene-based thermal emitter both experimentally and through simulations using finite element method modelling. Measurements were performed on devices containing square multilayer graphene emitting areas, with the devices driven by a pulsed DC drive current over a range of frequencies. Simulations show that the dominant heat path is from the emitter to the underlying substrate, and that the thermal resistance between the graphene and the substrate determines the modulation characteristics. This is confirmed by measurements made on devices in which the emitting area is encapsulated by hexagonal boron nitride.

  4. Field emitters with low turn on electric field based on carbon fibers

    International Nuclear Information System (INIS)

    Wang Qilong; Mu Hui; Zhang Xiaobing; Lei Wei; Wang Jinchan; Zhao Hongping

    2007-01-01

    Field emitters of vertical carbon fibers on a silicon substrate are fabricated by catalytic chemical vapor deposition. After an ageing process of 150 min, field emission measurement of the fibers is carried out in a vacuum chamber with a base pressure of 5.0 x 10 -4 Pa. The experimental results display that field emission performance of the carbon fibers depends strongly on the vacuum level during the experiments. After the field emission measurement, damage to the carbon fiber field emitters is observed from the scanning electron microscopic images

  5. 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...

  6. Investigation of slice emittance using an energy-chirped electron beam in a dispersive section for photo injector characterization at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Ivanisenko, Yevgeniy

    2012-06-15

    This work describes a transverse slice emittance diagnostics with an RMS temporal resolution down to 2 ps that was implemented at the Photo Injector Test facility in Zeuthen (PITZ). The measurements were performed for several bunch charges generated by a laser pulse that has a flat-top temporal profile of 21-22 ps FWHM duration. This diagnostics allows to study the beam projected emittance compensation with a solenoid magnetic field experimentally and therefore contributes to the beam emittance optimization for the needs of short wavelength linac-based FELs in particular. The diagnostics is based upon the usage of electron bunches which have a correlation between the longitudinal position and the momentum of the bunch particles. This property allows to convert the bunch longitudinal distribution into a transverse one in a dipole magnet. A slit with a narrow opening at the dipole exit selects a fraction of the particle ensemble, a slice, which emittance is analyzed at a screen downstream. Slit scan and quadrupole scan techniques can be used to measure the emittance of the slices. In the experiments it was found that the slice emittance values are 5-10% lower than the projected emittance values, indicating a good effectivity of the solenoid compensation. The emittance obtained using quadrupole scan technique has shown different results when compared to slit scan technique due to a beam halo. The observed beam halo in phase space contributes up to 40% of the emittance value while having only 10% of the bunch charge.

  7. Investigation of slice emittance using an energy-chirped electron beam in a dispersive section for photo injector characterization at PITZ

    International Nuclear Information System (INIS)

    Ivanisenko, Yevgeniy

    2012-06-01

    This work describes a transverse slice emittance diagnostics with an RMS temporal resolution down to 2 ps that was implemented at the Photo Injector Test facility in Zeuthen (PITZ). The measurements were performed for several bunch charges generated by a laser pulse that has a flat-top temporal profile of 21-22 ps FWHM duration. This diagnostics allows to study the beam projected emittance compensation with a solenoid magnetic field experimentally and therefore contributes to the beam emittance optimization for the needs of short wavelength linac-based FELs in particular. The diagnostics is based upon the usage of electron bunches which have a correlation between the longitudinal position and the momentum of the bunch particles. This property allows to convert the bunch longitudinal distribution into a transverse one in a dipole magnet. A slit with a narrow opening at the dipole exit selects a fraction of the particle ensemble, a slice, which emittance is analyzed at a screen downstream. Slit scan and quadrupole scan techniques can be used to measure the emittance of the slices. In the experiments it was found that the slice emittance values are 5-10% lower than the projected emittance values, indicating a good effectivity of the solenoid compensation. The emittance obtained using quadrupole scan technique has shown different results when compared to slit scan technique due to a beam halo. The observed beam halo in phase space contributes up to 40% of the emittance value while having only 10% of the bunch charge.

  8. Electron emission from MOS electron emitters with clean and cesium covered gold surface

    DEFF Research Database (Denmark)

    Nielsen, Gunver; Thomsen, Lasse Bjørchmar; Johansson, Martin

    2009-01-01

    MOS (metal-oxide-semiconductor) electron emitters consisting of a Si substrate, a SiO2 tunnel barrier and a Ti (1 nm)/Au(7 nm) top-electrode, with an active area of 1 cm(2) have been produced and studied with surface science techniques under UHV (ultra high vacuum) conditions and their emission...... characteristics have been investigated. It is known, that deposition of an alkali metal on the emitting surface lowers the work function and increases the emission efficiency. For increasing Cs coverages the surface has been characterized by X-ray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS...

  9. Simulation of electron beam formation and transport in a gas-filled electron-optical system with a plasma emitter

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, A. A. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation); Kornilov, S. Yu., E-mail: kornilovsy@gmail.com; Rempe, N. G. [Tomsk State University of Control Systems and Radioelectronics (Russian Federation); Shidlovskiy, S. V. [Tomsk State University (Russian Federation); Shklyaev, V. A. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

    2016-07-15

    The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.

  10. Low-energy electron emitters for targeted radiotherapy of small tumours

    International Nuclear Information System (INIS)

    Bernhardt, Peter; Forssell-Aronsson, Eva; Jacobsson, Lars; Skarnemark, Gunnar

    2001-01-01

    The possibility of using electron emitters to cure a cancer with metastatic spread depends on the energy of the emitted electrons. Electrons with high energy will give a high, absorbed dose to large tumours, but the absorbed dose to small tumours or single tumour cells will be low, because the range of the electrons is too long. The fraction of energy absorbed within the tumour decreases with increasing electron energy and decreasing tumour size. For tumours smaller than 1 g, the tumour-to-normal-tissue mean absorbed dose-rate ratio, TND, will be low, e.g. for 131 I and 90 Y, because of the high energy of the emitted electrons. For radiotherapy of small tumours, radionuclides emitting charged particles with short ranges (a few m u m ) are required. A mathematical model was constructed to evaluate the relation between TND and electron energy, photon-to-electron energy ratio, p/e, and tumour size. Criteria for the selection of suitable radionuclides for the treatment of small tumours were defined based on the results of the TND model. In addition, the possibility of producing such radionuclides and their physical and chemical properties were evaluated. Based on the mathematical model, the energy of the emitted electrons should be = 40 keV for small tumours ( 58m Co, 103m Rh, 119 Sb, 161 Ho, and 189m Os. All of these nuclides by internal transition or electron capture, which yields conversion and Auger electrons, and it should be possible to produce most of them in therapeutic amounts. The five low-energy electron-emitting radionuclides identified may be relevant in the radiation treatment of small tumours, especially if bound to internalizing radiopharmaceuticals

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

    International Nuclear Information System (INIS)

    Lüneburg, S.; Müller, M.; Paarmann, A.; Ernstorfer, R.

    2013-01-01

    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

  12. Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Feist, Armin; Bach, Nora; Rubiano da Silva, Nara; Danz, Thomas; Möller, Marcel; Priebe, Katharina E.; Domröse, Till; Gatzmann, J. Gregor; Rost, Stefan; Schauss, Jakob; Strauch, Stefanie; Bormann, Reiner; Sivis, Murat; Schäfer, Sascha, E-mail: sascha.schaefer@phys.uni-goettingen.de; Ropers, Claus, E-mail: claus.ropers@uni-goettingen.de

    2017-05-15

    We present the development of the first ultrafast transmission electron microscope (UTEM) driven by localized photoemission from a field emitter cathode. We describe the implementation of the instrument, the photoemitter concept and the quantitative electron beam parameters achieved. Establishing a new source for ultrafast TEM, the Göttingen UTEM employs nano-localized linear photoemission from a Schottky emitter, which enables operation with freely tunable temporal structure, from continuous wave to femtosecond pulsed mode. Using this emission mechanism, we achieve record pulse properties in ultrafast electron microscopy of 9 Å focused beam diameter, 200 fs pulse duration and 0.6 eV energy width. We illustrate the possibility to conduct ultrafast imaging, diffraction, holography and spectroscopy with this instrument and also discuss opportunities to harness quantum coherent interactions between intense laser fields and free-electron beams. - Highlights: • First implementation of an ultrafast TEM employing a nanoscale photocathode. • Localized single photon-photoemission from nanoscopic field emitter yields low emittance ultrashort electron pulses. • Electron pulses focused down to ~9 Å, with a duration of 200 fs and an energy width of 0.6 eV are demonstrated. • Quantitative characterization of ultrafast electron gun emittance and brightness. • A range of applications of high coherence ultrashort electron pulses is shown.

  13. Interconnection network architectures based on integrated orbital angular momentum emitters

    Science.gov (United States)

    Scaffardi, Mirco; Zhang, Ning; Malik, Muhammad Nouman; Lazzeri, Emma; Klitis, Charalambos; Lavery, Martin; Sorel, Marc; Bogoni, Antonella

    2018-02-01

    Novel architectures for two-layer interconnection networks based on concentric OAM emitters are presented. A scalability analysis is done in terms of devices characteristics, power budget and optical signal to noise ratio by exploiting experimentally measured parameters. The analysis shows that by exploiting optical amplifications, the proposed interconnection networks can support a number of ports higher than 100. The OAM crosstalk induced-penalty, evaluated through an experimental characterization, do not significantly affect the interconnection network performance.

  14. Low emittance electron beam formation with a 17 GHz RF gun

    Directory of Open Access Journals (Sweden)

    W. J. Brown

    2001-08-01

    Full Text Available We report on electron beam quality measurement results from the Massachusetts Institute of Technology 17 GHz RF gun experiment. The 1.5 cell RF gun uses a solenoid for emittance compensation. It has produced bunch charges up to 0.1 nC with beam energies up to 1 MeV. The normalized rms emittance of the beam after 35 cm of transport from the gun has been measured by a slit technique to be 3π mm mrad for a 50 pC bunch. This agrees well with PARMELA simulations at these beam energies. At the exit of the electron gun, we estimate the emittance to be about 1π mm mrad, which corresponds to a beam brightness of about 80 A/(π mm mrad^{2}. Improved beam quality should be possible with a higher energy output electron beam from the gun.

  15. Plexciton quenching by resonant electron transfer from quantum emitter to metallic nanoantenna.

    Science.gov (United States)

    Marinica, D C; Lourenço-Martins, H; Aizpurua, J; Borisov, A G

    2013-01-01

    Coupling molecular excitons and localized surface plasmons in hybrid nanostructures leads to appealing, tunable optical properties. In this respect, the knowledge about the excitation dynamics of a quantum emitter close to a plasmonic nanoantenna is of importance from fundamental and practical points of view. We address here the effect of the excited electron tunneling from the emitter into a metallic nanoparticle(s) in the optical response. When close to a plasmonic nanoparticle, the excited state localized on a quantum emitter becomes short-lived because of the electronic coupling with metal conduction band states. We show that as a consequence, the characteristic features associated with the quantum emitter disappear from the optical absorption spectrum. Thus, for the hybrid nanostructure studied here and comprising quantum emitter in the narrow gap of a plasmonic dimer nanoantenna, the quantum tunneling might quench the plexcitonic states. Under certain conditions the optical response of the system approaches that of the individual plasmonic dimer. Excitation decay via resonant electron transfer can play an important role in many situations of interest such as in surface-enhanced spectroscopies, photovoltaics, catalysis, or quantum information, among others.

  16. A combined emitter threat assessment method based on ICW-RCM

    Science.gov (United States)

    Zhang, Ying; Wang, Hongwei; Guo, Xiaotao; Wang, Yubing

    2017-08-01

    Considering that the tradition al emitter threat assessment methods are difficult to intuitively reflect the degree of target threaten and the deficiency of real-time and complexity, on the basis of radar chart method(RCM), an algorithm of emitter combined threat assessment based on ICW-RCM (improved combination weighting method, ICW) is proposed. The coarse sorting is integrated with fine sorting in emitter combined threat assessment, sequencing the emitter threat level roughly accordance to radar operation mode, and reducing task priority of the low-threat emitter; On the basis of ICW-RCM, sequencing the same radar operation mode emitter roughly, finally, obtain the results of emitter threat assessment through coarse and fine sorting. Simulation analyses show the correctness and effectiveness of this algorithm. Comparing with classical method of emitter threat assessment based on CW-RCM, the algorithm is visual in image and can work quickly with lower complexity.

  17. Nonlinear electrostatic emittance compensation in kA, fs electron bunches

    International Nuclear Information System (INIS)

    Geer, S.B. van der; Loos, M.J. de; Botman, J.I.M.; Luiten, O.J.; Wiel, M.J. van der

    2002-01-01

    Nonlinear space-charge effects play an important role in emittance growth in the production of kA electron bunches with a bunch length much smaller than the bunch diameter. We propose a scheme employing the radial third-order component of an electrostatic acceleration field, to fully compensate the nonlinear space-charge effects. This results in minimal transverse root-mean-square emittance. The principle is demonstrated using our design simulations of a device for the production of high-quality, high-current, subpicosecond electron bunches using electrostatic acceleration in a 1 GV/m field. Simulations using the GPT code produce a bunch of 100 pC and 73 fs full width at half maximum pulse width, resulting in a peak current of about 1.2 kA at an energy of 2 MeV. The compensation scheme reduces the root-mean-square emittance by 34% to 0.4π mm mrad

  18. Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

    International Nuclear Information System (INIS)

    Kwan, S.; Anderson, D.F.; Zimmerman, J.; Sbarra, C.; Salomon, M.

    1994-10-01

    We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed

  19. Evaluation and application of the low energy electron emitter 161Tb

    International Nuclear Information System (INIS)

    Lehenberger, Silvia M.

    2010-01-01

    The low energy electron emitter 161 Tb was produced n.c.a. in quantities sufficient for therapeutic applications and successfully used for labeling of peptides and antibodies. Furthermore, these compounds have been compared to n.c.a. 177 Lu labeled mAbs via cell experiments, a radionuclide that is already used in clinical nuclear oncology.

  20. 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.

  1. Measurements of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes

    Directory of Open Access Journals (Sweden)

    Yosuke Honda

    2003-09-01

    Full Text Available We present the measurement results of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes. The measurements were carried out with an upgraded laser wire beam profile monitor. The monitor has now a vertical wire as well as a horizontal one and is able to make much faster measurements thanks to an increased effective laser power inside the cavity. The measured emittance shows no large bunch-to-bunch dependence in either the horizontal or vertical directions. The values of the vertical emittance are similar to those obtained in the single-bunch operation. The present results are an important step toward the realization of a high-energy linear collider.

  2. Parametric emittance measurements of electron beams produced by a laser plasma accelerator

    Science.gov (United States)

    Barber, S. K.; van Tilborg, J.; Schroeder, C. B.; Lehe, R.; Tsai, H.-E.; Swanson, K. K.; Steinke, S.; Nakamura, K.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2018-05-01

    Laser plasma accelerators (LPA) offer an exciting possibility to deliver high energy, high brightness electrons beams in drastically smaller distance scales than is typical for conventional accelerators. As such, LPAs draw considerable attention as potential drivers for next generation light sources and for a compact linear collider. In order to asses the viability of an LPA source for a particular application, the brightness of the source should be properly characterized. In this paper, we present charge dependent transverse emittance measurements of LPA sources using both ionization injection and shock induced density down ramp injection, with the latter delivering smaller transverse emittances by a factor of two when controlling for charge density. The single shot emittance method is described in detail with a discussion on limitations related to second order transport effects. The direct role of space charge is explored through a series of simulations and found to be consistent with experimental observations.

  3. Special features of electron sources with CNT field emitter and micro grid

    International Nuclear Information System (INIS)

    Knapp, Wolfram; Schleussner, Detlef

    2005-01-01

    A micro-sized electron source plays an important role for new vacuum triode applications. For these applications, an electron source with CNT field emitter and micro grid for 1 mA was developed and investigated. The miniaturisation of the electron source was achieved by the use of a carbon nanotube (CNT) field emitter and a micro grid, with a distance of only a few micrometers. Because of the threshold field strength for field emission of CNTs being in the range 1-5 V/μm, the grid voltage can be lower than 100 V. In our contribution, we discuss the influence of the micro grid on electron source properties, especially anode-current hysteresis, anode-field penetration through the micro grid and micro-lensing effect

  4. Electron Emitter for small-size Electrodynamic Space Tether using MEMS Technology

    DEFF Research Database (Denmark)

    Fleron, René A. W.; Blanke, Mogens

    2004-01-01

    Adjustment of the orbit of a spacecraft using the forces created by an electro-dynamic space-tether has been shown as a theoretic possibility in recent literature. Practical implementation is being pursued for larger scale missions where a hot filament device controls electron emission...... and the current flowing in the electrodynamic space tether. Applications to small spacecraft, or space debris in the 1–10 kg range, possess difficulties with electron emission technology, as low power emitting devices are needed. This paper addresses the system concepts of a small spacecraft electrodynamic tether...... system with focus on electron emitter design and manufacture using micro-electro-mechanical- system (MEMS) technology. The paper addresses the system concepts of a small size electrodynamic tether mission and shows a novel electron emitter for the 1-2 mA range where altitude can be effectively affected...

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

    International Nuclear Information System (INIS)

    Hiraki, H.; Hiraki, A.; Jiang, N.; Wang, H. X.

    2006-01-01

    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/cm 2 emission current) to emit a 1 mA/cm 2 current at 3 V/μm and 100 mA/cm 2 current at a slightly higher applied voltage. The bright lamps are Mercury-free fluorescence lamps to exhibit brightness of ∼10 5 cd/m 2 with high efficiency of ∼100 lm/w.

  6. Multi-field electron emission pattern of 2D emitter: Illustrated with graphene

    Science.gov (United States)

    Luo, Ma; Li, Zhibing

    2016-11-01

    The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.

  7. A multislit transverse-emittance diagnostic for space-charge-dominated electron beams

    International Nuclear Information System (INIS)

    Piot, P.; Song, J.; Li, R.

    1997-01-01

    Jefferson Lab is developing a 10 MeV injector to provide an 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, the authors 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

  8. Method of measuring the current density distribution and emittance of pulsed electron beams

    International Nuclear Information System (INIS)

    Schilling, H.B.

    1979-07-01

    This method of current density measurement employs an array of many Faraday cups, each cup being terminated by an integrating capacitor. The voltages of the capacitors are subsequently displayed on a scope, thus giving the complete current density distribution with one shot. In the case of emittance measurements, a moveable small-diameter aperture is inserted at some distance in front of the cup array. Typical results with a two-cathode, two-energy electron source are presented. (orig.)

  9. Viability of Using Diamond Field Emitter Array Cathodes in Free Electron Lasers

    Science.gov (United States)

    2010-06-01

    essential component of a field emitter array is the shape of the electric field lines and equipotential lines at the surface of the array. The...BARRIER AND QUANTUM TUNNELING ...........25 B. FIELD ENHANCEMENT AND SURFACE PROTRUSIONS .........26 C. ELECTRIC FIELDS AND ELECTRON TRAVEL...26 Figure 4. Diagram of a protrusion (triangular in shape) from the surface of a cathode. The protrusion is of height h, with a

  10. Emittance growth of an electron beam in a periodic channel due to transfer of longitudinal energy to transverse energy

    International Nuclear Information System (INIS)

    Carlsten, B.E.

    1998-01-01

    Most discussions about emittance growth and halo production for an intense electron beam in a periodic focusing channel assume that the total transverse energy is constant (or, in other words, that the transverse and longitudinal Hamiltonians are separable). Previous analyses that include variations in the total transverse energy are typically based on a transverse-longitudinal coupling that is either from two-dimensional space-charge modes or particle-particle Coulomb collisions. With the space-charge modes, the energy exchange between the transverse and longitudinal directions is periodic, and of constant magnitude. The total energy transfer for the case of the Coulomb collisions is negligible. This limited increase of energy in the transverse direction from these other effects will limit the amount of transverse emittance growth possible. In this paper, the authors investigate a mechanism in which there is a continual transfer of energy from the longitudinal direction to the transverse direction, leading to essentially unlimited potential transverse emittance growth. This mechanism is caused by an asymmetry of the beam's betatron motion within the periodic focusing elements. This analysis is based on thermodynamic principles. This mechanism exists for both solenoids and quadrupole focusing, although only solenoid focusing is studied here

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

    Science.gov (United States)

    Kim, Jae-Woo; Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho

    2014-02-01

    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.

  12. Ultra-low emittance electron beam generation using ionization injection in a plasma beatwave accelerator

    Science.gov (United States)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    Ultra-low emittance beams can be generated using ionization injection of electrons into a wakefield excited by a plasma beatwave accelerator. This all-optical method of electron beam generation uses three laser pulses of different colors. Two long-wavelength laser pulses, with frequency difference equal to the plasma frequency, resonantly drive a plasma wave without fully ionizing a gas. A short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the beating long-wavelength lasers, ionizes a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wakefield. Using the beating of long-wavelength pulses to generate the wakefield enables atomically-bound electrons to remain at low ionization potentials, reducing the required amplitude of the ionization pulse, and, hence, the initial transverse momentum and emittance of the injected electrons. An example is presented using two lines of a CO2 laser to form a plasma beatwave accelerator to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection. Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  13. Transverse-emittance measurements on an S-band photocathode RF electron gun

    CERN Document Server

    Schmerge, J F; Clendenin, J E; Decker, Franz Josef; Dowell, D H; Gierman, S M; Limborg, C G; Murphy, B F

    2002-01-01

    Proposed fourth-generation light sources using SASE FELs to generate short pulse, coherent, X-rays require demonstration of high brightness electron sources. The gun test facility at SLAC was built to test high brightness sources for the proposed linac coherent light source at SLAC. The transverse-emittance measurements are made at nearly 30 MeV by measuring the spot size on a YAG screen using the quadrupole scan technique. The emittance was measured to vary from 1 to 3.5 mm mrad as the charge is increased from 50 to 350 pC using a laser pulse width of 2 ps FWHM. The measurements are in good agreement with simulation results using the LANL version of PARMELA.

  14. Monolayer graphene-insulator-semiconductor emitter for large-area electron lithography

    Science.gov (United States)

    Kirley, Matthew P.; Aloui, Tanouir; Glass, Jeffrey T.

    2017-06-01

    The rapid adoption of nanotechnology in fields as varied as semiconductors, energy, and medicine requires the continual improvement of nanopatterning tools. Lithography is central to this evolving nanotechnology landscape, but current production systems are subject to high costs, low throughput, or low resolution. Herein, we present a solution to these problems with the use of monolayer graphene in a graphene-insulator-semiconductor (GIS) electron emitter device for large-area electron lithography. Our GIS device displayed high emission efficiency (up to 13%) and transferred large patterns (500 × 500 μm) with high fidelity (industries and opening opportunities in nanomanufacturing.

  15. Asymmetrical field emitter

    Science.gov (United States)

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  16. An asymmetric emittance electron source for the GALAXIE dielectric-laser accelerator injector

    Energy Technology Data Exchange (ETDEWEB)

    Valloni, A.; Cahill, A.; Fukusawa, A.; Musumeci, P.; Spataro, B.; Yakub, A.; Rosenzweig, J. B. [Dept. of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90034 (United States); Accelerator Division, Laboratori Nazionali di Frascati (INFN-LNF), Via E. Fermi 40, Frascati (RM) 00044 (Italy); Dept. of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90034 (United States)

    2012-12-21

    The GALAXIE project is a program to develop an all-optical, very high field accelerator and undulator integrated SASE FEL system based on dielectric laser-excited structures that support >GV/m fields. These structures are very wide in one direction to allow adequate charge given beam loading considerations, but also having small (subwavelength) apertures in the narrow direction. Such small vertical dimensions yield strict restrictions on the emittance in this direction, while no such constraint exists in the wide transverse direction. However, the overall beam brightness is restricted by the performance requirements on the FEL. To meet these demands, we are studying a very high field gun with a magnetized cathode, yielding a beam with angular momentum content. This beam is then subject to a skew-quad triplet that splits the emittances; this process is reversed to give a round beam after acceleration. This symmetric emittance beam avoids gain-degrading multiple-transverse-mode operation of the FEL, which also demands that the effects of the angular momentum in the beam be mitigated. In this paper we discuss the RF design of an X-band gun to be operated at {approx}200 MV/m peak field giving a 1 pC magnetized beam with unprecedented brightness. We examine the design of the focusing and skew-quad systems, investigating the associated beam dynamics and efficacy of emittance splitting.

  17. Interface control: A modified rooting technique for enhancing field emission from multiwall carbon nanotube based bulk emitters

    Energy Technology Data Exchange (ETDEWEB)

    Lahiri, Indranil [Nanomaterials and Device Lab, Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States); Choi, Wonbong, E-mail: choiw@fiu.edu [Nanomaterials and Device Lab, Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States)

    2011-08-15

    The unique properties of carbon nanotubes (CNTs) have raised hopes that these materials might find wide application as cold cathodes in various electron sources. The excellent field emission properties shown by CNT-based field emitters has further stimulated this expectation. However, efficient performance of a practical field emitter, which comprises a large number of randomly or regularly oriented CNTs, is restricted primarily due to poor junctions formed between CNTs and substrates. This study is aimed at enhancing the junction performance by way of a modified 'rooting' technique-interface control. In this process, the interface between CNTs and substrate has been tailored with different metals in an attempt to improve the CNT-substrate junction performance. Multiwall carbon nanotubes (MWCNTs) were synthesized on different interface-controlled substrates, i.e. Cu, Al, W, Si and low-temperature co-fired ceramic. All the samples produced mat-type, randomly oriented MWCNT structures. Among the four different substrates studied, MWCNT-based field emitters on Cu substrate demonstrated the best field emission response, in terms of low turn-on field, high emission current, good field enhancement factor and excellent stability in long-term operation. Emitter structures and their field emission behavior were correlated and it was shown that interface control, as an advanced 'rooting' process, plays an important role in determining the emission response from a bulk field emitter.

  18. Interface control: A modified rooting technique for enhancing field emission from multiwall carbon nanotube based bulk emitters

    International Nuclear Information System (INIS)

    Lahiri, Indranil; Choi, Wonbong

    2011-01-01

    The unique properties of carbon nanotubes (CNTs) have raised hopes that these materials might find wide application as cold cathodes in various electron sources. The excellent field emission properties shown by CNT-based field emitters has further stimulated this expectation. However, efficient performance of a practical field emitter, which comprises a large number of randomly or regularly oriented CNTs, is restricted primarily due to poor junctions formed between CNTs and substrates. This study is aimed at enhancing the junction performance by way of a modified 'rooting' technique-interface control. In this process, the interface between CNTs and substrate has been tailored with different metals in an attempt to improve the CNT-substrate junction performance. Multiwall carbon nanotubes (MWCNTs) were synthesized on different interface-controlled substrates, i.e. Cu, Al, W, Si and low-temperature co-fired ceramic. All the samples produced mat-type, randomly oriented MWCNT structures. Among the four different substrates studied, MWCNT-based field emitters on Cu substrate demonstrated the best field emission response, in terms of low turn-on field, high emission current, good field enhancement factor and excellent stability in long-term operation. Emitter structures and their field emission behavior were correlated and it was shown that interface control, as an advanced 'rooting' process, plays an important role in determining the emission response from a bulk field emitter.

  19. Low emittance photoinjectors

    International Nuclear Information System (INIS)

    Ferrario, Massimo

    2001-01-01

    Photon colliders require high charge polarized electron beams with very low normalized emittances, possibly lower than the actual damping rings design goals. Recent analytical and numerical efforts in understanding beam dynamics in RF photoinjectors have raised again the question as to whether the performances of an RF electron gun based injector could be competitive with respect to a damping ring. As a matter of discussion we report in this paper the most recent results concerning low emittance photoinjector designs: the production of polarized electron beams by DC and/or RF guns is illustrated together with space charge compensation techniques and thermal emittance effects. New ideas concerning multi-gun injection system and generation of flat beams by RF gun are also discussed

  20. 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.

  1. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Science.gov (United States)

    Talman, Richard; Malitsky, Nikolay; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004)PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel , Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)NIMAER0168-900210.1016/S0168-9002(00)00729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]). All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance γx on beam width (as controlled by the lattice βx function) at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening , in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001), http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR). (ii) A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the 2004 FEL Conference, pp. 18

  2. Emittance and damping of electrons in the neighborhood of resonance fixed points

    International Nuclear Information System (INIS)

    Crosbie, E.A.

    1993-01-01

    The stable fixed points generated by nonlinear field harmonics in a cyclic lattice define a multiturn stable orbit. The position of the orbit for each turn in each magnet of the lattice determines the betatron tunes and lattice dispersion functions describing the linear motion of charged particles with respect to the stable orbit. Since the position of the fixed points is dependent in part on the central orbit tune, it turns out that the multiturn orbit dispersion function depends to a large extent on the central orbit chromaticity. In particular, the horizontal partition number can be made to vary from values less than zero (horizontal antidamping for electrons) to values greater than three (longitudinal antidamping). The central orbit chromaticity therefore plays a major role in determining the characteristic emittance of an electron beam with respect to the multiturn orbit

  3. Photonic emitters and circuits based on colloidal quantum dot composites

    Science.gov (United States)

    Menon, Vinod M.; Husaini, Saima; Valappil, Nikesh; Luberto, Matthew

    2009-02-01

    We discuss our work on light emitters and photonic circuits realized using colloidal quantum dot composites. Specifically we will report our recent work on flexible microcavity laser, microdisk emitters and integrated active - passive waveguides. The entire microcavity laser structure was realized using spin coating and consisted of an all-polymer distributed Bragg reflector with a poly-vinyl carbazole cavity layer embedded with InGaP/ZnS colloidal quantum dots. These microcavities can be peeled off the substrate yielding a flexible structure that can conform to any shape and whose emission spectra can be mechanically tuned. The microdisk emitters and the integrated waveguide structures were realized using soft lithography and photo-lithography, respectively and were fabricated using a composite consisting of quantum dots embedded in SU8 matrix. Finally, we will discuss the effect of the host matrix on the optical properties of the quantum dots using results of steady-state and time-resolved luminescence measurements. In addition to their specific functionalities, these novel device demonstrations and their development present a low cost alternative to the traditional photonic device fabrication techniques.

  4. Multi-function radar emitter identification based on stochastic syntax-directed translation schema

    OpenAIRE

    Liu, Haijun; Yu, Hongqi; Sun, Zhaolin; Diao, Jietao

    2014-01-01

    To cope with the problem of emitter identification caused by the radar words’ uncertainty of measured multi-function radar emitters, this paper proposes a new identification method based on stochastic syntax-directed translation schema (SSDTS). This method, which is deduced from the syntactic modeling of multi-function radars, considers the probabilities of radar phrases appearance in different radar modes as well as the probabilities of radar word errors occurrence in different radar phrases...

  5. The optoelectronic chameleon - GaN-based light emitters from the UV to green

    Energy Technology Data Exchange (ETDEWEB)

    Kneissl, Michael [Institut fuer Festkoerperphysik, Technische Universitaet Berlin (Germany)

    2008-07-01

    Group III-nitrides have evolved into one of the most versatile and important semiconductor materials for optoelectronic devices. GaN-based blue, green and white light emitting diodes have already entered many parts of everyday life and violet lasers are expected to be following soon. However, considering the extraordinary electronic properties and the wide spectral range that is accessible through nitride materials, it appears that it we have just touched the tip of the iceberg. We discuss some of the new fields of research for InAlGaN materials and devices and review progress in the development of near and deep ultraviolet light emitting diodes, as well as growth and optical properties of InN and indium rich InGaN alloys for emitter in the blue-green spectral range and beyond.

  6. Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

    International Nuclear Information System (INIS)

    Holtzapple, R.L.; Campbell, R.C.; McArdle, K.E.; Miller, M.I.; Totten, M.M.; Tucker, S.L.; Billing, M.G.; Dugan, G.F.; Ramirez, G.A.; Sonnad, K.G.; Williams, H.A.; Flanagan, J.; Palmer, M.A.

    2016-01-01

    Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions

  7. Analysis of Field Emission of Fabricated Nanogap in Pd Strips for Surface Conduction Electron-Emitter Displays

    Science.gov (United States)

    Lo, Hsiang-Yu; Li, Yiming; Tsai, Chih-Hao; Pan, Fu-Ming

    2008-04-01

    We study the field emission (FE) property of a nanometer-scale gap structure in a palladium strip, which was fabricated by hydrogen absorption under high-pressure treatment. A vigorous cracking process could be accompanied by extensive atomic migration during the hydrogen treatment. A three-dimensional finite-difference time-domain particle-in-cell method is adopted to simulate the electron emission in a surface-conduction electron-emitter display (SED) device. Examinations of conducting characteristics, FE efficiency, the local field around the emitter, and the current density on the anode plate with one FE emitter are conducted. The image of a light spot is successfully produced on a phosphor plate, which implies that the explored electrode with nanometer separation possesses a potential SED application. Experimental observation and numerical simulation show that the proposed structure can be used as a surface conduction electron emitter and has a high FE efficiency with low turn-on voltage and a different electron emission mechanism. This study benefits the advanced SED design for a new type of electron source.

  8. Low emittance design of the electron gun and the focusing channel of the Compact Linear Collider drive beam

    Directory of Open Access Journals (Sweden)

    M. Dayyani Kelisani

    2017-04-01

    Full Text Available For the Compact Linear Collider project at CERN, the power for the main linacs is extracted from a drive beam generated from a high current electron source. The design of the electron source and its subsequent focusing channel has a great impact on the beam dynamic considerations of the drive beam. We report the design of a thermionic electron source and the subsequent focusing channels with the goal of production of a high quality beam with a very small emittance.

  9. Characterization of electron bunches from field emitter array cathodes for use in next-generation x-ray free electron lasers

    International Nuclear Information System (INIS)

    Leemann, S. C.

    2007-01-01

    PSI is interested in developing an x-ray free electron laser (X-FEL) as a companion radiation source to the existing Swiss Light Source. In order to achieve radiation wavelengths as low as 1 Α, the X-FEL requires excellent electron beam quality and high beam energy. The energy requirements and thus the size and cost of the project can be reduced considerably if an ultra-low emittance electron source is developed. Therefore PSI has started the Low Emittance Gun Project with the aim to design a novel type of electron source that will deliver an electron beam with unprecedented emittance at high peak currents to the linear accelerator of the proposed X-FEL. A source candidate for such a gun is field emission from cold cathodes. In order to gain first experience with field emission guns, investigate the dynamics of space charge dominated electron beams and to develop diagnostics capable of resolving ultra-low emittances, it was decided to build a 100 keV DC gun test stand. In the scope of this thesis, the test stand has been designed, assembled and commissioned. For the first time, transverse phase space measurements of bunches emitted by field emitter arrays in pulsed DC accelerating fields have been performed. (author)

  10. Effects of pulse-length and emitter area on virtual cathode formation in electron guns

    International Nuclear Information System (INIS)

    Valfells, Agust; Feldman, D.W.; Virgo, M.; O'Shea, P.G.; Lau, Y.Y.

    2002-01-01

    Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads a distinction between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER) [P. G. O'Shea, M. Reiser, R. A. Kishek et al., Nucl. Instrum. Methods Phys. Res. A 464, 646 (2001)] where the goal is to generate pulses that are well-localized in time and space

  11. Initial observations of high-charge, low-emittance electron beams at HIBAF (High Brightness Accelerator FEL)

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.; Feldman, R.B.; Carsten, B.E.; Feldman, D.W.; Sheffield, R.L.; Stein, W.E.; Johnson, W.J.; Thode, L.E.; Bender, S.C.; Busch, G.E.

    1990-01-01

    We report our initial measurements of bright (high-charge, low-emittance) electron beams generated at the Los Alamos High Brightness Accelerator FEL (HIBAF) Facility. Normalized emittance values of less than 50 {pi} mm-mrad for charges ranging from 0.7 to 8.7 nC were obtained for single micropulses at a y-waist and at an energy of 14.7 MeV. These measurements were part of the commissioning campaign on the HIBAF photoelectric injector. Macropulse measurements have also been performed and are compared with PARMELA simulations. 5 refs., 8 figs., 3 tabs.

  12. Tunable, Room Temperature THZ Emitters Based on Nonlinear Photonics

    Science.gov (United States)

    Sinha, Raju

    The Terahertz (1012 Hz) region of the electromagnetic spectrum covers the frequency range from roughly 300 GHz to 10 THz, which is in between the microwave and infrared regimes. The increasing interest in the development of ultra-compact, tunable room temperature Terahertz (THz) emitters with wide-range tunability has stimulated in-depth studies of different mechanisms of THz generation in the past decade due to its various potential applications such as biomedical diagnosis, security screening, chemical identification, life sciences and very high speed wireless communication. Despite the tremendous research and development efforts, all the available state-of-the-art THz emitters suffer from either being large, complex and costly, or operating at low temperatures, lacking tunability, having a very short spectral range and a low output power. Hence, the major objective of this research was to develop simple, inexpensive, compact, room temperature THz sources with wide-range tunability. We investigated THz radiation in a hybrid optical and THz micro-ring resonators system. For the first time, we were able to satisfy the DFG phase matching condition for the above-mentioned THz range in one single device geometry by employing a modal phase matching technique and using two separately designed resonators capable of oscillating at input optical waves and generated THz waves. In chapter 6, we proposed a novel plasmonic antenna geometry – the dimer rod-tapered antenna (DRTA), where we created a hot-spot in the nanogap between the dimer arms with a very large intensity enhancement of 4.1x105 at optical resonant wavelength. Then, we investigated DFG operation in the antenna geometry by incorporating a nonlinear nanodot in the hot-spot of the antenna and achieved continuously tunable enhanced THz radiation across 0.5-10 THz range. In chapter 8, we designed a multi-metallic resonators providing an ultrasharp toroidal response at THz frequency, then fabricated and

  13. Measurement of transverse emittance at the source of spin-polarized electrons at the S-DALINAC

    Energy Technology Data Exchange (ETDEWEB)

    Eckardt, Christian; Barday, Roman; Bonnes, Uwe; Eichhorn, Ralf; Enders, Joachim; Hessler, Christoph; Patalakha, Oleksandr; Platz, Markus; Poltoratska, Yuliya; Rick, Wolfgang [Institut fuer Kernphysik, TU Darmstadt (Germany); Ackermann, Wolfgang; Mueller, Wolfgang F.O.; Steiner, Bastian; Weiland, Thomas [Institut fuer Theorie Elektromagnetischer Felder, TU Darmstadt (Germany)

    2008-07-01

    A new injector concept for 100 keV spin-polarized electrons (SPIN) at the S-DALINAC has been developed. The transverse emittance was measured for beam characterization. The emittance is a quantity concerning the quality of the beam, describing the phase space area. Determination of the emittance requires measurement of the beam profile and knowledge of the focal length of a beam focussing device. A wire scanner unit consisting of two 50 {mu}m diameter tungsten wires is used for the beam-profile measurement. Data analysis is performed by fitting a gaussian model distribution to estimate the 1{sigma} beam radius. Each determined beam width is correlated to the corresponding focal length of a magnetic lens, and a parabola fit is applied to calculate the parameters of the {sigma}-matrix. The square root of the determinant of the {sigma}-matrix defines the emittance. The results of the calculation are presented and the emittance is compared to theoretical estimates.

  14. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Directory of Open Access Journals (Sweden)

    Richard Talman

    2009-01-01

    Full Text Available Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004; R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006, Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes: (i Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000NIMAER0168-900210.1016/S0168-9002(0000729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]. All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance ϵ_{x} on beam width (as controlled by the lattice β_{x} function at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening et al., in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001, http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR. (ii A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the

  15. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    Science.gov (United States)

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  16. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter

    International Nuclear Information System (INIS)

    Vizir, A. V.; Tyunkov, A. V.; Shandrikov, M. V.; Oks, E. M.

    2010-01-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10 9 cm -3 at an operating gas pressure in the vacuum chamber of less than 2x10 -2 Pa. The device features high power efficiency, design simplicity, and compactness.

  17. Growth of GaN-based non- and semipolar heterostructures for high efficiency light emitters

    International Nuclear Information System (INIS)

    Wernicke, Tim

    2010-01-01

    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 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 cathodoluminescence imaging as

  18. Simulation study of electron cloud induced instabilities and emittance growth for the CERN Large Hadron Collider proton beam

    CERN Document Server

    Benedetto, Elena; Schulte, Daniel; Rumolo, Giovanni

    2005-01-01

    The electron cloud may cause transverse single-bunch instabilities of proton beams such as those in the Large Hadron Collider (LHC) and the CERN Super Proton Synchrotron (SPS). We simulate these instabilities and the consequent emittance growth with the code HEADTAIL, which models the turn-by-turn interaction between the cloud and the beam. Recently some new features were added to the code, in particular, electric conducting boundary conditions at the chamber wall, transverse feedback, and variable beta functions. The sensitivity to several numerical parameters has been studied by varying the number of interaction points between the bunch and the cloud, the phase advance between them, and the number of macroparticles used to represent the protons and the electrons. We present simulation results for both LHC at injection and SPS with LHC-type beam, for different electron-cloud density levels, chromaticities, and bunch intensities. Two regimes with qualitatively different emittance growth are observed: above th...

  19. Experimental and numerical investigations of Si-based photonic crystals with ordered Ge quantum dots emitters

    International Nuclear Information System (INIS)

    Jannesari, R.

    2014-01-01

    In recent years quasi-two-dimensional (2D) photonic crystals, also known as photonic crystal slabs, have been the subject of extensive research. The present work is based on photonic crystals where a hexagonal 2D lattice of air holes is etched through a silicon-on-insulator (SOI) slab. Light is guided in the horizontal plane using photonic band-gap properties, and index guiding provides the optical confinement in the third dimension. This work discusses photonic crystal slabs with Ge quantum dots (QDs) as internal sources. Ge quantum dots have luminescence around 1500nm, which is well suited for optical fiber communication in a way that is fully compatible with standard silicon technology. QD emission can be controlled by epitaxial growth on a pre-patterned SOI substrate. In this way the position of the QDs is controlled, as well as their homogeneity and spectral emission range. During this thesis, photonic crystal fabrication techniques together with techniques for the alignment of the photonic crystal holes with the QDs positions were developed. The employed techniques involve electron beam lithography (EBL) and inductively-coupled-plasma reactive ion etching (ICP-RIE). Perfect ordering of the QDs position was achieved by employing these techniques for pit patterning and the subsequent growth of Ge dots using molecular beam epitaxy (MBE). A second EBL step was then used for photonic crystal writing, which needed to be aligned with respect to the pit pattern with a precision of about ± 30nm. Micro-photoluminescence spectroscopy was used for the optical characterization of the photonic crystal. The emission from ordered quantum dots in different symmetry positions within a unit cell of photonic crystal was theoretically and experimentally investigated and compared with randomly distributed ones. Besides, different geometrical parameters of photonic crystals were studied. The theoretical investigations were mainly based on the rigorous coupled wave analysis (RCWA

  20. Electron field emission characteristics of graphene/carbon nanotubes hybrid field emitter

    International Nuclear Information System (INIS)

    Chen, Leifeng; He, Hong; Yu, Hua; Cao, Yiqi; Lei, Da; Menggen, QiQiGe; Wu, Chaoxing; Hu, Liqin

    2014-01-01

    The graphene (GP) and multi-walled carbon nanotubes (MCNTs) hybrid nanostructure emitter was constructed by a larger scale electrophoretic deposition (EPD) method. The field emission (FE) performance of the hybrid emitter is greatly improved compared with that of only GP or MCNTs emitter. The low turn-on electric field (EF), the low threshold EF and the reliability FE properties are obtained from the hybrid emitter. The better FE properties result from the improved electrical properties. For further enhancement FE of hybrids, Ag Nanoparticles (NPs) were decorated on the hybrids and FE characteristics were also studied. These studies indicate that we can use the hybrid nanostructure to improve conductivity and contact resistance, which results in enhancement of the FE properties

  1. Compact high-efficiency vortex beam emitter based on a silicon photonics micro-ring

    DEFF Research Database (Denmark)

    Li, Shimao; Ding, Yunhong; Guan, Xiaowei

    2018-01-01

    Photonic integrated devices that emit vortex beam carrying orbital angular momentum are becoming key components for multiple applications. Here we propose and demonstrate a high-efficiency vortex beam emitter based on a silicon micro-ring resonator integrated with a metal mirror. Such a compact...

  2. Laser based stripping system for measurement of the transverse emittance of H-beams at the CERN Linac4

    CERN Document Server

    Hofmann, T; Raich, U; Roncarolo, F; Cheymol, B

    2013-01-01

    The new LINAC4 at CERN will accelerate H- particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H- ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H0 atoms from the main H- beam. By imaging these H0 atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material ...

  3. Measurement of concentrations of {gamma}-ray emitters induced in the concrete shield of the JAERI electron linac facility

    Energy Technology Data Exchange (ETDEWEB)

    Endo, Akira; Kawasaki, Katsuya; Kikuchi, Masamitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Harada, Yasunori

    1997-07-01

    Measurement has been made to study distributions of {gamma}-ray emitters induced in the concrete shield of the JAERI electron linac facility. Core boring was carried out at seven positions to take samples from the concrete shield, and {gamma}-ray counting rates and {gamma}-ray spectra of these samples were measured with a NaI(Tl) detector and a Ge semiconductor detector, respectively. The following radionuclides were detected in the concrete samples: {sup 60}Co, {sup 134}Cs, {sup 152}Eu and {sup 154}Eu generated through thermal neutron capture reaction, and {sup 22}Na and {sup 54}Mn generated through nuclear reactions by bremsstrahlung and fast neutrons. The relation between the distributions of {gamma}-ray emitters, as a function of the depth of concrete, and the positions of core boring is discussed. (author)

  4. Double Emittance Exchanger as a Bunch Compressor for the MaRIE XFEL electron beam line at 1GeV

    Energy Technology Data Exchange (ETDEWEB)

    Malyzhenkov, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Northern Illinois Univ., DeKalb, IL (United States); Yampolsky, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carlsten, Bruce Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-22

    We demonstrate an alternative realization of a bunch compressor (specifically the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space.We compare our results with a traditional bunch compressor realized via chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beam line and analyze the eigen-emittances evolution to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR-effects in our scheme resulting in critical emittance growth and introduce alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  5. Photoelectron linear accelerator for producing a low emittance polarized electron beam

    Science.gov (United States)

    Yu, David U.; Clendenin, James E.; Kirby, Robert E.

    2004-06-01

    A photoelectron linear accelerator for producing a low emittance polarized electric beam. The accelerator includes a tube having an inner wall, the inner tube wall being coated by a getter material. A portable, or demountable, cathode plug is mounted within said tube, the surface of said cathode having a semiconductor material formed thereon.

  6. Effects of emitter junction and passive base region on low dose rate effect in bipolar devices

    International Nuclear Information System (INIS)

    Pershenkov, V.S.; Cherepko, S.V.; Maslov, V.B.; Belyakov, V.V.; Sogoyan, A.V.; Ulimov, N.; Emelianov, V.V.

    1999-01-01

    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)

  7. Dependence of the modulation response of quantum dot based nanocavity devices on the number of emitters

    DEFF Research Database (Denmark)

    Lorke, Michael; Nielsen, Torben Roland; Mørk, Jesper

    2011-01-01

    A microscopic theory is used to study the dynamical properties of semiconductor quantum dot based nanocavity laser systems. The carrier kinetics and photon populations are determined using a fully quantum mechanical treatment of the light‐matter coupling. In this work, we investigate the dependency...... of the modulation response in such devices on the number of emitters coupled to the cavity mode. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)...

  8. Beam emittance measurement from CERN thermionic guns

    International Nuclear Information System (INIS)

    Kester, O.; Rao, R.; Rinolfi, L.

    1992-01-01

    In the LEP Injector Linacs (LIL) a thermionic gun provides electron beams with different peak intensities at an energy of 80 keV. The beam emittances were estimated from the EGUN programme. Since the gun is of triode type, the main contribution to the emittance comes from the grid. The simulation programme does not model the real geometry by assuming a cylindrical symmetry, while the grid does not have such symmetry. A Gun Test Facility (GTF), allowing emittance measurements, based on the 3-gradients-method was installed. The experimental results are presented. (author) 6 refs.; 6 figs

  9. Laser Based Phosphor Converted Solid State White Light Emitters

    Science.gov (United States)

    Cantore, Michael

    Artificial lighting and as a consequence the ability to be productive when the sun does not shine may be a profound achievement in society that is largely taken for granted. As concerns arise due to our dependence on energy sources with finite lifespan or environmentally negative effects, efforts to reduce energy consumption and create clean renewable alternatives has become highly valued. In the scope of artificial lighting, the use of incandescent lamps has shifted to more efficient light sources. Fluorescent lighting made the first big gains in efficiency over incandescent lamps with peak efficiency for mature designs reaching luminous efficacy of approximately 90 lm/W; more than three times as efficient as an incandescent lamp. Lamps based on light emitting diodes (LEDs) which can produce light at even greater efficiency, color quality and without the potential for hazardous chemical release from lamp failure. There is a significant challenge with LED based light sources. Their peak efficiency occurs at low current densities and then droops as the current density increases. Laser diodes (LDs) do not suffer from decreasing efficiency due to increased current. An alternative solid state light source using LDs has potential to make further gains in efficiency as well as allow novel illuminant designs which may be impractical or even impossible even with LED or other conventional sources. While similar to LEDS, the use of LDs does present new challenges largely due to the increased optical power density which must be accommodated in optics and phosphor materials. Single crystal YAG:Ce has been shown to be capable of enduring this more extreme operating environment while retaining the optical and fluorescing qualities desired for use as a wavelength converter in phosphor converted LD based white emitting systems. The incorporation of this single crystal phosphor in a system with a commercial laser diode with peak wall plug efficiency of 31% resulted in emission of

  10. Improving Defect-Based Quantum Emitters in Silicon Carbide via Inorganic Passivation.

    Science.gov (United States)

    Polking, Mark J; Dibos, Alan M; de Leon, Nathalie P; Park, Hongkun

    2018-01-01

    Defect-based color centers in wide-bandgap crystalline solids are actively being explored for quantum information science, sensing, and imaging. Unfortunately, the luminescent properties of these emitters are frequently degraded by blinking and photobleaching that arise from poorly passivated host crystal surfaces. Here, a new method for stabilizing the photoluminescence and charge state of color centers based on epitaxial growth of an inorganic passivation layer is presented. Specifically, carbon antisite-vacancy pairs (CAV centers) in 4H-SiC, which serve as single-photon emitters at visible wavelengths, are used as a model system to demonstrate the power of this inorganic passivation scheme. Analysis of CAV centers with scanning confocal microscopy indicates a dramatic improvement in photostability and an enhancement in emission after growth of an epitaxial AlN passivation layer. Permanent, spatially selective control of the defect charge state can also be achieved by exploiting the mismatch in spontaneous polarization at the AlN/SiC interface. These results demonstrate that epitaxial inorganic passivation of defect-based quantum emitters provides a new method for enhancing photostability, emission, and charge state stability of these color centers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Characteristics of Transmission-type Microfocus X-ray Tube based-on Carbon Nanotube Field Emitter

    International Nuclear Information System (INIS)

    Heo, Sung Hwan; Ihsan, Aamir; Cho, Sung Oh

    2007-01-01

    A high resolution microfocus x-ray source is widely applied to noninvasive detection for industrial demands, material science and engineering, and to diagnostic study of microbiology and micro-tomography. Carbon nanotube (CNT) is regarded as an excellent electron emitter, which outperforms conventional electron sources in point of brightness. It has been suggested that CNT is used as an electron source of a high resolution x-ray tube according to their low threshold field with atomically sharp geometry, chemically robust structure, and electric conductivity. Several researchers have reported miniaturized x-ray tube based on diode structure and micro x-ray radiography and computed tomography systems using triode types with precise emission control and electrostatic focusing. Especially, a microfocus x-ray source of 30 μm resolution has been demonstrated recently using an elliptical CNT cathode and asymmetrical Eingel lens. However, to increase the spatial resolution of x-ray source, a smaller CNT emitter is desired. Electron focusing optics must be corrected to reduce aberrations. A thin wire tip end can provide a micro-area of CNT substrate, and a magnetic lens and transmission x-ray target are proper to reduce the lens aberration and a focal length. Until now, CNT based microfocus x-ray source with less than 10 um resolution has not been shown. Here we report a microfocus x-ray source with 4.7 μm x-ray focal spot consisted of a conical CNT tip, a single solenoid lens, and a transmission type x-ray target. A magnified x-ray image larger than 230 times was resolved with advantage of microfocused focal spot and transmission x-ray target

  12. An Ultra-Bright Pulsed Electron Beam with Low Longitudinal Emittance

    CERN Document Server

    Zolotorev, Max S; Denes, Peter; Heifets, Samuel; Hussain, Zahid; Lebedev, Gennadi; Lidia, Steven M; Robin, David; Sannibale, Fernando; Schönlein, Robert W; Vogel, Robert; Wan, Weishi

    2005-01-01

    We describe a novel scheme for an electron source in the 10 - 100 eV range with the capability of approaching the brightness quantum-limit and of lowering the effective temperature of the electrons orders of magnitude with respect to existing sources. Such a device can open the way for a wide range of novel applications that utilize angstrom-scale spatial resolution and ?eV-scale energy resolution. Possible examples include electron microscopy, electron holography, and investigations of dynamics on a picosecond time scale using pump-probe techniques. In this paper we describe the concepts for such a source including a complete and consistent set of parameters for the construction of a real device based on the presented scheme.

  13. Phosphorescent Organic Light-Emitting Devices: Working Principle and Iridium Based Emitter Materials

    Directory of Open Access Journals (Sweden)

    Emil J. W. List

    2008-08-01

    Full Text Available Even though organic light-emitting device (OLED technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs, further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this technology. Along these lines, the present work reviews the essentials of OLED technology putting special focus on the general working principle of single and multilayer OLEDs, fluorescent and phosphorescent emitter materials as well as transfer processes in host materials doped with phosphorescent dyes. Moreover, as a prototypical example of phosphorescent emitter materials, a brief discussion of homo- and heteroleptic iridium(III complexes is enclosed concentrating on their synthesis, photophysical properties and approaches for realizing iridium based phosphorescent polymers.

  14. Development of a Laser-based Emittance Monitor for Negative Hydrogen Beams

    CERN Document Server

    AUTHOR|(CDS)2078368; Schmauss, Bernhard; Gibson, Stephen; Boorman, Gary; Bosco, Alessio

    High energy particle accelerators are designed to collide charged particle beams and thus study the collision products. Maximising the collision rate, to generate sufficient statistics for precise measurements of rare processes, is one of the key parameters for optimising the overall collider performance. The CERN Large Hadron Collider (LHC) Injectors Upgrade (LIU) includes the construction of LINAC4, a completely new machine working as a first linear acceleration stage for the LHC beam. By accelerating a negative hydrogen beam (H-) instead of protons, it aims to double the beam brightness via a more efficient transfer to the first circular accelerator and subsequently boost the LHC collision rate. To achieve this, a precise knowledge of the transverse beam characteristics in terms of beam emittance is essential. This thesis work covers the development of a laser-based monitor meant to measure non-destructively the LINAC4 beam transverse profile and emittance. This included the implementation of dif...

  15. Real-time radionuclide identification in γ-emitter mixtures based on spiking neural network

    International Nuclear Information System (INIS)

    Bobin, C.; Bichler, O.; Lourenço, V.; Thiam, C.; Thévenin, M.

    2016-01-01

    Portal radiation monitors dedicated to the prevention of illegal traffic of nuclear materials at international borders need to deliver as fast as possible a radionuclide identification of a potential radiological threat. Spectrometry techniques applied to identify the radionuclides contributing to γ-emitter mixtures are usually performed using off-line spectrum analysis. As an alternative to these usual methods, a real-time processing based on an artificial neural network and Bayes’ rule is proposed for fast radionuclide identification. The validation of this real-time approach was carried out using γ-emitter spectra ( 241 Am, 133 Ba, 207 Bi, 60 Co, 137 Cs) obtained with a high-efficiency well-type NaI(Tl). The first tests showed that the proposed algorithm enables a fast identification of each γ-emitting radionuclide using the information given by the whole spectrum. Based on an iterative process, the on-line analysis only needs low-statistics spectra without energy calibration to identify the nature of a radiological threat. - Highlights: • A fast radionuclide identification algorithm applicable in spectroscopic portal monitors is presented. • The proposed algorithm combines a Bayesian sequential approach and a spiking neural network. • The algorithm was validated using the mixture of γ-emitter spectra provided by a well-type NaI(Tl) detector. • The radionuclide identification process is implemented using the whole γ-spectrum without energy calibration.

  16. Metamaterial-based integrated plasmonic absorber/emitter for solar thermo-photovoltaic systems

    International Nuclear Information System (INIS)

    Wu, Chihhui; Neuner III, Burton; Shvets, Gennady; John, Jeremy; Milder, Andrew; Zollars, Byron; Savoy, Steve

    2012-01-01

    We present the concept of a solar thermo-photovoltaic (STPV) collection system based on a large-area, nanoimprint-patterned film of plasmonic structures acting as an integrated solar absorber/narrow-band thermal emitter (SANTE). The SANTE film concept is based on integrating broad-band solar radiation absorption with selective narrow-band thermal IR radiation which can be efficiently coupled to a photovoltaic (PV) cell for power generation. By employing a low reflectivity refractory metal (e.g., tungsten) as a plasmonic material, we demonstrate that the absorption spectrum of the SANTE film can be designed to be broad-band in the visible range and narrow-band in the infrared range. A detailed balance calculation demonstrates that the total STPV system efficiency exceeds the Shockley–Queisser limit for emitter temperatures above T e = 1200 K, and achieves an efficiency as high as 41% for T e = 2300 K. Emitter temperatures in this range are shown to be achievable under modest sun concentrations (less than 1000 suns) due to the thermal insulation provided by the SANTE film. An experimental demonstration of the wide-angle, frequency-selective absorptivity is presented

  17. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator.

    Science.gov (United States)

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  18. Nitrogen incorporated ultrananocrystalline diamond based field emitter array for a flat-panel x-ray source

    International Nuclear Information System (INIS)

    Posada, Chrystian M.; Grant, Edwin J.; Lee, Hyoung K.; Castaño, Carlos H.; Divan, Ralu; Sumant, Anirudha V.; Rosenmann, Daniel; Stan, Liliana

    2014-01-01

    A field emission based flat-panel transmission x-ray source is being developed as an alternative for medical and industrial imaging. A field emitter array (FEA) prototype based on nitrogen incorporated ultrananocrystalline diamond film has been fabricated to be used as the electron source of this flat panel x-ray source. The FEA prototype was developed using conventional microfabrication techniques. The field emission characteristics of the FEA prototype were evaluated. Results indicated that emission current densities of the order of 6 mA/cm 2 could be obtained at electric fields as low as 10 V/μm to 20 V/μm. During the prototype microfabrication process, issues such as delamination of the extraction gate and poor etching of the SiO 2 insulating layer located between the emitters and the extraction layer were encountered. Consequently, alternative FEA designs were investigated. Experimental and simulation data from the first FEA prototype were compared and the results were used to evaluate the performance of alternative single and double gate designs that would yield better field emission characteristics compared to the first FEA prototype. The best simulation results are obtained for the double gate FEA design, when the diameter of the collimator gate is around 2.6 times the diameter of the extraction gate

  19. Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Treado, Colleen J.; /Massachusetts U., Amherst

    2012-09-07

    The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

  20. Emittance preservation

    Energy Technology Data Exchange (ETDEWEB)

    Kain, V; Arduini, G; Goddard, B; Holzer, B J; Jowett, J M; Meddahi, M; Mertens, T; Roncarolo, F; Schaumann, M; Versteegen, R; Wenninger, J [European Organization for Nuclear Research, Geneva (Switzerland)

    2012-07-01

    Emittance measurements during the LHC proton run 2011 indicated a blow-up of 20 % to 30 % from LHC injection to collisions. This presentation will show the emittance preservation throughout the different parts of the LHC cycle and discuss the current limitations on emittance determination. An overview of emittance preservation through the injector complex as function of bunch intensity will also be given. Possible sources for the observed blow-up and required tests in 2012 will be presented. Possible improvements of emittance diagnostics and analysis tools for 2012 will be shown.

  1. The low-energy β(-) and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy.

    Science.gov (United States)

    Lehenberger, Silvia; Barkhausen, Christoph; Cohrs, Susan; Fischer, Eliane; Grünberg, Jürgen; Hohn, Alexander; Köster, Ulli; Schibli, Roger; Türler, Andreas; Zhernosekov, Konstantin

    2011-08-01

    The low-energy β(-) emitter (161)Tb is very similar to (177)Lu with respect to half-life, beta energy and chemical properties. However, (161)Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to (177)Lu. It also emits low-energy photons that are useful for gamma camera imaging. The (160)Gd(n,γ)(161)Gd→(161)Tb production route was used to produce (161)Tb by neutron irradiation of massive (160)Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) (161)Tb from the bulk of the (160)Gd target and from its stable decay product (161)Dy. (161)Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. (177)Lu. A (161)Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Up to 15 GBq of (161)Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available (161)Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The (161)Tb obtained was of the quality required to prepare (161)Tb-DOTA-Tyr3-octreotate. We were able to produce (161)Tb in n.c.a. form by irradiating highly enriched (160)Gd targets; it can be obtained in the quantity and quality required for the preparation of (161)Tb-labeled therapeutic agents. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Nanowires-based light emitters on thermally and electrically conductive substrates and of making same

    KAUST Repository

    Ooi, Boon S.; Zhao, Chao; Ng, Tien Khee

    2017-01-01

    Elemental or compound semiconductors on metal substrates and methods of growing them are provided. The methods can include the steps of: (i) providing a metal substrate; (ii) adding an interlayer on a surface of the metal substrate, and (iii) growing semiconductor nanowires on the interlayer using a semiconductor epitaxy growth system to form the elemental or compound semiconductor. The method can include direct growth of high quality group III-V and group III-N based materials in the form of nanowires and nanowires-based devices on metal substrates. The nanowires on all- metal scheme greatly simplifies the fabrication process of nanowires based high power light emitters.

  3. Nanowires-based light emitters on thermally and electrically conductive substrates and of making same

    KAUST Repository

    Ooi, Boon S.

    2017-04-27

    Elemental or compound semiconductors on metal substrates and methods of growing them are provided. The methods can include the steps of: (i) providing a metal substrate; (ii) adding an interlayer on a surface of the metal substrate, and (iii) growing semiconductor nanowires on the interlayer using a semiconductor epitaxy growth system to form the elemental or compound semiconductor. The method can include direct growth of high quality group III-V and group III-N based materials in the form of nanowires and nanowires-based devices on metal substrates. The nanowires on all- metal scheme greatly simplifies the fabrication process of nanowires based high power light emitters.

  4. Generating femtosecond X-ray pulses using an emittance-spoiling foil in free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y., E-mail: ding@slac.stanford.edu; Coffee, R.; Decker, F.-J.; Emma, P.; Field, C.; Huang, Z.; Krejcik, P.; Krzywinski, J.; Loos, H.; Lutman, A.; Marinelli, A.; Maxwell, T. J.; Turner, J. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Behrens, C. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg (Germany); Helml, W. [Technische Universität München, James-Franck-Straße 1, 85748 Garching (Germany)

    2015-11-09

    Generation of femtosecond to sub-femtosecond pulses is attracting much attention in X-ray free-electron laser user community. One method is to use a slotted, emittance-spoiling foil which was proposed before (P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004)) and has been widely used at the Linac Coherent Light Source. Direct experimental characterization of the slotted-foil performance was previously unfeasible due to a lack of appropriate diagnostics. With a recently installed X-band radio-frequency transverse deflector, we are able to characterize the electron bunch spoiling effect and X-ray pulse when using the slotted foil. We show that few-femtosecond X-ray pulses are generated with flexible control of the single-pulse duration or double-pulse separation with comparison to the theoretical model.

  5. Emitter signal separation method based on multi-level digital channelization

    Science.gov (United States)

    Han, Xun; Ping, Yifan; Wang, Sujun; Feng, Ying; Kuang, Yin; Yang, Xinquan

    2018-02-01

    To solve the problem of emitter separation under complex electromagnetic environment, a signal separation method based on multi-level digital channelization is proposed in this paper. A two-level structure which can divide signal into different channel is designed first, after that, the peaks of different channels are tracked using the track filter and the coincident signals in time domain are separated in time-frequency domain. Finally, the time domain waveforms of different signals are acquired by reverse transformation. The validness of the proposed method is proved by experiment.

  6. Improvement of Control System Based on Labview for Beam Emittance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Il; Kim, Jae-Ha; Kwon, Hyeok-Jung; Kim, Han-Sung; Lee, Seok-Geun; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

    2016-10-15

    Some ion sources have been developing at KOMAC. It is important to measure the beam properties to characterize the ion sources such as beam emittance. An electric sweep scanner (ESS) was used to measure the beam distribution in phase space. For performance of ESS, it consists of control system based on NI PXI devices and GUI (graphic user interface) based on Labview. In this paper, a control system with algorism applied reliable sequence for data acquisition is presented. In a sequence with 1 Hz of repetition rate, in case of time 6 s and interval 0.2 V on panel, DC output voltage increases with interval of 0.2 V from -3.6 V to + 3.6 V every 6 seconds. Total period is 216 second. In this case, 6 files are saved in every step. But first one of 6 could not be used because of unreliable signal with variation of DC output voltage. The control system based on Labview was developed for beam emittance measurement. And it was improved by the modification of algorism and the use of external tools applied global variable. In Future, the control system will be used in other ion sources of KOMAC.

  7. Effects of electron blocking and hole trapping of the red guest emitter materials on hybrid white organic light emitting diodes

    International Nuclear Information System (INIS)

    Hong, Lin-Ann; Vu, Hoang-Tuan; Juang, Fuh-Shyang; Lai, Yun-Jr; Yeh, Pei-Hsun; Tsai, Yu-Sheng

    2013-01-01

    Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm 2 , and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39)

  8. Effects of electron blocking and hole trapping of the red guest emitter materials on hybrid white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Lin-Ann; Vu, Hoang-Tuan [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Juang, Fuh-Shyang, E-mail: fsjuang@seed.net.tw [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Lai, Yun-Jr [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Yeh, Pei-Hsun [Raystar Optronics, Inc., 5F No. 25, Keya Rd. Daya Township, Taichung County, Taiwan (China); Tsai, Yu-Sheng [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China)

    2013-10-01

    Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm{sup 2}, and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39)

  9. A Single RF Emitter-Based Indoor Navigation Method for Autonomous Service Robots

    Directory of Open Access Journals (Sweden)

    Tyrone Sherwin

    2018-02-01

    Full Text Available Location-aware services are one of the key elements of modern intelligent applications. Numerous real-world applications such as factory automation, indoor delivery, and even search and rescue scenarios require autonomous robots to have the ability to navigate in an unknown environment and reach mobile targets with minimal or no prior infrastructure deployment. This research investigates and proposes a novel approach of dynamic target localisation using a single RF emitter, which will be used as the basis of allowing autonomous robots to navigate towards and reach a target. Through the use of multiple directional antennae, Received Signal Strength (RSS is compared to determine the most probable direction of the targeted emitter, which is combined with the distance estimates to improve the localisation performance. The accuracy of the position estimate is further improved using a particle filter to mitigate the fluctuating nature of real-time RSS data. Based on the direction information, a motion control algorithm is proposed, using Simultaneous Localisation and Mapping (SLAM and A* path planning to enable navigation through unknown complex environments. A number of navigation scenarios were developed in the context of factory automation applications to demonstrate and evaluate the functionality and performance of the proposed system.

  10. A Single RF Emitter-Based Indoor Navigation Method for Autonomous Service Robots.

    Science.gov (United States)

    Sherwin, Tyrone; Easte, Mikala; Chen, Andrew Tzer-Yeu; Wang, Kevin I-Kai; Dai, Wenbin

    2018-02-14

    Location-aware services are one of the key elements of modern intelligent applications. Numerous real-world applications such as factory automation, indoor delivery, and even search and rescue scenarios require autonomous robots to have the ability to navigate in an unknown environment and reach mobile targets with minimal or no prior infrastructure deployment. This research investigates and proposes a novel approach of dynamic target localisation using a single RF emitter, which will be used as the basis of allowing autonomous robots to navigate towards and reach a target. Through the use of multiple directional antennae, Received Signal Strength (RSS) is compared to determine the most probable direction of the targeted emitter, which is combined with the distance estimates to improve the localisation performance. The accuracy of the position estimate is further improved using a particle filter to mitigate the fluctuating nature of real-time RSS data. Based on the direction information, a motion control algorithm is proposed, using Simultaneous Localisation and Mapping (SLAM) and A* path planning to enable navigation through unknown complex environments. A number of navigation scenarios were developed in the context of factory automation applications to demonstrate and evaluate the functionality and performance of the proposed system.

  11. Electron beam and rf characterization of a low-emittance X-band photoinjector

    Directory of Open Access Journals (Sweden)

    D. J. Gibson

    2001-09-01

    Full Text Available Detailed experimental studies of the first operation of an X-band (8.547 GHz rf photoinjector are reported. The rf characteristics of the device are first described, as well as the tuning technique used to ensure operation of the 11/2-cell rf gun in the balanced π-mode. The characterization of the photoelectron beam produced by the rf gun includes: measurements of the bunch charge as a function of the laser injection phase, yielding information about the quantum efficiency of the Cu photocathode ( 2×10^{-5} for a surface field of 100 MV/m; measurements of the beam energy (1.5–2 MeV and relative energy spread ( Δγ/γ_{0}=1.8±0.2% using a magnetic spectrometer; measurements of the beam 90% normalized emittance, which is found to be ɛ_{n}=1.65π mm mrad for a charge of 25 pC; and measurements of the bunch duration ( <2 ps. Coherent synchrotron radiation experiments at Ku-band and Ka-band confirm the extremely short duration of the photoelectron bunch and a peak power scaling quadratically with the bunch charge.

  12. A Time-Space Domain Information Fusion Method for Specific Emitter Identification Based on Dempster-Shafer Evidence Theory.

    Science.gov (United States)

    Jiang, Wen; Cao, Ying; Yang, Lin; He, Zichang

    2017-08-28

    Specific emitter identification plays an important role in contemporary military affairs. However, most of the existing specific emitter identification methods haven't taken into account the processing of uncertain information. Therefore, this paper proposes a time-space domain information fusion method based on Dempster-Shafer evidence theory, which has the ability to deal with uncertain information in the process of specific emitter identification. In this paper, radars will generate a group of evidence respectively based on the information they obtained, and our main task is to fuse the multiple groups of evidence to get a reasonable result. Within the framework of recursive centralized fusion model, the proposed method incorporates a correlation coefficient, which measures the relevance between evidence and a quantum mechanical approach, which is based on the parameters of radar itself. The simulation results of an illustrative example demonstrate that the proposed method can effectively deal with uncertain information and get a reasonable recognition result.

  13. Highly efficient deep-blue organic light emitting diode with a carbazole based fluorescent emitter

    Science.gov (United States)

    Sahoo, Snehasis; Dubey, Deepak Kumar; Singh, Meenu; Joseph, Vellaichamy; Thomas, K. R. Justin; Jou, Jwo-Huei

    2018-04-01

    High efficiency deep-blue emission is essential to realize energy-saving, high-quality display and lighting applications. We demonstrate here a deep-blue organic light emitting diode using a novel carbazole based fluorescent emitter 7-[4-(diphenylamino)phenyl]-9-(2-ethylhexyl)-9H-carbazole-2-carbonitrile (JV234). The solution processed resultant device shows a maximum luminance above 1,750 cd m-2 and CIE coordinates (0.15,0.06) with a 1.3 lm W-1 power efficiency, 2.0 cd A-1 current efficiency, and 4.1% external quantum efficiency at 100 cd m-2. The resulting deep-blue emission enables a greater than 100% color saturation. The high efficiency may be attributed to the effective host-to-guest energy transfer, suitable device architecture facilitating balanced carrier injection and low doping concentration preventing efficiency roll-off caused by concentration quenching.

  14. Paper based electronics platform

    KAUST Repository

    Nassar, Joanna Mohammad; Sevilla, Galo Andres Torres; Hussain, Muhammad Mustafa

    2017-01-01

    A flexible and non-functionalized low cost paper-based electronic system platform fabricated from common paper, such as paper based sensors, and methods of producing paper based sensors, and methods of sensing using the paper based sensors

  15. Highly efficient and stable white organic light emitting diode base on double recombination zones of phosphorescent blue/orange emitters.

    Science.gov (United States)

    Lee, Seok Jae; Koo, Ja Ryong; Lim, Dong Hwan; Park, Hye Rim; Kim, Young Kwan; Ha, Yunkyoung

    2011-08-01

    We demonstrated efficient and stable white phosphorescent organic light-emitting diodes (OLEDs) with double-emitting layers (D-EMLs), which were comprised of two emissive layers with a hole transport-type host of N,N'-dicarbazolyl-3,5-benzene (mCP) and a electron transport-type host of 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) with blue/orange emitters, respectively. We fabricated two type white devices with single emitting layer (S-EML) and D-EML of orange emitter, maintaining double recombination zone of blue emitter. In addition, the device architecture was developed to confine excitons inside the D-EMLs and to manage triplet excitons by controlling the charge injection. As a result, light-emitting performances of white OLED with D-EMLs were improved and showed the steady CIE coordinates compared to that with S-EML of orange emitter, which demonstrated the maximum luminous efficiency and external quantum efficiency were 21.38 cd/A and 11.09%. It also showed the stable white emission with CIE(x,y) coordinates from (x = 0.36, y = 0.37) at 6 V to (x = 0.33, y = 0.38) at 12 V.

  16. Experimental Development of Low-emittance Field-emission Electron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Lueangaranwong, A. [Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Buzzard, C. [Northern Illinois Univ., DeKalb, IL (United States); Divan, R. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Korampally, V. [Northern Illinois Univ., DeKalb, IL (United States); Piot, P. [Northern Illinois Univ., DeKalb, IL (United States). Northern Illinois Center for Accelerator & Detector Development; Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-10-10

    Field emission electron sources are capable of extreme brightness when excited by static or time-dependent electro- magnetic fields. We are currently developing a cathode test stand operating in DC mode with possibility to trigger the emission using ultra-short (~ 100-fs) laser pulses. This contribution describes the status of an experiment to investigate field-emission using cathodes under development at NIU in collaboration with the Argonne’s Center for Nanoscale Materials.

  17. Development of low emittance high brightness electron beams and rf accelerating structures

    International Nuclear Information System (INIS)

    Pellegrini, C.

    1991-01-01

    The main goals of this project were the construction of an S-band RF photoinjector for the production of a high brightness electron beam, and the development of a new type of RF accelerator structure; the Plane wave transformer. By the end of October 1991 the photoinjector had been built, its RF characteristics had been measured at low power, and an initial test of the gun at high RF power had been done. The Plane Wave Transformer had also been built and tested at lower power. In both cases the results obtained are mostly in agreement with the expected and calculated behavior

  18. Hybrid Radar Emitter Recognition Based on Rough k-Means Classifier and Relevance Vector Machine

    Science.gov (United States)

    Yang, Zhutian; Wu, Zhilu; Yin, Zhendong; Quan, Taifan; Sun, Hongjian

    2013-01-01

    Due to the increasing complexity of electromagnetic signals, there exists a significant challenge for recognizing radar emitter signals. In this paper, a hybrid recognition approach is presented that classifies radar emitter signals by exploiting the different separability of samples. The proposed approach comprises two steps, namely the primary signal recognition and the advanced signal recognition. In the former step, a novel rough k-means classifier, which comprises three regions, i.e., certain area, rough area and uncertain area, is proposed to cluster the samples of radar emitter signals. In the latter step, the samples within the rough boundary are used to train the relevance vector machine (RVM). Then RVM is used to recognize the samples in the uncertain area; therefore, the classification accuracy is improved. Simulation results show that, for recognizing radar emitter signals, the proposed hybrid recognition approach is more accurate, and presents lower computational complexity than traditional approaches. PMID:23344380

  19. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    CERN Document Server

    Talman, Richard; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004); N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using trafic4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)] and elegant [M. Borland, Argonne National Laboratory...

  20. Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using {sup 125}I, an Auger electron emitter

    Energy Technology Data Exchange (ETDEWEB)

    Gardette, M.; Papon, J.; Bonnet, M.; Labarre, P.; Miot-Noirault, E.; Madelmont, J. C.; Chezal, J. M.; Moins, N. [UMR 990, INSERM, Universite d' Auvergne, Clermont-Ferrand (France); Desbois, N. [EA 3660, Universite de Bourgogne, Dijon (France); Wu, T. D.; Guerquin-Kern, J. L. [U 759 INSERM, Institute Curie, Orsay (France)

    2013-06-01

    The full text of the publication follows. The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodo-benzamides or analogs are known to possess specific affinity for melanoma tissue. New hetero-aromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using {sup 125}I, Auger electrons emitter which gives high-energetic localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with {sup 125}I, the two compounds induced in vitro a significant radiotoxicity on B16F0 melanoma cells. The acridine compound, ICF01040, appeared more radio toxic than the acridone compound, ICF01035. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with ICF01035, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. Nevertheless, an important radiotoxicity was measured for the two compounds while the nuclear accumulation was low. Indeed, even if nuclear localization remains the main target sensitive to Auger electrons, the cell membrane remains sensitive to {sup 125}I decays. So, these compounds may induce secondary toxic effects of irradiation, such as membrane lipid damage. Conducted to current experiments are evaluate such hypothesis. Taken together, these results suggest that ICF01040 is a better candidate for application in targeted radionuclide therapy using {sup 125}I. The next step will be in vivo evaluation, where high tumoral vectorization gives

  1. Synthesis, characterization, photophysics and electroluminescence based on a series of pyran-containing emitters

    Energy Technology Data Exchange (ETDEWEB)

    Yang Lifen [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Guan Min [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Bian Zuqiang [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China)]. E-mail: bianzq@pku.edu.cn; Xie Junqi [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Chen Tianpeng [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Huang Chunhui [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China)]. E-mail: chhuang@pku.edu.cn

    2006-04-03

    Four unsymmetric as well as symmetric carbazole or oxadiazole modified pyran-containing compounds have been synthesized and characterized. These compounds are 4-(dicyanomethylene)-2-methyl-6-(4-(carbazolo-9-yl)phenyl)-4H-pyran (10), 4-(dicyanomethylene)-2,6-bis(4-(carbazolo-9-yl)phenyl)-4H-pyran (11), 4-(dicyanomethylene)-2-methyl-6-(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl)-4 H-pyran (12), and 4-(dicyanomethylene)-2,6-bis(4-tert-phenyl)-1,3, 4-oxdiazole-4-phenyl-4H-pyran (13). Photoluminescent measurements indicated that their maximal emissions can be tuned from 543 to 590 nm in acetone solution. Electroluminescent studies based on these compounds as dopants resulted in greenish yellow light emission. It was found that the device based on the bis-condensed symmetric compound (11) with the configuration of indium tin oxide / Copper (II) phthalocyanine (5 nm) / N,N'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine (40 nm) / compound (11) : tris-(8-quinolinolato)aluminium (Alq{sub 3}) (1%) (30 nm) / 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (5 nm) / Alq{sub 3} (40 nm) / Mg : Ag (9 : 1) (200 nm) / Ag (80 nm) has achieved the highest luminance (6869 cd/m{sup 2}) and efficiency (1.32 lm/W and 2.52 cd/A) among the four emitters.

  2. 135La as an auger-electron emitter for targeted internal radiotherapy

    DEFF Research Database (Denmark)

    Fonslet, Jesper; Lee, Boon Quan; Tran, Thuy A.

    2018-01-01

    Introduction: 135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, imaging characteristics, and dosimetry related to 135La therapy. Methods and Results: 135La was produced by 16.5 Me....... The generated Auger spectrum was used to recalculate cellular S-factors. Conclusion: 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy. ....... recovered > 98 % of the 135La with an effective molar activity of 70 ±20 GBq/µmol. To better assess cellular and organ dosimetry of this nuclide, we have recalculated the X-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade...

  3. 135La as an Auger-electron emitter for targeted internal radiotherapy

    Science.gov (United States)

    Fonslet, J.; Lee, B. Q.; Tran, T. A.; Siragusa, M.; Jensen, M.; Kibédi, T.; E Stuchbery, A.; Severin, G. W.

    2018-01-01

    135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, and dosimetry related to 135La therapy. 135La was produced by 16.5 MeV proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407  ±  19 MBq µA-1 (saturation activity), and the radionuclidic purity was 98% at 20 h post irradiation. Chemical separation recovered  >  98 % of the 135La with an effective molar activity of 70  ±  20 GBq µmol-1. To better assess cellular and organ dosimetry of this nuclide, we have calculated the x-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade. The generated Auger spectrum was used to calculate cellular S-factors. 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy.

  4. Multichannel all–optical switch based on a thin slab of resonant two–level emitters

    Directory of Open Access Journals (Sweden)

    Malikov Ramil

    2017-01-01

    Full Text Available We discuss the possibility of using a thin layer of inhomogeneously broadened resonant emitters as a multichannel all–optical switch. Switching time from the lower stable branch of the system's bistable characteristics to the upper one and vice versa, which determines the speed of operation of a bistable device, is studied.

  5. Microcontroller based motion control interface unit for double slit type beam emittance monitor for H- ion source

    International Nuclear Information System (INIS)

    Holikatti, A.C.; Jain, Rahul; Karnewar, A.K.; Sonawane, B.B.; Maurya, N.K.; Puntambekar, T.A.

    2015-01-01

    The Indian Spallation Neutron Source (ISNS), proposed to be developed at RRCAT, will use a 1 GeV H - linac and an accumulator ring to produce high flux of pulsed neutrons via spallation process. The development activity of front end of 1H - linac for ISNS is under progress at RRCAT, for which a pulsed H - ion source of 50 keV energy, 30 mA current with pulse width of 500 μs has been developed at RRCAT. In this paper, we present the design and development of a microcontroller based motion control interface unit for double slit type beam emittance monitor for the H - ion source. This is an interceptive type of beam diagnostic device, which is used for the quantitative measurement of transverse emittance and beam intensity profile

  6. Measured emittance dependence on injection method in laser plasma accelerators

    Science.gov (United States)

    Barber, Samuel; van Tilborg, Jeroen; Schroeder, Carl; Lehe, Remi; Tsai, Hai-En; Swanson, Kelly; Steinke, Sven; Nakamura, Kei; Geddes, Cameron; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    The success of many laser plasma accelerator (LPA) based applications relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot transverse emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock induced density down-ramp injection. Notably, the measurements reveal that ionization injection results in significantly higher emittance. With the down-ramp injection configuration, emittances less than 1 micron at spectral charge densities up to 2 pC/MeV were measured. This work was supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the NSF under Grant No. PHY-1415596, by the U.S. DOE NNSA, DNN R&D (NA22), and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  7. Shielding in ungated field emitter arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harris, J. R. [U.S. Navy Reserve, Navy Operational Support Center New Orleans, New Orleans, Louisiana 70143 (United States); Jensen, K. L. [Code 6854, Naval Research Laboratory, Washington, D.C. 20375 (United States); Shiffler, D. A. [Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, New Mexico 87117 (United States); Petillo, J. J. [Leidos, Billerica, Massachusetts 01821 (United States)

    2015-05-18

    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 10{sup 2}–10{sup 4} 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.

  8. Hybrid white organic light-emitting devices based on phosphorescent iridium-benzotriazole orange-red and fluorescent blue emitters

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhen-Yuan, E-mail: xiazhenyuan@hotmail.com [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Su, Jian-Hua [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Chang, Chi-Sheng; Chen, Chin H. [Display Institute, Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu, Taiwan 300 (China)

    2013-03-15

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange-red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N{sup 1},C{sup 3}] iridium acetylacetonate, Ir(TBT){sub 2}(acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1 Prime ;4 Prime ,1 Double-Prime ]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT){sub 2}(acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N Prime -(4,4 Prime -(1E,1 Prime E)-2,2 Prime -(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange-red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy){sub 3} ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: Black-Right-Pointing-Pointer An iridium-based orange-red phosphor Ir(TBT){sub 2}(acac) was applied in hybrid white OLEDs. Black-Right-Pointing-Pointer Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. Black-Right-Pointing-Pointer Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  9. Hybrid white organic light-emitting devices based on phosphorescent iridium–benzotriazole orange–red and fluorescent blue emitters

    International Nuclear Information System (INIS)

    Xia, Zhen-Yuan; Su, Jian-Hua; Chang, Chi-Sheng; Chen, Chin H.

    2013-01-01

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange–red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N 1 ,C 3 ] iridium acetylacetonate, Ir(TBT) 2 (acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1′;4′,1″]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT) 2 (acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N′-(4,4′-(1E,1′E)-2,2′-(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange–red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy) 3 ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: ► An iridium-based orange–red phosphor Ir(TBT) 2 (acac) was applied in hybrid white OLEDs. ► Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. ► Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  10. FACET Emittance Growth

    Energy Technology Data Exchange (ETDEWEB)

    Frederico, J; Hogan, M.J.; Nosochkov, Y.; Litos, M.D.; Raubenheimer, T.; /SLAC

    2011-04-05

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to {approx}20 {micro}m long and {approx}10 {micro}m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.

  11. FACET Emittance Growth

    International Nuclear Information System (INIS)

    Frederico, Joel

    2011-01-01

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to ∼20 (micro)m long and ∼10 (micro)m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.

  12. Oxadiazole-Based Highly Efficient Bipolar Fluorescent Emitters for Organic Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Qiong Wu

    2018-04-01

    Full Text Available In this study, a series of bipolar fluorescence emitters named 2DPAc-OXD, DPAc-OXD, 2PTZ-OXD and PTZ-OXD were designed and synthesized with excellent yields. The characterization of materials was investigated by using nuclear magnetic resonance (NMR (1H, 13C, mass spectrometry and thermogravimetric analysis (TGA. To investigate device efficiencies, two different OLED devices (Device 1, Device 2 were fabricated with two different host materials (Bepp2, DPEPO. The Device 2 with 2PTZ-OXD as fluorescent emitter exhibited excellent power and current efficiencies of 6.88 Lm/W and 10.10 cd/A, respectively. The external quantum efficiency of 2PTZ-OXD was around 3.99% for Device 2. The overall device properties of phenothiazine donor were better than acridine derivatives.

  13. Stationary scanning x-ray source based on carbon nanotube field emitters

    International Nuclear Information System (INIS)

    Zhang, J.; Yang, G.; Cheng, Y.; Gao, B.; Qiu, Q.; Lee, Y.Z.; Lu, J.P.; Zhou, O.

    2005-01-01

    We report a field emission x-ray source that can generate a scanning x-ray beam to image an object from multiple projection angles without mechanical motion. The key component of the device is a gated carbon nanotube field emission cathode with an array of electron emitting pixels that are individually addressable via a metal-oxide-semiconductor field effect transistor-based electronic circuit. The characteristics of this x-ray source are measured and its imaging capability is demonstrated. The device can potentially lead to a fast data acquisition rate for laminography and tomosynthesis with a simplified experimental setup

  14. Deep-UV Emitters and Detectors Based on Lattice-Matched Cubic Oxide Semiconductors (4.2 Optoelectronics)

    Science.gov (United States)

    2015-05-14

    calculated   by   dividing   photo-­‐‑ generated  current  by  the  optical  power  spectrum  of  the   lamp .    A   UV ...the optimized parameters for growth. Efforts led to significant increases in solar?blind detector responsivity (up to 0.1 A/W) with sub-­ nanoamp...Aug-2014 Approved for Public Release; Distribution Unlimited Final Report: Deep- UV Emitters and Detectors Based on Lattice- Matched Cubic Oxide

  15. 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

  16. Recent advances in carbon nanotube-based electronics

    International Nuclear Information System (INIS)

    Sharma, Prithu; Ahuja, Prerit

    2008-01-01

    CNT-electronics is a field involving synthesis of carbon nanotubes-based novel electronic circuits, comparable to the size of molecules, the practically fundamental size possible. It has brought a new paradigm in science as it has enabled scientists to increase the device integration density tremendously, hence achieving better efficiency and speed. Here we review the state-of-art current research on the applications of CNTs in electronics and present recent results outlining their potential along with illustrating some current concerns in the research field. Unconventional projects such as CNT-based biological sensors, transistors, field emitters, integrated circuits, etc. are taking CNT-based electronics to its extremes. The field holds a promise for mass production of high speed and efficient electronic devices. However, the chemical complexity, reproducibility and other factors make the field a challenging one, which need to be addressed before the field realizes its true potential

  17. Graphene field emitters: A review of fabrication, characterization and properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Leifeng, E-mail: chlf@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yu, Hu; Zhong, Jiasong; Song, Lihui [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Jun, E-mail: wujun@hdu.edu.cn [Institute of Electron Device & Application, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018 (China); Su, Weitao [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-06-15

    Highlights: • The preparation, characterization and field emission properties for Gs are reviewed. • The review provides an updated progress on design and construction of Gs field emitters. • The review offers fundamental insights into understanding and design of Gs emitters. • The review can broach the subject and inspire readers in field of Gs based emitters. - Abstract: Graphenes are beneficial to electrons field emission due to its high aspect ratio, high carrier density, the larger carrier mobility, excellent electrical and thermal conductivity, excellent mechanical strength and chemical stability. In recent years, graphene or reduced oxide graphene field emitters have been successfully constructed by various methods such as chemical vapor deposition, chemical exfoliation, electrophoretic deposition, screen-printing and chemical synthesis methods. Graphene emitters are tried to construct in distribution with some angles or vertical orientation with respect to the substrate surface. The vertical alignment of graphene sheets or edges arrays can facilitate efficient electron emission from the atomically thick sheets. Therefore they have even more a low turn-on and threshold-field electronic field, high field enhancement factor, high current stability and high luminance. In this review, we shortly survey and discuss recent research progress in graphene field emission properties with particular an emphasis on their preparing method, characterization and applications in devices especially for vertical graphene and single layer graphene, also including their challenges and future prospects.

  18. DVD Based Electronic Pulser

    International Nuclear Information System (INIS)

    Morris, Scott J.; Pratt, Rick M.; Hughes, Michael A.; Kouzes, Richard T.; Pitts, W K.; Robinson, Eric E.

    2005-01-01

    This paper describes the design, construction, and testing of a DVD based electronic pulser system (DVDEPS). Such a device is used to generate pulse streams for simulation of both gamma and neutron detector systems. The DVDEPS reproduces a random pulse stream of a full HPGe spectrum as well as a digital pulse stream representing the output of a neutron multiplicity detector. The exchangeable DVD media contains over an hour of data for both detector systems and can contain an arbitrary gamma spectrum and neutron pulse stream. The data is written to the DVD using a desktop computer program from either actual or simulated spectra. The targeted use of the DVDEPS is authentication or validation of monitoring equipment for non-proliferation purposes, but it is also of general use whenever a complex data stream is required. The DVD based pulser combines the storage capacity and simplicity of DVD technology with commonly available electronic components to build a relatively inexpensive yet highly capable testing instrument

  19. Nanodiamond Emitters of Single Photons

    Directory of Open Access Journals (Sweden)

    Vlasov I.I.

    2015-01-01

    Full Text Available Luminescence properties of single color centers were studied in nanodiamonds of different origin. It was found that single photon emitters could be realized even in molecularsized diamond (less than 2 nm capable of housing stable luminescent center “silicon-vacancy.” First results on incorporation of single-photon emitters based on luminescent nanodiamonds in plasmonic nanoantennas to enhance the photon count rate and directionality, diminish the fluorescence decay time, and provide polarization selectivity are presented.

  20. Paper based electronics platform

    KAUST Repository

    Nassar, Joanna Mohammad

    2017-07-20

    A flexible and non-functionalized low cost paper-based electronic system platform fabricated from common paper, such as paper based sensors, and methods of producing paper based sensors, and methods of sensing using the paper based sensors are provided. A method of producing a paper based sensor can include the steps of: a) providing a conventional paper product to serve as a substrate for the sensor or as an active material for the sensor or both, the paper product not further treated or functionalized; and b) applying a sensing element to the paper substrate, the sensing element selected from the group consisting of a conductive material, the conductive material providing contacts and interconnects, sensitive material film that exhibits sensitivity to pH levels, a compressible and/or porous material disposed between a pair of opposed conductive elements, or a combination of two of more said sensing elements. The method of sensing can further include measuring, using the sensing element, a change in resistance, a change in voltage, a change in current, a change in capacitance, or a combination of any two or more thereof.

  1. Chemically doped three-dimensional porous graphene monoliths for high-performance flexible field emitters.

    Science.gov (United States)

    Kim, Ho Young; Jeong, Sooyeon; Jeong, Seung Yol; Baeg, Kang-Jun; Han, Joong Tark; Jeong, Mun Seok; Lee, Geon-Woong; Jeong, Hee Jin

    2015-03-12

    Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate.

  2. 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

  3. Emittance growth due to the wake field driven by an electron beam accelerated in an RF-gun of free electron laser 'ELSA'

    CERN Document Server

    Salah, W

    2000-01-01

    It appears that the ease of the parameter chosen for 'ELSA' photo injector, the influence of the exit aperture, in terms of beam quality, is slight concerning the transverse emittance: (DELTA epsilon sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r /epsilon sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub = = r)(z)approx 3% at maximum, and negligible concerning the axial emittance. To complete this paper, we recall the results previously obtained concerning the wake field of a closed or open cavity for a beam approaching the anode . They had quantitatively specified the expected deep asymmetry between the conducting walls regarding their contribution to the total wake field, besides the space-charge contribution. (Given that the radial walls have no time to contribute, these conducting walls are the cathode and the anode.) Thus, concerning the effects on whole-beam emittances, the correction (DELTA epsilon sub p sub e sub r sub p sub e sub n sub d sub i ...

  4. Silicon based light emitter utilizing tunnel injection of excess carriers via MIS structure

    Energy Technology Data Exchange (ETDEWEB)

    Arguirov, Tzanimir; Kittler, Martin [IHP - Innovations for High Performance Microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); IHP/BTU Joint Lab BTU Cottbus, Konrad-Wachsmann-Allee 1, 03013 Cottbus (Germany); Wenger, Christian; Lukosius, Mindaugas [IHP - Innovations for High Performance Microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Mchedlidze, Teimuraz [IHP/BTU Joint Lab BTU Cottbus, Konrad-Wachsmann-Allee 1, 03013 Cottbus (Germany); Reiche, Manfred [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

    2011-04-15

    We report on electro-luminescence from metal-insulator-semiconductor diodes (MISLED). MISLEDs prepared on silicon with HfO2 layers of different thicknesses were investigated and their properties compared with such prepared by using SiO2 insulator layer. The role of the insulator layer was studied in view of the efficiency of the band-to-band radiation from silicon. We show that the luminescence efficiency depends on the dielectric constant of the insulator as well as on its ability to conduct carriers by tunnelling. Efficiency enhancement of 3.3 times was detected when the SiO{sub 2} insulator was substituted by HfO{sub 2} in the MIS emitter. Optimal injection current exists, which leads to a maximal efficiency of the luminescence. The optimal current depends strongly on the thickness of the oxide. We relate the existence of an optimal current with the depth at which the injected minority carriers recombine radiatively. Thus the electric field in the semiconductor and the surface recombination are the factors determining the optimal injection (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Song, Guo-Zhu; Zhang, Mei; Ai, Qing; Yang, Guo-Jian [Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875 (China); Alsaedi, Ahmed; Hobiny, Aatef [NAAM-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Deng, Fu-Guo, E-mail: fgdeng@bnu.edu.cn [Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875 (China); NAAM-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2017-03-15

    We propose a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We show the details by implementing nonlocal entanglement generation, entanglement swapping, and entanglement purification modules with atoms in waveguides, and discuss the feasibility of the repeater with currently achievable technology. In our scheme, the faulty events can be discarded by detecting the polarization of the photons. That is, our protocols are accomplished with a fidelity of 100% in principle, which is advantageous for implementing realistic long-distance quantum communication. Moreover, additional atomic qubits are not required, but only a single-photon medium. Our scheme is scalable and attractive since it can be realized in solid-state quantum systems. With the great progress on controlling atom-waveguide systems, the repeater may be very useful in quantum information processing in the future.

  6. Ultrathin MoS2 and WS2 layers on silver nano-tips as electron emitters

    Science.gov (United States)

    Loh, Tamie A. J.; Tanemura, Masaki; Chua, Daniel H. C.

    2016-09-01

    2-dimensional (2D) inorganic analogues of graphene such as MoS2 and WS2 present interesting opportunities for field emission technology due to their high aspect ratio and good electrical conductivity. However, research on 2D MoS2 and WS2 as potential field emitters remains largely undeveloped compared to graphene. Herein, we present an approach to directly fabricate ultrathin MoS2 and WS2 onto Ag nano-tips using pulsed laser deposition at low temperatures of 450-500 °C. In addition to providing a layer of chemical and mechanical protection for the Ag nano-tips, the growth of ultrathin MoS2 and WS2 layers on Ag led to enhanced emission properties over that of pristine nano-tips due to a reduction of the effective barrier height arising from charge injection from Ag to the overlying MoS2 or WS2. For WS2 on Ag nano-tips, the phasic mixture was also an important factor influencing the field emission performance. The presence of 1T-WS2 at the metal-WS2 interface in a hybrid film of 2H/1T-WS2 leads to improvement in the field emission capabilities as compared to pure 2H-WS2 on Ag nano-tips.

  7. Non-Doped Sky-Blue OLEDs Based on Simple Structured AIE Emitters with High Efficiencies at Low Driven Voltages.

    Science.gov (United States)

    Islam, Amjad; Zhang, Dongdong; Peng, Ruixiang; Yang, Rongjuan; Hong, Ling; Song, Wei; Wei, Qiang; Duan, Lian; Ge, Ziyi

    2017-09-05

    Blue organic light-emitting diodes (OLEDs) are necessary for flat-panel display technologies and lighting applications. To make more energy-saving, low-cost and long-lasting OLEDs, efficient materials as well as simple structured devices are in high demand. However, a very limited number of blue OLEDs achieving high stability and color purity have been reported. Herein, three new sky-blue emitters, 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI), with a combination of imidazole and tetraphenylethene groups, have been developed. High photoluminescence quantum yields are obtained for these materials. All derivatives have demonstrated aggregation-induced emission (AIE) behavior, excellent thermal stability with high decomposition and glass transition temperatures. Non-doped sky-blue OLEDs with simple structure have been fabricated employing these materials as emitters and realized high efficiencies of 2.41 % (4.92 cd A -1 , 2.70 lm W -1 ), 2.16 (4.33 cd A -1 , 2.59 lm W -1 ) and 3.13 % (6.97 cd A -1 , 4.74 lm W -1 ) for TPEI, TPEMeOPhI and 3TPEI, with small efficiency roll-off. These are among excellent results for molecules constructed from the combination of imidazole and TPE reported so far. The high performance of a 3TPEI-based device shows the promising potential of the combination of imidazole and AIEgen for synthesizing efficient electroluminescent materials for OLED devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Increase of intrinsic emittance induced by multiphoton photoemission from copper cathodes illuminated by femtosecond laser pulses

    Science.gov (United States)

    An, Chenjie; Zhu, Rui; Xu, Jun; Liu, Yaqi; Hu, Xiaopeng; Zhang, Jiasen; Yu, Dapeng

    2018-05-01

    Electron sources driven by femtosecond laser have important applications in many aspects, and the research about the intrinsic emittance is becoming more and more crucial. The intrinsic emittance of polycrystalline copper cathode, which was illuminated by femtosecond pulses (FWHM of the pulse duration was about 100 fs) with photon energies above and below the work function, was measured with an extremely low bunch charge (single-electron pulses) based on free expansion method. A minimum emittance was obtained at the photon energy very close to the effective work function of the cathode. When the photon energy decreased below the effective work function, emittance increased rather than decreased or flattened out to a constant. By investigating the dependence of photocurrent density on the incident laser intensity, we found the emission excited by pulsed photons with sub-work-function energies contained two-photon photoemission. In addition, the portion of two-photon photoemission current increased with the reduction of photon energy. We attributed the increase of emittance to the effect of two-photon photoemission. This work shows that conventional method of reducing the photon energy of excited light source to approach the room temperature limit of the intrinsic emittance may be infeasible for femtosecond laser. There would be an optimized photon energy value near the work function to obtain the lowest emittance for pulsed laser pumped photocathode.

  9. Electrically excited hot-electron dominated fluorescent emitters using individual Ga-doped ZnO microwires via metal quasiparticle film decoration.

    Science.gov (United States)

    Liu, Yang; Jiang, Mingming; Zhang, Zhenzhong; Li, Binghui; Zhao, Haifeng; Shan, Chongxin; Shen, Dezhen

    2018-03-28

    The generation of hot electrons from metal nanostructures through plasmon decay provided a direct interfacial charge transfer mechanism, which no longer suffers from the barrier height restrictions observed for metal/semiconductor interfaces. Metal plasmon-mediated energy conversion with higher efficiency has been proposed as a promising alternative to construct novel optoelectronic devices, such as photodetectors, photovoltaic and photocatalytic devices, etc. However, the realization of the electrically-driven generation of hot electrons, and the application in light-emitting devices remain big challenges. Here, hybrid architectures comprising individual Ga-doped ZnO (ZnO:Ga) microwires via metal quasiparticle film decoration were fabricated. The hottest spots could be formed towards the center of the wires, and the quasiparticle films were converted into physically isolated nanoparticles by applying a bias onto the wires. Thus, the hot electrons became spatially localized towards the hottest regions, leading to a release of energy in the form of emitting photons. By adjusting the sputtering times and appropriate alloys, such as Au and Ag, wavelength-tunable emissions could be achieved. To exploit the EL emission characteristics, metal plasmons could be used as active elements to mediate the generation of hot electrons from metal nanostructures, which are located in the light-emitting regions, followed by injection into ZnO:Ga microwire-channels; thus, the production of plasmon decay-induced hot-electrons could function as an efficient approach to dominate emission wavelengths. Therefore, by introducing metal nanostructure decoration, individual ZnO:Ga microwires can be used to construct wavelength-tunable fluorescent emitters. The hybrid architectures of metal-ZnO micro/nanostructures offer a fantastic candidate to broaden the potential applications of semiconducting optoelectronic devices, such as photovoltaic devices, photodetectors, optoelectronic sensors, etc.

  10. Enhancement of electron emission and long-term stability of tip-type carbon nanotube field emitters via lithium coating

    International Nuclear Information System (INIS)

    Kim, Jong-Pil; Chang, Han-Beet; Kim, Bu-Jong; Park, Jin-Seok

    2013-01-01

    Carbon nanotubes (CNTs) were deposited on conical tip-type substrates via electrophoresis and coated with lithium (Li) thin films with diverse thicknesses via electroplating. For the as-deposited (i.e., without Li coating) CNT, the turn-on (or triggering) electric field was 0.92 V/μm, and the emission current, which was generated at an applied field of 1.2 V/μm was 56 μA. In the case of the 4.7 nm-thick Li-coated CNT, the turn-on field decreased to 0.65 V/μm and the emission current at the same applied field increased more than ten times to 618 μA. The analysis based on the Kelvin probe measurement and Fowler–Nordheim theory indicated that the coating of Li caused a loss in the structural-aspect-ratio of the CNTs and it reduced their effective work functions from 5.36 eV to 4.90 eV, which led to a great improvement of their electron emission characteristics. The results obtained in this study also showed that the long-term emission stability could be enhanced by the coating of thin Li films on CNTs. - Highlights: ► CNTs are deposited via electrophoretic deposition (EPD). ► Thin films of Li are coated on CNTs via electroplating, without plasma damage. ► Li coating enhanced field emission properties and emission stability of CNTs. ► The effective work functions and field enhancement factors of CNTs are evaluated

  11. Some applications of Photon/Electron-Rejecting Alpha Liquid Scintillation (PERALS) spectrometry to the assay of alpha emitters

    International Nuclear Information System (INIS)

    McDowell, W.J.; Case, G.N.

    1988-01-01

    The combination of certain solvent extraction separations and a special kind of liquid scintillation detector and electronics designed for alpha spectrometry allows some highly accurate, yet simple determinations of alpha-emitting nuclides. Counting efficiency is 99.68% with backgrounds of 99.95%. The Photon/Electron Rejecting Alpha Liquid Scintillation (PERALS) equipment is described and procedures for the separation and determination of uranium, thorium, plutonium, polonium, radium, and trivalent actinides are outlined. 25 refs., 10 figs., 1 tab

  12. Cu incorporated amorphous diamond like carbon (DLC) composites: An efficient electron field emitter over a wide range of temperature

    Science.gov (United States)

    Ahmed, Sk Faruque; Alam, Md Shahbaz; Mukherjee, Nillohit

    2018-03-01

    The effect of temperature on the electron field emission properties of copper incorporated amorphous diamond like carbon (a-Cu:DLC) thin films have been reported. The a-Cu:DLC thin films have been deposited on indium tin oxide (ITO) coated glass and silicon substrate by the radio frequency sputtering process. The chemical composition of the films was investigated using X-ray photoelectron spectroscopy and the micro structure was established using high resolution transmission electron microscopy. The sp2 and sp3 bonding ratio in the a-Cu:DLC have been analyzed by the Fourier transformed infrared spectroscopy studies. The material showed excellent electron field emission properties; which was optimized by varying the copper atomic percentage and temperature of the films. It was found that the threshold field and effective emission barrier were reduced significantly by copper incorporation as well as temperature and a detailed explanation towards emission mechanism has been provided.

  13. A New Design Strategy for Efficient Thermally Activated Delayed Fluorescence Organic Emitters: From Twisted to Planar Structures

    KAUST Repository

    Chen, Xiankai

    2017-10-17

    In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.

  14. Spatial coherence of electron beams from field emitters and its effect on the resolution of imaged objects

    Energy Technology Data Exchange (ETDEWEB)

    Latychevskaia, Tatiana, E-mail: tatiana@physik.uzh.ch

    2017-04-15

    Sub-nanometer and nanometer-sized tips provide high coherence electron sources. Conventionally, the effective source size is estimated from the extent of the experimental biprism interference pattern created on the detector by applying the van Cittert Zernike theorem. Previously reported experimental intensity distributions on the detector exhibit Gaussian distribution and our simulations show that this is an indication that such electron sources must be at least partially coherent. This, in turn means that strictly speaking the Van Cittert Zernike theorem cannot be applied, since it assumes an incoherent source. The approach of applying the van Cittert Zernike theorem is examined in more detail by performing simulations of interference patterns for the electron sources of different size and different coherence length, evaluating the effective source size from the extent of the simulated interference pattern and comparing the obtained result with the pre-defined value. The intensity distribution of the source is assumed to be Gaussian distributed, as it is observed in experiments. The visibility or the contrast in the simulated holograms is found to be always less than 1 which agrees well with previously reported experimental results and thus can be explained solely by the Gaussian intensity distribution of the source. The effective source size estimated from the extent of the interference pattern turns out to be of about 2–3 times larger than the pre-defined size, but it is approximately equal to the intrinsic resolution of the imaging system. A simple formula for estimating the intrinsic resolution, which could be useful when employing nano-tips in in-line Gabor holography or point-projection microscopy, is provided. - Highlights: • van Cittert Zernike theorem for nano- and sub-nano electron emitting tips is revised. • Simulations show that nano- and sub-nano electron emitting tips are at least partially coherent. • A simple formula for evaluating

  15. Performance of hybrid p-type vertical transistors with poly(N-vinylcarbazole) as emitter and the transfer mechanism of charge carriers through the base

    International Nuclear Information System (INIS)

    Huang, Jinying; Ma, Dongge; Hümmelgen, Ivo A

    2013-01-01

    We report hybrid vertical architecture p-type transistors with poly(N-vinylcarbazole) as the emitter, p-type silicon as the collector and Al:Ca alloy layer as the base. The investigation of the common-base and common-emitter characteristics clearly demonstrates that the devices operate as permeable-base transistors (PBTs). The PBTs show common-base current gain α of 0.98 at −V BC = 1.5 V and common-emitter gain β of over 100. Atomic force microscope images of the base layer show an uneven surface, showing that the annealing does not dissolve the charge trap states but offers ‘pinholes’ for the oxidation in-depth even through the whole base layer. In this case, the charge carriers must tunnel the thin oxidized layer, and then are collected. It is clearly seen that there exists a barrier against holes injection from the base to the collector semiconductor at the interface, and the further oxidation caused by exposing the devices in air changes the operational mode of the resulting devices from the PBT to the metal-base transistor. (paper)

  16. Development of high-current-density LAB6 thermionic emitters for a space-charge-limited electron gun

    International Nuclear Information System (INIS)

    Herniter, M.E.; Getty, W.D.

    1987-01-01

    An electron gun has been developed for investigation of high current density, space charge limited operation of a lenthanum hexaboride (LaB 6 ) thermionic cathode. The 2.8 cm 2 cathode disk is heated by electron bombardment from a tungsten filament. For LaB 6 cathode temperatures greater than 1600 0 C it has been found that evaporation from the LaB 6 causes an increase in the tungsten filament emission, leading to an instability in the bombardment heating system. This instability has been investigated and eliminated by using a graphite disk in place of the LaB 6 cathode or by shielding the filament from the LaB 6 cathode by placing the LaB 6 in a graphite cup and bombarding the cup. The graphite disk has been heated to 1755 0 C with 755 W of heating power, and the shielded LaB 6 cathode has been heated to 1695 0 C. This temperature range is required for emission current densities in the 30 Acm 2 range. It is believed that the evaporation of lanthanum lowers the tungsten work function. In electron-gun use, the LaB 6 cathode has been operated up to 6.7 Acm 2 at 36 kV. A 120 kV Marx generator has been built to allow operation up to 40 Acm 2

  17. Miniature X-ray Tube for Electric Brachytherapy using Carbon Nanotube Field Emitter

    International Nuclear Information System (INIS)

    Heo, Sung Hwan; Kim, Hyun Jin; Ha, Jun Mok; Cho, Sung Oh

    2011-01-01

    An electric brachytherapy using a miniature x-ray tube has a major advantage to reduce the x-ray exposure of human body during the cancer radiation therapy by optimal positioning of x-ray radiation source and treatment objectives. In the view of a smaller electronic x-ray source, the CNT field emitter based xray tube can be more minimized than thermionic filament emitter based one because of a simple power supplier connection of cold field emission in diode type as well as a higher electron emission brightness of CNT. This abstract is for introducing the design of a prototype CNT field emitter based miniature x-ray tube. We have vacuum sealed CNT miniature x-ray tube with 7∼10 mm diameter, and characteristics of electron emission and x-ray transportation using MCNP5 code are surveyed

  18. Radiation emitter-detector package

    International Nuclear Information System (INIS)

    O'Brien, J.T.; Limm, A.C.; Nyul, P.; Tassia, V.S. Jr.

    1978-01-01

    Mounted on the metallic base of a radiation emitter-detector is a mounting block is a first projection, and a second projection. A radiation detector is on the first projection and a semiconductor electroluminescent device, i.e., a radiation emitter, is on the second projection such that the plane of the recombination region of the electroluminescent device is perpendicular to the radiation incident surface of the radiation detector. The electroluminescent device has a primary emission and a secondary emission in a direction different from the primary emission. A radiation emitter-detector package as described is ideally suited to those applications wherein the secondary radiation of the electroluminescent device is fed into a feedback circuit regulating the biasing current of the electroluminescent device

  19. Low emittance configuration for spear

    International Nuclear Information System (INIS)

    Blumberg, L.N.; Harris, J.; Stege, R.; Cerino, J.; Hettel, R.; Hofmann, A.; Liu, R.Z.; Wiedemann, H.; Winick, H.

    1985-01-01

    The quality of synchrotron radiation beams from SPEAR, in particular the brilliance of undulator radiation, can be improved significantly by reducing the emittance of the stored electron beam. A reduction of the horizontal emittance by a factor of 3.5 to a value of 130 nanometer-radians (nm-r) at 3 GeV has been achieved by using stronger focussing, mainly in the horizontal plane. The low emittance configuration also reduces the dispersion and vertical beta functions in the straight sections, making them more suitable for wigglers. The higher betatron tunes lead to a larger phase advance between the two kickers, which has to be corrected during injection by shunting current from some quadrupoles. The configuration was optimized within SPEAR hardware limitations and tested for dynamic aperture with the tracking program PATRICIA. After implementation of this scheme, beam was successfully injected and accumulated. The measured emittance of the stored beam was in agreement with calculations. Presently the configuration is being made operational

  20. High-brightness electron beam evolution following laser-based cleaning of a photocathode

    Directory of Open Access Journals (Sweden)

    F. Zhou

    2012-09-01

    Full Text Available Laser-based techniques have been widely used for cleaning metal photocathodes to increase quantum efficiency (QE. However, the impact of laser cleaning on cathode uniformity and thereby on electron beam quality are less understood. We are evaluating whether this technique can be applied to revive photocathodes used for high-brightness electron sources in advanced x-ray free-electron laser (FEL facilities, such as the Linac Coherent Light Source (LCLS at the SLAC National Accelerator Laboratory. The laser-based cleaning was applied to two separate areas of the current LCLS photocathode on July 4 and July 26, 2011, respectively. The QE was increased by 8–10 times upon the laser cleaning. Since the cleaning, routine operation has exhibited a slow evolution of the QE improvement and comparatively rapid improvement of transverse emittance, with a factor of 3 QE enhancement over five months, and a significant emittance improvement over the initial 2–3 weeks following the cleaning. Currently, the QE of the LCLS photocathode is holding constant at about 1.2×10^{-4}, with a normalized injector emittance of about 0.3  μm for a 150-pC bunch charge. With the proper procedures, the laser-cleaning technique appears to be a viable tool to revive the LCLS photocathode. We present observations and analyses for the QE and emittance evolution in time following the laser-based cleaning of the LCLS photocathode, and comparison to the previous studies, the measured thermal emittance versus the QE and comparison to the theoretical model.

  1. Quantum efficiency and thermal emittance of metal photocathodes

    Directory of Open Access Journals (Sweden)

    David H. Dowell

    2009-07-01

    Full Text Available Modern electron beams have demonstrated the brilliance needed to drive free electron lasers at x-ray wavelengths with major advances occurring since the invention of the photocathode gun and the realization of emittance compensation. These state-of-the-art electron beams are now becoming limited by the intrinsic thermal emittance of the cathode. In both dc and rf photocathode guns details of the cathode emission physics strongly influence the quantum efficiency and the thermal emittance. Therefore improving cathode performance is essential to increasing the brightness of beams. It is especially important to understand the fundamentals of cathode quantum efficiency and thermal emittance. This paper investigates the relationship between the quantum efficiency and the thermal emittance for metal cathodes using the Fermi-Dirac model for the electron distribution. We use a consistent theory to derive the quantum efficiency and thermal emittance, and compare our results to those of others.

  2. The Quantum Efficiency and Thermal Emittance of Metal Photocathodes

    International Nuclear Information System (INIS)

    Dowell, D.

    2009-01-01

    Modern electron beams have demonstrated the brilliance needed to drive free electron lasers at x-ray wavelengths, with the principle improvements occurring since the invention of the photocathode gun. The state-of-the-art normalized emittance electron beams are now becoming limited by the thermal emittance of the cathode. In both DC and RF photocathode guns, details of the cathode emission physics strongly influence the quantum efficiency and the thermal emittance. Therefore improving cathode performance is essential to increasing the brightness of beams. It is especially important to understand the fundamentals of cathode quantum efficiency and thermal emittance. This paper investigates the relationship between the quantum efficiency and the thermal emittance of metal cathodes using the Fermi-Dirac model for the electron distribution. We derive the thermal emittance and its relationship to the quantum efficiency, and compare our results to those of others

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

    International Nuclear Information System (INIS)

    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 beam profile will be described

  4. 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...

  5. Current-Fluctuation Mechanism of Field Emitters Using Metallic Single-Walled Carbon Nanotubes with High Crystallinity

    Directory of Open Access Journals (Sweden)

    Norihiro Shimoi

    2017-12-01

    Full Text Available Field emitters can be used as a cathode electrode in a cathodoluminescence device, and single-walled carbon nanotubes (SWCNTs that are synthesized by arc discharge are expected to exhibit good field emission (FE properties. However, a cathodoluminescence device that uses field emitters radiates rays whose intensity considerably fluctuates at a low frequency, and the radiant fluctuation is caused by FE current fluctuation. To solve this problem, is very important to obtain a stable output for field emitters in a cathodoluminescence device. The authors consider that the electron-emission fluctuation is caused by Fowler–Nordheim electron tunneling and that the electrons in the Fowler–Nordheim regime pass through an inelastic potential barrier. We attempted to develop a theoretical model to analyze the power spectrum of the FE current fluctuation using metallic SWCNTs as field emitters, owing to their electrical conductivity by determining their FE properties. Field emitters that use metallic SWCNTs with high crystallinity were successfully developed to achieve a fluctuating FE current from field emitters at a low frequency by employing inelastic electron tunneling. This paper is the first report of the successful development of an inelastic-electron-tunneling model with a Wentzel–Kramers–Brillouin approximation for metallic SWCNTs based on the evaluation of FE properties.

  6. Deep Ultraviolet Light Emitters Based on (Al,Ga)N/GaN Semiconductor Heterostructures

    Science.gov (United States)

    Liang, Yu-Han

    Deep ultraviolet (UV) light sources are useful in a number of applications that include sterilization, medical diagnostics, as well as chemical and biological identification. However, state-of-the-art deep UV light-emitting diodes and lasers made from semiconductors still suffer from low external quantum efficiency and low output powers. These limitations make them costly and ineffective in a wide range of applications. Deep UV sources such as lasers that currently exist are prohibitively bulky, complicated, and expensive. This is typically because they are constituted of an assemblage of two to three other lasers in tandem to facilitate sequential harmonic generation that ultimately results in the desired deep UV wavelength. For semiconductor-based deep UV sources, the most challenging difficulty has been finding ways to optimally dope the (Al,Ga)N/GaN heterostructures essential for UV-C light sources. It has proven to be very difficult to achieve high free carrier concentrations and low resistivities in high-aluminum-containing III-nitrides. As a result, p-type doped aluminum-free III-nitrides are employed as the p-type contact layers in UV light-emitting diode structures. However, because of impedance-mismatch issues, light extraction from the device and consequently the overall external quantum efficiency is drastically reduced. This problem is compounded with high losses and low gain when one tries to make UV nitride lasers. In this thesis, we provide a robust and reproducible approach to resolving most of these challenges. By using a liquid-metal-enabled growth mode in a plasma-assisted molecular beam epitaxy process, we show that highly-doped aluminum containing III-nitride films can be achieved. This growth mode is driven by kinetics. Using this approach, we have been able to achieve extremely high p-type and n-type doping in (Al,Ga)N films with high aluminum content. By incorporating a very high density of Mg atoms in (Al,Ga)N films, we have been able to

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

    International Nuclear Information System (INIS)

    Koji, T.; Tseng, W.F.; Mayer, J.W.; Suganuma, T.

    1979-01-01

    Emitters of npn silicon bipolar transistors have been made by a phosphorus implantation at 50 keV P + to a dose of 1 x 10 16 cm -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 N 2 , dry 0 2 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 N 2 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)

  8. Preservation of low slice emittance in bunch compressors

    Directory of Open Access Journals (Sweden)

    S. Bettoni

    2016-03-01

    Full Text Available Minimizing the dilution of the electron beam emittance is crucial for the performance of accelerators, in particular for free electron laser facilities, where the length of the machine and the efficiency of the lasing process depend on it. Measurements performed at the SwissFEL Injector Test Facility revealed an increase in slice emittance after compressing the bunch even for moderate compression factors. The phenomenon was experimentally studied by characterizing the dependence of the effect on beam and machine parameters relevant for the bunch compression. The reproduction of these measurements in simulation required the use of a 3D beam dynamics model along the bunch compressor that includes coherent synchrotron radiation. Our investigations identified transverse effects, such as coherent synchrotron radiation and transverse space charge as the sources of the observed emittance dilution, excluding other effects, such as chromatic effects on single slices or spurious dispersion. We also present studies, both experimental and simulation based, on the effect of the optics mismatch of the slices on the variation of the slice emittance along the bunch. After a corresponding reoptimization of the beam optics in the test facility we reached slice emittances below 200 nm for the central slices along the longitudinal dimension with a moderate increase up to 300 nm in the head and tail for a compression factor of 7.5 and a bunch charge of 200 pC, equivalent to a final current of 150 A, at about 230 MeV energy.

  9. Auger electron emitter against multiple myeloma - targeted endo-radio-therapy with 125I-labeled thymidine analogue 5-iodo-4'-thio-2'-deoxyuridine

    International Nuclear Information System (INIS)

    Morgenroth, Agnieszka; Dinger, Cornelia; Zlatopolskiy, Boris D.; Al-Momani, Ehab; Glatting, Gerhard; Mottaghy, Felix M.; Reske, Sven N.

    2011-01-01

    Introduction: Multiple myeloma (MM) is a plasma cell malignancy characterized by accumulation of malignant, terminally differentiated B cells in the bone marrow. Despite advances in therapy, MM remains an incurable disease. Novel therapeutic approaches are, therefore, urgently needed. Auger electron-emitting radiopharmaceuticals are attractive for targeted nano-irradiation therapy, given that DNA of malignant cells is selectively addressed. Here we evaluated the antimyeloma potential of the Auger electron-emitting thymidine analogue 125 I-labeled 5-iodo-4'-thio-2'-deoxyuridine ([ 125 I]ITdU). Methods: Cellular uptake and DNA incorporation of [ 125 I]ITdU were determined in fluorodeoxyuridine-pretreated KMS12BM, U266, dexamethasone-sensitive MM1.S and -resistant MM1.R cell lines. The effect of stimulation with interleukin 6 (IL6) or insulin-like growth factor 1 (IGF1) on the intracellular incorporation of [ 125 I]ITdU was investigated in cytokine-sensitive MM1.S and MM1.R cell lines. Apoptotic cells were identified using Annexin V. Cleavage of caspase 3 and PARP was visualized by Western blot. DNA fragmentation was investigated using laddering assay. Therapeutic efficiency of [ 125 I]ITdU was proven by clonogenic assay. Results: [ 125 I]ITdU was shown to be efficiently incorporated into DNA of malignant cells, providing a promising mechanism for delivering highly toxic Auger radiation emitters into tumor DNA. [ 125 I]ITdU had a potent antimyeloma effect in cell lines representing distinct disease stages and, importantly, in cell lines sensitive or resistant to the conventional therapeutic agent, but was not toxic for normal plasma and bone marrow stromal cells. Furthermore, [ 125 I]ITdU abrogated the protective actions of IL6 and IGF1 on MM cells. [ 125 I]ITdU induced massive damage in the DNA of malignant plasma cells, which resulted in efficient inhibition of clonogenic growth. Conclusion: These studies may provide a novel treatment strategy for overcoming

  10. Highly efficient and simplified phosphorescence white organic light-emitting diodes based on synthesized deep-blue host and orange emitter

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Ja Ryong; Lee, Seok Jae; Hyung, Gun Woo; Kim, Bo Young; Lee, Dong Hyung [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Woo Young [Department of Green Energy and Semiconductor Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Lee, Kum Hee [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of)

    2013-10-01

    The authors have demonstrated a highly efficient and stable phosphorescent white organic light-emitting diode (WOLED), which has been achieved by doping only one orange phosphorescent emitter, Bis(5-benzoyl-2-(4-fluorophenyl)pyridinato-C,N)iridium(III) acetylacetonate into an appropriate deep blue phosphorescent host, 4,4'-bis(4-(triphenylsilyl)phenyl)-1,1'-binaphthyl as an emitting layer (EML). The WOLED has been achieved by effective confinement of triplet excitons to emit a warm white color. The optimized WOLED, with a simple structure as a hole transporting layer-EML-electron transporting layer, showed a maximum luminous efficiency of 22.38 cd/A, a maximum power efficiency of 12.01 lm/W, a maximum external quantum efficiency of 7.32%, and CIEx,y coordinates of (0.38,0.42) at 500 cd/m{sup 2}, respectively. - Highlights: • Highly efficient phosphorescent white organic light-emitting diode (WOLED) • Single emitting layer consists of synthesized deep blue host and orange emitter • The WOLED with high EL efficiencies due to efficient triplet exciton confinement.

  11. Method to fabricate portable electron source based on nitrogen incorporated ultrananocrystalline diamond (N-UNCD)

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Divan, Ralu; Posada, Chrystian M.; Castano, Carlos H.; Grant, Edwin J.; Lee, Hyoung K.

    2016-03-29

    A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA.

  12. A low-emittance lattice for SPEAR

    International Nuclear Information System (INIS)

    Safranek, J.; Wiedemann, H.

    1992-01-01

    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 129 π nm rad, which makes the low emittance lattice the lowest emittance, runnning synchroton 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 incrased by reducing β y 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 despersion 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 resonable 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. (orig.)

  13. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  14. Coupling of Quantum Emitters in Nanodiamonds to Plasmonic Structures

    DEFF Research Database (Denmark)

    Kumar, Shailesh

    This PhD thesis describes work towards the enhancement and efficient channeling of photons emitted from a single photon emitter. The emitter used is a defect center, the Nitrogen-Vacancy (NV) center, in diamond. The NV-center has many unique properties, such as long coherence time of its electron...

  15. Cancer from internal emitters

    International Nuclear Information System (INIS)

    Boecker, B.B.; Griffith, W.C. Jr.

    1995-01-01

    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 226 Ra or medical injections of 224 Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes

  16. Transverse emittance measurement at REGAE via a solenoid scan

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, Max; Mayet, Frank; Gruener, Florian [Institut fuer Experimentalphysik, Universitaet Hamburg (Germany); Floettmann, Klaus [DESY, Hamburg (Germany)

    2013-07-01

    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 which can be identified with a small beam emittance. The current method to measure the transverse beam emittance at REGAE and results are presented.

  17. Simple-to-prepare multipoint field emitter

    Science.gov (United States)

    Sominskii, G. G.; Taradaev, E. P.; Tumareva, T. A.; Mishin, M. V.; Kornishin, S. Yu.

    2015-07-01

    We investigate multitip field emitters prepared by electroerosion treatment of the surface of molybdenum samples. Their characteristics are determined for operation with a protecting activated fullerene coating. Our experiments indicate that such cathodes are promising for high-voltage electron devices operating in technical vacuum.

  18. Emittance measuring system on the UNILAC

    International Nuclear Information System (INIS)

    Ehrich, A.; Glatz, J.; Strahl, P.

    A description is given of one of the beam emittance measuring systems designed for the UNILAC at GSI. The measuring system mechanics and the detector system are detailed, and the associated electronics are discussed. Computer programming and data processing and evaluation are described

  19. Calculating emittance for Gaussian and Non-Gaussian distributions by the method of correlations for slits

    International Nuclear Information System (INIS)

    Tan, Cheng-Yang; Fermilab

    2006-01-01

    One common way for measuring the emittance of an electron beam is with the slits method. The usual approach for analyzing the data is to calculate an emittance that is a subset of the parent emittance. This paper shows an alternative way by using the method of correlations which ties the parameters derived from the beamlets to the actual parameters of the parent emittance. For parent distributions that are Gaussian, this method yields exact results. For non-Gaussian beam distributions, this method yields an effective emittance that can serve as a yardstick for emittance comparisons

  20. Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

    International Nuclear Information System (INIS)

    Winkler, Justin M; Lukishova, Svetlana G; Bissell, Luke J

    2013-01-01

    Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ∼4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

  1. BEAM EMITTANCE MEASUREMENT TOOL FOR CEBAF OPERATIONS

    International Nuclear Information System (INIS)

    Chevtsov, Pavel; Tiefenback, Michael

    2008-01-01

    A new software tool was created at Jefferson Lab to measure the emittance of the CEBAF electron beams. The tool consists of device control and data analysis applications. The device control application handles the work of wire scanners and writes their measurement results as well as the information about accelerator settings during these measurements into wire scanner data files. The data analysis application reads these files and calculates the beam emittance on the basis of a wire scanner data processing model. Both applications are computer platform independent but are mostly used on LINUX PCs recently installed in the accelerator control room. The new tool significantly simplifies beam emittance measurement procedures for accelerator operations and contributes to a very high availability of the CEBAF machine for the nuclear physics program at Jefferson Lab.

  2. On the design guideline for the low emittance synchrotron radiation source

    International Nuclear Information System (INIS)

    Kamiya, Y.; Kihara, M.

    1983-09-01

    In this note we will describe how the emittance of the electron storage ring is determined by the orbit parameters of the storage ring and show the lowest value of emittance which is achieved theoretically. Implication of this note with regard to the design of the low emittance storage ring will be discussed. (author)

  3. Low-emittance tuning of storage rings using normal mode beam position monitor calibration

    Directory of Open Access Journals (Sweden)

    A. Wolski

    2011-07-01

    Full Text Available We describe a new technique for low-emittance tuning of electron and positron storage rings. This technique is based on calibration of the beam position monitors (BPMs using excitation of the normal modes of the beam motion, and has benefits over conventional methods. It is relatively fast and straightforward to apply, it can be as easily applied to a large ring as to a small ring, and the tuning for low emittance becomes completely insensitive to BPM gain and alignment errors that can be difficult to determine accurately. We discuss the theory behind the technique, present some simulation results illustrating that it is highly effective and robust for low-emittance tuning, and describe the results of some initial experimental tests on the CesrTA storage ring.

  4. Low-emittance tuning of storage rings using normal mode beam position monitor calibration

    Science.gov (United States)

    Wolski, A.; Rubin, D.; Sagan, D.; Shanks, J.

    2011-07-01

    We describe a new technique for low-emittance tuning of electron and positron storage rings. This technique is based on calibration of the beam position monitors (BPMs) using excitation of the normal modes of the beam motion, and has benefits over conventional methods. It is relatively fast and straightforward to apply, it can be as easily applied to a large ring as to a small ring, and the tuning for low emittance becomes completely insensitive to BPM gain and alignment errors that can be difficult to determine accurately. We discuss the theory behind the technique, present some simulation results illustrating that it is highly effective and robust for low-emittance tuning, and describe the results of some initial experimental tests on the CesrTA storage ring.

  5. 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.

  6. Beam manipulation for compact laser wakefield accelerator based free-electron lasers

    International Nuclear Information System (INIS)

    Loulergue, A; Labat, M; Benabderrahmane, C; Couprie, M E; Evain, C; Malka, V

    2015-01-01

    Free-electron lasers (FELs) are a unique source of light, particularly in the x-ray domain. After the success of FELs based on conventional acceleration using radio-frequency cavities, an important challenge is the development of FELs based on electron bunching accelerated by a laser wakefield accelerator (LWFA). However, the present LWFA electron bunch properties do not permit use directly for a significant FEL amplification. It is known that longitudinal decompression of electron beams delivered by state-of-the-art LWFA eases the FEL process. We propose here a second order transverse beam manipulation turning the large inherent transverse chromatic emittances of LWFA beams into direct FEL gain advantage. Numerical simulations are presented showing that this beam manipulation can further enhance by orders of magnitude the peak power of the radiation. (paper)

  7. Emittance scans for CMS luminosity calibration in 2017

    CERN Document Server

    CMS Collaboration

    2018-01-01

    Emittance scans are short van der Meer type scans performed at the beginning and at the end of LHC fills. The beams are scanned against each other in X and Y planes in 7 displacement steps. These scans are used for LHC diagnostics and since 2017 for a cross check of the CMS luminosity calibration. An XY pair of scans takes around 3 minutes. The BRIL project provides to LHC three independent online luminosity measurement from the Pixel Luminosity Telescope (PLT), the Fast Beam Condition Monitor (BCM1F) and the Forward calorimeter (HF). The excellent performance of the BRIL detector front-ends, fast back-end electronics and CMS XDAQ based data processing and publication allow the use of emittance scans for linearity and stability studies of the luminometers. Emittance scans became a powerful tool and dramatically improved the understanding of the luminosity measurement during the year. Since each luminometer is independently calibrated in every scan the measurements are independent and ratios of luminometers ca...

  8. Nanometer emittance ultralow charge beams from rf photoinjectors

    Directory of Open Access Journals (Sweden)

    R. K. Li

    2012-09-01

    Full Text Available In this paper we discuss the generation of a new class of high brightness relativistic electron beams, characterized by ultralow charge (0.1–1 pC and ultralow normalized emittance (<50  nm. These beams are created in rf photoinjectors when the laser is focused on the cathode to very small transverse sizes (<30  μm rms. In this regime, the charge density at the cathode approaches the limit set by the extraction electric field. By shaping the laser pulse to have a cigarlike aspect ratio (the longitudinal dimension much larger than the transverse dimension and a parabolic temporal profile, the resulting space charge dominated dynamics creates a uniformly filled ellipsoidal distribution and the emittance can be nearly preserved to its thermal value. We also present a new method, based on a variation of the pepper-pot technique, for single shot measurements of the ultralow emittances for this new class of beams.

  9. Experimental studies of emittance growth and energy spread in a photocathode RF gun

    International Nuclear Information System (INIS)

    Yang, J.; Sakai, F.; Okada, Y.; Yorozu, M.; Yanagida, T.; Endo, A.

    2002-01-01

    In this paper we report on a low emittance electron source, based on a photocathode RF gun, a solenoid magnet and a subsequent linac. The dependencies of the beam transverse emittance and relative energy spread with respect to the laser injection phase of the radio-frequency (RF) gun, the RF phase of the linac and the bunch charge were investigated experimentally. It was found that a lower beam emittance is observed when the laser injection phase in the RF gun is low. The emittance increases almost linearly with the bunch charge under a constant solenoid magnetic field. The corrected relative energy spread of the beam is not strongly dependent on the bunch charge. Finally, an optimal normalized rms transverse emittance of 1.91±0.28 πmm mrad at a bunch charge of 0.6 nC was obtained when the RF gun was driven by a picosecond Nd:YAG laser. A corrected relative rms energy spread of 0.2-0.25% at a bunch charge of 0.3-2 nC was obtained after the beam was accelerated to 14 MeV by the subsequent linac

  10. Experimental studies of emittance growth and energy spread in a photocathode RF gun

    CERN Document Server

    Yang, J; Okada, Y; Yorozu, M; Yanagida, T; Endo, A

    2002-01-01

    In this paper we report on a low emittance electron source, based on a photocathode RF gun, a solenoid magnet and a subsequent linac. The dependencies of the beam transverse emittance and relative energy spread with respect to the laser injection phase of the radio-frequency (RF) gun, the RF phase of the linac and the bunch charge were investigated experimentally. It was found that a lower beam emittance is observed when the laser injection phase in the RF gun is low. The emittance increases almost linearly with the bunch charge under a constant solenoid magnetic field. The corrected relative energy spread of the beam is not strongly dependent on the bunch charge. Finally, an optimal normalized rms transverse emittance of 1.91+-0.28 pi mm mrad at a bunch charge of 0.6 nC was obtained when the RF gun was driven by a picosecond Nd:YAG laser. A corrected relative rms energy spread of 0.2-0.25% at a bunch charge of 0.3-2 nC was obtained after the beam was accelerated to 14 MeV by the subsequent linac.

  11. Femtosecond pulse with THz repetition frequency based on the coupling between quantum emitters and a plasmonic resonator

    Science.gov (United States)

    Li, Shilei; Ding, Yinxing; Jiao, Rongzhen; Duan, Gaoyan; Yu, Li

    2018-03-01

    Nanoscale pulsed light is highly desirable in nano-integrated optics. In this paper, we obtained femtosecond pulses with THz repetition frequency via the coupling between quantum emitters (QEs) and plasmonic resonators. Our structure consists of a V -groove (VG) plasmonic resonator and a nanowire embedded with two-level QEs. The influences of the incident light intensity and QE number density on the transmission response for this hybrid system are investigated through semiclassical theory and simulation. The results show that the transmission response can be modulated to the pulse form. And the repetition frequency and extinction ratio of the pulses can be controlled by the incident light intensity and QE number density. The reason is that the coupling causes the output power of nanowire to behave as an oscillating form, the oscillating output power in turn causes the field amplitude in the resonator to oscillate over time. A feedback system is formed between the plasmonic resonator and the QEs in the nanowire. This provides a method for generating narrow pulsed lasers with ultrahigh repetition frequencies in plasmonic systems using a continuous wave input, which has potential applications in generating optical clock signals at the nanoscale.

  12. Super high-power AlGaInN-based laser diodes with a single broad-area stripe emitter fabricated on a GaN substrate

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Shu; Ohta, Makoto; Yabuki, Yoshifumi; Hoshina, Yukio; Hashizu, Toshihiro; Ikeda, Masao [Development Center, Sony Shiroishi Semiconductor, Inc., 3-53-2 Shiratori, Shiroishi, Miyagi, 989-0734 (Japan); Naganuma, Kaori; Tamamura, Koshi [Core Technology Development Group, Micro Systems Network Company, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi Kanagawa, 243-0041 (Japan)

    2003-11-01

    AlGaInN-based blue-violet laser diodes with a single broad-area stripe emitter were successfully fabricated on GaN substrates. Three stripe widths were examined; 10, 50, and 100 {mu}m, and the maximum light output power of 0.94 W under cw operation at 20 C was achieved for the sample with a stripe width of 10 {mu}m. A super high-power laser diode array was fabricated using 11 of these high-performance laser chips, with a resultant output power of 6.1 W under cw operation at 20 C. This result represents the highest reported output power for blue-violet laser diodes. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Optical sensing system based on wireless paired emitter detector diode device and ionogels for lab-on-a-disc water quality analysis.

    Science.gov (United States)

    Czugala, Monika; Gorkin, Robert; Phelan, Thomas; Gaughran, Jennifer; Curto, Vincenzo Fabio; Ducrée, Jens; Diamond, Dermot; Benito-Lopez, Fernando

    2012-12-07

    This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor, is applied for quantitative pH and qualitative turbidity monitoring of water samples at point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems.

  14. Low-emittance Storage Rings

    CERN Document Server

    Wolski, Andrzej

    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.

  15. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  16. Spherical proton emitters

    International Nuclear Information System (INIS)

    Berg, S.; Semmes, P.B.; Nazarewicz, W.

    1997-01-01

    Various theoretical approaches to proton emission from spherical nuclei are investigated, and it is found that all the methods employed give very similar results. The calculated decay widths are found to be qualitatively insensitive to the parameters of the proton-nucleus potential, i.e., changing the potential parameters over a fairly large range typically changes the decay width by no more than a factor of ∼3. Proton half-lives of observed heavy proton emitters are, in general, well reproduced by spherical calculations with the spectroscopic factors calculated in the independent quasiparticle approximation. The quantitative agreement with experimental data obtained in our study requires that the parameters of the proton-nucleus potential be chosen carefully. It also suggests that deformed proton emitters will provide invaluable spectroscopic information on the angular momentum decomposition of single-proton orbitals in deformed nuclei. copyright 1997 The American Physical Society

  17. Dosimetry of internal emitters

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The Dosimetry of Internal Emitter Program endeavors to refine the correlation between radiation dose and observed biological effects. The program is presently engaged in the development of studies that will demonstrate the applicability of microdosimetry models developed under the Microdosimetry of Internal Sources Program. The program also provides guidance and assistance to Pacific Northwest Laboratory's Biology Department in the dosimetric analysis of internally deposited radionuclides. This report deals with alpha particle dosimetry plutonium 239 inhalation, and in vitro studies of chromosomal observations

  18. Nonintercepting emittance monitor

    International Nuclear Information System (INIS)

    Miller, R.H.; Clendenin, J.E.; James, M.B.; Sheppard, J.C.

    1983-08-01

    A nonintercepting emittance monitor is a helpful device for measuring and improving particle beams in accelerators and storage rings as it allows continuous monitoring of the beam's distribution in phase space, and perhaps closed loop computer control of the distributions. Stripline position monitors are being investigated for use as nonintercepting emittance monitors for a beam focused by a FODO array in the first 100 meters of our linear accelerator. The technique described here uses the signal from the four stripline probes of a single position monitor to measure the quadrupole mode of the wall current in the beam pipe. This current is a function of the quadrupole moment of the beam, sigma 2 /sub x/ - sigma 2 /sub y/. In general, six independent measurements of the quadrupole moment are necessary to determine the beam emittance. This technique is dependent on the characteristically large variations of sigma 2 /sub x/ - sigma 2 /sub y/ in a FODO array. It will not work in a focusing system where the beam is round at each focusing element

  19. Emittance compensation of CW DC-gun photoinjector

    International Nuclear Information System (INIS)

    Li Peng; Wu Dai; Xu Zhou; Li Ming; Yang Xingfan

    2011-01-01

    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)

  20. 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.

  1. Multiobjective optimization design of an rf gun based electron diffraction beam line

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2017-03-01

    Full Text Available Multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line comprised of a 100  MV/m 1.6-cell normal conducting rf (NCRF gun, as well as a nine-cell 2π/3 bunching cavity placed between two solenoids, have been performed. These include optimization of the normalized transverse emittance as a function of bunch charge, as well as optimization of the transverse coherence length as a function of the rms bunch length of the beam at the sample location for a fixed charge of 10^{6} electrons. Analysis of the resulting solutions is discussed in terms of the relevant scaling laws, and a detailed description of one of the resulting solutions from the coherence length optimizations is given. For a charge of 10^{6} electrons and final beam sizes of σ_{x}≥25  μm and σ_{t}≈5  fs, we found a relative coherence length of L_{c,x}/σ_{x}≈0.07 using direct optimization of the coherence length. Additionally, based on optimizations of the emittance as a function of final bunch length, we estimate the relative coherence length for bunch lengths of 30 and 100 fs to be roughly 0.1 and 0.2  nm/μm, respectively. Finally, using the scaling of the optimal emittance with bunch charge, for a charge of 10^{5} electrons, we estimate relative coherence lengths of 0.3, 0.5, and 0.92  nm/μm for final bunch lengths of 5, 30 and 100 fs, respectively.

  2. On the feasibility of sub-100 nm rad emittance measurement in plasma accelerators using permanent magnetic quadrupoles

    Science.gov (United States)

    Li, F.; Wu, Y. P.; Nie, Z.; Guo, B.; Zhang, X. H.; Huang, S.; Zhang, J.; Cheng, Z.; Ma, Y.; Fang, Y.; Zhang, C. J.; Wan, Y.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Gu, Y. Q.

    2018-01-01

    Low emittance (sub-100 nm rad) measurement of electron beams in plasma accelerators has been a challenging issue for a while. Among various measurement schemes, measurements based on single-shot quad-scan using permanent magnetic quadrupoles (PMQs) has been recently reported with emittance as low as ˜200 nm Weingartner (2012 Phys. Rev. Spec. Top. Accel. Beams 15 111302). However, the accuracy and reliability of this method have not been systematically analyzed. Such analysis is critical for evaluating the potential of sub-100 nm rad emittance measurement using any scheme. In this paper, we analyze the effects of various nonideal physical factors on the accuracy and reliability using the PMQ method. These factors include aberration induced by a high order field, PMQ misalignment and angular fluctuation of incoming beams. Our conclusions are as follows: (i) the aberrations caused by high order fields of PMQs are relatively weak for low emittance measurement as long as the PMQs are properly constructed. A series of PMQs were manufactured and measured at Tsinghua University, and using numerical simulations their high order field effects were found to be negligible . (ii) The largest measurement error of emittance is caused by the angular misalignment between PMQs. For low emittance measurement of ˜100 MeV beams, an angular alignment accuracy of 0.1° is necessary. This requirement can be eased for beams with higher energies. (iii) The transverse position misalignment of PMQs and angular fluctuation of incoming beams only cause a translational and rotational shift of measured signals, respectively, therefore, there is no effect on the measured value of emittance. (iv) The spatial resolution and efficiency of the detection system need to be properly designed to guarantee the accuracy of sub-100 nm rad emittance measurement.

  3. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    International Nuclear Information System (INIS)

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R.; Pease, R.L.; Fleetwood, D.M.; Kosier, S.L.

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps

  4. Emittance formula for slits and pepper-pot measurement

    International Nuclear Information System (INIS)

    Zhang, M.

    1996-10-01

    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

  5. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    Science.gov (United States)

    Wang, Daojing [Daly City, CA; Yang, Peidong [Kensington, CA; Kim, Woong [Seoul, KR; Fan, Rong [Pasadena, CA

    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.

  6. A low emittance configuration for spear

    International Nuclear Information System (INIS)

    Blumberg, L.N.; Cerino, J.; Harris, J.; Hettel, R.; Hofmann, A.; Liu, R.Z.; Stego, R.; Wiedemann, H.; Winick, H.

    1985-01-01

    The quality of synchrotron radiation beams from SPEAR, in particular the brilliance of undulator radiation, can be improved significantly by reducing the emittance of the stored electron beam. A reduction of the horizontal emittance by a factor of 3.5 to a value of 130 nanometer-radians (nm-r) at 3 GeV has been achieved by using stronger focussing, mainly in the horizontal plane. The low emittance configuration also reduces the dispersion and vertical beta functions in the straight sections, making them more suitable for wigglers. The higher betatron tunes lead to a larger phase advance between the two kickers, which has to be corrected during injection by shunting current from some quadrupoles. The configuration was optimized within SPEAR hardware limitations and tested for dynamic aperture with the tracking program PATRICIA. After implementation of this scheme, beam was successfully injected and accumulated. The measured emittance of the stored beam was in agreement with calculations. Presently the configuration is being made operational

  7. Single-shot measurements of low emittance beams from laser-plasma accelerators comparing two triggered injection methods

    Science.gov (United States)

    van Tilborg, Jeroen

    2017-10-01

    The success of laser plasma accelerator (LPA) based applications, such as a compact x-ray free electron laser (FEL), relies on the ability to produce electron beams with excellent 6D brightness, where brightness is defined as the ratio of charge to the product of the three normalized emittances. As such, parametric studies of the emittance of LPA generated electron beams are essential. Profiting from a stable and tunable LPA setup, combined with a carefully designed single-shot energy-dispersed emittance diagnostic, we present a direct comparison of charge dependent emittance measurements of electron beams generated by two different injection mechanisms: ionization injection and shock-induced density down-ramp injection. Both injection mechanisms have gained in popularity in recent years due to their demonstrated stable LPA performance. For the down-ramp injection configuration, normalized emittances a factor of two lower were recorded: less than 1 micron at spectral charge densities up to 2 pC/MeV. For both injection mechanisms, a contributing correlation of space charge to the emittance was identified. This measurement technique in general, and these results specifically, are critical to the evaluation of LPA injection methods and development of high-quality LPA beam lines worldwide. This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231, by the U.S. DOE NNSA, DNN R&D (NA22), by the National Science Foundation under Grant No. PHY-1415596, and by the Gordon and Betty Moore Foundation under Grant ID GBMF4898.

  8. On the role of diluted magnetic cobalt-doped ZnO electrodes in efficiency improvement of InGaN light emitters

    International Nuclear Information System (INIS)

    Liu, Hong-Ru; Wang, Shih-Yin; Ou, Sin-Liang; Wuu, Dong-Sing

    2016-01-01

    The 120-nm-thick cobalt-doped ZnO (Co-doped ZnO, CZO) dilute magnetic films deposited by pulsed laser deposition were employed as the n-electrodes for both lateral-type blue (450 nm) and green (520 nm) InGaN light emitters. In comparison to the conventional blue and green emitters, there were 15.9% and 17.7% enhancements in the output power (@350 mA) after fabricating the CZO n-electrode on the n-GaN layer. Observations on the role of CZO n-electrodes in efficiency improvement of InGaN light emitters were performed. Based on the results of Hall measurements, the carrier mobilities were 176 and 141 cm"2/V s when the electrons passed through the n-GaN and the patterned-CZO/n-GaN, respectively. By incorporating the CZO n-electrode into the InGaN light emitters, the electrons would be scattered because of the collisions between the magnetic atoms and the electrons as the device is driven, leading to the reduction of the electron mobility. Therefore, the excessively large mobility difference between electron and hole carriers occurred in the conventional InGaN light emitter can be efficiently decreased after preparing the CZO n-electrode on the n-GaN layer, resulting in the increment of carrier recombination rate and the improvement of light output power.

  9. Analysis of emittance compensation and simulation results to photo-cathode RF gun

    CERN Document Server

    LiuShengGuang

    2002-01-01

    The emittance compensation technology will be used on the photo-cathode RF gun for Shanghai SDUV-FEL. The space charge force and its effect on electron beam transverse emittance in RF gun is studied, the principle of emittance compensation in phase-space is discussed. The authors have designed a compensation solenoid and calculated its magnetic field distribution. Its performance has been studied by the code PARMELA. A simulation result indicates that the normalized transverse RMS emittance for electron beam of 1.5 nC is 1.612 pi mm centre dot mrad, electron energy E = 5.71 MeV

  10. Effective temperature of an ultracold electron source based on near-threshold photoionization.

    Science.gov (United States)

    Engelen, W J; Smakman, E P; Bakker, D J; Luiten, O J; Vredenbregt, E J D

    2014-01-01

    We present a detailed description of measurements of the effective temperature of a pulsed electron source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by electron beam waist scans, source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14 ± 3 K were found; for femtosecond photoionization, 30 ± 5 K is possible. With a typical source size of 25 μm, this results in electron bunches with a relative transverse coherence length in the 10⁻⁴ range and an emittance of a few nm rad. © 2013 Elsevier B.V. All rights reserved.

  11. Movement of Irrigation Water in Soil from a Surface Emitter

    Directory of Open Access Journals (Sweden)

    Ibrahim Abbas Dawood

    2016-09-01

    Full Text Available rickle irrigation is one of the most conservative irrigation techniques since it implies supplying water directly on the soil through emitters. Emitters dissipate energy of water at the end of the trickle irrigation system and provide water at emission points. The area wetted by an emitter depends upon the discharge of emitter, soil texture, initial soil water content, and soil permeability. The objectives of this research were to predict water distribution profiles through different soils for different conditions and quantify the distribution profiles in terms of main characteristics of soil and emitter. The wetting patterns were simulated at the end of each hour for a total time of application of 12 hrs, emitter discharges of 0.5, 0.75, 1, 2, 3, 4, and 5 lph, and five initial volumetric soil water contents. Simulation of water flow from a single surface emitter was carried out by using the numerically-based software Hydrus-2D/3D, Version 2.04. Two approaches were used in developing formulas to predict the domains of the wetted pattern. In order to verify the results obtained by implementing the software Hydrus-2D/3D a field experiment was conducted to measure the wetted diameter and compare measured values with simulated ones. The results of the research showed that the developed formulas to express the wetted diameter and depth in terms of emitter discharge, time of application, and initial soil water content are very general and can be used with very good accuracy.

  12. Emittance growth in rf linacs

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1979-01-01

    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

  13. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1990-12-01

    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

  14. On-line monitoring of base current and forward emitter current gain of the voltage regulator's serial pnp transistor in a radiation environment

    Directory of Open Access Journals (Sweden)

    Vukić Vladimir Đ.

    2012-01-01

    Full Text Available A method of on-line monitoring of the low-dropout voltage regulator's operation in a radiation environment is developed in this paper. The method had to enable detection of the circuit's degradation during exploitation, without terminating its operation in an ionizing radiation field. Moreover, it had to enable automatic measurement and data collection, as well as the detection of any considerable degradation, well before the monitored voltage regulator's malfunction. The principal parameters of the voltage regulator's operation that were monitored were the serial pnp transistor's base current and the forward emitter current gain. These parameters were procured indirectly, from the data on the voltage regulator's load and quiescent currents. Since the internal consumption current in moderately and heavily loaded devices was used, the quiescent current of a negligibly loaded voltage regulator of the same type served as a reference. Results acquired by on-line monitoring demonstrated marked agreement with the results acquired from examinations of the voltage regulator's maximum output current and minimum dropout voltage in a radiation environment. The results were particularly consistent in tests with heavily loaded devices. Results obtained for moderately loaded voltage regulators and the risks accompanying the application of the presented method, were also analyzed.

  15. Sub-nanometer emittance monitor for high brightness synchrotron radiation source

    International Nuclear Information System (INIS)

    Nakajima, K.

    1991-01-01

    Method of measuring a very small beam emittance in electron storage rings is presented. The monitor can sense an intrinsic emittance of beam particles by detecting the angular distribution of Compton scatterings of laser photons on beam electrons. It is possible to achieve measurement resolution smaller than 10 -9 m-rad without difficulty. (author)

  16. High-brightness electron guns for linac-based light sources

    International Nuclear Information System (INIS)

    Lewellen, J.W.

    2004-01-01

    Most proposed linac-based light sources, such as single-pass free-electron lasers and energy-recovery-linacs, require very high-brightness electron beams in order to achieve their design performance. These beam requirements must be achieved not on an occasional basis, but rather must be met by every bunch produced by the source over extended periods of time. It is widely assumed that the beam source will be a photocathode electron gun; the selection of accelerator technique (e.g., dc or rf) for the gun is more dependent on the application.The current state of the art of electron beam production is adequate but not ideal for the first generation of linac-based light sources, such as the Linac Coherent Light Source (LCLS) x-ray free-electron laser (X-FEL). For the next generation of linac-based light sources, an order of magnitude reduction in the transverse electron beam emittance is required to significantly reduce the cost of the facility. This is beyond the present state of the art, given the other beam properties that must be maintained. The requirements for current and future linac-based light source beam sources are presented here, along with a review of the present state of the art. A discussion of potential paths towards meeting future needs is presented at the conclusion.

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

    International Nuclear Information System (INIS)

    Liu Shengguang; Masafumi Fukuda; Sakae Araki; Nobuhiro Terunuma; Junji Urakawa

    2010-01-01

    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)

  18. Boundary conditions on the plasma emitter surface in the presence of a particle counter flow: I. Ion emitter

    Energy Technology Data Exchange (ETDEWEB)

    Astrelin, V. T., E-mail: V.T.Astrelin@inp.nsk.su; Kotelnikov, I. A. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2017-02-15

    Emission of positively charged ions from a plasma emitter irradiated by a counterpropagating electron beam is studied theoretically. A bipolar diode with a plasma emitter in which the ion temperature is lower than the electron temperature and the counter electron flow is extracted from the ion collector is calculated in the one-dimensional model. An analog of Bohm’s criterion for ion emission in the presence of a counterpropagating electron beam is derived. The limiting density of the counterpropagating beam in a bipolar diode operating in the space-charge-limited-emission regime is calculated. The full set of boundary conditions on the plasma emitter surface that are required for operation of the high-current optics module in numerical codes used to simulate charged particle sources is formulated.

  19. A numerical study of emittance growths in RF guns

    CERN Document Server

    Masuda, K; Sobajima, M; Kitagaki, J; Ohnishi, M; Toku, H; Yoshikawa, K

    1999-01-01

    A beam with greatly reduced emittance is required for further improvements of FELs, in particular, for FELs of shorter wavelengths, and of narrower bandwidths. From this viewpoint, the BNL/SLAC/UCLA 1.6-cell S-band photocathode RF gun performance characteristics were calculated, first in order to evaluate what may contribute to the emittance growths in photocathode RF guns. We developed an RF gun to produce an electron beam with an extremely low emittance, by using a 2-D simulation code. It is found that, by optimizing the laser injection phase, the drive laser spot radius and the cavity shape around the laser spot, the beam emittance by the 1.6-cell RF gun can be greatly reduced to 2.1 pi mm mrad, from the previous 4.4 pi mm mrad of the original shape.

  20. An Online Multisensor Data Fusion Framework for Radar Emitter Classification

    Directory of Open Access Journals (Sweden)

    Dongqing Zhou

    2016-01-01

    Full Text Available Radar emitter classification is a special application of data clustering for classifying unknown radar emitters in airborne electronic support system. In this paper, a novel online multisensor data fusion framework is proposed for radar emitter classification under the background of network centric warfare. The framework is composed of local processing and multisensor fusion processing, from which the rough and precise classification results are obtained, respectively. What is more, the proposed algorithm does not need prior knowledge and training process; it can dynamically update the number of the clusters and the cluster centers when new pulses arrive. At last, the experimental results show that the proposed framework is an efficacious way to solve radar emitter classification problem in networked warfare.

  1. 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.

  2. Emittance measurements in low energy ion storage rings

    Science.gov (United States)

    Hunt, J. R.; Carli, C.; Resta-López, J.; Welsch, C. P.

    2018-07-01

    The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurement faces several challenges: non-zero dispersion, non-Gaussian beam distributions due to effects of the electron cooler and various systematic errors such as closed orbit offsets and inaccurate rms momentum spread estimation. In addition, diffusion processes, such as intra-beam scattering might lead to emittance overestimates. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA.

  3. Beam dynamics in rf guns and emittance correction techniques

    International Nuclear Information System (INIS)

    Serafini, L.

    1994-01-01

    In this paper we present a general review of beam dynamics in a laser-driven rf gun. The peculiarity of such an accelerating structure versus other conventional multi-cell linac structures is underlined on the basis of the Panofsky-Wenzel theorem, which is found to give a theoretical background for the well known Kim's model. A basic explanation for some proposed methods to correct rf induced emittance growth is also derived from the theorem. We also present three emittance correction techniques for the recovery of space-charge induced emittance growth, namely the optimum distributed disk-like bunch technique, the use of rf spatial harmonics to correct spherical aberration induced by space charge forces and the technique of emittance filtering by clipping the electron beam. The expected performances regarding the beam quality achievable with different techniques, as predicted by scaling laws and simulations, are analyzed, and, where available, compared to experimental results. (orig.)

  4. Solution processeable organic-inorganic hybrids based on pyrene functionalized mixed cubic silsesquioxanes as emitters in OLEDs

    KAUST Repository

    Yang, Xiaohui

    2012-01-01

    Traditional materials for application in organic light emitting diodes (OLEDs) are primarily based on small molecules and polymers, with much fewer examples of intermediate molecular weight materials. Our interest lies in this intermediate molecular weight range, specifically in hybrids based on 3-dimensional silsesquioxane (SSQ) cores that represents a new class of versatile materials for application in solution processable OLEDs. We report here various SSQ based hybrids that are easily prepared in one high-yield step from the Heck coupling of commercially available 1-bromopyrene, and 1-bromo-4-heptylbenzene with octavinyl-T8-SSQ, and a mixture of octavinyl-T8-, decavinyl-T10- and dodecavinyl-T12-SSQ. The resulting materials offer numerous advantages for OLEDs including amorphous properties, high-glass-transition temperatures (T g), low polydispersity, solubility in common solvents, and high purity via column chromatography. Solution processed OLEDs prepared from the SSQ hybrids provide sky-blue emission with external quantum efficiencies and current efficiencies of 3.64% and 9.56 cd A -1 respectively. © 2012 The Royal Society of Chemistry.

  5. WE-AB-204-12: Dosimetry at the Sub-Cellular Scale of Auger-Electron Emitter 99m-Tc in a Mouse Single Thyroid Follicle Model

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A; Benabdallah, N; Desbree, A [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-roses (France)

    2015-06-15

    Purpose: To perform a dosimetry study at the sub-cellular scale of Auger-electron emitter 99m-Tc using a mouse single thyroid cellular model to investigate the contribution of the 99m-Tc Auger-electrons to the absorbed dose and possible link to the thyroid stunning in in vivo experiments in mice, recently reported in literature. Methods: The simulation of S-values for Auger-electron emitting radionuclides was performed using both the recent MCNP6 software and the Geant4-DNA extension of the Geant4 toolkit. The dosimetric calculations were validated through comparison with results from literature, using a simple model of a single cell consisting of two concentric spheres of unit density water and for six Auger-electron emitting radionuclides. Furthermore, the S-values were calculated using a single thyroid follicle model for uniformly distributed 123-I and 125-I radionuclides and compared with published S-values. After validation, the simulation of the S-values was performed for the 99m-Tc radionuclide within the several mouse thyroid follicle cellular compartments, considering the radiative and non-radiative transitions of the 99m-Tc radiation spectrum. Results: The calculated S-values using MCNP6 are in good agreement with the results from literature, validating its use for the 99m-Tc S-values calculations. The most significant absorbed dose corresponds to the case where the radionuclide is uniformly distributed in the follicular cell’s nucleus, with a S-value of 7.8 mGy/disintegration, due mainly to the absorbed Auger-electrons. The results show that, at a sub-cellular scale, the emitted X-rays and gamma particles do not contribute significantly to the absorbed dose. Conclusion: In this work, MCNP6 was validated for dosimetric studies at the sub-cellular scale. It was shown that the contribution of the Auger-electrons to the absorbed dose is important at this scale compared to the emitted photons’ contribution and can’t be neglected. The obtained S

  6. A Carbon Nanotube Electron Source Based Ionization Vacuum Gauge

    Energy Technology Data Exchange (ETDEWEB)

    Changkun Dong; Ganapati Myneni

    2003-10-01

    The results of fabrication and performance of an ionization vacuum gauge using a carbon nanotube (CNT) electron source are presented. The electron source was constructed with multi-wall nanotubes (MWNT), which were grown using thermal chemical vapor deposition (CVD) process. The electron emission of the source was stable in vacuum pressure up to 10-7 Torr, which is better than the metal field emitters. The measurement linearity of the gauge was better than {+-}10% from 10-6 to 10-10 Torr. The gauge sensitivity of 4 Torr-1 was achieved under 50 {micro}A electron emission in nitrogen. The gauge is expected to find applications in vacuum measurements from 10-7 Torr to below 10-11 Torr.

  7. HIGH-CURRENT ERL-BASED ELECTRON COOLING FOR RHIC

    International Nuclear Information System (INIS)

    BEN-ZVI, I.

    2005-01-01

    The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R and D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC

  8. Transverse and longitudinal emittance measurements in the ELSA linac

    International Nuclear Information System (INIS)

    Loulergue, A.; Dowell, D.H.; Joly, S.; De Brion, J.P.; Haouat, G.; Schumann, F.

    1997-01-01

    The ELSA RF linac photoinjector has been designed to deliver high-brightness electron beams. The present paper deals with the transverse and longitudinal emittance measurements, at different locations along the ELSA beam line, and the analysis of their variations as a function of the photoinjector parameters : magnetic field generated by the anode focusing lens, bunch charge and pulse duration. While transverse emittance has been already studied in other similar installations, there has been little study of the electron beam longitudinal dynamics. Experimental results are presented and compared to simulation-code expectations. For 2.0 nC, 85 A electron bunches, a normalized rms emittance of 2 π mm mrad and a brightness of 4.5 x 10 13 A/(π m rad) 2 at the linac exit have been measured as well as less than 10 keV rms energy spread (or less than 0.1% at 16.5 MeV). (orig.)

  9. 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).

  10. Development of methodology for detection of long lived alpha emitters in air based on simultaneous alpha and beta activity measurement

    International Nuclear Information System (INIS)

    Kaushik, Vivek; Rath, D.P.; Vinayagami, Bhakti; Ashokkumar, P.; Umashankar, C.; Gopalakrishnan, R.K.; Kulkarni, M.S.

    2018-01-01

    Interference of the radon and thoron progeny co-deposited on the filtration media is the long-standing problem related to prompt analyses in continuous air sampling or monitoring of any potential suspect radionuclides. The solutions to this problem have been quite diverse, and included, for example, simple gross-alpha counting, the use of beta-to-alpha ratios, and the use of alpha spectrum analyses. The techniques based on beta to alpha disintegration ratios make use of the naturally occurring alpha to beta disintegration ratios and departures therefrom. This ratio is found empirically to be relatively constant. With the help of the solution of differential equation, which govern the deposition of radionuclide on filter paper, one can easily estimate theoretically the behavior of the radon progeny alpha to beta disintegration (or count) rate ratio

  11. A Program to Generate a Particle Distribution from Emittance Measurements

    CERN Document Server

    Bouma, DS; Lallement, JB

    2010-01-01

    We have written a program to generate a particle distribution based on emittance measurements in x-x’ and y-y’. The accuracy of this program has been tested using real and constructed emittance measurements. Based on these tests, the distribution generated by the program can be used to accurately simulate the beam in multi-particle tracking codes, as an alternative to a Gaussian or uniform distribution.

  12. Remote detection of single emitters via optical waveguides

    Science.gov (United States)

    Then, Patrick; Razinskas, Gary; Feichtner, Thorsten; Haas, Philippe; Wild, Andreas; Bellini, Nicola; Osellame, Roberto; Cerullo, Giulio; Hecht, Bert

    2014-05-01

    The integration of lab-on-a-chip technologies with single-molecule detection techniques may enable new applications in analytical chemistry, biotechnology, and medicine. We describe a method based on the reciprocity theorem of electromagnetic theory to determine and optimize the detection efficiency of photons emitted by single quantum emitters through truncated dielectric waveguides of arbitrary shape positioned in their proximity. We demonstrate experimentally that detection of single quantum emitters via such waveguides is possible, confirming the predicted behavior of the detection efficiency. Our findings blaze the trail towards efficient lensless single-emitter detection compatible with large-scale optofluidic integration.

  13. Electrohydrodynamic emitters of ion beams

    International Nuclear Information System (INIS)

    Dudnikov, V.G.; Shabalin, A.L.

    1990-01-01

    Physical processes determining generation of ion beams with high emission current density in electrohydrodynamic emitters are considered. Electrohydrodynamic effects developing in ion emission features and kinetics of ion interaction in beams with high density are discussed. Factors determining the size of the emission zone, emission stability at high and low currents, cluster generation, increase of energy spread and decrease of brightness are analyzed. Problems on practical provision of stable EHD emitter functioning are considered. 94 refs.; 8 figs.; 1 tab

  14. Reducing longitudinal emittance growth in RFQ accelerators

    International Nuclear Information System (INIS)

    Koscielniak, S.

    1994-08-01

    Bunching and capture of a monochromatic beam into an rf bucket inevitably lead to substantial emittance growth through the mechanisms of filamentation and non-adiabatic variation of parameters. We describe a three step strategy for minimizing this growth, based on a clear understanding of the non-linear beam dynamics, and apply to acceleration of heavy ions with Z/A = 1/60 (and initial kinetic energy 60 keV/u) in a radio frequency quadrupole (RFQ) operating at 25 MHz. We also describe a scheme, to further reduce the emittance, based upon the use of an external RFQ-type prebuncher before the main accelerator. The external unit permits the bunching voltage to be reduced, to inject into a moving bucket, and to reduce the structure length. (author). 7 refs., 6 figs

  15. Mesoscopic quantum emitters coupled to plasmonic nanostructures

    DEFF Research Database (Denmark)

    Andersen, Mads Lykke

    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......This thesis reports research on quantum dots coupled to dielectric and plasmonic nano-structures by way of nano-structure fabrication, optical measurements, and theoretical modeling. To study light-matter interaction, plasmonic gap waveguides with nanometer dimensions as well as samples for studies...... to allow for e- cient plasmon-based single-photon sources. Theoretical studies of coupling and propagation properties of plasmonic waveguides reveal that a high-refractive index of the medium surrounding the emitter, e.g. nGaAs = 3.5, limits the realizability of ecient plasmon-based single-photon sources...

  16. Beam emittance reduction during operation of Indus-2

    Energy Technology Data Exchange (ETDEWEB)

    Fakhri, Ali Akbar, E-mail: fakhri@rrcat.gov.in; Kant, Pradeep; Ghodke, A. D.; Singh, Gurnam [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2015-11-15

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed.

  17. Experimental investigation of thermal emittance components of copper photocathode

    Directory of Open Access Journals (Sweden)

    H. J. Qian

    2012-04-01

    Full Text Available With progress of photoinjector technology, thermal emittance has become the primary limitation of electron beam brightness. Extensive efforts have been devoted to study thermal emittance, but experiment results differ between research groups and few can be well interpreted. Besides the ambiguity of photoemission mechanism, variations of cathode surface conditions during cathode preparation, such as work function, field enhancement factor, and surface roughness, will cause thermal emittance differences. In this paper, we report an experimental study of electric field dependence of copper cathode quantum efficiency (QE and thermal emittance in a radio frequency (rf gun, through which in situ cathode surface parameters and thermal emittance contributions from photon energy, Schottky effect, and surface roughness are extracted. It is found the QE of a copper cathode illuminated by a 266 nm UV laser increased substantially to 1.5×10^{-4} after cathode cleaning during rf conditioning, and a copper work function of 4.16 eV, which is much lower than nominal value (4.65 eV, was measured. Experimental results also show a thermal emittance growth as much as 0.92  mm mrad/mm at 50  MV/m due to the cathode surface roughness effect, which is consistent with cathode surface morphology measurements.

  18. Accelerator based production of auger-electron-emitting isotopes for radionuclide therapy

    International Nuclear Information System (INIS)

    Thisgaard, H.

    2008-08-01

    In this research project the focus has been on the identification and production of new, unconventional Auger-electron-emitting isotopes for targeted radionuclide therapy of cancer. Based on 1st principles dosimetry calculations on the subcellular level, the Auger-emitter 119Sb has been identified as a potent candidate for therapy. The corresponding imaging analogue 117Sb has been shown from planar scintigraphy and single-photon emission computed tomography (SPECT) to be suitable for SPECT-based dosimetry of a future Sb-labeled radiopharmaceutical. The production method of these radioisotopes has been developed using a low-energy cyclotron via the nuclear reactions 119Sn(p,n)119Sb and 117Sn(p,n)117Sb including measurements of the excitation function for the former reaction. Moreover, a new high-yield radiochemical separation method has been developed to allow the subsequent separation of the produced 119Sb from the enriched 119Sn target material with high radionuclidic- and chemical purity. A method that also allows efficient recovery of the 119Sn for recycling. To demonstrate the ability of producing therapeutic quantities of 119Sb and other radioisotopes for therapy with a low-energy cyclotron, two new 'High Power' cyclotron targets were developed in this study. The target development was primarily based on theoretical thermal modeling calculations using finite-element-analysis software. With these targets, I have shown that it will be possible to produce several tens of GBq of therapeutics isotopes (e.g. 119Sb or 64Cu) using the PETtrace cyclotron commonly found at the larger PET-centers in the hospitals. Finally, research in a new method to measure the radiotoxicity of Auger-emitters invitro using cellular microinjection has been carried out. The purpose of this method is to be able to experimentally evaluate and compare the potency of the new and unconventional Auger-emitters (e.g. 119Sb). However, due to experimental complications, the development of this

  19. Accelerator based production of auger-electron-emitting isotopes for radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Thisgaard, H.

    2008-08-15

    In this research project the focus has been on the identification and production of new, unconventional Auger-electron-emitting isotopes for targeted radionuclide therapy of cancer. Based on 1st principles dosimetry calculations on the subcellular level, the Auger-emitter 119Sb has been identified as a potent candidate for therapy. The corresponding imaging analogue 117Sb has been shown from planar scintigraphy and single-photon emission computed tomography (SPECT) to be suitable for SPECT-based dosimetry of a future Sb-labeled radiopharmaceutical. The production method of these radioisotopes has been developed using a low-energy cyclotron via the nuclear reactions 119Sn(p,n)119Sb and 117Sn(p,n)117Sb including measurements of the excitation function for the former reaction. Moreover, a new high-yield radiochemical separation method has been developed to allow the subsequent separation of the produced 119Sb from the enriched 119Sn target material with high radionuclidic- and chemical purity. A method that also allows efficient recovery of the 119Sn for recycling. To demonstrate the ability of producing therapeutic quantities of 119Sb and other radioisotopes for therapy with a low-energy cyclotron, two new 'High Power' cyclotron targets were developed in this study. The target development was primarily based on theoretical thermal modeling calculations using finite-element-analysis software. With these targets, I have shown that it will be possible to produce several tens of GBq of therapeutics isotopes (e.g. 119Sb or 64Cu) using the PETtrace cyclotron commonly found at the larger PET-centers in the hospitals. Finally, research in a new method to measure the radiotoxicity of Auger-emitters invitro using cellular microinjection has been carried out. The purpose of this method is to be able to experimentally evaluate and compare the potency of the new and unconventional Auger-emitters (e.g. 119Sb). However, due to experimental complications, the development

  20. An explosive-emitter cathode produced using the heavy ion track technique

    International Nuclear Information System (INIS)

    Akap'ev, G.N.; Korenev, S.A.

    1988-01-01

    A cathode based on thin metallic foils with a homogeneous needle surface is described. The cathode was manufactured using the heavy ion track technique which permits the production of cathodes with an unlimited area and a needle density ranging from about 10 3 to 10 9 needles per cm 2 . An electron gun using this type of cathode has a current of 200-900 A and an energy of 100-300 keV. The cross section of the electron beam is fairly uniform. It is shown that needle emitters of similar shape and size play the principal role in forming a homogeneous cathode plasma

  1. Investigations on cermet electrodes for thermionic emitters

    International Nuclear Information System (INIS)

    Schmidt, D.; Nazare, S.

    1975-01-01

    Unstable Ba 2 CaWO 6 -W with their own supply of Ba, as well as stable UO 2 -Mo-emitter cermets that have to be operated with an external Ba-source, have been prepared by axial hot pressing. The relevant properties of these cermets such as electrical resistivity and thermal expansion are reported and compared with theoretical predictions. The electron emission of these materials is discussed on the basis of the surface films formed. It provides the basis for optimising the behavior of these materials

  2. Computing Eigen-Emittances from Tracking Data

    Energy Technology Data Exchange (ETDEWEB)

    Alexahin, Y. [Fermilab

    2014-09-18

    In a strongly nonlinear system the particle distribution in the phase space may develop long tails which contribution to the covariance (sigma) matrix should be suppressed for a correct estimate of the beam emittance. A method is offered based on Gaussian approximation of the original particle distribution in the phase space (Klimontovich distribution) which leads to an equation for the sigma matrix which provides efficient suppression of the tails and cannot be obtained by introducing weights. This equation is easily solved by iterations in the multi-dimensional case. It is also shown how the eigen-emittances and coupled optics functions can be retrieved from the sigma matrix in a strongly coupled system. Finally, the developed algorithm is applied to 6D ionization cooling of muons in HFOFO channel.

  3. Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, J.; Ruan, J.; Johnson, A.S.; Thurman-Keup, R.; Lumpkin, A.H.; Santucci, J.; Sun, Y.-E; Maxwell, T.; Edwards, H.; /Fermilab

    2012-05-01

    Emittance exchange has been proposed to increase the performance of free electron lasers by tailoring the phase space of an electron beam. The principle of emittance exchange - where the transverse phase space of the electron beam is exchanged with the longitudinal phase space - has been demonstrated recently at the A0 photoinjector. The experiment used a low charge bunch (250 pC) with no energy chirp. Theory predicts an improvement in the emittance exchange scheme when the incoming beam has an energy chirp imparted on it. The energy chirp helps to overcome the thick lens effect of the deflecting mode cavity and other second order effects that might lead to an incomplete emittance exchange at higher charges. In this work, we report experimental and simulation results from operating the emittance exchange beam line using an energy chirped beam with higher charge (500 pC) at different RF-chirp settings.

  4. Feedback scheme for kink instability in ERL based electron ion collider

    International Nuclear Information System (INIS)

    Hao, Y.; Litvinenko, V.N.; Ptitsyn, V.

    2011-01-01

    Kink instability presents one of the limiting factors from achieving higher luminosity in ERL based electron ion collider (EIC). However, we can take advantage of the flexibility of the linac and design a feedback system to cure the instability. This scheme raises the threshold of kink instability dramatically and provides opportunity for higher luminosity. We studied the effectiveness of this system and its dependence on the amplitude and phase of the feedback. In this paper we present results of theses studies of this scheme and describe its theoretical and practical limitations. The main advantage of an energy recovery linac (ERL) based electron ion collider (EIC) over a ring-ring type counterpart is the higher achievable luminosity. In ERL-based version, one electron beam collides with the opposing ion beam only once so that the beam-beam parameter can largely exceed the usual limitation in an electron collider ring, while the beam-beam parameter for the ion beam remains small values. The resulting luminosity may be enhanced by one order of magnitude. The beam dynamics related challenges also arise as the luminosity boost in ERL based EIC due to the significant beam-beam effect on the electron beam. The effects on the electron beam include the additional large beam-beam tune shift and nonlinear emittance growth, which are discussed. The ion beam may develop a head-tail type instability, referred as 'kink instability', through the interaction with the electron beam. In this paper, we discuss the feasibility of an active feedback system to mitigate the kink instability, by taking advantage of the flexibility of ERL. Throughout the paper, we will discuss the collision between proton and electron beam. Any other ion species can be scaled by its charge Z and ion mass A.

  5. Transverse emittance and phase space program developed for use at the Fermilab A0 Photoinjector

    International Nuclear Information System (INIS)

    Thurman-Keup, R.; Johnson, A.S.; Lumpkin, A.H.; Ruan, J.

    2011-01-01

    The Fermilab A0 Photoinjector is a 16 MeV high intensity, high brightness electron linac developed for advanced accelerator R and D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties. An integral part of accelerator research is a measurement of the beam phase space. Measurements of the transverse phase space can be accomplished by a variety of methods including multiple screens separated by drift spaces, or by sampling phase space via pepper pots or slits. In any case, the measurement of the phase space parameters, in particular the emittance, can be drastically simplified and sped up by automating the measurement in an intuitive fashion utilizing a graphical interface. At the A0 Photoinjector (A0PI), the control system is DOOCS, which originated at DESY. In addition, there is a library for interfacing to MATLAB, a graphically capable numerical analysis package sold by The Mathworks. It is this graphical package which was chosen as the basis for a graphical phase space measurement system due to its combination of analysis and display capabilities.

  6. Transverse emittance growth in staged laser-wakefield acceleration

    Directory of Open Access Journals (Sweden)

    T. Mehrling

    2012-11-01

    Full Text Available We present a study on the emittance evolution of electron bunches, externally injected into laser-driven plasma waves using the three-dimensional particle-in-cell (PIC code OSIRIS. Results show order-of-magnitude transverse emittance growth during the injection process, if the electron bunch is not matched to its intrinsic betatron motion inside the wakefield. This behavior is supported by analytic theory reproducing the simulation data to a percent level. The length over which the full emittance growth develops is found to be less than or comparable to the typical dimension of a single plasma module in current multistage designs. In addition, the analytic theory enables the quantitative prediction of emittance degradation in two consecutive accelerators coupled by free-drift sections, excluding this as a scheme for effective emittance-growth suppression, and thus suggests the necessity of beam-matching sections between acceleration stages with fundamental implications on the overall design of staged laser-wakefield accelerators.

  7. A Carbon Nanotube-based NEMS Parametric Amplifier for Enhanced Radio Wave Detection and Electronic Signal Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, B J; Sussman, A; Zettl, A [Physics Department, University of California, Berkeley, CA 94720 (United States); Mickelson, W, E-mail: azettl@berkeley.edu [Center of Integrated Nanomechanical Systems, University of California, Berkeley, CA 94720 (United States)

    2011-07-20

    We propose a scheme for a parametric amplifier based on a single suspended carbon nanotube field-emitter. This novel electromechanical nanotube device acts as a phase-sensitive, variable-gain, band-pass-filtering amplifier for electronic signal processing and, at the same time, can operate as a variable-sensitivity, tuneable detector and transducer of radio frequency electromagnetic waves. The amplifier can exhibit infinite gain at pumping voltages much less than 10 Volts. Additionally, the amplifier's low overhead power consumption (10-1000 nW) make it exceptionally attractive for ultra-low-power applications.

  8. A Carbon Nanotube-based NEMS Parametric Amplifier for Enhanced Radio Wave Detection and Electronic Signal Amplification

    International Nuclear Information System (INIS)

    Aleman, B J; Sussman, A; Zettl, A; Mickelson, W

    2011-01-01

    We propose a scheme for a parametric amplifier based on a single suspended carbon nanotube field-emitter. This novel electromechanical nanotube device acts as a phase-sensitive, variable-gain, band-pass-filtering amplifier for electronic signal processing and, at the same time, can operate as a variable-sensitivity, tuneable detector and transducer of radio frequency electromagnetic waves. The amplifier can exhibit infinite gain at pumping voltages much less than 10 Volts. Additionally, the amplifier's low overhead power consumption (10-1000 nW) make it exceptionally attractive for ultra-low-power applications.

  9. 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.

  10. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  11. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  12. Growth and characterization of ZnCdMgSe-based green light emitters and distributed Bragg reflectors towards II-VI based semiconductor disk lasers

    International Nuclear Information System (INIS)

    De Jesus, Joel; Gayen, Swapan K.; Garcia, Thor A.; Tamargo, Maria C.; Kartazaev, Vladimir; Jones, Brynmor E.; Schlosser, Peter J.; Hastie, Jennifer E.

    2015-01-01

    We report the structural and optical properties of molecular beam epitaxy grown II-VI semiconductor multiple quantum well (MQW) structures and distributed Bragg reflector (DBR) on InP substrates for application in developing optically-pumped semiconductor disk lasers (SDLs) operating in the green spectral range. One sample was grown directly on an InP substrate with an InGaAs buffer layer, while another had a 5-period ZnCdMgSe-based DBR grown on the InGaAs/InP substrate. X-ray diffraction and scanning electron microscopy measurements revealed sharp superlattice peaks and abrupt layer interfaces, while steady-state photoluminescence measurements demonstrated surface emission between 540-570 nm. Under pulsed excitation both samples exhibited features of amplified spontaneous emission (ASE) or stimulated emission, accompanied by luminescence lifetime shortening. The sample with the DBR showed higher surface luminescence and the onset of ASE at lower pump power. To further explore the design and performance of a ZnCdMgSe-based DBR, a 20-period DBR was grown and a reflectivity of 83% was obtained at ∝560 nm. We estimate that a DBR with ∝40 periods would be needed for optimal performance in a SDL using these materials. These results show the potential of II-VI MQW structures on InP substrates for the development of SDLs operational in the green-yellow wavelength range. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Generic conditions for suppressing the coherent synchrotron radiation induced emittance growth in a two-dipole achromat

    Science.gov (United States)

    Jiao, Yi; Cui, Xiaohao; Huang, Xiyang; Xu, Gang

    2014-06-01

    The effect of the coherent synchrotron radiation (CSR) becomes evident, and leads to increased beam energy spread and transverse emittance dilution, as both the emittance and bunch length of the electron beams are continuously pushed down in present and forthcoming high-brightness light sources and linear colliders. Suppressing this effect is important to preserve the expected machine performance. Methods of the R-matrix analysis and the Courant-Snyder formalism analysis have been proposed to evaluate and to suppress the emittance growth due to CSR in achromatic cells. In this paper a few important modifications are made on these two methods, which enable us to prove that these two methods are equivalent to each other. With the modified analysis, we obtain explicit and generic conditions of cancelling the CSR-driven emittance excitation in a single achromat consisting of two dipoles of arbitrary bending angles. In spite of the fact that the analysis constrains itself in a linear regime, based on the assumption that CSR-induced particle energy deviation is proportional to both θ and ρ1/3, with θ being the bending angle and ρ the bending radius, it is demonstrated through ELEGANT simulations that the conditions derived from this analysis are still effective in suppressing the emittance growth when a more detailed one-dimensional CSR model is considered. In addition, it illustrates that the emittance growth can be reduced to a lower level with the proposed conditions than with the other two approaches, such as matching the beam envelope to the CSR kick and setting the cell-to-cell betatron phase advance to an appropriate value.

  14. Intelligent Variable Emittance Panels Using New, ""True"" Solid Electrolyte, Phase II

    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...

  15. Secondary electron ion source neutron generator

    Science.gov (United States)

    Brainard, John P.; McCollister, Daryl R.

    1998-01-01

    A neutron generator employing an electron emitter, an ion source bombarded by the electrons from the electron emitter, a plasma containment zone, and a target situated between the plasma containment zone and the electron emitter. The target contains occluded deuterium, tritium, or a mixture thereof

  16. Emittance growth of bunched beams in bends

    International Nuclear Information System (INIS)

    Carlsten, B.E.; Raubenheimer, T.O.

    1995-01-01

    Talman [Phys. Rev. Lett. 56, 1429 (1986)] has proposed a novel relativistic effect that occurs when a charged particle beam is bent in the magnetic field from an external dipole. The consequence of this effect is that the space-charge forces from the particles do not exhibit the usual inverse-square energy dependence and some part of them are, in fact, independent of energy. This led to speculation that this effect could introduce significant emittance growth for a bending electron beam. Subsequently, it was shown that this effect's influence on the beam's transverse motion is canceled for a dc beam by a potential depression within the beam (to first order in the beam radius divided by the bend radius). In this paper, we extend the analysis to include short bunch lengths (as compared to the beam pipe dimensions) and find that there is no longer the cancellation for forces both transverse to and in the direction of motion. We provide an estimate for the emittance growth as a function of bend angle, beam radius, and current, and for magnetic compression of an electron bunch

  17. Data base systems in electronic design engineering

    Science.gov (United States)

    Williams, D.

    1980-01-01

    The concepts of an integrated design data base system (DBMS) as it might apply to an electronic design company are discussed. Data elements of documentation, project specifications, project tracking, firmware, software, electronic and mechanical design can be integrated and managed through a single DBMS. Combining the attributes of a DBMS data handler with specialized systems and functional data can provide users with maximum flexibility, reduced redundancy, and increased overall systems performance. Although some system overhead is lost due to redundancy in transitory data, it is believed the combination of the two data types is advisable rather than trying to do all data handling through a single DBMS.

  18. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1992-02-01

    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

  19. 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.

  20. Communication: Electron ionization of DNA bases

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, M. A.; Krishnakumar, E., E-mail: ekkumar@tifr.res.in

    2016-04-28

    No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space.

  1. Emittances Studies at the Fermilab/NICADD Photoinjector Laboratory

    CERN Document Server

    Tikhoplav, Rodion; Melissinos, A C; Regis-Guy Piot, Philippe

    2005-01-01

    The Fermilab/NICADD photoinjector incorporates an L-band rf-gun capable of generating 1-10 nC bunches. The bunches are then accelerated to 16 MeV with a TESLA superconducting cavity. In the present paper we present parametric studies of transverse emittances and energy spread for a various operating points of the electron source (RF-gun E-field, laser length and spot size, and solenoid settings). We especially study the impact, on transverse emittance, of Gaussian and Plateau temporal distribution of the photocathode drive-laser.

  2. Auger electron emitter against multiple myeloma - targeted endo-radio-therapy with {sup 125}I-labeled thymidine analogue 5-iodo-4'-thio-2'-deoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Morgenroth, Agnieszka, E-mail: amorgenroth@ukaachen.de [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Dinger, Cornelia; Zlatopolskiy, Boris D.; Al-Momani, Ehab; Glatting, Gerhard [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Mottaghy, Felix M. [Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Reske, Sven N. [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany)

    2011-10-15

    Introduction: Multiple myeloma (MM) is a plasma cell malignancy characterized by accumulation of malignant, terminally differentiated B cells in the bone marrow. Despite advances in therapy, MM remains an incurable disease. Novel therapeutic approaches are, therefore, urgently needed. Auger electron-emitting radiopharmaceuticals are attractive for targeted nano-irradiation therapy, given that DNA of malignant cells is selectively addressed. Here we evaluated the antimyeloma potential of the Auger electron-emitting thymidine analogue {sup 125}I-labeled 5-iodo-4'-thio-2'-deoxyuridine ([{sup 125}I]ITdU). Methods: Cellular uptake and DNA incorporation of [{sup 125}I]ITdU were determined in fluorodeoxyuridine-pretreated KMS12BM, U266, dexamethasone-sensitive MM1.S and -resistant MM1.R cell lines. The effect of stimulation with interleukin 6 (IL6) or insulin-like growth factor 1 (IGF1) on the intracellular incorporation of [{sup 125}I]ITdU was investigated in cytokine-sensitive MM1.S and MM1.R cell lines. Apoptotic cells were identified using Annexin V. Cleavage of caspase 3 and PARP was visualized by Western blot. DNA fragmentation was investigated using laddering assay. Therapeutic efficiency of [{sup 125}I]ITdU was proven by clonogenic assay. Results: [{sup 125}I]ITdU was shown to be efficiently incorporated into DNA of malignant cells, providing a promising mechanism for delivering highly toxic Auger radiation emitters into tumor DNA. [{sup 125}I]ITdU had a potent antimyeloma effect in cell lines representing distinct disease stages and, importantly, in cell lines sensitive or resistant to the conventional therapeutic agent, but was not toxic for normal plasma and bone marrow stromal cells. Furthermore, [{sup 125}I]ITdU abrogated the protective actions of IL6 and IGF1 on MM cells. [{sup 125}I]ITdU induced massive damage in the DNA of malignant plasma cells, which resulted in efficient inhibition of clonogenic growth. Conclusion: These studies may provide a

  3. Emittance studies of the BNL/SLAC/UCLA 1.6 cell photocathode rf gun

    International Nuclear Information System (INIS)

    Palmer, D.T.; Miller, R.H.; Wang, X.J.

    1997-01-01

    The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 micros. The transverse emittance of the photoelectron beam were measured for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, ε o , of the copper cathode has been measured

  4. 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

  5. Measuring emittances and sigma matrices

    International Nuclear Information System (INIS)

    Rees, J.; Rivkin, L.

    1984-03-01

    The method used for measuring emittance at the SLAC Linac and the linear collider damping ring is described. The basis of the method is derived using one two-by-two matrix to specify the state of the input beam (sigma matrix) and another to describe the lens-drift transport system (R-matrix)

  6. Emittance growth and tune spectra at PETRA III

    International Nuclear Information System (INIS)

    Wanzenberg, R.

    2011-08-01

    At DESY the PETRA ring has been converted into a synchrotron radiation facility, called PETRA III. 20 damping wigglers have been installed to achieve an emittance of 1 nm. The commissioning with beam started in April 2009 and user runs have been started in 2010. The design current is 100 mA and the bunch to bunch distance is 8 ns for one particular filling pattern with 960 bunches. At a current of about 50 mA a strong vertical emittance increase has been observed. During machine studies it was found that the emittance increase depends strongly on the bunch filling pattern. For the user operation a filling scheme has been found which mitigates the increase of the vertical emittance. In August 2010 PETRA III has been operated without damping wigglers for one week. The vertical emittance growth was not significantly smaller without wigglers. Furthermore tune spectra at PETRA III show characteristic lines which have been observed at other storage rings in the connection with electron clouds. Measurements at PETRA III are presented for different bunch filling patterns and with and without wiggler magnets. (orig.)

  7. An FPGA-Based Electronic Cochlea

    Directory of Open Access Journals (Sweden)

    M. P. Leong

    2003-06-01

    Full Text Available A module generator which can produce an FPGA-based implementation of an electronic cochlea filter with arbitrary precision is presented. Although hardware implementations of electronic cochlea models have traditionally used analog VLSI as the implementation medium due to their small area, high speed, and low power consumption, FPGA-based implementations offer shorter design times, improved dynamic range, higher accuracy, and a simpler computer interface. The tool presented takes filter coefficients as input and produces a synthesizable VHDL description of an application-optimized design as output. Furthermore, the tool can use simulation test vectors in order to determine the appropriate scaling of the fixed point precision parameters for each filter. The resulting model can be used as an accelerator for research in audition or as the front-end for embedded auditory signal processing systems. The application of this module generator to a real-time cochleagram display is also presented.

  8. The fabrication and evaluation of diamond cold cathodes for field emitter display applications

    International Nuclear Information System (INIS)

    Fox, N.A.

    1998-08-01

    mechanism may operate that facilitates the field emission of electrons from the p-diamond side of the interface into free space. A number of aspects relating to the junction structure could be considered to improve its performance as a cold cathode emitter: a p-diamond layer exhibiting a higher carrier mobility; a controlled number, distribution and type of defect residing at the interface; an emission surface conditioned to exhibit a stable Negative Electron Affinity (NEA). To more clearly define the operation of a diamond cold cathode emitter based upon this junction structure further exploratory effort would be required to be undertaken in the future. (author)

  9. Monte Carlo Transverse Emittance Study on Cs2Te

    CERN Document Server

    Banfi, F; Galimberti, P G; Giannetti, C; Pagliara, S; Parmigiani, F; Pedersoli, E

    2005-01-01

    A Monte Carlo study of electron transport in Cs2Te films is performed to investigate the transverse emittance epsilon at the cathode surface. We find the photoemitted electron angular distribution and explain the physical mechanism involved in the process, a mechanism hindered by the statistical nature of the Monte Carlo method. The effects of electron-phonon scattering are discussed. The transverse emittance is calculated for different radiation wavelengths and a laser spot size of 1.5*10(-3) m. For a laser radiation at 265 nm we find epsilon = 0.56 mm-mrad. The dependence of epsilon and the quantum yield on the electron affinity Ea is also investigated. The data shows the importance of aging/contamination on the material.

  10. Zope based electronic operation log system - Zlog

    International Nuclear Information System (INIS)

    Yoshii, K.; Satoh, Y.; Kitabayashi, T.

    2004-01-01

    Since January 2004, the Zope based electronic operation logging system, named Zlog, has been running at the KEKB and AR accelerator facilities. Since Zope is the python based open source web application server software and python language is familiar for the members in the KEKB accelerator control group, we have developed the Zlog system rapidly. In this paper, we report the development history and the present status of Zlog system. Also we show some general plug-in components, called Zope products, have been useful for our Zlog development. (author)

  11. Resonant plasmonic terahertz detection in vertical graphene-base hot-electron transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhii, V. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University and Institute of Ultra High Frequency Semiconductor Electronics of RAS, Moscow 111005 (Russian Federation); Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Mitin, V. [Department of Electrical Engineering, University at Buffalo, SUNY, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Department of Electrical, Computer, and System Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-28

    We analyze dynamic properties of vertical graphene-base hot-electron transistors (GB-HETs) and consider their operation as detectors of terahertz (THz) radiation using the developed device model. The GB-HET model accounts for the tunneling electron injection from the emitter, electron propagation across the barrier layers with the partial capture into the GB, and the self-consistent oscillations of the electric potential and the hole density in the GB (plasma oscillations), as well as the quantum capacitance and the electron transit-time effects. Using the proposed device model, we calculate the responsivity of GB-HETs operating as THz detectors as a function of the signal frequency, applied bias voltages, and the structural parameters. The inclusion of the plasmonic effect leads to the possibility of the GB-HET operation at the frequencies significantly exceeding those limited by the characteristic RC-time. It is found that the responsivity of GB-HETs with a sufficiently perfect GB exhibits sharp resonant maxima in the THz range of frequencies associated with the excitation of plasma oscillations. The positions of these maxima are controlled by the applied bias voltages. The GB-HETs can compete with and even surpass other plasmonic THz detectors.

  12. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    of a novel epitaxial structure design. The layered structure is based on chirping the barrier layer thickness of the over grown quantum dash layer, in a multi-stack quantum dash/barrier active region, with the aim of inducing additional inhomogeneity. Based on material-structure and device characterization, enhanced lasing-emission bandwidth is achieved from the narrow (2 u m)ridge-waveguide LDs as a result of the formation of multiple ensembles of quantum dashes that are electronically different, in addition to improved device performance. Moreover, realization of SLDs from this device structure demonstrated extra-ordinary emission bandwidth covering the entire international telecommunication union (O- to U-) bands. This accomplishment is a collective emission from quantum wells and quantum dashes of the device active region. All these results lead to a step forward in the eventual realization of more than 150 nm lasing bandwidth from a single semiconductor laser diode.

  13. Multi-gated field emitters for a micro-column

    International Nuclear Information System (INIS)

    Mimura, Hidenori; Kioke, Akifumi; Aoki, Toru; Neo, Yoichiro; Yoshida, Tomoya; Nagao, Masayoshi

    2011-01-01

    We have developed a multi-gated field emitter (FE) such as a quadruple-gated FE with a three-stacked electrode lens and a quintuple-gated FE with a four-stacked electrode lens. Both the FEs can focus the electron beam. However, the quintuple-gated FE has a stronger electron convergence than the quadruple-gated FE, and a beam crossover is clearly observed for the quintuple-gated FE.

  14. Dosimetry of internal emitters - quo vadis?

    International Nuclear Information System (INIS)

    Reddy, A.R.; Nagaratnam, A.; Jain, S.C.; Gupta, M.M.; Mehta, S.C.

    1999-01-01

    The dosimetry of internally administered radiopharmaceuticals in nuclear medicine procedures using MIRD formalisms and dosimetry in the case of intakes of radionuclides and ICRP methodology for the purpose of radiological protection are well established working practices. It should, however, be remembered that dose or dose coefficients calculated refer to a reference individual, defined in terms of a mathematical phantom established on the basis of certain biokinetic reference parameters. The reference individual represents a typical caucasian adult of West Europe or North American origin. Recently, some attempts have been made to define a Reference Asian and a Reference Indian individual and to assess the effects of anatomical differences and changes in the biokinetics of radiopharmaceuticals and other radionuclides in these different reference individuals on the estimation of dose and dose coefficients in relation to the intake of internal radionuclides. The assessment of doses to the embryo/fetus due to intake of radionuclides by pregnant women, local dose estimates, microdosimetry, radiobiology and radiation protection aspects relating to Auger electron emitters represent other areas of active research in the area of dosimetry of internal emitters. The present review summarises these different aspects of work. (orig.) [de

  15. Commissioning of the SPARC Movable Emittance Meter and Its First Operation at PITZ

    CERN Document Server

    Catani, L; Cianchi, A

    2005-01-01

    For the SPARC Project a novel diagnostic device, called "Emittance-meter", has been conceived and constructed to perform a detailed study of the emittance compensation process in the SPARC photo-injector and to optimize the RF-gun and the accelerator working point. It consists of a movable emittance measurement system, based on the 1D pepper-pot method, installed between two long bellows with the possibility to scan a region 1.5 m long downstream the RF-gun. The construction of the device was completed in the first part of this year and a series of laboratory tests, to evaluate its performances, were carried out in Spring 2005. At the beginning of the summer the complete system was moved to DESY at Zeuthen to be installed on the Photo Injector Test Facility PITZ. After the commissioning it will used for measurements of the PITZ electron beam in the framework of a collaboration between the SPARC and PITZ Projects aiming on studies and operations with photo injectors.

  16. Theoretical studies of thermionic conversion of solar energy with graphene as emitter and collector

    Science.gov (United States)

    Olawole, Olukunle C.; De, Dilip Kumar

    2018-01-01

    Thermionic energy conversion (TEC) using nanomaterials is an emerging field of research. It is known that graphene can withstand temperatures as high as 4600 K in vacuum, and it has been shown that its work function can be engineered from a high value (for monolayer/bilayer) of 4.6 eV to as low as 0.7 eV. Such attractive electronic properties (e.g., good electrical conductivity and high dielectric constant) make engineered graphene a good candidate as an emitter and collector in a thermionic energy converter for harnessing solar energy efficiently. We have used a modified Richardson-Dushman equation and have adopted a model where the collector temperature could be controlled through heat extraction in a calculated amount and a magnet can be attached on the back surface of the collector for future control of the space-charge effect. Our work shows that the efficiency of solar energy conversion also depends on power density falling on the emitter surface, and that a power conversion efficiency of graphene-based solar TEC as high as 55% can be easily achieved (in the absence of the space-charge effect) through proper choice of work functions, collector temperature, and emissivity of emitter surfaces. Such solar energy conversion would reduce our dependence on silicon solar panels and offers great potential for future renewable energy utilization.

  17. Source brightness and useful beam current of carbon nanotubes and other very small emitters

    International Nuclear Information System (INIS)

    Kruit, P.; Bezuijen, M.; Barth, J.E.

    2006-01-01

    The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters' virtual source size and thus restrict the microscope's performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter ''brightness'' becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed

  18. Study on cell survival, induction of apoptosis and micronucleus formation in SCL-II and RTiV3 cells after exposure to the Auger electron emitter Tc-99m

    International Nuclear Information System (INIS)

    Kadenbach, K.; Kriehuber, R.; Weiss, D.G.

    2003-01-01

    Full text: Cell survival, induction of apoptosis and micronucleus (MN) formation have been investigated in the human squamous cell carcinoma cell line SCL-II and in the rat tracheal cell line RTiV3 after exposure to the Auger electron emitter Tc-99m. Cells were either acutely gamma(Co-60)-irradiated (0.78 Gy/min) or exposed to Tc-99m-Pertechnetate (25-300 MBq/20ml) for 24 h under cell culture conditions and assayed for cell survival (Colony-forming assay), micronucleus formation (Cytochalasin B assay) and the frequency of apoptotic cells (Fluorescence microscopy). Analytical dosimetrical models have been applied to derive the absorbed dose corresponding to the accumulated decays of Tc-99m. Absorbed doses up to 1.3 Gy could be achieved after Tc-99m exposure leading to no significant cell killing in this dose range except at one dose point (0.25 Gy) in SCL-II cells. MN formation was consistently lower when compared to Co-60 irradiated cells and showed a linear dose-response. The apoptotic response in SCL-II cells after Tc-99m exposure was described best by a 3rd order polynomial and increased apoptosis induction could be observed at much lower doses (0.25 Gy) in comparison to the reference radiation (0.8 Gy). The relative biological effectiveness (RBE) has been determined for MN formation and apoptosis induction and was found to be in the range of 0.1- 1.3 for both investigated biological endpoints, depending on which mathematical model for describing the dose-effect curve was used. Up-take experiments revealed an activity concentration ratio cells vs. medium of 1.2 after 16 h up to 24 h of exposure. No increased biological effectiveness of Tc-99m applied as Sodium-Pertechnetate could be observed in the investigated cell lines in comparison to gamma-irradiation. Induction of apoptosis is slightly increased after Tc-99m exposure in SCL-II cells and it has to be further evaluated, if this is due to the emitted Auger-component. A passive up-take mechanism of Tc-99m is

  19. Longitudinal emittance measurement at the ATS

    International Nuclear Information System (INIS)

    Cottingame, W.B.; Cortez, J.H.; Higgins, W.W.; Sander, O.R.; Sandoval, D.P.

    1986-01-01

    With increasing brightness, beam diagnostic techniques requiring interception of the beam become impractical. For H - particle beams, solutions for this problem based on the phenomenon of photodissociation are now being investigated at the Los Alamos National Laboratory accelerator test stand (ATS). A laser can be used to selectively neutralize portions of the beam than can be characterized after the charged particles have been swept away. We have used this technique for measuring longitudinal emittance at the output of the ATS radio-frequency quadrupole

  20. Software Tools for Emittance Measurement and Matching for 12 GeV CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Dennis L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    This paper discusses model-driven setup of the Continuous Electron Beam Accelerator Facility (CEBAF) for the 12GeV era, focusing on qsUtility. qsUtility is a set of software tools created to perform emittance measurements, analyze those measurements, and compute optics corrections based upon the measurements.qsUtility was developed as a toolset to facilitate reducing machine configuration time and reproducibility by way of an accurate accelerator model, and to provide Operations staff with tools to measure and correct machine optics with little or no assistance from optics experts.

  1. On the role of diluted magnetic cobalt-doped ZnO electrodes in efficiency improvement of InGaN light emitters

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hong-Ru; Wang, Shih-Yin [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan (China); Ou, Sin-Liang [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Wuu, Dong-Sing, E-mail: dsw@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan (China); Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2016-07-11

    The 120-nm-thick cobalt-doped ZnO (Co-doped ZnO, CZO) dilute magnetic films deposited by pulsed laser deposition were employed as the n-electrodes for both lateral-type blue (450 nm) and green (520 nm) InGaN light emitters. In comparison to the conventional blue and green emitters, there were 15.9% and 17.7% enhancements in the output power (@350 mA) after fabricating the CZO n-electrode on the n-GaN layer. Observations on the role of CZO n-electrodes in efficiency improvement of InGaN light emitters were performed. Based on the results of Hall measurements, the carrier mobilities were 176 and 141 cm{sup 2}/V s when the electrons passed through the n-GaN and the patterned-CZO/n-GaN, respectively. By incorporating the CZO n-electrode into the InGaN light emitters, the electrons would be scattered because of the collisions between the magnetic atoms and the electrons as the device is driven, leading to the reduction of the electron mobility. Therefore, the excessively large mobility difference between electron and hole carriers occurred in the conventional InGaN light emitter can be efficiently decreased after preparing the CZO n-electrode on the n-GaN layer, resulting in the increment of carrier recombination rate and the improvement of light output power.

  2. Sources of Emittance in RF Photocathode Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-12-11

    Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of the electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.

  3. Emittance growth due to noise and its suppression with the Feedback system in large hadron colliders

    International Nuclear Information System (INIS)

    Lebedev, V.; Parkhomchuk, V.; Shiltsev, V.; Stupakov, G.

    1993-03-01

    The problem of emittance growth due to random fluctuation of the magnetic field in hadron colliders is considered. Based on a simple one-dimensional linear model, a formula for an emittance growth rate as a function of the noise spectrum is derived. Different sources of the noise are analyzed and their role is estimated for the Superconducting Super Collider (SSC). A theory of feedback suppression of the emittance growth is developed which predicts the residual growth of the emittance in the accelerator with a feedback system

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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.

  5. Charge transport through DNA based electronic barriers

    Science.gov (United States)

    Patil, Sunil R.; Chawda, Vivek; Qi, Jianqing; Anantram, M. P.; Sinha, Niraj

    2018-05-01

    We report charge transport in electronic 'barriers' constructed by sequence engineering in DNA. Considering the ionization potentials of Thymine-Adenine (AT) and Guanine-Cytosine (GC) base pairs, we treat AT as 'barriers'. The effect of DNA conformation (A and B form) on charge transport is also investigated. Particularly, the effect of width of 'barriers' on hole transport is investigated. Density functional theory (DFT) calculations are performed on energy minimized DNA structures to obtain the electronic Hamiltonian. The quantum transport calculations are performed using the Landauer-Buttiker framework. Our main findings are contrary to previous studies. We find that a longer A-DNA with more AT base pairs can conduct better than shorter A-DNA with a smaller number of AT base pairs. We also find that some sequences of A-DNA can conduct better than a corresponding B-DNA with the same sequence. The counterions mediated charge transport and long range interactions are speculated to be responsible for counter-intuitive length and AT content dependence of conductance of A-DNA.

  6. Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Yueh [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Wei-Tse; Chen, Yi-Sheng; Hwu, En-Te; Chang, Chia-Seng; Hwang, Ing-Shouh, E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Hsu, Wei-Hao [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2016-03-15

    In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This work demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.

  7. Electron Beam Diagnostics in Plasmas Based on Electron Beam Ionization

    Science.gov (United States)

    Leonhardt, Darrin; Leal-Quiros, Edbertho; Blackwell, David; Walton, Scott; Murphy, Donald; Fernsler, Richard; Meger, Robert

    2001-10-01

    Over the last few years, electron beam ionization has been shown to be a viable generator of high density plasmas with numerous applications in materials modification. To better understand these plasmas, we have fielded electron beam diagnostics to more clearly understand the propagation of the beam as it travels through the background gas and creates the plasma. These diagnostics vary greatly in sophistication, ranging from differentially pumped systems with energy selective elements to metal 'hockey pucks' covered with thin layers of insulation to electrically isolate the detector from the plasma but pass high energy beam electrons. Most importantly, absolute measurements of spatially resolved beam current densities are measured in a variety of pulsed and continuous beam sources. The energy distribution of the beam current(s) will be further discussed, through experiments incorporating various energy resolving elements such as simple grids and more sophisticated cylindrical lens geometries. The results are compared with other experiments of high energy electron beams through gases and appropriate disparities and caveats will be discussed. Finally, plasma parameters are correlated to the measured beam parameters for a more global picture of electron beam produced plasmas.

  8. A New Design Strategy for Efficient Thermally Activated Delayed Fluorescence Organic Emitters: From Twisted to Planar Structures

    KAUST Repository

    Chen, Xiankai; Tsuchiya, Youichi; Ishikawa, Yuma; Zhong, Cheng; Adachi, Chihaya; Bredas, Jean-Luc

    2017-01-01

    In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually

  9. Alpha particle emitters in medicine

    International Nuclear Information System (INIS)

    Fisher, D.R.

    1989-09-01

    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 ( 211 At) and natural bismuth-212 ( 212 Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ( 223 Ra) 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. Achievement of ultralow emittance coupling in the Australian Synchrotron storage ring

    Directory of Open Access Journals (Sweden)

    R. Dowd

    2011-01-01

    Full Text Available Investigations into producing an electron beam with ultralow vertical emittance have been conducted using the Australian Synchrotron 3 GeV storage ring. A method of tuning the emittance coupling (ϵ_{y}/ϵ_{x} has been developed using a machine model calibrated through the linear optics from closed orbits method. Direct measurements of the beam emittance have not been possible due to diagnostic limitations, however two independent indirect measurements both indicate a vertical emittance of 1.2–1.3 pm rad (ϵ_{y}/ϵ_{x}=0.01%. Other indirect measurements support the validity of these results. This result is the smallest vertical emittance currently achieved in a storage ring.

  11. A novel method to achieve selective emitter for silicon solar cell using low cost pattern-able a-Si thin films as the semi-transparent phosphorus diffusion barrier

    International Nuclear Information System (INIS)

    Chen, Da Ming; Liang, Zong Cun; Zhuang, Lin; Lin, Yang Huan; Shen, Hui

    2012-01-01

    Highlights: ► a-Si thin films as semitransparent phosphorus diffusion barriers for solar cell. ► a-Si thin films on silicon wafers were patterned by the alkaline solution. ► Selective emitter was formed with patterned a-Si as diffusion barrier for solar cell. -- Abstract: Selective emitter for silicon solar cell was realized by employing a-Si thin films as the semi-transparent diffusion barrier. The a-Si thin films with various thicknesses (∼10–40 nm) were deposited by the electron-beam evaporation technique. Emitters with sheet resistances from 37 to 145 Ω/□ were obtained via POCl 3 diffusion process. The thickness of the a-Si diffusion barrier was optimized to be 15 nm for selective emitter in our work. Homemade mask which can dissolve in ethanol was screen-printed on a-Si film to make pattern. The a-Si film was then patterned in KOH solution to form finger-like design. Selective emitter was obtainable with one-step diffusion with patterned a-Si film on. Combinations of sheet resistances for the high-/low-level doped regions of 39.8/112.1, 36.2/88.8, 35.4/73.9 were obtained. These combinations are suitable for screen-printed solar cells. This preparation method of selective emitter based on a-Si diffusion barrier is a promising approach for low cost industrial manufacturing.

  12. International Standardization of Pure Beta Emitters

    International Nuclear Information System (INIS)

    Los Arcos, Jose Maria; Rodriguez, Leonor

    2006-01-01

    The paper describes the traditional methods of standardization of Pure Beta Emitters, their principal characteristics, advantage and drawbacks. It does comparisons between two metrological LSC methods: Triple to double coincidence ratio (TDCR) method and the CIEMAT/NIST method and presents the result obtained with several Key Comparisons serving as practical test of both methods. Both of them represent the siferrit of methods of standardization of pure (and mixed decay) radionuclides. ESIR WG of CCRI(II) is to implement a reference exchange system for the permanent equivalence of β, α and electron capture nuclides, similar to traditional SIR gamma. ESIR project is currently testing a new XAN scintillator and operational tests of the whole system at BIPM are expected by the end of 2006 (test restricted to ESIR NMI members)

  13. Femtosecond and Subfemtosecond X-Ray Pulses from a SASE Based Free-Electron Laser

    Energy Technology Data Exchange (ETDEWEB)

    Emma, P

    2004-03-10

    We propose a novel method to generate femtosecond and sub-femtosecond photon pulses in a free electron laser by selectively spoiling the transverse emittance of the electron beam. Its merits are simplicity and ease of implementation. When the system is applied to the Linac Coherent Light Source, it can provide x-ray pulses the order of 1 femtosecond in duration containing about 1010 transversely coherent photons.

  14. Model based design of electronic throttle control

    Science.gov (United States)

    Cherian, Fenin; Ranjan, Ashish; Bhowmick, Pathikrit; Rammohan, A.

    2017-11-01

    With the advent of torque based Engine Management Systems, the precise control and robust performance of the throttle body becomes a key factor in the overall performance of the vehicle. Electronic Throttle Control provides benefits such as improved air-fuel ratio for improving the vehicle performance and lower exhausts emissions to meet the stringent emission norms. Modern vehicles facilitate various features such as Cruise Control, Traction Control, Electronic Stability Program and Pre-crash systems. These systems require control over engine power without driver intervention, which is not possible with conventional mechanical throttle system. Thus these systems are integrated to function with the electronic throttle control. However, due to inherent non-linearities in the throttle body, the control becomes a difficult task. In order to eliminate the influence of this hysteresis at the initial operation of the butterfly valve, a control to compensate the shortage must be added to the duty required for starting throttle operation when the initial operation is detected. Therefore, a lot of work is being done in this field to incorporate the various nonlinearities to achieve robust control. In our present work, the ETB was tested to verify the working of the system. Calibration of the TPS sensors was carried out in order to acquire accurate throttle opening angle. The response of the calibrated system was then plotted against a step input signal. A linear model of the ETB was prepared using Simulink and its response was compared with the experimental data to find out the initial deviation of the model from the actual system. To reduce this deviation, non-linearities from existing literature were introduced to the system and a response analysis was performed to check the deviation from the actual system. Based on this investigation, an introduction of a new nonlinearity parameter can be used in future to reduce the deviation further making the control of the ETB more

  15. Multiparametric electronic devices based on nuclear tracks

    Energy Technology Data Exchange (ETDEWEB)

    Fink, D. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany)], E-mail: FINK@HMI.DE; Saad, A. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Basic Science Department, Faculty of Science, Al Balqa University, Salt (Jordan); Dhamodaran, S. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); School of Physics, University of Hyderabad, Hyderabad 500 046 (India); Chandra, A. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Fahrner, W.R. [Chair of Electronic Devices, Institute of Electrotechnique, Fernuniversitaet, Hagen (Germany); Hoppe, K. [South Westfalia University of Applied Sciences, Hagen (Germany); Chadderton, L.T. [Institute of Advanced Studies, ANU Canberra, GPO Box 4, ACT (Australia)

    2008-08-15

    An overview is given on a family of novel electronic devices consisting of an insulating layer containing conducting or semiconducting nuclear tracks, deposited on a semiconducting substrate, and connected by at least one back and two surface contacts. Conducting and semiconducting latent tracks may emerge directly from swift heavy ion irradiation. Etched tracks in insulators can be filled with adequate materials to make them conducting or semiconducting. For this purpose metallic or semiconducting nanoclusters were deposited. We have denoted termed these devices made with latent tracks as 'tunable electronic anisotropic material on semiconductor' (TEAMS), if based on latent ion tracks, and as 'tunable electronic material in pores in oxide on semiconductor' (TEMPOS), if based on etched tracks. Depending on the band-to-band transition between tracks and substrate and on the ratio of surface to track conductivity, the current/voltage characteristics of TEAMS and TEMPOS structures can be modified in many different ways leading to tunable resistors, capacitors and diodes. Both devices show negative differential resistances. This should enable tunable tunneldiodes. TEAMS or TEMPOS structures can be controlled by various external physical and/or chemical parameters leading to sensors. It is even possible to combine different input currents and/or external parameters according to AND/OR logics. The currents through a clustered layer on a TEMPOS structure can be described by the Barbasi-Albert model of network theory enabling to calculate a 'radius of influence'r{sub ROI} around each surface contact, beyond which neighboring contacts do not influence each other. The radius of influence can be well below 1{mu}m leading to nanometric TEMPOS structures.

  16. Multiparametric electronic devices based on nuclear tracks

    International Nuclear Information System (INIS)

    Fink, D.; Saad, A.; Dhamodaran, S.; Chandra, A.; Fahrner, W.R.; Hoppe, K.; Chadderton, L.T.

    2008-01-01

    An overview is given on a family of novel electronic devices consisting of an insulating layer containing conducting or semiconducting nuclear tracks, deposited on a semiconducting substrate, and connected by at least one back and two surface contacts. Conducting and semiconducting latent tracks may emerge directly from swift heavy ion irradiation. Etched tracks in insulators can be filled with adequate materials to make them conducting or semiconducting. For this purpose metallic or semiconducting nanoclusters were deposited. We have denoted termed these devices made with latent tracks as 'tunable electronic anisotropic material on semiconductor' (TEAMS), if based on latent ion tracks, and as 'tunable electronic material in pores in oxide on semiconductor' (TEMPOS), if based on etched tracks. Depending on the band-to-band transition between tracks and substrate and on the ratio of surface to track conductivity, the current/voltage characteristics of TEAMS and TEMPOS structures can be modified in many different ways leading to tunable resistors, capacitors and diodes. Both devices show negative differential resistances. This should enable tunable tunneldiodes. TEAMS or TEMPOS structures can be controlled by various external physical and/or chemical parameters leading to sensors. It is even possible to combine different input currents and/or external parameters according to AND/OR logics. The currents through a clustered layer on a TEMPOS structure can be described by the Barbasi-Albert model of network theory enabling to calculate a 'radius of influence'r ROI around each surface contact, beyond which neighboring contacts do not influence each other. The radius of influence can be well below 1μm leading to nanometric TEMPOS structures

  17. Spin orbit torque based electronic neuron

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Abhronil, E-mail: asengup@purdue.edu; Choday, Sri Harsha; Kim, Yusung; Roy, Kaushik [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-04-06

    A device based on current-induced spin-orbit torque (SOT) that functions as an electronic neuron is proposed in this work. The SOT device implements an artificial neuron's thresholding (transfer) function. In the first step of a two-step switching scheme, a charge current places the magnetization of a nano-magnet along the hard-axis, i.e., an unstable point for the magnet. In the second step, the SOT device (neuron) receives a current (from the synapses) which moves the magnetization from the unstable point to one of the two stable states. The polarity of the synaptic current encodes the excitatory and inhibitory nature of the neuron input and determines the final orientation of the magnetization. A resistive crossbar array, functioning as synapses, generates a bipolar current that is a weighted sum of the inputs. The simulation of a two layer feed-forward artificial neural network based on the SOT electronic neuron shows that it consumes ∼3× lower power than a 45 nm digital CMOS implementation, while reaching ∼80% accuracy in the classification of 100 images of handwritten digits from the MNIST dataset.

  18. Spin orbit torque based electronic neuron

    International Nuclear Information System (INIS)

    Sengupta, Abhronil; Choday, Sri Harsha; Kim, Yusung; Roy, Kaushik

    2015-01-01

    A device based on current-induced spin-orbit torque (SOT) that functions as an electronic neuron is proposed in this work. The SOT device implements an artificial neuron's thresholding (transfer) function. In the first step of a two-step switching scheme, a charge current places the magnetization of a nano-magnet along the hard-axis, i.e., an unstable point for the magnet. In the second step, the SOT device (neuron) receives a current (from the synapses) which moves the magnetization from the unstable point to one of the two stable states. The polarity of the synaptic current encodes the excitatory and inhibitory nature of the neuron input and determines the final orientation of the magnetization. A resistive crossbar array, functioning as synapses, generates a bipolar current that is a weighted sum of the inputs. The simulation of a two layer feed-forward artificial neural network based on the SOT electronic neuron shows that it consumes ∼3× lower power than a 45 nm digital CMOS implementation, while reaching ∼80% accuracy in the classification of 100 images of handwritten digits from the MNIST dataset

  19. Electronic technology

    International Nuclear Information System (INIS)

    Kim, Jin Su

    2010-07-01

    This book is composed of five chapters, which introduces electronic technology about understanding of electronic, electronic component, radio, electronic application, communication technology, semiconductor on its basic, free electron and hole, intrinsic semiconductor and semiconductor element, Diode such as PN junction diode, characteristic of junction diode, rectifier circuit and smoothing circuit, transistor on structure of transistor, characteristic of transistor and common emitter circuit, electronic application about electronic equipment, communication technology and education, robot technology and high electronic technology.

  20. Passive emitter location with Doppler frequency and interferometric measurements

    NARCIS (Netherlands)

    Groot, J.S.; Dam, F.A.M.; Theil, A.

    2008-01-01

    Ground based emitters can be located with a receiver installed on an airborne platform. This paper discusses techniques based on Doppler frequency and differential phase measurements (interferometry). Measurements of the first technique are provided, while we discuss and compare the theoretical

  1. Field emission characteristics of a small number of carbon fiber emitters

    Directory of Open Access Journals (Sweden)

    Wilkin W. Tang

    2016-09-01

    Full Text Available This paper reports an experiment that studies the emission characteristics of small number of field emitters. The experiment consists of nine carbon fibers in a square configuration. Experimental results show that the emission characteristics depend strongly on the separation between each emitter, providing evidence of the electric field screening effects. Our results indicate that as the separation between the emitters decreases, the emission current for a given voltage also decreases. The authors compare the experimental results to four carbon fiber emitters in a linear and square configurations as well as to two carbon fiber emitters in a paired array. Voltage-current traces show that the turn-on voltage is always larger for the nine carbon fiber emitters as compared to the two and four emitters in linear configurations, and approximately identical to the four emitters in a square configuration. The observations and analysis reported here, based on Fowler-Nordheim field emission theory, suggest the electric field screening effect depends critically on the number of emitters, the separation between them, and their overall geometric configuration.

  2. Possible operation of the European XFEL with ultra-low emittance beams

    International Nuclear Information System (INIS)

    Brinkmann, R.; Schneidmiller, E.A.; Yurkov, M.V.

    2010-01-01

    Recent successful lasing of the Linac Coherent Light Source (LCLS) in the hard x-ray regime and the experimental demonstration of a possibility to produce low-charge bunches with ultra-small normalized emittance have lead to the discussions on optimistic scenarios of operation of the European XFEL. In this paper we consider new options that make use of low-emittance beams, a relatively high beam energy, tunable-gap undulators, and a multibunch capability of this facility. We study the possibility of operation of a spontaneous radiator (combining two of them, U1 and U2, in one beamline) in the SASE mode in the designed photon energy range 20-90 keV and show that it becomes possible with ultra-low emittance electron beams similar to those generated in LCLS. As an additional attractive option we consider the generation of powerful soft X-ray and VUV radiation by the same electron bunch for pump-probe experiments, making use of recently invented compact afterburner scheme. We also propose a betatron switcher as a simple, cheap, and robust solution for multi-color operation of SASE1 and SASE2 undulators, allowing to generate 2 to 5 X-ray beams of different independent colors from each of these undulators for simultaneous multi-user operation. We describe a scheme for pump-probe experiments, based on a production of two different colors by two closely spaced electron bunches (produced in photoinjector) with the help of a very fast betatron switcher. Finally, we discuss how without significant modifications of the layout the European XFEL can become a unique facility that continuously covers with powerful, coherent radiation a part of the electromagnetic spectrum from far infrared to gamma-rays. (orig.)

  3. 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

  4. 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.)

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

    International Nuclear Information System (INIS)

    Miltchev, V.

    2006-08-01

    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 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.)

  6. En Route: next-generation laser-plasma-based electron accelerators

    International Nuclear Information System (INIS)

    Hidding, Bernhard

    2008-05-01

    Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to ∼50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the ∼80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10 19 W=cm 2 into gas jets. The experimental observations could be explained via ''bubble acceleration'', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations < or similar 5 fs can thus be created, which is at least an order of magnitude shorter than with conventional accelerator technology. In addition, more than one laser pulse fragment can be powerful enough to drive a bubble. Distinct double peaks have been observed in the electron spectra, indicating that two quasimonoenergetic electron bunches separated by only few tens of fs have formed. This is backed up by PIC-Simulations (Particle-in-Cell). These results underline the feasibility of the construction of small table-top accelerators, while at the

  7. Materials Characterization at Utah State University: Facilities and Knowledge-base of Electronic Properties of Materials Applicable to Spacecraft Charging

    Science.gov (United States)

    Dennison, J. R.; Thomson, C. D.; Kite, J.; Zavyalov, V.; Corbridge, Jodie

    2004-01-01

    In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function of incident energy, species and angle, plus investigations of ion-induced electron yields, photoelectron yields, sample charging and dielectric breakdown. Extensive surface science characterization capabilities are also available to fully characterize the samples in situ. Our measurements for a wide array of conducting and insulating spacecraft materials have been incorporated into the SEE Charge Collector Knowledge-base as a Database of Electronic Properties of Materials Applicable to Spacecraft Charging. This Database provides an extensive compilation of electronic properties, together with parameterization of these properties in a format that can be easily used with existing spacecraft charging engineering tools and with next generation plasma, charging, and radiation models. Tabulated properties in the Database include: electron-induced secondary electron yield, backscattered yield and emitted electron spectra; He, Ar and Xe ion-induced electron yields and emitted electron spectra; photoyield and solar emittance spectra; and materials characterization including reflectivity, dielectric constant, resistivity, arcing, optical microscopy images, scanning electron micrographs, scanning tunneling microscopy images, and Auger electron spectra. Further

  8. High efficiency and stable white OLED using a single emitter

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian [Arizona State Univ., Tempe, AZ (United States). School of Mechanical, Aerospace, Chemical and Materials Engineering

    2016-01-18

    The ultimate objective of this project was to demonstrate an efficient and stable white OLED using a single emitter on a planar glass substrate. The focus of the project is on the development of efficient and stable square planar phosphorescent emitters and evaluation of such class of materials in the device settings. Key challenges included improving the emission efficiency of molecular dopants and excimers, controlling emission color of emitters and their excimers, and improving optical and electrical stability of emissive dopants. At the end of this research program, the PI has made enough progress to demonstrate the potential of excimer-based white OLED as a cost-effective solution for WOLED panel in the solid state lighting applications.

  9. Top-down fabrication of plasmonic nanostructures for deterministic coupling to single quantum emitters

    NARCIS (Netherlands)

    Pfaff, W.; Vos, A.; Hanson, R.

    2013-01-01

    Metal nanostructures can be used to harvest and guide the emission of single photon emitters on-chip via surface plasmon polaritons. In order to develop and characterize photonic devices based on emitter-plasmon hybrid structures, a deterministic and scalable fabrication method for such structures

  10. Emittance measurements from the LLUMC proton accelerator

    International Nuclear Information System (INIS)

    Coutrakon, G.; Gillespie, G.H.; Hubbard, J.; Sanders, E.

    2005-01-01

    A new method of calculating beam emittances at the extraction point of a particle accelerator is presented. The technique uses the optimization programs NPSOL and MINOS developed at Stanford University in order to determine the initial values of beam size, divergence and correlation parameters (i.e. beam sigma matrix, σ ij ) that best fit measured beam parameters. These σ ij elements are then used to compute the Twiss parameters α, β, and the phase space area, ε, of the beam at the extraction point. Beam size measurements in X and Y throughout the transport line were input to the optimizer along with the magnetic elements of bends, quads, and drifts. The σ ij parameters were optimized at the accelerator's extraction point by finding the best agreement between these measured beam sizes and those predicted by TRANSPORT. This expands upon a previous study in which a 'trial and error' technique was used instead of the optimizer software, and which yielded similar results. The Particle Beam Optics Laboratory (PBO Lab TM ) program used for this paper integrates particle beam optics and other codes into a single intuitive graphically-based computing environment. This new software provides a seamless interface between the NPSOL and MINOS optimizer and TRANSPORT calculations. The results of these emittance searches are presented here for the eight clinical energies between 70 and 250 MeV currently being used at LLUMC

  11. Narrowband infrared emitters for combat ID

    Science.gov (United States)

    Pralle, Martin U.; Puscasu, Irina; Daly, James; Fallon, Keith; Loges, Peter; Greenwald, Anton; Johnson, Edward

    2007-04-01

    There is a strong desire to create narrowband infrared light sources as personnel beacons for application in infrared Identify Friend or Foe (IFF) systems. This demand has augmented dramatically in recent years with the reports of friendly fire casualties in Afghanistan and Iraq. ICx Photonics' photonic crystal enhanced TM (PCE TM) infrared emitter technology affords the possibility of creating narrowband IR light sources tuned to specific IR wavebands (near 1-2 microns, mid 3-5 microns, and long 8-12 microns) making it the ideal solution for infrared IFF. This technology is based on a metal coated 2D photonic crystal of air holes in a silicon substrate. Upon thermal excitation the photonic crystal modifies the emitted yielding narrowband IR light with center wavelength commensurate with the periodicity of the lattice. We have integrated this technology with microhotplate MEMS devices to yield 15mW IR light sources in the 3-5 micron waveband with wall plug efficiencies in excess of 10%, 2 orders of magnitude more efficient that conventional IR LEDs. We have further extended this technology into the LWIR with a light source that produces 9 mW of 8-12 micron light at an efficiency of 8%. Viewing distances >500 meters were observed with fielded camera technologies, ideal for ground to ground troop identification. When grouped into an emitter panel, the viewing distances were extended to 5 miles, ideal for ground to air identification.

  12. Minimum entropy principle-based solar cell operation without a pn-junction and a thin CdS layer to extract the holes from the emitter

    Science.gov (United States)

    Böer, Karl W.

    2016-10-01

    The solar cell does not use a pn-junction to separate electrons from holes, but uses an undoped CdS layer that is p-type inverted when attached to a p-type collector and collects the holes while rejecting the backflow of electrons and thereby prevents junction leakage. The operation of the solar cell is determined by the minimum entropy principle of the cell and its external circuit that determines the electrochemical potential, i.e., the Fermi-level of the base electrode to the operating (maximum power point) voltage. It leaves the Fermi level of the metal electrode of the CdS unchanged, since CdS does not participate in the photo-emf. All photoelectric actions are generated by the holes excited from the light that causes the shift of the quasi-Fermi levels in the generator and supports the diffusion current in operating conditions. It is responsible for the measured solar maximum power current. The open circuit voltage (Voc) can approach its theoretical limit of the band gap of the collector at 0 K and the cell increases the efficiency at AM1 to 21% for a thin-film CdS/CdTe that is given as an example here. However, a series resistance of the CdS forces a limitation of its thickness to preferably below 200 Å to avoid unnecessary reduction in efficiency or Voc. The operation of the CdS solar cell does not involve heated carriers. It is initiated by the field at the CdS/CdTe interface that exceeds 20 kV/cm that is sufficient to cause extraction of holes by the CdS that is inverted to become p-type. Here a strong doubly charged intrinsic donor can cause a negative differential conductivity that switches-on a high-field domain that is stabilized by the minimum entropy principle and permits an efficient transport of the holes from the CdTe to the base electrode. Experimental results of the band model of CdS/CdTe solar cells are given and show that the conduction bands are connected in the dark, where the electron current must be continuous, and the valence bands are

  13. Conducting polymer based biomolecular electronic devices

    Indian Academy of Sciences (India)

    Conducting polymers; LB films; biosensor microactuators; monolayers. ... have been projected for applications for a wide range of biomolecular electronic devices such as optical, electronic, drug-delivery, memory and biosensing devices.

  14. Emitter/absorber interface of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tao, E-mail: tsong241@gmail.com; Sites, James R. [Physics Department, Colorado State University, Fort Collins, Colorado 80523 (United States); Kanevce, Ana [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2016-06-21

    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 ≤ ΔE{sub C} ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se{sub 2} (CIGS) cells. The basic principle is that positive ΔE{sub C}, 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 (ΔE{sub C} ≥ 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” (ΔE{sub C} < 0 eV) allows high hole concentration in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. Another way to mitigate performance losses due to interface defects is to use a thin and highly doped emitter, which can invert the absorber and form a large hole barrier at the interface. 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. The ΔE{sub C} 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 ΔE{sub C}. These

  15. Flexible and Cellulose-based Organic Electronics

    OpenAIRE

    Edberg, Jesper

    2017-01-01

    Organic electronics is the study of organic materials with electronic functionality and the applications of such materials. In the 1970s, the discovery that polymers can be made electrically conductive led to an explosion within this field which has continued to grow year by year. One of the attractive features of organic electronic materials is their inherent mechanical flexibility, which has led to the development of numerous flexible electronics technologies such as organic light emitting ...

  16. Emittance control in linear colliders

    International Nuclear Information System (INIS)

    Ruth, R.D.

    1991-01-01

    Before completing a realistic design of a next-generation linear collider, the authors must first learn the lessons taught by the first generation, the SLC. Given that, they must make designs fault tolerant by including correction and compensation in the basic design. They must also try to eliminate these faults by improved alignment and stability of components. When these two efforts cross, they have a realistic design. The techniques of generation and control of emittance reviewed here provide a foundation for a design which can obtain the necessary luminosity in a next-generation linear collider

  17. Emittance Growth in the NLCTA First Chicane

    International Nuclear Information System (INIS)

    Sun, Yipeng

    2011-01-01

    In this paper, the emittance growth in the NLCTA (Next Linear Collider Test Accelerator) first chicane region is evaluated by simulation studies. It is demonstrated that the higher order fields of the chicane dipole magnet and the dipole corrector magnet (which is attached on the quadrupoles) are the main contributions for the emittance growth, especially for the case with a large initial emittance (γε 0 = 5 (micro)m for instance). These simulation results agree with the experimental observations.

  18. Production of alpha emitters for therapy

    International Nuclear Information System (INIS)

    Vucina, J.; Orlic, M.; Lukic, D.

    2006-01-01

    The basis for the introduction of alpha emitters into nuclear medical practice are their radiobiological properties. High LET values and short ranges in biological tissues are advantageous in comparison with nowadays most often used beta emitters, primarily 90 Y and 131 I. Given are the most important criteria for the introduction of a given radionuclide in the routine use. Shown are the procedures for the production of the most important alpha emitters 211 At, 212 Bi and 213 Bi. (author)

  19. Emittance measurements by variable quadrupole method

    International Nuclear Information System (INIS)

    Toprek, D.

    2005-01-01

    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.

  20. Achievement of ultra-low emittance beam in the ATF damping ring

    CERN Document Server

    Honda, Y; Araki, S; Bane, Karl Leopold Freitag; Brachmann, A; Frisch, J; Fukuda, M; Hasegawa, K; Hayano, H; Hendrickson, L; Higashi, Y; Higo, T; Hirano, K; Hirose, T; Iida, K; Imai, T; Inoue, Y; Karataev, P; Kubo, K; Kurihara, Y; Kuriki, M; Kuroda, R; Kuroda, S; Luo, X; Matsuda, M; McCormick, D; Muto, T; Nakajima, K; Nelson, J; Nomura, M; Ohashi, A; Okugi, T; Omori, T; Ross, M; Sakai, H; Sakai, I; Sasao, N; Smith, S; Suzuki, T; Takano, M; Takashi, N; Taniguchi, T; Terunuma, N; Toge, N; Turner, J; Urakawa, J; Vogel, V; Wolski, A; Woodley, M; Yamazaki, I; Yamazaki, Y; Yocky, J; Young, A; Zimmermann, Frank

    2003-01-01

    We report on the smallest vertical emittance achieved in single-bunch-mode operation of the ATF. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured is 4 pm in the limit of zero current. It increases by a factor of 1.5 for a bunch intensity of 10^10 electrons. There are no discrepancies between the measured data and the calculations of intra-beam scattering.

  1. The Brookhaven ATF low-emittance beam line

    International Nuclear Information System (INIS)

    Wang, X.J.; Kirk, H.G.

    1991-01-01

    One component of the experimental program at the Brookhaven Accelerator Test Facility (ATF) consists of a class of experiments which will study the acceleration of electrons through micron-size structures which are exposed in coincidence to a 100 GW CO 2 laser beam. These experiments require the development and control of an electron beam with geometric emittances on the order of 10 -10 m-rad and intensities on the order of 10 6 electrons. In this paper, the authors describe the strategies for producing such beams and the effects of higher-order aberrations. Particle tracking results are presented for the final-focus system

  2. The Brookhaven ATF low-emittance beam line

    International Nuclear Information System (INIS)

    Wang, X.J.

    1991-01-01

    One component of the experimental program at the Brookhaven Accelerator Test Facility (ATF) consists of a class of experiments which will study the acceleration of electrons through micron-size structures which are exposed in coincidence to a 100 GW CO 2 laser beam. These experiments require the development and control of an electron beam with geometric emittances on the order of 10 -10 m-rad and intensities on the order of 10 6 electrons. In this paper, we describe the strategies for producing such beams and the effects of high-order aberrations. Particle tracking results are presented for the final-focus system. 9 refs., 6 figs., 2 tabs

  3. Neutron detector with own power supply, with an emitter made of gadolinium foil and two concentric collectors

    International Nuclear Information System (INIS)

    Brixy, H.; Spillekothen, H.G.; Benninghofen, G.; Serafin, N.

    1985-01-01

    The emitter consists of a material with a high absorption crossection for thermal neutrons, particularly gadolinium, and is provided with an auxiliary emitter layer on the inside and/or the outside. This increases the electron yield with suitable dimensions and material. (orig./HP) [de

  4. Minimum emittance in TBA and MBA lattices

    Science.gov (United States)

    Xu, Gang; Peng, Yue-Mei

    2015-03-01

    For reaching a small emittance in a modern light source, triple bend achromats (TBA), theoretical minimum emittance (TME) and even multiple bend achromats (MBA) have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 31/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design.

  5. Minimum emittance in TBA and MBA lattices

    International Nuclear Information System (INIS)

    Xu Gang; Peng Yuemei

    2015-01-01

    For reaching a small emittance in a modern light source, triple bend achromats (TBA), theoretical minimum emittance (TME) and even multiple bend achromats (MBA) have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 3 1/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design. (authors)

  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. Room-temperature deposition of diamond-like carbon field emitter on flexible substrates

    International Nuclear Information System (INIS)

    Chen, H.; Iliev, M.N.; Liu, J.R.; Ma, K.B.; Chu, W.-K.; Badi, N.; Bensaoula, A.; Svedberg, E.B.

    2006-01-01

    Room-temperature fabrication of diamond-like carbon electron field emitters on flexible polyimide substrate is reported. These thin film field emitters are made using an Ar gas cluster ion beam assisted C 6 vapor deposition method. The bond structure of the as-deposited diamond-like carbon film was studied using Raman spectroscopy. The field emission characteristics of the deposited films were also measured. Electron current densities over 15 mA/cm 2 have been recorded under an electrical field of about 65 V/μm. These diamond-like carbon field emitters are easy and inexpensive to fabricate. The results are promising for flexible field-emission fabrication without the need of complex patterning and tip shaping as compared to the Spindt-type field emitters

  8. Normal spectral emittance of Inconel 718 aeronautical alloy coated with yttria stabilized zirconia films

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Campo, L. del [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.es [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Emittance of Inconel 718 coated with plasma sprayed yttria stabilized zirconia. Black-Right-Pointing-Pointer The coating is opaque for {lambda} > 9 {mu}m and semi-transparent for {lambda} < 9 {mu}m. Black-Right-Pointing-Pointer In the semi-transparent region the emittance decreases with coating thickness. Black-Right-Pointing-Pointer 300 {mu}m thick coatings are still semi-transparent. Black-Right-Pointing-Pointer In the opaque region the surface roughness determines the emittance level. - Abstract: Knowledge of the radiative behaviour of the yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) is needed to perform radiative heat transfer calculations in industrial applications. In this paper, normal spectral emittance experimental data of atmospheric plasma sprayed (PS) YSZ films layered on Inconel 718 substrates are shown. The spectral emittance was measured between 2.5 and 22 {mu}m on samples with film thicknesses ranging from 20 to 280 {mu}m. The samples were heated in a controlled environment, and the emittance was measured for several temperatures between 330 and 730 Degree-Sign C. The dependence of the spectral emittance with film thickness, surface roughness and temperature has been studied and compared with the available results for YSZ TBCs obtained by electron-beam physical vapour deposition. The PS-TBC samples show a Christiansen point at {lambda} = 12.8 {mu}m. The films are semi-transparent for {lambda} < 9 {mu}m, and opaque for {lambda} > 9 {mu}m. In the semi-transparent region, the contribution of the radiation emitted by the Inconel 718 substrate to the global emittance of the samples is analysed. In addition, the influence of the roughness in the emittance values in the opaque spectral region is discussed. Finally, the total normal emittance is obtained as a function of the TBC thickness.

  9. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  10. Measurements of Transverse Emittance for RF Photocathode Gun at the PAL

    CERN Document Server

    Park Jang Ho; Park, Sung-Ju; Soo Ko In; Wang, Xijie; Woon Parc, Yong; Xiang, Dao

    2005-01-01

    A BNL GUN-IV type RF photo-cathode gun is under fabrication for use in the FIR (Far Infra-Red) facility being built at the Pohang Accelerator Laboratory (PAL). Performance test of the gun will include the measurement of transverse emittance profile along the longitudinal direction. Successful measurement of the emittance profile will provide powerful tool for the commissioning of the 4GLS (4th generation light source) injectors based on the emittance compensation principle. We are going to achieve this withthe use of pepper-pot based emittance meters that can be moved along the longitudinal direction. In this article, we present design considerations on the emittance meter with the resolution of 1 mm mrad.

  11. Field emission electronics

    CERN Document Server

    Egorov, Nikolay

    2017-01-01

    This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.

  12. Emittance control in linear colliders

    International Nuclear Information System (INIS)

    Ruth, R.D.

    1991-05-01

    In this paper, we discuss the generation and control of the emittance in a next-generation linear collider. The beams are extracted from a damping ring and compressed in length by the first bunch compressor. They are then accelerated in a preaccelerator linac up to an energy appropriate for injection into a high gradient linac. In many designs this pre-acceleration is followed by another bunch compression to reach a short bunch. After acceleration in the linac, the bunches are finally focused transversely to a small spot. The proposed vertical beam sizes at the interaction point are the order of a few nanometers while the horizontal sizes are about a factor of 100 larger. This cross-sectional area is about a factor of 10 4 smaller than the SLC. However, the main question is: what are the tolerances to achieve such a small size, and how do they compare to present techniques for alignment and stability? These tolerances are very design dependent. Alignment tolerances in the linac can vary from 1 μm to 100 μm depending upon the basic approach. In this paper we discuss techniques of emittance generation and control which move alignment tolerances to the 100 μm range

  13. On the importance of nonlocal effects on the description of emitter-plasmon coupling

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Wubs, Martijn; Mortensen, N. Asger

    2017-01-01

    Plasmonic nanostructures present several characteristics that make them ideal templates for the modification and control of the emission properties of quantum emitters such as organic molecules, fluorescent dyes and quantum dots. State-of-the-art plasmonic architectures strongly enhance and confine...... dimensions, allowing the design of ultranarrow plasmonic cavities and the precise positioning of emitters inside them. In these situations, however, a description beyond classical electrodynamics is rendered unavoidable, as nonclassical effects such as electron spill-out, tunnelling, and nonlocal screening...

  14. MIS hot electron devices for enhancement of surface reactivity by hot electrons

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar

    A Metal-Insulator-Semiconductor (MIS) based device is developed for investigation of hot electron enhanced chemistry. A model of the device is presented explaining the key concepts of the functionality and the character- istics. The MIS hot electron emitter is fabricated using cleanroom technology...... and the process sequence is described. An Ultra High Vacuum (UHV) setup is modified to facilitate experiments with electron emission from the MIS hot electron emitters and hot electron chemistry. Simulations show the importance of keeping tunnel barrier roughness to an absolute minimum. The tunnel oxide...... to be an important energy loss center for the electrons tunneling through the oxide lowering the emission e±ciency of a factor of 10 for a 1 nm Ti layer thickness. Electron emission is observed under ambient pressure conditions and in up to 2 bars of Ar. 2 bar Ar decrease the emission current by an order...

  15. Two-channel dansyl/tryptophan emitters with a cholic acid bridge as reporters for local hydrophobicity within supramolecular systems based on bile salts.

    Science.gov (United States)

    Gomez-Mendoza, M; Marin, M Luisa; Miranda, Miguel A

    2014-11-14

    The aim of the present work is to develop two-channel emitters to probe local hydrophobicity by means of fluorescence quenching within different biomimetic supramolecular environments. To achieve this goal, the dansyl (Dns) and tryptophan (Trp) fluorophores have been covalently attached to cholic acid (CA) in order to ensure simultaneous incorporation of the two emitting units into the same compartment. In principle, the two fluorophores of the synthesized Dns-CA-Trp probes could either exhibit an orthogonal behavior or display excited state interactions. The fluorescence spectra of 3β-Dns-CA-Trp showed a residual Trp emission band at ca. 350 nm and an enhanced Dns maximum in the 500-550 nm region. This reveals a partial intramolecular energy transfer, which is consistent with the Dns and Trp singlet energies. Thus, the two photoactive units are not orthogonal; nevertheless, 3β-Dns-CA-Trp seems appropriate as a two-channel reporter for the supramolecular systems of interest. Fluorescence quenching of 3β-Dns-CA-Trp by iodide (which remains essentially in bulk water) was examined within sodium cholate, sodium taurocholate, sodium deoxycholate and mixed micelles. Interestingly, a decrease in the emission intensity of the two bands was observed with increasing iodide concentrations. The most remarkable effect was observed for mixed micelles, where the quenching rate constants were one order of magnitude lower than in solution. As anticipated, the quenching efficiency by iodide decreased with increasing hydrophobicity of the microenvironment, a trend that can be correlated with the relative accessibility of the probe to the ionic quencher.

  16. Wire Position Monitoring with FPGA based Electronics

    International Nuclear Information System (INIS)

    Eddy, N.; Lysenko, O.

    2009-01-01

    This fall the first Tesla-style cryomodule cooldown test is being performed at Fermilab. Instrumentation department is preparing the electronics to handle the data from a set of wire position monitors (WPMs). For simulation purposes a prototype pipe with a WMP has been developed and built. The system is based on the measurement of signals induced in pickups by 320 MHz signal carried by a wire through the WPM. The wire is stretched along the pipe with a tensioning load of 9.07 kg. The WPM consists of four 50 (Omega) striplines spaced 90 o apart. FPGA based digitizer scans the WPM and transmits the data to a PC via VME interface. The data acquisition is based on the PC running LabView. In order to increase the accuracy and convenience of the measurements some modifications were required. The first is implementation of an average and decimation filter algorithm in the integrator operation in the FPGA. The second is the development of alternative tool for WPM measurements in the PC. The paper describes how these modifications were performed and test results of a new design. The last cryomodule generation has a single chain of seven WPMs (placed in critical positions: at each end, at the three posts and between the posts) to monitor a cold mass displacement during cooldown. The system was developed in Italy in collaboration with DESY. Similar developments have taken place at Fermilab in the frame of cryomodules construction for SCRF research. This fall preliminary cryomodule cooldown test is being performed. In order to prepare an appropriate electronic system for the test a prototype pipe with a WMP has been developed and built, figure 1. The system is based on the measurement of signals induced in pickups by 320 MHz signal carried by a wire through the WPM. The 0.5 mm diameter Cu wire is stretched along the pipe with a tensioning load of 9.07 kg and has a length of 1.1 m. The WPM consists of four 50 (Omega) striplines spaced 90 o apart. An FPGA based digitizer

  17. Electronic structure of hybrid interfaces for polymer-based electronics

    International Nuclear Information System (INIS)

    Fahlman, M; Crispin, A; Crispin, X; Henze, S K M; Jong, M P de; Osikowicz, W; Tengstedt, C; Salaneck, W R

    2007-01-01

    The fundamentals of the energy level alignment at anode and cathode electrodes in organic electronics are described. We focus on two different models that treat weakly interacting organic/metal (and organic/organic) interfaces: the induced density of interfacial states model and the so-called integer charge transfer model. The two models are compared and evaluated, mainly using photoelectron spectroscopy data of the energy level alignment of conjugated polymers and molecules at various organic/metal and organic/organic interfaces. We show that two different alignment regimes are generally observed: (i) vacuum level alignment, which corresponds to the lack of vacuum level offsets (Schottky-Mott limit) and hence the lack of charge transfer across the interface, and (ii) Fermi level pinning where the resulting work function of an organic/metal and organic/organic bilayer is independent of the substrate work function and an interface dipole is formed due to charge transfer across the interface. We argue that the experimental results are best described by the integer charge transfer model which predicts the vacuum level alignment when the substrate work function is above the positive charge transfer level and below the negative charge transfer level of the conjugated material. The model further predicts Fermi level pinning to the positive (negative) charge transfer level when the substrate work function is below (above) the positive (negative) charge transfer level. The nature of the integer charge transfer levels depend on the materials system: for conjugated large molecules and polymers, the integer charge transfer states are polarons or bipolarons; for small molecules' highest occupied and lowest unoccupied molecular orbitals and for crystalline systems, the relevant levels are the valence and conduction band edges. Finally, limits and further improvements to the integer charge transfer model are discussed as well as the impact on device design. (topical review)

  18. Hafnium carbide nanocrystal chains for field emitters

    International Nuclear Information System (INIS)

    Tian, Song; Li, Hejun; Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang

    2014-01-01

    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. Coupling single emitters to quantum plasmonic circuits

    DEFF Research Database (Denmark)

    Huck, Alexander; Andersen, Ulrik Lund

    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 nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters...

  20. Beta-delayed proton emitter $^{113}Xe$

    CERN Document Server

    Hagberg, E; Jonson, B; Jørgensen, B; Kugler, E; Mowinckel, T

    1973-01-01

    The ISOLDE facility at the CERN synchrocyclotron has been used for extending the series of beta -delayed proton emitters in xenon to masses lighter than those previously observed (/sup 115,117/Xe). Owing to the rapid decrease of the yields, experiments with solid-state counters were inconclusive, and instead a new and much more sensitive method based on nuclear emulsions was developed. The mass range 111-114 showed one new activity, /sup 113/Xe, with a half-life of 2.8+or-0.2 sec. From measurements of the track lengths for a total of 1130 protons from /sup 113/Xe it was possible to determine the energy spectrum. The results extend the systematics of beta -strength functions in the light xenon isotopes. (19 refs).

  1. Development and characterization of a rare earth emitter for a thermophotovoltaic power generator

    Energy Technology Data Exchange (ETDEWEB)

    Durisch, W; Panitz, J C [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Energy conversion based on thermophotovoltaic (TPV) methods has recently attracted renewed interest. Efforts at PSI are directed towards the development of a modular TPV system based on existing technology to demonstrate the feasibility of this method. Here, we report first results obtained with a prototype TPV generator based upon a modified rare earth emitter, a heat reflecting filter and commercial silicon solar cells. The preparation of the modified emitter is described, and first results of spectroscopic and electrical characterization of the TPV system are presented. The introduction of the modified emitter leads to an efficiency gain of 30-40%. (author) 3 figs., 4 refs.

  2. Electron Source based on Superconducting RF

    Science.gov (United States)

    Xin, Tianmu

    High-bunch-charge photoemission electron-sources operating in a Continuous Wave (CW) mode can provide high peak current as well as the high average current which are required for many advanced applications of accelerators facilities, for example, electron coolers for hadron beams, electron-ion colliders, and Free-Electron Lasers (FELs). Superconducting Radio Frequency (SRF) has many advantages over other electron-injector technologies, especially when it is working in CW mode as it offers higher repetition rate. An 112 MHz SRF electron photo-injector (gun) was developed at Brookhaven National Laboratory (BNL) to produce high-brightness and high-bunch-charge bunches for electron cooling experiments. The gun utilizes a Quarter-Wave Resonator (QWR) geometry for a compact structure and improved electron beam dynamics. The detailed RF design of the cavity, fundamental coupler and cathode stalk are presented in this work. A GPU accelerated code was written to improve the speed of simulation of multipacting, an important hurdle the SRF structure has to overcome in various locations. The injector utilizes high Quantum Efficiency (QE) multi-alkali photocathodes (K2CsSb) for generating electrons. The cathode fabrication system and procedure are also included in the thesis. Beam dynamic simulation of the injector was done with the code ASTRA. To find the optimized parameters of the cavities and beam optics, the author wrote a genetic algorithm Python script to search for the best solution in this high-dimensional parameter space. The gun was successfully commissioned and produced world record bunch charge and average current in an SRF photo-injector.

  3. GaN Based Electronics And Their Applications

    Science.gov (United States)

    Ren, Fan

    2002-03-01

    The Group III-nitrides were initially researched for their promise to fill the void for a blue solid state light emitter. Electronic devices from III-nitrides have been a more recent phenomenon. The thermal conductivity of GaN is three times that of GaAs. For high power or high temperature applications, good thermal conductivity is imperative for heat removal or sustained operation at elevated temperatures. The development of III-N and other wide bandgap technologies for high temperature applications will likely take place at the expense of competing technologies, such as silicon-on-insulator (SOI), at moderate temperatures. At higher temperatures (>300°C), novel devices and components will become possible. The automotive industry will likely be one of the largest markets for such high temperature electronics. One of the most noteworthy advantages for III-N materials over other wide bandgap semiconductors is the availability of AlGaN/GaN and InGaN/GaN heterostructures. A 2-dimensional electron gas (2DEG) has been shown to exist at the AlGaN/GaN interface, and heterostructure field effect transistors (HFETs) from these materials can exhibit 2DEG mobilities approaching 2000 cm2 / V?s at 300K. Power handling capabilities of 12 W/mm appear feasible, and extraordinary large signal performance has already been demonstrated, with a current state-of-the-art of >10W/mm at X-band. In this talk, high speed and high temperature AlGaN/GaN HEMTs as well as MOSHEMTs, high breakdown voltage GaN (>6KV) and AlGaN (9.7 KV) Schottky diodes, and their applications will be presented.

  4. Positron emitter labeled enzyme inhibitors

    International Nuclear Information System (INIS)

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.; Langstrom, B.

    1990-01-01

    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

  5. Emittance compensation with dynamically optimized photoelectron beam profiles

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, J.B. [Department of Physics and Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095 (United States)]. E-mail: rosen@physics.ucla.edu; Cook, A.M. [Department of Physics and Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095 (United States); England, R.J. [Department of Physics and Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095 (United States); Dunning, M. [Department of Physics and Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095 (United States); Anderson, S.G. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Ferrario, Massimo [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionale di Frascati, Via E. Fermi 41, Frascati, Rome (Italy)

    2006-02-01

    Much of the theory and experimentation concerning creation of a high-brightness electron beam from a photocathode, and then applying emittance compensation techniques, assumes that one must strive for a uniform density electron beam, having a cylindrical shape. On the other hand, this shape has large nonlinearities in the space-charge field profiles near the beam's longitudinal extrema. These nonlinearities are known to produce both transverse and longitudinal emittance growth. On the other hand, it has recently been shown by Luiten that by illuminating the cathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most recent photoinjectors. It is seen that the two processes are compatible, with simulations indicating a very high brightness beam can be obtained. The robustness of this scheme to systematic errors is examined. Prospects for experimental tests of this scheme are discussed.

  6. Emittance compensation with dynamically optimized photoelectron beam profiles

    International Nuclear Information System (INIS)

    Rosenzweig, J.B.; Cook, A.M.; England, R.J.; Dunning, M.; Anderson, S.G.; Ferrario, Massimo

    2006-01-01

    Much of the theory and experimentation concerning creation of a high-brightness electron beam from a photocathode, and then applying emittance compensation techniques, assumes that one must strive for a uniform density electron beam, having a cylindrical shape. On the other hand, this shape has large nonlinearities in the space-charge field profiles near the beam's longitudinal extrema. These nonlinearities are known to produce both transverse and longitudinal emittance growth. On the other hand, it has recently been shown by Luiten that by illuminating the cathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most recent photoinjectors. It is seen that the two processes are compatible, with simulations indicating a very high brightness beam can be obtained. The robustness of this scheme to systematic errors is examined. Prospects for experimental tests of this scheme are discussed

  7. Effects of emittance and space-charge in femtosecond bunch compression

    International Nuclear Information System (INIS)

    Kan, K.; Yang, J.; Kondoh, T.; Norizawa, K.; Yoshida, Y.

    2008-01-01

    Ultrashort electron bunches of the order of <100fs are essential for the study of ultrafast reactions and phenomena by means of time-resolved pump-probe experiments. In order to generate such an electron bunch, the effects of emittance, space-charge (SC) and coherent synchrotron radiation (CSR) on the bunch length in a femtosecond magnetic bunch compressor were studied theoretically. It was observed that the bunch length is dominated by the emittance, SC and CSR effects when the electron bunch is compressed into a femtosecond electron bunch. The increases in bunch length due to the transverse emittance, SC and CSR effects in the bunch compressor were 1.7 fs/mm mrad, 107 fs/nC and 72 fs/nC, respectively. Finally, the simulated bunch length was compared with the experimental results.

  8. Plasmonically enhanced hot electron based photovoltaic device.

    Science.gov (United States)

    Atar, Fatih B; Battal, Enes; Aygun, Levent E; Daglar, Bihter; Bayindir, Mehmet; Okyay, Ali K

    2013-03-25

    Hot electron photovoltaics is emerging as a candidate for low cost and ultra thin solar cells. Plasmonic means can be utilized to significantly boost device efficiency. We separately form the tunneling metal-insulator-metal (MIM) junction for electron collection and the plasmon exciting MIM structure on top of each other, which provides high flexibility in plasmonic design and tunneling MIM design separately. We demonstrate close to one order of magnitude enhancement in the short circuit current at the resonance wavelengths.

  9. The effect of dimethyl sulfoxide on the induction of DNA strand breaks in plasmid DNA and colony formation of PC Cl3 mammalian cells by alpha-, beta-, and Auger electron emitters (223)Ra, (188)Re, and (99m)Tc.

    Science.gov (United States)

    Runge, Roswitha; Oehme, Liane; Kotzerke, Jörg; Freudenberg, Robert

    2016-12-01

    DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The severity of DNA damage depends on the physical characteristics of the radiation quality, e.g., the linear energy transfer (LET). There are still contrary findings regarding direct or indirect interactions of high-LET emitters with DNA. Our aim is to determine DNA damage and the effect on cellular survival induced by (223)Ra compared to (188)Re and (99m)Tc modulated by the radical scavenger dimethyl sulfoxide (DMSO). Radioactive solutions of (223)Ra, (188)Re, or (99m)Tc were added to either plasmid DNA or to PC Cl3 cells in the absence or presence of DMSO. Following irradiation, single strand breaks (SSB) and double strand breaks (DSB) in plasmid DNA were analyzed by gel electrophoresis. To determine the radiosensitivity of the rat thyroid cell line (PC Cl3), survival curves were performed using the colony formation assay. Exposure to 120 Gy of (223)Ra, (188)Re, or (99m)Tc leads to maximal yields of SSB (80 %) in plasmid DNA. Irradiation with 540 Gy (223)Ra and 500 Gy (188)Re or (99m)Tc induced 40, 28, and 64 % linear plasmid conformations, respectively. DMSO prevented the SSB and DSB in a similar way for all radionuclides. However, with the α-emitter (223)Ra, a low level of DSB could not be prevented by DMSO. Irradiation of PC Cl3 cells with (223)Ra, (188)Re, and (99m)Tc pre-incubated with DMSO revealed enhanced survival fractions (SF) in comparison to treatment without DMSO. Protection factors (PF) were calculated using the fitted survival curves. These factors are 1.23 ± 0.04, 1.20 ± 0.19, and 1.34 ± 0.05 for (223)Ra, (188)Re, and (99m)Tc, respectively. For (223)Ra, as well as for (188)Re and (99m)Tc, dose-dependent radiation effects were found applicable for plasmid DNA and PC Cl3 cells. The radioprotection by DMSO was in the same range for high- and low-LET emitter. Overall, the results indicate the contribution of mainly indirect radiation

  10. Therapy with high LET Radioisotopes: Can sufficient levels of attractive Auger and alpha emitters be produced to make their use practical?

    International Nuclear Information System (INIS)

    Knapp, F.F. Jr.; Mirzadeh, S.; Stabin, M.; Brill, A.B.

    2005-01-01

    and processing technologies, radiolabeling and intracellular targeting studies, and experimental evaluation of the subsequent therapeutic potential of other Auger emitters is only in its infancy. Examples of Auger-emitters of current interest include indium-111 (A), neodymium-140 (A), platinum-195m (R) and rhodium-103m (R production of ruthenium-103 parent). One Auger-electron emitter of particular interest is platinum-195m, which has been previously available in only low specific activity (approx. 1 mCi/mg). Demonstration of a new indirect production route via decay of reactor-produced iridium-195 indicates that this Auger emitter may now be available in significantly higher specific activity (>70-100 mCi/mg) which will now permit for the first time studies of the therapeutic potential of this Auger emitter. Because of recent success in peptide targeting to membrane-based cellular receptors which are often over-expressed in tumor cells and advances in radiolabeling chemistry and radioisotope production and processing technologies, intracellular targeted therapy with Alpha and Auger emitters has taken on a new dimension. This talk will review the issues associated with the production and processing of several key candidates and the possibility of producing sufficient levels required for sustained research efforts and clinical trials

  11. Flexible, fpga-based electronics for modular robots

    DEFF Research Database (Denmark)

    Brandt, David; Larsen, Jørgen Christian; Christensen, David Johan

    2008-01-01

    In this paper we introduce electronics for the ATRON self-reconfigurable robot based on field programmable gate arrays (FPGAs). The immediate advantage of using FPGAs is that some of the module’s electronics can be moved into the FPGA, thereby the number of components can be reduced. In the case...... the FPGA and therefore integrate task-specific electronics without physically changing the electronics or we can reconfigure the electronics for specific tasks. The disadvantages of an FPGA-based design include the cost of FPGAs, the extra layer of complexity in programming, and a limited increase in power...... consumption compared to micro-controllers. However, overall FPGAs make the electronics of modular robots more flexible and therefore may make them more suitable for real applications. AB - In this paper we introduce electronics for the ATRON self-reconfigurable robot based on field programmable gate arrays...

  12. Schottky’s conjecture, field emitters, and the point charge model

    Directory of Open Access Journals (Sweden)

    Kevin L. Jensen

    2016-06-01

    Full Text Available A Point Charge Model of conical field emitters, in which the emitter is defined by an equipotential surface of judiciously placed charges over a planar conductor, is used to confirm Schottky’s conjecture that field enhancement factors are multiplicative for a small protrusion placed on top of a larger base structure. Importantly, it is shown that Schottky’s conjecture for conical / ellipsoidal field emitters remains unexpectedly valid even when the dimensions of the protrusion begin to approach the dimensions of the base structure. The model is analytic and therefore the methodology is extensible to other configurations.

  13. Emittance studies of the 2.45 GHz permanent magnet ECR ion source

    Science.gov (United States)

    Zelenak, A.; Bogomolov, S. L.; Yazvitsky, N. Yu.

    2004-05-01

    During the past several years different types of permanent magnet 2.45 GHz (electron cyclotron resonance) ion sources were developed for production of singly charged ions. Ion sources of this type are used in the first stage of DRIBs project, and are planned to be used in the MASHA mass separator. The emittance of the beam provided by the source is one of the important parameters for these applications. An emittance scanner composed from a set of parallel slits and rotary wire beam profile monitor was used for the studying of the beam emittance characteristics. The emittance of helium and argon ion beams was measured with different shapes of the plasma electrode for several ion source parameters: microwave power, source potential, plasma aperture-puller aperture gap distance, gas pressure. The results of measurements are compared with previous simulations of ion optics.

  14. Emittance studies of the 2.45 GHz permanent magnet ECR ion source

    International Nuclear Information System (INIS)

    Zelenak, A.; Bogomolov, S.L.; Yazvitsky, N.Yu.

    2004-01-01

    During the past several years different types of permanent magnet 2.45 GHz (electron cyclotron resonance) ion sources were developed for production of singly charged ions. Ion sources of this type are used in the first stage of DRIBs project, and are planned to be used in the MASHA mass separator. The emittance of the beam provided by the source is one of the important parameters for these applications. An emittance scanner composed from a set of parallel slits and rotary wire beam profile monitor was used for the studying of the beam emittance characteristics. The emittance of helium and argon ion beams was measured with different shapes of the plasma electrode for several ion source parameters: microwave power, source potential, plasma aperture-puller aperture gap distance, gas pressure. The results of measurements are compared with previous simulations of ion optics

  15. Triple Layer Antireflection Design Concept for the Front Side of c-Si Heterojunction Solar Cell Based on the Antireflective Effect of nc-3C-SiC:H Emitter Layer

    Directory of Open Access Journals (Sweden)

    Erick Omondi Ateto

    2016-01-01

    Full Text Available We investigated the antireflective (AR effect of hydrogenated nanocrystalline cubic silicon carbide (nc-3C-SiC:H emitter and its application in the triple layer AR design for the front side of silicon heterojunction (SHJ solar cell. We found that the nc-3C-SiC:H emitter can serve both as an emitter and antireflective coating for SHJ solar cell, which enables us to realize the triple AR design by adding one additional dielectric layer to normally used SHJ structure with a transparent conductive oxide (TCO and an emitter layer. The optimized SHJ structure with the triple layer AR coating (LiF/ITO/nc-3C-SiC:H exhibit a short circuit current density (Jsc of 38.65 mA/cm2 and lower reflectivity of about 3.42% at wavelength range of 300 nm–1000 nm.

  16. Beam diagnostics using an emittance measurement device

    International Nuclear Information System (INIS)

    Sarstedt, M.; Becker, R.; Klein, H.; Maaser, A.; Mueller, J.; Thomae, R.; Weber, M.

    1995-01-01

    For beam diagnostics aside from Faraday cups for current measurements and analysing magnets for the determination of beam composition and energy the most important tool is an emittance measurement device. With such a system the distribution of the beam particles in phase-space can be determined. This yields information not only on the position of the particles but also on their angle with respect to the beam axis. There are different kinds of emittance measurement devices using either circular holes or slits for separation of part of the beam. The second method (slit-slit measurement), though important for the determination of the rms-emittance, has the disadvantage of integrating over the y- and y'-coordinate (measurement in xx'-plane assumed). This leads to different emittance diagrams than point-point measurements, since in xx'-plane for each two corresponding points of rr'-plane there exists a connecting line. With regard to beam aberrations this makes xx'-emittances harder to interpret. In this paper the two kinds of emittance diagrams are discussed. Additionally the influence of the slit height on the xx'-emittance is considered. The analytical results are compared to experimental measurements in rr'-, rx'- and xx'-phase-space. (orig.)

  17. Emittance damping considerations for TESLA

    International Nuclear Information System (INIS)

    Floettmann, K.; Rossbach, J.

    1993-03-01

    Two schemes are considered to avoid very large damping rings for TESLA. The first (by K.F.) makes use of the linac tunnel to accomodate most of the damping 'ring' structure, which is, in fact, not a ring any more but a long linear structure with two small bends at each of its ends ('dog-bone'). The other scheme (by J.R.) is based on a positron (or electron, respectively) recycling scheme. It makes use of the specific TESLA property, that the full bunch train is much longer (240 km) than the linac length. The spent beams are recycled seven times after interaction, thus reducing the number of bunches to be stored in the damping ring by a factor of eight. Ultimately, this scheme can be used to operate TESLA in a storage ring mode ('storage linac'), with no damping ring at all. Finally, a combination of both schemes is considered. (orig.)

  18. Pseudogap in the Eliashberg approach based on electron-phonon and electron-electron-phonon interaction

    Energy Technology Data Exchange (ETDEWEB)

    Szczesniak, R. [Institute of Physics, Czestochowa University of Technology (Poland); Institute of Physics, Jan Dlugosz University in Czestochowa (Poland); Durajski, A.P.; Duda, A.M. [Institute of Physics, Czestochowa University of Technology (Poland)

    2017-04-15

    The properties of the superconducting and the anomalous normal state were described by using the Eliashberg method. The pairing mechanism was reproduced with the help of the Hamiltonian, which models the electron-phonon and the electron-electron-phonon interaction (EEPh). The set of the Eliashberg equations, which determines the order parameter function (φ), the wave function renormalization factor (Z), and the energy shift function (χ), was derived. It was proven that for the sufficiently large values of the EEPh potential, the doping dependence of the order parameter (φ/Z) has the analogous course to that observed experimentally in cuprates. The energy gap in the electron density of states is induced by Z and χ - the contribution from φ is negligible. The electron density of states possesses the characteristic asymmetric form and the pseudogap is observed above the critical temperature. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Homogeneous Gaussian Profile P+-Type Emitters: Updated Parameters and Metal-Grid Optimization

    Directory of Open Access Journals (Sweden)

    M. Cid

    2002-10-01

    Full Text Available P+-type emitters were optimized keeping the base parameters constant. Updated internal parameters were considered. The surface recombination velocity was considered variable with the surface doping level. Passivated homogeneous emitters were found to have low emitter recombination density and high collection efficiency. A complete structure p+nn+ was analyzed, taking into account optimized shadowing and metal-contacted factors for laboratory cells as function of the surface doping level and the emitter thickness. The base parameters were kept constant to make the emitter characteristics evident. The most efficient P+-type passivated homogeneous emitters, provide efficiencies around 21% for a wide range of emitter sheet resistivity (50 -- 500 omega/ with the surface doping levels Ns=1×10(19 cm-3 and 5×10(19 cm-3. The output electrical parameters were evaluated considering the recently proposed value n i=9.65×10(9 (cm-3. A non-significant increase of 0.1% in the efficiency was obtained, validating all the conclusions obtained in this work, considering n i=1×10(10 cm-3.

  20. Developing a model for application of electronic banking based on electronic trust

    Directory of Open Access Journals (Sweden)

    Amir Hooshang Nazarpoori

    2014-05-01

    Full Text Available This study develops a model for application of electronic banking based on electronic trust among costumers of Day bank in KhoramAbad city. A sample of 150 people was selected based on stratified random sampling. Questionnaires were used for the investigation. Results indicate that technology-based factors, user-based factors, and trust had negative relationships with perceived risk types including financial, functional, personal, and private. Moreover, trust including trust in system and trust in bank had a positive relationship with tendency to use and real application of electronic banking.

  1. Intelligent Variable Emittance Panels Using New, ?True? Solid Electrolyte, Phase I

    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...

  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. Single electron based binary multipliers with overflow detection ...

    African Journals Online (AJOL)

    electron based device. Multipliers with overflow detection based on serial and parallel prefix computation algorithm are elaborately discussed analytically and designed. The overflow detection circuits works in parallel with a simplified multiplier to ...

  4. Modeling of Diamond Field-Emitter-Arrays for high brightness photocathode applications

    Science.gov (United States)

    Kwan, Thomas; Huang, Chengkun; Piryatinski, Andrei; Lewellen, John; Nichols, Kimberly; Choi, Bo; Pavlenko, Vitaly; Shchegolkov, Dmitry; Nguyen, Dinh; Andrews, Heather; Simakov, Evgenya

    2017-10-01

    We propose to employ Diamond Field-Emitter-Arrays (DFEAs) as high-current-density ultra-low-emittance photocathodes for compact laser-driven dielectric accelerators capable of generating ultra-high brightness electron beams for advanced applications. We develop a semi-classical Monte-Carlo photoemission model for DFEAs that includes carriers' transport to the emitter surface and tunneling through the surface under external fields. The model accounts for the electronic structure size quantization affecting the transport and tunneling process within the sharp diamond tips. We compare this first principle model with other field emission models, such as the Child-Langmuir and Murphy-Good models. By further including effects of carrier photoexcitation, we perform simulations of the DFEAs' photoemission quantum yield and the emitted electron beam. Details of the theoretical model and validation against preliminary experimental data will be presented. Work ssupported by LDRD program at LANL.

  5. Graphene-based polymer nanocomposites in electronics

    CERN Document Server

    Sadasivuni, Kishor Kumar; Kim, Jaehwan

    2015-01-01

    This book covers graphene reinforced polymers, which are useful in electronic applications, including electrically conductive thermoplastics composites, thermosets and elastomers. It systematically introduces the reader to fundamental aspects and leads over to actual applications, such as sensor fabrication, electromagnetic interference shielding, optoelectronics, superconductivity, or memory chips. The book also describes dielectric and thermal behaviour of graphene polymer composites - properties which are essential to consider for the fabrication and production of these new electronic materials. The contributions in this book critically discuss the actual questions in the development and applications of graphene polymer composites. It will thus appeal to chemists, physicists, materials scientists as well as nano technologists, who are interested in the properties of graphene polymer composites.

  6. A molecular shift register based on electron transfer

    Science.gov (United States)

    Hopfield, J. J.; Onuchic, Josenelson; Beratan, David N.

    1988-01-01

    An electronic shift-register memory at the molecular level is described. The memory elements are based on a chain of electron-transfer molecules and the information is shifted by photoinduced electron-transfer reactions. This device integrates designed electronic molecules onto a very large scale integrated (silicon microelectronic) substrate, providing an example of a 'molecular electronic device' that could actually be made. The design requirements for such a device and possible synthetic strategies are discussed. Devices along these lines should have lower energy usage and enhanced storage density.

  7. Compressive sensing based algorithms for electronic defence

    CERN Document Server

    Mishra, Amit Kumar

    2017-01-01

    This book details some of the major developments in the implementation of compressive sensing in radio applications for electronic defense and warfare communication use. It provides a comprehensive background to the subject and at the same time describes some novel algorithms. It also investigates application value and performance-related parameters of compressive sensing in scenarios such as direction finding, spectrum monitoring, detection, and classification.

  8. Stretchable and foldable silicon-based electronics

    KAUST Repository

    Cavazos Sepulveda, Adrian Cesar

    2017-03-30

    Flexible and stretchable semiconducting substrates provide the foundation for novel electronic applications. Usually, ultra-thin, flexible but often fragile substrates are used in such applications. Here, we describe flexible, stretchable, and foldable 500-μm-thick bulk mono-crystalline silicon (100) “islands” that are interconnected via extremely compliant 30-μm-thick connectors made of silicon. The thick mono-crystalline segments create a stand-alone silicon array that is capable of bending to a radius of 130 μm. The bending radius of the array does not depend on the overall substrate thickness because the ultra-flexible silicon connectors are patterned. We use fracture propagation to release the islands. Because they allow for three-dimensional monolithic stacking of integrated circuits or other electronics without any through-silicon vias, our mono-crystalline islands can be used as a “more-than-Moore” strategy and to develop wearable electronics that are sufficiently robust to be compatible with flip-chip bonding.

  9. Electronic neutron sensor based on coincidence detection

    International Nuclear Information System (INIS)

    Barelaud, B.; Decossas, J.L.; Mokhtari, F.; Vareille, J.C.

    1996-01-01

    The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of researches were presented. They confirm the relevance of our studies in progress in the C2M team of the University of Limoges. The aim of this work is to realize an individual electronic neutron dosemeter. The device in the progress of being development will operate either as a dosemeter or as ratemeter giving H p (10) and H p (10) either as a spectrometer permitting to characterize the primary neutron beam. (author)

  10. Stretchable and foldable silicon-based electronics

    KAUST Repository

    Cavazos Sepulveda, Adrian Cesar; Diaz Cordero, M. S.; Carreno, Armando Arpys Arevalo; Nassar, Joanna M.; Hussain, Muhammad Mustafa

    2017-01-01

    Flexible and stretchable semiconducting substrates provide the foundation for novel electronic applications. Usually, ultra-thin, flexible but often fragile substrates are used in such applications. Here, we describe flexible, stretchable, and foldable 500-μm-thick bulk mono-crystalline silicon (100) “islands” that are interconnected via extremely compliant 30-μm-thick connectors made of silicon. The thick mono-crystalline segments create a stand-alone silicon array that is capable of bending to a radius of 130 μm. The bending radius of the array does not depend on the overall substrate thickness because the ultra-flexible silicon connectors are patterned. We use fracture propagation to release the islands. Because they allow for three-dimensional monolithic stacking of integrated circuits or other electronics without any through-silicon vias, our mono-crystalline islands can be used as a “more-than-Moore” strategy and to develop wearable electronics that are sufficiently robust to be compatible with flip-chip bonding.

  11. New beam-based and direct magnetic waveform measurements of the BTx.KFA10(20) vertical recombination kickers and induced emittance blow-up simulations at 1.4 and 2 GeV

    CERN Document Server

    Forte, Vincenzo; Borburgh, Jan; Sermeus, Luc; CERN. Geneva. ATS Department

    2018-01-01

    In the framework of the LHC Injectors Upgrade (LIU) project [1], this document summarises a new reconstruction methodology for the measurement of the magnetic waveforms of the vertical re-combination kickers BT1.KFA10, BT4.KFA10 and BT2.KFA20, from data collected during several Machine Development (MD) sessions. The reconstruction has been performed in order to verify the LIU specification of the recombination kickers, which is required for a clean transfer of the longer bunches coming from the PSB after the upgrade. A beam-based methodology was developed to measure the transient magnetics dynamics of the kicker where the bunch length is comparable to the rise and/or fall times. These measurements represent a valuable way to reconstruct the mag-netic waveform of the kickers where removing them to make direct probe measurements is time consuming. A benchmarking of the beam-based measurements with field probe measurements is presented, together with realistic simulations of the vertical emittance blow-up at 1...

  12. 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....

  13. Simple emittance measurement of negative hydrogen ion beam using pepper-pot method

    International Nuclear Information System (INIS)

    Hamabe, M.; Tsumori, K.; Takeiri, Y.; Kaneko, O.; Asano, E.; Kawamoto, T.; Kuroda, T.; Guharay, S.K.

    1997-01-01

    A simple apparatus for emittance measurement using pepper-pot method is developed. The pepper-pot patterns are directly exposed and recorded on a Kapton foil. Using this apparatus, emittance was measured in the case of the negative hydrogen (H - ) beam from the large negative ion source, which is the 1/3 scaled test device for the negative-ion-based neutral beam injection (N-NBI) on the Large Helical Device (LHD). As the consequence of the first trial, the 95% normalized emittance value is measured as 0.59 mm mrad. (author)

  14. Limitations of two-level emitters as nonlinearities in two-photon controlled-PHASE gates

    DEFF Research Database (Denmark)

    Nysteen, Anders; McCutcheon, Dara P. S.; Heuck, Mikkel

    2017-01-01

    We investigate the origin of imperfections in the fidelity of a two-photon controlled-PHASE gate based on two-level-emitter nonlinearities. We focus on a passive system that operates without external modulations to enhance its performance. We demonstrate that the fidelity of the gate is limited...... by opposing requirements on the input pulse width for one-and two-photon-scattering events. For one-photon scattering, the spectral pulse width must be narrow compared with the emitter linewidth, while two-photon-scattering processes require the pulse width and emitter linewidth to be comparable. We find...

  15. Simple emittance measurement of negative hydrogen ion beam using pepper-pot method

    Energy Technology Data Exchange (ETDEWEB)

    Hamabe, M.; Tsumori, K.; Takeiri, Y.; Kaneko, O.; Asano, E.; Kawamoto, T.; Kuroda, T. [National Inst. for Fusion Science, Nagoya (Japan); Guharay, S.K.

    1997-02-01

    A simple apparatus for emittance measurement using pepper-pot method is developed. The pepper-pot patterns are directly exposed and recorded on a Kapton foil. Using this apparatus, emittance was measured in the case of the negative hydrogen (H{sup -}) beam from the large negative ion source, which is the 1/3 scaled test device for the negative-ion-based neutral beam injection (N-NBI) on the Large Helical Device (LHD). As the consequence of the first trial, the 95% normalized emittance value is measured as 0.59 mm mrad. (author)

  16. Internal emitter research and standard setting

    International Nuclear Information System (INIS)

    Stannard, J.N.

    1981-01-01

    The history of the use of data from internal emitter research in the derivation of safety standards is reviewed. At first, observed biological effects were correlated with body burdens or exposure levels. This direct approach is illustrated by detailed accounts of the cases of uranium and plutonium. In the 1950's, when it was decided to provide standards for over 200 isotopes, the direct approach was replaced by a system of calculations. This necessitated changes in internal emitter research programs to provide metabolic data, and the development of models such as Reference Man and the Lung and Gastrointestinal Tract models. The continuing contribution of internal emitter research to standard setting can be seen in the references quoted in the metabolic data section of the new ICRP report (ICRP Publication 30). Present trends suggest a possible return to the direct use of internal emitter effects data for obtaining risk estimates. (U.K.)

  17. Beam emittance measurements on multicusp ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Sarstedt, M.; Lee, Y.; Leung, K.N. [and others

    1995-08-01

    Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 {mu}m patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma.

  18. Beam emittance measurements on multicusp ion sources

    International Nuclear Information System (INIS)

    Sarstedt, M.; Lee, Y.; Leung, K.N.

    1995-08-01

    Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 μm patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma

  19. Latest polarization and beam characterization results of the Orsay polarized electron source

    International Nuclear Information System (INIS)

    Arianer, J.; Cohen, S.; Essabaa, S.; Frascaria, R.; Zerhouni, O.

    1995-01-01

    The Orsay polarized electron source based on the chemi-ionization of aligned He(2 3 S 1 ) atoms and CO 2 molecules is briefly described. The latest results concerning electron polarization and beam emittance are presented. The present development status is also discussed. (K.A.)

  20. Neural network based electron identification in the ZEUS calorimeter

    International Nuclear Information System (INIS)

    Abramowicz, H.; Caldwell, A.; Sinkus, R.

    1995-01-01

    We present an electron identification algorithm based on a neural network approach applied to the ZEUS uranium calorimeter. The study is motivated by the need to select deep inelastic, neutral current, electron proton interactions characterized by the presence of a scattered electron in the final state. The performance of the algorithm is compared to an electron identification method based on a classical probabilistic approach. By means of a principle component analysis the improvement in the performance is traced back to the number of variables used in the neural network approach. (orig.)

  1. Self-powered detectors with thulium emitter

    International Nuclear Information System (INIS)

    Haller, P.; Klar, E.

    1978-01-01

    In addition to fission chambers, prompt-indicating self-powered (SPN) detectors are used for measuring the neutron flux density in the core of power reactors. Although current SPN detectors with a cobalt emitter give satisfactora results, detectors with other emitter materials have been analyzed and tested. The author describes the properties and decay pattern of the nuclide thulium and presents the results of measurements made while testing thulium detectors. (orig.) [de

  2. Alpha-emitters for medical therapy workshop

    International Nuclear Information System (INIS)

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

    1996-01-01

    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

  3. 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.

  4. Controlling resonance energy transfer in nanostructure emitters by positioning near a mirror

    Science.gov (United States)

    Weeraddana, Dilusha; Premaratne, Malin; Gunapala, Sarath D.; Andrews, David L.

    2017-08-01

    The ability to control light-matter interactions in quantum objects opens up many avenues for new applications. We look at this issue within a fully quantized framework using a fundamental theory to describe mirror-assisted resonance energy transfer (RET) in nanostructures. The process of RET communicates electronic excitation between suitably disposed donor and acceptor particles in close proximity, activated by the initial excitation of the donor. Here, we demonstrate that the energy transfer rate can be significantly controlled by careful positioning of the RET emitters near a mirror. The results deliver equations that elicit new insights into the associated modification of virtual photon behavior, based on the quantum nature of light. In particular, our results indicate that energy transfer efficiency in nanostructures can be explicitly expedited or suppressed by a suitably positioned neighboring mirror, depending on the relative spacing and the dimensionality of the nanostructure. Interestingly, the resonance energy transfer between emitters is observed to "switch off" abruptly under suitable conditions of the RET system. This allows one to quantitatively control RET systems in a new way.

  5. Electron energy and electron trajectories in an inverse free-electron laser accelerator based on a novel electrostatic wiggler

    Science.gov (United States)

    Nikrah, M.; Jafari, S.

    2016-06-01

    We expand here a theory of a high-gradient laser-excited electron accelerator based on an inverse free-electron laser (inverse-FEL), but with innovations in the structure and design. The electrostatic wiggler used in our scheme, namely termed the Paul wiggler, is generated by segmented cylindrical electrodes with applied oscillatory voltages {{V}\\text{osc}}(t) over {{90}\\circ} segments. The inverse-FEL interaction can be described by the equations that govern the electron motion in the combined fields of both the laser pulse and Paul wiggler field. A numerical study of electron energy and electron trajectories has been made using the fourth-order Runge-Kutta method. The results indicate that the electron attains a considerable energy at short distances in this device. It is found that if the electron has got sufficient suitable wiggler amplitude intensities, it can not only gain higher energy in longer distances, but also can retain it even after the passing of the laser pulse. In addition, the results reveal that the electron energy gains different peaks for different initial axial velocities, so that a suitable small initial axial velocity of e-beam produces substantially high energy gain. With regard to the transverse confinement of the electron beam in a Paul wiggler, there is no applied axial guide magnetic field in this device.

  6. A critical study of emittance measurements of intense low-energy proton beams

    CERN Document Server

    Evans, Lyndon R

    1972-01-01

    The measurement of emittance in low energy proton beams suffers from two perturbing effects: 1) the neutralisation of the beam by backstreaming secondary electrons and 2) the space charge blowup of the beam sample between defining and analysing apparatus. An experimental study shows a significant change of the emittance orientation when bias is used to eliminate the secondary electrons. Biased and non-biased cases are also compared with computed dynamics including space charge. Criteria for the slit size and drift distance which make the space charge blow-up negligible are derived. In addition a transverse coherent oscillation of the proton beam, which was revealed the measurements, is discussed briefly. (11 refs).

  7. Multinozzle emitter arrays for ultrahigh-throughput nanoelectrospray mass spectrometry

    Science.gov (United States)

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

    2017-10-17

    The present invention provides for a structure comprising a plurality of emitters, wherein a first nozzle of a first emitter and a second nozzle of a second emitter emit in two directions that are not or essentially not in the same direction; wherein the walls of the nozzles and the emitters form a monolithic whole. The present invention also provides for a structure comprising an emitter with a sharpened end from which the emitter emits; wherein the emitters forms a monolithic whole. The present invention also provides for a fully integrated separation of proteins and small molecules on a silicon chip before the electrospray mass spectrometry analysis.

  8. Graph-based linear scaling electronic structure theory

    Energy Technology Data Exchange (ETDEWEB)

    Niklasson, Anders M. N., E-mail: amn@lanl.gov; Negre, Christian F. A.; Cawkwell, Marc J.; Swart, Pieter J.; Germann, Timothy C.; Bock, Nicolas [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mniszewski, Susan M.; Mohd-Yusof, Jamal; Wall, Michael E.; Djidjev, Hristo [Computer, Computational, and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rubensson, Emanuel H. [Division of Scientific Computing, Department of Information Technology, Uppsala University, Box 337, SE-751 05 Uppsala (Sweden)

    2016-06-21

    We show how graph theory can be combined with quantum theory to calculate the electronic structure of large complex systems. The graph formalism is general and applicable to a broad range of electronic structure methods and materials, including challenging systems such as biomolecules. The methodology combines well-controlled accuracy, low computational cost, and natural low-communication parallelism. This combination addresses substantial shortcomings of linear scaling electronic structure theory, in particular with respect to quantum-based molecular dynamics simulations.

  9. Strong Coupling and Entanglement of Quantum Emitters Embedded in a Nanoantenna-Enhanced Plasmonic Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Hensen, Matthias [Institut; Heilpern, Tal [Center; Gray, Stephen K. [Center; Pfeiffer, Walter [Fakultät

    2017-10-12

    Establishing strong coupling between spatially separated and thus selectively addressable quantum emitters is a key ingredient to complex quantum optical schemes in future technologies. Insofar as many plasmonic nanostructures are concerned, however, the energy transfer and mutual interaction strength between distant quantum emitters can fail to provide strong coupling. Here, based on mode hybridization, the longevity and waveguide character of an elliptical plasmon cavity are combined with intense and highly localized field modes of suitably designed nanoantennas. Based on FDTD simulations a quantum emitter-plasmon coupling strength hg = 16.7 meV is reached while simultaneously keeping a small plasmon resonance line width h gamma(s) = 33 meV. This facilitates strong coupling, and quantum dynamical simulations reveal an oscillatory exchange of excited state population arid a notable degree of entanglement between the quantum emitters spatially separated by 1.8 mu m, i.e., about twice the operating wavelength.

  10. Direct electron transfer based enzymatic fuel cells

    International Nuclear Information System (INIS)

    Falk, Magnus; Blum, Zoltan; Shleev, Sergey

    2012-01-01

    In this mini-review we briefly describe some historical developments made in the field of enzymatic fuel cells (FCs), discussing important design considerations taken when constructing mediator-, cofactor-, and membrane-less biological FCs (BFCs). Since the topic is rather extensive, only BFCs utilizing direct electron transfer (DET) reactions on both the anodic and cathodic sides are considered. Moreover, the performance of mostly glucose/oxygen biodevices is analyzed and compared. We also present some unpublished results on mediator-, cofactor-, and membrane-less glucose/oxygen BFCs recently designed in our group and tested in different human physiological fluids, such as blood, plasma, saliva, and tears. Finally, further perspectives for BFC applications are highlighted.

  11. Measurements of Thermal Emittance for Cesium Telluride Photocathodes at PITZ

    CERN Document Server

    Miltchev, V; Grabosch, H J; Han, J H; Krasilnikov, M; Oppelt, A; Petrosian, B; Staykov, L; Stephan, F

    2005-01-01

    The thermal emittance determines the lower emittance limit and its measurement is of high importance to understand the ultimate injector performance. In this contribution we present results of thermal emittance measurements under rf operation conditions for various Cs2Te cathodes and different accelerating gradients. Measurements of thermal emittance scaling with the cathode laser spot size are presented and analysed. The significance of the Schottky effect in the emittance formation process is discussed.

  12. NLC electron injector beam dynamics

    International Nuclear Information System (INIS)

    Yeremian, A.D.; Miller, R.H.

    1995-10-01

    The Next Linear Collider (NLC) being designed at SLAC requires a train of 90 electron bunches 1.4 ns apart at 120 Hz. The intensity and emittance required at the interaction point, and the various machine systems between the injector and the IP determine the beam requirements from the injector. The style of injector chosen for the NLC is driven by the fact that the production of polarized electrons at the IP is a must. Based on the successful operation of the SLC polarized electron source a similar type of injector with a DC gun and subharmonic bunching system is chosen for the NLC

  13. Electron guns for accelerators

    International Nuclear Information System (INIS)

    Rangarajan, L.M.; Mahadevan, S.; Ramamurthi, S.S.

    1995-01-01

    The high voltage, high current electron guns developed elsewhere for Linacs are based on cathode pulsing with direct emitting cathodes. Our grid pulsed triode gun employs indirect emitting cathode pellet under electron bombardment or a direct cathode emitter. Electron beam from the gun is injected to the accelerator guide at 40 kV and pulse duration is 2.8μsec. The gun is limited to axially symmetric geometry and electron optical design is optimized by computer programming. The gun with a water cooled Faraday cup is connected to a vacuum system comprising of a sputter ion pump and sorption pump. Working pressure is 1x10 -6 Pa. Gun is designed to be baked as an assembly at temperatures of 400 degC while vacuum processing. Materials are therefore restricted to refractory metals, SS, OFHC copper and all the electrodes are housed inside a ceramic tube. Lower Z graphite is used as a base material of Faraday cup. Grid is non-intercepting modulator anode, a new feature introduced, as compared to meshed grid system by others. CAT gun delivers 160 mA current pulses at 40 kV and its working characteristics such as perveance, emittance and beam radius compare well with SLAC and Hermosa guns. The above guns can be used for electron beam machines such as medical Linacs, industrial accelerators and EB welding equipment. (author). 2 refs., 2 figs

  14. Single-stage unity power factor based electronic ballast

    Indian Academy of Sciences (India)

    This paper deals with the design, modeling, analysis and implementation of unity power factor (UPF) based electronic ballast for a fluorescent lamp (FL). The proposed electronic ballast uses a boost AC–DC converter as a power factor corrector (PFC) to improve the power quality at the input ac mains. In this singlestage ...

  15. Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yunkang [Department of Mathematics and Physics, Nanjing Institute of technology, Nanjing, 211167 (China); Chen, Jing, E-mail: chenjingmoon@gmail.com [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Zichen, E-mail: zz241@ime.ac.cn [Integrated system for Laser applications Group, Institute of Microelectronics of Chinese Academy of Sciences, 100029, Beijing (China)

    2017-02-28

    Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

  16. Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

    International Nuclear Information System (INIS)

    Cui, Yunkang; Chen, Jing; Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong; Zhang, Zichen

    2017-01-01

    Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

  17. Dihydropyrroloindoledione-based copolymers for organic electronics

    NARCIS (Netherlands)

    Rumer, JW; Dai, SY; Levick, M; Young Kim, Young; Madec, MB; Ashraf, R.S.; Huang, Z.; Rossbauer, S; Schroeder, B.; Biniek, L; Watkins, S.E.; Anthopoulos, T.D.; Janssen, R.A.J.; Durrant, J.R.; Procter, DJ; McCulloch, I.

    2013-01-01

    A series of four dihydropyrroloindoledione-based organic semi-conducting polymers are examined for performance in transistor and photovoltaic cell devices. The dihydropyrroloindoledione unit was alternately copolymerized with phenyl, thiophene and bithiophene comonomers, and the resultant polymers

  18. Low emittance lattice optimization using a multi-objective evolutionary algorithm

    International Nuclear Information System (INIS)

    Gao Weiwei; Wang Lin; Li Weimin; He Duohui

    2011-01-01

    A low emittance lattice design and optimization procedure are systematically studied with a non-dominated sorting-based multi-objective evolutionary algorithm which not only globally searches the low emittance lattice, but also optimizes some beam quantities such as betatron tunes, momentum compaction factor and dispersion function simultaneously. In this paper the detailed algorithm and lattice design procedure are presented. The Hefei light source upgrade project storage ring lattice, with fixed magnet layout, is designed to illustrate this optimization procedure. (authors)

  19. Method to evaluate steering and alignment algorithms for controlling emittance growth

    International Nuclear Information System (INIS)

    Adolphsen, C.; Raubenheimer, T.

    1993-04-01

    Future linear colliders will likely use sophisticated beam-based alignment and/or steering algorithms to control the growth of the beam emittance in the linac. In this paper, a mathematical framework is presented which simplifies the evaluation of the effectiveness of these algorithms. As an application, a quad alignment that uses beam data taken with the nominal linac optics, and with a scaled optics, is evaluated in terms of the dispersive emittance growth remaining after alignment

  20. 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.

  1. Emittance preservation during bunch compression with a magnetized beam

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Multicolor light emitters based on energy exchange between Tb and Eu ions co-doped into ultrasmall β-NaYF 4 nanocrystals

    KAUST Repository

    Podhorodecki, Artur P.; Bański, Mateusz; Misiewicz, Jan J.; Afzaal, Mohammad; O'Brien, Paul J.; Cha, Dong Kyu; Wang, Xianbin

    2012-01-01

    based on the experimental results and calculations using Judd-Ofelt theory. It has been shown that efficient energy transfer from Tb to Eu ions accounts for the efficient red emission of NaYF4:Tb,Eu nanocrystals. © The Royal Society of Chemistry 2012.

  3. Work function and surface stability of tungsten-based thermionic electron emission cathodes

    Science.gov (United States)

    Jacobs, Ryan; Morgan, Dane; Booske, John

    2017-11-01

    Materials that exhibit a low work function and therefore easily emit electrons into vacuum form the basis of electronic devices used in applications ranging from satellite communications to thermionic energy conversion. W-Ba-O is the canonical materials system that functions as the thermionic electron emitter commercially used in a range of high-power electron devices. However, the work functions, surface stability, and kinetic characteristics of a polycrystalline W emitter surface are still not well understood or characterized. In this study, we examined the work function and surface stability of the eight lowest index surfaces of the W-Ba-O system using density functional theory methods. We found that under the typical thermionic cathode operating conditions of high temperature and low oxygen partial pressure, the most stable surface adsorbates are Ba-O species with compositions in the range of Ba0.125O-Ba0.25O per surface W atom, with O passivating all dangling W bonds and Ba creating work function-lowering surface dipoles. Wulff construction analysis reveals that the presence of O and Ba significantly alters the surface energetics and changes the proportions of surface facets present under equilibrium conditions. Analysis of previously published data on W sintering kinetics suggests that fine W particles in the size range of 100-500 nm may be at or near equilibrium during cathode synthesis and thus may exhibit surface orientation fractions well described by the calculated Wulff construction.

  4. Preparation of Powdery Carbon Nanotwist and Application to Printed Field Emitter

    Directory of Open Access Journals (Sweden)

    Yuji Hosokawa

    2007-01-01

    Full Text Available In the present study, an automatic production system with sequencer control for the synthesis of carbon nanofibriform based on catalytic CVD using a substrate was developed. The carbon nanotwist (CNTw, which is one of the helical carbon nanofibers, was then synthesized in powdery form with an Ni–SnO2-composed catalyst. The production rate was 5 400 times that of the conventional CVD system and Ni–Cu–In2O3 catalyst. The powdery CNTw was easily scraped off the substrate, then pasted with organic binder, and printed by a squeegee method on ITO glass substrate for an electron field emitter. The field emission performance was found to be better than that of the directly grown CNTw film in conventional CVD with Ni–Cu catalyst.

  5. Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A calibration base line (CBL) is a precisely measured, straight-line course of approximately 1,400 m used to calibrate Electronic Distance Measuring Instruments...

  6. Measurement of X-ray beam emittance using crystal optics at an X-ray undulator beamline

    International Nuclear Information System (INIS)

    Kohmura, Yoshiki; Suzuki, Yoshio; Awaji, Mitsuhiro; Tanaka, Takashi; Hara, Toru; Goto, Shunji; Ishikawa, Tetsuya

    2000-01-01

    We present a method of using crystal optics to measure the emittance of the X-ray source. Two perfect crystals set in (++) configuration work as a high-resolution collimator. The phase-space diagram (i.e. beam cross-section and angular distribution) could be determined without any assumptions on the light source. When the measurement is done at short wavelength radiation from undulator, the electron beam emittance is larger than the diffraction limit of the X-rays. Therefore, the electron beam emittance could be estimated. The measurement was done with the hard X-rays of 18.5 and 55 keV from an undulator beamline, BL 47XU, of SPring-8. The horizontal emittance of the X-ray beam was estimated to be about 7.6 nmrad, close to the designed electron beam emittance of the storage ring (7 nmrad). Some portions of the instrumental functions, such as the scattering by filters and windows along the beamline and the slight bent of the crystal planes of the monochromator, could not be precisely evaluated, but an upper limit for the vertical emittance of the electron beam could be obtained as 0.14 nmrad

  7. A digital miniature x-ray tube with a high-density triode carbon nanotube field emitter

    International Nuclear Information System (INIS)

    Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Kim, Jae-Woo; Song, Yoon-Ho; Ahn, Seungjoon

    2013-01-01

    We have fabricated a digital miniature x-ray tube (6 mm in diameter and 32 mm in length) with a high-density triode carbon nanotube (CNT) field emitter for special x-ray applications. The triode CNT emitter was densely formed within a diameter of below 4 mm with the focusing-functional gate. The brazing process enables us to obtain and maintain a desired vacuum level for the reliable electron emission from the CNT emitters after the vacuum packaging. The miniature x-ray tube exhibited a stable and reliable operation over 250 h in a pulse mode at an anode voltage of above 25 kV.

  8. Characterization of microstructured fibre emitters: in pursuit of improved nano electrospray ionization performance.

    Science.gov (United States)

    Wu, Xinyun; Oleschuk, Richard D; Cann, Natalie M

    2012-09-21

    Full-dimensional computational fluid dynamics (CFD) simulations are presented for nano electrospray ionization (ESI) with various emitter designs. Our CFD electrohydrodynamic simulations are based on the Taylor-Melcher leaky-dielectric model, and the volume of fluid technique for tracking the fast-changing liquid-gas interface. The numerical method is first validated for a conventional 20 μm inner diameter capillary emitter. The impact of ESI voltage, flow rate, emitter tapering, surface hydrophobicity, and fluid conductivity on the nano-ESI behavior are thoroughly investigated and compared with experiments. Multi-electrospray is further simulated with 2-hole and 3-hole emitters with the latter having a linear or triangular hole arrangement. The simulations predict multi-electrospray behavior in good agreement with laboratory observations.

  9. Vertical electron transport in van der Waals heterostructures with graphene layers

    International Nuclear Information System (INIS)

    Ryzhii, V.; Otsuji, T.; Ryzhii, M.; Aleshkin, V. Ya.; Dubinov, A. A.; Mitin, V.; Shur, M. S.

    2015-01-01

    We propose and analyze an analytical model for the self-consistent description of the vertical electron transport in van der Waals graphene-layer (GL) heterostructures with the GLs separated by the barriers layers. The top and bottom GLs serve as the structure emitter and collector. The vertical electron transport in such structures is associated with the propagation of the electrons thermionically emitted from GLs above the inter-GL barriers. The model under consideration describes the processes of the electron thermionic emission from and the electron capture to GLs. It accounts for the nonuniformity of the self-consistent electric field governed by the Poisson equation which accounts for the variation of the electron population in GLs. The model takes also under consideration the cooling of electrons in the emitter layer due to the Peltier effect. We find the spatial distributions of the electric field and potential with the high-electric-field domain near the emitter GL in the GL heterostructures with different numbers of GLs. Using the obtained spatial distributions of the electric field, we calculate the current-voltage characteristics. We demonstrate that the Peltier cooling of the two-dimensional electron gas in the emitter GL can strongly affect the current-voltage characteristics resulting in their saturation. The obtained results can be important for the optimization of the hot-electron bolometric terahertz detectors and different devices based on GL heterostructures

  10. High performance bulk metallic glass/carbon nanotube composite cathodes for electron field emission

    International Nuclear Information System (INIS)

    Hojati-Talemi, Pejman; Gibson, Mark A.; East, Daniel; Simon, George P.

    2011-01-01

    We report the preparation of new nanocomposites based on a combination of bulk metallic glass and carbon nanotubes for electron field emission applications. The use of bulk metallic glass as the matrix ensures high electrical and thermal conductivity, high thermal stability, and ease of processing, whilst the well dispersed carbon nanotubes act as highly efficient electron emitters. These advantages, alongside excellent electron emission properties, make these composites one of the best reported options for electron emission applications to date.

  11. High performance bulk metallic glass/carbon nanotube composite cathodes for electron field emission

    Energy Technology Data Exchange (ETDEWEB)

    Hojati-Talemi, Pejman [Department of Materials Engineering, Monash University, Clayton, Vic 3800 (Australia); Mawson Institute, University of South Australia, Mawson Lakes, SA 5095 (Australia); Gibson, Mark A. [Process Science and Engineering, Commonwealth Scientific and Industrial Research Organisation, Clayton, Vic 3168 (Australia); East, Daniel; Simon, George P. [Department of Materials Engineering, Monash University, Clayton, Vic 3800 (Australia)

    2011-11-07

    We report the preparation of new nanocomposites based on a combination of bulk metallic glass and carbon nanotubes for electron field emission applications. The use of bulk metallic glass as the matrix ensures high electrical and thermal conductivity, high thermal stability, and ease of processing, whilst the well dispersed carbon nanotubes act as highly efficient electron emitters. These advantages, alongside excellent electron emission properties, make these composites one of the best reported options for electron emission applications to date.

  12. Generalized superradiant assembly for nanophotonic thermal emitters

    Science.gov (United States)

    Mallawaarachchi, Sudaraka; Gunapala, Sarath D.; Stockman, Mark I.; Premaratne, Malin

    2018-03-01

    Superradiance explains the collective enhancement of emission, observed when nanophotonic emitters are arranged within subwavelength proximity and perfect symmetry. Thermal superradiant emitter assemblies with variable photon far-field coupling rates are known to be capable of outperforming their conventional, nonsuperradiant counterparts. However, due to the inability to account for assemblies comprising emitters with various materials and dimensional configurations, existing thermal superradiant models are inadequate and incongruent. In this paper, a generalized thermal superradiant assembly for nanophotonic emitters is developed from first principles. Spectral analysis shows that not only does the proposed model outperform existing models in power delivery, but also portrays unforeseen and startling characteristics during emission. These electromagnetically induced transparency like (EIT-like) and superscattering-like characteristics are reported here for a superradiant assembly, and the effects escalate as the emitters become increasingly disparate. The fact that the EIT-like characteristics are in close agreement with a recent experimental observation involving the superradiant decay of qubits strongly bolsters the validity of the proposed model.

  13. Controlled cooling of an electronic system based on projected conditions

    Science.gov (United States)

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2015-08-18

    Energy efficient control of a cooling system cooling an electronic system is provided based, in part, on projected conditions. The control includes automatically determining an adjusted control setting(s) for an adjustable cooling component(s) of the cooling system. The automatically determining is based, at least in part, on projected power consumed by the electronic system at a future time and projected temperature at the future time of a heat sink to which heat extracted is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on an experimentally obtained model(s) relating the targeted temperature and power consumption of the adjustable cooling component(s) of the cooling system.

  14. Multicolor light emitters based on energy exchange between Tb and Eu ions co-doped into ultrasmall β-NaYF 4 nanocrystals

    KAUST Repository

    Podhorodecki, Artur P.

    2012-01-01

    Multicolor emission is reported from ultrasmall (<10 nm) β-NaYF4:Eu,Tb nanocrystals depending on the excitation wavelengths or emission detection delay time. Detailed optical investigations of three samples (NaYF4:Eu, NaYF4:Tb and NaYF4:Eu,Tb) obtained by a co-thermolysis method have been carried out. Photoluminescence, photoluminescence excitation and emission decay time obtained at different excitation wavelengths have been measured. Excitation mechanisms of Eu and Tb ions have been explained based on the experimental results and calculations using Judd-Ofelt theory. It has been shown that efficient energy transfer from Tb to Eu ions accounts for the efficient red emission of NaYF4:Tb,Eu nanocrystals. © The Royal Society of Chemistry 2012.

  15. Sub-bandgap response of graphene/SiC Schottky emitter bipolar phototransistor examined by scanning photocurrent microscopy

    Science.gov (United States)

    Barker, Bobby G., Jr.; Chava, Venkata Surya N.; Daniels, Kevin M.; Chandrashekhar, M. V. S.; Greytak, Andrew B.

    2018-01-01

    Graphene layers grown epitaxially on SiC substrates are attractive for a variety of sensing and optoelectronic applications because the graphene acts as a transparent, conductive, and chemically responsive layer that is mated to a wide-bandgap semiconductor with large breakdown voltage. Recent advances in control of epitaxial growth and doping of SiC epilayers have increased the range of electronic device architectures that are accessible with this system. In particular, a recently-introduced Schottky-emitter bipolar phototransistor (SEPT) based on an epitaxial graphene (EG) emitter grown on a p-SiC base epilayer has been found to exhibit a maximum common emitter current gain of 113 and a UV responsivity of 7.1 A W-1. The behavior of this device, formed on an n +-SiC substrate that serves as the collector, was attributed to a very large minority carrier injection efficiency at the EG/p-SiC Schottky contact. This large minority carrier injection efficiency is in turn related to the large built-in potential found at a EG/p-SiC Schottky junction. The high performance of this device makes it critically important to analyze the sub bandgap visible response of the device, which provides information on impurity states and polytype inclusions in the crystal. Here, we employ scanning photocurrent microscopy (SPCM) with sub-bandgap light as well as a variety of other techniques to clearly demonstrate a localized response based on the graphene transparent electrode and an approximately 1000-fold difference in responsivity between 365 nm and 444 nm excitation. A stacking fault propagating from the substrate/epilayer interface, assigned as a single layer of the 8H-SiC polytype within the 4H-SiC matrix, is found to locally increase the photocurrent substantially. The discovery of this polytype heterojunction opens the potential for further development of heteropolytype devices based on the SEPT architecture.

  16. Femtosecond pulse radiolysis based on photocathode electron accelerator

    International Nuclear Information System (INIS)

    Yoshida, Y.; Yang, Jinfeng; Kondoh, T.; Kozawa, T.; Tagawa, S.

    2006-01-01

    Pulse radiolysis is a powerful tool for studying chemical kinetics and primary processes or reactions of radiation chemistry. In the pulse radiolysis, a short electron beam, which is almost produced by radio-frequency (RF) electron linear accelerator with energy from a few MeV to a few tens MeV, is used as an irradiative source. The electron-induced reactions or phenomena in matter are analyzed by a short-pulse analyzing light (e.g. synchronized lasers) with the time-resolved stroboscopic technique. The time resolution of pulse radiolysis is not only dependent on the electron bunch length, the analyzing light pulse width, the time jitter between the electron bunch and the analyzing light, but also determined by degradation due to the velocity difference between light and the electron in the sample because of the refractive index. In order to improve the time resolution into femtosecond time region, we have develop a new pulse radiolysis based on a concept of 'Equivalent Velocity Spectroscopy (EVS)' to avoid the degradation of the time resolution caused by the velocity difference between the light and the electron beam in sample. In EVS as shown in Fig.1, a femtosecond electron beam produced by a photocathode electron linear accelerator was used, and a synchronized femtosecond laser was used as the analyzing light source. The electron beam and the laser light were injected into sample with an angle (θ), which is determined by the refractive index (n) of the sample. The electron bunch was also rotated with a same angle to make an overlap of the electron bunch with the laser pulse. The degradation of the time resolution caused by the velocity difference between the light and the electron beam can be calculated as g(L)=L[n/c-1/(vcos θ)], where L is the optical path length and v is the velocity of the electron in sample (we can assume v=c for a few tens MeV electron beam).We can thus obtained g(L)=0 by adjusting the incident angle to cos θ=1/n. However, the rotation

  17. Solid-state single-photon emitters

    Science.gov (United States)

    Aharonovich, Igor; Englund, Dirk; Toth, Milos

    2016-10-01

    Single-photon emitters play an important role in many leading quantum technologies. There is still no 'ideal' on-demand single-photon emitter, but a plethora of promising material systems have been developed, and several have transitioned from proof-of-concept to engineering efforts with steadily improving performance. Here, we review recent progress in the race towards true single-photon emitters required for a range of quantum information processing applications. We focus on solid-state systems including quantum dots, defects in solids, two-dimensional hosts and carbon nanotubes, as these are well positioned to benefit from recent breakthroughs in nanofabrication and materials growth techniques. We consider the main challenges and key advantages of each platform, with a focus on scalable on-chip integration and fabrication of identical sources on photonic circuits.

  18. Electron beam characterization of a combined diode rf electron gun

    Directory of Open Access Journals (Sweden)

    R. Ganter

    2010-09-01

    Full Text Available Experimental and simulation results of an electron gun test facility, based on pulsed diode acceleration followed by a two-cell rf cavity at 1.5 GHz, are presented here. The main features of this diode-rf combination are: a high peak gradient in the diode (up to 100  MV/m obtained without breakdown conditioning, a cathode shape providing an electrostatic focusing, and an in-vacuum pulsed solenoid to focus the electron beam between the diode and the rf cavity. Although the test stand was initially developed for testing field emitter arrays cathodes, it became also interesting to explore the limits of this electron gun with metallic photocathodes illuminated by laser pulses. The ultimate goal of this test facility is to fulfill the requirements of the SwissFEL project of Paul Scherrer Institute [B. D. Patterson et al., New J. Phys. 12, 035012 (2010NJOPFM1367-263010.1088/1367-2630/12/3/035012]; a projected normalized emittance below 0.4  μm for a charge of 200 pC and a bunch length of less than 10 ps (rms. A normalized projected emittance of 0.23  μm with 13 pC has been measured at 5 MeV using a Gaussian laser longitudinal intensity distribution on the photocathode. Good agreements with simulations have been obtained for different electron bunch charge and diode geometries. Emittance measurements at a bunch charge below 1 pC were performed for different laser spot sizes in agreement with intrinsic emittance theory [e.g. 0.54  μm/mm of laser spot size (rms for Cu at 274 nm]. Finally, a projected emittance of 1.25+/-0.2  μm was measured with 200 pC and 100  MV/m diode gradient.

  19. Dipolar versus octupolar triphenylamine-based fluorescent organic nanoparticles as brilliant one- and two-photon emitters for (bio)imaging.

    Science.gov (United States)

    Parthasarathy, Venkatakrishnan; Fery-Forgues, Suzanne; Campioli, Elisa; Recher, Gaëlle; Terenziani, Francesca; Blanchard-Desce, Mireille

    2011-11-18

    Two related triphenylamine-based dipolar and octupolar fluorophores are used to prepare aqueous suspensions of fluorescent organic nanoparticles (FONs) via the reprecipitation method. The obtained spherical nanoparticles (30-40 nm in diameter) are fluorescent in aqueous solution (up to 15% fluorescence quantum yield) and exhibit extremely high one- and two-photon brightness, superior to those obtained for quantum dots. Despite the two chromophores showing similar fluorescence in solution, the fluorescence of FONs made from the octupolar derivative is significantly red-shifted compared to that generated by the dipolar FONs. In addition, the maximum two-photon absorption cross section of the FONs made from the octupolar derivative is 55% larger than that of the dipolar derivative FONs. The experimental observations provide evidence that the different molecular shape (rodlike versus three-branched) and charge distribution (dipolar versus octupolar) of the two chromophores strongly affect the packing inside the nanoparticles as well as their spectroscopic properties and colloidal stability in pure water. The use of these FONs as probes for biphotonic in-vivo imaging is investigated on Xenopus laevis tadpoles to test their utilization for angiography. When using FONs made from the octupolar dye, the formation of microagglomerates (2-5 μm scale) is observed in vivo, with subsequent lethal occlusion of the blood vessels. Conversely, the nanoparticles of the dipolar dye allow acute imaging of blood vessels thanks to their suitable size and brightness, while no toxic effect is observed. Such a goal cannot be achieved with the dissolved dye, which permeates the vessel walls. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Beam envelope solution of a finite emittance beam including space charge and acceleration

    International Nuclear Information System (INIS)

    Larson, D.J.; Cole, F.T.; Mills, F.E.

    1985-01-01

    The intermediate-energy electron-cooling effort at the University of Wisconsin began as a collaboration with the University of California - Santa Barbara free electron laser group to measure the emittance of their test device. The measurement indicated that the optics of the FEL test device were extremely good; there was no emittance degradation throughout the system. For this reason, the electron gun for the electron-cooling effort has been designed to be optically identical to the UCSB gun designed by Hermannsfeldt of SLAC. The optics program used to investigate the gun behavior is EGUN, written by Hermannsfeldt. Because of the complicated problem of electron optics at the start of the Pelletron accelerating column, the first 120 kV of acceleration in the Pelletron is included in the gun optical study. At that point in the Pelletron, the electric field no longer has any significant radial component and the following optical treatment of the device is done

  1. MD2065: Emittance exchange with linear coupling

    CERN Document Server

    Carver, Lee Robert; Persson, Tobias Hakan Bjorn; Amorim, David; Levens, Tom; Pesah, Arthur Chalom; CERN. Geneva. ATS Department

    2018-01-01

    In order to better understand the luminosity imbalance between ATLAS and CMS that was observed in 2016, it was proposed to perform a test whereby the horizontal and vertical emittances are exchanged by crossing the tunes in the presence of linear coupling. The luminosity before and after the exchange could be compared to see if the imbalance stems purely from the uneven emittances or if there is an additional mechanism in play. However, due to limited machine availability only tests at injection were able to performed.

  2. Minimum emittance of three-bend achromats

    International Nuclear Information System (INIS)

    Li Xiaoyu; Xu Gang

    2012-01-01

    The calculation of the minimum emittance of three-bend achromats (TBAs) made by Mathematical software can ignore the actual magnets lattice in the matching condition of dispersion function in phase space. The minimum scaling factors of two kinds of widely used TBA lattices are obtained. Then the relationship between the lengths and the radii of the three dipoles in TBA is obtained and so is the minimum scaling factor, when the TBA lattice achieves its minimum emittance. The procedure of analysis and the results can be widely used in achromats lattices, because the calculation is not restricted by the actual lattice. (authors)

  3. 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.

  4. Studies of emittance growth in the ATF

    International Nuclear Information System (INIS)

    Zimmermann, F.

    1997-03-01

    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

  5. Energy Calibration of a Silicon Detector Using Pure Beta-Emitters

    International Nuclear Information System (INIS)

    Borras, C.; Arcos, J. M. los

    1992-01-01

    Energy calibration of SI detectors used in electron spectroscopy 13 commonly performed with conversion electron sources or monoenergetic electrons beams, which are preferred against beta emitters due to the problems arising from their continuous spectra. This paper presents a simple calibration procedure for a PIP-type silicon detector, using 14C, 147Pm, 99 T c and 45Ca sources, that is based on the correspondence between the average channel observed in the experimental spectrum and the mean energy evaluated from the theoretical Fermi distribution for each nuclide. First, a method for evaluating the average channel in the experimental spectrum distorted by the electronic noise is described and its uncertainty estimated. Then, the channel-energy relation ship is established by least squares fitting modified to account for uncertainties in both variables.The calibration has been successfully verified with 147Pm and '09cd sources, showing discrepaneles not greater than 2.5%, within the uncertainties due to the detector resolution and the sources features. (Author)

  6. Energy calibration of a silicon detector using pure beta-emitters

    International Nuclear Information System (INIS)

    Borras, C.; Los Arcos, J.M.

    1992-01-01

    Energy calibration of Si detectors used in electron spectroscopy is commonly performed with conversion electron sources or monoenergetic electrons beams, which are preferred against beta emitters due to the problems arising from their continuous spectra. This paper presents a simple calibration procedure for a PIP-type silicon detector, using 1 4C, 1 47m, 9 9Tc and 4 5Ca, that is based on the correspondence between the average channel observed in the experimental spectrum and the mean energy evaluated from the theoretical Fermi distribution for each nuclide. First, a method for evaluating the average channel in the experimental spectrum distorted by the electronic noise is described and its uncertainty estimated. Then, the channel-energy relation ship is established by least squares fitting modified to account for uncertainties in both variables. The calibration has been successfully verified with 147Pm and 109Cs source, showing discrepancies not greater than 2.5%, within the uncertainties due to the detector resolution and the sources features. (author)

  7. Using electron irradiation to probe iron-based superconductors

    Science.gov (United States)

    Cho, Kyuil; Kończykowski, M.; Teknowijoyo, S.; Tanatar, M. A.; Prozorov, R.

    2018-06-01

    High-energy electron irradiation at low temperatures is an efficient and controlled way to create vacancy–interstitial Frenkel pairs in a crystal lattice, thereby inducing nonmagnetic point-like scattering centers. In combination with London penetration depth and resistivity measurements, the electron irradiation was used as a phase-sensitive probe to study the superconducting order parameter in iron-based superconductors (FeSCs), lending strong support to sign-changing s ± pairing. Here, we review the key results of the effect of electron irradiation in FeSCs.

  8. Secure electronic commerce communication system based on CA

    Science.gov (United States)

    Chen, Deyun; Zhang, Junfeng; Pei, Shujun

    2001-07-01

    In this paper, we introduce the situation of electronic commercial security, then we analyze the working process and security for SSL protocol. At last, we propose a secure electronic commerce communication system based on CA. The system provide secure services such as encryption, integer, peer authentication and non-repudiation for application layer communication software of browser clients' and web server. The system can implement automatic allocation and united management of key through setting up the CA in the network.

  9. RFID-based Electronic Identity Security Cloud Platform in Cyberspace

    OpenAIRE

    Bing Chen; Chengxiang Tan; Bo Jin; Xiang Zou; Yuebo Dai

    2012-01-01

    With the moving development of networks, especially Internet of Things, electronic identity administration in cyberspace is becoming more and more important. And personal identity management in cyberspace associated with individuals in reality has been one significant and urgent task for the further development of information construction in China. So this paper presents a RFID-based electronic identity security cloud platform in cyberspace to implement an efficient security management of cyb...

  10. Vertically aligned carbon nanotube emitter on metal foil for medical X-ray imaging.

    Science.gov (United States)

    Ryu, Je Hwang; Kim, Wan Sun; Lee, Seung Ho; Eom, Young Ju; Park, Hun Kuk; Park, Kyu Chang

    2013-10-01

    A simple method is proposed for growing vertically aligned carbon nanotubes on metal foil using the triode direct current plasma-enhanced chemical vapor deposition (PECVD). The carbon nanotube (CNT) electron emitter was fabricated using fewer process steps with an acid treated metal substrate. The CNT emitter was used for X-ray generation, and the X-ray image of mouse's joint was obtained with an anode current of 0.5 mA at an anode bias of 60 kV. The simple fabrication of a well-aligned CNT with a protection layer on metal foil, and its X-ray application, were studied.

  11. Emittance control of a beam by shaping the transverse charge distribution, using a tomography diagnostic

    International Nuclear Information System (INIS)

    Yakimenko, V.; Babzien, M.; Ben-Zvi, I.; Malone, R.; Wang, X.J.

    1998-06-01

    A high-brightness beam is very important for many applications. A diagnostic that measures the multi-dimensional phase-space density-distribution of the electron bunch is a must for obtaining such beams. Measurement of a slice emittance has been achieved. Tomographic reconstruction of phase space was suggested and implemented using a single quadrupole scan. In the present work the authors give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This diagnostic, coupled with control of the radial charge distribution of presents an opportunity to improve the beam brightness. Combining the slice emittance and tomography diagnostics lead to an unprecedented visualization of phase space distributions in 5 dimensional phase-space and an opportunity to perform high-order emittance corrections

  12. Low Emittance Growth in a LEBT with Un-Neutralized Section

    Energy Technology Data Exchange (ETDEWEB)

    Prost, Lionel [Fermilab; Carneiro, Jean-Paul [Fermilab; Shemyakin, Alexander [Fermilab

    2016-06-01

    In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam's own space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT that contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report discusses the experimental realization of such a scheme at Fermilab's PXIE, where low beam emittance dilution was demonstrated

  13. Emittance growth rates for displaced beams

    International Nuclear Information System (INIS)

    Anderson, O.A.

    1993-05-01

    Emittance growth rates have been previously analyzed for nonuniform beams in linear channels and for initially uniform mismatched beams in nonlinear channels. These studies were for centered beams. Additional emittance growth can arise in cases where the beam is initially displaced. The purpose of this study is to obtain growth rates for displaced beams. This work differs from studies involving random displacement of electrodes. Our analysis assumes instead that the focusing system is perfectly aligned but that the beam is initially displaced with respect to the equilibrium axis. If the focusing force is slightly nonlinear, we find a gradual transfer of the potential energy of beam displacement into kinetic energy associated with emittance growth. We present explicit results for the emittance growth distance as a function of the nonlinearity of the channel. These results will have practical importance for designers of accelerators and transport systems when setting realistic tolerances for initial beam alignment. These tolerances will depend on the nonlinearity and the length of the system

  14. Aluminum oxide film thickness and emittance

    International Nuclear Information System (INIS)

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55 degrees C) moderator for about a year. The average moderator temperature was assumed to be 30 degrees C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 μm ± 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 μm ± 11%. Total hemispherical emittance is predicted to be 0.69 at 96 degrees C, decreasing to 0.45 at 600 degrees C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values

  15. Low Cost Constant – Head Drip Irrigation Emitter for Climate ...

    African Journals Online (AJOL)

    Low Cost Constant – Head Drip Irrigation Emitter for Climate Change Adaptation in Nigeria: Engineering Design and Calibration. ... The drip system comprises of abarrel, sub-main line, lateral lines, tubes and emitters, it can irrigate140 crop ...

  16. Thiazole-based organic semiconductors for organic electronics.

    Science.gov (United States)

    Lin, Yuze; Fan, Haijun; Li, Yongfang; Zhan, Xiaowei

    2012-06-19

    Over the past two decades, organic semiconductors have been the subject of intensive academic and commercial interests. Thiazole is a common electron-accepting heterocycle due to electron-withdrawing nitrogen of imine (C=N), several moieties based on thiazole have been widely introduced into organic semiconductors, and yielded high performance in organic electronic devices. This article reviews recent developments in the area of thiazole-based organic semiconductors, particularly thiazole, bithiazole, thiazolothiazole and benzobisthiazole-based small molecules and polymers, for applications in organic field-effect transistors, solar cells and light-emitting diodes. The remaining problems and challenges, and the key research direction in near future are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The generation and acceleration of low emittance flat beams for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, Tor O. [Stanford Univ., CA (United States)

    1991-11-01

    Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of γϵx = 3x10-6 m-rad and γϵy = 3x10-8 m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both the generation and the subsequent acceleration of such low emittance beams. We consider collective limitations, such as wakefields, space charge effects, scattering processes, and ion trapping; and also how intensity limitations, such as anomalous dispersion, betatron coupling, and pulse-to-pulse beam jitter. In general, the minimum emittance in both the generation and the acceleration stages is limited by the transverse misalignments of the accelerator components. We describe a few techniques of correcting the effect of these errors, thereby easing the alignment tolerances by over an order of magnitude. Finally, we also calculate ``fundamental`` limitations on the minimum vertical emittance; these do not constrain the current designs but may prove important in the future.

  18. The generation and acceleration of low emittance flat beams for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, T.O.

    1991-11-01

    Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of {gamma}{epsilon}{sub x} = 3{times}10{sup {minus}6} m-rad and {gamma}{epsilon}{sub y} = 3{times}10{sup {minus}8} m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both the generation and the subsequent acceleration of such low emittance beams. We consider collective limitations, such as wakefields, space charge effects, scattering processes, and ion trapping; and also how intensity limitations, such as anomalous dispersion, betatron coupling, and pulse-to-pulse beam jitter. In general, the minimum emittance in both the generation and the acceleration stages is limited by the transverse misalignments of the accelerator components. We describe a few techniques of correcting the effect of these errors, thereby easing the alignment tolerances by over an order of magnitude. Finally, we also calculate fundamental'' limitations on the minimum vertical emittance; these do not constrain the current designs but may prove important in the future.

  19. The generation and acceleration of low emittance flat beams for future linear colliders

    International Nuclear Information System (INIS)

    Raubenheimer, T.O.

    1991-11-01

    Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of γε x = 3x10 -6 m-rad and γε y = 3x10 -8 m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both the generation and the subsequent acceleration of such low emittance beams. We consider collective limitations, such as wakefields, space charge effects, scattering processes, and ion trapping; and also how intensity limitations, such as anomalous dispersion, betatron coupling, and pulse-to-pulse beam jitter. In general, the minimum emittance in both the generation and the acceleration stages is limited by the transverse misalignments of the accelerator components. We describe a few techniques of correcting the effect of these errors, thereby easing the alignment tolerances by over an order of magnitude. Finally, we also calculate ''fundamental'' limitations on the minimum vertical emittance; these do not constrain the current designs but may prove important in the future

  20. Arc-textured metal surfaces for high thermal emittance space radiators

    International Nuclear Information System (INIS)

    Banks, B.A.; Rutledge, S.K.; Mirtich, M.J.; Behrend, T.; Hotes, D.; Kussmaul, M.; Barry, J.; Stidham, C.; Stueber, T.; DiFilippo, F.

    1994-01-01

    Carbon arc electrical discharges struck across the surfaces of metals such as Nb-1% Zr, alter the morphology to produce a high thermal emittance surface. Metal from the surface and carbon from the arc electrode vaporize during arcing, and then condense on the metal surface to produce a microscopically rough surface having a high thermal emittance. Quantitative spectral reflectance measurements from 0.33 to 15 μm were made on metal surfaces which were carbon arc treated in an inert gas environment. The resulting spectral reflectance data were then used to calculate thermal emittance as a function of temperature for various methods of arc treatment. The results of arc treatment on various metals are presented for both ac and dc arcs. Surface characterization data, including thermal emittance as a function of temperature, scanning electron microscopy, and atomic oxygen durability, are also presented. Ac arc texturing was found to increase the thermal emittance at 800 K from 0.05. to 0.70

  1. Current-horn suppression for reduced coherent-synchrotron-radiation-induced emittance growth in strong bunch compression

    Directory of Open Access Journals (Sweden)

    T. K. Charles

    2017-03-01

    Full Text Available Control of coherent synchrotron radiation (CSR-induced emittance growth is essential in linear accelerators designed to deliver very high brightness electron beams. Extreme current values at the head and tail of the electron bunch, resulting from strong bunch compression, are responsible for large CSR production leading to significant transverse projected emittance growth. The Linac Coherent Light Source (LCLS truncates the head and tail current spikes which greatly improves free electron laser (FEL performance. Here we consider the underlying dynamics that lead to formation of current spikes (also referred to as current horns, which has been identified as caustics forming in electron trajectories. We present a method to analytically determine conditions required to avoid the caustic formation and therefore prevent the current spikes from forming. These required conditions can be easily met, without increasing the transverse slice emittance, through inclusion of an octupole magnet in the middle of a bunch compressor.

  2. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  3. Test results on two thermionic converters with cermet emitters

    International Nuclear Information System (INIS)

    Saunders, M.; Danielson, L.; Huffman, F.

    1983-01-01

    An emitter made of a directionally solidified Mo-Al 2 O 3 , Cr 2 O 3 eutectic was provided by Eindhoven University of Technology in Eindhoven, The Netherlands. Although the high temperature braze cycle used in bonding this electrode to the emitter substrate destroyed its characteristic needle microstructure, the converter gave good performance. Apparently, chemical species evaporated from the emitter onto the collector provided a low collector work function. The resulting low barrier indices suggest that this surface is a promising emitter

  4. Grid-based electronic structure calculations: The tensor decomposition approach

    Energy Technology Data Exchange (ETDEWEB)

    Rakhuba, M.V., E-mail: rakhuba.m@gmail.com [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Oseledets, I.V., E-mail: i.oseledets@skoltech.ru [Skolkovo Institute of Science and Technology, Novaya St. 100, 143025 Skolkovo, Moscow Region (Russian Federation); Institute of Numerical Mathematics, Russian Academy of Sciences, Gubkina St. 8, 119333 Moscow (Russian Federation)

    2016-05-01

    We present a fully grid-based approach for solving Hartree–Fock and all-electron Kohn–Sham equations based on low-rank approximation of three-dimensional electron orbitals. Due to the low-rank structure the total complexity of the algorithm depends linearly with respect to the one-dimensional grid size. Linear complexity allows for the usage of fine grids, e.g. 8192{sup 3} and, thus, cheap extrapolation procedure. We test the proposed approach on closed-shell atoms up to the argon, several molecules and clusters of hydrogen atoms. All tests show systematical convergence with the required accuracy.

  5. Electronic states of emodin and its conjugate base

    DEFF Research Database (Denmark)

    Nguyen, Son Chi; Hansen, Bjarke Knud Vilster; Hoffmann, Søren Vrønning

    2008-01-01

    The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The e......The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly...

  6. rf streak camera based ultrafast relativistic electron diffraction.

    Science.gov (United States)

    Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Tran, T

    2009-01-01

    We theoretically and experimentally investigate the possibility of using a rf streak camera to time resolve in a single shot structural changes at the sub-100 fs time scale via relativistic electron diffraction. We experimentally tested this novel concept at the UCLA Pegasus rf photoinjector. Time-resolved diffraction patterns from thin Al foil are recorded. Averaging over 50 shots is required in order to get statistics sufficient to uncover a variation in time of the diffraction patterns. In the absence of an external pump laser, this is explained as due to the energy chirp on the beam out of the electron gun. With further improvements to the electron source, rf streak camera based ultrafast electron diffraction has the potential to yield truly single shot measurements of ultrafast processes.

  7. Prediction and design of efficient exciplex emitters for high-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes.

    Science.gov (United States)

    Liu, Xiao-Ke; Chen, Zhan; Zheng, Cai-Jun; Liu, Chuan-Lin; Lee, Chun-Sing; Li, Fan; Ou, Xue-Mei; Zhang, Xiao-Hong

    2015-04-08

    High-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes based on exciplex emitters are demonstrated. The best device, based on a TAPC:DPTPCz emitter, shows a high external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex emitters are also provided. This approach allow prediction and design of efficient exciplex emitters for achieving high-efficiency organic light-emitting diodes, for future use in displays and lighting applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Electronic Biosensors Based on III-Nitride Semiconductors.

    Science.gov (United States)

    Kirste, Ronny; Rohrbaugh, Nathaniel; Bryan, Isaac; Bryan, Zachary; Collazo, Ramon; Ivanisevic, Albena

    2015-01-01

    We review recent advances of AlGaN/GaN high-electron-mobility transistor (HEMT)-based electronic biosensors. We discuss properties and fabrication of III-nitride-based biosensors. Because of their superior biocompatibility and aqueous stability, GaN-based devices are ready to be implemented as next-generation biosensors. We review surface properties, cleaning, and passivation as well as different pathways toward functionalization, and critically analyze III-nitride-based biosensors demonstrated in the literature, including those detecting DNA, bacteria, cancer antibodies, and toxins. We also discuss the high potential of these biosensors for monitoring living cardiac, fibroblast, and nerve cells. Finally, we report on current developments of covalent chemical functionalization of III-nitride devices. Our review concludes with a short outlook on future challenges and projected implementation directions of GaN-based HEMT biosensors.

  9. Design, simulation and construction of quadrupole magnets for focusing electron beam in powerful industrial electron accelerator

    Directory of Open Access Journals (Sweden)

    S KH Mousavi

    2015-09-01

    Full Text Available In this paper the design and simulation of quadrupole magnets and electron beam optical of that by CST Studio code has been studied. Based on simulation result the magnetic quadrupole has been done for using in beam line of first Iranian powerful electron accelerator. For making the suitable magnetic field the effects of material and core geometry and coils current variation on quadrupole magnetic field have been studied. For test of quadrupole magnet the 10 MeV beam energy and 0.5 pi mm mrad emittance of input beam has been considered. We see the electron beam through the quadrupole magnet focus in one side and defocus in other side. The optimum of distance between two quadrupole magnets for low emittance have been achieved. The simulation results have good agreement with experimental results

  10. Longitudinal emittance reduction in LEIR of ion beams for LHC

    CERN Document Server

    Angoletta, M E; Findlay, A; Hancock, S; Manglunki, D

    2014-01-01

    For the 2013 LHC ion run the anticipated request for batches from the PS Complex comprising four ion bunches spaced by 100 ns was changed to batches of two bunches spaced by 200 ns. This modified demand was met by suppressing a splitting step in the PS machine, but with the consequence of halving the longitudinal emittance required from LEIR. Thus NOMINAL Pb54+ beams from LEIR had to be delivered inside ~9 eVs to provide sufficient blow-up margin in the PS. Machine Development (MD) sessions were carried out in LEIR to investigate methods to satisfy these stricter requirements. Two main ingredients were found to reduce longitudinal emittance. The first and most important was to adjust carefully the frequency offset at capture in order to align the RF with the position where the beam is deposited by the electron cooling system prior to acceleration. The second ingredient was to reduce the final bucket area in order to reduce any residual filamentation during capture. This note documents the results obtaine...

  11. Discrete space charge affected field emission: Flat and hemisphere emitters

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Kevin L., E-mail: kevin.jensen@nrl.navy.mil [Code 6854, Naval Research Laboratory, Washington, DC 20375 (United States); Shiffler, Donald A.; Tang, Wilkin [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Rittersdorf, Ian M. [Code 6770, Naval Research Laboratory, Washington, DC 20375 (United States); Lebowitz, Joel L. [Department of Mathematics and Department of Physics, Rutgers University, Piscataway, New Jersey 08854-8019 (United States); Harris, John R. [U.S. Navy Reserve, New Orleans, Louisiana 70143 (United States); Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Petillo, John J. [Leidos, Billerica, Massachusetts 01821 (United States); Luginsland, John W. [Physics and Electronics Directorate, AFOSR, Arlington, Virginia 22203 (United States)

    2015-05-21

    Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surface roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.

  12. Efficient p-phenylene based OLEDs with mixed interfacial exciplex emission

    International Nuclear Information System (INIS)

    Data, P.; Motyka, R.; Lapkowski, M.; Suwinski, J.; Jursenas, S.; Kreiza, G.; Miasojedovas, A.; Monkman, A.P.

    2015-01-01

    Organic electronics, mainly due to the advancement of OLED (Organic Light Emitting Diode) technology, is a fast developing research area, and has already revolutionized the displays market. This direction presents the use of exciplex emitters and thermally activated delayed fluorescence (TADF) in OLEDs. This is shown through electrochemical characterisation of six p-phenylene derivatives for application in optoelectronic devices and presents the possibility the compounds’ use as OLED emitters. In these OLED devices, it is established that selenophene based compounds with a “heavy-atom effect” can be used as potential emitters when exciplex phenomena are involved.

  13. Fullerene-based Anchoring Groups for Molecular Electronics

    DEFF Research Database (Denmark)

    Martin, Christian A.; Ding, Dapeng; Sørensen, Jakob Kryger

    2008-01-01

    We present results on a new fullerene-based anchoring group for molecular electronics. Using lithographic mechanically controllable break junctions in vacuum we have determined the conductance and stability of single-molecule junctions of 1,4-bis(fullero[c]pyrrolidin-1-yl)benzene. The compound can...

  14. Electronic and chemical properties of graphene-based structures:

    DEFF Research Database (Denmark)

    Vanin, Marco

    In the present thesis several aspects of graphene-based structures have been investigated using density functional theory calculations to solve the electronic structure problem. A review of the implementation of a localized basis-set within the projector augmented wave method - the way of describ...... are attractive candidates although issues regarding the poisoning of the active site remain to be addressed....

  15. Towards model-based testing of electronic funds transfer systems

    NARCIS (Netherlands)

    Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.; Arbab, F.; Sirjani, M.

    2012-01-01

    We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the

  16. Towards model-based testing of electronic funds transfer systems

    NARCIS (Netherlands)

    Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.

    2010-01-01

    We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the

  17. Towards Evidence-Based Understanding of Electronic Data Sources

    DEFF Research Database (Denmark)

    Chen, Lianping; Ali Babar, Muhammad; Zhang, He

    2010-01-01

    Identifying relevant papers from various Electronic Data Sources (EDS) is one of the key activities of conducting these kinds of studies. Hence, the selection of EDS for searching the potentially relevant papers is an important decision, which can affect a study’s coverage of relevant papers...... the two studies and that from literature to provide initial evidence-based heuristics for EDS selection....

  18. In plane optical sensor based on organic electronic devices

    NARCIS (Netherlands)

    Koetse, M.M; Rensing, P.A.; Heck, G.T. van; Sharpe, R.B.A.; Allard, B.A.M.; Wieringa, F.P.; Kruijt, P.G.M.; Meulendijks, N.M.M.; Jansen, H.; Schoo, H.F.M.

    2008-01-01

    Sensors based on organic electronic devices are emerging in a wide range of application areas. Here we present a sensor platform using organic light emitting diodes (OLED) and organic photodiodes (OPD) as active components. By means of lamination and interconnection technology the functional foils

  19. S-band linac-based X-ray source with {pi}/2-mode electron linac

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, Abhay, E-mail: abhay@post.kek.jp [Department of Accelerator Science, School of High Energy Accelerator Science, Graduate University for Advanced Studies, Shonan International Village, Hayama, Miura, Kanagawa 240-0193 (Japan); Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Araki, Sakae [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Dixit, Tanuja [Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Fukuda, Masafumi [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Krishnan, R; Pethe, Sanjay [Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Sakaue, Kazuyuki [Waseda University, Shinjuku-ku, Tokyo 169-8555 (Japan); Terunuma, Nobuhiro; Urakawa, Junji [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Washio, Masakazu [Waseda University, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2011-05-01

    The activities with the compact X-ray source are attracting more attention, particularly for the applications of the source in medical fields. We propose the fabrication of a compact X-ray source using the SAMEER electron linear accelerator and the KEK laser undulator X-ray source (LUCX) technologies. The linac developed at SAMEER is a standing wave side-coupled S-band linac operating in the {pi}/2 mode. In the proposed system, a photocathode RF gun will inject bunches of electrons in the linac to accelerate and achieve a high-energy, low-emittance beam. This beam will then interact with the laser in the laser cavity to produce X-rays of a type well suited for various applications. The side-coupled structure will make the system more compact, and the {pi}/2 mode of operation will enable a high repetition rate operation, which will help to increase the X-ray yield.

  20. Alpha-particle detection based on the BJT detector and simple, IC-based readout electronics

    Energy Technology Data Exchange (ETDEWEB)

    Rovati, L; Bonaiuti, M [Dipartimento di Ingegneria dell' Informazione, Universita di Modena e Reggio Emilia, Modena (Italy); Bettarini, S [Dipartimento di Fisica, Universita di Pisa and INFN Pisa, Pisa (Italy); Bosisio, L [Dipartimento di Fisica, Universita di Trieste and INFN Trieste, Trieste (Italy); Dalla Betta, G-F; Tyzhnevyi, V [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento e INFN Trento, Trento (Italy); Verzellesi, G [Dipartimento di Scienze e Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia and INFN Trento, Reggio Emilia (Italy); Zorzi, N, E-mail: giovanni.verzellesi@unimore.i [Fondazione Bruno Kessler (FBK), Trento (Italy)

    2009-11-15

    In this paper we propose a portable instrument for alpha-particle detection based on a previously-developed BJT detector and a simple, IC-based readout electronics. Experimental tests of the BJT detector and readout electronics are reported. Numerical simulations are adopted to predict the performance enhancement achievable with optimized BJT detectors.